JP5808177B2 - Adhesive for optical member, optical part with adhesive layer, and image display device - Google Patents

Description

  The present invention relates to an adhesive for optical members, an optical member with an adhesive layer obtained by using the adhesive, and an image display device. Specifically, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP. An optical laminate in which a polarizing film is coated with a protective film such as a cellulose triacetate film, in particular, such as an optical film (polarizing film, retardation film, optical compensation film, brightness enhancement film, etc.) that is suitably used. TECHNICAL FIELD The present invention relates to an optical member pressure-sensitive adhesive used for bonding a body and a glass substrate of a liquid crystal cell, and an optical member with a pressure-sensitive adhesive layer in which a pressure-sensitive adhesive layer made of this optical member pressure-sensitive adhesive is formed, particularly a polarizing plate with a pressure-sensitive adhesive layer. Is.

  Conventionally, a liquid crystal in which a polarizing plate in which both surfaces of a polyvinyl alcohol film and the like having a polarizing property are coated with a cellulose film, for example, a cellulose triacetate film, is sandwiched between two glass plates. Lamination on the surface of the cell to form a liquid crystal display panel is performed by laminating the pressure-sensitive adhesive layer provided on the surface of the polarizing plate against the liquid crystal cell surface and pressing it. It is normal.

  Such a polarizing plate has a three-layer structure in which both surfaces of a polyvinyl alcohol-based polarizer are sandwiched between triacetyl cellulose-based protective films, but dimensional stability is poor due to the characteristics of these materials. Moreover, since the polyvinyl alcohol-type polarizer is shape | molded by extending | stretching, the dimensional change with time is easy to occur. If the internal stress generated by such a dimensional change cannot be absorbed and relaxed, the distribution of residual stress acting on the polarizing plate becomes non-uniform, and stress is concentrated particularly on the peripheral portion of the polarizing plate. As a result, color unevenness / light leakage phenomenon occurs in the liquid crystal display device such that the peripheral edge of the liquid crystal display device is brighter or darker than the center.

  Therefore, for various optical applications, especially adhesives for attaching polarizing plates, research has been conducted to find adhesives with excellent durability such as foaming and peeling, and excellent optical properties such as less light leakage. I have been.

For example, Patent Document 1 describes a pressure-sensitive adhesive containing a component having a weight average molecular weight of 1,000,000 or more and having a component of 100,000 or less of 15% or less. It is described that the durability is ensured by increasing the number.
In Patent Document 2, a polyfunctional ethylenically unsaturated monomer used in combination with an acrylic resin (substantially) having a weight average molecular weight of 1,500,000 is cross-linked by irradiation with active energy rays, and the storage elastic modulus is higher than usual. There is described a pressure-sensitive adhesive that is particularly excellent in durability and in good balance with optical characteristics when it is set to a high value.
As described above, the pressure-sensitive adhesive for optical members such as a polarizing plate has been developed to have high durability performance by increasing the weight average molecular weight of the acrylic resin. Along with this, increasing the draw ratio of the polarizer and improving the degree of polarization of the polarizing plate is required, and further enhancement of durability is required.

  On the other hand, in recent years, with the overwhelming widespread use of liquid crystal display devices such as liquid crystal televisions, personal computer monitors, and notebook computers, polarizing plates have only been produced in large quantities. It is also important to reduce the burden on the environment. For this reason, for example, when applying a pressure-sensitive adhesive composition to a polarizing plate, the line speed is increased or the drying temperature is lowered to increase the amount of energy efficiently. There is also a need to study production and to reduce the environmental load by reducing the organic solvent that is scattered during drying.

JP-A 64-66283 JP 2006-309114 A

  However, the technique disclosed in Patent Document 1 cannot achieve the currently required high level of durability performance, and the technique disclosed in Patent Document 2 shows a certain durability performance, but the adhesive is not used. The resin concentration at the time of coating was as low as about 15%. In other words, it contained a large amount of an organic solvent, and the load on the environment was large.

  Therefore, in the present invention, under such a background, when bonding an optical member such as a polarizing plate and a glass substrate, etc., the optical performance is excellent in durability and optical characteristics (light leakage resistance), and is excellent in coating suitability and drying suitability. It aims at provision of the adhesive for members.

  However, as a result of intensive studies in view of such circumstances, the present inventors have determined that an adhesive composition containing an acrylic resin (A) and a compound (B) containing one ethylenically unsaturated group is active energy. By irradiation and / or heating, the polymer of the ethylenically unsaturated compound (B) and the acrylic resin (A) can form an interpenetrating network structure, and the acrylic resin (A ), High durability performance is demonstrated without increasing the molecular weight. Furthermore, since the molecular weight of the acrylic resin (A) is low and the resin viscosity is low, the amount of dilution solvent used to make the coating suitable viscosity Thus, the present invention has been completed.

That is, the gist of the present invention, the acrylic resin (A), the d ethylenic unsaturated group one containing compound (B), and an ethylenically unsaturated compound containing two or more ethylenically unsaturated groups (C ) -Containing pressure-sensitive adhesive composition [I] is a pressure-sensitive adhesive for optical members that is cured by active energy rays and / or heat, and the acrylic resin (A) has a weight average molecular weight of 100,000 to 1,000,000. And a compound (B) containing one ethylenically unsaturated group has a glass transition temperature of −100 to 60 ° C. and a compound containing one ethylenically unsaturated group per 100 parts by weight of the acrylic resin (A). (B) a content of 10 to 100 parts by weight of a compound containing one d ethylenic unsaturated group (B) an ethylenically unsaturated compound containing two or more ethylenically unsaturated groups (C) Ethylene for the total amount of It relates the adhesive for optical members content being greater than 50 mol% of compounds containing one unsaturated group (B).
Furthermore, it is related with the optical member with an adhesive layer containing the adhesive layer containing the said adhesive for optical members, and the laminated structure of an optical member.

  The pressure-sensitive adhesive for optical members of the present invention is excellent in handleability (tack) and optical properties (haze), and even under high-temperature and high-humidity environments, optical laminates, especially optical members such as polarizing plates and glass A liquid crystal display device that is excellent in adhesiveness with the substrate, does not cause foaming or peeling between the pressure-sensitive adhesive layer and the glass substrate, and does not cause color unevenness or light leakage can be obtained.

  The acrylic resin (A) used in the present invention contains a (meth) acrylic acid alkyl ester monomer (a1) as a main component, and preferably includes an aromatic ring-containing monomer (a2) and a functional group-containing monomer (a3). The copolymerization component is copolymerized, and another copolymerizable monomer (a4) can be used as the copolymerization component.

  As such a (meth) acrylic acid alkyl ester monomer (a1), the alkyl group usually has 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, specifically, 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) Examples include acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, and stearyl (meth) acrylate. These can be used alone or in combination of two or more.

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

  The content in the case of copolymerizing the (meth) acrylic acid alkyl ester monomer (a1) is preferably 30 to 100% by weight, particularly preferably 50 to 90% by weight, more preferably, based on the entire copolymerization component. Preferably it is 60 to 80% by weight, and if the content of the (meth) acrylic acid ester monomer (a1) is too small, the adhesive performance tends to be lowered.

  Examples of the aromatic ring-containing monomer (a2) include phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate. Monomers containing one aromatic ring such as styrene, α-methylstyrene; monomers containing two or more aromatic rings such as biphenyl acrylate, biphenyloxyethyl (meth) acrylate and biphenyloxyalkyl (meth) acrylate It is done. These can be used alone or in combination of two or more.

