JP5449815B2 - Manufacturing method of polarizing plate - Google Patents

Description

  The present invention relates to a method for manufacturing a polarizing plate, a polarizing plate obtained by the manufacturing method, and a liquid crystal display device using the polarizing plate.

  Optical films such as polarizing films, protective films, and retardation films are used in image display devices such as liquid crystal display devices, organic EL display devices, and plasma display panels (PDP). The optical film is required to have various optical properties, mechanical strength, transparency, heat resistance, moisture resistance, and the like depending on the application. In particular, in recent years, development of optical films suitable for increasing the size of liquid crystal displays, development of optical films suitable for increasing the size of thin displays used for mobile devices, development of thin optical films used for mobile devices, etc. have been demanded. .

  As for the optical film, a kind of film may be used alone, but it is often used by being combined with another optical film to be combined. Bonding with another optical film for this composite is generally performed using an adhesive (see Patent Documents 1 and 2). For example, a polarizing plate, which is an optical member such as a liquid crystal display device, is usually manufactured by bonding a protective film to one or both sides of a polarizing film using an adhesive. However, depending on the type of optical film or the type of adhesive, sufficient adhesion strength cannot be obtained by bonding using an adhesive, and problems such as peeling may occur.

JP 2005-352403 A JP 2008-287207 A

  This invention is made | formed in order to solve the said conventional subject, and is providing the manufacturing method of the polarizing plate excellent in the adhesiveness of a polarizing film and a protective film.

In the present invention, a protective film made of a thermoplastic resin is bonded to a polarizing film made of a uniaxially stretched polyvinyl alcohol resin film in which iodine or a dichroic dye is adsorbed and oriented using an ultraviolet curable adhesive, and a polarizing plate The ultraviolet curable adhesive is a cationic polymerization type epoxy resin adhesive, and includes a step of heating the protective film, and an ultraviolet curable adhesive is applied to one side of the heated protective film. Provided is a method for producing a polarizing plate comprising a step of applying and forming an adhesive layer, a step of bonding a polarizing film on the adhesive layer to obtain a laminated film, and a step of irradiating the laminated film with ultraviolet rays. To do.

In one preferred embodiment, the step of forming the adhesive layer comprises as engineering for heating the ultraviolet curing adhesive prior to coating.

In the manufacturing method of the polarizing plate of this invention, it is preferable that the said epoxy resin does not contain an aromatic ring in a molecule | numerator .

Moreover , in the manufacturing method of the polarizing plate of this invention, it is preferable that the said ultraviolet curing adhesive contains a photocationic polymerization initiator in addition to the said epoxy resin .

  The thermoplastic resin constituting the protective film is preferably an acrylic resin. Moreover, it is preferable that the heating temperature in the said process to heat is 30-80 degreeC.

  Moreover, according to this invention, a liquid crystal display device provided with the polarizing plate obtained by the manufacturing method of the said invention and the said polarizing plate is provided.

  According to this invention, the polarizing plate which is excellent in the adhesiveness of a polarizing film and a protective film can be provided. Moreover, an image display apparatus provided with this polarizing plate and an image display element can also be provided. The polarizing plate of the present invention can be suitably used for a liquid crystal display device.

<Method of manufacturing a polarizing plate>
The manufacturing method of the polarizing plate of this invention is equipped with the following process, It is characterized by the above-mentioned.
(A) A process of forming an adhesive layer by applying an ultraviolet curable adhesive on one side of the protective film or polarizing film (adhesive layer forming process),
(B) A step of obtaining a laminated film by laminating a protective film and a polarizing film via an adhesive layer (film lamination step),
(C) a step of irradiating the laminated film with ultraviolet rays (ultraviolet irradiation step), and
(D) A step of heating at least one of the protective film and the ultraviolet curable adhesive (heating step).

  The heating step (d) is performed at any stage prior to the ultraviolet irradiation step (c). The following steps will be described in detail.

(A) Adhesive layer forming step This step is a step of forming an adhesive layer by applying an ultraviolet curable adhesive to one surface of a protective film or a polarizing film. First, the polarizing film, protective film, and ultraviolet curable adhesive used in this step will be described in detail.

(Polarizing film)
Specifically, the polarizing film used in the present invention is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film. As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film, a saponified polyvinyl acetate resin can be used. Polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith, such as ethylene-vinyl acetate copolymers. Etc. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like can be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1000 to 10000, preferably about 1500 to 5000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known appropriate method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 10-150 micrometers.

  A polarizing film is usually a process of dyeing an original film made of polyvinyl alcohol resin as described above with a dichroic dye and adsorbing the dichroic dye (dyeing process), and the dichroic dye is adsorbed. The polyvinyl alcohol-based resin film is produced through a step of treating with a boric acid aqueous solution (boric acid treatment step) and a step of washing with water after the treatment with the boric acid aqueous solution (water washing treatment step).

  Further, in the production of the polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched, but this uniaxial stretching may be performed before the dyeing treatment step or during the dyeing treatment step, It may be performed after the dyeing process. When uniaxial stretching is performed after the dyeing treatment step, this uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in these plural stages. Uniaxial stretching may be performed uniaxially between rolls having different peripheral speeds, or may be performed uniaxially using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 3 to 8 times.

  The dyeing of the polyvinyl alcohol-based resin film with the dichroic dye in the dyeing treatment step is performed, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine, a dichroic dye or the like is used. Examples of dichroic dyes include C.I. I. Dichroic direct dyes composed of disazo compounds such as DIRECT RED 39, and dichroic direct dyes composed of trisazo, tetrakisazo compounds and the like are included. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. . When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution, usually, 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water, preferably 1 × 10 ^-3 to 1 parts by weight, particularly preferably 1 × 10 ^{- 3} to 1 × 10 ⁻² parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is usually 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 10 to 1800 seconds. is there.

