KR20160006743A - Laminated adhesive sheet and laminate - Google Patents

Abstract

It is an object of the present invention to find a method for more accurately controlling the relative dielectric constant and to provide a pressure sensitive adhesive sheet whose relative dielectric constant is controlled according to the control method. The present invention relates to a laminated adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, wherein the absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure- To an adhesive sheet. The present invention also relates to a laminated pressure sensitive adhesive sheet comprising a first pressure sensitive adhesive layer having a relative dielectric constant of less than 4 at a frequency of 1 MHz and a second pressure sensitive adhesive layer having a relative dielectric constant of 4 or more at a frequency of 1 MHz.

Description

[0001] LAMINATED ADHESIVE SHEET AND LAMINATE [0002]

The present invention relates to a laminated adhesive sheet and a laminate. Specifically, the present invention relates to a laminated adhesive sheet having controlled relative dielectric constant, which can exhibit desired tackiness.

2. Description of the Related Art In recent years, input devices used in combination with display devices such as liquid crystal displays (LCD) and display devices such as touch panels have been widely used in various fields. In manufacturing these display devices and input devices, transparent double-sided pressure-sensitive adhesive sheets are used for bonding optical members, and transparent double-sided pressure-sensitive adhesive sheets are used for bonding display devices and input devices (see, for example, Patent Documents 1 to 3 ).

In such a display device and an input device, the pressure-sensitive adhesive sheet is not required to have only adhesive property, but various functions such as insulation characteristics are required. For example, Patent Document 4 discloses a pressure-sensitive adhesive sheet of a laminate type having a different dielectric constant. Patent Document 5 discloses a single-layer type pressure-sensitive adhesive sheet having a specific permittivity or dielectric tangent. As described above, it has been proposed to improve the operation performance of the touch panel by controlling the dielectric constant of the adhesive sheet.

Japanese Patent Application Laid-Open No. 2003-238915 Japanese Patent Application Laid-Open No. 2003-342542 Japanese Patent Application Laid-Open No. 2004-231723 Japanese Patent Publication No. 4093355 International publication publication 2010/147047 pamphlet

As described above, it is required that the dielectric constant of the pressure-sensitive adhesive sheet is controlled to be within a predetermined range in accordance with the performance required for the display device and the input device. However, since the relative dielectric constant is a property value inherent to a material, it is never easy to precisely control it, and it has been required to find a method of controlling the relative dielectric constant more accurately.

In order to solve the problems of the prior art, the inventors of the present invention have studied a method for more accurately controlling the relative dielectric constant and provide a pressure sensitive adhesive sheet having a controlled relative dielectric constant according to the control method.

As a result of diligent studies to solve the above problems, the inventors of the present invention have found that, in a laminated adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, the relative permittivity and thickness of the first pressure- It was found that the relative dielectric constant of the laminated adhesive sheet can be adjusted by adjusting the electric conductivity and the thickness to be the specific conditions. Thus, the present inventors succeeded in obtaining a laminated pressure-sensitive adhesive sheet in which the relative dielectric constant was controlled, and thus completed the present invention.

Specifically, the present invention has the following configuration.

[1] A laminated adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, wherein an absolute value of a difference in relative permittivity at a frequency of 1 MHz between the first pressure-sensitive adhesive layer and the second pressure- And the adhesive sheet.

[2] A laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, comprising a first pressure-sensitive adhesive layer having a relative dielectric constant of less than 4 at a frequency of 1 MHz and a second pressure-sensitive adhesive layer Sensitive adhesive sheet according to < RTI ID = 0.0 > [1]. ≪ / RTI >

[3] The laminated adhesive sheet according to [1] or [2], wherein the first pressure sensitive adhesive layer has a relative dielectric constant of less than 3 at a frequency of 1 MHz.

[4] The laminated adhesive sheet according to any one of [1] to [3], wherein the thickness of each layer of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 10 μm or more.

[5] The laminated adhesive sheet according to any one of [1] to [4], wherein the ratio of the thickness of the first pressure sensitive adhesive layer to the thickness of the second pressure sensitive adhesive layer is 1:99 to 99: 1.

[6] The laminated adhesive sheet according to any one of [1] to [5], wherein the first pressure sensitive adhesive layer and the second pressure sensitive adhesive layer are acrylic pressure sensitive adhesive layers.

[7] The laminated adhesive sheet according to any one of [1] to [6], wherein the first pressure sensitive adhesive layer and the second pressure sensitive adhesive layer comprise a (meth) acrylic acid ester.

[8] The laminated adhesive sheet according to any one of [1] to [7], further comprising a third pressure-sensitive adhesive layer.

[9] The laminated adhesive sheet according to any one of [1] to [8], further comprising a resin layer.

[10] The laminated adhesive sheet of [9], wherein the resin layer is formed between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.

[11] The laminate adhesive according to [9], wherein the first pressure sensitive adhesive layer is laminated on the resin layer, and the second pressure sensitive adhesive layer is laminated on the opposite side of the resin layer with the first pressure sensitive adhesive layer interposed therebetween Sheet.

[12] The laminated adhesive sheet according to any one of [9] to [11], wherein the relative dielectric constant of the resin layer at a frequency of 1 MHz is 2 to 10.

[13] A laminate characterized in that the laminated adhesive sheet according to any one of [1] to [12] is adhered to at least one optical member.

[14] The laminate according to [13], wherein at least one of the optical members is an ITO glass or an ITO film.

[15] A method of adjusting a relative permittivity of a laminated adhesive sheet having at least two pressure sensitive adhesive layers, wherein the laminated pressure sensitive adhesive sheet comprises a first pressure sensitive adhesive layer having a relative dielectric constant of less than 4 at a frequency of 1 MHz, The relative dielectric constant and thickness of the first pressure sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant and thickness at the frequency of 1 MHz of the second pressure sensitive adhesive layer were adjusted respectively, And the relative dielectric constant of the dielectric layer is adjusted.

The specific dielectric constant and thickness of the first pressure sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant and thickness at a frequency of 1 MHz of the second pressure sensitive adhesive layer are adjusted using the following equation (1) The method for adjusting the relative dielectric constant according to [15].

(Formula (1) of the, ε denotes a relative dielectric constant of a multilayer pressure-sensitive adhesive sheet, d represents the whole laminated adhesive sheet thickness. In addition, ε _n denotes the relative dielectric constant of each of the pressure-sensitive adhesive layer, d _n are each a pressure-sensitive adhesive layer Where n represents the number of layers of the pressure-sensitive adhesive layer).

[17] The relative dielectric constant adjusting method according to [16], wherein d _{1 to} d _n are determined to be a specific ε under the condition that ε _{1 to} ε _n are fixed in the above formula (1).

(18) In the above formula (1), ε ₁ to ε _n-1 and d _{1 to} d _n-1 are determined so as to become a specific ε under the condition that ε _n and d _n are fixed. 16].

