KR20140029414A - Laminate optical member and polarizing plate using photocurable adhesive - Google Patents

Abstract

A polarizing plate composed of a polyvinyl alcohol polarizer and a transparent protective film bonded to the polarizer via an adhesive, the adhesive comprising 100 parts by weight of the photocationic curable component (A) and the photocationic polymerization initiator (B). 1-10 weight part contains and the photocationic curable component (A) is formed with the photocurable adhesive agent containing the following amounts based on the total amount of the following (A1)-(A3). 30 to 85 weight% of alicyclic diepoxy compound (A1) represented by following formula (I); 1 to 69% by weight of a diglycidyl compound (A2) having a branched structure represented by the following Formula (II); And 1 to 69% by weight of the monofunctional epoxy compound (A3) represented by the following Formula (III). When the said protective film is immersed in the said photocurable adhesive agent at 23 degreeC for 2 days, the weight reduction of a protective film is 0 to 30 weight%.

Description

Polarizing plate and laminated optical member using a photocurable adhesive {LAMINATE OPTICAL MEMBER AND POLARIZING PLATE USING PHOTOCURABLE ADHESIVE}

This invention is a polarizing plate in which the protective film which consists of transparent resin was bonded to the polarizer which consists of a polyvinyl alcohol-type resin film in which the dichroic dye was adsorbed-oriented, and through a photocurable adhesive agent, and its polarizing plate It relates to the laminated optical member formed by laminating | stacking other optical layers, such as retardation film, on the back side.

The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate usually has a structure in which protective films are laminated on both surfaces of the polarizer, and is mounted on the liquid crystal display device. It is also known to form a protective film only on one side of the polarizer, but in many cases, a layer having another optical function is bonded to the other surface as a protective film instead of a simple protective film. Moreover, as a manufacturing method of a polarizer, the method of carrying out boric acid treatment of the uniaxially-stretched polyvinyl alcohol-type resin film dyed with the dichroic dye, and washing with water, and drying is widely employ | adopted.

Usually, a protective film is bonded immediately to the polarizer immediately after the above-mentioned water washing and drying. This is because the polarizer after drying has a weak physical strength, and once this is wound, it tends to tear in the processing direction. Therefore, normally, the water-based adhesive agent which is the aqueous solution of polyvinyl alcohol-type resin is apply | coated to the polarizer after drying immediately, and a protective film is simultaneously bonded to both surfaces of a polarizer through this adhesive agent. Conventionally, the triacetyl cellulose film of thickness 30-100 micrometers is used as a protective film.

The protective film that triacetyl cellulose is excellent in transparency, easy to form various surface treatment layers and optical functional layers, and has high moisture permeability, and can dry smoothly after bonding to a polarizer using the above-mentioned water-based adhesive agent. On the other hand, due to the high moisture permeability, the polarizing plate pasted as a protective film has a problem such as deterioration under moist heat, for example, under conditions such as a temperature of 70 ° C. and a relative humidity of 90%. there was. Therefore, it is also known to use amorphous polyolefin resin which has lower moisture permeability than triacetyl cellulose, for example, norbornene-type resin as a representative example as a protective film.

When bonding the protective film which consists of resin with low moisture permeability to a polyvinyl alcohol-type polarizer, if it uses the aqueous solution of the polyvinyl alcohol-type resin generally used for pasting of a polyvinyl alcohol-type polarizer and a triacetyl cellulose film as an adhesive agent, it will adhere | attach There was a problem that the strength was not sufficient or the appearance of the resulting polarizing plate was poor. This is because the resin film with low water vapor transmission rate is generally hydrophobic, or the water cannot be sufficiently dried as a solvent because of low water vapor transmission rate. On the other hand, it is also known to bond different types of protective films on both surfaces of a polarizer. For example, a protective film made of a resin having low moisture permeability, such as amorphous polyolefin resin, is bonded to one surface of the polarizer, and the other surface of the polarizer is made of resin having high moisture permeability such as cellulose resin such as triacetyl cellulose. There is also a proposal to bond a protective film.

Therefore, as an adhesive agent that provides high adhesion between a protective film made of a resin having a low moisture permeability and a polyvinyl alcohol polarizer, and also provides a high adhesion force between a high moisture-permeable resin such as a cellulose resin and a polyvinyl alcohol polarizer, Attempts have been made to use photocurable adhesives. For example, Japanese Unexamined Patent Application Publication No. 2004-245925 (Patent Document 1) discloses an adhesive mainly containing an epoxy compound that does not contain an aromatic ring, and is known by irradiation of active energy rays, specifically by irradiation with ultraviolet rays. It is proposed to harden this adhesive agent by cationic polymerization and to adhere | attach a polarizer and a protective film. In JP 2008-257199 A (Patent Document 2), an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group are combined, and a photocurable adhesive containing a photocationic polymerization initiator is further added to a polarizer. A technique used for bonding a protective film is disclosed.

Japanese Unexamined Patent Publication No. 2004-245925 Japanese Unexamined Patent Publication No. 2008-257199

However, the adhesive of the composition specifically disclosed by patent document 1 or patent document 2 does not necessarily become low enough, but is easy to apply to a polarizer or a protective film bonded to it, and to form a thin film and a uniform adhesive bond layer easily. Did not. Moreover, some of these adhesive agents may dissolve a protective film, and the dissolution may be a cause and may be a bubble defect.

The subject of this invention is providing the polarizing plate with which the polarizer and the protective film were bonded using the photocurable adhesive which has a sufficiently low viscosity which can be apply | coated at room temperature, and does not melt a protective film when bonding a protective film to a polarizer. Another object of this invention is to laminate | stack another optical layer, such as retardation film, on this polarizing plate, and to provide the laminated optical member used suitably for a liquid crystal display device.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve such a subject, this inventor came to complete this invention. Specifically, in the photocurable adhesive agent formed by mix | blending a predetermined amount of photocationic polymerization initiator with a photocationic curable component, as this photocationic curable component, a specific alicyclic diepoxy compound mainly makes it alicyclic type The epoxy group which has two epoxy groups which are not bonded to a ring in a molecule | numerator, the linking group mix | blends the divalent group diglycidyl compound which has a branched structure like a branched alkylene group, and is not bonded to an alicyclic ring further It was found that it is effective to use the composition which mix | blended a small amount of the monofunctional epoxy compound which has one in it. That is, the photocurable adhesive agent of such a specific composition has a small ability to dissolve a protective film, exhibits a low viscosity at room temperature, provides good coating aptitude, and firmly adheres the polarizer and the protective film after curing. Figured out. The present invention includes the following.

[1] A polarizing plate comprising a polarizer made of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented, and a protective film made of a transparent resin bonded to at least one surface of the polarizer via an adhesive, the 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 photocationic curable component (A) includes the following (A1) and (A2): ) And (A3) formed of a photocurable adhesive containing the following amounts based on the total amount thereof, and when the protective film is immersed in the photocurable adhesive at 23 ° C. for 2 days, the weight of the protective film decreases. The polarizing plate is 0-30 weight%.

