JP5022043B2 - Active energy ray-curable adhesive composition and polarizing plate using the same - Google Patents

Description

  The present invention relates to an active energy ray-curable adhesive composition, particularly an active energy ray-curable adhesive composition suitable for adhesion between a polyvinyl alcohol-based polarizing film and a thermoplastic norbornene-based resin film, and polarized light obtained by using the same. It is about a board.

  In general, adhesive compositions are widely used in various fields such as packaging materials, display materials such as labels, electronic parts, precision equipment, construction materials and the like. In recent years, active energy ray-curable adhesive compositions that are cured with active energy rays such as ultraviolet rays and electron beams are widely used in place of conventional thermosetting types for the purpose of speeding up production processes and improving productivity. ing. Thus, as the field of use expands and the requirements for the purpose of use increase, the demand for higher performance is also increasing for the active energy ray-curable adhesive composition.

  On the other hand, a polarizing film used in a liquid crystal display-related field or the like is usually produced by uniaxially stretching a polyvinyl alcohol (PVA) adsorbed with iodine or a dye. In order to shrink | contract with a water | moisture content and bring about the fall of polarizing performance, it is used in the state of the polarizing plate by which the protective film was bonded by the surface.

  Conventionally, an aqueous solution of a polyvinyl alcohol resin (PVA adhesive) has been widely used as an adhesive for attaching a protective film to a polarizing film. However, such a polyvinyl alcohol-based adhesive is suitable when triacetyl cellulose (TAC) is used as a protective film, but is a thermoplastic norbornene-based resin for improving moisture resistance and reducing the thickness of the protective film. When the film is used as a protective film, the water vapor transmission rate is very small, so it takes time to dry the adhesive, which is not only a problem in terms of productivity, but also a polyvinyl alcohol polarizing film and a thermoplastic norbornene. The adhesive strength with the resin film was not sufficient.

  As a method for solving such a problem, for example, in Patent Document 1, a hydrophilic layer is formed of polyvinyl pyrrolidone or the like on the surface of a thermoplastic resin such as a thermoplastic norbornene resin film, and 0.001 to It is possible to bond a polyvinyl alcohol film after forming a water film having a thickness of 20 μm. Patent Document 2 uses a saponified product of vinyl acetate and a monomer copolymerizable therewith as a urethane alcohol resin, and a urethane adhesive. In Patent Document 3, a thermoplastic saturated norbornene-based resin sheet is laminated on at least one surface of a polyvinyl alcohol-based sheet via an acrylic pressure-sensitive adhesive layer. It has been proposed to heat-press.

  However, the method of Patent Document 1 has a problem that it needs to be processed many times. The method of Patent Document 2 improves the adhesion performance, but the problem caused by using a water-based adhesive is that of Patent Document 3. There was a problem that sufficient adhesiveness could not be obtained with the pressure-sensitive adhesive, and there was a problem that the thickness of the pressure-sensitive adhesive itself had to be increased to a certain degree of 10 to 50 μm.

On the other hand, an active energy ray-curable adhesive composition used for bonding a polyvinyl alcohol polarizing film and a thermoplastic norbornene resin film has also been developed. For example, Patent Document 4 describes a polarizing plate in which a protective sheet is laminated on both sides of a polarizer, and an adhesive layer made of an active energy ray-curable compound is laminated on one side of the protective sheet. Yes. Patent Document 5 includes (a) a urethane (meth) acrylate compound having a number average molecular weight of 5,000 to 15,000, (b) one kind selected from acryloylmorpholine, dimethylacrylamide, diethylacrylamide and diisopropylacrylamide, or Liquid curable adhesive / adhesive compositions containing two or more compounds, (c) phenoxyethyl acrylate, phenoxy polyethylene glycol acrylate, or the like have been proposed. Patent Document 6 includes (A) 30 to 70 parts by weight of urethane acrylate having a number average molecular weight of 10,000 to 40,000, and (B) an ethylenically unsaturated monomer having a glass transition temperature of 60 ° C. or higher. A liquid curable resin composition containing 30 to 60 parts by weight has been proposed. Patent Document 7 discloses (A) a conjugated diene polymer having at least one (meth) acryloyl group in the molecule in order to improve adhesion performance to a nonpolar substrate such as a thermoplastic saturated norbornene resin sheet. (B) An adhesive containing a compound having at least one ethylenically unsaturated bond in the molecule and a radical polymerization initiator has been proposed. In Patent Document 8, (A) 30 to 70 parts by weight of urethane (meth) acrylate having a number average molecular weight of 10,000 to 40,000 (B) 0.1 to 70 parts by weight of an ethylenically unsaturated monomer having a cyclic ether Radiation curable resin compositions containing parts have been proposed.

