WO2012133163A1

WO2012133163A1 - Polarizing plate and laminated optical member

Info

Publication number: WO2012133163A1
Application number: PCT/JP2012/057477
Authority: WO
Inventors: 悦夫久米; 智康竹内; 高橋　利行; 英里本間
Original assignee: 住友化学株式会社; 株式会社Adeka
Priority date: 2011-03-29
Filing date: 2012-03-23
Publication date: 2012-10-04
Also published as: TW201245381A; KR20140029415A; CN109239831A; CN109239831B; TWI582199B; JP5945098B2; JP2012208246A; KR101894120B1; CN103430060A

Abstract

Provided is a polarizing plate configured from a polyvinyl alcohol-based polarizer and a protecting film pasted to the polarizer with an adhesive therebetween, wherein the adhesive contains 100 parts by weight of a photo cation curable component (A) and 1-10 parts by weight of a photo cation polymerization initiator (B), the cured product thereof is formed from a photocurable adhesive composition exhibiting a storage elastic modulus of at least 1000 MPa at 80°C, and the photo cation curable component (A) is prepared in a manner so as to contain the following (A1) and (A2) at the following quantities relative to the total quantity thereof: 50-95 wt% of an alicyclic epoxy compound (A1) having an epoxy group bonded to an alicyclic ring; and 5-50 wt% of a diglycidyl compound (A2) having no greater than 1 wt% of contained chlorine and represented by formula (I) (Z being an alkylene group or the like).

Description

Polarizing plate and laminated optical member

This invention relates to the polarizing plate which bonded the protective film on the single side | surface or both surfaces of the polarizer using the specific photocurable adhesive agent. The present invention also relates to a laminated optical member in which another optical layer such as a retardation film is laminated on the polarizing plate.

The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate is usually used by being incorporated in a liquid crystal display device in a state where protective films are laminated on both sides of the polarizer. It is also known that a protective film is provided only on one side of the polarizer, but in many cases, the other side is not merely a protective film, but a layer having another optical function also serves as the protective film. It will be pasted. Further, as a method for producing a polarizer, a method in which a uniaxially stretched polyvinyl alcohol resin film dyed with a dichroic dye is treated with boric acid, washed with water and dried is widely known.

Usually, a protective film is bonded to the polarizer immediately after washing and drying as described above. This is because the dried polarizer has a low physical strength, and once it is wound, there is a problem such as tearing in the processing direction. Therefore, the polarizer after drying is usually applied immediately after applying an aqueous adhesive, and then a protective film is simultaneously bonded on both sides via this adhesive. Usually, a triacetyl cellulose film having a thickness of 30 to 120 μm is used as the protective film.

Triacetylcellulose has high moisture permeability, and the polarizing plate bonded as a protective film has a problem of causing deterioration under wet heat, for example, at a temperature of 70 ° C. and a relative humidity of 90%. Therefore, it is also known to use an amorphous polyolefin resin having a lower moisture permeability than that of triacetyl cellulose, for example, an amorphous polyolefin resin represented by a norbornene resin as a protective film.

When a protective film made of a resin with low moisture permeability is bonded to a polyvinyl alcohol polarizer, a polyvinyl alcohol resin that has been conventionally used as an adhesive for bonding a polyvinyl alcohol polarizer and triacetyl cellulose. The aqueous solution has a problem that the adhesive strength is not sufficient or the appearance of the obtained polarizing plate becomes poor. This is because a resin film having low moisture permeability is generally hydrophobic, and water that is a solvent cannot be sufficiently dried due to low moisture permeability. On the other hand, it is also known to bond different types of protective films on both sides of the polarizer. For example, one side of the polarizer is made of a resin with low moisture permeability such as an amorphous polyolefin-based resin. There is also a proposal for bonding a protective film and bonding a protective film made of a highly moisture-permeable resin such as cellulose resin including triacetyl cellulose to the other surface of the polarizer.

Therefore, a high adhesion force is provided between the protective film made of a resin having a low moisture permeability and the polyvinyl alcohol polarizer, and a high adhesion between a highly moisture permeable resin such as a cellulose resin and the polyvinyl alcohol polarizer. There is an attempt to use an active energy ray-curable adhesive as an adhesive that gives force. For example, Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 1) discloses an adhesive mainly composed of an epoxy compound that does not contain an aromatic ring, and this adhesive is obtained by cationic polymerization by irradiation with active energy rays. It has been proposed to cure and bond the polarizer and the protective film. Japanese Patent Application Laid-Open No. 2008-257199 (Patent Document 2) discloses a photocuring property in which an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group are combined with a photocationic polymerization initiator. A technique of using an adhesive for bonding a polarizer and a protective film is disclosed.

On the other hand, JP 2009-181046 A (Patent Document 3) and JP 2002-365432 A (Patent Document 4) describe the case where an aqueous adhesive is used. Depending on the wettability of the adhesive and the viscosity of the adhesive, it is described that appearance defects may occur in the polarizing plate after production, and these parameters have a great influence on productivity, and as a countermeasure against it, improvement of wettability In addition, it is described that it is effective to reduce the viscosity of the adhesive itself and that the viscosity contributes greatly.

Unlike the solvent-type adhesive, the epoxy-based photocurable adhesive as shown in Patent Documents 1 and 2 is usually prepared without substantially adding a solvent. Therefore, in many cases, it is necessary to increase the ratio of the low viscosity component in the composition in order to reduce the viscosity. Reducing the viscosity of the adhesive liquid before curing by changing the composition ratio often results in insufficient hardness of the adhesive layer after curing, and the bonded polarizing plate is less likely to exhibit sufficient durability. There was a concern of becoming. So far, improvement of wettability by surface modification of a film or addition of a leveling agent has been mainly employed as a measure for avoiding poor appearance in the manufacturing process of a polarizing plate.

JP 2004-245925 A JP 2008-257199 A JP 2009-181046 A JP 2002-365432 A

When bonding the polarizer and the protective film using an epoxy-based photocurable adhesive, the inventors of the present invention do not exhibit a sufficiently high level of the adhesive layer after curing if the viscosity of the adhesive before the effect is lowered. As a result of intensive studies to improve the problem, the present invention has been completed. Accordingly, an object of the present invention is to increase the coating suitability by lowering the viscosity of the photocurable adhesive used in a polarizing plate in which a polarizer and a protective film are bonded using an epoxy-based photocurable adhesive. It is to provide a polarizing plate which gives sufficient hardness after the adhesive is cured and has an increased adhesive force between the polarizer and the protective film. Another object of the present invention is to provide a laminated optical member suitably used for a liquid crystal display device by laminating another optical layer such as a retardation film on the polarizing plate.

As a result of research, combining at least two types of photocationically curable epoxy compounds, alicyclic epoxy compounds and diglycidyl compounds, to reduce the amount of chlorine in diglycidyl compounds in photocurable adhesives that are substantially free of solvents. Thus, it was found that the viscosity can be reduced by adjusting the composition ratio while maintaining the hardness of the adhesive layer after curing at a high value. The present invention includes the following.

