TWI548897B - Method of manufacturing polarizing plate - Google Patents

Description

Method for manufacturing polarizing plate

The present invention relates to a method of manufacturing a polarizing plate which is used as one of optical parts constituting a liquid crystal display device or the like.

The polarizing film is widely used in the case of adsorbing a dichroic dye to a polyvinyl alcohol resin film, and it is known that iodine is used as an iodine-based polarizing film of a dichroic dye, and a dichroic direct dye is used as a dichroic dye. The dye is a polarizing film or the like. The polarizing film is usually formed by laminating a transparent film such as a triacetyl cellulose film on one surface or both surfaces thereof via an adhesive to form a polarizing plate.

A method of laminating a transparent film on one side or both sides of a polarizing film, and applying an active energy ray-curable resin to the surface of the transparent film in advance, and then applying a polarizing film and a transparent film to a pair of holding rollers (a bonding roller) a method in which the active energy ray is applied to the squeezing and squeezing, and the squeezing of the active energy ray is carried out. (Patent Document 1: JP-A-2004-245925, Patent Document 2: JP-A-2009-134190, and Patent Document 3: Japan JP-A-2011-95560).

However, as shown in Fig. 4 (a) and (b), by laminating the laminated body (polarizing film and transparent film) of the bonding rollers 51 and 52, the axial ends of the roller 51 are usually attached to one side. By pressing with a hydraulic pressure, air pressure, screw, etc. (such as the arrow of Fig. 4(b)), the center of the bonding roller 51 is bent, and the laminated body (polarizing film and transparent thin) The film) is subjected to uneven pressurization. In the case of uneven pressurization, bubbles are generated between the respective films in the obtained polarizing plate, and the adhesion between the films is deteriorated. Moreover, there is also a problem that the flow of the conveyance is deteriorated, and the manufacturing process is likely to cause an obstacle. Furthermore, such a phenomenon is a phenomenon in which a high pressure must be applied to the laminated body. In the case where an active energy ray-curable resin is used as the adhesive, it is necessary to apply a high pressure to the laminated body because the viscosity is high as compared with the case of using another polyvinyl alcohol-based resin or the like as an adhesive.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-245925

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2009-134190

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2011-95560

The present invention has been made to provide a method for producing a polarizing plate which can uniformly press a laminate (a polarizing film and a transparent film) constituting a polarizing plate, and a device for manufacturing a polarizing plate.

The present invention relates to a method for producing a polarizing plate comprising a transparent film bonded to one surface or both surfaces of a polarizing film, characterized in that the method includes the steps of: one side of the transparent film or one side or both sides of the polarizing film; An adhesive application step of applying an active energy ray-curable adhesive; and a laminated body formed by laminating the transparent film on one surface or both surfaces of the polarizing film via the adhesive, and rotating in a conveying direction Fitting roller a state in which at least one roller is pressed toward the other side of the bonding roller, and the transparent film is bonded to the polarizing film; and the laminated body is irradiated with an active energy ray to cause the adhesive The hardened active energy ray irradiation step; wherein one of the pair of bonding rollers is a crown roller having an outer circumferential shape which is tapered from a central portion toward an end portion.

It is not the aforementioned bonding roller of the aforementioned crown roller, and it is preferable to have a flat roller having a substantially uniform diameter.

In the bonding step, the shape of the crown roller is preferably designed such that the interval between the crown roller and the flat roller is substantially uniform in a state in which the pressing is performed.

The ratio of the difference between the diameter of the center portion of the crown roller and the diameter of the end portion is preferably 0.002% or more with respect to the length of the crown roller. Further, the tapered outer circumferential shape of the crown roller is preferably an arc shape.

Further, the external force of the pressing is preferably applied to both ends of the shaft of the bonding roller.

Further, the present invention relates to a device for manufacturing a polarizing plate comprising a transparent film bonded to one surface or both surfaces of a polarizing film, characterized in that it is provided on one surface of the transparent film or on one or both sides of the polarizing film. An adhesive application device for applying an active energy ray-curable adhesive; and a laminate in which the transparent film is laminated on one surface or both surfaces of the polarizing film via the adhesive, and is sandwiched while being conveyed. Bonding the roller to the transparent film and the polarizing film; and irradiating the laminated body with an active energy ray to activate the adhesive An energy ray irradiation device; wherein one of the pair of bonding rollers is a crown roller having a tapered outer circumferential shape formed by a diameter reduction from a central portion toward an end portion.

According to the present invention, it is possible to provide a method for producing a polarizing plate which can uniformly press a laminate (polarizing film and transparent film) constituting a polarizing plate, and a device for manufacturing a polarizing plate.

Further, according to the present invention, it is possible to obtain a polarizing plate which suppresses generation of bubbles between the respective films and deterioration of adhesion between the respective films. Moreover, it is possible to suppress the occurrence of an obstacle of the manufacturing step caused by the deterioration of the flow of the conveyance or the like.

1‧‧‧ polarizing film

2,3‧‧‧Transparent film

4‧‧‧Laminated body (polarizer)

11,12‧‧‧Binder coating device

13‧‧‧Roller (cooling roller)

14,15,16,17,18‧‧‧Active energy line irradiation device

19‧‧‧Transporting roller

20‧‧‧Rolling wheel

51‧‧‧Fitting roller (flat roller)

52‧‧‧Fitting roller (crown roller)

Fig. 1 is a schematic side view showing an embodiment of a manufacturing apparatus of a polarizing plate of the present invention.

Fig. 2 (a) and (b) are schematic side views showing an embodiment of a bonding roller used in the present invention.

Fig. 3 (a) and (b) are schematic perspective views for explaining wrinkles generated by the laminated body conveyed from the crown roller.

Fig. 4 (a) and (b) are schematic views for explaining a method of manufacturing a conventional polarizing plate.

(polarized film)

The polarizing film used in the polarizing plate of the present invention is specifically a polyvinyl alcohol-based resin film which is stretched on one axis, and the dichroic dye is adsorbed and oriented. The polyvinyl alcohol-based resin film can be obtained by saponification with a polyvinyl acetate-based resin. As a polyvinyl acetate-based resin, in addition to polyvinyl acetate of a vinyl acetate homopolymer, for example, a copolymer of vinyl acetate and other monomers copolymerizable therewith (for example, ethylene-vinyl acetate) Copolymer) and the like. Other monomers which can be copolymerized with vinyl acetate include, for example, 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, more preferably 90 mol% or more, and still more desirably 98 to 100 mol%. The average degree of polymerization of the polyvinyl alcohol-based resin is usually from 1,000 to 10,000, more preferably from 1,500 to 5,000. These polyvinyl alcohol-based resins may be modified, and for example, aldehyde-modified polyethylene formaldehyde, polyvinyl acetaldehyde, polyvinyl butyral or the like may be used.

A film made of such a polyvinyl alcohol-based resin is used as a raw material film of a polarizing film. The method of forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a conventionally known method. The film thickness of the raw material film composed of the polyvinyl alcohol-based resin is not particularly limited, and is, for example, about 10 to 150 μm . It is usually supplied in the form of a roll having a thickness in the range of 20 to 100 μm , preferably in the range of 30 to 80 μm , and an industrially practical width in the range of 500 to 6000 mm. In addition, a polyester film such as a polyolefin film or a PET film may be used as a substrate, and a polyvinyl alcohol resin may be applied to both surfaces or one surface thereof.

The commercially available polyvinyl alcohol-based film may, for example, be "Vinylon VF-PS #7500, Kuraray" and "OPL film M-7500, manufactured by Nippon Synthetic Co., Ltd." (raw material thickness is 75 μm ) , "Vinylon VF-PS #6000, Kuraray" and "Vinylon VF-PE #6000, Kuraray" (material thickness is 60 μ m), "Vinylon VF-PE #5000, Kuraray" (raw material) The thickness is 50 μm ), "Vinylon VF-PE #3000, Kuraray" (raw material thickness is 30 μm ).

