JP6290377B2 - Laminate - Google Patents

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet that can be used for a touch panel or the like.

  In various mobile electronic devices such as smartphones and tablet terminals in recent years, a capacitive touch panel is often used as a display.

  There are various configurations of capacitive touch panels. As a typical example, a display module such as a liquid crystal module, a first film sensor laminated thereon with an adhesive layer thereon, The structure provided with the 2nd film sensor laminated | stacked through the adhesive layer and the cover material laminated | stacked through the adhesive layer on it is mentioned.

  The film sensor is usually composed of a base film and a transparent conductive film made of patterned tin-doped indium oxide (ITO). In a touch panel having such a patterned transparent conductive film, there is a so-called bone appearance problem in which the circuit pattern of the transparent conductive film is visible and the appearance is impaired.

  In order to solve the above-mentioned problem of bone appearance, in Patent Document 1, an undercoat layer is formed between a film substrate and a transparent conductor layer, and the refractive index of the transparent conductor layer and the refractive index of the undercoat layer are By utilizing the difference, an attempt is made to suppress the difference in reflectance between the pattern portion and the non-pattern portion of the transparent conductor layer, thereby suppressing the appearance of bone.

  Moreover, in patent document 2, between the polyester film and the transparent conductor layer, the easy-adhesion layer which prescribed | regulated content, refractive index, and thickness of a polyester resin, and an optical adjustment layer are laminated | stacked, and the optical by an easy-adhesion layer is used. By suppressing the influence of interference, it tries to suppress bone appearance.

JP 2011-142089 A JP2013-184431A

  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 bone appearance suppressing effect. Moreover, there also existed a problem that cost became high by providing an 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 bone appearance suppressing effect.

  This invention is made | formed in view of the above actual conditions, and provides the double-sided adhesive sheet which can make it difficult to see the circuit pattern of a transparent conductive film with an adhesive layer in a capacitive touch panel etc. For the purpose.

  In order to achieve the above object, first, the present invention provides an adhesive layer disposed between two patterned transparent conductive films, or between a patterned transparent conductive film and a cover material or a display module. The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composed of a pressure-sensitive adhesive composition and a light-diffusing fine particle, and the haze value of the pressure-sensitive adhesive layer is 2 to 40%. A double-sided PSA sheet is provided (Invention 1).

  When the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet according to the invention (Invention 1) is disposed between two patterned transparent conductive films, or between a patterned transparent conductive film and a cover material or a display module. Moreover, when the haze value of the pressure-sensitive adhesive layer is in the above range, it is possible to make it difficult to see the circuit pattern of the transparent conductive film while maintaining high light transmittance.

  In the said invention (invention 1), it is preferable that the average particle diameter by the centrifugal sedimentation light transmission method of the said light-diffusing fine particle is 0.1-20 micrometers (invention 2).

  In the said invention (invention 1 and 2), it is preferable that the said adhesion component contains a (meth) acrylic acid ester polymer (invention 3).

  In the said invention (invention 3), it is preferable that the said (meth) acrylic acid ester polymer is bridge | crosslinked by the crosslinking agent (invention 4).

  In the said invention (invention 3 and 4), it is preferable that content of the said light-diffusion fine particle is 0.01-15 mass parts with respect to 100 mass parts of said (meth) acrylic acid ester polymers (invention 5). ).

  Moreover, this invention is an adhesive layer of the said double-sided adhesive sheet (invention 1-5) between two patterned transparent conductive films, or between a patterned transparent conductive film, and a cover material or a display body module. There is provided a laminated body characterized by comprising: In this laminate, the pressure-sensitive adhesive layer may be in direct contact with the transparent conductive film, the cover material, or the display module, or may not be in contact.

  According to the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet according to the present invention, it is possible to make it difficult to see the circuit pattern of the transparent conductive film while maintaining high light transmittance in a capacitive touch panel or the like.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows one structural example of a touchscreen.

Hereinafter, embodiments of the present invention will be described.
The double-sided pressure-sensitive adhesive sheet according to this embodiment includes a pressure-sensitive adhesive layer disposed between two patterned transparent conductive films or between a patterned transparent conductive film and a cover material or a display module. is there.

  As shown in FIG. 1, the double-sided pressure-sensitive adhesive sheet 1 according to this embodiment includes two release sheets 3a and 3b and the two release sheets so as to be in contact with the release surfaces of the two release sheets 3a and 3b. It is comprised from the adhesive layer 2 clamped by 3a, 3b. However, in the double-sided pressure-sensitive adhesive sheet 1, the release sheets 3a and 3b are not essential components, and are peeled off and removed when the double-sided pressure-sensitive adhesive sheet 1 is used. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

1. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 2 in the present embodiment is constituted by a pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive component and light diffusing fine particles (hereinafter sometimes referred to as “pressure-sensitive adhesive composition P”). The haze value is 2 to 40%. In the pressure-sensitive adhesive layer 2 in the present embodiment, by using the light diffusing fine particles and controlling the haze value as described above, a transparent conductive film is maintained while maintaining high light transmittance in a capacitive touch panel or the like. This makes it difficult to see the circuit pattern and exhibits an excellent bone-inhibiting effect.