[1] From a polarizer made of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented, and from a protective film made of a transparent resin bonded to at least one surface of the polarizer via an adhesive The polarizing plate is composed of an adhesive containing 100 parts by weight of the cationic photocuring component (A) and 1 to 10 parts by weight of the cationic photopolymerization initiator (B). It is formed from a photocurable adhesive composition that exhibits a storage elastic modulus of 1000 MPa or higher at 80 ° C., and the above photocationic curable component (A) contains the following (A1) and (A2) in the total amount A polarizing plate prepared so as to contain the following amount based on the above.

50 to 95% by weight of the alicyclic epoxy compound (A1) having two or more epoxy groups in the molecule, at least one of which is bonded to the alicyclic ring, and 1% by weight of chlorine % Of the diglycidyl compound (A2) represented by the following formula (I): 5 to 50% by weight:

In the formula, Z is an alkylene group having 1 to 9 carbon atoms, an alkylidene group having 3 or 4 carbon atoms, a divalent alicyclic hydrocarbon group, or the formula —C _m H _2m —Z ¹ —C _n H _2n —. Represents a divalent group shown, wherein —Z ¹ — represents —SO ₂ —, —SO— or —CO—, and m and n each independently represents an integer of 1 or more, Is 9 or less.

[2] The polarizing plate according to [1], wherein the protective film bonded to at least one surface of the polarizer is made of an acetylcellulose-based resin.

[3] The protective film bonded to at least one surface of the polarizer is made of a transparent resin selected from the group consisting of an amorphous polyolefin resin, a polyester resin, a polycarbonate resin, and a chain polyolefin resin. 1].

[4] A protective film made of acetylcellulose-based resin is bonded to one surface of the polarizer via the adhesive, and an amorphous polyolefin-based resin, polyester-based resin, polycarbonate is bonded to the other surface of the polarizer. The polarizing plate according to [1], wherein a protective film, which is a film made of a transparent resin selected from the group consisting of a series resin and a chain polyolefin resin, is bonded via the adhesive.

[5] A laminated optical member comprising a laminate of the polarizing plate according to any one of [1] to [4] and another optical layer.

[6] The laminated optical member according to [5], wherein the optical layer includes a retardation film.

The polarizing plate of the present invention has a high storage elastic modulus after curing, while the photocurable adhesive used for its production exhibits a low viscosity before curing and the coating suitability is improved. The film adheres well. This polarizing plate has a low possibility of causing cracks in the polarizer even when subjected to a thermal shock test (heat shock test) in which the polarizer is repeatedly placed in a high temperature environment and in a low temperature environment, for example. Excellent in properties. Similarly, a laminated optical member in which another optical layer such as a retardation film is laminated on this polarizing plate is also less likely to cause cracks in the polarizer even under severe conditions. The liquid crystal display device is also excellent in reliability.

Hereinafter, embodiments of the present invention will be described in detail. In the present invention, a protective film made of a transparent resin is bonded to at least one surface of a polarizer made of a polyvinyl alcohol-based resin film on which a dichroic dye is adsorbed and oriented via a photocurable adhesive, And The photocurable adhesive contains 100 parts by weight of the photocationic curable component (A) and 1 to 10 parts by weight of the photocationic polymerization initiator (B), and the cured product has a cured product of 1000 MPa or more at 80 ° C. It forms from the photocurable adhesive composition which shows the storage elastic modulus. Furthermore, another optical layer is laminated on this polarizing plate to obtain a laminated optical member suitably used for a liquid crystal display device. Then, description is advanced in order of the photocurable adhesive composition used for manufacture of a polarizing plate, a polarizing plate using the same, and a laminated optical member using the same.

[Photocurable adhesive composition]
As described above, the photocurable adhesive composition used in the present invention contains 100 parts by weight of the photocationic curable component (A) and 1 to 10 parts by weight of the photocationic polymerization initiator (B). Further, the photocationic curable component (A) contains the following (A1) and (A2) in the following amounts based on the total amount.

50 to 95% by weight of an alicyclic epoxy compound (A1) having two or more epoxy groups in the molecule, at least one of which is bonded to an alicyclic ring, and a chlorine content of 1% 5 to 50% by weight of the diglycidyl ether compound (A2) represented by the formula (I) below.

(Photocationic curable component)
The alicyclic epoxy compound (A1) as a main component of the photocationic curable component (A) can be a well-known general epoxy compound, but from the viewpoint of weather resistance, refractive index and photocurability, the molecule Those having no aromatic ring in the structure are preferred. Examples of the alicyclic epoxy compound (A1) include those represented by the following general formulas (1) to (23).

In the above general formulas, R ¹ to R ⁴⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. When R ¹ to R ⁴⁶ are alkyl groups, the position bonded to the alicyclic structure is any position from the 1st to 6th positions. The alkyl group having 1 to 6 carbon atoms may be linear or branched, and may have an alicyclic structure. Y ¹ represents an oxygen atom or an alkanediyl group, and Y ² to Y ²¹ each independently represents a linear, branched or alkanediyl group which may have an alicyclic structure. To express. The carbon number of the alkanediyl group is Y ² , Y ⁴ , Y ⁹ , Y ¹⁰ , Y ¹¹ , Y ¹² , Y ¹³ , Y ¹⁴ , Y ¹⁵ , Y ¹⁸ , Y ¹⁹ , Y ²⁰ , Y ^21. 20, Y ¹ , Y ³ , Y ⁵ , Y ⁶ , Y ⁷ , Y ⁸ , Y ¹⁷ , Y ¹⁸ are 2-20. Z ¹ and Z ² each independently represents a straight chain, may have a branch, and represents an alkanetriyl group which may have an alicyclic structure. As for the carbon number of the alkanetriyl group, Z ¹ is 2 to 20, and Z ² is 1 to 20. T ¹ may be straight-chain, branched, or an alkanetetrayl group having 1 to 20 carbon atoms that may have an alicyclic structure. a to r each represents an integer of 0 to 20.

The above alicyclic epoxy compounds (A1) can be used alone or in combination of two or more.

The diglycidyl compound (A2), which is another component of the photocation curable component (A), is represented by the formula (I). In the formula (I), Z represents an alkylene group having 1 to 9 carbon atoms, an alkylidene group having 3 or 4 carbon atoms, a divalent alicyclic hydrocarbon group, or a group represented by the formula:
—C _m H _2m —Z ¹ —C _n H _2n —
Wherein —Z ¹ — is —SO ₂ —, —SO— or —CO—, and m and n are each independently an integer of 1 or more. The total is 9 or less. Typical examples of the divalent alicyclic hydrocarbon group include cyclopentylene and cyclohexylene.

In the formula (I), the compound in which Z is an alkylene group is diglycidyl ether of alkylene glycol. Specific examples are ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neo Examples include pentyl glycol diglycidyl ether, 3-methyl-1,5-pentanediol diglycidyl ether, 2-methyl-1,8-octanediol diglycidyl ether, and 1,4-cyclohexanedimethanol.

In the formula (I), a compound in which Z is a divalent group represented by the formula —C _m H _2m —Z ¹ —C _n H _2n — is an alkylene group having 2 or more carbon atoms, This corresponds to the group in which the C—C bond is interrupted by —SO ₂ —, —SO—, or —CO—.

