JP6230256B2 - Acrylic pressure-sensitive adhesive, pressure-sensitive adhesive sheet, double-sided pressure-sensitive adhesive sheet, transparent electrode pressure-sensitive adhesive, touch panel and image display device, and method for producing a pressure-sensitive adhesive layer-containing laminate - Google Patents

Description

The present invention is, A acrylic pressure-sensitive adhesives, pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet, a transparent electrode for adhesive, a touch panel, an image display device, and a method of manufacturing a pressure-sensitive adhesive layer-containing laminate, details active energy ray-curable etc. of solvent-based acrylic pressure-sensitive adhesive relate.

  An adhesive used for a touch panel or the like is mainly used for bonding a support plate having an ITO (indium tin oxide) surface and a cover panel. The conventional touch panel has a glass / adhesive / glass structure, and the adhesive is required to have excellent shock absorption and visibility, and various adhesives have been developed. By increasing the thickness of the layer, these requirements were met.

  In order to cope with such a thick film, the present applicant, as an acrylic adhesive suitable for thick coating, has an acrylic resin, an organic solvent having a specific flash point, and an ethylene having a specific flash point. An acrylic pressure-sensitive adhesive obtained from an acrylic resin composition containing a polymerizable unsaturated compound has been developed and proposed (for example, see Patent Document 1).

Recently, in order to reduce weight and reduce danger, glass has been replaced by plastic materials such as polycarbonate, and decoration has been applied by printing or the like to further improve design. Since glass has been replaced with plastic materials, there is a new problem that bubbles are generated due to gas generated from plastic materials at high temperatures, leading to a decrease in visibility. It is required to have excellent blister properties. Further, since a step due to printing or the like occurs, if the pressure-sensitive adhesive layer does not follow the step well, workability is poor, and there is a problem that air bubbles enter there and visibility is lowered. In particular, since the stress is concentrated in the frame printing part, even if the pressure-sensitive adhesive layer that follows the level difference is once formed, if it is left for a long time under high temperature and high humidity, the pressure-sensitive adhesive layer will float. There was a problem that.
In order to improve the blister resistance, the pressure-sensitive adhesive contains an acrylic polymer and a crosslinking agent, and the structural unit derived from an alkyl acrylate monomer having an alkyl group having 4 to 20 carbon atoms is 30 to 77% by mass. An adhesive containing 20 to 60% by mass of a structural unit derived from an alicyclic group-containing (meth) acrylate monomer and 0.1 to 10.0% by mass of a structural unit derived from (meth) acrylic acid has been proposed. (For example, refer to Patent Document 2).

JP 2012-111939 A JP 2012-201877 A

However, since the acrylic pressure-sensitive adhesive of Patent Document 1 is suitable for thickening the pressure-sensitive adhesive layer, the ability to follow a step has been improved by increasing the film thickness, but there is still room for improvement. There was also a need for further improvements in blister resistance.
Moreover, although it is described that the acrylic adhesive of patent document 2 is excellent in blister resistance, there is no description of followability to a level | step difference, and it is not considered about coexistence of blister resistance and followability to a level | step difference Met.

Therefore, the present invention aims to provide an acrylic pressure-sensitive adhesive obtained from an acrylic resin composition excellent in blister resistance and step following performance, in particular, following after a durability test. is there.

  However, as a result of intensive research in view of such circumstances, the present inventor is apt to volatilize in a general adhesive condition using a solvent-based adhesive made of an acrylic resin produced by solution polymerization. When using an organic solvent and blending an ethylenically unsaturated monomer that does not volatilize in a specific ratio and further blending with a thiol compound, when the solvent is dried after coating the adhesive, Since the unsaturated unsaturated monomer remains, the viscosity of the pressure-sensitive adhesive layer can be prevented from rising excessively, and the pressure-sensitive adhesive layer surface can be prevented from becoming hard. Easily volatilizes and is excellent in dryness. Blister resistance and step-following performance due to chain transfer effect of thiol compound and cross-linking effect by enethiol reaction or introduction of sulfur element at the end. Especially found that excellent trackability after the durability test, thereby completing the present invention.

That is, the gist of the present invention is the acrylic resin (A),
Organic solvent (B),
Liquid ethylenically unsaturated compound (C) containing one ethylenically unsaturated group and thiol compound (D) (excluding silane compounds)
Containing
The content ratio (weight ratio) between the acrylic resin (A) and the liquid ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is (A) :( C) = 10: 90 to 75: The flash point (° C.) of the organic solvent (B) is Bf.p., and the flash point (° C.) of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is Cf.p. Is obtained from an acrylic resin composition having a Cf.p. higher than Bf.p. and a difference between Cf.p. and Bf.p. It is related with an adhesive .

Furthermore, the present invention is the acrylic pressure-sensitive adhesive tacky adhesive sheet Do that using a transparent electrode adhesive, a touch panel, an image display device, a method of manufacturing a pressure-sensitive adhesive layer-containing laminate.

Since the acrylic pressure - sensitive adhesive of the present invention uses an organic solvent that easily volatilizes under general drying conditions and contains a specific proportion of an ethylenically unsaturated monomer that is difficult to volatilize,
The solvent-based acrylic pressure-sensitive adhesive containing an acrylic resin produced by ordinary solution polymerization has an effect excellent in coating suitability at the time of thick coating, which has been difficult to achieve. Furthermore, since it contains a thiol compound, the obtained pressure-sensitive adhesive layer has an excellent effect on the blister resistance and the step following performance, particularly the following after the durability test.

The present invention will be described in detail below, but these show examples of desirable embodiments.
In the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

As the acrylic resin (A) used in the present invention, for example, a reactive structural site capable of reacting with a part of the acrylic resin or other curing component contained in the acrylic resin composition by irradiation with active energy rays. Active energy ray reactive acrylic resin (A1) having
Acrylic resin (A2) using a monomer containing a functional group that can be a crosslinking point by reacting with a crosslinking agent (G) described later (functional group-containing monomer (a2) described later) as a copolymerization component. It is done.
As the acrylic resin (A) of the present invention, an active energy ray-reactive acrylic resin (A1) is preferable because a curing period is unnecessary.

  The reactive structural site contained in the active energy ray-reactive acrylic resin (A1) is at least one selected from an ethylenically unsaturated group and a cyclic ether structure, and has high reactivity and requires aging. It is preferable at the point which does not carry out, Especially preferably, it is an ethylenically unsaturated group.

  Hereinafter, as the active energy ray-reactive acrylic resin (A1), an ethylenically unsaturated group-containing acrylic resin (A1-1) and a cyclic ether structure-containing acrylic resin (A1-2) will be described.

Ethylenically unsaturated group containing acrylic resin (A1-1) should just be an acrylic resin which contains an ethylenically unsaturated group in a molecule | numerator, for example, acrylic resin (x) which has a functional group in a molecule | numerator And an ethylenically unsaturated compound (y) having a functional group that reacts with the functional group in the molecule (hereinafter sometimes referred to as “ethylenically unsaturated compound (y)”). It is.
Examples of the acrylic resin (x) having a functional group in the molecule include a functional group-containing ethylenically unsaturated monomer (x1) and a (meth) acrylic acid ester monomer (x2), and further other copolymerization properties as required. It is a polymer obtained by copolymerizing the monomer (x3).

Examples of the functional group-containing ethylenically unsaturated monomer (x1) include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, (meth) acrylamide N-glycolic acid, cinnamon Michael adduct of acid, (meth) acrylic acid (for example, (meth) acrylic acid dimer, (meth) acrylic acid trimer, (meth) acrylic acid tetramer, 2- (meth) acryloyloxyethyl dicarboxylic acid monoester (for example, 2- (meth) acryloyloxyethyl succinic acid monoester, 2- (meth) acryloyloxyethyl phthalic acid monoester, 2- (meth) acryloyloxyethyl hexahydrophthalic acid monoester, etc.) monomer;
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro 2-hydroxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, Hydroxyl group-containing unsaturated monomers such as diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, N-methylol (meth) acrylamide;
Glycidyl group-containing unsaturated monomers such as glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate;
Isocyanate group-containing unsaturated monomers such as 2- (meth) acryloyloxyethyl isocyanate;
(Meth) acrylamide, N- (n-butoxyalkyl) (meth) acrylamide, (meth) acrylamide-3-methylbutylmethylamine, dimethylaminoalkyl (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, etc. An amide group-containing unsaturated monomer of
Olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, sulfonic acid group-containing unsaturated monomer such as 2- (meth) acrylamide-2-methylpropane sulfonic acid, styrene sulfonic acid or salts thereof;
Amino group-containing unsaturated monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate;
Etc., and at least one selected from these is used. Among them, carboxyl group-containing unsaturated monomers, hydroxyl group-containing unsaturated monomers, glycidyl group-containing unsaturated monomers, isocyanate group-containing unsaturated monomers, amide group-containing unsaturated monomers are preferably used, and carboxyl group-containing unsaturated monomers are particularly preferred. , A hydroxyl group-containing unsaturated monomer.

  As (meth) acrylic acid ester monomer (x2), (meth) acrylic acid alkyl ester, (meth) acrylic acid ester containing alicyclic ring, (meth) acrylic acid ester containing aromatic ring, 2-methoxyethyl (Meth) acrylate, 3-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, etc. are mentioned.

  Examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid alkyl esters, particularly (meth) acrylic acid alkyl esters having 1 to 12 carbon atoms, preferably 4 to 12 carbon atoms, and specific examples. N-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Examples include n-octyl (meth) acrylate and lauryl (meth) acrylate.

  (Meth) acrylic acid ester containing the above alicyclic, specifically, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, cyclopentanyl (meth) acrylate, cyclopentenyl (meth) acrylate, alkylene oxide group thereof Examples thereof include unsaturated monomers.

  Examples of the (meth) acrylic acid ester containing the aromatic ring include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene (meth) acrylate, and biphenyloxyethyl (meth) acrylate.

  Examples of other copolymerizable monomers (x3) include (meth) acryloylmorpholine, N- (meth) acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, and vinyl propionate. , Vinyl stearate, vinyl chloride, vinylidene chloride, vinyl acetate, styrene and the like.

  The above functional group-containing ethylenically unsaturated monomer (x1), acrylate monomer (x2), and other copolymerizable monomer (x3), if necessary, have a functional group in the molecule. An acrylic resin (x) is obtained.

  In the case of such copolymerization, it is preferable to produce it by solution polymerization because it is possible to produce the acrylic resin (x) safely and stably with an arbitrary monomer composition. Group-containing ethylenically unsaturated monomer (x1) and acrylate monomer (x2), if necessary, other copolymerizable monomer (x3), polymerization initiator (azobisisobutyronitrile, azobisisovalero Nitrile, benzoyl peroxide, etc.) are mixed or dropped and polymerized at reflux or at 50 to 90 ° C. for 4 to 20 hours.