  If the haze value is less than 2%, the effect of suppressing bone appearance cannot be obtained, and the circuit pattern of the transparent conductive film can be seen. Further, even if the haze value exceeds 40%, the bone appearance suppression effect cannot be obtained. From this viewpoint, the haze value of the pressure-sensitive adhesive layer 2 is preferably 3 to 30%, and particularly preferably 6 to 20%. The haze value in the present specification is a value measured according to JIS K7136: 2000.

(1) Adhesive component The adhesive component is not particularly limited as long as it exhibits a desired adhesive force on a capacitive touch panel or the like, has optical transparency, and does not inhibit the effect of the light diffusing fine particles. . Examples of the adhesive component include an acrylic adhesive component, a rubber adhesive component, a silicone adhesive component, a polyurethane adhesive component, and a polyester adhesive component. Among these, an acrylic adhesive component is preferable from the above viewpoint.

  As the acrylic pressure-sensitive adhesive component, those containing the (meth) acrylic acid ester polymer (A) are preferable, and in particular, the (meth) acrylic acid ester polymer (A) cross-linked by the cross-linking agent (B) is preferable. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. In the present specification, the term “polymer” includes the concept of “copolymer”.

(1-1) (Meth) acrylic acid ester polymer (A)
The (meth) acrylic acid ester polymer (A) preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer constituting the polymer. Thereby, the obtained adhesive can express preferable adhesiveness. The (meth) acrylic acid ester polymer (A) is a monomer having a functional group that reacts with the alkyl group (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms and the crosslinking agent (B) (reactivity). Particularly preferred is a copolymer of a functional group-containing monomer) and other monomers used as desired. In addition, the below-mentioned hard monomer is removed from the (meth) acrylic acid alkyl ester.

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, ( N-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate , Myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferable, methyl acrylate, n-butyl (meth) acrylate and (meth) acrylic acid 2- Ethylhexyl is particularly preferred. In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) contains 30 to 90% by mass of (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. The content is preferably 40 to 75% by mass, more preferably 50 to 65% by mass.

  As the reactive functional group-containing monomer, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing) Monomer) and the like.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate is preferred from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers. Is preferred. These 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 preferable from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) of the carboxyl group and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

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

  When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a reactive functional group-containing monomer constituting the polymer, the content is from the viewpoint of step following ability under durable conditions. It is preferably 15 to 30% by mass, particularly preferably 17 to 28% by mass. Furthermore, in addition to the above viewpoint, 20 to 25% by mass from the viewpoint of optimizing moisture and heat whitening resistance. It is preferable that

  When the (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a reactive functional group-containing monomer that constitutes the polymer, the content is the viewpoint of step following ability under durability conditions. From 5 to 25% by mass, particularly 7 to 20% by mass is preferable. Furthermore, in addition to the above-mentioned viewpoints, the moisture and heat whitening resistance is also optimal, so that it is 10 to 15% by mass. % Is preferred.

  Here, when the touch panel or the like is placed in a high-temperature and high-humidity environment, moisture enters the pressure-sensitive adhesive layer, and when the touch panel or the like returns to room temperature, the pressure-sensitive adhesive layer is whitened and transparency is reduced. There is a problem of "humid heat whitening". When the (meth) acrylic acid ester polymer (A) contains the reactive functional group-containing monomer in the above range, a predetermined amount of the reactive functional group remains in the pressure-sensitive adhesive layer. The reactive functional group is usually a hydrophilic group, and when such a hydrophilic group is present in the pressure-sensitive adhesive layer in a predetermined amount, even when the pressure-sensitive adhesive layer is placed under high-temperature and high-humidity conditions, The compatibility with the water | moisture content which permeated the adhesive layer below is good, As a result, whitening of an adhesive layer is suppressed and the adhesive layer 2 becomes the thing excellent in moisture-heat whitening resistance.

  The (meth) acrylic acid ester polymer (A) preferably contains an acrylic acid ester hard monomer as a monomer unit constituting the polymer. Here, the hard monomer means a monomer having a glass transition temperature (Tg) of 70 ° C. or higher, preferably 75 to 200 ° C., particularly preferably 80 to 180 ° C., as a homopolymer obtained by polymerizing only the hard monomer. Say. By including the hard monomer as a monomer unit constituting the (meth) acrylic acid ester polymer (A), the obtained pressure-sensitive adhesive has excellent durability and blister resistance. Therefore, even when the adherend is a plastic plate and outgas is generated from the plastic plate, occurrence of blisters such as bubbles, floats, and peeling is suppressed.

  Examples of the hard monomer include methyl methacrylate (Tg 105 ° C.), isobornyl acrylate (Tg 94 ° C.), isobornyl methacrylate (Tg 180 ° C.), acryloylmorpholine (Tg 145 ° C.), adamantyl acrylate (Tg 115 ° C.), and adamantyl methacrylate. (Tg 141 ° C.), dimethylacrylamide (Tg 89 ° C.), acrylamide (Tg 165 ° C.) and the like. These may be used alone or in combination of two or more.

