TW201726849A - Pressure-sensitive adhesive sheet, process for producing laminate including pressure-sensitive adhesive layer, laminate including pressure-sensitive adhesive layer, image display device, and touch panel - Google Patents

Abstract

The purpose of the present invention is to provide a pressure-sensitive adhesive sheet which is excellent in terms of level difference conformability and blistering resistance and which has an excellent balance among pressure-sensitive adhesive properties (adhesive force, holding power), moist-heat resistance, and blistering resistance and has a high level of reliability. The pressure-sensitive adhesive sheet according the present invention includes a pressure-sensitive adhesive layer which comprises a crosslinked resin obtained from a functional-group-containing acrylic resin (A) and a crosslinking agent (B) and which further includes an ethylenic compound (C) having one ethylenically unsaturated group, the functional-group-containing acrylic resin (A) having a glass transition temperature of -35 DEG C or higher.

Description

Adhesive sheet, method for manufacturing laminated body with adhesive layer, laminated body with adhesive layer, image display device and touch panel

The present invention relates to an adhesive sheet, a method for producing a laminate having an adhesive layer, a laminate having an adhesive layer, an image display device, and a touch panel, and more particularly, it is excellent in step followability and resistance The adhesive sheet of the adhesive layer is also excellent in foaming property, and the adhesive property or the moist heat resistance is also well balanced.

In recent years, display devices such as liquid crystal displays (LCDs) or input devices such as touch panels used in combination with the above display devices have been widely used in various fields, and in such manufacturing, bonding opticals have been widely used. The purpose of the component is to use a transparent adhesive sheet.

For example, a transparent double-sided adhesive sheet is used for bonding a touch panel to various display devices or optical members (protective plates, etc.), but in this application, with the change in the composition of the touch panel in recent years, the requirements may be Follow a variety of steps (hereinafter referred to as the step follower.). In addition, when a plastic material such as a polycarbonate resin, an acrylic resin, or a (cyclic) olefin resin is used as a member constituting the touch panel, there is a gas or moisture generated by the member, so that the object (member) and the object (member) Foaming or peeling occurs between the adhesive layers, and it is required to suppress such blister resistance.

A means of imparting follow-up to the step, using a soft adhesive layer In the above method, the step adhesion followability is improved by making the adhesive layer soft, but it is liable to be deformed and twisted, and has a problem of poor durability.

In view of the above problems, as an adhesive sheet which is easy to ensure the step followability and which can prevent deformation and distortion of the film, for example, Patent Document 1 proposes an adhesive sheet which uses an acrylic resin as a heat bridge bridging agent. a bridging type, an adhesive sheet of a type which is hardened by irradiation of an active energy ray with an ethylenically unsaturated monomer, comprising: a monomer having at least one polymerizable unsaturated group, and a monomer having a base polymer; The adhesive layer of the semi-hardened adhesive is heated by an adhesive composition of a bridging agent, a polymerization initiator, and a solvent which reacts with the polymer.

Moreover, as means for imparting foaming resistance, a method of using a polymer containing an acid-based or nitrogen-based monomer as a polymerization component to improve the cohesive force of the adhesive layer in the adhesive layer has been proposed, or After the adhesive layer is attached to the object to be placed, it is heated at a high temperature or the like.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: International Publication No. 2013/061938

However, in recent years, as described above, it is required to follow various types of steps as the composition of the object (component) changes, and since the environment of use is also various, depending on the object to be used or the environment and use. Etc., still require more improvement for the adhesive. Regarding the adhesive sheet disclosed in Patent Document 1, although the step is followed It is excellent in properties, but it is not very good in blister resistance, and an adhesive sheet which is superior in step followability and blister resistance is required.

Therefore, in the context of the present invention, the present invention provides an adhesive sheet excellent in step followability and blister resistance, excellent in adhesion property (adhesion, retention), and moist heat resistance, and has a high level of reliability. The degree of adhesive sheet is the target.

The inventors of the present invention have found that an adhesive sheet having an adhesive layer bridging an acrylic resin with a bridging agent is more commonly used as an adhesive by using a glass transition temperature in view of the results of such intensive research. Acrylic resin having a high glass transition temperature of an acrylic resin, the obtained adhesive sheet exhibits excellent step followability when bonded to a substrate having irregularities, and does not adhere to a substrate when bonded to a plastic substrate. The present invention has been completed by foaming or peeling with the adhesive layer, and excellent foaming resistance, excellent adhesiveness (adhesion, retention), and moist heat resistance.

That is, the gist of the present invention is the following (1) to (9).

(1) An adhesive sheet comprising: a bridge comprising a functional group-containing acrylic resin (A) and a bridging agent (B); and an adhesion of an ethylenically unsaturated compound (C) having one ethylenically unsaturated group In the agent layer, the glass transition temperature of the functional group-containing acrylic resin (A) is -35 ° C or higher.

(2) The adhesive sheet according to the above (1), wherein the functional group-containing acrylic resin (A) is an alkyl methacrylate monomer having an alkyl group and having 1 to 8 carbon atoms. An acrylic resin obtained by polymerizing a monomer component.

(3) The adhesive sheet according to the above (1) or (2), wherein the adhesive layer is The thickness is 5~300μm.

(4) The adhesive sheet according to any one of the above (1) to (3), wherein a double-sided adhesive sheet obtained by laminating a release sheet on both sides of the adhesive layer is used.

(5) A method for producing a laminate having an adhesive layer, wherein the adhesive layer of the adhesive sheet according to any one of the above (1) to (4) is adhered to an object to be subjected to active energy ray irradiation. And at least one of the heating.

(6) The method for producing a laminate having an adhesive layer according to the above (5), wherein the surface of the object has a step of 1 to 100 μm.

(7) A laminate having an adhesive layer obtained by the method for producing a laminate having an adhesive layer according to (5) or (6) above.

(8) An image display device comprising the laminate having the adhesive layer according to (7) above.

(9) A touch panel comprising the layered body having an adhesive layer according to (7) above

The most important feature of the present invention is that an adhesive having a followability to a step is used, and an acrylic resin having a high glass transition temperature which is generally difficult to use is used, and the adhesive layer further contains an ethylenically unsaturated compound containing one ethylenically unsaturated group. According to this configuration, when the adhesive sheet of the present invention is bonded to the adherend, it exhibits good step followability and adhesion, and after being bonded to the adherend, it is hardened by active energy rays and/or heat. Since the adherend and the adhesive layer can be very strongly fixed, foaming between the adherend and the adhesive layer can be suppressed.

The adhesive sheet of the present invention is excellent in adhesion followability and excellent in foaming resistance, adhesiveness (adhesion, retention), and resistance The wet heat is excellently balanced and excellent in recyclability, so that it is particularly useful as an adhesive sheet for bonding to a touch panel and an image display device.

Hereinafter, the present invention will be described in detail.

Further, in the present invention, the term "(meth)acrylic acid" means acrylic acid or methacrylic acid, and the term "(meth)acryl fluorenyl group means acryl fluorenyl group or methacryl fluorenyl group, so-called (meth) acrylate. Means acrylate or methacrylate.

In addition, the acrylic resin refers to a resin obtained by polymerizing a monomer component containing at least one type of (meth)acrylic monomer.

The adhesive sheet of the present invention has a bridging agent of an acrylic resin (A) and a bridging agent (B) having a functional group having a specific glass transition temperature, and an ethylenically unsaturated compound having an ethylenically unsaturated group. (C) Adhesive sheet of the adhesive layer.

<Acrylic resin containing functional group (A)>

The adhesive sheet of the present invention is characterized in that a functional group-containing acrylic resin (A) having a glass transition temperature of -35 ° C or higher is used. The glass transition temperature of the functional group-containing acrylic resin (A) is preferably -35 ° C to 30 ° C, and is -35. °C ~ 0 ° C is better, with -35 ° C ~ -10 ° C is particularly good, of which -30 ° C ~ 10 ° C is particularly good. When the glass transition temperature of the functional group-containing acrylic resin (A) is too low, the foaming resistance is deteriorated, and the object of the present invention cannot be attained. In addition, the glass transition temperature is too high, and there is a tendency for the step followability to be easily lowered.

In order to transfer the temperature of the glass containing the functional group-containing acrylic resin (A) The degree of the monomer component constituting the functional group-containing acrylic resin (A) or the blending ratio may be appropriately adjusted within the above range.

Further, the glass transition temperature is calculated by the following formula of Fox.

In the above formula,

Tg: glass transition temperature of copolymer (K)

Tga: glass transition temperature (K) of homopolymer of monomer A

Wa: the weight fraction of monomer A

Tgb: glass transition temperature (K) of homopolymer of monomer B

Wb: the weight fraction of monomer B

Tgn: glass transition temperature (K) of homopolymer of monomer N

Wn: the weight fraction of monomer N

(Where, Wa+Wb+...+Wn=1)

The functional group-containing acrylic resin (A) contains a functional group which can be bridged by reaction with a bridging agent (B) to be described later, and examples of the functional group include a hydroxyl group, a carboxyl group, an amine group, and an acetamidine group. Ethylene group, isocyanate group, glycidyl group and the like.

Among these, in order to effectively bridge the reaction, it is preferable to contain a hydroxyl group or a carboxyl group, and it is also possible to improve the heat and humidity resistance, and it is preferable to contain a hydroxyl group.

The functional group-containing acrylic resin (A) used in the present invention contains a functional group-containing monomer (a1) or (meth) propyl as an essential component. The olefinic acid alkyl ester monomer (a2) and a monomer component obtained by further polymerizing the monomer (a3) as needed are polymerized as a monomer component.

The functional group-containing monomer (a1) may be a monomer which can react with a bridging agent (B) to be described later to form a bridging point, and examples thereof include a hydroxyl group-containing monomer and a carboxyl group-containing monomer. A monomer containing an amine group, a monomer containing an ethyl acetyl group, a monomer containing an isocyanate group, a monomer containing a glycidyl group, and the like.