  As the content ratio of the functional group-containing ethylenically unsaturated monomer (x1), the acrylate monomer (x2), and other copolymerizable monomers (x3), the functional group-containing ethylenically unsaturated monomer (x1) is 0. 0.1 to 50% by weight (preferably 0.5 to 10% by weight), acrylic acid ester monomer (x2) is 50 to 99.9% by weight (preferably 90 to 99.5% by weight), and other copolymers The functional monomer (x3) is preferably 0 to 40% by weight (preferably 0.1 to 20% by weight).

  The ethylenically unsaturated group-containing acrylic resin (A1-1) is an ethylenically unsaturated compound (A) having a functional group that reacts with the functional group in the molecule. y) is reacted, and as the ethylenically unsaturated compound (y), the carboxyl group-containing unsaturated monomer, the hydroxyl group-containing unsaturated monomer, the glycidyl group-containing unsaturated monomer, the isocyanate group-containing unsaturated monomer, Examples include amide group-containing unsaturated monomers, amino group-containing unsaturated monomers, and sulfonic acid group-containing unsaturated monomers.

  In addition, isocyanate groups such as tolylene diisocyanate, isophorone diisocyanate or isocyanate compounds such as adducts and isocyanurates, and the above hydroxyl group-containing unsaturated monomers and hydroxyl groups and compounds having a plurality of (meth) acryloyl groups remain. A urethane acrylate-type isocyanate group-containing unsaturated oligomer obtained by reacting at such a ratio can also be used.

  Among these, it is preferable to use an isocyanate group-containing unsaturated compound such as an isocyanate group-containing unsaturated monomer or an isocyanate group-containing unsaturated oligomer because the acrylic resin (x) and the ethylenically unsaturated compound (y) are easily reacted. .

  For example, when the functional group in the acrylic resin (x) is a carboxyl group, the ethylenically unsaturated compound (y) is preferably a glycidyl group-containing unsaturated monomer or an isocyanate group-containing unsaturated monomer, and the acrylic resin (x) When the functional group is a hydroxyl group, the ethylenically unsaturated compound (y) is preferably an isocyanate group-containing unsaturated monomer. When the functional group in the acrylic resin (x) is a glycidyl group, the ethylenically unsaturated compound (y ) Is preferably a carboxyl group-containing unsaturated monomer or an amide group-containing unsaturated monomer. When the functional group in the acrylic resin (x) is an amino group, the ethylenically unsaturated compound (y) is a glycidyl group-containing unsaturated monomer. It is preferable. In the present invention, particularly when the functional group in the acrylic resin (x) is a hydroxyl group and the ethylenically unsaturated compound (y) is an isocyanate group-containing unsaturated compound, the reactivity of the functional group is particularly excellent. preferable.

In preparing the ethylenically unsaturated group-containing acrylic resin (A1-1), the acrylic resin (x) having a functional group in the molecule and the ethylenically unsaturated compound (y) are reacted. However, this reaction is usually performed at 20 to 80 ° C. for about 1 to 100 hours, and a catalyst may be appropriately used as necessary.
In the reaction, 0.001 to 10 parts by weight of the ethylenically unsaturated compound (y) is preferably reacted with 100 parts by weight of the acrylic resin (x), particularly preferably 0.02 to 2 parts by weight. Parts, more preferably 0.05 to 0.5 parts by weight. When the amount of the ethylenically unsaturated compound (y) is too small, the durability tends to decrease due to insufficient cohesive force, and when the amount is too large, the crosslinking density increases too much and the tackiness tends to decrease.

  The cyclic ether structure-containing acrylic resin (A1-2) is a functional group-containing ethylenically unsaturated monomer (x1) in the functional group-containing acrylic resin (x) described above, and the cyclic ether structure-containing monomer is used as an essential component. Any acrylic resin may be used.

Examples of the cyclic ether structure-containing monomer include glycidyl group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate, and oxetane rings such as 3-methyl-3-oxetanylmethyl acrylate (meth) acrylate. Containing monomers, and these monomers may be used alone or in combination of two or more.
Among these, an oxetane ring-containing monomer is preferable in terms of excellent storage stability.

The content of the cyclic ether structure-containing monomer is preferably 0.01 to 30% by weight, particularly preferably 0.1 to 10% by weight, more preferably 0.5 to 3 parts by weight.
If the amount is too large, the cohesive force tends to increase too much and the tackiness tends to decrease, and if too small, the cohesive force tends to decrease.

  What is necessary is just to manufacture the manufacturing method of cyclic ether structure containing acrylic resin (A1-2) according to the manufacturing method of functional group containing acrylic resin (x) mentioned above.

  The weight average molecular weight of the active energy ray-reactive acrylic resin (A1) in the present invention is usually 100,000 to 5,000,000, preferably 500,000 to 2,000,000, particularly preferably 1,000,000 to 1,500,000. If the weight average molecular weight is too small, the durability performance tends to be lowered. If the weight average molecular weight is too large, a large amount of diluent solvent is required, the coating property is lowered, and thick coating tends to be difficult.

  The dispersity (weight average molecular weight / number average molecular weight) of the active energy ray-reactive acrylic resin (A1) is preferably 20 or less, particularly preferably 15 or less, and further preferably 10 or less. When the degree of dispersion is too high, the durability performance of the pressure-sensitive adhesive layer is lowered, and foaming or the like tends to occur. The lower limit of the degree of dispersion is usually 1.1 from the viewpoint of production limit.

  Furthermore, the glass transition temperature of the active energy ray-reactive acrylic resin (A1) is preferably −80 to 10 ° C., particularly −60 to −10 ° C., more preferably −40 to −20 ° C. If the temperature is too high, tack tends to be insufficient, and if it is too low, the heat resistance tends to decrease.

Ｔg：共重合体のガラス転移温度（Ｋ）
Ｔga：モノマーＡのホモポリマーのガラス転移温度（Ｋ） Ｗa：モノマーＡの重量分率
Ｔgb：モノマーＢのホモポリマーのガラス転移温度（Ｋ） Ｗb：モノマーＢの重量分率
Ｔgn：モノマーＮのホモポリマーのガラス転移温度（Ｋ） Ｗn：モノマーＮの重量分率
（Ｗa＋Ｗb＋・・・＋Ｗn＝１） In addition, said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and it is a column in high performance liquid chromatography (The Japan Waters company "Waters 2695 (main body)" and "Waters 2414 (detector)"). : Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / piece, filler material: styrene-divinylbenzene copolymer, filler The particle diameter is measured by using three series of 10 μm), and the same method can be used for the number average molecular weight. The degree of dispersion is determined from the weight average molecular weight and the number average molecular weight. The glass transition temperature is calculated from the following Fox equation.

Tg: Glass transition temperature of copolymer (K)
Tga: Glass transition temperature of monomer A homopolymer (K) Wa: Weight fraction of monomer A Tgb: Glass transition temperature of homopolymer of monomer B (K) Wb: Weight fraction of monomer B Tgn: Homogeneity of monomer N Glass transition temperature of polymer (K) Wn: weight fraction of monomer N (Wa + Wb +... + Wn = 1)

  When the pressure-sensitive adhesive obtained from the acrylic resin composition of the present invention is used as a base material or an adherend, such as an easily corroded metal or metal oxide such as ITO or copper, the above active energy ray reaction It is preferable that the functional acrylic resin (A1) does not substantially contain an acid component.

  In addition, specifically, it means that the acid value is not more than 10 mgKOH / g, particularly preferably not more than 1 mgKOH / g, more preferably not more than 0.1 mgKOH / g.

  Further, the acrylic resin (A2) is obtained by copolymerizing a (meth) acrylic acid alkyl ester monomer (a1) as a main component and a functional group-containing monomer (a2) as a copolymerization component, Furthermore, another copolymerizable monomer (a3) can be used as a copolymerization component. Since the acrylic resin (A2) uses the functional group-containing monomer (a2) as a copolymerization component, the acrylic resin (A2) serves as a cross-linking point of the acrylic resin (A2), and has an adhesive property with a substrate or an adherend. It can be further raised.

  As such a (meth) acrylic acid alkyl ester monomer (a1), the alkyl group usually has 1 to 20, particularly 1 to 12, more preferably 1 to 8, particularly 4 to 8 carbon atoms. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-propyl (meth) ) Acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, Stearyl (meth) acrylate, iso-stearyl acrylate Rate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate. These can be used alone or in combination of two or more.

  Among such (meth) acrylic acid alkyl ester monomers (a1), n-butyl (meth) acrylate and 2-ethylhexyl (meth) are preferable in terms of copolymerizability, adhesive properties, ease of handling, and availability of raw materials. An acrylate is preferably used, and n-butyl (meth) acrylate is more preferably used because of excellent durability.

  The content of the (meth) acrylic acid alkyl ester monomer (a1) in the copolymerization component is preferably 10 to 100% by weight, particularly preferably 50 to 95% by weight, more preferably 65 to 90% by weight, It is preferably 60 to 85% by weight, and if the content of the (meth) acrylic acid alkyl ester monomer (a1) is too small, the adhesive strength when used as an adhesive tends to be reduced.

  The functional group-containing monomer (a2) may be any monomer containing a functional group that can become a crosslinking point by reacting with a crosslinking agent (G) described later. For example, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group -Containing monomers, acetoacetyl group-containing monomers, isocyanate group-containing monomers, glycidyl group-containing monomers, and the like. Among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used in terms of efficient crosslinking reaction.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meta ) Acrylic acid hydroxyalkyl esters such as acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate and other caprolactone-modified monomers, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate and other oxyalkylene-modified monomers, and other 2-acrylic Primary hydroxyl group-containing monomers such as leuoxyethyl-2-hydroxyethylphthalic acid; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) a Relate, secondary hydroxyl group-containing monomers such as 3-chloro-2-hydroxypropyl (meth) acrylate; may be mentioned 2,2-dimethyl-2-hydroxyethyl (meth) tertiary hydroxyl group-containing monomers such as acrylates.

  Among the above hydroxyl group-containing monomers, it is particularly preferable to use, for example, 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate in terms of excellent reactivity with the crosslinking agent.

  In addition, as a hydroxyl-containing monomer used by this invention, it is also preferable to use a thing with the content rate of di (meth) acrylate which is an impurity 0.5% or less, and also 0.2% or less, especially 0 It is preferable to use 1% or less, specifically 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, and cinnamic acid. 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 (meth) acrylate, and the like.

  Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

  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, allyl glycidyl (meth) acrylate, and the like.
These functional group-containing monomers (a2) may be used alone or in combination of two or more.

  The content of the functional group-containing monomer (a2) in the copolymerization component is preferably 0 to 90% by weight, particularly preferably 5 to 50% by weight, more preferably 10 to 45% by weight, and particularly preferably 15 to When the content of the functional group-containing monomer (a2) is too small, the moisture-and-heat whitening resistance and the cohesive force tend to decrease. When the content is too large, the viscosity increases or the stability of the resin. Tends to decrease.

