JP2016170418A - Curable adhesive composition and polarizing plate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable adhesive composition for bonding a polarizing film with a thermoplastic resin film, the curable adhesive composition capable of giving a polarizing plate having good durability, and a polarizing plate having good durability using the above composition.SOLUTION: The curable adhesive composition for bonding a polarizing film with a thermoplastic resin film comprises a radical polymerizable (meth)acrylic compound and a predetermined norbornene-based compound. A polarizing plate using the above curable adhesive composition is also provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a curable adhesive composition for bonding a polarizing film and a thermoplastic resin film, and a polarizing plate using the same.

  A polarizing plate widely used in an image display device typified by a liquid crystal display device usually has a configuration in which a thermoplastic resin film such as a protective film is laminated and bonded to one side or both sides of a polarizing film. An adhesive is usually used for laminating the polarizing film and the thermoplastic resin film, and a radical polymerizable adhesive is conventionally known as an example of the adhesive [for example, JP 2010-286737 A (patent document) 1)].

JP 2010-286737 A

  In addition, an image display device to which a polarizing plate is applied is required to have durability in an environment in which the polarizing plate is placed, and further durability is required for the polarizing plate. Therefore, the present invention provides a curable adhesive composition for adhering a polarizing film and a thermoplastic resin film, which can provide a polarizing plate with good durability, and the curable adhesive composition. An object is to provide a polarizing plate having good durability.

The present invention provides the following curable adhesive composition and polarizing plate.
[1] A curable adhesive composition for bonding a polarizing film and a thermoplastic resin film,
Radical polymerizable (meth) acrylic compound and the following formula (I):

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a H atom or a substituent containing at least one heteroatom selected from an O atom and an N atom. When R ¹ and R ³ are H atoms and R ² and R ⁴ are the substituents, R ² and R ⁴ together with the two C atoms of the norbornene ring to which they are attached A ring structure may be formed.)
And a norbornene-based compound represented by the formula:

[2] At least one of R ¹ , R ² , R ³ and R ⁴ is the substituent,
The curable adhesive composition according to [1], wherein the substituent includes at least one structure selected from the group consisting of —C (═O) —, —OH, and —NH ₂ .

[3] Any one or any two of R ¹ , R ² , R ³ and R ⁴ are the substituents,
The substituent is -C (= O) -O-alkyl, -C (= O) -NH-alkyl, -C (= O) -alkyl, -C (= O) -H, -C (= O ) -OH, -C (= O) -NH 2, -O-C (= O) - alkyl, -OH, -NH _2, - is selected from the group consisting of alkylene -NH ₂ - alkylene -OH, and The curable adhesive composition according to [2], wherein at least one hydrogen atom of the alkyl and alkylene is a group selected from the group consisting of —OH and —NH ₂ .

[4] The radical polymerizable (meth) acrylic compound includes a (meth) acrylamide monomer,
Any one or any two of R ¹ , R ² , R ³ and R ⁴ are the substituents;
It said substituents, -C (= O) -NH- alkyl, -NH _2, and - a group selected from the group consisting of alkylene -NH _2, at least one of the hydrogen atoms of the alkyl and alkylene is - curable adhesive composition according to may be substituted with a group selected from the group consisting of OH and -NH _{2 [2].}

  [5] The curable adhesive composition according to any one of [1] to [4], further including a radical polymerization initiator.

[6] including the polarizing film and a thermoplastic resin film laminated on at least one surface of the polarizing film via an adhesive layer,
The said adhesive bond layer is a polarizing plate which is a hardened | cured material layer of the curable adhesive composition in any one of [1]-[5].

  [7] The thermoplastic resin film may be made of a resin selected from the group consisting of a polyester resin, a polycarbonate resin, a polyolefin resin, a (meth) acrylic resin, and a cellulose ester resin. The polarizing plate as described.

  According to the curable adhesive composition according to the present invention, a polarizing plate having good durability can be provided.

It is a schematic sectional drawing which shows an example of the laminated constitution of the polarizing plate which concerns on this invention. It is a schematic sectional drawing which shows another example of the laminated constitution of the polarizing plate which concerns on this invention.

<Curable adhesive composition>
The curable adhesive composition according to the present invention is a curable adhesive composition for adhering a polarizing film and a thermoplastic resin film such as a protective film, a radically polymerizable (meth) acrylic compound, A norbornene compound represented by the above formula (I) (hereinafter also referred to as “norbornene compound (I)”). Details of R ¹ , R ² , R ³ and R ⁴ will be described later. In a polarizing plate formed by laminating a thermoplastic resin film via an adhesive layer which is a cured layer of a curable adhesive composition on one or both sides of a polarizing film by containing the norbornene compound (I) The adhesion (adhesive force) between the polarizing film and the thermoplastic resin film can be improved, and as a result, the durability of the polarizing plate can be improved. In addition, since the storage elastic modulus at 80 ° C. of the adhesive layer can be increased, the durability of the polarizing plate when it is placed in an environment where high temperature conditions and low temperature conditions are repeated (hereinafter referred to as “cold heat resistance”). It is also called “impact”.).

  The curable adhesive composition according to the present invention may be a thermosetting adhesive composition that is cured by heating, or is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Although it may be an active energy ray-curable adhesive composition, it is preferably an active energy ray-curable adhesive composition, more preferably an ultraviolet curable adhesive composition.

(1) Radical polymerizable (meth) acrylic compound The curable adhesive composition according to the present invention is a curable (polymerizable) compound that cures by causing radical polymerization reaction by irradiation with active energy rays or heating. Or the radically polymerizable (meth) acrylic-type compound which is an oligomer is contained. In this specification, the “radical polymerizable (meth) acrylic compound” refers to a compound having one or more (meth) acryloyl groups in the molecule. The “(meth) acryloyl group” means at least one selected from an acryloyl group and a methacryloyl group. The same applies to “(meth) acryloyloxy group”, “(meth) acryl”, “(meth) acrylate”, and the like. The curable adhesive composition can contain one or more radically polymerizable (meth) acrylic compounds.

  As a radically polymerizable (meth) acrylic compound, at least one (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule, a (meth) acrylamide monomer, and a functional group-containing compound are reacted in two or more types. And a (meth) acryl oligomer having at least two (meth) acryloyl groups in the molecule. The (meth) acryl oligomer is preferably a (meth) acrylate oligomer having at least two (meth) acryloyloxy groups in the molecule.

  As the (meth) acrylate monomer, a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule and a bifunctional (meth) acrylate having two (meth) acryloyloxy groups in the molecule Examples of the monomer include polyfunctional (meth) acrylate monomers having 3 or more (meth) acryloyloxy groups in the molecule.

  An example of a monofunctional (meth) acrylate monomer is an alkyl (meth) acrylate. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i- Examples include butyl (meth) acrylate, t-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. In addition, aralkyl (meth) acrylate such as benzyl (meth) acrylate; (meth) acrylate of terpene alcohol such as isobornyl (meth) acrylate; tetrahydrofurfuryl structure such as tetrahydrofurfuryl (meth) acrylate (meta) ) Acrylate; alkyl groups such as cyclohexyl (meth) acrylate, cyclohexylmethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate (Meth) acrylate having a cycloalkyl group at the site; aminoalkyl (meth) acrylate such as N, N-dimethylaminoethyl (meth) acrylate; 2-phenoxyethyl (meth) (Meth) acrylates having an ether bond at the alkyl moiety such as acrylate, dicyclopentenyloxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate, and phenoxypolyethylene glycol (meth) acrylate are also monofunctional (meth) acrylate monomers Can be used.

  Furthermore, a monofunctional alkyl (meth) acrylate having a hydroxyl group at the alkyl site and a monofunctional alkyl (meth) acrylate having a carboxyl group at the alkyl site can also be used. Specific examples of the monofunctional alkyl (meth) acrylate having a hydroxyl group at the alkyl site include 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2- Hydroxy-3-phenoxypropyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate is included. Specific examples of the monofunctional alkyl (meth) acrylate having a carboxyl group at the alkyl site are 2-carboxyethyl (meth) acrylate, ω-carboxy-polycaprolactone (n≈2) mono (meth) acrylate, 1- [2- (Meth) acryloyloxyethyl] phthalic acid, 1- [2- (meth) acryloyloxyethyl] hexahydrophthalic acid, 1- [2- (meth) acryloyloxyethyl] succinic acid, 4- [2- (meth) Acrylyloxyethyl] trimellitic acid, N- (meth) acryloyloxy-N ′, N′-dicarboxymethyl-p-phenylenediamine.

  Bifunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylate, polyoxyalkylene glycol di (meth) acrylate, halogen-substituted alkylene glycol di (meth) acrylate, aliphatic polyol di (meth) acrylate, hydrogenated Di (meth) acrylate of dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylate of dioxane glycol or dioxane dialkanol, di (meth) acrylate, bisphenol A or bisphenol of alkylene oxide adduct of bisphenol A or bisphenol F Examples thereof include epoxy di (meth) acrylate of F.

  More specific examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, ditri Methylolpropane di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, silicone di (meth) acrylate, di (meth) acrylate of hydroxypivalic acid neopentyl glycol ester, 2,2 -Bis [4- (meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclo Decanedimethanol di (meth) acrylate, 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], hydroxypivalaldehyde and trimethylo Acetal compound with propane [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane], di (meth) acrylate, tris (hydroxyethyl) ) Isocyanurate di (meth) acrylate and the like.

