TWI666284B - Photocurable adhesive, polarizing plate using same, laminated optical member and liquid crystal display device - Google Patents

Abstract

The present invention provides a photocurable adhesive, which is a photocation-curable component (A) containing a first photocation-curable component (A1) containing an aromatic epoxy compound, a specified monomer (I), and / or The polymer (B) of the monomer (II) and the photocationic polymerization initiator (C) are 100 parts by weight based on the total amount of the photocationic curable component (A) and the polymer (B), and the polymer (B ) Is 2 to 10 parts by weight, the content of the first photocationically curable component (A1) is 10 to 40 parts by weight, and the content of the photocationic polymerization initiator (C) is 1 to 10 parts by weight; A polarizing plate, a laminated optical member, and a liquid crystal display device of the photocurable adhesive.

Description

Photocurable adhesive, polarizing plate, laminated optical member, and liquid crystal display device using the adhesive

The present invention relates to a photocurable adhesive for use on a polyvinyl alcohol-based polarizer and a protective film, and a polarizing plate, a laminated optical member, and a liquid crystal display device using the adhesive.

A polarizing plate is one of optical members that can be used to constitute a liquid crystal display device. A polarizing plate generally has a structure in which protective films are laminated on both sides of a polarizer, and is disposed on a liquid crystal display device. It is also known that a protective film is provided only on one side of the polarizer, but in most cases, the other side of the polarizer is not only a protective film but also a protective film that is followed by a film having other optical functions. As a method of manufacturing a polarizer, a method of subjecting a uniaxially stretched polyvinyl alcohol-based resin film dyed with a dichroic dye to boric acid treatment, washing with water, and drying is widely used.

Usually, the protective film is directly attached to the polarizer after the above-mentioned water washing and drying. Since the dried polarizer has reduced physical strength, once it is wound, there are problems such as easy cracking in the processing direction. situation. Therefore, usually, the polarizer after drying is directly coated with a water-based adhesive having a polyvinyl alcohol-based resin aqueous solution, and the protective film is simultaneously adhered to both sides of the polarizer through this adhesive. In general, the protective film is a triethylammonium cellulose film having a thickness of 30 to 100 μm.

Triethyl cellulose film is excellent in transparency, it is easy to form various surface treatment layers or optical function layers on the surface, and the moisture permeability is high. Although the water-based adhesive as described above is used to adhere to the polarizer, the drying can be smoothly performed. It has the advantage of being a protective film, but its reverse side has a high moisture permeability, and it is used as a polarizing plate for a protective film. Under humid heat, such as temperature of 70 ° C and relative humidity of 90%, it will easily cause problems such as degradation. situation. Therefore, it is also known that moisture permeability is lower than that of triethylfluorene-based cellulose, and for example, a norbornene-based resin is a representative example of an amorphous polyolefin-based resin as a protective film. Japanese Patent Application Laid-Open No. 06-051117 (Patent Document 1) describes that a thermoplastic saturated norbornene-based resin sheet is laminated as a protective film on at least one surface of a polarizer.

When a protective film made of a resin having low moisture permeability is attached to a polyvinyl alcohol-based polarizer, the polyvinyl alcohol-based polarizer and the triethylfluorene-based cellulose film are adhered. The aqueous solution used as an adhesive may have problems such as insufficient bonding strength and poor appearance of the obtained polarizing plate. This is because resin films with low moisture permeability are generally hydrophobic, or water as a solvent cannot be dried sufficiently due to low moisture permeability. On the other hand, it is also known that different types of protective films are adhered to both surfaces of the polarizer. For example, it is also proposed in Japanese Patent Application Laid-Open No. 2002-174729 (Patent Document 2) that one side of a polarizer is made of, for example, an amorphous polyolefin-based tree A protective film made of a resin having a low moisture permeability such as a grease, and a protective film made of a resin having a high moisture permeability such as a cellulose resin containing a triethylfluorene-based cellulose film is bonded to the other surface of the polarizer.

Therefore, a high adhesion is provided between a protective film made of a resin having a low moisture permeability and a polyvinyl alcohol-based polarizer, and a high adhesion is also provided between a resin having a high moisture permeability such as a cellulose resin and a polyvinyl alcohol-based polarizer. As a strong adhesive, there have been attempts to use a photocurable adhesive. For example, in Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 3), an epoxy compound containing no aromatic ring as a main component is disclosed, which is proposed to be irradiated with active energy rays, specifically, by irradiating with active energy rays. The adhesive is hardened by the cationic polymerization produced by the irradiation of ultraviolet rays, and then the polarizer and the protective film are adhered. In Japanese Patent Application Laid-Open No. 2008-257199 (Patent Document 4), a combination of an alicyclic epoxy compound and an epoxy compound not containing an alicyclic epoxy group is disclosed, and a photo-cationic polymerization initiator is prepared. A hardening adhesive is used for the technique of adhering a polarizer and a protective film.

The epoxy-based adhesive disclosed in Patent Document 3 is effective for a protective film composed of an amorphous polyolefin-based resin or a cellulose-based resin and the like on a polarizer, but it is effective for adhering to a (meth) acrylic resin. When the protective film is used, it is obvious that the adhesion is not necessarily sufficient.

In Japanese Patent Application Laid-Open No. 2012-172026 (Patent Document 5), an adhesive for an optical film is disclosed, which is based on 100% by weight of the active energy ray-curable compound (A), and contains an epoxy group or an oxa group. Cyclobutyl (oxetanyl), active energy ray cation hardening type compound without active energy ray radical polymerizable functional group with a weight average molecular weight of less than 5000 The substance (a1) is 5 to 100% by weight, the active energy ray radical-curing compound (a2) is 0 to 95% by weight, and it has an epoxy group or The acrylic resin (B) having an oxetan weight average molecular weight of 5,000 to 150,000 contains 0.0001 to 2 parts by weight. However, if the content of the acrylic resin (B) exceeds 2 parts by weight, the viscosity of the adhesive increases, and there is a possibility that the smoothness of the coating surface is deteriorated (see paragraph [0079]). Therefore, the acrylic resin ( The content of B) is set to 2 parts by weight or less.

In Japanese Patent Application Laid-Open No. 2012-007080 (Patent Document 6), it is proposed to use a cationically polymerizable component containing a polyfunctional alicyclic epoxy compound (A) and a monofunctional epoxypropyl compound (B) and to contain photopolymerization. A method of bonding a polarizer and a protective film to a photocurable adhesive having an initiator viscosity of 10 to 150 mPa · s. However, the epoxy-based adhesive disclosed in Patent Document 6 is also effective for attaching a protective film composed of an amorphous polyolefin-based resin, a cellulose-based resin, and the like to a polarizer, and is effective for adhering a (meth) acrylic-based adhesive. In the case of a protective film made of resin, the adhesion may not be sufficient.

Japanese Patent Application Laid-Open No. 2013-092762 (Patent Document 7) discloses a method of manufacturing a polarizing plate as a method of manufacturing a polarizing plate that is difficult to generate air bubbles between a polarizing film (polarizing film) and a transparent film. The manufacturing method includes the steps of applying an active energy ray-curable adhesive on one surface of a transparent film, and bonding one or both sides of a polarizing film to a surface on which a transparent film is coated with an adhesive to produce a laminated body. A step, and a step of producing a polarizing plate by irradiating an active energy ray on the laminated body, and a diameter of a laminating roller used in the step of producing the laminated body is in a range of 50 to 250 mm.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 06-051117

[Patent Document 2] Japanese Patent Laid-Open No. 2002-174729

[Patent Document 3] Japanese Patent Laid-Open No. 2004-245925

[Patent Document 4] Japanese Patent Laid-Open No. 2008-257199

[Patent Document 5] Japanese Patent Laid-Open No. 2012-172026

[Patent Document 6] Japanese Patent Laid-Open No. 2012-007080

[Patent Document 7] Japanese Patent Laid-Open No. 2013-092762

An object of the present invention is to provide a polarizing plate that has a sufficiently low viscosity when applied at room temperature when a protective film is attached to a polyvinyl alcohol-based polarizer, and can provide an improved adhesion between the polarizer and the protective film. Light-curing adhesive. Another object of the present invention is to provide a low-viscosity photocurable adhesive agent capable of adhering a polyvinyl alcohol-based polarizer and a protective film without generating bubbles in the adhesive agent layer even when the thickness of the adhesive agent layer is reduced. Still another object of the present invention is to provide a laminated optical member in which other optical layers are laminated on the above-mentioned polarizing plate, and a liquid crystal display device containing the optical member.

The present invention provides a curable adhesive, a polarizing plate, a laminated optical member, and a liquid crystal display device as described below.

[1] A photocurable adhesive for attaching a protective film containing a thermoplastic resin on a polyvinyl alcohol-based polarizer, which contains an aromatic epoxy compound as a first photocationic curable component (A1) Photocation-curable component (A); 1 derived from the group consisting of monomer (I) represented by formula (I) below and monomer (II) represented by formula (II) below Polymer (B) as a constituent unit of more than one monomer

(Wherein X represents a hydrogen atom or an alkyl group having 1 to 7 carbon atoms which may be substituted with one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, a hydroxyl group and a carboxyl group, (1 to 7 carbon alkoxy groups, 6 to 12 carbon aryl groups, 6 to 12 carbon aryloxy groups or 6 to 10 alicyclic hydrocarbon groups)

(In the formula, R ¹ represents a hydrogen atom, a methyl group, or a halogen atom. Y represents a carbon that may be substituted with one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, a hydroxyl group, and a carboxyl group. An alkyl group having 1 to 7, an aryl group having 6 to 12 carbons or an alicyclic hydrocarbon group having 6 to 10 carbons); and a photocationic polymerization initiator (C); wherein The content is 2 to 10 parts by weight based on 100 parts by weight of the total amount of the photocationically curable component (A) and the polymer (B). The content of the first photocationically curable component (A1) is described above. The total content of the photocationically curable component (A) and the polymer (B) is 10 to 40 parts by weight, and the content of the photocationic polymerization initiator (C) is relative to the photocationically curable property. The total amount of the component (A) and the aforementioned polymer (B) is 100 parts by weight, and is 1 to 10 parts by weight.

[2] The photocurable adhesive according to [1], wherein the photocationically curable component (A) is selected from the group consisting of an aliphatic diglycidyl compound, a monofunctional aliphatic epoxy compound, and a vinyl group. One or more second photocationically hardenable components (A2) in the group of ether compounds and oxetane compounds.

