TWI649395B - Double-sided adhesive sheet - Google Patents

Abstract

The invention provides a double-sided adhesive sheet. The double-sided adhesive sheet (1) of the present invention includes an adhesive layer disposed between two patterned transparent conductive films, or between the patterned transparent conductive film and a cover material or a display body module ( 2), wherein the adhesive layer (2) is composed of an adhesive, the aforementioned adhesive is composed of an adhesive composition containing an adhesive component and light diffusing fine particles, and the haze value of the adhesive layer (2) is 2 to 40%. According to the adhesive layer (2) of the double-sided adhesive sheet (1), it is difficult to observe the circuit pattern of the transparent conductive film in a capacitive touch panel or the like.

Description

Double-sided adhesive sheet

The present invention relates to a double-sided adhesive sheet that can be used in a touch panel and the like.

In recent years, in various mobile electronic devices such as smart phones and tablet computers, the use of a capacitive touch panel as a display has been increasing.

There are a plurality of structures in a touch panel of an electrostatic capacitance type. As a typical example, the following structures can be exemplified, that is, a display body module such as a liquid crystal module, and a first thin film sensor through an adhesive layer. Laminated on the display body module; a second thin film sensor, which is laminated on the first thin film sensor via an adhesive; and a cover material, which is laminated on the second thin film sensor via an adhesive.

Generally, the above-mentioned thin film sensor is composed of a base film and a transparent conductive film composed of a patterned tin-doped indium oxide (ITO). In a touch panel having a patterned transparent conductive film, there is a so-called pattern visualization problem that affects the appearance due to the circuit pattern of the transparent conductive film being seen.

In order to solve the problem that the above pattern is visible, in Patent Document 1, an undercoat layer is formed between the thin film substrate and the transparent conductor layer, and the difference between the refractive index of the transparent conductor layer and the refractive index of the undercoat layer is used to change the thickness of the transparent conductor layer. Pattern department The reflectance difference between the non-patterned portion and the non-patterned portion is suppressed to be small, and an attempt is made to suppress the visibility of the pattern.

Further, in Patent Document 2, an easy-adhesion layer and an optical adjustment layer having a predetermined content, refractive index, and thickness of a polyester resin are laminated between a polyester film and a transparent conductor layer, and optical interference caused by the easy-adhesion layer is suppressed. Effect, trying to use this to suppress the pattern visible.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-142089

[Patent Document 2] Japanese Patent Application Publication No. 2013-184431

However, in the invention described in Patent Document 1, it is difficult to control the film thickness of the undercoat layer as described above, and it is difficult to obtain a sufficient effect of suppressing the visibility of the pattern. In addition, there is a problem that the cost is increased by the installation of the undercoat layer. On the other hand, in the invention described in Patent Document 2, it is difficult to control the refractive index and the film thickness of the easy-adhesion layer, and it is difficult to obtain a sufficient pattern visibility suppression effect.

The present invention has been made in view of the above-mentioned actual situation, and an object thereof is to provide a double-sided adhesive sheet in which a circuit pattern of a transparent conductive film is difficult to observe through an adhesive layer in a touch panel of an electrostatic capacitance method or the like.

In order to achieve the above object, the first and the present invention provide a double-sided adhesive sheet, which includes a double-sided adhesive sheet disposed between two patterned transparent conductive films, or The adhesive layer between the patterned transparent conductive film and the cover material or the display module, wherein the adhesive layer is composed of an adhesive, and the adhesive is composed of an adhesive composition containing an adhesive component and light diffusing fine particles, and The haze value of the adhesive layer is 2 to 40% (Invention 1).

When the adhesive layer of the double-sided adhesive sheet of the above invention (Invention 1) is disposed between two patterned transparent conductive films or between the patterned transparent conductive film and a cover material or a display module, When the haze value of the adhesive layer is within the above range, a high light transmittance can be maintained, and it is difficult to observe a circuit pattern of the transparent conductive film.

In the above invention (Invention 1), it is preferable that the average particle diameter of the light diffusion fine particles by the centrifugal sedimentation light transmission method is 0.1 to 20 μm (Invention 2).

In the above inventions (Inventions 1, 2), the adhesive component preferably contains a (meth) acrylate polymer (Invention 3).

In the above invention (Invention 3), the (meth) acrylate polymer is preferably crosslinked by a crosslinking agent (Invention 4).

In the above inventions (Inventions 3 and 4), the content of the light diffusing fine particles is preferably 0.01 to 15 parts by mass relative to 100 parts by mass of the (meth) acrylate polymer (Invention 5).

Moreover, the present invention provides a laminated body including the aforementioned double-sided adhesive sheet between two patterned transparent conductive films, or between the patterned transparent conductive film and a cover material or a display module (Invention 1 ~ 5) Adhesive layer. In the laminated body, the adhesive layer may be in direct contact with the transparent conductive film, cover material or display module, or may not be in contact.

The adhesive layer of the double-sided adhesive sheet according to the present invention can maintain high light transmittance in a capacitive touch panel or the like, and it is difficult to observe the circuit pattern of the transparent conductive film.

1‧‧‧ double-sided adhesive sheet

2‧‧‧ Adhesive layer

3a, 3b ‧‧‧ peeling sheet

4‧‧‧Display Module

5a‧‧‧1st thin film sensor

5b‧‧‧ 2nd thin film sensor

51‧‧‧ substrate film

52‧‧‧Transparent conductive film

6‧‧‧ Covering material

7‧‧‧print layer

10‧‧‧ touch panel

FIG. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of the configuration of a touch panel.

Hereinafter, embodiments of the present invention will be described.

The double-sided adhesive sheet of this embodiment includes an adhesive layer disposed between two patterned transparent conductive films or between the patterned transparent conductive film and a cover material or a display body module.

As shown in FIG. 1, the double-sided adhesive sheet 1 of this embodiment is composed of two release sheets 3a, 3b, and is contacted by the release sheets 3a, 3b of the two release sheets 3a, 3b, 3b is composed of an adhesive layer 2. However, in the double-sided adhesive sheet 1, the release sheets 3 a and 3 b are not an essential constituent element, and are those that are peeled off and removed when the double-sided adhesive sheet 1 is used. In addition, the release surface of the release sheet in the present specification refers to a surface having releasability in the release sheet, and includes any one of a surface subjected to a release treatment and a surface that exhibits releasability even without a release treatment.