Among these, it is preferable to use a monomer having a hydroxyl group or a monomer having a carboxyl group at a point where the bridging reaction can be efficiently carried out, and it is preferable to use a monomer having a hydroxyl group at a point where the heat and humidity resistance can be improved.

Further, when the object is a metal or an oxide thereof, it is likely to be corroded, and it is preferred that a monomer having a carboxyl group is not used.

The hydroxyl group-containing monomer may, for example, be 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, or (methyl). A hydroxyalkyl (meth) acrylate such as hexa-hydroxyhexyl acrylate or -8-hydroxyoctyl (meth)acrylate, or a caprolactone-denatured 2-hydroxyethyl (meth)acrylate An oxyalkylene denatured monomer such as an ester denatured monomer, diethylene glycol (meth)acrylate or polyethylene glycol (meth)acrylate, or other, for example, 2-propenyloxyethyl-2-hydroxyl a monomer containing a hydroxyl group such as ethylphthalic acid; 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, or 3-chloro(meth)acrylate- A monomer having a secondary hydroxyl group such as 2-hydroxypropyl ester or a monomer having a tertiary hydroxyl group such as 2,2-dimethyl-2-hydroxyethyl (meth)acrylate.

Among the above hydroxyl group-containing monomers, the reactivity of the bridging agent is excellent Preferably, a monomer having a hydroxyl group of 1 is preferred, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate is particularly preferred.

In addition, the content of the hydroxyl group-containing monomer used in the present invention, wherein the content of the di(meth)acrylate using the impurity is 0.5% or less, particularly preferably 0.2% or less, and further 0.1% or less. Preferably, specifically, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred. The carboxyl group-containing monomer may, for example, be (meth)acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, isaconic acid or propylene. Guanidine N-glycolic acid, cinnamic acid, etc., among which (meth)acrylic acid can be used favorably.

Examples of the amino group-containing monomer include, for example, tert-butylaminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, and dimethylaminoethyl (meth)acrylate. Diethylaminoethyl (meth)acrylate or the like.

The monomer containing an ethyl acetonitrile group may, for example, be 2-(ethylindenyl)ethyl (meth)acrylate or allyl acetate.

The monomer containing an isocyanate group may, for example, be 2-propenyloxyethyl isocyanate, 2-methylpropenyloxyethyl isocyanate, or an alkylene oxide adduct thereof.

Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate and allyl glycidyl (meth)acrylate.

These functional group-containing monomers (a1) may be used singly or in combination of two or more.

The content of the functional group-containing monomer (a1) in the monomer component is preferably 0.01 to 70% by weight, more preferably 0.1 to 50% by weight, further. It is preferably 1 to 35% by weight, particularly preferably 10 to 30% by weight. When the content ratio of the functional group-containing monomer (a1) is too small, the cohesive strength of the acrylic resin is insufficient, and the durability tends to be lowered. When the content is too large, the viscosity of the acrylic resin tends to be high, or the storage stability tends to be lowered.

When a monomer having a hydroxyl group is used as the functional group-containing monomer (a1), the content of the hydroxyl group-containing monomer is preferably 5 to 50% by weight based on the total of the copolymerization component, more preferably 7 to 40% by weight. Further, it is preferably 10 to 35% by weight, particularly preferably 15 to 30% by weight. When the content of the hydroxyl group-containing monomer is too small, the adhesive strength is lowered, and the moist heat resistance tends to be lowered. When the amount is too large, the viscosity of the acrylic resin is increased, and it is difficult to form a favorable coating film.

The (meth)acrylic acid alkyl ester monomer (a2) may, for example, be methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate or (meth)acrylate. , (3) butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, ( Isooctyl methacrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, (meth) acrylate Stearyl ester, isostearyl (meth)acrylate, behenyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate, and the like.

These (meth)acrylic acid alkyl ester type monomers (a2) may be used alone or in combination of two or more.

In the present invention, an alkyl group having a carbon number of 1 to 8 having an alkyl group such as methyl methacrylate, ethyl methacrylate or tributyl methacrylate is used to improve the cohesive force. The body (a2-1) is preferred, and more preferably, it is effective to increase the rigidity of the main chain, improve the point of resistance to foaming, or share with the monomer The point of excellent polymerizability (polymerization stability) is preferably an alkyl methacrylate monomer having an alkyl group having 4 to 8 carbon atoms, and particularly preferably a third butyl methacrylate.

From the point of imparting hydrophobicity to the adhesive layer, an alkyl acrylate monomer (a2-2) having a glass transition temperature of -20 ° C or higher and a carbon number of 8 or more in the case of a homopolymer is used. , remove (a2-1).) is better.

The propylene-based alkyl ester-based monomer having a glass transition temperature of -20 ° C or higher and a carbon number of 8 or more in the case of a homopolymer, for example, lauryl acrylate (Tg = -3 ° C; carbon number) 12), cetyl acrylate (Tg = 35 ° C; carbon number 16), n-stearyl acrylate (Tg = 30 ° C: carbon number 18), isostearyl acrylate (Tg = -18 ° C; carbon number 18), behenyl acrylate (Tg = 46 ° C; carbon number 22), 2-mercaptotetradecyl acrylate (Tg = 9 ° C; carbon number 24), methacrylic acid-2-B Hexyl hexyl ester (Tg = -10 ° C; carbon number 8), cetyl methacrylate (Tg = 23.5 ° C; carbon number 16), n-stearyl methacrylate (Tg = 38 ° C; carbon number 18 ), behenyl methacrylate (Tg = 44 ° C; carbon number 22), 2-mercaptotetradecyl methacrylate (Tg = 10 ° C; carbon number 24) and the like.

Among these, 2-ethylhexyl methacrylate and isostearyl acrylate can be preferably used in the point of excellent polymerization stability and hydrophobicity.

The content of the alkyl (meth) acrylate monomer (a2) in the monomer component is preferably from 5 to 99% by weight, more preferably from 20 to 80% by weight, further preferably from 40 to 70% by weight. good. When the content ratio of the alkyl (meth)acrylate monomer (a2) is too small, the foaming resistance and the cohesive strength tend to be lowered. When the content is too large, the adhesive properties when used as an adhesive tend to be lowered.

When the alkyl methacrylate monomer (a2-1) having a carbon number of 1 to 8 in the above alkyl group is used, the content of the monomer component is 10 to 70 by weight. % is preferably 15 to 60% by weight, more preferably 20 to 50% by weight. When the content ratio is too small, the foaming resistance and the cohesive strength tend to be lowered. When the content is too large, the step followability tends to be deteriorated.

When the alkyl acrylate monomer (a2-2) having a glass transition temperature of -20 ° C or higher and a carbon number of the alkyl group of 8 or more is used, the content ratio of the entire monomer component is It is preferably 1 to 70% by weight, more preferably 5 to 60% by weight, still more preferably 7 to 55% by weight, and particularly preferably 10 to 50% by weight. When the content ratio of the alkyl (meth)acrylate monomer (a2-2) is too small, the foaming resistance tends to be lowered. When the content of the acrylic resin is too large, the viscosity of the acrylic resin is increased, and handling becomes difficult, or Reduce the tendency of adhesive properties when making adhesives.

As the other polymerizable monomer (a3), for example, an alicyclic (meth)acrylate monomer such as cyclohexyl (meth)acrylate or isobornyl (meth)acrylate; (meth)acrylic acid can be used; Phenyl ester, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyl diglycol (meth) acrylate, 2-hydroxy-3-phenoxy propyl (meth) acrylate An ester, a monomer containing one aromatic ring such as styrene or α-methylstyrene; or a (meth)acrylate containing a biphenyloxy structure such as diphenoxyethyl (meth)acrylate Monomer; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, (meth)acrylic acid 2-butoxyethyl ester, 2-butoxy diglycol (meth)acrylate, methoxydiglycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate , ethoxylated diglycol (meth) acrylate, methoxy dipropylene glycol (meth) acrylate, (meth) acrylate Methoxy polyethylene glycol ester, octyloxy polyethylene glycol mono(meth)acrylate, lauryloxy polyethylene glycol mono(meth)acrylate, stearoxy poly(meth)acrylate (meth)acrylate monomer containing an ether chain such as ethylene glycol ester; acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, Alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, dialkyl isonate, dialkyl fumarate, allyl alcohol, propylene chloride, methyl vinyl ketone, N-propylene Indole methyl trimethyl ammonium chloride, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone, (meth) propylene morpholine or the like.

These may be used alone or in combination of two or more.

The content ratio of the other polymerizable monomer (a3) in the monomer component is preferably 0 to 40% by weight, more preferably 0 to 30% by weight, still more preferably 0 to 25% by weight. When the amount of the other polymerizable monomer (a3) is too large, there is a tendency that the adhesive property is easily lowered.

By polymerizing the above monomer component, a functional group-containing acrylic resin (A) can be produced. As the polymerization method of the functional group-containing acrylic resin (A), for example, a conventional polymerization method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, or the like can be used, and the polymerization conditions can also be in accordance with the conventionally known ones. Polymerization conditions are polymerized, but are produced by solution polymerization, and it is preferable to produce the functional group-containing acrylic resin (A) in a safe and stable manner in any monomer composition.

In the solution polymerization, for example, a monomer component of (a1) to (a3) and a polymerization initiator are mixed or dropped in an organic solvent, and polymerized in a reflux state or at a temperature of 50 to 98 ° C for 0.1 to 20 hours. .

The organic solvent for the above polymerization reaction may, for example, be toluene or dimethyl An aromatic hydrocarbon such as benzene, an aliphatic hydrocarbon such as hexane, an ester such as ethyl acetate or butyl acetate; a fatty alcohol such as n-propanol or isopropanol; acetone, methyl ethyl ketone or methyl isobutyl a ketone such as a ketone or methylcyclohexanone or the like. Among these solvents, the ease of polymerization or the chain transfer effect or the ease of drying when the adhesive is applied, in terms of safety, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, methyl isobutylene The ketone is preferred, and ethyl acetate, acetone, and methyl ketone are further preferred.