  Among the hard monomers, methyl methacrylate, isobornyl acrylate and acryloyl morpholine are more preferable from the viewpoint of exerting the performance of the hard monomer while preventing adverse effects on other properties such as adhesion and transparency, and methacrylic acid. Methyl is particularly preferred.

  The (meth) acrylic acid ester polymer (A) preferably contains 10 to 45% by mass of the hard monomer as a monomer unit constituting the polymer, and particularly preferably contains 15 to 30% by mass. By containing the hard monomer in an amount of 10% by mass or more, an effect of improving durability or blister resistance by the monomer unit can be expected. On the other hand, by setting the hard monomer content to 45% by mass or less, the relative shortage of other monomer units in the (meth) acrylic acid ester polymer (A) is prevented, and the pressure-sensitive adhesive obtained Adhesiveness, level difference followability and wet heat whitening resistance can be improved.

  The (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer and the hard monomer in the above-described ranges as monomer units constituting the polymer. Thereby, the obtained adhesive becomes more excellent in blister resistance.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group in order not to interfere with the action of the hydroxyl group-containing monomer. Such other monomers include, for example, (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and aliphatic rings such as cyclohexyl (meth) acrylate (meta ) Acrylic acid ester, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid N, N-dimethylaminopropyl, etc. (meth) acrylic acid ester having acetic acid tertiary amino group, acetic acid Examples include vinyl and styrene. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 100,000 to 1,500,000, particularly preferably 200,000 to 1,300,000, and more preferably 300,000 to 800,000. preferable. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

  When the adhesive composition P contains the (meth) acrylic acid ester polymer (A) as an adhesive component, and the (meth) acrylic acid ester polymer (A) has the above-mentioned predetermined composition and molecular weight, it is obtained. The pressure-sensitive adhesive layer 2 is excellent in step following ability. Therefore, even if the pressure-sensitive adhesive layer 2 is affixed to a cover material having a step due to a printed layer or the like, it is difficult to form a gap or a bubble between the step and the pressure-sensitive adhesive layer. Moreover, even when the laminate is placed at a high temperature such as 80 ° C., bubbles and the like are prevented from being generated in the vicinity of the step.

(1-2) Crosslinking agent (B)
When the adhesive component of the adhesive composition P contains a (meth) acrylic acid ester polymer (A) containing a reactive functional group-containing monomer as a monomer unit constituting the polymer, and a crosslinking agent (B), When the 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) acrylic acid ester polymer (A). Thereby, the structure by which (meth) acrylic acid ester polymer (A) was bridge | crosslinked with the crosslinking agent (B) is formed, and the intensity | strength and durability of the adhesive layer 2 improve.

  The crosslinking agent (B) may be any one that reacts with the reactive functional group of the (meth) acrylic acid ester polymer (A). For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, and an amine crosslinking agent. , Melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Is mentioned. Among these, when the reactive functional group of the (meth) acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that is excellent in reactivity with the hydroxyl group, and (meth) acrylic acid When the reactive functional group which the ester polymer (A) has is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group. In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

  It is preferable that content of the crosslinking agent (B) in the adhesive composition P is 0.001-10 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), especially 0. It is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 1 part by mass.

(2) Light diffusing fine particles The light diffusing fine particles may be any as long as the haze value of the pressure-sensitive adhesive layer 2 can be within the above range. For example, silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay Inorganic fine particles such as talc and titanium dioxide; organic translucent fine particles such as acrylic resin, polystyrene resin, polyethylene resin, and epoxy resin; silicon-containing intermediate structure between inorganic and organic such as silicone resin Fine particles composed of a compound (for example, Tospearl series manufactured by Momentive Performance Materials Japan) are included. Among these, acrylic resin fine particles and fine particles made of a silicon-containing compound having an intermediate structure between inorganic and organic are preferable because they are excellent in dispersibility with respect to the adhesive component and can provide uniform optical properties. The above light diffusing fine particles may be used alone or in combination of two or more.

  The shape of the light diffusing fine particles is preferably spherical fine particles with uniform light diffusion. The average particle diameter of the light diffusing fine particles by 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 made of a silicon-containing compound, the average particle diameter by the centrifugal sedimentation light transmission method is preferably 1 to 10 μm. When the average particle size is within the above range, the haze value can be set to the above-described range without hindering the light transmittance of the pressure-sensitive adhesive layer 2.

  In addition, the average particle diameter by the centrifugal sedimentation light transmission method was obtained by sufficiently stirring 1.2 g of fine particles and 98.8 g of isopropyl alcohol as a measurement sample, and using a centrifugal automatic particle size distribution measuring apparatus (manufactured by Horiba, Ltd., Measured using CAPA-700).

