TW201643650A - Scattering prevention sheet - Google Patents

Abstract

The present invention provides an internally adhesive scattering preventing sheet capable of ensuring excellent Newton ring preventing properties and certainly preventing close placement on a glass surface or a deflecting plate. To this end, the scattering preventing sheet is attached on the inner surface of a display device of a member for constituting the display device, has a layer containing particles and resin, and has a plurality of block parts formed on the surface thereof due to the particles. The average particle size of the particles is 0.5-10 micrometer, and a content thereof is less than 0.3 wt% of a resin solid constituting the layer. Further, the resin is obtained by introducing a photocurable unsaturated group in a thermoplastic resin or a thermosetting resin, and a weight average molecular weight thereof is 70000 or more. The resin is an ionization radiation hardening resin including more than 15 wt% and 50 wt% or less of a compound having a glass transition temperature of 45℃ or more in the total resin.

Description

Scattering prevention sheet

The present invention relates to a scattering preventing sheet that is attached to a surface opposite to a touch surface of a capacitive touch panel.

In the capacitive touch panel, there are a surface type and a projection type, but the input positions are detected by capturing changes in electrostatic capacitance occurring at the touch position. Therefore, compared with the resistive film type which is accompanied by mechanical contact deformation (which recesses the transparent conductive film), there is an advantage that no force is required at the time of input, and it is possible to input only by touching a slight touch of the screen.

The capacitive touch panel shown above protects a transparent substrate such as glass or plastic from scattering during breakage, and is often provided with a hard coat film or a protective sheet on the touch surface or the opposite side (scatter prevention) Sheet). The scattering prevention sheet is also referred to as an inner sheet if it is used on the opposite side to the touch surface, and the Newton ring does not occur when the glass sheet or the deflecting plate of the display device on the lower side is connected. .

Patent Document 1 discloses a display of an electrostatic capacitance type touch panel which is less prone to Newton's ring and has a good brightness of a touch surface. Device and capacitive touch panel. In this technique, a protective sheet having a hard coat layer having fine unevenness is attached to a surface opposite to the touch surface of the touch panel, and a surface facing the display device (liquid crystal display) is provided with unevenness. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5440747

In the protective sheet described in Patent Document 1, since the fine unevenness of 400 nm or less is distributed substantially uniformly over the entire uneven surface, the Newton's ring preventing effect is limited, and it is considered that the touch is not possible until the touch is relatively strong. Suppresses the occurrence of Newton's rings.

The applicant of the present invention has proposed a technique of taking into consideration the anti-glare property, the prevention of the Newton's ring, and the anti-glare prevention property, and has been used as a hard coat film for the front surface of a display device such as a touch panel (Japanese Patent Application No. 2013-198380). The resin of the hard coat layer of the agent and the resin, together with the ionizing radiation hardening resin, has a specific reactive functional group, and a specific glass transition temperature and molecular weight resin are used, whereby a hard coat film satisfying the above properties can be obtained. This technology is good for the hard coat film used above. However, the inner bonding sheet (scattering preventing sheet) used on the inner side of the display device does not necessarily have satisfactory performance.

The inventors of the present invention are based on the technique disclosed in Japanese Patent Application No. 2013-198380, and in particular, the composition for obtaining the performance of the scattering preventing sheet is continuously studied. As a result, it has been found that by setting the particle diameter and the content of the particles contained in the hard coat layer to a specific range and adjusting the manner (state) of the convex portion formed by the particles, it is possible to obtain the inner sheet by the inner sheet. The inventors of the present invention have achieved an excellent Newton's ring prevention property and can surely prevent adhesion to a glass surface or a deflecting plate.

In other words, the scattering preventing sheet of the present invention includes a layer containing particles and a resin, and has a plurality of convex portions on the surface thereof, and is prevented from being scattered on the surface of the member constituting the display device facing the inside of the display device. In the sheet, the particle-based average particle diameter is 0.5 to 10 μm and the content is less than 0.3% by weight of the resin solid content constituting the layer. In addition, the resin is introduced with a photocurable unsaturated group in the thermoplastic resin or the thermosetting resin, and contains more than 15% by weight and 50% by weight or less of the weight average molecular weight of the whole resin of 70,000 or more, and the glass transition temperature. An ionizing radiation-curable resin which is a compound of 45 ° C or more.

Further, the scattering preventing sheet of the present invention is preferably such that the area of the flat region of the convex portion which does not have the particles is 98% or more.

Further, the scattering preventing sheet of the present invention is suitable for a haze (JIS K7136:2000) of 2.0% or less.

In the present invention, the "display device" includes a display device including a display device or a touch panel or the like attached or added. It is used under the broad concept of (for example, a display device with a touch panel).

