KR20140088540A - Method for manufacturing polarizer - Google Patents

Abstract

A method of producing a polarizing plate according to the present invention is a method of manufacturing a polarizing plate comprising a step of applying an adhesive of active energy ray curing type to one side or both sides of a transparent film or a polarizing film, A step of bonding a transparent film and a polarizing film by applying a pressure to a laminate formed by laminating the laminate through an adhesive layer, and a step of irradiating an active energy ray to the laminate while conveying the laminate in a state of being in close contact with a roll rotating in the conveying direction to a first active energy ray irradiation process, the in this order and having a first active energy ray in the exposure step, an ultraviolet (UVB) the cumulative dose 10mJ / cm ² over 185mJ / cm ² or less to cure the adhesive.

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).

In the polarizing plate thus produced, if the active energy ray-curable resin is not properly cured, curling such as wave curling or the like, which causes the entire polarizing plate to wave, may occur. When the polarizing plate is subjected to wave curling, bubbles tend to remain on the bonding surface when adhering to the liquid crystal cell as well as the appearance defects, and the workability is deteriorated and the display quality in the liquid crystal display device is deteriorated.

Patent Document 3 discloses that when the active energy ray-curable resin is cured by irradiating an active energy ray, the laminate is cured while closely adhering to the outer surface of the roll, whereby occurrence of wave curling and the like can be suppressed.

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

In the method of producing a polarizing plate having a step of curing an active energy ray-curable resin by irradiating an active energy ray, undulations such as waving on the surface of the layered product (hereinafter referred to as " wave unevenness ") may occur. If wavefront irregularity occurs in the polarizing plate, quality deterioration in the liquid crystal display device may be caused by appearance defects as in the case of wave curling. An object of the present invention is to suppress the occurrence of wavy unevenness.

The present invention relates to a method for producing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film, wherein an active energy ray-curable adhesive is applied to one side of the transparent film or one side or both sides of the polarizing film A bonding step of bonding the transparent film and the polarizing film by applying pressure to a laminated body in which the transparent film is laminated on one side or both sides of the polarizing film through the adhesive, And a first active energy ray irradiation step of irradiating the laminate with an active energy ray to cure the adhesive while being conveyed in a state of being in tight contact with a roll rotating in the carrying direction, in the irradiation process, the accumulated light quantity of the ultraviolet ray (UVB) at least 10mJ / cm ² 185mJ / cm ² or less. The roll is preferably a cooling roll.

In the present invention, the effect is high when at least one of the transparent films is a cellulose acetate resin film.

The present invention may further comprise a second activation energy ray irradiation step of irradiating an activation energy ray to the laminate after the first activation energy ray irradiation step to cure the adhesive.

In one embodiment of the present invention, in the first active energy ray irradiation step, irradiation of active energy rays is performed with a plurality of light sources.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to produce a polarizing plate having favorable appearance with suppressed occurrence of wave phase unevenness and wave curling. Therefore, by using the polarizing plate obtained by the production method of the present invention, it is possible to prevent deterioration in workability of adhesion to the liquid crystal cell and to provide a high-quality liquid crystal display device.

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 side view showing an embodiment of an apparatus for producing a polarizing plate according to the present invention.

The present invention relates to a method for producing a polarizing plate comprising a polarizing film and a transparent film bonded to one or both sides of the polarizing film, wherein the polarizing film is applied on one side of the transparent film or on one side or both sides of the polarizing film with an adhesive for applying an active energy ray- A bonding step of bonding a transparent film and a polarizing film by applying a pressure to a laminated body in which a transparent film is laminated on one or both sides of a polarizing film through an adhesive; and a step of bonding the laminated body to a roll rotating in the carrying direction And a first active energy ray irradiation step of irradiating an active energy ray to the laminate to cure the adhesive while being conveyed in a state in which the first active energy rays are irradiated. First in active energy ray irradiation process, the accumulated light quantity of ultraviolet light (UVB) is 10mJ / cm ² over 185mJ / cm ² or less.

