KR20180036968A - A pressure sensitive adhesive layer, a pressure sensitive adhesive layer, a pressure sensitive adhesive layer, a pressure sensitive adhesive layer, an image display device, and a touch panel - Google Patents

Abstract

It is an object of the present invention to provide a pressure-sensitive adhesive sheet excellent in step-following property and blister resistance and having a high level of reliability, which is excellent in balance of adhesive properties (adhesive force, holding force), resistance to humid heat and blister resistance. The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing a crosslinked product of a functional group-containing acrylic resin (A) and a crosslinking agent (B) and an ethylenically unsaturated compound (C) having one ethylenic unsaturated group, Of -35 占 폚 or higher.

Description

A pressure sensitive adhesive layer, a pressure sensitive adhesive layer, a pressure sensitive adhesive layer, a pressure sensitive adhesive layer, an image display device, and a touch panel

The present invention relates to a pressure-sensitive adhesive sheet, a method for producing a laminate including the pressure-sensitive adhesive layer, a laminate including the pressure-sensitive adhesive layer, an image display device and a touch panel, and more particularly, A pressure-sensitive adhesive sheet excellent in balance of pressure-sensitive adhesive property and moisture resistance.

2. Description of the Related Art In recent years, display devices such as a liquid crystal display (LCD) and input devices such as touch panels used in combination with the display devices have been widely used in various fields. In these applications, Is used.

For example, a transparent double-sided pressure-sensitive adhesive sheet is used for attaching a touch panel and various display devices or optical members (protective plates, etc.). In such applications, (Hereinafter referred to as a step following ability) is required. 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, an adherend (member) and a pressure- And also an inner blistering property capable of suppressing these phenomena is also required.

As a means for imparting a step-following ability, there is a method of using a soft pressure-sensitive adhesive layer. In the above method, softening of the pressure-sensitive adhesive layer improves the step-wise followability but tends to cause deformation and distortion.

As a pressure sensitive adhesive sheet which is easy to secure step-following property and can prevent distortion and distortion of the film, Patent Document 1 discloses a pressure-sensitive adhesive sheet in which crosslinking of an acrylic resin according to a thermally crosslinkable crosslinking agent and crosslinking of an ethylenically unsaturated monomer A pressure sensitive adhesive sheet comprising a base polymer, a monomer having at least one polymerizable unsaturated group, a crosslinking agent capable of reacting with the base polymer by heat, a polymerization initiator and a solvent, A pressure-sensitive adhesive layer containing a pressure-sensitive adhesive which is semi-cured by the pressure-sensitive adhesive layer.

As means for imparting resistance to blistering, a method of increasing the cohesive strength of the pressure-sensitive adhesive layer by using a polymer containing an acid group or a nitrogen-based monomer as a polymerization component in the pressure-sensitive adhesive layer, a method of pressing the pressure- And a method of heating are proposed.

Patent Document 1 WO 2013/061938 A

However, in recent years, it has been required to follow various steps according to a change in the configuration of an adherend (member) as described above. Further, since the environment for use is also varied, Improvement is required. Although the pressure-sensitive adhesive sheet disclosed in Patent Document 1 is excellent in step-wise followability, it is not sufficient from the standpoint of blister resistance, and a pressure-sensitive adhesive sheet excellent in step-following property and blister resistance is required.

Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet excellent in step-following property and blister resistance under such a background and having a high level of reliability, which is excellent in both adhesive properties (adhesive force, holding power) and resistance to humidity and humidity.

SUMMARY OF THE INVENTION Accordingly, the present inventors have conducted intensive studies in view of such circumstances, and as a result, have found that in an adhesive sheet having an acrylic resin-crosslinked pressure-sensitive adhesive layer, the glass transition temperature is lower than the glass transition temperature of an acrylic resin By using a high acrylic resin, the obtained pressure sensitive adhesive sheet exhibits excellent step traceability when adhering to a substrate having unevenness, and at the same time, foaming or peeling occurs between the substrate and the pressure sensitive adhesive layer And has excellent blister resistance, excellent adhesive property (adhesive force, holding power), and excellent resistance to humidity and humidity, thereby completing the present invention.

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

(1) A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a crosslinked product of an acrylic resin (A) containing a functional group and a crosslinking agent (B) and an ethylenically unsaturated compound (C) having one ethylenic unsaturated group, A) having a glass transition temperature of -35 캜 or higher.

(2) The pressure-sensitive adhesive sheet according to the above (1), wherein the functional group-containing acrylic resin (A) is an acrylic resin obtained by polymerizing a monomer component containing a methacrylic acid alkyl ester monomer having an alkyl group of 1 to 8 carbon atoms.

(3) The pressure-sensitive adhesive sheet according to (1) or (2), wherein the pressure-sensitive adhesive layer has a thickness of 5 to 300 m.

(4) The pressure-sensitive adhesive sheet according to any one of (1) to (3), wherein the pressure-sensitive adhesive layer is a double-sided pressure-sensitive adhesive sheet laminated on both sides of the pressure-sensitive adhesive layer.

(5) A pressure-sensitive adhesive sheet as described in any one of (1) to (4) above, which comprises a pressure-sensitive adhesive layer surface bonded to an adherend and subjected to active energy ray irradiation and heating, Way.

(6) The pressure-sensitive adhesive layer according to (5), wherein the surface of the adherend has a step of 1 to 100 m.

(7) A laminate comprising a pressure-sensitive adhesive layer obtainable by a method for producing a laminate including the pressure-sensitive adhesive layer according to (5) or (6) above.

(8) An image display device having a laminate including the pressure-sensitive adhesive layer according to (7).

(9) A touch panel having a laminate including the pressure-sensitive adhesive layer according to (7).

The present invention is characterized in that an acrylic resin having a high glass transition temperature, which is difficult to be used for ordinary pressure sensitive adhesives requiring step-by-step conformability, is used as the most characteristic feature. Further, an ethylenically unsaturated compound containing one ethylenic unsaturated group is used as a pressure- . With this constitution, when the pressure-sensitive adhesive sheet of the present invention is brought into contact with an adherend, the adherend and the pressure-sensitive adhesive layer exhibit good step traceability and adhesive strength, and when adhered to an adherend and then cured by active energy rays and / So that the foaming between the adherend and the adhesive layer can be suppressed.

INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive sheet of the present invention is excellent in stepwise followability and excellent in resistance to blistering. It is excellent in balance of pressure-sensitive adhesive properties (adhesive force, holding force) and humidity resistance, And is useful as a pressure-sensitive adhesive sheet used for bonding an apparatus.

Hereinafter, the present invention will be described in detail.

Also, in the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

The acrylic resin is a resin obtained by polymerizing a monomer component containing at least one (meth) acrylic monomer.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer containing a crosslinked product of an acrylic resin (A) having a specific glass transition temperature and a crosslinking agent (B) and an ethylenically unsaturated compound (C) having one ethylenic unsaturated group Sheet.

≪ Functional group-containing acrylic resin (A) >

In the pressure-sensitive adhesive sheet of the present invention, the use of an acrylic resin (A) having a functional group having a glass transition temperature of -35 캜 or higher is the largest feature. The glass transition temperature of the functional group-containing acrylic resin (A) is preferably -35 ° C to 30 ° C, more preferably -35 ° C to 0 ° C, particularly preferably -35 ° C to -10 ° C, Particularly preferably -10 < 0 > C. If the glass transition temperature of the functional group-containing acrylic resin (A) is too low, the blister resistance is deteriorated and the object of the present invention can not be achieved. In addition, even if the glass transition temperature is too high, the step traceability tends to be lowered.

In order to set the glass transition temperature of the functional group-containing acrylic resin (A) within the above-mentioned range, the kind and the compounding ratio of the monomer components constituting the functional group-containing acrylic resin (A) can be appropriately adjusted.

The above-mentioned glass transition temperature is calculated by the following Fox equation.

Tg: Glass transition temperature (K) of the copolymer

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

Wa: weight fraction of monomer A

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

Wb: weight fraction of monomer B

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

Wn: the weight fraction of the monomer N (where Wa + Wb + ... + Wn = 1).

The acrylic resin (A) containing a functional group contains a functional group capable of becoming a crosslinking point by reacting with a crosslinking agent (B) described later. Examples of the functional group include a hydroxyl group, a carboxyl group, an amino group, an acetacetyl group, an isocyanate group, And a dealer.

Among them, those containing a hydroxyl group and a carboxyl group from the viewpoint of efficient crosslinking reaction are preferable, and those containing a hydroxyl group are preferable from the viewpoint of improving heat and humidity resistance.

The functional group-containing acrylic resin (A) used in the present invention contains a functional group-containing monomer (a1) as an essential component and contains a (meth) acrylic acid alkyl ester-based monomer (a2), and other polymerizable monomers (a3) is polymerized.

