JP5572197B2 - 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).

  However, as shown in FIGS. 5 (a) and (b), the sandwiching pressure of the laminate (polarizing film and transparent film) by the bonding rolls 51 and 52 is usually determined by the bearings at both ends of one bonding roll 51. Since it is performed by pressing with hydraulic pressure, pneumatic pressure, screws, etc. (arrow in FIG. 5 (b)), the vicinity of the center of the bonding roll 51 is bent, and the laminate (polarizing film and transparent film) is pressed unevenly. There was a case where it was done. When the pressure is applied unevenly, there are problems that bubbles are generated between the films in the obtained polarizing plate, and that the adhesion between the films is deteriorated. In addition, there is a problem that the flow of conveyance becomes worse and troubles in the manufacturing process are likely to occur. Such a phenomenon is a phenomenon that occurs when a high pressure needs to be applied to the laminate. When an active energy ray curable resin is used as an adhesive, the viscosity is higher than when other polyvinyl alcohol-based resins or the like are used as an adhesive. Therefore, it is necessary to apply a high pressure to the laminate.

  For this reason, in order to make it hard to produce the bending of the bonding roll at the time of a press, the roll which has a diameter larger than about 300 mm normally was used as a bonding roll conventionally. However, the larger the diameter of the bonding roll, the larger the contact area between the bonding roll and the laminate, so when the external force applied to the bonding roll is constant, the pressure per area applied to the laminate is It gets smaller. Therefore, when it is necessary to apply a high pressure to the laminate, it is desirable to make the diameter of the bonding roll as small as possible.

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

  The present invention provides a method for producing a polarizing plate and a polarizing plate capable of uniformly pressing a laminate (polarizing film and transparent film) constituting the polarizing plate even when a bonding roll having a relatively small diameter is used. An object is to provide an apparatus.

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,
An adhesive coating 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 in contact with the laminating roll in a state where a laminate formed by laminating one or both sides of the polarizing film via the adhesive is sandwiched between a pair of laminating rolls rotating in the transport direction. A pasting step of pasting the transparent film and the polarizing film by pressing at least one pasting roll in the direction of the other pasting roll with at least one pressing roll provided by
An active energy ray irradiation step of irradiating the laminate with an active energy ray to cure the adhesive; and
The diameter of the center part of the said press roll is a manufacturing method of a polarizing plate characterized by being larger than the diameter of the center part of the said bonding roll which touches this press roll.

  Each of the pair of bonding rolls is preferably driven independently. The pair of bonding rolls and the pressing roll are preferably flat rolls having a substantially uniform diameter.

In addition, the present invention is a polarizing plate manufacturing apparatus in which a transparent film is bonded to one side or both sides of a polarizing film,
An adhesive coating device for applying an active energy ray-curable adhesive on one side or both sides of the transparent film or the polarizing film;
A pair of the transparent film and the polarizing film are bonded together by sandwiching the transparent film while transporting a laminate in which the transparent film is laminated on one or both sides of the polarizing film via the adhesive. A bonding roll;
In order to press at least one bonding roll in the direction of the other bonding roll among the pair of bonding rolls, at least one pressing roll provided in contact with the bonding roll; and
An active energy ray irradiating device for irradiating the laminate with an active energy ray to cure the adhesive;
The diameter of the center part of the said press roll is also related with the manufacturing apparatus of a polarizing plate characterized by being larger than the diameter of the center part of the said bonding roll which touches this press roll.

  ADVANTAGE OF THE INVENTION According to this invention, even when the bonding roll of a comparatively small diameter is used, the manufacturing method and polarizing plate of a polarizing plate which can pressurize uniformly the laminated body (polarizing film and transparent film) which comprises a polarizing plate. The manufacturing apparatus can be provided.

  In addition, according to the present invention, it is possible to obtain a polarizing plate in which air bubbles are generated between the films or adhesion between the films is suppressed. In addition, the occurrence of troubles in the manufacturing process due to the deterioration in the flow of conveyance is also suppressed.