Specific examples of the polymerization initiator include azobisisobutyronitrile such as azobisisobutyronitrile, azobisdimethylvaleronitrile, and benzoyl peroxide, which are ordinary radical polymerization initiators. A peroxide-based polymerization initiator such as laurel, tributyl peroxide or cumene hydroperoxide. These monomers which can be used together are suitably used, and they can be used individually or in combination of 2 or more types.

The weight average molecular weight of the functional group-containing acrylic resin (A) is usually 50,000 to 2,000,000, preferably 200,000 to 1,000,000, and particularly preferably 300,000 to 800,000. If the weight average molecular weight is too small, there is a tendency to lower the durability, and if it is too large, there is a tendency to lower the step followability.

The degree of dispersion (weight average molecular weight/number average molecular weight) of the functional group-containing acrylic resin (A) is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, and particularly preferably 7 or less. If the degree of dispersion is too high, there is a tendency to lower the durability of the adhesive layer. Further, the lower limit of the degree of dispersion is usually 1.1 in terms of manufacturing limit.

Further, the weight average molecular weight is a weight average molecular weight in terms of molecular weight of a standard polystyrene, and a high performance liquid chromatography ("Waters 2695 (host)" and "Waters 2414 (sensor)" manufactured by Waters, Japan) is used. , 3 columns in series: Shodex GPC KF-806L (excluding the limit molecular weight: 2 × 10 ⁷ , separation range: 100 ~ 2 × 10 ⁷ , theoretical layer: 10,000 layers / branch, filler material: styrene - divinyl The same method was employed for the benzene copolymer, filler particle size: 10 μm), and the number average molecular weight. The degree of dispersion can be determined from the weight average molecular weight and the number average molecular weight.

Further, in the functional group-containing acrylic resin (A) of the present invention, a functional group-containing acrylic resin having an active energy ray-reactive structural site, that is, a functional group-containing acrylic acid having an ethylenically unsaturated group is used. The resin (acrylic resin containing an ethylenically unsaturated group) can be preferably a point having a higher modulus of elasticity of the adhesive layer after the active energy ray irradiation.

The acrylic resin containing an ethylenically unsaturated group is obtained by reacting a functional group of the functional group-containing acrylic resin (A) with an ethylenically unsaturated compound having a functional group reactive with a functional group. By. Examples of the ethylenically unsaturated compound include a carboxyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, a glycidyl group-containing unsaturated monomer, an isocyanate group-containing unsaturated monomer, and a guanamine group. An unsaturated monomer, an amine group-containing unsaturated monomer, a sulfonic acid group-containing unsaturated monomer, and the like.

For example, when the functional group in the acrylic resin is a carboxyl group, an unsaturated monomer containing a glycidyl group or an unsaturated monomer containing an isocyanate group is preferably used. When the functional group is a hydroxyl group, an isocyanate group-containing unsaturated monomer is used. When the functional group is a glycidyl group, a carboxyl group-containing unsaturated monomer or a decylamine-containing unsaturated monomer is used. When the functional group is an amine group, a glycidyl group-containing unsaturated monomer is used, and each of them is used. When the functional group in the acrylic resin is a hydroxyl group, the ethylenically unsaturated compound is preferably an isocyanate group-unsaturated compound, and the reactivity of the functional group is excellent.

Further, in the present invention, the adhesive sheet is used for a transparent electrode such as a touch panel or other electronic member, particularly for the purpose of bonding an information label used for a precision electronic component, or for use in fixing an electronic component. Since the corrosion resistance is required, in this case, the functional group-containing acrylic resin (A) is preferably one which does not contain an acidic group.

<Bridge agent (B)>

The bridging agent (B) used in the present invention mainly exhibits excellent adhesion by reacting with a functional group contained in the functional group-containing acrylic resin (A), for example, an isocyanate bridging agent or an epoxy bridging bridge. Agent, aziridine bridging agent, melamine bridging agent, aldehyde bridging agent, amine bridging agent, metal chelate bridging agent, and the like. Among these, an isocyanate-based bridging agent can be preferably used in terms of improving the adhesion to the substrate or the reactivity with the functional group-containing acrylic resin (A).

Examples of the isocyanate-based bridging agent include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hydrogenated toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, and Methylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylene diisocyanate, 1, 5-naphthalene diisocyanate, triphenylmethane triisocyanate, and an adduct of the polyisocyanate compound and a polyol compound such as trimethylolpropane, a diurea of the polyisocyanate compound or isocyanuric acid Ester.

The epoxy-based bridging agent may, for example, be a bisphenol A ‧ epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether or glycerol triglycidyl Ether, 1,6-hexanediol diglycidyl Ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl alcohol, diglycerin polyglycidyl ether, and the like.

The aziridine-based bridging agent may, for example, be tetramethylolmethane tri-β-aziridine propionate, trimethylolpropane tri-β-aziridine propionate or N,N'-diphenyl. Methane-4,4'-bis(1-aziridine carboxamide), N,N'-cyclohexane-1,6-bis(1-aziridine carboxamide), and the like.

The above melamine-based bridging agent may, for example, be hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexabutoxymethyl melamine, hexaethoxyoxymethyl melamine or hexa Oxymethyl melamine, melamine resin, and the like.

Examples of the aldehyde-based bridging agent include glyoxal, malondialdehyde, succinaldehyde, butenedialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, and benzaldehyde.

The above amine-based bridging agent may, for example, be hexamethylenediamine, triethyldiamine, polyethyleneimine, cyclohexanetetramine, diethylenetriamine, triethyltetramine or isophorone. Diamine, amine based resin, polydecylamine, and the like.

The metal chelate-based bridging agent may, for example, be an ethyl acetonide or acetamidine coordination of a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, lanthanum, magnesium, vanadium, chromium or zirconium. Compounds, etc.

Further, these bridging agents (B) may be used singly or in combination of two or more.

The amount of the bridging agent (B) to be added is usually 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and 0.1 to 2 parts by weight of the functional group-containing acrylic resin (A). The weight department is particularly good. Bridging agent (B) If the amount of use is too small, the cohesive strength is insufficient, and there is a tendency that sufficient durability cannot be obtained. When the amount is too large, the flexibility is lowered and the step followability tends to be lowered.

The reaction temperature at the time of bridging the acrylic resin (A) and the bridging agent (B) to form a bridging material may be normal temperature, for example, heating at 20 to 60 °C.

<Ethylene unsaturated compound containing one ethylenically unsaturated group (c)>

The ethylenically unsaturated compound (C) containing one ethylenically unsaturated group of the present invention (hereinafter sometimes referred to as a monofunctional unsaturated compound (C)), which has an ethylenically unsaturated group (A) Acrylate-based compound (C1) (Removal of (C2) to be described later. Hereinafter, it may be described as "monofunctional (meth)acrylate-based compound (C1)"), or may contain a nitrogen atom-containing ethylenic group. The ethylenically unsaturated compound (C2) having an unsaturated group (hereinafter sometimes referred to as "nitrogen-containing monofunctional unsaturated compound (C2)") is preferred.

The monofunctional (meth) acrylate compound (C1) may, for example, be a long-chain aliphatic (meth) acrylate (C1-1), an alicyclic (meth) acrylate (C1-2), or an aromatic An acrylate (C1-3), and an oxyalkylene structural denatured compound (C1-4) of the above acrylates.

The long-chain aliphatic (meth) acrylate (C1-1) may, for example, be decyl (meth) acrylate, isodecyl (meth) acrylate or dodecyl (meth) acrylate, (methyl) Tridecyl acrylate, isotridecyl (meth)acrylate, isotetradecyl (meth)acrylate, n-stearyl (meth)acrylate, isostearyl (meth)acrylate, (A) Base) behenyl acrylate, 2-mercaptotetradecyl (meth) acrylate, and the like.

An alicyclic (meth) acrylate (C1-2), for example, (methyl) Isobornyl acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and the like.

The aromatic (meth) acrylate (C1-3) may, for example, be biphenyl (meth) acrylate, naphthyl (meth) acrylate or 2-hydroxy-3-phenoxy (meth) acrylate. Propyl ester, 3-chloro-2-hydroxypropyl (meth)acrylate, and the like.

The oxyalkylene structural denatured compound (C1-4) of the above (C1-1) to (C1-3) is as follows.

The oxyalkylene structure denatured compound of (C1-1) may, for example, be 2-ethylhexyl diglycol (meth) acrylate, methoxy triethylene glycol (meth) acrylate, or (methyl) Ethoxyethylene glycol diacrylate, alkyl polyethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, alkylene glycol (meth)acrylate, single ( Alkyl methacrylate or the like.

The oxyalkylene structure denatured compound of (C1-2) may, for example, be a tert-butylcyclohexyloxyethyl (meth)acrylate, a cyclohexyloxyalkyl (meth)acrylate or a bicyclo(meth)acrylate. Pentenyloxyethyl ester, dicyclopentyloxyethyl (meth)acrylate, and the like.

The oxyalkylene structure denatured compound of (C1-3) may, for example, be benzyl (meth)acrylate, phenoxy (meth)acrylate, phenyl diglycol (meth)acrylate, or (methyl). Phenyltriethylene glycol acrylate, phenyltetraethylene glycol (meth)acrylate, biphenyloxyethyl (meth)acrylate, indophenol ethylene oxide denatured (repeated 4) (meth)acrylic acid Ester, indophenol ethylene oxide denatured (repeat 8) (meth) acrylate, and the like.

Among the monofunctional acrylate-based compounds (C1), long-chain aliphatic (meth) acrylate (C1-1), alicyclic (meth) acrylate (C1-2), and aromatic (A) are used. The oxyalkylene structure of the acrylate (C1-3) denatured compound (C1-4), which is preferable for obtaining a stable adhesive force, and particularly preferably (meth) propylene Acid isotetradecyl ester, isotridecyl (meth)acrylate, isostearyl (meth)acrylate, phenyl diglycol (meth)acrylate, dicyclopentenyloxy (meth)acrylate ester.