First, each element used in the manufacturing method of the present invention will be described in detail.

(Polarizing film)

Specifically, the polarizing film used in the method for producing a polarizing plate of the present invention is one obtained by orienting a dichromatic dye on a uniaxially stretched polyvinyl alcohol resin film. 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 in the range of 1500 to 6000 mm.

(Vinylon VF-PS # 7500, manufactured by Kuraray Co., Ltd. / OPL film M-7500, manufactured by Nippon Gosei Co., Ltd.) Vinylon VF-PE # 6000, Kuraray Co., Ltd.) has a thickness of 60 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 resin film is dipped in an aqueous solution containing a dichroic dye is generally 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 75 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. After the washing treatment, the drying treatment is usually carried out to obtain a polarizing film. 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 80 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 5 to 50 mu m.

(Transparent film)

In the present invention, a transparent film is bonded to one side or both sides of the above-mentioned polarizing 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 olefin resins such as polypropylene, which are conventionally widely used in the field. When the transparent film is bonded to both surfaces of the polarizing film, the respective transparent films may be the same or may be different kinds of films, but the effect is high when at least one of them is an acetic acid cellulose based resin film. When a cellulose acetate based resin film is used as the transparent film, the wave phase unevenness tends to easily occur, and therefore, the effect of suppressing occurrence of wave phase nonuniformity by the production method of the polarizing plate of the present invention becomes remarkable.

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 Co., Ltd.), KC8UY (manufactured by Konica Minolta Opto Co., Ltd.), Fujitac TD60UL (manufactured by Fuji Film Co., Ltd.), KC2UAW KC6UAW (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 manufacturing method 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 of an active energy ray from the viewpoints of weatherability, refractive index, cationic polymerizability and the like can be mentioned. However, the present invention is not limited thereto. Various types of active energy ray-curable adhesives (organic solvent adhesives, hot melt adhesives, solventless adhesives, etc.) conventionally used in the production of polarizers, such as acrylamide, An adhesive containing an acrylic resin composition such as acrylate, epoxy acrylate and the like can be employed.

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. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing an embodiment of a production apparatus used in a production method of a polarizing plate of the present invention. FIG.

The apparatus for producing a polarizing plate shown in Fig. 1 comprises adhesive applicators 11 and 12 for applying an adhesive to one surface of a transparent film 2 and 3, transparent films 2 and 3 and a polarizing film 1 (Nip rolls) 51 and 52 for joining to obtain the laminate 4 and a roll 13 in which the laminate 4 is brought into close contact with each other; 1 active energy ray irradiating devices 31 and 32 and second active energy ray irradiating devices 16 to 18 provided on the downstream side in the conveying direction and conveying nip rolls 19 are arranged in this order have.

First, an adhesive of the active energy ray curing 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 coating devices 11 and 12 (adhesive application 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 At least one of the bonding rolls is pressed in the direction of the other bonding roll so as to apply pressure to the laminated body to sandwich the polarizing film 1 and the transparent films 2 and 3 ) Are bonded to form a laminate 4 (bonding step).

Next, an active energy ray is irradiated from the first active energy ray irradiating device (31, 32) toward the outer peripheral surface of the roll (13) in the process of transporting the laminate (4) while adhering to the outer peripheral surface of the roll , And the adhesive is polymerized and cured (first active energy ray irradiation step).

Further, the second 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 (second active energy ray irradiating step), and can be added or omitted However, since the adhesive can be completely polymerized and cured by the second active energy ray irradiation step, it is not necessary to completely polymerize and cure the adhesive in the first active energy ray irradiation step, so that the occurrence of wave curling can be suppressed, It is easy to control the accumulated light amount, and therefore, it is preferable to have the second active energy ray irradiation step. 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 process will be described in detail.

(Adhesive application step)

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.