It is a schematic side view which shows one Embodiment of the manufacturing apparatus of the polarizing plate concerning this invention. It is a schematic side view which shows one Embodiment of the bonding roll and press roll used for this invention. It is a schematic front view about one Embodiment of the bonding roll and press roll shown in FIG. It is a schematic side view which shows another embodiment of the manufacturing apparatus of the polarizing plate concerning this invention. It is the schematic for demonstrating the manufacturing method of the conventional polarizing plate.

(Polarizing film)
Specifically, the polarizing film used in the polarizing plate of the present invention is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol 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 Nippon Gosei) has a thickness of 75 μm (vinylon VF-PS # 6000, manufactured by Kuraray, vinylon VF-PE #). (6000, made by Kuraray)
0 μm and the like.

  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 a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing an aqueous 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. 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. 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.

  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, and polymethyl methacrylate (PMMA). Examples thereof include film materials that have been widely used in the art, such as acrylic resins and olefin resins such as polypropylene.

  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 modification treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment is applied to the surface to be bonded to the polarizing film. Is preferably performed. 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), KC4UYW (manufactured by Konica Minolta Opto), KC6UAW (Konica Minolta Opto) Etc.) can be used preferably.

  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 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 modification treatment may be performed.

  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. Etc.) can be adopted. Examples of the active energy ray-curable adhesive include an adhesive made of an acrylic resin composition such as acrylamide, acrylate, urethane acrylate, and epoxy acrylate.

  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 the form of removing one or more hydrogen atoms in (CH ₂ ) _m in the above formula is bonded to another chemical structure can be an alicyclic epoxy resin. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (m = 3 in the above formula) or an oxabicycloheptane ring (m = 4 in the above formula) 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):

(Wherein 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):

(Wherein 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):

(Wherein R ⁹ and R ¹⁰ 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):

(Wherein, 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):

(In the formula, R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (J) Diepoxytricyclodecanes represented by the following formula (X):

(In the formula, R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).
Among the alicyclic epoxy resins exemplified above, the following alicyclic epoxy resins are commercially available or 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-CH ₃ , p = 4 compound]
(F) Etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the formula (V), R ⁹ = R ¹⁰ = H, r = 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 polarizing plate production apparatus of the present invention.

  In the polarizing plate manufacturing apparatus 30 shown in FIG. 1, 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 and the polarizing film 1 are bonded. Bonding rolls (nip rolls) 51 and 52 for obtaining the laminate 4, the roll 13 for bringing the transparent films 2 and 3 and the polarizing film 1 into close contact with each other in the laminate 4, and the outer peripheral surface of the roll 13 First active energy beam irradiation devices 14 and 15 installed at opposite positions, second and subsequent active energy beam irradiation devices 16 to 18 installed further downstream in the transport direction, and a transport nip roll 19 Are provided in order along the transport direction.

  Furthermore, as shown in FIG.1, FIG2 and FIG.3, the press rolls 61 and 62 are provided in contact with the bonding rolls 51 and 52, respectively. Here, the diameter of the center part of the press rolls 61 and 62 is larger than the diameter of the center part of the bonding rolls 51 and 52 which contact | connects it.

  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 an adhesive application device 11 or 12 (adhesive coating). Construction 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 sandwiched between a pair of bonding rolls 51, 52 rotating in the direction, the pressing film 61, 62 presses at least one bonding roll in the direction of the other bonding roll, so that the polarizing film 1 and The transparent films 2 and 3 are bonded together, and the laminated body 4 is formed (bonding process).

  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 14, 15 toward the outer peripheral surface of the roll 13, and bonded. The agent is polymerized and cured (active energy ray irradiation step).

  Note that the second and subsequent active energy ray irradiation devices 16 to 18 arranged on the downstream side in the transport direction are devices for completely polymerizing and curing the adhesive, and can be added or omitted as necessary. 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 coating 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, first, the transparent films 11 and 12 coated with the adhesive in the above-described step are laminated on both surfaces of the polarizing film 1 continuously drawn out from the rolled state via the adhesive. The