  Other copolymerizable monomers (a3) include, for example, phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) ) Monomers containing one aromatic ring such as acrylate, styrene, α-methylstyrene; biphenyloxy structure-containing (meth) acrylic acid ester monomers such as biphenyloxyethyl (meth) acrylate; ethoxymethyl (meth) acrylamide, n -Butoxymethyl (meth) acrylamide, (meth) acryloylmorpholine, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth) acrylamide N-methylol (meth) acrylamide, etc. (Meth) acrylamide monomer; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polypropylene glycol mono Monomers containing alkoxy groups or oxyalkylene groups such as (meth) acrylates; 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, acrylic chloride, methyl Ruvinyl ketone, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone and the like.

  The content of the other copolymerizable monomer (a3) in the copolymerization component is preferably 0 to 40% by weight, particularly preferably 0 to 30% by weight, more preferably 0 to 25% by weight. When there are too many copolymerizable monomers (a3), there exists a tendency for an adhesive characteristic to fall easily.

Thus, by polymerizing the above (meth) acrylic acid alkyl ester monomer (a1), preferably a functional group-containing monomer (a2), and optionally other copolymerizable monomer (a3) as a copolymerization component, The resin (A2) is produced. In such polymerization, production by solution polymerization is preferable because the acrylic resin (A) can be produced safely and stably with an arbitrary monomer composition.
In such solution polymerization, for example, a monomer component such as a (meth) acrylic acid alkyl ester monomer (a1), a functional group-containing monomer (a2), other copolymerizable monomer (a3), a polymerization initiator in an organic solvent. May be mixed or dropped and polymerized at reflux or at 50 to 98 ° C. for 0.1 to 20 hours.

  Examples of such polymerization initiators include azo-based polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, which are ordinary radical polymerization initiators, benzoyl peroxide, lauroyl peroxide, and di-t-butyl peroxide. Specific examples include peroxide polymerization initiators such as cumene hydroperoxide.

  The weight average molecular weight of the acrylic resin (A2) is usually 100,000 to 5,000,000, preferably 300,000 to 1,500,000, particularly preferably 500,000 to 900,000. If the weight average molecular weight is too small, the durability performance tends to decrease, and if it is too large, the production tends to be difficult.

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A2) is preferably 20 or less, particularly preferably 15 or less, more preferably 10 or less, and particularly preferably 7 or less. preferable. When the degree of dispersion is too high, the durability performance of the pressure-sensitive adhesive layer is lowered, and foaming or the like tends to occur. The lower limit of the degree of dispersion is usually 1.1 from the viewpoint of production limit.

  Furthermore, the glass transition temperature of the acrylic resin (A2) is preferably −80 to 10 ° C., particularly preferably −60 to −10 ° C., more preferably −50 to −20 ° C. If the glass transition temperature is too high. Tack tends to be insufficient, and if it is too low, heat resistance tends to decrease.

  In addition, the weight average molecular weight of the said acrylic resin (A2), a dispersion degree, and a glass transition temperature are calculated | required by the method similar to the said active energy ray reactive acrylic resin (A1).

  In addition, when using the acrylic pressure-sensitive adhesive of the present invention for transparent electrodes such as those for touch panels and other electronic members, particularly for information label uses that are bonded to precision electronic members, and for fixing electronic members, it is corrosion resistant. In this case, it is preferable that the acrylic resin (A2) does not contain an acidic group.

In addition to the acrylic resin (A), the acrylic resin composition of the present invention is a liquid ethylenically unsaturated compound (C) (hereinafter referred to as an organic solvent (B) and one ethylenically unsaturated group). It may be referred to as “ethylenically unsaturated compound (C)”) and thiol compound (D) as essential components.

Such an organic solvent (B) and an ethylenically unsaturated compound (C) exhibit the flash point (° C.) of the organic solvent (B) with respect to their flash point in order to exert the effect of the present invention relating to drying suitability. p, when the flash point (° C.) of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is Cf.p,
(1) Cf.p. is higher than Bf.p., and (2) the difference between Cf.p. and Bf.p.

  Regarding the condition (2), the difference between Cf.p. and Bf.p. needs to be 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 120 ° C. or higher. If the difference between Cf.p. and Bf.p. is too small, the residual ratio of the ethylenically unsaturated compound (C) will decrease during drying, which may prevent efficient drying during thick coating. When the residual ratio of the solvent (B) is increased, the solvent remains in the pressure-sensitive adhesive coating film, and the adhesive performance tends to decrease. The upper limit of the difference between Cf.p. and Bf.p. is usually 400.degree.

Moreover, as an organic solvent (B), the organic solvent which satisfy | fills conditions (1) and (2) may be used individually or in multiple types, and even as an ethylenically unsaturated compound (C), conditions (1) and ( You may use the ethylenically unsaturated compound which satisfy | fills 2) individually or in multiple types.
In addition, you may use together the organic solvent (B ') and ethylenically unsaturated compound (C') which do not satisfy | fill conditions (1) and (2) in the range which does not impair the effect of this invention.

  In the present invention, by satisfying the above relationship, when the adhesive using the acrylic resin composition is applied and then dried, the viscosity of the adhesive layer is prevented from excessively increasing, and the adhesive layer surface is hard. Therefore, even when a thick coating is applied, the solvent is easily evaporated and the drying can be performed efficiently.

  In general, the volatility of a compound is generally determined from the boiling point or evaporation rate. However, an unsaturated monomer (ethylenically unsaturated compound (C)) is polymerized when a temperature is applied at normal pressure. Since the boiling point cannot be measured accurately, the flash point correlated with the volatility of the compound was used as an indicator of volatility in the present invention. The flash point measurement shall be in accordance with JIS K2265, and the method used shall be as follows (with reference to the provisions of Class 4 of the Fire Service Act).

The details are as follows.
(A) Measure the flash point using a closed tag flash point tester.
(B) In (a), if the flash point is not measured at a temperature of 80 ° C. or lower, the flash point is measured by a Cleveland open flash point tester.
(C) In (a), if the flash point is measured at a temperature of 0 ° C. or higher and 80 ° C. or lower and the kinematic viscosity of the test article at the flash point is 10 cSt or higher, Measure the flash point with a measuring instrument.

  The organic solvent (B) used in the present invention is not particularly limited as long as the organic solvent (B) satisfies the conditions (1) and (2) relating to the above-mentioned flash point. An optimum organic solvent may be appropriately selected and used according to the polymerization conditions of the resin (A) and the type of the ethylenically unsaturated compound (C).

  The organic solvent (B) may be an organic solvent used when the acrylic resin (A) is produced by solution polymerization, or an organic solvent used for diluting the produced acrylic resin (A). It may be a solvent, or may be an organic solvent blended when the acrylic resin (A) and an ethylenically unsaturated compound (C) described later are mixed. It is preferable that it is an organic solvent used when manufacturing acrylic resin (A) by solution polymerization at the point which is excellent.

  The flash point of the organic solvent (B) is preferably 30 ° C. or less, particularly preferably 15 ° C. or less, and more preferably 0 ° C. or less in that it easily evaporates during coating drying and has excellent drying properties. If the flash point is too high, the solvent tends to remain when an adhesive sheet is made. The lower limit is usually −50 ° C. from the viewpoint of safety.

  Specific examples of the organic solvent (B) include ester solvents such as ethyl acetate (flash point −3 ° C.), methyl acetate (flash point −10 ° C.) and butyl acetate (flash point 28 ° C.); acetone (flash point) -20 ° C), ketone solvents such as methyl ethyl ketone (flash point -7 ° C), methyl isobutyl ketone (flash point 17 ° C); heptane (flash point -4 ° C), hexane (flash point -30 ° C), cyclohexane (flash point) Aliphatic hydrocarbon solvents such as methylcyclohexane (flash point −4 ° C.), toluene (flash point 5 ° C.), o-xylene (flash point 27 ° C.), m-xylene (flash point 23 ° C.) ), Aromatic hydrocarbon solvents such as p-xylene (flash point 23 ° C.); methanol (flash point 11 ° C.), ethanol (flash point 13 ° C.), isopropyl alcohol (flash point 12 ° C.), isobutanol (flash point) 2 ), Sec-butanol (flash point 23 ° C.), tertiary butanol (flash point 11 ° C.) and the like. (The flash point value is “Paint Raw Material Handbook 7th Edition, Nippon Paint” The value is described in “Industry Association.” However, for methyl isobutyl ketone, the value is described in “MSDS of Sankyo Chemical Co., Ltd.”).

  Among these, in terms of versatility, coating suitability, and polymerization suitability, ester solvents, ketone solvents, and aromatic hydrocarbon solvents are preferable, and ester solvents and ketone solvents are particularly preferable. More preferably, ethyl acetate, acetone, and methyl ethyl ketone are preferable because they have an optimum boiling point and can be obtained in large quantities at a low cost.

  The molecular weight of the organic solvent (B) is preferably 120 or less, particularly preferably 20 to 100, and more preferably 30 to 90. If the molecular weight is too large, it is difficult to volatilize and tends to remain after drying.

In addition, the boiling point of the organic solvent (B) is preferably 120 ° C. or less, particularly preferably 100 ° C. or less, and more preferably 85 ° C. or less, in that it easily volatilizes during coating drying and has excellent drying properties. . If the boiling point is too high, the solvent tends to remain when an adhesive sheet is produced.
Moreover, it is preferable that a lower limit is 40 degreeC or more normally at the point of safety | security.
In addition, the said boiling point shall be a boiling point when measured by a normal pressure (1 atmosphere), and the measurement should just be performed according to JISK5601-2-3.

As content of an organic solvent (B), it is preferable that it is 20-1000 weight part with respect to 100 weight part of acrylic resin (A), Most preferably, it is 40-500 weight part, More preferably, it is 80-250. Part by weight, particularly preferably 120 to 180 parts by weight.
When the content of the organic solvent (B) is too large, thick coating tends to be difficult due to excessive decrease in coating viscosity, and when it is too small, the acrylic resin (A) is produced by solution polymerization. There is a tendency for manufacturing safety and flexibility to be reduced.

  The ethylenically unsaturated compound (C) used in the present invention is not particularly limited as long as it is an ethylenically unsaturated compound (C) that satisfies the conditions (1) and (2) regarding the flash point described above. It is not a thing, but what is necessary is just to select and use the optimal ethylenically unsaturated compound suitably according to the kind of acrylic resin (A) and the kind of organic solvent (B).

  In order to improve the drying property of the organic solvent (B), the ethylenically unsaturated compound (C) used in the present invention is at the time of coating drying (particularly at the time of drying when thick film coating is performed), Those that are less volatile than the organic solvent (B) and remain in the pressure-sensitive adhesive layer are used.

The flash point of the ethylenically unsaturated compound (C) is preferably 40 ° C. or higher, particularly preferably 80 ° C. or higher, more preferably 100 ° C. or higher, particularly 140 ° C. or higher. If the flash point is too low, it tends to volatilize in the drying process. The upper limit of the normal flash point is 350 ° C.
Although some ethylenically unsaturated compounds do not ignite even when the measurement limit exceeds 350 ° C., such ethylenically unsaturated compounds are very stable and are not easily volatilized according to the present invention. Since the effect can be exhibited, it is treated as an ethylenically unsaturated compound (C).

The weight average molecular weight of the ethylenically 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. is there.
If the molecular weight is too large, the physical properties of the adhesive tend to be lowered, and if it is too small, it tends to volatilize in the drying process.