  When the adhesive composition P contains the (meth) acrylate polymer (A) as an adhesive component, the content of the light diffusing fine particles is 100 parts by mass of the (meth) acrylate polymer (A). 0.01 to 15 parts by mass, more preferably 0.1 to 4 parts by mass. Furthermore, in the case of light diffusing fine particles made of a silicon-containing compound having an intermediate structure between organic and inorganic, such as a silicone resin, the amount is particularly preferably 0.2 to 1.5 parts by mass. The amount is most preferably 2 to 0.9 parts by mass, and in the case of organic translucent fine particles, the amount is most preferably 0.3 to 3 parts by mass. When the content of the light diffusing fine particles is within the above range, the haze value of the pressure-sensitive adhesive layer 2 can be set to the above-described range, and an excellent bone appearance suppressing effect can be obtained. When the adhesive component is other than the acrylic adhesive component, the content of the light diffusing fine particles is preferably in the above range with respect to 100 parts by mass of the adhesive component.

(3) Various additives The pressure-sensitive adhesive composition P (the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2) may be various additives such as a silane coupling agent, a refractive index adjusting agent, an antistatic agent, a tackifier, if desired. You may contain antioxidant, a ultraviolet absorber, a light stabilizer, a softener, a filler, etc.

  The adhesive composition P preferably contains a silane coupling agent from the viewpoint of improving the adhesive strength of the obtained adhesive. The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the adhesive component and having light transmittance.

  Examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane Amino group-containing silicon such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane Compound, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of them, and alkyl group-containing silicon such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Examples include condensates with compounds. These may be used individually by 1 type and may be used in combination of 2 or more type.

  When the adhesive composition P contains the (meth) acrylate polymer (A) as an adhesive component, the content of the silane coupling agent is 100 parts by mass of the (meth) acrylate polymer (A). The content is preferably 0.01 to 10 parts by mass, particularly preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 1 part by mass. In addition, when an adhesive component is other than an acrylic adhesive component, it is preferable that content of a silane coupling agent is said range with respect to 100 mass parts of adhesive components.

(4) Production of Adhesive Composition The adhesive composition P can be produced by mixing an adhesive component, light diffusing fine particles, and an additive as required. When the pressure-sensitive adhesive component contains the (meth) acrylic acid ester polymer (A), the (meth) acrylic acid ester polymer (A) is prepared first, and a crosslinking agent (B) is blended if desired.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  When the (meth) acrylic acid ester polymer (A) is obtained, the light diffusing fine particles, and optionally the crosslinking agent (B), and additives are added to the solution of the (meth) acrylic acid ester polymer (A). By sufficiently mixing, an adhesive composition P (coating solution) diluted with a solvent is obtained.

  Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-40 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added.

(5) Formation of adhesive The adhesive in this embodiment is formed from the adhesive composition P. The pressure-sensitive adhesive can be usually formed by heat-treating the pressure-sensitive adhesive composition P. In addition, this heat processing can also serve as the drying process at the time of volatilizing the dilution solvent of the adhesive composition P, etc.

  When the adhesive composition P contains the (meth) acrylic acid ester polymer (A), the heating temperature of the heat treatment is preferably 50 to 150 ° C, particularly preferably 70 to 120 ° C. . The heating time is preferably 30 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). When this curing period is necessary, after the curing period has elapsed, and when the curing period is unnecessary, an adhesive is formed after the heat treatment.

(6) Thickness of the pressure-sensitive adhesive layer The thickness of the pressure-sensitive adhesive layer 2 (value measured according to JIS K7130) is preferably 5 to 600 μm, particularly preferably 20 to 300 μm, and further 50 It is preferable that it is -150 micrometers. Good adhesiveness is exhibited when the thickness of the pressure-sensitive adhesive layer 2 is 5 μm or more. Further, when pasted on an adherend having a step, the step following ability is exhibited. On the other hand, when the thickness of the pressure-sensitive adhesive layer 2 is 600 μm or less, workability is improved. The pressure-sensitive adhesive layer 2 may be formed as a single layer or may be formed by laminating a plurality of layers.

2. Release sheet Although it does not specifically limit as release sheet 12a, 12b, For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, Polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, A polycarbonate film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 2) of the release sheets 12a and 12b is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. Of the release sheets 12a and 12b, one release sheet is preferably a heavy release release sheet having a high release force, and the other release sheet is preferably a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of release sheet 12a, 12b, Usually, it is about 20-150 micrometers.

3. Manufacture of a double-sided pressure-sensitive adhesive sheet As one production example of the double-sided pressure-sensitive adhesive sheet 1, the coating liquid of the above-mentioned pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a (or 12b) and subjected to heat treatment, thereby applying a coating layer Then, the release surface of the other release sheet 12b (or 12a) is overlaid on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 2 as it is. Thereby, the said double-sided adhesive sheet 1 is obtained. The conditions for the heat treatment and curing are as described above.

  As another manufacturing example of the double-sided pressure-sensitive adhesive sheet 1, a coating layer is formed by applying a coating solution of the above-mentioned pressure-sensitive adhesive composition P to the release surface of one release sheet 12a and performing a heat treatment. The release sheet 12a is obtained. Moreover, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of the other peeling sheet 12b, heat processing are performed, an application layer is formed, and the peeling sheet 12b with an application layer is obtained. And the peeling sheet 12a with an application layer and the peeling sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When the curing period is necessary, the curing period is set, and when the curing period is unnecessary, the above-mentioned laminated application layer becomes the pressure-sensitive adhesive layer 2 as it is. Thereby, the said double-sided adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 2 is thick, it can be produced stably.