The diglycidyl compound represented by the formula (I) is generally distributed in a state containing a large amount of chlorine for the reason of the production process. That is, in the production of this compound, epichlorohydrin is reacted with a dihydric alcohol corresponding to the formula HO—Z—OH, including alkylene glycols, in the presence of an acidic catalyst such as sulfuric acid, boron trifluoride, and tin tetrachloride. In the case of using a two-stage method in which chlorohydrin ether is produced and then chlorohydrin ether is subjected to intramolecular ring closure with alkali, formation of a 2-mol adduct of epichlorohydrin is avoided in the addition reaction of epichlorohydrin in the first step. In addition, the organic chlorine contained in the 2-mole adduct is not decomposed by the intramolecular ring closure reaction in the second step, and glycidyl ethers cannot usually be purified by distillation. It contains about 3% by weight of organochlorine compounds.

The diglycidyl compound (A2) used in the present invention must have a chlorine content of 1% or less. For example, (1) dihydric alcohol and epichlorohydrin are added in the presence of an alkali metal hydroxide. Water in the reaction system is converted into an azeotropic solvent (for example, hydrocarbons such as n-hexane, cyclohexane, n-heptane, benzene, or toluene, ethers such as ethyl ether and isopropyl ether, 1,2- A method of reacting azeotropically with dichloroethane, 1,2-dichloropropane, trichloroethylene, or a halogenated hydrocarbon such as chloroform, a solvent having an azeotropic temperature of 30 to 90 ° C. such as sulfoxide compound, and the like (2 ) Adjust the equivalent of alkali metal hydroxide to 0.5-1.5 and in the presence of epichlorohydrin By reacting, washing with water and / or treating with an alkali adsorbent, and then distilling off epichlorohydrin, (3) by condensing the hydroxyl compound and epichlorohydrin in the presence of alkali, and reacting them while irradiating with ultrasonic waves, etc. Its chlorine content is reduced.

(Photocationic polymerization initiator)
The photocationic polymerization initiator (B) blended in the photocurable adhesive composition is a compound capable of releasing a substance that initiates cationic polymerization by light irradiation. A double salt that is an onium salt that releases an acid, or a derivative thereof. A typical example of such a compound is a salt of a cation and an anion represented by the general formula [A] ^{y +} [B] ^y- .

Here, the cation A ^{y +} is preferably onium, and the structure thereof can be represented by, for example, [(R ⁴¹ ) _x Q] ^{y +} .

Further, R ⁴⁵ is an organic group having 1 to 60 carbon atoms and may contain any number of atoms other than carbon, and x is an integer of 1 to 5. The x R ^{45 s} are independent and may be the same or different. Moreover, it is preferable that at least one is an aromatic group. Q is an atom or atomic group selected from the group consisting of S, N, Se, Te, P, As, Sb, Bi, O, I, Br, Cl, F, and N = N. Further, when the valence of Q in the cation A ^{y +} is z, it is necessary that the relationship y = x−z holds.

The anion B ^y− is preferably a halide complex, and its structure can be represented by, for example, [LX _s ] ^y− .

Here, L is a metal or metalloid which is a central atom of a halide complex, and B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V , Cr, Mn, Co and the like. X is a halogen. s is an integer of 3 to 7. Further, when the valence of L in the anion B ^y− is t, it is necessary that the relationship y = s−t holds.

Specific examples of the anion [LX _s ] ^y− in the above general formula include tetrafluoroborate (BF ₄ ) ⁻ , hexafluorophosphate (PF ₆ ) ⁻ , hexafluoroantimonate (SbF ₆ ) ⁻ , hexafluoroarsenate. (AsF ₆ ) ⁻ , hexachloroantimonate (SbC 1 ₆ ) ^{− and the} like.

As the anion B ^y− , one having a structure represented by [LX _s ⁻¹ (OH)] ^y− can be preferably used. L, X, and s are the same as described above. Other anions that can be used include perchlorate ion (ClO ₄ ) ⁻ , trifluoromethyl sulfite ion (CF ₃ SO ₃ ) ⁻ , fluorosulfonate ion (FSO ₃ ) ⁻ , and toluenesulfone anion ion. And trinitrobenzenesulfonic acid anion.

Further, tetrakis (pentafluorophenyl) borate can also be preferably used as the anion ^By- .

In the present invention, it is particularly effective to use an aromatic onium salt among such onium salts. Among them, aromatic halonium salts described in JP-A-50-151997, JP-A-50-158680, JP-A-50-151997, JP-A-52-30899, JP-A-56-55420, Group VIA aromatic onium salts described in JP-A-55-125105 and the like, Group VA aromatic onium salts described in JP-A-50-158698, JP-A-56-8428, JP-A-56-149402 And oxosulfoxonium salts described in JP-A No. 57-192429, aromatic diazonium salts described in JP-A No. 49-17040, and thiopyrylium salts described in US Pat. No. 4,139,655 are preferable.

Among these aromatic onium salts, particularly preferable ones are listed below.
・ Compound having sulfonium cation with the following structure

In the formula, each of R ⁴⁶ to R ⁵⁹ may be the same or different, a hydrogen atom, a halogen atom, an oxygen atom or a hydrocarbon group that may contain a halogen atom, or an alkoxy group that may have a substituent, Ar is 1 It is a phenyl group in which the above hydrogen atoms may be substituted.

-Compounds with onium cations such as:
(Torcumyl) iodonium, bis (tertiarybutylphenyl) iodonium, triphenylsulfonium, and the like.

