JP6027839B2 - Manufacturing method of polarizing plate - Google Patents

Description

  The present invention relates to a method for producing a polarizing plate useful as one of optical components constituting a liquid crystal display device or the like.

  Polarizing films are widely used as dichroic dyes adsorbed and oriented on polyvinyl alcohol resin films. Iodine polarizing films using iodine as a dichroic dye and dichroic direct dyes as dichroic Dye-type polarizing films used as pigments are known. These polarizing films are usually used as polarizing plates by laminating a transparent film such as a triacetyl cellulose film on one side or both sides via an adhesive.

  As a method of laminating a transparent film on one or both sides of a polarizing film, after applying an active energy ray-curable resin to the surface of the transparent film in advance, the polarizing film and the transparent film are sandwiched between a pair of nip rolls (bonding rolls). There is a method of bonding and curing by irradiation with active energy rays (Patent Document 1: Japanese Patent Laid-Open No. 2004-245925, Patent Document 2: Japanese Patent Laid-Open No. 2009-134190, Patent Document 3: Special). (Open 2011-95560).

  In Patent Document 3, when the active energy ray-curable resin is cured by irradiating active energy rays, it is possible to suppress the occurrence of wave curl or the like by curing the laminate while adhering it to the outer peripheral surface of the roll. Although it is described, when the balance of the rotation speed of the laminating roll and the roll for adhering the laminate upon irradiation with the active energy ray is inappropriate, the appearance defect such as a wavy plate formed on the produced polarizing plate (below) This state is referred to as “corrugated undulation”).

JP 2004-245925 A JP 2009-134190 A JP 2011-95560 A

  An object of this invention is to aim at suppression of generation | occurrence | production of a corrugated sheet form in the method provided with the process of hardening active energy ray hardening-type resin, making the above laminated bodies contact | adhere to the outer peripheral surface of a roll.

  The present invention is a method for producing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film, and the active energy ray-curable adhesive is attached to one side or both sides of the transparent film. And sandwiching a laminate in which the transparent film is laminated on one or both sides of the polarizing film via the adhesive between a pair of bonding rolls rotating in the conveying direction. While the laminate is transported in a state where the laminate is adhered to a rotating roll that rotates in the transport direction, the laminate is bonded to the laminate by laminating the transparent film and the polarizing film by applying pressure to the laminate. A first active energy ray irradiation step of irradiating active energy rays to cure the adhesive in this order, and at least one of the pair of bonding rolls is made of rubber. A rubber roll which is rotationally driven has a surface, the rotational speed of the rotating rolls is faster than the rotational speed of the rubber roll. The rotating roll is preferably a cooling roll.

  In the present invention, the rotational speed of the rotating roll is preferably 100.1 or more and 102.0 or less, assuming that the rotational speed of the rubber roll is 100.

  According to the present invention, it is possible to produce a polarizing plate with a good appearance in which the occurrence of corrugated sheet undulations is suppressed. Therefore, when the polarizing plate obtained by the manufacturing method of the present invention is used, a high-quality liquid crystal display device can be provided.

It is a schematic side view which shows one Embodiment of the manufacturing apparatus of the polarizing plate concerning this invention.

  The present invention is a method for producing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film, and an active energy ray-curable adhesive is applied to one side or both sides of a transparent film or a polarizing film. Adhesive application step to be applied, and a laminate formed by laminating a transparent film on one or both sides of the polarizing film via the adhesive is sandwiched between a pair of bonding rolls rotating in the conveying direction, and pressure is applied to the laminate The laminate is irradiated with active energy rays while the laminate is transported in a state of being adhered to a rotating roll that rotates in the transport direction, and a laminating step for pasting the transparent film and the polarizing film. A first active energy ray irradiation step of curing the adhesive in this order. At least one of the pair of bonding rolls is a rubber roll having a surface made of rubber and driven to rotate, and the rotation speed of the rotation roll is faster than the rotation speed of the rubber roll.

First, each element used in the manufacturing method of the present invention will be described in detail.
(Polarizing film)
Specifically, the polarizing film used in the method for producing a polarizing plate of the present invention is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol-based resin film. The polyvinyl alcohol-based resin can be obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and other monomers copolymerizable therewith (for example, ethylene-vinyl acetate copolymer). Polymer). Other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like. The saponification degree of the polyvinyl alcohol-based resin is 85 mol% or more, preferably 90 mol% or more, more preferably 98 to 100 mol%. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000. These polyvinyl alcohol resins may be modified. For example, polyvinyl formal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like may be used.

  A film obtained by forming such a polyvinyl alcohol resin 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. Usually, it is supplied in the form of a roll, the thickness is in the range of 20 to 100 μm, preferably in the range of 30 to 80 μm, and the industrially practical width is in the range of 1500 to 6000 mm.

  The commercially available polyvinyl alcohol film (vinylon VF-PS # 7500, manufactured by Kuraray / OPL film M-7500, manufactured by Nihon Gosei) has a thickness of 75 μm (vinylon VF-PS # 6000, manufactured by Kuraray, vinylon VF-PE #). The original fabric thickness of 6000 (manufactured by Kuraray) is 60 μm.

  The polarizing film is usually a process of dyeing a polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye (dyeing process), and a polyvinyl alcohol resin film adsorbed with the dichroic dye is boric acid. It is manufactured through a step of treating with an 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).

  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, the uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, uniaxial stretching can be performed 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.