The above nitrogen-containing monofunctional unsaturated compound (C2) is exemplified by the use of an adhesive which enhances the adhesion of the adhesive, and examples thereof include acrylamide, methacrylamide, butoxymethyl acrylamide, and hydroxyethyl group. A acrylamide-based unsaturated monomer such as acrylamide, dimethylaminopropyl acrylamide or diacetone acrylamide, N-propylene oxiranyl ethylhexahydrophthalic acid, or propylene oxime? a phenyl group, an oxazolidinone acrylate, or the like, wherein (meth) acrylamide-based unsaturated monomer is used, and it is preferable that the volatility and the adhesion property are well balanced, and the butoxy group is used. Methyl acrylamide and diacetone acrylamide are particularly preferred.

Among these, in the present invention, a long-chain aliphatic acrylate (C1-1) is preferably used, and an adhesive layer which is not easily colored and optically transparent, and which imparts hydrophobicity to the adhesive layer, is preferably used. Isotetradecyl ester, isotridecyl acrylate, isostearyl acrylate, 2-mercaptotetradecyl acrylate are particularly preferred.

Further, the monofunctional unsaturated compound (C) is cured by using at least one of an active energy ray and heat as described later, and is present as a polymer in the adhesive layer, but the polymer is selected. The monofunctional unsaturated compound (C) having a glass transition temperature of -80 to 80 ° C is preferred.

The glass transition temperature is preferably -60 to 40 ° C, more preferably -55 to 10 ° C, and particularly preferably -20 to 0 ° C. If the glass transition temperature is too high, it is difficult to exhibit adhesive properties, and if it is too low, there is a tendency to reduce cohesion.

Further, the glass transition temperature is calculated by the above formula of Fox.

Further, the monofunctional unsaturated compound (C) has an effect of improving the drying property when the organic solvent coating is applied while the adhesive is soft, and is coated. When the layer is dried (especially when it is dried when a thick film is applied), it is easy to remain in the adhesive layer by using an organic solvent which does not easily volatilize.

The ignition point of the monofunctional unsaturated compound (C) is preferably 40 ° C or higher, more preferably 80 ° C or higher, further preferably 100 ° C or higher, and particularly preferably 140 ° C or higher. If the ignition point is too low, there is a tendency to volatilize during the drying step. Furthermore, the upper limit of the ignition point is usually 350 °C.

The weight average molecular weight of the monofunctional unsaturated compound (C) is preferably from 100 to 2,000, more preferably from 120 to 1,000, further preferably from 160 to 600, and particularly preferably from 200 to 400.

If the molecular weight is too large, there is a tendency to lower the adhesiveness, and if it is too small, it tends to be easily volatilized in the drying step.

<Adhesive sheet>

The adhesive sheet of the present invention has a bridging agent comprising an acrylic resin (A) having a specific glass transition temperature and a bridging agent (B), and an adhesive layer of a monofunctional unsaturated compound (C). Adhesive sheet.

In the above adhesive layer, the content of the monofunctional unsaturated compound (C) is preferably from 5 to 70% by weight, more preferably from 9 to 50% by weight, further preferably from 12 to 40% by weight, based on the entire adhesive layer. Preferably, it is particularly good at 15 to 30% by weight.

When the content ratio of the monofunctional unsaturated compound (C) is too small, there is a tendency to lower the step followability. When the content is too large, the modulus of elasticity at the time of sheet formation becomes too low, and the workability or stability of the coating film is lowered. trend.

In addition, the content ratio of the monofunctional unsaturated compound (C) is a value obtained by the ratio of the monounsaturated compound (C) to the entire content of the adhesive composition after drying and removing the organic solvent constituting the adhesive layer. .

The adhesive layer may be a monofunctional unsaturated compound (C) after bridging the functional group-containing acrylic resin (A) and the bridging agent (B), or may be a monofunctional unsaturated compound (C) in advance. In the presence of the monofunctional unsaturated compound (C), the functional group-containing acrylic resin (A) and the bridging agent (B) are bridged, and the adhesive sheet having excellent step followability is easily obtained. The presence of the functional unsaturated compound (C) preferably bridges the functional group-containing acrylic resin (A) and the bridging agent (B).

When the adhesive sheet of the present invention is produced by using the functional group-containing acrylic resin (A), the bridging agent (B), and the monofunctional unsaturated compound (C), the amount of the functional group-containing acrylic resin (A) is adjusted. The compounding amount of the monofunctional unsaturated compound (C) is preferably 50:50 to 95:5 (weight ratio), more preferably 65:35 to 90:9, still more preferably 70:30 to 85:15.

When the amount of the monofunctional unsaturated compound (C) to the functional group-containing acrylic resin (A) is too large, the coating film stability tends to be lowered, and if it is too small, the step followability tends to be lowered.

The blending amount of the bridging agent (B) and the amount of the monofunctional unsaturated compound (C) are preferably 0.1:99.9 to 20:80 (weight ratio), more preferably 0.3:99.7 to 2:98, and further 0.5. : 99.5~1:99.0 is better.

When the amount of the monofunctional unsaturated compound (C) is adjusted to the amount of the bridging agent (B), the tendency to lower the stability of the coating film is excessive, and if it is too small, there is a tendency to reduce the followability of the step.

The adhesive layer of the adhesive sheet of the present invention contains two in addition to the bridging agent of the functional group-containing acrylic resin (A) and the bridging agent (B) and the monofunctional unsaturated compound (C) in the adhesive layer. More than one ethylenically unsaturated group The unsaturated compound (D) (hereinafter sometimes abbreviated as "polyfunctional unsaturated compound (D)") is preferably a point of adjusting the cohesive force of the entire adhesive layer, and further contains a polymerization initiator (E). It is preferable to stabilize the reaction at the time of irradiation of the active energy ray and/or at the time of heating.

For the polyfunctional unsaturated compound (D), for example, an ethylenically unsaturated monomer having two or more ethylenically unsaturated groups in one molecule, for example, a bifunctional monomer or a trifunctional or higher monomer, Or a urethane (meth) acrylate compound, an epoxy (meth) acrylate type compound, or a polyester (meth) acrylate type compound. Among these, an ethylenically unsaturated monomer and a urethane (meth) acrylate type compound are used, and it is excellent in the hardening rate and the stability of the physical property.

The bifunctional monomer may be a monomer containing two ethylenically unsaturated groups, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and Tetraethylene glycol methacrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, Butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide modified bisphenol A di(meth)acrylate, propylene oxide denatured bisphenol A type II ( Methyl)acrylate, 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol, ethylene oxide-denatured di(meth)acrylate, di(meth)acrylic acid Glyceride, pentaerythritol di(meth)acrylate, ethylene glycol glycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diminish Glycerol ether di(meth)acrylate, hydroxypivalic acid denatured neopentyl glycol di(meth)acrylate, isocyanuric acid ethylene oxide denatured di(meth)acrylate, 2-(A) Base) Acyl oxyethyl acid phosphate diesters.

The trifunctional or higher monomer may be a monomer having three or more ethylenically unsaturated groups, and examples thereof include trimethylolpropane tri(meth)acrylate and tris(meth)acrylic acid isoprene. Tetraol ester, pentaerythritol tetra(meth)acrylate, diisopentyl tetra(meth)acrylate, diisoamyl tetra(meth)acrylate, penta(meth)acrylate Isopentitol ester, diisoamyl hexa(meth) acrylate, tris(meth) propylene oxiranoxy trimethylolpropane, glycerol polyglycidyl ether poly(meth) acrylate, different Cyanuric acid ethylene oxide denatured tris(meth)acrylate, ethylene oxide denatured diisopentaerythritol penta (meth) acrylate, ethylene oxide denatured diisoprolol hexa(meth) acrylate Ester, ethylene oxide denatured pentaerythritol tri(meth)acrylate, ethylene oxide denatured pentaerythritol tetra(meth)acrylate, succinic acid denatured pentaerythritol tri(meth)acrylate Wait.

The urethane (meth) acrylate type compound is a (meth) acrylate type compound having a urethane bond in a molecule, and a (meth)acrylic compound containing a hydroxyl group and a polyvalent isocyanate compound are used. If necessary, the polyol compound) may be obtained by a conventional method. The weight average molecular weight of the urethane (meth) acrylate type compound is usually 300 to 4,000.

In the above adhesive layer, the content of the polyfunctional unsaturated compound (D) is preferably 20 to 0.1% by weight, more preferably 10 to 0.2% by weight, still more preferably 5 to 0.3% by weight, based on the entire adhesive layer. Preferably, it is particularly preferably from 1 to 0.5% by weight.

When the content ratio of the polyfunctional unsaturated compound (D) is too small, there is a tendency to lower the reliability when the active energy ray is irradiated and hardened. When the amount is too large, the cohesive force at the time of curing by the active energy ray is excessively increased to cause hardening and shrinkage. Reduce stickiness The trend of performance.

In addition, the content ratio of the polyfunctional unsaturated compound (D) is determined by the content ratio of the entire adhesive composition after drying and removing the organic solvent constituting the adhesive layer by using the polyfunctional unsaturated compound (D). The value.

Further, the content of the polyfunctional unsaturated compound (D) in the adhesive layer is preferably 0.01 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, per 100 parts by weight of the monofunctional unsaturated compound (C), further. It is preferably 1 to 5 parts by weight. When the content of the polyfunctional unsaturated compound (D) is too large, in the post-hardening step, the cohesive force excessively rises to cause hardening shrinkage, and the adhesive property tends to be lowered. When the amount is too small, the retaining force tends to be insufficient.

When the functional group-containing acrylic resin (A), the bridging agent (B), and the monofunctional unsaturated compound (C) are further used as the polyfunctional unsaturated compound (D), the polyfunctionality in the production of the adhesive sheet of the present invention is not The compounding amount of the saturated compound (D) is preferably 0.01 to 50 parts by weight, more preferably 0.1 to 30 parts by weight, and further preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the functional group-containing acrylic resin (A). Good, especially good for 1~5 weight. When the amount of the polyfunctional unsaturated compound (D) is too large, in the post-hardening step, the cohesive force excessively rises to cause hardening shrinkage, and the adhesive property tends to be lowered. When the amount is too small, the retaining force tends to be insufficient.