Adhesive layer

The adhesive layer 2 in this embodiment is composed of an adhesive and has a haze value of 2 to 40%. The aforementioned adhesive is composed of an adhesive composition (hereinafter sometimes referred to as "adhesiveness") containing an adhesive component and light-diffusing fine particles. Composition P ") is formed. This embodiment In the adhesive layer 2 in the state, the haze value is controlled as described above by using light-diffusing fine particles, thereby maintaining high light permeability in a capacitive touch panel and the like, and making it difficult to observe the circuit pattern of the transparent conductive film. , So as to exert excellent pattern visual effect.

If the haze value is less than 2%, the effect of visually suppressing the pattern cannot be obtained, and the circuit pattern of the transparent conductive film can be observed. In addition, if the haze value exceeds 40%, the effect of suppressing pattern visibility cannot be obtained. From this point of view, the haze value of the adhesive layer 2 is preferably 3 to 30%, and particularly preferably 6 to 20%. In addition, the haze value in the specification of the present application is a value measured in accordance with JIS K7136: 2000.

(1) Adhesive ingredients

The adhesive component is not particularly limited as long as it exhibits a desired adhesive force in a capacitive touch panel or the like, has light transmittance, and does not hinder the effect of the light-diffusing fine particles described above. Examples of such adhesive components include acrylic adhesive components, rubber-based adhesive components, silicone-based adhesive components, polyurethane-based adhesive components, and polyester-based adhesive components. However, from the above viewpoints, acrylic adhesive components Is better.

As the acrylic adhesive component, a (meth) acrylate polymer (A) is preferred, and a (meth) acrylate polymer (A) crosslinked by a crosslinking agent (B) is particularly preferred. In addition, in this specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. Other similar terms are the same. In addition, in this specification, the "polymer" also includes the concept of "copolymer."

(1-1) (meth) acrylate polymer (A)

In the (meth) acrylate polymer (A), as a monomer constituting the polymer, an alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group is more preferable. good. Thereby, the obtained adhesive can exhibit better adhesion. In addition, the (meth) acrylic polymer (A) -based alkyl (meth) acrylic acid alkyl having 1 to 20 carbon atoms, and a monomer (including a functional group that reacts with a crosslinking agent (B) (including Copolymers of a reactive functional monomer) and other monomers used as required are particularly preferred. In addition, a hard monomer described later is removed from the alkyl (meth) acrylate.

Examples of the alkyl (meth) acrylate having 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (methyl) N-butyl acrylate, n-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylic acid N-decyl ester, n-dodecyl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, octadecyl (meth) acrylate, and the like. Among them, from the viewpoint of further improving the adhesion, (meth) acrylates having 1 to 8 carbon atoms in the alkyl group are preferred, methyl acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid 2 -Ethylhexyl ester is particularly preferred. These substances may be used alone or in combination of two or more.

In the (meth) acrylic acid ester polymer (A), as a monomer unit constituting the polymer, 30 to 90% by mass of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is It is particularly preferable to contain 40 to 75 mass%, and it is more preferable to contain 50 to 65 mass%.

Preferred examples of the reactive functional group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl-containing monomer), and having a molecule in the molecule. Amino monomers (amino-containing monomers) and the like.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid. 2-hydroxybutyl (hydroxy) (meth) acrylate and the like, such as 2-hydroxybutyl, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among them, (meth) acrylic acid 2- (meth) acrylic acid ester polymer (A) is considered in terms of its reactivity with a hydroxyl group and a crosslinking agent (B) and copolymerizability with other monomers. Hydroxyethyl esters are preferred. These substances may be used alone or in combination of two or more.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoints of the reactivity of the carboxyl group in the obtained (meth) acrylate polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers. These can be used alone or in combination of two or more.

Examples of the amino-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These can be used alone or in combination of two or more.

When the (meth) acrylic acid ester polymer (A) contains a hydroxyl-containing monomer as a reactive functional group-containing monomer constituting the polymer, the content is 15 to 30 from the viewpoint of step-followability under durable conditions. The mass% is more preferable, and 17 to 28 mass% is particularly preferable. In addition to the above-mentioned viewpoints, 20 to 25 mass% is more preferable from the viewpoint that the moist-heat whitening resistance is also optimized.

When the (meth) acrylate polymer (A) contains a carboxyl group-containing monomer as a reactive functional group-containing monomer constituting the polymer, the content is 5 to 25 from the viewpoint of step-followability under durable conditions. Mass% is better, 7 ~ 20 Mass% is particularly preferred. In addition to the above viewpoints, 10 to 15 mass% is more preferable from the viewpoint that the moist-heat whitening resistance is also optimized.

Here, if a touch panel or the like is placed in a high-temperature and high-humidity environment, moisture is immersed in the adhesive layer. When the touch panel or the like returns to normal temperature, the adhesive layer has whitened and the transparency is reduced. "The problem. When the (meth) acrylate polymer (A) contains the reactive functional group-containing monomer in the above range, a predetermined amount of the reactive functional group remains in the adhesive layer. The reactive functional group is usually a hydrophilic group. If a certain amount of such a hydrophilic group exists in the adhesive layer, even when the adhesive layer is placed under high temperature and high humidity conditions, Under high humidity conditions-the compatibility of the water immersed in the adhesive layer is also good. As a result, the whitening of the adhesive layer is suppressed, and the adhesive layer 2 is excellent in moisture and heat whitening resistance.

In the (meth) acrylic acid ester polymer (A), as the monomer unit constituting the polymer, an acrylate-based hard monomer is preferable. Here, the hard monomer system refers to a homopolymer obtained by polymerizing only the hard monomer, and has a glass transition temperature (Tg) of 70 ° C or higher, preferably 75 to 200 ° C, and particularly preferably 80 to 180 ° C. monomer. By containing the above-mentioned hard monomer as a monomer unit constituting the (meth) acrylate polymer (A), the obtained adhesive becomes excellent in durability and foam resistance. Therefore, even in a case where the adherend is a plastic plate and air leakage occurs from the plastic plate, it is possible to suppress expansion such as generation of bubbles, warping, and peeling.

