TW201325871A - Method for manufacturing polarizing sheet - Google Patents

Abstract

Provided is a method for manufacturing a polarizing sheet with a transparent film (2, 3) laminated on one surface or two surfaces of a polarizing film (1), which includes an adhesive dispensing step, a laminating step for laminating the transparent film (2, 3) to the polarizing film (1) by pressing at least one laminating roller (51, 52) to the direction of the other laminating roller (51, 52) by at least one pressing roller (61, 62) contacting with the laminating roller (51, 52), with a laminate (4) formed by laminating the transparent film (2, 3) onto one surface or two surfaces of the polarizing film (1) via the adhesive being interposed between the pair of laminating rollers (51, 52) rotating in a transporting direction, and an active energy ray irradiating step for irradiating active energy ray to the laminate (4) to cure the adhesive, wherein the diameter in the central part of the pressing roller (61, 62) is larger than the diameter in the central part of the laminating roller (51, 52) contacting with the pressing roller.

Description

Method for manufacturing polarizing plate

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

The polarizing film is widely used as a film of a polyvinyl alcohol resin adsorbed by a dichroic dye, and an iodine-based polarizing film containing iodine as a dichroic dye and a dichroic direct dye as a dichroic property are known. The dye of the pigment is a polarizing film or the like. These polarizing films are usually laminated on a single surface or both surfaces with a transparent film such as a triacetyl cellulose film through an adhesive to form a polarizing plate.

As a method of laminating a transparent film on one surface or both surfaces of a polarizing film, a surface of a transparent film is coated with an active energy ray-curable resin, and a polarizing film and a transparent film are attached by a pair of holding rollers. The method of bonding the squeezing and squeezing and squeezing and squeezing the active energy ray, and then squeezing the squeezing of the active energy ray (Patent Document 1: JP-A-2004-245925, Patent Document 2: JP-A-2009-134190, Patent Document 3) : JP-A-2011-95560).

However, as shown in Fig. 5 (a) and (b), the lamination of the laminated body (polarizing film and transparent film) by the bonding rollers 51 and 52 is usually performed by The bearing such as the hydraulic pressure, the air pressure, and the screw is attached to the bearing at both ends of the roller 51 (the arrow of Fig. 5(b)), and the vicinity of the center of the bonding roller 51 is bent, and the laminated body (polarized film and The transparent 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 transfer is deteriorated, and it is easy to cause an obstacle in the manufacturing process. Furthermore, such a phenomenon is a phenomenon that occurs when a high pressure is applied to the laminated body. When the active energy ray-curable resin is used as an adhesive, it is necessary to apply a high pressure to the laminated body because the viscosity is high as compared with other polyvinyl alcohol-based resins or the like as an adhesive.

Therefore, in order to make the bending of the bonding roller hard to occur at the time of pressing, the conventional bonding roller generally uses a roller having a diameter of more than about 300 mm. However, since the contact area between the bonding roller and the laminated body becomes larger as the diameter of the bonding roller increases, the pressure applied per unit area of the laminated body becomes small when the force applied to the bonding roller is constant. Therefore, when high pressure must be applied to the laminated body, it is desirable to make the diameter of the bonding roller as small as possible.

[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 object of the present invention is to provide a laminating roll even with a smaller diameter. The wheel may be a method for producing a polarizing plate that uniformly presses 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 active energy is applied to one side or both sides of the transparent film. An adhesive application step of a line-curable adhesive; the laminate in which the transparent film is laminated on one surface or both surfaces of the polarizing film via the adhesive, and is sandwiched between a pair of bonds that are rotated in the conveying direction In a state between the rollers, at least one of the pressing rollers provided in contact with the bonding roller presses at least one of the rollers toward the bonding roller of the other side, so that the transparent film is bonded to the polarizing film. a bonding step; and an active energy ray irradiation step of irradiating the active layer with the active energy ray to cure the adhesive; wherein a diameter of a central portion of the pressing roller is larger than a central portion of the bonding roller contacting the pressing roller diameter of.

It is preferable that the pair of bonding rollers are driven independently of each other. Further, the pair of bonding rollers and the pressing roller are preferably a sliding roller having a substantially uniform diameter.

Further, the present invention relates to a device for manufacturing a polarizing plate, which is characterized in that a transparent film is bonded to a polarizing plate formed on one or both sides of a polarizing film, and is characterized in that: one side of the transparent film or the polarized light is provided One or two sides of the film An adhesive coating device for 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; a pair of bonding rollers for bonding the transparent film to the polarizing film; and pressing the bonding roller of at least one of the pair of bonding rollers toward the bonding roller on the other side At least one pressing roller provided in contact with the roller; and an active energy ray irradiation device for irradiating the laminated body with an active energy ray to cure the adhesive; wherein a diameter of a central portion of the pressing roller is larger than a contact with the pressing roller The diameter of the center portion of the bonding roller.

According to the present invention, it is possible to provide a method for producing a polarizing plate and a device for manufacturing a polarizing plate which can uniformly pressurize a laminated body (a polarizing film and a transparent film) constituting a polarizing plate even when a bonding roller having a small diameter is used.

Moreover, according to the present invention, it is possible to obtain a polarizing plate which suppresses generation of bubbles between the respective films and deteriorates the adhesion between the respective films. Further, it is possible to suppress the occurrence of an obstacle due to a manufacturing step such as a deterioration in the flow of the transfer.

1‧‧‧ polarizing film

2, 3‧‧‧ transparent film

4‧‧‧Laminated body (polarizer)

11, 12‧‧‧ adhesive coating device

13‧‧‧Roller (cooling roller)

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

19‧‧‧Transporting roller

20‧‧‧Rolling wheel

51, 52‧‧‧ fitted roller

61, 62‧‧‧ Press the wheel

61a‧‧‧ bearing components

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

Fig. 2 is a schematic side view showing an embodiment of a bonding roller and a pressing roller used in the present invention.

Figure 3 is a view of the bonding roller and the pressing roller shown in Figure 2 A schematic front view of the implementation.

Fig. 4 is a schematic side view showing another embodiment of the apparatus for manufacturing a polarizing plate of the present invention.