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, it is preferable to form an angle within a range of ± 3 ° with respect to a surface perpendicular to the pressing direction of the bonding roll, preferably an angle within a range of ± 1 °, It is preferable to transport the polarizing film between the joining rolls. 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.

As the material of the bonding rolls 51 and 52, a metal roll or a rubber roll may be used. It is preferable that one of the pair of bonding rolls 51 and 52 is a metal roll and the other is a rubber roll. As the base material of the metal roll, various known materials can be used, preferably SUS304, and the surface is more preferably subjected to chromium plating treatment. The material of the rubber roll is not particularly limited, and examples thereof include EPDM, NBR, urethane, titanium, silicon and the like. 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.

The pressing pressure of the metal roll and the rubber roll is preferably 0.5 to 3.0 MPa, and more preferably 0.7 to 2.3 MPa in terms of the instantaneous pressure in a sheet type free scale (for ultra low pressure) manufactured by Fuji Film. The diameter of the bonding rolls 51 and 52 is not particularly limited, but is usually 50 to 400 mm. The diameters of the two (pair of) bonding rolls 51 and 52 may be the same or different.

(First active energy ray irradiation step)

The roll 13 constitutes a convex curved surface whose outer circumferential surface is mirror-finished, and the laminated body 4 is conveyed while closely adhering to the surface thereof. During the process, the active energy ray irradiating devices 31 and 32 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. [ And the roll 13 is rotationally driven at a rotational speed corresponding to the line speed. 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 캜.

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. It is preferable that the irradiation of the active energy ray in the first active energy ray irradiation step is performed in plural steps. Fig. 1 shows a case in which irradiation of an active energy ray is performed in two steps, that is, two light sources (active energy ray irradiation devices 31 and 32) are arranged along the conveying direction of the laminate, For example, three times.

Fig. 2 shows an apparatus for producing a polarizing plate in which three light sources used in the first active energy ray irradiation step are arranged along the conveying direction of the laminate. The manufacturing apparatus shown in Fig. 2 differs from the manufacturing apparatus shown in Fig. 1 in that, in addition to the active energy ray irradiating devices 31 and 32, the active energy ray irradiating device 33, as a light source used in the first active energy ray irradiating step, The description of the other components will be omitted.

In the first active-energy ray irradiation process, the active energy ray is irradiated to the UV accumulated light quantity of (UVB) 10mJ / cm ² or more layers to be no more than 185mJ / cm ² unit 4 while passing through the roll 13 . Preferably, the active energy ray is irradiated with the accumulated light quantity of ultraviolet light (UVB) is presented 60mJ / cm ² or more than 175mJ / cm ^2. When the accumulated light quantity exceeds 185 mJ / cm ² , it is a cause of occurrence of wave unevenness in the polarizing plate. If the accumulated light quantity is less than 10 mJ / cm ² , then the accumulated light quantity of the active energy ray becomes large in the step of irradiating the active energy ray in the horizontal state (the second active energy ray irradiation step), and the curing shrinkage easily occurs, Wave culling is therefore likely to occur.

The light irradiation intensity for each active ray ray-curable adhesive is determined depending on the composition of the adhesive and is not particularly limited, but is preferably 10 to 5000 mW / cm ² . When the light irradiation intensity to the resin composition is less than 10 mW / cm ² , the reaction time becomes excessively long. When the light irradiation intensity exceeds 5000 mW / cm ² , heat radiated from the light source and heat generated during polymerization of the composition, There is a possibility that yellowing of the epoxy resin composition 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 .

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.