The polarizing film is usually a step of adsorbing a dichroic dye by dyeing a polyvinyl alcohol-based resin film (dyeing step), and a polyvinyl alcohol-based resin film having a dichroic dye adsorbed thereon as an aqueous solution of boric acid. Processing step (boric acid treatment step And a step of washing with water after treatment with an aqueous solution of boric acid (water washing treatment step).

When the polarizing film is produced, the polyvinyl alcohol-based resin film is usually subjected to one-axis stretching, which may be performed before the dyeing treatment step, or in the dyeing treatment step, or after the dyeing treatment step. The one-axis extension is performed after the dyeing treatment step, which may be performed before the boric acid treatment step or in the boric acid treatment step. Of course, one-axis extension can also be performed at the stage of the plural.

The one-axis extension can be extended on one axis between the rollers of different rotational speeds, and can be extended on one axis using a hot roller. Further, it may be a dry stretching which is extended in the atmosphere, and may be a wet stretching in which the solvent is swollen. The stretching ratio is usually about 3 to 8 times.

In the dyeing treatment step, the polyvinyl alcohol-based resin film is dyed by a dichroic dye, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye, and the dichroic dye contains, for example, CI directly. A dichroic direct dye formed by a dichroic direct dye, a compound such as trisazo or tetrazo, formed by a bisazo compound such as red 39. Further, the polyvinyl alcohol-based resin film is preferably subjected to immersion in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine or potassium iodide and dyed is usually used. The content of iodine in the aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C, and the time (dyeing time) of immersing in the aqueous solution is usually 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in the aqueous solution is usually from 1 × 10 ^-4 to 10 parts by weight, more preferably from 1 × 10 ^-3 to 1 part by weight, particularly preferably from 1 × 10 ^-3 to 100 parts by weight per 100 parts by weight of water. 1 × 10 ^-2 parts by weight. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is usually 20 to 80 ° C, and the immersion time (dyeing time) of the aqueous solution is usually 10 to 1800 seconds.

The boric acid treatment step is carried out by immersing in a polyvinyl alcohol-based resin film dyed with a dichroic dye by immersing in an aqueous solution containing boric acid. The amount of boric acid in the aqueous solution containing boric acid is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye in the dyeing step, the aqueous solution containing boric acid used in the boric acid treatment step preferably contains potassium iodide. In this case, the amount of potassium iodide in the aqueous solution containing boric acid is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The time of immersion in the aqueous solution containing boric acid is usually 60 to 1200 seconds, more preferably 150 to 600 seconds, still more preferably 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 40 ° C or higher, more preferably 50 to 85 ° C, still more preferably 55 to 80 ° C.

In the subsequent washing step, the boric acid-treated polyvinyl alcohol-based resin film is subjected to a water washing treatment by, for example, immersing in water. The temperature of the water in the water washing treatment is usually 4 to 40 ° C, and the immersion time is usually 1 to 120 seconds. After the water washing treatment, drying treatment is usually carried out to obtain a polarizing film. The drying treatment is suitably carried out, for example, using a hot air dryer, a far infrared heater or the like. The temperature of the drying treatment is usually from 30 to 100 ° C, preferably from 50 to 80 ° C. The drying treatment time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

In this manner, the polyvinyl alcohol-based resin film was subjected to one-axis stretching, dyeing with a dichroic dye, boric acid treatment, and water washing treatment to obtain a polarizing film. The thickness of the polarizing film is usually in the range of 3 to 50 μm . Further, the film is not limited to the above method, and a film having a polarizing function produced by another method may be used as the polarizing film.

(transparent film)

In the present invention, a transparent film is bonded to one surface or both surfaces of the polarizing film. In the case where the transparent film is bonded to both surfaces of the polarizing film, each of the transparent films may be the same or different types of films.

The material constituting the transparent film may, for example, be a cycloolefin resin or a cellulose acetate resin, such as polyethylene terephthalate, polyethylene naphthalate or polybutylene terephthalate. As the ester resin, a polycarbonate resin, an acrylic resin such as polymethyl methacrylate (PMMA), an olefin resin such as polypropylene, or the like, a film material widely used in the art can be used.

The cycloolefin resin is, for example, a thermoplastic resin (also referred to as a thermoplastic cycloolefin resin) having a monomer unit containing a norbornene or a polycyclic norbornene-based monomer-based cyclic olefin (cycloolefin). . The cycloolefin resin may be a ring-opening polymer of the above cycloolefin or a hydrogenated product of a ring-opening copolymer of two or more kinds of cyclic olefins, and may be a cyclic olefin, a chain olefin, or an aromatic compound having a vinyl group. Addition polymer. Moreover, it is also effective to introduce a polar base.

In the case of using a copolymer of a cycloolefin and a chain olefin or/and an aromatic compound having a vinyl group, the chain olefin may, for example, be ethylene or propylene, and the aromatic compound having a vinyl group may be exemplified. Such as styrene, α-methyl styrene, aryl substituted styrene and the like. In such a copolymer, the monomer unit containing a cyclic olefin may be 50 mol% or less (more desirably 15 to 50 mol%). Especially using the ring In the case of a ternary copolymer of an olefin, a chain olefin, and an aromatic compound having a vinyl group, the monomer unit containing a cycloolefin may be in an amount smaller than the above. In such a terpolymer, a monomer unit containing a chain olefin, usually 5 to 80 mol%, has a monomer unit containing an aromatic compound of a vinyl group, and is usually 5 to 80 mol%.

For the cycloolefin resin, a commercially available product such as Topas (manufactured by Ticona Co., Ltd.), Arton (manufactured by JSR Corporation), ZEONOR (manufactured by Japan ZEON Co., Ltd.), ZEONEX (manufactured by Japan ZEON Co., Ltd.), and APL (for example) can be used. Mitsui Chemicals Co., Ltd., OXIS (manufactured by Okura Industrial Co., Ltd.), etc. When the film of the cycloolefin resin is used as a film, a conventional method such as a solvent casting method or a melt extrusion method is suitably used. Further, a commercially available film of a cycloolefin-based resin such as a film produced by a scavenging system such as Seena (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), or a ZEONOR film (manufactured by Optes) can be used. Product.

The cycloolefin-based resin film may be one-axis extension or biaxial extension. By extending, it is possible to impart an arbitrary retardation value to the cycloolefin-based resin film. The stretching is usually performed by continuously winding up the film roll while extending in the heating furnace toward the traveling direction of the roll (the longitudinal direction of the film), the direction perpendicular to the traveling direction (the width direction of the film), or both. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cycloolefin-based resin film to the glass transition temperature + 100 °C. The stretching ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

When the cycloolefin-based resin film is in a state of a wound roll, the films are next to each other, and there is a tendency that agglomeration tends to occur, and a protective film is usually bonded to form a roll. Further, the cycloolefin-based resin film is preferably subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment on the surface adjacent to the polarizing film because of poor surface activity. Among them, plasma treatment which is easier to implement, in particular, atmospheric piezoelectric slurry treatment and corona treatment are suitable.

The cellulose acetate-based resin refers to a partially or completely esterified product of cellulose, for example, a cellulose acetate, a propionate, a butyrate, or a mixed ester of these. More specifically, for example, a triacetonitrile cellulose film, a diethylcellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, or the like. As such a cellulose ester-based resin film, a commercially available product such as Fujitac TD80 (made by Fujifilm Co., Ltd.), Fujitac TD80UF (made by Fujifilm Co., Ltd.), and Fujitac TD80UZ (Fuji Film Co., Ltd.) can be suitably used. System), KC8UX2M (Konica Minolta), KC8UY (Konica Minolta), Fujitac TD60UL (Fuji Film), KC4UYW (Konica Minolta) System), KC6UAW (Konica Minolta (share) system) and so on.