  Dyeing of the polyvinyl alcohol resin film with the dichroic dye in the dyeing process is performed, for example, by immersing the polyvinyl alcohol 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 compounds such as trisazo and tetrakisazo 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 resin film by dipping it in an aqueous solution usually containing iodine and potassium iodide is 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 using a dichroic dye as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing the 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 40 ° C. or higher, preferably 50 to 85 ° C., more preferably 55 to 75 ° 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 4 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 is preferably 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.

  In this way, the polyvinyl alcohol resin film is uniaxially stretched, dyed with a dichroic dye, treated with boric acid and washed with water to obtain a polarizing film. The thickness of this polarizing film is usually in the range of 5 to 50 μm.

(Transparent film)
In the present invention, a transparent film is bonded to one side or both sides of the polarizing film described above. Examples of the material constituting the transparent film include cycloolefin resins, cellulose acetate resins, polyethylene terephthalate, polyethylene naphthalate, polyester resins such as polybutylene terephthalate, polycarbonate resins, acrylic resins, and polypropylene. Examples thereof include film materials that have been widely used in the field. When a transparent film is bonded on both surfaces of a polarizing film, each transparent film may be the same or a different type of film.

  The cycloolefin-based resin is a thermoplastic resin (also referred to as a thermoplastic cycloolefin-based resin) having a monomer unit made of a cyclic olefin (cycloolefin), such as norbornene or a polycyclic norbornene-based monomer. The cycloolefin-based resin may be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a ring-opening copolymer using two or more cycloolefins, and has a cycloolefin, a chain olefin, and a vinyl group. An addition polymer with an aromatic compound or the like may be used. Those having a polar group introduced are also effective.

  When using a copolymer of a cycloolefin and a chain olefin or / and an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene, and examples of the aromatic compound having a vinyl group include Examples include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the monomer unit composed of cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). In particular, when a terpolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group is used, the amount of the monomer unit composed of cycloolefin can be made relatively small as described above. In such a terpolymer, the monomer unit composed of a chain olefin is usually 5 to 80 mol%, and the monomer unit composed of an aromatic compound having a vinyl group is usually 5 to 80 mol%.

  Cycloolefin-based resins may be commercially available products such as Topas (manufactured by Ticona), Arton (manufactured by JSR), ZEONOR (manufactured by Nippon Zeon), ZEONEX (manufactured by Nippon Zeon ( Co., Ltd.), Apel (manufactured by Mitsui Chemicals, Inc.), Oxis (OXIS) (manufactured by Okura Kogyo Co., Ltd.) and the like can be suitably used. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, for example, commercially available cycloolefin resin films such as Essina (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa Film (manufactured by Optes Co., Ltd.), etc. You may use goods.

  The cycloolefin resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be given to the cycloolefin-based resin film. Stretching is usually performed continuously while unwinding a film roll, and in a heating furnace, the roll traveling direction (film longitudinal direction), the direction perpendicular to the traveling direction (film width direction), or both Stretched. As the temperature of the heating furnace, a range from the vicinity of the glass transition temperature of the cycloolefin resin to the glass transition temperature + 100 ° C. is usually employed. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

  When the cycloolefin-based resin film is in a roll-wound state, the films tend to adhere to each other and easily cause blocking. Therefore, the cycloolefin-based resin film is usually rolled after the protective film is bonded. In addition, since the cycloolefin resin film generally has poor surface activity, the surface to be bonded to the polarizing film is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment. Is preferred. Among these, plasma treatment that can be carried out relatively easily, particularly atmospheric pressure plasma treatment, and corona treatment are preferable.

  The cellulose acetate-based resin is a cellulose partial or completely esterified product, and examples thereof include a film made of cellulose acetate ester, propionate ester, butyrate ester, and mixed ester thereof. More specifically, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like can be given. As such a cellulose ester resin film, an appropriate commercially available product, 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), Fujitac TD60UL (manufactured by Fuji Film), KC2UAW (manufactured by Konica Minolta Opto), KC4UYW (Konica Minolta Opto) KC6UAW (manufactured by Konica Minolta Opto Co., Ltd.) and the like can be suitably used.

  Moreover, the cellulose acetate type-resin film which provided the phase difference characteristic as a transparent film is also used suitably. Commercially available cellulose acetate resin films to which such retardation characteristics are imparted include WV BZ 438 (manufactured by Fuji Film Co., Ltd.), KC4FR-1 (manufactured by Konica Minolta Opto), and KC4CR-1 (Konica Minolta). Opt Co., Ltd.), KC4AR-1 (Konica Minolta Opto Co., Ltd.) and the like. Cellulose acetate is also called acetyl cellulose or cellulose acetate.

  These cellulose acetate-based resin films are easy to absorb water, and the moisture content of the polarizing plate may affect the end talmi of the polarizing plate. The moisture content during the production of the polarizing plate is preferably closer to the equilibrium moisture content in the storage environment of the polarizing plate, for example, a clean room production line or a roll storage warehouse, and depends on the configuration of the laminated film. About 5%, more preferably 2.5% to 3.0%. The numerical value of the moisture content of this polarizing plate was measured by the dry weight method and is a change in weight after 105 ° C./120 minutes.