[3] The photocurable adhesive according to [2], wherein the aliphatic diglycidyl compound is a compound represented by the following formula (III):

(In the formula, Z represents a linear or branched alkylene group having 1 to 9 carbon atoms, or a divalent alicyclic hydrocarbon group. The methylene group in the alkylene group may be selected from an oxygen atom, -CO- O-, -O-CO-, -SO _2- , -SO- or -CO- divalent substitution).

[4] The photocurable adhesive according to [3], wherein Z in the formula (III) is a branched alkylene group having 3 to 10 carbon atoms.

[5] The photocurable adhesive according to any one of [2] to [4], wherein a content of the second photocationically curable component (A2) is equal to that of the photocationically curable component (A). The total amount of the polymer (B) is 58 to 88 parts by weight based on 100 parts by weight.

[6] The photocurable adhesive according to any one of [1] to [5], wherein the weight average molecular weight of the polymer (B) is 5,000 to 500,000.

[7] The photocurable adhesive according to [6], wherein the weight average molecular weight of the polymer (B) is 6000 to 100,000.

[8] The photocurable adhesive according to any one of [1] to [7], wherein the moisture content is based on the total amount of the photocationically curable component (A) and the polymer (B). 100 parts by weight is 4 parts by weight or less.

[9] The photocurable adhesive according to any one of [1] to [8], wherein the viscosity is 25 to 300 mPa · s at 25 ° C.

[10] A polarizing plate comprising: a polyvinyl alcohol-based polarizer, and the photohardenability described in any one of [1] to [9] on at least one side of the polyvinyl alcohol-based polarizer. The hardened | cured material of an adhesive agent is bonded and contains the protective film of a thermoplastic resin.

[11] The polarizing plate according to [10], wherein the thermoplastic resin is selected from the group consisting of a cellulose resin, a (meth) acrylic resin, an amorphous polyolefin resin, a polyester resin, and a polycarbonate. One or more resins in the group of resins.

[12] The polarizing plate according to [10] or [11], wherein the protective film contains an ultraviolet absorber.

[13] The polarizing plate according to any one of [10] to [12], wherein a peel strength between the polyvinyl alcohol-based polarizer and the protective film measured by a 180-degree peel test is 0.5 N / 25mm or more.

[14] A laminated optical member comprising a laminated body comprising the polarizing plate according to any one of [10] to [13] and one or more other optical layers.

[15] The laminated optical member according to [14], wherein the other optical layer includes a retardation plate.

[16] A liquid crystal display device comprising a liquid crystal cell and a laminated optical member according to [14] or [15] arranged on at least one surface of the liquid crystal cell.

According to the system of the present invention, a photocurable adhesive is provided, which has a low viscosity and is difficult to generate bubbles in the adhesive layer, and enables the polyvinyl alcohol-based polarizer and the protective film to be adhered with a high adhesive strength. According to the photocurable adhesive of the present invention, a polarizing plate having a high bonding strength between a polyvinyl alcohol-based polarizer and a protective film can be provided even when a protective film containing a (meth) acrylic resin is next bonded. The polarizing plate with high bonding strength described in the present invention, and the laminated optical member and liquid crystal display device using the polarizing plate are excellent in durability.

1‧‧‧ polarizer

2, 3‧‧‧ protective film

4‧‧‧ laminated body

5a, 5b ‧‧‧ laminating roller

11, 12‧‧‧ Adhesive coating device

13‧‧‧roller

14, 15‧‧‧ the first active energy ray irradiation device

16‧‧‧Second active energy ray irradiation device

17‧‧‧ the third active energy ray irradiation device

18‧‧‧The fourth active energy ray irradiation device

19‧‧‧ Transport roller

20‧‧‧ Winding roller

[Fig. 1] A schematic sectional view showing a preferred example of an apparatus for manufacturing a polarizing plate of the present invention.

<Photocurable Adhesive>

The curable adhesive of the present invention is an adhesive used for attaching a protective film containing a thermoplastic resin on a polyvinyl alcohol-based polarizer, and contains a photocationically curable component (A), a polymer (B), and a photocationic polymerization initiation. Agent (C).

(1) Photocationic hardening component (A)

The main component of the photocurable adhesive is a photocationic curable component (A) that imparts adhesive force by polymerization hardening, and is a first photocationic curable component (A1) containing at least an aromatic epoxy compound. The photocationically curable component (A) preferably contains a second photocationically curable component (A2) different from (A1) in addition to the first photocationically curable component (A1).

(1-1) The first photocationically curable component (A1)

The first photocationically curable component (A1) contains an aromatic epoxy compound. The so-called aromatic epoxy compound is an epoxy compound having an aromatic ring. However, in the aromatic epoxy compound here, X and / or Y in the polymer (B) described later is an aromatic ring and an epoxy group, and does not include polymers belonging to the aromatic epoxy compound by classification. (B). The first photocation-curable component (A1) may contain two or more kinds of aromatic epoxy compounds. Specific examples of the aromatic epoxy compound include monovalent phenols such as phenol, cresol, and butylphenol, bisphenol derivatives such as bisphenol A and bisphenol F, and alkylene oxide adducts thereof. Mono- or polyglycidyl etherate; epoxy novolac resin; mono- or poly-aromatic compounds such as resorcinol, hydroquinone or catechol, which have more than two phenolic hydroxyl groups Glycidyl etherate; aromatics with two or more alcoholic hydroxyl groups, such as benzyl alcohol, benzene diethanol, or xylene butanol Glycidyl etherate of family compounds; Glycidyl esters of polycarboxylic acid aromatic compounds with two or more carboxyl groups such as phthalic acid, terephthalic acid, and trimellitic acid; Glycidyl esters of benzoic acid Or epoxypropyl esters of toluic acid, naphthoic acid, etc .; styrene oxides, alkylated styrene oxides, or styrene oxides of vinylnaphthalene, or bisepoxides of divinylbenzene Wait.

Among these, from the viewpoints of curability and adhesion, the first photoion-curable component (A1) preferably contains a polyfunctional aromatic epoxy compound, and more preferably contains a trifunctional or more aromatic epoxy compound.

From the viewpoint of hardenability and adhesiveness, the aromatic epoxy compound is preferably one having an epoxy equivalent of 80 to 500.

As the aromatic epoxy compound, commercially available products can be used, and examples thereof include "DENACOL EX-145", "DENACOL EX-146", "DENACOL EX-147", "DENACOL EX-201", "DENACOL EX-711", "DENACOL EX-721", "ON COURT EX-1020", "ON COURT EX-1030", "ON COURT EX-1040", "ON COURT EX-1050", "ON COURT EX-1051", "ON COURT EX-1010 "," ON COURT EX-1011 "and" ON COURT EX-1012 "(Above, any of them are made by Nagase ChemteX Co., Ltd.);" OGSOL PG-100 "," OGSOL EG-200 ", "OGSOL EG-210" and "OGSOL EG-250" (Above, any of them are manufactured by Osaka Gas Chemicals Co., Ltd.); "HP4032", "HP4032D" and "HP4700" (Above, any of them are DIC Co., Ltd.); "ESN-475V" (above, Any one is made by Nippon Steel & Sumitomo Chemical Co., Ltd.); "152", "154", "157S70" and "YX8800" (Above, any of them are made by Mitsubishi Chemical Co., Ltd.); "ADEKA RESIN EP-4100 "," ADEKA RESIN EP-4100G "," ADEKA RESIN EP-4100E "," ADEKA RESIN EP-4100L "," ADEKA RESIN EP-4100TX "," ADEKA RESIN EP-4000 "," ADEKA RESIN EP- 4005 "," ADEKA RESIN EP-4082HT "," ADEKA RESIN EP-4901 "," ADEKA RESIN EP-4901E "," ADEKA GLYCINATE ROLL ED-501 "," ADEKA GLYCINATE ROLL ED-509E "," ADEKA GLYCINATE ROLL ED " -509S "and" ADEKA GLYCINATE ROLL ED-529 "(Above, any of them are made by ADEKA Corporation);" TECHMORE VG3101L "(made by Printeq Corporation), etc.

The content of the first photocationically curable component (A1) is 10 to 40 parts by weight, and preferably 12 to 40 parts by weight based on 100 parts by weight of the total amount of the photocationically curable component (A) and the polymer (B) described later. 35 parts by weight. When the first photocationically curable component (A1) is contained in an amount of 10 parts by weight or more, the adhesive strength between the polyvinyl alcohol-based polarizer and the protective film is excellent, and the viscosity of the photocurable adhesive is lowered and the good properties are accompanied by this. Coatability can be achieved in parallel. On the other hand, when the amount of the first photocationically curable component (A1) exceeds 40 parts by weight, the above-mentioned coexistence is difficult to achieve, and in particular, the viscosity tends to increase. When the amount of the first photocationically curable component (A1) is less than 10 parts by weight, excellent adhesion strength cannot be obtained.

(1-2) The second photocationically curable component (A2)

The photocation-curable component (A) preferably contains a second photocation-curable component (A2) different from (A1) in addition to the first photocation-curable component (A1). The second photocationically curable component (A2) is a curable component selected from the group consisting of aliphatic diepoxypropyl compounds, monofunctional aliphatic epoxy compounds, vinyl ether compounds, and oxetane compounds, and may also include Two or more of these are curable components. However, in the so-called monofunctional aliphatic epoxy compound, X or Y in the polymer (B) described later has an epoxy group, and does not include the polymer (B) which belongs to the monofunctional aliphatic epoxy compound. ). In addition, among the so-called oxetane compounds, those in which X or Y in the (B) described later has an oxetanyl group do not include polymers (B) which are oxetane compounds. .

The second photocationically curable component (A2) preferably contains an aliphatic diglycidyl compound. Among them, the viscosity of the photocurable adhesive is reduced, that is, the viscosity is easily adjusted to 2 to 300 mPa at 25 ° C. The range of s is therefore preferably a compound represented by the following formula (III):

Z in the formula (III) represents a linear or branched alkylene group having 1 to 9 carbon atoms, or a divalent alicyclic hydrocarbon group, and the methylene group in the alkylene group may be selected from an oxygen atom, -CO-O-, -O-CO-, -SO _2- , -SO- or -CO- is substituted by a divalent group. Typical examples of the divalent alicyclic hydrocarbon group are a cyclopentyl group and a cyclohexyl group.

