KR20140088536A - Method for manufacturing polarizer - Google Patents

Abstract

The present invention relates to a laminate (4) comprising an adhesive coating process for applying an active energy ray-curable adhesive and a transparent film (2, 3) laminated on one or both sides of the polarizing film (1) (2, 3) and the polarizing film (2, 3) by pressing at least one of the joining rolls in the direction of the other joining roll in a state sandwiched between a pair of joining rolls (51, 52) (1), and an active energy ray irradiation step of curing the adhesive by irradiating an active energy ray to the laminate (4), wherein at least one of the pair of bonding rolls (51, 52) One side is a double vent roll 51 having a double structure composed of a central portion 51a and a roll portion 51b having an outer peripheral surface. Since the central portion 51a and the roll portion 51b are partially joined to each other , When the center shaft 51a is bent Also provides a method for producing a polarizing plate, it characterized in that the outer peripheral surface deflection does not occur in the roll (51b).

Description

METHOD FOR MANUFACTURING POLARIZER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a polarizing plate useful as one of optical components constituting a liquid crystal display or the like.

The polarizing film is widely used as a polyvinyl alcohol-based resin film in which a dichromatic dye is adsorbed and oriented, and an iodine-based polarizing film using iodine as a dichromatic dye or a dye-based polarizing film using a dichromatic direct dye as a dichromatic dye Film and the like are known. These polarizing films are usually polarized by bonding a transparent film such as a triacetylcellulose film to one or both sides thereof with an adhesive.

As a method of laminating a transparent film on one side or both sides of a polarizing film, an active energy ray-curable resin is applied to the surface of the transparent film in advance, and then the polarizing film and the transparent film are sandwiched between a pair of nip rolls (Japanese Patent Application Laid-Open No. 2004-245925, Patent Document 2: Japanese Patent Application Laid-Open No. 2009-134190, Patent Document 3: Japanese Patent Application Laid- Japanese Patent Application Laid-Open No. 11-95560).

4 (a) and 4 (b), the pressure of the laminate (polarizing film and transparent film) by the bonding rollers 51 and 52 is usually set at a constant value on both ends of one of the bonding rolls 51 (The arrow of Fig. 4 (b)), the vicinity of the center of the bonding roll 51 is warped, and the laminate (polarizing film and transparent film) is unevenly pressed . When the film is unevenly pressed, bubbles are generated between the films in the obtained polarizing plate, and the adhesion between the films is deteriorated. In addition, there is also a problem that the flow of the conveyance is deteriorated and troubles in the manufacturing process are liable to occur. This phenomenon also occurs when it is necessary to apply a high pressure to the laminate. When the active energy ray-curable resin is used as an adhesive, it is necessary to apply a high pressure to the laminate because the viscosity is high as compared with the case where another polyvinyl alcohol resin or the like is used as an adhesive.

Japanese Patent Application Laid-Open No. 2004-245925 Japanese Patent Application Laid-Open No. 2009-134190 Japanese Patent Laid-Open No. 11-95560

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method of manufacturing a polarizing plate capable of uniformly pressing a laminate (polarizing film and transparent film) constituting a polarizing plate and an apparatus for producing a polarizing plate.

The present invention is a method for producing a polarizing plate in which a transparent film is bonded to one or both surfaces of a polarizing film,

An adhesive applying step of applying an active energy ray-curable adhesive to one surface of the transparent film or one surface or both surfaces of the polarizing film;

The laminated body in which the transparent film is laminated on one side or both sides of the polarizing film through the adhesive is sandwiched between a pair of bonding rolls which are rotated in the carrying direction so that at least one of the bonding rolls A joining step of joining the transparent film and the polarizing film by pressing in the roll direction,

And an active energy beam irradiation step of curing the adhesive by irradiating an active energy ray to the laminate,

Wherein at least one of the pair of bonding rolls is a double vent roll having a double structure composed of a roll portion having a central axis and an outer peripheral face, and the central axis and the roll portion are only partially bonded, Is not generated on the outer circumferential surface of the roll portion.

It is preferable that the external force of the pressing is applied to the bearing member provided at both ends of the central shaft.

Further, the present invention is an apparatus for producing a polarizing plate comprising a polarizing film and a transparent film bonded to one or both sides of the polarizing film,

An adhesive applicator for applying an active energy ray-curable adhesive to one surface of the transparent film or one surface or both surfaces of the polarizing film,

A pair of bonding rolls for bonding the transparent film and the polarizing film by pressing and pressing the laminated body wherein the transparent film is laminated on one side or both sides of the polarizing film through the adhesive,

And an active energy ray irradiating device for irradiating an active energy ray to the laminate to cure the adhesive,

Wherein at least one of the pair of bonding rolls is a double vent roll having a double structure composed of a roll portion having a central axis and an outer peripheral face, and the central axis and the roll portion are only partially bonded, And the outer peripheral surface of the roll portion is not warped even when the polarizer is formed.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a polarizing plate and an apparatus for producing a polarizing plate that can uniformly press laminate (polarizing film and transparent film) constituting a polarizing plate.

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

1 is a schematic side view showing an embodiment of an apparatus for producing a polarizing plate according to the present invention.
2 is a schematic cross-sectional view showing one embodiment of a bonding roll used in the present invention.
3 is a schematic cross-sectional view showing another embodiment of the bonding roll used in the present invention.
4 is a schematic view for explaining a conventional method of manufacturing a polarizing plate.

(Polarizing film)

Specifically, the polarizing film used in the polarizing plate of the present invention is a monoaxially stretched polyvinyl alcohol-based resin film in which a dichromatic dye is adsorbed and oriented. The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetic acid-based resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith (for example, ethylene-vinyl acetate copolymer). Other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The degree of saponification of the polyvinyl alcohol-based resin is 85 mol% or more, preferably 90 mol% or more, and 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-based resins may be modified, and for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, or the like modified with aldehydes may be used.

Such a film of a polyvinyl alcohol-based resin is used as a original film of a polarizing film. The method of forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known appropriate method. The thickness of the original film containing the polyvinyl alcohol-based resin is not particularly limited, but is, for example, about 10 to 150 mu m. Usually, it is supplied in a roll form and has a thickness in the range of 20 to 100 mu m, preferably 30 to 80 mu m, and an industrially practical width of 500 to 6000 mm. It may also be a polyester film such as an olefin film or a PET film as a substrate and a polyvinyl alcohol resin applied to both sides or one side thereof.

(Vinylon VF-PS # 7500, manufactured by Kuraray Co., Ltd.) and "OPL film M-7500, manufactured by NIPPON GOSEI Co., Ltd." 6000, manufactured by Kuraray Co., Ltd., Vinylon VF-PE # 6000 manufactured by Kuraray Co., Ltd. (both disc thicknesses of 60 占 퐉), Vinylon VF-PE # 5000, Kuraray Co., VF-PE # 3000, manufactured by Kuraray Co., Ltd. (thickness of the disc is 30 mu m).