Examples of the hard monomer include methyl methacrylate (Tg 105 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C), and propylene morpholine (Tg 145 ° C). , Adamantane acrylate (Tg115 ℃), Adamantane methacrylate (Tg141 ℃), Dimethylpropane Methanamine (Tg 89 ° C), acrylamide (Tg 165 ° C), and the like. These substances may be used alone or in combination of two or more.

Among the above-mentioned hard monomers, methyl methacrylate, isobornyl acrylate, and acryl morpholine are more effective from the viewpoint of further exerting the performance of the hard monomer while preventing adverse effects on other properties such as adhesion and transparency. Good, especially methyl methacrylate.

In the (meth) acrylate polymer (A), as a monomer unit constituting the polymer, the hard monomer is preferably contained in an amount of 10 to 45% by mass, and particularly preferably contained in an amount of 15 to 30% by mass. By containing the above-mentioned hard monomer in an amount of 10% by mass or more, the effect of improving the durability or anti-foaming properties based on the monomer unit can be expected. On the other hand, by containing the above-mentioned hard monomer at a content of 45% by mass or less, the relative shortage of other monomer units in the (meth) acrylate polymer (A) is prevented, and the adhesiveness of the adhesive that can be obtained , Good step-following and moist heat whitening resistance.

In the (meth) acrylate polymer (A), it is preferable that the monomer units constituting the polymer contain a hydroxyl-containing monomer and the above-mentioned hard monomer in the aforementioned ranges, respectively. As a result, the obtained adhesive becomes more excellent in foam resistance.

The (meth) acrylate polymer (A) may contain other monomer as a monomer unit which comprises this polymer as needed. As the other monomer, a monomer having no reactive functional group is preferred so as not to impair the effect of the hydroxyl-containing monomer. Examples of the other monomers include alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and cyclohexyl (meth) acrylate. (Meth) acrylic acid esters having an aliphatic ring, such as (meth) acrylic acid-N, N-dimethylaminoethyl ester, (meth) acrylic acid (Meth) acrylates having non-crosslinkable tertiary amino groups such as enoic acid-N, N-dimethylaminopropyl, vinyl acetate, styrene, and the like. These substances may be used alone or in combination of two or more.

The polymerization state of the (meth) acrylate polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylate polymer (A) is preferably 100,000 to 1.5 million, more preferably 200,000 to 1.3 million, and even more preferably 300,000 to 800,000. In addition, the weight average molecular weight in this specification is a polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

In addition, in the adhesive composition P, a (meth) acrylate polymer (A) may be used individually by 1 type, and may use 2 or more types together.

When the (meth) acrylate polymer (A) is contained in the adhesive composition P as an adhesive component, and the (meth) acrylate polymer (A) has the aforementioned predetermined composition and molecular weight, the obtained adhesive layer The step difference followability of 2 is also excellent. Therefore, even if this adhesive layer 2 is attached to a covering material having a step difference caused by a printing layer or the like, it is difficult to form a void or a bubble between the step difference and the adhesive layer. In addition, even when the laminated body is placed at a high temperature such as 80 ° C., bubbles and the like can be prevented from being generated near the step.

(1-2) Crosslinking agent (B)

When the adhesive component of the adhesive composition P contains a (meth) acrylate polymer (A) and a crosslinking agent (B) containing a reactive functional group-containing monomer as a monomer unit constituting the polymer, When this adhesive composition P is heated or the like, the crosslinking agent (B) reacts with the reactive functional group of the reactive functional group-containing monomer constituting the (meth) acrylate polymer (A). Thereby, (methyl) is formed The structure in which the acrylate polymer (A) is crosslinked by the cross-linking agent (B) improves the strength and durability of the adhesive layer 2.

The cross-linking agent (B) may be any one that reacts with a reactive functional group of the (meth) acrylate polymer (A). Examples thereof include an isocyanate-based cross-linking agent and an epoxy-based cross-linking agent. , Amine-based crosslinker, melamine-based crosslinker, aziridine-based crosslinker, hydrazine-based crosslinker, aldehyde-based crosslinker, oxazoline-based crosslinker, metal alkoxide-based crosslinker, metal Chelating crosslinking agents, metal salt crosslinking agents, ammonium salt crosslinking agents, and the like. Among the above, when the reactive functional group of the (meth) acrylate polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. When (meth) When the reactive functional group of the acrylate polymer (A) is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group. The crosslinking agent (B) may be used alone or in combination of two or more thereof.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; and isophorone diisocyanate. Alicyclic polyisocyanates, such as hydrogenated diphenylmethane diisocyanate, etc., and biuret bodies, isocyanurate bodies of the substances, and ethylene glycol, propylene glycol, neopentyl glycol, and trimethylol The reactants of low-molecular active hydrogen-containing compounds such as propane and castor oil are adducts. Among them, trimethylolpropane-modified aromatic polyisocyanates are preferred from the viewpoint of reactivity with hydroxyl groups, and trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified xylene xylene are preferred. Isocyanates are particularly preferred.

Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl- M-xylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, and the like.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.001 to 10 parts by mass relative to 100 parts by mass of the (meth) acrylate polymer (A), particularly preferably 0.01 to 5 parts by mass, 0.02 to 1 part by mass is more preferable.

(2) Light-diffusing fine particles

The light-diffusing fine particles may be those that can make the haze value of the adhesive layer 2 within the above range, and examples thereof include silicon dioxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide. Inorganic fine particles; organic light-transmitting fine particles such as acrylic resins, polystyrene resins, polyethylene resins, and epoxy resins; silicon resins, such as silicone resins, are composed of silicon-containing compounds with an intermediate structure between inorganic and organic Fine particles (for example, TOSPEARL series manufactured by Japan Momentive Performance Materials Inc.) and the like. Among them, acrylic resin fine particles and fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic are excellent in dispersibility with respect to the above-mentioned adhesive components and can obtain uniform optical characteristics, and are therefore preferable. These light-diffusing fine particles may be used singly or in combination of two or more kinds.