  However, the adhesives described in Patent Documents 4 to 8 cannot provide adhesive strength sufficiently satisfactory for adhesion between the polyvinyl alcohol polarizing film and the thermoplastic norbornene resin film.

JP 2004-59911 A JP 2004-334168 A Japanese Patent Laid-Open No. 5-212828 JP 2004-70290 A JP-A-7-310067 JP 2004-115757 A JP 2004-161935 A JP 2005-255844 A

  In view of the above problems, the present invention is an active energy ray-curable adhesive composition that can be easily bonded and can firmly bond a polyvinyl alcohol polarizing film and a thermoplastic norbornene resin film in a short time. And it aims at providing the polarizing plate obtained by bonding using this adhesive composition.

  As a result of intensive studies to achieve the above object, the present inventors have reached the present invention.

（式中、Ｒ１は水素原子またはメチル基、Ｒ２は炭素数２〜６のアルキレン基、Ｒ３はフェニル基またはアルキレン（炭素数１〜１２のアルキレン）フェニル基である。ｎは２〜１７の実数を示す。）を含有する活性エネルギー線硬化型接着剤組成物；
（２） （ａ）分子内に（メタ）アクリロイル基を２以上有する（メタ）アクリル系化合物が、（メタ）アクリロイル基を２又は３個有することを特徴とする（１）記載の活性エネルギー線硬化型接着剤組成物；
（３） （ｂ）分子内に水酸基を有し、重合性二重結合をただ１個有する（メタ）アクリル系化合物が、ヒドロキシアルキル（メタ）アクリレート又はヒドロキシアクリルアミド誘導体であることを特徴とする（１）または（２）記載の活性エネルギー線硬化型接着剤組成物；
（４） （メタ）アクリル系化合物の合計量１００重量部に対して、重合開始剤を２〜１０重量部配合することを特徴とする（１）〜（３）のいずれかに記載の活性エネルギー線硬化型接着剤組成物；
（５） （１）〜（４）のいずれかに記載の活性エネルギー線硬化型接着剤組成物により、ポリビニルアルコール系偏光フィルムと熱可塑性ノルボルネン系樹脂フィルムを貼合して得られることを特徴とする偏光板；
（６） 浮動ローラ法（ＪＩＳ Ｋ６８５４）での剥離強度が７８Ｎ／ｍ以上であることを特徴とする（５）記載の偏光板；
を要旨とするものである。 That is, the present invention
(1) 10 to 40 parts by weight of (meth) acrylic compound having 2 or more (meth) acryloyl groups in the molecule (a) in 100 parts by weight of the total amount of (meth) acrylic compound (b) in the molecule 15 to 45 parts by weight of (meth) acrylic compound having a hydroxyl group and having only one polymerizable double bond (c) 35 to 45 (meth) acrylic compound represented by the following general formula [1] Parts by weight