The functional group-containing monomer (a1) may be a monomer containing a functional group capable of reacting with a cross-linking agent (B) described later to form a crosslinking site. Examples of the monomer include a hydroxyl group-containing monomer, a carboxyl group- Group-containing monomers, isocyanate group-containing monomers, and glycidyl group-containing monomers.

Among them, from the viewpoint of efficient crosslinking reaction, it is preferable to use a hydroxyl group-containing monomer or a carboxyl group-containing monomer, and furthermore, from the viewpoint that heat resistance can be improved, it is preferable to use a hydroxyl group-containing monomer.

In addition, when the adherend is a metal or an oxide thereof, it is likely to corrode, and therefore, it is preferable not to use a carboxyl group-containing monomer.

As the hydroxyl group-containing monomer, for example,

(Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl Caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate Oxyethylene-modified monomers such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, and the like; other monomers containing a primary hydroxyl group such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid;

Monomers containing a secondary hydroxyl group such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-chloro-2-hydroxypropyl (meth) acrylate;

And tertiary hydroxyl group-containing monomers such as 2,2-dimethyl-2-hydroxyethyl (meth) acrylate.

Among the hydroxyl group-containing monomers, monomers having a primary hydroxyl group are preferable from the viewpoint of excellent reactivity with a crosslinking agent, and it is particularly preferable to use 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate.

As the hydroxyl group-containing monomer used in the present invention, it is also preferable to use a monomer having a content of di (meth) acrylate of 0.5% or less as an impurity, particularly 0.2% or less and 0.1% or less Particularly preferred are 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate.

Examples of the carboxyl group-containing monomers include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide- Among them, (meth) acrylic acid is preferably used.

Examples of the amino group-containing monomer include t-butylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl .

Examples of the acetacetyl group-containing monomer include 2- (acetacetoxy) ethyl (meth) acrylate, allylacetate, and the like.

Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate and alkylene oxide adducts thereof.

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

These functional group-containing monomers (a1) may be used alone 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, particularly preferably 0.1 to 50% by weight, more preferably 1 to 35% by weight, further preferably 10 To 30% by weight. If the content of the functional group-containing monomer (a1) is too small, the cohesive force of the acrylic resin tends to be insufficient and the durability tends to deteriorate, while if it is too large, the viscosity of the acrylic resin tends to increase or the storage stability tends to deteriorate.

When the hydroxyl group-containing monomer is used as the functional group-containing monomer (a1), the content of the hydroxyl group-containing monomer is preferably 5 to 50% by weight, more preferably 7 to 40% 35% by weight, more preferably 15 to 30% by weight. If the content of the hydroxyl group-containing monomer is too small, the adhesive strength tends to deteriorate or the heat and humidity resistance tends to deteriorate. When the content is too large, the viscosity of the acrylic resin tends to be high and it tends to be difficult to form a good coating film.

Examples of the (meth) acrylate alkyl ester monomer (a2) include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) (meth) acrylate, n-hexyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl Stearyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (Meth) acrylate, behenyl (meth) acrylate, 2-decyltetradecanyl (meth) acrylate and the like.

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

In the present invention, from the viewpoint of enhancing the cohesive strength, it is preferable to use a methacrylic acid alkyl ester monomer (a2-1) having 1 to 8 carbon atoms in the alkyl group such as methyl methacrylate, ethyl methacrylate and tert-butyl methacrylate From the viewpoint that the rigidity of the main chain can be efficiently elevated and the blister resistance can be improved and the number of carbon atoms of the alkyl group is 4 to 8 in view of excellent copolymerization (polymerization stability) with the monomer It is preferable to use a methacrylic acid alkyl ester-based monomer, especially tert-butyl methacrylate.

From the viewpoint of imparting hydrophobicity to the pressure-sensitive adhesive layer, (meth) acrylic acid alkyl ester-based monomer (a2-2) having a glass transition temperature of -20 占 폚 or higher and a number of carbon atoms of an alkyl group of not less than 8 -1) is excluded).

(Tg = -3 DEG C, 12 carbon atoms) as a (meth) acrylic acid alkyl ester monomer having a glass transition temperature of -20 DEG C or higher as a homopolymer and having an alkyl group having 8 or more carbon atoms, (Tg = -18 DEG C, carbon number: 18), cetyl acrylate (Tg = 35 DEG C, number of carbon atoms: 16), n-stearyl acrylate (Tg = 46 DEG C, carbon number 22), 2-decyltetradecanyl acrylate (Tg = 9 DEG C, 24 carbon atoms), 2-ethylhexyl methacrylate (Tg = 23.5 占 폚, 16 carbon atoms), n-stearyl methacrylate (Tg = 38 占 폚, carbon number 18), behenyl methacrylate (Tg = 44 占 폚, 22 carbon atoms), 2-decyltetradecanyl methacryl (Tg = 10 占 폚; 24 carbon atoms), and the like.

Of these, 2-ethylhexyl methacrylate and isostearyl acrylate are preferably used from the viewpoint of excellent polymerization stability and hydrophobicity.

The content of the (meth) acrylic acid alkyl ester monomer (a2) in the monomer component is preferably 5 to 99% by weight, particularly preferably 20 to 80% by weight, more preferably 40 to 70% to be. If the content of the (meth) acrylic acid alkyl ester-based monomer (a2) is too low, the blister resistance and the cohesive force tend to deteriorate, while if too large, the adhesive property when used as a pressure sensitive adhesive tends to deteriorate.

In the case of using the methacrylic acid alkyl ester-based monomer (a2-1) having 1 to 8 carbon atoms in the alkyl group, the content ratio in the monomer component is preferably from 10 to 70% by weight, 15 to 60% by weight, and more preferably 20 to 50% by weight. If the content is too small, the blister resistance due to a decrease in the cohesive strength tends to deteriorate, while if too large, the stepwise followability tends to deteriorate.

(Meth) acrylic acid alkyl ester monomer (a2-2) having a glass transition temperature of -20 占 폚 or higher when the homopolymer is used and the number of carbon atoms in the alkyl group is 8 or more, is used as the monomer component The content is preferably 1 to 70% by weight, particularly preferably 5 to 60% by weight, more preferably 7 to 55% by weight, particularly preferably 10 to 50% by weight. When the content of the (meth) acrylic acid alkyl ester monomer (a2-2) is too low, the blister performance tends to deteriorate. When the content is too high, the viscosity of the acrylic resin becomes high and handling becomes difficult, The physical properties tend to deteriorate.

As other polymerizable monomer (a3), for example,

Alicyclic (meth) acrylic acid ester monomers such as cyclohexyl (meth) acrylate and isobonyl (meth) acrylate;

Phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, 2- , and? -methylstyrene; (meth) acrylic acid ester monomers having a biphenyloxy structure such as biphenyloxyethyl (meth) acrylate;

(Meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, (Meth) acrylate, methoxyethyleneglycol (meth) acrylate, methoxyethyleneglycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (Meth) acrylate such as polyethylene glycol (meth) acrylate, octoxypolyethylene glycol polypropylene glycol mono (meth) acrylate, lauroxypolyethylene glycol mono (meth) acrylate and stearoxypolyethylene glycol mono ) Acrylic ester monomers;

Acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester , Allyl alcohol, acryl chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, (meth) acryloylmorpholine, and the like.

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

The content of the other polymerizable monomer (a3) in the monomer component is preferably 0 to 40% by weight, particularly preferably 0 to 30% by weight, and more preferably 0 to 25% by weight. If the other polymerizable monomer (a3) is too much, the adhesive property tends to be lowered.

The functional group-containing acrylic resin (A) can be prepared by polymerizing the above monomer components. As the polymerization method of the functional group-containing acrylic resin (A), conventionally known polymerization methods such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be used. However, it is preferable from the viewpoint of production of the functional group-containing acrylic resin (A) with an arbitrary monomer composition in a safe and stable manner to be produced by solution polymerization.

In such a solution polymerization, for example, the monomer components (a1) to (a3) and the polymerization initiator may be mixed or dropped in an organic solvent, and the solution may be polymerized in a reflux state or at 50 to 98 占 폚 for 0.1 to 20 hours.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, N-propyl alcohol, isopropyl alcohol and the like Aliphatic alcohols such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and the like. Of these solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene and methyl isobutyl ketone are preferable from the viewpoint of ease of polymerization reaction, effect of chain transfer, ease of drying at the time of coating with a pressure-sensitive adhesive, Ethyl acetate, acetone, and methyl ethyl ketone are preferable.