As the shape of the light-diffusing fine particles, spherical fine particles with uniform light diffusion are preferred. The average particle diameter of the light-diffusing fine particles based on the centrifugal sedimentation light transmission method is preferably 0.1 to 20 μm, and more preferably 1 to 10 μm. In particular, when the light-diffusing fine particles are fine particles composed of a silicon-containing compound, the centrifugal sedimentation light transmission method is used. The average particle diameter is preferably 1 to 10 μm. When the average particle diameter is in the above range, the haze value can be made in the above range without hindering the light transmittance of the adhesive layer 2.

In addition, the average particle diameter based on the above-mentioned centrifugal sedimentation light transmission method is a sample with sufficient stirring of 1.2 g of fine particles and 98.8 g of isopropanol as a measurement sample, and a centrifugal automatic particle size distribution measurement device (produced by HORIBA, Ltd., CAPA-700 ) Tester.

When the (meth) acrylate polymer (A) is contained in the adhesive composition P as an adhesive component, the content of the light-diffusing fine particles is 0.01 to 15 masses relative to 100 parts by mass of the (meth) acrylate polymer (A). Parts are more preferred, and 0.1 to 4 parts by mass are more preferred. In addition, when it is a light-diffusing fine particle composed of a silicon-containing compound having an intermediate structure between organic and inorganic, such as a silicone resin, 0.2 to 1.5 parts by mass is particularly preferred, and 0.2 to 0.9 parts by mass is most preferred. In the case of organic light-transmitting fine particles, 0.3 to 3 parts by mass is the best. When the content of the light-diffusing fine particles is within the above-mentioned range, the haze value of the adhesive layer 2 can be within the above-mentioned range, and an excellent pattern visibility suppressing effect can be obtained. When the adhesive component is a component other than the acrylic adhesive component, the content of the light-diffusing fine particles is preferably within the above range with respect to 100 parts by mass of the adhesive component.

(3) Various additives

The adhesive composition P (adhesive constituting the adhesive layer 2) may contain various additives, such as a silane coupling agent, a refractive index adjuster, an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, and a light stabilizer, as required. , Softeners, fillers, etc.

From the viewpoint of improving the adhesion of the obtained adhesive, the adhesive It is preferable that the silane coupling agent is contained in the adhesive composition P. As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule and having good compatibility with an adhesive component and having light transmittance are preferred.

Examples of such a silane coupling agent include a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacrylidine, and 3-glycidyletherpropyltrimethoxy Silicon compounds with epoxy structures such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, Mercapto-containing silicon compounds such as 3-mercaptopropyldimethoxymethylsilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane and other amino-containing silicon compounds, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or these At least one kind of condensate with an alkyl silicon-containing compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, and the like. These substances may be used singly or in combination of two or more kinds.

When the (meth) acrylate polymer (A) is contained as an adhesive component in the adhesive composition P, the content of the silane coupling agent is 0.01 to 10 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A). Parts is more preferred, 0.05 to 5 parts by mass is particularly preferred, and 0.1 to 1 parts by mass is further preferred. In addition, when the adhesive component is a component other than the acrylic adhesive component, the content of the silane coupling agent is preferably within the above range with respect to 100 parts by mass of the adhesive component.

(4) Manufacturing method of adhesive composition

The adhesive composition P can be produced by mixing an adhesive component, light-diffusing fine particles, and additives added as needed. When (meth) c In the case of the acrylate polymer (A), a (meth) acrylate polymer (A) is first prepared, and a cross-linking agent (B) is blended as necessary.

A (meth) acrylate polymer (A) can be manufactured by polymerizing the mixture of the monomer unit which comprises a polymer by a normal radical polymerization method. If necessary, the polymerization of the (meth) acrylate polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, n-isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more of them may be used in combination. Examples of the azo-based compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexane- 1-carboxonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile) ), 2,2'-azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethyl) Propionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] and the like.

Examples of the organic peroxide include benzamidine peroxide, tert-butyl perbenzoate, cumene hydrogen peroxide, diisopropylperoxydicarbonate, and di-N-propylperoxydioxide. Carbonate, bis (2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexyl) ) Peroxide, dipropylammonium peroxide, diethylammonium peroxide, and the like.

In addition, in the above polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-mercaptoethanol.

After the (meth) acrylate polymer (A) is obtained, light-diffusing fine particles are added to the solution of the (meth) acrylate polymer (A), It is necessary to add the cross-linking agent (B) and additives and mix them sufficiently to obtain an adhesive composition P (coating solution) diluted with a solvent.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; chlorinated hydrocarbons such as dichloromethane and dichloroethane; and methanol and ethanol. , Alcohols such as propanol, butanol, 1-methoxy-2-propanol, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, butyl acetate Ester such as ester, cellosolvent solvent such as ethyl cellosolve, etc.

The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within the applicable range, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may become 10-40 mass%. In addition, when a coating solution is obtained, the addition of a diluent solvent or the like is not necessary, and if the adhesive composition P has a coatable viscosity or the like, the diluent solvent may not be added.

(5) the formation of adhesive

The adhesive in this embodiment is formed of an adhesive composition P. The formation of the adhesive can usually be performed by heat-treating the adhesive composition P. The heat treatment may be combined with a drying treatment in which a diluent solvent or the like of the adhesive composition P is volatilized.

When the (meth) acrylate polymer (A) is contained in the adhesive composition P, the heating temperature of the heat treatment is preferably 50 to 150 ° C, and particularly preferably 70 to 120 ° C. The heating time is preferably 30 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes. After the heat treatment, a health period of about 1 to 2 weeks at normal temperature (for example, 23 ° C., 50% RH) can be set as necessary. When needed During the health period, an adhesive is formed after the health period has elapsed, and when the health period is not required, the adhesive is formed after the heat treatment is completed.

(6) Thickness of the adhesive layer

The thickness of the adhesive layer 2 (value measured in accordance with JIS K7130) is preferably 5 to 600 μm, more preferably 20 to 300 μm, and even more preferably 50 to 150 μm. When the thickness of the adhesive layer 2 is 5 μm or more, good adhesiveness is exhibited. In addition, when attached to an adherend having a step difference, the step followability is exhibited. On the other hand, when the thickness of the adhesive layer 2 is 600 μm or less, the workability is improved. The adhesive layer 2 may be formed of a single layer or a plurality of layers.

