KR101752034B1

KR101752034B1 - Laminate optical member and polarizing plate using photocurable adhesive

Info

Publication number: KR101752034B1
Application number: KR1020137028008A
Authority: KR
Inventors: 에츠오 구메; 도모 이와타; 사토시 나가야스; 도시유키 다카하시; 에리 혼마
Original assignee: 스미또모 가가꾸 가부시끼가이샤; 가부시키가이샤 아데카
Priority date: 2011-03-29
Filing date: 2012-03-23
Publication date: 2017-06-28
Also published as: TWI583762B; KR20140029414A; JP2012208251A; WO2012133162A1; CN103597383A; CN103597383B; TW201245370A; JP5827483B2

Abstract

A polarizing plate comprising a polyvinyl alcohol polarizer and a transparent protective film bonded to the polarizer through an adhesive, wherein the adhesive contains 100 parts by weight of the photo cationic curing component (A), 100 parts by weight of the photo cationic polymerization initiator (B) 1 to 10 parts by weight of the photocathode curing component (A), and the photocathode curing component (A) is formed of a photocurable adhesive containing the following amounts of (A1) to (A3) based on the total amount thereof. 30 to 85% by weight of an alicyclic diepoxy compound (A1) represented by the following formula (I); 1 to 69% by weight of a diglycidyl compound (A2) represented by the following formula (II) and Z has a branched structure; And 1 to 69% by weight of the monofunctional epoxy compound (A3) represented by the following formula (III). When the protective film is immersed in the photocurable adhesive for 2 days at 23 占 폚, the weight loss of the protective film is 0 to 30% by weight.

Description

TECHNICAL FIELD [0001] The present invention relates to a polarizing plate and a laminated optical member using a photocurable adhesive,

The present invention relates to a polarizing plate in which a protective film made of a transparent resin is bonded to a polarizer made of a polyvinyl alcohol based resin film in which a dichroic dye is adsorbed and oriented via a photocurable adhesive, And another optical layer such as a retardation film is laminated on the laminated optical member.

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 a protective film is laminated on both surfaces of a polarizer, and is mounted on a liquid crystal display device. It is also known that a protective film is formed only on one side of a polarizer. However, in many cases, a layer having other optical functions is applied not only to the other side surface but also to a protective film. As a method for producing a polarizer, there has been widely adopted a method in which a uniaxially stretched polyvinyl alcohol based resin film dyed with a dichroic dye is subjected to boric acid treatment, washed with water and then dried.

Normally, the protective film is immediately adhered to the polarizer after washing and drying as described above. This is because the polarizer after drying has a weak physical strength and tends to tear in the processing direction once it is wound. Therefore, usually, an aqueous adhesive of an aqueous solution of a polyvinyl alcohol resin is applied immediately to the polarizer after drying, and a protective film is simultaneously applied to both surfaces of the polarizer via the adhesive. In general, a triacetylcellulose film having a thickness of 30 to 100 mu m is used as a protective film.

Triacetylcellulose is excellent in transparency and is easy to form various kinds of surface treatment layers and optical functional layers and has high moisture permeability and can be smoothly dried after being adhered to a polarizer using the above- On the other hand, a polarizing plate in which the polarizing plate is laminated as a protective film due to its high moisture permeability has a problem that it is liable to cause deterioration under a condition of, for example, a temperature of 70 DEG C and a relative humidity of 90% there was. It is also known to use an amorphous polyolefin resin having a lower moisture permeability than triacetyl cellulose, for example, a norbornene resin as a protective film.

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

Therefore, as an adhesive which gives a high adhesive force between a protective film made of a resin having a low moisture permeability and a polyvinyl alcohol polarizer, and also gives a high adhesive force between a resin having a high moisture permeability such as a cellulose resin and a polyvinyl alcohol polarizer, There is an attempt to use a photocurable adhesive. For example, Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 1) discloses an adhesive containing as an active ingredient an epoxy compound which does not contain an aromatic ring. The adhesive includes an active energy ray, specifically, It has been proposed that the adhesive is cured by cation polymerization to bond the polarizer and the protective film. Japanese Patent Laid-Open Publication No. 2008-257199 (Patent Document 2) discloses a photocurable adhesive comprising a combination of an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group, and further containing a photo cationic polymerization initiator, A technique for use in adhering a protective film is disclosed.

Japanese Patent Application Laid-Open No. 2004-245925 Japanese Patent Application Laid-Open No. 2008-257199

However, the adhesive of the composition specifically disclosed in Patent Document 1 or Patent Document 2 does not necessarily have a sufficiently low viscosity, and it is always necessary to coat the polarizer or the protective film to be adhered thereto to form a thin and uniform adhesive layer I did not. Some of these adhesives dissolve the protective film, resulting in dissolution of the protective film, resulting in bubble defects.

A problem to be solved by the present invention is to provide a polarizing plate in which a polarizer and a protective film are bonded to each other by using a photo-curable adhesive having a sufficiently low viscosity at room temperature when a protective film is applied to a polarizer and which does not melt the protective film. Another object of the present invention is to provide a laminated optical member which is preferably used in a liquid crystal display device by laminating another optical layer such as a retardation film on this polarizing plate.

The present inventors have conducted intensive studies to solve these problems, and as a result, they have completed the present invention. Specifically, a photocurable adhesive comprising a photocathode-curable component and a photocathode polymerization initiator in a predetermined amount, wherein the photocathode-curable component comprises a specific alicyclic diepoxy compound as a main component, A diglycidyl compound having two epoxy groups which are not bonded to the ring and having a branching structure such as a branched alkylene group, and further contains an epoxy group which is not bonded to the alicyclic ring, It is effective to use a composition comprising a small amount of a monofunctional epoxy compound having one epoxy group in its molecule. That is, the photocurable adhesive having such a specific composition has a small ability to dissolve the protective film, exhibits a low viscosity at room temperature and gives good application suitability, and strongly adheres the polarizer and the protective film after curing I found out. The present invention includes the following.