  Trifunctional or higher polyfunctional (meth) acrylate monomers include glycerin tri (meth) acrylate, alkoxylated glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, and ditrimethylol. Propane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. A poly (meth) acrylate of a tri- or higher functional aliphatic polyol; a poly (meth) acrylate of a tri- or higher-functional halogen-substituted polyol; Tri (meth) acrylate of an alkylene oxide adduct; tri (meth) acrylate of an alkylene oxide adduct of trimethylolpropane; 1,1,1-tris [(meth) acryloyloxyethoxyethoxy] propane; tris (hydroxyethyl) And isocyanurate tri (meth) acrylate.

  The (meth) acrylamide monomer is preferably (meth) acrylamide having a substituent at the N-position, and a typical example of the N-position substituent is an alkyl group, but the nitrogen atom of (meth) acrylamide And may form a ring, and this ring may have an oxygen atom as a ring member in addition to the carbon atom and the nitrogen atom of (meth) acrylamide. Further, a substituent such as alkyl or oxo (═O) may be bonded to the carbon atom constituting the ring.

  Specific examples of N-substituted (meth) acrylamide include N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, Ni-propyl (meth) acrylamide, N- N-alkyl (meth) acrylamides such as n-butyl (meth) acrylamide, Ni-butyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N-hexyl (meth) acrylamide; N, N- N, N-dialkyl (meth) acrylamides such as dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide are included. Further, the N-position substituent may be an alkyl group having a hydroxyl group, and examples thereof include N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, and N- (2 -Hydroxypropyl) (meth) acrylamide and the like. Furthermore, as a case where the above-mentioned substituent at the N-position forms a ring, N-substituted (meth) acrylamide which forms a 5-membered ring or a 6-membered ring can be mentioned, and specific examples thereof include N-acryloyl. There are pyrrolidine, 3- (meth) acryloyl-2-oxazolidinone, 4- (meth) acryloylmorpholine, N- (meth) acryloylpiperidine and the like.

  When the thermoplastic resin film is a polyolefin resin film or a (meth) acrylic resin film, the radically polymerizable (meth) acrylic compound contains a (meth) acrylamide monomer in terms of adhesion to the polarizing film. It is desirable to include.

  Examples of the (meth) acryl oligomer having at least two (meth) acryloyl groups in the molecule include urethane (meth) acryl oligomer, polyester (meth) acryl oligomer, and epoxy (meth) acryl oligomer.

  The urethane (meth) acryl oligomer is a compound having a urethane bond (—NHCOO—) and at least two (meth) acryloyl groups in the molecule. Specifically, a urethanization reaction product of a hydroxyl group-containing (meth) acrylic monomer having at least one (meth) acryloyl group and at least one hydroxyl group in the molecule and a polyisocyanate, or a polyol and a polyisocyanate. It may be a urethanation reaction product of a terminal isocyanato group-containing urethane compound obtained by reaction and a (meth) acryl monomer having at least one (meth) acryloyl group and at least one hydroxyl group in the molecule, etc. .

  The hydroxyl group-containing (meth) acrylic monomer used in the urethanization reaction can be, for example, a hydroxyl group-containing (meth) acrylate monomer, and specific examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycerol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, di Contains pentaerythritol penta (meth) acrylate. Specific examples other than the hydroxyl group-containing (meth) acrylate monomer include N-hydroxyalkyl (meth) acrylamide monomers such as N-hydroxyethyl (meth) acrylamide and N-methylol (meth) acrylamide.

  The polyisocyanate used for the urethanation reaction with a hydroxyl group-containing (meth) acrylic monomer includes hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and aromatic diamethylenes among these diisocyanates. Diisocyanates obtained by hydrogenating isocyanates (for example, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, and the above And polyisocyanates obtained by increasing the amount of the diisocyanate.

  Moreover, as a polyol used in order to make a terminal isocyanate group containing urethane compound by reaction with polyisocyanate, it is possible to use polyester polyol, polyether polyol, etc. in addition to aromatic, aliphatic or alicyclic polyols. it can. Aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, ditriol. Examples include methylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The polyester polyol is obtained by a dehydration condensation reaction between the above-described polyol and a polybasic carboxylic acid or an anhydride thereof. Examples of polybasic carboxylic acids or anhydrides thereof can be represented by adding “(anhydrous)” to those that may be anhydrides, and are (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) Itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, hexahydro (anhydrous) phthalic acid, etc.

  The polyether polyol may be a polyoxyalkylene-modified polyol obtained by a reaction of the above-described polyol or dihydroxybenzenes with an alkylene oxide, in addition to the polyalkylene glycol.

  The polyester (meth) acryl oligomer is a compound having an ester bond and at least two (meth) acryloyl groups (typically (meth) acryloyloxy groups) in the molecule. Specifically, it can be obtained by a dehydration condensation reaction using (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Examples of polybasic carboxylic acids or anhydrides thereof used in the dehydration condensation reaction can be represented by adding “(anhydrous)” to those that can be anhydrides. (Anhydrous) succinic acid, adipic acid, (anhydrous) There are maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, hexahydro (anhydrous) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid and the like. Examples of the polyol used for the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, Examples include ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The epoxy (meth) acryl oligomer can be obtained, for example, by an addition reaction between polyglycidyl ether and (meth) acrylic acid, and has at least two (meth) acryloyloxy groups in the molecule. Examples of the polyglycidyl ether used for the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A diglycidyl ether, and the like.

(2) Other curable compounds The curable adhesive composition according to the present invention may contain other radical polymerizable compounds other than the radical polymerizable (meth) acrylic compound and the norbornene compound (I). Examples of other radically polymerizable compounds include vinyl compounds such as styrene, styrene sulfonic acid, vinyl acetate, vinyl propionate, and N-vinyl-2-pyrrolidone, and one ethylenically unsaturated bond in the molecule. The compound which has more than can be mentioned. The curable adhesive composition can contain one or more other radically polymerizable compounds.

  However, from the viewpoint of durability of the polarizing plate formed by laminating a thermoplastic resin film through an adhesive layer that is a cured layer of a curable adhesive composition on one side or both sides of a polarizing film, other radical polymerization The content of the functional compound is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, with respect to 100 parts by weight of the radical polymerizable (meth) acrylic compound, and 10 parts by weight or less. More preferably.

  The curable adhesive composition according to the present invention is a compound or oligomer that cures by causing a cationic polymerization reaction by irradiation with active energy rays or heating in addition to a radical polymerizable compound as a curable (polymerizable) compound. A certain cationic polymerizable compound may be contained. As the cationically polymerizable compound, an epoxy compound having one or more, preferably two or more epoxy groups in the molecule (for example, an alicyclic epoxy compound, an aromatic epoxy compound, a hydrogenated epoxy compound, an aliphatic epoxy compound, etc. ), Oxetane compounds having one or more oxetane rings (oxetanyl group) in the molecule, aliphatic or alicyclic vinyl compounds, cyclic lactone compounds, cyclic acetal compounds, cyclic thioether compounds, spiroorthoester compounds, and the like. it can. The curable adhesive composition can contain one or more cationically polymerizable compounds.

  However, from the viewpoint of durability of the polarizing plate formed by laminating a thermoplastic resin film via an adhesive layer that is a cured product layer of the curable adhesive composition on one side or both sides of the polarizing film, a cationically polymerizable compound The content of is preferably 100 parts by weight or less, more preferably 50 parts by weight or less, still more preferably 30 parts by weight or less, with respect to 100 parts by weight of the radical polymerizable compound. It is particularly preferred that the amount is not more than parts.

(3) Radical polymerization initiator The curable adhesive composition according to the present invention comprises a photo radical polymerization initiator when it is active energy ray curable, and a thermal radical polymerization initiator when it is thermosetting. Can be contained. When it is electron beam curable, a radical photopolymerization initiator is not essential, but when it is ultraviolet curable, the curable adhesive composition according to the present invention contains a radical photopolymerization initiator. It is preferable. In the case of active energy ray curable, particularly in the case of ultraviolet curable, a radical photopolymerization initiator and a thermal radical polymerization initiator may be used in combination. The radical photopolymerization initiator is one that initiates a polymerization reaction of a radical curable compound by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams. The curable adhesive composition can contain one or more radical polymerization initiators.

  Conventionally known photo radical polymerization initiators and thermal radical polymerization initiators can be used. Specific examples of the photo radical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [ Acetophenone-based initiators such as 4- (methylthio) phenyl-2-morpholinopropan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone, 4,4 ′ -Benzophenone initiators such as diaminobenzophenone; Benzoin ether initiators such as benzoinpropyl ether and benzoin ethyl ether; Thioxanthone initiators such as 4-isopropylthioxanthone; Others, xanthone, fluorenone, camphorquinone, benzaldehyde, ant Including a quinone.

  Content of a radical polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of radically polymerizable compounds, Preferably it is 1-6 weight part. By containing 0.5 part by weight or more of the radical polymerization initiator, the radical polymerizable compound can be sufficiently cured, and high mechanical strength and adhesive strength can be imparted to the resulting polarizing plate. On the other hand, if the amount is excessively large, the durability of the polarizing plate may be lowered.

