KR102603519B1 - Laminate and touch panel - Google Patents

Abstract

[Problem] To provide a laminate having excellent blister resistance and whitening resistance under high durability conditions, which is a laminate having a polycarbonate plate with high moisture absorption ability and other layers through an adhesive layer.
[Solution] A laminate formed by laminating a first layer and a second layer through an adhesive layer, the weight ratio before and after the second layer is left in an 85°C/85% RH environment for 72 hours (the weight after the above-mentioned leave) / (weight before leaving) is a polycarbonate plate of 1.0010 to 1.0050, and the adhesive layer is a (meth)acrylic copolymer (A) which is a copolymer of a monomer component containing a polymerizable macro monomer and a crosslinkable functional group-containing monomer, and carbon number A laminate formed from an adhesive composition containing an isocyanate-based crosslinking agent (B) having two or more alkyleneoxy groups.

Description

Laminate and touch panel

The present invention relates to a laminate and a touch panel.

Recently, the market for smartphones and tablet-type computers has been expanding, and these are usually equipped with touch panels. A touch panel is a laminate of various materials, and an adhesive is used to laminate various materials (see Patent Documents 1 and 2).

Polycarbonate is often used as a material for the support and cover member (surface support) of the touch panel. Polycarbonate contains moisture due to its manufacturing process, and when an adhesive sheet is attached to a polycarbonate board and subjected to a durability test (e.g., evaluation test for blister resistance and whitening resistance), foaming resulting from this moisture occurs. occurs.

In addition, the deployment of touch panels in automotive applications is expanding, but automotive applications require higher durability than general applications due to high temperatures and high humidity in the summer. However, conventional adhesives could not solve the high durability conditions (high temperature and high humidity conditions) assumed for automotive use.

Japanese Patent Application No. 2013-018227 International Publication No. 2016/052276

According to the present inventors' examination, in the case of using a polycarbonate board as the subject of application of the adhesive, the above-mentioned durability is not so much a problem when the moisture absorption capacity of the polycarbonate plate is low, but when the moisture absorption capacity of the polycarbonate plate is high. In this case, I found that the durability of the tactic was a big problem. The object of the present invention is to provide a laminate having excellent blister resistance and whitening resistance under high durability conditions, which is a laminate having a polycarbonate plate with high moisture absorption ability and other layers through an adhesive layer.

The present inventors conducted intensive studies to solve the above problems. As a result, it was discovered that a laminate having the following structure could solve the above problems, and the present invention was completed.

The present invention relates to, for example, the following [1] to [3].

[1] It is a laminate formed by laminating a first layer and a second layer through an adhesive layer, and the weight ratio before and after the second layer is left for 72 hours in an 85°C/85% RH environment (weight after the leave/ It is a polycarbonate plate with a weight before leaving) of 1.0010 to 1.0050, and the adhesive layer is a (meth)acrylic copolymer (A) which is a copolymer of a monomer component containing a polymerizable macro monomer and a crosslinkable functional group-containing monomer, and a carbon number of 2 A laminate formed from an adhesive composition containing the above isocyanate-based crosslinking agent (B) having an alkyleneoxy group.

[2] The above [1], wherein the (meth)acrylic copolymer (A) is a copolymer of monomer components containing 1 to 35% by mass of the polymerizable macromonomer and 0.5 to 20% by mass of the crosslinkable functional group-containing monomer. The laminate described in .

[3] A touch panel comprising the laminate according to [1] or [2] above.

According to the present invention, it is possible to provide a laminate having excellent blister resistance and whitening resistance under high durability conditions, which is a laminate having a polycarbonate plate with high moisture absorption ability and other layers through an adhesive layer.

1 is a cross-sectional view schematically showing an example of a touch panel unit in a resistive touch panel.
Fig. 2 is a cross-sectional view schematically showing an example of a touch panel unit in a capacitive touch panel.

(Form for carrying out the invention)

Hereinafter, modes for carrying out the present invention will be described in detail. In addition, in this specification, acrylic and methacryl are collectively referred to as "(meth)acrylic".

[Laminate]

In the laminate of the present invention, the first layer and the second layer are laminated through an adhesive layer. For example, the laminate of the present invention has a first layer, an adhesive layer, and a second layer in this order in the lamination direction.

The second layer is a polycarbonate plate with a weight ratio (weight after leaving/weight before leaving) of 1.0010 to 1.0050 before and after being left in an 85°C/85% RH environment for 72 hours. The adhesive layer contains a (meth)acrylic copolymer (A), which is a copolymer of monomer components containing a polymerizable macro monomer and a crosslinkable functional group-containing monomer, and an isocyanate-based crosslinking agent (B) having an alkyleneoxy group having 2 or more carbon atoms. It is formed from an adhesive composition.

<First floor>

As the first layer, for example, polyester (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene, polypropylene, poly Plastic films such as vinyl chloride, polyurethane, polyamide, acrylonitrile-butadiene-styrene copolymer, and ethylene-vinyl acetate copolymer; glass plate; A transparent conductive film described later; Examples include a plastic film with a transparent conductive film and a glass plate with a transparent conductive film.

The first layer is, for example, a layer that constitutes a touch panel unit described later.

The first layer is, for example, an optical film containing a polarizing plate. As a polarizing plate, a polarizer in which an appropriate transparent protective film is bonded to one or both sides is generally used. Examples of the transparent protective film include cellulose resin, cyclic polyolefin resin, (meth)acrylic resin, phenylmaleimide resin, and polycarbonate resin.

The first layer may be, for example, the above-mentioned base material derived from a pressure-sensitive adhesive sheet having a base material and an adhesive layer formed on one side of the base material. As a base material, the plastic film mentioned above can be mentioned. The pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition containing a (meth)acrylic copolymer (A) and an isocyanate-based crosslinking agent (B) having an alkyleneoxy group of 2 or more carbon atoms.

The thickness of the first layer is usually 5 to 1000 μm, preferably 10 to 500 μm.

<2nd floor>

The second layer is a polycarbonate board (hereinafter also referred to as “PC board”).