According to the present invention, in the display device with a touch panel or the like, the occurrence of the Newton's ring and the flash can be effectively prevented, and the occurrence of the watermark caused by the adhesion preventing the adhesion of the sheet to the display surface can be prevented. Wherein, the watermarking means a region (closed region) in which the scattering preventing sheet is in close contact with the display surface, and a region (non-adhesive region) in which the two are not closely connected, since the traveling path of the light of each of the regions is greatly different, so that the watertight connection is made The obvious boundary between the area and the non-closed area.

1‧‧‧scattering prevention sheet

1a‧‧‧scattering prevention sheet

2‧‧‧hard coating

3‧‧‧Adhesive layer

4‧‧‧Substrate

5, 5a‧‧‧Adhesive resin

5a’‧‧‧ undulation

6, 6a‧‧‧ particles

8‧‧‧ convex

31‧‧‧ touch surface

32‧‧‧Touch panel

33‧‧‧Adhesive

34‧‧‧ display device

35‧‧‧Capacitive touch panel

Fig. 1 is a view showing an example of a display device with a capacitive touch panel to which a scattering preventing sheet of the present invention is applied.

Fig. 2 is a cross-sectional view showing a scattering preventing sheet as an example of the present invention.

Fig. 3 is a cross-sectional view showing a conventional scattering preventing sheet.

Hereinafter, an embodiment of the scattering preventing sheet of the present invention will be described.

The scattering preventing sheet of the present embodiment is attached to a sheet facing the surface of the display device in the member constituting the display device, and has A layer containing particles and a resin.

In the present embodiment, the display device is a display device with a touch panel integrated with a capacitive touch panel and a display device at a predetermined interval, and the scattering preventing sheet is attached to the electrostatic capacitance type as shown above. The face of the touch panel opposite the display device.

An example of a display device with a touch panel provided with the scattering preventing sheet of the present embodiment is shown in Fig. 1 . As shown in the figure, the display device 35 with a capacitive touch panel has a structure in which a display device 34 such as a liquid crystal display device and a touch panel 32 are adhered to each other by an adhesive 33 on both peripheral portions thereof. A certain gap is provided between the touch panel 32 and the touch panel 32. On the opposite side of the touch surface 31 of the touch panel 32, the scattering preventing sheet 1 is adhered to the adhesive layer 3.

As shown in FIG. 2, the scattering prevention sheet 1 includes a substrate 4 and a layer 2 containing particles and a resin. The layer 2 containing the particles and the resin is a layer which has irregularities on the surface and functions as an anti-Newton ring layer, and also functions as a hard coat layer for protecting the touch panel 32, and is hereinafter referred to as a hard coat layer 2. The scattering preventing sheet 1 is disposed in such a manner that the hard coat layer 2 faces the gap. In FIG. 2, the substrate 4 is provided with an adhesive layer 3 for attaching the scattering preventing sheet 1 to the touch panel 32, but the adhesive layer 3 may also be disposed on the side of the touch panel or in a scattered manner. The formation of the sheet 1 is prevented, and it is not necessary for the scattering prevention sheet 1 itself. Further, the scattering preventing sheet may be a single layer sheet of a hard coat layer, or a hard coat layer on one side or two areas of the base sheet.

The scattering preventing sheet 1 of the present embodiment is characterized by: By using a specific ionizing radiation curable resin as a resin and forming the particle size and content of the particles into a specific range, a specific surface shape can be formed, whereby a high total light transmittance and a low haze can be satisfied. The optical characteristics are such as to suppress the occurrence of the Newton's ring; the surface of the display device on the lower side is typically an adhesion preventing effect of the glass surface or the deflecting plate; and the flashing prevention effect when viewed from the side of the touch surface 31 .

Hereinafter, the scattering prevention sheet 1 having the structure shown in Fig. 2 will be taken as an example to explain the specific constitution of the substrate and the hard coat layer.

The substrate 4 can be used as long as it has a high optical transparency, and is not particularly limited. For example: polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polystyrene, cellulose triacetate, acrylic acid A transparent film formed by materials. Among these, the polyethylene terephthalate film which has been subjected to drawing processing, particularly biaxial stretching, is preferably excellent in mechanical strength or dimensional stability. Further, it is also suitable to use a corona discharge treatment on the surface of the substrate 4, or to improve the adhesion to the hard coat layer 2 by providing an easy-to-attach layer. The thickness of the substrate 4 is generally 6 to 500 μm, preferably 23 to 200 μm.

The hard coat layer 2 includes a binder resin 5 and particles 6 and a convex portion 8 having a plurality of particles 6 on its surface.