[1] A polarizer comprising a polarizer made of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorptively oriented, and a protective film made of a transparent resin bonded to at least one surface of the polarizer with an adhesive interposed therebetween, (A) contains 100 parts by weight of a photo cationic curable component (A) and 1 to 10 parts by weight of a photo cationic polymerization initiator (B), and the photo cationic curable component (A) ) And (A3), based on the total amount, based on the total amount of the photo-curable adhesive, wherein when the protective film is immersed in the photo-curable adhesive at 23 占 폚 for 2 days, Is 0 to 30% by weight.

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

[Chemical Formula 1]

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

(2)

, Y ¹ to Y ⁴ each represent an alkanediyl group having 1 to 20 carbon atoms, and when the number of carbon atoms is 3 or more, they may have an alicyclic structure; a and b each represent an integer of 0 to 20;

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

(3)

Z represents a branched alkylene 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 one or more and the other represents an integer of 2 or more, the sum of both is 8 or less, and one of C _m H _2m and C _n H _2n is Branched divalent saturated hydrocarbon group.

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

[Chemical Formula 4]

In the formula, R ³ represents an alkyl group having 1 to 15 carbon atoms.

[2] The polarizer 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 polarizer according to [1] or [2], wherein the photo-curable adhesive has a viscosity at 25 ° C of 100 mPa · sec or less.

[4] The polarizer according to any one of [1] to [3], wherein the photo-curable adhesive is cured.

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

[6] The protective film to be bonded onto at least one surface of the polarizer is any one of [1] to [4] comprising a transparent resin selected from the group consisting of an amorphous polyolefin resin, a polyester resin and a chained polyolefin resin &Lt; / RTI >

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

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

In the present invention, an alicyclic diepoxy compound (A1), a divalent group having a branching structure in a linking group, and a branching group, typically a branched group, are used as the photo cationic curing component (A) which is a main component of the photo- (A3) and a diglycidyl compound (A2) having an alkylene group and a monofunctional epoxy compound (A3), the photocurable adhesive has a low viscosity and does not dissolve the protective film well, The viscosity is low and the coating applicability is excellent. Therefore, when a protective film made of a transparent resin is bonded to at least one surface of the polarizer via the photo-curable adhesive, bubble defects caused by dissolution of the protective film are significantly reduced, and a polarizer having good adhesion between the polarizer and the protective film . In addition, a laminated optical member in which another optical layer is laminated on this polarizing plate also has few defects.

Hereinafter, embodiments of the present invention will be described in detail. The present invention provides a polarizing plate in which a protective film made of a transparent resin is bonded to a polarizer made of a polyvinyl alcohol based resin film via a photo-curable adhesive. The present invention also provides a laminated optical member in which another optical layer is laminated on the polarizing plate. The photo-curable adhesive used in the production of the polarizing plate, the polarizing plate using the same, and the laminated optical member will be described in order.

[Photocurable adhesive]

In the present invention, the photo-curable adhesive for bonding a protective film made of a transparent resin to a polarizer made of a polyvinyl alcohol-based resin film contains the following two components (A) and (B).

(A) a photocathode-curable component, and

(B) a photo cationic polymerization initiator.

(Photocathion-curable component)

The photo cationic curable component (A), which is the main component of the photo-curable adhesive and imparts an adhesive force by polymerization curing, contains the following three kinds of compounds.

(A1) an alicyclic diepoxy compound represented by the formula (I)

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

(A3) The monofunctional epoxy compound represented by the above formula (III).

In the formula (I) representing the alicyclic diepoxide compound (A1), R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. When the alkyl group has 3 or more carbon atoms, do. This alkyl group has 1-position of the cyclohexane ring to be bonded to X in the formula (I) (therefore, the positions of the epoxy groups in the two cyclohexane rings are all 3,4-positions), 1 It can be combined at any position of position - 6 position. The alkyl group may be linear, of course, or branched if it has 3 or more carbon atoms. As described above, when the number of carbon atoms is 3 or more, it may have an alicyclic structure. Typical examples of the alkyl group having an alicyclic structure include cyclopentyl and cyclohexyl.

Similarly, in the formula (I), X connecting the two 3,4-epoxycyclohexane rings is an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a divalent group represented by any of the formulas (Ia) to (Id) . Here, the alkanediyl group is a concept including an alkylene or an alkylidene, and the alkylene may be a straight chain or branched when it has 3 or more carbon atoms.

When X is a bivalent group represented by any of the formulas (Ia) to (Id), the connecting groups Y ¹ , Y ² , Y ³ and Y ⁴ in each formula are each an alkanediyl group having 1 to 20 carbon atoms , And when the alkanediyl group has 3 or more carbon atoms, it may have an alicyclic structure. These alkanediyl groups may of course be linear or branched if they have 3 or more carbon atoms. As described above, when the number of carbon atoms is 3 or more, it may have an alicyclic structure. Typical examples of alkanediyl groups having an alicyclic structure include cyclopentylene and cyclohexylene.

Specific examples of the alicyclic diepoxy compound (A1) represented by the formula (I) include a compound wherein X in the formula (I) is a divalent group represented by the formula (Ia) and a in the formula is 0 Is a copolymer of 3,4-epoxycyclohexylmethanol (the cyclohexane ring may have an alkyl group having 1 to 6 carbon atoms), 3,4-epoxycyclohexanecarboxylic acid (the cyclohexane ring having 1 to 6 carbon atoms Or an alkyl group may be bonded thereto). Specific examples thereof include 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [formula (I) wherein X is a divalent group represented by formula (Ia) in which a = 0) , A compound wherein R ¹ = R ² = H], 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate [compound of the formula (I) Methyl] cyclohexanecarboxylate [the compound wherein R ¹ = 6-methyl and R ² = 6-methyl], 3,4-epoxy-1-methylcyclohexylmethyl 3,4- (R ¹ = 1-methyl and R ² = 1 -methyl in the formula (I) having the general formula (1)), 3,4-epoxy-3-methylcyclohexylmethyl 3,4- [Compound in which R ¹ = 3-methyl and R ² = 3-methyl in the formula (I) having the same X as described above] and the like.

