WO2020170820A1 - Protection sheet and method for manufacturing glass unit - Google Patents

Abstract

Provided is a protection sheet for a Low-E glass plate that is easily discriminated on an adherend. Provided is a protection sheet for a Low-E glass plate. The protection sheet has a width of 1.5 m or more. Further, the protection sheet has a region, which satisfies at least one of (a) in which minimum transmittance is 90% or less in a wavelength of 450 to 800 nm and (b) in which a haze value is 10 or more, in at least a part of a sheet surface. Further, the protection sheet preferably has a region in which total light transmittance is 3% or more.

Description

Method for manufacturing protective sheet and glass unit

The present invention relates to a protective sheet and a method for manufacturing a glass unit.
This application claims priority based on Japanese Patent Application No. 2019-029737 filed on February 21, 2019, the entire content of which is incorporated herein by reference.

A technique is known in which a protective sheet is adhered to the surface of various articles for the purpose of preventing damage (scratches, stains, corrosion, etc.) on the surfaces when processing or transporting them. The objects of protection are wide-ranging, and for example, a protective sheet is also used for a glass plate with a Low-E (Low-Emissivity) layer that has been widely spread in recent years (Low-E glass plate). The Low-E glass plate is preferably used as a building material such as a window glass because of the effect of improving the cooling and heating efficiency of the indoor space by the Low-E layer. In the manufacture of Low-E glass plates, the Low-E glass plate and other glass plates are usually exposed as they are until the Low-E layer side surface faces inward to form a pair of glasses. A protective sheet is attached to the substrate via the adhesive layer. This protects the Low-E layer from damage, wear, deterioration, corrosion, etc. Patent Documents 1 and 2 are cited as prior art documents disclosing conventional techniques relating to the manufacturing method of the glass unit.

For surface protection, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive. The same applies hereinafter) can be preferably used as a peelable adhesive means. Generally, the pressure-sensitive adhesive is in the state of a soft solid (viscoelastic body) in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure. A surface protective sheet using an adhesive typically has an adhesive layer on one side of a sheet-like base material made of a resin or the like, and the adhesive layer is adhered to an adherend (object to be protected). By doing so, the protection purpose can be achieved. Patent Documents 3 to 6 are mentioned as prior art documents disclosing an adhesive sheet that can be used as a surface protection sheet. Patent Document 3 discloses a surface protection sheet that protects the surface of a metal plate during drawing, and Patent Document 4 discloses a surface protection sheet of an optical film such as a polarizing plate. Patent Document 5 relates to a surface protective sheet of a hydrophilic coated plate having a self-cleaning property. Patent Document 6 addresses the ease of peeling and the reduction of contamination of the surface protection sheet for metal plates on which a coating film is formed.

European Patent No. 2150669 International Publication No. 2016/139318 Japanese Patent Application Publication No. 2017-186517 Japanese Patent No. 5719194 Japanese Patent Application Publication 2012-131976 Japanese Patent No. 3571460

The Low-E glass plate is transported, processed, washed, etc. while being protected by a protective sheet, and during the protection period, there is no foreign matter such as water entering the surface of the object to be protected, Alternatively it can be inspected for defects or damage. Therefore, it is desirable that the Low-E glass sheet protective sheet has transparency so that the object to be protected can be visually recognized through the protective sheet. Further, the protection sheet is removed from the object to be protected at an appropriate timing after the purpose of protection is achieved. However, when the object to be protected is a transparent material such as a glass plate, it is difficult to distinguish between the two if the protective sheet is also transparent, and forgetting to peel off the protective sheet may occur. In particular, glass plates for building materials such as window glass represented by Low-E glass plates are becoming larger in area from the viewpoint of efficiency of production, transportation, etc., and have a width of 1.5 m or more (for example, 2 m or more, further 3 m or more). Some have a size of 0.3 m or more). With such a large-area glass plate, there is a situation in which it is difficult to instantaneously determine the presence or absence of the protective sheet on the surface of the glass plate during the removal work of the protective sheet, because the end of the protective sheet cannot be completely seen.

The present invention was created in view of the above circumstances, it is possible to inspect a Low-E glass plate through a protective sheet, and a Low-E glass plate that is easy to distinguish on a Low-E glass plate. The purpose is to provide a protective sheet for use. Another related object is to provide a method for manufacturing a glass unit using the protective sheet.

According to the present specification, a protection sheet for Low-E glass plate is provided. This protective sheet has a width of 1.5 meters (hereinafter abbreviated as "m") or more. Further, it has a region where the total light transmittance is 3% or more. Furthermore, at least a part of the sheet surface has a region satisfying at least one of (a) a minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) a haze value of 10 or more. According to the above configuration, it is possible to protect a large-area Low-E glass plate with one sheet or a small number of sheets. In addition, since the protective sheet has a region where the total light transmittance is 3% or more, it is possible to inspect the Low-E glass plate through the protective sheet while being attached to the Low-E glass plate. .. For example, when foreign matter such as water is present on the surface of the Low-E glass plate, by reattaching or replacing the protective sheet, it is possible to prevent the occurrence of defects caused by the foreign matter. Further, the protective sheet has a region satisfying at least one of (a) minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) haze value of 10 or more on at least a part of the sheet surface. Since it has a low-E glass plate surface, it is easy to see on the surface of the low-E glass plate, and even when it is used to protect a large-area Low-E glass plate that does not reach the end of the protective sheet, the center of the glass plate The presence or absence of the protective sheet can be determined simply by looking at the part.

In a preferred aspect, the haze value of the region where the total light transmittance is 3% or more is 50 or less. A protective sheet having a region having a haze value of not more than a predetermined value is excellent in transparency and tends to be limited in reflection, and thus is excellent in visibility of an adherend through the protective sheet.

In a preferred embodiment, the minimum transmittance at a wavelength of 450 to 800 nm is 30% or more in the region where the total light transmittance is 3% or more. With such a configuration, the adherend can be easily viewed through the protective sheet.

In a preferred aspect, the entire sheet surface is a region that satisfies at least one of (a) and (b) above. According to the above configuration, it becomes easier to identify the protective sheet.

In a preferred embodiment, the area satisfying at least one of (a) and (b) above is a colored area. By providing the colored area on the sheet surface, it is easy to obtain more excellent protection sheet discrimination.

The protective sheet according to a preferred aspect is almost uniformly colored over the entire sheet surface. According to the above configuration, it becomes easier to identify the protective sheet. For example, even if a part (for example, a small piece) of the protective sheet remains on the adherend due to tearing or the like, it is easy to find and remove.

The protective sheet according to a preferred embodiment is colored blue or green. By configuring in this way, it is possible to obtain sufficient visibility on the Low-E glass plate with a color that is relatively unnoticeable compared to red and yellow, and it is also easy to harmonize with the surrounding environment.

The protective sheet according to a preferred aspect includes a base material layer and an adhesive layer supported by the base material layer. Further, at least one of the base material layer and the pressure-sensitive adhesive layer is colored. With such a configuration, it is possible to preferably realize the effect of the technique disclosed herein.

In a preferred embodiment, the base material layer is made of a resin film containing a colorant. With this structure, it is possible to preferably obtain a structure in which the entire sheet surface is colored almost uniformly.

In one aspect, the pressure-sensitive adhesive layer is at least selected from the group consisting of acrylic polymers, urethane polymers, polyester polymers, polyether polymers, rubber polymers, silicone polymers, polyamide polymers and fluorine polymers. It contains one polymer in a proportion of 50% by weight or more. In the configuration including the pressure-sensitive adhesive layer, the effect of the technique disclosed herein is preferably realized.

Also, according to the present specification, a Low-E glass plate protective sheet according to another aspect is provided. This protective sheet has a width of 1.5 m or more. Further, at least a part of the sheet surface has a region satisfying at least one of (a) the minimum transmittance at a wavelength of 450 to 800 nm is 90% or less; and (b) the haze value is 10 or more. Since the protective sheet has a region satisfying at least one of the above (a) and (b) on at least a part of the sheet surface, the effect of being easily visible on the surface of the Low-E glass plate can be obtained. Even when such a protective sheet is used to protect a large-area Low-E glass plate that does not reach the end of the field of view, just by looking at the center of the glass plate, the presence or absence of the protective sheet Can be determined. In some cases, the transparency for inspecting the Low-E glass plate is not essential depending on the mode of use, and in such a mode, the above configuration is meaningful.

Further, according to the present specification, a method for manufacturing a glass unit is provided. The method comprises: preparing a Low-E glass plate comprising a glass substrate and a Low-E layer laminated on the glass substrate; A step of attaching any of the protective sheets disclosed in 1.; at least one selected from the group consisting of transportation, storage, processing, cleaning and handling for the Low-E glass sheet to which the protective sheet is attached. A step of removing the protective sheet from the Low-E glass plate; and a step of assembling a glass unit using the Low-E glass plate.
According to the above method, the Low-E glass plate has a risk of damage, abrasion, deterioration, corrosion, etc. due to the presence of the protective sheet during processing such as transportation, storage, cutting, washing such as washing, and various handling. Can be avoided. Further, by using the protective sheet disclosed herein, it is possible to protect a large-area Low-E glass plate with one sheet or a small number of sheets. Also, as described above, the protective sheet can be inspected through the protective sheet while being attached to the Low-E glass plate. Further, the protective sheet is easily visible on the surface of the Low-E glass plate as described above, and it is easy to determine the presence/absence of the protective sheet for a large-area Low-E glass plate, and the workability of removing the protective sheet is excellent. According to the above method, in the production of the glass unit, it is possible to produce the glass unit with high productivity while achieving protection of the Low-E glass plate.

It is a schematic diagram for demonstrating one Embodiment of the manufacturing method of a glass unit. It is sectional drawing which shows typically one form example of a protection sheet.

A preferred embodiment of the present invention will be described below. Matters other than the matters particularly referred to in the present specification and necessary for carrying out the present invention are based on the teaching for carrying out the invention described in the present specification and the common general knowledge as of the filing. It can be understood by those skilled in the art. The present invention can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the field.

<Glass unit manufacturing method>
The method for manufacturing a glass unit disclosed herein includes a step (A) of preparing a Low-E glass plate including a glass substrate and a Low-E layer laminated on the glass substrate; A step (B) of attaching a protective sheet to the surface of the Low-E layer of the above; and at least one selected from the group consisting of transportation, storage, processing, cleaning and handling for the Low-E glass plate to which the protective sheet is attached. And an optional step (C) for carrying out one of the steps; a step (D) for removing the protective sheet from the Low-E glass plate; and a step (E) for assembling a glass unit using the Low-E glass plate. .. In this method, the protective sheet disclosed herein (also referred to as a surface protective sheet) is used. Hereinafter, description will be given with reference to FIG.

First, in step (A), as shown in FIG. 1A, a Low-E glass plate 100 including a glass substrate 110 and a Low-E layer 120 laminated on the glass substrate 110 is prepared ( S10). The Low-E glass plate 100 is prepared by forming a Low-E layer 120 on one surface of a glass substrate 110. The Low-E layer includes a metal layer, an oxide layer such as a metal oxide layer, a layer such as a nitride layer such as a silicon nitride layer, and usually has a multilayer structure, and a known or common method such as sputtering. Is formed by. Examples of the material forming each layer of the Low-E layer include TiO ₂ , ZrO ₂ , Si _x N _y , ZnO _x , Ag, NiCrO _x , and SnO ₂ . An Ag layer is preferably used as the infrared reflective layer. In the Low-E layer according to one embodiment, the Ag layer is typically sandwiched between ZnO _x layers. The material of the outermost surface of the Low-E layer (the surface to which the protective sheet is attached) should be an oxide such as TiO ₂ , ZrO ₂ , ZnO _x , NiCrO _x , SnO ₂ or a nitride such as Si _x N _y. However, it is usually not a metal such as Ag. The Low-E layer may have a multilayer structure of 5 layers or more, for example, 10 layers or more, and further 15 layers or more, depending on the purpose and required characteristics. The thickness of each layer is not particularly limited and is usually 0 to 1000 Å, and about 10 to 700 Å is suitable, for example, about 30 to 300 Å. The thickness (total thickness) of the Low-E layer may be about 10 nm to 1000 nm (eg, about 50 to 500 nm). The size of the glass substrate is not particularly limited, and the length of one side (width) is, for example, about 2 m or more, and more than 2.6 m recently, and further, about 3 m or more (for example, about 3.3 m or more). The thing of the area is used.

In the step (B), as shown in FIG. 1B, the protective sheet 200 is attached to the surface of the Low-E layer 120 formed on the glass substrate 110 (S20). The protective sheet 200 is typically releasably attached to the surface. Here, "removably attached" means attachment intended or intended to be removed by peeling, and in many cases, the surface of the adherend after peeling the protective sheet (adhesive sheet) is the same as before attachment. Basically, it refers to pasting that can maintain the same state. From the viewpoint of protection, the size of the protective sheet 200 is preferably about the same as the surface of the Low-E layer 120. The surface to be protected may be covered by partially overlapping two or more protective sheets. By covering the surface of the Low-E layer 120 with the protective sheet 200, corrosion or the like of the Low-E layer 120 can be prevented or suppressed.

After the step (B), as the step (C), at least one step selected from the group consisting of transportation, storage, processing, cleaning and handling is performed on the Low-E glass sheet 100 to which the protective sheet 200 is attached. It can be implemented arbitrarily (S30). The processing may be cutting, edge seam, or the like of the Low-E glass plate 100 to which the protective sheet 200 is attached. The cutting means and the size after cutting are appropriately set according to the purpose and are not particularly limited. The protective sheet 200 may remain attached to the surface of the Low-E layer 120 even after cutting the Low-E glass plate 100. The cut Low-E glass plate 100 is typically washed with water or the like. In the washing step, in addition to water, a detergent (including a surfactant) can be optionally used. During the above-mentioned transportation, storage, processing such as cutting, washing such as water washing, and various handlings, as shown in FIG. 1C, the Low-E layer 120 is formed by the protective sheet 200 being present thereon. Protected from damage, wear, deterioration and corrosion.

Next, in the step (D), the protective sheet 200 is removed from the Low-E glass plate 100 ((D) S40 in FIG. 1). The protective sheet 200 is removed from the Low-E glass plate 100, which is the adherend, after achieving the protective purpose. Since the protective sheet 200 disclosed herein is easily visible on the surface of the Low-E glass plate 100 as described later, it is easy to determine the presence or absence of the protective sheet 200 with respect to the Low-E glass plate 100, and the protective sheet 200 It has excellent workability in removing. The Low-E glass plate 100 from which the protective sheet 200 has been removed is usually heat-treated in a heating furnace and tempered. Then, as shown in FIG. 1E, a glass unit 300 is manufactured using the Low-E glass plate 100 (step (E) S50). The glass unit 300 is typically a heat-shielding or heat-insulating glass unit. A pair of glass plates, at least one of which is the Low-E glass plate 100, is prepared, and the Low-E layer of the Low-E glass plate 100 is prepared. It can be made by making a pair of glass with the surface 120 facing inward. Reference numerals 320 and 340 in the figure respectively represent other glass plates and spacers that constitute the glass unit 300. The spacer 340 is disposed between the Low-E glass plate 100 and the other glass plate 320 to create a space between the glass plates 100 and 320. In the method disclosed herein, a known or commonly used powder or liquid coating may be used in combination with the protective sheet.

Also, the glass unit manufacturing method disclosed herein may include an inspection step of the Low-E glass plate 100 after the step (B) and before the step (D). In this aspect, the protective sheet 200 may be transparent. Therefore, it is possible to inspect the Low-E glass plate 100 through the protective sheet 200 while being attached to the Low-E glass plate 100. This inspection step can be typically performed at an appropriate timing while step (C) is being performed. The content of the inspection is not particularly limited, and may be the presence or absence of foreign matter such as water between the surface of the Low-E glass plate 100 and the protective sheet 200, and the presence or absence of defects or damage on the surface of the Low-E glass plate 100. .. The inspection is preferably visual observation by an inspector, or may be an inspection using various inspection devices or inspection devices. By carrying out such an inspection, when foreign matter such as water is present on the surface of the Low-E glass plate, it is possible to prevent the occurrence of defects by reattaching or replacing the protective sheet. Moreover, the occurrence of defects and damages can be detected and dealt with at an early stage.

<Surface protection method>
The surface protection method disclosed herein is a surface protection method using a protection sheet (also referred to as a surface protection sheet) disclosed herein, and typically, a part or all of the surface of a Low-E glass plate. Regarding how to protect. The protection method disclosed herein is characterized by including a step (sticking step) of sticking a protective sheet on the surface of the Low-E glass plate.

Further, the surface protection method disclosed herein may further include a step (removal step) of removing the protection sheet from the Low-E glass plate. Further, between the attaching step and the removing step, the article to which the protective sheet is attached may optionally include at least one step selected from the group consisting of transportation, storage, processing, cleaning and handling.

Suitable examples of the surface protection method disclosed herein are as described in the above-mentioned method for manufacturing a glass unit, and the attaching step and the removing step in this method are performed in steps (B) and (D) in the above-mentioned manufacturing method. Corresponds to each. Other matters in the surface protection method are not particularly limited, but since they can be understood by those skilled in the art in consideration of the above description of the method for manufacturing the glass unit, detailed description thereof will be omitted here.

<Structure of protective sheet>
As used herein, the term "adhesive" refers to a material that is in the state of a soft solid (viscoelastic body) in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure. .. The adhesive used herein generally has a complex tensile modulus E ^* (1 Hz) as defined in “C. A. Dahlquist, “Adhesion: Fundamentals and Practice”, McLaren & Sons, (1966) P. 143”. It may be a material having a property satisfying <10 ⁷ dyne/cm ² (typically, a material having the above property at 25° C.).
Further, the concept of the protective sheet in the present specification may include what is called an adhesive sheet, an adhesive tape, an adhesive label, an adhesive film and the like. The protective sheet disclosed herein may be in a roll shape or a sheet shape. Alternatively, it may be a sheet having a form further processed into various shapes.

The protective sheet disclosed herein typically has a pressure-sensitive adhesive layer on a base material layer (supporting base material). FIG. 2 shows a cross-sectional structure of the protective sheet according to the one example. This protective sheet 10 has a structure in which a pressure-sensitive adhesive layer 2 is provided on one surface 1A of a sheet-shaped base material layer 1, and the surface 2A of the pressure-sensitive adhesive layer 2 is attached to an adherend for use. .. When the protective sheet 10 is used as a surface protective sheet, the surface 2A of the pressure-sensitive adhesive layer 2 is attached to the object to be protected. The back surface 1B of the base material layer 1 (the surface opposite to the one surface 1A) is also the back surface of the protective sheet 10 and constitutes the outer surface of the protective sheet 10. The protective sheet 10 before use (that is, before being adhered to an adherend) has a surface (adhesive surface, that is, a surface to be adhered to an adherend) 2A of the pressure-sensitive adhesive layer 2, and a release surface at least on the pressure-sensitive adhesive layer side. It may be in a form protected by a release liner (not shown). Alternatively, the other surface (back surface) 1B of the base material layer 1 is a release surface, and when the protective sheet 10 is wound in a roll, the pressure-sensitive adhesive layer 2 comes into contact with the back surface and its surface (adhesion) The surface 2A may be the protective sheet 10 in a protected form.