30 to 85 weight% of alicyclic diepoxy compound (A1) represented by following formula (I);

[Chemical Formula 1]

In the formula, each of R ¹ and R ² independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, but when the alkyl group is 3 or more carbon atoms, it may have an alicyclic structure; X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (Ia) to (Id):

(2)

A divalent group represented by any of the above, wherein Y ¹ to Y ⁴ each represent an alkanediyl group having 1 to 20 carbon atoms, but in the case of having 3 or more carbon atoms, may have an alicyclic structure; a and b represent the integer of 0-20, respectively.

1 to 69 weight% of the diglycidyl compound (A2) represented by following formula (II);

(3)

In the formula, Z represents a dialkyl group having 3 to 8 carbon atoms or a divalent group represented by the formula -C _m H _2m -Z ¹ -C _n H _2n- , wherein -Z ¹ -represents -O-, -CO- O- or -O-CO-, one of m and n represents an integer of 1 or more, the other represents an integer of 2 or more, but the sum of both is 8 or less, and one of C _m H _2m and C _n H _2n A branched divalent saturated hydrocarbon group is shown.

1 to 69 wt% of the monofunctional epoxy compound (A3) represented by the following formula (III);

[Chemical Formula 4]

In formula, R <^3> represents a C1-C15 alkyl group.

[2] The polarizing plate according to [1], wherein in the formula (III) representing the monofunctional epoxy compound (A3), R ³ is an alkyl group having 6 to 10 carbon atoms.

[3] The polarizing plate according to [1] or [2], wherein the photocurable adhesive has a viscosity at 25 ° C. of 100 mPa · sec or less.

[4] The polarizing plate according to any one of [1] to [3], wherein the photocurable adhesive is cured.

[5] The polarizing plate according to any one of [1] to [4], wherein the protective film bonded to at least one surface of the polarizer is made of acetylcellulose-based resin in which an ultraviolet absorber is blended.

[6] The protective film bonded to at least one surface of the polarizer is any one of [1] to [4] made of a transparent resin selected from the group consisting of amorphous polyolefin resins, polyester resins and chain polyolefin resins. The polarizing plate of description.

[7] A laminated optical member comprising a laminate of the polarizing plate according to any one of [1] to [6] and another optical layer.

[8] The laminated optical member according to [7], wherein the other optical layer contains a retardation film.

In this invention, as a photocationic curable component (A) which becomes a main component of the photocurable adhesive agent which bonds a polarizer and a protective film, a bivalent group which has a branched structure in an alicyclic diepoxy compound (A1) and a connector, typically a branching By using the diglycidyl compound (A2) and monofunctional epoxy compound (A3) which respectively have a predetermined amount which mixed alkylene, the photocurable adhesive agent is low-viscosity, does not melt a protective film well, and is room temperature The viscosity at is also low, and the coating aptitude is excellent. Therefore, by bonding the protective film which consists of transparent resin to at least one surface of a polarizer through this photocurable adhesive agent, the bubble defect resulting from the dissolution of a protective film is drastically reduced, and the adhesiveness of a polarizer and a protective film is also made favorable polarizing plate. Can be. Moreover, the laminated optical member which laminated | stacked the other optical layer on this polarizing plate also becomes a thing with few defects.

Hereinafter, embodiments of the present invention will be described in detail. This invention provides the polarizing plate in which the protective film which consists of transparent resin was bonded to the polarizer which consists of polyvinyl alcohol-type resin films via a photocurable adhesive agent. This invention also provides the laminated optical member which laminated | stacked the other optical layer on this polarizing plate. The photocurable adhesive agent used for manufacture of a polarizing plate, the polarizing plate using the same, and laminated optical member are demonstrated in order.

[Photocurable adhesive]

In this invention, the photocurable adhesive agent for bonding the protective film which consists of transparent resins to the polarizer which consists of polyvinyl alcohol-type resin films contains two components of the following (A) and (B).

(A) photocationic curable component, and

(B) photocationic polymerization initiator.

(Photocationic curable component)

The photocationic curable component (A) which is a main component of a photocurable adhesive agent and provides adhesive force by polymerization hardening contains the following three types of compounds.

(A1) alicyclic diepoxy compound represented by said formula (I),

(A2) the diglycidyl compound represented by said formula (II), and

(A3) Monofunctional epoxy compound represented by said formula (III).

In said Formula (I) which shows an alicyclic diepoxy compound (A1), R <^1> and R <^2> is a hydrogen atom or a C1-C6 alkyl group each independently, but when an alkyl group is C3 or more, even if it has an alicyclic structure, do. This alkyl group makes the position of the cyclohexane ring couple | bonded with X in Formula (I) 1-position (hence, the position of the epoxy group in two cyclohexane rings becomes 3, 4-position), 1 You may couple to any position of -position-6-position. Of course, the alkyl group may be linear, or in the case of having 3 or more carbon atoms, it may be branched. Moreover, as above-mentioned, when it is C3 or more, you may have alicyclic structure. Typical examples of the alkyl group having an alicyclic structure include cyclopentyl and cyclohexyl.

Similarly, in Formula (I), X which connects two 3, 4- epoxycyclohexane rings is an oxygen atom, a C1-C6 alkanediyl group, or bivalent represented by any of said Formula (Ia)-(Id) Qi. Here, the alkanediyl group is a concept containing alkylene and alkylidene, and the alkylene may be linear, or may be branched when it is C3 or more.

Moreover, when X is a bivalent group represented by any of said Formula (Ia)-(Id), the coupling group Y <^1> , Y <^2> , Y <^3> and Y <^4> in each formula are a C1-C20 alkanediyl group, respectively. In addition, when this alkanediyl group has 3 or more carbon atoms, it may have alicyclic structure. These alkanediyl groups may, of course, also be linear, or may be branched when they have 3 or more carbon atoms. Moreover, as above-mentioned, when it is C3 or more, you may have alicyclic structure. Typical examples of the alkanediyl group having an alicyclic structure include cyclopentylene and cyclohexylene.

When the alicyclic diepoxy compound (A1) represented by Formula (I) is demonstrated concretely, X in Formula (I) is a bivalent group represented by the said Formula (Ia), and the compound of a in that formula is 0. Silver 3, 4- epoxycyclohexyl methanol (The C1-C6 alkyl group may couple | bond with the cyclohexane ring), and 3, 4- epoxy cyclohexane carboxylic acid (C1-C6 of the cyclohexane ring. An alkyl group may be bonded). For the specific example, in 3, 4- epoxycyclohexyl methyl 3, 4- epoxy cyclohexane carboxylate [Formula (I) (where X is a divalent group represented by Formula (Ia) whose a = 0)). , A compound wherein R ¹ = R ² = H], to 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate [Formula (I) having the same X as described above]] Wherein R ¹ = 6-methyl, R ² = 6-methyl], 3,4-epoxy-1-methylcyclohexylmethyl 3,4-epoxy-1-methylcyclohexanecarboxylate [X same as above] In formula (I) having a compound wherein R ¹ = 1-methyl, R ² = 1-methyl], 3,4-epoxy-3-methylcyclohexylmethyl 3,4-epoxy-3-methylcyclohexanecarb And a carboxylate [compound (I) having the same X as above, wherein R ¹ = 3-methyl, R ² = 3-methyl).

