JP6317061B2 - 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).

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

  Patent Document 2 describes a manufacturing method in which a transparent film coated with an adhesive is conveyed to a bonding roll via a guide roll. However, in the conventional method, wrinkles may occur in the transparent film conveyed to the bonding roll. In particular, wrinkles may be noticeably generated in a thin film, and the wrinkles of the transparent film at the time of pasting caused the bubbles to be mixed into the adhesive layer. Such a defect in the polarizing plate caused a deterioration in the quality of the liquid crystal display device.

  An object of this invention is to provide the manufacturing method of the polarizing plate which can prevent that a wrinkle generate | occur | produces in the transparent film conveyed by the bonding roll.

  The present inventors can control the tension of the transparent film without touching the adhesive application surface by conveying the transparent film coated with the adhesive to the bonding roll via the suction roll. It has been found that wrinkles can be prevented from occurring in the transparent film conveyed to the surface.

  This invention is made | formed based on the said knowledge, It is a manufacturing method of the polarizing plate by which a transparent film is bonded by the single side | surface or both surfaces of a polarizing film, Comprising: An adhesive agent is apply | coated to the single side | surface of the said transparent film. An adhesive application step, and a bonding step of bonding the transparent film to one or both sides of the polarizing film via the adhesive, and after the adhesive application step, the transparent film It conveys to the said bonding process through a suction roll. The suction roll has a large number of intake holes on the outer peripheral surface of the outer cylinder, and the conveyed object is obtained by rotating the outer cylinder while holding the conveyed object by adsorbing the conveyed object to the roll surface by the intake air from the intake holes. It is a roll which conveys.

  In one embodiment of the present invention, the adhesive is an active energy ray-curable adhesive, and after the bonding step, active energy rays are applied to the laminated body of the transparent film and the polarizing film that are bonded. An active energy ray irradiation step of irradiating and curing the adhesive is further provided. Since the active energy ray-curable adhesive is not an adhesive that cures by drying, and it can be prevented from dripping by adjusting the viscosity, there is a restriction that it must be applied immediately after the adhesive is applied. And suitable for the production method of the present invention in which the tension is controlled after the adhesive is applied.

  In one embodiment of the present invention, the surface modification step further includes a surface modification step for performing a treatment for improving adhesiveness on the surface of the transparent film to which the adhesive is applied before the adhesive coating step. Then, the said transparent film is conveyed to the said adhesive agent application process through a 2nd suction roll. In this embodiment, you may make it convey the said transparent film to the said surface treatment process via a 3rd suction roll.

  According to the method for producing a polarizing plate of the present invention, even if the transparent film is thin, the polarizing film is bonded to a transparent film having no wrinkles, whereby a polarizing plate having no appearance defect can be produced. It is possible to prevent deterioration of the quality of the display device.

It is a schematic side view which shows 1st Embodiment of the manufacturing apparatus of the polarizing plate concerning this invention. It is sectional drawing along the axial center direction of the suction roll. FIG. 3 is a sectional view taken along line III-III in FIG. It is a schematic side view which shows 2nd 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, the adhesive applying step of applying an adhesive to one side of the transparent film, and the transparent film as a polarizing film. A polarizing plate that is bonded to one side or both sides of an adhesive through an adhesive, and transports the transparent film to the bonding step via a first suction roll after the adhesive application step. It is a manufacturing method. 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 500 to 6000 mm. Alternatively, a polyester film such as an olefin film or a PET film may be used as a base material, and a polyvinyl alcohol resin may be applied on both surfaces or one surface thereof.

  The commercially available polyvinyl alcohol film (vinylon VF-PS # 7500, manufactured by Kuraray / OPL film M-7500, manufactured by Nippon Gosei) has a thickness of 75 μm (vinylon VF-PS # 6000, manufactured by Kuraray, vinylon VF-PE #). (6000, manufactured by Kuraray) has a thickness of 60 μm, (vinylon VF-PE # 5000, manufactured by Kuraray) has a thickness of 50 μm, (vinylon VF-PE # 3000, manufactured by Kuraray) has a thickness of 30 μm, etc. .