  Among these aromatic ring-containing monomers (a2), a (meth) acrylate monomer is preferable because the polymerization reaction is likely to proceed, and further, benzyl (meth) acrylate and phenoxyethyl (meta ) Acrylate and phenyldiethylene glycol (meth) acrylate are preferably used.

  The content of the aromatic ring-containing monomer (a2) is preferably 0 to 70% by weight, particularly preferably 5 to 40% by weight, more preferably 10 to 30% by weight, based on the entire copolymer component. When there is too much content of an aromatic ring containing monomer (a2), there exists a tendency for an adhesive characteristic to fall.

  Examples of the functional group-containing monomer (a3) include monomers containing a functional group that can become a crosslinking point by reacting with a crosslinking agent (E) described later. Examples include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and an amino group-containing monomer. Monomers, acetoacetyl group-containing monomers, isocyanate group-containing monomers, glycidyl group-containing monomers and the like can be mentioned, and among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used in terms of efficient crosslinking reaction.

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

  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 a content of di (meth) acrylate as an impurity is 0.5% or less. Further, it is preferable to use a material of 0.2% or less, particularly 0.1% or less. Specifically, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferable.

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

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

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

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

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, allyl glycidyl (meth) acrylate, and the like.
These functional group-containing monomers (a3) may be used alone or in combination of two or more.

  The content of the functional group-containing monomer (a3) is preferably 0 to 30% by weight, particularly preferably 0.5 to 20% by weight, more preferably 3 to 15% by weight, based on the entire copolymer component. Particularly preferably, the content is 6 to 10% by weight. If the content of the functional group-containing monomer (a3) is too large, the viscosity tends to increase or the stability of the resin tends to decrease.

  Examples of other copolymerizable monomer (a4) include, for example, alicyclic (meth) acrylic acid ester monomers such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2 -Ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate Alkoxy groups such as ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate and oxy Monomers containing a ruxylene group; alkoxyalkyls such as methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxymethyl (meth) acrylamide, n-butoxymethyl (meth) acrylamide, isobutoxymethyl (meth) acrylamide, etc. ) Acrylamide monomer; (Meth) acryloyl morpholine, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth) acrylamide N-methylol (meth) acrylamide, (meth) acrylamide monomers such as dimethylaminoethyl (meth) acrylamide Acrylonitrile, methacrylonitrile, vinyl acetate and the like.

  Among these, alkoxyalkyl (meth) acrylamide monomers and (meth) acrylamide monomers are preferable because they can easily improve adhesion to the adherend, and acryloylmorpholine is particularly preferable.

  The content of the other copolymerizable monomer (a4) is preferably 0 to 60% by weight, particularly preferably 1 to 30% by weight, more preferably 2 to 15% by weight, based on the entire copolymerization component. If the content of the other copolymerizable monomer (a4) is too large, the effects of the present invention tend to be difficult to obtain.

  For the purpose of increasing the molecular weight, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate A compound having two or more ethylenically unsaturated groups such as divinylbenzene can also be used in combination.

  The acrylic resin (A) is produced by polymerizing the monomer components (a1) to (a4). Such polymerization can be carried out by a conventionally known method such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization or the like, and it is particularly preferable to perform polymerization using a solution polymerization method. For example, in an organic solvent, a polymerization monomer such as a (meth) acrylic acid alkyl ester monomer (a1), an aromatic ring-containing monomer (a2), a functional group-containing monomer (a3), other copolymerizable monomer (a4), A polymerization initiator is mixed or dropped, and polymerization is carried out in a reflux state or at 50 to 90 ° C. for 2 to 20 hours.

  Examples of the organic solvent used for the polymerization include aromatic hydrocarbons such as toluene and xylene, esters such as methyl acetate, ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, acetone, Examples include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  As the polymerization initiator used for such radical copolymerization, azo-based polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, which are usual radical polymerization initiators, benzoyl peroxide, lauroyl peroxide, Specific examples thereof include peroxide polymerization initiators such as -t-butyl peroxide and cumene hydroperoxide.

  In the present invention, the molecular weight of the acrylic resin (A) is important, and the weight average molecular weight needs to be 100,000 to 1,000,000, preferably 300,000 to 900,000, particularly preferably 400,000. ˜800,000, particularly preferably 500,000 to 700,000. When the weight average molecular weight is too small, the durability performance is lowered, and when it is too large, a large amount of a diluent solvent is required, which is not preferable in terms of coating property and cost.

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 10 or less, more preferably 7 or less, and particularly preferably 4 or less. . When the degree of dispersion is too high, the durability performance of the pressure-sensitive adhesive layer is lowered, and foaming or the like tends to occur. The lower limit of the degree of dispersion is usually 1.1 from the viewpoint of production limit.

  The glass transition temperature of the acrylic resin (A) is preferably −80 to 0 ° C., particularly preferably −60 to −10 ° C., further preferably −45 to −20 ° C., and particularly preferably −35 to 35 ° C. If it is −25 ° C. and the glass transition temperature is too high, the adhesive strength tends to increase too much, and if it is too low, the heat resistance tends to decrease.

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 a 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 particle size : 10 μm), and the number average molecular weight can be used in the same manner. 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 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)

  The acid value of the acrylic resin (A) is preferably 10 mgKOH / g or more from the viewpoint of imparting adhesion and improving durability, particularly preferably 20 to 300 mgKOH / g, more preferably 40 to 100 mgKOH / g. It is. If the acid value is too high, the adhesive strength tends to increase too much, and if it is too low, the durability tends to decrease.

  As the compound (B) containing one ethylenically unsaturated group used in the present invention (hereinafter sometimes referred to as “monofunctional unsaturated compound (B)”), the acrylic resin (A) is used. A known general monofunctional unsaturated compound such as a monomer component used as a copolymerization component may be used, and among them, a monofunctional unsaturated compound containing an aromatic ring is preferable.

  Examples of the functional group containing an ethylenically unsaturated group include a (meth) acryloyl group, a crotonoyl group, a vinyl group, and an allyl group. As the monofunctional unsaturated compound (B), Among the above functional groups in the structure, a compound containing a (meth) acryloyl group, that is, a mono (meth) acrylate-based compound, the reaction is likely to proceed when cured by active energy rays and / or heat. This is preferable.

  Specific examples of the monofunctional unsaturated compound containing the aromatic ring (hereinafter sometimes referred to as “aromatic monofunctional monomer”) include ether-based aromatic monofunctional monomers and ester-based aromatic compounds. Examples of the ether-based aromatic monofunctional monomer include, for example, phenol derivatives, catechol, resorcinol, hydroquinone, and other dihydroxybenzene derivatives. Examples of the ester-based aromatic monofunctional monomer include, for example, Examples thereof include benzoic acid derivatives and phthalic acid derivatives.

  In addition, the number of aromatic rings contained in the aromatic monofunctional monomer may be one or a plurality of aromatic rings, but one aromatic ring is included in terms of balancing the physical properties of the adhesive. A compound is preferable, and a compound containing two aromatic rings is preferable in that the refractive index and birefringence of the adhesive layer can be controlled efficiently.

For the ether-based aromatic monofunctional monomer, the phenol derivative is preferably a derivative having a structure in which the hydrogen atom of the hydroxyl group of phenol is replaced with a structural site containing a (meth) acryloyl group. Is preferably a derivative in which one or both hydrogen atoms of the two hydroxyl groups of resorcinol are replaced with a structural site containing a (meth) acryloyl group.
As the structural moiety containing such a (meth) acryloyl group, those represented by the following general formula (1) also containing an oxyalkylene structure are preferable.