The weight ratio (weight after leaving/weight before leaving) of the PC board before and after being left in an 85°C/85% RH environment for 72 hours is 1.0010 to 1.0050, preferably 1.0015 to 1.0040, more preferably. is 1.0018∼1.0035. The weight ratio is a value defined and measured as follows. The PC board is left in a dry environment at 85°C for 72 hours, and its weight (weight 1: weight before leaving in a moist heat environment) is measured immediately after being taken out from the environment. Thereafter, the PC board is left in an 85°C/85% RH environment for 72 hours, and its weight (weight 2: weight after being left in a moist heat environment) is measured immediately after being taken out from the environment. From the weights 1 and 2 before and after introduction into this 85°C/85% RH environment, the weight ratio (weight 2/weight 1) is calculated.

In a conventional laminate, if the moisture absorption capacity of the PC board is low and the weight ratio is less than 1.0010, there is no problem in the durability test. However, if the moisture absorption ability of the PC board is high and the weight ratio is 1.0010 or more, blisters or whitening may occur in the durability test. There are cases. In the laminate of the present invention, even if the weight ratio of the PC board is 1.0010 or more, the blister resistance and whitening resistance are excellent. This is because the adhesive layer constituting the laminate of the present invention easily absorbs moisture and has sufficient high elasticity to suppress the occurrence of the blister phenomenon.

The density of the PC board is usually 1.000 to 1.120 g/ _cm ³ , preferably 1.050 to 1.110 g/cm ³ , and more preferably 1.080 to 1.100 g/cm ³ . In a conventional laminate, if the density of the PC board exceeds 1.120 g/cm ³ there is no problem in the durability test, but if the density is 1.120 g/cm ³ or less, blisters or whitening may occur in the durability test. In the laminate of the present invention, even if the density of the PC board is 1.120 g/cm ³ or less, the occurrence of blisters, whitening, etc. is suppressed in the durability test.

The second layer is, for example, a PC board as a transparent member constituting a touch panel unit described later. Additionally, the second layer is, for example, a PC board to which an optical film is attached through the adhesive layer.

The thickness of the PC board is usually 0.3 to 3 mm, preferably 0.5 to 2 mm.

<Adhesive layer>

The pressure-sensitive adhesive layer contains a (meth)acrylic copolymer (A) described below and an isocyanate-based crosslinking agent (B) having an alkyleneoxy group having 2 or more carbon atoms (hereinafter also simply referred to as “isocyanate-based crosslinking agent (B)”). It is formed from an adhesive composition.

By using the pressure-sensitive adhesive composition, it is possible to form a pressure-sensitive adhesive layer that has blister resistance and whitening resistance even under high durability conditions and has good adhesion to the first and second layers.

《(meth)acrylic copolymer (A)》

The (meth)acrylic copolymer (A) is a copolymer of a monomer component containing a polymerizable macro monomer and a crosslinkable functional group-containing monomer, and is obtained by copolymerizing the monomer components. The monomer component is usually a monomer containing a polymerizable unsaturated group.

<Polymerizable macro monomer>

The monomer component includes polymerizable macro monomers.

Polymerizable macromonomers have polymerizable unsaturated groups. Examples of the polymerizable unsaturated group include an ethylenically unsaturated double bond. For example, it is a polymer having a (meth)acryloyl group at the terminal.

During polymerization of the monomer component, the polymerizable macromonomer, for example, undergoes a radical polymerization reaction with other monomers forming the (meth)acrylic copolymer (A) in the polymerizable unsaturated group, thereby forming the (meth)acrylic copolymer (A). A) It is accepted into. When viewed as a (meth)acrylic copolymer (A), side chains based on polymerizable macromonomers are formed. This side chain prevents the molecules of the (meth)acrylic copolymer (A) from crowding together.

The polymerizable macromonomer is, for example, a polymer whose weight average molecular weight (Mw) is usually 5 million to 100,000, preferably 10,000 to 50,000. In this specification, the weight average molecular weight (Mw) of a polymerizable macromonomer is the weight average molecular weight measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

The polymerizable macromonomer preferably has a glass transition temperature (Tg) of 50 to 180°C, more preferably 80 to 150°C. For this reason, the (meth)acrylic copolymer (A) is hard from the viewpoint of Tg, and the resulting pressure-sensitive adhesive layer has excellent blister resistance. The Tg of the polymerizable macromonomer may be a value determined by Fox's formula, or when a commercial product is used, the value described in the catalog may be adopted.

Examples of monomers of the polymer chain (main chain) portion constituting the polymerizable macro monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, and tert. -Alkyl (meth)acrylates such as butyl (meth)acrylate are mentioned, and the alkyl group preferably has 1 to 20 carbon atoms, and also (meth)acrylonitrile; Styrene-based monomers such as styrene and α-methylstyrene can also be mentioned. The said monomer may be used individually by 1 type, or 2 or more types may be used.

Polymerizable macromonomers are preferably, for example, (meth)acrylic macromonomers, (meth)acrylonitrile-based macromonomers, and styrene-based macromonomers, and can be produced according to various known methods, for example It can be produced by the method described in paragraph [0039] of Japanese Patent Application Laid-Open No. 2013-018227.

As the polymerizable macromonomer, a commercially available product may be used, for example, a macromonomer whose main chain monomer is methyl methacrylate (product name: 45% AA-6 (AA-6S), AA-6; Toago Detergent), A macro monomer whose main chain is a copolymer of styrene/acrylonitrile (product name: AN-6S; Toago Detergent), a macro monomer whose main chain monomer is butylacrylate (product name: AB-6; Toago Detergent), These have a methacryloyl group at the terminal.

Polymerizable macromonomers may be used individually or in combination of two or more.

The amount of polymerizable macromonomers in the total monomer components is usually 1 to 35 mass%, preferably 2 to 33 mass%, and more preferably 5 to 30 mass%. Additionally, it is preferable that the amount of structural units derived from the polymerizable macromonomer is within the above range described in this paragraph among all structural units derived from monomers. When the polymerizable macromonomer amount is within the above range, blister resistance is excellent by suppressing expansion of foam at the interface between the first and second layers and the pressure-sensitive adhesive layer, and adhesion between these layers is also excellent. The amount of the structural unit can be calculated, for example, from the amount of monomer charged, and the same applies to other examples.

