JP5904860B2 - Acrylic resin composition, acrylic pressure-sensitive adhesive, pressure-sensitive adhesive sheet, double-sided pressure-sensitive adhesive sheet, pressure-sensitive adhesive for transparent electrode, touch panel and image display device, and method for producing pressure-sensitive adhesive layer-containing laminate - Google Patents

Description

  The present invention relates to an acrylic resin composition, an acrylic pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a double-sided pressure-sensitive adhesive sheet, a transparent electrode pressure-sensitive adhesive, a touch panel, an image display device, and a method for producing a pressure-sensitive adhesive layer-containing laminate. The present invention relates to an acrylic resin composition used for an active energy ray-curable solvent-based acrylic pressure-sensitive adhesive that is suitable for thick coating and has excellent step following ability.

  Conventionally, acrylic adhesives are strong adhesives that are intended to bond adherends firmly for a long period of time, or peel-off types based on the premise that they are peeled off from adherends after being attached. There are various types of pressure-sensitive adhesives such as pressure-sensitive adhesives, and pressure-sensitive adhesives having optimized adhesive properties are designed and used in various fields.

  In recent years, the properties required of adhesives include not only adhesive properties such as adhesive strength, but also transparency and impact resistance to the adhesive layer itself when used for bonding glass substrates in liquid crystal display devices and the like. Absorptivity is required.

For example, in mobile devices such as TVs, monitors for personal computers, notebook computers, mobile phones, and tablet terminals, a protective layer formed from a plastic sheet or the like is usually provided on the viewing side of the liquid crystal display, or due to external impacts. In order to prevent damage to the liquid crystal display, a space (air layer) is provided between the liquid crystal display and the protective layer.
However, there is a problem that reflection occurs at the interface between the protective layer and the air layer and at the interface between the air layer and the liquid crystal display, resulting in a decrease in visibility. Therefore, the impact-absorbing pressure-sensitive adhesive layer described above is used instead of the air layer for the purpose of improving visibility and further reducing the thickness of the plastic sheet (mobile device) while ensuring impact resistance. In order to improve the shock-absorbing performance, it has been proposed to increase the thickness of the pressure-sensitive adhesive layer.

  As a method for thickening the adhesive layer using an acrylic resin (coating a thick film), a dilution monomer ((meth) acrylic acid derivative ((meth) acrylic acid derivative (B)) is added to an acrylic resin ((meth) acrylic acid derivative polymer (B)). A)) and a solvent-free active energy ray-curable pressure-sensitive adhesive comprising a polyfunctional compound (polyfunctional (meth) acrylic acid derivative (C)) as a curing component is known (for example, patents) Reference 1).

  The active energy ray-curable pressure-sensitive adhesive generally does not contain a solvent used for viscosity adjustment with a normal acrylic pressure-sensitive adhesive, and a photopolymerizable unsaturated monomer as a dilution monomer instead of the solvent. Since it is a solvent-free pressure-sensitive adhesive used, there is no need for a drying step to remove the solvent after coating the pressure-sensitive adhesive, and it is possible to obtain a pressure-sensitive adhesive layer efficiently in a short time even when thick coating is applied. It can be done.

JP 2009-57550 A

  However, acrylic resins that can be used as solvent-free pressure-sensitive adhesives are only acrylic resins produced by a fairly limited method, such as (i) acrylic resins produced by bulk polymerization, (Ii) Once an acrylic resin was produced by solution polymerization or suspension polymerization, it was necessary to use an acrylic resin produced by drying and removing the solvent.

Here, in the case of producing by the method (i), it is difficult to produce an acrylic resin with good reproducibility due to poor polymerization stability, the reaction heat is difficult to control, the safety is low, and there are many reaction components. There was a problem that the reaction was so intense that heat removal was difficult and the production efficiency was poor.
Furthermore, even in the case of producing by the method (ii), large energy and time are required to remove the solvent and water from the acrylic resin containing the solvent (solvent and water) once produced, and the production efficiency is poor. there were. In particular, it is very difficult to completely remove the remaining solvent from the acrylic resin from which a certain amount of the solvent has been removed and the viscosity becomes high, and the residual solvent may adversely affect the physical properties of the adhesive. In addition, acrylic resins with a low glass transition temperature that are mainly used as pressure-sensitive adhesives, when dried up, the acrylic resin aggregates into an indefinitely insoluble gel and is difficult to handle. It was difficult and time-consuming to dissolve in the monomer again.

  Therefore, solvent-free pressure-sensitive adhesives are suitable for thick coating, but have the problem that the degree of freedom of acrylic resins that can be used is low, and acrylic pressure-sensitive adhesives having desired physical properties can be obtained. Since it was difficult, it was possible to design acrylic resin freely, and in terms of enabling more efficient production, a solvent that can use acrylic resin (solvent-containing one) produced by solution polymerization. This type of adhesive was more preferable than the solventless adhesive.

  However, when using solvent-based adhesives for thick coating applications, the adhesive layer is thick at the time of coating, so the solvent is less likely to volatilize during the drying process after coating, and foams into the adhesive layer. More specifically, the solvent on the surface of the pressure-sensitive adhesive layer is volatilized and the surface becomes hard, so that bubbles that try to evaporate from below or inside the pressure-sensitive adhesive layer remain inside the pressure-sensitive adhesive layer. There was a problem that the phenomenon that happens.

In recent years, in various fields, display devices such as liquid crystal displays (LCD) and input devices used in combination with the display devices such as touch panels have come to be widely used. Transparent adhesive sheets are used for applications where optical members are bonded together.
For example, a transparent double-sided pressure-sensitive adhesive sheet is used for pasting a touch panel and various display devices and optical members (protection plates, etc.). Some of the touch panels, etc. include members having steps such as printing steps. In such an application, the pressure-sensitive adhesive sheet is required to have a capability of filling a printing step at the same time as a performance of sticking and fixing a member, that is, an excellent step following capability.