The binder resin 5 of the present embodiment includes an ionizing radiation curable resin and a specific resin. The specific resin means that a photocurable unsaturated group is introduced into the thermoplastic resin or the thermosetting resin, and the weight average molecular weight is 70,000 or more, and the glass transition temperature is 45° C. or higher. The compound is hereinafter referred to as Resin A.

First, an ionizing radiation curable resin will be described. In the case of the ionizing radiation-curable resin, it is cured by crosslinking by irradiation with ionizing radiation (ultraviolet rays or electron beams). In the above, one or two kinds of photocationic polymerizable resin capable of photocationic polymerization, photopolymerizable prepolymer capable of photoradical polymerization, or photopolymerizable monomer may be used. The above.

Examples of the photocationic polymerizable resin include an epoxy resin such as a bisphenol epoxy resin, a novolac epoxy resin, a cycloaliphatic epoxy resin, or an aliphatic epoxy resin, or a vinyl ether resin.

In the photopolymerizable prepolymer, an acrylic prepolymer having two or more acrylonitrile groups in one molecule and having a three-dimensional network structure by cross-linking and curing is preferably used. As the acrylic prepolymer, urethane acrylate, polyester acrylate, epoxy acrylate, melamine acrylate, polyfluoroalkyl acrylate, decyl acrylate or the like can be used. Further, these acrylic prepolymers may be used singly, but in order to improve the crosslinking hardenability and to increase the hardness of the functional layer, it is preferred to add a photopolymerizable monomer.

For the photopolymerizable monomer, a monofunctional acrylic monomer such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate or butoxyethyl ester, 1,6-hexyl is used. 2-functional acrylic monomer such as diol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, hydroxypivalate neopentyl glycol diacrylate, Pentaerythritol hexaacrylate, trimethylpropane triacrylate, season One or two or more kinds of polyfunctional acrylic monomers such as pentaerythritol triacrylate.

In addition to the photocationic polymerizable resin, the photopolymerizable prepolymer, or the photopolymerizable monomer, the ionizing radiation-curable resin is cured by ultraviolet irradiation to contain a photopolymerization initiator or light. A curing accelerator such as a polymerization accelerator or an ultraviolet sensitizer is preferred.

In terms of photopolymerization initiators, exemplified are: acetophenones, benzophenones, mischrone, benzoin, benzyl methyl ketal, benzyl benzoate, α-mercapto oxime ester, thioxanthene A photo-cationic polymerization initiator such as a ketone or the like, or a photocationic polymerization initiator such as a phosphonium salt, a sulfonate or an organic metal complex. Examples of the ultraviolet sensitizer include n-butylamine, triethylamine, and tri-n-butylphosphine.

Further, the photopolymerization accelerator is one which accelerates the curing speed due to a decrease in polymerization resistance due to air during hardening, and examples thereof include isoamyl p-dimethylaminobenzoate and ethyl p-dimethylaminobenzoate. Wait.

Further, as the ionizing radiation-curable resin, an ionizing radiation-curable organic-inorganic hybrid resin can also be used. Ionizing radiation-curable organic-inorganic hybrid resin (hereinafter also referred to simply as "organic-inorganic hybrid resin") means a method different from the conventional composite represented by glass fiber reinforced plastic (FRP), a mixture of organic matter and inorganic matter. The film is dense, and the dispersed state is at or near the molecular level, and the inorganic component reacts with the organic component to form a film by irradiation of ionizing radiation.

In terms of inorganic components in the organic-inorganic hybrid resin, It is a metal oxide such as vermiculite or titanium oxide, but it is preferably a vermiculite. In the case of vermiculite, a reactive vermiculite having a photopolymerizable photosensitive group is introduced on the surface. The content of the inorganic component in the organic-inorganic hybrid resin is preferably 10% by weight or more, preferably 20% by weight, more preferably 65% by weight or less, and most preferably 40% by weight or less.

The organic component in the organic-inorganic hybrid resin is a compound having a polymerizable unsaturated group polymerizable with the above inorganic component (preferably, reactive vermiculite) (for example, having two or more polymerizable groups in a molecule) a polyvalent unsaturated organic compound having an unsaturated group or a monovalent unsaturated organic compound having one polymerizable unsaturated group in a molecule, or the like).

Next, the resin A will be described.

Resin A is a photocurable unsaturated base which is introduced into a thermoplastic resin or a thermosetting resin.

Examples of the thermoplastic resin include a polyester resin, an acrylic resin, a polycarbonate resin, a cellulose resin, an acetal resin, an ethylene resin, a polyethylene resin, and a polystyrene resin. A polypropylene resin, a polyamide resin, a polyimide resin, a fluorine resin, or the like. Examples of the thermosetting resin include a polyester acrylate resin, a polyurethane acrylate resin, an epoxy acrylate resin, an epoxy resin, a melamine resin, a phenol resin, and a hydrazine. Oxygen resin or the like.

