JP2010107951A - Polarizing plate and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate which has a transparent protective film, has a small birefringence and, even when stress is applied, hardly changes the birefringence. <P>SOLUTION: The polarizing plate has such a structure that at least one surface of a polarizer is directly protected by a protective film made of a resin without allowing other layer to intervene between the polarizing plate and the protective film, wherein the resin is a cured material of an active energy ray curable resin composition which contains a compound (A) having at least two unsaturated carboxylic acyl groups and crosslinked alicyclic skeleton and a compound (B) having at least two unsaturated carboxylic acyl groups and chain-like saturated aliphatic hydrocarbon skeleton, and contents of the compound (A) and the compound (B) in the active energy ray curable resin composition are respectively 30 to 98 wt.% and 1 to 40 wt.% based on the whole of active energy ray curable compounds in the active energy ray curable resin composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate used for a liquid crystal display device and the like and a method for producing the same.

  The polarizing plate is used as a polarized light supplying element and a polarized light detecting element in a liquid crystal display device. Conventionally, as a polarizing plate, a film in which a protective film made of triacetyl cellulose (TAC) is bonded to at least one surface of a polarizer made of a stretched polyvinyl alcohol (PVA) film doped with iodine or the like has been used. . In this case, if birefringence is present in the protective film itself, the function as a polarizing plate is greatly reduced. To prevent this, a TAC film without optical anisotropy prepared by a solvent casting method is used. .

  In such a conventional polarizing plate, since the PVA film is stretched at a high magnification, a large stress is generated in a relaxing direction. The protective film needs to be rigid enough to withstand this stress, but when TAC is used as a protective film, the shrinkage stress of the polarizer at the periphery of the film is superior to that of TAC in large screen applications such as liquid crystal TVs. As a result, deformation occurs, and color loss may occur due to the birefringence of the TAC protective film.

  JP-A-2005-92112 proposes a cured product of an active energy ray-curable resin composition as an alternative to a TAC protective film. According to this technique, a polarizing plate having small birefringence and excellent heat and moisture resistance can be obtained. However, if the birefringence is small, the birefringence changes at the location where the contraction stress of the polarizer is large, and the function as a polarizing plate is impaired.

JP 2005-92112 A

  An object of the present invention is to provide a polarizing plate having a transparent protective film, low birefringence, and hardly changing birefringence even when stress is applied, and a method for manufacturing the same.

  As a result of intensive studies to achieve the above object, the present inventors have found that at least one surface of the polarizer is a protective film made of a cured product of an active energy ray-curable resin composition containing a specific amount of two specific curable compounds. It was found that the polarizing plate directly protected by the above method has a low birefringence of the protective film and that the birefringence hardly changes even when stress is applied, and the present invention has been completed.

  That is, the present invention is a polarizing plate having a structure in which at least one surface of a polarizer is directly protected by a protective film made of a resin without interposing another layer, and the resin contains an unsaturated carboxylic acyl group. An active energy ray comprising the compound (A) having the above and a bridged alicyclic skeleton and the compound (B) having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton A cured product of the curable resin composition, having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton and two or more unsaturated carboxylic acyl groups, and The content of the compound (B) having a chain saturated aliphatic hydrocarbon skeleton in the active energy ray-curable resin composition is based on the entire active energy ray-curable compound in the active energy ray-curable resin composition. , To provide a polarizing plate which is a respectively 30 to 98 wt% and 40 wt%.

（式中、Ｒ¹、Ｒ²は、同一又は異なって、水素原子又は炭素数１〜４のアルキル基を示し、Ｘ¹、Ｘ²は、同一又は異なって、単結合、炭素数１〜８のアルキレン基、又は１若しくは２以上の炭素数１〜８のアルキレン基と１若しくは２以上の酸素原子又は硫黄原子とが結合した２価の基を示す。ｍ、ｎは、それぞれ、０又は１を示す）
で表される化合物であるのが好ましい。 As the compound (A) having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton, the following formula (1)

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; X ¹ and X ² are the same or different and represent a single bond or a carbon number of 1 to 8; Or a divalent group in which one or two or more alkylene groups having 1 to 8 carbon atoms and one or two or more oxygen atoms or sulfur atoms are bonded to each other, m and n are each 0 or 1; Indicate)
It is preferable that it is a compound represented by these.

