JP6909270B2 - Polarizing plate manufacturing method and manufacturing equipment - Google Patents

Description

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

The polarizing film is widely used as a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented. An iodine-based polarizing film using iodine as a dichroic dye and a dichroic direct dye as a dichroic dye are used. Dye-based polarizing films used as dyes are known. These polarizing films are usually obtained by laminating a transparent film such as a triacetyl cellulose film on one or both sides of the polarizing film via an adhesive to obtain a polarizing plate.

As a method of laminating a transparent film on one side or both sides of a polarizing film, an active energy ray-curable resin is applied to the surface of the transparent film in advance, and then the polarizing film and the transparent film are pressed by a pair of nip rolls (bonding rolls). Then, there is a method of bonding and curing by irradiating with active energy rays (Patent Document 1: Japanese Patent Application Laid-Open No. 2004-245925, Patent Document 2: JP-A-2009-134190, Patent Document 3: Special Publication No. Open 2011-95560 (Ab. 2011).

Japanese Unexamined Patent Publication No. 2004-245925 Japanese Unexamined Patent Publication No. 2009-134190 Japanese Unexamined Patent Publication No. 2011-95560

In the above method, when the thickness of the active energy ray-curable resin applied to the surface of the transparent film is set to 2.0 μm or less in order to reduce the thickness of the polarizing plate, for example, when the transparent film and the polarizing film are bonded together. There was a problem that air bubbles were easily mixed in the film.

The present invention has been made to solve the above problems, and provides a method and an apparatus for manufacturing a polarizing plate in which air bubbles are suppressed even if the thickness of the active energy ray-curable resin is reduced. The purpose is to do.

The present invention is a method for manufacturing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film, and an adhesive coating is applied to one side or both sides of a polarizing film by applying an active energy ray-curable adhesive. By sandwiching and pressing the laminate formed by the construction process and the transparent film laminated on one side or both sides of the polarizing film with an adhesive between a pair of bonding rolls rotating in the transport direction, the transparent film is formed. The present invention relates to a method for producing a polarizing plate, comprising a bonding step of bonding a polarizing film and an active energy ray irradiation step of irradiating a laminate with active energy rays to cure an adhesive.

In the adhesive coating step, the coating thickness of the active energy ray-curable adhesive applied to one side or both sides of the polarizing film is preferably 0.1 to 2.0 μm.

In one embodiment of the present invention, the adhesive coating step is a step of applying an active energy ray-curable adhesive to one or both sides of a polarizing film that is conveyed upward in the vertical direction.

In another embodiment of the present invention, the adhesive coating step is a step of applying an active energy ray-curable adhesive to one or both sides of a polarizing film that is conveyed downward in the vertical direction.

Further, the present invention is an apparatus for manufacturing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film, and the polarizing film is conveyed upward in the vertical direction and the polarizing film is conveyed upward in the vertical direction. An adhesive coating device for applying an active energy ray-curable adhesive to one or both sides of a polarizing film, and a transparent film laminated on one or both sides of the polarizing film via an adhesive. A pair of bonding rolls for bonding the transparent film and the polarizing film by sandwiching the body while transporting the body, and active energy rays for irradiating the laminated body with active energy rays to cure the adhesive. The present invention relates to an irradiation device and a manufacturing device including the irradiation device.

Further, the present invention is an apparatus for manufacturing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film, and the polarizing film is conveyed downward in the vertical direction and the polarizing film is conveyed downward in the vertical direction. An adhesive coating device for applying an active energy ray-curable adhesive to one or both sides of a polarizing film, and a laminate formed by laminating the transparent film on one or both sides of the polarizing film via an adhesive. A pair of bonding rolls for bonding the transparent film and the polarizing film by sandwiching the body while transporting the body, and active energy rays for irradiating the laminated body with active energy rays to cure the adhesive. The present invention relates to an irradiation device and a manufacturing device including the irradiation device.

According to the present invention, it is possible to provide a thin polarizing plate in which air bubbles are suppressed from being mixed.

It is a schematic side view which shows the 1st Embodiment of the polarizing plate manufacturing apparatus which concerns on this invention. It is a schematic side view which shows the 2nd Embodiment of the polarizing plate manufacturing apparatus which concerns on this invention. It is a schematic side view which shows the 3rd Embodiment of the polarizing plate manufacturing apparatus which concerns on this invention. It is a schematic side view which shows the 4th Embodiment of the polarizing plate manufacturing apparatus which concerns on this invention.

[Manufacturing method of polarizing plate]
The polarizing plate produced by the present invention is a polarizing plate formed by laminating a transparent film on one side or both sides of a polarizing film. The manufacturing method of the present invention includes an adhesive coating step of applying an active energy ray-curable adhesive to one or both sides of a polarizing film, and a transparent film laminated on one or both sides of the polarizing film via an adhesive. The laminated body is sandwiched between a pair of bonding rolls rotating in the transport direction and pressed to bond the transparent film and the polarizing film, and the laminated body is irradiated with active energy rays. It is provided with an active energy ray irradiation step of curing the adhesive. First, each material used in the production method of the present invention will be described.

(Polarizing film)
Specifically, the polarizing film used for the polarizing plate of the present invention is a uniaxially stretched polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented. The polyvinyl alcohol-based resin is obtained by saponifying the polyvinyl acetic acid-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith (for example, both ethylene and vinyl acetate). Polymer) and the like. Other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol-based resin is 85 mol% or more, preferably 90 mol% or more, and more preferably 98 to 100 mol%. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000. These polyvinyl alcohol-based resins may be modified, and for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes can also be used.

A film formed from such a polyvinyl alcohol-based resin is used as a raw film for a polarizing film. The method for forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a conventionally known appropriate method. The film thickness of the raw film made of a polyvinyl alcohol-based resin is not particularly limited, but is, for example, about 10 to 150 μm. It is usually supplied in roll form and has a thickness in the range of 20-100 μm, preferably in the range of 30-80 μm, and an industrially practical width in the range of 1500-6000 mm.