Specific compound names include, for example, 4- (4-benzoyl-phenylthio) phenyl-di- (4-fluorophenyl) sulfonium hexafluorophosphate, 4,4′-bis [bis ((β-hydroxyethoxy) Phenyl) sulfonio] phenyl sulfide-bis-hexafluorophosphate, 4,4′-bis [bis ((β-hydroxyethoxy) phenyl) sulfonio] phenyl sulfide-bis-hexafluoroantimonate, 4,4′-bis (difluoro) Phenylsulfonio) phenyl sulfide-bis-hexafluorophosphate, 4,4'-bis (difluorophenylsulfonio) phenyl sulfide-bis-hexafluoroantimonate, 4,4'-bis (phenylsulfonio) phenyl sulfide-bis - Hexafluorophosphate, 4,4′-bis (phenylsulfonio) phenyl sulfide-bis-hexafluoroantimonate, 4- (4-benzoylphenylthio) phenyl-di- (4- (β-hydroxyethoxy) phenyl) sulfonium Hexafluorophosphate, 4- (4-benzoylphenylthio) phenyl-di- (4- (β-hydroxyethoxy) phenyl) sulfonium hexafluoroantimonate, 4- (4-benzoylphenylthio) phenyl-di- (4- Fluorophenyl) sulfonium hexafluorophosphate, 4- (4-benzoylphenylthio) phenyl-di- (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (4-benzoylphenylthio) phenyl-diphenylsulfo Nium hexafluorophosphate, 4- (4-benzoylphenylthio) phenyl-diphenylsulfonium hexafluoroantimonate, 4- (phenylthio) phenyl-di- (4- (β-hydroxyethoxy) phenyl) sulfonium hexafluorophosphate, 4- (Phenylthio) phenyl-di- (4- (β-hydroxyethoxy) phenyl) sulfonium hexafluoroantimonate, 4- (phenylthio) phenyl-di- (4-fluorophenyl) sulfonium hexafluorophosphate, 4- (phenylthio) phenyl -Di- (4-fluorophenyl) sulfonium hexafluoroantimonate, 4- (phenylthio) phenyl-diphenylsulfonium hexafluorophosphate, 4- (phenylthio) pheny Ru-diphenylsulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium hexafluorophosphate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-Fluorophenyl) sulfonium hexafluoroantimonate, 4- (2-chloro-4-benzoylphenylthio) phenyldiphenylsulfonium hexafluorophosphate, 4- (2-chloro-4-benzoylphenylthio) phenyldiphenylsulfonium hexafluoro Antimonate, 4- (2-chloro-4-benzoylphenylthio) phenylbis (4-hydroxyphenyl) sulfonium hexafluorophosphate, 4- (2-chloro-4-benzoy) (Phenylthio) phenylbis (4-hydroxyphenyl) sulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate, (tolylcumyl) iodonium hexafluorophosphate, (tolylcumyl) iodonium hexafluoroantimonate, (tolylcumyl) ) Iodonium tetrakis (pentafluorophenyl) borate, bis (tertiarybutylphenyl) iodonium hexafluorophosphate, bis (tertiarybutylphenyl) iodonium hexafluoroantimonate, bis (tertiarybutylphenyl) iodonium tetrakis (pentafluorophenyl) borate , Benzyl-4-hydroxyphenylmethyls Fonium hexafluorophosphate, benzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, benzyldimethylsulfonium hexafluorophosphate, benzyldimethylsulfonium hexafluoroantimonate, p-chlorobenzyl-4-hydroxyphenylmethylsulfonium hexafluorophosphate, p -Chlorobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, 4-acetoxyphenyldimethylsulfonium hexafluorophosphate, 4-acetoxyphenyldimethylsulfonium hexafluoroantimonate, 4-methoxycarbonyloxyphenyldimethylsulfonium hexafluorophosphate, 4- Methoxycarbonyloxyphe Nyldimethylsulfonium hexafluoroantimonate, 4-ethoxycarbonyloxyphenyldimethylsulfonium hexafluorophosphate, 4-ethoxycarbonyloxyphenyldimethylsulfonium hexafluoroantimonate, α-naphthylmethyldimethylsulfonium hexafluorophosphate, α-naphthylmethyldimethylsulfonium hexa Fluoroantimonate, α-naphthylmethyltetramethylenesulfonium hexafluorophosphate, α-naphthylmethyltetramethylenesulfonium hexafluoroantimonate, cinnamyldimethylsulfonium hexafluorophosphate, cinnamyldimethylsulfonium hexafluoroantimonate, cinnamyltetramethylenesulfonium hexafluoro full Lophosphate, cinnamyltetramethylenesulfonium hexafluoroantimonate, N- (α-phenylbenzyl) cyanopyridinium hexafluorophosphate, N- (α-phenylbenzyl) -2-cyanopyridinium hexafluoroantimonate, N-cinnamyl- 2-cyanopyridinium hexafluorophosphate, N-cinnamyl-2-cyanopyridinium hexafluoroantimonate, N- (α-naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, N- (α-naphthylmethyl) -2-cyano There are pyridinium hexafluoroantimonate, N-benzyl-2-cyanopyridinium hexafluorophosphate, N-benzyl-2-cyanopyridinium hexafluoroantimonate, etc.

Other preferred photocationic polymerization initiators include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II ) -Tris (trifluoromethylsulfonyl) methanide and other iron / allene complexes, aluminum complexes / photolytic silicon compound initiators, and the like.

The cationic photopolymerization initiator (B) described above can be used singly or in combination of two or more, and the amount used is 100 weight of the entire cationic photocurable component (A). 1 to 10% by weight with respect to parts. When there are too few compounding quantities of a photocationic polymerization initiator (B), hardening of an adhesive agent will become inadequate and adhesive strength will fall. On the other hand, if the amount is too large, the ionic substance in the cured product increases, resulting in an increase in the hygroscopicity of the cured product and a decrease in the durability of the polarizing plate.

(Other components that can be blended in the photocurable adhesive composition)
A small amount of an organic solvent may be added to the photocurable adhesive composition in order to improve the coating suitability. The organic solvent is not particularly limited as long as it dissolves the photocurable adhesive composition well without deteriorating the optical performance of the polarizer. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used.

The photocurable adhesive composition may further contain a polymerizable monomer other than the alicyclic epoxy compound (A1) and the diglycidyl compound (A2). Examples of the polymerizable monomer include a cationic polymerizable monomer and a radical polymerizable monomer.

Examples of the cationic polymerizable monomer include oxetanes. Oxetanes are compounds having a 4-membered ring ether in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3 -Ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolac oxetane and the like. As these oxetane compounds, commercially available products can be easily obtained. For example, “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, and “Aron Oxetane OXT-211” are trade names. “Aron Oxetane® OXT-221”, “Aron Oxetane OXT-212” (above, manufactured by Toagosei Co., Ltd.), and the like.

The above-mentioned cationically polymerizable monomer has an effect of improving the adhesiveness after curing of the adhesive, and is used in a range that does not affect the weather resistance and the photocurability as necessary.

Examples of the radical polymerizable monomer include acrylate compounds, methacrylate compounds (hereinafter also referred to as (meth) acrylates in the meaning including both acrylates and methacrylates), allyl urethane compounds, unsaturated polyester compounds, and styrene compounds. It is done. When used in the photocurable adhesive of the present invention, (meth) acrylate is preferred because it is easily available and easy to handle. Examples of (meth) acrylates include urethane (meth) acrylates, (poly) ester (meth) acrylates, (poly) ether (meth) acrylates, alcohol (meth) acrylates, and other (meth) acrylates.

Here, the urethane (meth) acrylate exemplified as the (meth) acrylate compound is one or more (poly) ester polyols, (poly) ether polyols, polyols such as polyhydric alcohols, and (meth) acrylic acid. (Meth) acrylates obtained by reacting a hydroxyl group-containing (meth) acrylate that is an ester compound with one or more (poly) isocyanate compounds; one or more (poly) esters It is an ester compound having a urethane bond, such as a (meth) acrylate obtained by reacting a polyol such as polyol, (poly) ether polyol, polyhydric alcohol, etc., a hydroxyl group-containing (meth) acrylate and an isocyanate.

Examples of polyhydric alcohols for deriving (poly) ester polyols include 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, neopentyl glycol, polyethylene glycol, polypropylene Examples include glycol, polybutylene glycol, trimethylolpropane, glycerin, pentaerythritol, dipentaerythritol and the like. Examples of the polycarboxylic acid from which the (poly) ester polyol is derived include adipic acid, terephthalic acid, phthalic anhydride, trimellitic acid, trimesic acid, and the like.