  Therefore, in the present invention, under such a background, it is possible to apply thick coating, it is possible to obtain a pressure-sensitive adhesive layer on the surface of a beautiful coating film, and an active energy ray curable type excellent in step following ability An object of the present invention is to provide an acrylic resin composition used in the production of a solvent-based acrylic pressure-sensitive adhesive.

  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. Using an organic solvent and blending a specific proportion of a non-volatile ethylenically unsaturated monomer containing a (meth) acrylic acid ester monomer as a main component, thickly coat the adhesive, and then dry the solvent In this case, since the liquid ethylenically unsaturated monomer remains, the viscosity of the pressure-sensitive adhesive layer can be prevented from excessively increasing, and the pressure-sensitive adhesive layer surface can be prevented from becoming hard. It is found that the solvent easily evaporates even during coating, has excellent drying suitability, and uses a (meth) acrylic acid ester monomer with a specific structure, which also has excellent step following ability. This has led to the completion of the present invention.

That is, the gist of the present invention includes an acrylic resin (A), an organic solvent (B), and an ethylenically unsaturated compound (C) containing one ethylenically unsaturated group, and an acrylic resin (A). And an acrylic resin composition in which the content (weight ratio) of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is (A) :( C) = 10: 90 to 90:10 [I] The flash point (° C.) of the organic solvent (B) is set to B _{f. p.} The flash point (° C.) of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is expressed as C _{f. p.} C _{f. p.} Is B _f. higher than _p. and C _{f. p.} and B _f. The difference in _p. is 50 ° C. or higher, and [II] an ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is a (meth) acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms. An acrylic resin composition containing 50% by weight or more of the compound (C1).

  Furthermore, the present invention provides an acrylic pressure-sensitive adhesive, pressure-sensitive adhesive sheet, double-sided pressure-sensitive adhesive sheet, transparent electrode pressure-sensitive adhesive, touch panel, image display device, and method for producing a pressure-sensitive adhesive layer-containing laminate using the acrylic resin composition. It is about.

  The acrylic resin composition 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. In addition, the solvent-based acrylic pressure-sensitive adhesive containing an acrylic resin is excellent in coating suitability during thick coating, which has been difficult to achieve. That is, even when thick coating is performed using such an acrylic resin composition and an acrylic pressure-sensitive adhesive is obtained, dripping of the liquid, coating streaks, disturbance of the pressure-sensitive adhesive layer due to concentrated foaming of the solvent, etc. It does not occur, and the solvent can be easily dried. Further, the obtained pressure-sensitive adhesive layer has excellent step following ability, durability, adhesive strength, holding power, transparency, corrosion resistance, and the like.

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.

  The monomer component constituting the acrylic resin (A) used in the present invention contains a (meth) acrylic acid ester monomer (a1) as a main component, preferably a hydroxyl group and / or alkoxy group-containing monomer (a2), As long as it contains a functional group-containing monomer (a3) other than (a2) and other copolymerizable monomer (a4) as required, a monomer and a hydroxyl group and / or alkoxy group-containing monomer (a2) ), Using a functional group-containing monomer (a3) other than (a2) is a cross-linking point for the acrylic resin (A), and further increases the adhesion to the substrate and adherend. preferable.

  As such a (meth) acrylic acid ester monomer (a1), the alkyl group usually has 1 to 20, particularly 1 to 12, more preferably 1 to 8, and particularly preferably 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 Of (meth) acrylic acid alkyl ester, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate alicyclic of (meth) acrylic acid ester. These can be used alone or in combination of two or more.

  Among these (meth) acrylic acid ester monomers (a1), n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable in terms of copolymerizability, adhesive properties, ease of handling, and availability of raw materials. Is preferably used, and 2-ethylhexyl acrylate is more preferably used in terms of excellent step following ability.

  The content of the (meth) acrylic acid ester monomer (a1) in the monomer component is preferably 10 to 100% by weight, particularly preferably 50 to 95% by weight, and further preferably 60 to 90% by weight. If the content of the (meth) acrylic acid ester monomer (a1) is too small, the adhesive strength when used as an adhesive tends to be insufficient.

  Examples of the hydroxyl group and / or alkoxy group-containing monomer (a2) include the following, but the hydroxyl group-containing monomer is superior to the alkoxy group-containing monomer in terms of transparency when used under high temperature and high humidity. This is preferable.

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 ( Hydroxyalkyl esters of acrylic acid such as (meth) acrylate, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, oxyalkylene-modified monomers such as diethylene glycol (meth) acrylate and polyethylene glycol (meth) acrylate, 2- acryloyloxyethyl - primary hydroxyl group-containing monomers such as 2-hydroxyethyl phthalate; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth ) Secondary hydroxyl group-containing monomers such as acrylate and 3-chloro-2-hydroxypropyl (meth) acrylate; and tertiary hydroxyl group-containing monomers such as 2,2-dimethyl 2-hydroxyethyl (meth) acrylate.

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

  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 alkoxy group-containing monomer include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and the like. Can be given.

The content of the hydroxyl group and / or alkoxy group-containing monomer (a2) in the monomer component is preferably 0.1 to 70% by weight, particularly preferably 0.5 to 55% by weight, and more preferably 10%. -40% by weight, particularly preferably 15-30% by weight.
If the content of the hydroxyl group and / or alkoxy group-containing monomer (a2) is too small, the heat-and-moisture whitening tends to be inferior, and if it is too much, the adhesive property tends to be inferior.

  As other functional group-containing monomer (a3) other than the above (a2) (hereinafter sometimes referred to as “functional group-containing monomer (a3)”), by reacting with a crosslinking agent (F) described later. Any monomer may be used as long as it contains a functional group that can serve as a crosslinking point, and examples thereof include carboxyl group-containing monomers, amino group-containing monomers, acetoacetyl group-containing monomers, isocyanate group-containing monomers, and glycidyl group-containing monomers. A carboxyl group-containing monomer is preferable in that a crosslinking reaction can be efficiently performed.

  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 cinnamon. An acid etc. are mentioned, Especially, (meth) acrylic acid is used preferably.