[19] The relative dielectric constant adjusting method according to any one of [16] to [18], wherein n is 2 in the formula (1).

[20] A method for producing a laminated adhesive sheet having at least two pressure-sensitive adhesive layers, characterized in that the relative dielectric constant of the laminated adhesive sheet is adjusted according to the relative dielectric constant adjusting method described in any one of [16] to [19] A method for producing a laminated adhesive sheet.

According to the present invention, it is possible to provide a method for more accurately controlling the relative dielectric constant in the laminated adhesive sheet. Therefore, in the present invention, a laminated adhesive sheet having a desired relative dielectric constant can be obtained. Further, in the present invention, since the relative permittivity can be accurately controlled in the laminated pressure sensitive adhesive sheet, the production efficiency of the laminated pressure sensitive adhesive sheet can be enhanced, and the fine requirements required when the laminated body is produced can be satisfied.

1 is a schematic sectional view of a laminated adhesive sheet of the present invention.
2 is a schematic cross-sectional view showing another embodiment of the laminated adhesive sheet of the present invention.

Hereinafter, the present invention will be described in detail. Descriptions of the constituent elements described below can be made based on representative embodiments and concrete examples, but the present invention is not limited to these embodiments. In the present specification, a numerical range indicated by "~" means a range including numerical values written before and after "~" as a lower limit value and an upper limit value.

(Laminated adhesive sheet)

The present invention relates to a laminated adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer. In the laminated adhesive sheet of the present invention, the absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a frequency of 1 MHz is 0.5 or more. The relative dielectric constant of the first pressure-sensitive adhesive layer of the laminated pressure-sensitive adhesive sheet of the present invention at a frequency of 1 MHz is less than 4, and the relative dielectric constant of the second pressure-sensitive adhesive layer at a frequency of 1 MHz is preferably 4 or more. Further, the laminated adhesive sheet of the present invention can function as a double-sided pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer.

1 (a) to 1 (d) are schematic sectional views of a laminated adhesive sheet 10 of the present invention. As shown in Figs. 1 (a) to 1 (c), the laminated adhesive sheet 10 has a first pressure-sensitive adhesive layer 1 and a second pressure-sensitive adhesive layer 2. Fig. 1A to 1C, the laminated adhesive sheet 10 is composed of only the first pressure-sensitive adhesive layer 1 and the second pressure-sensitive adhesive layer 2, but may have another functional layer or a pressure-sensitive adhesive layer. For example, as shown in Fig. 1 (d), the laminated adhesive sheet 10 of the present invention has the third pressure sensitive adhesive layer 3 in addition to the first pressure sensitive adhesive layer 1 and the second pressure sensitive adhesive layer 2, . When the laminated adhesive sheet 10 has a functional layer other than the pressure-sensitive adhesive layer, at least one of the first pressure-sensitive adhesive layer 1, the second pressure-sensitive adhesive layer 2 and the third pressure- .

In the laminated adhesive sheet of the present invention, the absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.5 or more. The absolute value of the difference between the relative permittivities of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably 1 or more, more preferably 2 or more. By setting the relative permittivity difference between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer within the above ranges, the relative dielectric constant of the laminated pressure sensitive adhesive sheet can be easily adjusted and the relative dielectric constant of the laminated pressure sensitive adhesive sheet can be adjusted more precisely.

In the present invention, the relative dielectric constant of the first pressure-sensitive adhesive layer at a frequency of 1 MHz is preferably less than 4, more preferably less than 3, even more preferably less than 2.5, even more preferably less than 2. By setting the specific permittivity of the first pressure sensitive adhesive layer at the frequency of 1 MHz within the above range, the relative dielectric constant of the entire laminated pressure sensitive adhesive sheet can be more efficiently controlled. In addition, it is also possible to suppress the relative dielectric constant of the entire laminated adhesive sheet to a low value.

The relative dielectric constant of the second pressure-sensitive adhesive layer at a frequency of 1 MHz is preferably 4 or more, more preferably 4.5 or more, further preferably 5 or more, and still more preferably 5.5 or more. Thus, by setting the specific permittivity of the first pressure-sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant of the second pressure-sensitive adhesive layer at a frequency of 1 MHz within a specific range, the relative dielectric constant of the entire laminated pressure-sensitive adhesive sheet can be controlled.

Here, the relative dielectric constant? In the present invention can be determined by the method specified in JIS-C-2138.

The ratio of the thickness of the first pressure sensitive adhesive layer to that of the second pressure sensitive adhesive layer is preferably 1: 99 to 99: 1. Thus, by adjusting the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, the relative dielectric constant of the entire laminated pressure-sensitive adhesive sheet can be controlled.

In the laminated adhesive sheet of the present invention, by forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer under specific conditions, the relative dielectric constant of the entire laminated pressure-sensitive adhesive sheet can be controlled. More specifically, the relative dielectric constant of the laminated adhesive sheet can be controlled by adjusting the relative dielectric constant and thickness of the first pressure-sensitive adhesive layer and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer, respectively.

In the present invention, the relative dielectric constant and thickness of the first pressure-sensitive adhesive layer and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer can be adjusted using the following equation (1).

Here, in the formula (1),? Represents the relative dielectric constant of the entire laminated pressure sensitive adhesive sheet, and d represents the total thickness of the laminated pressure sensitive adhesive sheet. Also,? _N represents the relative dielectric constant of each pressure-sensitive adhesive layer, and d _n represents the thickness of each pressure-sensitive adhesive layer. Here, n represents the number of layers of the pressure-sensitive adhesive layer.

In the present invention, the relative dielectric constant and thickness of the first pressure-sensitive adhesive layer and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer can be calculated using the above formula (1) when forming a laminated pressure-sensitive adhesive sheet having a specific relative permittivity. That is, the relative dielectric constant and thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer can be calculated when the relative dielectric constant required for the laminated pressure-sensitive adhesive sheet is determined and the required thickness of the laminated pressure-sensitive adhesive sheet is determined.

In the present invention, specifically, it is preferable to adjust the dielectric constant under the following conditions. For example, d _{1 to} d _n can be determined to be a specific epsilon under the condition that? _{1 to} ? _N are fixed in the above formula (1). Further, under a condition in which ε _n and d _n is fixed in the above formula (1) it can be determined ε ₁ ~ε _n-1 and d ₁ ~d _n-1.

As described above, by setting the conditions in accordance with the mode of the laminated adhesive sheet, it is possible to form a laminated adhesive sheet having a desired relative dielectric constant while selecting a pressure-sensitive adhesive having adhesive property according to the adherend using the above-mentioned formula (1).

In the present invention, n in the formula (1) is preferably 2 to 6, more preferably 2 to 4, and even more preferably 2 or 3. By using the above formula (1), the relative dielectric constant of the laminated adhesive sheet having two or more pressure-sensitive adhesive layers can be easily adjusted.