  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 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 4 to 40 ° C., and the immersion time is usually 1 to 120 seconds. A method of spraying water in the form of a spray during or before and after the water-washing process, or spraying water from a slit-shaped ejection part and filling the film strongly may be appropriately selected. After the water washing treatment, a drying treatment is usually performed to obtain a polarizing film. A method such as blowing off water with an air knife or the like in the previous stage of the drying treatment, or sucking out moisture on the surface with a water absorption roll may be appropriately employed. 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 95 ° 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 3 to 50 μm. In addition, it is not restricted to the above, The film which has the polarizing function produced by another method is employ | adopted as a polarizing film.

(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 cycloolefin resin films generally have poor surface activity, surface treatment such as plasma treatment, corona discharge treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment is applied to the surface to be bonded to the polarizing film. It is preferred to do so. Among these, plasma treatment that can be carried out relatively easily, particularly atmospheric pressure plasma treatment, and corona discharge 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), KC4UYW (manufactured by Konica Minolta Opto), KC6UAW (Konica Minolta Opto) KC2UAW (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 adhesiveness between the adhesive and the polarizing film and / or the transparent film, the polarizing film and / or the transparent film may be subjected to a surface treatment. For example, surface treatment such as corona discharge treatment, flame treatment, plasma treatment, ultraviolet treatment, primer coating treatment, saponification treatment, etc. can be mentioned, but uniform treatment is possible, the device is simple and low in cost, Particularly preferred are corona discharge treatment and plasma treatment.

  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.

(adhesive)
The polarizing film and the transparent film are bonded via an adhesive. As the adhesive, an active energy ray-curable adhesive, a water-based adhesive, or the like can be used. Since the active energy ray-curable adhesive is not an adhesive that cures by drying, and it can be prevented from dripping by adjusting the viscosity, there is a restriction that it must be applied immediately after the adhesive is applied. And suitable for the production method of the present invention in which the tension is controlled after the adhesive is applied.

  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, durability, 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. Etc.) can be adopted. These include acrylic compositions, acrylamide compositions, epoxy acrylate compositions, urethane compositions, vinyl compositions and the like. Examples of the curing reaction include curing by a polymerization reaction such as radical polymerization, cationic polymerization, anionic polymerization, and thermal polymerization.

  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.

  Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane emulsion adhesive. Polyvinyl alcohol resins used as adhesives include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as other single quantities copolymerizable with vinyl acetate. And vinyl alcohol copolymers obtained by saponifying the copolymer with the polymer, and modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups. A polyhydric aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, or the like may be added as an additive to the water-based adhesive. When such a water-based adhesive is used, the adhesive layer obtained therefrom is usually much thinner than 1 μm.

  Usually, an adhesive agent is apply | coated at the temperature of 15-40 degreeC after the preparation, and the bonding temperature is the range of 15-30 degreeC normally. When using a water-system adhesive, after bonding a film, in order to remove the water contained in a water-system adhesive, it is made to dry. The temperature of the drying furnace is preferably 30 ° C to 90 ° C. If it is less than 30 ° C., the adhesive surface tends to be peeled off. If it is 90 ° C. or higher, the optical performance of a polarizer or the like may be deteriorated by heat. The drying time can be 10 to 1000 seconds.

  After drying, it may be further cured at room temperature or slightly higher temperature, for example, at a temperature of about 20 to 45 ° C. for about 12 to 600 hours. The temperature at the time of curing is generally set lower than the temperature adopted at the time of drying. Next, the manufacturing apparatus and manufacturing method of the polarizing plate of this invention are demonstrated, referring drawings.

<Polarizing plate manufacturing method (first embodiment)>
FIG. 1 is a schematic view showing a first embodiment of a production apparatus used in the method for producing a polarizing plate of the present invention. In the present embodiment, an active energy ray-curable adhesive is employed as an adhesive used for bonding the transparent film and the polarizing film.