As the release liner, a conventional release paper or the like can be used and is not particularly limited. For example, it is possible to use a release liner having a release treatment layer on the surface of a liner substrate such as a plastic film or paper, or a release liner made of a low adhesion material such as a fluoropolymer (polytetrafluoroethylene) or a polyolefin resin. it can. The release treatment layer may be formed by surface-treating the liner substrate with various release treatment agents such as silicone-based, long-chain alkyl-based, fluorine-based, and molybdenum sulfide.

The width of the protective sheet disclosed here may be approximately 1.5 m or more. Such a wide protective sheet can achieve a protective function for a large area Low-E glass plate with one sheet or a small number of sheets. Further, the protective sheet disclosed herein is easily distinguishable from the Low-E glass plate even if it is attached to the Low-E glass plate in a large area as described later. For protecting the Low-E glass plate, a protective sheet having a width of, for example, about 2 m or more, and further, about 2.6 m or more can be preferably used. The width of the protective sheet can be greater than 2.6 m (eg, 3 m or more, and even about 3.3 m or more). The upper limit of the width of the protective sheet is not particularly limited, and from the viewpoint of productivity, handleability, etc., it is suitable to be about 5 m or less, and for example, about 4 m or less. The length of the long protective sheet (distance in the length direction) is the same as or larger than the width.

The protective sheet disclosed herein may be a sheet specified by having long sides and short sides in its plane (sheet surface), for example. The long side is longer than the short side, and the short side is defined as the side shorter than the long side. Also, for example, the short side may be a side substantially orthogonal to the long side. The length direction of the protective sheet is a direction along the long side, and the width direction is a direction orthogonal to the length direction. Therefore, in this specification, "width" is defined as the length in the direction orthogonal to the length direction. The protective sheet called a long shape, a belt shape, and a rectangular shape is a typical example of the protective sheet disclosed herein. The long side is a line segment that extends substantially linearly, while the short side is not limited to a straight line and may be a curved line, a polygonal line, or the like. For example, the length (distance in the length direction) of the long protective sheet is equal to or more than the width.

The thickness of the protective sheet disclosed herein is not particularly limited, and from the viewpoint of handleability, lightness, etc., it is suitable to be about 1000 μm or less (typically about 300 μm or less, for example, about 150 μm or less). .. In one aspect, the thickness of the protective sheet may preferably be about 120 μm or less, more preferably about 100 μm or less, even more preferably about 75 μm or less, for example less than 60 μm. Also, the thickness of the protective sheet may typically be above 20 μm, preferably above 30 μm, more preferably above 40 μm, for example above 45 μm.
In this specification, the thickness of the protective sheet includes the thicknesses of the pressure-sensitive adhesive layer and the base material layer, but does not include the thickness of the release liner.

The thickness of the base material layer constituting the protective sheet disclosed herein is not particularly limited. The thickness of the base material layer may be, for example, about 800 μm or less (typically about 250 μm or less). In one aspect, the thickness of the substrate layer (typically a non-foamed resin film) can be preferably about 150 μm or less, more preferably about 100 μm or less, even more preferably less than 65 μm, for example less than 55 μm. When the thickness of the base material layer is small, the conformability of the protective sheet to the shape of the adherend is enhanced, and the peeling off tends to be suppressed. From the viewpoint of protection of the adherend, handling property, etc., the thickness of the base material layer is typically about 10 μm or more, preferably about 25 μm or more, more preferably more than 30 μm, further preferably more than 40 μm, for example, It can be above 45 μm.

The thickness of the pressure-sensitive adhesive layer forming the protective sheet disclosed herein is not particularly limited. From the viewpoint of preventing adhesive residue on the adherend, the thickness of the pressure-sensitive adhesive layer is appropriately about 50 μm or less and about 30 μm or less, preferably about 15 μm or less, and more preferably about 8 μm or less (for example, less than 6 μm). preferable. In another aspect, the thickness of the pressure-sensitive adhesive layer is appropriately about 5 μm or less, may be about 4 μm or less, and may be, for example, 3 μm or less, from the viewpoint of peelability and the like. Further, from the viewpoint of adhesiveness, the thickness of the pressure-sensitive adhesive layer is appropriately about 0.5 μm or more, preferably about 1 μm or more, and more preferably more than 2 μm. The pressure-sensitive adhesive layer may have a thickness of more than 3 μm, for example, more than 4 μm.

<Visibility of protective sheet>
The protective sheet disclosed herein has a region satisfying at least one of (a) a minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) a haze value of 10 or more (hereinafter, for convenience. It is characterized by having a "visual recognition area") on at least a part of the sheet surface. The protective sheet having the visible area is easily visible on the surface of the Low-E glass plate, and the presence or absence thereof can be easily determined.

-The layout, shape, size, and ratio of the visible area to the entire sheet surface are not particularly limited. For example, the entire sheet surface of the protective sheet may be the visible area, or a part of the sheet surface may be the visible area. A protective sheet having a pattern of a visible area and a transparent area (described later) on the sheet surface is an example of a protective sheet having a visible area. The area ratio of the visible region on the sheet surface of the protective sheet is about 1% or more (for example, about 5% or more), about 10% or more, preferably about 30% or more, and more preferably about 10% or more. It is 50% or more, more preferably about 70% or more, particularly preferably about 90% or more (typically 100%). In one particularly preferred embodiment, the entire sheet surface of the protective sheet is the visible area.

In the above visible region, the minimum transmittance in the wavelength range of 450 to 800 nm (minimum transmittance in the visible light region) is not particularly limited, and it is suitable that it is approximately 95% or less. In one aspect, the minimum transmittance of the visible region in the visible region may be about 90% or less. The protective sheet having such a visible region is easily visible on the surface of the Low-E glass plate, and the presence or absence thereof can be easily discriminated. The minimum transmittance of the visible region in the visible region is preferably about 80% or less, for example, about 70% or less, about 60% or less, or about 50% or less. Good. In the aspect in which the entire sheet surface of the protective sheet is the visible region, the minimum transmittance in the visible light region of the protective sheet can take the above range or value.

　The haze value in the above visible area is not limited to a specific range. It is appropriate that the haze value in the visible region is about 1 or more (for example, about 5 or more). In one aspect, the haze value in the visible region may be about 10 or more (eg, about 11 or more). The protective sheet having a haze value of a predetermined value or more is easily visible on the surface of the Low-E glass plate, and the presence or absence thereof can be easily discriminated. In another aspect, the haze value may be about 15 or more (eg, about 20 or more), and may be more than 50 (eg, about 80 or more, and even about 90 or more). In the aspect in which the entire sheet surface of the protective sheet is the visible region, the haze value of the protective sheet can take the above range or value.

Here, the “haze value” refers to the ratio of diffuse transmitted light to the total transmitted light when the measurement target is irradiated with visible light. Also called cloudiness value. The haze value can be expressed by the following formula.
Th=Td/Tt×100
In the above formula, Th is the haze value, Td is the scattered light transmittance, and Tt is the total light transmittance. The haze value can be adjusted, for example, by selecting the composition and thickness of the base material layer and the pressure-sensitive adhesive layer.

The total light transmittance in the visible region of the protective sheet is not limited to a specific range, but from the viewpoint of the discriminability on the Low-E glass plate, it is appropriate that it is approximately 95% or less, and preferably Is about 90% or less, for example, about 80% or less, or about 70% or less. In the aspect in which the entire sheet surface of the protective sheet is the visible region, the total light transmittance of the protective sheet can take the above range or value.

In a preferred aspect, the visible area is a colored area. Since the colored area is excellent in visibility, providing the colored area on the surface of the sheet makes it easier to obtain superior protection sheet discrimination. The coloring aspect is not particularly limited, and examples thereof include an aspect in which at least a part of the sheet surface of the protective sheet is a colored region. Specifically, the entire sheet surface of the protective sheet may be the colored area, or a part of the sheet surface may be the colored area. A protective sheet having a pattern of colored portions and non-colored portions on the sheet surface is an example of a protective sheet having colored regions.

At least a part (typically the whole) of the protective sheet according to one aspect is colored. It is preferable that the colored portion (which is also a colored region) is uniformly colored from the viewpoint of discriminating property. In a preferred aspect, the protective sheet is colored almost uniformly over the entire sheet surface. Thereby, for example, even if a part (for example, a small piece) of the protective sheet remains on the Low-E glass plate due to tearing or the like, it is easy to determine the presence or absence of the protective sheet. The term “uniform” as used herein means the uniformity at the visual level. The fact that the entire sheet surface has the same color and the same darkness is a typical example of a configuration in which the entire sheet surface is colored almost uniformly.

As a pattern of the visible area on the sheet surface of the protective sheet, a linear or curved stripe pattern can be mentioned. For example, a wavy stripe pattern may be adopted. Examples of the wavy shape include a curved shape such as a sine wave, a pseudo sine wave, and an arc wave, and a non-curved shape such as a zigzag shape and a triangular wave. The wavy pattern may be formed by overlapping two or more kinds of waves of the same shape or different shapes with their phases shifted, or by inverting the shape or pattern. Other examples of the above pattern include, for example, arc-shaped, circular, elliptical, and linear patterns.

As another example of the pattern of the visible area on the sheet surface of the protective sheet, a grid pattern can be cited. Here, the lattice pattern typically refers to a pattern including two stripe pattern portions that intersect each other. The lattice pattern includes various lattice shapes such as an orthorhombic lattice, a square lattice, a triangular lattice, and a hexagonal lattice. As still another example of the above pattern, a dot-shaped or polka-dot-shaped pattern, or a pattern in which a plurality of colored portions having a specific shape such as a quadrangle or a triangle are arranged at intervals is cited.

The visible area (typically the colored area) on the sheet surface of the protective sheet may be a mark. Here, the mark may typically be a combination of a color and a character (that is, a character, a figure or a symbol, or a combination thereof). Characters and symbols include those in which the above-mentioned characters and the like are designed in various degrees. As the information represented by the above characters, the product name, manufacturer name, specifications (Low-E and low VOC (volatile organic compounds), energy saving, environmental load, reduction of greenhouse gas emissions, and other expressions that mean them ), usage method, recycling related information, manufacturing date, product number (lot number), expiration date, logo mark, image character, mascot character, material of product components (adhesive, base material, etc.) Further, the kind, the kind of the contained component, the content thereof and the like can be mentioned. These marks may be used alone or in combination of two or more. Characters and the like representing these pieces of information can be a mark that more effectively conveys the information to the viewer by being combined with coloring.

The color of the colored area of the protective sheet is not particularly limited, and for example, one or more of black, gray, white, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl, etc. Can be From the viewpoint of the adherend visibility through the protective sheet, gray, red, blue, yellow, green, yellow-green, orange, and purple are preferable. In a particularly preferred aspect, the protective sheet is colored blue and/or green. The colors of blue and green are relatively unnoticeable compared to red and yellow, and they have sufficient visibility on the Low-E glass plate and are easy to harmonize with the surrounding environment.
In the technology disclosed herein, blue means a color having a visible spectrum wavelength range of 360 nm or more and less than 480 nm, and green means a color having a visible spectrum wavelength range of 480 nm or more and less than 560 nm.

An appropriate coloring agent is typically used for coloring the protective sheet. As the colorant, conventionally known pigments and dyes can be used. Examples of the pigment include zinc carbonate, zinc oxide, zinc sulfide, talc, kaolin, calcium carbonate, titanium oxide, silica, lithium fluoride, calcium fluoride, barium sulfate, alumina, zirconia, iron oxides, iron hydroxides. Inorganic pigments such as chromium oxide type, chromium hydroxide type, spinel type firing type, chromic acid type, chrome vermilion type, navy blue type, cobalt blue type, aluminum powder type, bronze powder type, silver powder type, calcium phosphate, etc., Phthalocyanine, azo, condensed azo, azo lake, anthraquinone, perylene/perinone, flavone, indigo, thioindigo, isoindolinone, azomethine, dioxazine, quinacridone, aniline black, triphenylmethane And organic pigments such as carbon black. Examples of the dye include azo dyes, anthraquinone, quinophthalone, styryl, diphenylmethane, triphenylmethane, oxazine, triazine, xanthan, methane, azomethine, acridine, and diazine. The colorants may be used alone or in appropriate combination of two or more.

The above coloring is realized by including an appropriate coloring agent in the pressure-sensitive adhesive layer, the base material layer, or a coloring layer different from them. In a preferred embodiment, at least one of the base material layer and the pressure-sensitive adhesive layer forming the protective sheet is colored. Specifically, both the base material layer and the pressure-sensitive adhesive layer are colored, the base material layer is colored and the pressure-sensitive adhesive layer is not colored, and the base material layer is not colored. The layer may be colored. Among them, the embodiment in which the base material layer is colored is preferable because it does not affect the adhesive property. In addition, in this specification, a non-colored base material layer and an adhesive layer may be a colorless transparent base material layer and an adhesive layer, respectively. The colorless transparent base material layer and the pressure-sensitive adhesive layer have a total light transmittance of more than 85% (eg, more than 90%), a minimum transmittance in the visible light region of more than 85% (eg, more than 90%), and The haze value can be 20 or less (eg, 10 or less).

The protective sheet may be colored by providing a colored layer on at least one surface of the base material layer. Such a coloring layer can be typically formed by applying a coloring layer-forming composition containing a coloring agent and a binder to a supporting substrate. As the colorant, a conventionally known pigment or dye can be used, and one kind or two or more kinds of the above-mentioned colorants can be used. As the binder, materials known in the field of paints or printing can be used without particular limitation. For example, polyurethane, phenol resin, epoxy resin, urea melamine resin, polymethylmethacrylate, etc. are exemplified. In addition, in the configuration in which the colored layers are arranged on both sides of the base material layer, the configurations of the colored layers may be the same or different.

The composition for forming a colored layer may be, for example, a solvent type, an ultraviolet curing type, a thermosetting type, or the like. The formation of the colored layer can be carried out by using the means conventionally used for forming the colored layer without particular limitation. For example, a method of forming a colored layer (printing layer) by printing such as gravure printing, flexographic printing and offset printing can be preferably adopted. The coloring layer may have a single-layer structure consisting of one layer or a multi-layer structure including two layers, three layers or more sub-coloring layers. The total thickness of the colored layer is appropriately about 1 μm to 10 μm, preferably about 1 μm to 7 μm, and for example, about 1 μm to 5 μm. In a colored layer including two or more sub-colored layers, the thickness of each sub-colored layer is preferably about 1 μm to 2 μm.

<Permeability of protective sheet>
The protective sheet disclosed herein typically has a transparent region (a region having transparency). With this, the Low-E glass plate can be inspected through the protective sheet while being attached to the Low-E glass plate. The term "transparency" as used herein means a degree of transparency that allows the state of the opposite side to be visually recognized through the protective sheet, and is a concept that includes translucency and colored transparency. Further, the transparency of the protective sheet is the permeability in the direction orthogonal to the sheet surface (in other words, the thickness direction of the protective sheet). The transparency can be characterized by, for example, total light transmittance. Specifically, in the present specification, “having transparency” means that the total light transmittance is 3% or more. Therefore, in the present specification, a protective sheet having a total light transmittance of less than 3%, a base material layer (for example, a resin film), or an adhesive layer is classified as having no transparency.

The arrangement, shape, size, and ratio of the transparent area to the entire sheet surface are not particularly limited. For example, the entire sheet surface of the protective sheet may be the transparent area, or a part of the sheet surface may be the transparent area. A protective sheet having a pattern of visible areas and transparent areas on the sheet surface is an example of a protective sheet having transparent areas. In a preferable aspect, the transparent region and the above-mentioned visible region may be the same region. The area ratio of the transparent region on the sheet surface of the protective sheet is about 1% or more (for example, about 5% or more), about 10% or more is appropriate, preferably about 30% or more, more preferably It is about 50% or more, more preferably about 70% or more, particularly preferably about 90% or more (typically 100%). In one particularly preferred embodiment, the entire sheet surface of the protective sheet is the transparent area. In this aspect, the entire sheet surface of the protective sheet is a transparent area and a visible area.

The total light transmittance in the transparent region is about 3% or more as described above, and may be, for example, about 5% or more (typically about 10% or more). From the viewpoint of the visibility of the adherend through the protective sheet, it is appropriate that the total light transmittance in the transparent region is about 20% or more (eg, about 30% or more), preferably about 40% or more, and more preferably about 40% or more. Is about 50% or more, more preferably about 60% or more, particularly preferably about 70% or more, and may be about 80% or more (for example, about 90% or more). In the aspect in which the entire sheet surface of the protective sheet is a transparent region, the total light transmittance of the protective sheet can take the above range or value.

The minimum transmittance of the visible region in the transparent region is not particularly limited, and is usually about 2% or more, for example, about 5% or more, and about 10% or more (for example, about 20% or more). Appropriate. By setting the minimum value of the transmittance in the wavelength range of 450 to 800 nm corresponding to the visible light region to a predetermined value or more, the visibility of the adherend through the protective sheet is improved. In a preferred embodiment, the minimum transmittance in the visible light region is about 30% or more, more preferably about 40% or more, even more preferably about 50% or more (for example, about 60% or more). In a mode in which the entire sheet surface of the protective sheet is a transparent region, the minimum transmittance in the visible light region of the protective sheet can take the above range or value.

The haze value in the transparent area is not limited to a specific range. Usually, the haze value of the transparent region is about 99 or less (for example, 90 or less). From the viewpoint of suppressing transparency and diffusion and reflection that affect visibility, the haze value is suitably about 50 or less, preferably about 30 or less, more preferably about 20 or less, and It may be 10 or less (for example, about 5 or less). In the aspect in which the entire sheet surface of the protective sheet is a transparent region, the haze value of the protective sheet can take the above range or value.

The total light transmittance of the protective sheet and each region thereof, the minimum transmittance at a wavelength of 450 to 800 nm, and the haze value are in accordance with JIS K7136:2000, and a commercially available transmittance meter (for example, a product name “HAZEMETER HM-150”). Manufactured by Murakami Color Research Laboratory Co., Ltd.). The total light transmittance, the minimum transmittance at a wavelength of 450 to 800 nm, and the haze value of the base material layer (supporting base material) described later are also measured by the same method. The same method is used in the examples described below.

<Surface characteristics of adhesive layer>
The technique disclosed herein is not particularly limited, but it is preferable that the surface layer portion of the pressure-sensitive adhesive layer has specific characteristics. The properties of the surface layer of the pressure-sensitive adhesive can be accurately characterized as mechanical properties by measurement by the nanoindentation method. Specifically, the surface hardness of the pressure-sensitive adhesive layer according to one aspect may be 0.3 MPa or more. By using the pressure-sensitive adhesive layer having a surface hardness of 0.3 MPa or more, the protective sheet after attachment has a suppressed adhesive strength over time and is excellent in workability for removing from the adherend. By increasing the hardness of the surface layer of the pressure-sensitive adhesive layer, the adhesive force is limited to a predetermined value or less and the amount of increase in the adhesive force with time is also limited, and the adhesive force with time to a level that does not impair the removal workability as a whole. Is thought to be suppressed. When importance is attached to the suppression of the adhesive strength over time in the balance between suppression of the adhesive strength over time and good adhesiveness, the surface hardness of the adhesive layer is preferably 0.4 MPa or more (for example, 0.6 MPa or more, further 0.7 MPa or more). ), more preferably 0.8 MPa or more (for example, 1.2 MPa or more, further 2 MPa or more). The upper limit of the surface hardness is appropriately 5 MPa or less from the viewpoint of adhesiveness, and can be, for example, 3 MPa or less, and further 2.7 MPa or less. In the above-mentioned balance, when importance is attached to prevention of floating and peeling and adhesion with an adherend, the surface hardness is preferably less than 2 MPa, more preferably less than 1.2 MPa, further preferably less than 0.8 MPa, particularly preferably 0 MPa. It is less than 4 MPa.