The original thickness of the commercially available polyvinyl alcohol-based film (Vinylon VF-PS # 7500, made by Kuraray / OPL film M-7500, made by Nippon Synthetic) is 75 μm, (Vinylon VF-PS # 6000, made by Kuraray, made by Vinylon VF-PE #). The original thickness of 6000 (manufactured by Kuraray) is 60 μm.

The polarizing film is usually a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye (dyeing treatment step), and a polyvinyl alcohol-based resin film having the dichroic dye adsorbed as boric acid. It is produced through a step of treating with an aqueous solution (boric acid treatment step) and a step of washing with water after the treatment with the boric acid aqueous solution (water washing treatment step).

Further, in the production of the polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched, and this uniaxial stretching may be performed before the dyeing treatment step or during the dyeing treatment step. It may be performed after the dyeing treatment step. When the uniaxial stretching is performed after the dyeing treatment step, the uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in these a plurality of steps.

The uniaxial stretching may be performed uniaxially between rolls having different peripheral speeds, or may be uniaxially stretched using a thermal roll. Further, it may be a dry stretching performed in the air, or a wet stretching performed in a state of being swollen with a solvent. The draw ratio is usually about 3 to 8 times.

Dyeing of the polyvinyl alcohol-based resin film with a dichroic dye in the dyeing treatment step is performed, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine, a dichroic dye and the like are used. For dichroic dyes, for example, C.I. I. Included are dichroic direct dyes consisting of disuazo compounds such as DIRECT RED 39 and dichroic direct dyes consisting of compounds such as trisazo and tetrakisazo. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

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

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

The boric acid treatment step is performed by immersing a polyvinyl alcohol-based resin film dyed with a dichroic dye in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye in the above-mentioned dyeing treatment step, the boric acid-containing aqueous solution used in this boric acid treatment step preferably contains potassium iodide. In this case, the amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 40 ° C. or higher, preferably 50 to 85 ° C., and more preferably 55 to 75 ° C.

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

In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment, and water washing treatment to obtain a polarizing film. The thickness of this polarizing film is usually in the range of 5 to 50 μm.

(Transparent film)
In the present invention, a transparent film is bonded to one side or both sides of the above-mentioned polarizing film. When transparent films are bonded 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 cycloolefin resins, cellulose acetate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and polybutylene terephthalates, polycarbonate resins, acrylic resins, and polypropylene. Examples of film materials that have been widely used in the field.

The cycloolefin-based resin is a thermoplastic resin (also referred to as a thermoplastic cycloolefin-based resin) having a monomer unit composed of a cyclic olefin (cycloolefin), such as norbornene and polycyclic norbornene-based monomers. The cycloolefin-based resin may be a hydrogenated compound of the above-mentioned cycloolefin ring-opening polymer or a ring-opening copolymer using two or more kinds of cycloolefins, and has a cycloolefin, a chain olefin, and a vinyl group. It may be an addition polymer with an aromatic compound or the like. In addition, those having a polar group introduced are also effective.

When a copolymer of a cycloolefin and a chain olefin and / or an aromatic compound having a vinyl group is used, examples of the chain olefin include ethylene and propylene, and examples of the aromatic compound having a vinyl group include Examples thereof include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the unit of the monomer composed of cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). In particular, when a ternary copolymer of a cycloolefin, a chain olefin and an aromatic compound having a vinyl group is used, the amount of the monomer unit composed of the cycloolefin can be relatively small as described above. In such a ternary copolymer, the unit of the monomer composed of a chain olefin is usually 5 to 80 mol%, and the unit of the monomer composed of an aromatic compound having a vinyl group is usually 5 to 80 mol%.

The cycloolefin-based resin is an appropriate commercially available product, for example, Topas (manufactured by Ticona), Arton (manufactured by JSR Co., Ltd.), ZEONOR (manufactured by ZEON CORPORATION), ZEONEX (Zeon Corporation). (Manufactured by Mitsui Kagaku Co., Ltd.), OXIS (manufactured by Okura Industrial Co., Ltd.) and the like can be preferably used. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, for example, pre-filmed cycloolefin resin films such as Scina (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), and Zeonoa Film (manufactured by Optes Co., Ltd.) are commercially available. Goods may be used.

The cycloolefin-based resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be imparted to the cycloolefin resin film. Stretching is usually carried out continuously while unwinding the film roll, and in a heating furnace, the rolling direction (longitudinal direction of the film), the direction perpendicular to the traveling direction (the width direction of the film), or both. Is stretched to. 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 a cycloolefin-based resin film is in a roll-wound state, the films tend to adhere to each other and cause blocking, so that the cycloolefin-based resin film is usually rolled after the protective film is attached. Further, since the surface activity of a cycloolefin resin film is generally inferior, the surface to be adhered to the polarizing film is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, and saponification treatment. Is preferable. Among them, plasma treatment that can be carried out relatively easily, particularly atmospheric pressure plasma treatment and corona treatment are preferable.

The cellulose acetate-based resin is a partial or complete esterified product of cellulose, and examples thereof include a film composed of an acetate ester of cellulose, a propionic acid ester, a butyric acid ester, and a mixed ester thereof. More specifically, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film and the like can be mentioned. Examples of such cellulose ester-based resin films include commercially available products such as Fujitac TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac TD80UF (manufactured by Fuji Film Co., Ltd.), and Fujitac TD80UZ (manufactured by Fuji Film Co., Ltd.). , KC8UX2M (manufactured by Konica Minolta Opto Co., Ltd.), KC8UY (manufactured by Konica Minolta Opto Co., Ltd.) Fujitac TD60UL (manufactured by Fuji Film Co., Ltd.), KC4UYW (manufactured by Konica Minolta Opto Co., Ltd.), KC6UAW (manufactured by Konica Minolta Opto Co., Ltd.) Co., Ltd.) and the like can be preferably used.

Further, as the transparent film, a cellulose acetate-based resin film imparted with a retardation characteristic is also preferably used. Commercially available products of cellol acetate resin films with such retardation characteristics include WV BZ 438 (manufactured by Fuji Film Co., Ltd.), KC4FR-1 (manufactured by Konica Minolta Opto Co., Ltd.), and KC4CR-1 (Konica Minolta Co., Ltd.). Examples include Opt Co., Ltd.) and KC4AR-1 (Konica Minolta Opto Co., Ltd.). Cellulose acetate is also called acetyl cellulose or cellulose acetate.