<Monomer containing crosslinkable functional group>

The monomer component includes a monomer containing a crosslinkable functional group.

The crosslinkable group is a functional group capable of crosslinking reaction with the isocyanate-based crosslinking agent (B), and examples include hydroxyl groups and acid groups. Examples of crosslinkable functional group-containing monomers include hydroxyl group-containing monomers and acidic group-containing monomers, and among these, hydroxyl group-containing monomers are preferable.

Examples of the hydroxyl group-containing monomer include hydroxyl group-containing (meth)acrylate, specifically, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxide. Hydroxyalkyl (meth)acrylates such as hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate can be mentioned.

Examples of the acid group include a carboxyl group, an acid anhydride group, a phosphoric acid group, and a sulfuric acid group. Examples of carboxyl group-containing monomers include β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, mono(meth)acryloyloxyethyl succinic acid, and ω-carboxypolycaprolactone mono(meth)acrylic acid. carboxyl group-containing (meth)acrylates such as latex; Examples include (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid. Examples of acid group-containing monomers other than carboxyl groups include acid anhydride group-containing monomers such as phthalic anhydride and maleic anhydride; Phosphate group-containing monomers such as (meth)acrylic monomers having a phosphate group in the side chain; Sulfuric acid group-containing monomers such as (meth)acrylic monomers having a sulfuric acid group in the side chain can be mentioned.

Additionally, in one embodiment, when corrosion of the layer in contact with the adhesive layer due to acid radicals is a problem, for example, when the adhesive layer formed from the adhesive composition is in direct contact with wiring made of metal or metal oxide. , it is preferable not to use an acid group-containing monomer substantially, that is, it is preferable that the (meth)acrylic copolymer (A) does not substantially have the acid group. Substantially having no acid group means, for example, that the acid value of the (meth)acrylic copolymer (A) is 0.5 mgKOH/g or less.

Among monomers containing a crosslinkable functional group, monomers containing a hydroxyl group are preferable. At least a part of the hydroxyl group derived from the hydroxyl group-containing monomer becomes a crosslinking point in the (meth)acrylic copolymer (A), and can form a crosslinked structure by, for example, reacting with the isocyanate group of the isocyanate-based crosslinking agent (B).

The crosslinkable functional group-containing monomer may be used individually or in combination of two or more.

The amount of crosslinkable functional group-containing monomer in the total monomer components is usually 0.5 to 20 mass%, preferably 1.5 to 15 mass%, and more preferably 2 to 13 mass%. In addition, it is preferable that the amount of structural units derived from the crosslinkable functional group-containing monomer is within the above range described in this paragraph among all structural units derived from the monomer. In this aspect, the crosslinked structure of the (meth)acrylic copolymer (A) is appropriately formed, and an adhesive layer with appropriate flexibility is obtained.

<Alkoxyalkyl (meth)acrylate>

The monomer component preferably includes alkoxyalkyl (meth)acrylate. By using a copolymer containing a structural unit derived from alkoxyalkyl (meth)acrylate, moisture absorbed in the adhesive layer in a high humidity environment can be dispersed within the adhesive layer, and blister resistance and whitening resistance can be improved.

The carbon number of the alkoxyalkyl group in alkoxyalkyl (meth)acrylate is usually 2 to 18, preferably 2 to 12, and more preferably 2 to 10. Examples of alkoxyalkyl (meth)acrylate include methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxypropyl ( Meta)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate.

Alkoxyalkyl (meth)acrylates may be used individually or in combination of two or more.

The amount of alkoxyalkyl (meth)acrylate in all monomer components is usually 50 to 98 mass%, preferably 55 to 95 mass%, and more preferably 60 to 90 mass%. Moreover, it is preferable that the amount of structural units derived from alkoxyalkyl (meth)acrylate is within the above range described in this paragraph among all structural units derived from monomers. If the amount of alkoxyalkyl (meth)acrylate is more than the above lower limit, the alkoxy group has hydrophilicity, and thus the blister resistance and whitening resistance increase by dispersing moisture that has entered the adhesive layer; Also, if it is below the above upper limit, the adhesion between the first and second layers and the adhesive layer is excellent.

<Other monomers>

The monomer component may further contain monomers other than the monomer. Monomers other than the above monomers include, for example, alkyl (meth)acrylates, (meth)acrylates containing alicyclic hydrocarbon groups or aromatic hydrocarbon groups, alkoxypolyalkylene glycol mono (meth)acrylates, styrene-based monomers, Examples include amide group-containing monomers, amino group-containing monomers, cyano group-containing monomers, and vinyl acetate.

The alkyl group in the alkyl (meth)acrylate preferably has 1 to 20 carbon atoms. Examples of alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, and n-butyl (meth)acrylate. Acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate Rate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, iso-nonyl (meth)acrylate, decyl (meth)acrylate, iso-decyl (meth)acrylate Rate, undeca(meth)acrylate, lauryl(meth)acrylate, oleyl(meth)acrylate, n-stearyl(meth)acrylate, iso-stearyl(meth)acrylate, dideca(meth)acrylate ) Acrylates can be mentioned.

Examples of (meth)acrylates containing an alicyclic hydrocarbon group or an aromatic hydrocarbon group include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, and benzyl (meth)acrylate. Acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate can be mentioned.

Examples of alkoxypolyalkylene glycol mono(meth)acrylate include methoxydiethylene glycol mono(meth)acrylate, methoxydipropylene glycol mono(meth)acrylate, and ethoxytriethylene glycol mono(meth)acrylate. , ethoxydiethylene glycol mono(meth)acrylate, and methoxytriethylene glycol mono(meth)acrylate.

Examples of styrene-based monomers include styrene; Alkyl styrene, such as methyl styrene, dimethyl styrene, trimethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, and octyl styrene; Halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, and dibromostyrene; Functionalized styrene such as nitrostyrene, acetylstyrene, and methoxystyrene can be mentioned.

Examples of amide group-containing monomers include (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, and N-hexyl (meth)acrylamide. N,N-dialkyl (meth)acrylamides such as N-alkyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, and N,N-diethyl (meth)acrylamide; and nitrogen-based heterocyclic-containing monomers such as N-vinylpyrrolidone, N-vinylcaprolactam, and (meth)acryloylmorpholine.