  The polarizing plate manufacturing apparatus shown in FIG. 1 controls the tension of the adhesive coating apparatuses 11 and 12 for applying an adhesive to one side of the transparent films 2 and 3 and the transparent films 2 and 3 coated with the adhesive. And the 1st suction rolls 61 and 62 conveyed to the following process, the bonding rolls (nip roll) 51 and 52 for bonding the transparent films 2 and 3 and the polarizing film 1, and obtaining the laminated body 4, The roll 13 for bringing the laminate 4 into close contact, the first active energy ray irradiating devices 31 and 32 installed at positions facing the outer peripheral surface of the roll 13, and further installed downstream in the transport direction. Second active energy ray irradiating devices 16 to 18 and a transport nip roll 19 are sequentially provided along the transport 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 by the adhesive application devices 11 and 12 (adhesive application step). ). The transparent films 2 and 3 to which the adhesive is applied are conveyed to the bonding rolls 51 and 52 through the first suction rolls 61 and 62. In the 1st suction rolls 61 and 62, it controls so that the tension | tensile_strength of the transparent films 2 and 3 may become an appropriate value, and is conveyed to the bonding rolls 51 and 52. FIG.

  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. Transparent film 1 by pressing at least one bonding roll in the direction of the other bonding roll and applying pressure to the laminate while sandwiched between a pair of bonding rolls 51 and 52 rotating in the direction. And polarizing 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 roll 13, the active energy rays are irradiated from the first active energy ray irradiating devices 31, 32 toward the outer peripheral surface of the roll 13, and bonded. The agent 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 process and each component 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 application methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Among these, considering the thin film coating, the degree of freedom of the pass line, the correspondence to the width, 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.

  The transparent films 2 and 3 are conveyed from the adhesive application devices 11 and 12 to the bonding rolls 51 and 52 via the first suction rolls 61 and 62. The 1st suction rolls 61 and 62 are arrange | positioned in the position where the surface on the opposite side to the surface which apply | coated the adhesive of the transparent films 2 and 3 contacts a roll. Hereinafter, the first suction rolls 61 and 62 will be described in detail.

(Suction roll)
2 is a cross-sectional view along the axial direction of the first suction rolls 61 and 62, FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2, and the first suction rolls 61 and 62 are transparent films. It is sectional drawing of the direction orthogonal to the axial center at the time of receiving. The first suction rolls 61 and 62 are composed of an inner cylinder 101 and an outer cylinder 102. One support shaft 103 of the inner cylinder 101 protrudes outward through the insertion hole 105 of one end plate 104 of the outer cylinder 102 and is supported and fixed to the support base 106. The support shaft 103 is provided with a communication hole 107 that allows the inside of the inner cylinder 101 to communicate with the outside, and the opening on the outside functions as the suction port 108. The suction port 108 is connected to an intake device such as a suction blower. The other support shaft 109 of the inner cylinder 101 is fitted into the insertion hole 111 of the other end plate 110 of the outer cylinder 102, and is supported between the end plate 110 by a bearing 112 such as a bearing. On the peripheral surface of the inner cylinder 101, as shown in FIG. 3, a large number of intake holes 113 are formed at portions corresponding to the holding angles at which the outer cylinder 102 adsorbs and holds the transparent films 2 and 3. A large number of air intake holes 119 are formed in the outer cylinder 102 over the entire circumference in the width direction corresponding to the holding position of the transparent films 2 and 3. The outer cylinder 102 is rotatably supported by the support shaft 103 of the inner cylinder 101 with a bearing 114 such as a bearing interposed in the insertion hole 105 of one end plate 104, and the rotation shaft 115 is mounted on the other end plate 110. The rotating shaft 115 is supported on the bearing 116 by projecting. The bearing 116 and the support base 106 are installed on a fixed surface. The rotating shaft 115 is connected to a drive motor. The outer cylinder 102 has a gap so that the inner surface of the outer wall can rotate with respect to the peripheral surface of the inner cylinder 101.