Examples of the (poly) ether polyol include those obtained by adding an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide to the polyhydric alcohol described above. Examples of the (poly) isocyanate compound include monovalent or divalent isocyanates, and divalent or higher isocyanates are preferred.

Divalent or higher isocyanates include 2,4- and / or 2,6-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, 3 , 3′-dimethyldiphenyl-4,4′-diisocyanate, dianisidine diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, trans and / or cis-1,4-cyclohexane diisocyanate, Norbornene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4 and / or (2,4,4) -trimethylhexamethylene diisocyanate, Diisocyanate, triphenylmethane triisocyanate, 1-methyl-benzol-2,4,6-triisocyanate, dimethyl triphenylmethane tetra isocyanate.

(Poly) ester (meth) acrylate is an ester compound of (poly) ester having (one) or two or more hydroxyl groups in the molecule and (meth) acrylic acid. (Poly) ester having one or more hydroxyl groups in the molecule is an ester compound of one or more polyhydric alcohols and one or more monocarboxylic acids or polycarboxylic acids. Is mentioned.

Examples of the polyhydric alcohol for deriving a (poly) ester having one or more hydroxyl groups in the molecule include the same compounds as described above, and examples of the monocarboxylic acid include formic acid, acetic acid, and propionic acid. Butyric acid, isobutyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, benzoic acid and the like. Examples of the polycarboxylic acid include the same compounds as those described above.

(Poly) ether (meth) acrylate is an ester compound of (poly) ether and (meth) acrylic acid having one or more hydroxyl groups in the molecule. As (poly) ether having one or more hydroxyl groups in the molecule, one or more alkylene oxides are added to 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, polyhydric alcohol What is obtained by doing. Examples of the polyhydric alcohol and alkylene oxide include the same compounds as those described above. Specifically, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, propylene Examples thereof include oxide-modified trimethylolpropane tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate.

Alcohol (meth) acrylate is an ester compound of alcohol (particularly aliphatic alcohol or aromatic alcohol) having one or two or more hydroxyl groups in the molecule and (meth) acrylate. For example, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isooctyl (meth) Acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, etc.

Other acrylates include ε-caprolactone-modified dipentaerythritol hexa (meth) acrylate, fluorene derivative di (meth) acrylate, carbazole derivative di (meth) acrylate, and the like.

The above radical polymerizable monomer can be used to adjust the curing rate.
When a radical polymerizable monomer is used as the polymerizable monomer, a radical photopolymerization initiator is also blended. Examples of the photo radical polymerization initiator include ketone compounds such as acetophenone compounds, benzyl compounds, benzophenone compounds, and thioxanthone compounds.

Examples of acetophenone compounds include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4′-isopropyl-2-hydroxy-2-methylpropiophenone, 2-hydroxymethyl- 2-methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, p-dimethylaminoacetophenone, P-tertiarybutyldichloroacetophenone, p-tertiarybutyltrichloroacetophenone, p-azidoben Salacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) ) -Butanone-1, Be Examples include zoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, and benzoin isobutyl ether. Examples of benzyl compounds include benzyl and anisyl. Examples of benzophenone compounds include: Examples include benzophenone, methyl o-benzoylbenzoate, Michler's ketone, 4,4′-bisdiethylaminobenzophenone, 4,4′-dichlorobenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, and the thioxanthone compound includes 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone And the like.

These radical photopolymerization initiators can be used alone or in combination of two or more according to the desired performance, and preferably 0.05 to 10% by mass with respect to the radical polymerizable monomer. More preferably, it is blended in an amount of 0.1 to 10% by mass. When the blending amount of the radical photopolymerization initiator with respect to the radical polymerizable monomer is 0.05% by mass or more, the curing of the photocurable adhesive can proceed more favorably, and when the blending amount is 10% by mass or less, The physical strength of the adhesive layer formed by curing the photocurable adhesive of the invention is good.

The compound used as the polymerizable monomer may be one type or a mixture of two or more types. When the photocurable adhesive contains a polymerizable monomer other than the alicyclic epoxy compound (A1) and the diglycidyl compound (A2), the amount of the polymerizable monomer used is the aforementioned alicyclic epoxy compound (A1) 100. The amount is preferably 100 parts by weight or less with respect to parts by weight. When the usage-amount of a polymerizable monomer is 100 weight part or less, when producing a polarizing plate using this photocurable adhesive agent, the adhesive strength of a polarizer and a protective film can be maintained favorable. The amount of the polymerizable monomer used relative to 100 parts by weight of the alicyclic epoxy compound (A1) is more preferably 5 parts by weight or more, and in this case, the modification effect by the polymerizable monomer can be obtained well. The amount of the polymerizable monomer used is more preferably 50 parts by weight or less.

Furthermore, this photo-curable adhesive can contain various additive components as long as the effects of the present invention are not impaired. As an additive component, in addition to the above-mentioned photo radical polymerization initiator, photosensitizer, thermal cationic polymerization initiator, polyols, ion trapping agent, antioxidant, light stabilizer, chain transfer agent, sensitizer, A tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, a leveling agent, a dye, an organic solvent, and the like can be blended.

When the additive component is contained, the amount used is preferably 1000 parts by weight or less with respect to 100 parts by weight of the alicyclic epoxy compound (A1). When the amount used is 1000 parts by weight or less, the combination of at least the alicyclic epoxy compound (A1), the diglycidyl compound (A2) and the photocationic polymerization initiator (B), which are essential components of the photocurable adhesive, The effects of improving storage stability, preventing discoloration, improving curing speed, and ensuring good adhesion can be exhibited well.

[Polarizer]
A polarizer and a protective film are bonded using the photocurable adhesive composition as described above to produce a polarizing plate. There is no particular limitation on the method of applying the photocurable adhesive between the polarizer and the protective film. 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, after dropping the above-mentioned photocurable adhesive between the polarizer and the protective film, it is also possible to use a method of applying pressure by a roll or the like and spreading it uniformly. Here, it is possible to use metal, rubber, or the like as the material of the roll. A material obtained by dripping the photocurable adhesive between the polarizer and the protective film is pressed between the rolls and pressed. When spreading, these rolls may be made of the same material or different materials. The thickness of the adhesive layer is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less.

A transparent protective film is bonded onto the adhesive layer thus formed of the photocurable adhesive. The protective film used here is not particularly limited, and specifically, an acetylcellulose-based film such as triacetylcellulose, which is currently most widely used as a protective film for polarizing plates, or a transparent material having lower moisture permeability than triacetylcellulose. Resin films can be used. Moisture permeability of triacetyl cellulose is approximately 400g / m ² / 24hr approximately. When bonding a protective film on both surfaces of a polarizer, two protective films may be bonded one step at a time, or both surfaces may be bonded in one step.

Examples of the acetylcellulose film used in the present invention include diacetylcellulose film and acetylbutylcellulose film in addition to the above-mentioned triacetylcellulose film.