The photocurable unsaturated group introduced into the thermoplastic resin or the thermosetting resin is preferably an ionizing radiation curable unsaturated group. Specific examples thereof include: (meth)acryl fluorenyl group, styryl group, and ethylene. An ethylenically unsaturated bond such as a propylene group or an epoxy group. Preferred is a (meth) acrylonitrile group.

In the present embodiment, the resin A particularly has a glass transition temperature (Tg) of 45 ° C or higher, preferably 80 ° C or higher, and more preferably 90 ° C or higher. A resin A having a Tg of 45 ° C or higher is used together with the ionizing radiation-curable resin, whereby the flow of the ionizing radiation-curable resin can be easily suppressed during the hardening process.

Here, the former Tg-based resin A is hardened before.

In the present embodiment, the resin A is particularly preferably used having a weight average molecular weight (Mw) of 70,000 or more, preferably 80,000 or more. A resin A having a Mw of 70,000 or more is used together with the ionizing radiation-curable resin, whereby the flow of the ionizing radiation-curable resin can be easily suppressed during the hardening process.

Wherein, the value of the weight average molecular weight (Mw) can be determined by, for example, a gel permeation chromatography (GPC) equipped with a differential refractive index detector (RID), and the resulting molecular weight distribution is obtained from the obtained chromatogram ( Table), the standard polystyrene was calculated as a calibration curve.

The effect achieved by the combination of the resin A will be described with reference to Fig. 3 .

In general, an ionizing radiation-curable resin has a property of being hardened while flowing while being hardened. Therefore, when a cured product containing the particles 6 and the binder resin 5 containing the ionizing radiation-curable resin is used to obtain a cured product, when the curable composition is cured, the ionizing radiation-curable resin flows, and as a result, As shown in Figure 3, occurs as a grain The sub-section 6a is a "lens 5a" of the centering agent resin 5a, and forms a lens shape. In the conventional scattering preventing sheet 1a, the undulation is one of the causes of the flash.

In the present embodiment, a predetermined amount of the specific resin A is used together with the ionizing radiation-curable resin, whereby the flow of the ionizing radiation-curable resin is suppressed during the hardening process. As a result, as shown in Fig. 2, occurrence of "undulation" of the binder resin 5 after hardening can be suppressed (substantially no equivalent to the undulation 5a of Fig. 3 is obtained. The same applies hereinafter), whereby it can be more effectively prevented. The scattering after hardening prevents the sheet 1 from flashing.

Further, the photocurable unsaturated group contained in the resin A is strongly bonded to the ionizing radiation-curable resin, and as a result, compared with the case where the photocurable unsaturated group is not introduced, Improve the hardness of the film.

The ionizing radiation-curable resin is preferably 50% by weight or more and less than 85% by weight, more preferably 60% by weight or more and 80% by weight or less, and more preferably 60% by weight or more based on the total resin component constituting the hard coat layer. More preferably, it is 75% by weight or less.

The resin A is preferably more than 15% by weight and 50% by weight or less, more preferably 20% by weight or more and 40% by weight or less, and preferably 25% by weight or more and 40% by weight or less, based on the total resin constituting the hard coat layer. For better. By forming the blending amount of the resin A to an amount exceeding 15% by weight, occurrence of undulation can be sufficiently suppressed, and flashing can be easily prevented. Further, by forming at 50% by weight or less, it is possible to easily prevent a decrease in coating film strength.

In addition, by more than 15% by weight and less than 50% by weight The blending amount of the resin A is blended in the range, and the particle dispersibility is improved, whereby the surface properties of the coating film are appropriately adjusted.

In the hard coat layer of the present embodiment, the ionizing radiation curable resin and the compound or resin other than the resin A can be added to the extent that the function is not inhibited.

Next, the particles 6 contained in the hard coat layer 2 will be described. Examples of the particles include inorganic particles (for example, calcium carbonate, magnesium carbonate, barium sulfate, aluminum hydroxide, vermiculite, kaolin, clay, talc, etc.), or resin particles (for example, acrylic resin particles, Polystyrene resin particles, polyurethane resin particles, polyethylene resin particles, benzoguanamine resin particles, epoxy resin particles, and the like). Among them, spherical fine particles are preferred from the viewpoint of handleability or ease of control of the surface shape. Further, the resin particles are more suitable in that the refractive index is easily brought close to the binder resin, it is easy to prevent the occurrence of flash, and it is difficult to prevent transparency.