In the above formula (III), the compound is a diglycidyl ether of an alkylene glycol in which Z is an alkylene group. This specific example contains ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 3-propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and the like. Among them, from the viewpoint of reducing the viscosity of the photocurable adhesive, the compound in which Z is an alkylene group in the formula (III) is preferably propylene glycol diglycidyl ether, neopentyl glycol diepoxy A compound of propyl ether in which Z in the above formula (III) is a branched alkylene group having 3 to 10 carbon atoms.

Examples of the monofunctional aliphatic epoxy compound include a glycidyl etherate of an aliphatic alcohol, a glycidyl ester of an alkyl carboxylic acid, and the like. Specific examples thereof include allyl glycidyl ether. , Butylglycidyl ether, 2nd butylphenylglycidyl ether, 2-ethylhexylglycidyl ether, alkyl glycidyl ether with mixed carbon number 12 and 13, ring of alcohol Oxypropyl ethers, monoglycidyl ethers of aliphatic higher alcohols, glycidyl esters of higher fatty acids, etc.

Examples of the vinyl ether compound include aliphatic or alicyclic vinyl ether compounds. Specific examples include n-pentyl vinyl ether, isoamyl vinyl ether, n-hexyl vinyl ether, and n-octyl ethylene. Ethyl, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, octadecyl vinyl ether, stearyl vinyl ether, etc. Ethers; 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether and other hydroxyl-containing vinyl ethers; cyclohexyl vinyl ether, 2-methyl ring Hexyl vinyl ether, cyclohexyl methyl vinyl ether, benzyl vinyl ether and other vinyl ethers with aliphatic or aromatic ring monohydric alcohols; glycerol monovinyl ether, 1,4-butane Glycol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, neopentyl tetraol divinyl ether, neopentyl tetraol tetravinyl ether, trimethylolpropane divinyl ether, Methylolpropane trivinyl ether, 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,4-dihydroxymethylcyclohexane monoethylene Mono- or polyvinyl ethers of polyhydric alcohols such as alkyl ethers, 1,4-dihydroxymethylcyclohexane divinyl ether; diethylene glycol divinyl ether, triethylene glycol divinyl ether, diethyl ether Polyalkylene glycol mono- or divinyl ethers such as glycol monobutyl monovinyl ether; other vinyl ethers such as epoxypropyl vinyl ether, ethylene glycol vinyl ether methacrylate, and the like.

An oxetane compound is a compound having an oxetanyl group. This specific example includes: 3,7-bis (3-oxetanyl) -5-oxe-nonane, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1, 3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, triethylene glycol bis ( 3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3-ethyl-3-oxo Heterocyclobutylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, 3-ethyl-3-[(phenoxy) methyl] oxa Cyclobutane, 3-ethyl-3- (hexyloxymethyl) oxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3- Ethyl-3- (hydroxymethyl) oxetane, 3-ethyl-3- (chloromethyl) oxetane, and the like.

The content of the second photocationically curable component (A2) is not particularly limited as long as the content of the first photocationically curable component (A1) is within the above range, but the photocationically curable component (A) and the polymer (described later) B) Of 100 parts by weight in total, 58 to 88 parts by weight is preferred, and 60 to 85 parts by weight is more preferred. When the content of the second photocationic curable component (A2) is within the above range, it is easy to prepare a photocurable adhesive having a viscosity of 2 to 300 mPa · s at 25 ° C. On the other hand, when the content of the second photocationically curable component (A2) exceeds 88 parts by weight, the adhesion strength between the polarizer and the protective film tends to be insufficient.

(1-3) the third photocationically curable component (A3)

The photocationically curable component (A) is a third photocationically curable component that may contain other curable components in addition to the first photocationically curable component (A1) and the second photocationically curable component (A2). (A3). Examples of the third photocationically curable component (A3) include epoxy compounds (for example, alicyclic epoxy compounds), cyclic lactone compounds, and cyclic compounds which do not belong to any of (A1) and (A2). Acetal compounds, cyclic thioether compounds, spiro orthoester compounds, and the like. The content of the third photocationically curable component (A3) is not particularly limited as long as the content of the first photocationically curable component (A1) falls within the above range. When the second photocationically curable component (A2) is contained, it is preferable The content of the second photocationically curable component (A2) is an amount in the above range.

(2) Polymer (B)

The polymer (B) is derived from a monomer (I) selected from the group consisting of the following formula (I): And the monomer (II) represented by the following formula (II):

A polymer of constituent units of one or more monomers in the group. Specifically, examples thereof include an oligomer obtained by polymerizing one monomer (I), a copolymer obtained by polymerizing two or more monomers (I), and a polymer obtained by polymerizing one monomer (II). An oligomer, a copolymer obtained by polymerizing two or more monomers (II), a copolymer obtained by polymerizing one or more monomers (I) and one or more monomers (II), and two or more of these mixture.

X in the above formula (I) represents a hydrogen atom, or a carbon number of 1 to 7 partially substituted with one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, a hydroxyl group and a carboxyl group Alkyl, alkoxy having 1 to 7 carbons, aryl having 6 to 12 carbons, aryloxy having 6 to 12 carbons or alicyclic hydrocarbon group having 6 to 10 carbons.

Examples of the alkyl group having 1 to 7 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, third butyl, isobutyl, n-pentyl, Isopentyl, 3rd pentyl, n-hexyl, 2-hexyl, 3-hexyl, cyclohexyl, 4-methylcyclohexyl, n-heptyl, 2-heptyl, 3-heptyl, isoheptyl, 3rd Heptyl and others. Among these, from the viewpoint of durability of the adhesive layer, an alkyl group having 1 to 4 carbon atoms is preferred.

Examples of the alkoxy group having 1 to 7 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, second butoxy, third butoxy, Isobutoxy, n-pentyloxy, isopentyloxy, third pentyloxy, n-hexyloxy, 2-hexyloxy, 3-hexyloxy, cyclohexyloxy, 4- Methylcyclohexyloxy, n-heptyloxy, 2-heptyloxy, 3-heptyloxy, isoheptyloxy, 3heptyloxy and the like. Among these, from the viewpoint of durability of the adhesive layer, an alkoxy group having 1 to 4 carbon atoms is preferred.

Examples of the aryl system having 6 to 12 carbon atoms include phenyl, methylphenyl, and naphthyl. The carbon number is preferably 6 to 10.

Examples of the aryloxy system having 6 to 12 carbon atoms include phenoxy, methylphenoxy, and naphthyloxy. The carbon number is preferably 6 to 10.

Examples of the alicyclic hydrocarbon group having 6 to 10 carbon atoms include cyclohexyl, methylcyclohexyl, norbornyl, dicyclopentyl, bicyclooctyl, trimethyldicycloheptyl, and tricyclooctyl , Tricyclodecyl, spirooctyl, spirobicyclopentyl, adamantyl, isobornyl, and the like.

X in the formula (I) is an alkyl group having 1 to 7 carbon atoms and carbon partially substituted with one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, a hydroxyl group and a carboxyl group. When an alkoxy group having 1 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, or an alicyclic hydrocarbon group having 6 to 10 carbon atoms, the functional group imparts a hardening reaction and has The durability of the adhesive layer and the advantage of suppressing the exudation of low molecular weight components from the adhesive layer. Among them, the functional group is preferably one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, and a hydroxyl group.

In the above formula (I), the monomer (I) when a part of X is substituted with an epoxy group or an oxetanyl group may be represented by the following formulae (Ia), (Ib), and (Ic) Of the monomer.

(In the formula, R ⁴ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m represents an integer of 1 to 6).

(In the formula, R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 1 to 6).

(In the formula, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and s represents an integer of 1 to 6).

R ¹ in the above formula (II) represents a hydrogen atom, a methyl group, or a halogen atom. Y represents an alkyl group having 1 to 7 carbon atoms and an aryl group having 6 to 12 carbon atoms which may be substituted with one or more functional groups selected from the group consisting of epoxy group, oxetanyl group, hydroxyl group and carboxyl group. And alicyclic hydrocarbon groups having 6 to 10 carbon atoms.

Examples of the halogen atom system include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Specific examples of the alkyl group having 1 to 7 carbon atoms, the aryl group having 6 to 12 carbon atoms, and the alicyclic hydrocarbon group having 6 to 10 carbon atoms are shown in the formula X in (I) is the same.

Same as X in formula (I), Y in formula (II) is a carbon partially substituted with one or more functional groups selected from the group consisting of epoxy, oxetanyl, hydroxyl and carboxyl groups When an alkyl group having 1 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alicyclic hydrocarbon group having 6 to 10 carbon atoms, the above functional group contributes to the hardening reaction, and has the durability of the adhesive layer and inhibits self-adhesion. Advantages of exudation of low molecular weight components of the agent layer. Among them, the functional group is preferably one or more functional groups selected from the group consisting of an epoxy group, an oxetanyl group, and a hydroxyl group.

Examples of the monomer (II) in the formula (II) when a part of Y is substituted with an epoxy group or an oxetanyl group are as shown in the following formulae (IIa), (IIb), and (IIc) Of the monomer.

(In the formula, R ¹ is the same as the above formula (II), R ⁷ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and t represents an integer of 1 to 6).

(In the formula, R ¹ is the same as the above formula (II), R ⁸ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and p represents an integer of 1 to 6)

(In the formula, R ¹ is the same as the above formula (II), R ⁹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and q represents an integer of 1 to 6)

From the viewpoint of the coexistence of the reduction in viscosity of the adhesive strength between the polyvinyl alcohol-based polarizer and the protective film and the light-curing adhesive, the polymer (B) is a standard polystyrene by gel permeation chromatography (GPC). The converted weight average molecular weight is preferably 5,000 to 500,000, and more preferably 6,000 to 100,000.

The content of the polymer (B) is 2 to 10 parts by weight, and preferably 2.5 to 10 parts by weight, based on 100 parts by weight of the total amount of the photocationically curable component (A) and the polymer (B). By containing the polymer (B) in an amount of 2 parts by weight or more, it was found that the adhesion between the polyvinyl alcohol-based polarizer and the protective film (especially a protective film containing a (meth) acrylic resin) can be improved while ensuring low viscosity. The effect of intensity. On the other hand, when the content of the polymer (B) exceeds 10 parts by weight, the viscosity of the photocuring adhesive becomes high. When it is less than 2 parts by weight, the adhesiveness with a protective film containing a (meth) acrylic resin is particularly low. The "(meth) acrylic acid" in this specification means at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth) acrylate".