Examples of transparent resin films with low moisture permeability used in the present invention include amorphous polyolefin resin films, polyester resin films, acrylic resin films, polycarbonate resin films, polysulfone resin films, and alicyclic polyimide resin films. Etc. Among these, a film made of an amorphous polyolefin resin is particularly preferably used. The amorphous polyolefin-based resin usually has a cyclic olefin polymerization unit such as norbornene or a polycyclic norbornene-based monomer, and may be a copolymer of a cyclic olefin and a chain olefin. Among them, a thermoplastic saturated norbornene resin is representative. Those having a polar group introduced are also effective. Commercially available amorphous polyolefin resins include “Arton” from JSR Corporation, “ZEONEX” and “ZEONOR” from Nippon Zeon Co., Ltd., “APO” and “Apel” from Mitsui Chemicals, Inc. There is. An amorphous polyolefin-based resin is formed into a film, and a known method such as a solvent casting method or a melt extrusion method is appropriately used for forming the film.

In the present invention, one preferred form, the protective film is one having the following moisture permeability 300g / m ² / 24hr consisting amorphous polyolefin resin.

When a protective film is bonded to both sides of the polarizer, both may be the same type or different types. When different types of protective films are bonded to both sides of the polarizer, the above-mentioned amorphous polyolefin resin film, polyester resin film, acrylic resin film, polycarbonate resin film, polysulfone are used as one protective film. Resin films with low moisture permeability such as olefin resin films and alicyclic polyimide resin films can be used, and as the other protective film, in addition to these, the aforementioned triacetyl cellulose film, diacetyl cellulose film and acetyl butyl cellulose A cellulose acetate film such as a film can also be used. Further, when a protective film made of a resin film having a relatively high moisture permeability such as a cellulose acetate film is provided on one surface of the polarizer in this way, the bonding surface of the resin film having a high moisture permeability is made of polyvinyl chloride. Adhesives other than epoxy-based adhesives such as alcohol-based adhesives may be used.

The protective film may be subjected to easy adhesion treatment such as saponification treatment, corona treatment, primer treatment, anchor coating treatment on the bonding surface prior to bonding to the polarizer. Moreover, you may have various process layers, such as a hard-coat layer, an antireflection layer, and a glare-proof layer, in the surface on the opposite side to the bonding surface to the polarizer of a protective film. The thickness of the protective film is usually in the range of about 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm.

As described above, the polarizer having the protective film bonded to the polarizer through the uncured adhesive layer is then irradiated with active energy rays to cure the adhesive layer made of the epoxy resin composition. The protective film is fixed on the polarizer.

The light source of the active energy ray is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp Etc. can be used. The light irradiation intensity to the epoxy resin composition is determined for each target composition and is not particularly limited, but the irradiation intensity in the wavelength region effective for activation of the initiator is 0.1 to It is preferably 100 mW / cm ² . If the light irradiation intensity to the resin composition is less than 0.1 mW / cm ² , the reaction time becomes too long, and if it exceeds 100 mW / cm ² , it is caused by heat radiated from the lamp and heat generated during polymerization of the composition. In addition, yellowing of the epoxy resin composition and deterioration of the polarizer may occur. The light irradiation time to the composition is controlled for each composition to be cured and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5,000 mJ / cm. It is preferably set to be ² . When the integrated light quantity to the epoxy resin composition is less than 10 mJ / cm ² , the generation of active species derived from the initiator is not sufficient, and the resulting protective film may be insufficiently cured, If the integrated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity.

In curing the photocurable adhesive by irradiation with active energy rays, it is possible to cure the polarizing plate within a range in which various functions of the polarizing plate such as the degree of polarization, transmittance and hue of the polarizer, and transparency of the protective film are not deteriorated. preferable.

[Laminated optical member]
When using a polarizing plate, it can also be set as the optical member which provided the optical layer which shows optical functions other than a polarizing function through the protective film layer of this invention. For the optical layer laminated on the polarizing plate for the purpose of forming an optical member, for example, formation of a liquid crystal display device such as a reflective layer, a transflective reflective layer, a light diffusing layer, a retardation plate, a light collector, a brightness enhancement film, etc. There are some that are used. The reflective layer, the semi-transmissive reflective layer, and the light diffusing layer are used when forming an optical member comprising a reflective or semi-transmissive or diffusive polarizing plate.

The reflection-type polarizing plate is used in a liquid crystal display device of a type that reflects incident light from the viewing side and displays the light source such as a backlight, so that the liquid crystal display device can be easily thinned. The transflective polarizing plate is used in a liquid crystal display device of a type in which a reflective type is used in a bright place and a light source such as a backlight is used in a dark place. The optical member as a reflective polarizing plate can form a reflective layer, for example, by attaching a foil or a vapor deposition film made of a metal such as aluminum to a protective film on a polarizer. The optical member as a transflective polarizing plate can be formed by using the reflecting layer as a half mirror or by adhering a reflecting plate containing a pearl pigment or the like and exhibiting light transmittance to the polarizing plate. On the other hand, optical members as diffusion type polarizing plates can be applied to various methods such as a method of performing a mat treatment on a protective film on a polarizing plate, a method of applying a resin containing fine particles, and a method of adhering a film containing fine particles. Use to form a fine relief structure on the surface.

Furthermore, the formation of an optical member as a polarizing plate for both reflection and diffusion can be performed by, for example, a method of providing a reflective layer reflecting the concavo-convex structure on the fine concavo-convex structure surface of the diffusive polarizing plate. The reflective layer having a fine concavo-convex structure has advantages such that incident light is diffused by irregular reflection, directivity and glare can be prevented, and unevenness in brightness and darkness can be suppressed. In addition, the resin layer or film containing fine particles has an advantage that incident light and its reflected light are diffused when passing through the fine particle-containing layer, and uneven brightness can be further suppressed. The reflective layer reflecting the surface fine concavo-convex structure can be formed, for example, by attaching a metal directly to the surface of the fine concavo-convex structure by a method such as vacuum deposition, ion plating, sputtering, or other vapor deposition or plating. Examples of the fine particles to be blended to form the surface fine concavo-convex structure include silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle size of 0.1 to 30 μm. Inorganic fine particles and organic fine particles made of a crosslinked or uncrosslinked polymer can be used.

On the other hand, the above-mentioned retardation plate as an optical layer is used for the purpose of compensation of retardation by a liquid crystal cell. Examples thereof include a birefringent film made of a stretched film of various plastics, a film in which a discotic liquid crystal or a nematic liquid crystal is aligned and fixed, and a film substrate on which the above liquid crystal layer is formed. In this case, a cellulose-based film such as triacetyl cellulose is preferably used as the film substrate that supports the oriented liquid crystal layer.

Examples of the plastic forming the birefringent film include polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polyolefin such as polypropylene, polyarylate, and polyamide. The stretched film may be processed by an appropriate method such as uniaxial or biaxial. Moreover, the birefringent film which controlled the refractive index of the thickness direction of a film by applying shrinkage force and / or extending | stretching force under adhesion | attachment with a heat-shrinkable film may be sufficient. Note that two or more retardation plates may be used in combination for the purpose of controlling optical characteristics such as broadening the bandwidth.