The pressure-sensitive adhesive layer according to the above aspect can be classified into two aspects from the duality of suppression of adhesive strength over time and adhesiveness to an adherend. The surface hardness of the pressure-sensitive adhesive layer according to one embodiment (first embodiment) is 0.3 MPa or more and less than 0.7 MPa. In this aspect, the lower limit of the surface hardness is preferably 0.32 MPa or more, more preferably 0.34 MPa or more, further preferably 0.35 MPa or more, and the upper limit thereof is preferably less than 0.55 MPa, more preferably Is less than 0.45 MPa, more preferably less than 0.4 MPa, particularly preferably less than 0.38 MPa. The surface hardness of the pressure-sensitive adhesive layer according to another embodiment (second embodiment) is 0.7 MPa or more and 5 MPa or less. In this aspect, the lower limit of the surface hardness is preferably 0.8 MPa or more, more preferably 0.9 MPa or more (for example, 1.2 MPa or more, further 2 MPa or more), and the upper limit thereof is preferably 4 MPa or less, It is more preferably 3 MPa or less, still more preferably 2.7 MPa or less, and particularly preferably 2.5 MPa or less.

The pressure-sensitive adhesive layer according to a preferred embodiment is a load curve slope (hereinafter, also simply referred to as “load curve slope”) obtained by a nanoindentation method, which is represented by a ratio of a load [μN] to an indentation depth [nm] up to a predetermined depth. .) is 0.7×10 ⁻² μN/nm or more. Information corresponding to elasticity (compressive elastic modulus) in the surface layer portion of the pressure-sensitive adhesive layer can be obtained from the slope of the load curve [μN/nm]. By having an appropriate elasticity, the adhesive force with time is suppressed, and excellent removal workability can be preferably realized. The gradient of the load curve is more preferably 0.73×10 ^-2 μN/nm or more, further preferably 0.75×10 ^-2 μN/nm or more, and particularly preferably 0.78×10 ^-2 μN/nm or more. is there. The slope of the load curve is 7×10 ⁻² μN/nm or less, for example, 5×10 ⁻² μN/nm or less, and further 4.5×10 ⁻² μN/nm or less from the viewpoint of adhesiveness.

Moreover, the load curve gradient of the pressure-sensitive adhesive layer according to the first embodiment is 0.7×10 ⁻² μN/nm or more and less than 1.2×10 ⁻² μN/nm. In this aspect, the lower limit of the load curve slope is preferably 0.75×10 ^-2 μN/nm or more, more preferably 0.8×10 ^-2 μN/nm or more (for example, 0.85×10 ^-2 μN/nm). nm or more), and the upper limit is preferably less than 1.1×10 ⁻² μN/nm, more preferably less than 1.0×10 ⁻² μN/nm, and further preferably 0.95×10 ⁻² μN. /Nm (eg less than 0.8×10 ^-2 μN/nm). The pressure-sensitive adhesive layer according to the second embodiment has a load curve gradient of 1.2×10 ⁻² μN/nm or more and 7×10 ⁻² μN/nm or less. In this aspect, the lower limit of the load curve slope is preferably 1.4×10 ⁻² μN/nm or more (for example, 1.8×10 ⁻² μN/nm or more), and 2×10 ⁻² μN/nm or more. (For example, 3×10 ⁻² μN/nm or more). The upper limit is preferably 5×10 ⁻² μN/nm or less, more preferably 4.5×10 ⁻² μN/nm or less (for example, 4×10 ⁻² μN/nm or less). The above numerical range is appropriately determined in consideration of the suppression of adhesive strength over time and good adhesiveness.

The pressure-sensitive adhesive layer disclosed herein preferably has a minimum load of an unloading curve by the nanoindentation method of less than 0 μN. The fact that the load applied to the indenter in the unloading direction is in the negative direction means that the indenter pushed into the pressure-sensitive adhesive layer is difficult to be pulled out, and thus the pressure-sensitive adhesive has a cohesive force. In such an adhesive layer, it is difficult for the adherend surface to wet the surface of the adherend, and it is difficult for the adhesive strength to increase with time. The minimum load of the unloading curve is more preferably −0.1 μN or less, for example −0.5 μN or less (typically less than −0.6 μN, or even less than −0.8 μN), It may be -1 μN or less and -2 μN or less. Further, the fact that the minimum load of the unloading curve is low may be that the adsorbability (adhesive force) to the indenter is evaluated. Considering the influence of this element on the light peeling property, it is appropriate that the minimum load of the unloading curve is -8 μN or more, preferably -5 μN or more, more preferably -3 μN or more, for example -2 μN. Or more (more specifically, −2.0 μN or more, typically −1.8 μN or more), or −1 μN or more.

The minimum load of the unloading curve of the pressure-sensitive adhesive layer according to the first embodiment is -8 μN or more and less than -1 μN. In this aspect, the lower limit of the minimum load of the unloading curve is preferably −5 μN or more, more preferably −3 μN or more, and the upper limit is preferably less than −1.5 μN, more preferably less than −1.8 μN. , And more preferably less than −2 μN. In the pressure-sensitive adhesive layer according to the second embodiment, the minimum load on the unloading curve is −1 μN or more and 0 μN or less. In this aspect, the lower limit of the minimum load of the unloading curve is preferably −0.5 μN or more, more preferably −0.4 μN or more (eg, −0.3 μN or more, more specifically −0.3 μN or more, Further, it may be −0.25 μN or more) and may be −0.2 μN or more (eg, −0.15 μN or more). The upper limit is preferably −0.1 μN or less, and may be, for example, −0.15 μN or less, −0.2 μN or less.

The surface hardness of the pressure-sensitive adhesive layer according to another aspect may be 0.5 MPa or less. By using the pressure-sensitive adhesive layer having a surface hardness of 0.5 MPa or less, the protective sheet adheres well to the surface of the adherend and can prevent the infiltration of water from the space between the adherend and the adherend. In a preferred embodiment, the surface hardness of the adhesive layer is less than 0.45 MPa, more preferably less than 0.4 MPa (typically less than 0.38 MPa, eg less than 0.35 MPa), eg 0.3 MPa. It may be less than. The lower limit of the surface hardness is not particularly limited, and it is suitable to be about 0.1 MPa or more, and preferably 0.2 MPa or more, more preferably from the viewpoint of light peelability and suppression of increase in adhesive strength with time. The pressure is preferably 0.25 MPa or more (typically 0.3 MPa or more, for example 0.32 MPa or more, further 0.34 MPa or more).

The pressure-sensitive adhesive layer according to a preferred aspect is a load curve slope by a nanoindentation method represented by a ratio of a load [μN] to an indentation depth [nm] up to a predetermined depth (hereinafter, also simply referred to as “load curve slope”). .) is less than 1.2×10 ⁻² μN/nm. Information corresponding to elasticity (compressive elastic modulus) in the surface layer portion of the pressure-sensitive adhesive layer can be obtained from the slope of the load curve [μN/nm]. From the viewpoint of adhesion to the surface of the adherend, the slope of the load curve is more preferably less than 1.1×10 ⁻² μN/nm, further preferably less than 1.0×10 ⁻² μN/nm, and particularly preferably It is less than 0.95×10 ^-2 μN/nm (for example, less than 0.8×10 ^-2 μN/nm). The lower limit of the slope of the load curve is not particularly limited, and it is suitable to be about 0.5×10 ⁻² μN/nm or more, and preferably from the viewpoint of having an appropriate elasticity and preventing adhesive residue and the like. 0.6×10 ^-2 μN/nm or more, more preferably 0.7×10 ^-2 μN/nm or more, further preferably 0.75×10 ^-2 μN/nm or more, particularly preferably 0.8×10 ^{It is −2} μN/nm or more (for example, 0.85×10 ⁻² μN/nm or more).

The adhesive layer disclosed herein preferably has a minimum load of -8 μN or more on the unloading curve by the nanoindentation method. The fact that the load applied to the indenter at the time of unloading is more than a predetermined value means that the indenter pushed into the pressure-sensitive adhesive layer is easy to be pulled out, which suggests that the cohesive force of the pressure-sensitive adhesive is limited. Such an adhesive layer easily wets the surface of the adherend and easily adheres to the surface of the adherend. The minimum load of the unloading curve is more preferably −5 μN or more, further preferably −3 μN or more (eg −2.5 μN or more). The minimum load of the unloading curve is not particularly limited and it is suitable that it is approximately less than 0 μN. Even when the pressure-sensitive adhesive is hard, the indenter pushed into the pressure-sensitive adhesive layer is easily pulled out, and the minimum load of the unloading curve can be in a high range (for example, around 0 μN). In consideration of such matters, from the viewpoint of obtaining appropriate softness and wettability, the minimum load of the unloading curve is preferably −0.3 μN or less (typically less than −0.6 μN, and further −0). Less than 0.8 μN), more preferably −1 μN or less, still more preferably −1.5 μN or less, and particularly preferably −2 μN or less (eg −2.5 μN or less).

The surface hardness of the pressure-sensitive adhesive layer, the load curve slope, and the minimum load of the unloading curve are determined based on the nanoindentation method by applying a minute indenter from the surface (adhesive surface) of the pressure-sensitive adhesive layer to the pressure-sensitive adhesive layer. A depth corresponding to a layer thickness of 6% (also referred to as a depth of 6%. 600 nm when the pressure-sensitive adhesive layer thickness is 10 μm) and a depth of 300 nm (a depth of 300 nm) are pushed to a shallower depth (for example, adhesiveness). When the adhesive layer thickness is 10 μm, push it to 300 nm, and when the adhesive layer thickness is 2 μm, push it to 120 nm), and then pull it out. At this time, the transition of the load (vertical axis) applied to the indenter is based on the adhesive surface. It is obtained from the load (push-in)-unload (pull-out) curve obtained by plotting against the displacement (horizontal axis) of the indenter. The surface hardness [MPa] of the pressure-sensitive adhesive layer is the maximum projected load (Pmax) [μN] of the load curve when the depth is 6% and the depth of 300 nm is the shallower of the contact projection area (A). It is calculated by dividing by. The load curve slope [μN/nm] is obtained by dividing Pmax [μN] by the indentation depth (D) [nm]. That is, the surface hardness and the load curve slope of the pressure-sensitive adhesive layer are calculated by the following equations.
Surface hardness [MPa]=Pmax/A
Load curve slope [μN/nm]=Pmax [μN]/D [nm]
The minimum load [μN] of the unloading curve is the minimum value of the unloading curve.
In the nanoindentation method, by performing the measurement at a depth corresponding to a thickness of 6% of the pressure-sensitive adhesive layer or a depth of 300 nm, the pressure-sensitive adhesive can be used even for a thin pressure-sensitive adhesive layer as in Examples described later. The behavior of the surface layer of the pressure-sensitive adhesive layer can be accurately evaluated without being affected by the base material layer supporting the layer. If the depth is increased, the influence of the base material layer may be detected, and the device (typically indenter size) is also limited. On the other hand, in the case of a thin pressure-sensitive adhesive layer, if the depth is less than 6%, the stress tends to be small and it becomes difficult to detect a significant difference. Therefore, in the technique disclosed herein, the shallower depth of 6% and 300 nm is adopted as the optimum depth.

The surface hardness, the load curve slope, and the minimum load of the unloading curve can be measured based on the nanoindentation method, for example, using a Triboindenter manufactured by Hysitron under the following conditions.
[Measurement condition]
Indenter used: Berkovich (triangular pyramid) diamond indenter Measuring method: Single indentation measuring temperature: Room temperature (25°C)
Indentation depth setting: 6% of adhesive layer thickness or 300 nm
Pushing speed: 100 nm/sec Pulling speed: 100 nm/sec

The surface hardness, the slope of the load curve, and the minimum load of the unloading curve are adjusted by the composition of the polymer (monomer composition), the glass transition temperature (Tg), the molecular weight, and the type and addition amount of the crosslinking agent contained in the adhesive. can do. Other factors that can be used for adjusting the above properties include gel fraction, polymerization method of the above polymers, polymerization conditions and the like.

The surface hardness, the load curve slope and the minimum load of the unloading curve when the depth is 6% are referred to as the depth 6% surface hardness, the depth 6% load curve slope and the minimum load of the depth 6% unloading curve, respectively. .. In addition, the surface hardness, the load curve slope and the minimum load of the unloading curve when the depth is 300 nm are referred to as the depth 300 nm surface hardness, the depth 300 nm load curve slope, and the minimum load of the depth 300 nm unloading curve, respectively. In the technology disclosed herein, surface hardness includes 6% depth surface hardness and 300 nm depth surface hardness. Further, the load curve slope includes a depth 6% load curve slope and a depth 300 nm load curve slope. Further, the minimum load of the unloading curve includes the minimum load of the 6% depth unloading curve and the minimum load of the 300 nm depth unloading curve.

<Adhesive layer>
The type of the pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer disclosed herein is not particularly limited. The pressure-sensitive adhesive layer is, for example, various polymers such as acryl-based, polyester-based, urethane-based, polyether-based, rubber-based, silicone-based, polyamide-based, and fluorine-based polymers (also referred to as a pressure-sensitive adhesive polymer or a pressure-sensitive adhesive polymer). It can be a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing as a base polymer (a main component among polymer components, that is, a component occupying 50% by weight or more) selected from the above. The technology disclosed herein can be preferably implemented in the form of a protective sheet provided with, for example, an acrylic pressure-sensitive adhesive layer or a rubber pressure-sensitive adhesive layer.

The term "acrylic pressure-sensitive adhesive layer" as used herein refers to a pressure-sensitive adhesive layer having an acrylic polymer as a base polymer. Similarly, the “rubber-based pressure-sensitive adhesive layer” refers to a pressure-sensitive adhesive layer having a rubber-based polymer as a base polymer. “Acrylic polymer” means a monomer having at least one (meth)acryloyl group in one molecule (hereinafter, this may be referred to as “acrylic monomer”) as a main constituent monomer component (mainly monomer). Component, that is, a component which accounts for 50% by weight or more of the total amount of monomers constituting the acrylic polymer). In addition, in the present specification, the term “(meth)acryloyl group” means a generic term for an acryloyl group and a methacryloyl group. Similarly, the term "(meth)acrylate" is used to mean a generic term for acrylate and methacrylate.

(Acrylic polymer)
The acrylic polymer includes, for example, an alkyl (meth)acrylate (hereinafter also referred to as “monomer A”) and another monomer having copolymerizability with the alkyl (meth)acrylate (hereinafter also referred to as “monomer B”). The polymer of the monomer raw material which can further include .) is preferable. The acrylic polymer typically has a copolymerization composition corresponding to the composition of the monomer component contained in the monomer raw material.

As the monomer A, an alkyl(meth)acrylate represented by the following general formula (1) can be preferably used.
CH ₂ =C(R ¹ )COOR ² (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. R ² is an alkyl group having 1 to 20 carbon atoms. Hereinafter, such a range of the number of carbon atoms may be represented as “C _1-20 ”. From the viewpoint of polymerization reactivity and polymerization stability, an alkyl (meth)acrylate in which R ² is a C _1-16 alkyl group is preferable, and R ² is C _1-12 (typically C _1-10 , for example, Alkyl (meth)acrylate, which is a C _1-8 ) alkyl group, is more preferable.

Examples of the alkyl(meth)acrylate in which R ² is a C _1-20 alkyl group include, for example, methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate. ) Acrylate, isobutyl(meth)acrylate, s-butyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, isopentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, 2 -Ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (Meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth) ) Acrylate, eicosyl (meth)acrylate and the like. Such alkyl (meth)acrylates may be used alone or in combination of two or more.

The technique disclosed herein is such that the alkyl acrylate as the monomer A is about 50% by weight or more (more preferably about 75% by weight or more, further preferably about 90% by weight or more, for example, about 95% by weight, based on the total monomer components. The above can be preferably carried out. The alkyl acrylate is preferably an alkyl acrylate in which R ² in the above formula (1) is a C _1-20 alkyl group, and R ² is C _1-12 (more preferably C _1-10 , particularly preferably C 1 ). Alkyl acrylate which is an alkyl group of _1-8 ) is more preferable. The technique disclosed herein is also preferably carried out in an embodiment in which the alkyl acrylate is an alkyl acrylate in which R ² in the formula (1) is a C _2-8 (typically C _4-8 ) alkyl group. Can be done. The alkyl acrylates may be used alone or in combination of two or more. When two or more kinds of alkyl acrylates are used, R ² is C _4-20 (more preferably C _4-10 , further preferably C _4-8 ) for the reason that the Tg of the acrylic polymer is adjusted to the optimum range. The alkyl acrylate A1 which is an alkyl group of 1 and the alkyl acrylate A2 which is a C _1-3 (more preferably C _1-2 , for example C ₂ ) alkyl group may be used in combination. In that case, the weight ratio (A1:A2) of the alkyl acrylate A1 and the alkyl acrylate A2 is not particularly limited, and is usually about 5:95 to 95:5, and about 10:90 to 90:10. It is suitable, for example, about 15:85 to 85:15.

In a preferred embodiment, the monomer component contains, as the monomer A, one kind or two or more kinds of alkyl methacrylate. By using alkyl methacrylate, it is possible to preferably design a base polymer that can achieve a desired adhesive hardness. The above-mentioned alkyl methacrylate is preferably an alkyl methacrylate in which R ² in the above formula (1) is a C _1-10 alkyl group, and R ² is a C _1-4 (more preferably C ₁ or C _2-4 ) Alkyl methacrylate, which is an alkyl group, is more preferable. The alkyl methacrylates can preferably be used in combination with alkyl acrylates. When the alkyl methacrylate and the alkyl acrylate are used in combination, the weight C _AM of one or more kinds of alkyl methacrylate (for example, C _2-4 alkyl methacrylate) and the weight C _{AA of} one or more kinds of alkyl acrylate are used. The ratio (C _AM :C _AA ) is not particularly limited, and in one embodiment, it is usually about 1:9 to 9:1, and it is suitable to be about 2:8 to 8:2, preferably about It is 3:7 to 7:3, more preferably about 4:6 to 6:4. In another aspect, the weight C _AM of alkyl methacrylate (eg, C ₁ alkyl methacrylate, or methyl methacrylate (MMA)) in the total amount of alkyl (meth)acrylate (C _AM +C _AA ) is usually about 30 wt% or less. Approximately 20% by weight or less is suitable, preferably approximately 10% by weight or less, more preferably approximately 7% by weight or less. On the other hand, the lower limit is usually about 0.1% by weight or more and about 1% by weight or more, and preferably about 2% by weight or more (for example, about 3% by weight or more).
The technique disclosed herein can be carried out in a mode in which the monomer component does not substantially contain alkyl methacrylate as the monomer A. In the mode in which the alkyl methacrylate is used, for example, C _1-3 alkyl methacrylate (typically Specifically, it can be carried out in a mode not including MMA).

In another preferred embodiment, the acrylic polymer contains an alkyl acrylate having an alkyl group having 4 to 9 carbon atoms (hereinafter, also referred to as a monomer m _A ), and may contain another monomer as necessary. It is a polymer of. The acrylic polymer can be synthesized by polymerizing a monomer raw material having a corresponding composition (monomer composition) by a known method.