Fig. 5 (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 one in which a dichroic dye is adsorbed and oriented to a polyvinyl alcohol-based resin film which is stretched by one axis. The polyvinyl alcohol-based resin can be obtained by saponification of a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to the polyvinyl acetate of the individual polymer of vinyl acetate, a copolymer of vinyl acetate and other monomers copolymerizable therewith (for example, ethylene-vinyl acetate copolymerization) may be mentioned. Things). Examples of the other monomer 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, 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.

Such a polyvinyl alcohol-based resin is used as a film for a polarizing film. The method for forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a conventionally known method. Polyvinyl alcohol resin The film thickness of the constituent embryo membrane 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, more desirably in the range of 30 to 80 μm, and an industrially practical width in the range of 1,500 to 6,000 mm.

A commercially available polyvinyl alcohol-based film (Vinylon VF-PS #7500, Kuraray/OPL film M-7500, manufactured by Nippon Synthetic Co., Ltd.) has a raw material thickness of 75 μm (Vinylon VF-PS #6000, Kuraray). The raw material thickness of the system, Vinylon VF-PE #6000, and Kuraray is 60 μm.

In the polarizing film, a polyvinyl alcohol-based resin film is dyed with a dichroic dye to form a dichroic dye, and a polyvinyl alcohol-based resin film having a dichroic dye adsorbed thereon is treated with an aqueous solution of boric acid. The step (boric acid treatment step) and the step of water washing after the aqueous boric acid treatment (water washing treatment step) are carried out.

Further, in the case of producing a polarizing film, the polyvinyl alcohol-based resin film is usually subjected to one-axis stretching, which may be performed before the dyeing treatment step, may be carried out in the dyeing treatment step, or may be performed after the dyeing treatment step. When the one-axis extension is performed after the dyeing treatment step, the one-axis extension 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 these multiple stages.

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

The polyvinyl alcohol-based resin film of the dyeing treatment step is a dichroic dye The dyeing 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 or the like is used. The dichroic dye includes a dichroic direct dye composed of a dichromatic direct dye composed of a bisazo compound such as C.I. Direct Red 39, a compound such as trisazo or tetrazo. Further, the polyvinyl alcohol-based resin film is preferably subjected to water immersion treatment in advance 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 and 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 immersion time (dyeing time) of the aqueous solution is usually 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as a dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing an aqueous dichroic dye and dyeing it 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 1 × 10 ^-3 , per 100 parts by weight of water. To 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 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 a polyvinyl alcohol dyed by a dichroic dye The resin film is formed by immersing in an aqueous solution containing boric acid. The amount of boric acid containing an aqueous solution of 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 immersion time for 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.

Then, in the water washing treatment 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.

Thus, the polyvinyl alcohol-based resin film is 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 5 to 50 μm.

(transparent film)

In the present invention, the one or both sides of the polarizing film are laminated and transparent. film. When the transparent film is attached to both sides of the polarizing film, the transparent films may be the same or different types of films.

Examples of the material constituting the transparent film include a cycloolefin resin, a cellulose acetate resin, and a polycondensation such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. As the ester resin, the 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 refers to a thermoplastic resin (also referred to as a thermoplastic cycloolefin resin) having a monomer unit composed of a cyclic olefin (cycloolefin) such as a norbornene or a polycyclic norbornene-based monomer. 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, or a cyclic olefin, a chain olefin, an aromatic compound having a vinyl group, or the like. Addition polymer. Moreover, it is also effective to introduce a polar base.

When a copolymer of a cyclic olefin and a chain olefin or/and an aromatic compound having a vinyl group is used, it is a chain olefin such as ethylene, propylene or the like, and as an aromatic compound having a vinyl group such as styrene or α- Methylstyrene, nucleoalkyl substituted styrene, and the like. In such a copolymer, the monomer unit of the cyclic olefin may be 50 mol% or less (more desirably 15 to 50 mol%). In particular, when a terpolymer of a cyclic olefin, a chain olefin, and an aromatic compound having a vinyl group is used, the monomer unit composed of the cyclic olefin can be made in a smaller amount as described above. In such a terpolymer, the monomer unit composed of a chain olefin is usually 5 to 80 mol%. The monomer unit composed of an aromatic compound having a vinyl group 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 APEL (for example) can be used. Mitsui Chemicals Co., Ltd., OXIS (manufactured by Okura Industrial Co., Ltd.), etc. When a film of such a cycloolefin-based resin is used as a film, a conventional method such as a solvent casting method or a melt extrusion method is suitably used. In addition, for example, a film made of a film of a cycloolefin-based resin which is pre-formed, such as a scenadium (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), or a ZEONOR film (manufactured by Optes), can be used. Sale.

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. Extending, generally, while winding up the film roll, continuously, in the heating furnace, 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 extend. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cycloolefin resin 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 wound state, the film tends to be agglomerated due to the subsequent adhesion of the film. Therefore, it is generally wound after bonding the protective film. Further, since the cycloolefin-based resin film is generally inferior in surface activity, it is preferred to perform surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, or saponification treatment on the surface adjacent to the polarizing film. Among them, the plasma treatment is easier to implement, especially at the atmospheric piezoelectric slurry. Rational, corona treatment is suitable.

The cellulose acetate-based resin refers to a partially or fully esterified cellulose, for example, a cellulose acetate, a propionate, a butyrate, or a mixed ester of these. More specifically, for example, a triacetyl cellulose film, a diethyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, or the like can be given. As such a cellulose ester-based resin film, a commercially available product such as Fujitac TD80 (Fuji Film Co., Ltd.), Fujitac TD80UF (Fuji Film Co., Ltd.), Fujitac TD80UZ (Fuji Film Co., Ltd.) can be suitably used. , KC8UX2M (Konica Minolta Opto), KC8UY (Konica Minolta Opto), Fujitac TD60UL (Fuji Film Co., Ltd.), KC4UYW (Konica Minolta Opto), KC6UAW (Konica) Minolta Opto (share) system, etc.