(4) Norbornene compound (I)
The curable adhesive composition according to the present invention has the following formula (I):

The norbornene-type compound (I) represented by these is contained. In the formula (I), R ¹ , R ² , R ³ and R ⁴ are each independently a H atom or a substituent containing at least one heteroatom selected from an O atom and an N atom It is. When all of R ¹ , R ² , R ³ and R ⁴ are H atoms, the norbornene-based compound (I) is 2-norbornene.

In the norbornene-based compound (I), preferably, at least one of R ¹ , R ² , R ³ and R ⁴ is the above substituent, and more preferably, among R ¹ , R ² , R ³ and R ⁴ Any one or any two are the above substituents. In the case where the norbornene-based compound (I) includes at least one of the above-described substituents, each of the substituents may have endo configuration, exo, or a mixture thereof. Also good.

From the viewpoint of durability of the polarizing plate formed by laminating a thermoplastic resin film via an adhesive layer that is a cured product layer of the curable adhesive composition on one or both sides of the polarizing film, the substituent is − It preferably includes at least one structure selected from the group consisting of C (═O) —, —OH, and —NH ₂ . Specific examples of the substituent containing a structure of -C (= O)-[carbonyl group] include -C (= O) -O-alkyl, -C (= O) -NH-alkyl, -C (= O). - alkyl, -C (= O) -H, -C (= O) -OH, -C (= O) -NH 2, -O-C (= O) - alkyl. “Alkyl” in these substituents can be each independently, for example, a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, preferably a linear chain having 1 to 4 carbon atoms. Or a branched alkyl group. At least one hydrogen atom in “alkyl” in the above substituent may be substituted with a group selected from the group consisting of —OH and —NH ₂ .

Further, specific examples of the substituent having a structure of -OH are -OH group and -alkylene-OH which are directly bonded to the norbornene ring. Specific examples of the substituent containing a structure of -NH ₂ is, -NH ₂ groups attached directly to the norbornene ring, - alkylene -NH _2. The “alkylene” in the substituents -alkylene-OH and -alkylene-NH ₂ can each independently be, for example, a linear, branched or cyclic alkylene group having 1 to 8 carbon atoms, preferably It is a C1-C4 linear or branched alkylene group. At least one hydrogen atom in the “alkylene” in the above substituent may be substituted with a group selected from the group consisting of —OH and —NH ₂ .

  Examples of the norbornene-based compound (I) having the above substituent are shown below together with its chemical formula.

[A] Norbornene compound (I) having a substituent —C (═O) —O-alkyl
a-1: methyl 5-norbornene-2-carboxylate,
a-2: t-butyl 5-norbornene-2-carboxylate,
a-3: 5-norbornene-2-carboxylic acid (2-aminoethyl),
a-4: Monomethyl 5-norbornene-2,3-dicarboxylate.

[B] Norbornene compound (I) having a substituent —C (═O) —NH-alkyl
b-1: 5-norbornene- (N-2-hydroxyethyl) -2-carboxamide.

[C] Norbornene compound (I) having a substituent —C (═O) -alkyl
c-1: 5-acetyl-2-norbornene.

[D] Norbornene compound (I) having substituent —C (═O) —H
d-1: 5-norbornene-2-carboxaldehyde.

[E] Norbornene compound (I) having substituent —C (═O) —OH
e-1: 5-norbornene-2-carboxylic acid,
e-2: 5-norbornene-2,3-dicarboxylic acid.

[F] Norbornene compound (I) having substituent —C (═O) —NH ₂
f-1: 5-norbornene-2-carboxamide.

[G] Norbornene compound (I) having a substituent —O—C (═O) -alkyl
g-1: 5-norbornen-2-yl acetate.

[H] Norbornene compound (I) having substituent —OH
h-1: 5-norbornen-2-ol,
h-2: 5-norbornene-2-methanol,
h-3: 5-norbornene-2,2-dimethanol,
h-4: 5-norbornene-2,3-dimethanol (endo, endo form, exo, exo form, etc.).

[I] Norbornene compound (I) having substituent —NH ₂
i-1: 5-amino-2-norbornene,
i-2: 5-norbornene-2-methylamine.

As described above, when R ¹ and R ³ are H atoms and R ² and R ⁴ are the above substituents, R ² and R ⁴ are the two C atoms of the norbornene ring to which they are bonded and Together, they may form a ring structure. Examples of the ring structure include a cyclic imide structure and a cyclic acid anhydride structure. Examples of norbornene compounds (I) having substituents forming a ring structure are shown below together with their chemical formulas.

[J] Norbornene compound (I) having a substituent forming a ring structure
j-1: 5-norbornene-2,3-dicarboximide,
j-2: 5-norbornene-2,3-dicarboxylic anhydride.

The curable adhesive composition according to the present invention may contain one or more norbornene compounds (I). When two or more kinds of norbornene compounds (I) are contained, for example, a compound having the same chemical composition but a substituent having an endo configuration and an exo configuration is used in combination. It is also included when doing. Among these, from the viewpoint of the adhesive strength between the polarizing film and the thermoplastic resin film, and thus the durability of the polarizing plate, -C (= O) -O-alkyl, -C (= O) -NH-alkyl, -alkylene-NH. ₂ , —OH, and —NH ₂ , a norbornene-based compound having a substituent containing at least one (preferably any one or any two) is preferably used, and the compound (a-1), (a -3) and (b-1) are more preferably used, and compounds (a-3) and (b-1) are particularly preferably used.

  From the viewpoint of durability of a polarizing plate formed by laminating a thermoplastic resin film via an adhesive layer which is a cured product layer of a curable adhesive composition on one side or both sides of a polarizing film, a norbornene compound (I) The content of is preferably 0.001 part by weight or more with respect to 100 parts by weight of the total amount of the radical polymerizable (meth) acrylic compound and the norbornene compound (I), and 0.01 part by weight or more. More preferably, it is 0.05 parts by weight or more. The content of the norbornene compound (I) is usually 20 parts by weight or less, preferably 10 parts by weight with respect to 100 parts by weight of the total amount of the radical polymerizable (meth) acrylic compound and the norbornene compound (I). Or less, more preferably 6 parts by weight or less, and even more preferably 5 parts by weight or less.

(5) Additive The curable adhesive composition according to the present invention may contain an additive as necessary. Specific examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a polymerization accelerator, a sensitizer, a sensitizer, a light stabilizer, a tackifier, a thermoplastic resin, a filler, and a flow modifier. , Plasticizers, antifoaming agents, leveling agents, silane coupling agents, dyes, antistatic agents, ultraviolet absorbers, light or thermal cationic polymerization initiators. The light or thermal cationic polymerization initiator is added when a cationic polymerizable compound is used in combination as a curable compound. Examples of the ion trapping agent include powdery bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed inorganic compounds. The antioxidant is a hindered phenol-based antioxidant. Etc.

<Polarizing plate>
The curable adhesive composition according to the present invention is preferably used as an adhesive for adhering a polarizing film constituting a polarizing plate and a thermoplastic resin film such as a protective film laminated thereon. Can do. That is, the polarizing plate according to the present invention includes a polarizing film and a thermoplastic resin film laminated on at least one surface of the polarizing film via an adhesive layer formed from the curable adhesive composition according to the present invention. Is included. The adhesive layer is a cured product layer of the curable adhesive composition according to the present invention. Since the polarizing plate according to the present invention bonds the polarizing film and the thermoplastic resin film using the curable adhesive composition according to the present invention, the polarizing plate and the thermoplastic resin film have good durability (adhesive strength between both films, Shows thermal shock resistance).

(1) Configuration of Polarizing Plate An example of the layer configuration of the polarizing plate according to the present invention is shown in FIGS. As shown in FIG. 1, the polarizing plate according to the present invention includes a polarizing film 30 and a first thermoplastic resin film 10 laminated and bonded to one surface of the polarizing film 30 via a first adhesive layer 15. be able to. As shown in FIG. 2, the polarizing plate according to the present invention includes a polarizing film 30, a first thermoplastic resin film 10 laminated and bonded to one surface of the polarizing film 30 via a first adhesive layer 15, and a polarizing film. The second surface of the film 30 may include the second thermoplastic resin film 20 laminated and bonded via the second adhesive layer 25. When the polarizing plate has the first adhesive layer 15 and the second adhesive layer 25, either one may be formed from the curable adhesive composition according to the present invention, or both adhesive layers. May be formed from the curable adhesive composition according to the present invention, but the latter is preferred from the viewpoint of durability.

  Not only the example of FIG.1 and FIG.2, but the polarizing plate which concerns on this invention can contain other layers (or film) other than the above. If the specific example of another layer is given, for example, an adhesive layer laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20 and / or the polarizing film 30; on the outer surface of the adhesive layer Separate film to be laminated (also referred to as “release film”); protect film (“surface protective film”) laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizing film 30 Also called an optical functional film (or layer) laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20 and / or the polarizing film 30 via an adhesive layer or an adhesive layer. Etc.