The laminated pressure sensitive adhesive sheet of the present invention may have a third pressure sensitive adhesive layer. When the laminated adhesive sheet has the third pressure-sensitive adhesive layer, the third pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer having the same relative dielectric constant as that of the first pressure-sensitive adhesive layer or the second pressure-sensitive adhesive layer not adjacent to the pressure- Sensitive adhesive layer having the same relative dielectric constant as the layer. That is, the third pressure-sensitive adhesive layer may have the same relative dielectric constant as that of the adjacent pressure-sensitive adhesive layer, or may have a different relative dielectric constant. When the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer are laminated in this order, the relative dielectric constants of the first pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer may be the same.

The third pressure sensitive adhesive layer may be a pressure sensitive adhesive layer having a relative dielectric constant different from that of any one of the first pressure sensitive adhesive layer and the second pressure sensitive adhesive layer. When the laminated adhesive sheet has the third pressure sensitive adhesive layer, the absolute value of the difference between the relative dielectric constant of the third pressure sensitive adhesive layer and the relative dielectric constant of the adjacent first pressure sensitive adhesive layer or second pressure sensitive adhesive layer is preferably 0.5 or more, And more preferably 2 or more. The absolute value of the difference in relative dielectric constant between all of the pressure-sensitive adhesive layers is also preferably within the above range. That is, the absolute value of the difference between the relative permittivity of the first pressure-sensitive adhesive layer and the relative permittivity of the second pressure-sensitive adhesive layer preferably falls within the above range, and the absolute value of the difference between the relative dielectric constant of the second pressure- Is preferably within the above range, and it is preferable that the absolute value of the difference between the relative permittivities of the first pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer is within the above range.

When the laminated pressure sensitive adhesive sheet has three or more pressure sensitive adhesive layers, it is preferable that ∈ _{2 to} ε _n-1 and d _{2 to} d (d) are formed under conditions that ε ₁ and ε _n , d ₁ and d _n are fixed in the above- _n-1 may be determined. In this case, a laminated adhesive sheet having a desired relative dielectric constant can be formed by adjusting the relative dielectric constant and thickness of the pressure-sensitive adhesive layer existing inside the laminated pressure-sensitive adhesive sheet.

That is, in the case of a laminated pressure-sensitive adhesive sheet in which n is 3 or more, it is possible to set in advance a pressure-sensitive adhesive having appropriate adhesive properties according to an adherend as a pressure-sensitive adhesive layer (hereinafter referred to as an outermost pressure- By using the formula (1), the thickness of the layer other than the outermost pressure-sensitive adhesive layer for making the dielectric constant of the entire laminated pressure-sensitive adhesive sheet a desired value can be obtained. As a result, a laminated pressure-sensitive adhesive sheet capable of simultaneously achieving a desired adhesive property and a dielectric constant can be obtained.

The thickness of each layer of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer of the laminated pressure-sensitive adhesive sheet of the present invention is preferably 10 占 퐉 or more. When the lower limit value is not less than the lower limit value, the relative dielectric constant of the entire laminated adhesive sheet can be precisely adjusted. The thickness of the entire laminated pressure sensitive adhesive sheet is preferably 20 to 1000 占 퐉, more preferably 10 to 100 占 퐉, and more preferably 25 to 50 占 퐉. By adjusting the thickness of the outermost pressure-sensitive adhesive layer within the above-mentioned range, a laminated pressure-sensitive adhesive sheet having an adhesive property according to an adherend is obtained. Further, even when the laminated adhesive sheet of the present invention has the third pressure-sensitive adhesive layer, the thickness of the third pressure-sensitive adhesive layer is preferably within the above range.

As described above, the present invention relates to a method of adjusting the relative dielectric constant of a laminated adhesive sheet having at least two pressure-sensitive adhesive layers, and a method of adjusting the relative dielectric constant using the above formula (1). By using the method of adjusting the relative dielectric constant of the present invention, it is possible to easily form a laminated adhesive sheet having various relative permittivities. As a result, the relative dielectric constant of the entire laminated adhesive sheet can be precisely controlled.

The present invention also provides a method for producing a laminated adhesive sheet having at least two pressure-sensitive adhesive layers, comprising the step of adjusting the relative dielectric constant of the laminated pressure-sensitive adhesive sheet according to the relative dielectric constant adjusting method using the formula (1) And a method for producing the same. By using such a manufacturing method, the production efficiency of the laminated adhesive sheet can be increased.

(adhesive)

As the main adhesive agent for forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, those having transparency are preferably used so as not to lower the visibility of the display device or the like. For example, known pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, rubber pressure-sensitive adhesives, and polyurethane pressure-sensitive adhesives can be used. Among them, an acrylic pressure-sensitive adhesive is preferably used, and an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base polymer is preferable.

<Acrylic Polymer>

The acrylic polymer contains an acrylic monomer unit having a non-crosslinkable (meth) acrylic acid ester unit and a crosslinkable functional group. Here, the &quot; monomer unit &quot; is a repeating unit constituting the polymer. The "acrylic monomer" is a compound having a (meth) acryloyl group. The "(meth) acryloyl group" represents an acryloyl group or a methacryloyl group. The non-crosslinkable acrylic monomer is an acrylic monomer having no crosslinkable group, and the crosslinkable monomer is a monomer having a crosslinkable group. The crosslinkable monomer may be either an acrylic monomer or a non-acrylic monomer, preferably an acrylic monomer, as long as it is capable of polymerization with an incompatible acrylic monomer. Examples of the crosslinkable group include a carboxyl group, a hydroxyl group, an amino group, an epoxy group and a glycidyl group.

Examples of the non-crosslinkable acrylic monomer unit include (meth) acrylic acid ester units in which the hydrogen atom of the carboxyl group of (meth) acrylic acid is substituted with a hydrocarbon group. In the present invention, each of the pressure-sensitive adhesive layers preferably contains a (meth) acrylic acid ester unit.

The number of carbon atoms of the hydrocarbon group in the (meth) acrylic acid ester unit is preferably from 1 to 18, more preferably from 1 to 8. The hydrocarbon group may have a substituent, and the substituent is not particularly limited as long as it does not contain a crosslinkable group, and examples thereof include an alkoxy group such as a methoxy group and an ethoxy group.

Specific examples of the (meth) acrylic esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, (Meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (Meth) acrylate, n-nonyl acrylate, isobornyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate and benzyl (meth) acrylate. Of these, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl acrylate are preferably used from the viewpoint of adhesiveness. These may be used singly or in combination of two or more. Here, in the present invention, the term "(meth) acrylic acid" means that it includes both "acrylic acid" and "methacrylic acid".

Examples of the crosslinkable monomer unit include a carboxyl group-containing copolymerizable monomer unit, a hydroxy group-containing copolymerizable monomer unit, an amino group-containing copolymerizable monomer unit and a glycidyl group-containing copolymerizable monomer unit. Examples of the carboxyl group-containing copolymerizable monomer include an?,? - unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, .