  When the outer intake device is operated, the suction is performed from the suction hole 119 of the outer cylinder 102 through the suction hole 113 of the inner cylinder 101, the inner cylinder 101, and the communication hole 107. This suction force is shown in FIG. As described above, the transparent films 2 and 3 start to be sucked at the position of the suction hole 102 at the start end of the holding angle of the outer cylinder 102, and there are a large number of intake holes 113 of the inner cylinder 101 within the range of the holding angle. Conveyance is guided along with the rotation of the cylinder 102, and after the last end of the holding angle, the suction force 113 does not act because it deviates from the position where the intake hole 113 of the inner cylinder 101 is drilled, so that the holding force with respect to the transparent films 2 and 3 is released. Then it is sent out.

  The tension of the transparent films 2 and 3 is preferably adjusted to 200 to 1000 N / m by the first suction rolls 61 and 62. When the tension | tensile_strength of the transparent films 2 and 3 is this range, generation | occurrence | production of the wrinkles in the transparent films 2 and 3 conveyed by the bonding rolls 51 and 52 is suppressed. In order to adjust the tension of the transparent films 2 and 3 to such a range, the diameter of the first suction rolls 61 and 62 is preferably 200 to 400 mm, and the holding angle of the transparent film is preferably 45 to 180 °. The force is appropriately adjusted according to the tension to be set, but is preferably 2 to 30 kPa.

(Bonding process)
In this step, the adhesive is applied by the above-described step on both surfaces of the polarizing film 1 that is continuously drawn out from the state wound in a roll shape, and the transparent film sent through the first suction rolls 61 and 62. Films 2 and 3 are laminated via an adhesive. 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.

  Examples of the material of the bonding rolls 51 and 52 include a metal roll and a rubber roll. One of the pair of bonding rolls 51 and 52 is preferably a metal roll and the other is a rubber roll. 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 pressing pressure between 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 0.7 to 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 roll 13 is conveyed while the laminate 4 is in close contact with the surface thereof, and the adhesive is polymerized and cured by the active energy ray irradiation devices 31 and 32 in the process. The diameter of the roll 13 is not particularly limited when the adhesive is polymerized and cured and the laminate 4 is sufficiently adhered. The roll 13 is rotationally driven at a rotational speed corresponding to the line speed, and when the rotational speed of the bonding rubber roll is 100, it is preferably 100.1 or more and 102.0 or less. Further, the roll 13 may act as a cooling roll for dissipating heat generated in the laminate 4 at the time of polymerization and curing by irradiation with active energy rays. 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. However, it is not limited to two times, and may be performed, for example, in three times.

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. Strength.

  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, it is preferable to set preferably such that the 10~5,000mJ / cm ^2.

  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 unwinding). 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.

<Production Method of Polarizing Plate (Second Embodiment)>
FIG. 4 is a schematic view showing a second embodiment of a production apparatus used in the method for producing a polarizing plate of the present invention. The manufacturing apparatus according to the second embodiment is different from the manufacturing apparatus according to the first embodiment in that corona discharge treatment apparatuses 91 and 92 are provided in front of the adhesive application apparatuses 11 and 12. The difference is that second suction rolls 71 and 72 and third suction rolls 81 and 82 are provided on the front and rear sides.

  The tension | tensile_strength of the transparent films 2 and 3 is adjusted with the 2nd suction rolls 71 and 72, and it can prevent that a wrinkle arises in the transparent films 2 and 3 at an adhesive agent coating process. By applying the adhesive to the transparent films 2 and 3 without wrinkles, it is possible to prevent uneven application of the adhesive. Moreover, wrinkle generation | occurrence | production of the transparent films 2 and 3 in a bonding process is controlled by controlling the tension | tensile_strength of the transparent films 2 and 3 in steps by the 2nd suction rolls 71 and 72 and the 1st suction rolls 61 and 62. It can prevent more reliably. In the present embodiment, the third suction rolls 81 and 82 are not necessarily provided. However, by providing the third suction rolls 81 and 82, the transparent films 2 and 3 can be formed before the corona discharge treatment. This is preferable in that the tension can be controlled. Hereinafter, a configuration different from the manufacturing apparatus shown in FIG. 1 will be described.