  As the ethylenically unsaturated compound (C), an ethylenically unsaturated compound having a relatively high flash point (flash point of 100 ° C. or higher), for example, a (meth) acrylic acid ester compound containing one ethylenically unsaturated group The use of (C1) (except for C2 described later) and the ethylenically unsaturated compound (C2) containing a nitrogen atom can efficiently dry the organic solvent (B) at a wide range of drying temperatures. Is preferable.

  Examples of the (meth) acrylic acid ester compound (C1) having one ethylenically unsaturated group include long-chain aliphatic (meth) acrylate (c1), alicyclic (meth) acrylate (c2), aromatic ( Examples include (meth) acrylate (c3) and oxyalkylene structure-modified compounds (c4) of these (meth) acrylates.

  Examples of the long chain aliphatic (meth) acrylate (c1) include decane (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, isomyristyl (meth) acrylate, and n-stearyl. (Meth) acrylate, isostearyl (meth) acrylate, etc. are mentioned.

  Examples of the alicyclic (meth) acrylate (c2) include isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and the like.

  Examples of the aromatic (meth) acrylate (c3) include benzyl (meth) acrylate, biphenyl (meth) acrylate, naphthalene (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and 3-chloro-2. -Hydroxypropyl (meth) acrylate etc. are mentioned.

  Examples of the oxyalkylene structure-modified compound (c4) of (c1) to (c3) include, for example, 2-ethylhexyldiethylene glycol (meth) acrylate, methoxytriethylene as the oxyalkylene structure-modified compound (c4-1) of (c1). Examples include glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, alkylene glycol monoalkyl ester (meth) acrylate, alkylene glycol mono (meth) acrylate, and the like (c2) oxyalkylene Examples of the structure-modifying compound (c4-2) include t-butylcyclohexyloxyethyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, and dicyclopentenyloxy. Ciethyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, and the like. Examples of (c3) oxyalkylene (alkyl) structure-modifying compound (c4-3) include phenoxyethyl (meth) acrylate and phenyl. Diethylene glycol (meth) acrylate, phenoxytriethylene glycol (meth) acrylate, phenoxytetraglycol (meth) acrylate, biphenyloxyethyl acrylate, nonylphenol ethylene oxide modified (repeat 4) (meth) acrylate, nonylphenol ethylene oxide modified (repeat 8) ( And (meth) acrylate.

The specific flash points of the exemplified compounds are as follows.
Long chain aliphatic (meth) acrylate (c1); isomyristyl acrylate (flash point: 129 ° C.), tridecyl acrylate (flash point: 154 ° C.), n-stearyl acrylate (flash point: 181 ° C.), isostearyl acrylate (Flash point: 154 ° C)
Alicyclic (meth) acrylate (c2); isobornyl acrylate (113 ° C.), dicyclopentanyl acrylate (132 ° C.), dicyclopentenyl acrylate (131 ° C.)
Aromatic (meth) acrylate (c3): benzyl acrylate (108 ° C.)
-(C1) Oxyalkylene structure-modified compound (c4-1); 2-ethylhexyl diethylene glycol acrylate (151 ° C), methoxytriethylene glycol acrylate (143 ° C), ethoxydiethylene glycol acrylate (113 ° C), methoxydipropylene glycol acrylate ( 102 ° C)
-(C2) oxyalkylene structure-modified compound (c4-2); dicyclopentenyloxyethyl acrylate (166 ° C)
(C3) oxyalkylene (alkyl) structure-modified compound (c4-3): phenoxyethyl acrylate (141 ° C.), phenyldiethylene glycol acrylate (173 ° C.), nonylphenol ethylene oxide-modified (repeated 4) acrylate (223 ° C.), nonylphenol Ethylene oxide modified (repeated 8) acrylate (304 ° C)

  In addition, about the methacrylate compound corresponding to the acrylate compound described above, the flash point is usually higher.

  Among these, it is preferable to use the oxyalkylene structure-modified compound (c4) of long-chain aliphatic (meth) acrylates (c1) and (c1) to (c3), and particularly preferably long-chain aliphatic (meth) acrylate in terms of excellent drying suitability. Aliphatic (meth) acrylate (c1), long-chain aliphatic (meth) acrylate (c1) oxyalkylene structure-modified compound (c4-1), aromatic (meth) acrylate (c3) oxyalkylene (alkyl) structure modification Compound (c4-3), more preferably isomyristyl acrylate, tridecyl acrylate, isostearyl acrylate, methoxytriethylene glycol acrylate, phenyldiethylene glycol acrylate, and cyclopentenyloxyethyl acrylate.

  The nitrogen-containing ethylenically unsaturated compound (C2) can be used to improve the adhesive strength of the pressure-sensitive adhesive. For example, N-acryloyloxyethylhexahydrophthalimide (190 ° C.), acryloylmorpholine (130 ° C.), oxazolidone acrylate, acrylamide (134 ° C.), methacrylamide, butoxymethyl acrylamide (flash point: 112 ° C.), hydroxyethyl acrylamide (189 ° C.), dimethylaminopropyl acrylamide (140 ° C.), diacetone acrylamide (110 Among these, it is preferable to use N-acryloyloxyethylhexahydrophthalimide, acryloylmorpholine, butoxymethylacrylamide, diacetone acrylamide. .

  Moreover, when using the adhesive obtained using the acrylic resin composition of this invention for a strong adhesive use, the content rate of (C2) with respect to the whole ethylenically unsaturated compound (C) is 1 to 90 weight%. It is preferably 5 to 80% by weight, more preferably 15 to 70% by weight, particularly preferably 30 to 65% by weight. If the content ratio of (C2) is too large or too small, the adhesive strength is difficult to increase, and the required adhesive strength tends to be difficult to obtain.

When the organic solvent (B) is dried at a relatively low temperature (100 ° C. or lower), a compound having a relatively low flash point (less than 100 ° C.) is used as the ethylenically unsaturated compound (C). You can also
Examples of the ethylenically unsaturated compound (C) include butyl acrylate (flash point: 40 ° C.) and 2-ethylhexyl acrylate (flash point: 88 ° C.).

In addition, the ethylenically unsaturated compound (C) is present as a polymer in the pressure-sensitive adhesive layer by being cured by active energy rays and / or heat as described later, and the glass transition temperature of the polymer. It is preferable to select the ethylenically unsaturated compound (C) so that (Tg) is -80 to 80 ° C.
The glass transition temperature is particularly preferably −60 to 40 ° C., more preferably −30 to 20 ° C., and particularly preferably −10 to 10 ° C. If the glass transition temperature is too high, the adhesive performance tends not to be obtained. If it is too low, the cohesive force tends to decrease.
The glass transition temperature is calculated from the Fox equation described above.

In the present invention, the content ratio (weight ratio) of the acrylic resin (A) and the ethylenically unsaturated compound (C) needs to be (A) :( C) = 10: 90 to 75:25. Yes, preferably (A) :( C) = 20: 80 to 70:30, particularly preferably (A) :( C) = 25: 75 to 65:35, particularly preferably (A). : (C) = 30: 70 to 55:45.
If the content of the ethylenically unsaturated compound (C) relative to the acrylic resin (A) is too small, thick coating tends to be difficult and the effect of the present invention tends not to be exhibited sufficiently. Too much thick coating tends to be difficult.

Examples of the thiol compound (D) used in the present invention (excluding a silane compound) include, for example, a monofunctional thiol compound (a compound containing one thiol group), a bifunctional thiol compound (containing two thiol groups) Compounds), trifunctional thiol compounds (compounds containing three thiol groups), tetrafunctional or higher thiol compounds (compounds containing four or more thiol groups), etc. A 2- to 4-functional thiol compound is preferable in terms of superiority, and a tri-functional thiol compound is particularly preferable.

Examples of the monofunctional thiol compound include hexanethiol, 1-heptanethiol, 1-octanethiol, 1-nonanethiol, 1-decanethiol, 1-undecanthiol, 1-dodecanethiol, 1-tridecanethiol, 1- Tetradecanethiol, 1-stearylthiol, methyl mercaptopropionate, methoxybutyl mercaptopropionate, octyl mercaptopropionate, tridecyl mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate 3-mercaptopropionate, n-octyl-3 -Mercaptopropionate, stearyl-3-mercaptopropionate, etc. are mentioned.
These may be used alone or in combination of two or more.

Examples of the bifunctional thiol compound include:
Tetraethylene glycol bis (3-mercaptopropionate), ethylene glycol bis (2-mercaptopropionate), 1,2-propylene glycol bis (2-mercaptopropionate), diethylene glycol bis (2-mercaptopropionate) ), Ethylene glycol bis (3-mercaptopropionate), 1,2-propylene glycol bis (3-mercaptopropionate), 1,2-propylene glycol bis (3-mercaptobutyrate), diethylene glycol bis (3- Mercaptobutyrate), 1,2-propylene glycol bis (3-mercaptoisobutyrate), diethylene glycol bis (3-mercaptoisobutyrate), ethylene glycol bisthioglycolate, ethylene glycol bis Glycols such as 2-mercaptoisobutyrate), 1,2-propylene glycol bis (2-mercaptoisobutyrate), diethylene glycol bis (2-mercaptoisobutyrate), diethylene glycol bis (3-mercaptopropionate), etc. Thiol compounds;
1,4-butanediol bis (2-mercaptopropionate), 1,4-butanediol bis (3-mercaptopropionate), 1,4-butanediol bis (3-mercaptobutyrate) 1,4- Bis (3-mercaptobutyryloxy) butane, 1,4-butanediol bis (3-mercaptoisobutyrate), 1,4-butanediol bis (2-mercaptoisobutyrate), butanediol bisthioglycolate, Butanediol thiol compounds such as ethylene glycol bis (3-mercaptoisobutyrate) and ethylene glycol bis (3-mercaptobutyrate);
1,8-octanediol bis (2-mercaptopropionate), 1,8-octanediol bis (3-mercaptopropionate, 1,8-octanediol bis (3-mercaptobutyrate), 1,8- Octanediol thiol compounds such as octanediol bis (3-mercaptoisobutyrate) and 1,8-octanediol bis (2-mercaptoisobutyrate);
Examples include hexanediol bisthioglycolate.
These may be used alone or in combination of two or more.

Examples of the trifunctional thiol compound include trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptoisobutyrate), and trimethylol. Trimethylolpropane thiol compounds such as propanetris (2-mercaptoisobutyrate), trimethylolpropane tristhioglycolate; tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate, trimethylolethanetris (3 -Mercaptobutyrate), 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, etc. Among them, trimming in terms of versatility Tyrolepropane tris (3-mercaptopropionate) is preferred.
These may be used alone or in combination of two or more.