  The thickness of the transparent film used in the method for producing a polarizing plate of the present invention is preferably thin, but if it is too thin, the strength is lowered and the processability is poor. On the other hand, when it is too thick, problems such as a decrease in transparency and a longer curing time after lamination occur. Therefore, an appropriate thickness of the transparent film is, for example, 5 to 200 μm, preferably 10 to 150 μm, and more preferably 10 to 100 μm.

  In order to improve the adhesion between the adhesive and the polarizing film and / or the transparent film, the polarizing film and / or the transparent film may be subjected to corona treatment, flame treatment, plasma treatment, ultraviolet treatment, primer coating treatment, saponification treatment, etc. A surface treatment may be applied.

  The transparent film may be subjected to surface treatments such as anti-glare treatment, anti-reflection treatment, hard coat treatment, antistatic treatment, and antifouling treatment alone or in combination of two or more. The transparent film and / or the transparent film surface protective layer may contain a UV absorber such as a benzophenone compound or a benzotriazole compound, or a plasticizer such as a phenyl phosphate compound or a phthalate compound.

  Furthermore, optical functions such as functions as a retardation film, function as a brightness enhancement film, function as a reflection film, function as a transflective film, function as a diffusion film, function as an optical compensation film, etc. Can have a function. In this case, for example, by laminating an optical functional film such as a retardation film, a brightness enhancement film, a reflection film, a transflective film, a diffusion film, and an optical compensation film on the surface of the transparent film, such a function is achieved. In addition, the transparent film itself can be given such a function. Further, the transparent film may have a plurality of functions such as a diffusion film having the function of a brightness enhancement film.

  For example, the above-mentioned transparent film is subjected to a stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or the like, or a process described in Japanese Patent No. 3168850 can be used as a retardation film. The function of can be provided. The retardation characteristics in the retardation film can be appropriately selected, for example, such that the front retardation value is 5 to 100 nm and the thickness direction retardation value is 40 to 300 nm. Further, two or more layers having different central wavelengths of selective reflection by forming fine holes in the transparent film by a method as described in JP-A No. 2002-169025 and JP-A No. 2003-29030 By superimposing these cholesteric liquid crystal layers, a function as a brightness enhancement film can be imparted.

  When a metal thin film is formed on the transparent film by vapor deposition or sputtering, a function as a reflective film or a transflective film can be imparted. By coating the transparent film described above with a resin solution containing fine particles, a function as a diffusion film can be imparted. Moreover, the function as an optical compensation film can be provided by coating and aligning liquid crystalline compounds, such as a discotic liquid crystalline compound, on said transparent film. Moreover, you may make the transparent film contain the compound which expresses retardation. Further, various optical functional films may be directly bonded to the polarizing film using an appropriate adhesive. Examples of commercially available optical functional films include brightness enhancement films such as DBEF (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan), and viewing angle improvements such as WV film (manufactured by Fuji Film Co., Ltd.). Film, Arton Film (manufactured by JSR Corporation), Zeonoor Film (manufactured by Optes Corporation), Essina (manufactured by Sekisui Chemical Co., Ltd.), VA-TAC (manufactured by Comic Minolta Opto Corporation), Sumikalite (Sumitomo) (Chemical Co., Ltd.) etc. can be mentioned.

(Active energy ray-curable adhesive)
The polarizing film and the transparent film are bonded via an active energy ray curable adhesive. Examples of the active energy ray-curable adhesive include an adhesive made of an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like. . However, the present invention is not limited to this, and various active energy ray-curable adhesives (organic solvent adhesives, hot melt adhesives, solventless adhesives) that have been used in the manufacture of polarizing plates. For example, an adhesive made of an acrylic resin composition such as acrylamide, acrylate, urethane acrylate, or epoxy acrylate can be used.

  The epoxy resin means a compound having two or more epoxy groups in the molecule. From the viewpoint of weather resistance, refractive index, cationic polymerizability, and the like, the epoxy resin contained in the curable epoxy resin composition that is an adhesive is an epoxy resin that does not contain an aromatic ring in the molecule (see, for example, Patent Document 1). It is preferable that Examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, and the like.

  The hydrogenated epoxy resin is obtained by a method of glycidyl etherifying a nuclear hydrogenated polyhydroxy compound obtained by selectively subjecting a polyhydroxy compound, which is a raw material of an aromatic epoxy resin, to a nuclear hydrogenation reaction under pressure in the presence of a catalyst. Can be obtained. Examples of aromatic epoxy resins include bisphenol-type epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; phenol novolac epoxy resins, cresol novolac epoxy resins, and hydroxy Examples include novolak-type epoxy resins such as benzaldehyde phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol. Of the hydrogenated epoxy resins, hydrogenated bisphenol A glycidyl ether is preferred.

  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” means a bridged oxygen atom —O— in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.

A compound in which a group in which one or more hydrogen atoms in (CH ₂ ) _m in the above formula are removed 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) exhibits excellent adhesion. Therefore, it is preferably used. Although the alicyclic epoxy resin used preferably below is specifically illustrated, 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) Epoxycyclohexyl methyl 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):

(Wherein 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):

(Wherein 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):

(Wherein 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 their analogs, 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 compound 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 [in the formula (III), R ⁵ = R ⁶ = H, p = 4 compound] ,
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in formula (III), R ⁵ = 4-CH ₃ , R ⁶ = 4-
Compound of CH ₃ , p = 4],
(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 = Compound of 2].

  Moreover, as an aliphatic epoxy resin, the polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide adduct can be mentioned. 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; Polyether of polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin A glycidyl ether etc. are mentioned.