The compound wherein X in the formula (I) is a bivalent group represented by the formula (Ib) is obtained by reacting an alkylene glycol and 3,4-epoxycyclohexanecarboxylic acid (the cyclohexane ring thereof is bonded to an alkyl group having 1 to 6 carbon atoms Or an esterified product thereof. The compound wherein X in the formula (I) is a divalent group represented by the formula (Ic) is obtained by reacting an aliphatic dicarboxylic acid and 3,4-epoxycyclohexylmethanol (wherein the cyclohexane ring is bonded with an alkyl group having 1 to 6 carbon atoms ). The compound in which X in the formula (I) is a bivalent group represented by the formula (Id) is preferably an ether of 3,4-epoxycyclohexylmethanol (the cyclohexane ring may have an alkyl group having 1 to 6 carbon atoms) Or an ether of an alkylene glycol or a polyalkylene glycol and 3,4-epoxycyclohexylmethanol (the cyclohexane ring may have an alkyl group having 1 to 6 carbon atoms attached thereto) Cargo (if b> 0).

In the formula (II) representing the diglycidyl compound (A2), Z represents a branched alkylene 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 - 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, _{One of m} H _2m and C _n H _2n is a branched divalent saturated hydrocarbon group.

In formula (II), the compound wherein Z is a branched alkylene group is a diglycidyl ether of a 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, 3-methyl-1 , 5-pentanediol diglycidyl ether, 2-methyl-1,8-octanediol diglycidyl ether and 1,4-cyclohexanedimethanol.

In the formula (II), a compound wherein Z is a divalent group represented by the formula -C _m H _2m -Z ¹ -C _n H _2n - is preferably a compound wherein Z is a branched alkylene group and the CC bond of the alkylene group is -O-, -CO-O- or -O-CO-.

In the formula (III) representing a monofunctional epoxy compound, R ³ is an alkyl group having 1 to 15 carbon atoms. This alkyl group may be a linear chain, of course, and branched if it has 3 or more carbon atoms. The alkyl group preferably has a relatively large number of carbon atoms, for example, 6 or more, and more preferably 6 to 10 carbon atoms. Among them, it is preferably branched alkyl group. As a typical example of the monofunctional epoxy compound represented by the formula (III), 2-ethylhexyl glycidyl ether can be given.

The amount of the alicyclic diepoxy compound (A1) in the photocathione-curable component (A) is 30 to 85% by weight based on the total amount of the photocathode-curable component (A). The amount thereof is preferably 40 to 80% by weight, more preferably 60 to 75% by weight. When the amount of the alicyclic diepoxy compound (A1) in the photocathione-curable component (A) is too small, the curing becomes insufficient and the adhesion between the polarizer / protective film is reduced. On the other hand, when the amount is too large, the amount of the diglycidyl compound (A2) and the monofunctional epoxy compound (A3) to be described below is relatively decreased, which makes it difficult to lower the viscosity of the photocurable adhesive used in the present invention .

The amount of the diglycidyl compound (A2) having a branched structure in the linking group in the photocathode-curable component (A) is 1 to 69% by weight. The amount thereof is preferably 5 to 50% by weight, more preferably 5 to 30% by weight. If the amount of the diglycidyl compound (A2) in the photocathione-curable component (A) exceeds 69% by weight, the curing becomes insufficient and adhesion between the polarizer and the protective film deteriorates.

The amount of the monofunctional epoxy compound (A3) in the photo cationically curable component (A) is 1 to 69% by weight. The amount thereof is preferably 2 to 50% by weight, more preferably 2 to 15% by weight. If the amount of the monofunctional epoxy compound (A3) in the photocathione-curable component (A) is more than 69% by weight, the curing becomes insufficient and adhesion between the polarizer and the protective film deteriorates.

The photocathode-curing component (A) constituting the photocurable adhesive can be obtained by copolymerizing the alicyclic diepoxide compound (A1) described above, the diglycidyl compound (A2) having a branching structure at the linking group and the monofunctional epoxy compound (A3) , Respectively, in the proportions described above. The diglycidyl compound (A2) is preferably used in an amount sufficient to lower the viscosity of the photocurable adhesive prior to curing and to further improve the adhesion between the polarizer and the protective film by the cured product, based on the total amount of the photocurable adhesive, And the monofunctional epoxy compound (A3) is 25% by weight or more.

The photocathode-curable component (A) is contained in the range that the alicyclic diepoxide compound (A1), the diglycidyl compound (A2) having a branched structure in the linking group and the monofunctional epoxy compound (A3) And may contain other cationic polymerizable compounds.

(Photocathione polymerization initiator)

In the present invention, a photo cationic polymerization initiator (B) is added to the photo-curable adhesive composition in order to cure the above-mentioned photo cationic curable component by cationic polymerization by irradiation of an active energy ray to form an adhesive layer . The photocathione polymerization initiator initiates the polymerization reaction of the photocathode-curing component (A) by generating a cationic species or Lewis acid by irradiation with an active energy ray such as visible light, ultraviolet light, X-ray or electron beam . Since the photo cationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when it is mixed with the photo cationic curable component (A). As a compound which generates a cationic species or Lewis acid by irradiation with an active energy ray, for example, an aromatic diazonium salt; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-allene complex and the like.

As the aromatic diazonium salt, for example, the following compounds can be mentioned.

Benzene diazonium hexafluoroantimonate, benzene diazonium hexafluoroantimonate,

Benzene diazonium hexafluorophosphate,

Benzene diazonium hexafluoroborate and the like.