（式中、Ｒ³、Ｒ⁴は、同一又は異なって、水素原子又は炭素数１〜４のアルキル基を示し、Ａは炭素数２〜１５の直鎖状又は分岐鎖状のアルキレン基を示し、Ｘ³、Ｘ⁴は、同一又は異なって、単結合又は連結基を示す）
で表される化合物であるのが好ましい。 The compound (B) having two or more unsaturated carboxylic acyl groups and having a chain saturated aliphatic hydrocarbon skeleton is represented by the following formula (2):

(In the formula, R ³ and R ⁴ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and A represents a linear or branched alkylene group having 2 to 15 carbon atoms. , X ³ and X ⁴ are the same or different and each represents a single bond or a linking group)
It is preferable that it is a compound represented by these.

  The present invention also includes a compound (A) having two or more unsaturated carboxylic acid acyl groups and having a bridged alicyclic skeleton and two or more unsaturated carboxylic acid acyl groups on at least one surface of the polarizer, and A compound (B) having a chain saturated aliphatic hydrocarbon skeleton, a compound (A) having two or more unsaturated carboxylic acyl groups and a bridged alicyclic skeleton, and the unsaturated carboxylic acid. The content of the compound (B) having two or more acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton is based on the whole active energy ray-curable compound in the active energy ray-curable resin composition, After directly applying the active energy ray-curable resin composition of 30 to 98% by weight and 1 to 40% by weight without passing through other layers, the active energy ray-curable resin composition is cured. Protective film To provide a method of manufacturing a polarizing plate characterized by forming.

  The compound (B) having two or more unsaturated carboxylic acyl groups and having a chain saturated aliphatic hydrocarbon skeleton has two or more unsaturated carboxylic acyl groups and a bridged alicyclic skeleton. It is assumed that a compound having

  According to the polarizing plate of the present invention, since the cured product of the active energy ray-curable resin composition containing a specific amount of two specific curable compounds is used as a protective film for the polarizer, the protective film is transparent and birefringent. In addition to being small, birefringence hardly changes even when stress is applied. It also has the characteristics of high toughness and resistance to cracking. According to the production method of the present invention, a polarizing plate having such excellent characteristics can be produced easily.

  The polarizing plate of the present invention has a structure in which at least one surface of the polarizer is protected by a protective film made of resin. The polarizer is not particularly limited, and a film obtained by doping and stretching iodine, a dichroic dye on a substrate such as polyvinyl alcohol (PVA), an acetalized product thereof, an ethylene-vinyl acetate copolymer, a saponified product thereof, or the like, or A film obtained by cross-linking them can be used. Among these, an iodine-containing polyvinyl alcohol film obtained by doping polyvinyl alcohol with iodine and crosslinked with boric acid or the like is particularly preferable.

  In the present invention, as the resin constituting the protective film, the compound (A) having two or more unsaturated carboxylate acyl groups and having a bridged alicyclic skeleton and two or more unsaturated carboxylate acyl groups and a chain are used. A cured product of an active energy ray-curable resin composition containing a compound (B) having a saturated saturated aliphatic hydrocarbon skeleton is used. In the present specification, the active energy ray-curable resin composition means a composition capable of forming a resin cured by irradiation with active energy rays.

[Compound (A) having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton]
The compound (A) having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton includes radical curing having a bridged alicyclic skeleton and two or more unsaturated carboxylic acyl groups in the molecule. If it is a property compound, it will not specifically limit. Examples of the unsaturated carboxylic acid acyl group include unsaturated carboxylic acids having about 3 to 10 carbon atoms such as acryloyl group, methacryloyl group, α-ethylacryloyl group, α-propylacryloyl group, α-butylacryloyl group, and crotonic acid acyl group. An acyl group etc. are mentioned.

Examples of the bridged alicyclic skeleton include, for example, a tricyclo [5.2.1.0 ^2,6 ] decane ring, a tricyclo [4.4.0.1 ^2,5 ] undecane ring, and a pentacyclo [6.5.1. .1 ^3,6 . 0 ^2,7 . 0 ^9,13] pentadecane ring, pentacyclo [6.6.1.1 ^3,6. 0 ^2,7 . 0 ^9,14 ] hexadecane ring, norbornane ring, bornane ring, isobornylane ring, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane ring, adamantane ring, decalin ring, perhydroindene ring and the like. Among these, tricyclo [5.2.1.0 ^2,6 ] decane ring, tricyclo [4.4.0.1 ^2,5 ] undecane ring, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] pentadecane ring, pentacyclo [6.6.1.1 ^3,6. 0 ^2,7 . 0 ^9,14 ] hexadecane ring is preferable, and tricyclo [5.2.1.0 ^2,6 ] decane ring is particularly preferable.

  The bridged alicyclic skeleton may have a substituent. Examples of the substituent include halogen atoms such as fluorine atom and chlorine atom; alkyl groups such as methyl, ethyl and propyl groups (alkyl groups having 1 to 6 carbon atoms); alkoxy groups such as methoxy, ethoxy and propoxy groups; Examples include acyl groups such as acetyl groups; alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl groups; hydroxyl groups; carboxyl groups and the like.