  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 (a3) may be used alone or in combination of two or more.

  The content of the functional group-containing monomer (a3) in the monomer component is preferably 0.01 to 30% by weight, particularly preferably 0.05 to 10% by weight, more preferably 0.1 to 10% by weight, Particularly preferred is 2 to 5% by weight. If the content of the functional group-containing monomer (a3) is too small, the cohesive force tends to be insufficient, so that the durability performance tends to decrease. If the content is too large, the viscosity increases or the stability of the resin decreases. There is.

  Examples of the other copolymerizable monomers (a4) (excluding (a1) to (a3)) include, for example, phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenyldiethylene glycol. Monomers containing one aromatic ring such as (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, styrene, α-methylstyrene; biphenyloxy structure-containing (meta) such as biphenyloxyethyl (meth) acrylate (meta ) Acrylic acid ester monomer; ethoxymethyl (meth) acrylamide, n-butoxymethyl (meth) acrylamide, (meth) acryloylmorpholine, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth) acrylamid (Meth) acrylamide monomers such as N-methylol (meth) acrylamide; monomers containing an oxyalkylene group such as polypropylene glycol mono (meth) acrylate; 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 vinyl ketone, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, etc. Can be mentioned.

  The content of the other copolymerizable monomer (a4) in the monomer 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 polymerizable monomers (a4), there exists a tendency for an adhesive characteristic to fall easily.

Thus, the (meth) acrylic acid ester monomer (a1), preferably a hydroxyl group and / or alkoxy group-containing monomer (a2), a functional group-containing monomer (a3), and other copolymerizable monomers (a4) as necessary. Acrylic resin (A) is produced by polymerizing as a monomer component. In such polymerization, production by solution polymerization can be performed safely and stably in any monomer composition with an acrylic resin ( A) is preferable in that it can be produced.
In such solution polymerization, for example, a (meth) acrylic acid ester monomer (a1), a hydroxyl group and / or alkoxy group-containing monomer (a2), a functional group-containing monomer (a3), and other copolymerizable monomers in an organic solvent. A monomer component such as (a4) and a polymerization initiator may be mixed or dropped, and polymerization may be performed in a reflux state 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 (A) 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 (A) 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 (A) is preferably −80 to 10 ° C., particularly preferably −60 to −20 ° C., more preferably −55 to −45 ° C. When the glass transition temperature is too high. Tack tends to be insufficient, and if it is too low, heat resistance tends to decrease. Outside the scope of the examples.

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)

  In addition, when the acrylic pressure-sensitive adhesive of the present invention is used in an information label application or an electronic member fixing application that is bonded to a transparent electrode for touch panel or other electronic member, particularly a precision electronic member, it is corrosion resistant. In this case, it is preferable that the acrylic resin (A) does not contain an acidic group.

  As the acrylic resin (A) used in the present invention, an acrylic resin having 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. It is preferable that the resin is an acrylic resin containing an ethylenically unsaturated group, in that an adhesive layer can be formed without aging.

  The ethylenically unsaturated group-containing acrylic resin is one in which an acrylic resin having a functional group in the molecule is reacted with an ethylenically unsaturated compound having a functional group that reacts with the functional group in the molecule. Examples of the ethylenically unsaturated compound include the carboxyl group-containing unsaturated monomer, the hydroxyl group-containing unsaturated monomer, the glycidyl group-containing unsaturated monomer, the isocyanate group-containing unsaturated monomer, the amide group-containing unsaturated monomer, and the amino group-containing unsaturated monomer. And sulfonic acid group-containing unsaturated monomers.

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

In addition to the acrylic resin (A), the acrylic resin composition of the present invention comprises an organic solvent (B) and an ethylenically unsaturated compound (C) containing one ethylenically unsaturated group (hereinafter referred to as “ethylene”). A unsaturated unsaturated compound (C) ”) as an essential component.
Such organic solvent (B) an ethylenically unsaturated compound (C), in order to exhibit the effect of the present invention relates to proper drying, for their flash point, the flash point of the organic solvent (B) a (° C.) B _{f . p} , the flash point (° C.) of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group, C _{f. p}
(1) C _{f. p.} Is B _f. higher than _p. , and (2) C _{f. p.} and B _f. It is necessary that the difference in _p .

For such condition (2), C _{f. p.} and B _f. The difference in _p. needs to be 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 120 ° C. or higher. C _{f. p.} and B _{f. If} the difference in _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, or the residual ratio of the organic solvent (B). As a result, the solvent remains in the pressure-sensitive adhesive coating film, and the pressure-sensitive adhesive performance tends to decrease. C _{f. p.} and B _f. The upper limit of the difference in _p .

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 also 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), when 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, the coating viscosity tends to be too low to make thick coating difficult, 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) containing one ethylenically unsaturated group used in the present invention satisfies the above-mentioned conditions (1) and (2) regarding the flash point, and the alkyl group has 10 carbon atoms. In order to improve the drying property of the organic solvent (B), it is necessary to contain the above (meth) acrylic acid alkyl ester compound (C1) in an amount of 50% by weight or more. When drying the film, a material that is less likely to volatilize than the organic solvent (B) and stays in the pressure-sensitive adhesive layer is 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 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. .
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), it is necessary to contain 50% by weight or more of a (meth) acrylic acid alkyl ester compound (C1) having an alkyl group having 10 or more carbon atoms, Contains an ethylenically unsaturated compound with a flash point (flash point of 100 ° C. or higher), for example, a (meth) acrylic ester compound (C2) containing one ethylenically unsaturated group other than (C1) or a nitrogen atom It is preferable to use the obtained ethylenically unsaturated compound (C3) in that the organic solvent (B) can be efficiently dried at a wide range of drying temperatures.

  The content ratio of the alkyl group (meth) acrylic acid alkyl ester compound (C1) having 10 or more carbon atoms of the alkyl group based on the whole ethylenically unsaturated compound (C) needs to be 50% by weight or more. , Preferably 50 to 100% by weight, particularly preferably 60 to 95% by weight, still more preferably 70 to 90% by weight. When the content ratio of (C1) is too small, the compatibility and the step following ability are deteriorated, which is not preferable.