  The boric acid treatment step is performed by immersing a polyvinyl alcohol-based resin film dyed with a dichroic dye in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye in the dyeing process described above, the boric acid-containing aqueous solution used in this boric acid treatment process preferably contains potassium iodide. In this case, the amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  In the subsequent washing process, the polyvinyl alcohol-based resin film after the boric acid treatment described above is washed with water, for example, by immersing it in water. The water temperature in the water washing treatment is usually 5 to 40 ° C., and the immersion time is usually 1 to 120 seconds. After the water washing treatment, a drying treatment is usually performed to obtain a polarizing film. The drying process can be performed using, for example, a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually 30 to 100 ° C, preferably 50 to 80 ° C. The time for the drying treatment is usually 60 to 600 seconds, preferably 120 to 600 seconds.

  Thus, a polarizing film is obtained by subjecting the polyvinyl alcohol-based resin film to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment and water washing treatment. The thickness of this polarizing film is usually in the range of 5 to 40 μm. In the manufacturing method of this invention, the roll-shaped polarizing film formed by winding the elongate polarizing film obtained as mentioned above is used, for example.

(Protective film)
The protective film used in the present invention is a film for physically and chemically protecting the polarizing film, and is made of a thermoplastic resin. Examples of the thermoplastic resin constituting the protective film include olefin resins such as polyethylene, polypropylene, and polyvinyl chloride; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; cycloolefin resins such as norbornene resins Resin; Polyurethane resin; Acrylic resin such as polyacrylate and polymethyl methacrylate; Transparent polymer material such as cellulose resin such as diacetyl cellulose and triacetyl cellulose (TAC). Especially, since the adhesive improvement effect of the polarizing film and protective film by this invention is acquired effectively, the thermoplastic resin which comprises a protective film is polyolefin resin, such as polyethylene, a polypropylene, a polyvinyl chloride; polyethylene Polyester resins such as terephthalate and polyethylene naphthalate; polycarbonate resins; cycloolefin resins such as norbornene resins; acrylic resins and the like are preferably used, and acrylic resins are particularly preferably used. In addition, the thermoplastic resin which comprises a protective film can contain additives, such as a ultraviolet absorber, antioxidant, and a plasticizer, as needed. A protective film can be obtained by forming the thermoplastic resin into a film by a known method such as a casting method or an extrusion method.

  As the acrylic resin, a methyl methacrylate resin can be suitably used. The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

  The methyl methacrylate resin may be a copolymer of methyl methacrylate and a monomer copolymerizable therewith. Examples of monomers that can be copolymerized with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, and the like. Methacrylic acid esters other than methyl methacrylate; acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate Esters; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituents such as alkylstyrenes such as vinyltoluene and α-methylstyrene Ren like; acrylonitrile, methacrylonitrile, maleic anhydride, phenyl maleimide, and cyclohexyl maleimide. These monomers may be used alone or in combination of two or more.

  A rubber-like polymer may be added to the methyl methacrylate resin. The addition of the rubbery polymer makes it difficult to break during film formation, and the yield can be improved. Moreover, since it becomes difficult to break also at the time of bonding with a polarizing film, there exists an advantage which handling becomes easy. When the rubber-like polymer is contained, the amount of the rubber-like polymer added is preferably 100 parts by weight or less, more preferably 3 to 50 parts by weight with respect to 100 parts by weight of the methyl methacrylate resin. is there. When the addition amount of the rubber-like polymer exceeds 100 parts by weight with respect to 100 parts by weight of the methyl methacrylate resin, the rigidity of the protective film tends to decrease.

  Examples of the rubber-like polymer include an acrylic multilayer structure polymer and a graft copolymer obtained by graft-polymerizing an ethylenically unsaturated monomer to a rubber component. The acrylic multilayer structure polymer is a multilayer structure having a rubber elastic layer or an elastomer layer and a hard layer as the outermost layer. The rubber elastic layer or the elastomer layer can be, for example, 20 to 60% by weight of the whole. The acrylic multilayer structure polymer may have a structure further including a hard layer as the innermost layer.

  The rubber elastic layer or the elastomer layer is a layer made of an acrylic polymer having a glass transition point (Tg) of less than 25 ° C. Acrylic polymers forming a rubber elastic layer or an elastomer layer are: lower alkyl acrylate; lower alkyl methacrylate; lower alkoxy acrylate; cyanoethyl acrylate; acrylamide; hydroxy lower alkyl acrylate, hydroxy lower alkyl methacrylate, acrylic acid, methacrylic acid, etc. At least one monoethylenically unsaturated monomer of allyl methacrylate, allyl acrylate, ethylene glycol dimethacrylate, butanediol dimethacrylate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene, maleic acid Cross-linking polymerization obtained by polymerizing with polyfunctional monomers such as diallyl, trimethylolpropane triacrylate and allylcinnamate It is.

  The hard layer is a layer made of an acrylic polymer having a Tg of 25 ° C. or higher. As the acrylic polymer forming the hard layer, a homopolymer of an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, and the alkyl methacrylate as a main component, other alkyl methacrylate, alkyl acrylate, styrene, Examples thereof include a copolymer copolymerized with a copolymerizable monofunctional monomer such as substituted styrene, acrylonitrile, and methacrylonitrile. The acrylic polymer forming the hard layer may be a crosslinked polymer obtained by adding a polyfunctional monomer to the monomer and polymerizing it. Examples of such an acrylic polymer include those described in JP-B-55-27576, JP-A-6-80739, and JP-A-49-23292.

  A graft copolymer obtained by graft-polymerizing an ethylenically unsaturated monomer to a rubber component contains 5 to 80% by weight of a monomer unit derived from the rubber component (therefore, 95% of ethylenically unsaturated monomer units are contained). It is preferable to contain ~ 20% by weight. Examples of rubber components include diene rubbers such as polybutadiene rubber, acrylonitrile / butadiene copolymer rubber, and styrene / butadiene copolymer rubber; acrylic rubbers such as polybutyl acrylate, polypropyl acrylate, and poly-2-ethylhexyl acrylate; and Ethylene / propylene / non-conjugated diene rubber can be used. As the rubber component, two or more components may be used. Examples of the ethylenically unsaturated monomer include styrene, acrylonitrile, and alkyl (meth) acrylate, and among them, acrylic unsaturated monomers such as acrylonitrile and alkyl (meth) acrylate are preferably used. As such a graft copolymer, those described in JP-A Nos. 55-147514 and 47-9740 can be used.