2. Release sheet

The release sheets 3a and 3b are not particularly limited. For example, polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, and vinyl chloride copolymers can be used. Material film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / ( (Meth) acrylic copolymer film, ethylene / (meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. In addition, a crosslinked film of these materials may be used. A laminated film of these materials may be used.

The release surfaces of the release sheets 3a and 3b (especially with the adhesive layer 2) The contact surface) is preferably subjected to a peeling treatment. Examples of the release agent used for the release treatment include release agents such as alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. In the release sheets 3a and 3b, one of the release sheets is a heavy release-type release sheet having a large peeling force, and the other release sheet is provided. It is preferable that it is a light peeling type peeling sheet with small peeling force.

The thickness of the release sheets 3a and 3b is not particularly limited, but is usually about 20 to 150 μm.

3. Manufacturing of double-sided adhesive sheet

As a manufacturing example of the double-sided adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the release surface of one release sheet 3a (or 3b), and heat treatment is performed to form a coating layer. A peeling surface of another peeling sheet 3b (or 3a) is superimposed on the coating layer. When a curing period is required, the coating layer becomes the adhesive layer 2 by setting a curing period. When a curing period is not required, the coating layer directly becomes the adhesive layer 2. Thereby, the above-mentioned double-sided adhesive sheet 1 is obtained. The conditions for heat treatment and health are as described above.

As another manufacturing example of the double-sided adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is coated on the peeling surface of one peeling sheet 3a, and heat treatment is performed to form a coating layer to obtain peeling with a coating layer. Sheet 3a. Then, the coating liquid of the adhesive composition P is applied to the release surface of the other release sheet 3b, and a heat treatment is performed to form a coating layer to obtain a release sheet 3b with a coating layer. Then, the tape-coated layer release sheet 3 a and the tape-coated layer release sheet 3 b are bonded so that the two coating layers are in contact with each other. When the curing period is required, the coating layer of the above-mentioned layer becomes the adhesive layer 2 by setting the curing period. When the curing period is not required, the coating layer of the above-mentioned layer directly becomes the adhesive layer 2. Thereby, the above-mentioned double-sided adhesive sheet 1 is obtained. According to this manufacturing example, even when the adhesive layer 2 is thick, it can be stably manufactured.

As a method of applying the coating liquid of the above-mentioned adhesive composition P, for example, a bar coating method, a blade coating method, a roll coating method, a blade coating method can be used, Die coating method, gravure coating method, and the like.

4. Use of double-sided adhesive sheet

The double-sided adhesive sheet 1 of this embodiment can be used for a laminated body having a circuit pattern of a transparent conductive film, and is particularly preferably used for a touch panel of an electrostatic capacitance method. When the double-sided adhesive sheet 1 is used for a capacitive touch panel, the adhesive layer 2 may exist in any position as long as it is tied between the display module and the cover material of the touch panel, for example, it can be located in two transparent conductive Between the films, between the transparent conductive film and the cover material, and between the transparent conductive film and the display module. Regardless of the presence of the adhesive layer 2 in any of these locations, it is difficult to observe the circuit pattern of the transparent conductive film due to the excellent pattern visible suppression effect of the adhesive layer 2.

By using the double-sided adhesive sheet 1 of this embodiment, for example, a touch panel 10 of the electrostatic capacitance type shown in FIG. 2 can be manufactured. The touch panel 10 includes a display body module 4, a first thin-film sensor 5a laminated on the adhesive layer 2 thereon, a second thin-film sensor 5b laminated on the adhesive layer 2 thereon, and A cover material 6 laminated thereon via an adhesive layer 2.

The three adhesive layers 2 in the touch panel 10 are the adhesive layers 2 of the double-sided adhesive sheet 1, but are not limited thereto, as long as at least one adhesive layer 2 is the adhesive of the double-sided adhesive sheet 1. Layer 2 is sufficient. When one or both of the adhesive layers 2 in the touch panel 10 are the adhesive layers 2 of the double-sided adhesive sheet 1 described above, the other adhesive layers are composed of a desired adhesive. As a desired adhesive agent, the light-diffusion fine particle which does not contain the adhesive agent which comprises the adhesive agent layer 2 mentioned above can be illustrated.

Examples of the display module 4 include a liquid crystal (LCD). Modules, light emitting diode (LED) modules, organic electroluminescence (organic EL) modules, electronic paper, etc.

The first thin-film sensor 5a and the second thin-film sensor 5b are generally composed of a base film 51 and a patterned transparent conductive film 52, respectively. The base film 51 is not particularly limited. For example, a polyethylene terephthalate film, a polycarbonate film, a polymethyl methacrylate film, a polycycloolefin film, a polyolefin film, or a cellulose triacetate film can be used. .

Examples of the transparent conductive film 52 include metals such as platinum, gold, silver, and copper; oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc dioxide; and tin-doped indium oxide (ITO) and zinc oxide Doped indium oxide, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and other complex oxides, chalcogenides, lanthanum hexaboride, titanium nitride, titanium carbide and other non-oxides Among the oxide compounds, tin-doped indium oxide (ITO) is preferred.

Generally, one of the transparent conductive film 52 of the first thin-film sensor 5a and the second conductive film 52 of the second thin-film sensor 5b constitutes a circuit pattern in the X-axis direction, and the other constitutes a circuit pattern in the Y-axis direction.

In FIG. 2, the transparent conductive film 52 of the first thin-film sensor 5 a of this embodiment is located on the upper side (the cover material 6 side) of the first thin-film sensor 5 a, but it is not limited to this, and may be located on the first side. The lower side of the thin film sensor 5a (showing the module 4 side). In addition, in FIG. 2, the transparent conductive film 52 of the second thin-film sensor 5 b is located below the second thin-film sensor 5 b (showing the module 4 side), but it is not limited to this, and may be located at the second The upper side of the thin film sensor 5b (the cover material 6 side).

The cover material 6 is usually a glass plate or a plastic plate as a main body. As The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass acid, lead glass, borosilicate glass, and barium borosilicate Salt glass, etc. The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate made of polymethyl methacrylate and the like.