(3) Photocationic polymerization initiator (C)

The photocurable adhesive system contains a photocationic polymerization initiator (C). Therefore, the photocationically curable component (A) is cured by cation polymerization by irradiation with active energy rays, and an adhesive layer can be formed. Photocationic polymerization initiation The agent (C) is irradiated with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams to generate a cationic substance or Lewis acid, thereby starting the polymerization reaction of the photocationic hardening component (A). By. Since the photocationic polymerization initiator (C) performs photocatalytic action with light, even when mixed with the photocationic hardening component (A), it has excellent storage stability and workability. Compounds that generate a cationic substance or a Lewis acid by irradiation with an active energy ray that can be used as the photocationic polymerization initiator (C) include, for example, aromatic diazonium salts; such as aromatic sulfonium salts and aromatic sulfonium salts. Onium salts; iron-arene complexes and the like.

Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

Examples of the aromatic iodonium salt include diphenylphosphonium (pentafluorophenyl) borate, diphenylphosphonium hexafluorophosphate, diphenylphosphonium hexafluoroantimonate, and bis (4-nonylbenzene). Base) rhenium hexafluorophosphate.

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, and 4,4'-bis [ Diphenylfluorenyl] diphenylsulfide bishexafluorophosphate, 4,4'-bis [bis (β-hydroxyethoxy) phenylfluorenyl] diphenylsulfide bishexafluoroantimonate, 4, 4'-bis [bis (β-hydroxyethoxy) phenylfluorenyl] diphenylsulfide dihexafluorophosphate, 7- [bis (p-tolyl) fluorenyl] -2-isopropylthio Anthrone hexafluoroantimonate, 7- [bis (p-tolyl) fluorenyl] -2-isopropylthiaxanthone tetra (pentafluorophenyl) borate, 4-phenylcarbonyl-4'- Diphenylfluorenyl-diphenylsulfide hexafluorophosphate, 4- (p-3rd-butylphenylcarbonyl) -4'-diphenylfluorenyl-diphenylsulfide hexafluoroantimonate, 4- (P-3rd-butylphenylcarbonyl) -4'-di (P-tolyl) fluorenyl-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like.

Examples of the iron-arene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene -Cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methane.

The photocationic polymerization initiator (C) may be used alone or in combination of two or more. Among the above, especially the aromatic sulfonium salts are suitable for use because they have ultraviolet absorbing properties in a wavelength region around 300 nm, so they have excellent hardenability, and can provide an adhesive layer having good mechanical strength and adhesive strength.

The content of the photocationic polymerization initiator (C) is 1 to 10 parts by weight, and preferably 2 to 6 parts by weight based on 100 parts by weight of the total measurement of the photocationic curable component (A) and the polymer (B). . When the photocationic polymerization initiator (C) is contained in an amount of 1 part by weight or more, the photocationic curable component (A) can be sufficiently cured, and high mechanical strength and adhesion strength can be imparted to the obtained polarizing plate. On the other hand, when the amount is increased, the ionic substance in the hardened substance increases, which increases the hygroscopicity of the hardened substance. Since the durability of the polarizing plate may decrease, the photocationic polymerization initiator (C The amount of) is 10 parts by weight or less based on 100 parts by weight of the total amount of the photocationically curable component (A) and the polymer (B).

(4) Photosensitizer

The photocurable adhesive may contain a photosensitizer. Although the photo-cationic polymerization initiator (C) exhibits maximum absorption in the vicinity of 300 nm or a shorter wavelength range, it induces light in the vicinity of the wavelength to generate a cationic substance or a Lewis acid. On the other hand, the cationic polymerization of the photocationically curable component (A) is started, but light of a longer wavelength is also sensed. Therefore, it is preferable that the photosensitizer exhibits maximum absorption at a wavelength longer than 380 nm. As the photosensitizer, an anthracene-based compound is suitably used.

Specific examples of the anthracene-based compound include, for example, 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-diisopropoxy Anthracene, 9,10-dibutoxyanthracene, 9,10-dipentoxyanthracene, 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-dibutoxy Anthracene, 2-methyl or 2-ethyl-9,10-dipentoxyanthracene, 2-methyl or 2-ethyl-9,10-dihexyloxyanthracene.

Since a photosensitizer is contained in a photocurable adhesive, the hardenability of an adhesive can be improved compared with the case where it does not contain it. Such an effect can be exhibited when the content of the photosensitizer is 0.1 parts by weight or more based on 100 parts by weight of the total amount of the photocationic curable component (A) and the polymer (B). On the other hand, when the content of the photosensitizer is increased, problems such as precipitation may occur during low-temperature storage. Therefore, its amount is preferably 100 parts by weight based on the total amount of the photocationically curable component (A) and the polymer (B). 2 parts by weight or less. From the viewpoint of maintaining the neutral gray of the polarizing plate, the content of the photosensitizer is more favorable when the effect of increasing the bonding strength between the polarizer and the protective film is sufficiently obtained. For example, the content of the photosensitizer is more favorable. (A) and polymer (B) 100 parts by weight are measured, and the amount of the photosensitizer is in the range of 0.1 to 0.5 parts by weight, preferably 0.1 to 0.3 parts by weight.

(5) Photosensitizer

The photocurable adhesive may contain a photosensitizer. The photosensitizer is preferably a naphthalene-based photosensitizer.

Specific examples of the naphthalene-based photosensitizer include 4-methoxy-1-naphthol, 4-ethoxy-1-naphthol, 4-propoxy-1-naphthol, and 4-butane Oxy-1-naphthol, 4-hexyloxy-1-naphthol, 1,4-dimethoxynaphthalene, 1-ethoxy-4-methoxynaphthalene, 1,4-diethoxy Naphthalene, 1,4-dipropoxynaphthalene, 1,4-dibutoxynaphthalene.

By including a naphthalene-based photosensitizing agent in the photocurable adhesive, the curability of the adhesive can be improved as compared with the case where the photocurable adhesive is not contained. Such an effect can be exhibited when the content of the naphthalene-based photosensitizing agent is 0.1 parts by weight or more based on 100 parts by weight of the total amount of the photocationic curable component (A) and the polymer (B). On the other hand, when the blending amount of the naphthalene-based photosensitizer is increased, due to problems such as precipitation during low-temperature storage, the amount is more than 100 parts by weight of the total amount of the photocationic curable component (A) and the polymer (B). It is preferably 5 parts by weight or less. The content of the naphthalene-based photosensitizer is preferably 3 parts by weight or less based on 100 parts by weight of the total amount of the photocationically curable component (A) and the polymer (B).

(6) Additive ingredients

As for the photocurable adhesive, as long as the effect of the present invention is not impaired, an additive component may be contained as another component as an optional component. Examples of the additive component include a thermal cationic polymerization initiator, a polyol, an ion trapping agent, Antioxidants, light stabilizers, chain transfer agents, adhesion-imparting agents, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, leveling agents, pigments, organic solvents, etc.

When the additive component is contained, its content is preferably 100 parts by weight, and preferably 1,000 parts by weight or less, based on the total amount of the photocationically curable component (A) and the polymer (B). When the content is 1,000 parts by weight or less, a combination of a photocationically curable component (A), a polymer (B), and a photocationic polymerization initiator (C) as essential components can make good use of a so-called polyvinyl alcohol system. The coexisting effects of excellent bonding strength between the polarizer and the protective film, reduction in viscosity of the photocurable adhesive, and good coating properties accompanied by this.

(7) Moisture content of photocuring adhesive

The photocurable adhesive may contain water. The content of water is usually 4 parts by weight or less, and more preferably 3 parts by weight or less based on 100 parts by weight of the total amount of the photocationic curable component (A) and the polymer (B). , Can improve the bonding strength between the polyvinyl alcohol polarizer and the protective film. However, when the moisture content is too large, the photocurable adhesive is separated from the moisture, and the photocurable adhesive may not be uniformly applied to the surface of the polarizer and the protective film, and the curability of the photocurable adhesive may be changed. Poor situation. The photocurable adhesive may also be purposefully added with water. In this case, it is not particularly limited, and purified water such as distilled water and pure water can be used. The moisture content of the photocurable adhesive is measured by the Karl Fischer volume method.

(8) Physical properties of photocuring adhesive

The photocurable adhesive system of the present invention may have low viscosity, specifically, In other words, the viscosity can be in the range of 2 to 300 mPa‧s at 25 ° C. Such a viscosity is a viscosity in a state where the solvent is not substantially contained. When the concentration is less than 2mPa‧s, the bonded polarizer may be peeled off from the protective film during transportation. When the viscosity exceeds 300mPa‧s, the polarizer and the protective film are bonded through the adhesive, especially the adhesive layer. When thin, the polarizer and the protective film, that is, the adhesive layer is prone to air bubbles. The above viscosity is more preferably 5 to 200 mPa‧s, and still more preferably 10 to 150 mPa‧s. When the viscosity is 150 mPa · s or less, even if the thickness of the adhesive layer is as thin as, for example, 2.8 μm or less, the generation of bubbles in the adhesive layer can be effectively suppressed. The viscosity of the photocurable adhesive was measured using an E-type viscometer.

<Polarizer>

The polarizing plate according to the present invention includes a polyvinyl alcohol-based polarizer and a protective film containing a thermoplastic resin bonded to at least one side of the polarizer through a cured product of the photocurable adhesive. Since this polarizing plate uses the photocurable adhesive according to the present invention, the bonding strength between the polarizer and the protective film is improved and the durability is excellent, and the inclusion of bubbles in the cured adhesive layer is suppressed.

(1) Polyvinyl alcohol polarizer

The polyvinyl alcohol-based polarizer is composed of a polyvinyl alcohol-based resin film having a dichroic pigment adsorbed and aligned. The polyvinyl alcohol-based resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include, in addition to polyvinyl acetate, a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. Wait. The saponification degree of the polyvinyl alcohol-based resin is usually in the range of 85 to 100 mol%, and preferably in the range of 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl alcohol formaldehyde and polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually in the range of 1,000 to 10,000, and preferably in the range of 1500 to 5,000.