  As the (meth) acrylic acid alkyl ester compound (C1) having 10 or more carbon atoms in the alkyl group, the alkyl group preferably has 11 or more carbon atoms, particularly preferably 12 or more, more preferably 13 or more, Preferably, it is 14 or more. Specifically, for example, decane (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, isotridecyl (meth) acrylate, isomyristyl (meth) acrylate , N-stearyl (meth) acrylate, isostearyl (meth) acrylate, 2-decyltetradecanyl (meth) acrylate, and the like. These can be used alone or in combination of two or more. If the alkyl group has too few carbon atoms, depending on the drying conditions, the drying efficiency may deteriorate and the (meth) acrylate compound may be scattered. The upper limit of the carbon number of the alkyl group is usually 30, and preferably 24.

Among these, an acrylate compound is preferable from the viewpoint of excellent reactivity with ultraviolet rays, and a (meth) acrylic acid alkyl ester compound having a branched structure is preferable from the viewpoint of excellent step followability and adjustment of adhesive strength.
Specifically, isostearyl acrylate, isomyristyl acrylate, and the like are preferable, and isostearyl acrylate is particularly preferable.

The specific flash point of the alkyl group (meth) acrylic acid alkyl ester compound (C1) having 10 or more carbon atoms in the alkyl group is as follows (the flash point is described in parentheses).
・ 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.)

  As the (meth) acrylic acid ester compound (C2) having one ethylenically unsaturated group other than (C1) (excluding (C3) described later), an alicyclic (meth) acrylate (C2- 1), aromatic (meth) acrylate (C2-2), and oxyalkylene structure-modified compound (C2-4) of these (meth) acrylates.

  Examples of the alicyclic (meth) acrylate (C2-1) include isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and the like.

  Examples of the aromatic (meth) acrylate (C2-2) include benzyl (meth) acrylate, biphenyl (meth) acrylate, naphthalene (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and 3-chloro. -2-hydroxypropyl (meth) acrylate and the like.

  Moreover, as long chain aliphatic (meth) acrylate, alicyclic (meth) acrylate, and oxyalkylene structure modifying compound (C2-3) of aromatic (meth) acrylate, oxy of long chain aliphatic (meth) acrylate Examples of the alkylene structure modifying compound (C2-3a) include 2-ethylhexyl diethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, and alkylene glycol mono Examples include alkyl ester (meth) acrylates, alkylene glycol mono (meth) acrylates, and oxyalkylene structure-modified compounds (C2-3b) of alicyclic (meth) acrylates such as t-butyl Examples include cyclohexylcyclohexyloxyethyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, and the like. Examples of the alkylene (alkyl) structure-modified compound (C2-3c) include phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, phenoxytriethylene glycol (meth) acrylate, phenoxytetraglycol (meth) acrylate, and biphenyloxyethyl. Acrylate, nonylphenol ethylene oxide modification (repeat 4) (meth) acrylate, nonylphenol ethylene oxide modification (repeat 8) ( Data) acrylate, and the like.

The specific flash points of the exemplified compounds are as follows (the flash points are indicated in parentheses).
Alicyclic (meth) acrylate (C2-1); isobornyl acrylate (113 ° C.), dicyclopentanyl acrylate (132 ° C.), dicyclopentenyl acrylate (131 ° C.)
Aromatic (meth) acrylate (C2-2): 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.) Oxyalkylene structure-modified compound of alicyclic (meth) acrylate (C2-3b); dicyclopentenyloxyethyl acrylate (166 ° C.)
Aromatic (meth) acrylate oxyalkylene (alkyl) structure-modified compound (C2-3c); phenoxyethyl acrylate (141 ° C.), phenyldiethylene glycol acrylate (173 ° C.), nonylphenol ethylene oxide modified (repeated 4) acrylate (223 ° C.) ), Nonylphenol ethylene oxide modified (repeat 8) acrylate (304 ° C)

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

  The nitrogen-containing ethylenically unsaturated compound (C3) can be used to improve the adhesive strength of the adhesive, such as N-acryloyloxyethyl hexahydrophthalimide (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. .

  In addition, it is preferable that an ethylenically unsaturated compound (C) does not contain an aromatic ring from the point that coloring does not occur easily.

Moreover, an ethylenically unsaturated compound (C) exists as a polymer in an adhesive layer by hardening with an active energy ray and / or a heat so that it may mention later. Therefore, it is preferable to select the ethylenically unsaturated compound (C) so that the glass transition temperature (Tg) when the homopolymer of the ethylenically unsaturated compound (C) is −100 to 80 ° C.
The glass transition temperature is particularly preferably −80 to 20 ° C., more preferably −70 to 0 ° C., particularly preferably −60 to −10 ° C. If the glass transition temperature is too high, the step following ability is lowered. If it is too low, the cohesive force tends to decrease.
The glass transition temperature is calculated from the Fox equation described above.

The content ratio (weight ratio) of the acrylic resin (A) and the ethylenically unsaturated compound (C) needs to be (A) :( C) = 10: 90 to 90:10, preferably ( A) :( C) = 20: 80 to 70:30, particularly preferably (A) :( C) = 25: 75 to 65:35, particularly preferably (A) :( C) = 30: 70-55: 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 effects of the present invention tend not to be exerted sufficiently. Too much thick coating tends to be difficult.

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 total components (A) to (C). %, 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 (C) is too low, thick coating becomes difficult and a thick 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 40% by weight, preferably 8 to 30% by weight, and particularly preferably 10 to 20% 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 of the organic solvent (B) with respect to the entire acrylic resin composition is usually 10 to 90% by weight, preferably 15 to 50% by weight, and particularly preferably 20 to 35% 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 8 to 60% 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 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.

  Thus, an acrylic resin composition containing the acrylic resin (A), the organic solvent (B), and the ethylenically unsaturated compound (C) of the present invention is obtained. When the content ratio (weight ratio) of the system resin (A) and the ethylenically unsaturated compound (C) is within the above range, it is excellent in drying suitability and enables coating with thick coating.