The polarizing film is usually formed by a process of dyeing a polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye (dyeing process), a process of treating a polyvinyl alcohol resin film adsorbed with a dichroic dye with an aqueous solution of boric acid (A boric acid treatment step), and a step of washing with water after the treatment with the aqueous solution of boric acid (a water washing step).

In producing the polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched. This uniaxial stretching may be performed before the dyeing process, during the dyeing process, or after the dyeing process. In the case of performing uniaxial stretching 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, it is also possible to perform uniaxial stretching in these plural steps.

The uniaxial stretching may be uniaxially stretched between different rolls of the main yarn, or uniaxially stretched by using a heat roll. In addition, it may be dry stretching in which stretching is performed in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen with a solvent. The stretching magnification is usually about 3 to 8 times.

The dyeing by the dichroic dye of the polyvinyl alcohol-based resin film in the dyeing treatment step is carried out, for example, by immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, for example, iodine, a dichroic dye and the like are used. The dichroic dyes include, for example, Si. children. Dichroic direct dyes including disazo compounds such as C. I. DIRECT RED 39, dichromatic direct dyes including compounds such as trisazo, tetrakisazo, and the like. The polyvinyl alcohol-based resin film is preferably subjected to immersion treatment with water before the dyeing treatment.

When iodine is used as the dichroism dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally 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 dichroism dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 占 폚, and the immersion time (dyeing time) for 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 in which a polyvinyl alcohol-based resin film is dipped in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually water, and 100 parts by weight of 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^-3 to 1 part by weight, particularly preferably 1 × 10 ^-3 to 1 × 10 ^{- 2} are parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. When a dichroic dye is used as the dichroism dye, the dye aqueous solution used for dyeing usually has a temperature of 20 to 80 캜, and the dipping time (dyeing time) for the aqueous solution is usually 10 to 1,800 seconds.

The boric acid treatment step is carried out by immersing a polyvinyl alcohol-based resin film stained with a dichroic dye in an aqueous solution containing boric acid. 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 above-described dyeing process, it is preferable that the boric acid-containing aqueous solution used in the boric acid treatment step 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 immersing time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 40 占 폚 or higher, preferably 50 to 85 占 폚, and more preferably 55 to 80 占 폚.

In the subsequent water washing treatment step, the polyvinyl alcohol resin film after the boric acid treatment is subjected to water washing treatment, for example, by immersion in water. The temperature of water in the water washing treatment is usually 4 to 40 占 폚, and the immersion time is usually 1 to 120 seconds. During or before the rinsing treatment, the film may be sprayed with water in a spray form, or water may be ejected from the slit-shaped spray section to strongly contact the film. After the washing treatment, the drying treatment is usually carried out to obtain a polarizing film. In the previous stage of the drying treatment, treatment such as spraying water with an air knife or the like or absorption of water on the surface by an absorbing roll may be appropriately performed. The drying treatment is preferably carried out using a hot-air dryer, a far-infrared heater, or the like. The temperature of the drying treatment is usually 30 to 100 占 폚, preferably 50 to 90 占 폚. The drying treatment time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

Thus, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment and washing treatment to obtain a polarizing film. The thickness of the polarizing film is usually in the range of 3 to 50 mu m.

In addition, not limited to the above method, a film having a polarizing function manufactured by a separate method is also employed as the polarizing film.

(Transparent film)

In the present invention, a transparent film is bonded to one side or both sides of the above-mentioned polarizing film. When a transparent film is bonded to both sides of a polarizing film, each transparent film may be the same or may be a different kind of film.

Examples of the material constituting the transparent film include a resin such as a cycloolefin resin, a cellulose acetate resin, a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, a polycarbonate resin, Acrylate resins such as acrylate (PMMA) and the like, and olefin resins such as polypropylene and the like, which are conventionally widely used in the field.

The cycloolefin-based resin is a thermoplastic resin (also referred to as a thermoplastic cycloolefin-based resin) having a unit of a monomer containing a cyclic olefin (cycloolefin), such as norbornene or a polycyclic norbornene monomer. The cycloolefin resin may be a hydrogenated product of a ring-opening polymer of the cycloolefin or a ring-opening copolymer using two or more cycloolefins, or an addition polymer with a cycloolefin, a chain olefin, or an aromatic compound having a vinyl group. It is also effective that a polar group is introduced.

When a copolymer of a cycloolefin and an aromatic compound having a chain or olefin and / or a vinyl group is used, examples of the chain olefin include ethylene and propylene. Examples of the aromatic compound having a vinyl group include styrene, Substituted styrene, and the like. In such a copolymer, the unit of the monomer containing the cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). Especially when a terpolymer of a cycloolefin, a chain olefin and an aromatic compound having a vinyl group is used, the unit of the monomer containing the cycloolefin can be a relatively small amount as described above. In such a terpolymer, the unit of the monomer containing a chain olefin is usually 5 to 80 mol%, and the unit of the monomer containing an aromatic compound having a vinyl group is usually 5 to 80 mol%.

Examples of the cycloolefin resin include commercially available products such as Topas (manufactured by Ticona), Aton (manufactured by JSR Corporation), Zeonor (manufactured by Nippon Zeon Co., Ltd.) ZEONEX (manufactured by Nippon Zeon Co., Ltd.), APEL (manufactured by Mitsui Chemicals, Inc.), and OXIS (manufactured by Okura Corporation) can be preferably used. When the cycloolefin resin is formed into a film, known methods such as a solvent casting method and a melt extrusion method are suitably used. Further, a preformed cycloolefin such as, for example, Essen (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonor film (manufactured by Optesis) A commercially available product of a film made of a resin can also be used.

The cycloolefin-based resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be imparted to the cycloolefin-based resin film. The stretching is usually carried out while unwinding the film roll, and is stretched by a heating furnace in the direction of advancement of the roll (longitudinal direction of the film), in the direction perpendicular to the progressing direction (width direction of the film), or both. The temperature of the heating furnace is usually in the range of the glass transition temperature + 100 deg. C in the vicinity of the glass transition temperature of the cycloolefin-based resin. The magnification of the stretching is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

When the cycloolefin-based resin film is in the roll-wound state, since the films tends to adhere to each other and blockiness tends to occur, roll-winding is usually carried out after the protective film is bonded. Since the cycloolefin-based resin film generally has poor surface activity, the surface to be bonded to the polarizing film is subjected to surface modification treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, frame (flame) treatment and saponification treatment . Among them, a plasma treatment, particularly an atmospheric pressure plasma treatment and a corona treatment, which can be carried out relatively easily, is preferable.