Examples of the tetrafunctional or higher functional thiol compound include, for example,
Pentaerythritol such as pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), pentaerythritol tetrakis (3-mercaptoisobutyrate), pentaerythritol tetrakis (2-mercaptoisobutyrate) Thiol compounds; dipentaerythritol hexakis (3-mercaptopropionate) dipentaerythritol hexakis (2-mercaptopropionate), dipentaerythritol hexakis (3-mercaptopropionate), dipentaerythritol hexakis (3-mercaptobutyrate), dipentaerythritol hexakis (3-mercaptoisobutyrate), dipentaerythritol hexakis (2-mercaptoisobutyrate) Rate), dipentaerythritol based thiol compounds such as pentaerythritol tetrakis thioglycolate dipentaerythritol hexakis thioglycolate; and the like.
These may be used alone or in combination of two or more.

The molecular weight of the thiol compound (D) of the present invention is preferably 100 or more, particularly preferably 150 or more, and further preferably 200 or more.
If the molecular weight is too low, it tends to volatilize during drying. The upper limit of the molecular weight is usually 5,000, preferably 1,000.

Content of a thiol compound (D) is 0.01-10 weight part normally with respect to 100 weight part of acrylic resin (A), Preferably it is 0.1-8 weight part, Most preferably, it is 0.3-6. Part by weight, more preferably 0.5 to 5 parts by weight.
If the content is too large, the workability tends to decrease, and if the content is too small, the adhesion tends to decrease.

Further, the total amount of the acrylic resin (A) and the ethylenically unsaturated compound (C) is preferably 20% by weight or more, particularly preferably 40% by weight with respect to the entire components (A) to (D). %, More preferably 60% by weight or more, and the upper limit of the content is usually 98% by weight.
If the ratio of the total amount of the acrylic resin (A) and the ethylenically unsaturated compound (C) to the total components (A) to (D) is too low, thick coating becomes difficult and a thick film adhesive layer Tends to be difficult to obtain.

  The content ratio of the acrylic resin (A) with respect to the entire acrylic resin composition is usually 5 to 50% by weight, preferably 10 to 40% by weight, and particularly preferably 25 to 35% by weight. If the content is too large, the viscosity tends to increase too much and the coating suitability tends to decrease, and if too small, the viscosity tends to decrease too much and the coating suitability tends to decrease.

  The content rate of the organic solvent (B) with respect to the whole acrylic resin composition is usually 10 to 90% by weight, preferably 15 to 50% by weight, and particularly preferably 20 to 40% by weight. If the content is too high, the coating concentration tends to be too low and the coating suitability tends to be lowered. If the content is too small, the viscosity tends to be too high and the coating suitability tends to be lowered.

  The content ratio of the ethylenically unsaturated compound (C) with respect to the entire acrylic resin composition is usually 5 to 85% by weight, preferably 10 to 50% by weight, and particularly preferably 20 to 40% by weight. If the content is too high, the content of (A) is too low and the adhesive properties tend to decrease. If the content is too low, the coating viscosity during drying is excessively increased, resulting in a decrease in drying properties. Coating tends to be difficult.

The content rate of the thiol compound (D) with respect to the whole acrylic resin composition is 0.01 to 30 weight% normally, Preferably it is 0.01 to 10 weight%, Especially preferably, it is 0.01 to 5 weight%.
If the content is too large, the workability tends to decrease, and if it is too small, the adhesion tends to decrease.

The acrylic resin composition of the present invention preferably has a viscosity of 20,000 mPa · s / 25 ° C. or less from the viewpoint of coating properties, particularly preferably 18,000 mPa · s / 25 ° C. or less, and more preferably. Is 15,000 mPa · s / 25 ° C. or less, particularly preferably 3,000 mPa · s / 25 ° C. or less. Usually, the lower limit of the viscosity is 100 mPa · s / 25 ° C.
If the viscosity is too high, the coating tends to be difficult due to, for example, the appearance of coating stripes.

  The acrylic resin composition of the present invention is produced by simultaneously mixing and stirring the acrylic resin (A), the ethylenically unsaturated compound (C), and the thiol compound (D) after producing the acrylic resin (A). It is preferable to do. The organic solvent (B) is preferably used at the time of producing the acrylic resin (A) and at the time of producing the acrylic resin (A), the ethylenically unsaturated compound (C), and the thiol compound (D). .

  Thus, an acrylic resin composition comprising the acrylic resin (A), organic solvent (B), ethylenically unsaturated compound (C), and thiol compound (D) of the present invention is obtained. In the present invention, when the content ratio (weight ratio) of the acrylic resin (A) and the ethylenically unsaturated compound (C) is within the above range, it is excellent in drying suitability and can be applied by thick coating. To do. Moreover, by including the thiol compound (D), the blister resistance is improved due to the chain transfer effect of the thiol compound and the crosslinking effect by the enethiol reaction or the effect of introducing sulfur element to the terminal.

  In the present invention, the acrylic resin composition containing the acrylic resin (A), organic solvent (B), ethylenically unsaturated compound (C), and thiol compound (D) is applied and dried. After the organic solvent (B) is volatilized, the acrylic pressure-sensitive adhesive can be obtained by curing / crosslinking (however, the organic solvent remaining in the drying step in the acrylic resin composition during curing / crosslinking ( B) may be included to some extent.)

  As such curing / crosslinking methods, [α] a method of curing with active energy rays and / or heat, a method of combining a method of curing with [β] active energy rays and / or heat and a method of crosslinking with a crosslinking agent. , Etc.

When performing the above-mentioned [α] active energy ray and / or heat curing, the acrylic resin composition further contains an ethylenically unsaturated compound (E) (hereinafter referred to as two or more ethylenically unsaturated groups). It may be abbreviated as “polyfunctional unsaturated compound (E)”) in that the cohesive force of the entire pressure-sensitive adhesive layer can be adjusted, and further contains a polymerization initiator (F). It is preferable at the point which can stabilize reaction at the time of active energy ray irradiation and / or a heating.
In such curing, the ethylenically unsaturated compound (C), the thiol compound (D), and the polyfunctional unsaturated compound (E) are polymerized (polymerized) by active energy rays and / or heat and cured.

  Moreover, when bridge | crosslinking using a crosslinking agent by said [(beta)], a crosslinking reaction can be performed by making an acrylic resin composition contain a crosslinking agent (G). In addition, when using a crosslinking agent (G), it is preferable that acrylic resin (A) has a functional group, and crosslinking (curing) is performed by this functional group and a crosslinking agent reacting.

In the present invention, the above [α] active energy ray and / or heat (irradiation with active energy ray and / or) is possible in that the gel fraction of the pressure-sensitive adhesive layer can be increased in a short time without requiring an aging time. It is preferable to perform curing by heating. In this case, it is also preferable to add an unsaturated group in advance to the functional group of the acrylic resin (A).
Moreover, in the point which raises the crosslinking density of an adhesive and raises cohesive force and what is further excellent about durability is obtained, it crosslinks using the method and the crosslinking agent which harden | cure by an active energy ray and / or heat. It is preferable to combine this method with the above method.

  As the polyfunctional unsaturated compound (E), for example, an ethylenically unsaturated monomer containing two or more ethylenically unsaturated groups in one molecule, for example, a bifunctional monomer, a trifunctional or higher monomer, Urethane (meth) acrylate compounds, epoxy (meth) acrylate compounds, and polyester (meth) acrylate compounds can be used. Among these, it is preferable to use an ethylenically unsaturated monomer and a urethane (meth) acrylate-based compound from the viewpoint of excellent curing rate and ultimate physical properties.

  The bifunctional monomer may be any monomer containing two ethylenically unsaturated groups. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene Oxide modified bisphenol A type di (meth) acrylate, propylene oxide modified bisphenol A type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate 1,6-hexanediol ethylene oxide modified di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di ( Meth) acrylate, diglycidyl phthalate di (meth) acrylate, hydroxypivalic acid modified neopentyl glycol di (meth) acrylate, isocyanuric acid ethylene oxide modified diacrylate, 2- (meth) acryloyloxyethyl acid phosphate diester, etc. It is done.

  The tri- or higher functional monomer may be any monomer containing three or more ethylenically unsaturated groups. For example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, 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 (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, succinic acid modified pentaerythritol tri (meth) acrylate Etc.

  The urethane (meth) acrylate compound is a (meth) acrylate compound having a urethane bond in the molecule, a (meth) acrylic compound containing a hydroxyl group and a polyvalent isocyanate compound (if necessary, a polyol What is necessary is just to use what is obtained by making it react by a well-known general method, and what is necessary is just to use the thing of 300-4000 normally as the weight average molecular weight.

  The content of the polyfunctional unsaturated compound (E) is desirably 0.01 to 100 parts by weight, preferably 0.05 to 10 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). More preferably, it is 0.1 to 5 parts by weight. If the content of the polyfunctional unsaturated compound (E) is too large, the cohesive force is excessively increased, so that the adhesive performance tends to be inferior. If the content is too small, the holding power tends to be insufficient.

  In addition, the content of the polyfunctional unsaturated compound (E) is desirably 0.01 to 99 parts by weight, preferably 0.05 to 100 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated compound (C). 10 parts by weight, more preferably 0.1 to 5 parts by weight. If the content of the polyfunctional unsaturated compound (E) is too large, the cohesive force of the pressure-sensitive adhesive will increase too much, and the adhesive performance tends to be inferior. If it is too small, the cohesive force will decrease, resulting in durability. It tends to decrease.

The content ratio of the polyfunctional unsaturated compound (E) and the thiol (D) is the ratio of the number of moles of the unsaturated group of (E) and the mercapto group of (D) (D) :( E) = 30. : 1 to 1: 1 is preferable, particularly preferably (D) :( E) = 15: 1 to 1.5: 1, and more preferably (D) :( E) = 5: 1 to 2: 1. .
If the content ratio of the polyfunctional unsaturated compound (E) with respect to the thiol compound (D) is too high, the processability tends to decrease, and if it is too low, the adhesion tends to decrease.

  As the polymerization initiator (F), for example, various polymerization initiators such as a photopolymerization initiator (f1) and a thermal polymerization initiator (f2) can be used. The use of f1) is preferable in that it can be cured by irradiation with active energy rays such as ultraviolet rays for a very short time.

  Further, when the photopolymerization initiator (f1) is used, the acrylic resin composition is cured by irradiation with active energy rays, and when the thermal polymerization initiator (f2) is used, the acrylic resin composition is cured by heating. However, it is also preferable to use both in combination as necessary.

  Examples of the photopolymerization initiator (f1) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4- Acetophenones such as morpholinophenyl) butanone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl Ben such as ether Ins; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium Benzophenones such as chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy -3 Thioxanthones such as 4-dimethyl-9H-thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl- And acyl phosphine oxides such as pentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. In addition, as for these photoinitiators (f1), only 1 type may be used independently and 2 or more types may be used together.

  These auxiliary agents include triethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone (Michler ketone), 4,4′-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-dimethylaminobenzoic acid. Ethyl, 4-dimethylaminobenzoic acid (n-butoxy) ethyl, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone Etc. can be used in combination.

  Among these, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoyl isopropyl ether, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1- It is preferable to use phenylpropan-1-one.