  The unsaturated carboxylic acyl group and the bridged alicyclic skeleton may be directly bonded, or may be bonded via a linking group.

  As the linking group, a polyvalent (for example, divalent) hydrocarbon group which may have a substituent, an oxygen atom (—O—), a sulfur atom (—S—), —NR— (R is a hydrogen atom) Or an alkyl group having 1 to 6 carbon atoms), a carbonyl group (—CO—), or a group in which two or more of these are bonded. Examples of the divalent hydrocarbon group include alkylene groups such as methylene, ethylene, methylmethylene, dimethylmethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, and octamethylene groups (having 1 to 8 carbon atoms). Divalent alicyclic hydrocarbon groups such as cycloalkylene groups such as cyclopentylene, cyclohexylene, cyclopentylidene, and cyclohexylidene groups; arylene groups such as phenylene and naphthylene groups A group in which two or more of these are bonded.

As the linking group, the following formula (3)
-X ⁵ -O- (3)
(In the formula, X ⁵ represents a single bond, an alkylene group having 1 to 8 carbon atoms, or an alkylene group having 1 or 2 or more carbon atoms and 1 or 2 or more oxygen atoms (—O—) or a sulfur atom. (-S-) is a divalent group bonded to the left side of X ⁵ is bonded to a bridged alicyclic skeleton, and the right side of O is bonded to an unsaturated carboxylic acyl group.
The group represented by these is preferable.

  Examples of the alkylene group having 1 to 8 carbon atoms include methylene, ethylene, methylmethylene, dimethylmethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene group and the like.

  Examples of the divalent group in which 1 or 2 or more alkylene group having 1 to 8 carbon atoms and 1 or 2 or more oxygen atoms or sulfur atoms are bonded include, for example, an oxyalkylene group having 1 to 8 carbon atoms and 2 carbon atoms. -8 alkyleneoxyalkylene group, thioalkylene group having 1 to 8 carbon atoms, alkylene thioalkylene group having 2 to 8 carbon atoms, poly (oxyalkylene) group having 2 to 8 carbon atoms, alkylene poly having 3 to 8 carbon atoms (Oxyalkylene) group and the like.

X ⁵ is particularly preferably a single bond or an alkylene group having 1 to 8 carbon atoms, and particularly preferably a methylene group.

A typical example of the compound (A) having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton is the compound represented by the formula (1). In the formula (1), R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X ¹ and X ² are the same or different and represent a single bond or 1 carbon atom. Or a divalent group in which one or two or more alkylene groups having 1 to 8 carbon atoms and one or two or more oxygen atoms or sulfur atoms are bonded to each other. m and n each represents 0 or 1;

Examples of the alkyl group having 1 to 4 carbon atoms in R ¹ and R ² include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and t-butyl groups. R ¹ and R ² are particularly preferably a hydrogen atom or a methyl group.

As the divalent group in which an alkylene group having 1 to 8 carbon atoms in X ¹ or X ² , an alkylene group having 1 or 2 or more carbon atoms and 1 or 2 or more oxygen atoms or sulfur atoms are bonded, is the same as the X ^5. X ¹ and X ² are each preferably a single bond or an alkylene group having 1 to 8 carbon atoms, particularly preferably a methylene group.

  It is particularly preferable that m and n are each 0.

Specific examples of the compound represented by the formula (1) include tricyclo [5.2.1.0 ^2,6 ] decanedimethanol di (meth) acrylate, tricyclo [5.2.1.0 ^2,6 ]. Decanediol di (meth) acrylate, tricyclo [4.4.0.1 ^2,5 ] undecane dimethanol di (meth) acrylate, tricyclo [4.4.0.1 ^2,5 ] undecanediol di (meth) acrylate , Pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] pentadecane dimethanol di (meth) acrylate, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] pentadecane diol di (meth) acrylate, pentacyclo [6.6.1.1 ^{3, 6.} 0 ^2,7 . 0 ^9,14 ] hexadecanedimethanol di (meth) acrylate, pentacyclo [6.6.1.1 ^3,6 . 0 ^2,7 . ^0,14 ] hexadecanediol di (meth) acrylate and the like.