As the cellulose acetate based resin, a cellulose ester partially or completely esterified product includes, for example, cellulose acetate ester, propionic ester, butyric acid ester, mixed ester thereof and the like. More specifically, a triacetylcellulose film, a diacetylcellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film and the like can be given. Examples of such a cellulose ester based resin film include commercially available products such as Fuji Tack TD80 (manufactured by Fuji Film), Fuji Tack TD80UF (manufactured by Fuji Film), Fuji Tack TD80UZ (manufactured by Fuji Film Co., Ltd.) , KC8UYW (manufactured by Konica Minolta Opto), KC8UY (manufactured by Konica Minolta Opto), Fujitack TD60UL (manufactured by Fuji Film), KC4UYW (manufactured by Konica Minolta Opto), KC6UAW KC2UAW (manufactured by Konica Minolta Opto Co., Ltd.), and the like can be preferably used.

Also, as the transparent film, a cellulose acetate resin film imparted with a retardation property is also preferably used. Examples of commercial products of the cellulose acetate based resin film to which such retardation properties are imparted include WV BZ 438 (manufactured by Fuji Film), KC4FR-1 (manufactured by Konica Minolta Opto Co., Ltd.), KC4CR-1 (Konica Minolta Opto Co., , KC4AR-1 (manufactured by Konica Minolta Opto), and the like. Acetate cellulose is also referred to as acetylcellulose or cellulose acetate.

These cellulose acetate resin films are easily absorbed, and the water content of the polarizer sometimes affects the end sagging of the polarizer. The moisture content at the time of production of the polarizing plate is preferably as close as possible to the storage environment of the polarizing plate, for example, the equilibrium moisture content in a production line of a clean room or a storage room of a winding roll, and depends on the composition of the laminated film. , And more preferably from 2.5% to 3.0%. The numerical value of the moisture content of the polarizing plate was measured by a dry weight method, and the 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 small, but if it is too thin, the strength is lowered and the workability is lowered. On the other hand, if the thickness is too large, the transparency may deteriorate or the curing time required after the lamination may be prolonged. Therefore, the suitable thickness of the transparent film is, for example, 5 to 200 占 퐉, preferably 10 to 150 占 퐉, and more preferably 10 to 100 占 퐉.

A surface modification treatment such as a corona treatment, a flame treatment, a plasma treatment, an ultraviolet treatment, a primer coating treatment, a saponification treatment or the like is applied to the polarizing film and / or the transparent film in order to improve the adhesiveness between the adhesive and the polarizing film and / .

The transparent film may be subjected to surface treatment such as antiglare treatment, anti-reflection treatment, hard coating treatment, antistatic treatment and antifouling treatment, either singly or in combination of two or more kinds. The transparent protective film and / or the transparent film surface protective layer may contain an ultraviolet absorber such as a benzophenone-based compound or a benzotriazole-based compound or a plasticizer such as a phenylphosphate-based compound or a phthalic acid ester compound.

In addition, the transparent film can have optical functions such as a function as a retardation film, a function as a luminance enhancement film, a function as a reflective film, a function as a transflective film, a function as a diffusion film, and an optical compensation film. In this case, for example, it is possible to have such a function by laminating an optical functional film such as a retardation film, a luminance enhancement film, a reflection film, a transflective film, a diffusion film, or an optical compensation film on the surface of a transparent film In addition to this, the transparent film itself may be provided with such a function. In addition, a plurality of functions such as a diffusion film having the function of a brightness enhancement film may be provided in the transparent film.

For example, the stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, and the like are performed on the above-mentioned transparent film, or the process described in Japanese Patent No. 3168850 is performed to give a function as a retardation film can do. The retardation property in the retardation film can be appropriately selected, for example, in the range of the front retardation value of 5 to 100 nm and the thickness retardation value of 40 to 300 nm. Further, by forming fine holes in the above-mentioned transparent film by the method described in Japanese Patent Application Laid-Open Nos. 2002-169025 and 2003-29030, or by forming fine holes having different center wavelengths of selective reflection 2 By superimposing the cholesteric liquid crystal layer above the layer, a function as a brightness enhancement film can be given.

When a metal thin film is formed on the above-mentioned transparent film by vapor deposition, sputtering or the like, a function as a reflective film or a transflective film can be given. By coating the above-mentioned transparent film with a resin solution containing fine particles, a function as a diffusion film can be imparted. Further, by coating a liquid crystal compound such as a discotic liquid crystal compound and orienting the above-mentioned transparent film, a function as an optical compensation film can be imparted. Further, the transparent film may contain a compound exhibiting a retardation. Further, various optical functional films may be directly bonded to the polarizing film by using a suitable adhesive. Examples of the commercially available optical functional film include a luminance enhancement film such as DBEF (available from 3M Company, Japan, available from Sumitomo 3M Ltd.), a WV film (manufactured by Fuji Film Co., Ltd.) (Manufactured by Shin-Etsu Chemical Co., Ltd.), VA-TAC (manufactured by Konica Minolta Opto Co., Ltd.) ), And Sumikarite (manufactured by Sumitomo Chemical Co., Ltd.).

(Active energy ray curable adhesive)

The polarizing film and the transparent film are bonded together through an adhesive of an active energy ray curing type. As an active energy ray curable adhesive, an adhesive containing an epoxy resin composition containing an epoxy resin which is cured by irradiation with an active energy ray from the viewpoints of weather resistance, refractive index and durability can be mentioned. However, the present invention is not limited thereto. Various active energy ray curable adhesives (organic solvent adhesives, hot melt adhesives, solventless adhesives, etc.) conventionally used in the production of polarizing plates can be employed. Examples of the active energy ray curable adhesive include adhesives including acrylic resin compositions such as acrylamide, acrylate, urethane acrylate, and epoxy acrylate. Examples of the polymerization curing method include radical polymerization, cationic polymerization, anionic polymerization, thermal polymerization and the like.

The epoxy resin means a compound having two or more epoxy groups in the molecule. From the standpoint of weatherability, refractive index, cationic polymerizability and the like, the epoxy resin contained in the curable epoxy resin composition as the adhesive is preferably an epoxy resin containing no aromatic ring in the molecule (for example, see Patent Document 1). As such epoxy resins, hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like can be exemplified.

The hydrogenated epoxy resin can be obtained by a method of glycidyl etherification of a nuclear hydrogenated polyhydroxy compound obtained by selectively subjecting a polyhydroxy compound as a raw material of an aromatic epoxy resin to a nuclear hydrogenation reaction under pressure in the presence of a catalyst . Examples of the aromatic epoxy resin include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; Novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; Glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and epoxy polyvinylphenols. The epoxy resin may be used alone or in combination of two or more. Of hydrogenated epoxy resins, hydrogenated glycidyl ethers of bisphenol A are preferred.

The alicyclic epoxy resin means an epoxy resin having at least one epoxy group bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means a bridging oxygen atom -O- in the structure represented by the following formula. In the following formulas, m is an integer of 2 to 5.