Examples of the hydroxy group-containing copolymerizable monomers include (meth) acrylic acid hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylic acid [(mono, di or poly) alkylene glycols such as (meth) acrylic acid mono (diethylene glycol), and (meth) acrylic acid monocaprolactone.

Examples of the amino group-containing copolymerizable monomers include (meth) acrylamide and allylamide.

Examples of the glycidyl group-containing copolymerizable monomers include glycidyl (meth) acrylate and the like.

Of these, hydroxy group-containing copolymerizable monomers are preferable from the viewpoint of adhesiveness, crosslinkability and polymerizability, and corrosion resistance of metals such as tin-doped indium oxide used in transparent conductive films and copper used for electromagnetic shielding. Hydroxyethyl (meth) acrylate is more preferable, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are particularly preferable.

In addition, when a carboxyl group-containing copolymerizable monomer unit is contained as a crosslinkable monomer unit, the acidity is increased, and if such a corrosion-resistant film such as a tin-doped indium oxide film or a metal film is in contact, these films may be corroded. Therefore, in the case of containing a carboxyl group-containing copolymerizable monomer unit as a crosslinkable monomer unit, the content thereof is preferably less than 0.5% by mass, and more preferably not contained at all. The content of the carboxyl group-containing copolymerizable monomer unit in the acrylic polymer is preferably less than 1.0% by mass from the standpoint of corrosion resistance as a whole in the laminated pressure-sensitive adhesive sheet.

The acrylic polymer may also have non-cross-linkable acrylic monomer units and other monomer units other than cross-linking monomer units. Examples of other monomers include (meth) acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinyl pyrrolidone, and vinyl pyridine.

The content of other monomer units in the acrylic polymer is preferably 0.1 to 20 mass%, more preferably 0.5 to 10 mass%. When the content of other monomer units is not less than the lower limit value, physical properties can be easily adjusted. If the content is below the upper limit value, yellowing due to deterioration with time can be prevented.

The relative dielectric constant of each pressure-sensitive adhesive layer can be set to a desired value by appropriately selecting the kind of resin used in the pressure-sensitive adhesive. For example, when the relative dielectric constant is increased, a (meth) acrylic acid ester unit having relatively high polarity such as methyl (meth) acrylate, ethyl (meth) acrylate, , N-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth) acrylate. Among them, methyl (meth) acrylate and n-butyl (meth) acrylate are preferred from the viewpoints of transparency and adhesion between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.

As the crosslinkable monomer unit, a carboxyl group-containing copolymerizable monomer unit, a hydroxy group-containing copolymerizable monomer unit and an amino group-containing copolymerizable monomer unit may be used which have a relatively high polarity. Examples of the carboxyl group-containing copolymerizable monomer include Examples of the?,? - unsaturated carboxylic acids, anhydrides and hydroxy group-containing copolymerizable monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and glutaconic acid, (Meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, hydroxyalkyl (Meth) acrylic acid [(mono, di or poly) alkylene glycol] such as (meth) acrylic acid, monocaprolactone such as Include, for example, (meth) acrylamide, allylamide and the like. Of these, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable because the proportion of the polar groups in the whole molecule becomes high in view of easy control of the relative dielectric constant.

On the other hand, in the case of lowering the relative dielectric constant of the pressure-sensitive adhesive layer, one having a low polarity may be used. (Meth) acrylate, n-octyl (meth) acrylate, isononyl (meth) acrylate, isononyl (meth) acrylate, N-decyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl And isobornyl acrylate. From the viewpoint of transparency and adhesiveness of the pressure-sensitive adhesive layer, it is preferable to use 2-ethylhexyl (meth) acrylate, (meth) acrylic acid Isobornyl methacrylate is preferable.

<Cross-linking agent>

A crosslinking agent may be used for each of the pressure-sensitive adhesive layers. Examples of the crosslinking agent include an isocyanate compound, an epoxy compound, an oxazoline compound, an aziridine compound, a metal chelate compound, and a butylated melamine compound. Among these crosslinking agents, an isocyanate compound and an epoxy compound are preferable in that the acrylic polymer can be easily crosslinked. Particularly, when the acrylic polymer contains only a hydroxy group-containing copolymerizable monomer unit as a crosslinkable monomer unit, it is preferable to use an isocyanate compound in view of the reactivity of the hydroxy group.

Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like. Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neo 1,6-hexanediol diglycidyl ether, tetraglycidyl xylene diamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylol Propylene polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether. The content of the crosslinking agent is desirably selected appropriately according to the desired adhesive property.

[additive]

Further, each of the pressure-sensitive adhesive layers may contain other additives such as antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and fillers, if necessary.

Examples of the antioxidant include a phenol-based antioxidant, an amine-based antioxidant, a lactone-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant. These antioxidants may be used alone or in combination of two or more.

As the metal corrosion inhibitor, a benzotriazole-based resin is preferable because the compatibility and the effect of the pressure-sensitive adhesive are high.

Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, coumaroneindene resin, styrene resin, xylene resin, phenol resin, petroleum resin and the like.

As the silane coupling agent, for example, a mercaptoalkoxysilane compound (e.g., a mercapto group-substituted alkoxy oligomer) can be mentioned.

Examples of the ultraviolet absorber include benzotriazole-based compounds, benzophenone-based compounds, and the like.

(Resin layer)

The laminated adhesive sheet of the present invention may further comprise a resin layer in addition to the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer. The resin layer may be a pressure-sensitive adhesive layer or a non-adhesive resin layer. It may be a single layer or a plurality of layers. When the resin layer is a non-tacky resin layer, it is preferable that the resin used does not affect the optical properties, and examples thereof include polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, Triacetyl cellulose, polyimide, and cellulose acylate.

It is preferable that the adhesive subject in the case where the resin layer is the pressure sensitive adhesive layer has transparency to such an extent that the visibility of the display device is not lowered, like the adhesive subject used in each pressure sensitive adhesive layer. For example, known pressure-sensitive adhesives such as acrylic pressure sensitive adhesives, silicone pressure sensitive adhesives, polyester pressure sensitive adhesives, rubber pressure sensitive adhesives and polyurethane pressure sensitive adhesives can be used. In particular, from the viewpoint of durability, (meth) acrylic acid alkyl esters As the main monomer component is preferably used as the acrylic polymer.

Fig. 2 shows a schematic cross-sectional view showing another embodiment of the laminated adhesive sheet 10 of the present invention. As shown in FIG. 2, the laminated adhesive sheet 10 of the present invention has a first pressure-sensitive adhesive layer 1, a second pressure-sensitive adhesive layer 2, and a resin layer 5. In the present invention, the resin layer 5 may be formed between the first pressure sensitive adhesive layer 1 and the second pressure sensitive adhesive layer 2 as shown in Fig. 2 (a). In this case, since the pressure-sensitive adhesive layer is formed on both sides of the resin layer 5, the laminated pressure-sensitive adhesive sheet can function as a double-sided pressure-sensitive adhesive sheet.