As such a polymerization initiator, azo polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, which are common radical polymerization initiators, benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene Peroxide-based polymerization initiators such as hydroperoxide, and the like. These may be appropriately selected and used in accordance with the monomers to be used, and they may be used alone or in combination of two or more.

The weight average molecular weight of the functional group-containing acrylic resin (A) is usually 50,000 to 200,000, preferably 200,000 to 1,000,000, and particularly preferably 300,000 to 800,000. If the weight average molecular weight is too small, the durability tends to deteriorate. If the weight average molecular weight is too large, the step traceability tends to decrease.

The dispersion degree (weight average molecular weight / number average molecular weight) of the acrylic resin (A) containing a functional group is preferably 20 or less, more preferably 15 or less, further preferably 10 or less, further preferably 7 or less. When the degree of dispersion is too high, the durability of the pressure-sensitive adhesive layer tends to be lowered. Further, the lower limit of the degree of dispersion is usually 1.1 in view of manufacturing limitations.

In addition, the weight average molecular weight was a weight average molecular weight in terms of standard polystyrene molecular weight, and the weight average molecular weight was measured by a high-performance liquid chromatography ("Waters 2695 (main body)" and "Waters 2414 3 pieces of 806 L (exclusion limit molecular weight: 2 x 10 ⁷ , separation range: 100 to 2 x 10 ⁷ , theoretical number of steps: 10,000 units / filler material: styrene- divinylbenzene copolymer, The same method can be used for the number average molecular weight. The degree of dispersion can be determined by weight average molecular weight and number average molecular weight.

As the functional group-containing acrylic resin (A) used in the present invention, a functional group-containing acrylic resin having an active energy ray-reactive structural site, that is, an acrylic resin containing a functional group containing an ethylenic unsaturated group (acrylic resin containing an ethylenic unsaturated group) From the viewpoint that the pressure-sensitive adhesive layer after irradiation with active energy rays can have a higher modulus of elasticity.

The ethylenic unsaturated group-containing acrylic resin can be obtained by reacting an ethylenically unsaturated compound having a functional group reactive with a functional group and a functional group of the acrylic resin (A) containing the functional group. Examples of the ethylenically unsaturated compound include the carboxyl group-containing unsaturated monomer, hydroxyl group-containing unsaturated monomer, glycidyl group-containing unsaturated monomer, isocyanate group-containing unsaturated monomer, amide group-containing unsaturated monomer, amino group-containing unsaturated monomer, sulfonic acid group- .

For example, when the functional group in the acrylic resin is a carboxyl group, the glycidyl group-containing unsaturated monomer or the isocyanate group-containing unsaturated monomer is preferably an isocyanate group-containing unsaturated monomer when the functional group is a hydroxyl group, When the carboxyl group-containing unsaturated monomer or amide group-containing unsaturated monomer is an amino group, a glycidyl group-containing unsaturated monomer is selected and used. Above all, when the functional group in the acrylic resin is a hydroxyl group, the ethylenically unsaturated compound is preferably an isocyanate group-containing unsaturated compound from the viewpoint of excellent reactivity of the functional group.

Further, in the present invention, when the adhesive sheet is used for an information label application in which a pressure-sensitive adhesive sheet is used in combination with a transparent electrode such as a touch panel or other electronic member, particularly a precision electronic member, , In this case, it is preferable that the functional group-containing acrylic resin (A) does not contain an acidic group.

≪ Crosslinking agent (B) >

The crosslinking agent (B) used in the present invention reacts with a functional group contained mainly in the acrylic resin (A) containing a functional group and exhibits excellent adhesion. For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, A melamine-based cross-linking agent, an aldehyde-based cross-linking agent, an amine-based cross-linking agent, and a metal chelate-based cross-linking agent. Of these, an isocyanate-based crosslinking agent is preferably used from the viewpoints of improving the adhesion with a substrate or from the reactivity with the acrylic resin (A) containing a functional group.

Examples of the isocyanate-based crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, Diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethyl xylene diisocyanate, 1,5-naphthalene diisocyanate, triphenyl methane Triisocyanate, adducts of these polyisocyanate compounds with polyol compounds such as trimethylolpropane, and biuret and isocyanurate compounds of these polyisocyanate compounds.

As the epoxy cross-linking agent, for example, an epoxy resin of bisphenol A epichlorohydrin type, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether , 1,6-hexanediol diglycidyl ether, trimethylol propane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol Polyglycidyl ether, and the like.

Examples of the aziridine crosslinking agent include tetramethylolmethane-tri-? -Aziridinylpropionate, trimethylolpropane-tri-? -Aziridinylpropionate, N, N'-diphenylmethane- , 4'-bis (1-aziridine carboxamide), and N, N'-hexamethylene 1,6-bis (1-aziridine carboxamide).

Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resin and the like. .

Examples of the aldehyde crosslinking agent include glyoxal, malondialdehyde, succindyaldehyde, maleindialdehyde, glutadialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

Examples of the amine-based crosslinking agent include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin and polyamide .

Examples of the metal chelate crosslinking agent include acetylacetone and acetoacetyl ester coordination compounds of a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, .

These crosslinking agents (B) may be used alone or in combination of two or more.

The blending amount of the crosslinking agent (B) is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, particularly preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the acrylic resin (A) Wealth. If the amount of the cross-linking agent (B) is too small, the cohesive force tends to be insufficient and sufficient durability can not be obtained. If too much, the flexibility is lowered and the step traceability tends to decrease.

The reaction temperature at the time of crosslinking the acrylic resin (A) and the crosslinking agent (B) to form a crosslinked product may be room temperature and may be heated, for example, at 20 to 60 캜.

<Ethylenically unsaturated compound (C) containing one ethylenically unsaturated group>

As the ethylenically unsaturated compound (C) (hereinafter also referred to as a monofunctional unsaturated compound (C)) containing one ethylenic unsaturated group used in the present invention, a (meth) acrylic ester compound having one ethylenic unsaturated group (C1) (hereinafter also referred to as &quot; monofunctional (meth) acrylic acid ester compound (C1) &quot;), or an ethylene It is preferable to use the unsaturated compound (C2) (hereinafter also referred to as &quot; nitrogen-containing monofunctional unsaturated compound (C2) &quot;).

(Meth) acrylate (C1-1), alicyclic (meth) acrylate (C1-2), aromatic (meth) acrylate (C1- 3) and oxyalkylene-modified compounds (C1-4) of these (meth) acrylates.

Examples of the long-chain aliphatic (meth) acrylate (C1-1) include decane (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, (Meth) acrylate, isostearyl (meth) acrylate, isodecyl (meth) acrylate, isodecyl (Meth) acrylate, and the like.

Examples of the alicyclic (meth) acrylate (C1-2) include isobonyl (meth) acrylate, dicyclopentanyl (meth) acrylate and dicyclopentenyl (meth) acrylate.

As the aromatic (meth) acrylate (C1-3), there can be mentioned, for example, biphenyl (meth) acrylate, naphthalene (meth) acrylate, 2- Chloro-2-hydroxypropyl (meth) acrylate, and the like.

Examples of the oxyalkylene-modified compounds (C1-4) of (C1-1) to (C1-3) include the following.

(Meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate (meth) acrylate, , Alkylpolyethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, alkylene glycol monoalkyl ester (meth) acrylate, and alkylene glycol mono (meth) acrylate.

(Meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, Dicyclopentanyloxyethyl (meth) acrylate, and the like.

(Meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, phenyltriethylene glycol (meth) acrylate, (Meth) acrylate, nonphenyloxyethyl (meth) acrylate, nonylphenol ethylene oxide modified (repeat 4) (meth) acrylate, nonylphenol ethylene oxide modified And the like.

Among these monofunctional (meth) acrylic acid ester compounds (C1), long-chain aliphatic (meth) acrylates (C1-1), alicyclic (meth) acrylates (C1-2) (C1-4) of the oxyalkylene structure-modified compound (C1-4) is preferably used from the viewpoint that the adhesive force can be stably obtained, and particularly preferable is isomyristyl acrylate, isotridecyl acrylate, isostearyl Aryl acrylate, phenyldiethylene glycol acrylate, and dicyclopentenyloxyethyl acrylate.

The nitrogen-containing monofunctional unsaturated compound (C2) can be used to improve the adhesive strength of the pressure-sensitive adhesive, and examples thereof include acrylamide, methacrylamide, butoxymethylacrylamide, hydroxyethyl acrylamide, Amide, and diacetone acrylamide, N-acryloyloxyethylhexahydrophthalimide, acryloylmorpholine, oxazolidone acrylate, and the like. Among these, (meth) acrylamide- The use of the (meth) acrylamide-based unsaturated monomer is preferable from the viewpoint of excellent balance of volatility and adhesion performance, and particularly preferable is butoxymethyl acrylamide and diacetone acrylamide.