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

The brightness enhancement film is used for the purpose of improving the brightness in a liquid crystal display device or the like. For example, a plurality of thin film films having different refractive index anisotropies are laminated to make the reflectance anisotropy. Examples thereof include a reflection-type polarization separation sheet designed to occur, a cholesteric liquid crystal polymer alignment film, and a circular polarization separation sheet in which the alignment liquid crystal layer is supported on a film substrate.

The optical member is composed of a polarizing plate and one or more layers selected according to the purpose of use from the above-described reflective layer or transflective reflective layer, light diffusing layer, phase difference plate, light collector, brightness enhancement film, and the like. It can be combined with an optical layer to form a laminate of two layers or three or more layers. In that case, two or more optical layers such as a light diffusion layer, a retardation plate, a light collector, and a brightness enhancement film may be arranged. In addition, there is no limitation in particular in arrangement | positioning of each optical layer.

The various optical layers forming the optical member are integrated using an adhesive, but the adhesive used for this purpose is not particularly limited as long as the adhesive layer is satisfactorily formed. It is preferable to use a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoint of easy bonding work and prevention of optical distortion. As the pressure-sensitive adhesive, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether or the like as a base polymer can be used. Above all, like acrylic adhesives, it has excellent optical transparency, retains appropriate wettability and cohesion, has excellent adhesion to substrates, and has weather resistance and heat resistance. It is preferable to select and use one that does not cause peeling problems such as floating and peeling under the conditions of heating and humidification. In acrylic adhesives, alkyl esters of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl, ethyl and butyl groups, and (meth) acrylic acid and hydroxyethyl (meth) acrylate An acrylic copolymer having a weight average molecular weight of 100,000 or more, in which a glass transition temperature is preferably 25 ° C. or less, more preferably 0 ° C. or less, and a functional group-containing acrylic monomer comprising 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 directly applied on the polarizing plate. This can be done by a method of forming a pressure-sensitive adhesive layer by coating or a method of forming a pressure-sensitive adhesive layer by previously forming a pressure-sensitive adhesive layer on a protective film and transferring it onto a polarizing plate. Can do. The thickness of the pressure-sensitive adhesive layer is determined according to the adhesive force and the like, but a range of about 1 to 50 μm is appropriate.

In addition, the adhesive layer may contain fillers made of glass fibers, glass beads, resin beads, metal powders and other inorganic powders, pigments, colorants, antioxidants, UV absorbers, etc. as necessary. May be. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.

The optical member can be arranged on one side or both sides of the liquid crystal cell. The liquid crystal cell to be used is arbitrary. For example, a liquid crystal display device using various liquid crystal cells such as an active matrix drive type represented by a thin film transistor type and a simple matrix drive type represented by a super twisted nematic type. Can be formed. The optical members provided on both sides of the liquid crystal cell may be the same or different.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. First, the reference example which produced the polyethylene terephthalate film with an anti-glare layer used as one protective film of a polarizer is shown.

[Reference Example] (Preparation of polyethylene terephthalate film with antiglare layer)
Each of the following components was dissolved in ethyl acetate at a solid content concentration of 60%, and an ultraviolet curable resin composition giving a refractive index of 1.53 after curing was prepared.

Pentaerythritol triacrylate 60 parts Polyfunctional urethanized acrylate ^* 40 parts ^* Polyfunctional urethanized acrylate: Reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate.

Next, 2 parts of porous silica particles [trade name “Silicia”, manufactured by Fuji Silysia Chemical Co., Ltd.] are added to 100 parts of the solid content of the ultraviolet curable resin composition and 2, 4 which are photopolymerization initiators. 5,6-Trimethylbenzoyldiphenylphosphine oxide (trade name “Lucirin TPO”, manufactured by BASF) was added to prepare a coating solution for an antiglare layer.

This coating solution is applied to the surface (surface made of polyethylene terephthalate itself) that has an easy-adhesion layer on one side and is not provided with a 38 μm thick biaxially stretched polyethylene terephthalate film. A resin composition layer was formed and dried for 3 minutes in a dryer set at 80 ° C. From the UV curable resin composition layer side of the dried film, the light from the high-pressure mercury lamp is irradiated at a UVA (315 to 400 nm) wavelength so that the illuminance is 250 mW / cm ² and the integrated light quantity is 300 mJ / cm ^2. Then, the ultraviolet curable resin composition layer was cured to obtain an antiglare film comprising a laminate of a 5 μm thick antiglare layer (cured resin) having irregularities on the surface and a biaxially stretched polyethylene terephthalate film. When the haze value of this antiglare film was measured using a haze / transmittance meter “HM-150” (Murakami Color Research Laboratory Co., Ltd.), a haze value of 10% was obtained.

Next, Examples and Comparative Examples in which a photocurable adhesive composition was prepared and applied to the production of a polarizing plate are shown. The photocationic curable component and the photocationic polymerization initiator used in the following examples are as follows, and are represented by the following symbols.

(A) Photocationic curable component (A1) Alicyclic epoxy compound a1: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (A2) Diglycidyl compound a21: 1,4-butanediol diglycidyl ether ( Chlorine content 0.5%)
a21c: 1,4-butanediol diglycidyl ether (chlorine content 8.0%)
a22: Neopentyl glycol diglycidyl ether (chlorine content 0.5%)
a22c: neopentyl glycol diglycidyl ether (chlorine content 8.1%)
a23: cyclohexanedimethanol diglycidyl ether (chlorine content 0.4%)
a23c: cyclohexanedimethanol diglycidyl ether (chlorine content 7.7%)
(B) Photocationic polymerization initiator (abbreviated as “initiator” in the table)
(B1) Triarylsulfonium hexafluorophosphate [Examples 1 to 6 and Comparative Examples 1 to 5]
(1) Preparation of a photocurable adhesive composition A photocationic curable component and a photocationic polymerization initiator were mixed in the blending ratios shown in Table 1, respectively, and then defoamed to prepare a photocurable adhesive solution. did. In addition, a photocationic polymerization initiator (b1) was mix | blended as a 50% propylene carbonate solution, and displayed in Table 1 with the solid content.

(2) Measurement of chlorine concentration of pre-curing adhesive The chlorine concentration contained in each adhesive solution prepared above was measured as follows. That is, first, each adhesive solution is decomposed with a combustion device “TOX-100” (manufactured by Dia Instruments Co., Ltd.), gas is collected in an absorbing solution, and then an ion chromatograph device “ICS-2000” (manufactured by Dionex). ) And the chlorine concentration was calculated from the amount of the adhesive solution used for the initial decomposition. The respective chlorine concentration measurement results are shown in Table 1.