Further, as the transparent film, a cellulose acetate resin film to which phase difference characteristics are imparted is also suitably used. For example, WV BZ 438 (made by Fujifilm Co., Ltd.), KC4FR-1 (made by Konica Minolta Opto Co., Ltd.), KC4CR-1, such as a commercially available product of the cellulose acetate-based resin film which imparts a phase difference characteristic. (Konica Minolta Opto Co., Ltd.), KC4AR-1 (Konica Minolta Opto Co., Ltd.), and the like. Cellulose acetate, also known as acetaminophen, cellulose acetate.

These cellulose acetate-based resin films are likely to absorb water, and the moisture content of the polarizing plate may affect the relaxation of the end portions of the polarizing plate. The moisture content when manufacturing the polarizing plate should be close to the storage environment of the polarizing plate. For example, the equilibrium moisture content in the production line of the clean room and the storage warehouse of the roll is related to the composition of the laminated film, for example, 2.0 to 3.5. % or so, more ideally 2.5 % to 3.0%. The numerical value of the moisture content of the polarizing plate was measured by the dry weight method and was changed by weight after 105 ° C / 120 minutes.

The thickness of the transparent film used in the polarizing plate of the present invention is preferably as thin as possible, but when it is too thin, workability is deteriorated due to a decrease in strength. On the other hand, when it is too thick, there is a problem that the curing time required after lamination is lengthened due to a decrease in transparency. 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 surface of the polarizing film and/or the transparent film may be subjected to corona treatment, flame treatment, plasma treatment, ultraviolet treatment, primer treatment, saponification treatment, or the like. Modification treatment.

Further, in the transparent film, surface treatment such as anti-glare treatment, anti-reflection treatment, hard coating treatment, antistatic treatment, and anti-stain treatment may be carried out singly or in combination of two or more. 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 film for enhancing brightness, a function as a reflective film, a function as a semi-transmissive reflective film, a function as a diffusion film, and an optical compensation film. Optical functions such as functions. In this case, for example, by the surface of the transparent film, an optical functional film such as a laminated retardation film, a film for enhancing brightness, a reflective film, a semi-transmissive reflective film, a diffusion film, or an optical compensation film can have such a function. Also in transparent film It gives itself such a function. Further, the transparent film may have a plurality of functions such as a diffusion film having a function of a film for enhancing brightness.

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 in the retardation film can be, for example, a range in which the front phase difference value is 5 to 100 nm, the thickness direction retardation value is 40 to 300 nm, or the like. Further, in the above-mentioned transparent film, by forming a fine hole by a method described in JP-A-2002-169025, JP-A-2003-29030, or by overlapping, the center wavelength of the reflection is different. The cholesteric liquid crystal layer above the layer can be imparted as a film for enhancing brightness.

When a metal thin film is formed by vapor deposition, sputtering, or the like in the transparent film, a function as a reflective film or a semi-transmissive reflective film can be imparted. The transparent film is provided with a function as a diffusion film by applying a resin solution containing fine particles. Further, in the transparent film, a liquid crystal compound such as a discotic liquid crystal compound is applied and aligned to impart a function as an optical compensation film. Further, a compound exhibiting a phase difference may be contained in the transparent film. Further, various optical functional films may be directly bonded to the polarizing film by using an appropriate adhesive. The commercially available product of the optical functional film may, for example, be a film having a brightness enhancement such as DBEF (available from Sumitomo 3M Co., Ltd.), or a WV film (Fuji Film Co., Ltd.). Arton film (JSR), ZEONOR film (manufactured by Optes), Escena (Shuishui Chemical Industry Co., Ltd.) A phase difference film such as VA-TAC (manufactured by Konica Minolta Opto Co., Ltd.) or SUMIKALITE (manufactured by Sumitomo Chemical Co., Ltd.).

(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 is an adhesive composed of an epoxy resin composition containing an epoxy resin which is cured by irradiation with an active energy ray, from the viewpoints of weather resistance, refractive index, and cationic polymerizability. . 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 composed of an acrylic resin composition such as acrylamide, acrylate, urethane acrylate or acrylate acrylate.

The epoxy resin refers to a compound having two or more epoxy groups in the molecule. From the viewpoints of weather resistance, refractive index, cationic polymerizability, and the like, the epoxy resin contained in the curable epoxy resin composition as an adhesive is an epoxy resin containing no aromatic ring in the molecule (for example, refer to the patent literature) 1) Ideal. As such an epoxy resin, a hydrogenated epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, etc. are mentioned.

Hydrogenated epoxy resin, a hydrogenated polyhydroxy compound obtained by selective hydrogenation of a polyhydroxy compound as a raw material of an aromatic epoxy resin in the presence of a catalyst under pressure, via a propylene group The method of etherification is obtained. Examples of the aromatic epoxy resin include diepoxypropyl ether of bisphenol A, diepoxypropyl ether of bisphenol F, and diepoxy of bisphenol S. Bisphenol type epoxy resin such as propyl ether; phenolic novolak epoxy resin, cresol novolac epoxy resin, and phenolic epoxy resin such as hydroxybenzaldehyde phenol novolac epoxy resin; tetrahydroxyphenylmethane A polyfunctional epoxy resin such as a glycidyl ether, a glycidyl ether of tetrahydroxydiphenyl ketone, 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 "epoxy group bonded to the alicyclic ring" means a bridged oxygen atom -O- in 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 of (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, since it exhibits good adhesion, an epoxy resin having an oxabicyclohexane ring (m=3 in the above formula) and an oxabicycloheptane ring (described above) are used. The epoxy resin of the formula m=4 is preferred. 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 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).

(c) Epoxycyclohexylmethyl esters of dicarboxylic acids represented by the following formula (III): (wherein R ⁵ and R ⁶ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).

(d) Epoxycyclohexyl methyl ether of polyethylene glycol represented by the following formula (IV): (wherein R ⁷ and R ⁸ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

(e) an epoxycyclohexyl methyl ether of an alkanediol represented by the following formula (V): (wherein R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 2 to 20).