(2) Polarizing film The polarizing film 30 is a film having a function of selectively transmitting one direction of linearly polarized light from natural light. For example, an iodine polarizing film in which iodine as a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film, and a dye system in which a dichroic dye as a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film Examples thereof include a polarizing film, and a coating type polarizing film coated with a lyotropic liquid crystal dichroic dye and oriented and fixed. These polarizing films are called absorption polarizing films because they selectively transmit one direction of linearly polarized light from natural light and absorb the other direction of linearly polarized light. The polarizing film 30 is not limited to an absorptive polarizing film, but is a reflective polarizing film that selectively transmits linearly polarized light in one direction from natural light and reflects linearly polarized light in another direction, or linearly polarized light in another direction. However, an absorptive polarizing film is preferable from the viewpoint of excellent visibility. Among them, a polyvinyl alcohol polarizing film composed of a polyvinyl alcohol resin is more preferable, and a polyvinyl alcohol polarizing film obtained by adsorbing and orienting a dichroic dye such as iodine or a dichroic dye on the polyvinyl alcohol resin film is further provided. A polyvinyl alcohol polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol resin film is particularly preferable.

  As the polyvinyl alcohol resin constituting the polyvinyl alcohol polarizing film, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth) acrylamides having ammonium groups, and the like.

  The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol resin is usually about 1000 to 10000, preferably about 1500 to 5000. The average degree of polymerization of the polyvinyl alcohol resin can be determined according to JIS K 6726.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of the polarizing film 30. The method for forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is employed. The thickness of the polyvinyl alcohol-based raw film is, for example, 150 μm or less, preferably 100 μm or less (for example, 50 μm or less).

  The polarizing film 30 is a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; a polyvinyl alcohol on which the dichroic dye is adsorbed The resin film can be produced by a method comprising a step of treating (crosslinking treatment) with a boric acid aqueous solution; and a step of washing with water after the treatment with the boric acid aqueous solution.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a polyvinyl alcohol-based resin film is swollen using a solvent or water. The draw ratio is usually about 3 to 8 times.

  As a method for dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing the dichroic dye is employed. As the dichroic dye, iodine or a dichroic organic dye is used. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

As the dyeing treatment with iodine, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The iodine content in the aqueous solution can be about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide can be about 0.5 to 20 parts by weight per 100 parts by weight of water. Moreover, the temperature of this aqueous solution can be about 20-40 degreeC. On the other hand, as a dyeing treatment with a dichroic organic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic organic dye is usually employed. The aqueous solution containing the dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The content of the dichroic organic dye in this aqueous solution can be about 1 × 10 ⁻⁴ to 10 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution can be about 20 to 80 ° C.

  As boric acid treatment after dyeing with a dichroic dye, a method of immersing a dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution is usually employed. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of boric acid in the boric acid-containing aqueous solution can be about 2 to 15 parts by weight per 100 parts by weight of water. The amount of potassium iodide in this aqueous solution can be about 0.1 to 20 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution can be 50 ° C. or higher, for example, 50 to 85 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. The polarizing film 30 is obtained by performing a drying process after washing with water. The drying process can be performed using a hot air dryer or a far infrared heater. A polarizing plate can be obtained by laminating a thermoplastic resin film as a protective film or the like on one or both surfaces of the polarizing film 30 using a curable adhesive composition or the like.

  Moreover, as another example of the manufacturing method of the polarizing film 30, the method as described in Unexamined-Japanese-Patent No. 2000-338329 and Unexamined-Japanese-Patent No. 2012-159778 is mentioned, for example. In this method, after applying a solution containing a polyvinyl alcohol-based resin on the surface of a base film to provide a resin layer, a laminated film composed of the base film and the resin layer is stretched, and then a dyeing process, a crosslinking process, etc. To form a polarizer layer (polarizing film layer) from the resin layer. This polarizing laminated film consisting of a base film and a polarizer layer has a structure shown in FIG. 1 after peeling a base film from a thermoplastic film as a protective film or the like on the surface of the polarizer layer. It can be set as this polarizing plate. If a thermoplastic resin film is further bonded to the surface of the polarizer layer exposed by peeling off the base film, a polarizing plate having the structure shown in FIG. 2 is obtained.

  The thickness of the polarizing film 30 can be 40 μm or less, and is preferably 30 μm or less (for example, 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less). According to the methods described in JP 2000-338329 A and JP 2012-159778 A, a thin polarizing film 30 can be more easily manufactured. The thickness of the polarizing film 30 is, for example, 20 μm or less, and Is more easily 15 μm or less, and even more preferably 10 μm or less. The thickness of the polarizing film 30 is usually 2 μm or more. Reducing the thickness of the polarizing film 30 is advantageous for reducing the thickness of the polarizing plate and thus the image display device.

(3) Thermoplastic resin film Each of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is a light-transmitting (preferably optically transparent) thermoplastic resin such as a chain polyolefin resin. (Polypropylene resins, etc.), polyolefin resins such as cyclic polyolefin resins (norbornene resins, etc.); cellulose ester resins such as triacetyl cellulose and diacetyl cellulose; polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc. A polyester resin; a polycarbonate resin; a (meth) acrylic resin; or a film made of a mixture or copolymer thereof. Among these, the first thermoplastic resin film 10 and the second thermoplastic resin film 20 are each selected from the group consisting of polyester resins, polycarbonate resins, polyolefin resins, (meth) acrylic resins, and cellulose ester resins. It is preferable to be comprised from resin.

  Each of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be an unstretched film or a uniaxially or biaxially stretched film. Biaxial stretching may be simultaneous biaxial stretching in which stretching is performed simultaneously in two stretching directions, or sequential biaxial stretching in which stretching is performed in a predetermined direction and then stretching in another direction. The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 may be a protective film that plays a role of protecting the polarizing film 30, or a protective film having an optical function such as a retardation film. There can also be. The retardation film is an optical functional film that is used for the purpose of compensation of retardation by a liquid crystal cell that is an image display element. For example, an arbitrary retardation value is given by stretching a film made of the thermoplastic resin (uniaxial stretching or biaxial stretching) or by forming a liquid crystal layer or the like on the thermoplastic resin film. It can be set as a retardation film.

  Examples of the chain polyolefin-based resin include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins.

  Cyclic polyolefin-based resin is a general term for resins containing, as polymerized units, cyclic olefins typically represented by norbornene, tetracyclododecene (also known as dimethanooctahydronaphthalene) or their derivatives. Specific examples of cyclic polyolefin resins include cyclic olefin ring-opening (co) polymers and hydrogenated products thereof, cyclic olefin addition polymers, cyclic olefins and chain olefins such as ethylene and propylene, or vinyl groups. A copolymer with an aromatic compound, a modified (co) polymer obtained by modifying these with an unsaturated carboxylic acid or a derivative thereof, and the like. Among these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.

  Cellulose ester-based resins are resins in which at least some of the hydroxyl groups in cellulose are acetated, and some are esterified and some are esterified with other acids. Good. The cellulose ester resin is preferably an acetyl cellulose resin. Specific examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

  The polyester-based resin is a resin other than the cellulose ester-based resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethyl naphthalate. Among these, polyethylene terephthalate is preferably used from the viewpoint of mechanical properties, solvent resistance, scratch resistance, cost, and the like. Polyethylene terephthalate means a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate, and may contain structural units derived from other copolymerization components.

  Examples of other copolymer components include a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include isophthalic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, 1 , 4-dicarboxycyclohexane and the like. Examples of the diol component include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Two or more dicarboxylic acid components and diol components can be used in combination as required. It is also possible to use a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p-β-hydroxyethoxybenzoic acid together with the dicarboxylic acid component or diol component. As other copolymerization component, a small amount of a dicarboxylic acid component and / or a diol component having an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be used.

  The polycarbonate-based resin is a polyester formed from carbonic acid and glycol or bisphenol. Among these, an aromatic polycarbonate having a diphenylalkane in the molecular chain is preferably used from the viewpoints of heat resistance, weather resistance and acid resistance. As polycarbonate, 2,2-bis (4-hydroxyphenyl) propane (also known as bisphenol A), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1 Illustrative are polycarbonates derived from bisphenols such as -bis (4-hydroxyphenyl) isobutane, 1,1-bis (4-hydroxyphenyl) ethane.

  The (meth) acrylic resin can be a polymer containing methacrylic acid ester as a main monomer (containing 50% by weight or more), and a copolymer in which a small amount of other copolymerization components are copolymerized. A polymer is preferred. The (meth) acrylic resin is more preferably a copolymer of methyl methacrylate and methyl acrylate, and a third monofunctional monomer may be further copolymerized.

  Examples of the third monofunctional monomer include ethyl methacrylate, n-, i- or t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid 2 -Methacrylic acid esters other than methyl methacrylate such as hydroxyethyl; ethyl acrylate, n-, i- or t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, Acrylic esters such as 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 2- (1-hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, 2- (hydroxy Methyl) acrylic acid n-, Hydroxyalkyl acrylates such as-or t-butyl; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; vinyltoluene and α-methylstyrene Substituted styrenes; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; unsaturated imides such as phenylmaleimide and cyclohexylmaleimide Can do. The third monofunctional monomer may be used alone or in combination of two or more.