These cellulose acetate resin films easily absorb water, and the water content of the polarizing plate may affect the edge tarmi of the polarizing plate. The moisture content during the production of the polarizing plate is preferably closer to the equilibrium moisture content in the storage environment of the polarizing plate, for example, in a clean room production line or a roll-wound storage warehouse, and depends on the structure of the laminated film, for example, 2.0 to 3. It is about 5.5%, more preferably 2.5% to 3.0%. The numerical value of the water content of this polarizing plate is measured by the dry gravimetric method, and is the weight change after 105 ° C./120 minutes.

The thickness of the transparent film used for the polarizing plate of the present invention is preferably thin, but if it is too thin, the strength will decrease and the processability will be inferior. On the other hand, if it is too thick, problems such as deterioration of transparency and lengthening of curing time required after laminating occur. Therefore, the appropriate thickness of the transparent film is, for example, 5 to 200 μm, preferably 10 to 150 μm, and more preferably 10 to 100 μm.

In order to improve the adhesiveness between the adhesive and the polarizing film and / or the transparent film, the polarizing film and / or the transparent film is subjected to corona treatment, flame treatment, plasma treatment, ultraviolet treatment, primer coating treatment, saponification treatment, etc. Surface treatment may be applied.

Further, the transparent film may be subjected to surface treatments such as anti-glare treatment, anti-reflection treatment, hard coating treatment, antistatic treatment, and antifouling treatment, respectively, individually or in combination of two or more. Further, the transparent film and / or the transparent film surface protective layer may contain an ultraviolet absorber such as a benzophenone compound or a benzotriazole compound, or a plasticizer such as a phenyl phosphate compound or a phthalate ester compound.

Further, the transparent film has a function as a retardation film, a function as a brightness improving film, a function as a reflective film, a function as a semitransparent reflective film, a function as a diffusion film, a function as an optical compensation film, and the like. It can have a function. In this case, for example, such a function is performed by laminating an optical functional film such as a retardation film, a brightness improving film, a reflective film, a transflective reflective film, a diffusion film, and an optical compensation film on the surface of the transparent film. In addition to being able to have such a function, the transparent film itself can be provided with such a function. Further, the transparent film may have a plurality of functions, such as a diffusion film having a function of a brightness improving film.

For example, the transparent film described above is subjected to the stretching treatment described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, etc., or the treatment described in Japanese Patent No. 3168850, thereby forming a retardation film. Function can be added. The retardation characteristics of the retardation film can be appropriately selected, for example, the front retardation value is in the range of 5 to 100 nm, the thickness direction retardation value is in the range of 40 to 300 nm, and the like. Further, two or more layers having different central wavelengths of selective reflection are formed by forming micropores in the above transparent film by a method as described in JP-A-2002-1690.25 and JP-A-2003-29030. By superimposing the cholesteric liquid crystal layer of the above, the function as a brightness improving film can be imparted.

If a metal thin film is formed on the transparent film by vapor deposition, sputtering, or the like, the function as a reflective film or a transflective reflective film can be imparted. By coating the above-mentioned transparent film with a resin solution containing fine particles, the function as a diffusion film can be imparted. Further, by coating the transparent film with a liquid crystal compound such as a discotic liquid crystal compound and orienting the transparent film, the function as an optical compensation film can be imparted. Further, the transparent film may contain a compound that expresses a phase difference. Further, various optical functional films may be directly attached to the polarizing film by using a suitable adhesive. Commercially available optical functional films include, for example, brightness-enhancing films such as DBEF (manufactured by 3M, available from Sumitomo 3M Ltd. in Japan), and improved viewing angles such as WV films (manufactured by Fuji Film Co., Ltd.). Film, Arton Film (manufactured by JSR Co., Ltd.), Zeonoa Film (manufactured by Optis Co., Ltd.), Esina (manufactured by Sekisui Chemical Industry Co., Ltd.), VA-TAC (manufactured by Comicaminota Opto Co., Ltd.), Sumikalite (Sumitomo) Examples thereof include retardation films manufactured by Kagaku Co., Ltd.).

(Active energy ray-curable adhesive)
The polarizing film and the transparent film are bonded together via an active energy ray-curable adhesive. Examples of the active energy ray-curable adhesive include an adhesive composed of an epoxy resin composition containing an epoxy resin that is cured by irradiation with active energy rays from the viewpoints of weather resistance, refractive index, cationic polymerizable property, and the like. .. However, the present invention is not limited to this, and various active energy ray-curable adhesives (organic solvent-based adhesives, hot-melt adhesives, solvent-free adhesives) conventionally used in the production of polarizing plates are used. Etc.) can be adopted.

The epoxy resin means a compound having two or more epoxy groups in the molecule. From the viewpoint of weather resistance, refractive index, cationic polymerizable property, etc., the epoxy resin contained in the curable epoxy resin composition which is an adhesive is an epoxy resin containing no aromatic ring in the molecule (see, for example, Patent Document 1). Is preferable. Examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.

The hydrogenated epoxy resin is produced by a method of glycidyl etherifying a nuclear hydrogenated polyhydroxy compound obtained by selectively nuclear hydrogenating a polyhydroxy compound, which is a raw material of an aromatic epoxy resin, in the presence of a catalyst under pressure. Obtainable. Aromatic epoxy resins include, for example, bisphenol type epoxy resins such as bisphenol A diglycidyl ether, bisfer F diglycidyl ether, and bisphenol S diglycidyl ether; phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxy. Novolac type epoxy resins such as benzaldehydephenol novolac epoxy resin; polyfunctional epoxy resins such as tetrahydroxyphenylmethane glycidyl ether, tetrahydroxybenzophenone glycidyl ether, and epoxidized polyvinylphenol can be mentioned. Among the hydrogenated epoxy resins, hydrogenated bisphenol A glycidyl ether is preferable.

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

A compound in which _{one or more hydrogen atoms in the (CH 2} ) _m in the above formula are bonded to another chemical structure can be an alicyclic epoxy resin. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy resins, epoxy resins having an oxavicyclohexane ring (m = 3 in the above formula) and an oxabicycloheptane ring (m = 4 in the above formula) show excellent adhesiveness. Therefore, it is preferably used. Hereinafter, alicyclic epoxy resins that are preferably used will be specifically exemplified, but the present invention is not limited to these compounds.