2 (b), a first pressure-sensitive adhesive layer 1 is laminated on the resin layer 5, and a second pressure-sensitive adhesive layer (not shown) is formed on the side opposite to the resin layer 5 via the first pressure- 2) may be formed. In this case, since the second pressure-sensitive adhesive layer 2 adheres to an adherend such as an optical member, it is preferable that the second pressure-sensitive adhesive layer 2 contains a resin excellent in adhesiveness to the adherend.

The relative dielectric constant of the resin layer at a frequency of 1 MHz is preferably 2 to 10. By setting the relative dielectric constant of the resin layer at a frequency of 1 MHz within this range, the relative permittivity of the laminated adhesive sheet can be easily adjusted and the relative dielectric constant of the laminated adhesive sheet can be adjusted more precisely. It is also preferable to adjust the relative dielectric constant of the resin layer by appropriately selecting the kind of resin to be used.

The thickness of the resin layer is preferably 10 to 500 mu m, more preferably 25 to 250 mu m. When the thickness of the resin layer is not less than the above lower limit value, the control of the relative dielectric constant of the entire laminated adhesive sheet becomes easy, and if the thickness of the resin layer is not more than the upper limit, the laminated adhesive sheet can be easily produced.

(A laminated adhesive sheet having a release sheet formed thereon)

The laminated adhesive sheet of the present invention can be obtained, for example, by applying a first pressure-sensitive adhesive composition and a second pressure-sensitive adhesive composition on a release sheet to form a coating film and heating the coating film to form a cured product. The release sheet may be a release laminated sheet having a base material for a release sheet and a release agent layer formed on one side of the release sheet or a polyolefin film such as a polyethylene film or a polypropylene film as a low polarity base material.

As the base material for the release sheet in the peelable laminated sheet, papers and polymer films are used. As the releasing agent constituting the releasing agent layer, for example, general-purpose addition-type or condensation-type silicone-based releasing agents and long-chain alkyl group-containing compounds are used.

Specific examples of the silicone release agent include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone Co., and KS-3600, KS-774 and X62-2600 manufactured by Shin-Etsu Chemical Co., have. Further, it is preferable that the silicone based releasing agent contains silicon resin, which is an organosilicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ = CH (CH ₃ ) SiO _1/2 units. Specific examples of the silicone resin include BY24-843, SD-7292 and SHR-1404 manufactured by Toray Dow Corning Silicone Co., and KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Co., .

In order to easily peel off the release sheet, it is preferable that the peelability of the first pressure-sensitive adhesive layer side release sheet and that of the second pressure-sensitive adhesive layer side release sheet are different from each other. That is, if the peelability from one side and the peelability from the other are different, it is easy to peel only the peel sheet having the higher peelability first. In this case, the peelability of the first pressure-sensitive adhesive layer side release sheet and the second pressure-sensitive adhesive layer side release sheet may be adjusted according to the bonding method or the bonding sequence.

The pressure-sensitive adhesive composition for forming each pressure-sensitive adhesive layer can be coated by a known coating apparatus. The pressure-sensitive adhesive composition may be applied to each of the pressure-sensitive adhesive layers, or two or more pressure-sensitive adhesive layers may be formed by simultaneously coating the pressure-sensitive adhesive composition. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater and a curtain coater. Solvent is included in the coating solution. Examples of the solvent include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butyl alcohol, methyl isobutyl ketone, methyl butyl ketone, ethyl butyl ketone, cyclohexanone, , Butyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, N-methyl-2-pyrrolidone and the like. These may be used singly or in combination of two or more kinds.

The heating of the coating film can be carried out by using a known heating apparatus such as a heating furnace or an infrared lamp.

The resin layer can also be formed by using the coating apparatus. When the resin layer is a non-tacky resin layer, it can be molded according to a known method and is not particularly limited, but a biaxial drawing method, a melt extrusion method and the like are preferable.

(Laminate)

In the present invention, a laminate can be manufactured by adhering a laminated adhesive sheet to at least one optical member. When the laminated adhesive sheet is a double-faced adhesive sheet, a pair of optical members can be bonded to both sides of the laminated adhesive sheet.

The optical member constituting the laminate is each constituent member in an optical product such as a touch panel or an image display device. Examples of the constituent members of the touch panel include an ITO film in which an ITO film is formed on a transparent resin film, ITO glass on which an ITO film is formed on the surface of a glass plate, a transparent conductive film in which a conductive polymer is coated on a transparent resin film, Moon Sung Film. Examples of constituent members of the image display device include an antireflection film, an orientation film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device. Examples of the material used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

In addition, the pair of optical members to be bonded by the laminated adhesive sheet of the present invention are not limited to the combination of the ITO films inside the touch panel, the ITO film and the ITO glass, the ITO film of the touch panel and the liquid crystal panel Bonding of the cover glass and the ITO film, bonding of the cover glass and the decorative film, and the like.

Example

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts, ratios, processing contents, processing procedures and the like shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Accordingly, the scope of the present invention should not be construed as being limited by the following specific examples.

(Production of pressure-sensitive adhesive composition (A) contained in the first pressure-sensitive adhesive layer)

80 parts by mass of 2-ethylhexyl acrylate, 17 parts by mass of isobornyl acrylate, and 3 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group as a non-crosslinkable acrylic acid ester unit were polymerized To obtain an acrylic acid ester copolymer solution. The pressure-sensitive adhesive solution containing the acrylic ester copolymer solution as a pressure sensitive adhesive was used as the pressure-sensitive adhesive composition (A).

(38 占 퐉 RL-07 (L), manufactured by Oji Aftex Co., Ltd.) having a release agent layer on a PET film as a release sheet was prepared, and a solution of the above pressure-sensitive adhesive composition (A) Was coated with a knife coater and heated at 100 占 폚 for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 100 占 퐉. The dielectric constant was measured based on JIS-C-2138 by a dielectric constant measuring system (Model 1260 manufactured by Toyotec Corporation) As a result of the detection, the relative dielectric constant (? ₁ ) at a frequency of 1 MHz was 2.6.

(Production of pressure-sensitive adhesive composition (B) contained in the second pressure-sensitive adhesive layer)

40 parts by mass of methyl acrylate as a non-crosslinkable acrylic acid ester unit, 40 parts by mass of butyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate as an acrylic monomer unit having a crosslinkable functional group were subjected to a polymerization reaction according to a known solvent polymerization method, To obtain a coalescent solution. The pressure-sensitive adhesive solution containing the acrylic acid ester copolymer solution as a pressure sensitive adhesive was used as the pressure-sensitive adhesive composition (B).

(38 占 퐉 RL-07 (L), manufactured by Oji Foote K.K.) having a release agent layer on a PET film as a release sheet was prepared, and a solution of the above pressure-sensitive adhesive composition (B) Was coated with a knife coater and heated at 100 占 폚 for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 100 占 퐉. The relative dielectric constant was measured. As a result, the relative dielectric constant? ₂ at a frequency of 1 MHz was 5.4.