Non-limiting examples of the monomer m _A include n-butyl acrylate (BA), n-hexyl acrylate, 2-ethylhexyl acrylate (2EHA), n-octyl acrylate, n-nonyl acrylate and isononyl acrylate (iNA). Can be mentioned. An alkyl acrylate having a —(CH ₂ ) ₃ — structure in the alkyl group is preferable, and an alkyl acrylate having a —(CH ₂ ) ₄ — structure in the alkyl group is more preferable. Suitable examples of monomers _{m A,} 2EHA, include BA and iNA. As the monomer m _A , one type can be used alone, or two or more types can be used in combination.

The amount of monomer m _A is typically at least 40 wt% of the total monomer raw material used in the synthesis of the acrylic polymer. Comprise a monomer m _A in a proportion of more than 40 wt% in the monomer composition is advantageous in terms of flexibility and low-temperature characteristics improve pressure-sensitive adhesive layer containing an acrylic polymer. From this viewpoint, the ratio of the monomers _{m A} is preferably 45 wt% or more, may be 50 wt% or more (e.g., 50 wt.%). Further, by the ratio of monomer m _A in the monomer in the composition and 99.9 wt% or less, it becomes easy to impart moderate cohesiveness to the adhesive layer containing an acrylic polymer. From this viewpoint, the proportion of the monomers m _A is preferably 95 wt% or less, more preferably 90 wt% or less, may be 85 wt% or less. In one embodiment, it may be less than 80 wt% the proportion of the monomers _{m A,} may be less than 70 wt% (e.g. 65 wt% or less).

The acrylic polymer in the technique disclosed herein may have a monomer composition containing a carboxy group-containing monomer (hereinafter, also referred to as a monomer m _B ) as the monomer _B. That is, the monomer m _B may be copolymerized with the acrylic polymer. The monomer m _B can be useful for introducing a cross-linking point in the acrylic polymer and for enhancing the cohesive force of the pressure-sensitive adhesive layer containing the acrylic polymer. The monomer m _B can also help improve the non-adhesive residue property by increasing the adhesiveness (anchoring property) between the pressure-sensitive adhesive layer containing an acrylic polymer and the base material layer. Examples of the carboxy group-containing monomer include ethylene such as acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, carboxyethyl(meth)acrylate, carboxypentyl(meth)acrylate, and 1-[2-(methacryloyloxy)ethyl]succinic acid. And unsaturated monocarboxylic acids; ethylenically unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid and anhydrides thereof (eg maleic anhydride, itaconic anhydride); and the like. The carboxy group-containing monomer may be used alone or in combination of two or more.

When the monomer m _B is used, the proportion of the monomer m _B in the monomer composition is not particularly limited. The proportion of the monomer m _B can be, for example, 0.05% by weight or more, suitably 0.1% by weight or more, and preferably 0.5% by weight or more from the viewpoint of polymerization stability and dispersion stability. It is more preferably 1% by weight or more. From the viewpoint of suppressing an excessive increase in peel strength (adhesive force), the proportion of the monomer m _B is preferably about 20% by weight or less (preferably about 10% by weight or less, typically about 7% by weight or less). Is about 5% by weight or less, more preferably about 4% by weight or less (for example, 3% by weight or less).

The acrylic polymer in the technology disclosed herein is a homopolymer in which the alkyl group has 4 to 20 carbon atoms as the monomer A for the purpose of adjusting the glass transition temperature (Tg) of the acrylic polymer, and the like. Alkyl (meth)acrylate having Tg of −50° C. or higher (hereinafter, also referred to as monomer m _C ) may be copolymerized. Here, the above-mentioned monomers belonging to the monomer m _A are excluded from the category of the monomer m _C. As the monomer m _C , one type can be used alone, or two or more types can be used in combination. The monomer m _C preferably has a homopolymer Tg in the range of −40° C. to +60° C., more preferably in the range of −30° C. to +40° C. (eg, −20° C. to +30° C.). Non-limiting examples of preferably used monomers m _C include n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate and lauryl acrylate.

When the monomer m _C is used, the proportion of the monomer m _C in the monomer composition is not particularly limited. The proportion of the monomer m _C may be, for example, 1% by weight or more, may be 5% by weight or more, may be 10% by weight or more, and may be 15% by weight or more. In one embodiment, from the viewpoint of better effective of monomers m _C, the ratio of the monomers m _C in the monomer in the composition may be more than 20 wt%, may be more than 25 wt%, even more than 30 wt% It may be 35 wt% or more (for example, 40 wt% or more). The proportion of the monomer m _C in the monomer composition can be less than 60% by weight, and from the viewpoint of improving flexibility and low-temperature characteristics, it is approximately 55% by weight or less (typically approximately 50% by weight or less, for example, approximately 45% by weight or less) is suitable. In some embodiments, the proportion of the monomer m _C may be less than 30% by weight, less than 20% by weight, less than 10% by weight (eg less than 5% by weight, even less than 1% by weight). ..

In the acrylic polymer in the technique disclosed herein, a monomer (monomer m _D ) other than the monomers m _A , m _B , and m _C may be copolymerized as the monomer A, if necessary. As the monomer m _D , various monomers copolymerizable with the monomer m _A can be used alone or in combination of two or more.

As the monomer m _D , for example, an alkyl(meth)acrylate represented by the above general formula (1) (monomer m _D1 ) (excluding those corresponding to the monomer m _A or the monomer m _C ) can be used. .. Specific examples of the alkyl (meth)acrylate that can be used as the monomer m _D1 include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and lauryl (meth)acrylate. The monomer m _D1 can be used alone or in combination of two or more.

Examples of the compound that can be used as the monomer m _D may include the following functional group-containing monomers (monomer B). Such a functional group-containing monomer can be useful for introducing a cross-linking point into the acrylic polymer and increasing the cohesive force of the acrylic polymer.
Hydroxyl group-containing monomer: For example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, Hydroxyalkyl (such as 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate and (4-hydroxymethylcyclohexyl)methyl acrylate) (Meth)acrylates; unsaturated alcohols such as vinyl alcohol and allyl alcohol.
Amide group-containing monomer: For example, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N-butyl(meth)acrylamide , N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone(meth)acrylamide.
Imido group-containing monomer: for example, N-isopropylmaleimide, N-cyclohexylmaleimide, itacone imide.
Amino group-containing monomer: For example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, t-butylaminoethyl (meth)acrylate.
Monomers having epoxy groups: for example, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allylglycidyl ether.
Cyano group-containing monomer: for example, acrylonitrile, methacrylonitrile.
Keto group-containing monomer: For example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate.
Monomers having nitrogen atom-containing ring: N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl Pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine, N-(meth)acryloylpyrrolidone.
Alkoxysilyl group-containing monomer: for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxy Propylmethyldiethoxysilane.

Other examples of the compound that can be used as the monomer m _D include vinyl ester-based monomers such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene, substituted styrenes (α-methylstyrene) and vinyltoluene; cyclohexyl ( Non-aromatic ring-containing (meth)acrylates such as (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclopentyl di(meth)acrylate, isobornyl (meth)acrylate; aryl (meth)acrylates (eg phenyl (meth)acrylate) , Benzyl (meth)acrylate, aryloxyalkyl (meth)acrylate (eg phenoxyethyl (meth)acrylate), arylalkyl (meth)acrylate (eg benzyl (meth)acrylate), etc. Olefin-based monomers such as ethylene, propylene, isoprene, butadiene and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; isocyanate group-containing monomers such as 2-(meth)acryloxyethyl isocyanate; methoxyethyl (meth)acrylate Alkoxy group-containing monomers such as ethoxyethyl (meth)acrylate; vinyl ether type monomers such as methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether; and the like.

Still another example of the compound that can be used as the monomer m _D is a polyfunctional monomer. Specific examples of the polyfunctional monomer include 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa. Examples thereof include compounds having two or more (meth)acryloyl groups in one molecule, such as (meth)acrylate and methylenebisacrylamide. When such a polyfunctional monomer is used, the amount used is not particularly limited, but it is suitable to be 2% by weight or less (more preferably 1% by weight or less) of the total monomer components.

The amount of the monomer m _D used is appropriately set so as not to exceed 40% by weight of the monomer composition, preferably does not exceed 20% by weight, and more preferably does not exceed 10% by weight. The monomer m _D may not be used. The technique disclosed herein can be preferably carried out in an embodiment in which the amount of the monomer m _D used is 0% by weight or more and less than 5% by weight of the monomer composition. Here, that the amount of the monomer m _D used is 0 wt% of the monomer composition means that the monomer m _D is not used at least intentionally.

Although not particularly limited, the proportion of the monomer A (alkyl (meth)acrylate) in all the monomer components can be, for example, about 50% by weight or more, and about 60% by weight or more is suitable. It is preferably about 70% by weight or more, more preferably about 80% by weight or more, and even more preferably about 85% by weight or more. By including the monomer A in a predetermined amount or more, a protective sheet having desired adhesive properties can be preferably realized. The technique disclosed herein can be preferably carried out, for example, in a mode in which the proportion of the monomer A in all the monomer components is about 90% by weight or more. In one embodiment, the proportion of the monomer A may be about 95% by weight or more, or about 97% by weight or more. Such a pressure-sensitive adhesive composition containing an acrylic polymer as a base polymer can be advantageous from the viewpoint of weather resistance of a pressure-sensitive adhesive layer formed from the composition (and by extension, a protective sheet having the pressure-sensitive adhesive layer). Further, in a mode in which the monomer A and the monomer B are used in combination, the ratio of the monomer A in all the monomer components can be, for example, 99.9% by weight or less from the viewpoint of appropriately exerting the effect of the monomer B. , Preferably 99.5% by weight or less, more preferably 99% by weight or less, or about 97% by weight or less (for example, 95% by weight or less).

When the above-mentioned functional group-containing monomer is copolymerized with the acrylic polymer, the proportion of the functional group-containing monomer in all the monomer components constituting the acrylic polymer is about 0.1% by weight or more (typically Is preferably about 0.5% by weight or more, for example about 1% by weight or more), and about 40% by weight or less (typically about 30% by weight or less, for example about 20% by weight or less). Is preferred. For example, when a hydroxyl group-containing monomer is copolymerized with an acrylic monomer, the proportion of the hydroxyl group-containing monomer in all the above monomer components is about 0.001% by weight or more (typically from the viewpoint of obtaining a desired cohesive force). Is about 0.01% by weight or more, for example about 0.1% by weight or more), preferably about 1% by weight or more, more preferably about 3% by weight or more, and about 10% by weight. % Or less (typically about 7% by weight or less, for example, about 5% by weight or less) is suitable.

(Rubber polymer)
In another preferable aspect, the pressure-sensitive adhesive layer may be a rubber-based pressure-sensitive adhesive layer. Examples of the base polymer include natural rubber; styrene-butadiene rubber (SBR); polyisoprene; butene (1-butene, and cis- or trans-2-butene) and/or 2-methylpropene (isobutylene). Butene-based polymer having as a main monomer; ABA type block copolymer rubber and hydrogenated products thereof, for example, styrene-butadiene-styrene block copolymer rubber (SBS), styrene-isoprene-styrene block copolymer rubber (SIS), styrene-isobutylene-styrene block copolymer rubber (SIBS), styrene-vinyl-isoprene-styrene block copolymer rubber (SVIS), styrene-ethylene-butylene-styrene block copolymer weight which is a hydride of SBS. Various rubber-based polymers such as a united rubber (SEBS) and a styrene hydride of styrene-ethylene-propylene-styrene block copolymer rubber (SEPS); These rubber-based polymers may be used alone or in combination of two or more.

(Tg of base polymer)
The Tg of the base polymer of the pressure-sensitive adhesive layer disclosed herein (acrylic polymer in the case of the acrylic pressure-sensitive adhesive layer) is not particularly limited. The Tg of the base polymer can be, for example, about 0° C. or lower. In a preferred embodiment, the Tg of the base polymer of the pressure-sensitive adhesive layer is about -5°C or lower. According to the base polymer having such Tg, a pressure-sensitive adhesive layer having excellent adhesion to an adherend can be preferably formed. According to the embodiment in which the Tg of the base polymer is about −15° C. or lower (more preferably about −20° C. or lower, for example, about −25° C. or lower), a better effect can be realized. In another preferred embodiment, from the viewpoint of adhesiveness to an adherend, the Tg of the base polymer of the pressure-sensitive adhesive layer is about −35° C. or lower, more preferably about −40° C. or lower, and further preferably about −45. C. or lower (for example, about −50° C. or lower, further about −52° C. or lower, or about −55° C. or lower). The Tg of the base polymer is suitably -70°C or higher, and from the viewpoint of cohesiveness of the pressure-sensitive adhesive, etc., it is preferably about -65°C or higher, more preferably -60°C or higher, and even more preferably -. The temperature is 55° C. or higher (eg, about −50° C. or higher), and may be about −35° C. or higher. The Tg of the base polymer can be adjusted by appropriately changing the monomer composition (that is, the type of monomer used in the synthesis of the polymer and the ratio of the amounts used).

In the present specification, the Tg of a polymer means a Fox based on the Tg of a homopolymer of each monomer constituting the polymer and the weight fraction of the monomer (copolymerization ratio on a weight basis). The value obtained from the formula. The Fox equation is a relational expression between Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1/Tg=Σ(Wi/Tgi)
In the above Fox equation, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi is a homopolymer of the monomer i. Represents the glass transition temperature (unit: K) of.

As the glass transition temperature of the homopolymer used for calculation of Tg, the value described in publicly known data shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of homopolymers of the monomers.
2-ethylhexyl acrylate -70°C
n-hexyl acrylate -65°C
n-octyl acrylate -65°C
Isononyl acrylate -60℃
n-nonyl acrylate-58℃
n-Butyl acrylate -55°C
Ethyl acrylate -20℃
Lauryl acrylate 0℃
2-ethylhexyl methacrylate -10°C
Methyl acrylate 8℃
n-butyl methacrylate 20°C
Methyl methacrylate 105°C
Acrylic acid 106℃
Methacrylic acid 228°C
Vinyl acetate 32°C
Styrene 100°C

Regarding the Tg of homopolymers of monomers other than those exemplified above, the values described in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. For monomers for which multiple types of values are described in this document, the highest value is adopted. When the Tg of the homopolymer is not described in the above Polymer Handbook, the value obtained by the measuring method described in Japanese Patent Application Publication No. 2007-51271 shall be used.

(Synthesis of base polymer)
The method for obtaining the base polymer (for example, an acrylic polymer) is not particularly limited. For example, a known polymerization method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, or a suspension polymerization method can be appropriately adopted. Alternatively, photopolymerization performed by irradiating light such as UV (typically, performed in the presence of a photopolymerization initiator), radiation polymerization performed by irradiating radiation such as β-ray or γ-ray. Active energy ray irradiation polymerization may be adopted. The base polymer (for example, an acrylic polymer) is obtained, for example, by emulsion polymerization of a monomer raw material having the above composition. For example, as a monomer supply method in the emulsion polymerization method, a batch charging method of supplying all the monomer raw materials at once, a continuous supply (dropping) method, a divided supply (dropping) method, and the like can be appropriately adopted. Part or all of the monomer components may be previously mixed with water and a surfactant to emulsify, and the emulsion may be supplied to the polymerization vessel.

The polymerization temperature can be appropriately selected according to the type of monomer and solvent used, the type of polymerization initiator, and the like. The polymerization temperature is appropriately about 20°C or higher, preferably about 40°C or higher, more preferably about 50°C or higher, about 60°C or higher, about 65°C or higher, and further about 70°C. It may be set to ℃ or higher. The polymerization temperature is appropriately about 170° C. or lower (typically about 140° C. or lower), and preferably about 95° C. or lower (eg, about 85° C. or lower). In emulsion polymerization, the polymerization temperature is preferably about 95° C. or lower (for example, about 85° C. or lower).

The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons), acetic acid esters such as ethyl acetate, and aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane are preferably used.

Examples of the polymerization initiator include, but are not limited to, an azo initiator, a peroxide initiator, and a redox initiator in which a peroxide and a reducing agent are combined. The polymerization initiators may be used alone or in combination of two or more.
Examples of azo initiators are 2,2′-azobisisobutyronitrile, 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate, 2,2′. -Azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'- Examples thereof include azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride and 2,2′-azobis(N,N′-dimethyleneisobutylamidine)dihydrochloride.
Examples of peroxide-based initiators include persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, di-n. -Octanoyl peroxide, di(4-methylbenzoyl) peroxide, t-butyl peroxybenzoate, t-butyl peroxysobutyrate, t-hexyl peroxypivalate, t-butyl peroxypivalate, di(2-ethylhexyl)peroxydi Carbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy neodecanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexano Ate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-hexylperoxy)cyclohexane, Hydrogen peroxide and the like can be mentioned.
Examples of the redox type initiator include a combination of peroxide and ascorbic acid (a combination of hydrogen peroxide solution and ascorbic acid, etc.), a combination of a peroxide and an iron (II) salt (a hydrogen peroxide solution and Iron (II) salt and the like), persulfate and sodium bisulfite, and the like.

The amount of the polymerization initiator used can be appropriately selected depending on the type of the initiator, the type of the monomer (composition of the monomer components), the polymerization conditions, and the like. The amount of the polymerization initiator used is, for example, about 0.0005 to 1 part by weight, preferably about 0.001 to 0.5 part by weight, based on 100 parts by weight of the monomer raw material. The amount is preferably 002 to 0.3 parts by weight, more preferably 0.005 to 0.1 parts by weight.

In the emulsion polymerization, various conventionally known chain transfer agents (which can be understood as a molecular weight modifier or a polymerization degree modifier) can be used as necessary. The chain transfer agents may be used alone or in combination of two or more. Examples of chain transfer agents include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, glycidyl mercaptan, 2-mercaptoethanol, mercaptoacetic acid, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. Classes can be preferably used. When a chain transfer agent is used, the amount thereof may be, for example, about 0.01 to 1 part by weight, and may be 0.02 to 0.1 part by weight, based on 100 parts by weight of all the monomer components. Is preferred, and more preferably 0.03 to 0.07 parts by weight. The technique disclosed herein can be preferably carried out even in a mode without using a chain transfer agent.

The surfactant (emulsifier) used for emulsion polymerization is not particularly limited, and known anionic surfactants, nonionic surfactants and the like can be used. You may use the surfactant which has a radically polymerizable functional group. Hereinafter, the surfactant having a radically polymerizable functional group is also referred to as a reactive (polymerizable) surfactant. On the other hand, a general surfactant having no radically polymerizable functional group may be referred to as a non-reactive (non-polymerizable) surfactant. The surfactants may be used alone or in combination of two or more. The amount of the surfactant used is preferably about 0.1 parts by weight or more (eg, about 0.5 parts by weight or more) based on 100 parts by weight of all the monomer components, and 100 parts by weight of all the monomer components. It is preferable that the total amount be about 10 parts by weight or less (for example, about 5 parts by weight or less).

Examples of non-reactive surfactants include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether ether, ammonium polyoxyethylene alkylphenyl ether sulfate, polyoxy Anionic emulsifiers such as sodium ethylene alkylphenyl ether sulfate and sodium polyoxyethylene alkyl sulfosuccinate; nonionics such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block polymer System emulsifiers; and the like.

The reactive surfactant is not particularly limited as long as it has a radically polymerizable functional group. For example, it may be a reactive surfactant having a structure in which a radically polymerizable functional group is introduced into the above-mentioned anionic surfactant or nonionic surfactant. Examples of the radically polymerizable functional group include a vinyl group, a propenyl group, an isopropenyl group, a vinyl ether group (vinyloxy group), an allyl ether group (allyloxy group) and the like. The concept of the propenyl group as used herein includes a 1-propenyl group (CH ₃ —CH═CH—) and a 2-propenyl group (CH ₂ ═CH—CH ₂ —; sometimes referred to as an allyl group). included.