  A polyfunctional monomer may be further copolymerized with the (meth) acrylic resin. Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and nonaethylene glycol di (meth). Ethylene glycol such as acrylate, tetradecaethylene glycol di (meth) acrylate, or both terminal hydroxyl groups of oligomers thereof esterified with (meth) acrylic acid; both terminal hydroxyl groups of propylene glycol or oligomers thereof (meth) acrylic acid Esterified with dihydric alcohol such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butanediol di (meth) acrylate. Esterified with phosphoric acid; bisphenol A, alkylene oxide adduct of bisphenol A, or those obtained by esterifying both hydroxyl groups of halogen-substituted products with (meth) acrylic acid; such as trimethylolpropane or pentaerythritol Polyhydric alcohol esterified with (meth) acrylic acid, and those obtained by ring-opening addition of glycidyl (meth) acrylate epoxy group to these terminal hydroxyl groups; succinic acid, adipic acid, terephthalic acid, phthalic acid, these Dibasic acids such as halogen substitution products, and those obtained by ring-opening addition of glycidyl (meth) acrylate epoxy groups to these alkylene oxide adducts; aryl (meth) acrylates; aromatic divinyl compounds such as divinylbenzene, etc. Is mentioned. Of these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

  The (meth) acrylic resin may be modified by further reacting between functional groups of the copolymer. As the reaction, for example, demethanol condensation reaction in a polymer chain between a methyl ester group of methyl (meth) acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, a carboxyl group of (meth) acrylic acid and 2 Examples thereof include a dehydration condensation reaction within a polymer chain with a hydroxyl group of methyl (hydroxymethyl) acrylate.

  The glass transition temperature of the (meth) acrylic resin is preferably 80 to 160 ° C. The glass transition temperature is determined by the polymerization ratio between the methacrylic acid ester monomer and the acrylate ester monomer, the carbon chain length of each ester group and the types of functional groups possessed by them, and the polyfunctional single monomer for the whole monomer. It can be controlled by adjusting the polymerization ratio of the monomer.

  It is also effective to introduce a ring structure into the main chain of the polymer as a means for increasing the glass transition temperature of the (meth) acrylic resin. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone structure. Specific examples include cyclic acid anhydride structures such as glutaric anhydride structure and succinic anhydride structure, cyclic imide structures such as glutarimide structure and succinimide structure, and lactone ring structures such as butyrolactone and valerolactone. As the content of the ring structure in the main chain is increased, the glass transition temperature of the (meth) acrylic resin can be increased. The cyclic acid anhydride structure and the cyclic imide structure are introduced by copolymerizing monomers having a cyclic structure such as maleic anhydride and maleimide, and the cyclic acid anhydride structure is formed by dehydration / demethanol condensation reaction after polymerization. It can introduce by the method of introduce | transducing, the method of making an amino compound react, and introduce | transducing a cyclic imide structure. A resin having a lactone ring structure (polymer) is prepared by preparing a polymer having a hydroxyl group and an ester group in a polymer chain, and then heating the hydroxyl group and the ester group in the obtained polymer by heating. Accordingly, it can be obtained by a method in which a lactone ring structure is formed by cyclocondensation in the presence of a catalyst such as an organic phosphorus compound.

  The (meth) acrylic resin may contain an additive as necessary. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, an impact resistance improver, and a surfactant. These additives can be used also when using other thermoplastic resins other than (meth) acrylic-type resin as a thermoplastic resin which comprises a thermoplastic resin film.

  The (meth) acrylic resin may contain acrylic rubber particles that are impact modifiers from the viewpoints of film-formability on the film and impact resistance of the film. Acrylic rubber particles are particles having an elastic polymer mainly composed of an acrylate ester as an essential component. The acrylic rubber particles have a single-layer structure consisting essentially of this elastic polymer, or one elastic polymer. The thing of the multilayered structure used as a layer is mentioned. Examples of this elastic polymer include a cross-linked elastic copolymer obtained by copolymerizing an alkyl acrylate as a main component with another vinyl monomer and a cross-linkable monomer copolymerizable therewith. Examples of the alkyl acrylate as the main component of the elastic polymer include those having an alkyl group with about 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. An alkyl acrylate having an alkyl group having 4 or more carbon atoms is preferably used. Examples of the other vinyl monomer copolymerizable with the alkyl acrylate include a compound having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methyl methacrylate. Methacrylic acid esters such as styrene, aromatic vinyl compounds such as styrene, vinyl cyanide compounds such as acrylonitrile, and the like. Examples of the crosslinkable monomer include a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di (meth) acrylate and butanediol. Examples include (meth) acrylates of polyhydric alcohols such as di (meth) acrylate, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate, and divinylbenzene.

  A laminate of a film made of (meth) acrylic resin not containing rubber particles and a film made of (meth) acrylic resin containing rubber particles can also be used as a protective film. Moreover, the (meth) acrylic-type resin layer is formed in the one or both surfaces of the phase difference expression layer which consists of resin different from (meth) acrylic resin, and the thing in which phase difference was expressed can also be used as a protective film.

  The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 may contain an ultraviolet absorber. When applying a polarizing plate to an image display device such as a liquid crystal display device, a protective film containing an ultraviolet absorber is disposed on the viewing side of the image display element (for example, a liquid crystal cell), thereby deteriorating the image display element due to ultraviolet rays. Can be suppressed. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

  The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be films made of the same thermoplastic resin, or may be films made of different thermoplastic resins. The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be the same or different in thickness, presence / absence of additives, types thereof, retardation characteristics, and the like.

  The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 has a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an electrification on the outer surface (surface opposite to the polarizing film 30). A surface treatment layer (coating layer) such as a prevention layer, an antifouling layer or a conductive layer may be provided.

  The thickness of the 1st thermoplastic resin film 10 and the 2nd thermoplastic resin film 20 is 5-200 micrometers normally, respectively, Preferably it is 10-120 micrometers, More preferably, it is 10-85 micrometers. Reducing the thicknesses of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is advantageous for reducing the thickness of the polarizing plate and thus the image display device.

(4) Manufacture of polarizing plate By laminating and bonding the first thermoplastic resin film 10 to the one surface of the polarizing film 30 via the first adhesive layer 15, the polarizing plate having the configuration shown in FIG. 1 is obtained. The second thermoplastic resin film 20 is further laminated and bonded to the other surface of the polarizing film 30 via the second adhesive layer 25, whereby the polarizing plate having the configuration shown in FIG. 2 can be obtained. When producing a polarizing plate having both the first thermoplastic resin film 10 and the second thermoplastic resin film 20 (hereinafter collectively referred to simply as “thermoplastic resin film”), these thermoplastic resins are used. The film may be laminated and bonded one side at a time, or both thermoplastic resin films may be laminated and bonded simultaneously.

  In the polarizing plate having the configuration shown in FIG. 1, the first adhesive layer 15 is a cured product layer of the curable adhesive composition according to the present invention. In the polarizing plate having the configuration shown in FIG. 2, the first adhesive layer 15 and the second adhesive layer 25 are at least one of the cured product layers of the curable adhesive composition according to the present invention. From the viewpoint of durability, it is preferable that both adhesive layers are cured layers of the curable adhesive composition according to the present invention. In addition, from the viewpoint of durability, in particular, thermal shock resistance, the polarizing plate has an adhesive layer (if the first adhesive layer 15 and the second adhesive layer 25 are provided, at least either one, preferably both The storage elastic modulus of the adhesive layer) at 80 ° C. is preferably 800 MPa or more.

  Specifically, the adhesion between the polarizing film 30 and the thermoplastic resin film is performed by applying an adhesive composition to the bonding surface of the polarizing film 30 and / or the bonding surface of the thermoplastic resin film, and then bonding the adhesive composition. The two films are overlapped via the coating layer of, for example, pressed from above and below using a bonding roll or the like, bonded and then cured by irradiation with active energy rays (active energy ray-curable adhesive composition) Or in the case of a thermosetting adhesive composition). Even when the active energy ray-curable adhesive composition is used, heat treatment may be performed simultaneously with the irradiation with the active energy ray or after the irradiation with the active energy ray. Before forming the coating layer of the adhesive composition, saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment is performed on one or both of the polarizing film 30 and the bonding surface of the thermoplastic resin film. Further, easy adhesion treatment such as anchor coating treatment may be performed.

  For forming the coating layer of the adhesive composition, for example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, the system which casts an adhesive composition in the meantime can also be employ | adopted, supplying continuously the polarizing film 30 and a thermoplastic resin film so that both bonding surfaces may become inside.

  From the viewpoint of coatability, the curable adhesive composition according to the present invention preferably has a low viscosity. Specifically, the viscosity at 25 ° C. is preferably 1000 mPa · s or less, more preferably 500 mPa · s or less, and still more preferably 100 mPa · s or less. Although the curable adhesive composition according to the present invention can be a solventless type, an organic solvent may be contained in order to adjust the viscosity to be suitable for the applied coating method.