(f) a dicyclooxytrispirate compound represented by the following formula (VI): (wherein R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(g) a diepoxymonosole compound represented by the following formula (VII): (wherein R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(h) 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) Epoxypentyl 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 ester of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid with (7-oxa-bicyclo[4.1.0]heptan-3-yl)methanol [in formula (I) a compound having R ¹ =R ² =H]; (B) 4-methyl-7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and (4-methyl-7-oxygen) An esterified product of a hetero-bicyclo[4.1.0]heptan-3-yl)methanol [in the formula (I), a compound of R ¹ =4-CH ₃ , R ² =4-CH ₃ ]; (C) 7 An ester of oxabicyclo[4.1.0]heptane-3-carboxylic acid with 1,2-ethanediol [in the formula (II), a compound of R ³ =R ⁴ =H, n=2] (D) (7-oxabicyclo[4.1.0]heptan-3-yl)methanol ester with adipic acid [in formula (III), R ⁵ =R ⁶ =H, p=4 Compound]; (E) (4-methyl-7-oxabicyclo[4.1.0]heptan-3-yl)methanol ester 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 ether of 1,2-ethanediol A compound (in the formula (V), R ⁹ = R ¹⁰ = H, r = 2).

Further, examples of the aliphatic epoxy resin include a polyepoxypropyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. More specifically, for example, diepoxypropyl ether of 1,4-butanediol; diepoxypropyl ether of 1,6-hexanediol; triepoxypropyl ether of glycerol; trihydroxypropane Triepoxypropyl ether; diepoxypropyl ether of polyethylene glycol; diepoxypropyl ether of propylene glycol; added by aliphatic polyols such as ethylene glycol, propylene glycol and glycerol Or a polyepoxy propyl ether of a polyether polyol obtained by two or more kinds of alkylene oxides (ethylene oxide or propylene oxide).

The epoxy resin which is an adhesive agent which comprises an epoxy resin composition can be used individually by 1 type, and can also use 2 or more types together. 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 low, and the strength is lowered. On the other hand, when it exceeds 3,000 g/eq, there is a case where the compatibility with other components contained in the adhesive is low.

In the adhesive, from the viewpoint of reactivity, it is preferred to use cationic polymerization as the curing reaction of the epoxy resin. Therefore, in the curable epoxy resin which is an active energy ray-curable adhesive, it is preferred to formulate a cationic polymerization initiator. a cationic polymerization initiator which is irradiated by an active energy ray such as visible light, ultraviolet light, X-ray or electron beam to generate a cation A sub-species or a Lewis acid initiates the polymerization of an epoxy group. Hereinafter, a cationic polymerization initiator which initiates a polymerization reaction of an epoxy group by irradiation of an active energy ray to generate a cationic species or a Lewis acid is referred to as a "photocationic polymerization initiator".

By using a photocationic polymerization initiator, the method of hardening the adhesive by irradiation with an active energy ray can be cured at room temperature, and the heat resistance of the polarizing film or the bending due to expansion can be reduced, so that the films can be well followed. The point is advantageous. Further, the photocationic polymerization initiator is subjected to a catalytic action by light, and even if it is mixed with an epoxy resin, it is excellent in storage stability and workability.

Examples of the photocationic polymerization initiator include an aromatic diazonium salt; an onium salt such as an aromatic onium salt or an aromatic onium salt; and an iron-aromatic hydrocarbon complex.

Examples of the aromatic diazonium salt include benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate, and benzene diazonium hexafluoroborate. Further, examples of the aromatic onium salt include diphenylphosphonium tetrakis(pentafluorophenyl)borate, diphenylphosphonium hexafluorophosphate, diphenylphosphonium hexafluoroantimonate, and hexafluorophosphate. 4-nonylphenyl) phosphonium salt and the like.

Examples of the aromatic onium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, and bis(hexafluorophosphoric acid) 4 , 4'-bis(diphenylfluorenyl)diphenyl sulfide, bis(hexafluoroantimonate) 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide, Bis(hexafluorophosphate) 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide, hexafluoroantimonic acid 7-[bis(p-tolylmethyl) fluorenyl ]-2-isopropyl thioxanthone, tetrakis(pentafluorophenyl)borate 7-[bis(p-tolylmethyl) hydrazine 4-isopropyl thioxanthone, 4-phenylcarbonyl-4'-diphenylindenyl-diphenyl sulfide, hexafluoroantimonate 4-(p-tert-butylbenzene 4-carbonyl- 4,2-diphenyldecyl-diphenyl sulfide, 4-(p-tert-butylphenylcarbonyl)-4'-di(p-tolylformamide) tetrakis(pentafluorophenyl)borate Base) fluorenyl-diphenyl sulfide and the like.

Further, examples of the iron-aromatic complex include dimethyl hexafluoroantimonate-cyclopentadienyl iron (II), cumene hexafluoro-cyclopentadienyl iron (II), and xylene-ring. Iron (II)-tris(trifluoromethylsulfonyl) methanide (methanide) and the like.

Commercially available products of the photo-cationic polymerization initiators can be easily obtained, and the respective brand names include, for example, "KAYARAD PCI-220" and "KAYARAD PCI-620" (manufactured by Nippon Kayaku Co., Ltd.). "UVI-6990" (made by Union Carbide), "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" (made by Rhodia Corporation).

The photocationic polymerization initiator may be used alone or in combination of two or more. Among them, the aromatic sulfonium salt has ultraviolet absorbing properties even in a wavelength region of 300 nm or more, and therefore has excellent hardenability. It is suitable for use because it imparts a cured product having good mechanical strength and 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. When the 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 is 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, and the hygroscopic property of the cured product becomes high, which is durable. A situation in which performance is degraded.

When a photocationic polymerization initiator is used, 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. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo and a diazo compound, a halogen compound, and a photoreductive dye.

More specific examples of the photosensitizer are, for example, benzoin methyl ether, benzoin isopropyl ether, and benzoin derivatives such as α,α'-dimethoxy-α-phenylacetophenone; diphenyl ketone, 2,4- Dichlorodiphenyl ketone, o-benzoin benzoic acid methyl ester, 4,4'-bis(dimethylamino)diphenyl ketone and 4,4'-bis(diethylamino)diphenyl ketone Iso-diphenyl ketone derivatives; thioxanthone derivatives such as 2-chlorothiazinone and 2-isopropylthioxanthone; anthracene derivatives such as 2-chloroindole and 2-methylindole ; acridinone derivatives such as N-methylacridone and N-butylacridone; others also include α,α-diethoxyacetophenone, diphenylethylenedione, fluorenone (Fluorenone), Xanthone, uranium-quinone 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.