(In the formula, R is a hydrogen atom or a methyl group, X is an alkylene group, and n is an integer of 1 or more.)

X in the above general formula (1) is an alkylene group, among which an alkylene group having 1 to 10 carbon atoms is preferable, and in particular, an alkylene group having 1 to 4 carbon atoms such as an ethylene group, a propylene group, or a tetramethylene group. Groups are preferred, especially ethylene groups.
When n is a polyoxyalkylene chain moiety having 2 or more, a homopolymer of the same oxyalkylene chain may be used, or different oxyalkylene chains may be copolymerized randomly or in a block form.
The alkylene group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group, an amino group, a sulfanyl group, an aryl group, and a heteroaryl group. Of these, a hydroxyl group is preferred.

  N in the general formula (1) is an integer of 1 or more, preferably 1 to 10, particularly preferably 1 to 2, and further preferably 2. If the value of n is too large, the heat and humidity resistance of the acrylic resin tends to decrease, and in order to control the refractive index and birefringence, shorter alkylene groups and oxyalkylene structures are preferable, so n is small. It is preferable.

  Specific examples of derivatives having a structure in which the hydrogen atom of the hydroxyl group of the phenol is replaced with a structural site containing a (meth) acryloyl group include, for example, phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, and phenyltriethylene. Phenyl polyethylene glycol (meth) acrylate having 2 to 8 (preferably 2 to 4) repeating ethylene glycol structures such as glycol (meth) acrylate, phenyltetraethylene glycol (meth) acrylate, and phenyloctaethylene glycol (meth) acrylate , Phenoxypropyl (meth) acrylate, phenyldipropylene glycol (meth) acrylate, phenyl polypropylene glycol (meth) acrylate, 2-hydroxy-3-phenoxy The number of repeating ethylene glycol structures such as cypropyl (meth) acrylate, ethoxylated phenylphenyl (meth) acrylate, nonylphenoxyethyl (meth) acrylate, and nonylphenyldiethylene glycol (meth) acrylate is 2 to 8 (preferably 2 to 4) Nonylphenyl polypropylene glycol having 2 to 8 (preferably 2 to 4) repeating units of propylene glycol structure such as nonylphenyl polyethylene glycol (meth) acrylate, nonylphenoxypropyl (meth) acrylate, nonylphenyldipropylene glycol (meth) acrylate, etc. (Meth) acrylate and the like can be mentioned, and as a commercial product, phenyl polyethylene glycol acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name “Biscoat # 193”), 2-hydride Xyl-3-phenoxypropyl acrylate (Osaka Organic Chemical Co., Ltd., trade name “Biscoat # 220”), phenyl diethylene glycol acrylate (Kyoeisha, trade name “Light acrylate P2HA”), phenyl triethylene glycol acrylate (Hitachi Chemical Co., Ltd., Product name “Phenoxytriethylene glycol acrylate”), Phenyltetraethylene glycol acrylate (manufactured by Hitachi Chemical Co., Ltd., product name “Phenoxytetraethylene glycol acrylate”), Nonylphenoxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., product name “Nonylphenoxyethyl acrylate” ”), Nonylphenyl diethylene glycol acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name“ nonylphenoxydiethylene glycol acrylate ”), nonylphenyl tetrae Ren glycol acrylate (trade name “nonylphenoxytetraethylene glycol acrylate” manufactured by Hitachi Chemical Co., Ltd.), nonylphenyl octaethylene glycol acrylate (trade name “nonylphenoxy octaethylene glycol acrylate” manufactured by Hitachi Chemical Co., Ltd.), nonylphenyl polypropylene glycol ( (Meth) acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “nonylphenoxypolypropylene glycol (meth) acrylate”), ethoxylated o-phenylphenyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A-LEN-10”), etc. Is mentioned.

Regarding the ester-based aromatic monofunctional monomer, the benzoic acid derivative is preferably a derivative having a structure in which the hydrogen atom of the carboxyl group of benzoic acid is replaced with a structural site containing a (meth) acryloyl group. The acid derivative is preferably a derivative having a structure in which one or both hydrogen atoms of two carboxyl groups of phthalic acid are replaced with a structural site containing a (meth) acryloyl group.
As the structural moiety containing such a (meth) acryloyl group, those represented by the general formula (1) described above are preferable.

  Specific examples of derivatives having a structure in which one or both hydrogen atoms of the two carboxyl groups of phthalic acid are replaced by a structural site containing a (meth) acryloyl group include 2-acryloyloxyethyl- 2-hydroxypropyl phthalate (trade name “Biscoat # 2311HP” manufactured by Osaka Organic Chemical Co., Ltd.), 2-acryloyloxyethyl hydrogen phthalate (trade name “Biscoat # 2000” manufactured by Osaka Organic Chemical Co., Ltd.), 2-acryloyloxypropyl hydrogen Examples include phthalate (trade name “Biscoat # 2100” manufactured by Osaka Organic Chemical Co., Ltd.), 2-methacryloyloxyethylphthalic acid (trade name “CB-1” manufactured by Shin-Nakamura Chemical Co., Ltd.), and the like.

  In the present invention, the monofunctional unsaturated compound (B) preferably has a flash point of 100 ° C. or higher, in that it does not volatilize during coating drying and remains in the pressure-sensitive adhesive layer. Preferably it is 120 degreeC or more, More preferably, it is 140 degreeC or more, Most preferably, it is 160 degreeC or more. If the flash point is too low, it tends to volatilize in the drying process, and the upper limit of the flash point is usually 350 ° C. The aromatic monofunctional monomer is also preferably within the flash point range.

  Here, butyl acrylate (flash point: 47 ° C.) and 2-ethylhexyl acrylate (flash point: 88 ° C.), which are general monofunctional ethylenically unsaturated compounds, are normal because of their high volatility. Under the drying conditions of the coating drying process, it will volatilize with the organic solvent, but when the flash point is 100 ° C. or higher, it is difficult to volatilize with the organic solvent under normal drying conditions. It is easy to stay inside.

In general, the volatility of a compound is generally determined from the boiling point or evaporation rate. However, unsaturated monomers (ethylenically unsaturated compounds) are polymerized when subjected to temperature at normal pressure and the boiling point is reduced. Since it may not be measured accurately, in the present invention, as an indicator of volatility,
It uses a flash point that correlates with the volatility of the unsaturated monomer.

  Examples of monofunctional unsaturated compounds having a flash point of 100 ° C. or higher include long chain aliphatic (meth) acrylates, alicyclic (meth) acrylates, aromatic (meth) acrylates, and oxy of these (meth) acrylates. Examples thereof include an alkylene structure-modified compound and a monofunctional unsaturated compound containing a nitrogen atom.

  Examples of the long-chain aliphatic (meth) acrylate include decane (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, isomyristyl acrylate (129 ° C.), isomyristyl methacrylate, and n-stearyl acrylate (181). ° C), n-stearyl methacrylate, isostearyl acrylate (154 ° C), isostearyl methacrylate and the like. Examples of these oxyalkylene structure-modified compounds include 2-ethylhexyl diethylene glycol acrylate (151 ° C.) and 2-ethylhexyl diethylene glycol. Methacrylate, methoxytriethylene glycol acrylate (143 ° C), methoxytriethylene glycol methacrylate, ethoxydiethylene glycol Examples include acrylate (113 ° C.), ethoxydiethylene glycol methacrylate, methoxydipropylene glycol acrylate (102 ° C.), methoxydipropylene glycol methacrylate, alkylene glycol monoalkyl ester (meth) acrylate, and alkylene glycol mono (meth) acrylate.