[Compound (B) having two or more unsaturated carboxylic acyl groups and a chain saturated aliphatic hydrocarbon skeleton]
The compound (B) having two or more unsaturated carboxylic acyl groups and having a chain saturated aliphatic hydrocarbon skeleton includes a chain saturated aliphatic hydrocarbon skeleton and two or more unsaturated carboxylic acyl groups in the molecule. If it is a radically curable compound which has this, it will not specifically limit. Examples of the unsaturated carboxylic acid acyl group include unsaturated carboxylic acids having about 3 to 10 carbon atoms such as acryloyl group, methacryloyl group, α-ethylacryloyl group, α-propylacryloyl group, α-butylacryloyl group, and crotonic acid acyl group. An acyl group etc. are mentioned.

  Carbon number of the chain saturated aliphatic hydrocarbon skeleton is, for example, 1 to 20, preferably 2 to 20, and more preferably 3 to 15 (particularly 3 to 10).

  The chain saturated aliphatic hydrocarbon skeleton includes a divalent or higher chain saturated aliphatic hydrocarbon group. Examples of the divalent or higher chain saturated aliphatic hydrocarbon group include a linear or branched alkylene group which is a divalent chain saturated aliphatic hydrocarbon group, and a corresponding trivalent to tetravalent alkylene group. Examples include chain saturated aliphatic hydrocarbon groups. Examples of the linear or branched alkylene group include methylene, ethylene, methylmethylene, dimethylmethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, trimethylhexamethylene, decamethylene, C1-C20 linear or branched alkylene groups, such as dodecamethylene and a tetradecamethylene group, are mentioned. Among these, a C2-C20 linear or branched alkylene group is preferable, and a C3-C15 (for example, 3-10) linear or branched alkylene group is particularly preferable.

  The chain saturated aliphatic hydrocarbon skeleton may have a substituent. Examples of the substituent include halogen atoms such as fluorine atom and chlorine atom; alkoxy groups such as methoxy, ethoxy and propoxy groups; acyl groups such as acetyl groups; alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl groups; hydroxyl groups; A carboxyl group etc. are mentioned.

  The unsaturated carboxylate acyl group and the chain saturated aliphatic hydrocarbon skeleton may be directly bonded, or may be bonded via a linking group.

  As the linking group, a polyvalent (for example, divalent) alicyclic or aromatic hydrocarbon group which may have a substituent, an oxygen atom (—O—), a sulfur atom (—S—), —NR -(R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), a carbonyl group (-CO-), a group in which two or more of these are bonded, or one or more of these may have a substituent. And a group in which one or more of good polyvalent (for example, divalent) aliphatic hydrocarbon groups are bonded. Examples of the polyvalent alicyclic or aromatic hydrocarbon group include cyclopentylene, cyclohexylene, and phenylene groups. Examples of the polyvalent aliphatic hydrocarbon group include alkylene groups such as methylene, ethylene, methylmethylene, dimethylmethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, and octamethylene groups (one carbon atom) -8 alkylene groups, etc.).

A typical example of the compound (B) having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton is a compound represented by the formula (2). In formula (2), R ³ and R ⁴ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and A represents a linear or branched alkylene group having 2 to 15 carbon atoms. X ³ and X ⁴ are the same or different and each represents a single bond or a linking group.

Examples of the alkyl group having 1 to ⁴ carbon atoms in R ³ and R ⁴ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and t-butyl groups. R ³ and R ⁴ are particularly preferably a hydrogen atom or a methyl group.

  Examples of the linear or branched alkylene group having 2 to 15 carbon atoms in A include ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, trimethylhexamethylene, decamethylene, Examples include dodecamethylene and tetradecamethylene groups. Among these, a C3-C12 linear or branched alkylene group is preferable, and a hexamethylene group and a trimethylhexamethylene group are particularly preferable.

As the linking group in X ³ and X ⁴ , one or two or more alkylene groups having 1 to 8 carbon atoms, an oxygen atom (—O—), a sulfur atom (—S—), —NR— (R is hydrogen) And a divalent group in which one or more groups selected from a carbonyl group (—CO—) are bonded to each other.

Representative examples of the linking group for X ^3, X ^4, for example, -NH-CO-O-CH 2 CH 2 -, - NH-CO-O-CH 2 CH 2 CH 2 -, - NH-CO —O—CH ₂ CH ₂ CH ₂ CH ₂ —, —NH—CO—O—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ — (both are bonded to A on the left and unsaturated carboxylic acid on the right And bonded to the oxygen atom of the acyloxy group).

  Specific examples of the compound represented by the formula (2) include a reaction product of hexamethylene diisocyanate and hydroxyethyl (meth) acrylate, a reaction product of trimethylhexamethylene diisocyanate and hydroxyethyl (meth) acrylate, Examples thereof include urethane compounds having two or more unsaturated carboxylic acyl groups and a chain saturated aliphatic hydrocarbon skeleton, such as a reaction product of a saturated aliphatic polyisocyanate and a hydroxyalkyl (meth) acrylate.