(A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(In the formula, R ¹ and R ² represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms independently of each other).

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

(In the formula, R ³ and R ⁴ represent hydrogen atoms or linear alkyl groups having 1 to 5 carbon atoms independently of each other, and n represents an integer of 2 to 20).

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

(In the formula, R ⁵ and R ⁶ represent hydrogen atoms or linear alkyl groups having 1 to 5 carbon atoms independently of each other, and p represents an integer of 2 to 20).

(D) Epoxycyclohexylmethyl ethers of polyethylene glycol represented by the following formula (IV):

(In the formula, R ⁷ and R ⁸ represent hydrogen atoms or linear alkyl groups having 1 to 5 carbon atoms independently of each other, and q represents an integer of 2 to 10).

(E) Epoxycyclohexylmethyl ethers of alkanediol represented by the following formula (V):

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

(F) The diepoxy trispyro compound represented by the following formula (VI):

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

(G) Diepoxy monospiro compound represented by the following formula (VII):

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

(H) Vinyl cyclohexene epoxides represented by the following formula (VIII):

(In the formula, R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(I) Epoxy cyclopentyl ethers represented by the following formula (IX):

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

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

(In the formula, R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

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

(A) Esterized product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [Formula (I) In R ¹ = R ² = H compound],
(B) 4-Methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [Compounds of ^{R 1} = 4-CH ₃ , R ² = 4-CH ₃ in formula (I)],
(C) Esterized product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [in formula (II), R ³ = R ⁴ = H, n = 2 Compound],
(D) (7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [ ^{Compound of R 5} = R ⁶ = H, p = 4 in formula (III)] ,
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [In formula (III), R ⁵ = 4-CH ₃ , R ⁶ = 4-CH ₃ , p = 4 compounds],
(F) Ethereate of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [In formula (V), R ⁹ = R ¹⁰ = H, r = Compound 2].

In addition, examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylrol propane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene Diglycidyl ether of glycol; Polyether polyol poly obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol, and glycerin. Glycidyl ether and the like can be mentioned.

As the epoxy resin constituting the adhesive composed of the epoxy resin composition, only one type may be used alone, or two or more types may be used in combination. The epoxy equivalent of the epoxy resin used in this composition is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent. If the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizing plate after curing may decrease, or the adhesive strength may decrease. On the other hand, if it exceeds 3,000 g / equivalent, the compatibility with other components contained in the adhesive may decrease.

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

The method of curing the adhesive by irradiating with active energy rays using a photocationic polymerization initiator enables curing at room temperature, reduces the need to consider the heat resistance of the polarizing film or distortion due to expansion, and reduces the need to consider distortion due to expansion between films. It is advantageous in that it can adhere well. Further, since the photocationic polymerization initiator acts catalytically with light, it is excellent in storage stability and workability even when mixed with an epoxy resin.

Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; and iron-allene complexes.

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

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, and 4,4'-bis (diphenylsulfonio) diphenylsulfide bis ( Hexafluorophosphate), 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bis (hexafluoroantimonate), 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio) ] Diphenylsulfide bis (hexafluorophosphate), 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (penta) Fluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4 -(P-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like can be mentioned.

Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) metanide and the like can be mentioned.

Commercially available products of these photocationic polymerization initiators are easily available. For example, under the trade names of "Kayarad PCI-220" and "Kayarad PCI-620" (above, Nippon Kayaku Co., Ltd.) ), "UVI-6990" (manufactured by Union Carbide), "Adeka Optomer SP-150" and "Adeka Optomer SP-170" (above, manufactured by ADEKA Corporation), "CI-5102", " "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S" and "CIP-2064S" (all manufactured by Nippon Soda Corporation), "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 (manufactured by Kagaku Co., Ltd.), "PI-2074" (manufactured by Rhodia), and the like can be mentioned.

As the photocationic polymerization initiator, only one type may be used alone, or two or more types may be mixed and used. Among them, aromatic sulfonium salts are preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength.

The blending amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less with respect to 100 parts by weight of the epoxy resin. If the blending amount of the photocationic polymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the epoxy resin, the curing tends to be insufficient, and the mechanical strength and the adhesive strength tend to decrease. Further, when the blending amount of the photocationic polymerization initiator exceeds 20 parts by weight with respect to 100 parts by weight of the epoxy resin, the ionic substance in the cured product increases, so that the hygroscopicity of the cured product becomes high and the durability performance is improved. May decrease.

When a photocationic polymerization initiator is used, the curable epoxy resin composition can further contain a photosensitizer, if necessary. By using a photosensitizer, the reactivity of cationic polymerization can be improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducing dyes and the like.

More specific examples of photosensitizers include, for example, benzoin methyl ether, benzoin isopropyl ether, and benzoin derivatives such as α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o. Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2 Anthraquinone derivatives such as -chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacrydone and N-butylacridone; other α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, There are halogen compounds and the like. Only one type of photosensitizer may be used alone, or two or more types may be used in combination. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.

The epoxy resin contained in the adhesive is cured by photocationic polymerization, but may be cured by both photocationic polymerization and thermal cationic polymerization. In the latter case, it is preferable to use a photocationic polymerization initiator and a thermal cationic polymerization initiator in combination.

Examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thiolanium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, amineimide and the like. These thermal cationic polymerization initiators can be easily obtained as commercial products. For example, all of them are trade names such as "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (all manufactured by ADEKA Corporation) and "CI". -2639 "and" CI-2624 "(above, manufactured by Nippon Soda Corporation)," Sun Aid SI-60L "," Sun Aid SI-80L "and" Sun Aid SI-100L "(above, manufactured by Sanshin Chemical Industry Co., Ltd.) And so on.

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

Oxetane is a compound having a 4-membered ring ether in the molecule, for example, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3 Examples thereof include −ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, and phenol novolac oxetane. These oxetane types can be easily obtained as commercial products. For example, all of them have trade names such as "Aron oxetane OXT-101", "Aron oxetane OXT-121", and "Aron oxetane OXT-211". , "Aron Oxetane OXT-221" and "Aron Oxetane OXT-212" (all manufactured by Toa Synthetic Co., Ltd.) and the like. These oxetane are usually contained in the curable epoxy resin composition in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight.