As the polymerization initiator (E), for example, various polymerization initiators such as a photopolymerization initiator (e1), a thermal polymerization initiator (e2), and the like, in particular, a photopolymerization initiator (e1) can be used. It can be hardened by irradiation with an active energy ray such as ultraviolet rays for a short period of time.

In addition, you can use both parties as needed.

The photopolymerization initiator (e1) and the thermal polymerization initiator (e2) A conventional general polymerization initiator can be used.

The photopolymerization initiator (e1) may, for example, be diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal or 4-(2). -hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholinyl (4-thiomethylphenyl) propyl 1-ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)butanone, 2-hydroxy-2-methyl-1-[4-(1-A Acetophenones such as phenyl) phenyl]acetone oligomers; benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone, phthalate Methyl benzoate, 4-phenylbenzophenone, 4-benzylidene-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra (t-butyl) Oxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzhydrazide-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy) a benzophenone such as tetraethylammonium bromide or (4-benzylidenebenzyl)trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthiophene Tons of ketone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2- Hydroxy)-3 , thioxanthone such as 4-dimethyl-9H-thioxanthene-9-one methyl chloride; 2,4,6-trimethylbenzimidium-diphenylphosphine oxide, bis(2,6- Mercaptophosphine oxide such as dimethoxybenzhydryl]-2,4,4-trimethyl-pentylphosphine oxide or bis(2,4,6-trimethylbenzhydrazide)-phenylphosphine oxide In addition, these photopolymerization initiators (e1) may be used alone or in combination of two or more.

In addition, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (milaxone), 4,4'-diethylaminobenzophenone, 2 may also be used in combination. - dimethylaminoethyl benzoic acid, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid (n-butoxy) ethyl ester, 4-dimethylamino benzoic acid Isoamyl ester, 4-dimethylamino benzoic acid 2-ethylhexyl ester, 2,4-diethyl thioxanthone, 2,4-diisopropylthioxanthone or the like is used as such an auxiliary.

Among these, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzamidine isopropyl ether, 4-(2-hydroxyethoxy)-phenyl (2-hydroxy-2-propene) are used. Ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one is preferred.

Further, the above thermal polymerization initiator (e2) may, for example, be methyl ethyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate acetate, acetoxyacetate acetate, 1,1-bis(third hexyl peroxide)-3,3,5-trimethylcyclohexane, 1,1-bis(peroxylated third hexyl)-cyclohexane, 1,1-double (over Oxidized tert-butyl)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)-2-methylcyclohexane, 1,1-double (peroxidation) Tertiary butyl)-cyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-butylperoxy)butane, 2,2-dual ( 4,4-di-t-butylcyclohexyl)propane, p-menthane hydroperoxide, p-cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, isopropyl Benzene hydroperoxide, third hexyl hydroperoxide, tert-butyl hydroperoxide, α,α'-bis(t-butylperoxy)diisopropylbenzene, dicumyl peroxide, 2,5- Dimethyl-2,5-bis(tributylbutyl peroxide)hexane, tert-butylperoxy cumene, dibutyltributyl peroxide, 2,5-dimethyl-2,5- Bis(t-butylperoxy)hex-3-yne, isobutyl peroxide Base, peroxidized 3,5,5-trimethylhexanide, octyl peroxide, oxidized laurel, stearyl peroxide, peroxy succinic acid, meta-toluene peroxide, benzammonium peroxide, over Di-n-propyl oxydicarboxylate, diisopropyl peroxydicarboxylate, bis(4-butyltributylcyclohexyl)peroxydicarboxylate, di-2-ethoxylated dicarboxylic acid dicarboxylate Ester, di-2-ethoxyhexyl peroxydicarboxylate, di-3-methoxybutyl peroxydicarboxylate, dibutyl butyl peroxydicarboxylate, dicarboxylic acid dicarboxylic acid 3-methyl-3-methoxybutyl)ester, α,α'-bis(peroxide neodymium) diisopropylbenzene, new peroxidation Isopropyl phenyl citrate, 1,1,3,3-tetramethylbutyl peroxy neodecanoate, neodecanoic acid-1-cyclohexyl-1-methylethyl ester, peroxy neodecanoic acid Trihexyl ester, tert-butyl peroxy neodecanoate, third hexyl peroxypivalate, tert-butyl peroxypivalate, 2-ethylhexanoic acid-1,1,3,3 -tetramethylbutyl ester, 2,5-dimethyl-2,5-bis(2-ethylperoxyhexano)hexanoate, 1-cyclohexyl-1-peroxy-2-ethylhexanoate Methyl ethyl ester, third hexyl peroxy-2-ethylhexanoate, tert-butyl peroxy 2-ethylhexanoate, trihexyl isopropyl monocarboxylate, isobutyric acid peroxide Third butyl ester, third butyl peroxy malate, third butyl peroxy 3,5,5-trimethylhexanoate, third butyl laurate, peroxidized monocarboxylic acid Tributyl ester, tert-butyl peroxy 2-ethylhexyl monocarboxylate, tert-butyl peroxyacetate, tert-butyl peroxytoluene benzoate, tert-butyl peroxybenzoate, bis ( Tert-butyl peroxy) isophthalate, 2,5-dimethyl-2,5-bis(m-toluene peroxide) hexane, third hexyl peroxybenzoate, 2 , 5-dimethyl-2,5-bis(benzyl peroxide)hexane, tert-butyl peroxyallylcarboxylate, tributyltrimethylsulfonyl peroxide, 3,3' , an organic peroxide-based initiator such as 4,4'-tetra(t-butylcarboxylate)benzophenone or 2,3-dimethyl-2,3-diphenylbutane; -Phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1-[(1-cyano-1-methylethyl)azo]carbamamine, 1,1'- Azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azo Bis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionamidine)hydrogen dichloride, 2,2'-azobis(2-methyl-N-phenyl) Propionate) dihydrogen chloride, 2,2'-azobis[N-(4-chlorophenyl)-2-methylpropionamidine]hydrogen dichloride, 2,2'-azobis[N-(4-hydrogen) Phenyl)-2-methylpropionamidine]dihydrogen chloride, 2,2'-azobis[2-methyl-N-propionamidine]hydrogen dichloride, 2,2'-azobis[2-methyl- N-(2-propenyl)propanoid]hydrogen dichloride, 2,2'-azobis[N-(2-hydroxyethyl)-2-methylpropionamidine] Hydrogen dichloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]hydrogen dichloride, 2,2'-azobis[2-(2-imidazoline) 2-yl)propane]hydrogen dichloride, 2,2'-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazin-2-yl)propane]hydrogen dihydrogen , 2,2'-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]hydrogen dichloride, 2,2'-azobis[2-(5-hydroxy- 3,4,5,6-tetrahydropyrimidin-2-yl)propane]hydrogen dichloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2- Propane}hydrogen dichloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis{2-methyl-N-[1, 1-bis(hydroxymethyl)-2-hydroxyethyl]propanamine}, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl] Propylamine, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propanamide, 2,2'-azobis(2-methylpropionamide), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl-2,2-azobis ( Azo such as 2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis[2-(hydroxymethyl)propanenitrile] It is an initiator and the like. In addition, these thermal polymerization initiators (e2) may be used alone or in combination of two or more.

The content of the above polymerization initiator (E) in the adhesive layer is 100 parts by weight of the monofunctional unsaturated compound (C) (when the polyfunctional unsaturated compound (D) is used, with (C) and (D) The total weight of 10 parts is preferably 0.01 to 50 parts by weight, more preferably 0.1 to 20 parts by weight, further preferably 0.3 to 12 parts by weight, and particularly preferably 0.5 to 5 parts by weight. When the content of the polymerization initiator (E) is too small, the curability is insufficient and the physical properties tend to be unstable. Even if it is too large, the above effects are not obtained.

The adhesive sheet of the present invention may be an adhesive sheet in which an adhesive layer is provided on a substrate sheet, or a double-sided adhesive sheet in which an adhesive layer is provided on a release sheet, and is bonded to a subject. Substrate-free double used in the state of the substrate sheet It is preferable that the surface is adhered to a sheet, and the adhesiveness is excellent, and the adhesion strength of the formed layer is high, and the substrate-free double-sided adhesive sheet is preferable.

In the method for producing an adhesive sheet of the present invention, for example, a functional group-containing acrylic resin (A), a bridging agent (B), and a monofunctional unsaturated compound (C) are essential components, and more than two or more are contained as needed. An adhesive composition of an ethylenically unsaturated ethylenically unsaturated compound (D) and a polymerization initiator (E), coated on a substrate sheet and a release sheet, dried, and cooked as necessary An adhesive sheet of the present invention comprising a functional group-containing acrylic resin (A), a bridging agent for the bridging agent (B), and an adhesive layer of the monofunctional unsaturated compound (C).

In the case of a substrate-free double-sided adhesive sheet, for example, after applying an adhesive composition on a release sheet to form an adhesive layer obtained by drying, on the side of the release sheet without the adhesive layer, further It is bonded to another release sheet and made as necessary to make it ripe.

The substrate sheet may, for example, be polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate or polyethylene terephthalate. A polyester resin such as a benzoic acid formic acid copolymer; a polyolefin resin such as polyethylene, polypropylene or polymethylpentene; or a product name "ARTON (cyclic olefin polymer; manufactured by JSR)", and a product A cyclic olefin resin such as "ZEONOR (cyclic olefin polymer; manufactured by Japan ZEON Co., Ltd.)"; a polyvinyl fluoride resin such as polyvinyl fluoride, polyvinylidene fluoride or polyvinyl fluoride; nylon 6, nylon 6 , 6, etc. polyamine; polyvinyl chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, vinylon and other vinyl polymers; Cellulose resin such as cellulose acetate or cellophane; polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, Acrylic resin such as polybutyl acrylate; polystyrene; polycarbonate; polyarylate; synthetic resin sheet such as polyimine, metal foil of aluminum, copper, iron, paper of high quality paper, transparent paper, etc. , fabric or non-woven fabric composed of glass fiber, natural fiber, synthetic fiber, and the like. These base material sheets can be used in a single layer or a laminate of two or more layers.