Examples of the thermal cationic polymerization initiator include a benzyl sulfonium salt, a thiophenium salt, a thiolanium salt, a benzylammonium salt, a pyridinium salt, a hydrazinium salt, and the like. A carboxylic acid ester, a sulfonate, an amine imine or the like. These thermal cationic polymerization initiators are easily available as commercial products, and are respectively sold under the trade names of "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 polyol.

The oxetane is a compound having a 4-membered cyclic ether in the molecule, and examples thereof include 3-ethyl-3-hydroxymethyloxetane and 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. The oxygen The heterocyclic butanes are easily available as commercially available products, and examples thereof include "Aron oxetane OXT-101", "Aron oxetane OXT-121", "Aron oxetane OXT-211", and "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 polyol is preferably an acidic group other than a phenolic hydroxyl group, and for example, a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, and a phenolic hydroxyl group. Polyol compound, polycarbonate polyol, and the like. The molecular weight of the polyols is usually 48 or more, more preferably 62 or more, still more preferably 100 or more, and still more preferably 1,000 or less. These polyols usually contain 50% by weight or less, and more preferably 30% by weight or less, in the curable epoxy resin composition.

In the active energy ray-curable adhesive, 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. may be further formulated. additive. Examples of the ion scavenger include inorganic compounds such as powdered lanthanoid, lanthanide, magnesium, aluminum, calcium, titanium, and such mixed systems. 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 for adjusting the viscosity can be contained in order to have a suitable viscosity range for each coating method. As a solvent, the epoxy resin can be dissolved well without lowering the optical characteristics of the polarizing film. The lipid composition or the like is preferably an organic solvent such as a hydrocarbon represented by toluene or an ester represented 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, more preferably in the range of 10 to 200 mPa ‧ s, more preferably in the range of 20 to 100 mPa ‧ s .

<Method of Manufacturing Polarizing Plate>

Next, 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.

In the manufacturing apparatus 30 for a polarizing plate shown in FIG. 1, the adhesive coating means 11 and 12 for applying the adhesive to one side of the transparent films 2 and 3 are sequentially provided along the transport direction; the transparent film 2 is used. And 3, which are bonded to the polarizing film 1 to obtain a bonding roller (clamping roller) 51 and 52 for the laminated body 4, and a roller 13 for bonding the transparent film 2, 3 and the polarizing film 1 to the laminated body 4; The first active energy ray irradiation devices 14 and 15 are disposed at opposite positions of the outer peripheral surface of the roller 13. 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 are provided.

Further, as shown in FIGS. 1 , 2 , and 3 , pressing rollers 61 and 62 that respectively contact the bonding rollers 51 and 52 are provided. Here, the diameter of the central portion of the pressing rollers 61, 62 is larger than the diameter of the central portion of the bonding rollers 51, 52 that are in contact therewith.

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 fed in a state of being wound into a roll, by the adhesive application devices 11 and 12.

Then, the both sides of the polarizing film 1 continuously fed in a state of being wound into a roll are coated with the transparent thin films 2 and 3 of the adhesive, and the laminated body composed of the adhesive layer is laminated and rotated in the conveying direction. In a state between the pair of bonding rollers 51 and 52, at least one of the bonding rollers is pressed toward the bonding roller on the other side by pressing the rollers 61 and 62, so that the polarizing film 1 and the transparent films 2 and 3 are pressed. The laminate is bonded to form a laminate 4 (a bonding step).

Then, the layered body 4 is transported while being in close contact with the outer peripheral surface of the roller 13, and the active energy rays are irradiated from the first active energy ray irradiation devices 14 and 15 toward the outer peripheral surface of the roller 13 to cure the adhesive (active energy). Line 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 needed. Finally, the laminated body 4 is taken up by the conveying roller 19 and taken up as a polarizing plate to the winding roller 20. 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 coating method, a notch wheel coating method, and a gravure coating method can be used. the way. Among them, in consideration 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 have a gravure roller.

When the application of the adhesive is carried out using the gravure roll as the adhesive application devices 11, 12, the thickness (coating thickness) of the applied adhesive is preferably from about 0.1 to 10 μm, more preferably from 0.2 μm to 4 μm. Coating of the subsequent agent The thickness is adjusted in accordance with the draw ratio of the speed of the intaglio roll to the linear speed of the transparent film. In general, the draw ratio (speed/line speed of the intaglio roll) is adjusted to 0.5 to 10, and the coating thickness of the adhesive can be adjusted to about 0.1 to 10 μm. More specifically, the linear speed of the transparent films 2, 3 is set to 10 to 100 m/min, and the intaglio roller is rotated in the opposite direction to the conveying direction of the transparent films 2, 3, and the speed of the intaglio roller is set to 5 to 1000 m/ In minutes, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 μm.

After the preparation, the preparation is usually adjusted to a predetermined temperature within a range of 15 to 40 ° C ± 5 ° 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, first, the transparent thin films 2 and 3 coated with the adhesive in the above-described steps are laminated on the both surfaces of the polarizing film 1 continuously fed from the state of being wound into a roll, and laminated with an adhesive.

In the state in which the laminated body is interposed between the pair of bonding rollers 51 and 52 that are rotated in the conveying direction, as shown in FIG. 3, the bearing member 61a of the pressing roller 61 is pressed in the direction of the arrow (the direction in which the roller 52 is bonded). By pressing the entire roller, the entire bonding roller 51 is pressed in the direction of the arrow, and the polarizing film 1 and the transparent films 2 and 3 are bonded together to form the laminated body 4. In this case, the direction in which the polarizing film is conveyed is preferably within a range of ±3° from the surface perpendicular to the pressing direction of the bonding roller, and more preferably within an angle of ±1°, and the polarizing film is placed between the bonding rollers. Transfer. It is particularly preferable that the polarizing film is transferred between the bonding rollers so that the direction in which the polarizing film is conveyed and the surface perpendicular to the pressing direction of the bonding roller overlap. Thereby, the polarizing film and the transparent film are in the bonding roll Contact before the wheel will not produce bubbles. Here, since the diameter of the central portion of the pressing roller 61 is larger than the diameter of the central portion of the bonding roller 51 connected thereto, even when the bearing member 61a is pressed, the pressing roller 61 is less likely to be bent, and the pressure can be uniformly pressed. The entire roller 51 is combined. Thereby, the laminated body (the polarizing film 1 and the transparent films 2 and 3) which comprise a polarizing plate can be uniformly pressurized.