(Production of pressure-sensitive adhesive composition (C) contained in the first pressure-sensitive adhesive layer)

80 parts by mass of 2-ethylhexyl acrylate, 17 parts by mass of isobornyl acrylate, and 3 parts by mass of 4-hydroxybutyl acrylate were subjected to polymerization reaction according to a known bulk polymerization method to obtain an acrylic acid ester copolymer. A pressure-sensitive adhesive syrup prepared by adding 30 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isooctyl acrylate and 0.5 part by mass of a photopolymerization initiator as a reactive diluent to 100 parts by mass of the acrylic ester copolymer was used as the pressure-sensitive adhesive composition (C).

A release film (38 占 퐉 RL-07 (L), manufactured by Oji Foote K.K.) having a release agent layer on a PET film was prepared as a release sheet, and the release agent layer of the release sheet was coated with a syrup Was coated by a knife coater and then irradiated with a cumulative light quantity of 1000 mJ / cm &lt; 2 &gt; while cooling with a UV light source in a nitrogen atmosphere to form a pressure-sensitive adhesive layer having a thickness of 100 m. The pressure-sensitive adhesive layer was measured and measured for its dielectric constant based on JIS-C-2138 by a dielectric constant measuring system (Model 1260, manufactured by Toyo Technica), and as a result, the relative dielectric constant (? ₁ ) at a frequency of 1 MHz was 2.4.

(Production of pressure-sensitive adhesive composition (D) contained in the second pressure-sensitive adhesive layer)

40 parts by mass of methyl acrylate as a non-crosslinkable acrylic acid ester unit, 40 parts by mass of butyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate as an acrylic monomer unit having a crosslinkable functional group were subjected to polymerization reaction according to a known bulk polymerization method, I got the merger. A pressure-sensitive adhesive syrup, prepared by adding 50 parts by mass of lauryl acrylate and 0.5 part by mass of a photopolymerization initiator to 100 parts by mass of the acrylic ester copolymer, was used as the pressure-sensitive adhesive composition (D).

A release film (38 占 퐉 RL-07 (L), manufactured by Oji-Fetex Co., Ltd.) having a release agent layer on a PET film was prepared as a release sheet, and the release agent layer of the release sheet was coated with a syrup Was coated by a knife coater and then irradiated with a cumulative light quantity of 1000 mJ / cm &lt; 2 &gt; while cooling with a UV light source in a nitrogen atmosphere to form a pressure-sensitive adhesive layer having a thickness of 100 m. By the pressure-sensitive adhesive layer to the dielectric constant measurement system (Toyo Technica produced 1260-type) on the basis of JIS-C-2138 a result of detection by measuring the relative dielectric constant and relative dielectric constant in the frequency 1MHz (ε ₁₎ was 5.8.

(Example 1) Production of laminated adhesive sheet

In order to produce a laminated adhesive sheet having a dielectric constant of 3.5 using the pressure-sensitive adhesive compositions (A) and (B), the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the equation (1). The ratio of the calculated thickness was "(thickness of the first pressure-sensitive adhesive layer): (thickness of the second pressure-sensitive adhesive layer) = 1: 1", so that the first pressure-sensitive adhesive layer and the second pressure-

As a first peeling sheet, a peeling film (38 μm RL-07 (L), manufactured by Oji Foote K.K.) having a peeling agent layer on a PET film was prepared, and the peeling agent layer of the first peeling sheet was coated with the pressure- (A) was applied by a knife coater and then heated at 100 占 폚 for 3 minutes to form a first pressure-sensitive adhesive layer having a thickness of 50 占 퐉.

As a second peeling sheet, a peeling film (38 μm RL-07 (L), manufactured by Oji Foote K.K.) having a peeling agent layer on a PET film was prepared, and the peeling agent layer of the above- (B) was coated with a knife coater and heated at 100 DEG C for 3 minutes to form a second pressure-sensitive adhesive layer having a thickness of 50 mu m.

The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer were in contact with each other and pressed. Thus, a laminated pressure-sensitive adhesive sheet having a release sheet having a thickness of 100 mu m as the pressure-sensitive adhesive layer was obtained.

(Example 2)

In order to produce a laminated adhesive sheet having a relative dielectric constant of 4.3 using the pressure-sensitive adhesive compositions (A) and (B), the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the formula (1). The thickness ratio of the first pressure-sensitive adhesive layer to the second pressure-sensitive adhesive layer was 25 占 퐉 and the thickness of the second pressure-sensitive adhesive layer was 25 占 퐉 75 mu m, a laminated adhesive sheet in which a release sheet having a thickness of 100 mu m was formed in the same manner as in Example 1 was obtained.

(Example 3)

In order to produce a laminated adhesive sheet having a relative dielectric constant of 3.0 using the pressure-sensitive adhesive compositions (A) and (B), the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the formula (1). (Thickness of the first pressure-sensitive adhesive layer) = 3: 1 &quot;, the thickness of the first pressure-sensitive adhesive layer was set to 75 μm and the thickness of the second pressure-sensitive adhesive layer was set to 25 mu m, a laminated adhesive sheet in which a release sheet having a thickness of 100 mu m was formed in the same manner as in Example 1 was obtained.

(Example 4) Production of laminated adhesive sheet using UV curable pressure sensitive adhesive composition

In order to produce a laminated adhesive sheet having a dielectric constant of 3.5 using the pressure-sensitive adhesive compositions (C) and (D), the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the formula (1). The calculated thickness ratio was "(thickness of the first pressure-sensitive adhesive layer): (thickness of the second pressure-sensitive adhesive layer) = 0.9: 1.1". Thus, the first pressure-sensitive adhesive layer and the second pressure-

As a first peeling sheet, a peeling film (38 μm RL-07 (L), manufactured by Oji Foote K.K.) having a peeling agent layer on a PET film was prepared, and the peeling agent layer of the first peeling sheet was coated with the pressure- (C) was coated with a knife coater and then irradiated with a cumulative light quantity of 1000 mJ / cm &lt; 2 &gt; while cooling with a UV emitter under a nitrogen atmosphere to form a pressure-sensitive adhesive layer having a thickness of 45 m.

As a second peeling sheet, a peeling film (38 μm RL-07 (L), manufactured by Oji Foote K.K.) having a peeling agent layer on a PET film was prepared, and the peeling agent layer of the second peeling sheet was coated with the pressure- (D) was applied by a knife coater and then irradiated with a cumulative light quantity of 1000 mJ / cm &lt; 2 &gt; while cooling with a UV emitter in a nitrogen atmosphere to form a pressure sensitive adhesive layer having a thickness of 55 m.

The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer were in contact with each other and pressed. Thus, a laminated pressure-sensitive adhesive sheet having a release sheet having a thickness of 100 mu m as the pressure-sensitive adhesive layer was obtained.