The polarizer can be produced through the steps of uniaxially stretching the polyvinyl alcohol-based resin film, dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and adsorbing the dichroic dye. A step of treating a polyvinyl alcohol-based resin film of a dichroic dye with a boric acid aqueous solution.

Uniaxial stretching can be performed before dyeing with a dichroic pigment, or simultaneously with dyeing with a dichroic pigment, or after dyeing with a dichroic pigment. When uniaxial stretching is performed after dyeing with a dichroic pigment, the uniaxial stretching may be performed before the boric acid treatment, or may be performed during the boric acid treatment. It is also possible to perform uniaxial extension in these plural stages. There is no particular limitation on the method of uniaxial stretching. Uniaxial stretching can be performed between rollers with different speeds, and hot rolling can also be used for uniaxial stretching. In addition, it may be dry stretching in the atmosphere, or wet stretching in a swollen state by a solvent. The stretching ratio is usually 4 to 8 times.

The dichroic pigment can be adsorbed by immersing the polyvinyl alcohol-based resin film in a water-soluble solution containing the dichroic pigment. As the dichroic pigment system, iodine or a dichroic organic dye can be used.

When iodine is used as a dichroic dye, it is usually dyed by impregnating a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide. method. The content of iodine in the 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 generally 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 ° C, and the immersion time (dyeing time) of the aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic organic dye is used as a dichroic dye, a method of dyeing by dipping a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is generally used. 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. The aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80 ° C, and the immersion time (dyeing time) of the aqueous solution is generally about 30 to 300 seconds.

The boric acid treatment system after dyeing can be performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution of boric acid. The content of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by weight, and preferably about 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as a dichroic dye, it is preferable that the boric acid aqueous solution contains potassium iodide for this purpose. The content of potassium iodide in the boric acid aqueous solution is usually 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 1200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is generally 50 ° C or higher, and preferably 50 to 85 ° C.

Polyvinyl alcohol resin film after boric acid treatment, usually Wash with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. After washing with water, a drying process is performed to obtain a polarizer. The temperature of the water for water washing treatment is usually about 5 to 40 ° C, and the immersion time is usually about 2 to 120 seconds. The subsequent drying treatment can usually be performed using a hot-air dryer or a far-infrared heater. The drying temperature is usually 40 to 100 ° C. The time of the drying treatment is usually about 120 to 600 seconds. The thickness of the polyvinyl alcohol-based polarizer may be about 10 to 50 μm.

(2) Protective film

The protective film containing a thermoplastic resin may be either an unstretched film or a uniaxially or biaxially stretched film.

The thermoplastic resin constituting the protective film is preferably at least one selected from the group consisting of a cellulose resin, a (meth) acrylic resin, an amorphous polyolefin resin, a polyester resin, and a polycarbonate resin. 1 resin.

The polyester resin is not particularly limited, but in terms of mechanical properties, solvent resistance, scratch resistance, and cost, polyethylene terephthalate is preferred. The term "polyethylene terephthalate" means that 80 mol% or more of the repeating unit is a resin composed of ethylene terephthalate, and may also include a structural unit derived from other copolymerization components.

Examples of the other copolymerization component include a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component system include isophthalic acid, 4,4'-dicarboxybiphenyl, 4,4'-dicarboxydiphenyl ketone, bis (4-carboxyphenyl) ethane, and adipic acid. Acid, sebacic acid, sodium 5-sulfoisophthalate, and 1,4-dicarboxylic acid Carboxycyclohexane and the like. Examples of the diol component include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and Polybutylene glycol and the like. These dicarboxylic acid components and diol components can be used in combination of two or more kinds, respectively, as needed. In addition to the dicarboxylic acid component and the diol component, a hydroxycarboxylic acid such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid can be used in combination. As other copolymerization components, a dicarboxylic acid component and / or a diol component having a amine bond, a urethane bond, an ether bond, a carbonate bond, or the like can be used in a small amount.

After the polyethylene terephthalate resin is formed into a film, it can be used as a protective film by using a stretcher. In addition to being excellent in mechanical properties, solvent resistance, scratch resistance, cost, etc., it can be reduced in thickness. Polarizer.

Polycarbonate resins are polyesters made of carbonic acid and diols or bisphenols. Among them, an aromatic polycarbonate having diphenylalkane in its molecular chain is suitable for use because it is excellent in heat resistance, weather resistance, and acid resistance. Examples of such polycarbonates include, for example, 2,2-bis (4-hydroxyphenyl) propane (alias bisphenol A), 2,2-bis (4-hydroxyphenyl) butane, and 1,1- Poly (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) isobutane, or bisphenols derived from 1,1-bis (4-hydroxyphenyl) ethane Carbonate.

The acrylic resin is not particularly limited, and is generally a polymer of monomers mainly composed of methacrylate, and is preferably a copolymer copolymerized with a small amount of other comonomer components. This copolymer is usually obtained by polymerizing a monofunctional monomer composition containing methyl methacrylate and methyl acrylate in the coexistence of a radical polymerization initiator and a chain transfer agent. Again, (A A) acrylic resin can copolymerize a third monofunctional monomer.

Examples of the third monofunctional monomer include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-methacrylic acid 2- Methacrylates other than methyl methacrylate, such as ethylhexyl ester and 2-hydroxyethyl methacrylate; ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, acrylic acid 2-ethylhexyl and 2-hydroxyethyl acrylate and other acrylates; 2- (hydroxymethyl) acrylate, 2- (1-hydroxyethyl) acrylate, 2- (hydroxymethyl) acrylate Ethyl esters and hydroxyalkyl acrylates such as butyl 2- (hydroxymethyl) acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; vinyl toluene and α- Substituted styrenes such as methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and methyl maleic anhydride; phenylmaleimide and Unsaturated pyrimides such as cyclohexylmaleimide and the like. The third monofunctional monomer may be used singly or in combination.

The (meth) acrylic resin may also copolymerize a polyfunctional monomer. Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and bis (methyl) The two terminal hydroxyl groups of ethylene glycol or its oligomers, such as tetraethylene glycol acrylate, nonaethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate, are acrylic acid or methyl formaldehyde. Based on acrylic acid; propylene glycol or its oligomers are esterified with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate Esters and diols such as butanediol di (meth) acrylate with hydroxyl groups of acrylic acid or methacrylic acid; bisphenol A, alkylene oxide adducts of bisphenol A or halogen substituted products thereof The two terminal hydroxyl groups are esterified with acrylic acid or methacrylic acid; the polyhydric alcohols such as trimethylolpropane and neopentyl alcohol are esterified with acrylic acid or methacrylic acid; Epoxy or epoxy propylene methacrylate ring-opening adducts; succinic acid, adipic acid, terephthalic acid, phthalic acid, dibasic acids such as halogen substitutions, and the like Such as alkylene oxide adducts, etc., epoxy ring-opening addition of propylene acrylate or propylene methacrylate; (meth) acrylic acid aromatic esters; aromatic divinylbenzene and the like Vinyl compounds, etc. Among these, it is preferable to use ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate.

The (meth) acrylic resin can be modified by further reacting between functional groups of the copolymer. As this reaction, for example, the condensation reaction of the methyl group of methyl acrylate and the hydroxyl group of methyl 2- (hydroxymethyl) acrylate in a polymer chain is de-methanolized, and the carboxyl group of acrylic acid and methyl 2- (hydroxymethyl) acrylate are reacted. Dehydration condensation reaction of the hydroxyl polymer chain.

The glass transition temperature Tg of the (meth) acrylic resin is preferably in the range of 80 to 120 ° C. In order to adjust the glass transition temperature Tg of the (meth) acrylic resin to the above range, a polymerization ratio of a methacrylate monomer and an acrylate monomer, a carbon chain length of each ester group, or The type of functional group it has, the method of polymerization ratio of the polyfunctional monomer with respect to all the monomers, and the like.

(Meth) acrylic resin, which can contain custom Known additives. Examples of conventional additives include lubricants, anti-caking agents, heat stabilizers, antioxidants, antistatic agents, light stabilizers, impact resistance improvers, and surfactants. However, as the protective film laminated on the polarizer is necessary for transparency, the amount of these additives is preferably a minimum amount.

The (meth) acrylic resin may contain acrylic rubber particles as an impact modifier from the viewpoints of film forming properties and impact resistance of the film. The acrylic rubber particles referred to here are particles having an elastic polymer mainly composed of acrylate as an essential component. For example, a substantially single-layer structure including the elastic polymer or a single layer of the elastic polymer is used. Constructor. As an example of the above-mentioned elastic polymer, for example, a crosslinked elastic copolymer mainly composed of an alkyl acrylate and copolymerized with other vinyl monomers and crosslinkable monomers which can be copolymerized therewith. The alkyl acrylate as the main component of the elastic polymer includes, for example, those having an alkyl group having a carbon number of about 1 to 8 such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, particularly An acrylate having an alkyl group having 4 or more carbon atoms is used. Other vinyl monomers copolymerizable with this alkyl acrylate may be compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, such as methyl methacrylate, methacrylate, Aromatic vinyl compounds such as styrene, vinyl cyanide compounds such as acrylonitrile, and the like. The crosslinkable monomer may be, for example, a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di (meth) acrylate and butanediol (Meth) acrylates of polyols of di (meth) acrylate, such as (meth) acrylic alkenyl groups of allyl (meth) acrylate Esters, divinylbenzene, etc.

Further, a laminate of a film made of a (meth) acrylic resin containing no rubber particles and a film made of a (meth) acrylic resin containing rubber particles may be used as the protective film. The (meth) acrylic resin may be a commercially available product, for example, "SUMIPEX" (manufactured by Sumitomo Chemical Co., Ltd.), "ACRYPET" (manufactured by Mitsubishi Rayon Co., Ltd.), and "DELPET" under respective trade names. (Manufactured by Asahi Kasei Co., Ltd.), "PARAPET" (manufactured by Kuraray Co., Ltd.), "ACRYVIEWA" (manufactured by Japan Catalyst Co., Ltd.), etc.