  Examples of the alicyclic (meth) acrylate include isobornyl acrylate (113 ° C.), isobornyl methacrylate, dicyclopentanyl acrylate (132 ° C.), dicyclopentanyl methacrylate, dicyclopentenyl acrylate (131 ° C. ), Dicyclopentenyl methacrylate, and the like. These oxyalkylene structure-modified compounds include, for example, t-butylcyclohexyloxyethyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, dicyclopentenyloxyethyl acrylate (166 ° C. ), Dicyclopentenyloxyethyl methacrylate, dicyclopentanyloxyethyl (meth) acrylate, and the like.

  Examples of the aromatic (meth) acrylate include benzyl acrylate (108 ° C.), benzyl methacrylate, biphenyl (meth) acrylate, naphthalene (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and 3-chloro. -2-hydroxypropyl (meth) acrylate and the like, and as these oxyalkylene (alkyl) structure-modified compounds, for example, phenoxyethyl acrylate (141 ° C.), phenoxyethyl methacrylate, phenoxydiethylene glycol acrylate (173 ° C.), phenoxydiethylene glycol Methacrylate, phenoxytriethylene glycol (meth) acrylate, phenoxytetraglycol (meth) acrylate, biphenyloxyethyl acetate Relate, nonylphenol ethylene oxide modified (repeat 4) acrylate (223 ° C), nonylphenol ethylene oxide modified (repeat 4) methacrylate, nonylphenol ethylene oxide modified (repeat 8) acrylate (304 ° C), nonylphenol ethylene oxide modified (repeat 8) methacrylate, etc. Nonylphenol alkylene oxide-modified (meth) acrylate and the like.

  The number of repeating units of the oxyalkylene structure is preferably 3 or less from the viewpoint of excellent adhesion performance.

  In addition, although the flash point was described in parentheses for the acrylate compound, the flash point is usually higher for the methacrylate compound corresponding to the acrylate compound having the flash point described.

  Among these long-chain aliphatic (meth) acrylates, alicyclic (meth) acrylates, aromatic (meth) acrylates, and oxyalkylene structure-modified compounds of these (meth) acrylates, excellent durability and light leakage resistance Preferred are alicyclic (meth) acrylates, aromatic (meth) acrylates, alicyclic (meth) acrylate oxyalkylene structure-modified compounds, and aromatic (meth) acrylate oxyalkylene structure-modified compounds, particularly preferably An oxyalkylene structure-modified compound of an alicyclic (meth) acrylate and an oxyalkylene structure-modified compound of an aromatic (meth) acrylate.

  Examples of the monofunctional unsaturated compound containing a nitrogen atom include N-acryloyloxyethyl hexahydrophthalimide (190 ° C.), acryloyl morpholine (130 ° C.), oxazolidone acrylate, acrylamide (134 ° C.), methacrylamide, butoxy. Examples include acrylamide, hydroxyethyl acrylamide (189 ° C.), dimethylaminopropyl acrylamide (140 ° C.), diacetone acrylamide (110 ° C.), etc. Among them, it is difficult to use an acrylamide unsaturated monomer, N-acryloyloxyethylhexahydrophthalimide is particularly preferable because of excellent balance in adhesive performance.

Among the monofunctional unsaturated compounds (B) described so far, a monofunctional unsaturated compound having a cyclic structure is preferable in terms of excellent durability, and more preferably a monofunctional unsaturated compound having an alicyclic structure. It is.
In addition, these monofunctional compounds (B) may be used individually by 1 type, and may use 2 or more types together.

  As a weight average molecular weight of the said monofunctional unsaturated compound (B), Preferably it is 150-10,000, Especially preferably, it is 200-1,000, More preferably, it is 220-500. If the weight average molecular weight is too large, the network of the monofunctional monomer network becomes loose and the durability tends to decrease. If the weight average molecular weight is too small, the pressure-sensitive adhesive tends to volatilize and the effect of the invention is obtained. It tends to be difficult.

  Further, as the monofunctional unsaturated compound (B), when 1 g of monofunctional unsaturated compound (B) and 10 g of ethyl acetate are mixed and then dried under the conditions of 105 ° C. × 5 min, the monofunctional unsaturated compound is used. What has the ratio of the remainder (weight) of a compound (B) being 95% or more is preferable.

  Examples of the monofunctional unsaturated compound (B) that satisfies the residual ratio in the volatility test include, for example, phenoxydiethylene glycol acrylate (residual ratio: 100%), ethoxylated orthophenylphenol acrylate (residual ratio: 100%). ). [<Reference value>, phenoxyethyl acrylate (residual ratio: 89.5%), benzyl acrylate (residual ratio: 67.8%), styrene (residual ratio: 0.5%)]

The glass transition temperature of the monofunctional unsaturated compound (B) (Tg), the Ri -100 to 60 ° C. der in that take balance of durability and adhesive property, and more preferably -30 to 60 ° C., particularly preferably -10 to 20 ° C. If the glass transition temperature of the monofunctional unsaturated compound (B) is too high, it tends to be difficult to control the adhesive force, and if it is too low, the durability tends to be poor.
The glass transition temperature (Tg) is calculated using the Fox equation described above.

The content of the monofunctional unsaturated compound (B), per 100 parts by weight of the acrylic resin (A), the a 1 0 0 by weight unit, particularly preferably 15 to 100 parts by weight, more preferably 20 to 60 parts by weight, particularly preferably 30 to 50 parts by weight.

  In the present invention, the pressure-sensitive adhesive composition [I] containing the acrylic resin (A) and the monofunctional unsaturated compound (B) as essential components contains active energy rays and / or heat (active energy ray irradiation). And / or heating) to obtain a pressure-sensitive adhesive for optical members.

In the present invention, when curing by the active energy ray and / or heat, the pressure-sensitive adhesive composition [I] further contains an ethylenically unsaturated compound (C) containing two or more ethylenically unsaturated groups. (Hereinafter sometimes abbreviated as “polyfunctional unsaturated compound (C)”) is necessary in that the cohesive force of the entire pressure-sensitive adhesive layer can be adjusted , and contains a polymerization initiator (D). It is preferable that the reaction at the time of irradiation with active energy rays and / or heating can be stabilized.
In such curing, the monofunctional aromatic compound (B) and the polyfunctional unsaturated compound (C) are polymerized (polymerized) by active energy rays and / or heat and cured.

  In the present invention, as a method of curing the pressure-sensitive adhesive composition [I], in addition to the component (A) and the component (B) (the component (C) or the component (D) as required) Further, there may be mentioned a method in which the crosslinking agent (E) is contained, and the pressure-sensitive adhesive composition [I] is cured by curing with active energy rays and / or heat and curing (crosslinking) with a crosslinking agent.

  In the present invention, the above-described curing by active energy rays and / or heat (irradiation of active energy rays and / or heating) is preferable in that it can be cured by irradiation of active energy rays such as ultraviolet rays for a very short time. However, it is also preferable to use curing (crosslinking) with a cross-linking agent in combination, and the cross-linking density of the pressure-sensitive adhesive is increased, the cohesive force is increased, and a further superior durability can be obtained.