  In the present invention, the acrylic resin composition containing the acrylic resin (A), the organic solvent (B), and the ethylenically unsaturated compound (C) is applied and dried to obtain the organic solvent (B). After volatilization, it can be made into an acrylic pressure-sensitive adhesive by curing and crosslinking (however, the acrylic resin composition at the time of curing and crosslinking contains some organic solvent (B) remaining in the drying step) May be.)

  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 the above [α] active energy ray and / or heat curing is performed, the acrylic resin composition further contains an ethylenically unsaturated compound (D) (hereinafter referred to as two or more ethylenically unsaturated groups). It may be abbreviated as “polyfunctional unsaturated compound (D)”) in that the cohesive force of the entire pressure-sensitive adhesive layer can be adjusted, and further contains a polymerization initiator (E). 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) and the polyfunctional unsaturated compound (D) are polymerized (polymerized) with 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 (F). In addition, when using a crosslinking agent (F), it is preferable that acrylic resin (A) has a functional group, and this functional group and a crosslinking agent react, and crosslinking (curing) is performed.

  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 preferable to add an unsaturated group to the functional group of the acrylic resin (A) in advance.

  As the polyfunctional unsaturated compound (D), 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 (D) is desirably 0.01 to 100 parts by weight, preferably 0.5 to 10 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). More preferably, it is 1 to 5 parts by weight. When the content of the polyfunctional unsaturated compound (D) is too large, the cohesive force is excessively increased, so that the adhesive performance tends to be inferior. When the content is too small, the holding power tends to be insufficient.

  In addition, the content of the polyfunctional unsaturated compound (D) is desirably 0.01 to 99 parts by weight, preferably 0.1 to 100 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated compound (C). 10 parts by weight, more preferably 0.5 to 5 parts by weight. If the content of the polyfunctional unsaturated compound (D) 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 be insufficient, resulting in durability. It tends to be inferior.

  As the polymerization initiator (E), for example, various polymerization initiators such as a photopolymerization initiator (e1) and a thermal polymerization initiator (e2) can be used. It is preferable to use e1) in that it can be cured by irradiation with active energy rays such as ultraviolet rays for a very short time.

  When the photopolymerization initiator (e1) is used, the acrylic resin composition is cured by irradiation with active energy rays. When the thermal polymerization initiator (e2) 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 (e1) 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, these photoinitiators (e1) may be used individually by 1 type, 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 (e2) 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 ) azo initiators such as propionitrile]; and the like can be mentioned up. 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 (E), when using the said ethylenically unsaturated compound (C) 100 weight part (when using a polyfunctional unsaturated compound (D), (C) and (D) 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 (E) 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 (e1).

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 (e2) as said polymerization initiator (E), a polymerization reaction is started and advanced by heating. The treatment temperature and treatment time at the time of curing by heating vary depending on the type of the thermal polymerization initiator (e2) to be 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 (F) 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 (F) may be used independently and may use 2 or more types together.

  Usually, the content of the crosslinking agent (F) 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 (F) 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 the 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, a base sheet, a release sheet, or an optical member. Specifically, 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 be used as

  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.

  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 obtained, for example, by 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 on the side without the mold sheet, performing treatment with at least one of active energy ray irradiation 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.

  Such optical members include transparent electrode films such as ITO conductive films such as ITO electrode films and polythiophenes, 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 strength is obtained, and an ITO (indium tin oxide) 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, with respect to the drying conditions in the drying step, the drying temperature 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 volatilize and remove the organic solvent (B), and the pressure-sensitive adhesive without volatilizing 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. In the following, it is more preferable that the pressure-sensitive adhesive composition layer can be efficiently formed by 1% by weight or less and the residual ratio of the ethylenically unsaturated compound (C) being 50% by weight or more, preferably 75% by weight or more. preferable.

  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 an aging treatment is preferably performed particularly when the crosslinking agent (F) is used in the acrylic resin composition. As conditions for such an 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 30 to 100%, particularly 50 to 90% in terms of durability and adhesive strength. Is preferable, and 60 to 80% is particularly preferable. If the gel fraction is too low, durability tends to be insufficient due to insufficient cohesive force. On the other hand, if the gel fraction is too high, the adhesive force tends to decrease due to an increase in cohesive force.

  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, since it contains a specific proportion of an ethylenically unsaturated monomer that does not easily volatilize together with an organic solvent that easily volatilizes under general drying conditions, 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 150 μm or more. Is usually 2000 μm.

  In addition, the film thickness in this invention uses Mitutoyo "ID-C112B", and subtracts the measured value of the thickness of structural members other than an adhesive layer from the measured value of the adhesive layer containing laminated body whole. This is the calculated value.

  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, 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 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 adhesive layer of the pressure-sensitive adhesive sheet, the double-sided pressure-sensitive adhesive sheet and the optical member with the pressure-sensitive adhesive layer of the present invention 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 was measured in accordance with JIS K7105, and the measurement was performed under transmission conditions using a color difference meter (Σ90: manufactured by Nippon Denshoku Industries Co., Ltd.).

  In the present invention, the haze, total light transmittance, and color difference b value are measured by using only an adhesive layer with alkali-free glass (total light transmittance = 93%, haze = 0.06, b value = 0.16). ) And measured by sticking.

  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))] (See Table 1)

[Acrylic resin (A-1)]
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 70 parts of 2-ethylhexyl acrylate (a1), 30 parts of 2-hydroxyethyl acrylate (a2) and 80 parts of ethyl acetate 1 part of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and after reaction for 3 hours at the reflux temperature of ethyl acetate, azobisisobutyronitrile (AIBN) 0.1 was added. Part and 20 parts of ethyl acetate were added, reacted for another 4 hours, diluted with ethyl acetate, and the acrylic resin (A-1) solution (weight average molecular weight 750,000, dispersity 3.8, glass transition temperature -56 ° C. , Solid content 50%, viscosity 15,000 mPa · s (25 ° C.)).