Examples of the amorphous polyolefin-based resin include ring-opening of norbornene or a derivative thereof obtained by the reaction of cyclopentadiene and an olefin through a Diels-Alder reaction as a monomer, Shift polymerization, followed by hydrogenation of the resin; tetracyclododecene or its derivatives obtained from Dicyclopentadiene and olefins or methacrylates by Diels-Alder reaction as monomers And carry out ring-opening shift polymerization, followed by hydrogenation of the resin; using two or more selected from norbornene, tetracyclododecene and derivatives thereof, and other cyclic polyolefin monomers, similarly Resin obtained by ring-opening shift copolymerization, followed by hydrogenation; resin obtained by addition copolymerization of norbornene, tetracyclododecene, or the like with an aromatic compound having a vinyl group and the like. Examples of commercially available amorphous polyolefin-based resins include "ARTON" of JSR Corporation, "ZEONEX" and "ZEONOR" of ZEON Corporation of Japan, "APO" of Mitsui Chemicals Corporation, and "APEL" and so on.

At least one of the hydroxyl groups in the cellulose-based resin-based cellulose Part of the resin esterified by acetic acid may be a mixed ester of which a part is esterified by acetic acid and a part is esterified by other acid. The cellulose-based resin is preferably a cellulose ester-based resin, and more preferably an acetyl cellulose-based resin. Specific examples of the ethyl cellulose-based resin include triethyl cellulose, diethyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like. Examples of commercially available films of such ethyl acetate cellulose resins include "FUJITAC TD80", "FUJITAC TD80UF", "FUJITAC TD80UZ", and Konica Minolta manufactured by Fuji Membrane Corporation. "KC8UX2M" and "KC8UY" manufactured by Konica Minolta Opto Co., Ltd.

A cellulose-based resin film that provides an optical compensation function may also be used. Examples of the optical compensation film include a film containing a compound having a retardation adjusting function on a cellulose-based resin, a coating of a compound having a retardation adjusting function on the surface of the cellulose-based resin, and cellulose Films obtained by uniaxial or biaxial stretching of resins. Examples of commercially available cellulose-based resin optical compensation films include "WIDE VIEW FILM WV BZ 438" and "WIDE VIEW FILM WV EA" manufactured by Fuji Film Co., Ltd., Konica Minolta Precision Optics Co., Ltd. "KC4FR-1" and "KC4HR-1" made by the company.

The thickness of the protective film is usually in the range of about 5 to 200 μm, preferably 10 to 120 μm, and more preferably 10 to 85 μm. The protective film may have various surface treatment layers (coating layers) such as a hard coat layer, an anti-reflection layer, an anti-glare layer, and a light diffusion layer on the surface on the side opposite to the bonding surface of the polarizer of the protective film.

The protective film adhered to at least one surface of the polarizer may contain an ultraviolet absorber. Placing a protective film containing an ultraviolet absorber on the identification side of the liquid crystal cell can protect the liquid crystal cell from being deteriorated by ultraviolet rays. Examples of the ultraviolet absorber include a salicylate-based compound, a diphenyl ketone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, and a nickel salt-based compound.

(3) Manufacturing of polarizing plates

A polarizing plate is obtained by using a photocurable adhesive as described above, by attaching a protective film on at least one side of the polarizer. Specifically, the above-mentioned coating layer of the photocurable adhesive is formed on the bonding surface of the polarizer and / or the protective film, and the polarizer and the protective film are bonded together via the coating layer, and the uncured light is cured. The coating layer of the adhesive is hardened by irradiation with active energy rays, and the protective film is fixed on the polarizer. For the formation of the coating layer of the photocurable adhesive, various coating methods such as a doctor blade method, a wire rod method, a slit coating method, a notch wheel coating method, and a gravure coating method can be used. In addition, a method of continuously casting the adhesive in the middle while continuously supplying the inner surfaces of both the polarizer and the protective film may be adopted.

Depending on the coating method of the photocurable adhesive, the viscosity of the photocurable adhesive can be adjusted using a solvent. The type of the solvent is not particularly limited as long as it does not decrease the optical performance of the polarizer and can dissolve the photocurable adhesive well. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used. However, when a solvent is contained, it is preferable not to use a solvent as much as possible since it is necessary to provide a drying step to remove the solvent before the irradiation of active energy rays.

The thickness of the adhesive layer after curing can be arbitrarily set according to the characteristic design of the polarizing plate, but from the viewpoint of reducing the material cost of the adhesive, the smaller one is better. It is generally 0.01 to 20 μm, preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm. When the thickness of the adhesive layer is reduced, it is easy to cause bubbles in the adhesive layer to be mixed, and the adhesion and durability are reduced. However, if the photocurable adhesive of the present invention is used, these situations can be effectively suppressed.

When a protective film is attached only to one side of the polarizer, for example, a type in which an adhesive layer for directly adhering other optical components such as a liquid crystal cell can be provided on the other side of the polarizer. On the other hand, when a protective film is attached to both sides of the polarizer, the protective films may be made of the same resin or different resins. The protective film adhered to one side of the polarizer is adhered using the photocurable adhesive of the present invention, but the protective film adhered to the other side of the polarizer may be adhered using the photocurable adhesive of the present invention. Use another adhesive and follow.

Before the protective film is attached to the polarizer, a saponification treatment, a corona treatment, a plasma treatment, a primer coating treatment, an anchor coating treatment, a flame treatment, or the like can be easily adhered to the adhesive film and / or the adhesive surface of the polarizer.

The light source for irradiating the coating layer of the photocurable adhesive with active energy rays may be any one that can generate ultraviolet rays, electron beams, and X-rays. It is particularly suitable for those with a light emission distribution below 400nm, such as 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.

The intensity of irradiation of the active energy ray of the photocurable adhesive is not particularly limited, and it is preferable that the irradiation intensity in a wavelength range effective for activation of the photocationic polymerization initiator (C) is 0.1 to 3000 mW / cm ² . When it is less than 0.1 mW / cm ² , the reaction time becomes too long, and when it exceeds 3000 mW / cm ² , it receives light radiation from the lamp and heat generated during the polymerization of the photo-curable adhesive, resulting in photo-curable adhesive. The possibility of yellowing and deterioration of polarizers.

The light irradiation time of the photocurable adhesive is not particularly limited, but it is preferable to set the cumulative light amount represented by the product of the irradiation intensity and the irradiation time to 10 to 5,000 mJ / cm ² . When it is less than 10 mJ / cm ² , the generation of the active material from the photocationic polymerization initiator (C) is insufficient, and the hardening of the obtained adhesive layer may become insufficient. On the other hand, the accumulated light amount exceeds At 5,000 mJ / cm ² , the irradiation time becomes very long, which is a disadvantage for improving productivity.

When a protective film is attached to both sides of the polarizer, the irradiation of active energy rays can be performed from any protective film side, but it is preferable that, for example, the protective film on one side contains an ultraviolet absorber, and the protective film on the other side does not include an ultraviolet absorber At this time, irradiating active energy rays from the side of the protective film containing no ultraviolet absorber will effectively use the irradiated active energy rays and increase the curing speed.

The polarizing plate obtained by curing the photocurable adhesive is a peeling strength between the polarizer and the protective film measured by a 180-degree peeling test, preferably 0.5N / 25mm or more, and more preferably 1N / 25mm or more. When the peeling strength is less than 0.5N / 25mm, peeling may occur between the polarizer and the adhesive layer when the polarizing plate is cut.

An embodiment of the production of the polarizing plate will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing a preferred example of an apparatus for manufacturing a polarizing plate. On the protective films 2 and 3 that are continuously fed out from the state of being wound into a roll shape, photocurable adhesives are applied on one side by the adhesive application devices 11 and 12, respectively. Next, the protective films 2 and 3 are laminated on the both sides of the polarizer 1 continuously sent out in the same manner as the protective films 2 and 3 by the bonding rollers 5 a and 5 b with the adhesive therebetween, thereby producing a laminated body 4. The diameter of the bonding rollers 5a and 5b is, for example, 50 to 250 mm.

Next, the laminated body 4 is irradiated with an active energy ray, and a polarizing plate can be manufactured by hardening the coating layer of an adhesive agent. As shown in the example shown in FIG. 1, the produced multilayer body 4 is conveyed while being in close contact with the outer peripheral surface of the roller 13. The first active energy ray irradiation devices 14 and 15 are provided at positions opposite to the outer peripheral surface of the roller 13, and the second active energy ray irradiation devices 16 and 3 are sequentially arranged along the conveying direction on the downstream side in this conveying direction. An active energy ray irradiation device 17 and a fourth active energy ray irradiation device 18. According to this, in the process of conveying the coating layer-based laminated body 4 of the adhesive possessed by the laminated body 4 while closely contacting the outer peripheral surface of the roller 13, the laminated body 4 is activated by the active energy rays from the first active energy ray irradiation devices 14 and 15. The polymerization and hardening are further polymerized and hardened by the active energy rays of the second active energy ray irradiation device 16, the third active energy ray irradiation device 17, and the fourth active energy ray irradiation device 18 from the downstream side. The second and subsequent active energy ray irradiation devices 16, 17, and 18, which are arranged downstream of the conveying direction, are devices for completely polymerizing and curing the adhesive, and can be added and omitted as necessary. Finally, the cured laminated body 4 is wound around a winding roller 20 as a polarizing plate by a nip roller 19 for conveyance.

The outer peripheral surface of the roller 13 is composed of a mirror-polished convex curved surface, and is conveyed while closely adhering the laminated body 4 on this surface. In the process, the coating layer of the adhesive is polymerized and hardened by the active energy ray irradiation devices 14 and 15. . The diameter of the roll 13 is not particularly limited as long as the adhesive is polymerized and hardened, and the films constituting the laminated body 4 are sufficiently closely adhered. The roller 13 may be driven or moved in accordance with the linear operation of the laminated body 4 or may be fixed so that the laminated body 4 slides on the surface thereof. In addition, the roller 13 is a cooling roller that can be used to dissipate heat generated by the laminated body 4 during polymerization and hardening by irradiation with active energy rays. At this time, the surface temperature of the roller 13 acting as a cooling roller is preferably set to 4 to 30 ° C.

<Laminated optical member and liquid crystal display device>

The polarizing plate of the present invention is a laminated optical member that can be used as a laminated optical member having an optical layer laminated on an optical function other than the polarizing plate. Generally, it is a laminated optical member that is formed by laminating and attaching an optical layer on a protective film of a polarizing plate with an adhesive interposed therebetween. Alternatively, for example, a photocurable adhesive of the present invention may be interposed on one side of a polarizer Then, a protective film is laminated on the other surface of the polarizer through an adhesive and an adhesive to attach an optical layer. In the latter case, if the photocurable adhesive of the present invention is used as an adhesive for attaching a polarizer and an optical layer, the optical layer system can simultaneously serve as a protective film. It is also possible to laminate two or more optical layers on a polarizing plate.