  As the polyfunctional unsaturated compound (C), 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 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 (C) is preferably 0.01 to 100 parts by weight, particularly preferably 1 to 30 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). More preferably, it is 5-20 weight part. When the content of the polyfunctional unsaturated compound (C) is too large, both durability and light leakage resistance tend to decrease, and when too small, the light leakage resistance tends to decrease.

In the present invention, the monofunctional unsaturated compound (B) and the above-mentioned monofunctional unsaturated compound can be used in that the crosslinking density is appropriate, the tackiness can be appropriately adjusted, and the durability can be balanced. polyfunctional unsaturated compound greatly than the content ratio 50 mol% of a monofunctional aromatic compound to the total amount of (C) (B), particularly preferably less than 50 mol% greater than 100 mol%, more preferably 55~99mol %, Particularly preferably 60 to 98 mol%.

  When the content ratio of the monofunctional unsaturated compound (B) with respect to the total amount of the monofunctional aromatic compound (B) and the polyfunctional unsaturated compound (C) is too small, the monofunctional unsaturated compound (B) is used. Since the content of the polyfunctional unsaturated compound (C) increases, the crosslink density tends to increase too much and the tackiness tends to be insufficient. In addition, when the content rate of the monofunctional unsaturated compound (B) with respect to the total amount of a monofunctional unsaturated compound (B) and a polyfunctional unsaturated compound (C) is too large, a monofunctional unsaturated compound (B ), The content of the polyfunctional unsaturated compound (C) decreases, so that the crosslinking density does not increase so much and the durability tends to decrease.

  As the polymerization initiator (D), for example, various polymerization initiators such as a photopolymerization initiator (d1) and a thermal polymerization initiator (d2) can be used. It is preferable to use d1) in that it can be cured by irradiation with active energy rays such as ultraviolet rays for a very short time.

  Moreover, when using the said photoinitiator (d1), adhesive composition [I] is hardened by active energy ray irradiation, and when using a thermal polymerization initiator (d2), adhesive composition [ I] is cured, but it is also preferable to use both together if necessary.

  Examples of the photopolymerization initiator (d1) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4- Acetophenones such as morpholinophenyl) butanone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl Ben such as ether Ins; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethananium bromide, (4-benzoylbenzyl) trimethylammonium Benzophenones such as chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy -3 Thioxanthones such as 4-dimethyl-9H-thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl- And acyl phosphine oxides such as pentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; In addition, as for these photoinitiators (d1), only 1 type may be used independently and 2 or more types may be used together.

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

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

  Examples of the thermal polymerization initiator (d2) include methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetyl acetate peroxide, 1,1-bis (t-hexyl peroxide). ) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1, 1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) -cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 1,1- Bis (t-butylperoxy) butane, 2,2-bis (4 -Di-t-butylperoxycyclohexyl) propane, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroper Oxide, t-butyl hydroperoxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-Butyl cumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexa Noyl peroxide, octanoyl per Oxide, lauroyl peroxide, stearoyl peroxide, succinic acid peroxide, m-toluoyl benzoyl peroxide, benzoyl peroxide, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis (4-t-butyl) (Cyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-s-butyl peroxydicarbonate, Di (3-methyl-3-methoxybutyl) peroxydicarbonate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-te Lamethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxy Pivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylper) Oxy) hexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t- Hexyl peroxyisopropyl monocarbonate, t-butyl peroxyisobutyrate t-butyl peroxymalate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2 -Ethylhexyl monocarbonate, t-butyl peroxyacetate, t-butyl peroxy-m-toluylbenzoate, t-butyl peroxybenzoate, bis (t-butylperoxy) isophthalate, 2,5-dimethyl-2,5 -Bis (m-toluylperoxy) hexane, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyallyl monocarbonate, t-butyltrimethylsilylper Oxide, 3,3 ', 4,4'-tetra Organic peroxide initiators such as (t-butylperoxycarbonyl) benzophenone and 2,3-dimethyl-2,3-diphenylbutane; 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 1- [(1-cyano-1-methylethyl) azo] formamide, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′- Azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis (2-methyl- N-phenylpropionamidine) dihydrochloride, 2,2'-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] Hydride chloride, 2,2'-azobis [N- (4-hydrophenyl) -2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride 2,2'-azobis [2-methyl-N- (2-propenyl) propionamidine] dihydrochloride, 2,2'-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine] dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl) Lopan] dihydrochloride, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (5-hydroxy-3 , 4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane] dihydrochloride 2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] ] Propionamide], 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide], 2,2'-azobis [2-me Til-N- (2-hydroxyethyl) propionamide], 2,2'-azobis (2-methylpropionamide), 2,2'-azobis (2,4,4-trimethylpentane), 2,2'- Azobis (2-methylpropane), dimethyl-2,2-azobis (2-methylpropionate), 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis [2- (hydroxymethyl ) Propionitrile] and the like; and the like. In addition, only 1 type may be used independently for these thermal polymerization initiators, and 2 or more types may be used together.

  About content of the said polymerization initiator (D), 0.01-10 weight part with respect to 100 weight part of said acrylic resin (A), Especially 0.1-7 weight part, Furthermore, 0.3 It is preferably ~ 3 parts by weight. If the content of the polymerization initiator (D) 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. Moreover, it is preferable that it is 0.01-100 weight part with respect to a total of 100 weight part of a monofunctional unsaturated compound (B) and a polyfunctional unsaturated compound (C), More preferably, it is 0.1-100 weight part. 20 parts by weight, particularly preferably 1 to 15 parts by weight.

  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 without using the said photoinitiator (d1).

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. In the case of the high-pressure mercury lamp, for example, it is performed under conditions of 5 to 3000 mJ / cm ² , preferably 10 to 1000 mJ / cm ² . Moreover, in the case of the said electrodeless lamp, it is performed on the conditions of 2-1500 mJ / cm < ² >, for example, Preferably 5-500 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 (d2) as said polymerization initiator (D), 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 (d2) 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.

  Examples of the crosslinking agent (E) include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, amine crosslinking agents, and metal chelate crosslinking agents. Among these, an isocyanate-based crosslinking agent is preferably used from the viewpoint of improving the adhesion to the substrate and the reactivity with the base polymer.

  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 (E) may be used independently and may use 2 or more types together.

  In general, the content of the crosslinking agent (E) is preferably 0.01 to 20 parts by weight, more preferably 1 to 15 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). Particularly preferred is 4 to 10 parts by weight. When the amount of the crosslinking agent (E) is too small, there is a tendency that the cohesive force is insufficient and sufficient durability cannot be obtained, and when it is too large, the flexibility and the adhesive strength are lowered, and the durability is liable to be lowered. Seen.

  In the present invention, it is preferable to further contain a silane coupling agent (F) as a constituent component of the pressure-sensitive adhesive composition [I] from the viewpoint of improving the adhesion to the optical member.

  Examples of the silane coupling agent (F) include an epoxy group-containing silane coupling agent, a (meth) acryloyl group-containing silane coupling agent, a mercapto group-containing silane coupling agent, a hydroxyl group-containing silane coupling agent, and a carboxyl group-containing. Examples thereof include a silane coupling agent, an amino group-containing silane coupling agent, an amide group-containing silane coupling agent, and an isocyanate group-containing silane coupling agent. These may be used alone or in combination of two or more. Among these, an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent are preferably used, and the combined use of an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent also improves wet heat durability. It is preferable in that the adhesive strength does not increase too much.