In addition, one or both sides of the glass plate or plastic plate may be provided with functional layers such as a hard coat layer, an anti-reflection layer, and an anti-glare layer, and optical components such as a hard-coat film, an anti-reflection film, and an anti-glare film may also be laminated.

In the present embodiment, the surface of the covering material 6 on the side of the adhesive layer 2 has a step, and specifically has a step formed by the presence or absence of the printing layer 7. The printing layer 7 is generally formed in a frame shape on the side of the adhesive layer 2 in the cover material 6.

The material constituting the printing layer 7 is not particularly limited, and a known material for printing can be used. The thickness of the printing layer 7, that is, the step height is preferably 3 to 45 μm, more preferably 5 to 35 μm, particularly preferably 7 to 25 μm, and 7 to 15 μm is more preferable.

In addition, the thickness (height of the step) of the printing layer 7 is preferably 50% or less of the thickness of the adhesive layer 2, more preferably 5 to 40%, and even more preferably 10 to 30%. When the thickness of the adhesive layer 2 and the thickness of the printing layer 7 satisfy the above-mentioned relationship, the adhesive layer 2 well follows the step difference generated by the printing layer 7 and suppresses the occurrence of warping, bubbles, and the like near the step difference.

An example of a method of manufacturing the touch panel 10 will be described below.

As the double-sided adhesive sheet 1, first, second, and third double-sided adhesive sheets 1 were prepared. First, one peeling sheet 3a (or 3b) is peeled from the first double-sided adhesive sheet 1, and The exposed adhesive layer 2 is adhered to the thin film sensor 5a in a manner of being in contact with the patterned transparent conductive film 52 of the thin film sensor 5a. Next, the other release sheet 3b (or 3a) is peeled from the first double-sided adhesive sheet 1, and the exposed adhesive layer 2 is brought into contact with the thin-film sensor 5b with the patterned transparent conductive film 52 The sensor 5b is attached. Thereby, a laminated body in which the thin film sensor 5a, the adhesive layer 2 and the thin film sensor 5b are laminated in this order is obtained.

Next, one peeling sheet 3a (or 3b) is peeled from the second double-sided adhesive sheet 1, and the exposed adhesive layer 2 is attached to the surface of the film sensor 5a side of the laminated body (the base of the film sensor 5a). Material film 51). Then, one release sheet 3a (or 3b) is peeled from the third double-sided adhesive sheet 1, and the exposed adhesive layer 2 is bonded to the surface of the laminated body on the side opposite to one side of the laminated adhesive layer 2 ( (The exposed surface of the base film 51 of the thin film sensor 5b).

Thereafter, the other release sheet 3b (or 3a) is peeled from the third double-sided adhesive sheet 1, and the exposed adhesive layer 2 is bonded to the adhesive layer 2 so that the printed layer 7 side of the cover material 6 is in contact with the adhesive layer 2. Covering material 6. Thereby, the structure which laminated | stacked the cover material 6, the adhesive layer 2, the thin film sensor 5b, the adhesive layer 2, the thin film sensor 5a, the adhesive layer 2, and the peeling sheet 3b (or 3a) in this order was obtained.

Finally, the release sheet 3b (or 3a) is peeled from the above-mentioned structure, and the structure is bonded to the display module 4 so that the exposed adhesive layer 2 is in contact with the display module 4. Thereby, the touch panel 10 shown in FIG. 2 is manufactured.

When the adhesive layer 2 in contact with the covering material 6 is composed of an adhesive composition P containing a (meth) acrylate polymer (A) as an adhesive component, the (meth) acrylate polymer (A) has the aforementioned properties. When the predetermined composition and molecular weight and the adhesive layer 2 have a predetermined thickness, the step difference of the adhesive layer 2 follows Excellent sex. Therefore, when the adhesive layer 2 and the cover material 6 are bonded in the above process, voids or bubbles are difficult to form between the step difference generated by the printing layer 7 and the adhesive layer 2, and the adhesive layer 2 can fill the step difference. In addition, even when the touch panel 10 is placed under high temperature and high humidity conditions, it is possible to prevent air bubbles and the like from being generated near the step.

In the touch panel 10 described above, since the adhesive layer 2 has a predetermined haze value, it exhibits excellent pattern visibility suppression effects, and it is difficult to observe the circuit pattern of the transparent conductive film 52. In addition, since the adhesive layer 2 has high light transmittance, the screen of the display body module 4 can be displayed as colorless. In addition, when the adhesive layer 2 is composed of an adhesive composition P containing a (meth) acrylate polymer (A) as an adhesive component, and the (meth) acrylate polymer (A) has the aforementioned predetermined composition, the The pressure-sensitive adhesive layer 2 has excellent resistance to moist heat and whitening. When the touch panel 10 is returned to normal temperature after being placed under high temperature and high humidity conditions, whitening is suppressed.

In addition, the touch panel 10 may include other layers in addition to the above-mentioned layers, which exert a pattern visibility suppression effect. For example, a well-known refractive index adjustment layer (refractive index matching layer) may be included between the base film 51 and the transparent conductive film 52 in the first thin film sensor 5a and / or the second thin film sensor 5b.

The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Therefore, each of the elements disclosed in the above embodiments is intended to include all design changes or equivalents belonging to the technical scope of the present invention.

For example, any one of the release sheets 3a and 3b in the double-sided adhesive sheet 1 may be omitted.

[Example]

Hereinafter, the present invention will be further specifically described by examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Example 1]

1. Preparation of (meth) acrylate copolymer

90 mass parts of n-butyl acrylate and 10 mass parts of acrylic acid were copolymerized to prepare a (meth) acrylate polymer (A). As a result of measuring the molecular weight of this (meth) acrylate polymer (A) by the method mentioned later, the weight average molecular weight (Mw) was 400,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the above process (1) (solid content conversion value; the same applies hereinafter), and 1 of the crosslinking agent (B) (epoxy-based crosslinking agent) 0.057 parts by mass of 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name "TETRAD C-5") as a silane coupling agent 0.25 parts by mass of etheroxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403"), and a light-diffusing fine particle containing an intermediate structure containing inorganic and organic Particles (manufactured by Japan Momentive Performance Materials Inc., trade name “TOSPEARL120”, average particle diameter: 2.0 μm, refractive index: 1.42) 0.1 parts by mass of the silicon compound and sufficiently stirred, and diluted with methyl ethyl ketone to obtain a solid content A coating solution of an adhesive composition having a concentration of 34% by mass.