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P.

4). Use of a double-sided adhesive sheet The double-sided adhesive sheet 1 which concerns on this embodiment can be used for the laminated body which has a circuit pattern of a transparent conductive film, and can be preferably used especially for a capacitive touch panel etc. When the double-sided pressure-sensitive adhesive sheet 1 is used for a capacitive touch panel, the pressure-sensitive adhesive layer 2 may be present at any position between the touch panel display module and the cover material. For example, it can be located between two transparent conductive films, between a transparent conductive film and a cover material, and between a transparent conductive film and a display module. Even if the pressure-sensitive adhesive layer 2 is present at any of these positions, the circuit pattern of the transparent conductive film becomes difficult to see due to the excellent bone-inhibiting effect of the pressure-sensitive adhesive layer 2.

  By using the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment, for example, the capacitive touch panel 10 shown in FIG. 2 can be manufactured. The touch panel 10 includes a display module 4, a first film sensor 5 a laminated thereon via an adhesive layer 2, and a second film sensor 5 b laminated thereon via an adhesive layer 2. And the cover material 6 laminated | stacked through the adhesive layer 2 on it is comprised.

  The three pressure-sensitive adhesive layers 2 in the touch panel 10 are the pressure-sensitive adhesive layers 2 of the double-sided pressure-sensitive adhesive sheet 1, but are not limited to this, and at least one pressure-sensitive adhesive layer 2 is the double-sided pressure-sensitive adhesive sheet 1. The pressure-sensitive adhesive layer 2 may be used. When the 1 or 2 adhesive layer 2 in the touch panel 10 is the adhesive layer 2 of the said double-sided adhesive sheet 1, another adhesive layer is comprised from a desired adhesive. As a desired adhesive, what does not contain the light-diffusion fine particle of the adhesive which comprises the adhesive layer 2 mentioned above can be illustrated.

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

  The 1st film sensor 5a and the 2nd film sensor 5b are normally comprised from the base film 51 and the patterned transparent conductive film 52, respectively. Although it does not specifically limit as the base film 51, For example, a polyethylene terephthalate film, a polycarbonate film, a polymethylmethacrylate film, a polycycloolefin film, a polyolefin film, a triacetylcellulose film etc. are 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, tin-doped indium oxide (ITO), and zinc oxide-doped oxide. Examples include composite oxides such as indium, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, and non-oxidized compounds such as chalcogenide, lanthanum hexaboride, titanium nitride, and titanium carbide. Among these, those made of tin-doped indium oxide (ITO) are preferable.

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

  The transparent conductive film 52 of the first film sensor 5a in the present embodiment is located on the upper side (the cover material 6 side) of the first film sensor 5a in FIG. 2, but is not limited thereto. The first film sensor 5a may be located on the lower side (display module 4 side). Moreover, although the transparent conductive film 52 of the 2nd film sensor 5b is located in the lower side (display body module 4 side) of the 2nd film sensor 5b in FIG. 2, it is not limited to this. , May be positioned above the second film sensor 5b (on the cover material 6 side).

  The cover material 6 is mainly composed of a glass plate or a plastic plate. The glass plate is not particularly limited. For example, chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass. Etc. The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate and the like, and a polycarbonate plate.

  In addition, a functional layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on one side or both sides of the glass plate or plastic plate, or a hard coat film, an antireflection film, or an antiglare film. Such optical members may be laminated.

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

  The material which comprises the printing layer 7 is not specifically limited, The well-known material for printing is used. The thickness of the printing layer 7, that is, the height of the step, is preferably 3 to 45 μm, more preferably 5 to 35 μm, particularly preferably 7 to 25 μm, and preferably 7 to 15 μm. Further preferred.

  Further, the thickness of the printing layer 7 (the height of the step) is preferably 50% or less, particularly preferably 5 to 40%, and more preferably 10 to 30%. Preferably there is. When the thickness of the pressure-sensitive adhesive layer 2 satisfies the above relationship with the thickness of the printing layer 7, the pressure-sensitive adhesive layer 2 follows the step due to the printing layer 7 well, and it is possible to suppress the occurrence of floating or bubbles in the vicinity of the step. .

An example of a method for manufacturing the touch panel 10 will be described below.
As the double-sided pressure-sensitive adhesive sheet 1, first, second and third double-sided pressure-sensitive adhesive sheets 1 are prepared. First, one release sheet 3a (or 3b) is peeled from the first double-sided pressure-sensitive adhesive sheet 1, and the exposed adhesive layer 2 is in contact with the patterned transparent conductive film 52 of the film sensor 5a. Bonding with the sensor 5a. Next, the other release sheet 3b (or 3a) is peeled from the first double-sided pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 2 is in contact with the patterned transparent conductive film 52 of the film sensor 5b. Paste with 5b. Thereby, the laminated body by which the film sensor 5a, the adhesive layer 2, and the film sensor 5b are laminated | stacked one by one is obtained.