  Examples of the thermal polymerization initiator (f2) include methyl ethyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate peroxide, acetyl acetate peroxide, 1,1-bis (t-hexyl peroxide). ) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1, 1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 1,1- Bis (t-butylperoxy) butane, 2,2-bis (4 -Di-t-butylperoxycyclohexyl) propane, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroper Oxide, t-butyl hydroperoxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-Butyl cumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexa Noyl peroxide, octanoyl per Oxide, lauroyl peroxide, stearoyl peroxide, succinic acid peroxide, m-toluoyl benzoyl peroxide, benzoyl peroxide, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butyl) (Cyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-s-butyl peroxydicarbonate, Di (3-methyl-3-methoxybutyl) peroxydicarbonate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-te Lamethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxy Pivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylper) Oxy) hexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t- Hexyl peroxyisopropyl monocarbonate, t-butyl peroxyisobutyrate t-butyl peroxymalate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2 -Ethylhexyl monocarbonate, t-butyl peroxyacetate, t-butyl peroxy-m-toluylbenzoate, t-butyl peroxybenzoate, bis (t-butylperoxy) isophthalate, 2,5-dimethyl-2,5 -Bis (m-toluylperoxy) hexane, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyallyl monocarbonate, t-butyltrimethylsilylper Oxide, 3,3 ', 4,4'-tetra Organic peroxide initiators such as (t-butylperoxycarbonyl) benzophenone and 2,3-dimethyl-2,3-diphenylbutane; 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1- [(1-cyano-1-methylethyl) azo] formamide, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′- Azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis (2-methyl- N-phenylpropionamidine) dihydrochloride, 2,2'-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] Hydride chloride, 2,2'-azobis [N- (4-hydrophenyl) -2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride 2,2'-azobis [2-methyl-N- (2-propenyl) propionamidine] dihydrochloride, 2,2'-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl) Lopan] dihydrochloride, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (5-hydroxy-3 , 4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane] dihydrochloride 2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] ] Propionamide], 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide], 2,2'-azobis [2-me Til-N- (2-hydroxyethyl) propionamide], 2,2'-azobis (2-methylpropionamide), 2,2'-azobis (2,4,4-trimethylpentane), 2,2'- Azobis (2-methylpropane), dimethyl-2,2-azobis (2-methylpropionate), 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis [2- (hydroxymethyl ) Propionitrile] and the like; and the like. In addition, only 1 type may be used independently for these thermal polymerization initiators, and 2 or more types may be used together.

  About content of the said polymerization initiator (F), when using the said ethylenically unsaturated compound (C) 100 weight part (when using a polyfunctional unsaturated compound (E), (C) and (E) The total amount is preferably from 0.01 to 50 parts by weight, particularly preferably from 0.1 to 20 parts by weight, more preferably from 0.3 to 12 parts by weight, particularly preferably from 0. It is preferably 5 to 3 parts by weight. If the content of the polymerization initiator (F) is too small, the curability tends to be poor and the physical properties tend to become unstable, and if it is too much, no further effect can be obtained.

  In the active energy ray irradiation, far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays and other electromagnetic waves, X rays, γ rays and other electromagnetic waves, as well as electron beams, proton rays, neutron rays, etc. can be used. Curing by ultraviolet irradiation is advantageous from the standpoint of availability of the device and price. In addition, when performing electron beam irradiation, it can harden | cure even without using the said photoinitiator (f1).

As a light source for the ultraviolet irradiation, a high pressure mercury lamp, an electrodeless lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, or the like is used. For the high-pressure mercury lamp, for example, 5~3000mJ / cm ^2, preferably at the conditions of 50~2000mJ / cm ^2. Moreover, in the case of the said electrodeless lamp, it is 2-2000 mJ / cm < ² >, for example, Preferably it is performed on the conditions of 10-1000 mJ / cm < ² >. The irradiation time varies depending on the type of the light source, the distance between the light source and the coating surface, the coating thickness, and other conditions, but may be usually from several seconds to several tens of seconds, and in some cases, may be a fraction of a second. On the other hand, in the case of the electron beam irradiation, for example, an electron beam having an energy in the range of 50 to 1000 Kev is used, and the irradiation amount is preferably 2 to 50 Mrad.

  Moreover, when using a thermal-polymerization initiator (f2) as said polymerization initiator (F), a polymerization reaction is started and advanced by heating. The treatment temperature and treatment time during curing by heating vary depending on the type of thermal polymerization initiator (f2) used, and are usually calculated from the half-life of the initiator, but the treatment temperature is usually The temperature is preferably 70 ° C to 170 ° C, and the treatment time is usually preferably 0.2 to 20 minutes, and particularly preferably 0.5 to 10 minutes.

  The crosslinking agent (G) exhibits an excellent adhesive force by reacting with a functional group derived from the functional group-containing monomer (a2) that is a constituent monomer of the acrylic resin (A), Examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, aldehyde-based crosslinking agents, amine-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, an isocyanate type crosslinking agent is suitably used from the point of improving the adhesiveness with the base material and the reactivity with the acrylic resin (A).

  Examples of the isocyanate crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and hexamethylene. Diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and polyisocyanate compounds thereof And adducts of a polyol compound such as trimethylolpropane, and burettes and isocyanurates of these polyisocyanate compounds.

  Examples of the epoxy crosslinking agent include bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. , Trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether and the like.

  Examples of the aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4. '-Bis (1-aziridinecarboxamide), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide) and the like can be mentioned.

  Examples of the melamine-based crosslinking agent include hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexaptoxymethyl melamine, hexapentyloxymethyl melamine, hexahexyloxymethyl melamine, and melamine resin. .

  Examples of the aldehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

  Examples of the amine-based crosslinking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resin, polyamide, and the like.

  Examples of the metal chelate-based crosslinking agent include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium, and zirconium. Can be mentioned.

  Moreover, these crosslinking agents (G) may be used independently and may use 2 or more types together.

  In general, the content of the crosslinking agent (G) is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the acrylic resin (A). Particularly preferred is 0.1 to 2 parts by weight. When the amount of the crosslinking agent (G) is too small, there is a tendency that the cohesive force is insufficient and sufficient durability cannot be obtained. When the amount is too large, the flexibility and adhesive strength are lowered, the durability is lowered, and peeling is caused. Since it tends to occur, the use as an optical member tends to be difficult.

  In addition, the acrylic resin composition includes a silane coupling agent, an antistatic agent, other acrylic pressure-sensitive adhesives, other pressure-sensitive adhesives, urethane resin, rosin, rosin ester, water, as long as the effects of the present invention are not impaired. Adhesive rosin ester, phenolic resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin, tackifier, colorant, filler, anti-aging agent, ultraviolet ray Conventionally known additives such as absorbers and functional dyes, and compounds that cause coloration or discoloration by irradiation with ultraviolet rays or radiation can be blended. The blending amount of these additives is 30 of the entire composition. It is preferably not more than wt%, particularly preferably not more than 20 wt%, and it may contain as little additives as possible low molecular components having a molecular weight lower than 10,000. Preferable from the viewpoint of excellent durability.

  In addition to the above additives, a small amount of impurities contained in the raw materials for producing the constituent components of the pressure-sensitive adhesive composition may be contained.

  In the present invention, the acrylic resin composition obtained above is cured or crosslinked to obtain an acrylic pressure-sensitive adhesive.

  The acrylic pressure-sensitive adhesive of the present invention is preferably used as a pressure-sensitive adhesive layer-containing laminate comprising a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive and a base sheet, a release sheet, or an optical member. Specifically, as an adhesive sheet having an adhesive layer provided on a base sheet, a double-sided adhesive sheet having an adhesive layer provided on a release sheet, and an optical member with an adhesive layer having an adhesive layer provided on an optical member It is preferable to use it.

  Such a pressure-sensitive adhesive sheet can be produced according to a known general pressure-sensitive adhesive sheet production method. For example, the pressure-sensitive adhesive composition can be produced by coating the acrylic resin composition on a substrate sheet and drying the composition. After the layer is formed, the pressure-sensitive adhesive layer can be formed by performing treatment with at least one of active energy ray irradiation and heating, and curing as necessary.

  Examples of the base sheet on which the acrylic resin composition is provided include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, boribylene terephthalate, polyethylene terephthalate / isophthalate copolymer; polyethylene, polypropylene, polymethylpentene, and the like. Polyolefin resins; Polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene; Polyamides such as nylon 6, nylon 6, and 6; Polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-acetic acid Vinyl copolymers such as vinyl copolymers, ethylene-vinyl alcohol copolymers, polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; polymethyl methacrylate, polymetac Acrylic resins such as ethyl oxalate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; synthetic resin sheets such as polyimide, aluminum, copper, iron metal foil, high-quality paper, glassine paper, etc. Woven and non-woven fabrics made of glass fiber, natural fiber, synthetic fiber and the like. These base material sheets can be used as a single layer body or a multilayer body in which two or more kinds are laminated. Among these, a synthetic resin sheet is preferable from the viewpoint of weight reduction.

  Moreover, as said double-sided adhesive sheet, what is necessary is just a double-sided adhesive sheet of the well-known general structure using the said acrylic adhesive, and especially it is excellent in transparency, and the adhesive force with respect to the thickness to comprise is high. A double-sided pressure-sensitive adhesive sheet is preferred.

  Such a baseless double-sided pressure-sensitive adhesive sheet is formed by, for example, forming the pressure-sensitive adhesive composition layer obtained by coating the acrylic resin composition on a release sheet and drying it, and then releasing the pressure-sensitive adhesive layer. A pressure-sensitive adhesive layer can be formed by further bonding another release sheet to the side without the sheet, performing treatment with at least one of irradiation with active energy rays and heating, and curing as necessary. As for the method of use, after peeling off one release sheet and bonding it to the adherend, the other release sheet may be peeled off and bonded to the adherend.

  Furthermore, in the present invention, the acrylic pressure-sensitive adhesive is preferably used as a pressure-sensitive adhesive for optical members, and the pressure-sensitive adhesive layer is provided by laminating and forming a pressure-sensitive adhesive layer made of the acrylic pressure-sensitive adhesive on the optical member. An optical member can be obtained.

  Examples of such optical members include transparent electrode films such as ITO electrode films and organic conductive films such as polythiophene, polarizing plates, retardation plates, elliptical polarizing plates, optical compensation films, brightness enhancement films, electromagnetic wave shielding films, and near-infrared absorbing films. And AR (anti-reflection) film. Among these, when the optical member is a transparent electrode film, the effect of the present invention can be remarkably exhibited and high adhesive force is obtained, and an ITO electrode film is particularly preferable. The ITO electrode film is often formed as a thin film on a substrate such as glass or PET.

  Here, when the acrylic resin composition of the present invention is used for the optical member, the acrylic resin (A) and the ethylenically unsaturated compound (C) do not contain an acidic group, particularly corrosion. It is preferable that it does not easily occur. Furthermore, it is more preferable that the entire composition does not contain an acidic group.

  In addition, specifically, it means that the acid value is not more than 10 mgKOH / g, particularly preferably not more than 1 mgKOH / g, and more preferably not more than 0.1 mgKOH / g.

  In the optical member with the pressure-sensitive adhesive layer, it is preferable to further provide a release sheet on the surface opposite to the optical member surface of the pressure-sensitive adhesive layer. An adhesive layer and an adherend will be bonded. As such a release sheet, a silicon-based release sheet is preferably used.