Examples of the anionic reactive surfactant include polyoxyethylene (allyloxymethyl) alkyl ether sulfate (for example, ammonium salt), polyoxyethylene nonylpropenyl phenyl ether sulfate (for example, ammonium salt), alkylallyl sulfosuccinic acid. Examples thereof include salts (for example, sodium salt), methacryloxy polyoxypropylene sulfate ester salt (for example, sodium salt), polyoxyalkylene alkenyl ether sulfate (for example, ammonium salt in which the terminal of the alkenyl group is an isopropenyl group), and the like. When the anionic reactive surfactant forms a salt, the salt may be a metal salt such as sodium salt or a non-metal salt such as ammonium salt or amine salt.
Examples of the nonionic reactive surfactant include polyoxyethylene nonylpropenyl phenyl ether.

Although not particularly limited, in some embodiments, a reactive surfactant having an oxyethylene chain may be preferably used. Here, the oxyethylene chain refers to a repeating structure of oxyethylene units, that is, a structural portion represented by —(C ₂ H ₄ O) _n —. n represents the number of repeating oxyethylene units. For example, a reactive surfactant having a repeating number n of about 5 to 30 (for example, 8 to 25) is preferable.

From the viewpoint of polymerization stability during emulsion polymerization, in some embodiments, a reactive surfactant having a propenyl group can be preferably adopted. Reactive surfactants having a propenyl group and an oxyethylene chain are particularly preferred.

In some aspects, an anionic reactive surfactant (for example, an anionic reactive surfactant having an oxyethylene chain) can be preferably used from the viewpoint of emulsification performance and the like. When the anionic reactive surfactant forms a salt, the salt is preferably a non-metal salt, and particularly preferably an ammonium salt.
When using a nonionic reactive surfactant, other surfactants such as anionic reactive surfactant, anionic non-reactive surfactant, nonionic non-reactive surfactant, etc. When used in combination with, more preferable results can be realized.

By subjecting the monomer raw material to emulsion polymerization in the presence of a reactive surfactant having a radically polymerizable functional group, the reactive surfactant can react and be incorporated into a base polymer (eg, acrylic polymer). The reactive surfactant incorporated in the base polymer is less likely to bleed out on the surface of the pressure-sensitive adhesive layer because its movement within the pressure-sensitive adhesive layer is limited. Therefore, the use of the reactive surfactant can suppress the bleed-out of the low molecular weight compound to the surface of the pressure-sensitive adhesive layer. This is preferable from the viewpoint of low contamination. From the viewpoint of achieving a more excellent low contamination property, an embodiment in which only a reactive surfactant is used as a surfactant during emulsion polymerization can be preferably adopted.

The pressure-sensitive adhesive layer of the protective sheet disclosed herein may be a pressure-sensitive adhesive layer formed from various forms of pressure-sensitive adhesive compositions. As the form of the pressure-sensitive adhesive composition, for example, a composition in which a pressure-sensitive adhesive (pressure-sensitive adhesive component) is contained in an organic solvent (solvent-type pressure-sensitive adhesive composition), a form in which at least a part of the pressure-sensitive adhesive is dispersed in an aqueous solvent Composition (water-dispersible pressure-sensitive adhesive composition), composition prepared to form a pressure-sensitive adhesive by curing with active energy rays such as ultraviolet rays and radiation (active energy ray-curable pressure-sensitive adhesive composition), heating Examples thereof include hot-melt pressure-sensitive adhesive compositions which are applied in a molten state and form a pressure-sensitive adhesive when cooled to around room temperature.
From the viewpoint of reducing environmental load, a water-dispersed pressure-sensitive adhesive composition can be preferably used. As a preferred example of such a water-dispersed pressure-sensitive adhesive composition, a water-dispersed pressure-sensitive adhesive composition containing an acrylic polymer as a base polymer (acrylic water-dispersed pressure-sensitive adhesive composition, typically acrylic emulsion-type pressure-sensitive adhesive) Composition). From the viewpoint of adhesive properties, solvent-based adhesive compositions are preferred. The hot-melt pressure-sensitive adhesive composition that does not require the use of a solvent is advantageous in that it is easy to handle in the production process.

(Crosslinking agent)
In the technique disclosed herein, the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer preferably contains a crosslinking agent. By using the crosslinking agent, the surface hardness of the pressure-sensitive adhesive layer can be appropriately adjusted. The type of crosslinking agent used is not particularly limited, and can be appropriately selected from conventionally known crosslinking agents.

Specific examples of the crosslinking agent include oxazoline-based crosslinking agents, aziridine-based crosslinking agents, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents. , A metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, a hydrazine-based crosslinking agent, an amine-based crosslinking agent, and a silane coupling agent. These may be used alone or in combination of two or more. For example, it is preferable to use one kind or two or more kinds selected from the group consisting of an oxazoline type crosslinking agent, an aziridine type crosslinking agent, an isocyanate type crosslinking agent and an epoxy type crosslinking agent. Of these, oxazoline-based crosslinking agents, isocyanate-based crosslinking agents, and epoxy-based crosslinking agents are more preferable. In the embodiment using the water-dispersed pressure-sensitive adhesive composition, a water-soluble or dispersible crosslinking agent is preferable, and a water-soluble (that is, water-soluble) crosslinking agent is particularly preferable.

As the oxazoline-based cross-linking agent, one having one or more oxazoline groups in one molecule can be used without particular limitation. In the water-dispersed pressure-sensitive adhesive composition, it is preferable to use an oxazoline-based crosslinking agent that can be dissolved or dispersed in water.
The oxazoline group may be any of a 2-oxazoline group, a 3-oxazoline group and a 4-oxazoline group. An oxazoline-based crosslinking agent having a 2-oxazoline group can be preferably used. For example, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4- A water-soluble copolymer or a water-dispersible copolymer obtained by copolymerizing an addition-polymerizable oxazoline such as methyl-2-oxazoline and 2-isopropenyl-5-ethyl-2-oxazoline with another monomer , And can be used as an oxazoline-based crosslinking agent.
Examples of commercially available products of the oxazoline-based cross-linking agent include trade names “Epocros WS-500”, “Epocros WS-700”, “Epocros K-2010E”, “Epocros K-2020E”, and “Epocros K-” manufactured by Nippon Shokubai Co., Ltd. 2030E” and the like.

Examples of the aziridine crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl)propionate] and trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)]. To be Examples of commercially available products of the aziridine crosslinking agent include "Chemite PZ-33" and "Chemite DZ-22E" manufactured by Nippon Shokubai Co., Ltd.

As an example of the isocyanate cross-linking agent, a bifunctional or higher polyfunctional isocyanate compound can be used. For example, aromatic isocyanate such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, diphenylmethane diisocyanate; alicyclic isocyanate such as isophorone diisocyanate; aliphatic such as hexamethylene diisocyanate Isocyanate; and the like. As commercial products, trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name “Coronate L”), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name “ Coronate HL"), an isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX") and the like can be exemplified. In the water-dispersed PSA composition, it is preferable to use an isocyanate-based crosslinking agent that can be dissolved or dispersed in water. For example, a water-soluble, water-dispersible or self-emulsifying type isocyanate crosslinking agent can be preferably used. A so-called blocked isocyanate type isocyanate cross-linking agent in which an isocyanate group is blocked can be preferably used.

As the epoxy-based cross-linking agent, one having two or more epoxy groups in one molecule can be used without particular limitation. An epoxy-based cross-linking agent having 3 to 5 epoxy groups in one molecule is preferable. In the water-dispersed PSA composition, it is preferable to use an epoxy-based crosslinking agent that can be dissolved or dispersed in water.
Specific examples of the epoxy-based cross-linking agent include N,N,N′,N′-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexane. Examples thereof include diol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether and the like.
Commercially available epoxy crosslinking agents are trade names "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi Gas Chemical Co., Inc., trade names "Epiclone CR-5L" manufactured by DIC, and products manufactured by Nagase ChemteX. Examples include the name "Denacol EX-512" and the trade name "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd.

As the carbodiimide cross-linking agent, a low molecular compound or a high molecular compound having two or more carbodiimide groups can be used. In the water-dispersed pressure-sensitive adhesive composition, it is preferable to use a carbodiimide-based crosslinking agent that can be dissolved or dispersed in water. Examples of commercially available carbodiimide crosslinking agents include carbodilite V series (aqueous solution type) such as "carbodilite V-02", "carbodilite V-02-L2", and "carbodilite V-04" manufactured by Nisshinbo Co., Ltd. Carbodilite series such as carbodilite E series (water dispersion type) such as carbodilite E-01”, “carbodilite E-02”, and “carbodilite E-04” can be mentioned.

The content of the cross-linking agent (total amount of the cross-linking agent) in the pressure-sensitive adhesive composition disclosed herein is not particularly limited, and in consideration of the composition and the molecular weight of the base polymer, an appropriate property may be obtained after the cross-linking. Can be set. Although not particularly limited, it is appropriate that the amount of the crosslinking agent used with respect to 100 parts by weight of the base polymer (typically an acrylic polymer) is about 0.01 parts by weight or more, and about 0.1 parts by weight or more, It is preferably about 1 part by weight or more (for example, about 2 parts by weight or more). From the viewpoint of adhesiveness and the like, the amount of the cross-linking agent used is about 15 parts by weight or less (preferably about 10 parts by weight or less, for example, about 5 parts by weight or less) with respect to 100 parts by weight of the base polymer. It is suitable, and from the viewpoint of enhancing the adhesion to the adherend, it is preferably about 4 parts by weight or less, more preferably less than 3.5 parts by weight, further preferably less than 3 parts by weight.

(Phosphate ester)
The pressure-sensitive adhesive composition (and thus the pressure-sensitive adhesive layer) disclosed herein may contain a phosphoric acid ester. Examples of the phosphoric acid ester include alkyl phosphoric acid esters such as lauryl phosphoric acid and lauryl phosphate, phosphoric acid esters having an oxyethylene chain, and salts thereof. The salt may be, for example, a sodium salt, a potassium salt, a barium salt, a triethanolamine salt or the like of the phosphoric acid ester. Hereinafter, unless otherwise specified, “phosphate ester” is used to include a salt. Above all, it is more preferable to use a phosphoric acid ester having an oxyethylene chain. The phosphoric acid ester having an oxyethylene chain mainly suppresses an increase in the adhesive force with time (that is, improves the stability of the adhesive force), while at the same time adding water or acid between the adhesive layer and the surface of the adherend. It is possible to prevent entry of corrosion-inducing components such as alkali. Here, the oxyethylene chain refers to a chain-like structural portion that contains at least one ethylene oxide (EO) unit and may further contain another oxyalkylene unit (for example, an oxyalkylene unit having about 3 to 6 carbon atoms). Say. One preferable example of the phosphoric acid ester having an oxyethylene chain is a phosphoric acid ester having an oxyethylene chain constituted by EO units or repeating thereof. For example, a phosphoric acid ester represented by the following general formula (a) or a salt thereof can be preferably adopted.

In the general formula (a), R ¹ is —OH or —(OCH ₂ CH ₂ ) _n OR ³ , and R ² represents —(OCH ₂ CH ₂ ) _m OR ⁴ . n and m represent the number of moles of EO added. The EO-added mole number n is an integer of 1 to 30, typically an integer of about 1 to 20, preferably an integer of about 1 to 10, and may be an integer of about 1 to 8, for example. The number of moles of EO added n is preferably an integer of about 1 to 6, and more preferably an integer of about 1 to 4 (eg, 2 to 4). In the general formula (a), the number EO-added moles m can typically be approximately the same as the number EO-added moles n. n and m may be the same or different. R ³ and R ⁴ are monovalent organic groups (typically hydrocarbon groups), and are, for example, each independently selected from an alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group and an arylalkyl group. Can be a group that is R ³ and R ⁴ are preferably linear or branched alkyl groups, aryl groups or alkylaryl groups. R ³ and R ⁴ are each independently an organic group having 1 to 30 carbon atoms, and may be an organic group having 6 or more carbon atoms (preferably 8 or more, for example 11 or more). In a preferred embodiment, R ³ and R ⁴ may be an organic group having 20 or less carbon atoms, preferably 18 or less carbon atoms, for example 15 or less carbon atoms. The salt of the phosphoric acid ester represented by the general formula (a) may be, for example, sodium salt, potassium salt, barium salt, triethanolamine salt or the like of these phosphoric acid ester. The phosphate ester may be used alone or in combination of two or more.

Examples of the phosphoric acid ester include polyoxyethylene tridecyl ether phosphoric acid, polyoxyethylene lauryl ether phosphoric acid, polyoxyethylene octadecyl ether phosphoric acid, and the like; polyoxyethylene alkyl phosphoric acid ester; polyoxyethylene nonylphenyl ether phosphoric acid. , Polyoxyethylene octyl phenyl ether phosphoric acid, polyoxyethylene dinonyl phenyl ether phosphoric acid, polyoxyethylene dioctyl phenyl ether phosphoric acid, etc., and the like. In one aspect, a phosphoric acid ester having a molecular weight of 150 to 5000 can be preferably used.

The amount of the phosphate ester used can be, for example, about 0.05 part by weight or more, and preferably about 0.1 part by weight or more, relative to 100 parts by weight of the base polymer (eg, acrylic polymer). More preferably, it is about 0.3 parts by weight or more (for example, about 0.5 parts by weight or more). From the viewpoint of low contamination of the surface of the adherend, the amount of the phosphoric acid ester used is about 30 parts by weight or less (eg, 20 parts by weight or less) with respect to 100 parts by weight of the base polymer (eg, acrylic polymer). It is suitable, and is preferably about 10 parts by weight or less, more preferably about 5 parts by weight or less, further preferably about 3 parts by weight or less, particularly preferably about 2 parts by weight or less (for example, 1 part by weight or less).

(anti-rust)
The pressure-sensitive adhesive layer according to a preferred embodiment may contain a rust preventive agent. The rust preventive agent is not particularly limited, and examples thereof include amine compounds, azole compounds, nitrites, ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, and dicyclohexylamine benzoate. Examples thereof include acid salts, urea, urotropine, thiourea, phenyl carbamate, cyclohexyl ammonium-N-cyclohexyl carbamate (CHC) and the like. These rust preventives may be used alone or in combination of two or more. Of these, amine compounds and azole compounds are preferable.

The content of the rust preventive agent (for example, amine compound (amine rust preventive) or azole compound (azole rust preventive)) is not particularly limited, and is, for example, 0.01 part by weight based on 100 parts by weight of the base polymer. It can be more than 1 part (typically more than 0.05 part by weight). From the viewpoint of obtaining a better effect of preventing corrosion and the like, the content may be 0.1 parts by weight or more, 0.3 parts by weight or more, and 0.5 parts by weight or more. On the other hand, the content of the rust preventive agent is appropriately less than 8 parts by weight based on 100 parts by weight of the base polymer from the viewpoints of preventing corrosion and the like due to the contained components and cohesive strength of the pressure-sensitive adhesive. The amount may be not more than 5 parts by weight, preferably not more than 5 parts by weight, for example not more than 3 parts by weight, or not more than 1 part by weight. The technique disclosed herein can be preferably carried out even in a mode in which a rust preventive agent is not substantially used.

In embodiments where the adhesive layer is colored, the adhesive layer may typically include a colorant. The kind of the colorant is not particularly limited, and for example, one kind or two or more kinds of the above-mentioned colorants can be preferably used. The amount of the colorant compounded is not particularly limited, and is appropriately 0.3% by weight or more of the adhesive layer, preferably 0.5% by weight or more, and more preferably 1.0% by weight or more. The content of the colorant can be, for example, less than 10% by weight, preferably less than 5% by weight, more preferably less than 3.5% by weight, still more preferably less than 3.0% by weight. The technique disclosed here can be preferably implemented in a mode in which the pressure-sensitive adhesive layer does not substantially contain a colorant. In this aspect, the pressure-sensitive adhesive layer may be uncolored.

The pressure-sensitive adhesive composition may contain a known tackifier such as a rosin-based tackifier, a terpene-based tackifier, or a hydrocarbon-based tackifier, if necessary. From the viewpoint of preventing the peel strength from becoming too high, the amount of the tackifier used is preferably about 5 parts by weight or less, and more preferably about 1 part by weight or less, relative to 100 parts by weight of the base polymer. .. The protective sheet disclosed herein can effectively control the adhesive force through the composition and Tg of the base polymer, the gel fraction of the pressure-sensitive adhesive, and the like, and thus can be preferably carried out even in a mode where no tackifier is used.

The pressure-sensitive adhesive composition (and by extension, the pressure-sensitive adhesive layer) is, if necessary, a viscosity modifier (thickener, etc.), a cross-linking aid, a plasticizer, a softening agent, a filler, an antistatic agent, an antiaging agent, an ultraviolet ray. It may contain various optional additives generally used in the field of pressure-sensitive adhesive compositions, such as an absorber, an antioxidant, a light stabilizer and a defoaming agent. Further, as the above-mentioned optional additive, an arbitrary polymer component different from the base polymer (for example, an acrylic polymer) may be used. The content of such an optional polymer is, for example, about 10% by weight or less, for example, about 1% by weight or less) in the PSA composition, and the PSA composition disclosed herein is substantially the same as the above optional polymer. May not be included in. Further, the pressure-sensitive adhesive composition according to one aspect may be one in which the content of a plasticizer such as a fatty acid ester is limited to less than 10 parts by weight (for example, less than 1 part by weight) with respect to 100 parts by weight of the base polymer. .. Typically, the adhesive composition may be substantially free of plasticizer. Further, the technology disclosed herein can be preferably implemented in a mode in which an antistatic agent (which may be a conductive agent) such as an ionic compound (for example, an ionic liquid or an alkali metal salt) is not substantially contained. Regarding other matters regarding the various optional additives, conventionally known various additives, various methods, and the like can be appropriately adopted based on common general technical knowledge, and do not particularly characterize the present invention, and thus detailed description thereof is omitted. To do.

In the technique disclosed herein, in an embodiment in which a water-dispersed pressure-sensitive adhesive composition is used to form a pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition is, for example, an acrylic polymer obtained by emulsion polymerization using a surfactant. It can be prepared by mixing other components used as necessary (for example, a cross-linking agent, a phosphoric acid ester, etc.) with the water dispersion liquid. The above aqueous dispersion may contain the below-mentioned aqueous liquid. For example, it is preferable to use a polymerization reaction liquid obtained by emulsion polymerization, or one obtained by subjecting the polymerization reaction liquid to treatment such as pH adjustment (for example, neutralization), adjustment of non-volatile content, adjustment of viscosity, etc. as necessary. it can. Usually, the dispersion stability of the emulsion can be improved by adding a neutralizing agent such as aqueous ammonia to the polymerization reaction liquid to adjust the pH to an appropriate range (for example, a pH range of about 6 to 9).

Although not particularly limited, the nonvolatile content (NV; nonvolatile content) of the pressure-sensitive adhesive composition is, for example, about 20% by weight or more (typically about 30% by weight or more, preferably from the viewpoint of drying efficiency). It can be about 40% by weight or more), and can be about 75% by weight or less (typically about 70% by weight or less, preferably about 60% by weight or less) from the viewpoint of coatability and the like. ..