Further, as the transparent film, a cellulose acetate-based resin film which imparts a phase difference is also suitably used. Such a commercially available product of a cellulose acetate-based resin film which imparts a phase difference, for example, WV BZ 438 (manufactured by Fuji Film Co., Ltd.), KC4FR-1 (manufactured by Konica Minolta Co., Ltd.), KC4CR-1 (Ke Nika Minolta (share) system, KC4AR-1 (Konica Minolta (share) system) and so on. Cellulose acetate, also known as acetaminophen, cellulose acetate.

These cellulose acetate-based resin films are easy to absorb water, and the water content of the polarizing plate affects the relaxation of the end portions of the polarizing plate. The water content when manufacturing the polarizing plate is closer to the storage environment of the polarizing plate, for example, the balance water content of the production line of the clean room and the storage warehouse of the roll is better, although it is also related to the composition of the laminated film, for example, 2.0 to 3.5%. More preferably, it is 2.5% to 3.0%. The value of the water content of the polarizing plate was measured by the dry weight method and the weight change after 105 ° C / 120 minutes.

The thickness of the transparent film used in the polarizing plate of the present invention is preferably thin, but when it is too thin, the strength is lowered and the workability is deteriorated. On the other hand, when it is too thick, there arises a problem that the transparency is lowered and the ripening time required after lamination is lengthened. Therefore, a suitable thickness of the transparent film is, for example, 5 to 200 μm , more preferably 10 to 150 μm , still more preferably 10 to 100 μm .

In order to improve the adhesion between the adhesive and the polarizing film and/or the transparent film, the polarizing film and/or the transparent film may be subjected to corona treatment, flame treatment, plasma treatment, ultraviolet treatment, primer coating treatment, Surface modification treatment such as saponification treatment.

The surface treatment such as anti-glare treatment, anti-reflection treatment, hard coating treatment, electrification prevention treatment, and anti-fouling treatment of the transparent film may be carried out alone or in combination of two or more kinds. Further, the transparent film and/or the transparent film surface protective layer may contain a UV absorber such as a diphenylketone compound or a benzotriazole compound, a phenyl phosphate compound or a phthalate compound. Plasticizer.

Further, the transparent film may have a function as a retardation film, a function as a brightness enhancement film, a function as a reflection film, a function as a semi-transmissive reflection film, a function as a diffusion film, and an optical function as an optical compensation film. Features. In this case, for example, an optical functional film such as a retardation film, a brightness enhancement film, a reflection film, a semi-transmissive reflection film, a diffusion film, or an optical compensation film may be laminated on the surface of the transparent film to have such a function and be transparent. The film itself can also impart this function. Further, the transparent film may have a plurality of functions such as a diffusion film having a function as a brightness enhancement film.

For example, the above-mentioned transparent film is subjected to the stretching treatment described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, and the like, and the function described as Japanese Patent No. 3168850 can be used to impart a function as a retardation film. The phase difference characteristic of the retardation film can be, for example, a range in which the front phase difference value is 5 to 100 nm, and the thickness direction retardation value is 40 to 300 nm. Further, in the above-mentioned transparent film, by forming a fine hole by a method as described in JP-A-2002-169025, JP-A-2003-29030, or by reflecting by reflection Two or more layers of the cholesteric liquid crystal layer having different core wavelengths can impart a function as a brightness enhancement film.

In the transparent film, a metal thin film is formed by vapor deposition, sputtering, or the like, and a function as a reflective film or a semi-transmissive reflective film can be imparted. The transparent film can be provided with a function as a diffusion film by applying a resin solution containing fine particles. In addition, the liquid crystal compound such as a disc-shaped liquid crystal compound is applied to the transparent film to be oriented, and a function as an optical compensation film can be imparted. Further, in the transparent film, a compound exhibiting a phase difference may be contained. Further, various optical functional films can be directly bonded to the polarizing film by using an appropriate adhesive. As a commercially available product of an optical functional film, for example, a brightness enhancement film such as DBEF (available from Sumitomo 3M Co., Ltd.), a viewing angle improving film such as WV film (made by Fujifilm Co., Ltd.), and Arton film (JSR) (share) system, ZEONOR film (made by Optes), Escena (made by Sekisui Chemical Industry Co., Ltd.), VA-TAC (Konica Minolta (share) system), SUMICALIGHT (Sumitomo Chemical Co., Ltd.) a retardation film or the like.

(active energy ray hardening type adhesive)

The polarizing film and the transparent film are bonded together via an active energy ray-curable adhesive. The active energy ray-curable adhesive may be 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, cationic polymerizability, and the like. Adhesive. However, the present invention is not limited to these, and various active energy ray-curable adhesives (organic solvent-based adhesives, hot-melt adhesives, solventless adhesives, and the like) used in the production of conventional polarizing plates can be used. The active energy ray-curable adhesive may, for example, be an adhesive containing an acrylic resin composition such as acrylamide, acrylate, urethane acrylate or epoxy acrylate.

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

A hydrogenated epoxy resin obtained by selectively performing a nuclear hydrogenation reaction by a polyhydroxy compound which is a raw material of an aromatic epoxy resin in the presence of a catalyst under pressure and subjected to a nuclear hydrogenation reaction. Obtained by the method of etherification. The aromatic epoxy resin may, for example, be a bisphenol epoxy such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, or diepoxypropyl ether of bisphenol S. Resin; phenolic novolak epoxy resin, cresol novolac epoxy resin, and phenolic epoxy resin such as hydroxybenzaldehyde phenol novolac epoxy resin; epoxypropyl ether of tetrahydroxyphenylmethane, tetrahydroxydiphenyl A polyfunctional epoxy resin such as a epoxidized propyl ether or an epoxidized polyvinyl phenol. Among the hydrogenated epoxy resins, a glycidyl ether of hydrogenated bisphenol A is preferred.

The alicyclic epoxy resin refers to an epoxy resin having one or more epoxy groups bonded to an alicyclic ring in the molecule. The term "epoxy group bonded to an alicyclic ring" means a bridged oxygen atom -O- of the structure shown by the following formula. In the following formula, m is an integer of 2 to 5.

The group in which the form of one or a plurality of hydrogen atoms in the above formula (CH ₂ ) _m is bonded to a compound having another chemical structure can be an alicyclic epoxy resin. One or a plurality of hydrogen atoms in the above formula (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. In the alicyclic epoxy resin, an epoxy resin having an epoxy cyclane (the above formula m=3) and an epoxycyclohexane (the above formula m) are used because of exhibiting good adhesion. =4) epoxy resin is ideal. Hereinafter, the alicyclic epoxy resin which is preferably used is specifically exemplified, but is not limited to these compounds.

(a) Epoxycyclohexanecarboxylic acid epoxycyclohexyl methyl ester represented by the following formula (I):

(wherein R ¹ and R ² independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms)

(b) an epoxycyclohexanecarboxylic acid ester of an alkanediol represented by the following formula (II):

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

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

(wherein R ⁵ and R ⁶ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20)

(d) Epoxycyclohexyl methyl ether of polyethylene glycol represented by the following formula (IV):

(wherein R ⁷ and R ⁸ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10)

(e) an epoxycyclohexyl methyl ether of an alkanediol represented by the following formula (V):

(wherein R ⁹ and R ¹⁰ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 2 to 20)

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

(wherein R ¹¹ and R ¹² independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms)

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

(wherein R ¹³ and R ¹⁴ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms)

(h) a vinylcyclohexene diepoxide represented by the following formula (VIII):

(wherein R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms)

(i) Epoxycyclopentyl ethers of the following formula (IX):

(wherein R ¹⁶ and R ¹⁷ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms)

(j) a dicyclooxytricyclodecane represented by the following formula (X):

(wherein R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

Among the alicyclic epoxy resins exemplified above, the following alicyclic epoxy resins are commercially available or the like, and it is preferred to use them for reasons such as ease of use.