As the polyols, those having no acidic group other than the phenolic hydroxyl group are preferable. For example, a polyol compound having no functional group other than the hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol compound having a phenolic hydroxyl group, and a polycarbonate. Examples thereof include polyols. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and preferably 1,000 or less. These polyols are usually contained in the curable epoxy resin composition in a proportion of 50% by weight or less, preferably 30% by weight or less.

Active energy ray-curable adhesives include ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, leveling agents, plasticizers, defoamers, etc. Additives can be blended. Examples of the ion trap agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based and mixed-based inorganic compounds, and examples of the antioxidant include hindered phenol-based antioxidants. And so on.

The active energy ray-curable adhesive can be used as a solvent-free adhesive that does not substantially contain a solvent component, but since each coating method has an optimum viscosity range, it is necessary to adjust the viscosity. A solvent may be contained. As the solvent, it is preferable to use a solvent that dissolves the epoxy resin composition and the like well without deteriorating the optical performance of the polarizing film. For example, hydrocarbons typified by toluene and esters typified by ethyl acetate. Examples of organic solvents such as the above can be mentioned. The viscosity of the active energy ray-curable adhesive used in the present invention is, for example, in the range of about 5 to 1000 mPa · s, preferably 10 to 200 mPa · s, and more preferably 20 to 100 mPa · s.

(First Embodiment)
Next, a manufacturing apparatus and a manufacturing method for the polarizing plate of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a first embodiment of the polarizing plate manufacturing apparatus of the present invention.

In the polarizing plate manufacturing apparatus shown in FIG. 1, the adhesive coating devices 11 and 12 for applying an adhesive to both surfaces of the polarizing film 1, the transparent films 2 and 3 and the polarizing film 1 are laminated and laminated. Adhesive rolls (nip rolls) 51 and 52 for obtaining the body 4, rolls 13 for bringing the transparent films 2 and 3 and the polarizing film 1 into close contact with each other in the laminated body 4, and positions facing the outer peripheral surface of the rolls 13. The first active energy ray irradiating devices 14 and 15 installed in the above, the second and subsequent active energy ray irradiating devices 16 to 18 installed further downstream in the conveying direction, and the conveying nip roll 19 are conveyed. They are provided in order along the direction.

First, the active energy ray-cured by the adhesive coating devices 11 and 12 on both sides of the polarizing film 1 which is continuously unwound from the rolled state and conveyed upward in the vertical direction by a conveying means (not shown). The mold adhesive is applied (adhesive coating process).

Then, a laminate formed by laminating transparent films 2 and 3 coated with an adhesive on both sides of the transparent films 2 and 3 continuously unwound from a rolled state via an adhesive is formed. By pressing at least one of the bonding rolls in the direction of the other bonding roll while being sandwiched between the pair of bonding rolls 51 and 52 rotating in the transport direction, the transparent film 1 and the polarizing film 2, 3 is bonded to form a laminated body 4 (bonding step).

Next, in the process of transporting the laminated body 4 while adhering it to the outer peripheral surface of the roll 13, the first active energy ray irradiating devices 14 and 15 irradiate the outer peripheral surface of the roll 13 with active energy rays and bond them. The agent is polymerized and cured (active energy ray irradiation step).

The second and subsequent active energy ray irradiation devices 16 to 18 arranged on the downstream side in the transport direction are devices for completely polymerizing and curing the adhesive, and can be added or omitted as necessary. Finally, the laminated body 4 passes through the transport nip roll 19 and is wound on the winding roll 20 as a polarizing plate (polarizing plate winding step). Hereinafter, each step will be described in detail.

<Adhesive coating process>
The method of applying the adhesive to the polarizing film 1 is not particularly limited, but various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Of these, gravure rolls are preferable as the adhesive coating devices 11 and 12, considering the thin film coating, the degree of freedom of the pass line, and the wide width.

When the adhesive is applied using the gravure roll as the adhesive coating devices 11 and 12, the thickness (coating thickness) of the applied adhesive is preferably 0.1 to 2.0 μm, which is more preferable. Is 0.2 μm to 1.0 μm. In the present embodiment, the unevenness of the surface of the polarizing film 1 can be covered with the adhesive by directly applying the adhesive to the surface of the polarizing film 1, so that the bubbles at the time of bonding with the transparent films 2 and 3 are generated. Occurrence can be suppressed. When the transparent film and the polarizing film are bonded to each other via the adhesive applied on the transparent film, bubbles that are considered to be caused by the unevenness of the surface of the polarizing film are likely to be generated, and the coating thickness of the adhesive is increased. Although it is possible to reduce the generation of bubbles, it may be difficult to suppress the generation of bubbles when the coating thickness of the adhesive is 2.0 μm or less. In the adhesive coating method of the present embodiment, even if the thickness of the adhesive is within the above range, the generation of air bubbles at the time of bonding can be suppressed.

The coating thickness of the adhesive is adjusted by the draw ratio, which is the speed ratio of the gravure roll to the line speed of the transparent film. Generally, by adjusting the draw ratio (gravure roll speed / line speed) to 0.5 to 10, the coating thickness of the adhesive can be adjusted to 0.1 to 2.0 μm. More specifically, the line speed of the polarizing film 1 is set to 10 to 100 m / min, the gravure roll is rotated in the direction opposite to the transport direction of the polarizing film 1, and the speed of the gravure roll is set to 5 to 1000 m / min. , The coating thickness of the adhesive can be adjusted to 0.1 to 2.0 μm.

In the adhesive coating step, as described above, the polarizing film 1 is conveyed upward in the vertical direction, and the adhesive is applied from both sides of the polarizing film 1 by the adhesive coating devices 11 and 12. Although the adhesive can be applied to the polarizing film transported in the horizontal direction from below, it is difficult to continuously apply the adhesive from above with a normal coating device because the adhesive drips down. Therefore, in the case of the method for manufacturing a polarizing plate in which a transparent film is bonded to both sides of the polarizing film 1, an adhesive is applied from both sides to the polarizing film 1 which is conveyed upward in the vertical direction as in the apparatus of the present embodiment. The method is useful. The term "vertically upward" as used herein is not limited to the vertical direction as long as the adhesive can be applied from both side surfaces, and is not limited to the vertical direction, for example, within ± 5 degrees with respect to the vertical upward direction. It shall include the direction.