Examples of amino group-containing monomers include N,N-dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate. can be mentioned.

Examples of cyano group-containing monomers include cyano (meth)acrylate and (meth)acrylonitrile.

Other monomers may be used individually or in combination of two or more.

It is preferable that the amount of other monomers in the total monomer components is 35% by mass or less. Furthermore, it is preferable that the amount of structural units derived from other monomers is 35% by mass or less out of the total structural units derived from monomers.

<Composition and manufacturing method of (meth)acrylic copolymer (A)>

The weight average molecular weight (Mw) of the (meth)acrylic copolymer (A) measured by gel permeation chromatography (GPC) is usually 100,000 to 800,000, preferably 150,000 to 600,000, more preferably. is 200,000 to 500,000. With this aspect, an adhesive layer excellent in high temperature durability can be obtained.

The molecular weight distribution (Mw/Mn; Mn is number average molecular weight) of the (meth)acrylic copolymer (A) is usually 1.5 to 15, preferably 2 to 13, and more preferably 5 to 12. With this aspect, an adhesive layer excellent in high temperature durability can be obtained.

Mw and Mw/Mn can be measured, for example, by the method described in the Examples.

The glass transition temperature (Tg) of the (meth)acrylic copolymer (A) determined by the so-called Fox equation is usually -80 to 0°C, preferably -70 to -10°C. With this aspect, an adhesive layer having excellent adhesive strength at room temperature (25°C) can be obtained. Additionally, if Tg becomes too high, the affinity of the adhesive layer for the first and second layers may deteriorate, and defects such as foaming or lifting may easily occur.

The glass transition temperature (Tg) of the homopolymer formed from each monomer in Fox's equation can be, for example, the value described in Polymer Handbook Fourth Edition (Wiley-Interscience 2003).

The total content of the (meth)acrylic copolymer (A) and the isocyanate-based crosslinking agent (B) in the adhesive composition is usually 70% by mass or more, preferably 75% by mass or more, more preferably 75% by mass or more, based on 100% by mass of solid content of the adhesive composition. In other words, it is 80% by mass or more. Additionally, solid content is a component that removes solvent.

The (meth)acrylic copolymer (A) can be produced by a known method, but is preferably produced by solution polymerization. Specifically, a monomer component and a polymerization solvent are charged into a reaction vessel, a polymerization initiator is added in an inert gas atmosphere such as nitrogen gas, and the reaction temperature is heated to about 50 to 90° C. and allowed to react for 2 to 20 hours. Additionally, during the polymerization reaction, a polymerization initiator, chain transfer agent, monomer component, and polymerization solvent may be additionally added as appropriate.

Examples of the polymerization initiator include common organic polymerization initiators, and specifically, peroxides such as benzoyl peroxide and lauroyl peroxide, and azo compounds such as 2,2'-azobisisobutyronitrile. You can. Among these, azo compounds are preferable.

Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis. (2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azo Bis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis (2-amidinopropane)dihydrochloride, 2,2'-azobis(N, N'-dimethyleneisobutylamidine), 2,2'-azobis[2-methyl-N- (2- Hydroxyethyl)-propionamide], 2,2'-azobis(isobutylamide) dihydrate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2- cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]. there is.

Polymerization initiators may be used individually or in combination of two or more.

The amount of polymerization initiator used is usually 0.01 to 5 parts by mass per 100 parts by mass of the monomer component. In this aspect, the Mw of the (meth)acrylic copolymer (A) can be adjusted within an appropriate range.

In solution polymerization, examples of polymerization solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; Aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; Alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, and diphenyl ether; Halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; Amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; Nitriles such as acetonitrile and benzonitrile; Sulfoxides such as dimethyl sulfoxide and sulfolane can be mentioned.

One type of polymerization solvent may be used individually, or two or more types may be used.

《Isocyanate-based crosslinking agent (B)》

The isocyanate-based crosslinking agent (B) is a component that can cause a crosslinking reaction with the (meth)acrylic copolymer (A). The isocyanate-based crosslinking agent (B) is, for example, an isocyanate compound having two or more isocyanate (-N=C=O) groups in one molecule. The number of isocyanate groups in one molecule is preferably 2 to 8, more preferably 2 to 6.

The isocyanate-based crosslinking agent (B) has an alkyleneoxy group having 2 or more carbon atoms. Here, the “alkyleneoxy group” is a divalent group represented by -R-O-, and R is an alkanediyl group having 2 or more carbon atoms. The upper limit of the number of carbon atoms of the alkyleneoxy group is usually 10, preferably 8.

Also, for example, the reaction product of tolylene diisocyanate and trimethylolpropane has -CH ₂ -O-, but does not have an alkyleneoxy group (divalent group) having 2 or more carbon atoms.

The alkyleneoxy group having 2 or more carbon atoms may be included in the crosslinking agent (B) as part of the ring-opening structure of the lactone, as in formula (3) described later, or as in formula (4) described later. For example, an isocyanate-based crosslinking agent having a lactone-modified group and/or an alkylene oxide-modified group is preferred, and a structure in which two or more molecules of a polyfunctional isocyanate compound are urethane-bonded to a compound obtained by lactone-modifying and/or alkylene-oxide-modifying a polyhydric alcohol. A compound having a may be mentioned. In addition, the lactone modified group is the ring-opened structure of lactone, and the alkylene oxide modified group is the ring-opened structure of alkylene oxide.

Since the isocyanate-based crosslinking agent (B) has an alkyleneoxy group having 2 or more carbon atoms, the distance between crosslinking points becomes longer. In general, when the polymer component is hardened to increase durability, the affinity of the adhesive layer for the substrate or adherend tends to decrease, but by using the cross-linking agent (B) with a long distance between cross-linking points, the adhesive layer has flexibility. This improves affinity, thereby creating an adhesive layer that is both hard and flexible. That is, in the present invention, the durability of the adhesive layer can be increased by hardening the (meth)acrylic copolymer (A), and by using the crosslinking agent (B) with a long distance between crosslinking points, the copolymer (A) It is possible to prevent a decrease in affinity for the first and second layers accompanying the hardness of the layer. For this reason, even when a polycarbonate plate with high moisture absorption ability is used, a laminate with good durability (blister resistance) is obtained.