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

Diphenyl iodonium tetrakis (pentafluorophenyl) borate,

Diphenyl iodonium hexafluorophosphate,

Diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroantimonate,

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

As the aromatic sulfonium salt, for example, the following compounds may be mentioned.

Triphenylsulfonium hexafluorophosphate,

Triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate,

Triphenylsulfonium tetrakis (pentafluorophenyl) borate,

4,4'-bis [diphenylsulfonio] diphenyl sulfide bishexafluorophosphate,

4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,

4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenyl sulfide 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.

The iron-allene complexes include, for example, the following compounds.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,

Cumene-cyclopentadienyl iron (II) hexafluorophosphate,

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

These photocathione polymerization initiators may be used alone or in combination of two or more. Among them, an aromatic sulfonium salt is preferably used since it has an ultraviolet ray absorbing property in a wavelength region around 300 nm and is excellent in curability and can give a cured product having good mechanical strength and adhesive strength.

The blending amount of the photocathode polymerization initiator (B) is 1 to 10 parts by weight based on 100 parts by weight of the whole photocathode curing component (A). By compounding at least 1 part by weight of the photo cationic polymerization initiator per 100 parts by weight of the photo cationically curable component (A), the photo cationic curable component (A) can be sufficiently cured and a high mechanical strength and adhesive strength can be imparted to the resulting polarizer do. On the other hand, if the amount of the photo cationic polymerization initiator (B) is too large, the ionic substance in the cured product increases and the hygroscopicity of the cured product increases, which may lower the endurance performance of the polarizing plate. (A) is not more than 10 parts by weight per 100 parts by weight. The blending amount of the photocathode polymerization initiator (B) is preferably 2 parts by weight or more, more preferably 6 parts by weight or less, per 100 parts by weight of the photocathode curing component (A).

(Other components that can be blended in the photocurable adhesive)

The photocurable adhesive of the present invention can be used in combination with a photocathode curing component (A) and a photocathode polymerization initiator (B) containing an epoxy compound as described above and other photocurable resins or adhesives Or < / RTI > Preferable examples of other components include photosensitizers and photosensitizers. The photosensitizer is a compound that exhibits maximum absorption at a wavelength longer than the maximum absorption wavelength exhibited by the photocathione polymerization initiator (B) and promotes the polymerization initiation reaction by the photocathode polymerization initiator (B). Further, the photosensitizer is a compound that further promotes the action of the photosensitizer. Depending on the kind of the protective film, it may be preferable to blend such a photosensitizer and further a photosensitizer.

The photosensitizer is preferably a compound exhibiting maximum absorption in light having a wavelength longer than 380 nm. The photo cationic polymerization initiator (B) exhibits maximum absorption at a wavelength of about 300 nm or shorter and generates a cationic species or Lewis acid in response to light having a wavelength in the vicinity thereof to form a photo cationic curing component (A) However, when such a photosensitizer is blended, it is also sensitive to light having a wavelength longer than 380 nm, particularly longer than 380 nm. As such a photosensitizer, anthracene-based compounds are advantageously used. Specific examples of the anthracene-based photosensitizer 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-dipropoxyanthracene,

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

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 compounding the photosensitizer as described above, the curing property of the adhesive is improved as compared with the case where the photosensitizer is not blended. This effect is exhibited by blending at least 0.1 part by weight of a photosensitizer with respect to 100 parts by weight of the photocathione-curable component (A). On the other hand, when the compounding amount of the photosensitizer is increased, the amount of the photosensitizer is preferably 2 parts by weight or less based on 100 parts by weight of the photo cationic curing component (A). From the viewpoint of maintaining the neutral gray of the polarizing plate, it is advantageous to reduce the compounding amount of the photosensitizing agent within a range in which the adhesive strength between the polarizer and the protective film is appropriately maintained. For example, , And the amount of the photosensitizer is preferably in the range of 0.1 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight.

Next, the photosensitizer is described. There are various kinds of photo-sensitizers, but naphthalene-based compounds are advantageously used. Specific examples of the naphthalene-based photo-sensitization assistant include the following compounds.

4-methoxy-1-naphthol,

4-ethoxy-1-naphthol,

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, and the like.

By adding a naphthalene-based photo-sensitization assistant to the photo-curable adhesive, the curability of the adhesive improves as compared with the case where it is not blended. This effect is manifested by blending at least 0.1 part by weight of a naphthalene-based photo-sensitization assistant to 100 parts by weight of the photo cationically curable component (A). On the other hand, when the blending amount of the naphthalene-based photo-sensitization assistant is increased, the amount of the naphthalene-based photo-sensitization assistant is preferably 5 parts by weight or less based on 100 parts by weight of the photo cationic curing component (A) And further more preferably 3 parts by weight or less.

(Physical Properties of Photocurable Adhesive)

The above-described photocurable adhesive is used for producing a polarizing plate by attaching a protective film to a polarizer made of a polyvinyl alcohol-based resin film, as described above. At this time, if the adhesive dissolves the protective film, as described above, the dissolution may cause bubble defects in the polarizing plate. In the present invention, a photocurable adhesive in which a photocathode-curing component (A) containing the specified three kinds of compounds described above in a predetermined ratio is incorporated is used, and in particular, as the diglycidyl compound (A2) A compound in which the linking group has a branched structure, typically a compound in which the linking group is a branched alkylene group is employed, thereby making the adhesive not to dissolve the protective film well. That is, in this adhesive, when the protective film constituting the polarizing plate is immersed at 23 ° C for 2 days, the weight loss of the protective film is 0 to 30% by weight.

Here, the weight loss 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, the cut film is prepared in a liquid state, immersed in a light-curing adhesive maintained at a temperature of 23 占 폚, allowed to stand for 2 days, removed, and the adhesive adhered to the surface is wiped off and its weight is obtained. From the equation below, the weight loss after immersion is obtained.