  Next, one release sheet 3a (or 3b) is peeled from the second double-sided pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 2 is replaced with the surface on the film sensor 5a side of the laminate (base film of the film sensor 5a). 51 exposed surface). Also, one release sheet 3a (or 3b) is peeled from the third double-sided pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 2 is opposite to the side where the pressure-sensitive adhesive layer 2 is laminated in the laminate. Bonding to the surface (exposed surface of the base film 51 of the film sensor 5b).

  Thereafter, the other release sheet 3b (or 3a) is peeled from the third double-sided pressure-sensitive adhesive sheet 1, and the printed layer 7 side of the cover material 6 is in contact with the pressure-sensitive adhesive layer 2 with respect to the exposed pressure-sensitive adhesive layer 2. The cover material 6 is bonded. Thereby, the structure by which the cover material 6, the adhesive layer 2, the film sensor 5b, the adhesive layer 2, the film sensor 5a, the adhesive layer 2, and the peeling sheet 3b (or 3a) are laminated | stacked one by one is obtained.

  Finally, the release sheet 3b (or 3a) is peeled off from the above-described 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.

  The pressure-sensitive adhesive layer 2 in contact with the cover material 6 is composed of a pressure-sensitive adhesive composition P containing a (meth) acrylic acid ester polymer (A) as a pressure-sensitive adhesive component, and the (meth) acrylic acid ester polymer (A) is When the pressure-sensitive adhesive layer 2 has the predetermined composition and molecular weight and has a predetermined thickness, the pressure-sensitive adhesive layer 2 is excellent in step following ability. For this reason, when the pressure-sensitive adhesive layer 2 and the cover material 6 are bonded together in the above process, it is difficult to form a gap or a bubble between the step formed by the printing layer 7 and the pressure-sensitive adhesive layer 2, and the pressure-sensitive adhesive layer 2 forms the step. Can be filled. Moreover, even when the touch panel 10 is subjected to a high temperature and high humidity condition, it is possible to prevent bubbles and the like from being generated near the step.

  In the touch panel 10 described above, the adhesive layer 2 has a predetermined haze value, so that an excellent bone appearance suppressing effect is exhibited, and the circuit pattern of the transparent conductive film 52 is difficult to see. Moreover, since the adhesive layer 2 has high light transmittance, the screen of the display body module 4 can be displayed clearly. Furthermore, the pressure-sensitive adhesive layer 2 is composed of a pressure-sensitive adhesive composition P containing a (meth) acrylic acid ester polymer (A) as a pressure-sensitive adhesive component, and the (meth) acrylic acid ester polymer (A) is the predetermined one described above. When it has a composition, the pressure-sensitive adhesive layer 2 is excellent in moisture and heat whitening resistance, and whitening when the touch panel 10 returns to room temperature after being placed in a high temperature and high humidity condition is suppressed.

  In addition to the above layers, the touch panel 10 may include other layers that exhibit the effect of suppressing bone appearance. For example, a known refractive index adjustment layer (index matching layer) may be provided between the base film 51 and the transparent conductive film 52 in the first film sensor 5a and / or the second film sensor 5b. .

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

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

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of (meth) acrylic acid ester copolymer 90 parts by mass of n-butyl acrylate and 10 parts by mass of acrylic acid were copolymerized to prepare a (meth) acrylic acid ester polymer (A). When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, it was a weight average molecular weight (Mw) of 400,000.

2. Preparation of Adhesive Composition 100 parts by mass (solid content converted value; the same shall apply hereinafter) of the (meth) acrylic acid ester polymer (A) obtained in the above step (1), and a crosslinking agent (B) (epoxy crosslinking agent) ) 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane (Mitsubishi Gas Chemical Co., Ltd., product name “TETRAD C-5”) 0.057 parts by mass and 3 as a silane coupling agent -From 0.25 part by mass of glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") and a silicon-containing compound having an intermediate structure between inorganic and organic as light diffusion fine particles And 0.1 part by mass of fine particles (Momentive Performance Materials Japan, trade name “Tospearl 120”, average particle size: 2.0 μm, refractive index: 1.42), Min and stirring, by diluting with methyl ethyl ketone to obtain a coating solution having a solid content concentration of 34 wt% of the adhesive composition.