Among them, in the present invention, it is preferable to use a long-chain aliphatic acrylate (C1-1) from the viewpoint of obtaining an optically transparent pressure-sensitive adhesive layer which is hardly colored and can impart hydrophobicity to the pressure- Iso-myristyl acrylate, isotridecyl acrylate, isostearyl acrylate, and 2-decyl tetradecanyl acrylate.

As described later, the monofunctional unsaturated compound (C) is cured by using at least one of an active energy ray and heat. The monofunctional unsaturated compound (C) is present as a polymer in the pressure-sensitive adhesive layer. However, It is preferable to select the monofunctional unsaturated compound (C) to be 80 to 80 ° C.

Such a glass transition temperature is particularly preferably -60 to 40 占 폚, more preferably -55 to 10 占 폚, particularly preferably -20 to 0 占 폚. When the glass transition temperature is too high, the adhesion performance tends to be hardly exhibited, while when it is too low, the cohesive strength tends to decrease.

The glass transition temperature is calculated by the above-described Fox equation.

Further, the monofunctional unsaturated compound (C) has an effect of softening the pressure-sensitive adhesive and improving the dryness at the time of coating with an organic solvent. In the case of coating drying (in particular, drying at the time of coating with a thick film) Those which are hard to volatilize as compared with the solvent and easily remain in the pressure-sensitive adhesive layer are used.

The monofunctional unsaturated compound (C) preferably has a flash point of 40 占 폚 or higher, particularly preferably 80 占 폚 or higher, more preferably 100 占 폚 or higher, furthermore 140 占 폚 or higher. If the flash point is too low, it tends to volatilize in the drying process. Normally, the upper limit of the flash point is 350 占 폚.

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

If the molecular weight is too large, the adhesive property tends to deteriorate. If the molecular weight is too small, it tends to be easily volatilized in the drying step.

<Adhesive sheet>

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a crosslinked product of a crosslinkable agent (B) with an acrylic resin (A) having a specific glass transition temperature and a monofunctional unsaturated compound (C).

The content of the monofunctional unsaturated compound (C) in the pressure-sensitive adhesive layer is preferably 5 to 70% by weight, more preferably 9 to 50% by weight, further preferably 12 to 40% Is preferably 15 to 30% by weight.

When the content of the monofunctional unsaturated compound (C) is too small, the stepwise followability tends to decrease. When the content is too large, the modulus of elasticity at the time of sheet formation tends to be too low, and the handling property and the stability of the coating film tend to deteriorate.

The content of the monofunctional unsaturated compound (C) is a value obtained as a content of the monofunctional unsaturated compound (C) in the whole pressure-sensitive adhesive composition after the organic solvent constituting the pressure-sensitive adhesive layer is dried and removed.

The pressure-sensitive adhesive layer may be obtained by crosslinking the functional group-containing acrylic resin (A) and the crosslinking agent (B), followed by blending the monofunctional unsaturated compound (C), or by blending monofunctional unsaturated compound (C) (A) and the crosslinking agent (B) may be crosslinked in the presence of the compound (C) in the presence of the monofunctional unsaturated compound (C) It is preferable that the acrylic resin (A) and the crosslinking agent (B) are crosslinked.

(B) and the monofunctional unsaturated compound (C) are used in combination with the acrylic resin (A) containing a functional group and the monofunctional unsaturated compound (C ) Is preferably from 50:50 to 95: 5 (weight ratio), more preferably from 65:35 to 90: 9 and further preferably from 70:30 to 85:15.

If the blending amount of the monofunctional unsaturated compound (C) relative to the acrylic resin (A) containing a functional group is too large, the stability of the coating film tends to deteriorate.

The blending amount of the crosslinking agent (B) and the amount of the monofunctional unsaturated compound (C) is preferably 0.1: 99.9 to 20:80 (by weight), more preferably 0.3: 99.7 to 2:98, 99.0.

When the blending amount of the monofunctional unsaturated compound (C) relative to the blending amount of the crosslinking agent (B) is too large, the stability of the coating film tends to deteriorate.

In the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer may contain an ethylenically unsaturated compound (C) (D) (hereinafter, may be abbreviated as "polyfunctional unsaturated compound (D)") is preferable from the viewpoint that the cohesive force of the entire pressure-sensitive adhesive layer can be adjusted. From the viewpoint of stabilizing the reaction at the time of preliminary irradiation and / or heating.

Examples of the polyfunctional unsaturated compound (D) include ethylenically unsaturated monomers containing two or more ethylenic unsaturated groups in one molecule, for example, bifunctional monomers, monomers having three or more functionalities, urethane (meth) acryl An epoxy (meth) acrylate compound, and a polyester (meth) acrylate compound may be used. Among these, it is preferable to use an ethylenically unsaturated monomer or a urethane (meth) acrylate-based compound from the viewpoint of excellent stability of the curing speed and physical properties.

As the bifunctional monomer, any monomer may be used as long as it is a monomer containing two ethylenic unsaturated groups, and examples thereof include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (Meth) acrylate, propylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethylene oxide modified bisphenol A type (meth) acrylate, propylene oxide modified bisphenol A (Meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol di (Meth) acrylates such as glycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, phthalic acid diglycidyl ester di (meth) acrylate, hydroxypivalic acid modified neopentyl glycol di ) Acrylate, isocyanuric acid ethylene oxide-modified diacrylate, and 2- (meth) acryloyloxyethyl acid phosphate diester.

The monomer having three or more functional groups may be a monomer containing three or more ethylenic unsaturated groups. Examples thereof include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (Meth) acrylate, tri (meth) acryloyloxyethoxy trimethylol propane, glycerin polyglycidyl ether poly (meth) acrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate, ethylene oxide modified dipentaerythritol (Meth) acrylate, ethylene oxide-modified dipentaerythritol hexa (meth) acrylate, ethylene oxide-modified pentaerythritol tri L) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, succinic acid-modified pentaerythritol tri (meth) acrylate.

As the urethane (meth) acrylate compound, a (meth) acrylic compound and a polyisocyanate compound (polyol compound, if necessary) having a urethane bond in the molecule and being a hydroxyl group- , And those obtained by reacting by the method of the general public can be used. The weight average molecular weight of the urethane (meth) acrylate compound is usually 300 to 4000.

The content of the polyfunctional unsaturated compound (D) in the pressure-sensitive adhesive layer is preferably 20 to 0.1 wt%, more preferably 10 to 0.2 wt%, further preferably 5 to 0.3 wt% 0.5% by weight.

If the content of the polyfunctional unsaturated compound (D) is too small, the reliability upon curing by irradiation with active energy rays tends to deteriorate. If too large, the cohesive force when cured by active energy ray irradiation becomes too high Curing shrinkage occurs and the adhesive performance tends to be lowered.

The content of the polyfunctional unsaturated compound (D) is a value obtained as a content of the polyfunctional unsaturated compound (D) in the whole pressure-sensitive adhesive composition after drying and removing the organic solvent constituting the pressure-sensitive adhesive layer.

The content of the polyfunctional unsaturated compound (D) in the pressure-sensitive adhesive layer is preferably 0.01 to 50 parts by weight, particularly preferably 0.5 to 20 parts by weight, more preferably 0.5 to 20 parts by weight, per 100 parts by weight of the monofunctional unsaturated compound (C) Is 1 to 5 parts by weight. If the content of the polyfunctional unsaturated compound (D) is too large, the cohesive force is excessively increased in the post-curing step to cause curing shrinkage, which tends to deteriorate the adhesive performance, and if too small, the retention force tends to become insufficient.

(A), the cross-linking agent (B) and the monofunctional unsaturated compound (C) are used again in the acrylic resin (A) containing the functional group and the polyfunctional unsaturated compound D) is preferably from 0.01 to 50 parts by weight, particularly preferably from 0.1 to 30 parts by weight, more preferably from 0.5 to 20 parts by weight, further preferably from 1 to 20 parts by weight, based on 100 parts by weight of the acrylic resin (A) 5 parts by weight is preferable. If the blending amount of the polyfunctional unsaturated compound (D) is too large, the cohesive force becomes too high in the post-curing step to cause curing shrinkage and tackiness tends to deteriorate, while if too small, the retention force tends to become insufficient.

As the polymerization initiator (E), various polymerization initiators such as a photopolymerization initiator (e1) and a thermal polymerization initiator (e2) can be used. In particular, the use of a photopolymerization initiator (e1) From the viewpoint of enabling curing by irradiation with active energy rays such as ultraviolet rays.

It is also preferable to use both of them in combination if necessary.