  In a state where the laminate is sandwiched between a pair of bonding rolls 51 and 52 that rotate in the transport direction, the bearing member 61a of the pressing roll 61 is moved in the direction of the arrow (of the bonding roll 52) as shown in FIG. The polarizing film 1 and the transparent films 2 and 3 are bonded together by pressing the entire bonding roll 51 in the direction of the arrow with the entire pressing roll, and the laminate 4 is formed. At this time, the polarizing film is so formed that the conveying direction of the polarizing film forms an angle within a range of ± 3 °, more preferably within a range of ± 1 ° with respect to a plane perpendicular to the pressing direction of the bonding roll. Is conveyed between the bonding rolls. Particularly preferably, the polarizing film is conveyed between the bonding rolls so that the conveying direction of the polarizing film overlaps with a surface perpendicular to the pressing direction of the bonding roll. 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. Here, since the diameter of the center part of the press roll 61 is larger than the diameter of the center part of the bonding roll 51 which touches it, even when the bearing member 61a is pressed, it is hard to produce the press roll 61, and the bonding roll 51 Can be pressed with uniform pressure. Thereby, the laminated body (polarizing film 1 and transparent films 2 and 3) which comprises a polarizing plate can be pressurized uniformly.

  Usually, a rotational driving force is applied to the pressing roll itself and the bonding roll also rotates. However, in this embodiment, the pair of bonding rolls are driven independently of each other, so that the curl can be adjusted. .

  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.

  Moreover, as shown in FIG. 4, the press roll 61 may be provided only in one of a pair of bonding rolls 51 and 52. As shown in FIG.

  The diameter of the central part of the bonding roll in contact with the pressing roll is preferably 30 mm or more and less than 300 mm, and more preferably 50 to 270 mm. By using a bonding roll having a relatively small diameter in this way, it becomes difficult for air to be caught between the polarizing film and the transparent film, and the adjustment range of the thickness of the adhesive for preventing bubbles from being caught. Therefore, it is possible to easily manufacture a polarizing plate in which bubbles are not easily generated between the polarizing film and the transparent film. In particular, when the diameter of the bonding roll is 300 mm or more, air is easily caught between the polarizing film and the transparent film. Moreover, when the diameter of a bonding roll is less than 50 mm, there exists a malfunction that intensity | strength falls. In addition, although the bonding roll is comprised at least by a pair of roll, the diameter of the roll which became the pair may mutually be the same, and may differ. The width of the bonding roll is preferably 300 to 3000 mm.

Moreover, it is preferable that the diameter of the center part of the said press roll is 200-500 mm. Is less than 200mm, when pressing the lamination rolls by applying an external force to the bearing member of the pressure roll, tends to occur bending the pressing roll, it may not be possible to press the lamination rolls in a uniform pressure . Moreover, when larger than 500 mm, there exists a problem in the point that an installation becomes large.

  Each of the pair of bonding rolls 51 and 52 and the pressing rolls 61 and 62 is preferably a flat roll having a substantially uniform diameter. However, one of the pair of bonding rolls 51 and 52 or one of the pressing rolls 61 and 62 may be a roll (crown roll) having a tapered outer shape whose diameter decreases from the center to the end. .

  When one of the pair of bonding rolls 51 and 52 or one of the pressing rolls 61 and 62 is a crown roll, the ratio of the difference between the diameter of the center portion of the crown roll and the diameter of the end portion is the length of the crown roll. It is preferably about 0.0020 to 0.0500% with respect to (the length in the axial direction). Usually, in such a ratio range, the shape of the crown roll can be designed so that the distance between the crown roll and the flat roll is uniform in a state where pressing is performed in the bonding step.

  Although the pressure applied to a laminated body by the bonding rolls 51 and 52 is not specifically limited, When using a metal roll and a rubber roll, the instantaneous pressure in a Fuji film two sheet type press case (for ultra-low pressure) is The pressure is preferably 0.5 to 3.0 MPa, more preferably 1.0 to 2.5 MPa. In this invention, the external force of the press with respect to a press roll is normally applied with respect to the bearing member of the both ends of a press roll.

  Examples of the material for the bonding roll and the pressing roll include metal and rubber. One of the pair of bonding rolls is preferably made of metal and the other is made of rubber. Moreover, the arrangement | positioning of a bonding roll and a press roll is not specifically limited, You may arrange | position so that an arbitrary angle may be made mutually. That is, the pressing roll is not limited to the upper and lower sides of the bonding loin, and may be arranged at a horizontal or other angle.