(Example 5)

In order to produce a laminated adhesive sheet having a relative dielectric constant of 4.4 using the pressure-sensitive adhesive compositions (C) and (D), the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the formula (1). (Thickness of the first pressure-sensitive adhesive layer) = 1: 4 &quot;, the thickness of the first pressure-sensitive adhesive layer was set at 20 占 퐉 and the thickness of the second pressure-sensitive adhesive layer was set at A laminated pressure-sensitive adhesive sheet in which a release sheet having a pressure-sensitive adhesive layer thickness of 100 탆 was formed was obtained in the same manner as in Example 4.

(Example 6)

In order to produce a laminated adhesive sheet having a dielectric constant of 3.0 using the pressure-sensitive adhesive compositions (C) and (D), the ratio of the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer was calculated using the formula (1). (Thickness of the first pressure-sensitive adhesive layer) = 6.5: 3.5 &quot;, the thickness of the first pressure-sensitive adhesive layer was set to 65 占 퐉, and the thickness of the second pressure- A laminated pressure-sensitive adhesive sheet in which a release sheet having a pressure-sensitive adhesive layer thickness of 100 탆 was formed was obtained in the same manner as in Example 4.

(Measurement of relative dielectric constant)

The relative dielectric constant of the laminated adhesive sheet obtained in Examples was measured at a frequency of 1 MHz, and the results are shown in Table 1. Here, the theoretical relative permittivity is a value obtained by equation (1).

In the formula (1),? Represents the relative dielectric constant of the entire laminated pressure sensitive adhesive sheet, and d represents the total thickness of the laminated pressure sensitive adhesive sheet. Also,? _N represents the relative dielectric constant of each pressure-sensitive adhesive layer, and d _n represents the thickness of each pressure-sensitive adhesive layer. Here, n represents the number of layers of the pressure-sensitive adhesive layer.

From the results in Table 1, the relative dielectric constant and actual relative dielectric constant obtained from equation (1) are in good agreement. Thus, by using the calculation formula (1), it is possible to easily produce a laminated adhesive sheet having a desired relative dielectric constant.

Further, a laminated pressure-sensitive adhesive sheet having a third pressure-sensitive adhesive layer was produced.

(Production of pressure-sensitive adhesive composition (1)) [

40 parts by mass of methyl acrylate, 40 parts by mass of butyl acrylate, and 20 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group were polymerized in accordance with a known solvent polymerization method to obtain an acrylic ester To obtain a coalescent solution. The pressure-sensitive adhesive solution containing the acrylic ester copolymer solution as a pressure sensitive adhesive was used as the pressure-sensitive adhesive composition (1).

(Production of pressure-sensitive adhesive composition (2)) [

60 parts by mass of 2-ethylhexyl acrylate, 38 parts by mass of isobornyl acrylate, and 2 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group as a non-crosslinkable acrylic acid ester unit were polymerized To obtain an acrylic acid ester copolymer solution. The pressure-sensitive adhesive solution containing the acrylic ester copolymer solution as a pressure sensitive adhesive was used as the pressure-sensitive adhesive composition (2).

(Production of pressure-sensitive adhesive composition (3)) [

30 parts by mass of methyl acrylate as a non-crosslinkable acrylic acid ester unit, 60 parts by mass of butyl acrylate, and 10 parts by mass of 4-hydroxybutyl acrylate as an acrylic monomer unit having a crosslinkable functional group were subjected to a polymerization reaction according to a known solvent polymerization method, To obtain a coalescent solution. The pressure-sensitive adhesive solution containing the acrylic ester copolymer solution as a pressure sensitive adhesive was used as the pressure-sensitive adhesive composition (3).

(Example 7) Production of laminated adhesive sheet (7) having three pressure sensitive adhesive layers

(1) Production of second pressure-sensitive adhesive layer

As a first release sheet, a release film (38 占 퐉 RL-07 (L), manufactured by Oji-Fetex Co., Ltd.) having a release agent layer on a PET film was prepared, 2) was coated with a knife coater and heated at 100 DEG C for 3 minutes to form a second pressure-sensitive adhesive layer. The relative dielectric constant ( _r ) at the frequency of 100 Hz of the formed second pressure-sensitive adhesive layer was 4.5.

In order to make the relative permittivity of the entire laminated adhesive sheet 7 5.5, the thickness of the first pressure-sensitive adhesive layer, the relative dielectric constant, the thickness of the third pressure-sensitive adhesive layer, As a result of finding the optimum thickness, the second pressure-sensitive adhesive (2) was applied so as to have a thickness of 51 탆.

(2) Production of first pressure-sensitive adhesive layer

As a second release sheet, a release film (38 μm RL-07 (2)) having a release agent layer having a lower release property than that of the above-mentioned first release sheet was prepared on a PET film, The solution of the pressure-sensitive adhesive (1) was coated on the release agent layer of the second release sheet by a knife coater so as to have a thickness of 25 μm, and then heated at 100 ° C. for 3 minutes to form a first pressure-sensitive adhesive layer. The relative dielectric constant ( _r ) at the frequency of 100 Hz of the formed first pressure-sensitive adhesive layer was 7.1.

(3) Production of the third pressure-sensitive adhesive layer

(38 占 퐉 RL-07 (L), manufactured by Oji Aftex Co., Ltd.) as the first release film was prepared as the third release sheet, and the release agent layer of the third release sheet had a thickness of 25 占 퐉 The solution of the pressure-sensitive adhesive (1) was applied by a knife coater and heated at 100 DEG C for 3 minutes to form a third pressure-sensitive adhesive layer. The relative dielectric constant ( _r ) at the frequency of 100 Hz of the formed third pressure-sensitive adhesive layer was 7.1.

(4) Production of laminated adhesive sheet

The second pressure sensitive adhesive layer and the first pressure sensitive adhesive layer are in contact with each other, and then the first release sheet is peeled off to expose the second pressure sensitive adhesive layer. After the second pressure sensitive adhesive layer and the third pressure sensitive adhesive layer are in contact with each other, To obtain a laminated pressure-sensitive adhesive sheet (7) having a release sheet. The thickness and relative dielectric constant of each layer of the laminated adhesive sheet 7 are shown in Table 2.

(Measurement of relative dielectric constant of laminated adhesive sheet)

The relative dielectric constant of the laminated adhesive sheet 7 at a frequency of 100 kHz was measured. As a result, the relative dielectric constant? _R of the obtained laminated adhesive sheet 7 at a frequency of 100 Hz as a whole was 5.4. Table 3 shows the estimated values and the measured values of the relative permittivity of the laminated adhesive sheet 7 at a frequency of 100 Hz.

As shown in Table 3, by forming a pressure-sensitive adhesive layer having a low relative dielectric constant in the second pressure-sensitive adhesive layer and adjusting the thickness thereof, the relative dielectric constant of the entire laminated pressure-sensitive adhesive sheet 7 was able to obtain an actual value close to the presumed value. That is, it can be said that a laminated pressure-sensitive adhesive sheet having a desired relative dielectric constant was obtained.