As the photopolymerization initiator (e1) and the thermal polymerization initiator (e2), known polymerization initiators may be used. Examples of the photopolymerization initiator (e1) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyldimethylketal, 4- (2- hydroxyethoxy) (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan- Acetophenones such as 1- (4-morpholinophenyl) butanone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin Benzoin such as methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl- Sulfide, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, (1-oxo-2-propenylox Benzophenones such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, and 2-isopropylthioxanthone; 2-hydroxy-3, 4-dimethyl-9H-thioxanthone-9-one (2, 6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (trimethylbenzoyl) 2,4,6-trimethylbenzoyl) -phenylphosphine oxide; and the like. These photopolymerization initiators (e1) may be used singly or in combination of two or more.

Examples of these auxiliary agents include triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Mihira ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid ethyl , 4-dimethylaminobenzoic acid (n-butoxy) ethyl, 4-dimethylaminobenzoic acid isoamyl, 4-dimethylaminobenzoic acid 2-ethylhexyl, 2,4-diethylthioxanthone, It is also possible to use a combination of thioxanthone and the like.

Among these, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy- 2-methyl-1-phenylpropan-1-one is preferably used.

Examples of the thermal polymerization initiator (e2) include methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetylacetate peroxide, 1,1-bis -Hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -cyclohexane, 1,1-bis (T-butylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1- Bis (4,4-di-t-butylperoxycyclohexyl) propane, p-menthane hydroperoxide, di Isopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexylhydroperoxide, t-butyl hydroperoxide,?,? '- bis (t Butylperoxy) diisopropylbenzene, dicumylperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylcumylperoxide, di- Dimethyl-2,5-bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, Di-n-propyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-n-propyl peroxydicarbonate, di Di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutylperoxydicarbonate, di-s-butylperoxydicarbonate, di (3-methyl- Peroxybutyl) peroxydicarbonate,?,? '- bis (neodecanoylperoxy) diisopropyl 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, Decanoate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate , 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, 2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxyisopropylmonocarbonate, t-butylperoxyisobutyrate, t-butylperoxymaleate, t-butyl Peroxy-3,5,5-trimethohexanoate, t-butylperoxy laurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl Butyl peroxybenzoate, t-butyl peroxybenzoate, bis (t-butylperoxy) isophthalate, 2,5-dimethyl-2,5 T-butylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyallyl monocarbonate, t-butyltrimethyl Organic peroxide initiators such as silyl peroxide, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone and 2,3-dimethyl-2,3-diphenylbutane; (1-cyano-1-methylethyl) azo] formamide, 1,1'-azobis (cyclohexane-1-carbonitrile Azobis (2-methylbutylonitrile), 2,2'-azobisisobutylonitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2'-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] di Azobis [2-methyl-N- (phenylmethyl) -2-methylpropionamidine] dihydrochloride, 2,2'- (2-methyl-N- (2-propenyl) propionamidine] dihydrochloride, 2,2'-azobis [N- 2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin2- yl) propane] dihydrochloride, 2,2'- Azobis [2- (4,5,6,7-tetrahydro-1H-1,3-benzodiazepin-2-yl) propane] dihydrochloride, Diazepin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (3,4,5,6-tetra Dihydrochloride, 2,2'-azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) propane] di Azo compounds such as 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2'- (2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, and 2,2'- Azo bis [2-methyl-N- (1,1-bis (hydroxymethyl) ethyl] propionamide}, 2,2'- Ethyl) propionamide], 2,2'-azobis (2-methylpropionamide), 2,2'-azobis (2,4,4-trimethylpentane), 2,2'- Azobis (2-methylpropionate), 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis [2- (hydroxymethyl) The Azo-based initiators such as triphenylphosphine and triphenylphosphine; These thermal polymerization initiators (e2) may be used alone, or two or more of them may be used in combination.

The content of the polymerization initiator (E) in the pressure-sensitive adhesive layer is preferably 100 parts by weight (100 parts by weight in total of (C) and (D) when the polyfunctional unsaturated compound (D) , Particularly preferably from 0.1 to 20 parts by weight, more preferably from 0.3 to 12 parts by weight, particularly preferably from 0.5 to 5 parts by weight. If the content of the polymerization initiator (E) is too small, the curability tends to be insufficient and the physical properties become unstable. If the content of the polymerization initiator (E) is too large,

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on a base sheet, a double-sided pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on a releasable sheet, Sheet, and the like, but a substrate-less double-sided pressure-sensitive adhesive sheet is preferable from the viewpoint of excellent transparency and high adhesion to a constituent thickness.

Examples of the method for producing the pressure-sensitive adhesive sheet of the present invention include a method in which an acrylic resin (A) containing a functional group, a crosslinking agent (B), and a monofunctional unsaturated compound (C) are contained as essential components, (D) and a polymerization initiator (E) are coated on a base sheet or a release sheet, dried, and cured if necessary, to obtain a pressure-sensitive adhesive sheet containing a functional group-containing acrylic resin (A) (B) and a pressure-sensitive adhesive layer containing a monofunctional unsaturated compound (C) are obtained.

In the case of a substrate-less double-sided pressure-sensitive adhesive sheet, for example, after forming a pressure-sensitive adhesive layer obtained by coating a pressure-sensitive adhesive composition on a release sheet and drying, another release sheet is bonded onto the side of the pressure- And can be produced by curing if necessary.

Examples of the base sheet include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate and polyethylene terephthalate / isophthalate copolymer; polyolefins such as polyethylene, polypropylene and polymethylpentene; (Cyclic olefin polymer; manufactured by JSR Corporation), trade name "Zeonoa (cyclic olefin polymer; manufactured by Nippon Zeon Co., Ltd.)", and the like; polyvinyl fluoride, poly Polyvinylidene fluoride, polyvinylidene fluoride, and polyfluorinated ethylene; polyamides such as nylon 6, nylon 6 and 6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene- Polyvinyl alcohol, and vinylon; cellulose-based resins such as cellulose triacetate, cellophane, and the like; Acrylic resin such as polymethyl methacrylate, ethyl polymethacrylate, ethyl polyacrylate and butyl polyacrylate, synthetic resin sheets such as polystyrene, polycarbonate, polyarylate and polyimide, metal foil of copper, iron, Paper, glasinji paper, glass fibers, natural fibers, synthetic fibers, and the like. These base sheets can be used as a single layer body or as a multi-layer body in which two or more kinds of layers are laminated.

As the substrate sheet, a transparent electrode film such as an ITO (indium tin oxide) electrode film or an organic conductive film such as Cu mesh, Ag mesh, Ag nanofibers, or polythiophene, or the above various substrates including an electrode film, An optical member such as a retardation plate, an elliptically polarizing plate, an optical compensation film, a luminance improving film, an electromagnetic wave shielding film, a near infrared absorbing film, and an AR (anti reflection) film may be used.

As the release sheet, those obtained by subjecting to various synthetic resin sheets, paper, cloth, non-woven fabric and the like exemplified in the base sheet can be used. For example, silicone release sheet, olefin release sheet, fluorine release sheet, A release sheet of an alkyd type, and a release sheet of an alkyd type.

As a coating method of the pressure-sensitive adhesive composition, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater and a spray coater can be used.

As the drying conditions, the drying conditions are usually 50 to 250 캜, preferably 60 to 120 캜, and more preferably 65 to 95 캜. The drying time is usually 10 seconds to 10 minutes.

As the condition of the curing treatment, the temperature is usually from room temperature to 70 ° C, and the time is usually from 1 day to 30 days. Specifically, for example, the curing treatment is carried out at 23 ° C for 1 day to 20 days, preferably at 23 ° C for 3 to 10 days , 40 占 폚 for 1 day to 7 days, and the like.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is preferably 5 to 300 占 퐉, particularly preferably 10 to 250 占 퐉, more preferably 25 to 200 占 퐉, particularly preferably 50 to 175 占 퐉. If the thickness of the pressure sensitive adhesive layer is too thin, the step following property tends to decrease. If it is too thick, the thickness of the entire optical member tends to increase too much.

In particular, when a pressure-sensitive adhesive layer of a thick film is to be obtained, it is preferable to coat it with a film thickness of 10 m or more, particularly preferably 50 m or more, and more preferably 100 m or more. Is usually 800 mu m.

The film thickness is a value obtained by using &quot; ID-C112B &quot; manufactured by Mitsutoyo Corporation and subtracting the measured value of the thickness of the constituent members other than the pressure-sensitive adhesive layer from the measured value of the thickness of the whole pressure sensitive adhesive sheet.