Weight loss (%) = (1- weight of film after immersion / weight of film before immersion) x 100

Further, the adhesive is applied to at least one of the concave surfaces of the polarizer and the protective film, and then the two are superimposed with the adhesive layer interposed therebetween, whereby the adhesive is cured. In order to improve the applicability to the polarizer and / or the protective film, the viscosity of the adhesive is preferably low. In the present invention, as the photocathode curing component (A), the viscosity of the photocurable adhesive is lowered by blending the specified three kinds of the compounds described above at a predetermined ratio, and the application suitability is improved. Specifically, the photo-curable adhesive can have a viscosity of 100 mPa · sec or less at 25 ° C.

[Polarizer]

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 via the above-described photo-curable adhesive, and the photo-curable adhesive is cured to form a polarizing plate. In the present invention, as described above, the storage elastic modulus of the adhesive layer which is a cured product of the photo-curable adhesive can be increased, and the adhesion between the polarizer and the protective film can be enhanced. Therefore, the bonding strength by the 180 degree peel test between the polarizer and the protective film can be 0.6 N / 25 mm or more. Here, the 180 degree peel test is carried out in accordance with JIS K 6854-2: 1999 " Adhesive-peel adhesion strength test method- Part 2: 180 degree peel ".

Hereinafter, the polarizer and the protective film constituting the polarizing plate of the present invention will be described, and a manufacturing method of the polarizing plate will be briefly described.

(Polarizer)

The polarizer is composed of a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented. The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and other monomers copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and the like. The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehyde may be used. The polymerization degree 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 the polyvinyl alcohol-based resin film, a step of dying the polyvinyl alcohol-based resin film with a dichroic dye, a step of adsorbing the dichroic dye, a step of dyeing the dichroic dye- And a step of treating the resin film with an aqueous boric acid solution.

The uniaxial stretching may be carried out before dyeing with a dichroic dye or simultaneously with dyeing with a dichroic dye or after dyeing with a dichroic dye. In the case where uniaxial stretching is carried out after dyeing with a dichroic dye, the uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. Of course, uniaxial stretching can also be carried out in these plural stages. In the case of uniaxial stretching, the uniaxial stretching may be performed between rolls different in the main speed, or may be uniaxially stretched using hot roll. In addition, it may be dry stretching in which stretching is performed in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen by a solvent. The stretching magnification is usually about 4 to 8 times.

In order to dye a polyvinyl alcohol-based resin film with a dichroic dye, for example, a polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally employed. 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 the aqueous solution is usually about 20 to 40 占 폚, and the immersion time (dyeing time) for the aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of dying and dyeing a polyvinyl alcohol-based resin film into an aqueous solution containing a water-soluble dichroic organic dye is generally employed. The content of the dichroic organic dye in the aqueous solution is usually about 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80 DEG C, and the immersion time (dyeing time) for the aqueous solution is usually about 30 to 300 seconds.

The boric acid treatment after dyeing with the dichroic dye is carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous solution of boric acid. The boric acid content in the boric acid aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution of boric acid contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is generally about 2 to 20 parts by weight, preferably 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time for the boric acid aqueous solution is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 占 폚 or higher, preferably 50 to 85 占 폚.

The polyvinyl alcohol resin film after boric acid treatment is usually subjected to water washing treatment. The water washing treatment is carried out, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. After washing with water, drying treatment is carried out to obtain a polarizer. The temperature of the water in the water washing treatment is usually about 5 to 40 占 폚, and the immersion time is usually about 2 to 120 seconds. The drying process to be performed thereafter is usually carried out using a hot-air dryer or a far-infrared heater. The drying temperature is usually 40 to 100 ° C. The drying treatment time is usually about 120 to 600 seconds.

The thickness of the polarizer made of the polyvinyl alcohol-based resin film thus obtained can be about 10 to 50 mu m.

(Protective film)

A protective film is bonded to the polarizer made of the above-described polyvinyl alcohol based resin film via the above-described photo-curable adhesive, and the photo-curable adhesive is cured to form a polarizing plate. The protective film can be composed of an acetylcellulose resin film including triacetyl cellulose, which is most widely used as a protective film of a polarizing plate, or a resin film having lower moisture permeability than triacetyl cellulose. The moisture permeability of triacetyl cellulose is generally about 400 g / m 2/24 hr.

In one preferred form, the protective film to be bonded to at least one surface of the polarizer is composed of an acetylcellulose-based resin. In particular, the protective film to be adhered to one surface of the polarizer may be composed of an acetylcellulose resin in which an ultraviolet absorber is blended. In another preferred embodiment, the protective film to be bonded to at least one surface of the polarizer is composed of a resin film having a lower moisture permeability than triacetyl cellulose, for example, a resin film having a moisture permeability of 300 g / m 2/24 hr or less. Examples of the resin constituting the resin film having low moisture permeability include an amorphous polyolefin resin, a polyester resin, an acrylic resin, a polycarbonate resin, and a chained polyolefin resin. Among these, an amorphous polyolefin resin, a polyester resin and a chain polyolefin resin are preferably used. In another preferred embodiment, a protective film made of an acetylcellulose resin is bonded to one surface of the polarizer with the adhesive layer interposed therebetween. On the other surface of the polarizer, similarly to the above-mentioned adhesive layer, A protective film made of a transparent resin having a low refractive index is bonded.

The acetylcellulose-based resin may be a mixed ester in which at least a part of hydroxyl groups in cellulose are converted into an acetic acid ester, and a part thereof is converted into acetic acid ester and partly esterified with another acid. Specific examples of the acetylcellulose-based resin include triacetylcellulose, diacetylcellulose, cellulose acetate propionate, and cellulose acetate butyrate.