（式中、Ｒ³、Ｒ⁴は前記に同じ。Ｒ⁵、Ｒ⁶、Ｒ⁷は、同一又は異なって、水素原子又は炭素数１〜４のアルキル基を示す）
で表される化合物が好ましい。 Among the compounds represented by the formula (2), the following formula (2a)

(Wherein R ³ and R ⁴ are the same as above. R ⁵ , R ⁶ and R ⁷ are the same or different and represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms)
The compound represented by these is preferable.

As a C1-C4 alkyl group in R < ⁵ >, R < ⁶ >, R < ⁷ >, a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl group is mentioned, for example. R ³ and R ⁴ are particularly preferably a hydrogen atom or a methyl group.

Other examples of the compound (B) having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton include, for example, 1,4-butanediol di (meth) acrylate, 1,6- Hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, alkylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate [C _2-15 alkylene glycol di (meth) acrylate etc.], polyethylene glycol Di (meth) acrylate, polyalkylene glycol di (meth) acrylate such as polypropylene glycol di (meth) acrylate, bisphenol A-diglycidyl ether di (meth) acrylate, ethylene oxide modified bisphenol A-di (meth) acrylate, etc. Functional (meth) acrylic acid esters; trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol penta (meth) acrylate, pentaerythritol hexa (meth) acrylate, ethylene oxide added trimethylolpropane Trifunctional or higher polyfunctional monomers such as tri (meth) acrylate and dipentaerythritol penta (meth) acrylate are exemplified. Among these, C _2-15 alkylene glycol di (meth) acrylate (particularly C _4-12 alkylene glycol di (meth) acrylate) such as 1,6-hexanediol di (meth) acrylate is preferable.

  In the present invention, in the active energy ray-curable resin composition, as the active energy ray-curable compound, the compound (A) having two or more unsaturated carboxylic acid acyl groups and having a bridged alicyclic skeleton, and It may contain only the compound (B) having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton, but may further contain other active energy ray-curable compounds. . Examples of such other active energy ray curable compounds include radical curable compounds and cationic curable compounds.

  The radical curable compound has at least one ethylenic double bond in the molecule and is irradiated with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.) in the presence of a polymerization initiator. And a polymerizable compound. Examples of such compounds include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and t-butyl (meth) acrylate. , 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, glycidyl (meth) acrylate, methoxyethyl (meth) ) Acrylate, ethoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, phenoxyethyl (meth) acrylate, norbornyl (meth) acrylate, isovol Monofunctional (meth) acrylic acid ester monomers such as ru (meth) acrylate, (meth) acryloylmorpholine, γ- (meth) acryloyloxypropyltrimethoxysilane; styrene, α-methylstyrene, vinyltoluene, vinyl acetate, Vinyl monomers such as allyl acetate, vinyl propionate, vinyl benzoate, N-vinylpyrrolidone, N-vinylimidazole, N-vinylcaprolactam; triallyl cyanurate, triallyl isocyanurate, 1,3,5-triacryloylhexa And hydro-s-hydrazine. Among these, polyfunctional monomers having two or more functions are preferable. These radically curable compounds can be used alone or in combination of two or more.

  Moreover, (meth) acrylate oligomers, such as ester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, and acrylic (meth) acrylate, can also be used as the radical curable compound.

  Examples of the cationic curable compound include vinyl ether compounds, epoxy compounds, oxetane compounds, and the like.

  Examples of vinyl ether compounds include ethylene oxide modified bisphenol A-divinyl ether, ethylene oxide modified hydroquinone divinyl ether, and the like.

  Examples of the epoxy compound include 1,2-epoxycyclohexane, limonene diepoxide, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 1,4-butanediol diglycidyl ether, Methylolpropane diglycidyl ether, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, bisphenyl A-diglycidyl ether, bisphenyl F-diglycidyl ether, bisphenyl S-diglycidyl ether, hydrogenated bisphenol A -Diglycidyl ether etc. are mentioned.

  Examples of the oxetane compound include 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (phenoxymethyl) oxetane, and di [(3-ethyl-3-oxetanyl) methyl] ether.

  In the present invention, the active energy ray-curable resin composition may contain a thermosetting compound in addition to the active energy ray-curable compound.

  The proportion of the compound (A) having two or more unsaturated carboxylic acid acyl groups and having a bridged alicyclic skeleton in the total curable compound in the active energy ray-curable resin composition is 30 to 98% by weight. Yes, preferably 50 to 98% by weight, more preferably 70 to 98% by weight. By including in this range the compound (A) having two or more unsaturated carboxylic acid acyl groups and having a bridged alicyclic skeleton, the birefringence is small and the birefringence hardly changes even when stress is applied. A membrane is obtained.