(A) an esterified product of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid with (7-oxabicyclo[4.1.0]heptan-3-yl)methanol [in formula (I) a compound of R ¹ =R ² =H]; (B) 4-methyl-7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and (4-methyl-7-oxadiyl) Esters of cyclo[4.1.0]heptan-3-yl)methanol [compounds of formula (I), R ¹ =4-CH ₃ , R ² =4-CH ₃ ]; (C) 7-oxadi An ester of cyclo[4.1.0]heptane-3-carboxylic acid with 1,2-ethanediol [a compound of formula (II), R ³ = R ⁴ =H, n=2]; (D) ( An esterified product of 7-oxabicyclo[4.1.0]heptan-3-yl)methanol with adipic acid [compound of formula (III), R ⁵ =R ⁶ =H, p=4]; (E) An esterified product of (4-methyl-7-oxabicyclo[4.1.0]heptan-3-yl)methanol with adipic acid [in formula (III), R ⁵ =4-CH ₃ , R ⁶ =4 -CH ₃ , p=4 compound]; (F) (7-oxabicyclo[4.1.0]heptan-3-yl)methanol and 1,2-ethanediol etherate [at formula (V) , R ⁹ = R ¹⁰ = H, compound of r = 2].

The aliphatic epoxy resin may, for example, be a polyepoxypropyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. More specifically, it may, for example, be a di-epoxypropyl ether of 1,4-butanediol; a diepoxypropyl ether of 1,6-hexanediol; a triepoxypropyl ether of glycerol; Triepoxypropyl ether of methylolpropane; diepoxypropyl ether of polyethylene glycol; diepoxypropyl ether of propylene glycol; aliphatic polyols such as ethylene glycol, propylene glycol and glycerin, plus A polyepoxy propyl ether of a polyether polyol obtained by forming one or more kinds of alkylene oxides (ethylene oxide or propylene oxide).

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 the composition is usually from 30 to 3,000 g/equivalent, more preferably from 50 to 1,500 g/equivalent. When the epoxy equivalent is less than 30 g/equivalent, the flexibility of the composite polarizing plate after curing is lowered, and the strength is likely to decrease. On the other hand, when it exceeds 3,000 g / equivalent, there is a possibility that the compatibility with other components contained in the adhesive is lowered.

In the adhesive, from the viewpoint of reactivity, the curing reaction of the epoxy resin is preferably carried out using cationic polymerization. Therefore, it is hard as an active energy ray-curable adhesive. The epoxy resin composition is preferably formulated with a cationic polymerization initiator. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with an active energy ray such as visible light, ultraviolet rays, X-rays, or electron beams to initiate polymerization of an epoxy group. Hereinafter, a cationic polymerization initiator which generates a cationic species or a Lewis acid by irradiation with an active energy ray and initiates polymerization of an epoxy group is referred to as a "photocationic polymerization initiator".

The photocationic polymerization initiator is used to cure the adhesive by irradiation with an active energy ray, and may be hardened at room temperature. Since the heat resistance of the polarizing film or the need for bending due to expansion is reduced, the film can be favorably formed between the films. The next point is favorable. Further, the photocationic polymerization initiator is subjected to a catalytic action by light, and is excellent in storage stability and workability even when it is mixed in an epoxy resin.

The photocationic polymerization initiator may, for example, be an aromatic diazonium salt; an onium salt such as an aromatic onium salt or an aromatic onium salt; an iron-aromatic hydrocarbon complex or the like.

The aromatic diazonium salt may, for example, be benzenediazonium hexafluoroantimonate, benzodiazepine hexafluorophosphate or benzodiazepine hexafluoroborate. The aromatic onium salt may, for example, be diphenylphosphonium tetrakis(pentafluorophenyl)borate, diphenylphosphonium hexafluorophosphate, diphenylsulfonium hexafluoroantimonate or bis(4-mercaptobenzenesulfonate) hexafluorophosphate. Base) 錪 etc.

The aromatic onium salt may, for example, be triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)borate or 4,4'-bis ( Diphenyl sulfonium) diphenyl sulfide bis(hexafluorophosphate) salt, 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide bis(hexafluoroantimonate) salt , 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide bis(hexafluorophosphate), 7-[di(p-tolyl)indenyl]-2- Isopropyl thioxanthone hexafluoroantimonate, 7-[bis(p-tolyl)indolyl]-2-isopropylthioxanthone tetrakis(pentafluorophenyl)borate, 4-phenylcarbonyl-4'-diphenylanthracene Base-diphenyl sulfide hexafluorophosphate, 4-(p-tert-butylphenylcarbonyl)-4'-diphenylfluorenyl-diphenyl sulfide hexafluoroantimonate, 4-(p-- 3 butylphenylcarbonyl)-4'-bis(p-tolyl)indenyl-diphenyl sulfide tetrakis(pentafluorophenyl)borate.

The iron-aromatic complex may, for example, be xylene-cyclopentadienyl iron (II) hexafluoroantimonic acid, cumene-cyclopentadienyl iron (II) hexafluorophosphate or xylene-cyclopentane. Diene iron (II)-tris(trifluoromethylsulfonyl)methane or the like.

Commercially available products of these photo-cationic polymerization initiators are easily available, and are sold under the trade names such as "KAYALITE PCI-220" and "KAYALITE PCI-620" (manufactured by Nippon Kayaku Co., Ltd.), "UVI-6990". (made by Union Carbide Corporation), "ADEKA OPTOMER SP-150", and "ADEKA OPTOMER SP-170" (made by ADEKA Corporation), "CI-5102", "CIT-1370", "CIT-1682", " CIP-1866S", "CIP-2048S" and "CIP-2064S" (above Japanese Soda (share) system), "DPI-101", "DPI-102", "DPI-103", "DPI-105", MPI-103, MPI-105, BBI-101, BBI-102, BBI-103, BBI-105, TPS-101, TPS-102, TPS -103", "TPS-105", "MDS-103", "MDS-105", "DTS-102" and "DTS-103" (above Green Chemicals Co., Ltd.), "PI-2074" (Rhodia) Company system) and so on.

The photocationic polymerization initiator may be used alone or in combination of two or more. Among them, the aromatic ruthenium is preferred because it has ultraviolet ray absorbing properties in a wavelength region of 300 nm or more and has excellent hardenability, and can provide a cured product having good mechanical strength and adhesion strength.

The amount of the photocationic polymerization initiator to be added is usually 0.5 to 20 parts by weight, more 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. The amount of photocationic polymerization initiator, for epoxy resin When the amount is less than 0.5 part by weight in terms of 100 parts by weight, the hardening becomes insufficient, and the mechanical strength and the subsequent strength tend to be lowered. In addition, when the 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 ionic substance in the cured product increases, the hygroscopic property of the cured product becomes high, and the durability is lowered. possibility.

In the case of using a photocationic polymerization initiator, the curable epoxy resin composition may further contain a photosensitizer as needed. By using a photosensitizer to increase the reactivity of cationic polymerization, the mechanical strength and the strength of the cured product can be improved. The photo sensitizer may, for example, be a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo or a diazo compound, a halogen compound or a photoreductive dye.

More specific examples of the photosensitizer include benzoin methyl ether, benzoin isopropyl ether, and benzoin derivatives such as α,α'-dimethoxy-α-phenylacetophenone; diphenyl ketone, 2 , 4-dichlorodiphenyl ketone, methyl o-benzoyl benzoate, 4,4'-bis(dimethylamino)diphenyl ketone and 4,4'-bis(diethylamine) a diphenyl ketone derivative such as diphenyl ketone; a thioxanthone derivative such as 2-chlorothiazinone or 2-isopropylthioxanthone; 2-chloroindole and 2-methylindole Anthracene derivatives such as hydrazine; acridine derivatives such as N-methylacridone and N-butylacridone; other α,α-diethoxyacetophenone, diphenylethylenedione, anthrone (Fluorenone), Xanthone, uranium compounds, halogen compounds, and the like. The light sensitizer may be used alone or in combination of two or more. The light sensitizer is preferably contained in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the curable epoxy resin composition.