Examples of the optical layer laminated on the polarizing plate include, for example, a reflective layer, a semi-transmissive reflective layer, and a light diffusion layer laminated on the opposite side of the liquid crystal cell in the polarizing plate with respect to the polarizing plate disposed on the opposite side of the liquid crystal cell. Layer, light collecting plate, brightness enhancement film, etc. For example, with respect to a liquid crystal cell A polarizing plate arranged on the front side and / or a polarizing plate arranged on the reverse side of the liquid crystal cell, a retardation plate laminated on the liquid crystal cell side in the polarizing plate, and the like.

The reflective layer, the transflective reflective layer, or the light diffusion layer are respectively provided as laminated optical members of a reflective polarizing plate, a transflective polarizing plate, or a diffusing polarizing plate. A reflective polarizing plate is a type of liquid crystal display device that reflects incident light from the recognition side and displays it. Since a light source such as a backlight can be omitted, it is easy to make the liquid crystal display device thin. The semi-transmissive polarizing plate is a type of liquid crystal display device used as a reflection type in a bright place and a display from a backlight in a dark place. A reflective polarizing plate can be produced by, for example, attaching a protective film on a polarizer to a foil containing a metal such as aluminum, or forming a reflective layer by vapor-depositing a film. A semi-transmissive polarizing plate can be produced by using the above-mentioned reflecting layer as a half mirror, or a reflecting plate containing a pearlescent pigment and the like, which exhibits light transmittance, and is then attached to the polarizing plate. On the other hand, the diffusion-type polarizing plate is a method of applying a mat treatment to a protective film of the polarizing plate, a method of coating a resin containing fine particles, a method of bonding a film containing fine particles, and the like, for example. Various methods are used to produce a fine uneven structure on the surface.

Furthermore, the laminated optical member may also be a polarizing plate for both reflection and diffusion. A polarizing plate for both reflection and diffusion can be produced by, for example, providing a reflective layer reflecting the uneven structure on the fine uneven structure surface of the diffused polarizing plate. The reflective layer with a fine uneven structure has the advantages of diffused reflection of incident light, preventing directivity and glare, and suppressing uneven brightness. In addition, the resin layer or film containing fine particles has a function of suppressing uneven light and dark in order to diffuse incident light and reflected light. advantage. The reflective layer reflecting the fine uneven structure on the surface can be formed by directly attaching a metal to the surface of the fine uneven structure by a method such as vacuum evaporation, ion plating, or sputtering, or plating. The fine particles blended to form a fine uneven structure on the surface may be, for example, an inorganic system such as silicon dioxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.1 to 30 μm. Fine particles; organic fine particles such as cross-linked or non-cross-linked polymers.

The light collecting plate is used by the user for the purpose of controlling the optical path and the like, and may be formed as a prism array sheet, a lens array sheet, or a dot-attached sheet.

The brightness-improving film is for the purpose of improving the brightness in a liquid crystal display device. The specific examples include: laminating a plurality of films having different refractive index anisotropies from each other, and designing such a method that the reflectivity is anisotropic. Reflective polarizing separation sheet; a circularly polarizing separation sheet supporting an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer thereof on a film substrate.

The retardation plate is used for the purpose of compensating the retardation of the liquid crystal cell and the like. This specific example includes a birefringent film including stretch films of various plastics, a discotic liquid crystal or a nematic liquid crystal as an alignment-fixed film, and forming the liquid crystal on a film substrate. Layers. When forming a liquid crystal layer on a film substrate, it is preferable to use a cellulose-based resin film such as cellulose triacetate as the film substrate.

Examples of the plastic forming the birefringent film include, for example, amorphous polyolefin resins, polycarbonate resins, and (meth) acrylic resins. Acrylic resins, chain polyolefin resins such as polypropylene, polyvinyl alcohol, polystyrene, polylate, polyamine, and the like. The stretch film can be treated in a suitable manner such as uniaxial or biaxial. The retardation plate is used for the purpose of controlling optical characteristics such as wideband, and a combination of two or more retardation films may be used.

Since it can effectively perform optical compensation when applied to a liquid crystal display device, it is preferable to use a layered optical member as an optical layer other than a polarizing plate as a laminated optical member. The retardation value (in-plane and thickness direction) of the retardation plate can be adjusted according to the applicable liquid crystal cell.

A laminated optical member is a laminated body in which two or more layers are formed by combining a polarizing plate and one or more layers selected from the above-mentioned various optical layers in accordance with the purpose of use. At this time, the various optical layers forming the laminated optical member are integrated with the polarizing plate using an adhesive and an adhesive (also referred to as a pressure-sensitive adhesive). The adhesive and the adhesive used for this purpose can be formed as long as they are well formed. The adhesive layer and the adhesive layer are not particularly limited. From the viewpoints of simplicity of the publishing industry and prevention of optical distortion, it is preferable to use an adhesive. As the adhesive, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, and the like can be used as the base polymer. Among them, it is preferable to use an optical transparency such as a (meth) acrylic adhesive, to maintain moderate wettability and cohesion, to have good adhesion to a substrate, and to have weather resistance and heat resistance. 2. Those who do not have problems such as warping and peeling under heating and humidifying conditions. Among the (meth) acrylic adhesives, (meth) acrylic acid having an alkyl group having a carbon number of 20 or less such as methyl, ethyl, and butyl is useful as a base polymer. Functional group-containing acrylic monomers such as alkyl esters, and (meth) acrylic acid or hydroxyethyl (meth) acrylate, such that the glass transition temperature is preferably 25 ° C or lower, more preferably 0 ° C or lower The (meth) acrylic copolymer having a weight average molecular weight of 100,000 or more is prepared.

The formation of the adhesive layer on the polarizing plate can be performed by, for example, dissolving or dispersing the adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a solution of 10 to 40% by weight, and It is a method of directly coating on a polarizing plate; or a method of forming an adhesive layer on a release film in advance and moving it to a polarizing plate. The thickness of the adhesive layer is determined according to its adhesive force and the like, but is more preferably in the range of about 1 to 50 μm.

The adhesive layer can be blended as required: fillers containing glass fibers or glass beads, resin beads, metal powders, or other inorganic powders, pigments or colorants, antioxidants, ultraviolet absorbers, and the like. Examples of the ultraviolet absorber include a salicylate-based compound, a diphenyl ketone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, and a nickel salt-based compound.

The liquid crystal display device according to the present invention includes a liquid crystal cell and the laminated optical member of the present invention which is arranged on at least one side of the liquid crystal cell, or may include a polarizing plate of the present invention instead of the laminated optical member. The polarizing plate or the laminated optical member can be laminated on one or both sides of the liquid crystal cell via an adhesive layer. The polarizing plate and the laminated optical member of the present invention may also be a polarizing plate with an adhesive layer and a laminated optical member, which are used for bonding the adhesive layer of the liquid crystal cell to the outer surface layer. Used LCD The cell system is arbitrary, and various types of liquid crystal cells such as an active matrix driving type represented by a thin film transistor type and a simple matrix driving type represented by a super twisted nematic type can be used to form a liquid crystal display. Device.

[Example]

Examples and comparative examples are shown below and the present invention will be described more specifically, but the present invention is not limited to these examples. In the following, the amounts and percentages of usage and content are indicated, and the basis of weight is the weight unless otherwise noted. The photocationically curable component (A), the polymer (B), and the photocationic polymerization initiator (C) used in the following examples are as follows.

[Photocation-curable component (A)]

1st photocationically hardenable component (A1): a1-I: bisphenol A type epoxy resin "ADEKA RESIN EP-4100L" manufactured by ADEKA Co., Ltd., a1-II: bisphenol A type manufactured by ADEKA Co., Ltd. Polyfunctional epoxy resin "ADEKA RESIN EP-5100R", a1-III: Aromatic polyfunctional epoxy resin "TECHMORE VG3101" manufactured by Printeq Co., Ltd., a1-IV: Phenol novolac manufactured by Nippon Kayaku Co., Ltd. Varnish-type epoxy resin "EPPN-201", a1-V: Special novolac-type epoxy resin "157S20" made by Mitsubishi Chemical Corporation, a1-VI: phenyl epoxy propyl ether.

The second photocationically curable component (A2): a2-I: neopentyl glycol diglycidyl ether [compound of Z = -CH ₂ C (CH ₃ ) ₂ CH ₂ -in the formula (III)], a2-II: 1,4-butanediol diglycidyl ether [compound of Z = -CH ₂ CH ₂ CH ₂ CH ₂ -in the above formula (III)], a2-III: 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, a2-IV: 2-ethylhexyl epoxypropyl ether, a2-V: 4 -Hydroxybutyl vinyl ether, a2-VI: triethylene glycol divinyl ether.

Third photocationically curable component (A3): a3-I: Alicyclic epoxy resin "CELLOXIDE 2021P" manufactured by DAICEI Co., Ltd., and a3-II: Limonene dioxide.

[Polymer (B)]

bI: a polymer having a weight average molecular weight of 8000 (GMA-MMA) obtained by radically polymerizing a monomer composition containing 25 parts of propylene methacrylate (GMA) and 75 parts of methyl methacrylate (MMA) Copolymer), b-II: polymer (GMA monomer) containing a weight average molecular weight of 8000 obtained by free radical polymerization of propylene methacrylate, b-III: propylene methacrylate A polymer (GMA-MMA copolymer) having a weight average molecular weight of 60,000 obtained by radical polymerization of 25 parts of an ester and 75 parts of a methyl methacrylate monomer composition, including b-IV: Weight average score obtained by free radical polymerization of 50 parts of ester and 50 parts of methyl methacrylate Polymer (GMA-MMA copolymer) with a molecular weight of 200,000.

[Photocationic polymerization initiator (C)]

Diphenyl (phenylthio) phenylphosphonium hexafluorophosphate.

[Photosensitizer, Photosensitizer]

d-I: 1,4-diethoxynaphthalene, d-II: 9,10-dibutoxyanthracene.