(Example 8) Production of laminated adhesive sheet (8)

A laminated pressure-sensitive adhesive sheet (8) was prepared in the same manner as in Example 7 except that the pressure-sensitive adhesive (1) was applied to the first pressure-sensitive adhesive layer, the pressure-sensitive adhesive (2) was applied to the second pressure- In order to make the relative permittivity of the laminated pressure-sensitive adhesive sheet 8 to be 5.0, the optimum value of the second pressure-sensitive adhesive layer was determined from the thickness and relative dielectric constant of the first pressure-sensitive adhesive layer, the thickness of the third pressure- , The pressure-sensitive adhesive 2 was coated so as to have a thickness of 100 탆.

(Example 9) Production of laminated adhesive sheet (9)

A laminated adhesive sheet (9) was produced in the same manner as in Example 8 except that the pressure-sensitive adhesive (3) was applied to the first pressure-sensitive adhesive layer, the pressure-sensitive adhesive (1) was applied to the second pressure-sensitive adhesive layer,

(1) is calculated from the thickness of the first pressure-sensitive adhesive layer, the relative dielectric constant, the thickness of the third pressure-sensitive adhesive layer and the relative dielectric constant so that the relative permittivity? _R of the entire laminated pressure-sensitive adhesive sheet 9 is 6.3. 2 pressure-sensitive adhesive layer, the pressure-sensitive adhesive 1 was coated so as to have a thickness of 100 m.

Table 4 shows the thicknesses and relative dielectric constants of the layers of the laminated pressure-sensitive adhesive sheets (8) and (9).

(Measurement of relative dielectric constant of laminated adhesive sheet)

The relative dielectric constant of the laminated adhesive sheets (8) and (9) at a frequency of 100 kHz was measured, and the results are shown in Table 5.

As shown in Table 5, it was possible to freely manufacture the entire relative dielectric constant of the laminated pressure-sensitive adhesive sheet by controlling the relative dielectric constant and thickness of the pressure-sensitive adhesive layer even when the relative dielectric constant of all the pressure-sensitive adhesive layers were different.

According to the present invention, it is possible to provide a method for more accurately controlling the relative dielectric constant in the laminated adhesive sheet. Therefore, in the present invention, a laminated adhesive sheet having a desired relative dielectric constant can be obtained. The laminated adhesive sheet of the present invention is useful for bonding optical members, for example, bonding of ITO films in a touch panel sensor or bonding of a touch panel module and a liquid crystal module.

1 first pressure-sensitive adhesive layer
2 Second pressure sensitive adhesive layer
3 Third pressure-sensitive adhesive layer
5 resin layer
10 Laminated adhesive sheet

Claims (20)

Wherein the absolute value of the difference in relative dielectric constant between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a frequency of 1 MHz is not less than 0.5, characterized in that the pressure- Sheet. The method according to claim 1,
A laminated pressure-sensitive adhesive sheet having at least a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, which has a first pressure-sensitive adhesive layer having a relative dielectric constant of less than 4 at a frequency of 1 MHz and a second pressure-sensitive adhesive layer having a relative dielectric constant of at least 4 at a frequency of 1 MHz Wherein the pressure-sensitive adhesive sheet is a laminated adhesive sheet. 3. The method according to claim 1 or 2,
Wherein the first pressure sensitive adhesive layer has a relative dielectric constant of less than 3 at a frequency of 1 MHz. 4. The method according to any one of claims 1 to 3,
Wherein the thickness of each layer of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 10 占 퐉 or more. 5. The method according to any one of claims 1 to 4,
Wherein the ratio of the thickness of the first pressure-sensitive adhesive layer to the thickness of the second pressure-sensitive adhesive layer is 1: 99 to 99: 1. 6. The method according to any one of claims 1 to 5,
Wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are acrylic pressure-sensitive adhesive layers. 7. The method according to any one of claims 1 to 6,
Wherein the first pressure sensitive adhesive layer and the second pressure sensitive adhesive layer comprise a (meth) acrylic acid ester. 8. The method according to any one of claims 1 to 7,
And a third pressure-sensitive adhesive layer. 9. The method according to any one of claims 1 to 8,
And further has a resin layer. 10. The method of claim 9,
Wherein the resin layer is formed between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. 10. The method of claim 9,
Wherein the first pressure sensitive adhesive layer is laminated on the resin layer and the second pressure sensitive adhesive layer is laminated on the opposite side of the resin layer via the first pressure sensitive adhesive layer. 12. The method according to any one of claims 9 to 11,
Wherein the resin layer has a relative dielectric constant of 2 to 10 at a frequency of 1 MHz. A laminate characterized in that the laminated adhesive sheet of any one of claims 1 to 12 is adhered to at least one optical member. 14. The method of claim 13,
Wherein at least one of the optical members is an ITO glass or an ITO film. As a method of adjusting the relative dielectric constant of a laminated adhesive sheet having at least two pressure-sensitive adhesive layers,
Wherein said laminated adhesive sheet has a first pressure-sensitive adhesive layer having a relative dielectric constant of less than 4 at a frequency of 1 MHz and a second pressure-sensitive adhesive layer having a relative dielectric constant of 4 or more at a frequency of 1 MHz,
Wherein the dielectric constant and the thickness of the first pressure sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant and thickness at the frequency of 1 MHz of the second pressure sensitive adhesive layer are respectively adjusted to adjust the relative dielectric constant of the laminated pressure sensitive adhesive sheet Throne adjustment method. 16. The method of claim 15,
Wherein the relative dielectric constant and thickness of the first pressure-sensitive adhesive layer at a frequency of 1 MHz and the relative dielectric constant and thickness of the second pressure-sensitive adhesive layer at a frequency of 1 MHz are adjusted using the following equation (1) Way:
[Equation 1]

(Formula (1) of the, ε denotes a relative dielectric constant of a multilayer pressure-sensitive adhesive sheet, d represents the whole laminated adhesive sheet thickness; also, ε _n denotes the relative dielectric constant of each of the pressure-sensitive adhesive layer, d _n are each a pressure-sensitive adhesive layer , Where n represents the number of layers of the pressure-sensitive adhesive layer). 17. The method of claim 16,
Wherein d _{1 to} d _n are determined to be a specific? Under the condition that? _{1 to} ? _N are fixed in the above formula (1). 17. The method of claim 16,
Wherein? _{1 to} ? _N-1 and d _{1 to} d _n-1 are determined under the condition that? _N and d _n are fixed in the above formula (1). 19. The method according to any one of claims 16 to 18,
Wherein in the formula (1), n is 2. A process for producing a laminated adhesive sheet having at least two pressure-sensitive adhesive layers, characterized in that the relative dielectric constant of the laminated pressure-sensitive adhesive sheet is adjusted according to the relative dielectric constant adjusting method of any one of claims 16 to 19 Gt;

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