Wherein R1 is a hydrogen atom or a methyl group, R2 is an alkylene group having 2 to 6 carbon atoms, R3 is a phenyl group or an alkylene (alkylene having 1 to 12 carbon atoms) phenyl group, and n is a real number having 2 to 17 Active energy ray-curable adhesive composition containing
(2) (a) The active energy ray according to (1), wherein the (meth) acrylic compound having two or more (meth) acryloyl groups in the molecule has two or three (meth) acryloyl groups Curable adhesive composition;
(3) (b) The (meth) acrylic compound having a hydroxyl group in the molecule and having only one polymerizable double bond is a hydroxyalkyl (meth) acrylate or a hydroxyacrylamide derivative ( 1) or active energy ray-curable adhesive composition according to (2);
(4) The active energy according to any one of (1) to (3), wherein 2 to 10 parts by weight of a polymerization initiator is blended with respect to 100 parts by weight of the total amount of the (meth) acrylic compound. Wire curable adhesive composition;
(5) It is obtained by bonding a polyvinyl alcohol polarizing film and a thermoplastic norbornene resin film with the active energy ray-curable adhesive composition according to any one of (1) to (4). Polarizing plate;
(6) The polarizing plate according to (5), wherein the peel strength according to the floating roller method (JIS K6854) is 78 N / m or more;
Is a summary.

  When the active energy ray-curable adhesive composition of the present invention is used, it exhibits high adhesion not only to a thermoplastic norbornene resin film but also to a highly hydrophilic polyvinyl alcohol polarizing film. A norbornene-based resin film is bonded to a norbornene-based resin film with a strength of, for example, a floating roller method (JIS K6854) of 78 N / m or more (including material destruction and non-peeling), and in a short time (in-line). Became possible. Further, unlike the case of the pressure-sensitive adhesive, it can be applied even with a thickness of 5 μm or less, so that a thermoplastic norbornene-based resin film excellent in optical properties and moisture-proof properties without deteriorating the optical properties due to the adhesive layer is used as a polyvinyl alcohol polarizing film. It became possible to provide a high-performance polarizing plate used as a protective film.

The present invention is described in detail below. In the present invention, “(meth) acryl” means acryl or methacryl. The “(meth) acryloyl group” is used to mean an acryloyl group or a methacryloyl group. The (meth) acrylic compound means a (meth) acrylic monomer or a (meth) acrylic oligomer.
The active energy ray-curable adhesive composition of the present invention is an adhesive composition that cures when irradiated with active energy rays. Here, active energy rays refer to, for example, ultraviolet rays, electron beams, X-rays, and the like. In particular, ultraviolet rays that are easy to use as an energy ray generator and easy to handle energy rays are more preferable.

Examples of the (meth) acrylic compound (a) having two or more (meth) acryloyl groups in the molecule used in the present invention include ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, tricyclode Canmethanol di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, isocyanuric acid ethylene oxide modified diacrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol (Meth) acrylate, pentaerythritol / ethylene oxide modified tri (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (2-hydroxyethyl) isocyanate (Meth) acrylic monomers such as nurate di (meth) acrylate, ε-caprolactone modified tris (2-acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, pentaerythritol / ethylene oxide modified tetra (meth) acrylate It is done. Also included are (meth) acrylic oligomers such as urethane acrylate. Moreover, (a) may use 1 type and can also use 2 or more types together.
Particularly preferred are (meth) acrylic compounds having 2 or 3 (meth) acryloyl groups in the molecule.

  The (a) used in the present invention has adhesiveness, flexibility, photocurability, viscosity, etc. by blending in a range of 10 to 40 parts by weight in a total amount of 100 parts by weight of the (meth) acrylic compound. It is preferable because it is easy to balance. If it is less than 10 parts by weight, the crosslinking density is low, the adhesion rate is slowed, and the adhesiveness is lowered, which is not preferable. On the other hand, if it exceeds 40 parts by weight, the crosslinking density is too high, the adhesive composition itself becomes hard, and the adhesiveness is lowered, which is not preferable. More preferably, it is blended in the range of 20 to 30 parts by weight.