  The epoxy resin which comprises the adhesive agent which consists of an epoxy-type resin composition may be used individually by 1 type, and may use 2 or more types together. The epoxy equivalent of the epoxy resin used in this composition is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent. When the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizing plate 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 this adhesive, cationic polymerization is preferably used as a curing reaction of the epoxy resin from the viewpoint of reactivity. Therefore, it is preferable to mix | blend a cationic polymerization initiator with the curable epoxy resin composition which is an active energy ray hardening-type adhesive agent. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates an epoxy group polymerization reaction. Hereinafter, a cationic polymerization initiator that generates a cationic species or a Lewis acid by irradiation of active energy rays and initiates a polymerization reaction of an epoxy group is referred to as a “photo cationic polymerization initiator”.

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

  Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes.

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

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

  Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide etc. are mentioned.

  Commercially available products of these photocationic polymerization 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" and "Adekaoptomer SP-170" (manufactured by ADEKA Corporation), "CI-5102", " "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", and "CIP-2064S" (manufactured by 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”, “ Examples thereof include “DTS-102” and “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like.

  Only one kind of the cationic photopolymerization initiator may be used alone, or two or more kinds thereof may be mixed and used. Among these, aromatic sulfonium salts are preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus can provide a cured product having excellent curability and good mechanical strength and adhesive strength.

  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 and adhesive strength tend to decrease. Moreover, when the compounding quantity of a photocationic polymerization initiator exceeds 20 weight part with respect to 100 weight part of epoxy resins, the hygroscopic property of hardened | cured material will become high because the ionic substance in hardened | cured material will increase, and durability performance. May be reduced.

  When using a photocationic polymerization initiator, the curable epoxy resin composition 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 photoreductive dyes.

  Specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o -Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2 Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other α, α-diethoxyacetophenone, benzi Ru, fluorenone, xanthone, uranyl compounds, halogen compounds, and the like. A photosensitizer may be used individually by 1 type and may use 2 or more types together. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.

  The epoxy resin contained in the adhesive is cured by photocationic polymerization, but may be cured by both photocationic polymerization and thermal cationic polymerization. In the latter case, it is preferable to use a photocationic polymerization initiator and a thermal cationic polymerization initiator in combination.

  Examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thioranium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. These thermal cationic polymerization initiators can be easily obtained as commercial products. For example, “Adeka Opton CP77” and “Adeka Opton CP66” (manufactured by ADEKA Corporation), “CI” are available under the trade names. -2639 "and" CI-2624 "(manufactured by Nippon Soda Co., Ltd.)," Sun-Aid SI-60L "," Sun-Aid SI-80L "and" Sun-Aid SI-100L "(manufactured by Sanshin Chemical Industry Co., Ltd.) Etc.

  The active energy ray-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, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3 -Ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolac oxetane and the like. These oxetanes can be easily obtained as commercial products. For example, all of these oxetanes are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”. "Aron oxetane OXT-221" and "Aron oxetane OXT-212" (manufactured by Toagosei Co., Ltd.). These oxetanes are usually contained in the curable epoxy resin composition in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight.

  As the polyols, those having no acidic group other than phenolic hydroxyl groups are preferable. For example, polyol compounds having no functional groups other than hydroxyl groups, polyester polyol compounds, polycaprolactone polyol compounds, polyol compounds having phenolic hydroxyl groups, polycarbonates A polyol etc. can be mentioned. 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. These polyols are usually contained in the curable epoxy resin composition in a proportion of 50% by weight or less, preferably 30% by weight or less.

  Active energy ray-curable adhesives include ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, leveling agents, plasticizers, antifoaming agents, etc. Additives can be blended. Examples of the ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed inorganic compounds. The antioxidant is a hindered phenol-based antioxidant. Etc.

  Active energy ray-curable adhesives can be used as solventless adhesives that are substantially free of solvent components, but each coating method has an optimum viscosity range, A solvent may be included. It is preferable to use a solvent that dissolves the epoxy resin composition and the like well without degrading the optical performance of the polarizing film. For example, hydrocarbons represented by toluene, esters represented by ethyl acetate, and the like. And organic solvents such as The viscosity of the active energy ray-curable adhesive used in the present invention is, for example, in the range of about 5 to 1000 mPa · s, preferably 10 to 200 mPa · s, and more preferably 20 to 100 mPa · s.

<Production method of polarizing plate>
Next, the manufacturing apparatus and manufacturing method of the polarizing plate of this invention are demonstrated, referring drawings. FIG. 1 is a schematic view showing an embodiment of a production apparatus used in the method for producing a polarizing plate of the present invention.

  The polarizing plate manufacturing apparatus shown in FIG. 1 bonds adhesive coating apparatuses 11 and 12 for applying an adhesive to one side of transparent films 2 and 3, transparent films 2 and 3, and polarizing film 1. Bonding rolls (nip rolls) 51 and 52 for obtaining the laminated body 4, the rotating roll 13 in close contact with the laminated body 4, and the first activity installed at a position facing the outer peripheral surface of the rotating roll 13. Energy beam irradiation devices 31, 32, second active energy beam irradiation devices 16 to 18 installed further downstream in the conveyance direction, and a nip roll 19 for conveyance are sequentially provided along the conveyance direction.

  First, an active energy ray-curable adhesive is applied to one side of the transparent films 2 and 3 that are continuously drawn out from a rolled state (adhesive application). Process).