The compound in which one or more hydrogen atoms of the (CH ₂ ) _m in the above formula are removed from other groups in the chemical structure may be an alicyclic epoxy resin. (CH ₂ ) _m may be suitably substituted with a straight chain alkyl group such as methyl group or ethyl group. Among the alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (wherein m = 3 in the above formula) or an oxabicycloheptane ring (in which m = 4 in the above formula) exhibits excellent adhesiveness, . Hereinafter, the alicyclic epoxy resin which is preferably used is specifically exemplified, but the present invention is not limited thereto.

(a) epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(Wherein R ¹ and R ² represent, independently of each other, a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(b) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(Wherein R ³ and R ⁴ represent, independently of each other, a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and n represents an integer of 2 to 20).

(c) epoxycyclohexylmethyl esters of dicarboxylic acids represented by the following formula (III):

(Wherein R ⁵ and R ⁶ are each independently of the other a hydrogen atom or a straight chain alkyl group of 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 are, independently of each other, a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

(e) epoxycyclohexyl methyl ethers of alkane diols represented by the following formula (V):

(Wherein R ⁹ and R ¹⁰ are independently of each other a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and r represents an integer of 2 to 20).

(f) a diepoxy trispyro compound represented by the following formula (VI):

(Wherein R < ¹¹ > and R < ¹² > independently represent a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms).

(g) a diepoxy monospiro compound represented by the following formula (VII):

(Wherein R ¹³ and R ¹⁴ represent, independently of each other, a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(h) vinylcyclohexene epoxides represented by the following formula (VIII):

(Wherein R ¹⁵ represents a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(i) epoxycyclopentyl ethers represented by the following formula (IX):

(Wherein R ¹⁶ and R ¹⁷ represent, independently of each other, a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(j) diepoxytricyclodecane compounds represented by the following formula (X):

(Wherein R ¹⁸ represents a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms).

Among the above-exemplified alicyclic epoxy resins, the following alicyclic epoxy resins are more preferably used because they are commercially available, or as analogues thereof, and are relatively easy to obtain.

(A) an ester of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept- ¹ = compound of R < ² > = H]

(B) An esterified product of 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl- [In the formula (I), a compound of R ¹ = 4-CH ₃ and R ² = 4-CH ₃ ]

(C) an esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [compound of formula (II) wherein R ³ = R ⁴ = H, n = 2] ,

Compounds of formula (III) wherein R ⁵ = R ⁶ = H, p = 4], (D) (7-oxabicyclo [4.1.0] hept-3-yl) methanol and adipic acid [

(E) (R ⁴ = CH ₃ , R ⁶ = CH ₃ ) in the formula (III) with an esterified product of (4-methyl- 4-CH ₃ , p = 4]

(F) (7- oxabicyclo [4.1.0] hept-3-yl) ether in the cargo [formula (V) of methanol and 1,2-ethanediol, R ⁹ = R ¹⁰ = a H, r = 2 compound].

Examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, diglycidyl ether of 1,4-butanediol; Diglycidyl ether of 1,6-hexanediol; Triglycidyl ether of glycerin; Triglycidyl ether of trimethylolpropane; Diglycidyl ether of polyethylene glycol; Diglycidyl ether of propylene glycol; And polyglycidyl ethers of polyether polyols 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.

The epoxy resin constituting the adhesive containing the epoxy resin composition may be used alone or in combination of two or more. 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. If the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizer after curing may be lowered or the adhesive strength may be lowered. On the other hand, if it exceeds 3,000 g / equivalent, 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 incorporate a cationic polymerization initiator into the curable epoxy resin composition which is an active energy ray curable adhesive. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation of an active energy ray such as visible light, ultraviolet ray, X-ray or electron ray to initiate the polymerization reaction of the epoxy group. Hereinafter, the cationic polymerization initiator for generating a cationic species or Lewis acid by irradiation of an active energy ray to initiate the polymerization reaction of the epoxy group is referred to as " photo cationic polymerization initiator ".

The method of curing the adhesive by irradiation of an active energy ray using a photo cationic polymerization initiator enables curing at room temperature and reduces the need to take into account distortion due to heat resistance or expansion of the polarizing film, It is advantageous in that it can be bonded. Further, since the photo cationic polymerization initiator acts catalytically with light, it is excellent in storage stability and workability even when mixed with an epoxy resin.

Examples of the photo cationic polymerization initiator include aromatic diazonium salts; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-arene complexes and the like.

Examples of the aromatic diazonium salt include benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate, benzene diazonium hexafluoroborate, and the like. Examples of the aromatic iodonium salt include diphenyl iodonium tetrakis (pentafluorophenyl) borate, diphenyl iodonium hexafluorophosphate, diphenyl iodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

The aromatic sulfonium salts include, for example, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis Diphenylsulfone bis (hexafluorophosphate), 4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenylsulfide bis (hexafluoroantimonate) (P-toluyl) sulfonyl] diphenylsulfide bis (hexafluorophosphate), 4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] (P-toluyl) sulfonium] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenyl Diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfone-diphenylsulfide hexafluorophosphate, And the like can be mentioned diphenyl sulfide tetrakis (pentafluorophenyl) borate-antimonate, 4- (p-tert- butylphenyl-carbonyl) -4'-di (p- toluyl) Pony O.

Examples of the iron-arene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron ) -Tris (trifluoromethylsulfonyl) methanide, and the like.

Commercially available products of these cationic photopolymerization initiators can be easily obtained. For example, "Kayarad PCI-220" and "Kayarad PCI-620" (trade names, manufactured by Nippon Kayaku Co., , "Adeka Optomer SP-150" and "Adeka Optomer SP-170" (manufactured by Adeka Corporation), "CI-6990" (manufactured by Union Carbide Corporation) DPI-101 "," CIP-2082S "and" CIP-2064S "(manufactured by Nippon Soda Co., Ltd.)," CIT- DPI-103, DPI-105, MPI-103, MPI-105, BBI-101, BBI-102, BBI- 105, TPS-101, TPS-102, TPS-103, TPS-105, MDS-103, MDS-105, DTS- (Manufactured by Midori Kagaku Co., Ltd.) and " PI-2074 " (manufactured by Rhodia).

The cationic photopolymerization initiator may be used singly or as a mixture of two or more thereof. Among them, an aromatic sulfonium salt is preferably used because it has an ultraviolet ray absorbing property even in a wavelength range of 300 nm or more and is therefore excellent in curability and can provide a cured product having good mechanical strength and adhesive strength.

The compounding amount of the photo cationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and more preferably 15 parts by weight or less, based on 100 parts by weight of the epoxy resin. If the blending amount of the photo cationic polymerization initiator is less than 0.5 part by weight based on 100 parts by weight of the epoxy resin, the curing becomes insufficient and the mechanical strength and the adhesive strength tend to be lowered. If the compounding amount of the photo cationic polymerization initiator is more than 20 parts by weight based on 100 parts by weight of the epoxy resin, the amount of the ionic substance in the cured product increases to increase the hygroscopicity of the cured product.