The (meth) acrylic compound (b) having a hydroxyl group in the molecule used in the present invention and having only one polymerizable double bond includes, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, caprolactone modified (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, polyethylene glycol mono (meta ) Acrylate, trimethylolpropane (mono) acrylate, compounds obtained by addition reaction of glycidyl group-containing compounds such as alkyl glycidyl ether and glycidyl (meth) acrylate with (meth) acrylic acid, and N-methylol (methyl) T) acrylamide, N-hydroxyethyl (meth) acrylamide, N, N′-dihydroxyethylacrylamide and the like. Moreover, 1 type may be used for (b) component and it can also use 2 or more types together.
In particular, hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and hydroxyacrylamide derivatives such as N-hydroxyethyl (meth) acrylamide are preferred.
More preferably, hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide are preferable, and it is more preferable to use these in combination.

  (B) used in the present invention is preferably blended in the range of 15 to 45 parts by weight in 100 parts by weight of the total amount of the (meth) acrylic compound. If this is less than 15 parts by weight, the hydrophilicity of the adhesive composition as a whole is lowered, and in particular, the adhesiveness to the polyvinyl alcohol polarizing film is lowered, which is not preferable, and if it exceeds 45 parts by weight, the adhesive composition not only becomes hard, Since curability falls, it is not preferable. More preferably, it mix | blends in 20-40 weight part.

（式中、Ｒ１は水素原子またはメチル基、Ｒ２は炭素数２〜６のアルキレン基、Ｒ３はフェニル基またはアルキレン（炭素数１〜１２のアルキレン）フェニル基である。ｎは２〜１７の実数を示す。） The (meth) acrylic compound (c) represented by the following general formula [1] used in the present invention includes, for example, phenol ethylene oxide modified (n = 2 or n = 2.5 or n = 4) acrylate, nonylphenol And ethylene oxide-modified (n = 4 or n = 5 or n = 17) acrylate. Moreover, (c) may use 1 type and can also use 2 or more types together.

Wherein R1 is a hydrogen atom or a methyl group, R2 is an alkylene group having 2 to 6 carbon atoms, R3 is a phenyl group or an alkylene (alkylene having 1 to 12 carbon atoms) phenyl group, and n is a real number having 2 to 17 Is shown.)

Since R1 is a hydrogen atom or a methyl group, it means that (c) is a (meth) acrylic compound having a (meth) acryloyl group. N represents the number of repeating alkylene oxide chains.
The adhesive composition containing phenoxyethyl acrylate where n = 1 in formula (1) is hard and the adhesive strength is not sufficient. By setting n to 2 to 6, the alkylene oxide chain becomes longer, the active energy ray-curable adhesive composition becomes soft, and adhesion can be imparted. On the other hand, when n exceeds 6, sufficient adhesion cannot be satisfied. (C) of this invention is mix | blended in the range of 35-45 weight part in 100 weight part of total amounts of a (meth) acrylic-type compound. Even if it is less than 35 parts by weight or exceeds 45 parts by weight, the adhesiveness is lowered.

  In the present invention, the following (meth) acrylic compound (d) can be used in combination with the essential components (a), (b) and (c) as required. For example, n-alkyl (meth) acrylate such as benzyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, isoalkyl (meth) acrylate such as isobutyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, 2-ethylhexyl carbitol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, 2-acryloyloxyethyl Succinic acid, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylic , T-butyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) ) Acrylate, octadecyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, cyclohexyl acrylate, ethoxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, isobornyl (Meth) acrylate, t-octyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, die Ruaminoechiru (meth) acrylate, 7-amino-3,7-dimethyl-octyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, epoxy (meth) acrylate, oxetane (meth) acrylate, acrylamide derivatives. For example, acrylamide derivatives include N, N′-dimethylacrylamide, N, N′-diethylacrylamide, N, N′-dimethylaminoethylacrylamide, N, N′-dimethylaminopropylacrylamide, N-isopropylacrylamide, N, N'-dimethylaminopropyl acrylamide etc. are mentioned

  These (meth) acrylic compounds (d) are preferably 30 parts by weight or less with respect to 100 parts by weight of (meth) acrylate from the viewpoint of adhesiveness and the like.