  Specific examples of the epoxy group-containing silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycol. Sidoxypropylmethyldimethoxysilane, methyltri (glycidyl) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like can be mentioned. γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

  Specific examples of the mercapto group-containing silane coupling agent include, for example, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, oligomer type mercapto silane coupling agent, and the like. Can be given.

  Among these, an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent are preferably used.

  As content of a silane coupling agent (F), it is 0.001-10 weight part normally with respect to 100 weight part of said acrylic resin (A), Preferably it is 0.01-1 weight part, Especially. Preferably it is 0.03-0.8 weight part. If the content of the silane coupling agent (F) is too small, there is a tendency that the addition effect cannot be obtained. If the content is too large, the compatibility with the acrylic resin (A) is reduced, and adhesive strength and cohesive strength can be obtained. There is a tendency to get tired.

The pressure-sensitive adhesive composition [I] further includes an antistatic agent, other pressure-sensitive adhesives, urethane resin, rosin, rosin ester, hydrogenated rosin ester, phenolic resin, aromatic, as long as the effects of the present invention are not impaired. Modified terpene resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins, xylene resins, and other tackifiers, colorants, fillers, anti-aging agents, ultraviolet absorbers, functional dyes, etc. Known additives and compounds that cause coloration or discoloration upon irradiation with ultraviolet rays or radiation can be blended.
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 [I] may be contained.

  Examples of the antistatic agent include cationic antistatic agents of quaternary ammonium salts such as imidazolium salts and tetraalkylammonium sulfonates, aliphatic sulfonates, higher alcohol sulfates, and higher alcohol alkylene oxide additions. Anion-type antistatic agents such as sulfuric acid ester salts, higher alcohol phosphate salts, higher alcohol alcohol alkylene oxide adduct phosphate salts, potassium bis (fluorosulfonyl) imide, lithium bis (trifluorosulfonyl) imide and lithium chloride And alkali metal salts such as alkaline earth metal salts, higher alcohol alkylene oxide adducts, and polyalkylene glycol fatty acid esters.

  Thus, in the present invention, the pressure-sensitive adhesive composition [I] is cured to obtain a pressure-sensitive adhesive for optical parts.

  And the optical member with an adhesive layer can be obtained by carrying out lamination formation of the adhesive layer which consists of the said adhesive for optical parts on an optical member (optical laminated body).

  It is preferable that the optical member with the pressure-sensitive adhesive layer is further provided with a release sheet on the surface opposite to the optical member surface of the pressure-sensitive adhesive layer.

  As the method for producing the optical member with the pressure-sensitive adhesive layer, when the pressure-sensitive adhesive composition [I] is cured by at least one of active energy ray irradiation and heating, [1] the pressure-sensitive adhesive composition on the optical member After applying and drying the product [I], a release sheet is bonded, and the treatment is performed by at least one of active energy ray irradiation and heating, [2] the pressure-sensitive adhesive composition [I] on the release sheet After applying and drying, a method of pasting the optical member and performing treatment by at least one of active energy ray irradiation and heating, [3] applying and drying the adhesive composition [I] on the optical member, A method of pasting a release sheet after performing treatment by at least one of irradiation with active energy rays and heating, [4] coating and drying the adhesive composition [I] on the release sheet, and further active energy rays After performing the morphism and at least one by treatment with heating, and a method of bonding an optical member. Among these, the case of performing active energy ray irradiation by the method [2] is preferable from the viewpoint of not damaging the substrate, workability and stable production.

  In applying the pressure-sensitive adhesive composition [I], it is preferable to dilute the pressure-sensitive adhesive composition [I] in a solvent, and the dilution concentration is preferably 5 to 95% by weight, particularly preferably 10%. -80% by weight, more preferably 17-60% by weight, particularly preferably 25-40% by weight. The solvent is not particularly limited as long as it can dissolve the pressure-sensitive adhesive composition [I]. Examples thereof include ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate, acetone Further, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and propyl alcohol can be used. Among these, ethyl acetate and methyl ethyl ketone are preferably used from the viewpoints of solubility, drying property, price, and the like.

  In addition, the application of the pressure-sensitive adhesive composition [I] is performed by a conventional method such as roll coating, die coating, gravure coating, comma coating, or screen printing.

In addition, when a crosslinking agent is used for the pressure-sensitive adhesive composition [I] (when curing with a crosslinking agent (crosslinking) is also used), an aging treatment is performed after the optical member with the pressure-sensitive adhesive layer is produced using the above method. It is preferable to apply. Such aging treatment is performed to balance the physical properties of the adhesive. As aging conditions, the temperature is usually from room temperature to 70 ° C., and the time is usually from 1 day to 30 days. 1 to 20 days at ℃, 3 to 10 days at 23 ℃, 40
What is necessary is just to carry out on conditions, such as 1 day-7 days at ° C.

  The gel fraction of the pressure-sensitive adhesive layer produced by the above method is preferably 30 to 100%, more preferably 60 to 90%, particularly 70 to 85, from the viewpoints of durability and light leakage prevention performance. % Is preferred. If the gel fraction is too low, durability tends to be insufficient due to insufficient cohesive force. Moreover, when the gel fraction is too high, tackiness is insufficient due to an increase in cohesive force, and the tackiness of the pressure-sensitive adhesive on the adherend tends to decrease.

  The pressure-sensitive adhesive layer produced by the above method preferably has a good tack feeling when touched with a finger, because it has good wettability when actually attached to an adherend, and therefore tends to improve workability. .

  In adjusting the gel fraction of the optical member pressure-sensitive adhesive to the above range, for example, adjusting the irradiation amount and irradiation intensity of the active energy ray, adjusting the type and amount of the unsaturated group-containing compound, This is achieved by adjusting the type of polymerization initiator and the combination ratio thereof, adjusting the blending amount of the polymerization initiator, adjusting the type and amount of the crosslinking agent, and the like. Moreover, since the gel fraction changes by each interaction, the irradiation amount and irradiation intensity | strength of said active energy ray, the composition ratio of a polymerization initiator, and addition amount need to balance each.

  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.

  Moreover, 5-300 micrometers is preferable normally, and, as for the thickness of the adhesive layer in the optical member with an adhesive layer obtained, 10-50 micrometers is especially preferable, Furthermore, 12-30 micrometers is preferable. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive physical properties tend to be difficult to stabilize, and if it is too thick, the thickness of the entire optical member tends to increase too much.

  The optical member with the pressure-sensitive adhesive layer of the present invention has a release sheet directly or after the release sheet is peeled off, and then the surface of the pressure-sensitive adhesive layer is bonded to a glass substrate and used for a liquid crystal display panel, for example. .

  The initial adhesive strength of the pressure-sensitive adhesive layer of the present invention is appropriately determined according to the material of the adherend. For example, when sticking on a glass substrate, it preferably has an adhesive strength of 0.2 N / 25 mm to 20 N / 25 mm, and more preferably 0.5 N / 25 mm to 10 N / 25 mm.

  The initial adhesive strength is calculated as follows. The polarizing plate with the pressure-sensitive adhesive layer is cut to a width of 25 mm, the release film is peeled off, and the pressure-sensitive adhesive layer side is pressed against a non-alkali glass plate (Corning XG), polarizing plate and glass. Paste the board. Then, after performing an autoclave process (50 degreeC, 0.5 MPa, 20 minutes), 23 degreeC and 50% R. H. Then, after leaving for 24 hours, perform a 180 ° C. peel test.