X in Formula (I) is a divalent group compound represented by Formula (Ib), wherein alkylene glycols and 3,4-epoxycyclohexanecarboxylic acid (an alkyl group having 1 to 6 carbon atoms are bonded to the cyclohexane ring May be used). X in formula (I) is a divalent group compound represented by formula (Ic) is aliphatic dicarboxylic acid and 3,4-epoxycyclohexylmethanol (even if the C1-C6 alkyl group is bonded to the cyclohexane ring) Ester). Moreover, the ether of the 3, 4- epoxycyclohexyl methanol (The C1-C6 alkyl group may couple | bond with the cyclohexane ring) is a compound of the bivalent group which X in Formula (I) shows by Formula (Id). Ether of a sieve (when b = 0) or alkylene glycols or polyalkylene glycols and 3,4-epoxycyclohexylmethanol (the alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring) Cargo (if b> 0).

Diglycidyl In the formula (Ⅱ) represents the pyridyl compound (A2), Z is a branched alkylene group, or a group represented by the formula ^{_{-C m H 2m -Z 1 -C n}} H 2n of 3 to 8 carbon atoms - a divalent group represented by the to be. Here, -Z ¹ -is -O-, -CO-O- or -O-CO-, one of m and n is an integer of 1 or more and the other is an integer of 2 or more, but the sum of both is 8 or less, and C _{One of m} H _2m and C _n H _2n is a branched divalent saturated hydrocarbon group.

In Formula (II), the compound whose Z is a branched alkylene group is the diglycidyl ether of branched alkylene glycol. Specific examples thereof include propylene glycol diglycidyl ether, 1,3-butanediol diglycidyl ether, 1,2-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 3-methyl-1 , 5-pentanediol diglycidyl ether, 2-methyl-1,8-octanediol diglycidyl ether, 1,4-cyclohexanedimethanol, and the like.

In the formula (II), Z is a divalent group represented by the formula -C _m H _2m -Z ¹ -C _n H _2n - _wherein Z is a branched alkylene group, and the CC bond of the alkylene group is It corresponds to the case where it is interrupted by -O-, -CO-O-, or -O-CO-.

In said Formula (III) which shows a monofunctional epoxy compound, R <^3> is a C1-C15 alkyl group. Of course, the alkyl group may also be a straight chain, and in the case of having 3 or more carbon atoms, it may be branched. It is preferable that this alkyl group has comparatively many carbon atoms, for example, 6 or more, and also it is preferable to exist in the range of C6-C10. Especially, it is preferable that it is a branched alkyl group. 2-ethylhexyl glycidyl ether is mentioned as a typical example of the monofunctional epoxy compound represented by Formula (III).

The amount of the alicyclic diepoxy compound (A1) in the photocationic curable component (A) is 30 to 85% by weight based on the total amount of the photocationic curable component (A). The amount is preferably 40 to 80% by weight, more preferably 60 to 75% by weight. If the amount of the alicyclic diepoxy compound (A1) in the photocationic curable component (A) is too small, curing will be insufficient and the adhesion between the polarizer / protective film will decrease. On the other hand, when the amount is too large, the amounts of the diglycidyl compound (A2) and the monofunctional epoxy compound (A3) described below are relatively small, which makes it difficult to reduce the viscosity of the photocurable adhesive agent in the present invention. .

Moreover, the quantity of the diglycidyl compound (A2) which has a branched structure in the coupling group in a photocationic curable component (A) is 1-69 weight%. The amount is preferably 5 to 50% by weight, more preferably 5 to 30% by weight. When the amount of the diglycidyl compound (A2) in the photocationic curable component (A) is more than 69% by weight, the curing is insufficient, and the adhesion between the polarizer / protective film decreases.

In addition, the quantity of the monofunctional epoxy compound (A3) in a photocationic curable component (A) shall be 1-69 weight%. The amount is preferably 2 to 50% by weight, more preferably 2 to 15% by weight. When the amount of the monofunctional epoxy compound (A3) in the photocationic curable component (A) is more than 69% by weight, curing is insufficient, and adhesion between the polarizer / protective film is lowered.

The photocationic curable component (A) which comprises a photocurable adhesive agent contains the alicyclic diepoxy compound (A1) demonstrated above, the diglycidyl compound (A2) which has a branched structure in a coupling group, and a monofunctional epoxy compound (A3). , And contained in the ratio described above, respectively. In further reducing the viscosity of the photocurable adhesive before curing and improving the adhesion between the polarizer and the protective film by the cured product, the diglycidyl compound (A2) is based on the total amount of the photocurable adhesive. And the total amount of the monofunctional epoxy compound (A3) is preferably 25% by weight or more.

The photocationic curable component (A) is in a range in which the alicyclic diepoxy compound (A1), the diglycidyl compound (A2) having a branched structure and the monofunctional epoxy compound (A3) become the amounts described above. In addition, you may contain the other cationically polymerizable compound.

(Photocationic polymerization initiator)

In the present invention, the photocationic polymerization initiator (B) is blended with the photocurable adhesive composition in that the photocationic curable component is cured by cationic polymerization by irradiation of active energy rays to form an adhesive layer. . The photocationic polymerization initiator is to generate cationic species or Lewis acids by irradiation of active energy rays such as visible light, ultraviolet light, X-rays or electron beams to initiate the polymerization reaction of the photocationic curable component (A). . Since a photocationic polymerization initiator acts catalytically with light, even if it mixes with a photocationic curable component (A), it is excellent in storage stability and workability. As a compound which generate | occur | produces a cation species or a Lewis acid by irradiation of an active energy ray, For example, Aromatic diazonium salt; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-Allene complex etc. are mentioned.

As an aromatic diazonium salt, the following compounds are mentioned, for example.

Benzenediazonium hexafluoroantimonate,

Benzenediazonium hexafluorophosphate,

Benzenediazonium hexafluoroborate and the like.

As aromatic iodonium salt, the following compounds are mentioned, for example.

Diphenyl iodonium tetrakis (pentafluorophenyl) borate,

Diphenyl iodonium hexafluorophosphate,

Diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroantimonate,

Di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

As an aromatic sulfonium salt, the following compounds are mentioned, for example.

Triphenylsulfonium hexafluorophosphate,

Triphenylsulfonium hexafluoroantimonate,

Triphenylsulfonium tetrakis (pentafluorophenyl) borate,

4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate,

4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate,

4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluorophosphate,

7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,

7- (di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,

4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate,

4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate,

4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like.