  In the step of forming the coating layer of the adhesive composition or the step of laminating the polarizing film 30 and the thermoplastic resin film, at least one of the thermoplastic resin film and the adhesive composition is heated. Also good. Thereby, the adhesiveness of the polarizing film 30 and a thermoplastic resin film, especially the adhesiveness of a thermoplastic resin film and an adhesive bond layer improves. Specific examples of heating include heating of a thermoplastic resin film, heating of an adhesive composition, heating of a laminate in which a polarizing film 30 and a thermoplastic resin film are laminated via an uncured adhesive layer, and the like. There is. Examples of the method for heating the thermoplastic resin film and the laminate include, for example, a method in which a long thermoplastic resin film or laminate is sequentially passed through a device that emits radiant heat such as an infrared heater, a long thermoplastic resin film, The method etc. which spray the gas heated using the air blower etc. to the laminated body can be mentioned. Examples of the method of heating the adhesive composition include a method of heating and keeping the adhesive composition in a storage tank in advance and supplying the heated adhesive composition to the coating apparatus. it can. The temperature for heating the thermoplastic resin film, the adhesive composition or the laminate is preferably 30 to 80 ° C, and more preferably 40 to 60 ° C. If the heating temperature exceeds 80 ° C, the thermoplastic resin film, the adhesive composition or the laminate may be deteriorated by heat. Moreover, it exists in the tendency for the adhesive improvement effect of a thermoplastic resin film and the polarizing film 30 to become inadequate that heating temperature is less than 30 degreeC.

  The light source of the active energy ray may be any light source that generates ultraviolet rays, electron beams, X-rays, and the like, for example. The active energy ray is preferably ultraviolet rays. As the ultraviolet light source, a light source having a light emission distribution at a wavelength of 400 nm or less is preferable. be able to.

Although the active energy ray irradiation intensity | strength to an adhesive bond layer is determined for every adhesive composition, the light irradiation intensity | strength of the wavelength range effective for activation of a photoinitiator will be 0.1-1000 mW / cm < ² >. It is preferable to do so. If the light irradiation intensity is too low, the reaction time becomes too long. On the other hand, if the light irradiation intensity is too high, the yellowing of the adhesive layer occurs due to heat radiated from the lamp and heat generated during polymerization of the adhesive composition. Or deterioration of the polarizing film 30, or skin failure of the thermoplastic resin film may occur. Moreover, although the light irradiation time to an adhesive bond layer is also controlled for every adhesive composition, it sets so that the integrated light quantity represented as a product of light irradiation intensity and light irradiation time may be 10-5000 mJ / cm < ² >. It is preferred that If the integrated light quantity is too small, active species derived from the photopolymerization initiator may not be sufficiently generated, and the resulting adhesive layer may be insufficiently cured. Irradiation time becomes very long and tends to be disadvantageous for productivity improvement.

  When the polarizing plate having the configuration shown in FIG. 2 is manufactured, the timing for laminating the thermoplastic resin film on the polarizing film 30 via the coating layer of the adhesive composition and the timing for curing the coating layer are not particularly limited. . For example, after laminating one thermoplastic resin film, the coating layer can be subsequently cured, and then the other thermoplastic resin film can be laminated and the coating layer can be cured. Or after laminating | stacking both the thermoplastic resin films sequentially or simultaneously, you may harden the coating layer of both surfaces simultaneously. Moreover, you may perform irradiation of an active energy ray from which thermoplastic resin film side. For example, when one thermoplastic resin film contains a UV absorber and the other thermoplastic resin film does not contain a UV absorber, active energy rays are irradiated from the side of the thermoplastic resin film that does not contain a UV absorber. It is preferable to do. By irradiating in this way, it is possible to effectively use the irradiated active energy rays and increase the curing rate.

  The active energy ray may be irradiated while applying tension to a laminate in which the polarizing film 30 and the thermoplastic resin film are laminated via an uncured adhesive layer and holding the film in a roll. Moreover, in order to improve the reactivity of an adhesive composition, you may heat a polarizing plate simultaneously with active energy ray irradiation, or after active energy ray irradiation. Although there is no restriction | limiting in particular in heating temperature, Usually, it is below the glass transition temperature of a thermoplastic resin film.

  The thicknesses of the first and second adhesive layers 15 and 25 after curing are usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 3 μm or less. When the thickness of the 1st and 2nd adhesive bond layers 15 and 25 is too large, the reaction rate of an adhesive composition falls and it exists in the tendency for the heat-and-moisture resistance of a polarizing plate to deteriorate. The thickness of the 1st and 2nd adhesive bond layers 15 and 25 is 0.01 micrometer or more normally, Preferably it is 0.1 micrometer or more. The thickness of the first adhesive layer 15 and the second adhesive layer 25 may be the same or different.

(5) Other components of polarizing plate (5-1) Optical functional film The polarizing plate can be provided with an optical functional film other than the polarizing film 30 for imparting a desired optical function, A suitable example thereof is a retardation film. As described above, the first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 can also serve as a retardation film, but a retardation film can be laminated separately from the thermoplastic resin film. . In the latter case, the retardation film can be laminated on the outer surface of the first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 via an adhesive layer or an adhesive layer. Further, a retardation film can be laminated instead of the thermoplastic resin film. If the specific example is given, for example, the retardation film will be formed on the other surface of the polarizing film 30 in the one-side protective polarizing plate in which the first thermoplastic resin film 10 is bonded to one surface of the polarizing film 30 shown in FIG. It is the structure which bonded. In this case, the retardation film can be laminated on the surface of the polarizing film 30 via an adhesive layer or an adhesive layer.

  Specific examples of the retardation film include a birefringent film composed of a stretched thermoplastic resin film, a film in which a discotic liquid crystal or nematic liquid crystal is oriented and fixed, and the liquid crystal layer on the base film. Including those formed. The base film is usually a film made of a thermoplastic resin, and a cellulose ester resin such as triacetyl cellulose is preferably used as the thermoplastic resin.

  As the thermoplastic resin forming the birefringent film, those described for the first and second thermoplastic resin films 10 and 20 can be used. For example, when using a cellulose ester resin as an example, a method of forming a film from a cellulose ester resin containing a compound having a retardation adjusting function, a retardation on the surface of a cellulose ester resin film A birefringent film can be obtained by a method of applying a compound having an adjusting function and a method of stretching a cellulose ester resin uniaxially or biaxially. As the thermoplastic resin forming the birefringent film, other thermoplastic resins such as polyvinyl alcohol resin, polystyrene resin, polyarylate resin, and polyamide resin can also be used.

Two or more retardation films may be used in combination for the purpose of controlling optical characteristics such as broadening the band. Moreover, not only the film which has optical anisotropy but a substantially optically isotropic zero retardation film can also be used as a retardation film. The zero Letters retardation film in-plane retardation value R _e and the thickness direction retardation R _th means a film are both -15～15Nm. Here plane retardation value refers R _e and the thickness direction retardation R _th is a value at a wavelength of 590 nm.

The in-plane retardation value _Re and the thickness direction retardation value R _th are respectively expressed by the following formulas:
_{R e = (n x -n y} ) × d
R _th = [(n _x + _ny ) / 2−n _z ] × d
Defined by Wherein, n _x is a refractive index in a slow axis direction (x-axis direction) in the film plane, n _y is the fast axis direction in the film plane of the (y-axis direction orthogonal to the x-axis in a plane) It is a refractive index, _nz is the refractive index in the film thickness direction (z-axis direction perpendicular to the film surface), and d is the thickness of the film.

  As the zero retardation film, the thermoplastic resins described for the first and second thermoplastic resin films 10 and 20 and the birefringent film can be used. For example, cellulose ester resins, chain polyolefin resins, and cyclic resins can be used. A thermoplastic resin film made of a polyolefin resin such as a polyolefin resin or a polyester resin such as polyethylene terephthalate can be used. Among these, cellulose ester resins and polyolefin resins are preferably used because the retardation value is easily controlled and easily available.

  Examples of other optical functional films (optical members) that can be included in the polarizing plate include a light collector, a brightness enhancement film, a reflective layer (reflective film), a semi-transmissive reflective layer (semi-transmissive reflective film), and a light diffusion layer (light Diffusion film). These are generally provided when the polarizing plate is a polarizing plate disposed on the back side (backlight side) of the liquid crystal cell.

  The light collector is used for the purpose of optical path control and can be a prism array sheet, a lens array sheet, a dot-attached sheet, or the like.

  The brightness enhancement film is used for the purpose of improving the brightness in a liquid crystal display device to which a polarizing plate is applied. Specifically, a reflective polarized light separation sheet, an alignment film of a cholesteric liquid crystal polymer, and an alignment film that are designed so that anisotropy occurs in the reflectance by laminating a plurality of thin film films having different refractive index anisotropies Examples include a circularly polarized light separating sheet that supports a liquid crystal layer on a base film.

  The reflective layer, the semi-transmissive reflective layer, and the light diffusing layer are provided to make the polarizing plate into a reflective, semi-transmissive, and diffusing optical member, respectively. The reflective polarizing plate is used in a liquid crystal display device of a type that reflects and displays incident light from the viewing side. Since a light source such as a backlight can be omitted, the liquid crystal display device can be easily thinned. The transflective polarizing plate is used in a liquid crystal display device of a type that displays with a light from a backlight in a dark place as a reflection type in a bright place. The diffusion type polarizing plate is used for a liquid crystal display device that imparts light diffusibility and suppresses display defects such as moire. The reflective layer, transflective layer, and light diffusion layer can be formed by a known method.