  As a manufacturing method of the optical member with an adhesive layer by which the said release sheet was bonded, [1] After apply | coating and drying a resin composition on an optical member, the release sheet is bonded and active energy rays. Method of performing treatment by at least one of irradiation and heating, [2] After applying and drying the resin composition on the release sheet, the optical member is bonded, and the treatment by at least one of active energy ray irradiation and heating A method of performing, [3] a method of applying a resin composition on an optical member, drying, and further performing treatment by at least one of active energy ray irradiation and heating, and then bonding a release sheet; [4] mold release The resin composition can be applied on a sheet, dried, and further subjected to treatment by at least one of active energy ray irradiation and heating, followed by a method of bonding an optical member. Among these, the case of performing only the active energy ray irradiation by the method [2] is preferable from the viewpoint of not damaging the substrate, workability and stable production.

  Up to here, after manufacturing the optical member with the pressure-sensitive adhesive layer once the release sheet is bonded, the pressure-sensitive adhesive that bonds the pressure-sensitive adhesive layer and the adherend (other optical members) after peeling off the release sheet. Although the usage method of the agent was demonstrated, you may use the method of bonding optical members using the above-mentioned double-sided adhesive sheet.

  The adhesive layer contained in the said adhesive sheet, a double-sided adhesive sheet, and an optical member with an adhesive layer is demonstrated. Such an adhesive layer is formed by applying an acrylic resin composition on a substrate sheet, a release sheet, or an optical member, and drying to form an adhesive composition layer. It is preferable to manufacture by the method which performs the process by one side and performs an aging process as needed.

  The acrylic resin composition is applied by a conventional method such as roll coating, die coating, gravure coating, comma coating, or screen printing.

  In producing such a pressure-sensitive adhesive layer, the drying temperature in the drying step is usually 50 ° C. to 250 ° C., preferably 60 ° C. to 120 ° C., more preferably 65 ° C. to 95 ° C. Moreover, when using a compound with a low flash point as an ethylenically unsaturated compound (C), it is preferable to dry at 70 to 90 degreeC, Most preferably, it is 75 to 85 degreeC.

  The drying time is usually 10 seconds to 10 minutes, and drying at a low temperature for a longer time can surely volatilize and remove the organic solvent (B), and does not volatilize the ethylenically unsaturated compound (C). This is preferable in that it can remain in the composition layer. In consideration of economy and production efficiency, it is preferable that the drying time is short.

  In the present invention, the residual ratio of the acrylic resin (A) in the pressure-sensitive adhesive composition layer after drying is 90% by weight or more, more preferably 95% by weight or more, and the residual ratio of the organic solvent (B) is 5% by weight. Hereinafter, more preferably 1% by weight or less, the residual ratio of the ethylenically unsaturated compound (C) is 50% by weight or more, preferably 75% by weight or more, and the residual ratio of the thiol compound (D) is 25% by weight or more, preferably It is preferably 50% by weight or more, particularly preferably 80% by weight or more from the viewpoint that the pressure-sensitive adhesive composition layer can be efficiently formed.

  The pressure-sensitive adhesive composition layer thus obtained is subjected to treatment by at least one of active energy ray irradiation and heating, and if necessary, an aging treatment is performed to balance the pressure-sensitive adhesive properties, whereby a pressure-sensitive adhesive layer is formed. A pressure-sensitive adhesive sheet, a double-sided pressure-sensitive adhesive sheet, and an optical laminate with a pressure-sensitive adhesive layer are produced.

  Such active energy ray irradiation conditions are as described above.

  Such aging treatment is preferably carried out particularly when the crosslinking agent (G) is used in the acrylic resin composition. As conditions for such aging 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 treatment may be performed at 23 ° C. for 1 day to 20 days, preferably at 23 ° C. for 3 to 10 days, at 40 ° C. for 1 day to 7 days, and the like.

The gel fraction of the pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer of the optical member with the pressure-sensitive adhesive layer is preferably 5 to 70%, particularly preferably 10 to 65% in terms of excellent adhesion. Preferably, it is more preferably 15 to 60%.
If the gel fraction is too low, the pressure-sensitive adhesive is too soft, and the processability tends to decrease. Moreover, when a gel fraction is too high, there exists a tendency for the adhesiveness to a base material to fall.

  In addition, in adjusting a gel fraction to the said range, it is achieved by adjusting the kind and quantity, such as a kind and quantity of a crosslinking agent, and polyfunctional acrylate, etc., for example.

  The gel fraction is a measure of the degree of crosslinking (curing degree), and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (not provided with a separator) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, polyethylene terephthalate film or the like) as a base material is wrapped with a 200-mesh SUS wire mesh, and 23 in toluene. The weight percentage of the insoluble pressure-sensitive adhesive component immersed in the wire mesh at 24 ° C. for 24 hours is defined as the gel fraction. However, the weight of the substrate is subtracted.

The thickness of the pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer of the optical member with the pressure-sensitive adhesive layer is usually preferably 5 to 3000 μm, particularly preferably 50 to 3000 μm, and more preferably 100 to 1000 μm. It is preferable that there is, and it is especially preferable that it is 120-350 micrometers.
If the thickness of the pressure-sensitive adhesive layer is too thin, the impact absorbability tends to be insufficient, and if it is too thick, the thickness of the entire optical member tends to increase too much.

  In the acrylic resin composition of the present invention, as described above, under a general drying condition, it contains a specific proportion of an ethylenically unsaturated compound that is difficult to volatilize together with an organic solvent that easily volatilizes. This is an excellent material, and it is possible to obtain a thick film pressure-sensitive adhesive layer that could not be obtained by coating and drying with a conventional solvent-based acrylic pressure-sensitive adhesive composition.

In the case of obtaining the above thick adhesive layer, it is preferably applied with a film thickness of 100 μm or more, particularly preferably 110 μm or more, and more preferably 250 μm or more. The film thickness is usually 3000 μm.
In particular, when used for applications such as shock absorption and air gap filling, the thickness of the pressure-sensitive adhesive layer after drying is preferably 100 μm or more, particularly preferably 120 μm or more. Is usually 2000 μm.

  In addition, the film thickness in this invention subtracts the measured value of the thickness of structural members other than an adhesive layer from the measured value of the thickness of the adhesive layer containing laminated body whole using "ID-C112B" by Mitutoyo Corporation. It is the value calculated | required by.

  The adhesive strength of the pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer of the optical member with the pressure-sensitive adhesive layer is appropriately determined according to the material of the adherend. When sticking to a methyl methacrylate plate and a PET sheet having an ITO layer deposited thereon, it preferably has an adhesive strength of 5 N / 25 mm to 500 N / 25 mm, more preferably 10 N / 25 mm to 100 N / 25 mm.

  The adhesive strength is calculated as follows. A 100 μm-thick polyethylene terephthalate (PET) sheet with a 100 μm thick adhesive layer-formed PET is cut to a width of 25 mm, the release sheet is peeled off, and the adhesive layer side is covered with the above-mentioned coated layer. The above adhesive sheet of 25 mm × 100 mm was applied to the body by pressurizing and reciprocating 2 kg rubber rollers in an atmosphere of 23 ° C. and 50% relative humidity, and left in the same atmosphere for 30 minutes, and then peeled at a room temperature of 300 mm / min. 180 degree peel strength (N / 25mm) was measured.

  The total line transmittance of the pressure-sensitive adhesive sheet, double-sided pressure-sensitive adhesive sheet, and pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached optical member is preferably 85% or more, particularly preferably 90% or more, and still more preferably. Is 92% or more. If the total line transmittance is too low, the transmittance is low, so that it tends to be difficult to use in display applications. The upper limit of the total light transmittance is usually 95%.

  The haze value of the pressure-sensitive adhesive sheet, double-sided pressure-sensitive adhesive sheet, and pressure-sensitive adhesive layer of the optical member with a pressure-sensitive adhesive layer is preferably 10% or less, particularly preferably 2% or less. If the haze value is too high, the image tends to be unclear when used for display. The lower limit of the haze value is usually 0.00%.

  Here, the above-mentioned total line transmittance and haze value are values measured using a haze meter based on JIS K7361-1.

The color difference b value of the pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer of the optical member with the pressure-sensitive adhesive layer is preferably 1 or less, particularly preferably 0.5 or less. If the color difference b value is too high, the original color tends to be difficult to be obtained when used for display. The lower limit of the color difference b value is normally -1.
Here, the color difference b value is measured according to JIS K7105, and the measurement is performed under transmission conditions using a color difference meter (Σ90: manufactured by Nippon Denshoku Industries Co., Ltd.).

  In the present invention, the measurement of haze, total light transmittance, and color difference b value was carried out using an alkali-free glass (total light transmittance = 93, haze = 0.06, b value = 0). .16) and measured.

  The acrylic pressure-sensitive adhesive comprising the acrylic resin composition of the present invention is made of glass, ITO transparent electrode sheet, optical sheets such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polarizing plate, It is useful for attaching optical members such as a phase difference plate, an optical compensation film, and a brightness enhancement film. Furthermore, it can be suitably used for an image display device such as a touch panel including these optical members.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “parts” and “%” mean weight basis.

  First, various acrylic resin (A) solutions (including the organic solvent (B)) were prepared as follows. In addition, regarding the measurement of the weight average molecular weight, dispersion degree, and glass transition temperature of acrylic resin (A), it measured according to the above-mentioned method.

  Regarding the measurement of the solid content concentration, 1 to 2 g of acrylic resin (A) solution was taken on aluminum foil, dried by heating for 45 minutes with a ket (infrared dryer, 185 W, height 5 cm), and the weight change before and after drying. The viscosity was measured according to the JIS K5400 (1990) 4.5.3 rotational viscometer method.

[Preparation of acrylic resin (A) solution (including organic solvent (B)]]

[Acrylic resin (A-1)]
A four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer was charged with 150 parts of ethyl acetate, and 0.04 part of azobisisobutyronitrile (AIBN) as a polymerization initiator. The mixture was heated with stirring, and a mixture of 70 parts of 2-ethylhexyl acrylate (2EHA) and 30 parts of 2-hydroxyethyl acrylate (HEA) was added dropwise at reflux temperature over 2 hours. After reacting at the ethyl acetate reflux temperature for 1.5 hours, the reaction mixture was diluted with ethyl acetate to obtain an acrylic resin solution (solid content concentration 50%, viscosity 15000 mPa · s (25 ° C.)). To 100 parts (resin content) of the obtained acrylic resin solution, 0.08 part of dibutylhydroxytoluene and 0.07 part of 2-methacryloyloxyethyl isocyanate were charged and reacted at 50 ° C. for 30 hours. Active energy ray-reactive acrylic resin (A-1) solution in which 0.2 mol% of ethylenically unsaturated groups are added to the side chain to hydroxyethyl acrylate (weight average molecular weight 1.4 million; dispersity 9.2; resin Min. 50%; viscosity 15000 mPa · s (25 ° C.)).