  In the conventional bonding roll, the upper bonding roll to be pressed is usually made of rubber, and the lower bonding roll is made of metal. This is because the lower laminating roll is made of metal, and the lower laminating roll is not deformed when pressed because the lower laminating roll is made of metal because the drive motor is attached to the lower laminating roll. It is because it is easy to maintain the peripheral speed of a bonding roll constant. However, in this case, in order to facilitate the curl adjustment of the positive curl described later, in the present invention, the pressed (upper) bonding roll is made of metal, and the other (lower) bonding roll is It is preferably made of rubber.

  Moreover, it is preferable that the press roll provided in contact with metal bonding rolls is rubber. The pressing roll provided in contact with the rubber bonding roll may be made of metal or rubber. When the bonding roll and the pressing roll that are in contact with each other are both made of metal, it is difficult to use them continuously because the rolls are easily damaged by use. On the other hand, there is no problem in particular when both the bonding roll and the pressing roll in contact with each other are made of rubber.

  Various known materials can be used as the base material of the metal roll, but stainless steel is preferable, and SUS304 (stainless steel containing 18% Cr and 8% Ni) is more preferable. The surface of the metal roll is preferably subjected to chrome plating.

  The material of the rubber roll is not particularly limited, and examples thereof include NBR (nitrile rubber), Titan, urethane, silicon, EPDM (ethylene-propylene-diene rubber), and preferably NBR, Titan, and urethane. 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.

  A pair of bonding rolls may have a difference in peripheral speed between one bonding roll and the other bonding roll. For example, the peripheral speed of the bonding roll (1st bonding roll) installed in the surface side bonded to the liquid crystal panel of the laminated body 4 is the opposite side of the bonding roll (2nd bonding roll). It is preferably faster than the peripheral speed. Thereby, it is possible to give the obtained polarizing plate a curl (positive curl) in which the surface bonded to the liquid crystal panel becomes convex and the opposite surface becomes concave. When the obtained polarizing plate is curled (reverse curl) so that the surface to be bonded to the liquid crystal panel is concave and the opposite surface is convex, the polarizing plate is bonded to the liquid crystal cell. When it does, it will become easy to produce malfunctions, such as a bubble biting in a center part. In this case, it is preferable to use a metal roll as the first laminating roll and a rubber roll as the second laminating roll.

  Furthermore, when the peripheral speed of the 2nd bonding roll is set to 1, it is more preferable that the ratio of the peripheral speed of the 1st bonding roll is 1.0050-1.0200. When the peripheral speed of the first laminating roll is faster than this range, the curl amount of the positive curl becomes too large, causing problems such as entrapment of bubbles at the end when laminating the polarizing plate to the liquid crystal cell. This is because, when placed in a harsh environment, the positive curl is further promoted and the end of the polarizing plate may be peeled off from the liquid crystal cell.

The roll 13 constitutes a convex curved surface whose outer peripheral surface is mirror-finished, and the laminate 4 is conveyed while closely contacting the surface, and the adhesive is polymerized and cured by the active energy ray irradiation devices 14 and 15 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 laminated body 4 in which the adhesive is in an uncured state is preferably irradiated with active energy rays so that the cumulative amount of light while passing through the roll 13 is 10 mJ / cm ² or more. The roll 13 may be driven or rotated according to the movement of the line of the laminate 4 or may be fixed so that the laminate 4 slides on the surface. 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.

(Active energy ray irradiation process)
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.

Although the light irradiation intensity | strength to an active energy ray hardening-type adhesive agent is determined for every composition of an adhesive agent and it does not specifically limit, It is preferable that it is 10-5000 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 50
If it exceeds 00 mW / cm ² , yellowing of the epoxy resin composition, which is a constituent material of the adhesive, or deterioration of the polarizing film may occur due to heat radiated from the lamp and heat generated during polymerization of the composition. . 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.

The irradiation time of the active energy ray to the active energy ray-curable adhesive is controlled for each composition to be cured and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 mJ / cm ² or more, it is preferable to set preferably such that the 10~5,000mJ / cm ^2. When the integrated light quantity to the adhesive is less than 10 mJ / cm ² , the generation of active species derived from the initiator is not sufficient, 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 the present invention, the adhesive is polymerized and cured by irradiating the laminate with active energy rays, but polymerization curing by heating may be used in combination.