  The suitable viscosity of the adhesive composition of the present invention is 10 to 5,000 mPa, preferably 30 to 3,000 mPa, more preferably 50 to 1,500 mPa at 23 ° C., and can be adjusted by the adhesive composition.

  In the active energy ray-curable adhesive composition of the present invention, it is preferable to use 2 to 10 parts by weight of a polymerization initiator with respect to 100 parts by weight of the total amount of (meth) acrylic compound. Examples of the polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4- Chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane -1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2- Rollo thioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino - propan-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the like.

  Further, other known additives can be mixed with the active energy ray-curable adhesive. Known additives include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and the like. Polymerization accelerators, photosensitizers, ionic conductive agents, conductive conductivity additives such as conductive metal oxide fine particles, and light diffusibility imparting additives such as light diffusing fine particles having a refractive index different from the refractive index of the adhesive And known solvents for adjusting the viscosity.

The polyvinyl alcohol polarizing film to which the active energy ray-curable adhesive composition of the present invention is applied will be described. It does not specifically limit as a polyvinyl-alcohol-type polarizing film used in the manufacturing method of the polarizing plate of this invention, The conventionally well-known polymer for polarizing films can be used. Specifically, the polyvinyl alcohol resin used for the polyvinyl alcohol polarizing film is usually obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but is not necessarily limited to this in the present invention. , Small amounts of unsaturated carboxylic acids (including salts, esters, amides, nitriles, etc.), olefins having 2 to 30 carbon atoms (ethylene, propylene, n-butene, isobutene, etc.), vinyl ethers, unsaturated sulfonates, etc. Alternatively, a modified polyvinyl alcohol resin containing a component copolymerizable with vinyl acetate may be used. The weight average molecular weight of the polyvinyl alcohol resin is not particularly limited, but is preferably 60,000 to 300,000, more preferably 120,000 to 260,000.
The polyvinyl alcohol polarizing film can be produced by dyeing and adsorbing a dichroic material such as iodine or an organic dye on the polyvinyl alcohol resin film by a known method and uniaxially stretching it.

  On the other hand, the thermoplastic norbornene-based resin film is, for example, (i) a ring-opening polymer or a ring-opening copolymer of a norbornene-based monomer, which is subjected to modification such as maleic acid addition or cyclopentadiene addition as necessary. A hydrogenated resin, (b) a resin obtained by addition polymerization of a norbornene monomer, (c) a resin obtained by addition polymerization of a norbornene monomer and an olefin monomer such as ethylene or α-olefin, and (d) a norbornene monomer. It means a resin obtained by addition polymerization of a cyclic olefin monomer such as cyclopentene, cyclooctene, or 5,6-dihydrodicyclopentadiene, and a film obtained by molding a thermoplastic norbornene resin such as a modified product thereof. Any film formed by a known method such as a casting method or a melt extrusion method may be used. As thermoplastic norbornene resins, the product name “Arton” of JSR and the product name “Zeonor” of Nippon Zeon are well known.

  Moreover, what has phase difference can be used for the thermoplastic norbornene-type resin film bonded together with a polyvinyl-alcohol-type polarizing film. By using the thermoplastic norbornene-based resin film exhibiting the phase difference, the step of further laminating the phase difference film on the polarizing plate is omitted, thereby further reducing the cost and simplifying the step. The method for imparting retardation to the thermoplastic norbornene-based resin film may be a known method, and a uniaxial retardation film obtained by stretching the film in the longitudinal direction or the transverse direction, and stretching the film in the longitudinal direction and the transverse direction. Examples thereof include a stretched film such as a biaxial retardation film and a liquid crystal coating type viewing angle compensation film in which a liquid crystal such as a discotic liquid crystal is tilted and oriented on a thermoplastic norbornene resin film.