Generally, the driving force for applying the self-rotation of the pressing roller also causes the bonding roller to rotate. However, in the present embodiment, the pair of bonding rollers are independently driven to adjust the bending.

Further, in the first drawing, the adhesive is uniformly applied to one surface of the transparent films 2 and 3, and the surface of the adhesive to which the transparent films 2 and 3 are applied is superposed on the polarizing film 1 and By bonding the rollers 51 and 52 together, the adhesive may be uniformly applied to both surfaces of the polarizing film 1 to overlap the surface of the adhesive coated with the polarizing film 1 with the transparent films 2 and 3, and by sticking The rollers 51 and 52 are combined to fit together.

Further, as shown in Fig. 4, the pressing roller 61 can be provided only in one of the pair of bonding rollers 51, 52.

The diameter of the central portion of the bonding roller that contacts the pressing roller is preferably 30 mm or more and less than 300 mm, more preferably 50 to 270 mm. By using such a small-diameter bonding roller, it is difficult to bite air between the polarizing film and the transparent film, and the thickness of the adhesive which does not bite into the bubble is widened, so that it is easy to manufacture the polarizing film. A polarizing plate that generates bubbles between the transparent film and the transparent film. In particular, when the diameter of the bonding roller is 300 mm or more, the polarizing film and the transparent film become easy to bite into the air. gas. Further, when the diameter of the bonding roller is less than 50 mm, there is a problem that the strength is lowered. Further, the bonding roller is composed of at least one pair of rollers, and the diameters of the rollers constituting the pair may be the same or different. The width of the fitting roller is preferably 300 to 3000 mm.

Further, the diameter of the central portion of the pressing roller is preferably 200 to 500 mm. When it is less than 200 mm, when an external force is applied to the bearing member of the roller, and the bonding roller is pressed, the pressing roller is likely to be bent, and the bonding roller may not be pressed with uniform pressure. Moreover, when it is larger than 500 mm, there is an inconvenience in the point where the apparatus becomes large.

It is preferable that the pair of bonding rollers 51 and 52 and the pressing rollers 61 and 62 have a sliding roller having a substantially uniform diameter. However, one of the pair of fitting rollers 51, 52 and one of the pressing rollers 61, 62 may be a roller having a peripheral shape having a tapered diameter which is tapered from the central portion toward the end portion (crowned roller (crowned Roll)) and so on.

When one of the pair of bonding rollers 51, 52 or one of the pressing rollers 61, 62 is a convex roller, the ratio of the difference between the diameter of the central portion of the convex roller and the diameter of the end portion, the length of the convex roller The length (the length in the axial direction) is preferably from about 0.0020% to about 0.0500%. Generally, in the range of the ratio, the shape of the convex roller can be designed such that the fitting step makes the interval between the convex roller and the sliding roller uniform in a state of being pressed.

The pressure applied to the laminated body by the bonding rollers 51 and 52 is not particularly limited. When a metal roller and a rubber roller are used, the instantaneous pressure of the two-piece PRESCACE (trade name) (for ultra low pressure) made of Fuji film is used. It is preferably from 0.5 to 3.0 MPa, more preferably from 1.0 to 2.5 MPa. In the present invention, The external force of the pressing of the bonding roller is usually applied to the bearing members that press the both ends of the roller.

The material of the bonding roller and the pressing roller is, for example, metal or rubber. It is preferable that one of the pair of bonding rollers is a metal roller and the other is a rubber roller. Further, the arrangement of the bonding roller and the pressing roller is not particularly limited, and can be arranged at any angle to each other. That is, the setting of the pressing roller is not limited to the upper and lower sides of the bonding roller, and may be arranged at a horizontal or other angle.

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 attached with a drive motor to control the rotation speed, and the lower side of the bonding roller is made of metal. When the pressing, the lower side of the bonding roller does not deform, and the peripheral speed of the bonding roller is easily maintained. . However, in this case, since it is easy to adjust the bending of the forward bending described later, in the present invention, it is preferable that the pressing roller (the upper side) is made of metal, and the other (lower side) bonding roller is made of rubber.

Further, it is preferable that the pressing roller provided in contact with the metal bonding roller is made of rubber. The pressing roller provided in contact with the rubber-made bonding roller may be either metal or rubber. When the bonding roller and the pressing roller that are in contact with each other are made of metal, it is difficult to continuously use the roller because it is easily scratched during use. On the other hand, when the bonding roller and the pressing roller which are in contact with each other are made of rubber, there is no problem.

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), titanium, urethane, hydrazine, EPDM (ethylene-propylene-diene rubber), etc., preferably NBR, titanium, urethane. . The hardness of the rubber roller is not particularly limited and is usually from 60 to 100 °, more preferably from 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 is pressed with a rod, the surface resistance of the rubber roller is measured by a durometer.

Among the pair of bonding rollers, the peripheral speed of one of the bonding rollers and the other of the bonding rollers may be different. For example, the peripheral speed of the bonding roller (first bonding roller) provided on the surface side of the laminated body 4 bonded to the liquid crystal panel is faster than the peripheral speed of the bonding roller (second bonding roller) on the opposite side Ideal. Thereby, in the obtained polarizing plate, the surface to be bonded to the liquid crystal panel can be convex, and the surface on the opposite side can be concavely curved (positive bending). In the obtained polarizing plate, when 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, bubbles are generated in the center portion. Bad situation. Further, 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 larger than the range, the amount of bending of the forward bending becomes too large, and when the polarizing plate is attached to the liquid crystal cell, it is easy to cause a problem such as biting bubbles at the end portion, and further, it is placed in a severe manner. In the environment, the positive bending is further promoted, except that the end of the polarizing plate is peeled off from the liquid crystal cell.