And the laminated body formed by laminating | stacking the transparent films 2 and 3 with which the adhesive agent was apply | coated on both surfaces of the polarizing film 1 continuously drawn out from the state wound by roll shape via an adhesive agent is conveyed. In a state of being sandwiched between a pair of bonding rolls 51 and 52 that rotate in the direction, by pressing at least one bonding roll in the direction of the other bonding roll and applying pressure to the laminate, a polarizing film < The film 1 and the transparent films 2 and 3 are bonded together to form a laminate 4 (bonding step).

  Next, in the process of transporting the laminate 4 in close contact with the outer peripheral surface of the rotating roll 13, the active energy rays are irradiated from the first active energy ray irradiation devices 31, 32 toward the outer peripheral surface of the rotating roll 13. Then, the adhesive is polymerized and cured (first active energy ray irradiation step).

  In addition, the 2nd active energy ray irradiation apparatuses 16-18 arrange | positioned in a conveyance direction downstream are apparatuses for fully superposing | polymerizing and hardening an adhesive agent (2nd active energy ray irradiation process), as needed. Can be added or omitted. Finally, the laminate 4 passes through the conveyance nip roll 19 and is wound around the winding roll 20 as a polarizing plate. Hereinafter, each step will be described in detail.

(Adhesive application process)
The method for applying the adhesive to the transparent films 2 and 3 is not particularly limited, 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. Of these, taking into consideration the thin film coating, the degree of freedom of the pass line, the wideness, etc., gravure rolls are preferable as the adhesive coating apparatuses 11 and 12.

  When applying an adhesive using a gravure roll as the adhesive application device 11, 12, the thickness of the applied adhesive (application thickness) is preferably about 0.1 to 10 μm, more preferably. 0.2 μm to 4 μm. The coating thickness of the adhesive is adjusted by the draw ratio, which is the speed ratio of the gravure roll to the line speed of the transparent film. Generally, by adjusting the draw ratio (gravure roll speed / line speed) to 0.5 to 10, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 μm. More specifically, the line speed of the transparent films 2 and 3 is 10 to 100 m / min, the gravure roll is rotated in the direction opposite to the conveying direction of the transparent films 2 and 3, and the speed of the gravure roll is 5 to 1000 m / min. By doing so, the application thickness of the adhesive can be adjusted to about 0.1 to 10 μm.

  After preparation, the adhesive is usually at a predetermined temperature within the range of 15 to 40 ° C. ± 5 ° C. (for example, when the predetermined temperature is 30 ° C., 30 ° C. ± 5 ° C.), preferably ± 3 ° C., more preferably It is applied in an environment adjusted to ± 1 ° C.

(Bonding process)
In this step, the transparent films 2 and 3 to which the adhesive is applied by the above-described steps are laminated on both surfaces of the polarizing film 1 that is continuously drawn out from the state wound in a roll shape. In a state where the laminate is sandwiched between a pair of bonding rolls 51 and 52 rotating in the transport direction, for example, the bonding roll 51 is pressed in the direction of the bonding roll 52 so that the polarizing film 1 and the transparent film are pressed. 2 and 3 are bonded together to form a laminate 4. At this time, an angle within a range of ± 3 °, preferably an angle within a range of ± 1 °, particularly preferably in the pressing direction, with respect to a plane perpendicular to the pressing direction of the bonding roll. It is preferable to transport the polarizing film between the bonding rolls so as to overlap the vertical surface. By doing in this way, a polarizing film and a transparent film will contact before the bonding roll, and a bubble will not generate | occur | produce.

  In FIG. 1, the adhesive is uniformly applied to one side of the transparent films 2, 3, and the polarizing film 1 is overlapped on the surface of the transparent films 2, 3 applied with the bonding rolls 51, 52. Although the method to combine is shown, the adhesive agent is apply | coated uniformly on both surfaces of the polarizing film 1, and the transparent films 2 and 3 are piled up on the surface by which the adhesive agent of the polarizing film 1 was apply | coated, and the bonding rolls 51 and 52 are used. You may paste.

  Examples of the material of the bonding rolls 51 and 52 include a metal roll and a rubber roll whose surface is made of rubber. At least one of the pair of bonding rolls 51 and 52 is a rubber roll that has a surface made of rubber and is rotationally driven. In the manufacturing apparatus shown in FIG. 1, for example, the lower roll 52 can be a rubber roll. Usually, the rotational speed of the rubber roll that is rotationally driven matches the line speed of the laminate that passes between the pair of bonding rolls. As the other laminating roll, a metal roll is preferably used, which may follow the movement of the line of the laminate or be rotationally driven. The rotation speed of the rubber roll is, for example, 10 to 50 m / min.

  Various known materials can be used as the base material of the metal roll, but SUS304 is preferable, and the surface is more preferably subjected to chrome plating. The material of the rubber roll is not particularly limited, and examples thereof include EPDM, NBR, urethane, titan, and silicon. Although the hardness of a rubber roll is not specifically limited, Usually, it is 60-100 degrees, Preferably it is 85-95 degrees. In addition, the hardness of a rubber roll can be measured with the hardness meter based on JISK6253. As a commercially available hardness meter, for example, a rubber hardness meter “Type-A” manufactured by Asuka Corporation is used. Specifically, the resistance of the surface of the rubber roll when the surface is pressed with a stick or the like is measured with a hardness meter.