Examples of polyhydric alcohols include trimethyl or higher alcohols such as trimethylolpropane, glycerin, and pentaerythritol. The number of hydroxyl groups in the polyhydric alcohol is preferably 3 to 8.

Examples of the lactone include cyclic esters with 3 to 11 carbon atoms such as β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone, and examples of alkylene oxide include, Examples include alkylene oxides having 2 to 10 carbon atoms, such as ethylene oxide, propylene oxide, and butylene oxide.

Examples of polyfunctional isocyanate compounds include aliphatic diisocyanate and cycloaliphatic diisocyanate, and their isocyanurate or biuret forms. Examples of aliphatic diisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, and 3-methyl-1,5-pentanedi. and aliphatic diisocyanates having 4 to 30 carbon atoms, such as isocyanate and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate. Examples of alicyclic diisocyanate include isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylidene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethyl. and alicyclic diisocyanates having 7 to 30 carbon atoms, such as xylidene diisocyanate.

As the isocyanate-based crosslinking agent (B), a crosslinking agent having a skeleton ((-O-CH ₂ -) ₃ -C-CH ₂ CH ₃ ) derived from trimethylolpropane is preferred, and is represented by formula (1) or formula (2) A cross-linking agent is more preferable.

In formulas (1) and (2), R ^1A , R ^1B and R ^1C are each independently a group containing a group represented by formula (3) and/or a group represented by formula (4), and R ^2A , R ^2B , R ^2C , R ^3A , R ^3B , R ^3C , R ^3D , R ^3E and R ^3F are each independently an alkanediyl group having 4 to 10 carbon atoms, such as a 1,6-hexanediyl group.

In formula (3), R ¹¹ is an alkanediyl group having 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms, more preferably linear, and m is an integer of 1 to 10, preferably an integer of 1 to 6. am. In formula (4), R ²¹ is an alkanediyl group having 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms, and n is an integer of 1 to 10, preferably 1 to 6.

The group containing the group represented by the formula (3) and/or the group represented by the formula (4) is, for example, the group represented by the formula (3), the group represented by the formula (4), and the group represented by the formula (3). It is a group consisting of a group represented by the group and a group represented by the formula (4).

From the viewpoint of further increasing the elasticity of the adhesive layer, the molecular weight of the isocyanate-based crosslinking agent (B) is preferably 500 to 10,000, and more preferably 1,500 to 7,000.

As the isocyanate-based crosslinking agent (B), a commercially available crosslinking agent can be used. Examples include E402-80B (manufactured by Asahi Kasei), E405-70B (manufactured by Asahi Kasei), and MFA-75B (manufactured by Asahi Kasei).

The isocyanate-based crosslinking agent (B) may be used individually or in combination of two or more.

The content of the isocyanate-based crosslinking agent (B) in the adhesive composition is usually 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, more preferably 0.1 to 0.1 parts by mass, based on 100 parts by mass of the (meth)acrylic copolymer (A). It is 2.5 parts by mass. With this aspect, the cross-linked structure is formed sufficiently and appropriately, and thus a pressure-sensitive adhesive layer with high cohesion and excellent durability can be obtained.

《Other cross-linking agents》

In addition to the isocyanate-based crosslinking agent (B), the adhesive composition may contain other crosslinking agents such as a metal chelate crosslinking agent and/or an epoxy-based crosslinking agent.

In the adhesive composition, the content of the other crosslinking agent is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, based on 100 parts by mass of the (meth)acrylic copolymer (A). With this aspect, an adhesive can be obtained in which the crosslinked structure is sufficiently and appropriately formed, has high cohesion, has an excellent balance of adhesive properties, and is excellent in durability.

As a metal chelate crosslinking agent, for example, polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium, and alkoxides, acetylacetone, and ethyl acetoacetate are used. Compounds for: Specifically, aluminum isopropylate, aluminum secondary butyrate, aluminum ethyl acetoacetate diisopropylate, aluminum trisethylacetoacetate, and aluminum trisacetylacetonate.

As an epoxy-based crosslinking agent, an epoxy compound having two or more epoxy groups per molecule is usually used. For example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl) Cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, N,N,N',N'-tetraglycidylaminophenylmethane, triglycidylisocyanurate , m-N,N-diglycidylaminophenylglycidyl ether, N,N-diglycidyltoluidine, and N,N-diglycidylaniline.

《Plasticizer》

In one embodiment, the adhesive composition preferably further contains a plasticizer.

Plasticizers include, for example, phthalic acid ester compounds, adipic acid ester compounds, trimellitic acid ester compounds, sebacic acid ester compounds, citric acid ester compounds, phosphoric acid ester compounds, polyester compounds, and palmitate. Acid-based compounds and stearic acid-based compounds may be mentioned, and specifically, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, dibutyl phthalate, dioctyl adipate, diisononyl adipate, and trimellitic acid. Octyl, tricresyl phosphate, low molecular weight polyester, isopropyl palmitate, octyl palmitate, methyl stearate, butyl stearate, and octyl stearate. Among these, palmitic acid-based compounds and/or stearic acid-based compounds are preferable from the viewpoint of compatibility with the (meth)acrylic copolymer (A).

Plasticizers may be used individually or in combination of two or more.

The content of the plasticizer in the adhesive composition is usually 0.01 to 3 parts by mass, preferably 0.05 to 1 part by mass, based on 100 parts by mass of the (meth)acrylic copolymer (A). In this aspect, the affinity for the adherend (PC board) is excellent.

"additive"

In addition to the above components, the adhesive composition contains, to the extent that the effect of the present invention is not impaired, a silane coupling agent, an antistatic agent, an ultraviolet absorber, an antioxidant, a tackifying resin, an adhesion regulator (e.g., an organopolysiloxane compound), an antifoamer, and a filler. , a stabilizer, a softener, and a wettability regulator may be contained.

《Organic solvent》

The adhesive composition may contain an organic solvent in order to improve its handleability.