  The proportion of the compound (B) having two or more unsaturated carboxylic acyl groups and a chain saturated aliphatic hydrocarbon skeleton in the total curable compound in the active energy ray curable resin composition is 1 to 40 wt. %, Preferably 1.5 to 30% by weight, more preferably 1.5 to 20% by weight. When the content of the compound (B) having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton is too small, the cured product is brittle and cracked when used as a protective film of a polarizing plate. Such problems are likely to occur. On the other hand, when the content of the compound (B) having two or more unsaturated carboxylate acyl groups and having a chain saturated aliphatic hydrocarbon skeleton is too large, the glass transition temperature (Tg) of the protective film is lowered. Therefore, it is difficult to obtain the characteristic that the birefringence hardly changes even when stress is applied.

  The compound (A) having 2 or more of the unsaturated carboxylic acid acyl groups in the total curable compound in the active energy ray-curable resin composition and having the bridged alicyclic skeleton and 2 unsaturated carboxylic acid acyl groups The total proportion of the compound (B) having a chain saturated aliphatic hydrocarbon skeleton is, for example, 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight. % Or more.

  In addition to the above curable compound, the active energy ray-curable resin composition includes a photopolymerization initiator, and, if necessary, a photosensitizer, a photocationic polymerization initiator, a thermal cationic polymerization initiator, and a thermal radical polymerization initiation. An agent, a light accelerator, a light stabilizer, an ultraviolet absorber, a leveling agent, an antifoaming agent and the like may be blended.

  As a photoinitiator, it can select suitably according to the kind of active energy ray which is a hardening means. Examples of photopolymerization initiators include acetophenone, 3-methylacetophenone, benzophenone, 4-chlorobenzophenone, 4,4-diaminobenzophenone, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,2-dimethoxy-2-phenylacetone , Xanthofluorenone, benzaldehyde, anthraquinone, benzoin ethyl ether, benzoin propyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 4-oxanthone, camphorquinone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one and the like can be mentioned.

  Compound (A) having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton and compound having two or more unsaturated carboxylic acyl groups and having a chain saturated aliphatic hydrocarbon skeleton ( The total content of B) in the active energy ray-curable resin composition is, for example, 30 to 99 with respect to the entire solid content (including components solidified by curing) in the active energy ray-curable resin composition. 9.9% by weight, preferably 50 to 99.5% by weight, more preferably 70 to 99% by weight, particularly preferably 90 to 99% by weight.

  The content of the photopolymerization initiator in the active energy ray-curable resin composition is, for example, 0.1% with respect to the entire solid content (including components that are solidified by curing) in the active energy ray-curable resin composition. It is about 10 to 10% by weight, preferably about 1 to 8% by weight.

  In the polarizing plate of the present invention, the active energy ray-curable resin composition is directly applied to at least one surface of the polarizer without interposing another layer, and then the active energy ray-curable resin composition is applied. It is manufactured by forming a protective film by curing.

  The coating method of the active energy ray-curable resin composition is not particularly limited, and various coating methods such as a doctor blade, a wire bar, a die coater, and a gravure coater can be used. When coating, the viscosity of the curable resin composition may be adjusted using a solvent.

  The coating film made of the active energy ray-curable resin composition is cured by irradiating active energy rays to form a protective film. Examples of active energy rays include ultraviolet rays, visible rays, electron beams, and X-rays. Among these, it is preferable to use ultraviolet rays. Examples of ultraviolet ray generation sources include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, chemical lamps, xenon lamps, black light lamps, metal halide lamps, and the like.

  The thickness of the protective film is, for example, 10 to 200 μm, preferably 30 to 100 μm, from the viewpoints of thin and lightweight properties, protective properties, handleability and the like.

  The polarizing plate of the present invention has a compound (A) having two or more unsaturated carboxylic acid acyl groups and a bridged alicyclic skeleton as a protective film for a polarizer and two or more unsaturated carboxylic acid acyl groups, and Since a cured product of an active energy ray-curable resin composition containing a specific amount of the compound (B) having a chain saturated aliphatic hydrocarbon skeleton is used, not only is the protective film transparent and birefringence is small, but also stress is Even if applied, it has a great advantage that birefringence hardly changes.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The photoelastic coefficient and retardation of the cured film (cured film) and the glass transition temperature were measured by the following methods.

[Measurement of photoelastic coefficient and phase difference]
A cured film having a thickness of 100 μm was prepared and measured using a three-dimensional birefringence meter (“KOBRA-WR”) manufactured by Oji Scientific Instruments.