(5-2) Adhesive layer The polarizing plate which concerns on this invention can contain the adhesive layer for bonding this to image display elements, such as a liquid crystal cell, or another optical member. The pressure-sensitive adhesive layer is the outer surface of the polarizing film 30 in the polarizing plate having the configuration shown in FIG. 1, and the outer surface of the first thermoplastic resin film 10 or the second thermoplastic resin film 20 in the polarizing plate having the configuration shown in FIG. Can be laminated.

  As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer, those having a base polymer of (meth) acrylic resin, silicone-based resin, polyester-based resin, polyurethane-based resin, polyether-based resin, or the like can be used. Among these, a (meth) acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, weather resistance, heat resistance, reworkability, and the like. The (meth) acrylic pressure-sensitive adhesive includes a (meth) acrylic acid alkyl ester having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, an n-, i- or t-butyl group, and (meth) Weight average molecular weight, blended with a functional group-containing (meth) acrylic monomer such as acrylic acid or hydroxyethyl (meth) acrylate so that the glass transition temperature is preferably 25 ° C. or lower, more preferably 0 ° C. or lower. A (meth) acrylic resin having a molecular weight of 100,000 or more is useful as a base polymer.

  The pressure-sensitive adhesive layer is formed on the polarizing plate by, for example, dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a 10 to 40% by weight solution, which is the target surface of the polarizing plate. A method of forming a pressure-sensitive adhesive layer by coating directly on the surface, or a method of forming a pressure-sensitive adhesive layer in the form of a sheet on a release film and transferring it to the target surface of a polarizing plate Etc. Although the thickness of an adhesive layer is determined according to the adhesive force etc., the range of about 1-50 micrometers is suitable, Preferably it is 2-40 micrometers.

  A polarizing plate may contain said separate film. The separate film can be a film made of a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, or a polyester resin such as polyethylene terephthalate. Among these, a stretched film of polyethylene terephthalate is preferable.

  If necessary, the adhesive layer contains glass fiber, glass beads, resin beads, fillers made of metal powder or other inorganic powders, pigments, colorants, antioxidants, UV absorbers, antistatic agents, etc. May be.

Examples of the antistatic agent include ionic compounds, conductive fine particles, and conductive polymers, and ionic compounds are preferably used. The cation component constituting the ionic compound may be an inorganic cation or an organic cation. Examples of the organic cation include pyridinium cation, imidazolium cation, ammonium cation, sulfonium cation, phosphonium cation, piperidinium cation, and pyrrolidinium cation. Examples of the inorganic cation include lithium ion and potassium ion. On the other hand, the anionic component constituting the ionic compound may be an inorganic anion or an organic anion, but an anionic component containing a fluorine atom is preferable because it gives an ionic compound having excellent antistatic performance. As an anion component containing a fluorine atom, hexafluorophosphate anion [(PF ₆ ⁻ )], bis (trifluoromethanesulfonyl) imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ] anion, bis (fluorosulfonyl) imide anion [ (FSO ₂ ) ₂ N ⁻ ] anion and the like.

(5-3) Protective Film The polarizing plate according to the present invention can include a protective film for temporarily protecting the surface (typically the surface of the thermoplastic resin film). For example, after a polarizing plate is bonded to an image display element or another optical member, the protective film is peeled and removed together with the pressure-sensitive adhesive layer that the protective film has.

  The protective film is composed of a base film and an adhesive layer laminated thereon. The above description is cited for the pressure-sensitive adhesive layer. The resin constituting the base film is, for example, a thermoplastic resin such as a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, or a polycarbonate resin. be able to. Polyester resins such as polyethylene terephthalate are preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

(Production Example 1: Production of protective film)
The pellet-shaped resin [A] and the pellet-shaped resin [B] were introduced into an extruder at a weight ratio of 75:25 to obtain a (meth) acrylic resin composition. The obtained composition was melt-kneaded by heating to obtain a liquid melt-kneaded product. The obtained melt-kneaded product was solidified using a cooling roll while continuously extruding it from a T-die into a film, thereby producing a long (meth) acrylic resin film having a thickness of 120 μm.

[A] Methyl methacrylate-based resin “ALTUGLAS HT121” manufactured by ARKEMA (glass transition temperature Tg: 124 ° C., weight average molecular weight Mw: 78200, number average molecular weight Mn: 41200, molecular weight dispersion Mw / Mn: 1.9),
[B] Methyl methacrylate resin (glass transition temperature Tg: 110 ° C., weight average molecular weight Mw: 162000, number average molecular weight Mn: 84500, molecular weight dispersion Mw / Mn: 1.9).

  The obtained (meth) acrylic resin film was subjected to a longitudinal stretching treatment, and then subjected to a transverse stretching treatment (sequential biaxial stretching treatment) to obtain a stretched protective film having a thickness of 40 μm. The stretching temperature is the glass transition temperature of the (meth) acrylic resin film + 10 ° C. for both the longitudinal stretching and the lateral stretching, and the stretching ratio of the longitudinal stretching and the lateral stretching is 2 for the (meth) acrylic resin film, respectively. .2 times and 2.0 times.

<Examples 1-3, Comparative Example 1>
(1) Preparation of curable adhesive composition Each of the components shown in Table 1 was mixed in parts by weight shown in Table 1 to prepare a curable adhesive composition. Details of the components shown in Table 1 are as follows. The “radically polymerizable (meth) acrylic compound” described in Table 1 is a mixture of “DMAA”, “DCPA”, “A-DPH” and “UV3700B” described below, and the mixing ratio is It is DMAA / DCPA / A-DPH / UV3700B = 65/14/1/20 by weight ratio.

DMAA: N, N-dimethylacrylamide (obtained from KJ Chemicals),
DCPA: Dicyclopentanyl acrylate (obtained from Hitachi Chemical Co., Ltd.)
A-DPH: Dipentaerythritol hexaacrylate (obtained from Shin-Nakamura Chemical Co., Ltd.)
UV3700B: bifunctional urethane acrylate (obtained from Nippon Synthetic Chemical Industry Co., Ltd.)
Photo radical polymerization initiator: 2-hydroxy-2-methyl-1-phenyl-propan-1-one ("DAROCUR 1173" obtained from BASF Japan Ltd.),
Norbornene compound (I): methyl 5-norbornene-2-carboxylate (obtained from Tokyo Chemical Industry Co., Ltd.).

(2) Measurement of storage elastic modulus at 80 ° C. of cured product of curable adhesive composition On one side of a cyclic polyolefin resin film having a thickness of 50 μm, a coating machine [Bar Coater, manufactured by Daiichi Rika Co., Ltd.] was used. Then, the curable adhesive composition was applied so that the film thickness after curing was about 30 μm, and a cyclic polyolefin resin film having a thickness of 50 μm was further laminated thereon. Next, from one cyclic polyolefin resin film side, UV light is irradiated with a “D bulb” manufactured by Fusion UV Systems Co., Ltd. so that the integrated light quantity is 3000 mJ / cm ^2, and the curable adhesive composition is cured. It was. This was cut into a size of 5 mm × 30 mm, and the cyclic polyolefin resin film was peeled off to obtain a cured film of the curable adhesive composition. The cured film thus obtained was gripped with a gripping tool spacing of 2 cm using a dynamic viscoelasticity measuring device “DVA-220” manufactured by IT Measurement Control Co., Ltd. so that its long side is in the tension direction. The storage elastic modulus at a temperature of 80 ° C. was determined by setting the shrinkage frequency to 10 Hz and the temperature rising rate to 3 ° C./min. The results are shown in Table 1. The higher the storage elastic modulus at a temperature of 80 ° C., the better. The higher the value, the more likely it is to suppress the cracking of the polarizing film during the thermal shock test.

(3) Production of polarizing plate The surface of the protective film produced in Production Example 1 is subjected to corona discharge treatment, and the curable adhesive composition prepared in (1) above is applied to the corona discharge treatment surface using a bar coater. Coating was performed so that the film thickness after curing was about 2.5 μm. A polyvinyl alcohol-iodine polarizing film having a thickness of 25 μm was bonded to the coated surface. Next, a corona discharge treatment was applied to the surface of a retardation film [trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.] having a thickness of 50 μm made of a cyclic polyolefin-based resin, and the corona discharge treatment surface was prepared according to (1) above. The cured curable adhesive composition (same as the adhesive for bonding the protective film) was applied using a bar coater so that the film thickness after curing was about 2.5 μm. On the coated surface, the polarizing film with the protective film obtained above was bonded on the polarizing film side to obtain a laminate. From the protective film side of this laminate, ultraviolet light is irradiated using an ultraviolet irradiation device with a belt conveyor (the lamp uses “D bulb” manufactured by Fusion UV Systems) so that the integrated light quantity is 250 mJ / cm ² (UVB). Then, the curable adhesive composition was cured to produce a polarizing plate.

(4) Evaluation of peel strength (adhesion strength) The surface of the protective film made of (meth) acrylic resin in the obtained polarizing plate is subjected to corona discharge treatment, and then the (meth) acrylic pressure-sensitive adhesive is applied to the corona discharge treated surface. The sheet was bonded to obtain a polarizing plate with an adhesive layer. A test piece having a width of 25 mm and a length of about 200 mm was cut from the obtained polarizing plate with the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer surface was bonded to soda glass. Next, a cutter blade is inserted between the polarizing film and the protective film, and 30 mm is peeled from the end in the length direction, and the peeled portion is removed from a universal tensile tester [“AG-1” manufactured by Shimadzu Corporation]. I grabbed at the grip. The test piece in this state was subjected to JIS K 6854-2: 1999 “Adhesive—Peeling adhesive strength test method—Part 2: 180 degree peeling” in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%. Then, a 180 degree peeling test was performed at a gripping moving speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripping portion was obtained. The results are shown in Table 1.