  The cycloolefin resin is a thermoplastic resin having a monomer unit composed of cycloolefin such as norbornene and polycyclic norbornene monomers. The cycloolefin resin may be a hydrogenated product of a ring-opening polymer using a single cycloolefin or a hydrogenated product of a ring-opening copolymer using two or more kinds of cycloolefins. It may be an addition copolymer with an aromatic compound having a chain olefin and / or a vinyl group. Further, those having a polar group introduced into the main chain or side chain are also effective.

  Commercially available thermoplastic cycloolefin-based resins include “Topas” sold by Ticona, Germany, “Arton” sold by JSR Corporation, and “Zeonor” sold by Nippon Zeon Corporation. ZEONOR ”and“ ZEONEX ”,“ APEL ”(both trade names) sold by Mitsui Chemicals, Inc., and the like, which can be suitably used. Also, for example, “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd., “Zeonor Film” sold by Optes Co., Ltd., “Arton Film” sold by JSR Co., Ltd. Cycloolefin-based resin films (such as trade names) are also commercially available, and these can also be suitably used as protective films.

  The cellulose-based resin means a partially esterified product or a completely esterified product of cellulose, and examples thereof include cellulose acetate ester, propionate ester, butyrate ester, and mixed ester thereof. More specifically, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate and the like can be mentioned. Cellulosic resin films can be obtained commercially, for example, “Fujitac TD80” (Fuji Film Co., Ltd.), “Fujitac TD80UF” (Fuji Film Co., Ltd.), “Fujitac TD80UZ” (Fuji Film ( Co., Ltd.), “KC8UX2M” (manufactured by Konica Minolta Opto), “KC8UY” (manufactured by Konica Minolta Opto), and the like.

  The thickness of the protective film is not particularly limited, but is preferably about 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 100 μm or less from the viewpoint of reducing the thickness and weight of the polarizing plate. In the production method of the present invention, for example, a roll-shaped protective film formed by winding a long protective film is used.

(UV curable adhesive)
The adhesive used to form the adhesive layer on one side of the protective film or polarizing film is an ultraviolet curable adhesive. By using the ultraviolet curable adhesive, the protective film and the polarizing film can be bonded with high adhesive strength.

  UV curable adhesives include radical polymerization adhesives and cationic polymerization adhesives when classified according to the type of curing. Acrylic resin adhesives and epoxy resins are classified according to the chemical species of the adhesive component. System adhesives and the like. In the present invention, any of these may be used, and a mixture of two or more of these may be used. From the viewpoints of ease of handling, adhesive strength obtained, and the like, a cationic polymerization type epoxy resin A system adhesive is preferably used. The epoxy resin refers to a compound or polymer that has an average of two or more epoxy groups in the molecule and is cured by a polymerization reaction involving the epoxy group. Called.

  As the epoxy resin contained in the ultraviolet curable adhesive, an epoxy resin that does not contain an aromatic ring in the molecule is suitably used from the viewpoints of weather resistance, refractive index, and cationic polymerizability. Examples of the epoxy resin that does not contain an aromatic ring in the molecule include a hydrogenated epoxy resin, an alicyclic epoxy resin, and an aliphatic epoxy resin.

  The hydrogenated epoxy resin can be obtained by subjecting an aromatic epoxy resin to a nuclear hydrogenation reaction selectively under pressure in the presence of a catalyst. Examples of the aromatic epoxy resin include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin and hydroxybenzaldehyde phenol Examples thereof include novolak-type epoxy resins such as novolak epoxy resins; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone and epoxidized polyvinylphenol. Among them, it is preferable to use hydrogenated bisphenol A glycidyl ether as the hydrogenated epoxy resin.

The alicyclic epoxy resin means an epoxy resin having one or more epoxy groups bonded to the alicyclic ring in the molecule. The “epoxy group bonded to an alicyclic ring” is a group in a form in which one or a plurality of hydrogen atoms are removed from (CH ₂ ) _m in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.

Accordingly, a compound in which a group in the form of removing one or more hydrogen atoms in (CH ₂ ) _m in the above formula is bonded to another chemical structure can be an alicyclic epoxy resin. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (m = 3 in the above formula) or an oxabicycloheptane ring (m = 4 in the above formula) is a polarizing film and a protective film. It is preferably used because an adhesive having excellent adhesive strength is obtained. Although the alicyclic epoxy resin preferably used in the present invention is specifically exemplified below, it is not limited to these compounds.

  (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(B) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).
(C) Epoxycyclohexylmethyl esters of dicarboxylic acid represented by the following formula (III):

(In the formula, R ⁵ and R ⁶ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).
(D) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (IV):

(In the formula, R ⁷ and R ⁸ independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).
(E) Epoxycyclohexyl methyl ethers of alkanediols represented by the following formula (V):

(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 2 to 20).
(F) Diepoxy trispiro compound represented by the following formula (VI):

(In the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(G) Diepoxy monospiro compound represented by the following formula (VII):

(In the formula, R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(H) Vinylcyclohexene diepoxides represented by the following formula (VIII):

(In the formula, R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(I) Epoxycyclopentyl ethers represented by the following formula (IX):

(In the formula, R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(J) Diepoxytricyclodecanes represented by the following formula (X):

(In the formula, R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
Among the alicyclic epoxy resins exemplified above, the following alicyclic epoxy resins are commercially available or similar, and are more preferably used because they are relatively easy to obtain. .

(A) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [formula (I) In which R ¹ = R ² = H]
(B) 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept-3-yl) methanol Ester compounds of [In the formula (I), R ¹ = 4-CH ₃ , R ² = 4-CH ₃ compound],
(C) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [in the formula (II), R ³ = R ⁴ = H, n = 2 Compound〕,
(D) (7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [compound of formula (III), wherein R ⁵ = R ⁶ = H, p = 4] ,
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the formula (III), R ⁵ = 4-CH ₃ , R ⁶ = 4-CH ₃ , p = 4 compound]
(F) etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the formula (V), R ⁹ = R ¹⁰ = H, r = Two compounds].

  Examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene Diglycidyl ether of glycol; and polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide, propylene oxide, etc.) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol or glycerin And polyglycidyl ether.

  In this invention, an epoxy resin may be used individually by 1 type, or may use 2 or more types together.

  The epoxy equivalent of the epoxy resin used by this invention is 30-3,000 g / equivalent normally, Preferably it exists in the range of 50-1,500 g / equivalent. When the epoxy equivalent is less than 30 g / equivalent, the flexibility of the adhesive layer after curing may be reduced or the adhesive strength may be reduced. On the other hand, if it exceeds 3,000 g / equivalent, the compatibility with other components contained in the adhesive may be lowered.

  In the present invention, as described above, cationic polymerization is preferably used as the curing reaction of the epoxy resin. For this purpose, the ultraviolet curable adhesive preferably contains a cationic photopolymerization initiator. The cationic photopolymerization initiator generates a cationic species or a Lewis acid when irradiated with ultraviolet rays, and initiates an epoxy group polymerization reaction. Any type of cationic polymerization initiator may be used, but it is preferable from the viewpoint of workability that the potential is imparted.

  The method of curing the adhesive by irradiating with ultraviolet light using a cationic photopolymerization initiator enables curing at room temperature, reducing the need to consider the heat resistance of the polarizing film or distortion due to expansion, and a protective film. It is advantageous in that it can be bonded well to the polarizing film. In addition, since the photocationic polymerization initiator acts catalytically by light, the adhesive is excellent in storage stability and workability even when mixed with an epoxy resin.

  Although it does not specifically limit as a photocationic polymerization initiator, For example, onium salts, such as an aromatic diazonium salt, an aromatic iodonium salt, an aromatic sulfonium salt, and an iron- allene complex etc. can be mentioned.

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

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di (4-nonylphenyl) iodonium hexafluorophosphate.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis (diphenylsulfonio) diphenylsulfide bis ( Hexafluorophosphate), 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis (hexafluoroantimonate), 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio ] Diphenyl sulfide bis (hexafluorophosphate), 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4 Examples include '-diphenylsulfonio-diphenylsulfide hexafluoroantimonate and 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate. .

  Examples of iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and xylene-cyclopentadienyl iron (II)- And tris (trifluoromethylsulfonyl) methanide.

  Commercially available products of these cationic photopolymerization initiators can be easily obtained. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd. )), “UVI-6990” (manufactured by Union Carbide), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA, Inc.), “CI-5102”, “ "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (Nippon Soda Co., Ltd.), "DPI-101", "DPI-102" , “DPI-103”, “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI” 103 "," BBI-105 "," TPS-101 "," TPS-102 "," TPS-103 "," TPS-105 "," MDS-103 "," MDS-105 "," DTS-102 " , “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like. Among these, “CI-5102” manufactured by Nippon Soda Co., Ltd. is one of preferred photocationic polymerization initiators.

  The above cationic photopolymerization initiators may be used alone or in combination of two or more. Among these, in particular, the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength. Preferably used.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of epoxy resins, Preferably it is 1 weight part or more, Preferably it is 15 weight part or less. When the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the epoxy resin, curing becomes insufficient, and mechanical strength or adhesive strength tends to be lowered. Moreover, when the compounding quantity of a photocationic polymerization initiator exceeds 20 weight part with respect to 100 weight part of epoxy resins, the ionic substance in hardened | cured material will increase, and the hygroscopic property of hardened | cured material will become high, and polarization | polarized-light. The durability of the board may be reduced.

  When using a photocationic polymerization initiator, the ultraviolet curable adhesive may further contain a photosensitizer as necessary. By using a photosensitizer, the reactivity of cationic polymerization is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreducible dyes. More specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate Benzophenone derivatives such as 4,4′-bis (dimethylamino) benzophenone and 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2-chloroanthraquinone, 2-methyl Anthraquinone derivatives such as anthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; and α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl Including compounds and halogen compounds. However, it is not limited to these. These photosensitizers may be used alone or in combination of two or more. The photosensitizer is preferably contained within a range of 0.1 to 20 parts by weight in 100 parts by weight of the ultraviolet curable adhesive.

  The ultraviolet curable adhesive may further contain a compound that promotes cationic polymerization, such as oxetanes and polyols.

  Oxetanes are compounds having a 4-membered ring ether in the molecule. Examples of oxetanes include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [ (3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolac oxetane. Commercial products of these oxetanes can be easily obtained. For example, “Aron oxetane OXT-101”, “Aron oxetane OXT-121”, and “Aron oxetane OXT-211” are trade names. , “Aron Oxetane OXT-221”, “Aron Oxetane OXT-212” (manufactured by Toagosei Co., Ltd.), and the like. Oxetanes are usually contained in the ultraviolet curable adhesive in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight.

  The polyols are preferably those having no acidic groups other than phenolic hydroxyl groups. Examples of such polyols include a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol compound having a phenolic hydroxyl group, and a polycarbonate polyol. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and preferably 1,000 or less. The polyols are usually contained in the ultraviolet curable adhesive in a proportion of 50% by weight or less, preferably 30% by weight or less.

  Further, the ultraviolet curable adhesive is not limited to the effects of the present invention, and other additives such as ion trapping agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, filling Agents, flow modifiers, plasticizers, antifoaming agents, and the like. Examples of the ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based inorganic compounds, and mixtures thereof. Examples of the antioxidant include hindered phenol antioxidants.

  The ultraviolet curable adhesive is an adhesive used for bonding the protective film and the polarizing film. The surface on which the UV curable adhesive is applied and the adhesive layer is formed may be a bonding surface with the polarizing film in the protective film, or may be a bonding surface with the protective film in the polarizing film, Both may be sufficient. Preferably, an adhesive layer is formed on the bonding surface of the protective film with the polarizing film. There are no particular limitations on the method of applying the adhesive, and various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Since each coating method has an optimum viscosity range, it is also a useful technique to adjust the year of the adhesive using a solvent. As the solvent, a solvent that dissolves the adhesive well without degrading the optical performance of the polarizing film is preferably used. Specific examples of the solvent are not particularly limited, and examples thereof include hydrocarbons such as toluene; organic solvents such as esters such as ethyl acetate.