The outer peripheral surface of the roller 13 is formed as a convex curved surface of the mirror surface, and the surface thereof is conveyed while being in close contact with the laminated body 4, and the adhesive is polymerized and hardened by the active energy ray irradiation devices 14 and 15 in the process. The polymerization agent is hardened, and the diameter of the roller 13 is not particularly limited as long as the laminated body 4 is sufficiently adhered. In the laminate 4 in which the adhesive is not cured, it is preferable to irradiate the active energy ray so that the amount of accumulated light passing between the rollers 13 is 10 mJ/cm ² or more. The roller 13 can be driven by the linear motion of the laminated body 4, or can be rotationally driven, or fixed, and the laminated body 4 can be slid over the surface thereof. Further, when the roller 13 is polymerized and cured by irradiation with an active energy ray, it can also function as a cooling roller that dissipates heat generated by the laminated body 4, and in this case, the surface temperature of the cooling roller is set to 4 to 30. °C is ideal.

(active energy ray irradiation step)

The light source used for the polymerization hardening of the adhesive by the irradiation of the active energy ray is not particularly limited, and a light source having a light-emitting distribution having 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 ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp.

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 is too long, and when it exceeds 5000 mW/cm ² , the heat of radiation passing through the lamp and the heat generation of the composition during polymerization may occur. The yellowing of the epoxy resin composition or the like of the constituent material of the agent, and the deterioration of the polarizing film. In addition, the intensity of the wavelength region in which the irradiation intensity is preferably effective for activation of the photocationic polymerization initiator is more preferably the intensity in the wavelength region of 400 nm or less, and more preferably the intensity in the wavelength region of 280 to 320 nm.

The irradiation time of the active energy ray of the active energy ray-curable adhesive is limited to each hardening composition, and is not particularly limited, and the cumulative light amount indicating the product of the irradiation intensity and the irradiation time is preferably set to 10 mJ/cm. ² or more is more preferably 10 to 5,000 mJ/cm ² . When the cumulative amount of the above-mentioned adhesive is less than 10 mJ/cm ² , the generation of the active species from the initiator is insufficient, and the hardening of the adhesive is insufficient. On the other hand, when the cumulative amount of light exceeds 5,000 mJ/cm ² , the irradiation time becomes extremely long, which is unfavorable for productivity improvement. In this case, it is necessary to determine whether or not the cumulative amount of light in the wavelength region (UVA (320 to 390 nm)), UVB (280 to 320 nm), or the like is required depending on the combination of the film to be used and the type of the adhesive.

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

When the active energy ray is ultraviolet ray, in the step of irradiating the laminated body 4 with the active energy ray, the laminated body 4 is given a tension of 100 to 800 N/m in the longitudinal direction (transport direction) while the irradiation time is 0.1. It is preferable to transmit the laminated body 4 at a linear velocity of more than one second. Further, it is preferable that the irradiation intensity of ultraviolet rays is 10 mW/cm ² or more.

Further, when the accumulated light amount of the active energy ray by the active energy ray irradiation devices 14 and 15 is insufficient, the second and subsequent active energy ray irradiation devices 16 to 18 are further provided, and the active energy ray is additionally irradiated to promote the laminated body 4 The hardener of the adhesive is ideal. The cumulative amount of light in all of the steps is preferably set to 10 mJ/cm ² or more, more desirably 10 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 performed in plural times.

In order to ensure the hardening of the adhesive at the end of the polarizing plate (layered body), for example, "Light Hammer 10" manufactured by FUSION, which is an electrodeless D valve lamp, is a method of aligning the movement of the film. Wait.

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 in the range of 30 N/cm ² to 150 N/cm ² . It is preferably in the range of 30 N/cm ² to 120 N/cm ² . When the length of the roll is less than 30 N/cm ² , it is not preferable to move the long roll. When it is more than 150 N/cm ² , the winding is too tight and tends to be slack.

In addition, the longer the length of the roll is, the more the winding tends to be too tight (the phenomenon that it is difficult to return to flatness when unwinding), so that the polarizing plate can be wound onto the core while continuously or in stages. Reduce the tension. The method of imparting a so-called tapered shape and reducing the tension is such that the tension at this time is 150 N/cm ² or less.

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

The diameter of the cylindrical core is preferably 6 to 12 inches. The diameter of the core is larger, and it is more ideal for 11吋, 12吋, etc., and when it is too large, There is a tendency to move and keep it difficult.

The material of the cylindrical core is used in the clean room, as long as it is not easy to generate dust, and can ensure that the wide polarizing plate is wound under appropriate strength, that is, there is no special restriction, and FRP (glass fiber reinforced plastic) can be selected. )Wait.

Example

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 the embryonic 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, which is driven by the driving nip rollers before and after the treatment tank, imparts a circumferential speed difference.

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

Then, while immersing in a dyeing tank containing an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.02/2.0/100, one-axis extension was carried out at a stretching ratio of about 1.5 times. Then, in a boric acid bath containing an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 12/3.7/100, while immersing at 55.5 ° C for 130 seconds, one-axis stretching was performed from the cumulative stretching ratio of the embryonic membrane to 5.7 times. Then, with potassium iodide/boric acid/water in a weight ratio of 9/2.4/100 The aqueous solution was boiled at 40 ° C for 60 seconds in a boric acid bath.

Further, in a washing tank, it is washed with pure water at 8 ° C for about 16 seconds, and then sequentially passed through a drying furnace at about 60 ° C and a drying furnace at about 85 ° C, and the residence time in the drying furnaces is totaled. Dry for 160 seconds. Thus, a polarizing film having a thickness of 28 μm in which iodine was adsorbed and aligned was obtained.

(production of polarizing plate)

As a transparent film, a cycloolefin-based resin film "Zeonor" (manufactured by Zeon Co., Ltd.) having a thickness of 50 μm and a triacetone cellulose film "KC8UX2MW" (manufactured by Konica Minolta Co., Ltd.) having a thickness of 80 μm were prepared.