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. In addition, the irradiation intensity of ultraviolet rays is preferably 10 mW / cm ² or more.

Moreover, when the integrated light quantity of the active energy rays by the active energy ray irradiation devices 14 and 15 is insufficient, the active energy ray irradiation devices 16 to 18 after the second are further provided to irradiate the active energy rays, and the laminated body It is preferable to accelerate the curing of the adhesive No. 4. Integrated light intensity in these whole process is 10 mJ / cm ² or more, preferably it is preferably set so that 10~5,000mJ / cm ^2. As described above, in the step of irradiating the active energy ray, the irradiation of the active energy ray is preferably performed in a plurality of times.

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, etc. 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 up 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 “Vinylon VF-PS # 7500 (manufactured by Kuraray)” 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 tension of the film so that the original film did not loosen. 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, a cycloolefin-based resin film “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 50 μm and a triacetyl cellulose film “KC8UX2MW” (manufactured by Konica Minolta) having a thickness of 80 μm were prepared.

  Next, an epoxy resin composition “KR series” (made by ADEKA, including a cationic polymerization initiator) is provided on one side of the cycloolefin resin film “ZEONOR” having a thickness of 50 μm. ) Was applied using an adhesive coating device (Microchamber Doctor: manufactured by Fuji Machine Co., Ltd.). Also, an epoxy resin composition “KR series” (made by ADEKA, including a cationic polymerization initiator), which is an ultraviolet curable adhesive, is the same adhesive on one side of the 80 μm thick triacetyl cellulose film “KC8UX2MW”. Coating was performed using a coating apparatus. At this time, the line speed of the polarizing film laminate in the adhesive coating apparatus was set to 25 m / min, the gravure roll was rotated in the direction opposite to the conveying direction of the laminated material, and the 50 μm thick cycloolefin resin film “ZEONOR” The thickness of the adhesive layer on “)” was about 3.5 μm, and the thickness of the adhesive layer on the triacetyl cellulose film “KC8UX2MW” having a thickness of 80 μm was about 3.5 μm.

  Next, the cycloolefin resin film “ZEONOR” having a thickness of 50 μm and the triacetyl cellulose film “KC8UX2MW” having a thickness of 80 μm are applied to both sides of the polarizing film with the epoxy resin composition (ultraviolet curable type). It was bonded via an adhesive). For bonding, as shown in FIG. 1, a pair of bonding rolls with a diameter of 250 mm and a pair of pressing rolls with a diameter of 400 mm provided so as to be in contact with each bonding roll, the average of the bonding rolls Nipping was performed so that the nip pressure (pressure applied to the laminate by the bonding roll) was 1.53 MPa.

  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 in close contact with the cooling roll, and continues in series in the width direction of the film. The first active energy ray irradiation process is performed by passing through the ultraviolet light irradiated from two metal halide lamps (manufactured by GS-YUSASA, one power of 120 W / cm), and then the width of the film 6 electrodeless D bulb lamps arranged in series in the direction (Fusion's “Light Hammer 10”, power 216 W / cm per unit length of one lamp) are allowed to pass through the ultraviolet rays. Then, a second active energy ray irradiation step was performed to produce a polarizing plate.

  When passing through the metal halide lamp, the 80 μm thick triacetylcellulose 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 the 50 μm thick cycloolefin resin. Ultraviolet rays were irradiated from the side of the film “ZEONOR”. Thereby, deterioration of the adhesive agent and polarizing film by the influence of the heat | fever in a 1st active energy ray irradiation process is suppressed.

(Evaluation of nip pressure distribution of bonding roll and bubbles of polarizing plate)
When the nip pressure of the bonding roll of Example 1 was measured using a Fujifilm two-sheet type prescale (for ultra-low pressure), the distribution of the nip pressure was almost uniform in the width direction. Moreover, when the produced polarizing plate was evaluated, the bubble was not observed. The results are shown in Table 1.