  The protective film may be bonded only to one side of the polarizing film, or may be bonded to both sides of the polarizing film. In the case where protective films are laminated on both sides of the polarizing film, the two adhesive layers are preferably the same ultraviolet curable adhesive.

  Moreover, when a protective film is laminated | stacked only on the single side | surface of a polarizing film, you may laminate | stack an optical compensation film on the surface on the opposite side to the surface where the protective film in a polarizing film is bonded. The adhesive for laminating the polarizing film and the optical compensation film is an adhesive different from an ultraviolet curable adhesive such as an aqueous adhesive containing a polyvinyl alcohol resin or a urethane resin as an adhesive component. Alternatively, an ultraviolet curable adhesive may be used. When the same adhesive as the ultraviolet curable adhesive used for bonding the polarizing film and the protective film is used, the production efficiency can be improved and the number of raw material types can be reduced.

  Optical compensation films include cellulose resins such as triacetyl cellulose (TAC); olefin resins such as polyethylene, polypropylene and polyvinyl chloride; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; cycloolefins such as norbornene resins An optical compensation film made of an acrylic resin such as polyacrylate or polymethyl methacrylate.

  As an optical compensation film comprising a cellulose resin film, for example, a film in which a compound having a retardation adjusting function is contained in the cellulose resin film; a film in which a compound having a retardation adjusting function is applied to the surface of a cellulose resin film. A film obtained by uniaxially or biaxially stretching a cellulose resin film, and the like. Examples of the optical compensation film made of a commercially available cellulose resin film include “WV film Wide View Film“ WV BZ 438 ””, “WV film Wide View Film“ WV EA ””, Konica Minolta manufactured by Fuji Film Co., Ltd. Examples thereof include “KC4FR-1” and “KC4HR-1” manufactured by Opto Corporation.

  The thickness of the optical compensation film made of a cellulose resin film is not particularly limited, but is preferably in the range of 20 to 90 μm, and more preferably in the range of 30 to 90 μm. When the thickness is less than 20 μm, it is difficult to handle the film. On the other hand, when the thickness exceeds 90 μm, the workability is inferior, and it is disadvantageous in reducing the thickness and weight of the resulting polarizing plate.

  Examples of the optical compensation film made of the cycloolefin-based resin include a uniaxially stretched or biaxially stretched cycloolefin-based resin film. When the polarizing plate obtained by the present invention is used for a liquid crystal panel for a large-sized liquid crystal television, particularly a liquid crystal panel having a vertical alignment (VA) mode liquid crystal cell, a stretched product of a cycloolefin resin film is used as the optical compensation film. However, it is also preferable from the viewpoint of optical characteristics and durability.

  If the thickness of the optical compensation film made of a stretched cycloolefin-based resin is too thick, it becomes inferior in workability, and the transparency is lowered, or it is disadvantageous in reducing the thickness and weight of the polarizing plate, etc. It is preferably about 20 to 80 μm.

  Prior to the formation of the adhesive layer, the protective film, the optical compensation film, or the polarizing film adhesive layer forming surface may be subjected to easy adhesion treatment such as corona treatment, primer treatment, and anchor coating treatment.

(B) Film lamination process This process is a process of obtaining a laminated film by bonding a protective film and a polarizing film through an adhesive layer. The laminated film may have a protective film laminated on one side or both sides of the polarizing film. Alternatively, the laminated film may have a protective film laminated on one surface of the polarizing film and an optical compensation film laminated on the other surface of the polarizing film.

(C) Ultraviolet irradiation step This step is a step of irradiating the laminated film with ultraviolet rays. The adhesive layer made of an ultraviolet curable adhesive is cured by irradiation with ultraviolet rays. The ultraviolet light source is not particularly limited, and has a light emission distribution at a wavelength of 400 nm or less. Can be used.

The light irradiation intensity to the adhesive layer composed of the ultraviolet curable adhesive is determined for each composition of the ultraviolet curable adhesive, and is not particularly limited, but in the wavelength region effective for activating the polymerization initiator. The irradiation intensity is preferably 0.1 to 100 mW / cm ² . When the light irradiation intensity is less than 0.1 mW / cm ² , the reaction time becomes too long. When the light irradiation intensity exceeds 100 mW / cm ² , adhesion occurs due to heat radiated from the lamp and heat generated during polymerization of the ultraviolet curable adhesive. It may cause yellowing of the agent and deterioration of the polarizing film. The light irradiation time to the adhesive layer composed of the ultraviolet curable adhesive is controlled for each composition of the ultraviolet curable adhesive and is not particularly limited, but is expressed as a product of the irradiation intensity and the irradiation time. It is preferable that the integrated light quantity to be set is 10 to 5000 mJ / cm ² . If the cumulative amount of light to the ultraviolet curable adhesive is less than 10 mJ / cm ² , the generation of active species derived from the polymerization initiator is not sufficient, and the adhesive layer may be insufficiently cured. If it exceeds cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity.

  Curing of the adhesive layer by ultraviolet irradiation is preferably performed under conditions that do not deteriorate the various functions of the polarizing plate such as the degree of polarization of the polarizing film, the transmittance and the hue, and the transparency of the protective film and the optical compensation film. The thickness of the adhesive layer after curing is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less.

(D) Heating step This step is a step of heating at least one of the protective film or the ultraviolet curable adhesive. This heating step (d) is performed at any stage prior to the ultraviolet irradiation step (c). By providing this heating step, it is possible to obtain a polarizing plate that is excellent in adhesion between the polarizing film and the protective film, in particular, in which the adhesion between the protective film and the adhesive layer is greatly improved.