As an iron- allene complex, the following compounds are mentioned, for example.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,

Cumene-cyclopentadienyl iron (II) hexafluorophosphate,

Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide and the like.

These photocationic polymerization initiators may be used independently, respectively and may mix and use 2 or more types. Among these, in particular, the aromatic sulfonium salt is preferably used because it has excellent ultraviolet curability in the wavelength region around 300 nm and can provide a cured product having excellent mechanical strength and adhesive strength.

The compounding quantity of a photocationic polymerization initiator (B) shall be 1-10 weight part with respect to 100 weight part of whole photocationic curable components (A). By mix | blending 1 weight part or more of photocationic polymerization initiators per 100 weight part of photocationic curable components (A), a photocationic curable component (A) can fully be hardened | cured and a high mechanical strength and adhesive strength are provided to the obtained polarizing plate. do. On the other hand, when the amount increases, the hygroscopicity of the cured product is increased by increasing the ionic substance in the cured product, and the durability of the polarizing plate may be reduced, so that the amount of the photocationic polymerization initiator (B) is increased by (A) It is 10 parts by weight or less per 100 parts by weight. It is preferable to make the compounding quantity of a photocationic polymerization initiator (B) into 2 weight part or more per 100 weight part of photocationic curable components (A), and also to be 6 weight part or less.

(Other components which can be mix | blended with a photocurable adhesive agent)

The photocurable adhesive agent of this invention is mix | blended with general photocurable resin or an adhesive agent in addition to the photocationic curable component (A) and photocationic polymerization initiator (B) containing the above epoxy compounds. It may contain a component. As a preferable example of another component, a photosensitizer and a photosensitization adjuvant are mentioned. A photosensitizer is a compound which shows maximum absorption in the wavelength longer than the maximum absorption wavelength represented by a photocationic polymerization initiator (B), and promotes the polymerization start reaction by a photocationic polymerization initiator (B). The photosensitizer is a compound that further promotes the action of the photosensitizer. Depending on the kind of protective film, it may be preferable to mix | blend such a photosensitizer and further a photosensitization adjuvant.

It is preferable that a photosensitizer is a compound which shows maximum absorption in the light of wavelength longer than 380 nm. Said photocationic polymerization initiator (B) shows the maximum absorption in wavelength 300 nm or shorter, and generate | occur | produces a cation species or a Lewis acid in response to the light of the wavelength in the vicinity, and a photocationic curable component (A) Although the cationic polymerization of the above is initiated, when the above photosensitizer is blended, it is also sensitive to light having a wavelength longer than that, especially a wavelength longer than 380 nm. As such a photosensitizer, an anthracene type compound is used advantageously. Specific examples of the anthracene-based photosensitizers include the following compounds.

9,10-dimethoxyanthracene,

9,10-diethoxyanthracene,

9,10-dipropoxyanthracene,

9,10-diisopropoxyanthracene,

9,10-dibutoxyanthracene,

9,10-dipentyloxyanthracene,

9,10-dihexyloxyanthracene,

9,10-bis (2-methoxyethoxy) anthracene,

9,10-bis (2-ethoxyethoxy) anthracene,

9,10-bis (2-butoxyethoxy) anthracene,

9,10-bis (3-butoxypropoxy) anthracene,

2-methyl- or 2-ethyl-9,10-dimethoxyanthracene,

2-methyl- or 2-ethyl-9,10-diethoxyanthracene,

2-methyl- or 2-ethyl-9,10-dipropoxycanthracene,

2-methyl- or 2-ethyl-9,10-diisopropoxycanthracene,

2-methyl- or 2-ethyl-9,10-dibutoxyanthracene,

2-methyl- or 2-ethyl-9,10-dipentyloxyanthracene,

2-methyl- or 2-ethyl-9,10-dihexyloxyanthracene and the like.

By mix | blending such a photosensitizer with a photocurable adhesive agent, the hardenability of an adhesive agent improves compared with the case where it is not mix | blended. Such effect is expressed by mix | blending 0.1 weight part or more of photosensitizers with respect to 100 weight part of photocationic curable components (A). On the other hand, when the compounding quantity of a photosensitizer increases, the problem which precipitates at the time of low temperature storage generate | occur | produces, It is preferable that the quantity shall be 2 weight part or less with respect to 100 weight part of photocationic curable components (A). From the viewpoint of maintaining the neutral gray of the polarizing plate, it is advantageous to reduce the blending amount of the photosensitizer in a range in which the adhesion between the polarizer and the protective film is appropriately maintained, and for example, to 100 parts by weight of the photocationic curable component (A). The amount of the photosensitizer is more preferably 0.1 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight.

Next, the photosensitizer will be described. Although there exist various things in a photosensitizer, a naphthalene type compound is used advantageously. Specific examples of the naphthalene-based light sensitizing aid include the following compounds.

4-methoxy-1-naphthol,

4-ethoxy-1-naphthol,

4-propoxy-1-naphthol,

4-butoxy-1-naphthol,

4-hexyloxy-1-naphthol,

1,4-dimethoxynaphthalene,

1-ethoxy-4-methoxynaphthalene,

1,4-diethoxynaphthalene,

1,4-dipropoxynaphthalene,

1,4-dibutoxynaphthalene etc.

By mix | blending a naphthalene type photosensitization adjuvant with a photocurable adhesive agent, the hardenability of an adhesive agent improves compared with the case where it is not mix | blended. Such effect is expressed by mix | blending 0.1 weight part or more of naphthalene type photosensitivity adjuvant with respect to 100 weight part of photocationic curable components (A). On the other hand, when the compounding quantity of a naphthalene type photosensitivity auxiliary agent increases, it will generate | occur | produce the problem which precipitates at the time of low temperature storage, and it is preferable that the quantity shall be 5 weight part or less with respect to 100 weight part of photocationic curable components (A). Furthermore, it is more preferable to set it as 3 weight part or less further.

(Physical Properties of Photocurable Adhesives)

The photocurable adhesive agent demonstrated above is used for bonding a protective film to the polarizer which consists of a polyvinyl alcohol-type resin film, and manufacturing a polarizing plate as mentioned above. Under the present circumstances, when an adhesive agent melt | dissolves a protective film, as mentioned above, the dissolution may be a cause and a bubble defect may arise in a polarizing plate. In this invention, what employ | adopted the photocurable adhesive agent which mix | blended the photocationic curable component (A) which contains the specific 3 types of compound demonstrated above in a predetermined ratio, Especially as diglycidyl compound (A2) in it, By employing a compound in which the linking group has a branched structure, and typically, the linking group is a branched alkylene group, an adhesive is hardly dissolved in the protective film. That is, when this adhesive agent is immersed for 2 days at 23 degreeC in the protective film which comprises a polarizing plate, the weight reduction of the said protective film will be 0 to 30 weight%.