The amorphous polyolefin resin is a polymer having polymerized units of a cyclic olefin, such as norbornene or tetracyclododecene (also known as dimethanoctahydronaphthalene) or a compound having a substituent bonded thereto, and the cyclic olefin May be a copolymer obtained by copolymerizing a chain-like olefin and / or an aromatic vinyl compound. In the case of a homopolymer of cyclic olefin or a copolymer of two or more cyclic olefins, a double bond remains due to ring-opening polymerization, and hydrogenated there is generally used as an amorphous polyolefin resin. Among them, a thermoplastic norbornene resin is typical.

The polyester-based resin is a polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol, and polyethylene terephthalate is representative. The acrylic resin is a polymer containing methyl methacrylate as a main monomer and may be a homopolymer of methyl methacrylate as well as a copolymer of methyl methacrylate and an acrylic ester such as methyl acrylate or an aromatic vinyl compound. The polycarbonate resin is a polymer having a carbonate bond (-O-CO-O-) in the main chain and is typically obtained by condensation polymerization of bisphenol A and phosgene. The chain-like polyolefin-based resin is a polymer having a main chain of a chain-like olefin such as ethylene or propylene, and may be a homopolymer or a copolymer. Among them, a homopolymer of propylene or a copolymer in which propylene is copolymerized with a small amount of ethylene is typical.

Such a protective film may have various surface-treated layers such as a hard coat layer, an antireflection layer, an antiglare layer, or an antistatic layer on the surface opposite to the surface to be bonded to the polarizer. The thickness of the protective film, including the case where such a surface treatment layer is formed, can be set to about 5 to 150 mu m. The thickness thereof is preferably 10 占 퐉 or more, more preferably 120 占 퐉 or less, further preferably 100 占 퐉 or less.

(Production method of polarizing plate)

In the production of the polarizing plate, the application layer of the above-described photo-curable adhesive is formed on one or both of the side of the lamination of the polarizer and the protective film, the polarizer and the protective film are laminated via the applied layer, Of the photo-curable adhesive is cured by irradiation of active energy rays to fix the protective film on the polarizer. The coating layer of the photocurable adhesive may be formed on the coplanar surface of the polarizer or on the coplanar surface of the protective film. For forming the coating layer, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. It is also possible to employ a method in which the polarizer and the protective film are continuously supplied so that the concave surfaces of the polarizer and the protective film are inwardly and the adhesive is plied therebetween. Since each coating method has an optimum viscosity range, it is also useful to conduct viscosity adjustment using a solvent. The solvent for this purpose is one which dissolves the photo-curable adhesive well without deteriorating the optical performance of the polarizer, but there is no particular limitation on the kind thereof. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used. The thickness of the adhesive layer is usually 20 占 퐉 or less, preferably 10 占 퐉 or less, more preferably 5 占 퐉 or less. If the adhesive layer is thickened, the reaction rate of the adhesive is lowered, and the humidity resistance of the polarizing plate tends to deteriorate.

In one or both of the coplanar surfaces of the polarizer and the protective film, an easy adhesion treatment such as a corona discharge treatment, a plasma treatment, a flame treatment, a primer treatment, or an anchor coating treatment may be performed .

The light source used for irradiating the active energy ray to the coating layer of the photocurable adhesive may be one which generates ultraviolet rays, electron beams, X-rays, or the like. In particular, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps and the like having a light emission distribution with a wavelength of 400 nm or less are preferably used. The active energy ray irradiation intensity for the photocurable adhesive is determined for each desired composition and is not particularly limited, but it is preferable that the irradiation intensity in the wavelength range effective for activation of the photocathode polymerization initiator is 0.1 to 100 mW / desirable. If the light irradiation intensity to the photo-curable adhesive is too small, the reaction time becomes excessively long. On the other hand, if the light irradiation intensity is too high, heat radiated from the lamp and heat generated during polymerization of the photo- There is a possibility of causing yellowing or deterioration of the polarizer. The light irradiation time for the photo-curable adhesive is controlled for each composition to be cured and is not particularly limited, but is preferably set so that the accumulated light quantity, which is a product of irradiation intensity and irradiation time, is 10 to 5,000 mJ / cm 2. If the amount of accumulated light for the photo-curable adhesive is too small, the generation of active species derived from the photo-cation polymerization initiator is not sufficient and there is a possibility that the curing of the obtained adhesive layer becomes insufficient. On the other hand, The time becomes very long, which is detrimental to the productivity improvement.

When the protective film is attached to both surfaces of the polarizer, the active energy ray may be irradiated from either side of the protective film. For example, when one of the protective films contains an ultraviolet absorbing agent and the other protective film does not contain an ultraviolet absorbing agent , It is preferable to irradiate the active energy ray from the side of the protective film not containing the ultraviolet absorber in order to effectively utilize the irradiated active energy ray to increase the curing rate.

[Laminated Optical Member]

The polarizing plate of the present invention can be a laminated optical member by laminating optical layers having optical functions other than the polarizing plate. Typically, a laminated optical member is obtained by laminating an optical layer on a protective film of a polarizing plate with an adhesive or a pressure-sensitive adhesive interposed therebetween. In addition, for example, a photo-curable adhesive may be provided on one surface of a polarizer, And a protective film is laminated on the other surface of the polarizer, and the optical layer may be laminated and adhered to the other surface of the polarizer through an adhesive or a pressure-sensitive adhesive. In the latter case, if the photo-curable adhesive specified in the present invention is used as an adhesive for bonding the polarizer and the optical layer, the optical layer can be a protective film specified in the present invention at the same time.

Examples of the optical layer to be laminated on the polarizing plate include a polarizing plate disposed on the rear surface side of the liquid crystal cell such as a reflective layer, a transflective layer, a light diffusion layer, a condenser plate, And a brightness enhancement film. In addition, both of the polarizing plate disposed on the front surface side of the liquid crystal cell and the polarizing plate disposed on the back surface side of the liquid crystal cell have a retardation film laminated on the side facing the liquid crystal cell of the polarizing plate.