  The corona discharge treatment by the corona discharge treatment devices 91 and 92 is a treatment for activating the transparent films 2 and 3 disposed between the electrodes by discharging by applying a high voltage between the electrodes. The effect of the corona discharge treatment varies depending on the type of electrode, electrode interval, voltage, humidity, type of transparent film used, etc., for example, the electrode interval is set to 1 to 5 mm, and the moving speed is set to about 3 to 50 m / min. It is preferable to do this. After the corona discharge treatment, the adhesive is applied to the treated surfaces of the transparent films 2 and 3 by the adhesive application devices 11 and 12 as described above, and is bonded to the polarizing film. By performing the corona discharge treatment, the adhesion between the transparent films 2 and 3 and the adhesive can be increased, and as a result, the adhesion between the transparent films 2 and 3 and the polarizing film 1 can be increased.

  The configurations of the third suction rolls 81 and 82 and the second suction rolls 71 and 72 provided before and after the corona discharge treatment devices 91 and 92 are the same as the configurations of the first suction rolls 61 and 62 described above. Shall be. Moreover, it is preferable that the tension | tensile_strength of the transparent films 2 and 3 is adjusted to 200-1000 N / m with the 2nd suction rolls 71 and 72 and the 3rd suction rolls 81 and 82. FIG. In order to adjust the tension of the transparent films 2 and 3 to such a range, the diameters of the second suction rolls 71 and 72 and the third suction rolls 81 and 82 are the same as the first suction rolls 61 and 62. Is preferably 200 to 400 mm, and the holding angle of the transparent film is preferably in the range of 45 to 180 °, and the suction force is appropriately adjusted according to the tension to be set, but preferably 2 to 30 kPa.

  Moreover, in order to prevent generation | occurrence | production of wrinkles more reliably, the tension | tensile_strength of the transparent film of the area of the bonding rolls 51 and 52 and the 1st suction rolls 61 and 62 is I, the 1st suction rolls 61 and 62, and the 2nd. The tension of the transparent film in the section of the suction rolls 71 and 72 is II, and the tension of the transparent film in the section of the second suction rolls 71 and 72 and the third suction rolls 81 and 82 is III. It is preferable to adjust the size so that I ≦ II ≦ III.

  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 to be bonded to both sides of the polarizing film, a cycloolefin resin film “ZEONOR” (manufactured by ZEONOR) having a thickness of 23 μm and a polyethylene terephthalate film “140E25T” having a thickness of 25 μm (Mitsubishi Resin ( Co., Ltd.) was prepared.

  Next, an epoxy resin composition “KR series” (manufactured by ADEKA), which is an ultraviolet curable adhesive, on one side of the cycloolefin-based resin film “ZEONOR” and one side of the polyethylene terephthalate film “140E25T”. It applied using the adhesive agent coating apparatus (microchamber doctor: Fuji machine company make). At this time, the line speed of the transparent film in the adhesive application apparatus is 25 m / min, the gravure roll is rotated in the direction opposite to the conveying direction of the laminate, and the thickness of the adhesive layer on both transparent films is about 3.5 μm. It was.

  Next, the cycloolefin resin film “ZEONOR” and the polyethylene terephthalate film “140E25T” coated with an epoxy resin composition (ultraviolet curable adhesive) are adhered to the suction roll (first suction roll). Then, the film was conveyed at a line speed of 25 m / min, and both the transparent films were bonded to both surfaces of the polarizing film by a nip roll (bonding roll) via an epoxy resin composition (ultraviolet curable adhesive). At this time, the tensions of I, II, and III of each transparent film are as follows: “ZEONOR” is I: 230 N / m, II: 230 N / m, III: 260 N / m, “140E25T” is I: 380 N / M, II: 450 N / m, III: 530 N / m. The suction roll had a diameter of 300 mm, a holding angle of 90 °, and a suction force of 10 kPa.