The average particle diameter of the particles 6 varies depending on the thickness of the hard coat layer 2, and therefore cannot be generalized, but is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 1 μm or more, and most preferably 10 μm or less. It is 8 μm or less. By forming the average particle diameter of the particles 6 to 10 μm or less, the induction of the flash can be easily prevented, and by setting the average particle diameter to 0.1 μm or more, the antiglare property or the Newton ring preventing property can be easily exhibited. In the present specification, the "average particle diameter" of the particles 6 and the "variation coefficient of the particle diameter distribution" are values measured by a Coulter counter method.

The particles 6 may also be composed of a plurality of particles having different average particle diameters. Composition.

The content of the particles 6 is preferably less than 0.3% by weight based on the solid content of the binder resin 5. The following limit is preferably 0.05% by weight or more, and more preferably 0.075% by weight or more. When the content of the particles relative to the solid content of the resin is 0.05% by weight or more, the watermark preventing property and the Newton's ring preventing property can be obtained, and by forming it to less than 0.3% by weight, the desired haze can be achieved as an inner sheet. High total light transmittance.

The hard coat layer 2 of the present embodiment can be formed by applying a curable composition containing a resin and particles before curing to a substrate 4 by applying, drying, and ionizing radiation. Additives such as a leveling agent, an ultraviolet absorber, and an antioxidant may be added to the curable composition.

The thickness of the hard coat layer 2 is preferably 0.5 μm or more, preferably 1 μm or more, more preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 3 μm or less.

Next, the shape and optical characteristics of the hard coat layer 2 will be described.

A convex portion due to the particles is formed on the surface of the hard coat layer 2 composed of the resin and the particles. However, the particle diameter and the content of the particles are formed into a specific range, and the area other than the convex portion is used ( The flat portion area is adjusted to be 98% or more and less than 100%. The state in which the flat portion area is 98% or more and less than 100% is a state in which the convex portions adjacent to the surface of the hard coat layer do not closely adhere to each other, and are sparsely dispersed. The interval between the convex portion and the nearest convex portion is, for example, about several times to ten times the radius of the convex portion. Due to the state shown above, with fine Compared with the case where the convex portion exists on one side, the Newton's ring preventing effect can be improved. Further, since the convex portion is scattered, even if a flat surface, for example, a surface (glass surface or deflecting plate) of the display device is pressed, it does not adhere to each other and a so-called watermark is generated.

In the case of the flat portion, the surface of the scattering preventing sheet of the present embodiment is photographed by a CCD camera at a magnification of 100 times, and the data obtained by binarizing the image (valley method) is calculated. Specifically, in the binarized image, the convex portion is drawn in white, and the flat portion is drawn in black. Regarding the reference area (for example, 6.3 mm ² ), the area of black is calculated, and the ratio of the area to the reference area is determined as the area of the flat portion.

Since the scattering preventing sheet-like convex portion of the present embodiment exists in a sparse state as described above, even if relatively large particles (for example, particles having an average particle diameter of 5 μm) are used, the haze does not become high and can be kept high. Full light transmission rate. The haze (JIS K7136:2000) is preferably 2.0% or less, and more preferably 1.0% or less. By adjusting the content of the particles in accordance with the average particle diameter, an appropriate haze can be maintained.

As described above, in the hard coat layer of the present embodiment, the ionizing radiation-curable resin containing the specific resin A is used as the resin constituting the resin, and thus the "undulation" is not caused, and the height of the convex portion is The ratio of the length of the base of the convex portion (referred to as the aspect ratio) becomes a relatively large convex portion. Specifically, the aspect ratio is 0.043 or more. When the aspect ratio of the convex portion 8 is out of this range, it is difficult to obtain the strength of the coating film while maintaining the suppression of the coating film. The effect of flash prevention caused by volts.

Further, the aspect ratio of the convex portion is preferably 0.2 or less, more preferably 0.18 or less, and still more preferably 0.16 or less from the viewpoint of preventing the fall of the particles 6 on the surface of the coating film.

The "aspect ratio of the convex portion" means the ratio (H/L) of the height H of the convex portion 8 to the length L of the flat foot region (refer to FIG. 3, respectively). Here, the "protrusion 8" means a portion where the particles 6 protrude on the surface of the coating film (hard coat layer 2), and the height (height of the convex portion 8) H means a smooth portion of the coating film in the absence of the particles 6. The cut line drawn and the shortest distance (μm) of the tangent drawn at the upper end portion of the convex portion 8. The "mountain-level flat area" means the bottom surface of the coating film portion which is in contact with the periphery of the convex portion 8 with a slanted circular area having a height of 0.1 μm when the plane is convex, and the length (the length of the mountain foot grading area) L means the diameter (μm) of the bottom surface of the circular area.