[Organic solvent (B)]
The following were prepared as the organic solvent (B).
B-1: ethyl acetate (flash point: -3 ° C)

[Ethylenically unsaturated compound (C)]
The following were prepared as the ethylenically unsaturated compound (C).
C-1: Isostearyl acrylate (manufactured by Osaka Organic Chemical Industry, “ISTA”); flash point 154 ° C .; molecular weight 324

[Thiol Compound (D)]
The following were prepared as the thiol compound (D).
D-1: trimethylolpropane tris (3-mercaptopropionate) (manufactured by SC Organic Chemical Co., Ltd., trade name “TMMP”; functional group number 3; molecular weight 398.5)
D-2: Pentaerythritol tetrakis (3-mercaptobutyrate): (trade name “Karenz MT PE1” manufactured by Showa Denko KK; functional group number 4; molecular weight 544.8)
D-3: 1-dodecanethiol: (made by Kishida Chemical Co., Ltd., trade name “1-dodecanethiol”
Functional group number 1; molecular weight 202.4)

[Polyfunctional unsaturated compound (E)]
The following were prepared as the polyfunctional unsaturated compound (E).
E-1: Tripropylene glycol diacrylate ("TPGDA" manufactured by Daicel-Cytec)
E-2: 1.9-nonanediol diacrylate (“Light acrylate 1.9-NDA” manufactured by Kyoeisha Chemical)
E-3: trimethylolpropane triacrylate (manufactured by Toagosei Co., Ltd., “Aronix M-309”)
E-4: urethane acrylate (“UV-1700B” manufactured by Nippon Synthetic Chemical Co., Ltd.)

[Photoinitiator (F)]
F-1: 1: 1 mixture of 1-hydroxycyclohexyl phenyl ketone and benzophenone (Ciba Japan, “Irgacure 500”)

[Example 1]
100 parts of acrylic resin (A-1) (resin content), ethylenically unsaturated compound (C-1) in a four-necked round bottom flask equipped with a reflux condenser, stirrer, nitrogen gas inlet and thermometer ) 100 parts, 3 parts of a thiol compound (D-1), 1 part of a polyfunctional unsaturated compound (E-1), 1 part of a photopolymerization initiator (F) are simultaneously charged, and the blending amount of the organic solvent (B) is 70. It prepared so that it might become a part, and the acrylic resin composition solution was obtained by mixing.

[Examples 2 to 10, Comparative Examples 1 to 3]
An acrylic resin composition solution was prepared by blending the blended components prepared and prepared as described above in the proportions shown in Tables 1 and 2 below.

Then, the acrylic resin composition solution obtained above is applied to a polyester release sheet so that the thickness after drying is 175 μm, and dried at 100 ° C. for 5 minutes to form an adhesive composition layer. I let you. The obtained pressure-sensitive adhesive composition layer is sandwiched between polyester release sheets and irradiated with ultraviolet rays at a peak illuminance of 150 mW / cm ² and an integrated exposure amount of 1000 mJ / cm ² using a high-pressure mercury UV irradiation apparatus (500 mJ / cm ² × 2 pass) A substrate-less double-sided PSA sheet was obtained.

  Using the substrate-less double-sided pressure-sensitive adhesive sheet obtained above, the gel fraction, adhesive strength, blister resistance, and step following ability were measured and evaluated according to the following methods. These results are shown in Table 1 and Table 2 below.

[Gel fraction]
After cutting the substrate-less double-sided pressure-sensitive adhesive sheet into 40 mm × 40 mm, the single-sided release sheet was peeled off, and the pressure-sensitive adhesive layer side was bonded to a 50 mm × 100 mm SUS mesh sheet (200 mesh). When lightly applied to the SUS mesh sheet, the other release sheet is peeled off, folded back from the center with respect to the longitudinal direction of the SUS mesh sheet, wrapped in a sample, and immersed in a sealed container containing 250 g of toluene. The gel fraction (%) was measured based on the weight change.

[Adhesive force]
After the substrate-less double-sided pressure-sensitive adhesive sheet was cut into 40 mm × 40 mm, the single-sided release sheet was peeled off and pressed onto a 125 μm thick easy-adhesive PET (polyethylene terephthalate) film to obtain a PET film with a pressure-sensitive adhesive layer. The PET film with the pressure-sensitive adhesive layer was cut into a width of 25 mm and a length of 100 mm, the release sheet was peeled off, and the pressure-sensitive adhesive layer side was placed on soda glass at 23 ° C. and a relative humidity of 50% in a 2 kg rubber roller 2 After applying pressure by reciprocating and leaving it in the same atmosphere for 30 minutes, 180 degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min at room temperature.

[Blister resistance]
The PET film with the pressure-sensitive adhesive layer is cut into a width of 25 mm and a length of 100 mm, the release sheet is peeled off, and the pressure-sensitive adhesive layer side is placed on a polycarbonate plate at 23 ° C. and 50% relative humidity in a 2 kg rubber roller 2 After pressure reciprocating in a reciprocating manner, autoclaving was performed at 0.5 MPa × 50 ° C. for 20 minutes, and then left at 80 ° C. After 24 hours, the generation of bubbles was confirmed visually. The evaluation criteria are as follows.
(Evaluation criteria)
○… There are no bubbles exceeding φ0.5mm. Δ… There are bubbles exceeding φ0.5mm, but the bubble generation area is less than 1/3 of the entire pasting surface.

[Step following capability]
A 5 μm wide 25 μm PET film and a 50 μm PET film were adhered to a soda glass plate with a rubber roller to form steps of 25 μm and 50 μm, respectively. A PET film with an adhesive layer cut to a width of 25 mm and a length of 100 mm was peeled off from the test substrate, the release sheet was peeled off, and the adhesive layer side was placed on a soda glass plate at 23 ° C. and a relative humidity of 50%. 2kg rubber roller with 2 reciprocating pressures, autoclave treatment at 0.5MPa x 50 ° C for 20 minutes, then left at 80 ° C x 90%, and after 3 days confirmed. The evaluation criteria are as follows.
(Evaluation criteria)
◎: No bubbles or floats are observed. ○: Slightly small bubbles or floats are observed. △: Large bubbles are observed and the bubbles may be connected. ×: Large bubbles are connected and parallel to the step. There is a float

※表中（ ）内の数字は重量部を表す。また、――は配合しなかったことを表す。

* Numbers in parentheses in the table represent parts by weight. In addition,-indicates that it was not blended.

  Moreover, about Examples 1-10 and Comparative Examples 1-3, the alkali-free glass plate with an adhesive layer was produced as follows using the base-material-free double-sided adhesive sheet obtained above, total light transmittance, The haze and color difference b value were measured and evaluated according to the following methods. These results are shown in Table 3 below.

[Production of alkali-free glass plate with adhesive layer]
The above PET sheet with pressure-sensitive adhesive is cut out to 3 cm × 4 cm, the heavy release release sheet is peeled off, and the pressure-sensitive adhesive layer side is pressed against a non-alkali glass plate (Corning Co., Ltd., Eagle XG). An alkali glass plate was obtained.

[Total light transmittance] and [Haze]
The diffuse transmittance and total light transmittance of the alkali-free glass plate with the pressure-sensitive adhesive layer were measured using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). This machine complies with JIS K7361-1.
The values of the obtained diffuse transmittance and total light transmittance were substituted into the following formula to calculate haze.
Haze (%) = (diffuse transmittance / total light transmittance) × 100

[Color difference b value]
The color difference b value of the alkali-free glass plate with the pressure-sensitive adhesive layer was measured according to JIS K7105. The measurement was performed under transmission conditions using a color difference meter (Σ90: manufactured by Nippon Denshoku Industries Co., Ltd.).

  In addition, only the glass plate WHEREIN: The value at the time of measuring the said total light transmittance, haze, and color difference b value was 93% of total light transmittance, haze 0.1%, and color difference b value 0.2.

Examples 1 to 10 containing a thiol compound (D) in addition to the acrylic resin (A), the organic solvent (B), and the liquid ethylenically unsaturated compound (C) containing one ethylenically unsaturated group It can be seen that this acrylic resin composition is excellent in blister resistance, level difference followability and optical characteristics. This is considered to be a result of the chain transfer effect by thiol and the increase in the number of crosslinking points, as well as the improvement of adhesion and cohesive force by introduction of sulfur atom into the crosslinked part or terminal part by ene-thiol reaction.

  On the other hand, in the acrylic resin compositions of Comparative Examples 1 to 3 that do not contain the thiol compound (D), it can be seen that both the blister resistance and the step following ability are insufficient.

  The acrylic pressure-sensitive adhesive composed of the acrylic resin composition of the present invention can be suitably used as a pressure-sensitive adhesive sheet, in particular, a double-sided pressure-sensitive adhesive sheet, especially a double-sided pressure-sensitive adhesive sheet that does not have a base material (no base material), Optical sheets such as glass, ITO transparent electrode sheet, polyethylene terephthalate (PET), polycarbonate (PC), and polymethyl methacrylate (PMMA) because they have high adhesive strength, high light transmittance, and are less likely to cause haze. It is useful for application of optical members such as polarizing plates, retardation plates, optical compensation films, and brightness enhancement films. Furthermore, it can be suitably used for a touch panel including these optical members.

Claims (10)

Acrylic resin (A),
Organic solvent (B),
Liquid ethylenically unsaturated compound (C) containing one ethylenically unsaturated group and thiol compound (D) (excluding silane compounds)
Containing
The content ratio (weight ratio) between the acrylic resin (A) and the liquid ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is (A) :( C) = 10: 90 to 75: 25,
The flash point (° C) of the organic solvent (B) is Bf.p., and the flash point (° C) of the liquid ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is Cf.p. An acrylic adhesive characterized in that it is obtained from an acrylic resin composition having a Cf.p. higher than Bf.p. and a difference between Cf.p. and Bf.p. Agent . The acrylic pressure - sensitive adhesive according to claim 1, wherein the thiol compound (D) is a 2-4 functional thiol compound. The acrylic pressure - sensitive adhesive according to claim 1 or 2, wherein the content of the thiol compound (D) is 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic resin (A). A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive according to claim 1. The pressure-sensitive adhesive sheet according to claim 4 , wherein the pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive layer has a gel fraction of 5 to 70%. A double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive according to claim 1. A pressure-sensitive adhesive for transparent electrodes, comprising the acrylic pressure-sensitive adhesive according to claim 1. A touch panel comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive for transparent electrodes according to claim 7 . An image display device comprising an adhesive layer containing the acrylic adhesive according to claim 1. The claims 1-3 acrylic resin composition according to any one of the substrate sheet, the release sheet or coated on an optical member, and dried to active energy rays or you polymerized by thermal viscosity Chakuzaiso containing laminate, The acrylic resin (A) residual rate in the pressure-sensitive adhesive layer after drying is 90% by weight or more, the organic solvent (B) residual rate is 5% by weight or less, and an ethylenically unsaturated group. The residual ratio of the liquid ethylenically unsaturated compound (C) containing one of the above is 50% by weight or more, and the residual ratio of the thiol compound (D) is 25% by weight or more. Manufacturing method .