The adhesive coating devices 11 and 12 arranged on both sides of the conveyed polarizing film 1 are preferably arranged at positions where they do not face each other. The coating thickness of the adhesive can be adjusted by the pressure applied to the polarizing film 1 by pressing the adhesive coating devices 11 and 12, but it is difficult to adjust the pressure when they are arranged at opposite positions. Because it becomes.

After preparation, the adhesive is usually at a predetermined temperature within the range of 15 to 40 ° C. ± 5 ° C. (for example, 30 ° C. ± 5 ° C. when the predetermined temperature is 30 ° C.), preferably ± 3 ° C., more preferably. It is applied in an environment adjusted to ± 1 ° C.

<Lasting process>
In this step, transparent films 2 and 3 continuously unwound from a rolled state are laminated on both sides of the polarizing film 1 coated with the adhesive by the above steps via the adhesive. The transparent film 1 and the polarizing film are formed by pressing the laminated body between the pair of bonding rolls 51 and 52 rotating in the transport direction, for example, in the direction of the bonding roll 52. A few are bonded together to form a laminated body 4.

The pressure applied to the laminate by pressing is not particularly limited, but when a metal roll and a rubber roll are used, the instantaneous pressure in the Fujifilm two-seat type press case is 0.2 to 3.0 MPa. Is preferable, and more preferably 0.5 to 2.3 MPa.

The pair of laminating rolls may have a difference in peripheral speed between one laminating roll and the other laminating roll. For example, the peripheral speed of the bonding roll (first bonding roll) installed on the surface side to be bonded to the liquid crystal panel of the laminated body 4 is the peripheral speed of the bonding roll (second bonding roll) on the opposite side. It is preferably faster than the peripheral speed. As a result, it is possible to give the obtained polarizing plate a curl (normal curl) such that the surface to be bonded to the liquid crystal panel is convex and the surface on the opposite side is concave. When the obtained polarizing plate is given a curl (reverse curl) such that the surface to be bonded to the liquid crystal panel is concave and the surface on the opposite side is convex, the polarizing plate is bonded to the liquid crystal cell. When doing so, problems such as biting air bubbles in the central part are likely to occur. In this case, it is preferable to use a metal roll as the first laminating roll and a rubber roll as the second laminating roll.

Further, when the peripheral speed of the second bonding roll is 1, the ratio of the peripheral speed of the first bonding roll is more preferably 1.005 to 1.0200. If the peripheral speed of the first bonding roll is faster than this range, the curl amount of the positive curl becomes too large, causing problems such as biting air bubbles at the ends when the polarizing plate is bonded to the liquid crystal cell. This is because it is easy, and when it is placed in a harsh environment, the positive curl is further promoted and the end portion of the polarizing plate may be peeled off from the liquid crystal cell.

<Active energy ray irradiation process>
The roll 13 has a convex curved surface whose outer peripheral surface is mirror-finished, and the laminated body 4 is conveyed while being in close contact with the surface thereof, and the adhesive is polymerized and cured by the active energy ray irradiating devices 14 and 15 in the process. .. The diameter of the roll 13 is not particularly limited in order to polymerize and cure the adhesive so that the laminate 4 is sufficiently adhered. The roll 13 may be driven or rotationally driven by the movement of the line of the laminated body 4, or may be fixed so that the laminated body 4 slides on the surface. Further, the roll 13 may act as a cooling roll for dissipating heat generated in the laminated body 4 at the time of polymerization curing by irradiation with active energy rays. In that case, the surface temperature of the cooling roll is preferably set to 20 to 30 ° C.

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

The light irradiation intensity of the active energy ray-curable adhesive is determined by the composition of the adhesive and is not particularly limited, but is preferably 10 to ^{5000 mW / cm 2.} If the light irradiation intensity of the resin composition is ^{less than 10 mW / cm 2} , the reaction time becomes too long, and if it ^{exceeds 5000 mW / cm 2} , the heat radiated from the lamp and the heat generated during the polymerization of the composition cause adhesion. There is a possibility of causing yellowing of the epoxy resin composition, which is a constituent material of the agent, and deterioration of the polarizing film. The irradiation intensity is preferably an intensity in a wavelength region effective for activating the photocationic polymerization initiator, more preferably an intensity in a wavelength region having a wavelength of 400 nm or less, and further preferably a wavelength region having a wavelength of 280 to 320 nm. Is the strength in.

The irradiation time of the active energy ray on the active energy ray-curable adhesive is controlled for each composition to be cured, and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 mJ / cm ² or more, it is preferable to set preferably such that the 10~5,000mJ / cm ^2. If the integrated light intensity to the adhesive is ^{less than 10 mJ / cm 2} , the active species derived from the initiator are not sufficiently generated, and the adhesive is not sufficiently cured. On the other hand, if the integrated light intensity ^{exceeds 5,000 mJ / cm 2} , the irradiation time becomes very long, which is disadvantageous for improving productivity.

In the present invention, the laminate is irradiated with active energy rays to polymerize and cure the adhesive, but polymerization and curing by heating may be used in combination.

When the active energy rays are ultraviolet rays, in the step of irradiating the laminated body 4 with the active energy rays, the irradiation time is 0.1 while applying a tension of 100 to 800 N / m to the laminated body 4 in the longitudinal direction (conveying direction). It is preferable that the laminated body 4 is conveyed at a line speed of 1 second or more. Further, the irradiation intensity of ultraviolet rays ^{is preferably 10 mW / cm 2} or more.

If the integrated light amount of the active energy rays by the active energy ray irradiating devices 14 and 15 is insufficient, the second and subsequent active energy ray irradiating devices 16 to 18 are further provided to additionally irradiate the active energy rays to form a laminated body. It is preferable to accelerate the curing of the adhesive of 4. Integrated light intensity in these whole process is 10 mJ / cm ² or more, preferably it is preferably set so that 10~5,000mJ / cm ^2. As described above, in the step of irradiating the active energy rays, it is preferable that the irradiation of the active energy rays is performed in a plurality of times.