When a photo cationic polymerization initiator is used, the curable epoxy resin composition may further contain a photosensitizer, if necessary. By using a photosensitizer, the reactivity of the cationic polymerization is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfate compound, a redox compound, an azo compound and a diazo compound, a halogen compound, a light reducing pigment and the like.

More specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and?,? -Dimethoxy-? -Phenylacetophenone; Benzophenone derivatives such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; Thioxanthone derivatives such as 2-chlorothioxanthone, and 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloro anthraquinone, and 2-methyl anthraquinone; Acridone derivatives such as N-methyl acridone, and N-butyl acridone; Other examples include?,? - diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compound, and halogen compound. The photosensitizer may be used alone or in combination of two or more. It is preferable that the photosensitizer is 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 from photo cation polymerization, but may also be cured by both photo cation polymerization and thermal cation polymerization. In the latter case, a photo cationic polymerization initiator and a thermal cationic polymerization initiator are preferably used in combination.

Examples of the thermal cationic polymerization initiator include a benzylsulfonium salt, a thiophenium salt, a thioronium salt, a benzylammonium salt, a pyridinium salt, a hydrazinium salt, a carboxylic acid ester, a sulfonic acid ester, and an amine imide. These thermal cationic polymerization initiators can be easily obtained as commercial products, and examples thereof include "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (trade names, manufactured by Adeka Kagaku Co., Ltd.) CI-2639 "and" CI-2624 "(manufactured by Nippon Soda Co., Ltd.)," Sun Aid SI-60L "," Sun Aid SI-80L "and" Sun Aid SI- Manufactured by Kabushiki Kaisha).

The active energy ray curable adhesive may further contain a compound that promotes cationic polymerization such as oxetanes and polyols.

The oxetanes are compounds having a 4-membered ring ether in the molecule, and examples thereof include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxy (3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) ox Cetane, phenol novolac oxetane, and the like. These oxetanes are commercially available as commercially available products, and examples thereof include "AARON oxetane OXT-101", "AARON oxetane OXT-121", "AARON oxethane OXT-211" , "Aronoxetan OXT-221" and "Aronoxetan OXT-212" (all manufactured by Toagosei Co., Ltd.). These oxetanes are contained in the curable epoxy resin composition in an amount of usually 5 to 95% by weight, preferably 30 to 70% by weight.

As the polyol, it is preferable that an acid group other than the phenolic hydroxyl group is not present. For example, a polyol compound having no functional group other than the hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol compound having a phenolic hydroxyl group , Polycarbonate polyol, and the like. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and further preferably 1,000 or less. These polyols are usually contained in a proportion of not more than 50% by weight, preferably not more than 30% by weight, in the curable epoxy resin composition.

Additives such as an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a leveling agent, a plasticizer, and an antifoaming agent may be further added to the active energy ray curable adhesive. Examples of the ion trap agent include inorganic compounds such as powdery bismuth, antimony, magnesium, aluminum, calcium, titanium and mixtures thereof. Examples of the antioxidant include hindered phenol antioxidants have.

The active energy ray-curable adhesive can be used as a solvent-free adhesive agent substantially not containing a solvent component. However, since each coating method has an optimum viscosity range, a solvent may be added for viscosity adjustment. As the solvent, it is preferable to use a solvent which dissolves an epoxy resin composition or the like well without lowering the optical performance of the polarizing film. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate . 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.

≪ Polarizing plate production method >

Next, a manufacturing apparatus and a manufacturing method of a polarizing plate of the present invention will be described with reference to the drawings. 1 is a schematic view showing an embodiment of an apparatus for producing a polarizing plate of the present invention.

The polarizing plate manufacturing apparatus 30 shown in Fig. 1 is provided with adhesive applicators 11 and 12 for applying an adhesive to one side of the transparent films 2 and 3, transparent films 2 and 3 and polarizing films (Nip rolls) 51 and 52 for joining the transparent films 2 and 3 and the polarizing film 1 to each other to obtain the laminated body 4, A first active energy ray irradiating device (14, 15) provided at a position facing the outer circumferential surface of the roll (13), and a second and subsequent active energy ray irradiating device 16 to 18 and a transporting nip roll 19 are provided in this order along the transport direction.

First, an adhesive of an active energy ray-curable type is applied to one side of the transparent films 2 and 3 which are continuously unwound from the roll-shaped state by the adhesive applicators 11 and 12 (adhesive applying step).

A laminate in which transparent films 2 and 3 coated with an adhesive are laminated on both sides of a polarizing film 1 which has been continuously unwound from a roll-like wound state through an adhesive agent The polarizing film 1 and the transparent films 2 and 3 are bonded by pressing at least one of the bonding rolls in the direction of the other bonding roll in a state sandwiched between the pair of bonding rolls 51 and 52, (Bonding step).

Next, an active energy ray is irradiated from the first active energy ray irradiating device (14, 15) toward the outer peripheral surface of the roll (13) in the process of conveying the laminate (4) while adhering to the outer peripheral surface of the roll , And the adhesive is polymerized and cured (active energy irradiation step).

The second and subsequent active energy ray irradiating devices 16 to 18 disposed on the downstream side in the carrying direction are devices for completely polymerizing and curing the adhesive agent and can be added or omitted as necessary. Finally, the layered product 4 passes through the transporting nip roll 19 and is wound on the winding roll 20 as a polarizing plate. Hereinafter, each step will be described in detail.

(Adhesive Coating Process)

The method of coating the adhesive on the transparent films 2, 3 is not particularly limited, but various coating methods such as doctor blade, wire bar, die coater, comma coater, and gravure coater can be used. Among them, a gravure roll is preferable as the adhesive applicators 11 and 12 in consideration of the thin film coating, the degree of freedom of the pass line, and the correspondence to the wide width. A commercially available coating apparatus is an MCD (micro chamber doctor) manufactured by Fuji Machinery.

When the adhesive is applied using a gravure roll as the adhesive applicators 11 and 12, the thickness (coating thickness) of the applied adhesive is preferably about 0.1 to 10 mu m, more preferably 0.2 to 4 mu m to be. The coating thickness of the adhesive is adjusted in accordance with the draw ratio, which is the velocity ratio of the gravure roll to the line speed of the transparent film. In general, by adjusting the draw ratio (speed / line speed of the gravure roll) to 0.5 to 10, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 mu m. More specifically, the gravure roll is rotated in the direction opposite to the conveying direction of the transparent film (2, 3) with the line speed of the transparent film (2, 3) set at 10 to 100 m / 1000 m / min, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 탆.

After the adhesive is produced, it is preferable that the adhesive is heated to a predetermined temperature within a range of usually 15 to 40 ° C ± 5 ° C (for example, 30 ° C ± 5 ° C when the predetermined temperature is 30 ° C) Is applied under an environment adjusted to ± 1 ° C.