In the present embodiment, the height H of the convex portion 8 is preferably 0.3 μm or more, and preferably 0.4 μm or more, in consideration of the Newton's ring prevention property. On the other hand, from the viewpoint of preventing the fall of the particles 6 on the surface of the coating film, it is preferably 8 μm or less, and more preferably 6 μm or less.

In the present embodiment, the length L of the mountain sloping region is preferably 80 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, and most preferably 37 μm or less, in consideration of the flash prevention property. On the other hand, from the viewpoint of taking into account Newton's ring prevention property and flash prevention property, it is preferably 3 μm or more, and more preferably 4 μm or more.

In the present embodiment, the height H of the convex portion 8 and the length L of the footrest gentle region can be, for example, a confocal laser microscope (VK-). 9710, KEYENCE Co., Ltd.) The cross-sectional shape of the coating film which was imaged was obtained. Further, it can be obtained by three-dimensional information on the surface shape of the coating film measured by various devices such as a confocal microscope, an interference microscope, and an atomic force microscope (AFM).

From the viewpoint of preventing damage, the hard coat layer 2 has a degree that it does not damage even if the steel wool #0000 is caused by a load of 200 g/2 cm ² or more, 5 times or more (preferably 10 times). The surface hardness is better. In particular, in the present embodiment, the thermoplastic resin/thermosetting resin blended together with the ionizing radiation-curable resin is introduced with a photocurable unsaturated group, so that the surface of the hard coat layer 2 can be made of steel wool #0000. The number of round trips caused is more than 10 times.

In the scattering preventing sheet of the present embodiment, if the adhesive layer 3 is provided (FIG. 2), the same optical adhesive as the adhesive of the display device and the touch panel can be used as the adhesive layer.

The scattering preventing sheet of the present invention is described as an example of the scattering preventing sheet of the present invention. However, the scattering preventing sheet of the present invention is not limited to the structure of FIG. 2, and the unnecessary elements of the scattering preventing sheet of the present invention may be omitted or added. Other elements not shown, such scattering prevention sheets are also included in the present invention.

Next, an application example of the scattering preventing sheet of the embodiment will be described. The scattering preventing sheet of the present embodiment is applicable to various display devices as long as it has a surface disposed to face the inside. However, in a representative application example, the scattering preventing sheet of the present embodiment is used. A display device of a capacitive touch panel will be described.

As shown in FIG. 1 , the display device 35 with the capacitive touch panel is fixed to the display device 34 by an optical adhesive (OCA: Optically Clear Adhesive) 33, and the capacitive touch panel with the scattering preventing sheet 1 is fixed. 32, as the main component. The scattering preventing sheet 1 is disposed on the opposite side of the touch surface 31 of the capacitive touch panel 32, and the hard coat layer 2 of the scattering preventing sheet 1 faces the display device 34. The display device 35 with the capacitive touch panel uses the optical adhesive 33 to fix only the outer edge portion of the capacitive touch panel 32 to the display device 34.

Examples of the display device 34 include a liquid crystal display device, a CRT display device, a plasma display device, and an EL display device.

As the capacitive touch panel 32, a conventional capacitive touch panel can be used, and a capacitive touch panel having a surface type structure or a projection type structure can be used.

The optical adhesive 33 can use a well-known adhesive used for optical use of the capacitive touch panel 32, such as a natural rubber adhesive, a synthetic rubber adhesive, an acrylic adhesive, and an urethane adhesive. Or a bismuth-based adhesive. The adhesive may be any of a solvent system, a solvent-free system, an emulsion system, or a water system. Among them, from the viewpoints of transparency, weather resistance, durability, and cost, it is also preferable to use an acrylic adhesive, especially a solvent.

FIG. 1 shows a surface type structure in which only the outer edge portion of the capacitive touch panel 32 is fixed to the display device 34 by the optical adhesive 33, but it is also applicable to the full connection of the capacitive touch panel 32. The surface type structure of the display device 34 is shown.

Further, the scattering preventing sheet of the embodiment can be used in any of large or small display devices.

[Examples]

Hereinafter, examples of further embodying the embodiments of the present invention will be described in further detail. In the following examples, "parts" and "%" refer to the weight basis unless otherwise specified.

1. Synthesis of Resin A

150 parts by weight of methyl isobutyl ketone was supplied as a solvent in the reaction vessel, and the mixture was heated and maintained at 90 °C. 61 parts by weight of methyl methacrylate, 26 parts by weight of glycidyl methacrylate, and 1.5 parts by weight of azobis-2-methylbutyronitrile as a radical polymerization initiator were gradually added over 2 hours. After dropping into the reaction vessel, it was allowed to stand for 4 hours. Thereafter, the polymerization was carried out by heating at 120 ° C for 1 hour to obtain a polymer.