The gel fraction of the pressure sensitive adhesive sheet of the pressure sensitive adhesive sheet (before curing by active energy ray irradiation and / or heating) of the present invention is preferably 5 to 60%, more preferably 10 to 50% , Particularly preferably 20 to 45%. When the gel fraction is too low, the pressure-sensitive adhesive sheet tends to become scratched by the foreign matter or the pressure-sensitive adhesive sheet to be stretched due to the decrease of the cohesive force. If the gel fraction is too high, the stepwise followability is lowered due to the increase of the cohesive force, or the adhesiveness to the adherend is lowered, and the blister resistance tends to deteriorate.

The gel fraction of the pressure-sensitive adhesive layer after curing by activation energy ray irradiation and / or heating of the pressure-sensitive adhesive sheet of the present invention is preferably from 10 to 95%, more preferably from 20 to 90% , Further preferably 30 to 80%. If the gel fraction is too low, the durability of the pressure-sensitive adhesive layer tends to deteriorate due to a decrease in the cohesive force. If the gel fraction is too high, adhesion with the interface tends to be lowered due to an increase in the cohesive force.

The gel fraction is a standard for the degree of crosslinking (degree of curing), and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (without a separator) having a pressure-sensitive adhesive layer formed on a base polymer sheet (e.g., a polyethylene terephthalate film) was wrapped with a 200 mesh SUS wire net, The weight percentage of the insoluble adhesive component remaining in the wire net after immersion for 24 hours is regarded as the gel fraction. However, the weight of the base material shall be omitted.

Since the pressure-sensitive adhesive sheet of the present invention thus obtained contains a monofunctional unsaturated compound (C) in addition to the crosslinked product of the acrylic resin (A) containing a functional group having a specific glass transition temperature and the crosslinking agent (B) Since the unsaturated compound (C) imparts a plasticizing effect to the pressure-sensitive adhesive, the modulus of elasticity of the pressure-sensitive adhesive layer is lowered, so that the pressure-sensitive adhesive layer exhibits excellent followability to the step (unevenness) of the adherend. Further, since the glass transition temperature of the acrylic resin (A) containing a functional group is higher than usual, the content of the crosslinking agent can be reduced, and therefore the deterioration of the adhesiveness due to thermal crosslinking of the acrylic resin can be minimized.

After the adhesion of the adherend, it is possible to polymerize the monofunctional unsaturated compound (C) contained in the pressure-sensitive adhesive layer and to firmly adhere to the adherend by irradiating the pressure-sensitive adhesive layer with active energy rays and / It will be.

As a method of bonding the pressure-sensitive adhesive sheet to an adherend, for example, a pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is applied to an adherend, Min) is carried out.

In the present invention, when the pressure-sensitive adhesive layer is cured by irradiation with active energy rays, it is possible to use a transparent material for at least one of the substrate sheet and the adherend, and to conduct active energy ray irradiation from such a transparent surface.

The active energy rays may be irradiated in addition to electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays and infrared rays, X rays and γ rays, electron beams, It is advantageous to cure by irradiation with ultraviolet rays. In addition, when electron beam irradiation is carried out, curing is possible without using the photopolymerization initiator (e1).

A metal halide lamp, a chemical lamp, a black light, an LED lamp, or the like is used as a light source for irradiating the ultraviolet ray, such as a high pressure mercury lamp, an electrodeless lamp, a super high pressure mercury lamp or the like, or a xenon lamp. In the case of the high-pressure mercury lamp, for example, 5 to 3000 mJ / cm 2, preferably 50 to 2000 mJ / cm 2. In the case of the electrodeless lamp, it is performed under the condition of, for example, 2 to 2000 mJ / cm 2, preferably 10 to 1000 mJ / cm 2. The irradiation time varies depending on the kind of the light source, the distance between the light source and the coated surface, and the conditions after the coating, but usually it may be several seconds to several tens of seconds, and sometimes a fraction of a second. On the other hand, in the case of electron beam irradiation, for example, it is preferable to use an electron beam having an energy in the range of 50 to 1000 Kev to make an irradiation dose of 2 to 50 Mrad.

When the pressure-sensitive adhesive layer is cured by heat, the polymerization reaction is initiated and proceeded by heating using the thermal polymerization initiator (e2) as the polymerization initiator (E). The treatment temperature and the treatment time at the time of curing by heating are different depending on the type of the thermal polymerization initiator (e2) to be used and usually calculated by the half life of the initiator, but the treatment temperature is preferably 70 to 170 DEG C, The treatment time is usually 0.2 to 20 minutes, preferably 0.5 to 10 minutes.

In this manner, the pressure-sensitive adhesive sheet of the present invention is attached to an adherend, and at least one of the active energy ray irradiation and the heating is performed to form a laminate (hereinafter referred to as &quot; (Adherend / pressure-sensitive adhesive layer / substrate sheet) or a substrate-less pressure sensitive adhesive sheet (adherend / pressure-sensitive adhesive layer / adherend).

Examples of the adherend include, but are not limited to, a transparent electrode film such as an ITO film, a Cu mesh, an organic conductive film such as Ag nanofiber or polythiophene, a polarizing plate, a retardation plate, an elliptically polarizing plate, , A brightness enhancement film, an electromagnetic wave shield film, a near-infrared absorbing film, and an AR (anti-reflection) film. Particularly, it is preferable that the adhesive having a step on the surface exhibits the effect of the pressure-sensitive adhesive sheet excellent in followability of the present invention remarkably. For example, it is preferably 1 to 100 탆, particularly 3 to 50 탆, The surface of the substrate having the step difference is also excellent in followability.

In the pressure-sensitive adhesive sheet of the present invention, it is preferable that the pressure-sensitive adhesive layer has a storage elastic modulus of 1.0 x 10 ^{3 to} 1.0 x 10 ⁵ at 23 ° C and 1 Hz, and tan δ at 50 ° C and 1 Hz of 0.5 to 0.7.

It is also preferable that the storage elastic modulus of the pressure-sensitive adhesive layer after curing with an active energy ray and / or heat is not less than 1.0 x 10 ⁴ at 23 ° C and 1 Hz, and tan δ at 50 ° C and 1 Hz is less than 0.5.

The pressure-sensitive adhesive sheet of the present invention can be applied to various fields such as glass, ITO transparent electrode sheet, optical sheets such as polyethylene terephthalate (PET), polycarbonate (PC), polymethylmethacrylate (PMMA), polarizing plate, retardation plate, And is useful for attaching an optical member such as a film. Further, it can be suitably used for an image display apparatus such as a touch panel including these optical members.

(Example)

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In the examples, &quot; part &quot; and &quot;% &quot;

First, a solution of the acrylic resin (A) 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 acrylic resin (A) containing a functional group was carried out according to the above-mentioned method.

For measurement of the solid content concentration, 1 to 2 g of the functional group-containing acrylic resin (A) solution was taken on an aluminum foil and heated and dried for 45 minutes in a blanket (infrared drier, 185 W, height 5 cm) And the viscosity was measured in accordance with 4.5.3 rotation viscometer method of JIS K 5400 (1990).

[Preparation of solution of functional group-containing acrylic resin (A)]

[Functional group-containing acrylic resin (A-1)]

Ethyl hexyl acrylate (a2) 29 parts, 2-hydroxyethyl acrylate (a1) 30 parts, and 2-ethylhexyl acrylate (a1) were placed in a four-necked round bottom flask equipped with a stirrer, a nitrogen gas inlet, 15 parts of ethylhexyl methacrylate (a2-2), 15 parts of isostearyl acrylate (a2-2), 11 parts of tert-butyl methacrylate (a2-1) and 8 parts of acetone, methyl ethyl ketone 41 (AIBN) as a polymerization initiator was added thereto, and the mixture was reacted at a methyl ethyl ketone refluxing temperature for 3 hours. Thereafter, 0.02 part of azobisisobutyronitrile (AIBN) And 3 parts of ethyl acetate were added. The mixture was further reacted for 4 hours and diluted with ethyl acetate to obtain an acrylic resin solution. Methacryloyloxyethyl isocyanate (0.03 part) was added to 100 parts of the obtained acrylic resin solution (resin component) and reacted at 50 ° C for 12 hours to obtain an ethylenically unsaturated group in the side chain in an amount of 0.13 mol% (Weight average molecular weight: 29.6 million, dispersion degree: 3.72, glass transition temperature: -25.4 占 폚, solid content: 60%, viscosity: 12,000 mPa 占 퐏 (25 占 폚)).