Table 1 shows the blending of the adhesive composition. Details of abbreviations and the like described in Table 1 are as follows.

[(Meth) acrylate polymer (A)]

BA: n-butyl acrylate

AA: Acrylic

2EHA: 2-ethylhexyl acrylate

MMA: methyl methacrylate

HEA: 2-hydroxyethyl acrylate

[Crosslinking agent (B)]

Epoxy: 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name "TETRAD C-5")

Isocyanate: xylene diisocyanate-based crosslinking agent (manufactured by TOYO INK CO., LTD., Product name "BHS8515")

[Light diffusing fine particles]

TOSPEARL120: fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (manufactured by Japan Momentive Performance Materials Inc., trade name "TOSPEARL120", average particle diameter: 2.0 μm, refractive index: 1.43)

TOSPEARL145: fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (manufactured by Japan Momentive Performance Materials Inc., trade name "TOSPEARL145", average particle diameter: 4.5 μm, refractive index: 1.43)

SSX102: cross-linked acrylic resin beads (manufactured by SEKISUI PLASTICS CO., LTD., Trade name "SSX102", average particle diameter: 2.5 μm, refractive index: 1.49)

SSX104: cross-linked acrylic resin beads (manufactured by SEKISUI PLASTICS CO., LTD., Trade name "SSX104", average particle diameter: 4.0 μm, refractive index: 1.49)

3. Manufacturing of double-sided adhesive sheet

The coating solution of the obtained adhesive composition was applied with a doctor blade coater so that the thickness after drying became 25 μm to a unit of a polyethylene terephthalate film using a silicone release agent. After the release-treated surface of a heavy release-type release sheet (manufactured by Lintec Corporation, product name "SP-PET752150") on which the surface was subjected to release treatment, it was heat-treated at 90 ° C for 1 minute to form a coating layer. Similarly, the coating solution of the obtained adhesive composition was applied to a polyethylene terephthalate using a doctor blade coater so that the thickness after drying became 25 μm. After the release-treated surface of a light release type release sheet (manufactured by Lintec Corporation, product name "SP-PET382120") of which one side of the ester film was peeled off, the heat treatment was performed at 90 ° C for 1 minute to form a coating layer.

Next, the above-obtained heavy release-type release sheet with a coating layer and the above-mentioned light-release type release sheet with a coating layer were bonded together so that the two coating layers were in contact with each other. After curing for 7 days under the conditions of 50 ° C and 50 ° C, a double-sided adhesive sheet composed of a heavy release type release sheet / adhesive layer (thickness: 50 μm) / light release type release sheet was produced. The thickness of the adhesive layer is a value measured in accordance with JIS K7130 using a constant-pressure thickness measuring device (manufactured by TECLOCK Company Inc., product name "PG-02").

[Examples 2 to 14, Comparative Examples 1 to 8]

As shown in Table 1, the types, ratios, and average molecular weights (Mw) of the monomers constituting the (meth) acrylate polymer (A) were changed, and the types and blending amounts of the cross-linking agent (B) and light diffusion were changed. A double-sided adhesive sheet was produced in the same manner as in Example 1 except for the type and amount of the fine particles.

Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

‧GPC measuring device: manufactured by Tosoh Corporation, HLC-8020

‧GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (× 2)

TSK gel G2000HXL

‧Determination solvent: tetrahydrofuran

‧Measuring temperature: 40 ℃

[Test Example 1] (Measurement of Haze Value)

About the adhesive layer of the double-sided adhesive sheet obtained by the Example and the comparative example, the haze value (%) was measured using the haze meter (NIPPON DENSHOKU INDUSTRIES Co., Ltd., NDH2000) based on JISK 7136: 2000. The results are shown in Table 2.

[Experimental Example 2] (Evaluation of the effect of pattern visible suppression)

A transparent conductive film (manufactured by OIKE & Co., Ltd.) provided with a transparent conductive film (ITO film) made of tin-doped indium oxide (ITO) on one side of a polyethylene terephthalate film having a thickness of 125 μm, ITO film) on the ITO film, a plurality of polyimide adhesive tapes (1 cm in width) were laminated so as to be spaced apart by 1 cm and arranged in parallel.

The obtained laminated body was immersed in acetic acid adjusted to 1 mol / l for 2 minutes, and the portion of the ITO film to which the polyimide adhesive tape was not pasted was placed. Line etching. Next, the laminated body was sufficiently washed with ion-exchanged water, and then dried at 120 ° C. for 10 minutes, and then the polyimide adhesive tape was peeled from the transparent conductive film. As a result, a transparent conductive film in which the ITO film was patterned in such a manner that the ITO film portion having a width of 1 cm and the non-existing portion of the ITO film having a width of 1 cm was repeatedly alternated was obtained.

Next, the transparent conductive thin film in which the ITO film was patterned as described above was subjected to an annealing treatment at 150 ° C. for 90 minutes to crystallize the patterned ITO film.

On the other hand, the double-sided pressure-sensitive adhesive sheets obtained in the examples and comparative examples were cut into a width of 45 mm and a length of 70 mm, and then the light-peelable release sheet was peeled off. The exposed adhesive layer was bonded to the patterned ITO film (crystallized) of the transparent conductive film obtained above. A heavy release-type release sheet was peeled from this laminate, and the exposed adhesive layer was attached to a glass plate having a thickness of 0.5 mm made of alkali-free glass, and this was used as a sample.

The sample was pressurized in an autoclave at 0.5 MPa and 50 ° C. for 30 minutes, and then charged in an environment of 85 ° C. and 85% RH for 72 hours. Thereafter, it was confirmed whether the circuit pattern can be visually observed from the polyethylene terephthalate film side, and the pattern visually suppressing effect was evaluated by the following criteria. The results are shown in Table 2.

：: No pattern was observed.

：: Patterns are faintly observed.

×: A pattern is observed.