The reflective layer, the transflective layer, or the light diffusion layer is formed to be a reflective polarizing plate (optical member), a transflective polarizing plate (optical member), or a diffusion polarizing plate (optical member), respectively. The reflection type polarizing plate is used in a liquid crystal display device of the type that reflects and displays incident light on the viewer side, and since a light source such as a backlight can be omitted, the liquid crystal display device can be easily made thin. In addition, the transflective type polarizing plate is used in a liquid crystal display device of a type that is displayed in a light spot as a reflection type and in a dark place as light from a backlight. In the optical member as the reflection type polarizing plate, for example, a foil or a vapor deposition film made of a metal such as aluminum may be attached to a protective film on a polarizer to form a reflection layer. The optical member as a transflective type polarizing plate can be formed by making the above-mentioned reflective layer a half mirror, or containing a pearl pigment or the like and adhering a reflective plate exhibiting light transmittance to a polarizing plate. On the other hand, the optical member as the diffusion-type polarizing plate can be manufactured by 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, a method of adhering a film containing fine particles To form a fine concavo-convex structure on the surface.

In this case, for example, a method of forming a reflective layer reflecting the concavo-convex structure on the fine concavo-convex structure surface of the diffusion-type polarizing plate can be employed have. The reflective layer of the micro concavo-convex structure has an advantage of diffusing incident light by diffuse reflection to prevent directivity and glare, and to suppress unevenness of light and shade. The resin layer or film containing fine particles also has an advantage that the incident light and its reflected light are diffused when it penetrates the fine particle-containing layer, thereby suppressing unevenness in contrast. The reflective layer reflecting the surface micro concavo-convex structure can be formed by directly attaching a metal to the surface of the micro concavo-convex structure by, for example, vapor deposition, plating, or plating such as vacuum deposition, ion plating or sputtering . The fine particles to be blended for forming the surface micro concavo-convex structure may be inorganic fine particles such as silica, aluminum oxide, tin oxide, zirconia, tin oxide, indium oxide, cadmium oxide and antimony oxide having an average particle diameter of 0.1 to 30 탆 , Organic fine particles such as crosslinked or non crosslinked polymers, and the like.

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

The brightness enhancement film is used for the purpose of improving brightness in a liquid crystal display device. Examples of the brightness enhancement film include a reflective polarized light separation sheet designed to have a plurality of thin film films having different refractive index anisotropies, An orientation film of a cholesteric liquid crystal polymer, and a circularly polarized light separation sheet in which the alignment liquid crystal layer is supported on a film base.

On the other hand, the above-mentioned retardation film serving as an optical layer is used for the purpose of compensating a retardation by a liquid crystal cell or the like. Examples thereof include birefringent films made of stretched films of various plastics, films on which discotic liquid crystals or nematic liquid crystals are aligned and fixed, and those on which the liquid crystal layer is formed on a film substrate. When a liquid crystal layer is formed on a film substrate, a cellulose based resin film such as triacetyl cellulose is preferably used as the film substrate.

Examples of the plastic forming the birefringent film include a polyolefin resin such as amorphous polyolefin resin, polycarbonate resin, acrylic resin, polypropylene, polyvinyl alcohol, polystyrene, polyarylate, polyamide And the like. The stretched film may be processed in a suitable manner such as one-axis or two-axis. Further, two or more retardation films may be used in combination for the purpose of controlling optical characteristics such as broadening.

In the laminated optical member, it is preferable to use a retardation film as an optical layer other than the polarizing plate because it can effectively perform optical compensation when applied to a liquid crystal display device. The retardation value (in-plane and thickness directions) of the retardation film may be selected in accordance with the liquid crystal cell to be applied.

The laminated optical member can be formed as a laminate of two or more layers by combining a polarizing plate and one or more layers selected according to the purpose of use in the above-mentioned various optical layers. In this case, the various optical layers forming the laminated optical member are integrated with the polarizing plate by using an adhesive or a pressure-sensitive adhesive, but the adhesive or pressure-sensitive adhesive to be used therefor is not particularly limited as long as the adhesive layer and the pressure-sensitive adhesive layer are well formed. It is preferable to use a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoints of simplicity of the bonding operation and prevention of occurrence of optical deformation. As the pressure-sensitive adhesive, an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyether, or the like may be used as the base polymer. Among them, as in the case of an acrylic pressure-sensitive adhesive, it has excellent optical transparency, maintains appropriate wettability and cohesive force, has excellent adhesiveness to a substrate, and further has weather resistance and heat resistance. It is preferable to select and use those that do not cause the peeling problem. In the acrylic pressure-sensitive adhesive, an acrylic ester of a (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group or a butyl group and an acrylic monomer containing a functional group comprising (meth) acrylic acid or (meth) An acrylic copolymer having a weight average molecular weight of 100,000 or more, which is blended such that the glass transition temperature is preferably 25 占 폚 or lower, more preferably 0 占 폚 or lower, is useful as the base polymer.

The pressure-sensitive adhesive layer for the polarizing plate can be formed by, for example, dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a solution of 10 to 40% by weight and directly applying the solution to the polarizing plate, A method in which a pressure-sensitive adhesive layer is formed on a protective film in advance, and the polarizing plate is transferred onto a polarizing plate. The thickness of the pressure-sensitive adhesive layer is determined depending on its adhesive force and the like, but is preferably in the range of about 1 to 50 mu m.

The pressure-sensitive adhesive layer may contain a filler, a pigment, a colorant, an antioxidant, an ultraviolet absorber or the like, if necessary, such as glass fiber, glass beads, resin beads, metal powder or other inorganic powder. Examples of the ultraviolet absorber include a salicylate ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound.

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 may be any liquid crystal cell, for example, an active matrix drive type represented by a thin film transistor type or a simple matrix drive type represented by a super twisted nematic type, Can be formed. For adhesion of the laminated optical member and the liquid crystal cell, the same pressure-sensitive adhesive as that described above is generally used.