Examples of the organic solvent include the polymerization solvent described in the description of the method for producing the (meth)acrylic copolymer (A). For example, a pressure-sensitive adhesive composition can be prepared by mixing a solution containing a (meth)acrylic copolymer (A) and a polymerization solvent with an isocyanate-based crosslinking agent (B). In the adhesive composition, the content of the organic solvent is usually 0 to 90% by mass, and preferably 10 to 80% by mass.

《Formation of adhesive layer》

The pressure-sensitive adhesive layer can be obtained by crosslinking the pressure-sensitive adhesive composition, specifically, by crosslinking the (meth)acrylic copolymer (A) with an isocyanate-based crosslinking agent (B).

The conditions for forming the adhesive layer are, for example, as follows. The pressure-sensitive adhesive composition is applied on the first separator and dried at usually 60 to 120°C, preferably 70 to 110°C, usually for 1 to 5 minutes, preferably 2 to 4 minutes, to form a coating film. Subsequently, a second separator is bonded onto the coating film. Subsequently, the obtained laminate is usually stored for 1 day or more, preferably 3 to 10 days, usually at 5 to 60°C, preferably 15 to 40°C, usually at 30 to 70% RH, preferably at 40 to 70% RH. Curing (maturation) in an environment of % RH. If crosslinking is performed under the above-mentioned aging conditions, a crosslinked product can be formed efficiently.

The separator is preferably a long substrate with one or both sides peeled. Examples of the separator include polyester (e.g., polyethylene terephthalate, polyethylene naphthalate), polycarbonate, polymethyl methacrylate, and polyethylene. plastics such as polypropylene, polyvinyl chloride, polyurethane, polyamide, and ethylene-vinyl acetate copolymer; Non-woven; You can lift paper.

The thickness of the adhesive layer is usually 3 to 1000 μm, preferably 5 to 500 μm.

The gel fraction of the adhesive layer is preferably 40 to 95 mass%, more preferably 50 to 90 mass%, and even more preferably 60 to 85 mass%. This aspect is preferable from the viewpoint of improving cohesion and adhesion.

The gel fraction can be measured as follows. Approximately 0.1 g of adhesive was collected from the adhesive layer into a sample bottle, 30 mL of ethyl acetate was added and shaken for 4 hours, the contents of the sample bottle were filtered through a 200 mesh stainless steel wire mesh, and the residue on the wire mesh was filtered at 100°C. Dry for 2 hours and measure the dry mass. The gel fraction of the adhesive layer is determined by the following equation.

Gel fraction (mass %) = (dry mass/adhesive sampled mass) x 100 (%)

The adhesive layer is disposed to bond the first layer and the second layer, for example, bonding transparent members described later (that is, the first and second layers are transparent members), or a transparent member described later It is arranged to bond a transparent conductive film (that is, the first layer is a transparent conductive film and the second layer is a transparent member).

<Manufacture of laminate>

The laminate of the present invention can be obtained by bonding the first layer and the second layer through an adhesive layer obtained from the above adhesive composition. For example, after attaching the surface of the adhesive layer to the surface of the first layer (or second layer), the other surface (back side) of the adhesive layer is attached to the surface of the second layer (or first layer). , the first layer and the second layer can be bonded together with an adhesive layer.

Additionally, using a pressure-sensitive adhesive sheet having a base material as a first layer and an adhesive layer obtained from the pressure-sensitive adhesive composition formed on one side of the base material, the adhesive layer is bonded to a polycarbonate board as a second layer, thereby forming a lamination process according to the present invention. You can get a sieve.

[Touch panel usage]

For example, touch panels are mounted on vehicle-mounted devices such as car navigation devices as well as smartphones and tablet-type computers. The touch panel includes a touch panel unit.

Examples of the touch panel unit include a resistive touch panel unit and a capacitive touch panel unit. These are laminates of various materials, and some or all of the units are the laminate of the present invention. can be used.

Since the touch panel unit is disposed on the outermost surface of the screen, the adhesive used is required to have high transparency and also needs to have characteristics such as high heat resistance and heat-and-moisture resistance.

The touch panel unit has, for example, a surface support, an adhesive layer, and a transparent conductive film made of metal or metal oxide in this order in the stacking direction, or a surface support, an adhesive layer, an electrode support, and a metal. Alternatively, transparent conductive films made of metal oxides are arranged in this order in the stacking direction. Examples of metals and metal oxides include indium tin oxide (ITO), antimony tin oxide (ATO), and tin oxide.

<Resistive touch panel>

As shown in FIG. 1, the resistive touch panel unit 10-1 includes an upper laminate 11-1 and a lower laminate 13 so that a gap 34 is formed by an adhesive 30. It is formed by joining -1), and a spacer 32 is disposed within the gap 34 to effectively secure the gap width.

Transparent conductive films 27-1 and 27-2 made of metal or metal oxide are disposed on the upper laminate 11-1 and the lower laminate 13-1, respectively, facing the gap 34. there is. The transparent conductive films 27-1 and 27-2 are usually formed on the surfaces of the upper electrode support 25-1 and the lower electrode support 25-2 made of transparent members.

A surface support 21-1 is disposed on the outermost surface of the upper laminate 11-1, and the surface support 21-1 is usually a transparent member. At the deepest part of the lower laminate 13-1, a deep surface support 21-2 is disposed so as to face the surface of the flat panel display (FPD), and the surface support 21-2 is usually a transparent member. . An adhesive layer 23-1 is disposed to adhere the surface support 21-1 and the upper electrode support 25-1. An adhesive layer 23-2 is disposed to adhere the deep surface support 21-2 and the lower electrode support 25-2.

Examples of transparent members include transparent plastic films such as polyester (eg, polyethylene terephthalate, polyethylene naphthalate), polycarbonate, and polymethyl methacrylate; You can lift a glass plate. This also applies to the capacitance method described below.

The laminate of the present invention can be used as a laminate of the surface support (21-1), the adhesive layer (23-1), and the upper electrode support (25-1). In this case, the adhesive layer 23-1 is formed of the above-described adhesive composition, and at least one of the surface support 21-1 and the upper electrode support 25-1 is a polycarbonate plate with the weight ratio of 1.0010 to 1.0050. am.