[Experimental Example 3] (Evaluation of Step Followability)

(a) Preparation of evaluation samples

On a surface of a glass plate (product name: "Corning glass EAGLE XG", manufactured by NSG Precision Co, Ltd., 90 mm in height x 50 mm in width x 0.5 mm in thickness), the thickness of the coating was any of 5 μm, 10 μm, 15 μm, and 20 μm. As a method, a UV-curable ink (manufactured by Teikoku Printing Inks Mfg. Co., Ltd., product name "POS-911 ink") was screen-printed into a frame shape (outer shape: 90 mm in length × 50 mm in width, 5 mm in width). Next, ultraviolet rays were irradiated (80 W / cm ² , two metal halide lamps, a lamp height of 15 cm, and a belt speed of 10 to 15 m / min) to harden the above-mentioned ultraviolet curable ink for printing to produce a step (step difference) caused by printing. Height: any of 5 μm, 10 μm, 15 μm, and 20 μm).

The light-peeling type release sheet was peeled from the double-sided adhesive sheet obtained in the examples and comparative examples, and the exposed adhesive layer was bonded to a polyethylene terephthalate film (Toyobo Co., Ltd., PET A4300, thickness: 100 μm). Next, the heavy release type peeling sheet was peeled to expose the adhesive layer. Then, a laminating machine (product name "LPD3214" manufactured by Fujipura Company Inc.) was used to cover the entire frame-shaped printing surface with an adhesive layer, and the laminated volume layers were laminated on each stepped glass plate to obtain an evaluation sample. .

(b) Evaluation of evaluation samples

The obtained samples for evaluation were subjected to an autoclave treatment at 50 ° C. and 0.5 MPa for 30 minutes, and then stored for 72 hours under humid and hot conditions at 85 ° C. and 85% RH. Thereafter, the adhesive layer was visually confirmed (especially in the vicinity of the step difference caused by the printed layer), and the step followability was evaluated by the following criteria. The results are shown in Table 2.

(Double-circle): There are no bubbles, lifting, and peeling at all.

○: Only bubbles having a diameter of 0.2 mm or less were generated.

×: Bubbles exceeding 0.2 mm in diameter were generated, lifted, or peeled.

[Test Example 4] (Evaluation of anti-foaming properties)

A transparent conductive film of polyethylene terephthalate film (ITO film, thickness: 125 μm) provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side, and Acrylic plate (manufactured by Mitsubishi Gas Chemical Company, IUPILON SHEET MR200, thickness: 1 mm) made of polymethyl methacrylate (PMMA) or polycarbonate (PC) plate (manufactured by Mitsubishi Gas Chemical Company, IUPILON SHEET MR58, thickness: 1mm) sandwiched the adhesive layer of the double-sided adhesive sheet obtained in the Example and the comparative example, and obtained the laminated body.

The obtained laminated body was subjected to an autoclave treatment at 50 ° C. and 0.5 MPa for 30 minutes, and then left at normal pressure, 23 ° C., and 50% RH for 15 hours. Then, it was stored for 72 hours under the durable conditions of 85 ° C. and 85% RH. Thereafter, the presence or absence of bubbles, lifting, or peeling in the adhesive layer was visually confirmed, and the anti-foaming property was evaluated by the following criteria. The results are shown in Table 2.

(Circle): There are no bubbles, lifting, and peeling at all, or only bubbles with a diameter of 0.1 mm or less are generated.

×: Bubbles exceeding 0.1 mm in diameter were generated, raised or peeled.

[Test Example 5] (Evaluation of Humidity and Whitening Resistance)

Prepare two polyethylene terephthalate films (ITO film, thickness: 125 μm) manufactured by OIKE & Co., Ltd. with a transparent conductive film made of tin-doped indium oxide (ITO) on one side. Transparent ITO Film and Example Or the adhesive layer of the double-sided adhesive sheet obtained in the comparative example was sandwiched in such a manner that the adhesive layer was contacted, and the laminate was used as a sample.

First, the haze value (haze value before the wet heat condition) of the obtained sample was measured. Then, the sample was stored for 72 hours under a humid heat condition of 85 ° C. and 85% RH. After that, the atmosphere was returned to 23 ° C. and 50% RH (normal temperature and normal humidity), and the haze value (haze value after moist heat condition) of the sample was measured within 30 minutes. The haze value is measured in accordance with JIS K7136: 2000 using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH2000").

The haze value before the moist heat condition is subtracted from the haze value after the moist heat condition to calculate a haze value increase (percentage) after the moist heat condition. The results are shown in Table 2. If the increase in the haze value is less than 1.0%, it can be said that the moist heat whitening resistance is good.

As can be seen from Table 2, the pattern of the adhesive layer of the double-sided adhesive sheet obtained in the example is excellent in visual suppression performance, and has good step-followability and resistance to hot and whitening. In addition, the adhesive layers of Examples 8 to 14 using a hydroxyl-containing monomer and a hard monomer as monomer units constituting the (meth) acrylate polymer (A) were also excellent in foam resistance.

[Industrial availability]

Touch of the double-sided adhesive sheet of the present invention in the form of electrostatic capacitance Very useful when using an adhesive layer in a panel.

Claims (5)

A double-sided adhesive sheet includes an adhesive layer disposed between two patterned transparent conductive films, or between a patterned transparent conductive film and a cover material or a display body module, which is characterized in that: The adhesive layer is composed of an adhesive. The adhesive is formed of an adhesive composition containing an adhesive component and light diffusing fine particles. The haze value of the adhesive layer is 2 to 40%. The double-sided adhesive sheet according to item 1 of the scope of the patent application, wherein the average particle diameter of the light diffusion fine particles by the centrifugal sedimentation light transmission method is 0.1-20 μm. The double-sided adhesive sheet according to item 1 of the patent application scope, wherein the aforementioned adhesive component contains a (meth) acrylate polymer. The double-sided adhesive sheet according to item 3 of the scope of patent application, wherein the (meth) acrylate polymer is crosslinked by a crosslinking agent. The double-sided adhesive sheet according to item 3 of the scope of patent application, wherein the content of the light-diffusing fine particles is 0.01 to 15 parts by mass relative to 100 parts by mass of the (meth) acrylate polymer.