Further, as the substrate sheet, a transparent electrode film such as an ITO (oxygen indium tin) electrode film or an organic conductive film such as a Cu mesh, an Ag mesh, an Ag nanofiber, or a polyphenylene, or an electrode film may be used. The optical members such as the above various substrates, polarizing plates, retardation plates, elliptically polarizing plates, optical compensation films, brightness enhancement films, electromagnetic shielding films, near infrared absorbing films, and AR (antireflection) films.

The mold release sheet can be used for a release treatment of various synthetic resin sheets, paper, cloth, nonwoven fabric, etc., which are exemplified in the above-mentioned base material sheet, and examples thereof include a bismuth-based release sheet and an olefin-based release sheet. A release sheet, a fluorine-based release sheet, a long-chain alkyl-based release sheet, and an alkyd-based release sheet.

The coating method of the above adhesive composition may, for example, be a gravure roller coating machine, a reverse roller coating machine, a contact roller coating machine, a dip roller coating machine, a wire roller coating machine, Scraper roller coating machine, spray coating machine.

The drying conditions, drying conditions, and drying temperature are usually 50 ° C to 250 ° C, preferably 60 ° C to 120 ° C, and more preferably 65 ° C to 95 ° C. Drying time, usually 10 seconds to 10 minutes.

The temperature of the above-mentioned ripening treatment is usually room temperature to 70 ° C, and the time is usually from 1 day to 30 days, specifically, for example, 23 to 1 day to 20 days, preferably 23 to 3 to 10 days. It can be carried out under the conditions of 40 ° C for 1 day to 7 days.

The thickness of the adhesive layer of the adhesive sheet of the present invention is usually 5~300μm, preferably 10~250μm, further 25~200μm, especially 50~175μm.

When the thickness of the pressure-sensitive adhesive layer is too small, there is a tendency to lower the step followability, and if it is too thick, the thickness of the entire optical member tends to increase too much.

Further, in particular, when a thick film adhesive layer is to be obtained, a film thickness coating of 10 μm or more is preferable, and 50 μm or more is more preferable, and further preferably 100 μm or more, and an upper limit of the film thickness is used as a film at the time of coating. Thick, often 800 μm.

In the above-mentioned film thickness, "ID-C 112B" manufactured by Mitutoyo Co., Ltd. is used, and the value obtained by subtracting the measured value of the thickness of the constituent member other than the adhesive layer is measured from the measured value of the thickness of the entire adhesive sheet.

The gel fraction of the adhesive layer of the adhesive sheet of the present invention (before irradiation with an active energy ray and/or heat hardening) is preferably 5 to 60% in terms of adhesion and step followability, and further 10~50% is better, and 20~45% is especially good. If the gel fraction is too low, the cohesive force is lowered, and there is a tendency that the adhesive sheet has a trace due to foreign matter, or the adhesive sheet is drooped. Further, when the gel fraction is too high, the cohesive force is increased to lower the step followability, and the adhesion to the object is lowered, and the blister resistance tends to be deteriorated.

In the adhesive sheet of the present invention, the gel fraction of the adhesive layer after irradiation with an active energy ray and/or heat curing is preferably 10 to 95%, and 20 to 90, in terms of durability and adhesion. The % is more preferable, and 30 to 80% is particularly preferable, and when the gel fraction is too low, the durability of the adhesive layer is deteriorated due to a decrease in cohesive force. Further, when the gel fraction is too high, the adhesion of the interface tends to decrease due to an increase in the cohesive force.

The above gel fraction, an index of the degree of bridging (degree of hardening), for example For example, it is calculated as follows. In other words, an adhesive sheet (without an isolator) formed by forming an adhesive layer on a polymer sheet (for example, a polyethylene terephthalate film) to be a substrate, and a SUS of 200 mesh The wire mesh was wrapped, immersed in toluene at 23 ° C for 24 hours, and the weight percentage of the insoluble adhesive component remaining in the wire mesh was taken as the gel fraction. However, the weight of the substrate is subtracted.

The obtained adhesive sheet of the present invention contains a monofunctional unsaturated compound by a binder containing a functional group-containing acrylic resin (A) and a bridging agent (B) having a specific glass transition temperature. (C), the plasticizing effect of the adhesive is imparted by the monofunctional unsaturated compound (C), and the elastic modulus of the adhesive layer is lowered to exhibit excellent followability to the step (concavity and convexity) of the adherend. In addition, since the glass transition temperature of the functional group-containing acrylic resin (A) is higher than usual, the content of the bridging agent can be reduced, so that the adhesion of the acrylic resin can be minimized due to the reduction of the heat bridge. .

Then, after the body is bonded, the monofunctional unsaturated compound (C) contained in the adhesive layer is polymerized by irradiating the adhesive layer with active energy rays and/or heating, thereby being stronger with the adherend. Go on.

In the bonding method of the adhesive sheet and the adherend, for example, after the adhesive layer of the adhesive sheet is adhered to the object, it is subjected to heat and pressure treatment in an autoclave or the like (for example, at 50 ° C, 0.5). MPa × 30 minutes) method.

In the present invention, when the adhesive layer is cured by irradiation with an active energy ray, it is sufficient that at least one of the substrate sheet and the object is transparent, and the transparent energy source is irradiated with the active energy ray.

When the active energy ray is irradiated, in addition to light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays, and electromagnetic waves such as X-rays and gamma rays, It is also possible to use an electron beam, a proton line, a neutron line, etc., but it is advantageous to harden by ultraviolet irradiation, such as the hardening speed, the ease of obtaining the irradiation device, and the price. Further, when the electron beam irradiation is performed, the photopolymerization initiator (e1) can be hardened without using the photopolymerization initiator (e1).

Then, a high-pressure mercury lamp, an electrodeless lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide mercury lamp, a chemical lamp, a black light, an LED lamp, or the like can be used as the light source for the ultraviolet irradiation. In the case of the above-mentioned high-pressure mercury lamp, it can be carried out, for example, at 5 to 3000 mJ/cm ² , preferably 50 to 2000 mJ/cm ² , and in the case of the above-described electrodeless lamp, for example, 2 to 2000 mJ/cm. ² , carried out under the conditions of 10~1000mJ/cm ² . The irradiation time varies depending on the type of the light source, the distance between the light source and the coated surface, the thickness of the coating layer, and other conditions, but is usually several seconds to several tens of seconds, and may be several seconds in a case. On the other hand, at the time of irradiation of the above-mentioned electron beam, for example, an electron beam having an energy in the range of 50 to 1000 keV is used, and an irradiation amount of 2 to 50 Mrad is preferable.

Further, when the pressure-sensitive adhesive layer is thermally cured, the polymerization initiator (E) is carried out by heating to start the polymerization reaction using a thermal polymerization initiator (e2). The treatment temperature and the treatment time by heat hardening vary depending on the type of the thermal polymerization initiator (e2) to be used, and are usually calculated by the half life of the initiator, but the treatment temperature is usually 70 to 170 ° C. , processing time, usually 0.2 to 20 minutes, especially good for 0.5 to 10 minutes.

The adhesive sheet of the present invention is adhered to the object, and at least one of irradiation or heating of the active energy ray is performed, whereby the cured adhesive layer of the present invention after curing can be obtained. Laminating layer of adhesive layer [Body/Adhesive Layer/Substrate Sheet], or [Substrate/Adhesive Layer/Recipient] when making a substrate-free double-sided adhesive sheet.

The above-mentioned object is not particularly limited, and examples thereof include a transparent electrode film such as an organic conductive film such as an ITO film, a Cu mesh, an Ag nanofiber, or a polyphenylene, a polarizing plate, a phase difference plate, an elliptically polarizing plate, and optical compensation. An optical member such as a film, a brightness enhancement film, an electromagnetic wave shielding film, a near-infrared absorbing film, or an AR (anti-reflection) film, in particular, a substrate having a step on the surface, can remarkably exhibit excellent followability of the present invention. The effect of the adhesive sheet is good. For example, even a subject having a step of 1 to 100 μm, particularly 3 to 50 μm, or even 5 to 30 μm on the surface can exhibit good followability.

In the adhesive sheet of the present invention, the storage elastic modulus of the adhesive layer is preferably 1.0×10 ³ to 1.0×10 ⁵ at 23° C., 1 Hz, and is preferably 0.5 to 0.7 at 50° C. and 1 Hz tan δ.

Further, the storage elastic modulus of the active energy ray and/or the heat-cured adhesive layer is preferably 1.0 × 10 ⁴ or more at 23 ° C and 1 Hz, and is preferably 0.5 or less at 50 ° C and 1 Hz tan δ.

The adhesive sheet of the present invention has optical sheets for glass or ITO transparent electrode sheets, polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), and the like. Adhesive use of optical members such as materials, polarizers, phase difference plates, optical compensation films, and brightness enhancement films. Further, it can be suitably used for an image display device such as a touch panel including the optical members.

Example

Hereinafter, the present invention will be more specifically described by way of examples, but the present invention Without departing from the gist thereof, the following embodiments are not limited. In addition, in the example, "part" and "%" are the weight basis.

First, an acrylic resin (A) solution containing various functional groups was prepared as follows. The measurement of the weight average molecular weight, the degree of dispersion, and the glass transition temperature of the functional group-containing acrylic resin (A) was carried out in accordance with the above method.

Further, regarding the measurement of the solid content concentration, 1 to 2 g of the functional group-containing acrylic resin (A) solution was taken to an aluminum foil, and dried by Kett (infrared dryer, 185 W, height 5 cm) for 45 minutes, and before and after drying. The change in weight and the measurement of the viscosity were measured in accordance with the 4.5.3 rotational viscometer method of JIS K5400 (1990).