[Acrylic resin (A-2)]
To 100 parts (resin content) of the resulting acrylic resin (A-1) solution, 0.1 part of dibutylhydroxytoluene and 0.1 part of 2-methacryloyloxyethyl isocyanate were charged and reacted at 50 ° C. for 30 hours. Active energy ray-reactive acrylic resin (A-2) solution in which 0.24 mol% of ethylenically unsaturated group is added to the side chain with respect to hydroxyethyl acrylate (resin content 50%, viscosity 15000 mPa · s (25 ° C.) )

[Acrylic resin (A-3)]
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 59 parts of n-butyl acrylate (a3), 40 parts of methyl acrylate (a3), 2-hydroxyethyl acrylate ( a2) 1 part of ethyl acetate and 120 parts of ethyl acetate were charged. After heating and refluxing were started, 0.1 part of azobisisobutyronitrile (AIBN) was added as a polymerization initiator and reacted at the reflux temperature of ethyl acetate for 3 hours. Add 0.1 part of ronitrile (AIBN) and 20 parts of ethyl acetate, react for another 4 hours, dilute with ethyl acetate, and prepare acrylic resin (A-3) solution (weight average molecular weight 550,000, dispersity 4. 3, glass transition temperature -34 degreeC, solid content 38%, viscosity 8000 mPa * s (25 degreeC)) was obtained.

[Acrylic resin (A-4)]
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 99 parts of n-butyl acrylate (a3), 1 part of 2-hydroxyethyl acrylate (a2) and 100 of ethyl acetate 1 part was added, 0.1 parts of azobisisobutyronitrile (AIBN) was added as a polymerization initiator after heating and refluxing, and after reacting at the reflux temperature of ethyl acetate for 3 hours, azobisisobutyronitrile (AIBN) 0. 1 part and 20 parts of ethyl acetate were added, and the mixture was further reacted for 4 hours, diluted with ethyl acetate, and an acrylic resin solution (weight average molecular weight 600,000, dispersity 4.9, glass transition temperature -54 ° C., solid content 38 %, Viscosity 5000 mPa · s (25 ° C.)).
The acrylic resin solution obtained above was applied to a release sheet so that the thickness after drying was 10 to 20 μm, dried at 100 ° C. for 5 minutes, the remaining acrylic polymer was recovered, and no solvent was used. Acrylic resin (A-4).

[Organic solvent (B)]
The following were prepared as the organic solvent (B).
B-1: ethyl acetate (flash point: -3 ° C)
B-2: Methyl acetate cellosolve (flash point: 51 ° C.)

※表中 ―― は配合しなかったことを表す。
※１ アクリル系樹脂（Ａ−２）はアクリル系樹脂（Ａ−１）にエチレン性不飽和基を導入したものである。
（注）２ＥＨＡ：２−エチルヘキシルアクリレート
ＨＥＡ：２−ヒドロキシエチルアクリレート
ＢＡ：ｎ−ブチルアクリレート
ＭＡ：メチルアクリレート

* In the table, ―― indicates that it was not blended.
* 1 Acrylic resin (A-2) is obtained by introducing an ethylenically unsaturated group into acrylic resin (A-1).
(Note) 2EHA: 2-ethylhexyl acrylate HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate MA: methyl acrylate

[Ethylenically unsaturated compound (C)]
(C-1): Isostearyl acrylate (“ISTA” manufactured by Osaka Organic Chemical Industry); flash point 154 ° C .; molecular weight 324: glass transition temperature of homopolymer: −18 ° C.
(C-2): tridecyl acrylate (“SR489D” manufactured by Sartomer); flash point 154 ° C .; molecular weight 254: glass transition temperature of homopolymer: −54 ° C.
(C-3): Isomyristyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., “Light acrylate IM-A”); flash point 129 ° C .; molecular weight 282: glass transition temperature of homopolymer: −55 ° C.
(C′-1): 2-ethylhexyl acrylate; flash point 86 ° C .; molecular weight 184: glass transition temperature of homopolymer: −70 ° C.
(C′-2): Phenoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., “Light acrylate P2HA”); Flash point 165 ° C .; Molecular weight 236: Glass transition temperature of homopolymer: −8 ° C.
(C′-3): butoxymethylacrylamide (“NBM-3” manufactured by Kasano Kosan); flash point 112 ° C .; molecular weight 157: glass transition temperature of homopolymer: 0 ° C.
(C′-4): cyclopentenyloxyethyl acrylate (“FA-512AS” manufactured by Hitachi Chemical Co., Ltd.); flash point 132 ° C .; molecular weight 248: glass transition temperature of homopolymer: 10 ° C.
(C'-5): butyl acrylate; flash point 40 ° C; molecular weight 128: glass transition temperature of homopolymer: -54 ° C

[Compound (D) containing two or more ethylenically unsaturated groups]
D-1: Trimethylolpropane triacrylate

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

[Crosslinking agent (F)]
F-1: 55% ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethane Co., Ltd., “Coronate L-55E”)

[Examples 1-5, Comparative Examples 1-5, 8, 9]
An acrylic resin composition solution was prepared by blending the blended components prepared and prepared as described above in the ratios shown in Tables 2 and 3 below.

  Then, the acrylic resin composition solution obtained above is applied to a polyester release sheet so that the thickness after drying is 200 μm, and dried at 100 ° C. for 5 minutes to form an adhesive composition layer. I let you. The coating suitability when forming the pressure-sensitive adhesive composition layer was evaluated as follows.

[Comparative Example 6]
With the composition shown in Table 3, a pressure-sensitive adhesive composition layer was formed in the same manner as in Example 1 except that drying was not performed, and coating suitability was evaluated.

[Comparative Example 7]
With the composition shown in Table 3, a pressure-sensitive adhesive composition layer was formed in the same manner as in Example 1 except that the drying temperature was changed to 70 ° C. for 3 minutes, and coating suitability was evaluated.