Subsequently, the manufacturing method of the polarizing plate using the active energy ray hardening-type adhesive composition of this invention is demonstrated. First, using a commonly used coating apparatus such as a roll coater, bar coater, gravure roll, adhesive supply nozzle on one or both sides of a polyvinyl alcohol polarizing film, the thickness is less than 10 μm, preferably less than 3 μm, and a thickness of 0.5 μm or more. The laminated film polarizing plate of the present invention is cured by applying ultraviolet light at 800 to 3,000 mJ / cm ² and curing the active energy ray-curable adhesive composition. Obtainable.
In addition, the surface of the thermoplastic norbornene-based resin film or the polyvinyl alcohol-based polarizing film is preliminarily used as necessary in order to reinforce the adhesion between the thermoplastic norbornene-based resin film and the polyvinyl alcohol-based polarizing film. The surface can be modified by a known corona treatment, plasma treatment, UV treatment, flame treatment or the like.

Furthermore, the polarizing plate obtained by the present invention includes an antiglare layer, a hard coat layer, an antireflection layer, a low reflection layer, a reflection layer, an antifouling layer, an antifogging layer, a phosphorescent layer, and a light diffusion layer as necessary. Further, one or more functional layers such as an electroluminescence layer can be laminated.
The polarizing plate thus obtained is preferably applied as a polarizing plate to be used on at least one side of a liquid crystal panel, or as a polarizing plate adhered to at least one side of a spectacle lens such as sunglasses or glasses for correcting vision. .

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
Table 1 shows the component compositions (Examples and Comparative Examples) of the active energy ray-curable adhesive composition and the evaluation results.

The composition of the active energy ray-curable adhesive composition is as follows.
<(A) component>
(A-1) Urethane acrylate (bifunctional acrylate)
(A-2) Tris (2-acryloyloxyethyl) isocyanurate (trifunctional acrylate)
(A-3) Isocyanuric acid ethylene oxide-modified diacrylate (bifunctional acrylate)
(A-4) ε-caprolactone-modified tris (2-acryloxyethyl) isocyanurate (trifunctional acrylate)
<(B) component>
(B-1) Hydroxyethyl methacrylate (b-2) 4-hydroxybutyl acrylate (b-3) N-hydroxyethyl acrylamide <(c) component>
(C-1) Phenolethylene oxide modified (n = 4) acrylate <(d) Other (meth) acrylic compound>
(D-1) Phenoxyethyl acrylate (d-2) N, N′-diethylacrylamide (d-3) Oxetane methacrylate (d-4) Lauryl acrylate (d-5) Tetrahydrofurfuryl methacrylate (d-6) Methacrylic acid <Polymerization initiator>
(E-1) 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name “Irgacure 651” manufactured by Ciba Specialty Chemicals)
(E-2) Ethyl-4-dimethylaminobenzoate (trade name “DAROCUR EDB” manufactured by Ciba Specialty Chemicals)

Moreover, it evaluated by the peeling strength represented with the following measuring methods as a parameter which shows the adhesiveness of adhesive composition. In addition, the preparation method of the test piece used for it is as follows.
<Measurement method>
Under 23 ° C, 50% RH environment, using a tensile tester “Autograph AGS-100B” manufactured by Shimadzu Corporation, JIS K6854-4 Adhesive-Peeling adhesive strength test method-Part 4: Conforms to the floating roller method , And measured at a tensile speed of 300 mm / min.
<Specimen>
An active energy ray-curable adhesive comprising 100 parts by weight of the (meth) acrylic monomer shown in Table 1 and 2.5 parts by weight of the polymerization initiator (e-1) and 2.5 parts by weight of (e-2). A composition was prepared. Next, after coating so as to have a coating thickness of 1 μm, pressure is applied with a pinch roll to bond, and a polyvinyl alcohol polarizing film (iodine polarizing film made of polyvinyl alcohol film, thickness 27 μm) / active energy ray-curable adhesive A laminated structure having an agent composition / norbornene-based resin film (manufactured by JSR Corporation, a film made of trade name “ARTON”, thickness 60 μm) was obtained. Next, the active energy ray-curable adhesive composition is irradiated with ultraviolet rays from a norbornene-based resin film side with a metal halide lamp so that the illuminance is 240 mW / cm ² , the integrated light quantity is 1,500 mJ / cm ² , and the irradiation distance is 170 mm. The product was cured to obtain a laminated film polarizing plate. This was cut into a width of 25 mm and used as a test piece for peel strength measurement.