(Second active energy ray irradiation step)

When the accumulated energy of the active energy rays by the active energy ray irradiators 31 and 32 is insufficient, the second and subsequent active energy ray irradiators 16 to 18 are further provided, the active energy ray is further irradiated, It is preferable to accelerate the curing of the adhesive of the layered product 4. [ It is preferable that one active energy ray irradiation process and the sum of the accumulated light quantity of ultraviolet light (UVB) in a full step 10mJ / cm ² or more, particularly from 60 to 5,000mJ / cm ² are to be set. 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 leads to an improvement in productivity. 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 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, 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 "OPL film M-7500 (manufactured by Nippon Gosei)" 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 performed at a draw ratio of about 1.5 times while immersing in a dyeing bath containing an aqueous solution of iodine / potassium iodide / water in a weight ratio of 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 the transparent film, a cellulose acetate based resin film "KC4CR-1 (manufactured by Konica Minolta Opto)" with a retardation property of 40 탆 in thickness and a triacetyl cellulose film "KC8UX2MW" (manufactured by Konica Minolta Co., ) Were prepared.

Next, an epoxy resin composition " KR series " (manufactured by Adeka Corporation, including a cationic polymerization initiator), which is an ultraviolet (UVB) curing type adhesive, was applied on one side of a cellulose acetate based resin film " KC4CR- (Micro chamber doctor: manufactured by Fuji Machinery Co., Ltd.). An epoxy resin composition "KR series" (manufactured by Adeka Corporation, including a cation polymerization initiator), which is an ultraviolet (UVB) curing type adhesive, was applied to one side of the triacetyl cellulose film "KC8UX2MW" using the same adhesive coating apparatus . At this time, the gravure roll was rotated in the direction opposite to the conveying direction of the laminated material with the line speed of the polarizing film laminate in the adhesive coating device set at 25 m / min to adjust the thickness of the adhesive layer on the cellulose acetate resin film " KC4CR- About 4.0 mu m, and the thickness of the adhesive layer on the triacetyl cellulose film " KC8UX2MW " was about 3.3 mu m (total about 7.3 mu m).

Next, the acetic acid cellulose-based resin film "KC4CR-1" and the triacetyl cellulose film "KC8UX2MW" were bonded to both sides of the polarizing film with a nip roll through the epoxy resin composition (ultraviolet curable adhesive) Pressure 1.5 MPa).

The polarizing film to which the above two kinds of transparent films were bonded was fed at a line speed of 25 m / min while a tension of 600 N / m was applied in the longitudinal direction to the cooling roll, and a metal halide lamp 2 (GS-YUASA (Manufactured by Fusion Corporation, manufactured by Fusion Co., Ltd., electric power 130 W / cm, manufactured by Fuji Photo Film Co., Ltd.), and then the first active energy ray irradiation step was performed. 1, etc., 216 W / cm), and the second active energy ray irradiation step was performed to produce a polarizing plate.

The above-mentioned electrodeless D-valve lamp 3 etc. were arranged in three rows in the longitudinal direction of the film, in which six electrodeless D-valve lamps were arrayed in the film width direction.

At the time of passing through the metal halide lamp, the triacetyl cellulose film "KC8UX2MW" bonded to the polarizing film was brought into contact with the outer circumferential surface of a cooling roll set at 23 ° C and irradiated with ultraviolet rays from the cellulose acetate resin film "KC4CR-1" side . As a result, deterioration of the adhesive or the polarizing film due to the influence of heat in the first active energy ray irradiation step is suppressed.

In the first active energy ray irradiation step in the present embodiment, the total amount of accumulated ultraviolet rays in the metal halide lamp total 2 and the like was 172 mJ / cm ² . Further, in the second active energy ray irradiation step thereafter, the total amount of accumulated ultraviolet light in the total of Electrodeless D-valve Lamp No. 3 and the like was 296 mJ / cm ² . From the above, the total amount of accumulated ultraviolet light in the entire process of irradiating the active energy ray (first and second active energy ray irradiation processes) was 468 mJ / cm ² . The accumulated light quantity here is based on the measurement value of the light irradiation intensity in the wavelength range (UVB) of 280 to 320 nm (Power Puck II manufactured by FUJIFILM Corporation). There was no problem with the adhesion of the polarizer produced above.