As a method for providing the pressure-sensitive adhesive layer on the supporting base material which becomes the base material layer, a method of directly applying (typically coating) the above-mentioned pressure-sensitive adhesive composition to the supporting base material and performing a curing treatment (direct method) ) Or an appropriate release surface (for example, the surface of a transfer sheet having releasability), and by applying a curing treatment to the pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer is formed on the release surface. A method in which the layer is attached to a supporting base material and transferred (transfer method) or the like can be used. The curing treatment may be one or more treatments selected from drying (heating), cooling, crosslinking, additional copolymerization reaction, aging and the like. For example, the treatment of simply drying the pressure-sensitive adhesive composition containing a solvent (heat treatment or the like) or the treatment of simply cooling (solidifying) the pressure-sensitive adhesive composition in a heating and melting state is also included in the curing treatment here. May be included. When the curing treatment includes two or more treatments (for example, drying and crosslinking), these treatments may be performed simultaneously or may be performed in multiple steps.

The pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, and a spray coater. From the viewpoint of accelerating the crosslinking reaction, improving the production efficiency, etc., it is preferable to dry the pressure-sensitive adhesive composition under heating. A drying temperature of, for example, about 40° C. to 150° C. can be adopted, although it depends on the type of the object (supporting substrate or the like) to which the pressure-sensitive adhesive composition is applied.

The pressure-sensitive adhesive layer constituting the protective sheet disclosed herein is not particularly limited, but the chloride ion amount measured by hot water extraction is about 105 μg or less per 1 g of the pressure-sensitive adhesive (layer). Appropriate. This makes it possible to prevent corrosion and the like in the Low-E glass plate that is the protection target for a long period of time. The chloride ion amount per 1 g of the adhesive (layer) is preferably about 100 μg or less, more preferably about 95 μg or less, further preferably about 90 μg or less, particularly preferably about 85 μg or less, about 75 μg or less (about 70 μg or less. ). The lower limit of the amount of chloride ions per 1 g of the pressure-sensitive adhesive (layer) is ideally 0 μg, but from the viewpoint of production efficiency, practically acceptable level, etc., it may be about 1 μg or more, about 10 μg. It may be more than 50 μg. The chloride ion amount per 1 g of the pressure-sensitive adhesive (layer) is measured by the following method. Alternatively, the chloride ion amount in the protective sheet and the base material layer is measured by hot water extraction, and the chloride ion amount from the pressure-sensitive adhesive layer is calculated from the difference in the chloride ion amount between the two, and the obtained value is used as a unit. It may be obtained by converting it into a value per weight of the adhesive (layer).

[Amount of chloride ions in adhesive (layer)]
The protective sheet to be measured is thoroughly washed with pure water, cut into a sheet area of 200 cm ² and only the adhesive is collected. The collected adhesive is put in a polypropylene (PP) container and weighed. 25 mL of pure water is added to a PP container, and extraction with heating is performed at 120° C. for 1 hour using a dryer. With respect to the obtained extract, the amount of chloride ion in the extract was quantified using a chloride ion standard solution by the same method as the ion chromatography method described later, and chloride ion per 1 g of the adhesive used for extraction Find the amount.

(Gel fraction)
The weight fraction (gel fraction) of the ethyl acetate insoluble matter in the pressure-sensitive adhesive layer disclosed herein is not particularly limited and may be, for example, about 40% or more (typically about 50% or more). In one aspect, from the viewpoint of obtaining a predetermined or higher surface hardness, the gel fraction of the pressure-sensitive adhesive layer is suitably about 60% or more, preferably about 80% or more, and about 90% or more (for example, about 91% or more. , And about 93% or more) is more preferable. The gel fraction of the pressure-sensitive adhesive layer may be, for example, about 95% or more (eg, about 98% or more). The increase in the gel fraction tends to improve the cohesiveness of the pressure-sensitive adhesive and suppress the temporal adhesive force. The upper limit of the gel fraction is 100% in principle. In some embodiments, the gel fraction can be, for example, about 98% or less, and can be about 95% or less (eg, about 90% or less). The gel fraction can be adjusted by, for example, the composition of the base polymer, the polymerization method and the polymerization conditions of the base polymer, the molecular weight of the base polymer, the presence or absence of the use of a crosslinking agent, and the selection of the type and the amount thereof. The gel fraction is measured by the following method.

(Swelling degree)
The swelling degree of the pressure-sensitive adhesive layer disclosed herein is not particularly limited and may be about 30 times or less. The degree of swelling is appropriately about 20 times or less, preferably about 15 times or less, more preferably about 12 times or less, for example, about 10 times or less, from the viewpoint of obtaining a surface hardness of a predetermined value or more. It may be about 8 times or less. The lower limit of the degree of swelling is in principle 1 time and may be approximately 3 times or more, for example approximately 5 times or more. The degree of swelling can be adjusted by, for example, the molecular weight of the base polymer, the type (distance between functional groups) of the crosslinking agent, the amount used, and the like. The degree of swelling is measured by the following method. The same method is adopted for the examples described later.

[Measurement of gel fraction and swelling degree]
About 0.1 g of the adhesive layer sample (weight W ₁ ) was wrapped in a purse-like shape with a porous polytetrafluoroethylene membrane (weight W ₂ ) having an average pore diameter of 0.2 μm, and the mouth was tied with a tacho thread (weight W ₃ ). .. As the above-mentioned porous polytetrafluoroethylene film, a product name “Nitoflon (registered trademark) NTF1122” (manufactured by Nitto Denko Corporation, average pore diameter 0.2 μm, porosity 75%, thickness 85 μm) or its equivalent is used. The package is dipped in 50 mL of ethyl acetate and kept at room temperature (typically 23° C.) for 7 days, then the package is taken out, the ethyl acetate adhering to the outer surface is wiped off, and the weight of the package (W ₄ ) To measure. Then, the package is dried at 130° C. for 2 hours, and the weight (W ₅ ) of the package is measured. The gel fraction and swelling degree of the pressure-sensitive adhesive layer can be calculated by substituting each value into the following equation.
Gel fraction (%)=[(W ₅ −W ₂ −W ₃ )/W ₁ ]×100
Swelling degree (times)=(W ₄ -W ₂ -W ₃ )/(W ₅ -W ₂ -W ₃ )

<Base material layer>
The protective sheet disclosed herein may include a substrate layer. As the base material layer, a resin film, a rubber sheet, a foam sheet, a composite of these, or the like can be used. Examples of the rubber sheet include a natural rubber sheet and a butyl rubber sheet. Examples of the foam sheet include a polyurethane foam sheet, a chloroprene rubber sheet, and the like.

The technique disclosed here can be preferably applied to a protective sheet having a resin film as a base layer. The "resin film" here is typically a film formed by molding a resin composition containing a resin component as shown below into a film, and is distinguished from so-called non-woven fabrics and woven fabrics. (That is, the concept excluding non-woven fabric and woven fabric). A substantially non-foamed resin film is preferred. Here, the non-foamed resin film refers to a resin film that has not been intentionally treated to form a foam, and specifically, has a foaming ratio of less than about 1.1 times (for example, 1.05 times). Less, typically less than 1.01 times) resin film.

Examples of the resin component constituting the resin film include polyolefin resin (polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc.), polyvinyl chloride resin (typically soft poly Vinyl chloride resin), polyvinyl acetate resin, polyurethane resin (ether polyurethane, ester polyurethane, carbonate polyurethane, etc.), urethane (meth)acrylate resin, thermoplastic elastomer (olefin elastomer, styrene elastomer, Acrylic elastomer, etc.), polyester resin (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc.), polycarbonate resin, polyamide resin, polyimide resin, fluorine resin, cellophane resin, etc. Resin etc. are mentioned. These resin components may be used alone or in combination of two or more. Suitable examples of the resin film include a polyolefin resin film, a polyester resin film, and a vinyl chloride resin film.

Although not particularly limited, in the protective sheet according to one aspect, one or more selected from the group consisting of a polyolefin resin, a polyvinyl chloride resin, a polyurethane resin, a thermoplastic elastomer and a polyester resin. A base material layer containing the above resin component as a main component (typically, a base material layer containing such a resin component in a proportion exceeding 50% by weight) can be preferably used. In another aspect, a base material layer including a polyolefin-based resin layer, a polyester-based resin layer, or a polyvinyl chloride-based resin layer can be preferably used in consideration of performance, handleability, cost, and the like. Among the above resin materials, polyolefin-based resins, polyurethane-based resins and olefin-based elastomers are preferable from the viewpoint of thermal stability and light weight, and polyolefin-based resins and olefin-based elastomers are particularly preferable from the viewpoint of handleability.

The protective sheet disclosed herein is preferably carried out in an aspect including a base material layer containing a polyolefin-based resin as a main component (in a proportion exceeding 50% by weight), that is, an embodiment using a polyolefin-based resin film as the base material layer. obtain. For example, a polyolefin resin film in which 50% by weight or more of the entire base material layer is a polyethylene (PE) resin and/or a polypropylene (PP) resin can be preferably used. In other words, the total amount of the PE resin and the PP resin in the polyolefin resin film may account for 50% by weight or more of the entire base material layer. The polyolefin resin film may be a blend of PE resin and PP resin.

The PP resin may be mainly composed of various polymers (propylene-based polymers) containing propylene as a constituent monomer. It may be a PP resin substantially composed of one or two or more propylene-based polymers. In addition to homopolypropylene, the concept of propylene-based polymer includes a random copolymer of propylene and another monomer (random polypropylene) or a block copolymer (block polypropylene). The concept of the propylene-based polymer here includes, for example, the following.
A homopolymer of propylene (homopolypropylene). For example, isotactic polypropylene.
A random copolymer (random polypropylene) of propylene and another α-olefin (typically, one or more selected from ethylene and α-olefins having 4 to 10 carbon atoms). Preferably, a random polypropylene containing propylene as a main monomer (main constituent monomer, that is, a component occupying 50% by weight or more of the whole monomer).
A copolymer (block polypropylene) obtained by block copolymerizing propylene with another α-olefin (typically, one or more selected from ethylene and α-olefins having 4 to 10 carbon atoms). Preferably, a block polypropylene containing propylene as a main monomer (main constituent monomer, that is, a component accounting for 50% by weight or more of the whole monomer).

The PE resin may be mainly composed of various polymers (ethylene-based polymers) containing ethylene as a constituent monomer. It may be a PE resin substantially composed of one or two or more ethylene-based polymers. The ethylene-based polymer may be a homopolymer of ethylene, which is obtained by copolymerizing ethylene as a main monomer with another α-olefin as a sub-monomer (random copolymerization, block copolymerization, etc.). Good. Preferable examples of the α-olefin include propylene, 1-butene (which may be branched 1-butene), 1-hexene, 4-methyl-1-pentene, 1-octene and the like having 3 to 10 carbon atoms. .Alpha.-olefins. For example, a PE resin containing an ethylene-based polymer as a main component, which is copolymerized with the α-olefin as the sub-monomer at a ratio of about 10% by weight or less (typically about 5% by weight or less) can be preferably used.

The PE resin also includes a PE resin containing a copolymer of ethylene with a monomer (functional group-containing monomer) having another functional group in addition to the polymerizable functional group, and a copolymer of the functional group-containing monomer with an ethylene-based polymer. It may be PE resin or the like. Examples of the copolymer of ethylene and a functional group-containing monomer include ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-acrylic. Methyl acid copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-(meth)acrylic acid (that is, acrylic acid and/or methacrylic acid). ) Examples thereof include those obtained by crosslinking the copolymer with metal ions.

The density of the PE resin is not particularly limited. The concept of the PE resin as used herein includes any of high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). In one aspect, the density of the PE resin may be, for example, about 0.90 to 0.94 g/cm ³ . Preferred PE resins include LDPE and LLDPE. The PE resin may include one or more kinds of LDPE and one or more kinds of LLDPE. The blending ratio of each LDPE or LLDPE and the blending ratio of LDPE and LLDPE are not particularly limited, and can be appropriately set so that the PE resin exhibits desired characteristics. As the base material layer of the protective sheet disclosed herein, an LLDPE film or LDPE containing LLDPE in an amount of more than 50% by weight (preferably about 75% by weight or more, for example, about 90% by weight or more) is added to more than 50% by weight ( A polyethylene resin film such as an LDPE film, which is preferably contained in a proportion of about 75% by weight or more, for example about 90% by weight or more) can be preferably used. A laminated resin film containing such a polyethylene resin film as a constituent may be used.

In a preferred embodiment, the base material layer contains a colorant. Typically, the base material layer may include a resin film containing a colorant. This makes it possible to preferably obtain a protective sheet having a substantially uniform coloring on the entire sheet surface. More specifically, as the base material layer disclosed herein, a base material layer made of a resin film in which a colorant is kneaded can be preferably used. Here, the resin film in which the colorant is kneaded refers to a resin film in which the colorant is mixed in the main constituent material (typically the resin material) of the resin film. The colorant is substantially contained in the resin film in a dispersed state. Further, the colorant-containing resin film is advantageous in terms of productivity as compared with the aspect in which the color layer is provided. The colorant-containing base material layer (for example, a colorant-containing resin film) can be said to be colored in itself, and can be referred to as a colored base material layer (for example, a colored resin film).

The amount of the colorant used in the base material layer (preferably the resin film) is not particularly limited, and may be an amount appropriately adjusted so as to achieve desired transparency and colorability. The amount of the colorant used is suitably about 0.1 to 30% by weight of the weight of the base material layer, for example 0.1 to 25% by weight (typically 0.1 to 20% by weight). It can be a degree.

The resin film (for example, a polyolefin resin film) used as the base material layer of the protective sheet disclosed herein may optionally contain appropriate components that are allowed to be contained in the base material layer. For example, additives such as a filler, an antioxidant, a light stabilizer (which means a radical scavenger, an ultraviolet absorber, etc.), an antistatic agent, a plasticizer, a slip agent, an antiblocking agent, etc. are appropriately mixed. can do. The amount of each additive compounded can be, for example, approximately the same as the amount normally compounded in the field of a resin film used as a base layer or the like of a protective sheet.

The base material layer may have a single-layer structure or a multi-layer structure having two layers, three layers or more. In the case of a multilayer structure, at least one layer (preferably all layers) is preferably any one of the resin films described above. For example, a base material layer having a structure in which 75% or more (more preferably 90% or more) of the thickness is a single-layer or multi-layer (typically single-layer) polyolefin resin film is preferable. The entire base material layer may be a base material layer made of a single-layer or multi-layer polyolefin resin film. From the viewpoint of economy, a base material layer made of a resin film having a single-layer structure (for example, LLDPE film, LDPE film, etc.) can be preferably used.

The method for producing the base material layer may be any conventionally known method, and is not particularly limited. For example, when a resin film is adopted as the base material layer, a resin film produced by appropriately adopting a conventionally known general film forming method such as inflation molding, extrusion molding, T die cast molding, calender roll molding, etc. Can be used.

In a constitution in which at least one surface of the base material layer (surface on the side of the adhesive layer) is the surface of the resin film, the surface of the resin film is subjected to corona discharge treatment, plasma treatment, ozone exposure, flame exposure, ultraviolet irradiation treatment. Conventionally known surface treatments such as acid treatment, alkali treatment, and application of an undercoat agent may be applied. Such a surface treatment may be a treatment for improving the adhesion between the base material layer and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer to the base material layer. In the aspect in which the polyolefin-based resin film is used as the base material layer, it is particularly significant to perform the above surface treatment.

The total light transmittance of the base material layer disclosed herein is not particularly limited. Generally, the total light transmittance of the substrate layer is about 3% or more, for example about 5% or more (typically about 10% or more). From the viewpoint of the adherend visibility through the protective sheet, the total light transmittance is appropriately about 20% or more (for example, about 30% or more), preferably about 40% or more, and more preferably about 50%. As described above, it is more preferably about 60% or more, particularly preferably about 70% or more, and may be about 80% or more (for example, about 90% or more). The upper limit of the total light transmittance of the base material layer is not limited to a specific range, but from the viewpoint of the discriminability on the Low-E glass plate, it is suitable to be about 95% or less, and preferably Is about 90% or less, for example, about 80% or less, or about 70% or less.

The minimum transmittance of the base material layer disclosed herein at a wavelength of 450 to 800 nm is not particularly limited. The minimum transmittance at the wavelength of 450 to 800 nm is usually about 2% or more, for example about 5% or more, and about 10% or more (for example, about 20% or more) is suitable. By setting the minimum value of the transmittance in the wavelength range of 450 to 800 nm corresponding to the visible light region to a predetermined value or more, the visibility of the adherend through the protective sheet is improved. In a preferred embodiment, the minimum transmittance at a wavelength of 450 to 800 nm is about 30% or more, more preferably about 40% or more, even more preferably about 50% or more (for example, about 60% or more). Further, the minimum transmittance at the wavelength of 450 to 800 nm is appropriately about 95% or less, preferably about 90% or less, from the viewpoint of discriminating property on the Low-E glass plate, and for example, about 90% or less. It may be 80% or less, about 70% or less, about 60% or less, or about 50% or less.

The haze value of the base material layer is not limited to a specific range. Usually, the haze value of the base material layer is about 99 or less (for example, 90 or less). From the viewpoint of suppressing transparency and diffusion and reflection that affect visibility, the haze value is suitably about 50 or less, preferably about 30 or less, more preferably about 20 or less, and It may be 10 or less (for example, about 5 or less). The lower limit of the haze value is not particularly limited, and it is suitable to be about 1 or more (for example, about 5 or more), and for example, about 10 or more. In another aspect, the haze value may be about 20 or more, and may be more than 50 (for example, about 80 or more, and further about 90 or more). By setting the high haze value within the range in which the visibility of the adherend through the protective sheet is not impaired, the distinguishability of the protective sheet on the Low-E glass plate can be improved.

<Method for preparing adhesive composition>
The method for preparing the pressure-sensitive adhesive composition disclosed herein is not particularly limited, and a conventionally known or commonly used pressure-sensitive adhesive composition preparation method can be appropriately adopted. Although not particularly limited, the pressure-sensitive adhesive composition preparation method according to one embodiment has, for example, (a) an electric conductivity of less than 300 μS/cm; and (b) an amount of chloride ions less than 35 μg/mL. It is preferable to use an aqueous liquid satisfying at least one of the following. According to this method, a pressure-sensitive adhesive composition that can prevent corrosion and the like can be obtained. Such an adhesive composition is particularly preferably used for protecting Low-E glass plate.

(Preparation of aqueous liquid)
The method for preparing the pressure-sensitive adhesive composition according to one aspect may include a step of preparing the aqueous liquid. The aqueous liquid satisfying the above (a) and/or (b) is desired from surface water, raw water including ground water (which may be well water), tap water, and treated water obtained by performing known water treatment. It is possible to obtain an aqueous liquid satisfying the electric conductivity and/or the amount of chloride ions of (1) by selecting, for example, by analyzing as necessary.

In a preferred embodiment, the above-mentioned aqueous liquid is obtained by subjecting an aqueous liquid such as raw water (untreated aqueous liquid) to known treatment such as filtration, membrane separation, ion exchange, distillation, physical adsorption, electrolysis and the like. Among them, the treatment by membrane separation using a reverse osmosis membrane, a nanofiltration membrane, an ultrafiltration membrane, a microfiltration membrane or the like is more preferable, and a reverse osmosis membrane is particularly preferable. When ion exchange is adopted as the water treatment method, cation exchange (using cation exchange resin), anion exchange (using anion exchange resin), or a mixed system thereof can be used, but corrosion, etc. From the viewpoint of removing anions (typically chloride ions) which are considered to be the main cause of the above, when ion-exchanged water is used, it is preferable to employ anion exchange. In this aspect, the untreated aqueous liquid used in the treatment step has an electric conductivity of 300 μS/cm or more and a chloride ion amount of 35 μg/mL or more. The processing device is not particularly limited, and a known or common processing device can be used. The treatment condition is not limited to a specific condition as long as it is appropriately set depending on the untreated water, the device, and the required water quality.