As a specific aspect of the heating step (d), any of the following steps can be preferably employed.
(D-1) a step of heating a protective film made of a thermoplastic resin,
(D-2) a step of heating the ultraviolet curable adhesive, and
(D-3) The process of heating the laminated body by which the protective film, the adhesive bond layer which consists of an ultraviolet curable adhesive, and the polarizing film were laminated | stacked in this order.

  When employing the above step (d-1), the production method of the present invention preferably includes a step (d-1) of heating a protective film made of a thermoplastic resin and an ultraviolet ray on one side of the heated protective film. A step of forming an adhesive layer by applying a curable adhesive [adhesive layer forming step (a)], and a step of laminating a polarizing film on the adhesive layer to obtain a laminated film [film lamination step ( b)] and a step of irradiating the laminated film with ultraviolet rays [ultraviolet irradiation step (c)] in this order.

  The method for heating the protective film is not particularly limited. For example, a long protective film drawn from a roll-shaped protective film is sequentially passed through a device that emits radiant heat, such as an infrared heater, and the long protective film. And a method of blowing heated gas using a blower or the like. The timing for heating the protective film is not particularly limited as long as it is before the adhesive layer is formed on one side of the protective film. For example, it may be before easy adhesion treatment such as corona treatment or after. May be.

  In the case of employing the above step (d-2), the production method of the present invention is preferably a step (d-2) for heating the ultraviolet curable adhesive and heating on one side of a protective film made of a thermoplastic resin. A step of forming an adhesive layer by applying the UV curable adhesive [adhesive layer forming step (a)], and a step of laminating a polarizing film on the adhesive layer to obtain a laminated film [film A lamination step (b)] and a step of irradiating the laminated film with ultraviolet rays [ultraviolet irradiation step (c)].

  The method of heating the ultraviolet curable adhesive is not particularly limited, and examples thereof include a method of heating and keeping the adhesive in a storage tank in advance and supplying the heated adhesive to the coating apparatus. it can. In this case, the heated adhesive is coated on the protective film while the heated state is maintained, and a heated adhesive layer is formed on the protective film.

  When employing the above step (d-3), the production method of the present invention is preferably a protective film made of a thermoplastic resin, or a uniaxially stretched polyvinyl alcohol resin film in which iodine or a dichroic dye is adsorbed and oriented. A step of forming an adhesive layer by applying an ultraviolet curable adhesive on one surface of the polarizing film [adhesive layer forming step (a)], and a protective film and a polarizing film through the adhesive layer The step of obtaining a laminated film by pasting [film lamination step (b)], the step of heating the laminated film (d-3), and the step of irradiating the heated laminated film with ultraviolet rays [ultraviolet irradiation step (C)] in this order.

  The method of heating the laminated film is not particularly limited. For example, the obtained laminated film is sequentially passed through a device that emits radiant heat such as an infrared heater, and the laminated film is sprayed with a gas heated using a blower or the like. The method etc. can be mentioned.

  In the case of adopting any of the steps (d-1) to (d-3), the temperature for heating the protective film, the ultraviolet curable adhesive or the laminated film is preferably 30 to 80 ° C., 40 More preferably, it is -60 degreeC. If the heating temperature exceeds 80 ° C., the protective film, the ultraviolet curable adhesive or the polarizing film may be deteriorated by heat. Further, if the heating temperature is less than 30 ° C., the effect of improving the adhesion between the protective film and the polarizing film is not sufficient.

  In the production method of the present invention, an adhesive layer made of an ultraviolet curable adhesive is laminated on a protective film in any of the above steps (d-1) to (d-3), It is particularly preferable that at least one of the protective film or the adhesive layer includes a state where it is heated within the above temperature range. Thereby, the polarizing plate which is excellent in the adhesiveness of a protective film and a polarizing film, especially the adhesiveness of a protective film and an adhesive bond layer can be obtained. The time for which this state is maintained is preferably 0.2 seconds or more and 1 hour or less, and more preferably 1 second or more and 10 minutes or less. If it is less than 0.2 seconds, the effect of improving the adhesion between the protective film and the polarizing film, particularly the adhesion between the protective film and the adhesive layer, is not sufficient. Moreover, when it exceeds 1 hour, there exists a possibility that a protective film, an ultraviolet curable adhesive, or a polarizing film may deteriorate with a heat | fever.

  More specifically, in the case of adopting the step (d-1), the protective film is heated in the above temperature range, and an adhesive layer is formed on one surface of the protective film in a state where this temperature range is maintained. To do. In this case, preferably, the state in which the protective film heated in the above temperature range and the adhesive layer are in contact with each other until the ultraviolet irradiation step (c) is secured for a period of 0.2 seconds to 1 hour. In the case of adopting the step (d-2), the ultraviolet curable adhesive is heated in the above temperature range, and a heated adhesive layer is formed on one side of the protective film in a state where this temperature range is maintained. . In this case, preferably, the state in which the protective film and the adhesive layer heated in the above temperature range are in contact with each other until the ultraviolet irradiation step (c) is secured for a period of 0.2 seconds to 1 hour. Moreover, when employ | adopting a process (d-3), Preferably, by the time of 0.2 second or more and 1 hour or less, the said temperature range is obtained for the laminated | multilayer film until an ultraviolet irradiation process (c). Heat with.

  The manufacturing method of the polarizing plate of this invention may include two or more of the said process (d-1)-(d-3).

  The polarizing plate of the present invention is a polarizing plate obtained by the production method of the present invention, and includes a protective film on one side or both sides of the polarizing film. In the case where a protective film is provided on one side of the polarizing film, the pressure-sensitive adhesive used for bonding with a liquid crystal cell or the like on the surface of the polarizing film opposite to the surface on which the protective film is laminated. A layer (or adhesive layer) may be formed. Further, a protective film or an optical compensation film may be laminated on the surface of the polarizing film opposite to the surface on which the protective film is laminated, and an adhesive layer (or adhesive layer) may be formed thereon. Furthermore, an optical functional film is laminated on the polarizing film or a protective film or an optical compensation film laminated on the polarizing film, and an adhesive layer (or adhesive layer) is formed on the optical functional film. You can also.