(Bonding step)

In this step, the transparent films 2, 3 coated with the adhesive by the above-described process are laminated on both sides of the polarizing film 1 which has been continuously unwound from the roll-like wound state through the adhesive. The lamination body is pressed in the direction of the bonding roll 52 in the state in which the lamination body is sandwiched between the pair of bonding rolls 51 and 52 which are rotated in the carrying direction, And the transparent films 2 and 3 are bonded to each other to form the layered product 4. At this time, the polarizing film is moved between the bonding rolls so as to form an angle within a range of preferably ± 3 °, more preferably ± 1 ° with respect to the plane perpendicular to the pressing direction of the bonding roll, . Particularly preferably, the polarizing film is conveyed between the bonding rolls so that the conveying direction of the polarizing film overlaps the surface perpendicular to the pressing direction of the joining roll. By doing so, the polarizing film and the transparent film do not come into contact with each other immediately before the bonding roll, and bubbles are not generated.

1, an adhesive is uniformly applied to one surface of the transparent films 2 and 3, and the polarizing film 1 is laminated on the surface of the transparent films 2 and 3 coated with the adhesive, The adhesive is uniformly applied to both surfaces of the polarizing film 1 and the transparent films 2 and 3 are laminated on the surface of the polarizing film 1 coated with the adhesive to form a bonding roll 51, and 52, respectively.

The present invention is characterized in that at least one of the pair of bonding rolls (51, 52) is a double bent roll. The double-vent roll is a roll having a dual structure composed of a roll having a central axis and an outer circumferential surface. Since the center shaft and the roll portion are only partially joined, even if a bending due to an external force occurs in the center shaft, And has a structure in which no warping occurs. The other roll may be a conventional flat roll having a substantially uniform diameter, or may be a double bent roll, but a double bent roll is more preferable.

For example, the bonding roll 51 is a double vent roll 51 having a double structure composed of a metal center shaft 51a and a metal roll 51b as shown in Fig. 2, and the bonding roll 52 Is an ordinary flat roll made of rubber, an external force is applied to the bearing member 51d of the double vent roll 51 in the direction of the normal flat roll 52, as shown by arrows in Fig. Since the roll portion 51b is joined to the central shaft 51a only at the central portion in the axial direction, the roll 51b The outer circumferential surface of the outer circumferential surface is not warped. Thus, the laminate (the polarizing film 1 and the transparent films 2 and 3) constituting the polarizing plate can be uniformly pressed.

2, the width of the gap 51c and the length in the width direction of the non-contact portion between the center shaft 51a and the roll portion 51b are set such that the center axis 51a And the end of the roll portion 51b are not in contact with each other, and is appropriately adjusted in accordance with the material of the center shaft 51a, the width and diameter of the roll, and the pressing force. Here, the ratio of the length (support width B) of the joining portion of the center shaft 51a to the roll portion 51b to the axial length (roll surface length A) of the surface of the roll portion is 10 to 70% . And more preferably in the range of 20 to 60%. If it is out of this range, the warp becomes too large or too small, so that there is a high possibility that the pressurization becomes uneven.

The diameter of the bonding roll is not particularly limited, but the diameter of the double vent roll (outer diameter of the roll portion) is preferably 50 to 400 mm. The diameter of a conventional flat roll is preferably 50 to 400 mm. The diameter of each of the pair of bonding rolls may be the same or different. The width (roll surface length) of the joining roll is preferably 300 to 3000 mm.

The pressure applied to the laminate by the above pressurization is not particularly limited, but when a metal roll and a rubber roll are used, the instantaneous pressure in the fuji film-producing sheet type free scale is preferably 0.5 to 3.0 MPa, And more preferably 0.7 to 2.3 MPa. In the present invention, the external force of pressing against this joining roll is usually applied to the bearing members at both ends of the joining roll.

The material of the joining roll may be metal or rubber. It is preferable that one of the pair of bonding rolls is a metal roll and at least the outer circumferential surface of the other bonding roll is made of rubber. When the pair of bonding rolls are all made of metal, scratches easily occur between the rolls by use, so that it is difficult to use them continuously. On the other hand, when the outer circumferential surfaces of the pair of bonding rolls are all made of rubber, high pressure is hardly generated. The arrangement of the joining rolls and the pressurizing rolls is not particularly limited and may be arranged so as to form an arbitrary angle with respect to each other. That is, the pressing rolls are not limited to the upper and lower sides of the bonding roll, but may be arranged horizontally or at other angles.

In the conventional joining roll, the joining roll on the upper side which is normally pressed is made of rubber, and the joining roll on the lower side is made of metal. This is because the lower joining roll is made of metal so that the lower joining roll is not deformed at the time of pressurization and the main speed of the joining roll is easily kept constant Because. However, in order to facilitate the curling adjustment of the laterally-described curling, in the present invention, it is preferable that the pressing roll (upper side) is made of metal and at least the outer circumferential surface of the other (lower side) .

As the base material of the metal roll, various known materials can be used, preferably stainless steel, and more preferably SUS304 (stainless steel containing 18% of Cr and 8% of Ni). The surface of the metal roll is preferably subjected to a chromium plating treatment.

The material of the rubber constituting at least the outer circumferential surface of the bonding roll is not particularly limited and examples thereof include NBR (nitrile rubber), titan, urethane, silicone and EPDM (ethylene-propylene-diene rubber) , Titanium, and urethane. The hardness of the rubber roll is not particularly limited, but is usually 60 to 100 °, preferably 85 to 95 °. The hardness of the rubber roll can be measured by a hardness meter according to JIS K6253. As a commercially available hardness meter, for example, a rubber hardness meter "Type-A" manufactured by Asuka Co., Ltd. is used. Specifically, the resistance of the surface of the rubber roll when the surface is pressed by a rod or the like is measured with a hardness meter.

When the roll portion of the double vent roll is made of rubber, it is preferable that the roll portion is provided with a metal body having sufficient strength on the inner circumferential side so that uniform pressurization can be performed on the outer circumferential surface of the roll portion.

The pair of joining rolls are preferably driven independently of each other, and there may be a difference in the main speeds of one joining roll and the other joining roll. For example, it is preferable that the peripheral speed of the bonding roll (first bonding roll) provided on the surface side of the laminate 4 bonded to the liquid crystal panel is higher than the peripheral speed of the bonding roll on the opposite side (second bonding roll). Thus, curling (positive curling) in which the surface bonded to the liquid crystal panel is convex and the surface on the opposite side thereof is concave is provided on the obtained polarizing plate. In the case where curling (reverse curling) in which the surface to be bonded to the liquid crystal panel is concave and the surface on the opposite side thereof is convex is imparted to the obtained polarizing plate, when bonding the polarizing plate to the liquid crystal cell, Problems are likely to occur. In this case, it is preferable that a metal roll is used as the first bonding roll, and a roll whose outer peripheral surface is at least rubber is used as the second bonding roll.