(3) Measurement of storage elastic modulus at 80 ° C. of cured product On one side of a polyethylene terephthalate film (trade name “Toyobo Ester Film E7002”, manufactured by Toyobo Co., Ltd.) having no easy-adhesion layer on the surface, a coating machine [ Using a bar coater manufactured by Daiichi Rika Co., Ltd.], each adhesive solution prepared in the above (1) was applied so that the film thickness after curing was about 25 μm. Next, the adhesive was cured by irradiating with ultraviolet rays so that the integrated light amount was 3000 mJ / cm ² by a “D bulb” manufactured by Fusion UV Systems. This was cut into a size of 5 mm × 30 mm, and the polyethylene terephthalate film was peeled off to obtain a cured film of an adhesive. Then, using a dynamic viscoelasticity measuring device “DVA-220” manufactured by IT Measuring Instruments Co., Ltd., the cured film obtained above is gripped with a gripping tool spacing of 2 cm so that its long side is in the pulling direction. The storage elastic modulus at a temperature of 80 ° C. was determined by setting the frequency of tension and shrinkage to 1 Hz and the temperature rising rate of 3 ° C./min. The results are shown in Table 1.

(4) Preparation of polarizing plate Corona discharge treatment was applied to the surface of an 80 μm-thick triacetyl cellulose film (trade name “Fujitac”, manufactured by Fuji Film Co., Ltd.) containing an ultraviolet absorber. Using a bar coater, each adhesive solution prepared in the above (1) was applied so that the film thickness after curing was about 3 μm. A polyvinyl alcohol-iodine polarizer was bonded to the adhesive layer. On the other hand, a corona discharge treatment was applied to the surface opposite to the antiglare layer of the 43 μm-thick biaxially stretched polyethylene terephthalate film having an antiglare layer produced in the reference example (the surface of the easy adhesion layer), The same adhesive solution as above was applied with a bar coater so that the film thickness after curing was about 3 μm. The adhesive layer was bonded to the polarizer side of the polarizer having the triacetylcellulose film prepared above bonded on one side, to prepare a laminate. From the biaxially stretched polyethylene terephthalate film side having the antiglare layer of this laminate, an integrated light quantity is set to 750 mJ / cm ² by a “D bulb” manufactured by Fusion UV Systems using a UV irradiation device with a belt conveyor. The adhesive was cured by irradiating with UV rays. Thus, a polarizing plate in which protective films were bonded to both sides of the polarizer was produced.

(5) Evaluation of durability of polarizing plate by thermal shock test The polarizing plate prepared in (4) above was cut into a size of 170 mm × 110 mm, and an acrylic pressure-sensitive adhesive layer having a thickness of 25 μm was provided on the triacetyl cellulose film side. The pressure-sensitive adhesive layer was attached to a glass plate, and a cold shock test (heat shock test) was performed. In the thermal shock test, the operation of holding the polarizing plate sample bonded to the above glass plate at −35 ° C. for 1 hour, then raising the temperature to 70 ° C. and holding it for 1 hour is defined as one cycle. This was done by repeating 30 cycles. This test was performed for each of the 6 polarizing plate samples, and evaluation was made based on the ratio of the number of samples (6) to which the cracks were observed in the polarizer after the test. The results are shown in Table 1.

As shown in Table 1, in the photocurable adhesive composition in which the alicyclic epoxy compound (A1) in the photocationic curable component (A) is 50 to 60% and the diglycidyl compound (A2) is 50 to 40%. As the diglycidyl compound (A2), 1,4-butanediol diglycidyl ether (a21c), neopentyl glycol diglycidyl ether (a22c), or cyclohexanedimethanol diglycidyl ether (a23c) having a high chlorine content is used. In Comparative Examples 2 to 5, the cured product of the adhesive showed only a low storage elastic modulus, and when it was used as a polarizing plate, the polarizer was easily broken by a thermal shock test.

On the other hand, Examples using 1,4-butanediol diglycidyl ether (a21), neopentyl glycol diglycidyl ether (a22), or cyclohexanedimethanol diglycidyl ether (a23), all having a reduced chlorine content In Nos. 1 to 6, it was confirmed that the cured product of the adhesive combined with the alicyclic epoxy compound (A1) exhibits a high storage elastic modulus and can effectively prevent the polarizer from cracking when used as a polarizing plate.

The adhesive of Comparative Example 1 in which 1,4-butanediol diglycidyl ether (a21) having a low chlorine content was used, and the blending amount was 50% in the photocationic curable component (A). The cured product had a low storage elastic modulus, and when it was used as a polarizing plate, the polarizer was easily broken by a thermal shock test. Thus, depending on the type of the diglycidyl compound (A2), even if the chlorine content is reduced, the diglycidyl compound (A2) in the photocationically curable component (A) is cured when the blending amount is close to 50%. The product may not give a sufficient storage elastic modulus, but as specified in the present invention, the alicyclic epoxy compound (A1) and the diglycidyl compound so that the cured product exhibits a storage elastic modulus of 1000 MPa or more at 80 ° C. It can be seen that (A2) may be combined.

In Examples 1 to 6, the amount of the alicyclic epoxy compound (A1 = a1) in the photocationic curable component (A) is increased to 70% or 80%, and the remainder is a diglycidyl compound (a21, low chlorine content). If it is a22 or a23), the viscosity of the adhesive liquid will rise correspondingly, but it will be suppressed to such a viscosity that it can be applied at room temperature, and the cured product will give a high storage elastic modulus. As a result, cracking of the polarizer can be effectively prevented.

Claims

Polarized light composed of a polarizer composed of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented, and a protective film composed of a transparent resin bonded to at least one surface of the polarizer via an adhesive A board,
The adhesive is
100 parts by weight of the photocationically curable component (A),
Containing 1 to 10 parts by weight of the cationic photopolymerization initiator (B),
The photocationic curable component (A) is based on the total amount thereof.
50 to 95% by weight of the alicyclic epoxy compound (A1) having two or more epoxy groups in the molecule, at least one of which is bonded to the alicyclic ring, and 1% by weight of chlorine %, And the following formula (I):

(In the formula, Z is an alkylene group having 1 to 9 carbon atoms, an alkylidene group having 3 or 4 carbon atoms, a divalent alicyclic hydrocarbon group, or a formula —C m H 2m —Z 1 —C n H 2n — In which —Z 1 — represents —SO 2 —, —SO— or —CO—, and m and n each independently represents an integer of 1 or more. The total is 9 or less.)
A polarizing plate comprising 5 to 50% by weight of the diglycidyl compound (A2) represented by the formula (II), and a cured product thereof formed from a photocurable adhesive composition having a storage modulus of 1000 MPa or more at 80 ° C.
The polarizing plate according to claim 1, wherein the protective film bonded to at least one surface of the polarizer is made of an acetylcellulose-based resin.
The protective film bonded to at least one surface of the polarizer is made of a transparent resin selected from the group consisting of an amorphous polyolefin resin, a polyester resin, a polycarbonate resin, and a chain polyolefin resin. The polarizing plate as described.
A protective film made of acetyl cellulose resin is bonded to one surface of the polarizer via the adhesive, and an amorphous polyolefin resin, polyester resin, polycarbonate resin and the other surface of the polarizer The polarizing plate of Claim 1 by which the protective film which is a film which consists of transparent resin chosen from the group which consists of chain | strand-shaped polyolefin resin is bonded through the said adhesive agent.
A laminated optical member comprising a laminate of the polarizing plate according to claim 1 and another optical layer.
The laminated optical member according to claim 5, wherein the optical layer includes a retardation film.