  As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer, a conventionally known appropriate pressure-sensitive adhesive can be used without particular limitation, and examples thereof include an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer is provided by a method in which such a pressure-sensitive adhesive is, for example, an organic solvent solution, which is applied to a base film (for example, a protective film, a polarizing film, etc.) with a die coater or a gravure coater and dried. Can do. Moreover, it can provide also by the method of transcribe | transferring the sheet-like adhesive formed on the plastic film (it is called a separate film) to which the mold release process was given to a base film. Although there is no restriction | limiting in particular also about the thickness of an adhesive layer, Generally it is preferable to exist in the range of 2-40 micrometers.

  The optical functional film can be laminated on a polarizing film or a protective film or an optical compensation film laminated on the polarizing film via an adhesive layer. As an optical functional film, for example, an optical compensation film in which a liquid crystal compound is coated on a substrate surface and oriented; a reflection type that transmits a certain kind of polarized light and reflects polarized light that shows the opposite property Polarizing film; Retardation film made of polycarbonate-based resin; Retardation film made of cycloolefin-based resin; Film with anti-glare function having a concavo-convex shape on the surface; Film with surface anti-reflection function; Reflective film having reflection function on the surface; And a transflective film having both a reflection function and a transmission function. Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the surface of the base material are “WV film” (Fuji Film Co., Ltd.), “NH film” (Shin Nippon Oil Co., Ltd.) And “NR Film” (manufactured by Nippon Oil Corporation). For example, “DBEF” (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan) is a commercially available product corresponding to a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties. Can be obtained), “APF” (manufactured by 3M, available from Sumitomo 3M Limited in Japan), and the like. Moreover, as a commercial item corresponding to the retardation film which consists of cycloolefin type resin, for example, "Arton film" (made by JSR Corporation), "Essina" (made by Sekisui Chemical Co., Ltd.), "Zeonor film" ( (Manufactured by Optes Co., Ltd.).

<Liquid crystal display device>
The liquid crystal display device of the present invention includes a liquid crystal panel. The liquid crystal panel includes a liquid crystal cell and the polarizing plate of the present invention laminated on one or both sides of the liquid crystal cell, and the liquid crystal cell and the polarizing plate are bonded via an adhesive layer. When the liquid crystal panel includes the polarizing plate of the present invention only on one side of the liquid crystal cell, the polarizing plate provided on the other side of the liquid crystal cell is not particularly limited, and a conventionally known appropriate polarizing plate is used. be able to. In the liquid crystal panel provided in the liquid crystal display device of the present invention, the polarizing plate provided on the front side of the liquid crystal cell (the viewing side in the liquid crystal display device and opposite to the backlight) is, for example, antiglare treatment, hard coat The polarizing plate etc. which the process and the antireflection process were performed may be sufficient.

  In the liquid crystal display device of the present invention, as the configuration other than the liquid crystal panel, an appropriate configuration of a conventionally known liquid crystal display device can be adopted, and for example, a backlight, a light diffusion plate, and a liquid crystal panel are provided in this order. A configuration and a configuration including a backlight, a light diffusion plate, a light diffusion sheet, and a liquid crystal panel in this order can be given.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

(Production Example 1: Production of protective film)
(A) Production of acrylic multilayer polymer An acrylic multilayer polymer having a three-layer structure was produced according to the method described in the examples of JP-B-55-27576. 3. A glass reaction vessel having an internal volume of 5 L was charged with 1700 g of ion exchange water, 0.7 g of sodium carbonate, and 0.3 g of sodium persulfate, stirred under a nitrogen stream, and then Perex OT-P (manufactured by Kao Corporation). 46 g, ion-exchanged water 150 g, methyl methacrylate 150 g and allyl methacrylate 0.3 g were charged. Then, the temperature was raised to 75 ° C. and stirring was continued for 150 minutes.

  Subsequently, a mixture of 689 g of butyl acrylate, 162 g of styrene and 17 g of allyl methacrylate, and a mixture of 0.85 g of sodium persulfate, 7.4 g of Perex OT-P and 50 g of ion-exchanged water were added from another inlet over 90 minutes. The polymerization was continued for another 90 minutes. After the completion of the polymerization, a mixture of 326 g of methyl acrylate and 14 g of ethyl acrylate and 30 g of ion-exchanged water in which 0.34 g of sodium persulfate was dissolved were added from separate ports over 30 minutes. After completion of the addition, the polymerization was completed by holding for another 60 minutes. The obtained latex was put into a 0.5% aluminum chloride aqueous solution to aggregate the polymer. This was washed 5 times with warm water and then dried to obtain an acrylic multilayer polymer.

(B) Production of protective film 20 parts by weight of the acrylic multilayer polymer with respect to 80 parts by weight of a copolymer of methyl methacrylate / methyl acrylate = 96/4 (weight ratio) (refractive index 1.49) The contained acrylic composition was mixed with a Henschel mixer and then melt-kneaded with an extruder. Extrusion was performed at an extrusion resin temperature of 260 ° C., and a protective film having a thickness of 80 μm was produced through a roll unit so that the extruded resin was pressure-bonded to an elastic roll set at 80 ° C.

The structure of the used extrusion apparatus is as follows.
Extruder: Screw diameter 65 mm, single screw, with vent (manufactured by Toshiba Machine Co., Ltd.).
Die: T-die, lip width 1400 mm, lip interval 1 mm (manufactured by Hitachi Zosen Corporation).
Roll: Three elastic polishing rolls, horizontal type.

(Production Example 2: Production of Polarizing Film)
After immersing a 75 μm-thick polyvinyl alcohol film made of polyvinyl alcohol having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more in pure water at 30 ° C., the weight ratio of iodine / potassium iodide / water is 0. It was immersed in an aqueous solution of 02/2/100 at 30 ° C. Then, it was immersed at 56.5 ° C. in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100. Subsequently, the film was washed with pure water at 8 ° C. and then dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on a polyvinyl alcohol film. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

(Production Example 3: Preparation of UV-curable adhesive)
Trade name “Epicoat YX8000” (diglycidyl ether of nuclear hydrogenated bisphenol A, having an epoxy equivalent of about 205 g / equivalent) 10.0 g, Japan, which is a hydrogenated epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. Dispense 100 ml of the product name “CI5102” 4.0 g, which is a photocationic polymerization initiator manufactured by Soda Co., Ltd., and 1.0 g of the product name “CS7001”, which is a photosensitizer made by Nippon Soda Co., Ltd. An adhesive made of a curable resin composition containing an epoxy resin was prepared by weighing into a cup, mixing and defoaming.