Further, when the main speed of the second joining roll is 1, it is more preferable that the ratio of the main speed of the first joining roll is 1.0050 to 1.0200. When the primary velocity of the first bonding roll is faster than this range, the amount of curling of the positive curling becomes large, and when the polarizing plate is bonded to the liquid crystal cell, there arises a problem of bubbling the end portion. Curling is further promoted and the end of the polarizing plate may peel off from the liquid crystal cell.

The roll 13 constitutes a convex curved surface whose outer circumferential surface is mirror-finished and is conveyed while adhering the laminated body 4 to the surface thereof. During the process, the active energy ray irradiating devices 14 and 15 polymerize and cure the adhesive . The diameter of the rolls 13 is not particularly limited in order to polymerize and cure the adhesive and sufficiently adhere the layered product 4. [ It is preferable that the laminated body 4 in which the adhesive is in an uncured state is irradiated with an active energy ray so that the accumulated light quantity during passage through the roll 13 becomes 10 mJ / cm ² or more. The roll 13 may be driven or rotated to move the line of the laminate 4, or may be fixed so that the laminate 4 slides on the surface. The roll 13 may also serve as a cooling roll for dissipating the heat generated in the laminate 4 at the time of polymerization curing by irradiation of active energy rays. In this case, the surface temperature of the cooling roll is preferably set to 4 to 30 占 폚.

(Active energy irradiation process)

The light source used for polymerizing and curing the adhesive by irradiation of an active energy ray is not particularly limited, but is preferably a light source having a light emission distribution at a wavelength of 400 nm or less. Examples of such light sources include low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, and metal halide lamps.

The light irradiation intensity for the active energy ray-curable adhesive is not particularly limited, as determined depending on the composition of the adhesive, but is preferably 10 to 5000 mW / cm ² . If the light irradiation intensity to the resin composition is less than 10 mW / cm ² , the reaction time becomes too long, and if it exceeds 5,000 mW / cm ² , heat radiated from the lamp and heat generated during polymerization of the composition, There is a possibility that yellowing of the epoxy resin composition or the like or deterioration of the polarizing film may occur. The irradiation intensity is preferably the intensity in the wavelength range effective for activation of the photo cationic polymerization initiator, more preferably the intensity in the wavelength range of 400 nm or less, more preferably the wavelength range of 280 to 320 nm .

The irradiation time of the active energy ray for the active energy ray curable adhesive is controlled for each composition to be cured and is not particularly limited, but it is preferably 10 mJ / cm ² or more, more preferably 10 mJ / cm ² or more, To 5,000 mJ / cm < ² >. If the integrated amount of light for the adhesive is less than 10 mJ / cm ² , the generation of the active species derived from the initiator is not sufficient and the curing of the adhesive becomes insufficient. On the other hand, if the accumulated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes extremely long, which is disadvantageous for the productivity improvement. At this time, depending on the combination of the film to be used and the kind of the adhesive agent, it depends on what wavelength range (UVA (320 to 390 nm), UVB (280 to 320 nm), etc.)

In the present invention, the adhesive is polymerized and cured by irradiating the laminate with an active energy ray, but polymerization curing by heating may also be used in combination.

When the active energy ray is ultraviolet ray, in the step of irradiating the layered product 4 with the active energy ray, a tensile force of 100 to 800 N / m is applied to the layered product 4 in the longitudinal direction (conveying direction) It is preferable that the layered product 4 is transported at a line speed of 0.1 second or more. The irradiation intensity of ultraviolet rays is preferably 10 mW / cm ² or more.

When the accumulated energy of the active energy rays by the active energy ray irradiating devices 14 and 15 is insufficient, the second and subsequent active energy ray irradiating devices 16 to 18 are further provided, , Thereby accelerating the curing of the adhesive of the layered product (4). These are the accumulated light quantity of the entire process, 10mJ / cm ² or more, and preferably set to be from 10 to 5,000mJ / cm ^2. As described above, in the step of irradiating the active energy rays, it is preferable that the irradiation of the active energy rays is performed a plurality of times.

In order to surely cure the adhesive at the end of the polarizing plate (laminate), for example, a "Light Hammer 10" manufactured by Fusion, which is an electrodeless D valve lamp, is arranged to be transverse to the running of the film And the like.

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

(Polarizing plate winding step)

The tension for winding the laminate (polarizing plate) 4 is 30 N / cm ² to 150 N / cm ² . Preferably 30N / cm ² to 120N / cm ^2. If it is less than 30 N / cm ² , it is not preferable because a winding deviation occurs when a long winding roll is fed. When it is larger than 150 N / cm ² , the winding is likely to be tightened and sagging easily occurs.

Further, the longer the winding length becomes, the more easily the winding tension (the phenomenon in which it becomes difficult to return to the flat state when unwinding) becomes the same with the same tension, so that the tension can be continuously or stepwise lowered while the polarizing plate is wound around the core . Even in the method of lowering the tension by placing such a taper, the tension at that time is set to 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 diameter of the core is preferable, and 11 inches or 12 inches is more preferable, but if it is too large, transport or storage becomes difficult.

The material of the cylindrical core is not particularly limited so long as it can be used in a clean room and can secure sufficient strength so that it can not oscillate and can wind a wide polarizer. However, FRP (glass fiber reinforced plastic ) Can be selected.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[Example 1]

(Production of polarizing film)

As the original film of polyvinyl alcohol, a long polyvinyl alcohol film "Vinylon VF-PS # 7500 (Kuraray Co., Ltd.)" having a degree of polymerization of 2400, a degree of saponification of 99.9 mol%, a thickness of 75 μm and a width of 3000 mm was used. The stretching was carried out with the peripheral speed difference between the driving nip rolls before and after the treatment tank.

First, the original film was immersed in a swelling tank containing pure water at 30 DEG C for 80 seconds while keeping the tension of the film so that the original film was not loosened, thereby sufficiently swelling the film. The ratio of the roll speed at the inlet to the exit due to swelling in the swelling bath was 1.2. After dewatering in a nip roll, it was immersed in a water immersion tank containing pure water at 30 DEG C for 160 seconds. The draw ratio in the machine direction in this tank was 1.09 times.

Next, uniaxial stretching was carried out at a drawing magnification of about 1.5 times while immersed in a dyeing bath containing an aqueous solution containing iodine / potassium iodide / water (weight ratio: 0.02 / 2.0 / 100). Thereafter, uniaxial stretching was carried out by soaking in a boric acid bath containing an aqueous solution of 12 / 3.7 / 100 by weight of potassium iodide / boric acid / water at 55.5 DEG C for 130 seconds, until the cumulative stretching magnification from the disk reached 5.7. Thereafter, it was immersed in a boric acid bath containing an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 9 / 2.4 / 100 at 40 ° C for 60 seconds.