[Measurement of glass transition temperature]
An active energy ray-curable resin composition is applied to a cold-rolled steel sheet (thickness 0.3 mm × width 20 mm × length 50 mm) (thickness 40 μm), and a small UV irradiator (produced by Eyegraphic Co., Ltd., “ECS”). -401GX ", rated voltage 200V, high-pressure mercury lamp) was irradiated with ultraviolet rays with an integrated light amount of 350 mJ / cm ² from a distance of 11 cm to obtain a cured film of the active energy ray-curable resin composition. This was heated from 25 ° C. to 200 ° C. using a rigid pendulum type viscoelasticity measuring apparatus (manufactured by A & D Co., Ltd., “RPT-3000W”), and the glass transition temperature (Tg) was measured.

Synthesis Example 1 (Synthesis of a compound having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton)
In a 1 L flask equipped with a stirrer, a thermometer and a condenser, 52.5 parts by weight (2 mol) of 2-hydroxyethyl acrylate, 0.02 part by weight of dibutyltin laurate (200 ppm, added to the resulting compound) and hydroquinone monomethyl 0.08 part by weight of ether (800 ppm, amount added to the resulting compound) was added, and while stirring, the internal temperature was raised to 70 ° C., and then 47.5 parts by weight (1 mol) of trimethylhexane diisocyanate was added dropwise over 3 hours. Thereafter, the reaction was continued until the residual isocyanate group became 0.1% or less, and a compound having two or more unsaturated carboxylic acyl groups and a chain saturated aliphatic hydrocarbon skeleton was obtained.

Example 1
In 95 parts by weight of tricyclo [5.2.1.0 ^2,6 ] decanedimethanol diacrylate represented by the following formula (1a) (trade name “IRR-214K”, manufactured by Daicel-Cytec Co., Ltd.) 5 parts by weight of the compound obtained in 1 and 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone were added and mixed to obtain an active energy ray-curable resin composition 1. An active energy ray-curable resin composition 1 is applied to a glass plate with a film thickness of 120 μm using an applicator, and a small UV irradiator (“ECS-401GX” manufactured by Eye Graphic Co., Ltd., rated voltage 200 V, high-pressure mercury lamp ) Was irradiated twice with an ultraviolet ray having an accumulated light amount of 350 mJ / cm ² from a distance of 11 cm, to obtain a single cured film of the active energy ray-curable resin composition 1. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Example 2
10 parts by weight of the compound obtained in Synthesis Example 1 in 90 parts by weight of tricyclo [5.2.1.0 ^2,6 ] decane dimethanol diacrylate (trade name “IRR-214K”, manufactured by Daicel Cytec Co., Ltd.) And 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone were added and mixed to obtain an active energy ray-curable resin composition 2. The active energy ray-curable resin composition 2 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 2 alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Example 3
1,6-hexanediol diacrylate (Cytec Surface) was added to 90 parts by weight of tricyclo [5.2.1.0 ^2,6 ] decane dimethanol diacrylate (manufactured by Daicel-Cytec Co., Ltd., trade name “IRR-214K”). 10 parts by weight of Specialties, trade name “HDDA”) and 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone were added and mixed to obtain an active energy ray-curable resin composition 3. The active energy ray-curable resin composition 3 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 3 alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Comparative Example 1
An active energy ray-curable resin composition 4 is obtained by adding and mixing 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone to 100 parts by weight of epoxy acrylate obtained by reacting 2 mol of acrylic acid with bisphenol A glycidyl ether. It was. The active energy ray-curable resin composition 4 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 4 alone. A film was obtained. The photoelastic coefficient and retardation of the obtained cured film were measured.

Comparative Example 2
To 100 parts by weight of the compound obtained in Synthesis Example 1, 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone was added and mixed to obtain an active energy ray-curable resin composition 5. The active energy ray-curable resin composition 5 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 5 alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Comparative Example 3
The active energy ray-curable resin composition 6 was obtained by mixing 50 parts by weight of pentaerythritol triacrylate, 50 parts by weight of the compound obtained in Synthesis Example 1, and 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone. The active energy ray-curable resin composition 6 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 6 alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Comparative Example 4
Mixing 50 parts by weight of triacrylate of trimethylolpropane ethylene oxide 2-mole adduct, 50 parts by weight of the compound obtained in Synthesis Example 1, and 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone, the active energy ray curability is mixed. A resin composition 7 was obtained. The active energy ray-curable resin composition 7 is applied on a glass plate with a film thickness of 120 μm using an applicator, irradiated with ultraviolet rays in the same manner as in Example 1, and the active energy ray-curable resin composition 7 is cured alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Comparative Example 5
The active energy ray-curable resin composition 8 was obtained by mixing 50 parts by weight of ditrimethylolpropane tetraacrylate, 50 parts by weight of the compound obtained in Synthesis Example 1, and 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone. The active energy ray-curable resin composition 8 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 8 alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured.