Here, the weight reduction when the protective film is immersed in the adhesive can be obtained as follows. That is, first, the transparent resin film constituting the protective film is cut to an appropriate size and its weight is obtained. Next, this cut film is prepared in a liquid state, immersed in a photocurable adhesive maintained at a temperature of 23 ° C., left for 2 days, taken out, and after wiping off the adhesive attached to the surface, the weight thereof is obtained. And the weight reduction after immersion is calculated | required from the following formula | equation.

Weight reduction (%) = (film weight after 1-immersion / film weight before immersion) × 100

Moreover, after apply | coating this adhesive agent to at least one bonding surface of the said polarizer and a protective film, this adhesive agent superimposes both via the adhesive bond layer, and an adhesive agent hardens. And in order to improve the applicability to a polarizer and / or a protective film, it is preferable that the viscosity of this adhesive agent is low. In this invention, as a photocationic curable component (A), by mix | blending the specific 3 types of compound demonstrated above in a predetermined ratio, the viscosity of a photocurable adhesive agent becomes low and coating suitability improves. Specifically, this photocurable adhesive agent can be made so that the viscosity in 25 degreeC may be 100 mPa * sec or less.

[Polarizer]

In this invention, the protective film which consists of transparent resin is bonded together on at least one surface of the polarizer which consists of a polyvinyl alcohol-type resin film through the photocurable adhesive agent mentioned above, and the photocurable adhesive agent is hardened and it is set as a polarizing plate. In this invention, as mentioned above, the storage elastic modulus of the adhesive bond layer which is the hardened | cured material of a photocurable adhesive agent can be raised, and adhesiveness between a polarizer and a protective film can be improved. Therefore, adhesive strength by the 180 degree peeling test between a polarizer and a protective film can be made to be 0.6 N / 25 mm or more. The 180 degree peeling test is performed here according to JISK6854-2: 1999 "Adhesive- peeling adhesive strength test method-part 2: 180 degree peeling."

Hereinafter, the polarizer and protective film which comprise the polarizing plate of this invention are demonstrated, and the manufacturing method of a polarizing plate is simply demonstrated.

(Polarizer)

A polarizer is comprised from the polyvinyl alcohol-type resin film by which the dichroic dye was adsorption-oriented. Polyvinyl alcohol-type resin which comprises a polarizer is obtained by saponifying polyvinyl acetate type resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers copolymerizable with this, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. As another monomer copolymerized with vinyl acetate, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, etc. are mentioned, for example. The saponification degree of polyvinyl alcohol-type resin is 85-100 mol% normally, Preferably it is the range of 98-100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually in the range of 1,000 to 10,000, preferably 1,500 to 5,000.

The polarizer is a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye, adsorbing the dichroic dye, and a polyvinyl alcohol system in which the dichroic dye is adsorbed. It manufactures through the process of processing a resin film with boric-acid aqueous solution.

Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, uniaxial stretching can also be performed in these some steps. In order to uniaxially stretch, you may extend | stretch to 1 axis between rolls from which a circumferential speed differs, and you may extend | stretch to 1 axis using a hot roll. Moreover, dry stretching which extends | stretches in air | atmosphere may be sufficient, and wet extending | stretching which extends | stretches in the state swollen by the solvent may be sufficient. The draw ratio is usually about 4 to 8 times.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, what is necessary is just to immerse a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye. As a dichroic dye, an iodine or a dichroic organic dye is used specifically.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution is about 20-40 degreeC normally, and the immersion time (dyeing time) with respect to this aqueous solution is about 30 to 300 second normally.

On the other hand, when using a dichroic organic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic organic dye is employ | adopted normally. Content of the dichroic organic dye in this aqueous solution is about 1 * 10 <^-3> -1 * 10 <^-2> weight part normally per 100 weight part of water. This aqueous solution may contain inorganic salts, such as sodium sulfate. The temperature of this aqueous solution is about 20-80 degreeC normally, and the immersion time (dyeing time) with respect to this aqueous solution is about 30-300 second normally.

Boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-type resin film in boric-acid aqueous solution. Content of boric acid in boric-acid aqueous solution is about 2-15 weight part normally per 100 weight part of water, Preferably it is about 5-12 weight part. When iodine is used as the dichroic dye, it is preferable that the aqueous solution of boric acid contains potassium iodide. Content of potassium iodide in boric-acid aqueous solution is about 2-20 weight part normally per 100 weight part of water, Preferably it is 5-15 weight part. Immersion time in boric-acid aqueous solution is about 100 to 1,200 second normally, Preferably it is about 150 to 600 second, More preferably, it is about 200 to 400 second. The temperature of boric-acid aqueous solution is 50 degreeC or more normally, Preferably it is 50-85 degreeC.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. The water washing process is performed by immersing the polyvinyl alcohol-type resin film processed by boric acid in water, for example. After water washing, a drying process is performed and a polarizer is obtained. The temperature of the water in a water washing process is about 5-40 degreeC normally, and immersion time is about 2 to 120 second normally. The drying treatment carried out thereafter is usually carried out using a hot air dryer or a far infrared heater. Drying temperature is 40-100 degreeC normally. Moreover, the time of a drying process is about 120 to 600 second normally.

The thickness of the polarizer which consists of a polyvinyl alcohol-type resin film obtained in this way can be about 10-50 micrometers.

(Shield)

A protective film is bonded to the polarizer which consists of a polyvinyl alcohol-type resin film demonstrated above through the photocurable adhesive agent mentioned above, and a photocurable adhesive agent is hardened and it is set as a polarizing plate. The protective film can be composed of an acetyl cellulose-based resin film including triacetyl cellulose, which is conventionally most widely used as a protective film for a polarizing plate, and a resin film having a lower moisture permeability than triacetyl cellulose. The water vapor transmission rate of triacetyl cellulose is generally about 400 g / m 2/24 hr.

In one preferable aspect, the protective film bonded to at least one surface of a polarizer is comprised from acetyl cellulose resin. Especially the protective film bonded to one surface of a polarizer can also be comprised from the acetyl cellulose type resin in which the ultraviolet absorber is mix | blended. In another preferable aspect, the protective film bonded to at least one surface of the polarizer is composed of a resin film having a moisture permeability lower than triacetyl cellulose, for example, a resin film having a moisture permeability of 300 g / m 2/24 hr or less. As resin which comprises such a resin film with low water vapor transmission rate, amorphous polyolefin resin, polyester resin, acrylic resin, polycarbonate resin, chain type polyolefin resin, etc. are mentioned. Among these, amorphous polyolefin resins, polyester resins and chain polyolefin resins are preferably used. In still another preferred embodiment, a protective film made of acetylcellulose-based resin is bonded to one surface of the polarizer via the adhesive layer, and similarly to the other side of the polarizer via the adhesive layer to provide the same moisture permeability. The protective film which consists of low transparent resin is bonded together.