Example

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" indicating the content or amount are based on weight unless otherwise specified. The photocathode curing component and the photocathode polymerization initiator used in the following examples are as follows, and are represented by the respective symbols below.

(A) a photocathion-curable component

(a1) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [compound wherein R ¹ = R ² = H, X = -COOCH ₂ - in the formula (I)

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

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

(a3) 2-ethylhexyl glycidyl ether [a compound wherein R ³ = CH ₃ (CH ₂ ) ₃ -CH (CH ₂ CH ₃ ) -CH ₂ - in the above formula (III)].

(B) a photocathion polymerization initiator (abbreviated as " initiator " in the table)

(b1) triarylsulfonium hexafluorophosphate.

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

(1) Preparation of photocurable adhesive

The above photo cationic curing component and the photo cationic polymerization initiator were mixed at the compounding ratio (unit: parts) shown in Table 1 and defoamed to prepare a photo-curable adhesive liquid. The photocationic polymerization initiator (b1) was compounded as a 50% propylene carbonate solution, and the solid content was shown in Table 1.

(2) Viscosity measurement of the adhesive liquid at 25 ° C

For each of the adhesive solutions prepared above, the viscosity at 25 캜 was measured using a rotary viscoelasticity measuring apparatus "Physica MCR 301" manufactured by Anton Paar. The results are shown in Table 1.

(3) Solubility of the protective film

(Trade name: "N-TAC KC4FR-1 ", manufactured by Konica Minolta Opt Co., Ltd.) having a thickness of 40 占 퐉 and made of acetylcellulose resin was prepared. This retardation film is used for producing a polarizing plate by being bonded to a polyvinyl alcohol polarizer as a protective film having an optical compensation function. The phase difference film was cut to a size of 10 mm x 40 mm, and then immersed in 20 g of each of the adhesive liquids prepared above at a temperature of 23 DEG C for 2 days. Two days later, the retardation film was taken out, the adhesive liquid adhering to the protective film was removed with Ben Coat, and the weight was measured. From the weight of the film before immersion in the adhesive liquid and the weight of the film after immersion, the weight loss of the film was determined by the following formula, and the results are shown in Table 1.

As in Comparative Example 1, the ternary adhesive in which the alicyclic diepoxy compound (a1) and diglycidyl ether (a21) having branched alkylene as a linking group and the monofunctional epoxy compound (a3) were mixed, Although the solubility of the cellulose-based resin film is small, since the blending ratio of the alicyclic diepoxy compound (a1) is large, the viscosity becomes high, and the applicability in application to a protective film or a polarizer is not sufficient. On the other hand, in the case of using the diglycidyl ether (a22) having a straight chain alkylene group as a linking group as the diglycidyl compound (A2) as in Comparative Examples 2 and 3, the acetylcellulose resin The solubility of the film is increased. On the contrary, when a ternary adhesive containing a diglycidyl ether (a21) having a branching alkylene as a linking group and having the same mixing ratios as those of Examples 1 to 4, it has a low viscosity and a light curing property Adhesive.

The retardation films used in Examples 1 to 4 were bonded to one side of a polarizer on which iodine was adsorbed and aligned on a polyvinyl alcohol film via the photo-curing adhesive prepared in Examples 1 to 4, and the other side of the polarizer A triacetylcellulose film having a thickness of 80 mu m is laminated on the surface of the polarizing plate with the same adhesive agent, and ultraviolet rays are irradiated from the side of the retardation film to obtain a polarizing plate exhibiting good adhesion. In particular, as in Examples 1 and 2, when the amount of the alicyclic diepoxy compound (a1) in the photocathode-curable component is 50% or more, a high adhesive force can be obtained.

Claims

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 with an adhesive interposed therebetween,
Preferably,
100 parts by weight of the photo cationically curable component (A)
1 to 10 parts by weight of a photocathode polymerization initiator (B)
The light cationically curable component (A), based on its total amount,
The following formula (I)

(Wherein R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the alkyl group has 3 or more carbon atoms, the alkyl group may have an alicyclic structure;
X represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a group represented by the following formulas (Ia) to (Id):

, Y ¹ to Y ⁴ each represent an alkanediyl group having 1 to 20 carbon atoms, and when the number of carbon atoms is 3 or more, they may have an alicyclic structure;
a and b each represent an integer of 0 to 20)
, 30 to 85% by weight of an alicyclic diepoxy compound (A1)
(II): < EMI ID =

(Wherein Z represents a branched alkylene 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 one or more and the other represents an integer of 2 or more, 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 to 69% by weight of a diglycidyl compound (A2) represented by the following formula
The following formula (III)

(Wherein R ³ represents a branched alkyl group having 3 to 15 carbon atoms)
And 1 to 69% by weight of a monofunctional epoxy compound (A3) represented by the following formula
Wherein a weight loss of the protective film is 0 to 30% by weight when the protective film is immersed in the photocurable adhesive at 23 캜 for 2 days.

The method according to claim 1,
Wherein in the formula (III) representing the monofunctional epoxy compound (A3), R ³ is a branched alkyl group having 6 to 10 carbon atoms.

The method according to claim 1,
Wherein the photo-curable adhesive has a viscosity at 25 캜 of 100 mPa sec or less.

The method according to claim 1,
Wherein the photo-curable adhesive is cured.

The method according to claim 1,
The protective film to be bonded onto at least one surface of the polarizer is made of an acetylcellulose resin mixed with an ultraviolet absorber.

The method according to claim 1,
The protective film to be bonded onto at least one surface of the polarizer is made of a transparent resin selected from the group consisting of an amorphous polyolefin-based resin, a polyester-based resin and a chained polyolefin-based resin.

A laminated optical member comprising a laminate of the polarizing plate and another optical layer according to claim 1.

8. The method of claim 7,
Wherein the optical layer comprises a retardation film.