  As for the pressure applied to the laminate by pressing the metal roll and the rubber roll, the instantaneous pressure in a two-sheet type press case (for ultra-low pressure) made of Fuji Film is preferably 0.5 to 3.0 MPa, more preferably 0.7. -2.3 MPa. Although the diameter of the bonding rolls 51 and 52 is not specifically limited, Usually, it is 50-400 mm. Moreover, the diameter of the two (pair) bonding rolls 51 and 52 may be the same, and may differ.

(First active energy ray irradiation process)
The rotating roll 13 forms a convex curved surface having a mirror-finished outer peripheral surface, and the laminate 4 is conveyed while closely contacting the surface. In the process, the adhesive is polymerized and cured by the active energy ray irradiation devices 31 and 32. Let The diameter of the rotating roll 13 is not particularly limited when the adhesive is polymerized and cured and the laminate 4 is sufficiently adhered. The rotating roll 13 shall be driven at a rotational speed faster than the rotational speed of the rubber roll that is rotationally driven among the pair of bonding rolls 51 and 52. Of the pair of bonding rolls 51 and 52, assuming that the rotational speed of the rubber roll that is rotationally driven is 100, the rotational speed of the rotary roll 13 is preferably 100.1 or more and 102.0 or less, more preferably 100. .1 to 101.5. If it is less than 100.1, wave curling is likely to occur in the laminate. On the other hand, if it exceeds 102.0, there is a possibility that the film and the roll slip to cause scratches.

  The rotation speed of the rotating roll 13 is, for example, 10 to 50 m / min. The rotational speed of the rotary roll 13 does not need to be controlled at a constant level. For example, the rotational speed of the rotary roll 13 may be appropriately controlled while confirming the state of occurrence of corrugated swell according to the type of film and the slipperiness of the roll surface. .

  Moreover, you may make the rotary roll 13 act as a cooling roll for radiating the heat which arises in the laminated body 4 at the time of the polymerization hardening by irradiation of an active energy ray. In that case, it is preferable that the surface temperature of a cooling roll is set to 4-30 degreeC.

  The light source used for polymerizing and curing the adhesive by irradiation with active energy rays is not particularly limited, but is preferably a light source having an emission distribution at a wavelength of 400 nm or less. Examples of such a light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, and a metal halide lamp. The active energy ray irradiation in the first active energy ray irradiating step is preferably performed in a plurality of times. FIG. 1 shows a case where irradiation of active energy rays is performed twice, that is, two light sources (active energy ray irradiation devices 31 and 32) are arranged along the transport direction of the laminate. .

The intensity of light irradiation to the active energy ray-curable adhesive each time is determined for each composition of the adhesive and is not particularly limited, but is preferably 10 to 5000 mW / cm ² . When the light irradiation intensity to the resin composition is less than 10 mW / cm ² , the reaction time becomes too long, and when it exceeds 5000 mW / cm ² , adhesion occurs due to heat radiated from the light source and heat generated during polymerization of the composition. There is a possibility that yellowing of the epoxy resin composition as a constituent material of the agent or deterioration of the polarizing film may occur. The irradiation intensity is preferably an intensity in a wavelength region effective for activation of the photocationic polymerization initiator, more preferably an intensity in a wavelength region of a wavelength of 400 nm or less, and further preferably a wavelength region of a wavelength of 280 to 320 nm. It is the intensity in (UVB).

  When the active energy rays are ultraviolet rays, in the step of irradiating the laminate 4 with the active energy rays, the irradiation time is 0.1 while applying a tension of 100 to 800 N / m in the longitudinal direction (conveying direction) to the laminate 4. It is preferable that the laminate 4 is conveyed at a line speed that is at least 2 seconds.

(Second active energy ray irradiation process)
When the integrated light quantity of the active energy rays by the active energy ray irradiation devices 31 and 32 is insufficient, the active energy ray irradiation devices 16 to 18 after the second are further provided to irradiate the active energy rays, and It is preferable to accelerate the curing of the adhesive. Integrated light intensity in the entire process, in conjunction with the first active energy ray irradiation process is 10 mJ / cm ² or more is preferably set to particular a 10~5,000mJ / cm ^2. When the integrated light amount to the adhesive is less than 10 mJ / cm ² , active species derived from the initiator are not sufficiently generated, and the adhesive is not sufficiently cured. On the other hand, when the integrated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity. At this time, depending on the film to be used, the combination of adhesive types, and the like, it is different in which wavelength region (UVA (320 to 390 nm), UVB (280 to 320 nm), etc.) the accumulated light amount is necessary.

  In order to surely cure the adhesive at the end of the polarizing plate (laminate), for example, a method of arranging “Light Hammer 10” made by FUSION, which is an electrodeless D bulb lamp, so as to cross the film running. Is mentioned.

  The rate at which the active energy ray-curable resin is cured, that is, the reaction rate, is preferably 90% or more, more preferably 95% or more.

(Polarizing plate winding process)
The tension for winding the laminate (polarizing plate) 4 is set to 30 N / cm ^{2 to} 150 N / cm ² . Preferably, a ^{30N / cm 2 ~120N / cm 2} . If it is less than 30 N / cm ^2, it is not preferable because winding deviation occurs when a long roll is transferred. When it is larger than 150 N / cm ² , the tightness of the winding is strong and the tarmi is likely to occur.