The epoxy resin contained in the adhesive is hardened by photocationic polymerization, and can be hardened by photocationic polymerization and thermal cationic polymerization. In the latter case, it is preferred to use a photocationic polymerization initiator and a thermal cationic polymerization initiator in combination.

The thermal cationic polymerization initiator may, for example, be benzyl hydrazine, thiophenium, thiolanium, benzylammonium, pyridinium, hydrazinium or carboxy. Acid esters, sulfonates, amine imines, and the like. These thermal cationic polymerization initiators are easily available as commercially available products, and such as "Adeka opton CP77" and "Adeka opton CP66" (made by Adeka Co., Ltd.), "CI-2639" and "CI- 2624" (manufactured by Soda Corporation), "Sunaid SI-60L", "Sunaid SI-80L" and "Sunaid SI-100L" (manufactured by Sanshin Chemical Industry Co., Ltd.).

The active energy ray-curable adhesive may further contain a compound which promotes cationic polymerization such as oxetane or polyalcohol.

The oxetane is a compound having a 4-membered cyclic ether in the molecule, and may, for example, be 3-ethyl-3-hydroxymethyloxetane or 1,4-bis[(3-ethyl-3) -oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, bis[(3-ethyl-3-oxetanyl) ) methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, phenol novolac oxetane, and the like. These oxetanes are easily available as commercially available products, such as "Aron oxetane OXT-101", "Aron oxetane OXT-121", "Aron oxetane OXT-211", "Aron". Oxetane OXT-221" and "Aron oxetane OXT-212" (above East Asia Synthetic Co., Ltd.). The oxetanes usually have a ratio of from 5 to 95% by weight, more preferably from 30 to 70% by weight, based on the curable epoxy resin composition.

The polyalcohol is preferably an acid group other than a phenolic hydroxyl group, and may be a polyalcohol compound having no functional group other than a hydroxyl group, a polyester polyol compound, or a polycaprolactone polyalcohol compound. A phenolic hydroxyl group polyol compound, a polycarbonate polyol, or the like. The molecular weight of the polyalcohols is usually 48 or more, and more preferably 62. The above is more preferably 100 or more, and more preferably 1000 or less. These polyhydric alcohols usually contain 50% by weight or less, and more preferably 30% by weight or less, in the curable epoxy resin composition.

An active energy ray-curable adhesive can be further formulated with an ion scavenger, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow regulator, a leveling agent, a plasticizer, an antifoaming agent, etc. additive. The ion scavenger may, for example, be an inorganic compound such as a powdery lanthanoid, lanthanide, magnesium, aluminum, calcium, titanium or such mixed system, and examples of the antioxidant include hindered phenolic compounds. Antioxidants, etc.

As the active energy ray-curable adhesive, a solventless adhesive which does not substantially contain a solvent component can be used, and a solvent may be contained for adjusting the viscosity in order to have a suitable viscosity range for various coating methods. The solvent is preferably an organic solvent such as a hydrocarbon represented by toluene or an ester represented by ethyl acetate, which is preferably used to dissolve the epoxy resin composition without lowering the optical characteristics of the polarizing film. 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, more preferably in the range of 10 to 200 mPa ‧ s, more preferably 20 to 100 mPa ‧ s range.

<Method of Manufacturing Polarizing Plate>

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

The manufacturing apparatus 30 for a polarizing plate shown in Fig. 1 is provided in order to apply an adhesive to the adhesive coating apparatuses 11 and 12 for one surface of the transparent films 2 and 3 in the transport direction; The film 2, 3 and the polarizing film 1 are bonded to the laminated body 4 a wheel (clamping roller) 51, 52; a roller 13 for adhering the transparent film 2, 3 to the polarizing film 1 to the laminated body 4; and a first active energy ray irradiation at a position relative to the outer circumferential surface of the roller 13 The devices 14, 15; the second and subsequent active energy ray irradiation devices 16 to 18 disposed on the downstream side in the transport direction; and the transport nip roller 19.

First, an active energy ray-curable adhesive (adhesive coating step) is applied to one surface of the transparent films 2 and 3 which are continuously discharged from the state of the roll by the adhesive application devices 11 and 12.

Then, the transparent film 2 and 3 coated with the adhesive agent are applied to both surfaces of the polarizing film 1 continuously discharged from the state of the roll, and the laminated body formed by laminating the adhesive layer is rotated in the conveying direction. In a state between the bonding rollers 51 and 52, the polarizing film 1 and the transparent films 2 and 3 are bonded together by pressing at least one roller toward the bonding roller on the other side to form a laminated body 4 Step by step).

Then, the layered body 4 is conveyed while being in close contact with the outer circumferential surface of the roller 13, and the active energy ray is irradiated from the first active energy ray irradiation devices 14 and 15 toward the outer circumferential surface of the roller 13 to cure the adhesive. (Active energy ray irradiation step).

In addition, the second and subsequent active energy ray irradiation devices 16 to 18 disposed on the downstream side in the transport direction are devices for completely curing and curing the adhesive, and may be added or omitted as necessary. Finally, the laminated body 4 is taken up by the take-up reel 20 by the conveyance holding roller 19 as a polarizing plate. Hereinafter, each step will be described in detail.

(adhesive coating step)

The method of applying the adhesive to the transparent films 2 and 3 is not particularly limited, and for example, various coatings such as a doctor blade, a wire bar, a slit coater, a comma coater, and a gravure coater can be used. the way. Among them, in view of the film coating, the degree of freedom of the path line, the correspondence of the width, and the like, it is preferable that the adhesive coating devices 11 and 12 are intaglio rollers. Make A commercially available coating device is, for example, MCD (Micro Chamber Doctor) manufactured by Fuji Machinery Co., Ltd., or the like.

When a gravure roll is used as the adhesive application means 11, 12, when the adhesive is applied, the thickness (coating thickness) of the applied adhesive is preferably about 0.1 to 10 μm , more preferably 0.2 μ. m to 4 μ m. The coating thickness of the subsequent agent is adjusted according to the linear ratio of the linear velocity of the transparent film to the speed of the intaglio roller. Generally, the draw ratio (speed/line speed of the intaglio roller) is adjusted to 0.5 to 10, and the coating thickness of the adjustable adhesive is about 0.1 to 10 μm . More specifically, the linear speed of the transparent films 2, 3 is 10 to 100 m/min, and the intaglio roller rotates in the opposite direction to the conveying direction of the transparent films 2, 3, and the speed of the intaglio roller is 5 to 1000 m/min. The coating thickness of the adhesive is adjusted to be about 0.1 to 10 μm .

After the agent is prepared, it is usually adjusted to ±5 ° C at a predetermined temperature in the range of 15 to 40 ° C (for example, 30 ° C ± 5 ° C when the predetermined temperature is 30 ° C), more preferably ± 3 ° C, more preferably Coating at ±1 °C.

(Fitting step)

In this step, the transparent films 2 and 3 coated with the adhesive agent in the above step are laminated on the both surfaces of the polarizing film 1 which are continuously discharged from the state of the roll. The laminated body is pressed between the pair of bonding rollers 51 and 52 that are rotated in the conveying direction, for example, the bonding roller 51 is pressed in the direction of the bonding roller 52, and the polarizing film 1 and the transparent films 2 and 3 are attached. The laminated body 4 is formed. In this case, the direction in which the polarizing film is conveyed is preferably an angle within a range of ±3° in a direction perpendicular to the pressing direction of the bonding roller, and more preferably an angle within a range of ±1°, and the polarizing film is attached to the roller. Transfer between. It is particularly preferable that the polarizing film is transferred between the bonding rollers so that the conveying direction of the polarizing film overlaps the surface perpendicular to the pressing direction of the bonding roller. Thereby, the polarizing film and the transparent film are It is in contact with the front of the roller and does not generate air bubbles.

Further, in Fig. 1, although the adhesive is uniformly applied to one surface of the transparent films 2 and 3, the surface of the transparent film 2, 3 to which the adhesive is applied overlaps with the polarizing film 1, and the roller is bonded. In the method of bonding 51 and 52, the adhesive may be uniformly applied to both surfaces of the polarizing film 1, and the surface of the polarizing film 1 coated with the adhesive may be overlapped with the transparent films 3 and 2 by the bonding roller 51. , 52 fit.