In order to surely cure the adhesive at the end of the polarizing plate (laminate), for example, a method of arranging "Light Hammer 10" manufactured by FUSION, which is an electrodeless D bulb lamp, so as to cross the film running. Can be mentioned.

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

<Polarizing plate winding process>
The tension for winding the laminated body (polarizing plate) 4 is 30 N / cm ^{2 to} 150 N / cm ² . Preferably, it is 30 N / cm ^{2 to} 120 N / cm ² . If it is less than 30 N / cm ^2, it is not preferable because the winding shift occurs when the long roll winding is transferred. If it is larger than 150 N / cm ² , the winding tightness is strong and tarmi is likely to occur.

The longer the winding length, the more likely it is that winding tightening (a phenomenon in which it becomes difficult to return to a flat state when unwound) occurs at the same tension, so the tension is continuously or gradually reduced while winding the polarizing plate around the core. You may let me. Even in the method of lowering the tension by applying such a so-called taper, the tension at that time is set to 150 N / cm ² or less.

The length of the polarizing plate wound around the core is not particularly limited, but is preferably 100 m or more and 4000 m or less.

The diameter of the cylindrical core is preferably 6 inches to 12 inches. Larger core diameters are preferred, more preferably 11 inches, 12 inches, etc., but larger cores make transport and storage difficult.

Since the material of the cylindrical core is used in a clean room, it is difficult to generate dust by itself, and there is no particular limitation as long as an appropriate strength can be secured so that a wide polarizing plate can be wound, but FRP (glass fiber reinforced plastic) Etc. can be selected.

(Second embodiment)
FIG. 2 is a schematic view showing a second embodiment of the polarizing plate manufacturing apparatus of the present invention. In the manufacturing apparatus of the second embodiment, the polarizing film 1 continuously unwound from the rolled state is conveyed downward in the vertical direction by a conveying means (not shown), and is conveyed upward in the vertical direction. It is different from the first embodiment. Since other configurations are the same as those in the first embodiment, description thereof will be omitted. The term "vertically downward" in the present specification is not limited to the vertical direction as long as the adhesive can be applied from both side surfaces, and is, for example, in the range of ± 5 degrees with respect to the vertical downward direction. It shall include the direction inside.

In the manufacturing apparatus of the present embodiment as well, as in the first embodiment, the adhesive can be applied from both sides of the polarizing film 1, so that the polarizing films 2 and 3 are bonded to both sides of the polarizing film 1. It is useful for the method of manufacturing plates. In the present embodiment, the unevenness of the surface of the polarizing film 1 can be covered with the adhesive by directly applying the adhesive to the surface of the polarizing film 1, so that the bubbles at the time of bonding with the transparent films 2 and 3 are generated. Occurrence can be suppressed.

(Third Embodiment)
FIG. 3 is a schematic view showing a third embodiment of the polarizing plate manufacturing apparatus of the present invention. In the manufacturing apparatus of the third embodiment, the active energy rays are not irradiated in the state where the laminated body is in close contact with the roll, and therefore the roll 13 and the active energy ray irradiation devices 14 and 15 in FIG. 1 are not provided. Only different from the manufacturing apparatus of the first embodiment. In the manufacturing apparatus of the present embodiment, instead of the first active energy ray irradiating devices 14 and 15 in FIG. 1, the laminated body 4 is irradiated with active energy rays by the active energy ray irradiating devices 16 and 17 and 18 and adhered. The agent is polymerized and cured. The preferable conditions such as the light irradiation intensity and the integrated light amount in the active energy ray irradiation step are the same as the preferable conditions in the active energy ray irradiation step in the first embodiment. Since the other configurations and other steps are the same as those in the first embodiment, the description thereof will be omitted.

In the manufacturing apparatus of the present embodiment as well, as in the first embodiment, the adhesive can be applied from both sides of the polarizing film 1, so that the polarizing films 2 and 3 are bonded to both sides of the polarizing film 1. It is useful for the method of manufacturing plates. In the present embodiment, the unevenness of the surface of the polarizing film 1 can be covered with the adhesive by directly applying the adhesive to the surface of the polarizing film 1, so that the bubbles at the time of bonding with the transparent films 2 and 3 are generated. Occurrence can be suppressed.

(Fourth Embodiment)
In this embodiment, the polarizing plate is manufactured from one polarizing film and one transparent film. Then, in the adhesive coating step, an adhesive is applied to one side of one polarizing film, and in the bonding step, the polarizing film and the transparent film are brought into contact with the adhesive of the polarizing film on one side of the transparent film. In a laminated state, the polarizing film and the transparent film are bonded to each other by sandwiching them between a pair of bonding rolls.

Next, the manufacturing method of the present embodiment will be described with reference to the drawings. FIG. 4 is a schematic view showing a fourth embodiment of the polarizing plate manufacturing apparatus of the present invention.

In the polarizing plate manufacturing apparatus shown in FIG. 4, the adhesive coating apparatus 11 for applying an adhesive to one side of the polarizing film 1 and the polarizing film 1 and the transparent film 2 are laminated to obtain a laminate 4. The bonding rolls (nip rolls) 51 and 52 for this purpose, the roll 13 for bringing the polarizing film 1 and the transparent film 2 into close contact with each other in the laminated body 4, and the first roll 13 installed at a position facing the outer peripheral surface of the roll 13. The active energy ray irradiation devices 14 and 15 of the above, the second and subsequent active energy ray irradiation devices 16 to 18 installed on the downstream side in the transport direction, and the transport nip roll 19 are provided in order along the transport direction. Has been done.

First, an active energy ray-curable adhesive is applied by an adhesive coating device 11 to one side of a polarizing film 1 that is continuously unwound from a rolled state (adhesive coating step).

Then, a laminate in which the polarizing film 1 coated with the adhesive is laminated via the adhesive on one side of the transparent film 2 continuously unwound from the rolled state is transferred in the transport direction. The polarizing film 2 and the transparent film 1 are bonded by pressing at least one bonding roll in the direction of the other bonding roll while being sandwiched between the pair of rotating bonding rolls 51 and 52. , The laminated body 4 is formed (bonding step).