Comparative Example 6
Tricyclo [5.2.1.0 ^2,6 ] decane dimethanol diacrylate (manufactured by Daicel Cytec Co., Ltd., trade name “IRR-214K”) in 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone Part was added and mixed to obtain an active energy ray-curable resin composition 9. The active energy ray-curable resin composition 9 is applied on a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1 to cure the active energy ray-curable resin composition 9 alone. A film was obtained. While visually observing the appearance of the obtained cured film, the photoelastic coefficient and the phase difference were measured. In addition, the obtained cured film is very fragile and easily breaks when it is bent by hand. On the other hand, the cured films obtained in Examples 1 to 3 and Comparative Examples 1 to 5 are not broken even if they are bent by hand.

Comparative Example 7
An active energy ray-curable resin composition obtained by mixing 5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone with 100 parts by weight of 1,6-hexanediol diacrylate (trade name “HDDA” manufactured by Cytec Surface Specialties) 10 was obtained. The active energy ray-curable resin composition 10 was applied to a glass plate with a film thickness of 120 μm using an applicator and irradiated with ultraviolet rays in the same manner as in Example 1. As a result, the coating film cracked during UV curing, and a cured film was not obtained.

  Table 1 shows the measurement results of the appearance, properties, glass transition temperature, photoelastic coefficient, and retardation of the cured films obtained in Examples and Comparative Examples. In the table, “-” indicates that measurement is not possible. In the cured film of Comparative Example 1, when the photoelastic coefficient and the phase difference were measured, the photoelastic coefficient and the phase difference could not be measured because they were plastically deformed within the measurement load range. From Table 1, the cured films obtained in the examples are transparent, and both the phase difference and the photoelastic coefficient are small, and not only the birefringence is small, but also the birefringence changes even when stress is applied. I find it difficult.

Claims (4)

  A polarizing plate having a structure in which at least one surface of a polarizer is directly protected by a protective film made of a resin without interposing another layer, wherein the resin has two or more unsaturated carboxylate acyl groups and has a bridge An active energy ray-curable resin composition comprising a compound (A) having an alicyclic skeleton and a compound (B) having two or more unsaturated carboxylic acid acyl groups and having a chain saturated aliphatic hydrocarbon skeleton Compound (A) having two or more unsaturated carboxylic acyl groups and a bridged alicyclic skeleton, and two or more unsaturated carboxylic acyl groups and a chain saturated aliphatic carbonization, which is a cured product The content of the compound (B) having a hydrogen skeleton in the active energy ray-curable resin composition is 30 to 98 times the total amount of the active energy ray-curable compound in the active energy ray-curable resin composition. A polarizing plate characterized in that it is a%, and 1 to 40 wt%. The compound (A) having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton is represented by the following formula (1):

(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; X ¹ and X ² are the same or different and represent a single bond or a carbon number of 1 to 8; Or a divalent group in which one or two or more alkylene groups having 1 to 8 carbon atoms and one or two or more oxygen atoms or sulfur atoms are bonded to each other, m and n are each 0 or 1; Indicate)
The polarizing plate according to claim 1, which is a compound represented by the formula: The compound (B) having two or more unsaturated carboxylic acyl groups and having a chain saturated aliphatic hydrocarbon skeleton is represented by the following formula (2):

(In the formula, R ³ and R ⁴ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and A represents a linear or branched alkylene group having 2 to 15 carbon atoms. , X ³ and X ⁴ are the same or different and each represents a single bond or a linking group)
The polarizing plate according to claim 1, which is a compound represented by the formula:   Compound (A) having at least two unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton and at least two unsaturated carboxylic acyl groups on at least one surface of the polarizer, and chain saturated aliphatic carbonization A compound (B) having a hydrogen skeleton, having two or more unsaturated carboxylic acyl groups and having a bridged alicyclic skeleton, and two or more unsaturated carboxylic acyl groups. And the content of the compound (B) having a chain saturated aliphatic hydrocarbon skeleton is 30 to 98% by weight with respect to the entire active energy ray-curable compound in the active energy ray-curable resin composition, respectively. And an active energy ray-curable resin composition that is 1 to 40% by weight is directly applied without any other layer, and then the active energy ray-curable resin composition is cured to form a protective film. Special Method for producing a polarizing plate with.