The present invention is characterized in that one of the pair of bonding rollers 51 and 52 is a crown roller having an outer circumferential shape which is tapered from the central portion toward the end portion. That is, the radius of the central portion of the crown roller is larger than the radius of the end portion. A non-crown roller, usually a flat roller with a substantially uniform diameter.

The shape of the crown roller is designed to be pressed in the bonding step, so that the interval between the crown roller and the flat roller is substantially uniform. Here, the distance between the crown roller and the flat roller refers to the interval between the crown roller and the outer circumference of the flat roller in the cross section including the axis of the crown roller and the axis of the flat roller. Further, in general, the crown roller and the flat roller are disposed so that the axis of the crown roller is parallel to the axis of the flat roller without being pressed.

For example, as shown in Fig. 2(a), the bonding roller 51 is a metal flat roller, and the bonding roller 52 is a rubber crown roller. As shown by the arrow in Fig. 2(b), the flat roller 51 is shown. Both ends of the shaft exert an external force in the direction of the crown roller 52. Since the crown roller 52 is bent in a state in which the pressing is performed, and the interval between the crown roller 52 and the flat roller 51 is substantially uniform, the shape of the crown roller 52 is designed, so that the laminated body can be uniformly pressurized ( Figure 2 (b)). In addition, in the second drawing, the case where the flat roller 51 is pressed in the direction of the crown roller 52 is shown, but the same can be obtained when the crown roller 52 is pressed in the direction of the flat roller 51. effect. Moreover, both the flat roller 51 and the crown roller 52 can also be pressed in a direction in which they approach each other.

The ratio of the difference between the diameter of the center portion of the crown roller and the diameter of the end portion is preferably 0.002% or more with respect to the length (length in the axial direction) of the crown roller. More preferably, it is 0.005 to 0.040%. Generally, in the range of the ratio, the shape of the crown roller can be designed to be uniform in the state in which the crown roller and the flat roller are pressed in the state of being pressed in the bonding step.

Further, the tapered outer circumferential shape of the crown roller is preferably an arc shape. Here, the tapered outer circumferential shape of the crown roller is an arc shape, and the cross section of the crown roller including the surface of the tapered outer circumferential shape is an arc. In the bonding step, when the shaft member of the flat roller is pressed, the outer circumferential shape of the flat roller is curved in an arc shape, and the outer circumferential shape of the opposing crown roller is a circle having the same degree of curvature radius. The arc shape can make the interval between the opposing bonding rollers (the crown roller and the flat roller) uniform, and the polarizing film and the transparent film can be bonded under a uniform pressure.

The diameter of the fitting roller is not particularly limited, and the diameter of the flat roller is preferably 50 to 400 mm. Moreover, the diameter of the end of the crown roller is preferably 50 to 400 mm. Furthermore, the individual diameters of the pair of bonding rollers may be the same or different. The width of the fitting roller is preferably 300 to 3000 mm.

The pressure applied to the laminated body by the pressing is not particularly limited, and when a metal roller and a rubber roller are used, the instantaneous pressure of the two-piece press box (for ultra low pressure) made of Fuji film is 0.5 to 3.0 MPa. Ideally, it is more preferably 0.7 to 2.3 MPa. In the present invention, the external force applied to the bonding roller is usually applied to both ends of the shaft to which the roller is attached, via a bearing or the like.

The material of the bonding roller is, for example, metal or rubber. One of the pair of bonding rollers is a metal roller, and the other is a rubber roller. Furthermore, the flat roller is made of metal, and the crown roller is made of rubber.

In the conventional bonding roller, the upper bonding roller that is usually pressed is made of rubber, and the lower bonding roller is made of metal. This is because the lower side of the bonding roller is provided with a driving motor for controlling the rotation speed, and the lower side of the bonding roller is made of metal. When the pressing roller is pressed, the lower side of the bonding roller is not deformed, and the circumferential speed of the bonding roller is easily maintained. for sure. However, in this case, in order to facilitate the adjustment of the curl, in the present invention, the pressing roller (the upper side) is made of metal, and the other (lower side) bonding roller is preferably made of rubber.

As the base material of the metal roller, various conventional materials can be used, and stainless steel is preferable, and SUS304 (containing 18% chromium and 8% nickel stainless steel) is more preferable. It is preferable to perform chrome plating on the surface of the metal roller.

The material of the rubber roller is not particularly limited, and is, for example, NBR (nitrile rubber), Titan, urethane, hydrazine, EPDM (ethylene-propylene-diene rubber), etc., preferably NBR, Titan, Ethyl carbamate. The hardness of the rubber roller is not particularly limited and is usually 60 to 100°, more preferably 85 to 95°. Further, the hardness of the rubber roller can be measured by a hardness meter according to JIS K6253. As a commercially available hardness tester, for example, a rubber hardness tester "A type" manufactured by ASKA Corporation or the like is used. Specifically, when the surface was pressed with a rod, the surface resistance of the rubber roller was measured with a durometer.

When the crown roller is used as the bonding roller, it is preferable to maintain the high tension for the laminated body, for example, 300 to 800 N/m. In this case, as shown in FIG. 3(b), the laminated body 4 conveyed from the crown roller 52 does not cause wrinkles, and when the tension of the laminated body 4 is lower, as shown in FIG. 3(a), The laminated body 4 conveyed from the crown roller 52 is prone to wrinkles.

The peripheral speed of the bonding roller (first bonding roller) provided on the surface side of the liquid crystal panel, and the circumferential speed of the bonding roller (second bonding roller) on the opposite side is preferably faster. Thereby, the obtained polarizing plate can be made convex, and the surface on the opposite side becomes convex curved (positive bending). In the obtained polarizing plate, the surface to be bonded to the liquid crystal panel is concave, and the surface on the opposite side is convexly curved (reversely bent). When the polarizing plate is bonded to the liquid crystal cell, the central portion is liable to cause biting. Bad conditions such as bubbles. In this case, it is preferable to use a metal roller as the first bonding roller and a rubber roller as the second bonding roller.

Further, when the peripheral speed of the second bonding roller is 1, the ratio of the peripheral speed of the first bonding roller is preferably 1.050 to 1.0200. When the circumferential speed of the first bonding roller is faster than the range, the amount of bending of the positive bending becomes too large, and when the polarizing plate is bonded to the liquid crystal cell, a problem such as biting bubbles is likely to occur at the end portion, and further, In a harsh environment, the positive bending is further promoted, and the end of the polarizing plate may be peeled off from the liquid crystal cell.

The roller 13 has an outer circumferential surface which is formed as a convex curved surface of the mirror surface, and is conveyed in a state in which its surface is in close contact with the laminated body 4, and in the process, the adhesive is hardened by the active energy ray irradiation means 14, 15. . When the adhesive is polymerized and cured, the laminated body 4 is sufficiently adhered, and the diameter of the roller 13 is not particularly limited. It is preferable that the laminated body 4 in which the adhesive is not cured is irradiated with an active energy ray so that the cumulative amount of light passing between the rollers 13 is 10 mJ/cm ² or more. The roller 13 can be moved with the line of the laminated body 4, or can be driven by rotation, or can be fixed while the laminated body 4 is slid over its surface. Further, when the roller 13 is polymerized and cured by irradiation with an active energy ray, it can also function as a cooling roller for releasing heat generated by the laminated body 4, and in this case, the surface temperature of the cooling roller is set to 4 It is ideal to 30 °C.

(active energy ray irradiation step)

The light source used for the polymerization hardening of the adhesive agent by irradiation with the active energy ray is not particularly limited, and a light source having a light-emitting distribution of a wavelength of 400 nm or less is preferable. As such a light source, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black lamp, a microwave excited mercury lamp, or a metal halide lamp can be exemplified.