The acetyl cellulose-based resin may be a resin in which at least a part of the hydroxyl groups in the cellulose is esterified, a part of which is esterified, and a part of which is esterified with another acid. Specific examples of the acetyl cellulose resins include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like.

The amorphous polyolefin resin is a polymer having a polymerized unit of a cyclic olefin, such as norbornene or tetracyclododecene (aka dimethanooctahydronaphthalene), or a compound having a substituent bonded thereto, and a cyclic olefin A copolymer obtained by copolymerizing a chain olefin and / or an aromatic vinyl compound may be used. In the case of the homopolymer of a cyclic olefin or the copolymer of 2 or more types of cyclic olefins, since a double bond remains by ring-opening polymerization, what was hydrogenated therein is generally used as amorphous polyolefin resin. Especially, thermoplastic norbornene-type resin is typical.

Polyester-based resin is a polymer obtained by condensation polymerization of dibasic acid and a dihydric alcohol, and polyethylene terephthalate is typical. The acrylic resin is a polymer containing methyl methacrylate as the main monomer, and in addition to the homopolymer of methyl methacrylate, a copolymer such as methyl methacrylate and an acrylic acid ester such as methyl acrylate or an aromatic vinyl compound may be used. Polycarbonate resin is a polymer which has a carbonate bond (-O-CO-O-) in a principal chain, and what is obtained by condensation polymerization of bisphenol A and phosgene is typical. The linear polyolefin resin is a polymer containing a chain olefin such as ethylene or propylene as a main monomer, and may be a homopolymer or a copolymer. Especially, the homopolymer of propylene and the copolymer by which a small amount of ethylene is copolymerized in propylene are typical.

Such a protective film may have various surface treatment layers, such as a hard-coat layer, an antireflection layer, an antiglare layer, or an antistatic layer, on the surface on the opposite side to the surface bonded to a polarizer. The protective film can be made into about 5-150 micrometers in thickness, including the case where such a surface treatment layer is formed. Preferably the thickness is 10 micrometers or more, Preferably it is 120 micrometers or less, More preferably, it is 100 micrometers or less.

(Production method of polarizing plate)

In manufacture of a polarizing plate, the coating layer of the photocurable adhesive agent mentioned above is formed in one or both of the bonding surface of a polarizer and a protective film, a polarizer and a protective film are bonded together through this coating layer, and the uncured formed in this way The application layer of the photocurable adhesive agent is cured by irradiation with an active energy ray, and the protective film is fixed on the polarizer. The coating layer of a photocurable adhesive agent may be formed in the bonding surface of a polarizer, and may be formed in the bonding surface of a protective film. Various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater, can be used for formation of an application layer. Moreover, the method which makes a adhesive agent flexible can also be employ | adopted, supplying a polarizer and a protective film continuously so that the bonding surface of both may be inside. Since each coating system has an optimum viscosity range, it is also a useful technique to perform viscosity adjustment using a solvent. Although what melt | dissolves a photocurable adhesive agent favorably is used for the solvent for this without reducing the optical performance of a polarizer, there is no special limitation in the kind. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used. The thickness of an adhesive bond layer is 20 micrometers or less normally, Preferably it is 10 micrometers or less, More preferably, it is 5 micrometers or less. When the adhesive layer becomes thick, the reaction rate of the adhesive decreases, and the heat and moisture resistance of the polarizing plate tends to deteriorate.

In adhering the polarizer and the protective film, one or both of the bonding surfaces may be easily treated such as corona discharge treatment, plasma treatment, flame treatment, primer treatment, or anchor coating treatment before forming the coating layer of the adhesive. May be carried out.

What is necessary is just to generate | occur | produce an ultraviolet-ray, an electron beam, X-rays, etc. as a light source used for irradiating an active energy ray to the application layer of a photocurable adhesive agent. In particular, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultrahigh pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps, and the like, which have a luminescence distribution at a wavelength of 400 nm or less, are preferably used. The active energy ray irradiation intensity for the photocurable adhesive is determined for each target composition, and is not particularly limited, but it is such that the irradiation intensity of the wavelength region effective for the activation of the photocationic polymerization initiator is 0.1 to 100 mW / cm 2. desirable. If the light irradiation intensity to the photocurable adhesive is too small, the reaction time is too long, while if the light irradiation intensity is too large, the heat generated from the lamp and the heat generated during the polymerization of the photocurable adhesive may cause There is a possibility of causing yellowing and deterioration of the polarizer. Light irradiation time with respect to a photocurable adhesive agent is controlled for every composition to harden | cure, Although it does not specifically limit, It is preferable to set so that accumulated light quantity represented by the product of irradiation intensity and irradiation time may be 10-5,000 mJ / cm <2>. If the amount of accumulated light for the photocurable adhesive is too small, the generation of active species derived from the photocationic polymerization initiator may not be sufficient, and there is a possibility that the curing of the obtained adhesive layer may become insufficient, while the amount of accumulated light is increased. The time becomes very long, which is disadvantageous for productivity improvement.

When bonding a protective film on both surfaces of a polarizer, irradiation of an active energy ray may be performed from which protective film side, For example, when one protective film contains a ultraviolet absorber and the other protective film does not contain a ultraviolet absorber. Irradiation of an active energy ray from the protective film side which does not contain an ultraviolet absorber is preferable in order to make effective use of the irradiated active energy ray, and to raise a hardening rate.

[Laminated Optical Member]

The polarizing plate of this invention can laminate | stack the optical layers which have optical functions other than a polarizing plate, and can be set as a laminated optical member. Typically, by laminating and sticking an optical layer to the protective film of a polarizing plate through an adhesive agent and an adhesive, it becomes a laminated optical member, In addition, for example, it interposes a photocurable adhesive agent in accordance with this invention on one surface of a polarizer, for example. A protective film is bonded together, and an optical layer can also be laminated | stacked on the other surface of a polarizer through an adhesive agent and an adhesive. In the latter case, when the photocurable adhesive agent prescribed | regulated by this invention is used as an adhesive agent for bonding a polarizer and an optical layer, this optical layer can also be a protective film prescribed | regulated by this invention simultaneously.

For example, the optical layer laminated on the polarizing plate, for the polarizing plate disposed on the back side of the liquid crystal cell, the reflective layer, semi-transmissive reflective layer, light diffusing layer, light collecting plate, laminated on the opposite side to the side facing the liquid crystal cell of the polarizing plate, Brightness enhancement films and the like. Moreover, any of the polarizing plate arrange | positioned at the front side of a liquid crystal cell, and the polarizing plate arrange | positioned at the back side of a liquid crystal cell, there exists a retardation film etc. laminated | stacked on the side facing the liquid crystal cell of this polarizing plate.