Note that the longer the winding length, the more likely it is that tightening will occur with the same tension (a phenomenon that makes it difficult to return to a flat state when unrolled), so the tension is lowered continuously or stepwise while the polarizing plate is wound around the core. You may let them. Even in such a method of reducing the tension by applying a so-called taper, the tension at that time is 150 N / cm ² or less.

  The length of the polarizing plate wound around the core is not particularly limited, but is preferably 100 m or more and 4000 m or less.

  The diameter of the cylindrical core is preferably 6 inches to 12 inches. The larger the diameter of the core is, the more preferable, and more preferable is 11 inches, 12 inches, and the like.

  The material of the cylindrical core is not particularly limited as long as it can be used in a clean room and does not easily generate dust, and can secure an appropriate strength so that a wide-width polarizing plate can be wound. FRP (glass fiber reinforced plastic) Etc. can be selected.

  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.

[Example 1]
(Preparation of polarizing film)
As a polyvinyl alcohol raw film, a long polyvinyl alcohol film “OPL film M-7500 (manufactured by Nippon Gosei Co., Ltd.)” having a polymerization degree of 2400, a saponification degree of 99.9 mol%, a thickness of 75 μm, and a width of 3000 mm was used. Stretching was performed with a difference in peripheral speed between the driving nip rolls before and after the treatment tank.

  First, the film was sufficiently swollen by immersing it in a swelling tank containing pure water at 30 ° C. for 80 seconds while keeping the tensioned state of the film so that the original film was not loosened. The inlet / outlet roll speed ratio accompanying the swelling in the swelling tank was 1.2. After draining with a nip roll, it was immersed in a water immersion tank containing 30 ° C. pure water for 160 seconds. The draw ratio in the machine direction in this tank was 1.09 times.

  Next, uniaxial stretching was performed at a draw ratio of about 1.5 times while being immersed in a dyeing tank containing an aqueous solution of 0.02 / 2.0 / 100 in weight ratio of iodine / potassium iodide / water. Then, while being immersed in a boric acid bath containing an aqueous solution of potassium iodide / boric acid / water at a weight ratio of 12 / 3.7 / 100 at 55.5 ° C. for 130 seconds, the cumulative draw ratio from the original fabric is 5 Uniaxial stretching was performed until it became 7 times. Then, it was immersed at 40 ° C. for 60 seconds in a boric acid bath containing an aqueous solution of potassium iodide / boric acid / water at a weight ratio of 9 / 2.4 / 100.

  Further, it is washed with pure water at 8 ° C. for about 16 seconds in a water washing tank, and then sequentially passed through a drying furnace at about 60 ° C. and then a drying furnace at about 85 ° C., and the residence time in these drying furnaces is 160 in total. Drying was performed for a second. Thus, a polarizing film having a thickness of 28 μm on which iodine was adsorbed and oriented was obtained.

(Preparation of polarizing plate)
As a transparent film, an acetic acid cellulose resin film “KC4CR-1 (manufactured by Konica Minolta Opto Co., Ltd.)” having a retardation property of 40 μm thickness and a triacetyl cellulose film “KC8UX2MW” (Konica Minolta) having a thickness of 80 μm are used. Prepared).

  A polarizing plate was produced by the apparatus shown in FIG. 1 using the polarizing film and the transparent film prepared as described above. First, an epoxy resin composition “KR series” (manufactured by ADEKA), which is an ultraviolet curable adhesive, is applied to one side of an acetic acid cellulose resin film “KC4CR-1” to which the above retardation characteristics are imparted. Coating was performed using an apparatus (microchamber doctor: manufactured by Fuji Machine Co., Ltd.). In addition, an epoxy resin composition “KR series” (manufactured by ADEKA), which is an ultraviolet curable adhesive, was applied to one side of the triacetyl cellulose film “KC8UX2MW” using the same adhesive coating apparatus. At this time, the line speed of the polarizing film laminate in the adhesive coating apparatus was 25 m / min, the thickness of the adhesive layer on the cellulose acetate-based resin film “KC4CR-1” was about 4.0 μm, and triacetyl cellulose. The thickness of the adhesive layer on the film “KC8UX2MW” was set to about 3.3 μm (total of about 7.3 μm).

  Next, it is transported between a rubber roll that is driven and rotated and a metal roll so that the cellulose acetate resin film “KC4CR-1” and the triacetyl cellulose film “KC8UX2MW” are aligned on both surfaces of the polarizing film. And bonded together via the epoxy resin composition (ultraviolet curable adhesive) (bonding step).

  The polarizing film on which the two types of transparent films are bonded is transferred at a line speed of 25 m / min while applying a tension of 600 N / m in the longitudinal direction and closely contacting the cooling roll, and two metal halide lamps (manufactured by GS-YUSAS) The first active energy ray irradiation process is performed by passing through the ultraviolet rays irradiated from one lamp with an electric power of 130 W / cm, and then three electrodeless D bulb lamps ("Light Hammer" manufactured by Fusion) 10 ", the amount of electric power of one lamp (216 mW / cm) was passed through the ultraviolet rays irradiated to perform the second active energy ray irradiation step, and a polarizing plate was produced.

  The three electrodeless D bulb lamps were obtained by arranging three units of six electrodeless D bulb lamps arranged in the film width direction in the film longitudinal direction.