Next, after cooling the polymer to 60 ° C, 13 parts by weight of acrylic acid, 0.05 parts by weight of p-methoxyphenol as a polymerization inhibitor, and 0.5 parts by weight of triphenylphosphine as a catalyst were mixed in a polymer to obtain a mixture. Thereafter, the mixture was heated at 110 ° C for 8 hours to add acrylic acid to the polymer. Thereby, the resin A (nonvolatile content 40%) in which an acrylonitrile group (photocurable unsaturated group) was introduced into the thermosetting resin was produced. The resin A-based glass had a transfer point of 86 ° C and a weight average molecular weight of 80,000.

2. Flying to prevent the formation of thin sheets [Example 1]

On one side of a transparent polyester film (Cosmo Shine A4350: Toyobo Co., Ltd.) having a thickness of 125 μm, the coating liquid of the following formulation was applied, dried, and then irradiated with ultraviolet rays to form a hard coat layer having a thickness of 3 μm to obtain the hard coat layer of Example 1. Scattered to prevent flakes.

<Coating solution for hard coating>

Here, in Example 1, the ratio of the acrylic resin particles to the total resin solid content of the hard coat layer was 0.05% by weight. Further, in Examples 1 to 7 and Comparative Examples 1 and 2 of Example 1 and below, the ratio of the resin A to the total resin was 28% by weight.

[Embodiment 2]

In addition to the acrylic resin particles in the coating liquid for hard coat layer of Example 1. The scattering preventing sheet of Example 2 was obtained in the same manner as in Example 1 except that the content of the sub-component was changed to 0.14 parts (0.1% by weight).

[Example 3]

In the same manner as in Example 1, except that the acrylic resin particles in the coating liquid for a hard coat layer of Example 1 were changed to acrylic resin particles (MX-300: Izumi Chemical Industry Co., Ltd., average particle diameter: 3 μm) having different average particle diameters. The scattering preventing sheet of Example 3 was obtained.

[Example 4]

The scattering preventing sheet of Example 4 was obtained in the same manner as in Example 3 except that the content of the acrylic resin particles in the coating liquid for a hard coat layer of Example 3 was changed to 0.14 parts (0.1% by weight).

[Comparative Example 1]

The scattering preventing sheet of Comparative Example 1 was obtained in the same manner as in Example 3 except that the content of the acrylic resin particles in the coating liquid for a hard coat layer of Example 3 was changed to 0.42 parts (0.3% by weight).

[Example 5]

In the same manner as in Example 1, except that the acrylic resin particles in the coating liquid for a hard coat layer of Example 1 were changed to acrylic resin particles (MX-500: Izumi Chemical Industry Co., Ltd., average particle diameter: 5 μm) having different average particle diameters. The scattering preventing sheet of Example 5 was obtained.

[Embodiment 6]

The scattering preventing sheet of Example 6 was obtained in the same manner as in Example 5 except that the content of the acrylic resin particles in the coating liquid for a hard coat layer of Example 5 was changed to 0.14 parts (0.1% by weight).

[Comparative Example 2]

The scattering preventing sheet of Comparative Example 2 was obtained in the same manner as in Example 5 except that the content of the acrylic resin particles in the coating liquid for a hard coat layer of Example 5 was changed to 0.42 parts (0.3% by weight).

[Comparative Example 3]

The scattering preventing sheet of Comparative Example 3 was obtained in the same manner as in Example 1 except that the coating liquid for hard coat layer of Example 1 was changed to the following formulation.

<Coating solution for hard coating>

In Comparative Example 3, the ratio of the resin A to the total resin was 10% by weight.

[Comparative Example 4]

The scattering preventing sheet of Comparative Example 4 was obtained in the same manner as in Example 1 except that the acrylic resin particles in the coating liquid for hard coat layer of Example 1 were excluded.

[Comparative Example 5]

The acrylic resin particles in the coating liquid for hard coat layer of Example 1 were changed to colloidal vermiculite dispersions having different average particle diameters (SIRMIBK (solid content: 30%): CIK NanoTek, Inc., average particle diameter of colloidal vermiculite A scattering preventing sheet of Comparative Example 5 was obtained in the same manner as in Example 1 except that the content was changed to 153 parts (33% by weight).

The details of the resins and particles used in the examples and comparative examples are collectively shown in Table 1.

3. Evaluation

The following evaluations were carried out regarding the scattering preventing sheets obtained in the respective examples and comparative examples.