[Functional group-containing acrylic resin (A-2)]

50 parts of 2-ethylhexyl acrylate (a2), 30 parts of 2-hydroxyethyl acrylate (a1), 30 parts of tert-butyl acrylate (a1) , 20 parts of butyl methacrylate (a2-1) and 76 parts of ethyl acetate were added, and after starting to reflux, 0.04 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator was added, and after 3 hours of reaction at the ethyl acetate reflux temperature , 0.02 part of azobisisobutyronitrile (AIBN) and 3 parts of ethyl acetate were added to the reaction mixture, followed by further reaction for 3 hours. The mixture was diluted with ethyl acetate to obtain an acrylic resin solution. Methacryloyloxyethyl isocyanate (0.03 part) was added to 100 parts of the obtained acrylic resin solution (resin component) and reacted at 50 占 폚 for 12 hours to add 0.08 mole% of an ethylenic unsaturated group to the side chain (Weight average molecular weight: 62.2 million, dispersion degree: 4.95, glass transition temperature: -32.2 占 폚, solid content: 49.1%, viscosity: 16,000 mPa 占 퐏 (25 占 폚)) was obtained.

[Functional group-containing acrylic resin (A'-1)]

70 parts of 2-ethylhexyl acrylate (a2), 30 parts of 2-hydroxyethyl acrylate (a1) and 10 parts of 2-ethylhexyl acrylate (a1) were placed in a four-neck round bottom flask equipped with a stirrer, a nitrogen gas inlet, After heating and refluxing was started, 150 parts of ethyl acetate was added, and 0.04 part of azobisisobutyronitrile (AIBN) as a polymerization initiator was added. After reacting at an ethyl acetate reflux temperature for 3 hours, it was diluted with ethyl acetate to obtain an acrylic resin solution. Methacryloyloxyethyl isocyanate (0.03 part) was added to 100 parts of the obtained acrylic resin solution (resin component) and reacted at 50 DEG C for 12 hours to obtain an ethylenically unsaturated group in the side chain in an amount of 0.17 mol% (Having a weight average molecular weight of 69.1, a dispersion degree of 4.99, a glass transition temperature of -56.1 占 폚, a solid content of 51.7%, and a viscosity of 20,000 mPa 占 퐏 (25 占 폚)).

With respect to the acrylic resin (A-1), (A-2) and (A'-1) containing the functional group prepared as described above, the content of the raw material monomer component, the glass transition temperature when the raw material monomer component was used as the homopolymer , The weight average molecular weight, the degree of dispersion, and the viscosity of the acrylic resin containing a functional group are shown in Table 1 below.

The abbreviations in Table 1 represent the following compounds.

HEA: 2-hydroxyethyl acrylate

2EHA: 2-ethylhexyl acrylate

tBMA: tert-butyl methacrylate

2EHMA: 2-ethylhexyl methacrylate

ISTA: Isostearyl acrylate

[Crosslinking agent (B)]

As the crosslinking agent (B-1), the following were prepared.

A 55% ethyl acetate solution of a tolylene diisocyanate adduct of trimethylol propane ("Colonate L-55E", manufactured by Nippon Polyurethane Industry Co., Ltd.)

[Monofunctional unsaturated compound (C)]

The following monofunctional unsaturated compound (C) was prepared.

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

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

(C1-1 c) Isostearyl acrylate ("ISTA" manufactured by Osaka Yuki Kagaku Kogyo Co., Ltd.)

[Multifunctional unsaturated compound (D)]

The following polyfunctional unsaturated compound (D-1) was prepared.

Trimethylolpropane triacrylate (TMPTA)

[Polymerization initiator (E)]

The following polymerization initiator (E-1) was prepared.

A mixture of 1-hydroxycyclohexyl phenyl ketone and benzophenone (1: 1) ("Irgacure 500" manufactured by Chiba Japan)

&Lt; Example 1 &gt;

0.2 part of a crosslinking agent (B-1), 40 parts of a monofunctional unsaturated compound (C-1) and 1 part of a polyfunctional unsaturated compound (D-1) were added to 100 parts (resin component) of the acrylic resin (A- , And 1 part of a photopolymerization initiator (E-1) were blended to prepare a pressure-sensitive adhesive composition solution.

The pressure-sensitive adhesive composition solution was applied to a polyester release sheet so that the thickness after drying was 100 占 퐉 and dried at 90 占 폚 for 5 minutes to form a pressure-sensitive adhesive layer. The resulting pressure-sensitive adhesive layer was sandwiched between polyester-type release sheets and aged for 3 days under a condition of 40 캜 to obtain a substrate-less double-faced pressure-sensitive adhesive sheet [I-1].

Further, the release sheet on one side was peeled off from the pressure-sensitive adhesive layer of the base-less pressure sensitive adhesive sheet obtained above and pressed against a reverse-adhered polyethylene terephthalate (PET) sheet having a thickness of 125 m to obtain a pressure- Thereby obtaining a PET sheet [II-1] containing a pressure-sensitive adhesive layer.

Further, a release sheet on one side was peeled off from the pressure-sensitive adhesive layer of the baseless double-side pressure-sensitive adhesive sheet and pressed against a polyethylene terephthalate (PET) sheet having a thickness of 50 占 퐉 to obtain a pressure- To obtain a PET sheet [III-1].

&Lt; Example 2, Comparative Examples 1 and 2 &gt;

I-2], [I'-1], and [I'-2] were obtained in the same manner as in Example 1 except that the mixing ratios of the components (A) [II'-1], [II'-2], [III-2], [III'-1], and [III'- -2].

&Lt; Example 3 &gt;

Except that the compositional ratio of the components (A) to (E) was changed to the blend ratio shown in Table 2 and the thickness after drying was 160 占 퐉, the thickness of the pressure- II-3] and [III-3] containing a substrate-less double-faced pressure-sensitive adhesive sheet [I-3] and a pressure-sensitive adhesive layer.

The gel fraction of the pressure-sensitive adhesive layer, the optical properties of the pressure-sensitive adhesive layer, and the blister resistance were measured using the above-described base-printed sheets [I-1] to [I- Respectively. The adhesive strength of the pressure-sensitive adhesive layer was measured using the PET sheets [II-1] to [II-3], [II'-1] and [II'-2] . The humidity resistance of the pressure-sensitive adhesive layer was evaluated using the PET sheets [III-1] to [III-3], [III'-1] and [III'-2] containing the pressure-sensitive adhesive layer. The results are shown in Table 3 below.

[Ultraviolet ray pre-gel fraction]

The substrateless double-faced pressure-sensitive adhesive sheets [I-1] to [I-3], [I'-1] and [I'-2] were each cut into 40 mm x 40 mm, Left for 30 minutes. Thereafter, one release sheet was peeled off, the pressure sensitive adhesive layer side was stuck to a SUS mesh sheet (200 mesh) of 50 mm x 100 mm, and the other release sheet was peeled off again, , And then the gel fraction (%) was measured at a change in weight when the sample was immersed in a sealed container containing 250 g of toluene for 24 hours.

[Gel fraction after ultraviolet irradiation]

Each of the base materialless double-faced pressure-sensitive adhesive sheets [I-1] to [I-3], [I'-1] and [I'-2] was cut to a size of 40 mm x 40 mm, (500 mJ / cm &lt; 2 &gt; × 2 passes) under the conditions of 23 ° C. × 50% RH for 30 minutes. Thereafter, one release sheet was peeled off, the pressure-sensitive adhesive layer side was stuck to a SUS mesh sheet (200 mesh) of 50 mm x 100 mm, and the other release sheet was peeled off, After the folded sample was wrapped, the gel fraction (%) was measured at a change in weight when the sample was immersed in a sealed container containing 250 g of toluene for 24 hours.

[Adhesion (Initial Adhesion)]

The PET films [II-1] to [II-3], [II'-1] and [II'-2] containing the pressure-sensitive adhesive layer were cut to a width of 25 mm and a length of 100 mm, respectively, , And the pressure-sensitive adhesive layer side was pressure-bonded to a non-alkali glass under an atmosphere of 23 占 폚 and relative humidity of 50% for 2 reciprocations of 2 kg rubber rollers and left for 30 minutes in an atmosphere at 23 占 폚 and a relative humidity of 50% (N / 25 mm) was measured.

[Adhesion (adhesion after curing)]

The PET films [II-1] to [II-3], [II'-1] and [II'- 2] containing the above pressure sensitive adhesive layer were cut to a width of 25 mm and a length of 100 mm, The pressure-sensitive adhesive layer side was pressure-bonded to an alkali-free glass in two rounds of 2 kg rubber rollers under an atmosphere of 23 캜 and 50% relative humidity, and subjected to a pressure heating treatment at 50 캜 for 0.5 MPa for 20 minutes in an autoclave. Thereafter, ultraviolet irradiation was performed (500 mJ / cm 2 x 2 passes) at a peak illuminance of 150 mW / cm 2 and an integrated exposure amount of 1,000 mJ / cm 2 by a high-pressure mercury UV irradiator from the PET film side, After leaving for 30 minutes, the 180 degree peel strength (N / 25 mm) was measured at a peeling speed of 300 mm / min at room temperature.