  The optical member in the present invention is not particularly limited, and an optical film suitably used for an image display device such as a liquid crystal display device, an organic EL display device, or a PDP, such as a polarizing plate, a retardation plate, or an elliptical polarizing plate. , Optical compensation films, brightness enhancement films, and those in which these are laminated. Among them, a polarizing plate is particularly effective in the present invention.

  The polarizing plate used in the present invention is usually a laminate of a cellulose triacetate film as a protective film on both sides of a polarizing film. The polarizing film has an average degree of polymerization of 1,500 to 10,000, A uniaxially stretched film dyed with an aqueous solution of iodine-potassium iodide or a dichroic dye using a film made of a polyvinyl alcohol resin having a degree of conversion of 85 to 100 mol% as a raw film (usually 2 to 10 times, preferably Is a stretching ratio of about 3 to 7 times.

  The polyvinyl alcohol resin is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but a small amount of unsaturated carboxylic acid (including salt, ester, amide, nitrile, etc.), olefins, vinyl ether And a component copolymerizable with vinyl acetate, such as an unsaturated sulfonate. Moreover, what is called polyvinyl acetal resin and polyvinyl alcohol derivatives, such as polybutyral resin and polyvinyl formal resin, which are obtained by reacting polyvinyl alcohol with an aldehyde in the presence of an acid can be mentioned.

  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 resins were prepared as follows. In addition, about the measurement of the weight average molecular weight of acrylic resin, a dispersion degree, a glass transition temperature, and an acid value, it measured according to the above-mentioned method.
In addition, regarding the measurement of a viscosity, it measured according to the 4.5.3 rotational viscometer method of JISK5400 (1990).

[Preparation of Acrylic Resin (A)] (See Table 1)
[Acrylic resin (A-1)]
A 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer was charged with 90 parts of butyl acrylate (a1), 10 parts of acrylic acid (a3) and 80 parts of ethyl acetate and heated. After the start of reflux, 0.5 part of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, reacted for 7 hours at the reflux temperature of ethyl acetate, diluted with ethyl acetate, and the acrylic resin (A-1) solution (Weight average molecular weight (Mw) 750,000, dispersity (Mw / Mn) 4.2, glass transition temperature -46 ° C., solid content 35%, viscosity 7,000 mPa · s (25 ° C.), acid value 78 mgKOH / g) Got.

[Acrylic resin (A-2)]
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 85 parts of butyl acrylate (a1), 5 parts of phenoxyethyl acrylate (a2), 10 parts of acrylic acid (a3) , And 100 parts of ethyl acetate were added, and after heating to reflux, 0.5 parts of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, reacted at ethyl acetate reflux temperature for 7 hours, and diluted with ethyl acetate. Acrylic resin (A-2) solution (weight average molecular weight (Mw) 600,000, dispersity (Mw / Mn) 4.7, glass transition temperature -45 ° C., solid content 35%, viscosity 4,000 mPa · s ( 25 ° C.) and an acid value of 78 mgKOH / g).

[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, 95 parts of butyl acrylate (a1), 5 parts of acrylic acid (a3) and 150 parts of ethyl acetate, 45 parts of acetone After starting the reflux with heating, 0.03 part of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, reacted at the reflux temperature of ethyl acetate for 3 hours, diluted with ethyl acetate, and then the acrylic resin (A -3) Solution (weight average molecular weight (Mw) 1,500,000, dispersity (Mw / Mn) 3.5, glass transition temperature -51 ° C., solid content 20%, viscosity 8,000 mPa · s (25 ° C.), acid value 39 mg KOH / g) was obtained.

(Note) BA: Butyl acrylate
AAc: Acrylic acid PEA: Phenoxyethyl acrylate

[Monofunctional unsaturated compound (B)]
The following were prepared as the monofunctional unsaturated compound (B-1).
Phenyl diethylene glycol acrylate (manufactured by Kyoeisha, trade name “Light acrylate P2HA”: molecular weight 236.3)
The following were prepared as the monofunctional unsaturated compound (B-2).
・ Isobornyl acrylate (Made in Osaka Organic Chemical Industry, molecular weight: 205)
The following were prepared as the monofunctional unsaturated compound (B-3).
Dicyclopentenyloxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “Fancryl FA-512AS” molecular weight: 248)

[Polyfunctional unsaturated compound (C)]
The following were prepared as the polyfunctional unsaturated compound (C-1).
・ Trimethylolpropane triacrylate (molecular weight 296.3)

[Polymerization initiator (D)]
The following were prepared as the photopolymerization initiator (D-1).
A mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone in a mass ratio of 1: 1 (Ciba Specialty Chemicals, “Irgacure 500”)

[Crosslinking agent (E)]
The following were prepared as a crosslinking agent (E-1).
・ 55% ethyl acetate solution of trimethylolpropane tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Co., Ltd., “Coronate L-55E”)

[Silane coupling agent (F)]
The following were prepared as the silane compound (F-1).
・ Mercapto silane coupling agent (oligomer type) (manufactured by Shin-Etsu Chemical Co., Ltd., “X-41-1805”)

[Examples 1 to 4 , Reference Example 1, Comparative Examples 1 and 2]
Prepare the pressure-sensitive adhesive composition to be a pressure-sensitive adhesive forming material for optical members by blending the components prepared and prepared as described above in the proportions shown in Table 2 below, and dilute them with ethyl acetate. A pressure-sensitive adhesive composition solution was prepared.

Then, the pressure-sensitive adhesive composition solution obtained above was applied to a polyester release sheet so that the thickness after drying was 25 μm, and dried at 90 ° C. (70 ° C. only in Example 4) for 1.5 minutes. After that, the formed pressure-sensitive adhesive composition layer was transferred onto a polyethylene terephthalate (PET) film (thickness 38 μm). For Examples 1 to 5 and Comparative Example 2, an electrodeless lamp manufactured by Fusion [LH6UV lamp H Bulb] was irradiated with ultraviolet rays at a peak illuminance of 600 mW / cm ² and an integrated exposure amount of 240 mJ / cm ² (120 mJ / cm ² × 2 passes), 23 ° C. × 50% R.D. H. The film was aged for 10 days under the above conditions to obtain a PET film with an adhesive layer. Moreover, about the comparative example 1, ultraviolet irradiation was not performed but only the aging process was performed on the same conditions, and the PET film with an adhesive layer was obtained.

  The dryness at the time of producing the PET film with the pressure-sensitive adhesive layer was evaluated as follows.

[Proper drying]
<Volatile solvent amount>
The amount of the solvent that volatilized when the pressure-sensitive adhesive composition solution was dried at 90 ° C. for 1.5 minutes was measured. The amount of the volatile solvent was expressed in terms of the amount of solvent that volatilizes when the pressure-sensitive adhesive resin composition is used and dried so as to obtain the pressure-sensitive adhesive 1t.
From the current situation where green production is desired, it is desirable that the amount of volatile (disposal) solvent when producing adhesive 1t is less than 3t.

<Odor resistance>
About the PET film with an adhesive layer manufactured by drying the said adhesive composition solution for 30 seconds at 100 degreeC, the odor of the ethyl acetate which is a volatile solvent was confirmed.
(Evaluation)
○ ・ ・ ・ No odor.
△ ・ ・ ・ Slight odor × ・ ・ ・ Smell odor

  Moreover, gel fraction was measured and evaluated according to each method shown below using the obtained PET film with an adhesive layer.