(Preparation of adhesive composition)
Then, using the aqueous liquid prepared as described above, a polymer-containing liquid containing a polymer (which may be a base polymer) as an adhesive component is obtained. That is, the method disclosed herein may include a step of obtaining a polymer-containing liquid containing the aqueous liquid and the polymer. The usage form of the aqueous liquid is not particularly limited as long as it is used for preparing the pressure-sensitive adhesive composition, and the timing of use is also not particularly limited. The above aqueous liquid is also referred to as water for preparing the pressure-sensitive adhesive composition. Examples of the form of use of the water for preparation include use as water for polymerization in polymerization of the above-mentioned polymer and water for post-polymerization added after polymerization (post-added water). The resulting polymer-containing liquid may be used as it is as a pressure-sensitive adhesive composition, or a mixture of the polymer-containing liquid and additional components may be used as a pressure-sensitive adhesive composition. The PSA composition obtained by using the aqueous liquid may be in the form of a water-dispersed PSA composition in which at least a part (typically all) of the polymer is dispersed in the aqueous liquid. The details of the polymer (typically a base polymer) used in the pressure-sensitive adhesive composition, the details of the pressure-sensitive adhesive composition, and other matters relating to the preparation of the pressure-sensitive adhesive composition are as described above, and therefore, duplicate description will be given. Is omitted.

In a preferred embodiment, the above aqueous liquid is used as water for polymerization in emulsion polymerization. That is, the pressure-sensitive adhesive composition preparation method disclosed herein may include a step of performing emulsion polymerization in the presence of the aqueous liquid to obtain a polymer. The details of the polymer obtained by the emulsion polymerization are as described above, and thus the duplicate description is omitted.

(Characteristics of aqueous liquid)
In one aspect, the electrical conductivity of the aqueous liquid used for preparing the pressure-sensitive adhesive composition is not particularly limited. The chloride ions in the aqueous liquid are preferably limited to less than a predetermined amount, in which case the electrical conductivity of the aqueous liquid need not be less than 300 μS/cm. On the other hand, since the electrical conductivity correlates with the amount of ions in the aqueous liquid, the electrical conductivity of the aqueous liquid in another aspect is preferably less than 300 μS/cm from the viewpoint of limiting the amount of ions causing corrosion and the like. It is more preferably less than 200 μS/cm, further preferably less than 100 μS/cm, particularly preferably less than 50 μS/cm (eg less than 30 μS/cm, even less than 15 μS/cm). Such an aqueous liquid can be used as one having a corrosion preventing property without quantifying the amount of chloride ions which is considered to be a main cause of corrosion.

The lower limit of the electrical conductivity of the aqueous liquid used may be a theoretical lower limit value (around 0.05 μS/cm at room temperature), but considering the production efficiency and the practically acceptable level, it is about 1 μS/cm or more. May be about 5 μS/cm or more, about 10 μS/cm or more, about 50 μS/cm or more (for example, about 100 μS/cm or more, and further about 200 μS/cm or more). It may be.

The electric conductivity of the aqueous liquid is measured at room temperature (23°C) using a commercially available electric conductivity meter. Specifically, it can be measured using a portable electric conductivity meter “ES-71” manufactured by Horiba Ltd. or its equivalent.

In one aspect, it is preferable that the amount of chloride ions in the aqueous liquid used for preparing the pressure-sensitive adhesive composition is limited. Specifically, when the electric conductivity of the aqueous liquid is 300 μS/cm or more, the chloride ion amount thereof is preferably less than 35 μg/mL. As a result, a corrosion prevention effect can be realized. Although not particularly limited, the chloride ion amount in the aqueous liquid is preferably less than 35 μg/mL even when the electric conductivity thereof is less than 300 μS/cm. In that case, the aqueous liquid used in the preparation of the PSA composition disclosed herein contains less than 35 μg/mL of chloride ion, regardless of its electrical conductivity.

In one aspect, the chloride content of the aqueous liquid is suitably less than 35 μg/mL (eg less than 30 μg/mL), preferably less than 25 μg/mL, more preferably less than 20 μg/mL, even more preferably 15 μg. /ML, particularly preferably less than 10 μg/mL, most preferably less than 5 μg/mL, and may be less than 3 μg/mL (eg less than 1 μg/mL). The lower limit of the amount of chloride ions in the above aqueous liquid is ideally 0 μg/mL, but in consideration of production efficiency, practically acceptable level, etc., it may be approximately 1 μg/mL or more, approximately 3 μg. /ML or more.

In a preferred embodiment, the ratio (A _Cl /C) of the chloride ion amount A _Cl [μg/mL] to the electrical conductivity C [μS/cm] of the aqueous liquid is about ⅕ or less. When the ratio (A _Cl /C) is not more than the predetermined value, it means that the chloride ion amount is relatively low among all the ions. By setting the above ratio (A _Cl /C) to about 1/5 or less, it is possible to preferably realize both prevention of corrosion and the like and productivity. The above ratio (A _Cl /C) is more preferably about ⅛ or less, may be about 1/10 or less, and may be about 1/15 or less. The lower limit value of the ratio (A _Cl /C) is not particularly limited and may be about 1/30 or more (for example, about 1/20 or more).

It is desirable that the amount of sulfate ion of the aqueous liquid used for preparing the pressure-sensitive adhesive composition according to one aspect is limited from the viewpoint of preventing corrosion and the like. The amount of sulfate ion in the aqueous liquid is usually about 50 μg/mL or less, about 35 μg/mL or less (for example, about 25 μg/mL or less) is suitable, and preferably about 15 μg/mL or less, more preferably It is about 5 μg/mL or less, more preferably about 2 μg/mL or less (for example, about 1 μg/mL or less). The lower limit of the amount of sulfate ion of the aqueous liquid is ideally 0 μg/mL, but in consideration of production efficiency, practically acceptable level, etc., it may be about 10 μg/mL or more, about 20 μg. /ML or more.

It is desirable that the amount of nitrate ions in the aqueous liquid used for preparing the pressure-sensitive adhesive composition according to one aspect is limited from the viewpoint of preventing corrosion and the like. The amount of nitrate ion in the aqueous liquid is usually about 30 μg/mL or less, about 20 μg/mL or less (for example, about 10 μg/mL or less) is suitable, and preferably about 7 μg/mL or less, more preferably It is about 5 μg/mL or less, more preferably about 2 μg/mL or less (for example, about 1 μg/mL or less). The lower limit of the amount of nitrate ions of the above aqueous liquid is ideally 0 μg/mL, but in consideration of production efficiency, practically acceptable level, etc., it may be about 1 μg/mL or more, about 3 μg. /ML or more, or about 5 μg/mL or more (for example, 10 μg/mL or more).

In the aqueous liquid used for preparing the pressure-sensitive adhesive composition according to one aspect, it is appropriate that the total amount of nitrate ion, sulfate ion, and chloride ion is about 80 μg/mL or less. By limiting the total amount of these plural types of ions that may cause corrosion and the like, it is possible to prevent the corrosion and the like more reliably. The total amount of the three ions is preferably less than 50 μg/mL, more preferably less than 30 μg/mL, even more preferably less than 15 μg/mL, and approximately 10 μg/mL or less (for example, approximately 5 μg/mL or less). May be. The lower limit of the total amount of the three types of ions in the aqueous liquid is ideally 0 μg/mL, but may be approximately 1 μg/mL or more from the viewpoint of production efficiency, practically acceptable level, and the like. It may be about 5 μg/mL or more, or about 10 μg/mL or more (for example, 30 μg/mL or more).

From the viewpoint of prevention of corrosion and the like, in the technique disclosed herein, it is preferable to limit the amount of anions (typically chloride ions) among the ions contained in the aqueous liquid. On the other hand, the amount of cations in the aqueous liquid is not particularly limited. In one aspect, the amount of cations in the aqueous liquid can be in the range of having an electrical conductivity of less than 300 μS/cm. For example, the amount of calcium ions and magnesium ions removed by general water softening treatment is not particularly limited, and the amount of calcium ions and magnesium ions in the aqueous liquid used for preparing the pressure-sensitive adhesive composition is 1 μg/mL. Or more, about 10 μg/mL or more, or 20 μg/mL or more.

The amount of chloride ion, amount of sulfate ion, amount of nitrate ion, amount of calcium ion, and amount of magnesium ion of the aqueous liquid can be determined by ion chromatography using each commercially available ion standard solution (for example, available from Wako Pure Chemical Industries, Ltd.). Can be measured. Specifically, it is measured by the following method.

[Measurement of ion content of aqueous liquid]
Ion chromatography measurement conditions are as follows.
(Measurement condition)
Anion analysis:
Device: "ICS-3000" made by Thermo Fisher Scientific
Separation column: Dionex IonPac AS18-fast (4mm x 250mm)
Guard column: Dionex IonPac AG18-fast (4mm x 50mm)
Removal system: Dionex AERS-500 (external mode)
Detector: Electric conductivity detector Eluent: KOH aqueous solution (using eluent generator cartridge)
Eluent flow rate: 1.0 mL/min
Sample injection volume: 250 μL
Cation analysis:
Equipment: "DX-320" made by Thermo Fisher Scientific
Separation column: Dionex Ion Pac CS16 (5mm x 250mm)
Guard column: Dionex Ion Pac CG16 (5mm x 50mm)
Removal system: Dionex CSRS-500 (recycle mode)
Detector: Electric conductivity detector Eluent: Methanesulfonic acid aqueous solution Eluent flow rate: 1.0 mL/min
Sample injection volume: 25 μL

The aqueous liquid disclosed herein is a liquid containing water (H ₂ O) as a main component, and may contain an organic solvent such as alcohol in a ratio smaller than that of water. Typically, a liquid having a water content of more than 50% by volume is used as the aqueous liquid. The proportion of water in the aqueous liquid is usually about 90% by volume or more, and about 99% by volume or more (for example, 99.9% by volume or more) is suitable.

<Characteristics of protective sheet>
Although not particularly limited, in the protective sheet disclosed herein, the amount of chloride ions measured by hot water extraction is less than 8.9 μg per 1 g of the protective sheet (for example, about 8.5 μg or less). Appropriate. As a result, it is easy to obtain a structure that prevents corrosion or the like in the Low-E glass plate that is the object of protection for a long period of time, and the protective sheet tends to have excellent long-term reliability. The amount of chloride ions per 1 g of the protective sheet is preferably less than 8.0 μg, more preferably less than 7.0 μg, still more preferably less than 6.5 μg, particularly preferably less than 6.0 μg (eg less than 5.5 μg). .. The lower limit of the amount of chloride ions per 1 g of the protective sheet is ideally 0 μg, but from the viewpoint of production efficiency and practically acceptable level, it may be approximately 1 μg or more, or approximately 3 μg or more. Or about 5 μg or more. The chloride ion amount per 1 g of the protective sheet is measured by the following method.

[Chloride ion content of protective sheet]
The protective sheet to be measured is thoroughly washed with pure water, cut into a sheet area of 50 cm ^{2 in} size, put in a polypropylene (PP) container, and weighed. 25 mL of pure water is added to a PP container, and extraction with heating is performed at 120° C. for 1 hour using a dryer. For the obtained extract, the amount of chloride ions in the extract was quantified using a chloride ion standard solution by the same method as the ion chromatography method described later, and chloride ion per 1 g of the protective sheet used for extraction Find the amount.

The protective sheet disclosed herein has an initial peel strength of about 0.01 N/20 mm or more, which is measured at a peeling speed of 0.3 m/min and a peeling angle of 180 degrees, 30 minutes after being attached to a Low-E glass plate. Is suitable. The protective sheet having the above initial peel strength, after being adhered to the adherend, adheres well to the adherend within a relatively short time, and is unlikely to be peeled off from the adherend, It can exhibit excellent protection performance. In one aspect, the initial peel strength can be about 0.05 N/20 mm or greater (eg, about 0.1 N/20 mm or greater). In a preferred aspect, the initial peel strength can be about 0.5 N/20 mm or greater (eg, about 1 N/20 mm or greater). The upper limit of the initial peeling strength is not particularly limited, but from the viewpoint of light peeling property, about 5 N/20 mm or less is suitable, and about 2.5 N/20 mm or less (for example, about 2 N/20 mm or less) is preferable. The initial peel strength is measured by the following method.

[Initial peel strength]
A protective sheet to be measured is cut into a strip having a width of 20 mm and a length of 100 mm to prepare a test piece. Under a standard environment of 23° C. and 50% RH, this test piece is pressure-bonded to a Low-E glass plate as an adherend by reciprocating a 2 kg rubber roller twice. After holding this sample in the standard environment for 30 minutes, under the standard environment, using a universal tensile tester, under conditions of a tensile speed of 0.3 m/min and a peel angle of 180 degrees, the initial peel strength [N /20 mm] is measured. As the Low-E glass plate, product number “RSFL6AS” (100 mm×100 mm) manufactured by Nippon Sheet Glass Co., Ltd. is used. As the adherend, any low-E glass plate can be used without particular limitation, and equivalent products of the above products or other commercially available low-E glass plates may be used.

The protective sheet disclosed herein has a peel strength of about 5 N measured with a pulling speed of 0.3 m/min and a peel angle of 180 degrees after being attached to a Low-E glass plate and stored at 50°C for 7 days. It is preferably /20 mm or less. A protective sheet satisfying these characteristics has sufficiently suppressed adhesive strength over time even if it is adhered to an adherend for a relatively long period of time, and can maintain its light releasability from the adherend. Therefore, the workability of removing from the adherend is excellent. With a protective sheet having a peel strength of about 4 N/20 mm or less (more preferably about 2 N/20 mm or less), better peeling workability can be realized. Further, from the viewpoint of suppressing floating and peeling during the protection period of the adherend (for example, during processing of the adherend to which the protective sheet is attached), the temporal peel strength is about 0.05 N/20 mm or more. Is suitable, preferably about 0.1 N/20 mm or more, more preferably about 0.3 N/20 mm or more. The time-dependent peel strength may be about 1 N/20 mm or more. The peel strength with time is measured by the following method.

[Peel strength over time]
A protective sheet to be measured is cut into a strip having a width of 20 mm and a length of 100 mm to prepare a test piece. Under a standard environment of 23° C. and 50% RH, this test piece is pressure-bonded to a Low-E glass plate as an adherend by reciprocating a 2 kg rubber roller twice. This sample was stored in an environment of 50° C. for 7 days, and then kept in a standard environment of 23° C. and 50% RH for 1 hour, and then, in the standard environment, a tensile rate of 0. The peel strength with time [N/20 mm] is measured under the conditions of 3 m/min and a peel angle of 180 degrees. The Low-E glass plate used as the adherend is the same as in the case of the above initial peel strength measurement.

Although not particularly limited, the protective sheet disclosed herein has a ratio (that is, P ₂ /P ₁ ratio) of the temporal peel strength P ₂ [N/20 mm] to the initial peel strength P ₁ [N/20 mm]. It can be 5 times or less. A small P ₂ /P ₁ ratio means that the peel strength does not increase with time. As a result, the initial adhesiveness and the light releasability during the peeling work are suitably compatible with each other. From this viewpoint, the P ₂ /P ₁ ratio may be preferably 4 or less, more preferably 3 or less, still more preferably 2 or less, for example 1.8 or less, and 1.5 or less, further 1.3. It may be the following. _Further, P 2 / _{P 1} ratio may typically be in is 0.8 or more, such as one or more.

From the viewpoint of environmental hygiene, the protective sheet disclosed herein includes the protective sheet (the base material layer and the pressure-sensitive adhesive layer may be included when the protective sheet is heated at 80° C. for 30 minutes, but the release liner is not included. The total amount of volatile organic compounds (VOC: volatile organic compounds) emitted from 1 g (hereinafter, also simply referred to as VOC emission amount) is 1000 μg (hereinafter, this may be referred to as “μg/g”). ) The following is preferable. The VOC emission amount is more preferably 500 μg/g or less (for example, 300 μg/g or less, typically 100 μg/g or less). The VOC emission amount is measured by the following method.

[VOC measurement test]
A protective sheet is cut into a predetermined size (here, a size of about 5 cm ² ) and the release liner is peeled off to form a sample piece. Then, the vial is heated at 80° C. for 30 minutes, and 1.0 mL of heated gas (sample gas) is injected into a gas chromatograph (GC) measuring device using a headspace autosampler (HSS). Based on the obtained gas chromatogram, the amount of gas generated from the above-mentioned sample piece is obtained as an n-decane conversion amount. From the obtained value, the amount of VOC emission (μg/g) per 1 g of the protective sheet (excluding the release liner) is determined. The n-decane conversion amount is determined by applying the calibration curve of n-decane prepared in advance, by regarding the detected intensity of the generated gas obtained by GC Mass as the detected intensity of n-decane. The settings of HSS and GC are as follows.
HSS: Model "7694" manufactured by Agilent Technologies
Heating time: 30 minutes Pressurization time: 0.12 minutes Loop filling time: 0.12 minutes Loop equilibration time: 0.05 minutes Injection time: 3 minutes Sample loop temperature: 160°C
Transfer line temperature: 200℃
GC device: Model "6890" manufactured by Agilent Technologies
Column: GL Sciences, Inc. J&W Capillary Column Product name “DB-ffAP” (inner diameter 0.533 mm×length 30 m, film thickness 1.0 μm)
Column temperature: 250° C. (heated from 40° C. to 90° C. at 10° C./min, then heated to 250° C. at 20° C./min and held for 5 minutes)
Column pressure: 24.3 kPa (constant flow mode)
Carrier gas: Helium (5.0 mL/min)
Inlet: Split (split ratio 12:1)
Inlet temperature: 250℃
Detector: FID
Detector temperature: 250℃

<Use>
The protective sheet disclosed herein is suitable for a surface protective sheet for a glass plate used as a building material such as a window glass. The glass plate to be attached typically includes a glass substrate and a coating layer laminated on the glass substrate, and the coating layer may include a metal layer. More specifically, the glass plate may be a glass plate having a Low-E layer on one surface. The Low-E layer usually includes a metal layer such as silver. In the production of the above glass plate, the low-E layer forming surface can be exposed until two glass plates including the Low-E glass plate are paired with the Low-E layer side surface facing inward. .. The protective sheet disclosed herein is preferably used for the purpose of preventing the surface on which the Low-E layer is formed from damage, abrasion, deterioration, corrosion and the like. That is, the protective sheet can be used as a low-E layer forming surface protective sheet. Low-E glass sheets have higher heat shielding properties and heat insulating properties than conventional glass sheets, and can improve the cooling and heating efficiency of indoor spaces, and are therefore widely used as building materials such as window glass. The technology disclosed herein can indirectly contribute to energy saving and reduction of greenhouse gas emissions by being used for manufacturing such a material.