[Production of Functional Group-Based Acrylic Resin (A) Solution]

[Acrylic resin (A-1) containing a functional group]

In a 4-neck round bottom bottle equipped with a reflux condenser, a stirrer, a nitrogen inlet and a thermometer, 29 parts of 2-ethylhexyl acrylate (a2), 30 parts of 2-hydroxyethyl acrylate (a1), 15 were added. 2-ethylhexylmethyl acrylate (a2-2), 15 parts isostearyl acrylate (a2-2), 11 parts of tributyl methacryl (a2-1) and 8 parts of acetone, 41 parts of methyl ethyl ketone, 5 Ethyl acetate, after heating to reflux, 0.04 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator was added, and after reacting for 3 hours at the reflux temperature of methyl ethyl ketone, 0.02 parts of azobisisobutyronitrile was added. AIBN), 3 parts of ethyl acetate, further reacted for 4 hours, diluted with ethyl acetate to obtain an acrylic resin solution, and 100 parts (resin portion) of the obtained acrylic resin solution, 0.03 parts of 2-methylpropene oxyfluoride The isocyanate is reacted at 50 ° C for 12 hours to obtain an ethylenically unsaturated group in the side chain, and the addition of 0.13 mol% to the hydroxyethyl acrylate. A functional group-containing acrylic resin (A-1) solution (weight average molecular weight: 296,000, dispersion degree: 3.72, glass transition temperature - 25.4 ° C, solid content: 60%, viscosity: 12,000 mPa s (25 ° C)).

(Acrylic resin containing functional group (A-2)

In a 4-neck round bottom bottle equipped with a reflux condenser, a stirrer, a nitrogen inlet and a thermometer, 50 parts of 2-ethylhexyl acrylate (a2), 30 parts of 2-hydroxyethyl acrylate (a1), 20 parts were added. After the third-butyl methyl acrylate (a2-1) and 76 parts of ethyl acetate were heated and refluxed, 0.04 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator was added, and the reaction was carried out at the reflux temperature of ethyl acetate. After 3 hours, 0.02 parts of azobisisobutyronitrile (AIBN) and 3 parts of ethyl acetate were added, and further reacted for 3 hours, and diluted with ethyl acetate to obtain an acrylic resin solution, and 100 parts of the obtained acrylic resin solution (resin portion) 0.03 parts of 2-methylpropenyloxyethyl isocyanate was placed and reacted at 50 ° C for 12 hours to obtain a functional group containing an ethylenically unsaturated group to a hydroxyethyl acrylate in a side chain and adding 0.08 mol%. Acrylic resin (A-2) solution (weight average molecular weight 622,000, dispersion 4.95, glass transition temperature -32.2 ° C, solid fraction 49.1%, viscosity 16,000 mPa ‧ (25 ° C)).

(Acrylic resin containing functional group (A'-1))

Into a 4-neck round bottom bottle equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer, 70 parts of 2-ethylhexyl acrylate (a2), 30 parts of 2-hydroxyethyl acrylate (a1), and After 150 parts of ethyl acetate was heated and refluxed, 0.04 part of azobisisobutyronitrile (AIBN) as a polymerization initiator was added, and after reacting for 3 hours at the reflux temperature of ethyl acetate, ethyl acetate was diluted to obtain acrylic acid. A resin solution was added to 100 parts (resin portion) of the obtained acrylic resin solution, and 0.03 part of 2-methylpropenyloxyethyl isocyanate was placed and reacted at 50 ° C for 12 hours to obtain a resin solution. Adding an ethylenically unsaturated group to a hydroxyethyl acrylate in a side chain to a 0.17 mol% solution of a functional group-containing acrylic resin (A'-1) (weight average molecular weight: 691,000, dispersion degree 4.99, glass transition temperature) -56.1 ° C, solid content 51.7%, viscosity 20,000 mPas (25 ° C)).

The functional group-containing acrylic resins (A-1), (A-2), and (A'-1) produced as described above have a raw material monomer component content and a raw material monomer component as a homopolymer. The glass transition temperature at the time, the weight average molecular weight of the functional group-containing acrylic resin, the degree of dispersion, and the viscosity are shown in Table 1 below.

The abbreviation of Table 1 indicates the following compounds

HEA: 2-hydroxyethyl acrylate

2EHA: 2-ethylhexyl acrylate

tBMA: tert-butyl methacrylate

2EHMA: 2-ethylhexyl methacrylate

ISTA: Isostearyl acrylate

[Bridge agent (B)]

The bridging agent (B-1) is prepared as follows.

‧ 55% ethyl acetate solution of toluene diisocyanate adduct of trimethylolpropane ("Coronate L-55E" manufactured by Nippon Polyurethane Co., Ltd.)

[monofunctional unsaturated compound (C)]

The monofunctional unsaturated compound (C) is prepared as follows.

‧(C1-1a) Isotridecyl acrylate ("FA-113A" manufactured by Hitachi Chemical Co., Ltd.)

‧(C1-1b)-2-meryltetradecyl acrylate ("DTD-A" manufactured by Kyoeisha Chemical Co., Ltd.)

‧(C1-1c) isostearyl acrylate ("STAR", Osaka Organic Chemical Industry Co., Ltd.)

[Polyfunctional unsaturated compound (D)]

The polyunsaturated compound (D-1) is prepared as follows.

‧Trimethylolpropane triacrylate (TMPTA)

[Polymerization initiator (E)]

The polymerization initiator (E-1) was prepared as follows.

1:1 1-1:1 mixture of cyclohexyl benzophenone and benzophenone ("IRGACURE500" manufactured by Ciba Japan)

<Example 1>

To 100 parts (resin portion) of the functional group-containing acrylic resin (A-1), 0.2 part of bridging agent (B-1), 40 parts of monofunctional unsaturated compound (C-1), and 1 part of polyfunctionality were blended. The saturated compound (D-1) and 1 part of the photopolymerization initiator (E-1) were prepared to prepare a solution of the adhesive composition.

This adhesive composition solution was applied to a polyester release sheet, and the thickness after drying was 100 μm, and dried at 90 ° C for 5 minutes to form an adhesive layer. The obtained adhesive layer was sandwiched with a polyester release sheet and aged at 40 ° C for 3 days to obtain a substrateless double-sided adhesive sheet [I-1].

Further, the release sheet of the one side peeled off from the adhesive layer of the obtained baseless double-sided adhesive sheet was pressure-bonded to an easy-to-treat polyphenylene oxide having a thickness of 125 μm. A polyethylene diacetate (PET) sheet was obtained as a PET sheet [01-1] with an adhesive layer having an adhesive thickness of 100 μm.

Further, the release sheet of the other surface is peeled off from the adhesive layer of the substrate-free double-sided adhesive sheet, and is crimped to a polyethylene terephthalate (PET) sheet having a thickness of 50 μm. A PET sheet [III-1] with an adhesive layer having an adhesive layer of 100 μm was obtained.

<Example 2, Comparative Examples 1, 2>

The baseless double-sided adhesive sheet [I-2], [I'-1) was obtained in the same manner as in Example 1 except that the blending ratio of the components (A) to (E) was changed to the blending ratio described in Table 2. ], [I'-2] and PET sheets with adhesive layers [II-2], [II'-1], [II'-2], [III-2], [III'-1], [III'-2].

<Example 3>

The blending ratio of the components (A) to (E) was changed to the blending ratio described in Table 2, and the thickness of the adhesive layer was 160 μm in the same manner as in Example 1 except that the thickness after drying was 160 μm. The substrate-free double-sided adhesive sheet [I-3] and the PET sheet with the adhesive layer [II-3], [III-3].

The gel fraction of the adhesive layer and the optical properties of the adhesive layer were measured using the above-mentioned substrate-free double-sided adhesive sheets [I-1] to [I-3], [I'-1], [I'-2]. Characteristics and resistance to foaming. Further, the adhesion of the adhesive layer of the PET sheets [II-1] to [II-3], [II'-1], and [II'-2] using the above adhesive tape layer, and the step followability were measured. . Further, the heat resistance of the adhesive layer was evaluated using the PET sheets [III-1] to [III-3], [III'-1], and [III'-2] with the above adhesive layer. The results are shown in Table 3.

[Gel fraction before ultraviolet irradiation]

The above-mentioned substrate-free double-sided adhesive sheets [I-1]-[I-3], [I'-1], [I'-2] were respectively cut into 40 mm×40 mm, and then 23° C.×50% RH. Allow to stand for 30 minutes. Thereafter, one of the release sheets was peeled off, and the adhesive side was adhered to a SUS mesh sheet (200 mesh) of 50 mm × 100 mm, and then the other release sheet was peeled off, and the longitudinal direction of the SUS mesh sheet was applied. After the sample was folded back from the center portion, the gel fraction (%) was measured in a sealed container containing 250 g of toluene under the weight change at the time of immersion for 24 hours.

[Gel fraction after ultraviolet irradiation]

After the above-mentioned substrate-free double-sided adhesive sheets [I-1] to [I-3], [I'-1], and [I'-2] are respectively cut into 40 mm × 40 mm, a high-pressure mercury UV irradiation device is used. Ultraviolet irradiation (500 mJ/cm ² × 2 passes) was carried out at a peak illuminance: 150 mW/cm ² , and an integrated exposure amount: 1000 mJ/cm ² , and allowed to stand at 23 ° C × 50% RH for 30 minutes. Thereafter, one of the release sheets was peeled off, and the adhesive side was adhered to a SUS mesh sheet (200 mesh) of 50 mm × 100 mm, and then the other release sheet was peeled off, and the longitudinal direction of the SUS mesh sheet was applied. After the sample was folded back from the center portion, the gel fraction (%) was measured in a sealed container containing 250 g of toluene under the weight change at the time of immersion for 24 hours.