Then, an epoxy resin composition of an ultraviolet curable adhesive was applied to one surface of a cycloolefin-based resin film "Zeonor" having a thickness of 50 μm, using an adhesive application device (Micro Chamber Doctor: manufactured by Fuji Machinery Co., Ltd.). KR series" (manufactured by Adeka Co., Ltd.; containing a cationic polymerization initiator). Furthermore, the epoxy resin composition "KR series" (made by Adeka Co., Ltd.) of the ultraviolet-curable adhesive was applied to the single surface of the above-mentioned 80 μm-thickness trimethylcellulose film "KC8UX2MW" using the same adhesive application device. Containing a cationic polymerization initiator). At this time, the linear velocity of the polarizing film laminate of the adhesive application device was 25 m/min, and the intaglio roller was rotated in the opposite direction to the conveyance direction of the laminated material to form a cycloolefin-based resin film "Zeonor" having a thickness of 50 μm. The thickness of the adhesive layer was about 3.5 μm, and the thickness of the adhesive layer on the triacetonitrile cellulose film "KC8UX2MW" having a thickness of 80 μm was about 3.5 μm.

Then, a cycloolefin-based resin film "Zeonor" having a thickness of 50 μm and a trimethyl fluorene fiber having a thickness of 80 μm were formed on both surfaces of the polarizing film. The vitamin film "KC8UX2MW" was bonded via the epoxy resin composition (ultraviolet curing type adhesive). At the time of bonding, as shown in Fig. 1, a pair of bonding rollers having a diameter of 250 mm and a pair of pressing rollers having a diameter of 400 mm which are provided in contact with the respective bonding rollers are used to make the average clamping of the bonding rollers. The pressure (the pressure applied to the laminated body by the bonding roller) was clamped so as to become 1.53 MPa.

The polarizing film in which the above two kinds of transparent films were bonded was adhered to a cooling roller having a tension of 600 N/m in the longitudinal direction, and moved at a linear velocity of 25 m/min to be continuously connected in series from the width direction of the film. The first active energy ray irradiation step is performed in the ultraviolet ray irradiated by the metal halide lamp 2 (a power of 120 W/cm per 盏 manufactured by GS-YUASA Co., Ltd.), and then passed through the width direction of the film. The second active energy ray irradiation step is performed in an ultraviolet ray irradiated by an electrodeless D-valve lamp 6 盏 (Light Hammer 10 manufactured by Fusion Co., Ltd., 216 W/cm per unit length) Polarizer.

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 peripheral surface of the cooling roller at 23 ° C, and a cycloolefin resin film "Zeonor" having a thickness of 50 μm is used. The side is exposed to ultraviolet light. Thereby, the deterioration of the adhesive or 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 nip pressure of the pair of bonding rollers of the first embodiment was measured using a two-piece press box (for ultra low pressure) made of Fuji film, the nip pressure distribution was almost uniform in the width direction. Moreover, when evaluating the produced polarizing plate, no gas was observed. bubble. The results are shown in Table 1.

[Example 2]

In the present embodiment, a polarizing plate was produced in the same manner as in Example 1 except that the average nip pressure of the bonding roller was 2.25 MPa.

(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 of the second embodiment was measured using a two-piece press box (for ultra low pressure) made of Fuji film, the nip pressure distribution 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]

A polarizing plate was produced in the same manner as in Example 1 except that only a pair of bonding rollers were used and the average clamping pressure was 1.13 MPa.

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

In the measurement of the nip pressure of the bonding roller of Comparative Example 1, when the two-piece press box (for ultra low pressure) made of Fuji film was used, the distribution of the nip pressure in the width direction became large. Further, when the produced polarizing plate was evaluated, bubbles were observed. The results are shown in Table 1.

[Industrial availability]

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

1‧‧‧ polarizing film

2, 3‧‧‧ transparent film

4‧‧‧Laminated body (polarizer)

11, 12‧‧‧ adhesive coating device

13‧‧‧Roller (cooling roller)

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

19‧‧‧Transporting roller

20‧‧‧Rolling wheel

51, 52‧‧‧ fitted roller

61, 62‧‧‧ Press the wheel

Claims (4)

A method for producing a polarizing plate, which is a method for producing a polarizing plate comprising a transparent film (2, 3) bonded to one surface or both surfaces of a polarizing film (1), characterized by comprising: one side of the transparent film Or a coating step of applying an active energy ray-curable adhesive on one or both sides of the polarizing film (1); and the transparent film (2, 3) is laminated on the polarizing film (1) via the adhesive. The laminated body (4) formed on one side or both sides is sandwiched between a pair of bonding rollers (51, 52) that rotate in the conveying direction, and is bonded to the aforementioned roller (51, 52) At least one pressing roller (61, 62) provided in contact, presses at least one of the bonding rollers (51, 52) toward the bonding roller on the other side, thereby making the transparent film (2, 3) a bonding step of bonding 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; wherein the pressing roller (61, 62) The diameter of the central portion is larger than the diameter of the central portion of the bonding roller (51, 52) that contacts the pressing roller. The method of manufacturing a polarizing plate according to claim 1, wherein the pair of bonding rollers (51, 52) are independently driven. The method for producing a polarizing plate according to claim 1, wherein the pair of bonding rollers (51, 52) and the pressing rollers (61, 62) are sliding rollers having substantially uniform diameters. A manufacturing apparatus of a polarizing plate, wherein the transparent film (2, 3) is bonded 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 or both sides of the polarizing film (1), an adhesive coating device (11, 12) for applying an active energy ray-curable adhesive; and the transparent film (2, 3) The laminate (4) formed by laminating the one or both surfaces of the polarizing film (1) with the adhesive layer is sandwiched while being conveyed, whereby the transparent film (2, 3) and the polarizing film (1) are laminated. One pair of bonding rollers (51, 52) for bonding; in order to fit the roller (51, 52) of at least one side of the pair of bonding rollers (51, 52) toward the roller on the other side Directional pressing, at least one pressing roller (61, 62) provided in contact with the bonding roller (51, 52); and active energy ray for irradiating the laminated body (4) with an active energy ray to cure the adhesive An illuminating device (14, 15, 16, 17, 18); wherein a diameter of a central portion of the pressing roller (61, 62) is larger than a diameter of the bonding roller contacting the pressing roller The diameter of the central part of (51, 52).