(Appearance evaluation)

With respect to the polarizing plate produced as described above, the occurrence of wave non-uniformity and wave culling was evaluated by a reflection inspection of a fluorescent lamp. Specifically, when undulations were observed on the surface of the polarizing plate, it was evaluated as " wavy unevenness ", and when undulations were not confirmed, the wavy unevenness was evaluated as " When undulation of the entire polarizing plate was confirmed, it was evaluated as " presence of wave culling ", and when no undulation was confirmed, it was evaluated as " no wave culling ". The results are shown in Table 1.

[Example 2]

A metal halide lamp 3 or the like (produced by GS-Infant Industries, Ltd., a power amount of 60 W / cm 2 or the like) was passed through the first active energy ray irradiating step and then an electrodeless D valve lamp 1 10 ", a first power amount of 180 W / cm), and the second active energy ray irradiation step was performed. A polarizing plate was produced in the same manner as in Example 1 except for the above.

In the first active energy ray irradiation step in the present example, the total amount of accumulated ultraviolet rays in the metal halide lamp sum 3, etc. was 173 mJ / cm ² . Further, in the second active energy ray irradiation step thereafter, the total amount of cumulative light quantity of ultraviolet rays at the total of the first electrode of the electrodeless D-valve lamp was 63 mJ / cm ² . From the above, the total amount of accumulated ultraviolet light in the entire process of irradiating the active energy ray (first and second active energy ray irradiation processes) was 236 mJ / cm ² . The accumulated light quantity here is based on the measurement value of the light irradiation intensity in the wavelength range (UVB) of 280 to 320 nm (UV power mode II, manufactured by FUJIFILM Corporation). There was no problem with the adhesion of the polarizer produced above.

The appearance of the polarizing plate of Example 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]

A polarizing plate was produced in the same manner as in Example 1 except that the first active energy ray irradiation step was performed by passing through a metal halide lamp 1 (manufactured by GS-Infant Co., Ltd., electric power of 60 W / cm, Respectively.

In the first active energy ray irradiation step in the present example, the total amount of accumulated ultraviolet rays in the first half of the metal halide lamp was 20 mJ / cm ² . Further, in the second active energy ray irradiation step thereafter, the total amount of accumulated ultraviolet light in the total of Electrodeless D-valve Lamp No. 3 and the like was 296 mJ / cm ² . From the above, the total amount of accumulated ultraviolet light in the entire process of irradiating the active energy ray (first and second active energy ray irradiation processes) was 316 mJ / cm ² . The accumulated light quantity here is based on the measurement value of the light irradiation intensity in the wavelength range (UVB) of 280 to 320 nm (UV power mode II, manufactured by FUJIFILM Corporation). There was no problem with the adhesion of the polarizer produced above.

The polarizing plate of Example 3 was also evaluated for appearance in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]

A metal halide lamp 2 or the like (manufactured by GS-Infant Industries, Ltd., electric power of 140 W / cm) was passed through the first active energy ray irradiation step. A polarizing plate was produced in the same manner as in Example 1 except for the above.

In the first active energy ray irradiation step in this comparative example, the total amount of accumulated ultraviolet rays in the metal halide lamp sum 2 and the like was 191 mJ / cm ² . Further, in the second active energy ray irradiation step thereafter, the total amount of accumulated ultraviolet light in the total of Electrodeless D-valve Lamp No. 3 and the like was 296 mJ / cm ² . From the above, the total amount of accumulated ultraviolet light in the entire process of irradiating the active energy ray (first and second active energy ray irradiation processes) was 487 mJ / cm ² . The accumulated light quantity here is based on the measurement value of the light irradiation intensity in the wavelength range (UVB) of 280 to 320 nm (UV power mode II, manufactured by FUJIFILM Corporation). There was no problem with the adhesion of the polarizer produced above.