<Examples 1 to 27, Comparative Examples 1 to 9>

(1) Preparation of photocuring adhesive

The components shown in Table 1 were mixed, and then defoamed to prepare photocurable adhesives (liquid) of Examples 1 to 27 and Comparative Examples 1 to 9. The unit of the amount of each component in Table 1 is "part". In addition, the photocationic polymerization initiator (C) is actually formulated with a 50% propylene carbonate solution, but Table 1 shows the blended amount based on its solid content.

(2) Viscosity measurement of photocuring adhesive at 25 ° C

For each of the photocurable adhesives (adhesive solutions) prepared above, an E-type viscometer "TVE-25L" manufactured by Toki Sangyo Co., Ltd. was used to measure the viscosity at a temperature of 25 ° C. The results are shown in Table 2.

(3) Moisture measurement of photocurable adhesive at 25 ° C

For each of the photocurable adhesives (adhesive solutions) prepared as described above, the moisture content at a temperature of 25 ° C. was measured using a moisture meter “AQV-2100ST” manufactured by Hiranuma Sangyo Co., Ltd. The results are shown in Table 2.

(4) Production of polarizing plate

A protective film composed of a (meth) acrylic resin (PMMA) [trade name "TEKUNOROI S001", manufactured by Sumitomo Chemical Co., Ltd.] and a norbornene-based resin with a thickness of 80 µm containing an ultraviolet absorber and a norbornene-based resin A 50 μm retardation film [trade name “ZEONOR”, manufactured by Japan Zeon Co., Ltd.] was corona-treated on one side, and the corona-treated surface was coated with an adhesive coating device using the adhesive coating device described above in (1). Each prepared adhesive is applied separately. At this time, the linear speed of the film in the adhesive coating device was set to 25 m / min, and the gravure roll was rotated in a direction opposite to the film conveyance direction. The thickness of the adhesive layer was 2.8 μm after curing.

Next, on one side of the polyvinyl alcohol-iodine-based polarizer having a thickness of 25 μm, a phase difference formed by the (meth) acrylic resin and a norbornene-based resin was formed on the other side. Film, these are bonded together via an adhesive layer. At the time of bonding, a pair of nip rollers [bonding roller (chrome-plated metal roller / rubber roller)] with a diameter of 250 mm was used, and the pressing was set to 1.5 MPa.

The obtained laminated body was transported at a linear velocity of 25 m / min while applying a tension of 600 N / m in the longitudinal direction, and the total accumulated light amount (cumulative amount of light irradiation intensity in a wavelength range of 280 to 320 nm) was about 200 mJ / cm ² (measurement value: measurement value of UV Power Puck II manufactured by FusionUV Co., Ltd.) was irradiated with ultraviolet rays (UVB) to harden the adhesive layer to obtain a polarizing plate.

(5) Confirmation of bubbles in the adhesive layer

The obtained polarizing plate was cut with a length of 300 mm × 200 mm in width, and the surface was observed with a microscope (measuring device: Digital microscope VHX-500 manufactured by KEYENCE) at a magnification of 100 times to confirm the hardening. The presence or absence of air bubbles of 50 μm or more in the subsequent adhesive layer.

<Evaluation criteria>

A: No bubbles are recognized,

B: Bubbles confirmed

(6) 180-degree peel test of polarizing plate

After cutting the polarizing plate prepared in the above (4) to a length of 200 mm × width of 25 mm, an acrylic adhesive layer was provided on the side of the protective film made of (meth) acrylic resin as the protective film for measurement. Test piece for peel strength with polarizer. In addition, an acrylic adhesive layer was provided on the retardation film side as a test piece for measuring the peeling strength between the retardation film and the polarizer.

Each test piece is adhered to a glass plate with its adhesive layer, and a polarizer and a protective film (adhesive film made of (meth) acrylic resin or pinene-based retardation film) on the side of the adhesive layer are placed between the cutters. Blade, from length side 30 mm was peeled to the end part, and this peeled part was clamped by the clamp part of a testing machine. The test piece in this state was placed in an environment at a temperature of 23 ° C. and a relative humidity of 55%. According to JIS K 6854-2: 1999 “Adhesives-Peeling Adhesive Strength Test Method-Part 2: 180 Degree Peeling”, the speed of the jig was determined. A 180-degree peel test was performed at 300 mm / minute, and an average peel force of 170 mm in length other than 30 mm of the jig portion was obtained. The measurement was performed 24 hours after the polarizing plate was produced. The results are shown in Table 2. The "PMMA / PVA peel strength" in Table 2 indicates the peel strength between the protective film made of the (meth) acrylic resin and the polarizer, and the "COP / PVA peel strength" indicates the reduction The peeling strength between the olefin-based retardation film and the polarizer. In addition, the "substrate failure" in Table 2 means that the peeling strength is large and at least one of the polarizer and the protective film (or retardation film) is broken in the peeling test.

(7) Determination of Tg and tensile elastic modulus of hardened adhesive layer

Each of the photocurable adhesives prepared in the above (1) was coated on an untreated PET ("Soft Shine" manufactured by Toyobo Co., Ltd.) film with a bar coater # 20, and then a belt conveyor was used. An ultraviolet irradiation device (a light bulb is a "D bulb" manufactured by Fusion UV Systems) and irradiates ultraviolet rays so that a cumulative amount of light becomes 3000 mJ / cm ² (UVB). After 24 hours, the cured adhesive layer was taken out of the film, and a glass transition temperature Tg and a tensile elastic modulus (80 ° C) were measured using a viscoelasticity measuring device "DMA7100" manufactured by Hitachi Hightech Science. The results are shown in Table 2. The adhesive of Comparative Example 9 was not cured under the above conditions.

[Table 2]

Claims (16)

A photo-curable adhesive, which is a photo-curable adhesive used on a polyvinyl alcohol-based polarizer, followed by a protective film containing a thermoplastic resin, and contains: a photo-cationic curable component (A), which is contained as an aromatic The first photocationic curable component (A1) of the group epoxy compound; polymer (B), which is derived from a monomer (I) selected from the following formula (I) and the following formula (II) Constituent units of more than one monomer in the group of monomers shown

(In the formula, X represents a hydrogen atom, or a C1-C7 alkyl group which may be substituted with one or more functional groups selected from the group consisting of epoxy group, oxetanyl group, hydroxyl group and carboxyl group, Alkoxy groups having 1 to 7 carbon atoms, aryl groups having 6 to 12 carbon atoms, aryloxy groups having 6 to 12 carbon atoms or alicyclic hydrocarbon groups having 6 to 10 carbon atoms),

(In the formula, R ¹ represents a hydrogen atom, a methyl group or a halogen atom; Y represents a carbon that may be substituted with one or more functional groups selected from the group consisting of epoxy, oxetanyl, hydroxyl and carboxy Alkyl groups with 1 to 7 carbon atoms, aryl groups with 6 to 12 carbon atoms or alicyclic hydrocarbon groups with 6 to 10 carbon atoms); and photocationic polymerization initiator (C); wherein, the content of the aforementioned polymer (B) In the total weight of 100 parts by weight of the photo-cation hardening component (A) and the polymer (B), 2 to 10 parts by weight, the content of the first photo-cation hardening component (A1), in the light 10 to 40 parts by weight of 100 parts by weight of the total weight of the cationic hardening component (A) and the polymer (B), the content of the photocationic polymerization initiator (C) relative to the photocationic hardening component The total weight of (A) and the aforementioned polymer (B) is 100 parts by weight, which is 1 to 10 parts by weight. The photo-curable adhesive according to item 1 of the patent application scope, wherein the photo-cation-curable component (A) includes a compound selected from the group consisting of aliphatic diglycidyl compounds, monofunctional aliphatic epoxy compounds, and vinyl groups. One or more second photocation hardening components (A2) in the group consisting of an ether compound and an oxetane compound. The photocurable adhesive as described in item 2 of the patent application, wherein the aliphatic diglycidyl compound is a compound represented by the following formula (III):

(In the formula, Z represents a linear or branched alkylene group having 1 to 9 carbon atoms, or a divalent alicyclic hydrocarbon group. The methylene group in the alkylene group may be selected from an oxygen atom, -CO- (O-, -O-CO-, -SO _2- , -SO- or -CO- is substituted with a divalent group). The photocurable adhesive as described in item 3 of the patent application, wherein Z in the aforementioned formula (III) is a branched alkylene group having 3 to 10 carbon atoms. The photo-curable adhesive according to item 2 of the patent application scope, wherein the content of the second photo-cation-curable component (A2) is between the photo-cation-curable component (A) and the polymer (B) Of the total weight of 100 parts by weight, 58 to 88 parts by weight. The photocurable adhesive as described in item 1 of the patent application range, wherein the weight average molecular weight of the aforementioned polymer (B) is 5,000 to 500,000. The photocurable adhesive as described in item 6 of the patent application range, wherein the weight average molecular weight of the aforementioned polymer (B) is 6,000 to 100,000. The photocurable adhesive as described in item 1 of the patent application range, wherein the water content is 4 parts by weight relative to 100 parts by weight of the total weight of the photocationically curable component (A) and the polymer (B) the following. The photo-curable adhesive according to any one of the items 1 to 8 of the patent application, wherein the viscosity at 25 ° C is 2 to 300 mPa‧s. A polarizing plate comprising: a polyvinyl alcohol-based polarizer, and a photocurable adhesive described in any one of claims 1 to 9 on at least one surface of the polyvinyl alcohol-based polarizer A protective film that contains the thermoplastic resin and adheres to the cured product. The polarizing plate according to item 10 of the patent application range, wherein the thermoplastic resin is selected from the group consisting of cellulose resin, (meth) acrylic resin, amorphous polyolefin resin, polyester resin and polycarbonate One or more resins in the group of resins. The polarizing plate as described in item 10 of the patent application range, wherein the protective film contains an ultraviolet absorber. The polarizing plate according to item 10 of the patent application range, wherein the peel strength between the polyvinyl alcohol-based polarizer and the protective film measured by a 180-degree peel test is 0.5 N / 25 mm or more. A laminated optical member comprising a polarizing plate according to any one of claims 10 to 13 and one or more other optical layers. The laminated optical member as described in item 14 of the patent application range, wherein the other optical layer includes a retardation plate. A liquid crystal display device includes a liquid crystal cell and a laminated optical member according to item 14 of the patent application range disposed on at least one surface of the liquid crystal cell.