Additionally, the laminate of the present invention can be used as a laminate of the deep surface support 21-2, the adhesive layer 23-2, and the lower electrode support 25-2. In this case, the adhesive layer 23-2 is formed of the above-described adhesive composition, and at least one of the core surface support 21-2 and the lower electrode support 25-2 is polyester with the weight ratio of 1.0010 to 1.0050. It is a carbonate board.

A circuit is formed in the transparent conductive films 27-1 and 27-2, and by applying pressure with a finger or the like from above the surface support 21-1, the gap 34 in the area where the pressure is applied disappears, making the transparent conductive film 27-1 and 27-2 transparent. The conductive films 27-1 and 27-2 come into contact and conduct electricity, allowing the pressurized portion to be detected.

<Capacitive touch panel>

As shown in FIG. 2, the capacitive touch panel unit 10-2 generally has an upper laminated body 15-1 and a lower body with a central support 60 made of a transparent member sandwiched therebetween. In many cases, it has a structure in which the laminate 15-2 is arranged.

In the upper laminate 15-1, a transparent conductive film 57-1 is disposed in contact with the central support 60, and a surface support 51-1 made of a transparent member is disposed on the outermost surface. An adhesive layer 53-1 is disposed to adhere the transparent conductive film 57-1 and the surface support 51-1, and the adhesive layer 53-1 is in direct contact with the transparent conductive film 57-1. I'm doing it.

The laminate of the present invention can be used as the upper laminate 15-1. In this case, the adhesive layer 53-1 is formed of the above-described adhesive composition, the transparent conductive film 57-1 is the first layer, and the surface support 51-1 is polyester having the weight ratio of 1.0010 to 1.0050. It is a carbonate board (second layer).

In the lower laminate 15-2, a transparent conductive film 57-2 is disposed in contact with the central support 60, and a surface support 51-2 made of a transparent member is disposed at the deepest part. An adhesive layer 53-2 is disposed to adhere the transparent conductive film 57-2 to the deepest surface support 51-2, and the adhesive layer 53-2 is connected to the transparent conductive film 57-2. is in direct contact with.

The laminate of the present invention can be used as the upper laminate 15-2. In this case, the adhesive layer 53-2 is formed of the above-described adhesive composition, the transparent conductive film 57-2 is the first layer, and the deepest surface support 51-2 has the weight ratio of 1.0010 to 1.0010. It is a 1.0050 polycarbonate board (second layer).

In the capacitive touch panel unit 10-2, the deepest surface support 51-2 is arranged to face the flat panel display.

The transparent conductive films 57-1 and 57-2 form a circuit. In a capacitive touch panel, the change in electrostatic capacitance of a contact portion caused by a finger touching the surface of the touch panel unit 10-2 is read, and the contact position can be detected.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In descriptions such as the examples below, unless otherwise specified, “part” refers to “part by mass.”

Each measured value in the examples was obtained by the following method.

[Weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn)]

For the (meth)acrylic copolymer, Mw and Mw/Mn in terms of standard polystyrene were determined by gel permeation chromatography (GPC) under the following conditions.

·Measurement device: HLC-8120GPC (Tosoh)

·GPC column composition: 5 columns as follows (all made by Tosoh)

(1) TSK-GEL HXL-H (guard column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

·Sample concentration: diluted with tetrahydrofuran to 1.0 mg/cm ³

·Mobile phase solvent: tetrahydrofuran

·Flow rate: 1.0cm ³ /min

·Column temperature: 40℃

[Glass transition temperature (Tg)]

The Tg of the (meth)acrylic copolymer was obtained using Fox's equation.

[Synthesis Example 1]

In a reaction device equipped with a stirrer, reflux condenser, thermometer, and nitrogen introduction tube, 80 parts of 2-methoxyethyl acrylate (MEA), 10 parts of 2-hydroxyethyl acrylate (HEA), and methyl methacrylate-based macromonomer 10 parts of (AA-6), 50 parts of methyl ethyl ketone, and 80 parts of ethyl acetate were charged as solvents, and the temperature was raised to 75°C while introducing nitrogen gas. Next, 0.1 part of 2,2'-azobisisobutyronitrile was added, and a polymerization reaction was performed at 75°C for 4 hours in a nitrogen atmosphere. After completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution. The Mw of the obtained (meth)acrylic copolymer (A-1) was 360,000, Mw/Mn was 11, and Tg was -37°C.

[Synthesis Examples 2 to 8]

(Meth)acrylic copolymers (A-2) to (A-8) were synthesized in the same manner as in Synthesis Example 1 except that the composition of the monomer component was changed as shown in Table 1.

BA: n-butylacrylate

MEA: 2-methoxyethyl acrylate

HEA: 2-hydroxyethyl acrylate

AA: Acrylic acid

AA-6: Methyl methacrylate macromonomer (Toago detergent)

[Example 1]

Based on 100 parts of solid content of the (meth)acrylic copolymer (A-1), E405-70B, which is an isocyanate-based crosslinking agent: hexamethylene diisocyanate/butylene oxide and ε-caprolactone modified trimethylolpropane-adduct (Asahikaze) Now, 70% by mass of solid content) was added to the polymer solution in an amount such that the solid content was 0.9 parts, to obtain an adhesive composition.

The obtained pressure-sensitive adhesive composition was applied onto the peeled PET film (separator) so that the thickness after drying was 50 μm, dried at 90°C for 3 minutes to remove the solvent, and a coating film with a thickness of 50 μm was formed. A separator made of PET film, which has a weaker peeling force than the above separator, was bonded to the surface opposite to the surface of the coating film in contact with the PET film. Next, aging was performed for 7 days in an environment of 23°C and 65% RH to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with a thickness of 50 μm.

[evaluation]

<Gel fraction>

The gel fraction was measured as follows. Approximately 0.1 g of adhesive was collected from the adhesive layer of the adhesive sheet into a sample bottle, 30 mL of ethyl acetate was added and shaken for 4 hours, and the contents of the sample bottle were filtered through a 200 mesh stainless steel wire mesh, and the residue on the wire mesh was filtered. was dried at 100°C for 2 hours and the dry mass was measured. The gel fraction of the adhesive layer was determined by the following equation.