Here, Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic acid ester polymer (A)]
BA: n-butyl acrylate AA: acrylic acid 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: Xylylene diisocyanate-based crosslinking agent (product name “BHS8515” manufactured by Toyo Ink Co., Ltd.)
[Light diffusion fine particles]
Tospearl 120: Fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (made by Momentive Performance Materials Japan, trade name “Tospearl 120”, average particle size: 2.0 μm, refractive index: 1 .43)
Tospearl 145: Fine particles comprising a silicon-containing compound having an intermediate structure between inorganic and organic (made by Momentive Performance Materials Japan, trade name “Tospearl 145”, average particle size: 4.5 μm, refractive index: 1 .43)
SSX102: Crosslinked acrylic resin beads (manufactured by Sekisui Plastics Co., Ltd., trade name “SSX102”, average particle size: 2.5 μm, refractive index: 1.49)
SSX104: Cross-linked acrylic resin beads (manufactured by Sekisui Plastics Co., Ltd., trade name “SSX104”, average particle size: 4.0 μm, refractive index: 1.49)

3. Production of double-sided pressure-sensitive adhesive sheet A coating solution of the obtained pressure-sensitive adhesive composition was prepared from a heavy release type release sheet (product name “SP-PET752150” manufactured by Lintec Corporation) in which one side of a polyethylene terephthalate film was peeled with a silicone-based release agent. The surface to be peeled was coated with a knife coater so that the thickness after drying was 25 μm, and then heat-treated at 90 ° C. for 1 minute to form a coating layer. Similarly, a release treatment of a light release release sheet (product name “SP-PET382120” manufactured by Lintec Corporation) in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent was applied to the obtained adhesive composition coating solution. The surface was coated with a knife coater so that the thickness after drying was 25 μm, and then heat-treated at 90 ° C. for 1 minute to form a coating layer.

  Subsequently, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded so that both coating layers were in contact with each other. Then, by curing for 7 days under the condition of 50% RH, a double-sided pressure-sensitive adhesive sheet having a structure of heavy release type release sheet / adhesive layer (thickness: 50 μm) / light release type release sheet was produced. The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

[Examples 2-14, Comparative Examples 1-8]
The type, ratio and polymerization average molecular weight (Mw) of each monomer constituting the (meth) acrylic acid ester polymer (A), the type and blending amount of the crosslinking agent (B), and the type and blending amount of the light diffusing fine particles are shown. A double-sided PSA sheet was produced in the same manner as in Example 1 except that the change was made as shown in FIG.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[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, haze value (%) was measured according to JISK7136: 2000 using the haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH2000). . The results are shown in Table 2.

[Test Example 2] (Evaluation of bone appearance suppression effect)
On the ITO film of a transparent conductive film (Oike Industry Co., Ltd., ITO film) in which a transparent conductive film (ITO film) made of tin-doped indium oxide (ITO) is provided on one side of a 125 μm thick polyethylene terephthalate film The polyimide pressure-sensitive adhesive tapes (width: 1 cm) were bonded so as to be arranged in parallel at intervals of 1 cm.

  The obtained laminate was dipped in hydrochloric acid adjusted to 1 mol / l for 2 minutes to etch the ITO film portion on which the polyimide adhesive tape was not applied. Subsequently, the laminate was sufficiently washed with ion-exchanged water, dried at 120 ° C. for 10 minutes, and then the polyimide adhesive tape was peeled off from the transparent conductive film. As a result, a transparent conductive film was obtained in which the ITO film was patterned so that the 1 cm wide ITO film portion and the 1 cm wide ITO film non-existing portion were alternately repeated.

  Next, the transparent conductive film patterned with the ITO film as described above was annealed at 150 ° C. for 90 minutes to crystallize the patterned ITO film.

  On the other hand, after the double-sided PSA sheets obtained in Examples and Comparative Examples were cut to a width of 45 mm and a length of 70 mm, the light release type release sheet was peeled off. The exposed adhesive layer was bonded to the patterned ITO film (crystallization) of the transparent conductive film obtained above. The heavy release release sheet was peeled off from the laminate, and the exposed pressure-sensitive adhesive layer was attached to a 0.5 mm thick glass plate made of alkali glass, which was used as a sample.

The sample was pressurized in an autoclave at 0.5 MPa and 50 ° C. for 30 minutes, and then placed in an environment of 85 ° C. and 85% RH for 72 hours. Then, it was confirmed whether the circuit pattern was visually visible from the polyethylene terephthalate film side, and the bone appearance suppression effect was evaluated according to the following criteria. The results are shown in Table 2.
A: The pattern is not visible.
○: The pattern is slightly visible.
X: A pattern is visible.

[Test Example 3] (Evaluation of step following ability)
(A) Preparation of sample for evaluation On the surface of a glass plate (manufactured by NSG Precision, product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), an ultraviolet curable ink (made by Teikoku Ink, The product name “POS-911 Black”) was screen-printed in a frame shape (outside: vertical 90 mm × width 50 mm, width 5 mm) so that the coating thickness was any one of 5 μm, 10 μm, 15 μm, and 20 μm. Next, irradiation with ultraviolet rays (80 W / cm ² , ^two metal halide lamps, lamp height of 15 cm, belt speed of 10 to 15 m / min) is performed to cure the printed ultraviolet curable ink, and a level difference due to printing (level difference) A stepped glass plate having a thickness of any one of 5 μm, 10 μm, 15 μm, and 20 μm was produced.