The reflective layer, the semi-transmissive reflective layer, or the light diffusing layer is formed to be a reflective polarizing plate (optical member), a semi-transmissive reflective polarizing plate (optical member), or a diffusing polarizing plate (optical member), respectively. A reflective polarizing plate is used for a liquid crystal display device of the type which reflects and displays incident light on the viewer's side, and since a light source such as a backlight can be omitted, it is easy to thin the liquid crystal display device. In addition, the semi-transmissive polarizing plate is used for a liquid crystal display device of a type which displays reflection light at a spot and light from a backlight at a dark spot. The optical member as a reflective polarizing plate can, for example, attach and form a foil or a vapor deposition film made of a metal such as aluminum to a protective film on the polarizer to form a reflective layer. The optical member as a semi-transmissive polarizing plate can be formed by making the said reflective layer into a half mirror, or adhering the reflecting plate which contains a pearl pigment etc. and shows light transmittance to a polarizing plate. On the other hand, the optical member as a diffusion type polarizing plate has various methods, such as the method of performing a mat process to the protective film on a polarizing plate, the method of apply | coating resin containing microparticles, and the method of adhering the film containing microparticles | fine-particles. To form a fine concavo-convex structure on the surface.

Moreover, the optical member which acts as a polarizing plate for both reflection and diffusion can also be formed, In that case, the method of forming the reflecting layer in which the uneven structure was reflected in the fine uneven structure surface of a diffused polarizing plate, for example can be employ | adopted. have. The reflective layer having a fine concave-convex structure has the advantage of diffusing incident light by diffuse reflection, preventing directivity and glare, and suppressing unevenness in contrast. Moreover, the resin layer and film containing microparticles | fine-particles also have the advantage that it can spread | diffuse when incident light and the reflected light permeate | transmit the microparticles-containing layer, and can suppress a brightness-and-evenness nonuniformity. The reflective layer reflecting the surface fine concavo-convex structure can be formed by directly attaching and forming a metal to the surface of the fine concavo-convex structure, for example, by a method such as vacuum deposition, ion plating, or deposition or plating such as sputtering. . The microparticles | fine-particles mix | blended in order to form surface fine uneven | corrugated structure are inorganic microparticles | fine-particles, for example, silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide with an average particle diameter of 0.1-30 micrometers. Organic particulates such as crosslinked or uncrosslinked polymers.

A light collecting plate is used for the purpose of optical path control, etc., and can be formed as a prism array sheet, a lens array sheet, a dot formation sheet | seat, etc.

The brightness enhancing film is used for the purpose of improving the brightness in a liquid crystal display device. Examples thereof include a reflective polarization separating sheet designed to produce anisotropy in reflectance by stacking a plurality of thin films having different refractive anisotropy, And a circularly polarized light separating sheet which supported the alignment film of the cholesteric liquid crystal polymer and the alignment liquid crystal layer on the film substrate.

On the other hand, said retardation film which acts as an optical layer is used for the purpose of compensation of retardation by a liquid crystal cell. As an example, the birefringent film which consists of stretched films of various plastics, the film in which the discotic liquid crystal and the nematic liquid crystal were orientated, and the said liquid crystal layer were formed on the film base material, etc. are mentioned. When forming a liquid crystal layer on a film base material, cellulose resin films, such as a triacetyl cellulose, are used suitably as a film base material.

As the plastic forming the birefringent film, for example, amorphous polyolefin resin, polycarbonate resin, acrylic resin, chain polyolefin resin such as polypropylene, polyvinyl alcohol, polystyrene, polyarylate, polyamide Etc. can be mentioned. The stretched film may be processed by a suitable method such as uniaxial or biaxial. In addition, you may use retardation film in combination of 2 or more sheet for the purpose of control of optical characteristics, such as widening.

In a laminated optical member, what includes a retardation film as an optical layer other than a polarizing plate is used preferably at the point which can effectively compensate optical when it applies to a liquid crystal display device. What is necessary is just to select the optimal retardation value (in-plane and thickness direction) of retardation film according to the liquid crystal cell applied.

A laminated optical member can be made into the laminated body of two layers or three layers or more combining the polarizing plate and 1 or 2 layers or more selected according to the use purpose in the above-mentioned various optical layers. In that case, although the various optical layers which form a laminated optical member are integrated with a polarizing plate using an adhesive agent or an adhesive, there is no restriction | limiting in particular if the adhesive agent or adhesive agent used for it is a favorable adhesive bond layer or an adhesive layer. It is preferable to use an adhesive (it is also called a pressure-sensitive adhesive) from a viewpoint of the simplicity of an adhesion | attachment operation, the prevention of the occurrence of optical deformation, etc. As an adhesive, what uses an acryl-type polymer, a silicone type polymer, polyester, a polyurethane, a polyether, etc. as a base polymer can be used. Among them, like an acrylic adhesive, it is excellent in optical transparency, maintains proper wettability and cohesion, and is excellent in adhesiveness with a base material, Furthermore, it has weather resistance, heat resistance, etc., and lifts and peels off under the conditions of heating or humidification. It is preferable to select and use the thing which does not produce a peeling problem. In an acrylic adhesive, the functional group containing acrylic monomer which consists of alkyl ester of (meth) acrylic acid which has a C20 or less alkyl group, such as a methyl group, an ethyl group, and a butyl group, and (meth) acrylic acid, (meth) acrylic-acid hydroxyethyl, etc., An acrylic copolymer having a weight average molecular weight of 100,000 or more, which is blended so that the glass transition temperature is preferably 25 ° C. or less, more preferably 0 ° C. or less, is useful as the base polymer.

Formation of the adhesive layer with respect to a polarizing plate, for example, melt | dissolves or disperse | distributes an adhesive composition in organic solvents, such as toluene and ethyl acetate, prepares a 10-40 weight% solution, and apply | coats this directly on a polarizing plate, The pressure-sensitive adhesive layer is formed on the protective film in advance, and can be carried out by a method of transferring it onto a polarizing plate or the like. Although the thickness of an adhesive layer is determined by the adhesive force etc., the range of about 1-50 micrometers is suitable.

Moreover, the filler, pigment, colorant, antioxidant, ultraviolet absorber, etc. which consist of glass fiber, glass beads, resin beads, metal powder, another inorganic powder, etc. may be mix | blended with an adhesive layer as needed. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex salt compounds and the like.

The laminated optical member can be disposed 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 | mold represented by a thin-film transistor type and the simple matrix drive type represented by a super twisted nematic type | mold. Can be formed. Usually, the same adhesive as mentioned above is used for adhesion | attachment of a laminated optical member and a liquid crystal cell.

Example

Although an Example is shown to the following and this invention is demonstrated to it further more concretely, this invention is not limited by these Examples. In the examples,% and parts representing the content to the amount used are based on weight unless otherwise specified. In addition, the photocationic curable component and photocationic polymerization initiator which were used by the following example are as follows, and are represented by each symbol below.