Gel fraction (mass %) = (dry mass/adhesive sampled mass) x 100 (%)

<Blister resistance test>

The separator on the side with weaker peeling force is peeled off from the adhesive sheet, and the exposed adhesive layer is attached to a PET film (first layer) with a thickness of 100 μm, cut to a size of 60 mm × 50 mm, and further peeled on the other side. The separated separator was peeled off, and the exposed adhesive layer was attached to a polycarbonate plate PC1600 (thickness 2.0 mm, weight ratio as shown below: 1.0021, density: 1.093 to 1.098 g/cm ³ : manufactured by Tachyron Cement) (second layer), followed by 50 A test plate was produced by keeping it in an autoclave adjusted to ℃ and 5 atm for 20 minutes. After the test panel was left under conditions of 85°C/85% RH for 72 hours, the blister resistance was evaluated based on the standards listed in Table 2.

Additionally, the weight ratio and density of the polycarbonate plate were measured as follows.

[Moisture absorption capacity (weight ratio)]

The polycarbonate plate described above was left in a dry environment at 85°C for 72 hours, and its weight (weight 1) was measured immediately after it was taken out from the environment. Thereafter, the polycarbonate plate was left in an 85°C/85% RH environment for 72 hours, and its weight (weight 2) was measured immediately after being taken out from the environment. From the weights 1 and 2 before and after introduction into this 85°C/85% RH environment, the weight ratio (weight 2/weight 1) was calculated.

[density]

It was calculated from the relationship between the volume and weight of the polycarbonate plate.

< Whitening resistance test>

The separator on the side with weaker peeling force is peeled off from the adhesive sheet, and the exposed adhesive layer is attached to a PET film (first layer) with a thickness of 100 μm, cut to a size of 60 mm × 50 mm, and further peeled on the other side. The separated separator was peeled off, and the exposed adhesive layer was adhered to a polycarbonate plate (PC1600: manufactured by Tachyron Siai Co., Ltd. (2nd layer)), and then kept in an autoclave adjusted to 50°C and 5 atm for 20 minutes to produce a test plate. . After the test panel was left under conditions of 85°C/85% RH for 72 hours, the presence or absence of whitening was visually confirmed based on the following criteria.

◎: No appearance defects such as whitening were observed at all.

○: Although a very slight appearance of whitening is observed, it is within the range of no problem in actual use.

×: Poor appearance of whitening was observed over a wide area.

[Examples 2 to 9, Comparative Examples 1 to 4, Reference Examples 1 and 2]

Except that the mixing composition of the adhesive composition was changed as shown in Table 3, the same procedure as in Example 1 was performed to prepare an adhesive composition and obtain an adhesive sheet. The amount of crosslinking agent is the amount per 100 parts of (meth)acrylic copolymer.

In addition, in Reference Example 1 and Reference Example 2, NF2000VU (thickness 1.5 mm, weight ratio: 1.0006, density: 1.124 to 1.132 g/cm ³ : manufactured by Mitsubishi Chemical Corporation) was used as the polycarbonate plate.

E405-70B: Hexamethylene diisocyanate/butylene oxide and ε-caprolactone modified trimethylolpropane-adduct (manufactured by Asahi Kasei, solid content 70% by mass)

MFA-75B: Isocyanurate/ε-caprolactone modified trimethylolpropane-adduct body of hexamethylene diisocyanate (manufactured by Asahi Kasei, solid content 70% by mass)

E402-80B: Hexamethylene diisocyanate/ε-caprolactone modified trimethylolpropane-adduct (manufactured by Asahi Kasei, solid content 90% by mass)

D-90: Burette sieve of hexamethylene diisocyanate

(made by Soken Kagaku, solid content 90% by mass)

L-45: Reaction product of tolylene diisocyanate and trimethylolpropane (made by Soken Chemical, solid content 45% by mass)

TD-75: Reaction product of xylidene diisocyanate and trimethylolpropane (made by Soken Chemical, solid content 75% by mass)

In Reference Examples 1 and 2, the PC board with the weight ratio of 1.0006 was used, and the blister resistance and whitening resistance were good. However, in Comparative Example 1, where the adhesive layer was formed with the same composition as Reference Example 2 and a PC board with the weight ratio of 1.0021 was used, the blister resistance was poor. In this way, when a PC board with a low moisture absorption capacity is used, the durability problem does not appear significantly, but when a PC board with a high moisture absorption capacity is used, a durability problem arises. This point has not been examined in the prior art, so it can be said to be a new problem.

On the other hand, in the examples, even when the PC board with the weight ratio of 1.0021 was used, the blister resistance and whitening resistance were good. In this way, in the present invention, when a PC board with high moisture absorption ability is used, a laminate with excellent durability can be provided.

10-1···Resistive film type touch panel unit,
10-2···Capacitive touch panel unit,
11-1...upper laminate, 13-1...lower laminate,
15-1···upper laminate, 15-2···lower laminate,
21-1...surface support, 21-2...deep surface support,
23-1, 23-2···Adhesive layer,
25-1···upper electrode support, 25-2···lower electrode support,
27-1···Transparent conductive film, 27-2···Transparent conductive film,
30···Adhesive, 32···Spacer, 34···Gap,
51-1, 51-2···Surface support,
53-1, 53-2···Adhesive layer,
57-1, 57-2... transparent conductive film,
60···Central support,

Claims (3)

A laminate formed by laminating a first layer and a second layer through an adhesive layer,
The second layer is a polycarbonate plate with a weight ratio (weight after leaving/weight before leaving) of 1.0010 to 1.0050 before and after being left in an 85°C/85% RH environment for 72 hours,
The adhesive layer contains a (meth)acrylic copolymer (A), which is a copolymer of a monomer component containing a polymerizable macro monomer and a crosslinkable functional group-containing monomer, and an isocyanate-based crosslinking agent (B) having an alkyleneoxy group having 2 or more carbon atoms. A laminate characterized in that it is formed from an adhesive composition. According to paragraph 1,
A laminate, characterized in that the (meth)acrylic copolymer (A) is a copolymer of a monomer component containing 1 to 35% by mass of the polymerizable macromonomer and 0.5 to 20% by mass of the crosslinkable functional group-containing monomer. A touch panel comprising the laminate according to claim 1 or 2.