<Example 1>
The protective film obtained in Production Example 1 was placed in an infrared heater set at 60 ° C. for 5 seconds and heated. Subsequently, the ultraviolet curable adhesive obtained in Production Example 3 was applied to one side of the heated protective film to form an adhesive layer. In parallel with this, the ultraviolet curable adhesive obtained in Production Example 3 was applied to one side of a norbornene-based resin film ("ZEONOR film" manufactured by Optes Co., Ltd.) to form an adhesive layer.

  Next, the protective film having the adhesive layer and the norbornene-based resin film are bonded to both surfaces of the polarizing film obtained in Production Example 2 under the environment of 23 ° C. via the adhesive layer, and the protective film. A laminated film composed of / adhesive layer / polarizing film / adhesive layer / norbornene resin film was formed, and ultraviolet rays were irradiated from the norbornene resin film surface to obtain a polarizing plate. The time during which the adhesive layer is laminated on the heated protective film and the temperature of the protective film is maintained in the range of 40 to 60 ° C. is approximately 1 second until the laminated film is irradiated with ultraviolet rays. there were.

< Reference Example 1 >
One side of the protective film obtained in Production Example 1 was coated with the ultraviolet curable adhesive obtained in Production Example 3 that had been heated and kept at 60 ° C. in a storage tank in advance, thereby forming a heated adhesive layer. . In parallel with this, the ultraviolet curable adhesive obtained in Production Example 3 was applied to one side of a norbornene-based resin film ("ZEONOR film" manufactured by Optes Co., Ltd.) to form an adhesive layer.

  Next, the protective film having the adhesive layer and the norbornene-based resin film are bonded to both surfaces of the polarizing film obtained in Production Example 2 under the environment of 23 ° C. via the adhesive layer, and the protective film. A laminated film composed of / adhesive layer / polarizing film / adhesive layer / norbornene resin film was formed, and ultraviolet rays were irradiated from the norbornene resin film surface to obtain a polarizing plate. The time during which the heated adhesive layer is laminated on the protective film and the temperature of the adhesive layer is maintained in the range of 40 to 60 ° C. until the laminated film is irradiated with ultraviolet rays is about 5 seconds. Met.

<Example 2 >
Example 1 except that the UV curable adhesive obtained in Production Example 3 that was heated and kept at 60 ° C. in advance in a storage tank was applied to one side of the protective film heated in the same manner as Example 1. A polarizing plate was obtained in the same manner. The heated adhesive layer is laminated on the heated protective film and the temperature of the protective film and the adhesive layer is maintained in the range of 40 to 60 ° C. until the laminated film is irradiated with ultraviolet rays. The time was approximately 10 seconds.

< Reference Example 2 >
The ultraviolet curable adhesive obtained in Production Example 3 was applied to one side of the protective film obtained in Production Example 1 to form an adhesive layer. In parallel with this, the ultraviolet curable adhesive obtained in Production Example 3 was applied to one side of a norbornene-based resin film ("ZEONOR film" manufactured by Optes Co., Ltd.) to form an adhesive layer. .

  Next, the protective film having the adhesive layer and the norbornene-based resin film are bonded to both surfaces of the polarizing film obtained in Production Example 2 under the environment of 23 ° C. via the adhesive layer, and the protective film. A laminated film composed of / adhesive layer / polarizing film / adhesive layer / norbornene resin film was formed, and the laminated film was subsequently placed in an infrared heater set at 60 ° C. for 60 seconds and heated. Subsequently, ultraviolet rays were irradiated from the norbornene-based resin film surface to obtain a polarizing plate.

<Comparative Example 1>
A polarizing plate was obtained in the same manner as in Example 1 except that the protective film was not heated.

About the obtained polarizing plate, the blade edge | tip of the cutter was inserted between the polarizing film and the protective film, and the adhesiveness between a polarizing film and a protective film was evaluated. In the polarizing plates of Examples 1 and 2 and Reference Examples 1 and 2 , when the cutting edge of the cutter was inserted, no peeling occurred between the polarizing film and the protective film, and the polarizing film and the protective film were broken and polarized. The adhesion between the film and the protective film was very good. On the other hand, in the polarizing plate of Comparative Example 1, peeling was confirmed between the polarizing film and the protective film.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (6)

A method for producing a polarizing plate by bonding a protective film made of a thermoplastic resin to a polarizing film made of a uniaxially stretched polyvinyl alcohol-based resin film on which iodine or a dichroic dye is adsorbed and oriented using an ultraviolet curable adhesive Because
The ultraviolet curable adhesive is a cationic polymerization type epoxy resin adhesive ,
The method
Heating the protective film;
Applying the ultraviolet curable adhesive to one surface of the heated protective film to form an adhesive layer;
A step of laminating the polarizing film on the adhesive layer to obtain a laminated film;
Irradiating the laminated film with ultraviolet rays;
The manufacturing method of the polarizing plate containing this.   The method for producing a polarizing plate according to claim 1, wherein the step of forming the adhesive layer includes a step of heating the ultraviolet curable adhesive before coating.   The said epoxy resin is a manufacturing method of the polarizing plate of Claim 1 or 2 which does not contain an aromatic ring in a molecule | numerator.   The said ultraviolet curable adhesive agent is a manufacturing method of the polarizing plate in any one of Claims 1-3 containing a photocationic polymerization initiator in addition to the said epoxy resin.   The method for producing a polarizing plate according to claim 1, wherein the thermoplastic resin is an acrylic resin.   The manufacturing method of the polarizing plate according to any one of claims 1 to 5, wherein a heating temperature in the heating step is 30 to 80 ° C.