[Gel fraction]
After the obtained PET film with the pressure-sensitive adhesive layer is cut into 40 × 40 mm, the release sheet is peeled off and the pressure-sensitive adhesive layer side is bonded to a 50 × 100 mm SUS mesh sheet (200 mesh), and then the SUS mesh sheet. After wrapping the sample from the center with respect to the longitudinal direction, the gel fraction was measured by the change in weight when immersed in a sealed container containing 250 g of toluene at 23 ° C. for 24 hours.

Next, the pressure-sensitive adhesive composition solutions of Examples 1 to 4 , Reference Example 1 and Comparative Examples 1 and 2 were applied to a polyester release sheet so that the thickness after drying was 25 μm. After drying for a minute, the formed pressure-sensitive adhesive composition layer was transferred onto a polarizing plate (thickness 190 μm), and peak illuminance: 600 mW / cm2, integrated exposure amount with a fusion-free electrodeless lamp [H bulb of LH6UV lamp]. : UV irradiation at 240 mJ / cm 2 (120 mJ / cm 2 × 2 passes), 23 ° C. × 65% R.D. H. The film was aged for 10 days under the above conditions to obtain a polarizing plate with an adhesive layer.
In addition, “MLP38U” manufactured by Biei Imaging Co., Ltd. was used as the polarizing plate, and the polarizing plate was cut at 45 ° C. with respect to the stretching axis.

  Using the polarizing plate with the pressure-sensitive adhesive layer thus obtained, durability (wet heat resistance test, heat cycle test, heat resistance test) and adhesive strength were measured and evaluated according to the following methods. These results are also shown in Table 3 below.

〔durability〕
The release sheet of the obtained polarizing plate with the pressure-sensitive adhesive layer was peeled off, and the pressure-sensitive adhesive layer side was pressed against a non-alkali glass plate (Corning Corp., Eagle XG) to bond the polarizing plate and the glass plate. After that, autoclave treatment (50 ° C., 0.5 MPa, 20 minutes) is performed, and then foaming and peeling are evaluated in the following durability tests (1) to (4) (moisture and heat resistance test, heat cycle test, heat resistance test). I did it. Furthermore, in the heat resistance test of (4) below, in addition to the evaluation of foaming and peeling, a sample for light leakage observation was prepared by bonding the same sample on both the front and back surfaces so that the polarizing plate became crossed Nicol. The light leakage phenomenon was also evaluated.
In addition, the used test piece size was punched into 20 cm × 15 cm.

〔An endurance test〕
(1) Moisture and heat resistance test 60 ° C., 90% R.D. H. Endurance test for 150 hours (2) Heat cycle test Endurance test for 75 cycles with the operation of leaving at -35 ° C for 60 minutes and then at 70 ° C for 60 minutes (3) Heat resistance test (A)
Durability test at 90 ° C for 150 hours (4) Heat resistance test (B)
Durability test at 150C for 150 hours and light leakage evaluation

〔Evaluation criteria〕
(Foam)
○: Foam is hardly seen △ ... Foam is slightly seen × ... Foam is seen a lot (peeling)
○ ・ ・ ・ Peeling of less than 0.5 mm or occurrence of floating marks less than 0.5 mm Δ ・ ・ ・ Peeling of 0.5 mm or more and less than 10 mm, or generation of lift marks of 0.5 mm or more and less than 10 mm × ・ ・ ・10 mm or more peeling or 10 mm or more of lift mark (light leakage)
◎ ・ ・ ・ There is almost no light leakage ○ ・ ・ ・ Slight leakage occurs △ ・ ・ ・ Slight leakage occurs × ・ ・ ・ Large light leakage occurs on 4 sides

[Initial adhesive strength]
About the prepared polarizing plate with an adhesive layer, it cuts to width 25mm width, peels off a release film, presses the adhesive layer side to a non-alkali glass board (Corning company make, "Corning 1737"), and polarized light The plate and the glass plate were bonded together. Thereafter, autoclaving (50 ° C., 0.5 MPa, 20 minutes) was performed, and 23 ° C. 50% R.D. H. A 180 ° C. peel test was performed after leaving the sample for 24 hours. In reworkability (peelability), it is desirable that the adhesive strength is small, and the target is 10 N / 25 mm or less after one day.

Since the adhesives of Examples 1 to 4 use a low molecular weight acrylic resin having a low resin viscosity, it is possible to increase the solid content concentration when diluted to a viscosity that can be applied, and only with durability performance. In addition, it is excellent in drying suitability, has high energy efficiency, and can produce a pressure-sensitive adhesive cleanly.
On the other hand, although the acrylic resin having a low molecular weight was used, it was found that the comparative example 1 in which the monofunctional unsaturated compound (B) was not used was inferior in durability performance.
Further, in Comparative Example 2 using an acrylic resin having a high molecular weight, since a large amount of diluent solvent is used to make the viscosity of the acrylic resin high and coatable, the durability performance is excellent. However, compared to the pressure-sensitive adhesives of the examples, about twice as much waste solvent is generated during drying and the solvent odor is also generated, so it is difficult to say that this is a clean manufacturing method.

  The pressure-sensitive adhesive for optical members of the present invention is an optical layered body, particularly an optical member such as a polarizing plate and a glass substrate, even when the pressure-sensitive adhesive layer after curing with active energy rays and / or heat is in a high temperature and high humidity environment. Thus, a liquid crystal display device can be obtained in which foaming or peeling does not occur between the pressure-sensitive adhesive layer and the glass substrate, and color unevenness or light leakage does not occur. In addition, since it requires less waste solvent, it is useful as an adhesive that can be produced in an environmentally friendly and small environmental load.

Claims (7)

Acrylic resin (A), a compound containing one d ethylenic unsaturated group (B), and an ethylenically unsaturated compound an ethylenically unsaturated group containing two or more (C) a pressure-sensitive adhesive composition containing a [I] is an adhesive for optical members that is cured by active energy rays and / or heat, the acrylic resin (A) has a weight average molecular weight of 100,000 to 1,000,000, and an ethylenically unsaturated group. The compound (B) containing one compound has a glass transition temperature of −100 to 60 ° C., and the content of the compound (B) containing one ethylenically unsaturated group with respect to 100 parts by weight of the acrylic resin (A) is 10. 100 parts by weight, ethylenically unsaturated relative to the total amount of compounds containing one d ethylenic unsaturated group (B) an ethylenically unsaturated compound containing two or more ethylenically unsaturated groups (C) Contains one group Adhesive for optical members content being greater than 50 mol% of the compound (B).   The pressure-sensitive adhesive for optical members according to claim 1, wherein the acid value of the acrylic resin (A) is 10 mgKOH / g or more.   The compound (B) containing one ethylenically unsaturated group is an aromatic monofunctional monomer having an aromatic ring and one ethylenically unsaturated group in the molecule. Adhesive for optical members.   The pressure-sensitive adhesive composition [I] contains a polymerization initiator (D), and the pressure-sensitive adhesive for optical members according to any one of claims 1 to 3.   An optical member is a polarizing plate, The adhesive for optical members in any one of Claims 1-4 characterized by the above-mentioned.   An optical member with a pressure-sensitive adhesive layer, comprising a laminated structure of a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive for optical members according to claim 1 and an optical member.   An image display device comprising the optical member with an adhesive layer according to claim 6.