  When passing through the metal halide lamp, the triacetyl cellulose film “KC8UX2MW” bonded to the polarizing film is brought into contact with the outer peripheral surface of the cooling roll set at 23 ° C., and from the cellulose acetate resin film “KC4CR-1” side. Irradiated with ultraviolet rays. The rotation speed of the rubber roll driven and rotated in the bonding step was 25.00 m / min, and the rotation speed of the cooling roll was 25.23 m / min. That is, assuming that the rotation speed of the rubber roll is 100, the rotation speed of the cooling roll was 100.9.

In this example, the integrated light amount of the first active energy ray irradiation step and the second active energy ray irradiation step was 468 mJ / cm ² . Here, the integrated light quantity is based on a value measured by a light irradiation intensity measuring device (UV Power Pack II manufactured by FusionUV) in a wavelength region (UVB) of a wavelength of 280 to 320 nm.

(Appearance evaluation)
About the polarizing plate of Example 1 produced as mentioned above, when the external appearance was observed by the reflection test which applied the fluorescent lamp, generation | occurrence | production of the corrugated sheet wave | undulation was not confirmed.

[Example 2]
Example 1 except that a 60 μm thick cycloolefin resin film “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.) was used instead of the cellulose acetate resin film “KC4CR-1” as the transparent film. A polarizing plate of Example 2 was produced in the same manner as described above.

(Appearance evaluation)
About the polarizing plate of Example 2 produced as mentioned above, when the external appearance was observed similarly to Example 1, generation | occurrence | production of a corrugated sheet shape wave | undulation was not confirmed.

[Example 3]
As a transparent film, instead of the cellulose acetate resin film “KC4CR-1”, a cycloolefin resin film “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 25 μm is applied to the triacetyl cellulose film “KC8UX2MW”. Instead, a triacetyl cellulose film “K2UAW” (manufactured by Konica Minolta Co., Ltd.) having a thickness of 25 μm was used. / Min. That is, assuming that the rotation speed of the rubber roll is 100, the rotation speed of the cooling roll was 100.3. Except for these points, the polarizing plate of Example 3 was produced in the same manner as Example 1.

(Appearance evaluation)
About the polarizing plate of Example 3 produced as mentioned above, when the external appearance was observed similarly to Example 1, generation | occurrence | production of a corrugated sheet wave | undulation was not confirmed.

[Example 4]
As a transparent film, instead of the cellulose acetate-based resin film “KC4CR-1”, a cycloolefin-based resin film “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 50 μm is used as the triacetyl cellulose film “KC8UX2MW”. Instead, a triacetyl cellulose film “TD60UL” (manufactured by Fuji Film Co., Ltd.) having a thickness of 60 μm is used. .28 m / min. That is, assuming that the rotation speed of the rubber roll is 100, the rotation speed of the cooling roll was 101.1. Except for these points, the polarizing plate of Example 4 was produced in the same manner as Example 1.

(Appearance evaluation)
About the polarizing plate of Example 4 produced as mentioned above, when the external appearance was observed similarly to Example 1, generation | occurrence | production of corrugated sheet-like wave | undulation was not confirmed.

[Example 5]
A polarizing plate was produced in the same manner as in Example 1 except that the rotation speed of the cooling roll was set to 102.2 with respect to the rotation speed 100 of the rubber roll driven and rotated in the bonding step.

(Appearance evaluation)
The appearance of the polarizing plate of Example 5 produced as described above was observed. As a result, although the occurrence of corrugated waviness was not confirmed, the occurrence of scratches was confirmed.

[Comparative Example 1]
The rotating speed of the cooling roll was 100 with respect to the rotating speed 100 of the rubber roll driven and rotated in the bonding step, that is, the polarizing plate of Comparative Example 1 was produced in the same manner as in Example 1 except that the rotating speed was the same. .

(Appearance evaluation)
When the external appearance was observed about the polarizing plate of the comparative example 1 produced as mentioned above, generation | occurrence | production of the corrugated sheet-like wave | undulation was confirmed.

  The polarizing plate of the present invention can be effectively applied to various display devices including liquid crystal display devices.

  DESCRIPTION OF SYMBOLS 1 Polarizing film, 2, 3 Transparent film, 4 Laminate (polarizing plate), 11, 12 Adhesive coating apparatus, 13 Rotating roll (cooling roll), 16, 17, 18, 31, 32 Active energy ray irradiation apparatus, 19 Transport nip roll, 20 take-up roll.

Claims (3)

A method for producing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film,
An adhesive application step of applying an active energy ray-curable adhesive to one side or both sides of the transparent film or the polarizing film;
The transparent film is sandwiched between a pair of laminating rolls that rotate in the transport direction by laminating a laminate in which the transparent film is laminated on one side or both sides of the polarizing film with the pressure applied to the laminate. A bonding step of bonding the transparent film and the polarizing film;
While transporting the laminated body in a state where the outer peripheral surface is mirror-finished and rotationally driven in the carrying direction and in close contact with a rotating roll, the laminated body is irradiated with active energy rays to cure the adhesive. A first active energy ray irradiation step in this order,
At least one of the pair of bonding rolls is a rubber roll that has a surface made of rubber and is driven to rotate,
The rotating speed of the said rotating roll is a manufacturing method of a polarizing plate faster than the rotating speed of the said rubber roll.   The method for producing a polarizing plate according to claim 1, wherein the rotating roll is a cooling roll.   The rotating speed of the said rotating roll is a manufacturing method of the polarizing plate of Claim 1 or 2 which is 100.1 or more and 102.0 or less when the rotating speed of the said rubber roll is set to 100.

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