The light irradiation intensity of the active energy ray-curable adhesive is determined by the composition of each adhesive, and is not particularly limited, and is preferably from 10 to 5,000 mW/cm ² . When the light irradiation intensity of the resin composition is less than 10 mW/cm ² , the reaction time becomes too long, and when it exceeds 5000 mW/cm ² , an adhesive may be generated due to radiant heat from the lamp and heat generation during polymerization of the composition. The yellowing of the epoxy resin composition or the like of the constituent material and the deterioration of the polarizing film. Further, the irradiation intensity is preferably an intensity in a wavelength region effective for activation of the photocationic polymerization initiator, more preferably a wavelength region having a wavelength of 400 nm or less, and more preferably a wavelength region of a wavelength of 280 to 320 nm. strength.

The irradiation time of the active energy ray of the active energy ray-curable adhesive is controlled by each hardened composition, and is not particularly limited. The cumulative light amount expressed by the product of the irradiation intensity and the irradiation time is set to 55 mJ/cm ^{2 .} Above, it is preferably 55 to 5,000 mJ/cm ² . When the cumulative amount of the above-mentioned adhesive agent is less than 55 mJ/cm ² , the generation of the active species from the initiator is insufficient, and the hardening of the adhesive is insufficient, and the wave-side relaxation defects may occur at both end portions of the polarizing plate. On the other hand, when the cumulative light amount exceeds 5,000 mJ/cm ² , the irradiation time becomes extremely long, which is disadvantageous in improving productivity. At this time, depending on the film to be used, the combination of the types of the adhesive, and the like, it is required to have different wavelengths (UVA (320 to 390 nm)), UVB (280 to 320 nm), and the like.

In the present invention, the layered body is irradiated with an active energy ray to cure and cure the adhesive. It is also possible to use a polymerization hardening by heating.

In the case where the active energy ray is ultraviolet ray, the step of irradiating the laminated body with the active energy ray is applied to the laminated body 4 with a tension of 100 to 800 N/m in the longitudinal direction (transport direction), and the irradiation time is 0.1 second. It is preferable to transmit the laminated body 4 at the above linear velocity. Further, the irradiation intensity of ultraviolet rays is preferably 10 mW/cm ² or more.

When the accumulated light amount of the active energy ray of the active energy ray irradiation devices 14 and 15 is insufficient, the second and subsequent active energy ray irradiation devices 16 , 17 , and 18 are additionally provided, and the active energy ray is additionally irradiated to promote the laminated body 4 . The hardening of the adhesive is ideal. The cumulative light amount of all of the steps is set to 55 mJ/cm ² or more, preferably 55 to 5,000 mJ/cm ² . Thus, in the step of irradiating the active energy ray, it is preferred that the irradiation of the active energy ray is divided into a plurality of times.

In order to ensure the hardening of the adhesive agent at the edge of the polarizing plate (layered body), a method of arranging the film by the method of "light Hammer 10" made of FUSION of the electrodeless D bulb is exemplified. .

The curing ratio of the active energy ray-curable resin, that is, the reaction rate is preferably 90% or more, more preferably 95% or more.

(Polarizing plate winding step)

The tension of the wound laminated body (polarizing plate) 4 is not particularly limited, and is preferably in the range of 30 to 150 N/cm ² and more preferably in the range of 30 to 120 N/cm ² . When the tension of the wound laminated body 4 is less than 30 N/cm ² , when the long roll is moved, the winding deviation is caused, and when it is larger than 150 N/cm ² , the winding is not smooth, and there is a strong It tends to cause slack.

In addition, the longer the length of the roll is, the more the winding is likely to be unsatisfactory in the same tension (the phenomenon that it is difficult to return to a flat state when unwinding), and the polarizing plate can be wound continuously to the core while being continuously or stepwise. tension. In this way, a so-called tapered shape and a method of reducing the tension are applied, and the tension at this time is also 150 N/cm ² or less.

The length of the polarizing plate taken up from the core is not particularly limited, and is preferably 100 to 4000 m or less.

The diameter of the cylindrical core is preferably 6 to 12 inches. The diameter of the core is larger, and the 11吋, 12吋, etc. are more desirable. In the case of too large, there is a tendency to move and store.

The material of the cylindrical core is not easy to dust due to its use in a clean room. As long as the polarizing plate with a wide winding width can be ensured at an appropriate strength, there is no particular limitation, and FRP (glass) can be selected. Fiber reinforced plastic).

[Examples]

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

[Example 1] (production of polarizing film)

As a raw material film of polyvinyl alcohol, a long-length polyvinyl alcohol film "VINYLON VF-PS #7500 (manufactured by Kuraray)" having a polymerization degree of 2,400, a saponification degree of 99.9 mol%, a thickness of 75 μm , and a width of 3000 mm was used. The extension is performed by imparting a peripheral speed difference to the drive nip rollers before and after the treatment tank.

First, the raw material film is not slackened, and the film is kept in a state of tension. The film is immersed in a swelling tank of pure water at 30 ° C for 80 seconds to sufficiently swell the film. With the swelling of the swelling tank, the speed ratio of the inlet to the outlet roller is 1.2. . After the water was removed by the nip roller, it was immersed in a water immersion tank of 30 ° C pure water, and immersed for 160 seconds. In this groove, the stretching ratio of the machine direction is 1.09 times.

Then, while immersing in a dyeing bath containing an aqueous solution containing iodine/potassium iodide/water (weight ratio: 0.02/2.0/100), one-axis extension was carried out at a stretching ratio of about 1.5 times. Then, it was immersed in a boric acid bath containing an aqueous solution of potassium iodide/boric acid/water (weight ratio: 12/3.7/100) at 55.5 ° C for 130 seconds, and subjected to one-axis stretching so that the cumulative stretching ratio from the raw material was 5.7 times. Then, it was immersed in a boric acid bath of an aqueous solution of potassium iodide/boric acid/water (weight ratio: 9/2.4/100) at 40 ° C for 60 seconds.

Furthermore, it was washed in pure water at 8 ° C for about 16 seconds in a water washing tank, and then dried in a drying oven at about 60 ° C in a drying oven at about 85 ° C in order, and the residence time in the drying furnaces. The total is 160 seconds. Thus, a polarizing film having a thickness of 28 μm oriented by iodine adsorption was obtained.

(production of polarizing plate)

As a transparent film, a cycloolefin resin film "Zeonor" (manufactured by Zeon Co., Ltd.) having a thickness of 75 μm and a triacetone cellulose film "KC8UX2MW" (manufactured by Konica Minolta Co., Ltd.) having a thickness of 80 μm were used. .

Then, on one side of the cycloolefin-based resin film "Zeonor" having a thickness of 75 μm , an epoxy resin composition of an ultraviolet curing adhesive was applied using an adhesive application device (Micro Chamber Doctor: manufactured by Fuji Machinery Co., Ltd.). (including a cationic polymerization initiator) "KR series" (made by Adeka Co., Ltd.). Further, an epoxy resin composition (including a cationic polymerization initiator) of an ultraviolet curable adhesive was applied to one surface of the above-mentioned 80 μm-thick triethylene cellulose film "KC8UX2MW" using the same adhesive application device. "KR Series" (made by ADEKA). In this case, the linear velocity of the polarizing film laminate in the adhesive application device was 25 m/min, and the intaglio roller was rotated in a direction opposite to the direction in which the laminated material was conveyed, and the cycloolefin resin film having a thickness of 75 μm was "Zeonor". The thickness of the adhesive layer on the triethylcellulose film "KC8UX2MW" having a thickness of about 3.5 μm is about 3.5 μm , and the thickness of the adhesive layer on the thickness of 80 μm is about 3.5 μm .