The appearance of the polarizing plate of Comparative Example 1 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]

A metal halide lamp 3 or the like (manufactured by GS-Infant Industries, Ltd., electric power of 100 W / cm) was passed through the first active energy irradiation step. A polarizing plate was produced in the same manner as in Example 2 except for the above.

In the first active energy ray irradiation step in this comparative example, the total amount of accumulated ultraviolet rays in the metal halide lamp sum 3, etc. was 289 mJ / cm ² . Further, in the second active energy ray irradiation step thereafter, the total amount of cumulative light quantity of ultraviolet rays at the total of the first electrode of the electrodeless D-valve lamp was 63 mJ / cm ² . From the above, the total amount of accumulated ultraviolet light in the entire process of irradiating the active energy ray (the first and second active energy ray irradiation processes) was 352 mJ / cm ² . The accumulated light quantity here is based on the measurement value of the light irradiation intensity in the wavelength range (UVB) of 280 to 320 nm (UV power mode II, manufactured by FUJIFILM Corporation). There was no problem with the adhesion of the polarizer produced above.

The appearance of the polarizing plate of Comparative Example 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]

The first active energy ray irradiation process is not performed but the second active energy ray irradiation is performed by passing through the ultraviolet ray irradiated from the electrodeless D valve lamp 3 or the like ("Light Hammer 10" manufactured by Fusion Corporation, the amount of electric power of 216 W / . A polarizing plate was produced in the same manner as in Example 1 except for the above.

In the second active energy ray irradiation step in this comparative example, the total amount of accumulated ultraviolet rays in the total of the electrodeless D-valve lamps 3 and the like was 296 mJ / cm ² , and the whole process of irradiating active energy rays Energy beam irradiation process) was 296 mJ / cm < ^{2 &} gt ;. The accumulated light quantity here is based on the measurement value of the light irradiation intensity in the wavelength range (UVB) of 280 to 320 nm (UV power mode II, manufactured by FUJIFILM Corporation). There was no problem with the adhesion of the polarizer produced above.

The appearance of the polarizing plate of Comparative Example 3 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

In Table 1, a blank ("-") indicates that there is no applicable. As shown in Table 1, with respect to the polarizing plates of Examples 1 to 3, there was no problem in adhesiveness, and no occurrence of wave nonuniformity or wave culling was confirmed. On the other hand, in Comparative Examples 1 and 2, occurrence of wave nonuniformity was confirmed, and in Comparative Example 3, wave curling was confirmed. From the above result, it was found that one can avoid, wavy unevenness and the occurrence of wave curling by the total amount of accumulated light quantity of the active energy ray irradiation process to less than 10mJ / cm ² over 185mJ / cm ^2.

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)
16, 17, 18, 31, 32, 33: an active energy ray irradiating device
19: Return nip roll
20: winding roll

Claims (5)

A method 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 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;
A bonding step of bonding the transparent film and the polarizing film by applying pressure to a laminated body in which the transparent film is laminated on one side or both sides of the polarizing film through the adhesive;
And a first active energy ray irradiation step of irradiating an active energy ray to the laminate to cure the adhesive while conveying the laminate in a state in close contact with a roll rotating in the carrying direction,
The first on the active energy ray irradiation process, ultraviolet rays (UVB) the cumulative dose 10mJ / cm ² over 185mJ / cm ² or less in the method for manufacturing a polarizing plate. The method of manufacturing a polarizing plate according to claim 1, wherein the roll is a cooling roll. The method of producing a polarizing plate according to claim 1 or 2, wherein at least one of said transparent films is a cellulose acetate resin film. The method according to any one of claims 1 to 3, further comprising a second activation energy ray irradiation step of irradiating an activation energy ray to the laminate after the first activation energy ray irradiation step to cure the adhesive , And a method for producing a polarizing plate. The method of manufacturing a polarizing plate according to any one of claims 1 to 4, wherein in the first active energy ray irradiation step, irradiation of the active energy ray is performed with a plurality of light sources.

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