  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 is performed by passing through the ultraviolet rays irradiated from one lamp with an electric energy of 120 W / cm, and then an electrodeless D bulb lamp (provided by Fusion, “Light Hammer 10”). The polarizing plate was produced by passing through the ultraviolet ray irradiated from the electric energy of one lamp (216 W / cm) to irradiate the second active energy ray.

  The one electrodeless D bulb lamp described above is a unit in which six units of electrodeless D bulb lamps are arranged in the width direction of the film and arranged in a row in the longitudinal direction of the film.

(Evaluation of polarizing plate)
When the presence or absence of wrinkles in the transparent film was visually evaluated at the position immediately before the bonding roll, the occurrence of wrinkles was not confirmed.

[Example 2]
As a transparent film to be bonded to both sides of the polarizing film, a cycloolefin resin film “ZEONOR” (made by Nippon Zeon Co., Ltd.) having a thickness of 25 μm and a triacetyl cellulose film “KC6UAW” (Konica Minolta) having a thickness of 60 μm are used. Opt Co., Ltd.) was prepared. The tension of each of the transparent films I, II and III is as follows: “ZEONOR” is I: 230 N / m, II: 230 N / m, III: 340 N / m, “KC6UAW” is I: 380 N / m, It was produced in the same manner as in Example 1 except that II: 530 N / m and III: 740 N / m.

(Evaluation of polarizing plate)
When the presence or absence of wrinkles in the transparent film was visually evaluated at the position immediately before the bonding roll, the occurrence of wrinkles was not confirmed.

[Comparative Example 1]
Without providing the second suction roll in front of the adhesive applicator and the first suction roll in front of the bonding roll, the third suction roll is a pair of rubber nip rolls, and a pair of rubber nip rolls A polarizing plate was produced in the same manner as in Example 1 except that the tension between the bonding rolls was 260 N / m for “ZEONOR” and 530 N / m for “140E25T”.

(Evaluation of polarizing plate)
When the presence or absence of wrinkles on the transparent film was visually evaluated at the position immediately before the bonding roll, the occurrence of wrinkles 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 device, 13 roll (cooling roll), 16, 17, 18, 31, 32 Active energy ray irradiation device, 19 Conveyance Nip roll, 20 take-up roll, 61, 62 first suction roll, 71, 72 second suction roll, 81, 82 third suction roll, 91, 92 corona discharge treatment apparatus, 101 inner cylinder, 102 outer cylinder .

Claims (5)

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 at a coating thickness of 0.1 to 10 μm on one side of the transparent film having a thickness of 5 to 60 μm ;
A laminating step of laminating the transparent film on one or both sides of the polarizing film via the adhesive ;
After the adhesive application step, the transparent film is provided with a conveyance step for conveying the transparent film to the bonding step via a first suction roll,
In the said conveyance process, the suction force of a 1st suction roll is 2-30 kPa, The manufacturing method of a polarizing plate. After pre-Symbol bonding step, the laminate of the transparent film stuck to the polarizing film, further comprises an active energy ray irradiation step of curing the adhesive by irradiation with active energy rays, to claim 1 The manufacturing method of the polarizing plate of description. Before the adhesive application step, further comprising a surface treatment step of performing a treatment to improve the adhesion to the surface of the transparent film to which the adhesive is applied,
The manufacturing method of the polarizing plate of Claim 1 or 2 which conveys the said transparent film to the said adhesive agent application process through a 2nd suction roll after the said surface treatment process. The manufacturing method of the polarizing plate of Claim 3 which conveys the said transparent film to the said surface treatment process via a 3rd suction roll. The tension of the transparent film conveyed to the bonding step is I, the tension of the transparent film in the section between the first suction roll and the second suction roll is II, the second suction roll and the third suction roll The manufacturing method of the polarizing plate of Claim 4 adjusted so that the magnitude | size of these tensions may become I <= II <= III, when the tension | tensile_strength of the said transparent film of a area is set to III.

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