<Examples 4 to 13, Comparative Example 2>
(5) Preparation of curable adhesive composition Each of the components shown in Table 2 or Table 3 was mixed in parts by weight shown in Table 2 or Table 3 to prepare a curable adhesive composition. Details of the components shown in Tables 2 and 3 are as follows. “Radically polymerizable (meth) acrylic compound (I)” described in Table 2 is a mixture of “DMAA”, “DCPA”, “A-DPH” and “UV3700B” described below, and the mixture The ratio is DMAA / DCPA / A-DPH / UV3700B = 65/14/1/20 in weight ratio, and the “radical polymerizable (meth) acrylic compound (II)” described in Table 3 is the following: It is "HEAA" of description.

DMAA: N, N-dimethylacrylamide (obtained from KJ Chemicals),
DCPA: Dicyclopentanyl acrylate (obtained from Hitachi Chemical Co., Ltd.)
A-DPH: Dipentaerythritol hexaacrylate (obtained from Shin-Nakamura Chemical Co., Ltd.)
UV3700B: bifunctional urethane acrylate (obtained from Nippon Synthetic Chemical Industry Co., Ltd.)
HEAA: N- (2-hydroxyethyl) acrylamide (obtained from KJ Chemicals),
Photo radical polymerization initiator: 2-hydroxy-2-methyl-1-phenyl-propan-1-one ("DAROCUR 1173" obtained from BASF Japan Ltd.),
Norbornene compound (I): methyl 5-norbornene-2-carboxylate (obtained from Tokyo Chemical Industry Co., Ltd.)
Norbornene compound (II): 5-norbornene- (N-2-hydroxyethyl) -2-carboxamide (obtained from ENAMINE),
Norbornene compound (III): 5-norbornene-2-methanamine (isomer mixture) (obtained from Tokyo Chemical Industry Co., Ltd.).

(6) Measurement of storage elastic modulus at 80 ° C. of cured product of curable adhesive composition For curable adhesive compositions obtained in Examples 4 to 6, the cured product was obtained in the same manner as (1) above. The storage elastic modulus at 80 ° C. was measured. The results are shown in Table 2.

(7) Preparation of polarizing plate (Examples 4 to 6)
The surface of the protective film produced in Production Example 1 is subjected to corona discharge treatment, and the corona discharge treatment surface has a film thickness after curing the curable adhesive composition prepared in (5) above using a bar coater. Coating was carried out to 2.5 μm. A polyvinyl alcohol-iodine polarizing film having a thickness of 25 μm was bonded to the coated surface. Next, the surface of a retardation film (trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.) having a thickness of 50 μm made of a cyclic polyolefin resin is subjected to corona discharge treatment, and the corona discharge treatment surface is prepared according to (5) above. The cured curable adhesive composition (same as the adhesive for bonding the protective film) was applied using a bar coater so that the film thickness after curing was about 2.5 μm. On the coated surface, the polarizing film with the protective film obtained above was bonded on the polarizing film side to obtain a laminate. From the protective film side of this laminate, ultraviolet light is irradiated using an ultraviolet irradiation device with a belt conveyor (the lamp uses “D bulb” manufactured by Fusion UV Systems) so that the integrated light quantity is 250 mJ / cm ² (UVB). Then, the curable adhesive composition was cured to produce a polarizing plate.

(8) Preparation of polarizing plate (Examples 7 to 13, Comparative Example 2)
The surface of a phase difference film [trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.] made of a cyclic polyolefin-based resin is subjected to corona treatment, and the curability prepared in (5) above is applied to the corona discharge treatment surface. The adhesive composition was applied using a bar coater so that the film thickness after curing was about 2.5 μm. A polyvinyl alcohol-iodine polarizing film having a thickness of 25 μm was bonded to the coated surface. Next, the surface of a protective film made of cellulose ester resin having a thickness of 80 μm [trade name “Konicatak KC8UX2MW”, manufactured by Konica Minolta Opto Co., Ltd.] is subjected to corona discharge treatment, and the corona discharge treatment surface is subjected to the above (5). The curable adhesive composition prepared in (1) was applied using a bar coater so that the film thickness after curing was about 2.5 μm. On the coated surface, the polarizing film with the retardation film obtained above was bonded on the polarizing film side to obtain a laminate. From the phase difference film side of this laminate, ultraviolet rays are applied so that the integrated light quantity becomes 250 mJ / cm ² (UVB) using an ultraviolet irradiation device with a belt conveyor (the lamp uses “D bulb” manufactured by Fusion UV Systems). Irradiated to cure the curable adhesive composition to produce a polarizing plate.

(9) Evaluation of peel force (adhesion force) (Examples 4 to 6)
The protective film surface made of (meth) acrylic resin in the obtained polarizing plate is subjected to corona discharge treatment, and then a (meth) acrylic pressure-sensitive adhesive sheet is bonded to the corona discharge-treated surface to provide a pressure-sensitive adhesive layer. A polarizing plate was used. A test piece having a width of 25 mm and a length of about 200 mm was cut from the obtained polarizing plate with the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer surface was bonded to soda glass. This sample was stored for 24 hours in an environment of 80 ° C. and 90% relative humidity, and then stored overnight in an environment of 23 ° C. and 55% relative humidity. Next, a cutter blade is inserted between the polarizing film and the protective film, and 30 mm is peeled from the end in the length direction, and the peeled portion is removed from a universal tensile tester [“AG-1” manufactured by Shimadzu Corporation]. I grabbed at the grip. The test piece in this state was subjected to JIS K 6854-2: 1999 “Adhesive—Peeling adhesive strength test method—Part 2: 180 degree peeling” in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%. Then, a 180 degree peeling test was performed at a gripping moving speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripping portion was obtained. The results are shown in Table 2. The higher the peel strength after storage in an environment with a temperature of 80 ° C and a relative humidity of 90%, the better. The higher the value, the higher the float or peel between the polarizing film and the thermoplastic resin film during the endurance test in a humid heat environment. It tends to be able to suppress.

(10) Evaluation of peeling force (adhesion force) (Examples 7 to 13, Comparative Example 2)
The surface of the retardation film in the obtained polarizing plate was subjected to corona discharge treatment, and then a (meth) acrylic pressure-sensitive adhesive sheet was bonded to the corona discharge-treated surface to obtain a polarizing plate with a pressure-sensitive adhesive layer. A test piece having a width of 25 mm and a length of about 200 mm was cut from the obtained polarizing plate with the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer surface was bonded to soda glass. This sample was stored for 24 hours in an environment of 80 ° C. and 90% relative humidity, and then stored overnight in an environment of 23 ° C. and 55% relative humidity. Next, a cutter blade is inserted between the polarizing film and the retardation film, and the film is peeled off 30 mm from the end in the length direction. The peeled portion is a universal tensile tester [“AG-1” manufactured by Shimadzu Corporation]. I grabbed at the grip part. The test piece in this state was subjected to JIS K 6854-2: 1999 “Adhesive—Peeling adhesive strength test method—Part 2: 180 degree peeling” in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%. Then, a 180 degree peeling test was performed at a gripping moving speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripping portion was obtained. The results are shown in Table 3. The higher the peel strength after storage in an environment with a temperature of 80 ° C and a relative humidity of 90%, the better. The higher the value, the higher the float or peel between the polarizing film and the thermoplastic resin film during the endurance test in a humid heat environment. There is a tendency to be able to suppress.

  DESCRIPTION OF SYMBOLS 10 1st thermoplastic resin film, 15 1st adhesive bond layer, 20 2nd thermoplastic resin film, 25 2nd adhesive bond layer, 30 Polarizing film.

Claims (5)

A curable adhesive composition for bonding a polarizing film and a thermoplastic resin film,
Radical polymerizable (meth) acrylic compound and the following formula (I):

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a H atom or a substituent containing at least one heteroatom selected from an O atom and an N atom. When R ¹ and R ³ are H atoms and R ² and R ⁴ are the substituents, R ² and R ⁴ together with the two C atoms of the norbornene ring to which they are attached A ring structure may be formed.)
And a norbornene-based compound represented by the formula: At least one of R ¹ , R ² , R ³ and R ⁴ is the substituent,
The curable adhesive composition according to claim 1, wherein the substituent includes at least one structure selected from the group consisting of —C (═O) —, —OH, and —NH ₂ .   The curable adhesive composition according to claim 1 or 2, further comprising a radical polymerization initiator. Including the polarizing film and a thermoplastic resin film laminated on at least one surface of the polarizing film via an adhesive layer;
The said adhesive bond layer is a polarizing plate which is a hardened | cured material layer of the curable adhesive composition of any one of Claims 1-3.   The polarized light according to claim 4, wherein the thermoplastic resin film is composed of a resin selected from the group consisting of a polyester resin, a polycarbonate resin, a polyolefin resin, a (meth) acrylic resin, and a cellulose ester resin. Board.

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