[Adhesion (initial adhesion)]

The PET film [II-1]~[II-3], [I1'-1], and [II'-2] with the adhesive layer were cut into a width of 25 mm × a length of 100 mm, and the release sheet was peeled off. The adhesive layer side was pressed back and forth on an alkali-free glass at 23 ° C and a relative humidity of 50% with a 2 kg rubber roller 2, and allowed to stand at 23 ° C and a relative humidity of 50%. The 180-degree peel strength (N/25 mm) was measured at a peeling speed of 300 mm/min at room temperature for 30 minutes.

[Adhesion (adhesion after hardening)]

The PET film [II-1]~[II-3], [I1'-1], and [II'-2] with the adhesive layer were cut into a width of 25 mm × a length of 100 mm, and the release sheet was peeled off. The adhesive layer side was pressed back and forth on an alkali-free glass at 23 ° C and a relative humidity of 50% with a 2 kg rubber roller 2, and an autoclave was added at 50 ° C for ‧ 0.5 MPa × 20 minutes. Pressure heat treatment. Thereafter, ultraviolet irradiation (500 mJ/cm ² × 2 passes) was carried out from the PET film side with a high-pressure mercury UV irradiation device, peak illuminance: 150 mW/cm ² , and integrated exposure: 1000 mJ/cm ² at 23 ° C × 50% RH. After standing for 30 minutes under the conditions, the 180-degree peel strength (N/25 mm) was measured at a peeling speed of 300 mm/min at normal temperature.

[step difference follow-up]

On the alkali-free glass, PET films of 25 μm, 38 μm, 50 μm, 70 μm, and 100 μm were respectively fixed by a transparent tape to prepare a glass having a step. The PET sheets [II-1] to [II-3], [I1'-1], and [II'-2] with the above adhesive layer were respectively subjected to the glass having a step difference at 23 ° C and a relative humidity of 50. In a % atmosphere, a 2 kg rubber roller 2 was pressed back and forth, and an autoclave was subjected to a pressure heat treatment at 50 ° C for ‧ 0.5 MPa × 20 minutes. Thereafter, from the PET film side, a high-pressure mercury UV irradiation device, peak illuminance: 150 mW/cm ² , integrated exposure: 1000 mJ/cm ² for ultraviolet irradiation of 500 mJ/cm ² × 2 lanes, at 23 ° C × 50% RH After standing for 30 minutes under conditions, the followability to the step was evaluated visually as follows.

(assessment)

◎...There was no confirmation that the air was trapped or floated in the step.

○... Some bites of air were confirmed in a part of the step, but it was not confirmed to float.

△... It is confirmed that a part of the step is biting air or floating.

×... A large float was confirmed in the step portion.

[Measurement of Optical Properties of Adhesive Layer]

[Production of sample for optical measurement]

The above-mentioned substrate-free double-sided adhesive sheets [I-1] to [I-3], [I'-1], and [I'-2] are respectively cut into a width of 25 mm × 25 mm, and a high-pressure mercury UV irradiation device is used. Wave illuminance: 150 mW/cm ² , integrated exposure: 1000 mJ/cm ² for ultraviolet irradiation of 500 mJ/cm ² × 2). Thereafter, one release sheet was peeled off from the adhesive layer, and the adhesive side was adhered to a glass slide (EAGLE XG, manufactured by Corning Co., Ltd.), and then autoclaved (50 ° C, 0.5 MPa, 20 minutes) to 23 The mixture was allowed to stand for 30 minutes under the conditions of °C × 50% RH. Finally, the release sheet on the other side was peeled off to prepare a test piece having a structure of "slide/adhesive layer".

The haze value and the color difference b* value were measured using the obtained test piece.

[Haze value]

The haze value is measured by the HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), and the values of the obtained diffusion transmittance and total light transmittance are substituted into the following formula. Haze. Furthermore, this machine is compliant According to JIS K7361-1.

Haze value (%) = (diffusion transmittance (%) / total light transmittance (%)) × 100

[color difference]

The color difference b* value was measured in accordance with JIS K7105, and the measurement was carried out under a penetration condition using a spectral color difference meter (SE6000: Nippon Denshoku Industries).

Furthermore, in the present invention, the haze, the total light transmittance, and the color difference b* value are measured by adhering only the adhesive layer to the alkali-free glass (total light transmittance = 93, haze = 0.06, b* value = 0.16) The measured value.

[heat and humidity resistance]

The PET film [III-1]~[III-3], [III'-1], and [III'-2] with the adhesive layer were cut into a width of 25 mm×25 mm, and the release sheet was peeled off to adhere. The agent side was adhered to a glass slide (EAGLE XG, manufactured by Corning Co., Ltd.), and then autoclaved (50 ° C, 0.5 MPa, 20 minutes). Thereafter, ultraviolet irradiation (500 mJ/cm ² × 2 passes) was carried out from the PET film side with a high-pressure mercury UV irradiation device, peak illuminance: 150 mW/cm ² , and integrated exposure: 1000 mJ/cm ² at 23 ° C × 50% RH. The test piece having a structure of "slide/adhesive layer/PET film" was prepared by allowing to stand for 30 minutes under the conditions.

Using the obtained test piece, the humidity resistance test was performed for 168 hours in an atmosphere of 85 ° C × 85% R. H., and the haze value after the moisture heat resistance test was started before the moisture heat resistance test was started, and the evaluation was performed on the following basis. The haze value was measured in the same manner as the measurement of the optical properties of the above-mentioned adhesive layer.

(assessment)

○ The haze value after the moisture resistance test was less than 2.0%, and the increase in the haze value before and after the moist heat resistance test was 1.2 times or less.

Δ... The haze value after the wet heat resistance test was less than 2.0%, and the increase in the haze value before and after the moist heat resistance test was larger than 1.2 times.

×... The haze value after the moisture resistance test was 2.0% or more.

[Flamation resistance]

The PET film [II-1]~[II-3], [I1'-1], and [II'-2] with the adhesive layer were cut into a width of 25 mm×50 mm, and the release sheet was peeled off. The adhesive layer side was adhered to an untreated polycarbonate plate having a thickness of 2 mm, and subjected to autoclave treatment (50 ° C, 0.5 MPa, 20 minutes). Next, from the PET film side, a high-pressure mercury UV irradiation apparatus, a peak illuminance: 150 mW/cm ² , and an integrated exposure amount: 1000 mJ/cm ² for ultraviolet irradiation (500 mJ/cm ² × 2 lanes) at 23 ° C × 50% RH The test piece having a structure of "polycarbonate sheet / acrylic pressure-sensitive adhesive layer / PET film" was produced by allowing to stand for 30 minutes.

Thereafter, the mixture was allowed to stand in an atmosphere of 85 ° C × 85% R.H. for 24 hours, and the degree of occurrence of foaming before and after standing was visually observed. The evaluation criteria are as follows.

(assessment)

◎... no foaming.

○... Although foaming of ψ0.5 mm or less was observed, foaming of less than mm0.5 mm was not observed.

△...The foaming of more than ψ0.5mm occurs in less than 1/3 of the total adhesion.

×...The foaming of more than ψ0.5mm occurs in 1/3 or more of the total adhesion.

[table 3]

From the above results, it was found that the adhesive sheets of Examples 1 and 2 having a thickness of 100 μm of the pressure-sensitive adhesive layer exhibited very excellent followability to the step of 25 μm and 38 μm, and the adhesive sheet of Example 1 showed sufficient difference to 50 μm. Follow-up.

Further, it was found that the adhesive sheet of Example 3 having a thickness of the adhesive layer of 160 μm exhibited very excellent followability to the step of 25 μm, 38 μm, and 50 μm, and showed sufficient followability to the step of 75 μm. In this case, the step of about 47% of the thickness of the adhesive layer showed sufficient followability, and it was found that the adhesive sheet of Example 1 having sufficient followability with respect to the step of 50% of the thickness of the adhesive layer was the same. The degree of excellent segmental follow-up.

Further, the adhesive sheets of Examples 1 to 3 are excellent in physical properties, strong adhesion, moist heat resistance, and blister resistance when the adhesive sheet is used for bonding an optical member such as a touch panel. .

On the other hand, it was found that the adhesive sheets of Comparative Examples 1 and 2 containing the functional group-containing acrylic resin (A) having a glass transition temperature lower than -35 ° C were inferior in step followability and blister resistance.

While the present invention has been described in detail with reference to the specific embodiments thereof, various modifications and changes can be added without departing from the spirit and scope of the invention. The present invention claims priority to Japanese Patent Application No. 2015-153476, the entire filing date of which is incorporated herein by reference.

[Industry profitability]

The adhesive sheet of the invention has excellent step followability, high adhesion, high light transmittance, and is not prone to haze, and is used for glass or Optical sheet of ITO transparent electrode sheet, polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polarizing plate, phase difference plate, optics The use of an optical member such as a compensation film or a brightness enhancement film. Furthermore, it can also be suitably used for a touch panel including these optical members.

Claims (9)

An adhesive sheet comprising: a bridge comprising a functional group-containing acrylic resin (A) and a bridging agent (B); and an adhesive layer of an ethylenically unsaturated compound (C) having one ethylenically unsaturated group. The glass transition temperature of the functional group-containing acrylic resin (A) is -35 ° C or higher. The adhesive sheet according to claim 1, wherein the functional group-containing acrylic resin (A) is a single alkyl methacrylate monomer having an alkyl group having 1 to 8 carbon atoms. An acrylic resin obtained by polymerizing a body component. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer has a thickness of 5 to 300 μm. The adhesive sheet according to any one of claims 1 to 3, which is a double-sided adhesive sheet obtained by laminating a release sheet on both sides of the pressure-sensitive adhesive layer. A method for producing a laminate having an adhesive layer, which is obtained by adhering an adhesive layer of an adhesive sheet according to any one of claims 1 to 4 to an object, and performing active energy ray irradiation and heating. At least one of them. The method for producing a laminate having an adhesive layer according to claim 5, wherein the surface of the object has a step of 1 to 100 μm. A laminate having an adhesive layer obtained by the method for producing a laminate having an adhesive layer according to claim 5 or 6. An image display device comprising the laminate having an adhesive layer according to claim 7 of the patent application. A touch panel having a laminate body having an adhesive layer according to claim 7