<Discussion>
As is clear from Table 1, the active energy ray-curable adhesive compositions of Examples 1 to 7 exhibited a peel strength exceeding 78 N / m (floating roller method in accordance with JIS K6854), whereas In Comparative Examples 1 to 8 which do not contain (a), (b) or (c) of the invention, the peel strength was not a satisfactory value, and sufficient peel strength was not obtained. Examples 4 to 7 using N-hydroxyethyl (meth) acrylamide as the component (b) have high peel strength, and Example 7 uses N-hydroxyethyl (meth) acrylamide and hydroxyethyl methacrylate in combination. Was found to have higher peel strength than the other examples.

Furthermore, about Comparative Examples 4-6, since there were too many compounding quantities of (a) component of this invention, adhesive composition became hard and sufficient peel strength was not obtained. In addition, Comparative Examples 7 to 8 using phenoxyethyl acrylate having a short polyalkylene oxide chain (phenol ethylene oxide-modified (n = 1) acrylate) instead of the component (c) are satisfactory in peel strength. It was found that the peel strength was not sufficient.
From the comparison of Examples 1-7 and Comparative Examples 9-14, the peel strength varies depending on the blending ratio of the component (a), the component (b), and the component (c) of the present invention. / M peel strength (floating roller method according to JIS K6854) was shown.

  The adhesive composition of the present invention can firmly adhere a thermoplastic norbornene resin film to a polyvinyl alcohol polarizing film, which is currently mainstream, in a short time, and further reduce the thickness of the adhesive layer. Therefore, it is suitable for adhesion of a protective film of a polyvinyl alcohol polarizing film.

Claims (6)

10 to 40 parts by weight of (meth) acrylic compound having 2 or more (meth) acryloyl groups in the molecule (a) in 100 parts by weight of the total amount of (meth) acrylic compounds (b) having hydroxyl groups in the molecule 15 to 45 parts by weight of (meth) acrylic compound having only one polymerizable double bond (c) 35 to 45 parts by weight of (meth) acrylic compound represented by the following general formula [1]

Wherein R1 is a hydrogen atom or a methyl group, R2 is an alkylene group having 2 to 6 carbon atoms, R3 is a phenyl group or an alkylene (alkylene having 1 to 12 carbon atoms) phenyl group, and n is a real number having 2 to 17 Is shown.)
An active energy ray-curable adhesive composition containing: The active energy ray-curable adhesive according to claim 1, wherein the (a) (meth) acrylic compound having two or more (meth) acryloyl groups in the molecule has two or three (meth) acryloyl groups. Agent composition. (B) The (meth) acrylic compound having a hydroxyl group in the molecule and having only one polymerizable double bond is a hydroxyalkyl (meth) acrylate or a hydroxyacrylamide derivative, 2. The active energy ray-curable adhesive composition according to 2. The active energy ray-curable type according to any one of claims 1 to 3, wherein 2 to 10 parts by weight of a polymerization initiator is blended with respect to 100 parts by weight of the total amount of the (meth) acrylic compound. Adhesive composition. A polarizing plate obtained by laminating a polyvinyl alcohol polarizing film and a thermoplastic norbornene resin film with the active energy ray-curable adhesive composition according to claim 1. . 6. The polarizing plate according to claim 5, wherein the peeling strength according to the floating roller method (JIS K6854) is 78 N / m or more.