Then, the substrate was rinsed with pure water at 8 DEG C for about 16 seconds in a water bath, and then dried at about 60 DEG C and then at about 85 DEG C successively, and the retention time in the drying furnace was set to 160 seconds Drying was carried out. Thus, a polarizing film having a thickness of 28 mu m in which iodine was adsorbed and oriented was obtained.

(Production of polarizing plate)

As a transparent film, a cycloolefin 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 Co., Ltd.) having a thickness of 80 μm were prepared.

Next, an epoxy resin composition " KR series " (including a cation polymerization initiator manufactured by Adeka Co., Ltd.), which is an ultraviolet curing type adhesive, was adhered to one surface of a cycloolefin resin film " Zeonor " (Micro Chamber Doctor: manufactured by Fuji Machinery Co., Ltd.). Further, an epoxy resin composition "KR series" (manufactured by Adeka Corporation, including a cationic polymerization initiator), which is an ultraviolet curable adhesive, was applied on one side of a triacetyl cellulose film "KC8UX2MW" having a thickness of 80 μm Respectively. At this time, the gravure roll was rotated in the direction opposite to the conveying direction of the laminate with the line speed of the polarizing film laminate in the adhesive coating device set at 25 m / min to obtain a cycloolefin resin film "ZEONOR" The thickness of the adhesive layer on the triacetylcellulose film " KC8UX2MW " having a thickness of 80 mu m was set to about 3.5 mu m.

Next, a cycloolefin resin film "ZEONOR" having a thickness of 50 μm and a triacetyl cellulose film "KC8UX2MW" having a thickness of 80 μm were laminated on both sides of the above polarizing film with the above epoxy resin composition (an ultraviolet curable adhesive ) And a flat roll (lower side: NBR rubber roll, diameter: 240 mm) having a support width ratio of 35% to the roll surface length (1300 mm) ) Was used as a joining roll, and both ends of the bearing of the double vent roll were subjected to an external force of urging to join them.

The polarizing film to which the two kinds of transparent films were bonded was fed at a line speed of 25 m / min while being tightly adhered to a cooling roll with a tensile force of 600 N / m in the longitudinal direction so that the width direction of the film was in the longitudinal direction, A first activating energy for passing through the ultraviolet ray irradiated from a rod-like metal halide lamp 2 (GS-YUASA, power 1 per unit length 120 W / cm) arranged in parallel in the carrying direction Electrodeless D valve lamp 6 or the like (" Light Hammer 10 " manufactured by Fusion Co., Ltd., power of 216 W / cm per unit length) arranged in series in the width direction of the film A UV curing treatment was carried out by a second active energy ray irradiation step in which ultraviolet rays passing through the second active energy ray irradiation step were irradiated to produce a polarizing plate.

At the time of passing through the metal halide lamp, a triacetyl cellulose film " KC8UX2MW " having a thickness of 80 mu m bonded to the above polarizing film was brought into contact with the outer circumferential surface of a cooling roll set at 23 DEG C to prepare a cycloolefin resin film " Zeonor (ZEONOR) " side. As a result, deterioration of the adhesive and the polarizing film due to the influence of heat in the first active energy ray irradiation step is suppressed.

(Nip pressure distribution of bonding roll and evaluation of bubble in polarizer)

The nip pressure of the bonding roll of Example 1 was measured using a Freescale (ultra-low pressure) sheet made of a Fuji film, and was found to be substantially uniform in the width direction. Further, evaluation of the prepared polarizing plate showed no bubbles. The results are shown in Table 1.

[Example 2]

A polarizing plate was produced in the same manner as in Example 1 except that the ratio of the support width to the roll surface length of the double vent roll was 46%.

(Nip pressure distribution of bonding roll and evaluation of bubble in polarizer)

The nip pressure of the bonding roll of Example 2 was measured using a Freescale (ultra-low pressure) sheet with a two-sheet film made of Fuji Film, and was found to be substantially uniform in the width direction. Further, evaluation of the prepared polarizing plate showed no bubbles. 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 a conventional flat roll (upper side: SUS-made metal roll, diameter 250 mm) was used instead of the double vent roll.

(Nip pressure distribution of bonding roll and evaluation of bubble in polarizer)

The nip pressure of the bonding roll of Comparative Example 1 was measured using Freescale (ultra-low pressure), which is a two-sheet type sheet produced by Fuji Film, and the distribution in the width direction was large. Further, the produced polarizing plate was evaluated, and bubbles were observed. The results are shown in Table 1.

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

1: polarizing film
2, 3: Transparent film
4: laminate (polarizer)
11, 12: Adhesive coating device
13: roll (cooling roll)
14, 15, 16, 17, 18: an active energy ray irradiator
19: Return nip roll
20: winding roll
51: bonding roll (double vent roll)
51a: center axis
51b:
51c: gap
51d: bearing member
52: bonding roll (flat roll)

Claims (3)

A method for producing a polarizing plate comprising a polarizing film (1) and transparent films (2, 3) bonded to one or both surfaces thereof,
An adhesive applying step of applying an active energy ray-curable adhesive to one surface of the transparent film (2, 3) or one surface or both surfaces of the polarizing film (1)
Between the pair of bonding rolls 51 and 52 for rotating the laminated body 4 in which the transparent films 2 and 3 are laminated on one or both sides of the polarizing film 1 with the adhesive in the carrying direction A joining step of joining the transparent film (2, 3) and the polarizing film (1) by pressing at least one of the joining rolls in the direction of the other joining roll,
And an active energy ray irradiation step of irradiating the layered product (4) with an active energy ray to cure the adhesive,
At least one of the pair of bonding rolls 51 and 52 is a double bent roll 51 having a double structure composed of a central shaft 51a and a roll portion 51b having an outer peripheral surface, And the roll part (51b) are partially bonded to each other so that no warpage occurs in the outer peripheral surface of the roll part (51b) even when the center shaft (51a) is bent. The method of manufacturing a polarizing plate according to claim 1, wherein the external force of the pressing is applied to a bearing member (51d) provided at both ends of the center shaft (51a). An apparatus for producing a polarizing plate comprising a polarizing film (1) and transparent films (2, 3) bonded to one or both surfaces thereof,
(11, 12) for applying an active energy ray-curable adhesive to one surface of the transparent film (2, 3) or one surface or both surfaces of the polarizing film (1)
The laminated body (4) comprising the transparent film (2, 3) laminated on one side or both sides of the polarizing film (1) through the adhesive is conveyed and pressed, A pair of bonding rolls 51 and 52 for bonding the film 1,
And an active energy ray irradiating device (14, 15, 16, 17, 18) for irradiating the layered product (4) with an active energy ray to cure the adhesive,
At least one of the pair of bonding rolls 51 and 52 is a double bent roll 51 having a double structure composed of a central shaft 51a and a roll portion 51b having an outer peripheral surface, And the roll part (51b) are partially bonded to each other so that no warpage occurs in the outer peripheral surface of the roll part (51b) even when the center shaft (51a) is bent.

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