  The light release type release sheet was peeled off from the double-sided PSA sheet obtained in Examples and Comparative Examples, and the exposed PSA layer was made of a polyethylene terephthalate film (PET A4300, manufactured by Toyobo Co., Ltd., thickness: 100 μm) having an easy adhesion layer. It bonded to the easily bonding layer. Next, the heavy release type release sheet was peeled off to expose the pressure-sensitive adhesive layer. Then, using a laminator (product name “LPD3214”, manufactured by Fuji Plastics Co., Ltd.), the laminate is laminated on each stepped glass plate so that the adhesive layer covers the entire frame-like print, and this is used as an evaluation sample. did.

(B) Evaluation of Evaluation Sample After the obtained evaluation sample was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, it was further stored for 72 hours under wet heat conditions of 85 ° C. and 85% RH. . Thereafter, the pressure-sensitive adhesive layer (particularly in the vicinity of the step due to the printing layer) was visually confirmed, and the step following property was evaluated according to the following criteria. The results are shown in Table 2.
(Double-circle): There was no bubble, floating, and peeling at all.
○: Only bubbles with a diameter of 0.2 mm or less were generated.
X: Bubbles with a diameter of more than 0.2 mm, floating or peeling occurred.

[Test Example 4] (Blister resistance evaluation)
The pressure-sensitive adhesive layer of the double-sided PSA sheet obtained in Examples and Comparative Examples is a polyethylene terephthalate film provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side (Oike Industry Co., Ltd., ITO film, thickness : 125 μm) transparent conductive film and polymethylmethacrylate (PMMA) acrylic plate (Mitsubishi Gas Chemical Co., Ltd., Iupilon sheet MR200, thickness: 1 mm) or polycarbonate (PC) plate (Mitsubishi Gas Chemical Co., Ltd., Iupilon) -Sheet MR58, thickness: 1 mm) to obtain a laminate.

The obtained laminate was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and then allowed to stand at normal pressure, 23 ° C. and 50% RH for 15 hours. Subsequently, it was stored for 72 hours under 85 ° C. and 85% RH durability conditions. Thereafter, it was visually confirmed whether or not the pressure-sensitive adhesive layer had bubbles, floating or peeling, and blister resistance was evaluated according to the following criteria. The results are shown in Table 2.
○: No bubbles, no floating and peeling, or only bubbles with a diameter of 0.1 mm or less were generated.
X: Bubbles with a diameter of more than 0.1 mm, floating or peeling occurred.

[Test Example 5] (Moisture and heat whitening evaluation)
Prepare two sheets of polyethylene terephthalate film (made by Oike Kogyo Co., Ltd., ITO film, thickness: 125 μm) with a transparent conductive film made of tin-doped indium oxide (ITO) on one side. The pressure-sensitive adhesive layer was sandwiched between the double-sided pressure-sensitive adhesive sheets obtained in Examples or Comparative Examples, and the laminate was used as a sample.

  First, the haze value (haze value before wet heat condition) of the obtained sample was measured. Next, the sample was stored for 72 hours under wet heat conditions of 85 ° C. and 85% RH. Then, it returned to the atmosphere of 23 degreeC and 50% RH (normal temperature normal humidity), and the haze value (haze value after wet heat conditions) of the said sample was measured within 30 minutes. The haze value was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name “NDH2000”) according to JIS K7136: 2000.

  The haze value before the moist heat condition was subtracted from the haze value after the moist heat condition to calculate an increase (point) in haze value after the moist heat condition. The results are shown in Table 2. If this haze value rise is less than 1.0 point, it can be said that heat-and-moisture whitening resistance is good.

  As can be seen from Table 2, the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet obtained in the examples was excellent in bone appearance suppression performance, and had good step followability and moisture heat whitening resistance. Moreover, the adhesive layer of Examples 8-14 which used the hydroxyl-containing monomer and the hard monomer as a monomer unit which comprises a (meth) acrylic acid ester polymer (A) was excellent also in blister resistance.

  The double-sided pressure-sensitive adhesive sheet of the present invention is very useful for forming a pressure-sensitive adhesive layer used for a capacitive touch panel.

DESCRIPTION OF SYMBOLS 1 ... Double-sided adhesive sheet 2 ... Adhesive layer 3a, 3b ... Release sheet 4 ... Display body module 5a ... 1st film sensor 5b ... 2nd film sensor 51 ... Base film 52 ... Transparent electrically conductive film 6 ... Cover material 7 ... Printing layer 10 ... Touch panel

Claims (5)

A laminate comprising an adhesive layer between two patterned transparent conductive films, or between a patterned transparent conductive film and a cover material or display module,
The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive component and light diffusing fine particles,
A laminate having a haze value of 2 to 30 %.   2. The laminate according to claim 1, wherein an average particle diameter of the light diffusing fine particles by a centrifugal sedimentation light transmission method is 0.1 to 20 μm.   The laminate according to claim 1, wherein the adhesive component contains a (meth) acrylic acid ester polymer.   The laminate according to claim 3, wherein the (meth) acrylic acid ester polymer is crosslinked by a crosslinking agent.   The laminate according to claim 3 or 4, wherein the content of the light diffusing fine particles is 0.01 to 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer.

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