Further, the protective sheet disclosed herein is preferably used for a large-area adherend surface whose peel strength tends to be limited in terms of workability for removal. The protective sheet disclosed herein is preferably in a mode of covering the entire surface of the adherend having a width of about 1.5 m or more, for example, about 2 m or more (typically about 3 m or more, further about 3.3 m or more). Used. The length of the adherend surface is equal to or larger than the width. In a preferred embodiment, the flat plate having a large area (preferably, a flat plate having a smooth surface) as described above is preferably used in a mode of covering one entire surface. In particular, glass plates for building materials such as window glass are becoming larger in area in terms of efficiency of production, transportation and the like. The entire surface of a glass sheet having such a large area (for example, a surface width of more than 2.6 m, typically a surface width of about 3 m or more, and even about 3.3 m or more) (typically The low-E glass plate is preferably used in such a manner as to cover the entire surface on which the Low-E layer is formed). Since the protective sheet disclosed herein is easily visible on the surface of the Low-E glass plate, it is easy to determine the presence or absence of the protective sheet on the Low-E glass plate, and the workability of removing the protective sheet is excellent. In addition, the glass sheet can be inspected for defects through the protective sheet while the glass sheet is protected by the protective sheet. Furthermore, according to a preferred aspect of the technology disclosed herein, excellent corrosion resistance and the like can be realized for the adherend having a large area as described above while maintaining light peelability.

Furthermore, since the protective sheet according to some aspects may have a suppressed adhesive force over time, for example, the period of application to the adherend (which may be the period of protection of the adherend) is relatively long. Good removal workability can be exhibited even (typically for 2 weeks or longer, for example, for 4 weeks or longer). Therefore, for example, it can be suitably used even in a usage mode in which the period from attachment to an adherend (specifically, Low-E glass plate) to removal from the adherend can be 2 weeks or more (eg, 4 weeks or more). Can be done.

The matters disclosed by this specification include the following.
(1) A method of manufacturing a glass unit,
A step (A) of preparing a Low-E glass plate including a glass substrate and a Low-E layer laminated on the glass substrate;
Attaching a protective sheet to the surface of the Low-E layer of the Low-E glass plate (B);
An optional step (C) of carrying out at least one selected from the group consisting of transportation, storage, processing, cleaning and handling on the Low-E glass plate having the protective sheet attached thereto;
A step (D) of removing the protective sheet from the Low-E glass plate;
A step (E) of assembling a glass unit using the Low-E glass plate;
Including,
Here, the protective sheet has a width of 1.5 m or more,
A method in which at least a part of the sheet surface has at least one of (a) a minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) a haze value of 10 or more.
(2) The method according to (1) above, which includes an inspection step of the Low-E glass plate between the step (B) and the step (D).
(3) The method according to (1) or (2) above, wherein the Low-E glass plate has a width of 2 m or more.
(4) The method according to (1) or (2) above, wherein the Low-E glass plate has a width of more than 2.6 m.
(5) The method according to (1) or (2) above, wherein the Low-E glass plate has a width of 3.3 m or more.
(6) The method according to any one of (1) to (5) above, wherein the Low-E layer includes a metal layer.
(7) The method according to any one of (1) to (5) above, wherein the Low-E layer includes a silver layer.
(8) The method according to any one of (1) to (7) above, wherein the thickness of the Low-E layer is 1000 nm or less.
(9) The method according to any one of (1) to (8) above, wherein the step (B) includes a step of covering one entire surface of the Low-E glass plate with at least one protective sheet. ..
(10) Any one of (1) to (9) above, wherein the step (C) is an essential step, and in the step (C), the Low-E glass plate is washed with water. The method described in crab.

(11) a step of attaching a protective sheet to the surface of a Low-E glass plate including a glass substrate and a Low-E layer laminated on the glass substrate (attaching step);
Here, the protective sheet has a width of 1.5 m or more,
Low-E having a region satisfying at least one of (a) a minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) a haze value of 10 or more; How to protect glass plates.
(12) The method further includes a step (removal step) of removing the protective sheet from the Low-E glass plate,
Between the attaching step and the removing step, optionally, at least one step selected from the group consisting of transportation, storage, processing, cleaning and handling of the Low-E glass sheet to which the protective sheet is attached is included. The method according to (11) above.
(13) The Low-E glass plate has a width of 1.5 m or more,
The said pasting process is a method as described in said (11) or (12) including the process of covering one whole surface of the said Low-E glass plate with at least one said protective sheet.

(14) The method according to any one of (1) to (13) above, which has a region having a total light transmittance of 3% or more.
(15) The method according to any one of (1) to (14) above, wherein the haze value of the region having a total light transmittance of 3% or more is 50 or less.
(16) The method according to any one of (1) to (15) above, wherein the region having a total light transmittance of 3% or more has a minimum transmittance of 30% or more at a wavelength of 450 to 800 nm.
(17) The method according to any one of (1) to (16) above, wherein the entire sheet surface is a region that satisfies at least one of (a) and (b).
(18) The method according to any one of (1) to (17) above, wherein the area satisfying at least one of (a) and (b) is a colored area.
(19) The method according to any one of (1) to (18) above, wherein the sheet surface is colored almost uniformly.
(20) The method according to (19) above, which is colored blue or green.

(21) At least a part of the sheet surface has a region satisfying at least one of (a) the minimum transmittance at a wavelength of 450 to 800 nm is 90% or less; and (b) the haze value is 10 or more. Protective sheet.
(22) A protective sheet having a colored region on at least a part of the sheet surface.
(23) The protective sheet according to (21) or (22), which has a width of 1.5 m or more.
(24) The protective sheet according to any of (21) to (23), which has a region having a total light transmittance of 3% or more.
(25) The protective sheet according to any one of (21) to (24), wherein the haze value of the region having the total light transmittance of 3% or more is 50 or less.
(26) The protective sheet according to any of (21) to (25), wherein the region having a total light transmittance of 3% or more has a minimum transmittance of 30% or more at a wavelength of 450 to 800 nm.
(27) The protective sheet according to any of (21) to (26) above, wherein the entire sheet surface is a region that satisfies at least one of (a) and (b).
(28) The protective sheet according to any of (21) to (27) above, wherein the region satisfying at least one of (a) and (b) is a colored region.
(29) The protective sheet according to any one of (21) to (28) above, which is colored substantially uniformly over the entire sheet surface.
(30) The protective sheet according to any of (21) to (29), which is colored blue or green.
(31) A base material layer, and an adhesive layer supported by the base material layer,
The protective sheet according to any of (21) to (30) above, wherein at least one of the base material layer and the pressure-sensitive adhesive layer is colored.
(32) The protective sheet according to (31), wherein the base material layer is made of a resin film containing a colorant.
(33) The pressure-sensitive adhesive layer is at least one selected from the group consisting of acrylic polymers, urethane polymers, polyester polymers, polyether polymers, rubber polymers, silicone polymers, polyamide polymers, and fluorine polymers. The protective sheet according to (31) or (32) above, which contains the polymer of 50% by weight or more.
(34) The protective sheet according to any of (21) to (33), which has a width of 3.3 m or more.
(35) The protective sheet according to any of (21) to (34), which is used for protecting a Low-E glass plate.
(36) A method for manufacturing a glass unit, comprising:
Preparing a Low-E glass plate comprising a glass substrate and a Low-E layer laminated on the glass substrate;
Attaching the protective sheet according to any one of (21) to (35) to the surface of the Low-E layer of the Low-E glass plate;
An optional step of performing at least one selected from the group consisting of transportation, storage, processing, cleaning, and handling on the Low-E glass plate to which the protective sheet is attached;
Removing the protective sheet from the Low-E glass plate;
Assembling a glass unit using the Low-E glass plate;
A method of manufacturing a glass unit, comprising:

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in the examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

<Example 1>
Monomer raw material consisting of 58 parts of 2-ethylhexyl acrylate, 40 parts of n-butyl methacrylate and 2 parts of acrylic acid, and a surfactant (trade name "Aqualon KH-1025" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., EO addition mole number 30 or less) 3 parts of polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate) and 150 parts of ion-exchanged water are mixed and emulsified with an emulsifying machine (homomixer) while introducing nitrogen gas to obtain a monomer raw material. An emulsion was prepared.
The above emulsified liquid was placed in a reaction vessel equipped with a thermometer, a nitrogen gas introduction tube, a condenser and a stirrer, and heated to a liquid temperature of 50°C while stirring under a nitrogen stream. To this, 0.03 part of 2,2′-azobis(2-methylpropionamidine)dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name “V-50”) was added as a polymerization initiator, and the liquid temperature was around 50° C. The polymerization reaction was carried out for 5 hours. Ammonia water was added to the obtained polymerization reaction solution to adjust the pH to about 8. Thus, an aqueous dispersion of acrylic polymer was prepared.
According to this example, 2 parts of an oxazoline-based cross-linking agent (trade name "Epocros WS-500" manufactured by Nippon Shokubai Co., Ltd.) was mixed with 100 parts of a non-volatile component contained in the aqueous dispersion. An adhesive composition was prepared.
As a supporting substrate, an LDPE film having a thickness of 46 μm (blue LDPE film) in which a blue pigment was kneaded was prepared by inflation molding under the conditions such as temperature and speed.
Corona discharge treatment was applied to one surface of the blue LDPE film, and the adhesive composition prepared above was applied to the corona-treated surface (first surface) with a bar coater so that the thickness after drying was 6 μm. .. This was dried at 70° C. for 2 minutes and then aged at 50° C. for 1 day to prepare a single-sided adhesive pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer on one surface of a base layer made of a blue LDPE film. The pressure-sensitive adhesive sheet thus obtained was used as the protective sheet according to this example.

<Example 2>
A 46 μm-thick LDPE film in which a green pigment was kneaded was produced by the same method as in Example 1, and the protective sheet according to this example was obtained in the same manner as in Example 1 except that this was used as a supporting substrate.

<Example 3>
As a supporting base material, a 55 μm-thick LDPE film containing no pigment was produced by adjusting the conditions such as temperature and speed by inflation molding and used as a supporting base material. A protective sheet according to this example was obtained in the same manner as in Example 1 except for the above.

<Example 4>
A protective film according to this example was obtained in the same manner as in Example 3, except that an LDPE film having a thickness of 55 μm, in which a blue pigment was kneaded, was produced in the same manner as in Example 3, and this was used as a supporting base material.

<Example 5>
A protective sheet according to this example was obtained in the same manner as in Example 3 except that an LDPE film having a thickness of 55 μm, in which a white pigment was kneaded, was prepared in the same manner as in Example 3, and this was used as a supporting substrate.

<Example 6>
A 50 μm-thick PE/PP blend film (trade name “Tretec CF470”, manufactured by Toray Film Co., Ltd.) containing no pigment was used as a supporting substrate. A protective sheet according to this example was obtained in the same manner as in Example 1 except for the above.

<Example 7>
A 50 μm thick PE/PP blend film (trade name “Tretec CF470”, manufactured by Toray Film Co., Ltd.) in which a blue pigment was kneaded was used as a supporting substrate. A protective sheet according to this example was obtained in the same manner as in Example 1 except for the above.

<Example 8>
A 38 μm-thick PET film (trade name “Diafoil W100”, manufactured by Mitsubishi Chemical Corporation) in which a white pigment was kneaded was used as a supporting substrate. A protective sheet according to this example was obtained in the same manner as in Example 1 except for the above.

<Example 9>
As a supporting base material, a transparent LDPE film having a thickness of 60 μm was produced by inflation molding under controlled conditions such as temperature and speed. A protective sheet according to this example was obtained in the same manner as in Example 1 except that this was used as a supporting substrate.

<Example 10>
As the supporting base material, a PET film (trade name “Diafoil B100”, manufactured by Mitsubishi Chemical Co., Ltd.) having a thickness of 25 μm in which a black pigment was kneaded was used. A protective sheet according to this example was obtained in the same manner as in Example 1 except for the above.

[Visibility evaluation]
A Low-E glass plate having a width of 1500 mm and a length of 1000 mm was prepared and a protective sheet was attached thereto. Place the Low-E glass plate with a protective sheet upright at a position 3 m away from the fluorescent lamp, and place the protective sheet affixing surface of the Low-E glass plate at a position 1 m away from the protective sheet affixing surface side of the Low-E glass plate. It was visually observed to evaluate whether the presence or absence of the protective sheet can be confirmed. The case where the protective sheet on the Low-E glass plate was visible was judged as "○", and the case where it was not visible was judged as "x".

[Low-E glass plate defect inspection]
Prepare a Low-E glass plate with a width of 1500 mm and a length of 1000 mm, which has streaky defects with a length of 3 to 5 cm (3 places) and chipping scratches with a diameter of 1 to 5 mm (3 places) on the surface. A protective sheet was attached to. Place a Low-E glass plate with a protective sheet at a position 3 m away from the fluorescent lamp, and place the protective sheet affixing surface of the Low-E glass plate at a position 1 m away from the protective sheet affixing surface side of the Low-E glass plate. It was visually observed, and the defect inspection property of the Low-E glass plate was evaluated through the protective sheet according to the following criteria.
(Evaluation criteria)
4 points: All streak defects and chipping scratches were visible.
3 points: Stripe defects and chipping scratches were almost visible.
2 points: Either streak defects or chipping scratches were visually recognized.
1 point: No streak defects and chipping scratches were visible.

Table 1 shows the evaluation results of the protective sheet of each example. Table 1 also shows an outline of each example (base material type, color, total light transmittance, minimum transmittance in visible light region (wavelength 450 to 800 nm), haze value).

As shown in Table 1, Examples 1 to 8 had good visibility and were easy to discriminate on the glass plate. In the protective sheet according to these examples, a region which satisfies at least one of (a) the minimum transmittance at a wavelength of 450 to 800 nm is 90% or less; and (b) the haze value is 10 or more; Have at least a portion. On the other hand, in Example 9 which does not satisfy the above (a) and (b), good visibility was not obtained. From this result, it can be seen that the protective sheet having the region satisfying at least one of the above (a) and (b) on at least a part of the sheet surface is easy to discriminate on the Low-E glass plate.
Further, the protective sheets of Examples 1 to 8 had a total light transmittance of not less than the predetermined value, and it was possible to inspect the Low-E glass plate for defects. On the other hand, the protective sheet of Example 10 which does not have the region where the total light transmittance is 3% or more does not have a good evaluation result of the defect inspection property of the Low-E glass plate, and the Low-E glass plate through the protective sheet is poor. The inspection was difficult. From this result, it can be seen that a protective sheet having a region having a total light transmittance of 3% or more enables a Low-E glass plate inspection through the protective sheet. The effect can be better exhibited in a structure having a width of 1.5 m or more.

The specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

1: Base material layer 1A: One surface 1B: Other surface 2: Adhesive layer 2A: Adhesive surface 10: Protective sheet 100: Low-E glass plate 110: Glass substrate 120: Low-E layer 200: Protective sheet 300 : Glass unit 320: Other glass plate 340: Spacer

Claims (31)

With a width of 1.5m or more,
At least one of (a) the minimum transmittance at a wavelength of 450 to 800 nm is 90% or less; and (b) the haze value is 10 or more. A low-E glass sheet protective sheet having a satisfying area on at least a part of the sheet surface. The protective sheet according to claim 1, wherein the haze value of the region where the total light transmittance is 3% or more is 50 or less. The protective sheet according to claim 1 or 2, wherein the region having a total light transmittance of 3% or more has a minimum transmittance of 30% or more at a wavelength of 450 to 800 nm. The protective sheet according to any one of claims 1 to 3, wherein the entire sheet surface is an area that satisfies at least one of (a) and (b). The protective sheet according to any one of claims 1 to 4, wherein the area satisfying at least one of (a) and (b) is a colored area. The protective sheet according to any one of claims 1 to 5, which is colored substantially uniformly over the entire surface of the sheet. The protective sheet according to any one of claims 1 to 6, which is colored blue or green. A base material layer and an adhesive layer supported by the base material layer,
The protective sheet according to any one of claims 1 to 7, wherein at least one of the base material layer and the pressure-sensitive adhesive layer is colored. The protective sheet according to claim 8, wherein the base material layer is made of a resin film containing a colorant. With a width of 1.5m or more,
Low-E having a region satisfying at least one of (a) a minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) a haze value of 10 or more; Protective sheet for glass plate. Protective sheet according to any one of claims 1 to 10, having a width of 3.3 m or more. The pressure-sensitive adhesive layer is at least one polymer selected from the group consisting of acrylic polymers, urethane polymers, polyester polymers, polyether polymers, rubber polymers, silicone polymers, polyamide polymers and fluorine polymers. The protective sheet according to claim 8 or 9, which contains 50% by weight or more. A method of manufacturing a glass unit,
Preparing a Low-E glass plate comprising a glass substrate and a Low-E layer laminated on the glass substrate;
A step of sticking the protective sheet according to any one of claims 1 to 12 on the surface of the low-E layer of the low-E glass plate;
An optional step of performing at least one selected from the group consisting of transportation, storage, processing, cleaning, and handling on the Low-E glass plate to which the protective sheet is attached;
Removing the protective sheet from the Low-E glass plate;
Assembling a glass unit using the Low-E glass plate;
A method of manufacturing a glass unit, comprising: The method according to claim 13, further comprising a step of inspecting the Low-E glass plate between the step of attaching the protective sheet and the step of removing the protective sheet. The method according to claim 13 or 14, wherein the Low-E glass plate has a width of 2 m or more. The method according to claim 13 or 14, wherein the Low-E glass plate has a width of more than 2.6 m. The method according to claim 13 or 14, wherein the Low-E glass plate has a width of 3.3 m or more. The method according to any one of claims 13 to 17, wherein the Low-E layer includes a metal layer. The method according to any one of claims 13 to 18, wherein the Low-E layer includes a silver layer. The method according to any one of claims 13 to 19, wherein the thickness of the Low-E layer is 1000 nm or less. The method according to any one of claims 13 to 20, wherein the step of attaching the protective sheet includes a step of covering one entire surface of the Low-E glass plate with at least one protective sheet. An optional step of carrying out at least one selected from the group consisting of transportation, storage, processing, cleaning, and handling is an essential step for the Low-E glass plate having the protective sheet attached, The method according to any one of claims 13 to 21, wherein the low-E glass plate is washed with water in the process (1). A step of attaching a protective sheet to the surface of a Low-E glass plate including a glass substrate and a Low-E layer laminated on the glass substrate (attaching step);
Here, the protective sheet has a width of 1.5 m or more,
Low-E having a region satisfying at least one of (a) a minimum transmittance of 90% or less at a wavelength of 450 to 800 nm; and (b) a haze value of 10 or more; How to protect glass plates. Further comprising a step (removal step) of removing the protective sheet from the Low-E glass plate,
Between the attaching step and the removing step, optionally, at least one step selected from the group consisting of transportation, storage, processing, cleaning and handling of the Low-E glass sheet to which the protective sheet is attached is included. 24. The method of claim 23, which may be. The Low-E glass plate has a width of 1.5 m or more,
The method according to claim 23 or 24, wherein the attaching step includes a step of covering one entire surface of the Low-E glass plate with at least one protective sheet. The method according to any one of claims 13 to 25, wherein a haze value of a region where the total light transmittance is 3% or more is 50 or less. The method according to any one of claims 13 to 26, wherein a minimum transmittance at a wavelength of 450 to 800 nm is 30% or more in a region where the total light transmittance is 3% or more. The method according to any one of claims 13 to 27, wherein the entire sheet surface is a region that satisfies at least one of (a) and (b). 29. The method according to claim 28, wherein the area satisfying at least one of (a) and (b) is a colored area. The method according to any one of claims 13 to 29, wherein the entire surface of the sheet is colored substantially uniformly. The method according to claim 30, wherein the protective sheet is colored blue or green.

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