(A) photocationic curable component

(a1) 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate [in the formula ^{(Ⅰ), R 1 = R} 2 = H, X = -COOCH 2 - A compound],

(a21) neopentyl glycol diglycidyl ether [in the formula (II), Z = -CH ₂ C (CH ₃ ) ₂ CH ₂ -phosphorus compound),

(a22) 1,4-butanediol diglycidyl ether [In the formula (II), Z =-(CH ₂ ) ₄ -phosphorus compound] (for comparison),

(a3) 2- ethylhexyl glycidyl ether [In the formula ^{(Ⅲ), R 3 = CH} 3 (CH 2) 3 -CH (CH 2 CH 3) -CH 2 - in the compound.

(B) photocationic polymerization initiator (in the table, "initiator" and abbreviation)

(b1) triarylsulfonium hexafluorophosphate.

[Examples 1-4 and Comparative Examples 1-3]

(1) Preparation of photocurable adhesive

After mixing said photocationic curable component and photocationic polymerization initiator in the compounding ratio (unit is unit) shown in Table 1, it defoamed and prepared the photocurable adhesive liquid. In addition, the photocationic polymerization initiator (b1) was mix | blended as a 50% propylene carbonate solution, and it showed in Table 1 by the solid content.

(2) Viscosity measurement at 25 degrees C of adhesive liquid

About each adhesive liquid prepared above, the viscosity in the temperature of 25 degreeC was measured using the rotary viscoelasticity measuring apparatus "Physica MCR 301" by Anton Paar. The results are shown in Table 1.

(3) solubility of the protective film

A 40-micrometer-thick retardation film [brand name "N-TAC KC4FR-1", manufactured by Konica Minolta Opt Co., Ltd.) consisting of acetyl cellulose resin was prepared. This retardation film is bonded to a polyvinyl alcohol-type polarizer as a protective film which has an optical compensation function, and is used for manufacturing a polarizing plate. After cutting this retardation film into the magnitude | size of 10 mm x 40 mm, it was immersed in 20 g of each adhesive liquid prepared above at the temperature of 23 degreeC for 2 days. After 2 days, the retardation film was taken out, the adhesive liquid adhered to the protective film with Bencoat was wiped, and the weight was measured. And the weight reduction of the film was calculated | required by the following formula from the film weight before immersion in an adhesive liquid, and the film weight after immersion, and the result was shown in Table 1.

Weight reduction (%) = (film weight after 1-immersion / film weight before immersion) × 100

As in the comparative example 1, the ternary adhesive which mix | blended the diglycidyl ether (a21) and monofunctional epoxy compound (a3) which have a branched alkylene with the alicyclic diepoxy compound (a1) as a coupling agent is acetyl which is a protective film. Although the solubility of a cellulose resin film is small, since the compounding ratio of an alicyclic diepoxy compound (a1) is large, a viscosity becomes high and the coating suitability at the time of applying to a protective film or a polarizer is not enough. On the other hand, when using diglycidyl ether (a22) which has a C4 linear alkylene as a linkage like a diglycidyl compound (A2) like Comparative Examples 2 and 3, it is an acetyl cellulose type resin which is a protective film. The solubility of a film becomes large. On the other hand, when it is a ternary adhesive containing diglycidyl ether (a21) which has a branched alkylene as a coupling compound, it will be low viscosity and photocurable which will not melt | dissolve a protective film well when it is set as the compounding ratio similar to Examples 1-4. It becomes an adhesive.

The retardation film used in Examples 1-4 was bonded together to the polyvinyl alcohol film on one surface of the polarizer by which iodine is adsorbed-oriented, through the photocurable adhesive agent produced in Examples 1-4, and the other of a polarizer When the triacetyl cellulose film of thickness 80micrometer is bonded together on the surface through the same adhesive agent, respectively, and an ultraviolet-ray is irradiated from the retardation film side, the polarizing plate which shows favorable adhesive force is obtained. In particular, as in Examples 1 and 2, when the amount of the alicyclic diepoxy compound (a1) is 50% or more in the photocationic curable component, high adhesive force is obtained.

Claims (8)

As a polarizing plate comprised from the polarizer which consists of a polyvinyl alcohol-type resin film by which a dichroic dye was adsorption-oriented, and the protective film which consists of a transparent resin bonded together at least one surface of this polarizer via an adhesive agent,
Preferably,
100 parts by weight of the photocationic curable component (A),
1-10 weight part of photocationic polymerization initiators (B) are contained,
The said photocationic curable component (A) is based on the total amount,
The following formula (I)
[Chemical Formula 1]

(In formula, R <^1> and R <^2> respectively independently represents a hydrogen atom or a C1-C6 alkyl group, but when an alkyl group is C3 or more, you may have alicyclic structure;
X is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or the following formulas (Ia) to (Id):
(2)

A divalent group represented by any of the above, wherein Y ¹ to Y ⁴ each represent an alkanediyl group having 1 to 20 carbon atoms, but in the case of having 3 or more carbon atoms, may have an alicyclic structure;
a and b each represent an integer of 0 to 20)
30 to 85 weight% of the alicyclic diepoxy compound (A1) shown by
(II): &lt; EMI ID =
(3)

(Wherein Z represents a C3-C8 branched alkylene group or a divalent group represented by the formula -C _m H _2m -Z ¹ -C _n H _2n- , wherein -Z ¹ -represents -O-, -CO -O- or -O-CO- is represented, and one of m and n represents an integer of 1 or more, the other represents an integer of 2 or more, but the sum of both is 8 or less, and one of C _m H _2m and C _n H _2n . Represents a branched divalent saturated hydrocarbon group)
1-69 weight% of the diglycidyl compound (A2) represented by
Formula (III) below:
[Chemical Formula 4]

(In formula, R <^3> represents a C1-C15 alkyl group.)
It is formed with the photocurable adhesive agent containing 1-69 weight% of monofunctional epoxy compounds (A3) shown by
The polarizing plate whose weight loss of the said protective film is 0-30 weight%, when the said protective film is immersed in said photocurable adhesive agent at 23 degreeC for 2 days. The method of claim 1,
In formula (III) which shows a monofunctional epoxy compound (A3), R <^3> is a C6-C10 alkyl group. The method of claim 1,
The said photocurable adhesive agent is a polarizing plate whose viscosity in 25 degreeC is 100 mPa * sec or less. The method of claim 1,
The polarizing plate in which the said photocurable adhesive agent is hardened. The method of claim 1,
The protective film bonded to at least one surface of a polarizer is a polarizing plate which consists of acetyl cellulose type resin in which the ultraviolet absorber is mix | blended. The method of claim 1,
The protective film bonded to at least one surface of a polarizer is a polarizing plate which consists of transparent resin chosen from the group which consists of amorphous polyolefin resin, polyester resin, and chain-type polyolefin resin. The laminated optical member which consists of a laminated body of the polarizing plate of Claim 1, and another optical layer. The method of claim 7, wherein
The optical layer is a laminated optical member comprising a retardation film.