[Example 2]
In this example, a polarizing plate was produced in the same manner as in Example 1 except that the nip was performed so that the average nip pressure of the bonding roll was 2.25 MPa.
(Evaluation of nip pressure distribution of bonding roll and bubbles of polarizing plate)
When the nip pressure of the bonding roll of Example 2 was measured using a Fujifilm two-sheet type prescale (for ultra-low pressure), the distribution of the nip pressure was almost uniform in the width direction. Moreover, when the produced polarizing plate was evaluated, the bubble was not observed. The results are shown in Table 1.

[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that only a pair of bonding rolls was used for nipping so that the average nip pressure was 1.13 MPa.
(Evaluation of nip pressure distribution of bonding roll and bubbles of polarizing plate)
When the nip pressure of the bonding roll of Comparative Example 1 was measured using a Fujifilm two-sheet type prescale (for ultra-low pressure), the distribution of the nip pressure in the width direction was large. Moreover, when the produced polarizing plate was evaluated, the bubble was observed. The results are shown in Table 1.

  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 roll (cooling roll), 14, 15, 16, 17, 18 Active energy ray irradiation apparatus, 19 Transport nip roll, 20 take-up roll, 51, 52 laminating roll, 61, 62 pressing roll, 61a bearing member.

Claims (4)

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 coating step of applying an active energy ray-curable adhesive having a viscosity of 1000 mPa · s or less to one side or both sides of the transparent film or the polarizing film;
The transparent film is in contact with the laminating roll in a state where a laminate formed by laminating one or both sides of the polarizing film via the adhesive is sandwiched between a pair of laminating rolls rotating in the transport direction. A pasting step of pasting the transparent film and the polarizing film by pressing at least one pasting roll in the direction of the other pasting roll with at least one pressing roll provided by
An active energy ray irradiating step of curing the adhesive by irradiating the laminated body that has undergone the bonding step with an active energy ray;
The diameter of the central part of the pressing roll is larger than the diameter of the central part of the bonding roll in contact with the pressing roll,
A pair of the bonding rolls are independently driven,
The peripheral speed of the bonding roll arranged on the surface side bonded to the liquid crystal panel of the laminate is faster than the peripheral speed of the bonding roll on the opposite side,
When the peripheral speed of the pasting roll on the opposite side is 1, the ratio of the peripheral speed of one of the pasting rolls is 1.0050-1.200,
The bonding roll to be pressed is made of metal, and the other bonding roll is made of rubber.
The method for producing a polarizing plate, wherein the pressing roll provided in contact with the metal bonding roll is made of rubber.   The said pair of bonding roll and the said press roll are the manufacturing methods of the polarizing plate of Claim 1 which is a flat roll with a substantially uniform diameter. The method for producing a polarizing plate according to claim 1, wherein the polarizing film is continuously drawn, and the transparent film is continuously drawn. A polarizing plate manufacturing apparatus in which a transparent film is bonded to one side or both sides of a polarizing film,
An adhesive coating device for applying an active energy ray-curable adhesive having a viscosity of 1000 mPa · s or less to one side or both sides of the transparent film or the polarizing film;
A pair of the transparent film and the polarizing film are bonded together by sandwiching the transparent film while transporting a laminate in which the transparent film is laminated on one or both sides of the polarizing film via the adhesive. A bonding roll;
In order to press at least one bonding roll in the direction of the other bonding roll among the pair of bonding rolls, at least one pressing roll provided in contact with the bonding roll; and
An active energy ray irradiating device for curing the adhesive by irradiating active energy rays to the laminate that has passed through the bonding roll ;
The diameter of the central part of the pressing roll is larger than the diameter of the central part of the bonding roll in contact with the pressing roll,
A pair of the bonding rolls are independently driven,
The peripheral speed of the bonding roll arranged on the surface side bonded to the liquid crystal panel of the laminate is faster than the peripheral speed of the bonding roll on the opposite side,
When the peripheral speed of the pasting roll on the opposite side is 1, the ratio of the peripheral speed of one of the pasting rolls is 1.0050-1.200,
The bonding roll to be pressed is made of metal, and the other bonding roll is made of rubber.
The apparatus for producing a polarizing plate, wherein the pressing roll provided in contact with the metal bonding roll is made of rubber.

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