  And the acrylic resin composition solution obtained above was apply | coated to the polyester-type release sheet so that the thickness after coating might be set to 200 micrometers, and the adhesive composition layer was formed. The coating suitability when forming the pressure-sensitive adhesive composition layer was evaluated as follows.

[Coating is appropriate]
The appearance of the pressure-sensitive adhesive composition layer was visually evaluated when the pressure-sensitive adhesive composition layer was formed under the above drying conditions.
○: A clean pressure-sensitive adhesive composition layer was obtained. Δ: Air bubbles were confirmed, or irregularities were confirmed on the coating film.
X: It is confirmed that a large amount of air bubbles are bitten, or the coating film is very uneven.

In Examples 1 to 5 and Comparative Examples 1 to 4 and 7 to 9, the obtained pressure-sensitive adhesive composition layer was sandwiched between polyester release sheets, and the peak illuminance was 150 mW / cm ^{2 with} a high-pressure mercury UV irradiation device. integrated exposure amount: 1000 mJ / cm ² performs ultraviolet irradiation in (500mJ / cm ² × ² pass), 23 ℃ × 65% R . H. A baseless double-sided PSA sheet was obtained by aging under the conditions of 10 days.

  In Comparative Example 5, the obtained pressure-sensitive adhesive composition layer was sandwiched between polyester release sheets, and 23 ° C. × 50% R.D. H. A baseless double-sided PSA sheet was obtained by aging under the conditions of 10 days.

In Comparative Example 6, the obtained pressure-sensitive adhesive composition layer was sandwiched between polyester release sheets, and ultraviolet irradiation was performed with a high-pressure mercury UV irradiation device at a peak illuminance of 150 mW / cm ² and an integrated exposure amount of 2400 mJ / cm ^2. (800 mJ / cm ² × 3 pass), 23 ° C. × 50% R.D. H. A baseless double-sided PSA sheet was obtained by aging under the conditions of 10 days.

  Using the substrate-less double-sided pressure-sensitive adhesive sheet obtained above, a PET film with a pressure-sensitive adhesive layer was prepared as follows, and the gel fraction, the adhesive strength, and the holding strength were measured and evaluated according to the following methods. These results are shown in Tables 2 and 3 below.

[Preparation of PET film with adhesive layer]
The release sheet on one surface was peeled off from the pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive sheet and pressed against a 100 μm PET film to obtain a PET film with a pressure-sensitive adhesive layer.

[Gel fraction]
After cutting the PET film with the pressure-sensitive adhesive layer to 40 mm × 40 mm, the release sheet is peeled off, and the pressure-sensitive adhesive layer side is bonded to a 50 mm × 100 mm SUS mesh sheet (200 mesh), and then the length of the SUS mesh sheet is increased. The sample was wrapped from the center with respect to the direction, and the sample was wrapped. Then, the gel fraction (%) was measured by the change in weight when immersed in a sealed container containing 250 g of toluene.

[Adhesive force]
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.

[Retention force]
The PET film with the pressure-sensitive adhesive layer is cut to 25 mm × 25 mm, the release sheet is peeled off, the pressure-sensitive adhesive layer side is attached to a polished SUS plate, and a load of 1 kg is applied at 80 ° C. Then, the deviation was evaluated according to the measuring method of the holding power of JIS Z 0237. The evaluation criteria are as follows.
(Evaluation)
○ ・ ・ ・ No deviation occurs after 1440 minutes △ ・ ・ ・ Deformation occurs after 1440 minutes × ・ ・ ・ Drops by 1440 minutes

  Moreover, about Examples 1-5 and Comparative Examples 1-4, the level | step difference followability, transparency, and heat-and-moisture resistance were evaluated as follows.

[Step following capability]
On the soda glass, a 50 μm PET film was fixed with a cellophane tape to produce a stepped glass. The above-mentioned PET film with an adhesive layer is pressure-applied to the glass with a step in two reciprocations of a 2 kg rubber roller in an atmosphere of 23 ° C. and a relative humidity of 50%, and applied with an autoclave at 50 ° C. and 0.5 MPa × 20 minutes. Pressure heat treatment, 23 ° C. × 50% R.D. H. After being allowed to stand for 30 minutes under the above conditions, the ability to follow a step was visually evaluated. The evaluation results are as follows.
(Evaluation)
◎ ・ ・ ・ No air can be seen in the step.
○ ... Air can hardly be found in the step.
Δ: A slight amount of air can be seen in the step.
×: Air is entrained in the step and the pressure-sensitive adhesive layer is largely floating.

[optical properties]
The substrate-less double-sided pressure-sensitive adhesive sheet is cut to a size of 25 mm × 25 mm, one release sheet is peeled off, and the pressure-sensitive adhesive layer side is bonded to a slide glass (Corning, Corning 1737), followed by autoclave treatment (50 ° C., 0.5 MPa, 20 minutes), the other release sheet is peeled off to prepare a test piece having the configuration of “slide glass / adhesive layer”, and the haze value and color difference b are as follows. The value was measured.

<Haze value: Transparency>
For the haze value, diffuse transmittance and total light transmittance are measured using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), and the obtained diffuse transmittance and total light transmittance value are substituted into the following formula. The haze was calculated. This machine complies with JIS K7361-1.
Haze value (%) = (diffuse transmittance / total light transmittance) × 100
(Evaluation)
○: Haze is less than 0.5 Δ: Haze is 0.5 or more and less than 1 ×: Haze is 1 or more

<Color difference b value; Colorability>
The color difference b value of the test piece having the above-mentioned “slide glass / 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.).
(Evaluation)
B: Color difference b value is 0.5 or less Δ: Color difference b value is less than 0.5 to 1 x Color difference b value is 1 or more

  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.