(1) Number of particles, area ratio of convex portions, and area ratio of flat portions

The surface of each of the scatter prevention sheets was photographed at a magnification of 100 times using a digital microscope VHX-100 (manufactured by KEYENCE), and the image was taken into the binary image analysis software WinROOF (Sangu Business Co., Ltd.), and the 6.3 mm ² range was subjected to a black and white image. Treatment (2-valued trough method). The area of the white portion and the black portion in the black-and-white image after the treatment was calculated, and the area of the convex portion and the area of the flat portion were respectively formed.

The convex portion area was divided by the measurement range of 6.3 mm ² to calculate the convex portion area ratio. The flat portion area ratio was calculated from the convex portion area ratio calculated by 100% reduction.

(2) arithmetic mean roughness

Atomic force microscopy (machine name: Nanocute system manufactured by Hitachi High-Tech Science Co., Ltd., specification: JIS B0601: 2001, probe: Si single crystal probe, measurement mode: DFM mode, image processing: flat processing (XY) (1)) The arithmetic mean roughness of the uneven surface of the scattering preventing sheet was determined.

100 μm × 100 μm of each scattering prevention sheet was observed by an atomic force microscope, and 10 μm × 10 μm was used as a measurement portion of the convex portion as a center, and 10 μm × 10 μm was flat as a center without a convex portion. Part of the measurement area, take the image, press The arithmetic mean roughness was obtained for each measurement zone.

In the comparative example 5, the fine convex portion was formed substantially uniformly and the region in which the convex portion was not divided and the region having the concave portion were not uniformly formed in the measurement region. Therefore, the arithmetic mean roughness was obtained for the measurement region (10 μm × 10 μm).

(3) Flash

After the display screen of the wide VGA liquid crystal display device having a size of 3 吋 and a resolution of 480×854 dpi is displayed in full green, each scattering preventing sheet is placed on the display screen, and the liquid crystal display screen is visually observed. As a result, it is impossible to visually recognize that the flasher is set to "◎", and although the flash is slightly recognized, the obstacle is not set to "○", and it is visually recognized that the flasher is set to "x".

(4) Newton ring prevention

Each of the scattering preventing sheets was placed so that the uneven surface was in close contact with the glass plate having a smooth surface, and the finger was pressed with a finger, and the state of occurrence of the Newton's ring was visually confirmed. As a result, the person who does not see the Newton ring is set to "○", and the person who sees the Newton ring is set to "X".

(5) Watermark

A sample piece of 3 cm square was cut out from each of the scattering preventing sheets, and each of the sample pieces was placed on a glass plate having a smooth contact surface with a concave-convex surface. A silicone cube (size: 2.5 mm square) was placed on the corner 4 of the scattering prevention sheet (sample piece), and a glass plate was placed thereon, and a weight (weight: 1 Kg) was placed, and 4 kg was applied to the entire sheet. /cm ² load. In this state, after heating at 110 ° C for 10 minutes, it was visually confirmed whether or not a watermark occurred.

It is impossible to visually recognize that the watermarker is set to "○", and it is visually recognized that the watermarker is set to "X".

The evaluation results are summarized in Table 2.

As is clear from the results shown in Table 2, in the hard coat layer using the specific resin A, the amount of the particles was not more than 0.3% by weight of the solid content of the resin, and the area ratio of the flat portion was 98% or more. The optical characteristics of the inner sheet are satisfied, and a scattering preventing sheet excellent in Newton's ring prevention property and adhesion prevention property is provided.

Claims (6)

A scattering preventing sheet comprising a layer containing particles and a resin, and having a plurality of convex portions on the surface thereof, and a scattering preventing sheet attached to a surface of the member constituting the display device facing the inside of the display device, The particle-based average particle diameter is 0.5 to 10 μm, and the content is less than 0.3% by weight of the resin solid content constituting the layer, and the resin is introduced into the thermoplastic resin or the thermosetting resin to have photocurability. The unsaturated group contains an ionizing radiation-curable resin having a weight average molecular weight of 70,000 or more and a glass transition temperature of 45 ° C or more in an amount of more than 15% by weight and 50% by weight or less in the total resin. The scattering preventing sheet according to the first aspect of the invention is characterized in that the area of the flat portion of the convex portion which does not have the particles is 98% or more. The scattering preventing sheet according to the first aspect of the patent application, wherein the haze (JIS K7136:2000) is 2.0% or less. The scattering preventing sheet according to the first aspect of the invention, wherein the aspect ratio of the convex portion is 0.043 to 0.2. The scattering preventing sheet according to the first aspect of the invention, wherein the height of the convex portion is 0.3 to 8 μm. The scattering preventing sheet according to the first aspect of the patent application, wherein the length of the flat portion of the convex portion is 3 to 80 μm.