Then, on the both surfaces of the polarizing film, a cycloolefin resin film "Zeonor" having a thickness of 75 μm and a triacetonitrile cellulose film "KC8UX2MW" having a thickness of 80 μm were interposed between the epoxy resin composition (ultraviolet rays). a hardened type of adhesive), one of which is a flat roller made of metal (200 mm in diameter), and the other is a ratio of the difference between the diameter of the center portion and the diameter of the end portion, which is made of rubber of 0.015% with respect to the length of the roller. One of the crown rollers (the diameter of the center is 200 mm, the diameter of the end is 199.8 mm, and the length is 1300 mm) is applied to the roller, and the external force of the pressing force is applied to both ends of the shaft to perform the bonding.

The polarizing film to which the above two kinds of transparent films were bonded was adhered to a cooling roller having a tensile force of 600 N/m in the longitudinal direction, and moved at a linear velocity of 25 m/min to pass the longitudinal direction of the film. The first active energy ray is irradiated in an ultraviolet ray irradiated by a rod-shaped metal halide lamp 2 (a power of 100 W/cm per unit length manufactured by GS-YUASA Co., Ltd.) disposed in a film transport direction. After the irradiation step, the electrodeless D bulb 6 (the "Light Hammer 10" manufactured by Fusion Co., Ltd., and the electric power per unit length of 216 W/cm) is continuously irradiated through the film in the width direction of the film. In the middle, the second active energy ray irradiation step is performed to prepare a polarizing plate.

When a metal halide lamp is used, the triacetyl cellulose film "KC8UX2MW" having a thickness of 80 μm bonded to the polarizing film is brought into contact with the outer circumferential surface of the cooling roller at 23 ° C, and a cycloolefin system having a thickness of 75 μm is used. The "Zeonor" side of the resin film is irradiated with ultraviolet rays. Thereby, the deterioration of the adhesive and the polarizing film caused by the influence of the heat of the first active energy ray irradiation step is suppressed.

(The clamping pressure distribution of the bonding roller and the evaluation of the bubble of the polarizing plate)

When the pressure of the pair of bonding rollers used in the first embodiment was measured using a pressure measuring film (a pressure gauge made of Fuji film, a two-piece type, and an ultra low pressure), the distribution of the nip pressure was almost uniform in the width direction. Further, when the produced polarizing plate was evaluated, no bubbles were observed. The results are shown in Table 1.

[Embodiment 2]

In the present embodiment, one is a flat roller (a diameter of 300 mm) made of metal, and the other is a rubber crown roller having a ratio of a difference between the diameter of the center portion and the diameter of the end portion to the length of the roller of 0.008%. (The center portion has a diameter of 300 mm, the end portion has a diameter of 299.89 mm, and the length is 1300 mm.) One of the pair of bonding rollers applies an external force to the both ends of the shaft to perform clamping. In the same manner as in Example 1, a polarizing plate was produced.

(The clamping pressure distribution of the bonding roller and the evaluation of the bubble of the polarizing plate)

When the nip pressure of the bonding roller used in Example 2 was measured using a pressure measuring film (a pressure gauge of Fujifilm to two sheets, and an ultra low pressure), the distribution of the nip pressure was almost uniform in the width direction. Further, when the produced polarizing plate was evaluated, no bubbles were observed. The results are shown in Table 1.

[Comparative Example 1]

In the comparative example, one was made of a flat roller made of metal, and the other was a flat roller made of rubber, and one of the diameters of 200 mm was attached to the roller, and an external force of pressing was applied to both ends of the shaft to perform clamping. In the same manner as in Example 1, a polarizing plate was produced.

(The clamping pressure distribution of the bonding roller and the evaluation of the bubble of the polarizing plate)

The clamping pressure of the bonding roller used in Comparative Example 1 was measured using a pressure measuring film. (When the pressure film of Fujifilm is used, the two-piece type, and the ultra low pressure), the distribution of the nip pressure is almost uniform in the width direction. Further, when the produced polarizing plate was evaluated, bubbles were observed. The results are shown in Table 1.

From the above results, it has been found that by using one of the pair of bonding rollers as the crown roller, uniform pressurization becomes possible, and a polarizing plate having no problem in quality without generating bubbles can be produced.

[Industry use possibility]

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

51‧‧‧Fitting roller (flat roller)

52‧‧‧Fitting roller (crown roller)

Claims (8)

A method for producing a polarizing plate, which is a method for producing a polarizing plate in which a transparent film (2, 3) is bonded to one or both sides of a polarizing film (1), and is characterized in that it has the following steps: 2, 3) single side or the polarizing film (1) on one or both sides, the coating viscosity is 1000mPa. An adhesive application step of an active energy ray-curable adhesive of s or less; a laminate formed by laminating the transparent film (2, 3) on one side or both sides of the polarizing film (1) via the adhesive ( 4) pressing the at least one bonding roller in the direction of the bonding roller on the other side in a state of being sandwiched between the pair of bonding rollers (51, 52) that are rotated in the conveying direction to fit the transparent film a step of bonding (2, 3) to the polarizing film (1); and an active energy ray irradiation step of irradiating the layered body (4) with an active energy ray to cure the adhesive through the bonding step; One of the pair of bonding rollers (51, 52) is a crown roller (52) having a tapered outer circumferential shape whose diameter is reduced from the central portion toward the end portion, and the pair of bonding rollers (51, 52) The peripheral speed of the bonding roller provided on the surface side of the laminated body (4) that is bonded to the liquid crystal panel is larger than the peripheral speed of the bonding roller on the opposite side, and the bonding is performed on the opposite side. When the circumferential speed of the roller is set to 1, the ratio of the peripheral speed of the other bonding roller is 1.0050. Up to 1.0200, the pressing roller to be pressed is a flat roller made of metal, and the other bonding roller is a crown roller made of rubber. The method for manufacturing a polarizing plate according to claim 1, wherein In the bonding step, the shape of the crown roller (52) is designed such that the interval between the crown roller (52) and the flat roller (51) is substantially uniform. The method of manufacturing a polarizing plate according to claim 1, wherein a ratio of a difference between a diameter of a central portion of the crown roller (52) and a diameter of the end portion is relative to a length of the crown roller (52) 0.002% or more. The method of manufacturing a polarizing plate according to claim 1, wherein a ratio of a difference between a diameter of a central portion of the crown roller (52) and a diameter of the end portion is relative to a length of the crown roller (52) 0.005% to 0.040%. The method for producing a polarizing plate according to claim 1, wherein the tapered outer circumferential shape of the crown roller (52) has an arc shape. The method of manufacturing a polarizing plate according to claim 1, wherein the external force of the pressing is applied to both ends of the shaft of the bonding roller (51, 52). The method for producing a polarizing plate according to claim 1, wherein the polarizing film is continuously discharged, and the transparent film is continuously discharged. A manufacturing apparatus for a polarizing plate, wherein the transparent film (2, 3) is attached to a polarizing plate formed on one or both sides of the polarizing film (1), and is characterized in that: the transparent film (2, 3) One side or one or both sides of the aforementioned polarizing film (1), the coating viscosity is 1000mPa. An adhesive coating device (11, 12) for an active energy ray-curable adhesive of s or less; a single-sided or two-sided layer of the polarizing film (1) laminated on the transparent film (2, 3) via the adhesive The formed layered body (4) is pressed while being conveyed to bond the transparent film (2, 3) and the polarizing film (1) with a pair of bonding rollers (51, 52); An active energy ray irradiation device (14, 15, 16, 17, 18) for applying the active energy ray to the laminate (4) of the pair of bonding rollers to cure the adhesive; and the pair of bonding One of the rollers is a crown roller (52) having a tapered outer circumferential shape which is reduced in diameter from the central portion toward the end portion, and the pair of bonding rollers (51, 52) are independently driven and disposed on The circumferential speed of the bonding roller on the surface side of the laminated body (4) that is bonded to the liquid crystal panel is larger than the circumferential speed of the bonding roller on the opposite side, and the peripheral speed of the bonding roller on the opposite side is set to 1 The ratio of the peripheral speed of the other bonding roller is 1.0050 to 1.0200, the pressing roller to be pressed is a flat roller made of metal, and the other bonding roller is a crown roller made of rubber.