※ 表中（Ａ）〜（Ｆ）内の（ ）内の数字は、重量部を表す。 [Moisture and heat resistance]
The PET film with an adhesive layer is cut to 25 mm × 25 mm, the release sheet is peeled off, and the adhesive layer side is bonded to a slide glass (Corning, Corning 1737), followed by autoclaving (50 ° C. , 0.5 MPa, 20 minutes), and a test piece having a configuration of “slide glass / adhesive layer / PET film” was produced.
Using the test piece, a moisture and heat resistance test for 120 hours was performed in an atmosphere of 80 ° C. and 90% RH, and the haze value after the moisture and heat resistance test was measured and evaluated according to the following criteria.
The haze value is determined by measuring the diffuse transmittance and the total light transmittance using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). Substituted to calculate haze. This machine complies with JIS K7361-1.
Haze value (%) = (diffuse transmittance / total light transmittance) × 100
(Evaluation)
○ ・ ・ ・ Haze value after moist heat resistance test is less than 2 △ ・ ・ ・ Haze value immediately after moist heat resistance test is 2 or more and less than 3 × ・ ・ ・ Haze value immediately after moist heat resistance test is 3 or more

* Numbers in parentheses in (A) to (F) in the table represent parts by weight.

※ 表中の（ ）内の数字は重量部を表し、「−」は配合しなかったことを表す。

* Numbers in parentheses in the table represent parts by weight, and “-” represents that no compound was added.

Ethylenically unsaturated compound containing one ethylenically unsaturated group containing 50 wt% or more of acrylic resin (A) and alkyl (meth) acrylic acid alkyl ester compound (C1) having 10 or more carbon atoms in the alkyl group In the acrylic resin compositions of Examples 1 to 6 including (C), a clean pressure-sensitive adhesive layer was obtained even when a thick film pressure-sensitive adhesive composition layer was formed so that the thickness after drying was 200 μm. It is excellent in coating suitability. Furthermore, it exhibits good followability even with a high step of 50 μm, and the resulting pressure-sensitive adhesive layer has a low haze value and is optically transparent, has a low color difference b value, and has a yellowish color. It can be seen that the pressure-sensitive adhesive layer is weak and less colored.
Moreover, it turns out that adhesive force can be controlled by selecting the kind of ethylenically unsaturated compound (C), or the outstanding holding force and level | step difference tracking performance can be exhibited.

  On the other hand, as the ethylenically unsaturated compound (C), any unsaturated compound is not included in Comparative Examples 1 to 4, which does not include a (meth) acrylic acid alkyl ester compound (C1) having 10 or more carbon atoms in the alkyl group. In, the increase in the elastic modulus of the coating film is inferior in the step following ability, and in particular, as the ethylenically unsaturated compound, a (meth) acrylic acid alkyl ester compound having an alkyl group with a carbon number smaller than 10 is used. The resin composition of Comparative Example 1 used was inferior in drying suitability and low in holding power because the compound was scattered during drying.

On the other hand, in the pressure-sensitive adhesive composition layer of Comparative Example 5 obtained using an acrylic resin composition not containing an ethylenically unsaturated compound (C), a large amount of air bubbles was confirmed and the dryness was inferior. Met.
As a result, it can be seen that this pressure-sensitive adhesive layer is not practical for optical applications due to the bubbles generated in the pressure-sensitive adhesive layer, although the pressure-sensitive adhesive layer is excellent.

  In Comparative Example 6 using a solventless acrylic resin, since the organic solvent (B) is not contained, the coating viscosity becomes very high, and as a result, a clean coating film cannot be obtained ( As a result, the unevenness of the coating film was large) and the unevenness of the film thickness was increased.

C of the ethylenically unsaturated compound (C) _{f. p.} And B of organic solvent (B) _f. Regarding Comparative Examples 7 to 9 in which the difference in _p. is less than 50 ° C., in Comparative Examples 8 and 9, the ethylenically unsaturated compound (C) is volatilized together with the organic solvent (B), and the pressure-sensitive adhesive composition during drying It turns out that the viscosity of a physical layer rises and the coating suitability at the time of thick coating coating worsens.
In Comparative Example 7, the drying temperature was low, and neither the organic solvent (B) nor the ethylenically unsaturated compound (C) was dried. Since the component (B) remained in the agent composition layer, the adhesive physical properties of the holding power deteriorated and could not be put to practical use.

  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) and ethylenically unsaturated compound (C) containing one ethylenically unsaturated group
The content ratio (weight ratio) of the acrylic resin (A) and the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is (A) :( C) = 10: 90- 90:10 acrylic resin composition,
[I] The flash point (° C.) of the organic solvent (B) is set to B _{f. p.} The flash point (° C.) of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group is expressed as C _{f. p.} C _{f. p.} Is B _f. higher than _p. and C _{f. p.} and B _{f. p.} difference is 50 ° C. or more,
[II] The ethylenically unsaturated compound (C) containing one ethylenically unsaturated group contains 50% by weight or more of a (meth) acrylic acid alkyl ester compound (C1) having 10 or more carbon atoms in the alkyl group. An acrylic resin composition characterized by comprising:   The acrylic resin composition according to claim 1, wherein the homopolymer of the ethylenically unsaturated compound (C) containing one ethylenically unsaturated group has a glass transition temperature of -80 to 20 ° C.   An acrylic pressure-sensitive adhesive obtained from the acrylic resin composition according to claim 1.   A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive according to claim 3.   A double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive according to claim 3.   A transparent electrode pressure-sensitive adhesive comprising the acrylic pressure-sensitive adhesive according to claim 3.   A touch panel comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive for transparent electrodes according to claim 6.   An image display device comprising an adhesive layer containing the acrylic adhesive according to claim 3.   A pressure-sensitive adhesive characterized in that the acrylic resin composition according to claim 1 or 2 is applied to a substrate sheet, a release sheet, or an optical member, dried, and polymerized by active energy rays and / or heat. A method for producing a layer-containing laminate. The residual ratio of the acrylic resin (A) in the pressure-sensitive adhesive layer after drying is 90% by weight or more, the residual ratio of the organic solvent (B) is 5% by weight or less, and contains one ethylenically unsaturated group. The method for producing a pressure-sensitive adhesive layer-containing laminate according to claim 9, wherein the residual ratio of the saturated compound (C) is 50% by weight or more.