[Steps followability]

PET films of 25 mu m, 38 mu m, 50 mu m, 70 mu m, and 100 mu m were fixed with cellophane tape, respectively, on the alkali-free glass to prepare glass having a step difference. The PET sheets [II-1] to [II-3], [II'-1] and [II'-2] containing the pressure- % Atmosphere, and subjected to a pressurizing heat treatment at 50 占 폚 for 0.5 MPa 占 20 minutes with an autoclave. Thereafter, ultraviolet ray irradiation was performed (500 mJ / cm 2 x 2 passes) at a peak illuminance of 150 mW / cm 2 and an integrated exposure amount of 1000 mJ / cm 2 by a high-pressure mercury UV irradiator from the PET film side, After standing for 30 minutes, the followability to the step was visually evaluated as follows.

(evaluation)

◎ · · · Chewing and lifting of air could not be confirmed at the stepped portion.

○ · · A little chewing of the air can be confirmed in a part of the stepped portion, but lifting can not be confirmed.

△ ... It was confirmed that air was chewed and lifted in a part of the stepped portion.

× ··········································································································.

[Measurement of Optical Properties of Pressure-Sensitive Adhesive Layer]

[Production of sample for optical measurement]

The substrateless double-faced pressure-sensitive adhesive sheets [I-1] to [I-3], [I'-1] and [I'-2] were cut to a size of 25 mm x 25 mm, (500 mJ / cm &lt; 2 &gt; × 2 passes) at an exposure dose of 150 mW / cm 2 and an integrated exposure dose of 1000 mJ / cm 2. Thereafter, the release sheet on one side was peeled from the pressure-sensitive adhesive layer, and the side of the pressure-sensitive adhesive layer was stuck to a slide glass (Eagle XG, manufactured by Corning Incorporated) and subjected to autoclave treatment (50 DEG C, 0.5 MPa, 20 minutes) And allowed to stand for 30 minutes under conditions of 23 캜 x 50% RH. Finally, the other one of the release sheets was peeled off, and a test piece having the structure of "slide glass / pressure-sensitive adhesive layer" was produced.

The haze value and color difference b * value of the obtained test pieces were measured.

[Haze value]

The haze value was obtained by measuring the diffuse transmittance and the total light transmittance using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.), and calculating the haze by substituting the values of the obtained diffuse transmittance and total light transmittance into the following formula. In addition, this instrument conforms to JIS K 7361-1.

Haze value (%) = (diffuse transmittance (%) / total light transmittance (%)) x 100

[Color difference]

The color difference b * value was measured in accordance with JIS K 7105, and the measurement was performed using a spectral colorimeter (SE6000: manufactured by Nippon Denshoku Kogyo Co., Ltd.) under the conditions of transmission. The measurement of haze, total light transmittance and color difference b * value in the present invention is a value measured by attaching only the pressure-sensitive adhesive layer to an alkali-free glass (total light transmittance = 93, haze = 0.06, b * value = 0.16).

[Humidity Resistance]

The PET films [III-1] to [III-3], [III'-1] and [III'-2] containing the above pressure sensitive adhesive layer were cut to have a size of 25 mm x 25 mm, (Manufactured by Corning Incorporated, Eagle XG), followed by autoclave treatment (50 DEG C, 0.5 MPa, 20 minutes). Thereafter, ultraviolet ray irradiation was performed (500 mJ / cm 2 x 2 passes) at a peak illuminance of 150 mW / cm 2 and an integrated exposure amount of 1000 mJ / cm 2 by a high-pressure mercury UV irradiator from the PET film side, For 30 minutes to prepare a test piece having a configuration of &quot; slide glass / pressure-sensitive adhesive layer / PET film &quot;.

The obtained test pieces were subjected to a moisture resistance thermostability test for 168 hours under an atmosphere of 85 占 폚 and 85% RH. The haze values after the initiation of the humid heat resistance test and the humidity resistance thermostability test were measured and evaluated according to the following criteria.

The haze value was measured by the same method as the measurement of optical properties of the pressure-sensitive adhesive layer.

(evaluation)

○ · The haze value after the humid heat resistance test is less than 2.0%, and the rising ratio of the haze value before and after the humid heat resistance test is 1.2 times or less.

The haze value immediately after the humidity and humidity resistance test is less than 2.0%, and the increase ratio of the haze value before and after the humidity and humidity resistance test is greater than 1.2 times.

× · · · The haze value immediately after the humid heat resistance test is 2.0% or more.

[My Blistering]

The PET films [II-1] to [II-3], [II'-1], and [II'-2] containing the pressure-sensitive adhesive layer were cut to a size of 25 mm x 50 mm, Was attached to an untreated polycarbonate plate having a thickness of 2 mm and subjected to an autoclave treatment (50 DEG C, 0.5 MPa, 20 minutes). Subsequently, ultraviolet light irradiation (500 mJ / cm 2 x 2 passes) was performed at a peak illuminance of 150 mW / cm 2 and an integrated exposure amount of 1000 mJ / cm 2 in a high-pressure mercury UV irradiator from the PET film side, Minute, and a test piece having the configuration of "polycarbonate plate / acrylic pressure-sensitive adhesive layer / PET film" was produced.

Thereafter, the mixture was allowed to stand for 24 hours under an atmosphere of 85 DEG C x 85% RH, and the degree of blister formation before and after the standing was visually observed. The evaluation criteria are as follows.

(evaluation)

◎ ... There is no foaming.

○ ... foaming of less than 0.5 mm was observed, but foaming exceeding 0.5 mm was not observed.

△ ... Foaming exceeding φ0.5 mm occurs to less than 1/3 of the whole attached surface.

× ... Foaming exceeding φ0.5 mm occurs more than 1/3 of the whole attached side.

From the above results, the pressure-sensitive adhesive sheet of Examples 1 and 2, in which the thickness of the pressure-sensitive adhesive layer was 100 m, exhibited excellent followability to the steps of 25 m and 38 m, and the pressure- And it shows followability.

In addition, the pressure-sensitive adhesive sheet of Example 3 in which the thickness of the pressure-sensitive adhesive layer is 160 탆 exhibits excellent followability with respect to the steps of 25 탆, 38 탆 and 50 탆, and shows sufficient followability even for the step of 75 탆 . This shows satisfactory followability with respect to the step difference of about 47% with respect to the thickness of the pressure-sensitive adhesive layer, and excellent follow-up property of the same degree as that of the pressure-sensitive adhesive sheet of Example 1 showing satisfactory followability with respect to the step of 50% .

In addition, the pressure-sensitive adhesive sheets of Examples 1 to 3 are excellent in physical properties required when the pressure-sensitive adhesive sheet is used for the application of an optical member such as a touch panel, such as strong adhesive force, Able to know.

On the other hand, the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 using a functional group-containing acrylic resin (A) having a glass transition temperature lower than -35 占 폚 were found to be poor in step traceability and blister resistance.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. The present application is based on Japanese Patent Application (Application No. 2015-153476) filed on Aug. 3, 2015, the content of which is incorporated herein by reference.

The pressure-sensitive adhesive sheet of the present invention is excellent in step-following property and is excellent in adhesiveness, high light transmittance, and haze from the viewpoint that it is difficult to generate haze, such as glass or ITO transparent electrode sheet, polyethylene terephthalate (PET), polycarbonate ), And polymethylmethacrylate (PMMA), polarizing plates, retardation plates, optical compensation films, brightness enhancement films, and the like. In addition, it can be suitably used for a touch panel including these optical members.

Claims (9)

A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive sheet comprising a crosslinked product of an acrylic resin (A) containing a functional group and a crosslinking agent (B) and an ethylenically unsaturated compound (C) having one ethylenic unsaturated group, wherein the pressure- A pressure-sensitive adhesive sheet having a transition temperature of -35 캜 or higher. The method according to claim 1,
Wherein the functional group-containing acrylic resin (A) is an acrylic resin obtained by polymerizing a monomer component containing a methacrylic acid alkyl ester monomer having an alkyl group of 1 to 8 carbon atoms. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive layer has a thickness of 5 to 300 占 퐉. 4. The method according to any one of claims 1 to 3,
Sensitive adhesive sheet in which a release sheet is laminated on both sides of the pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer surface is attached to an adherend, and the pressure-sensitive adhesive layer is subjected to active energy ray irradiation and heating. The method of claim 5,
And a pressure-sensitive adhesive layer having a step difference of 1 to 100 m on the surface of the adherend. A laminate having a pressure-sensitive adhesive layer obtainable by a method for producing a laminate including the pressure-sensitive adhesive layer according to claim 5 or 6. An image display apparatus having a laminate including the pressure-sensitive adhesive layer according to claim 7. A touch panel having a laminate including the pressure-sensitive adhesive layer according to claim 7.