Next, in the process of transporting the laminated body 4 while adhering it to the outer peripheral surface of the roll 13, the first active energy ray irradiating devices 14 and 15 irradiate the outer peripheral surface of the roll 13 with active energy rays and bond them. The agent is polymerized and cured (active energy ray irradiation step). The second and subsequent active energy ray irradiation devices 16 to 18 arranged on the downstream side in the transport direction are devices for completely polymerizing and curing the adhesive, and can be added or omitted as necessary. The details of each step are the same as those in the first embodiment and will be omitted.

In the manufacturing apparatus of the present embodiment, since the adhesive can be applied from one side of the polarizing film 1, it is useful for a method of manufacturing a polarizing plate in which a transparent film is bonded to one side of the polarizing film. In the present embodiment, since the unevenness of the polarizing film surface can be covered with the adhesive by directly applying the adhesive to the surface of the polarizing film, the generation of air bubbles at the time of bonding the transparent film 2 can be suppressed. Can be done.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
In this embodiment, a polarizing plate formed by laminating one polarizing film and one transparent film was produced by using an apparatus as shown in FIG. 4 described in the fourth embodiment.

A 40 μm-thick triacetyl cellulose film “KC4CR-1” (manufactured by Konica Minolta) and a 135 μm-thick composite film laminate with a polarizing film on the outermost surface (polyvinyl alcohol film “Vinylon VF-PS # 7500” (Clare). This is a polarizing film made of (manufactured by), a cellulose ester resin film "KC4UYW" (manufactured by Konica Minolta Opto Co., Ltd.) and a surface protective film "NBO-0424" (manufactured by Fujimori Kogyo Co., Ltd.) with an adhesive layer on the KC4UYW surface. The epoxy resin composition "KR-70T" (manufactured by ADEKA, viscosity: 44 mPa · s), which is an ultraviolet curable adhesive, is prepared on the surface of the polarizing film of the composite film laminate. Was coated using an adhesive coating device while transporting the film vertically upward as shown in FIG. 4 and the like. At this time, the line speed of the polarizing film laminate in the adhesive coating apparatus was set to 25 m / min, and the gravure roll was rotated in the direction opposite to the transport direction of the laminate to set the thickness of the adhesive layer to 1.0 μm.

Next, the laminate in which the triacetyl cellulose film is laminated so as to be in contact with the adhesive applied to the polarizing film is sandwiched between a pair of nip rolls (bonding rolls) having a diameter of 250 mm and pressed at a pressure of 1.0 MPa. As a result, the triacetyl cellulose film and the polarizing film were bonded together.

The laminate to which the above two types of films are bonded is transferred at a line speed of 25 m / min while applying a tension of 600 N / m in the longitudinal direction, and the total integrated light amount (light irradiation intensity in the wavelength region of wavelength 280 to 320 nm). Cumulative amount) is about 250 mJ / cm ² (Measuring instrument: UV manufactured by Fusion UV)
It was irradiated with ultraviolet rays (UVB) (measured by Power Pack II).

When the obtained polarizing plate was visually observed, no bubbles were observed between the polarizing film and the triacetyl cellulose film.

[Comparative Example 1]
An epoxy resin composition, which is an ultraviolet curable adhesive, is applied to one side of a triacetyl cellulose film using an adhesive coating device so as to have a thickness of 1.0 μm, and the coated adhesive is used. A polarizing plate was produced in the same manner as in Example 1 except that it was bonded to the polarizing film of the composite film laminate.

When the obtained polarizing plate was visually observed, bubbles were observed between the polarizing film and the triacetyl cellulose film.

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

1 Polarizing film, 2, 3 Transparent film, 4 Laminated body (polarizing plate), 11, 12 Adhesive coating device, 13 rolls (cooling roll), 14, 15, 16, 17, 18 Active energy ray irradiation device, 19 Nip roll for transport, 20 take-up roll, 51, 52 laminating roll.

Claims (6)

A method for manufacturing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film.
An adhesive coating step of applying an active energy ray-curable adhesive to one or both sides of the polarizing film that is continuously unwound from a rolled state.
A pair of laminated bodies in which the transparent film continuously unwound from a rolled state is laminated on one side or both sides of the polarizing film via the adhesive, and the laminated body is rotated in the transport direction. A bonding step of bonding the transparent film and the polarizing film by sandwiching the film between rolls and pressing the film.
A method for producing a polarizing plate, comprising an active energy ray irradiation step of irradiating the laminate with active energy rays to cure the adhesive. A method for manufacturing a polarizing plate in which a transparent film is bonded to one side or both sides of a polarizing film.
An adhesive coating step of applying an active energy ray-curable adhesive to one or both sides of the polarizing film configured as a continuous film.
A laminate in which the transparent film configured as a continuous film is laminated on one side or both sides of the polarizing film via the adhesive is sandwiched between a pair of bonding rolls rotating in the transport direction and pressed. Therefore, the bonding step of bonding the transparent film and the polarizing film, and
A method for producing a polarizing plate, comprising an active energy ray irradiation step of irradiating the laminate with active energy rays to cure the adhesive. The polarizing plate according to claim 1 or 2, wherein the adhesive coating step is a step of applying an active energy ray-curable adhesive to one or both sides of the polarizing film that is conveyed upward in the vertical direction. Production method. The polarizing plate according to claim 1 or 2, wherein the adhesive coating step is a step of applying an active energy ray-curable adhesive to one or both sides of the polarizing film that is conveyed downward in the vertical direction. Production method. A polarizing plate manufacturing device in which a transparent film is bonded to one or both sides of a polarizing film.
Conveying means for feeding transportable said polarizing film from a state wound into a roll was continuously fed upward in the vertical direction,
An adhesive coating device for applying an active energy ray-curable adhesive to one or both sides of the polarizing film that is conveyed upward in the vertical direction.
The transparent film continuously unwound from the rolled state is laminated on one side or both sides of the polarizing film via the adhesive, and the laminated body is sandwiched while being conveyed. A pair of bonding rolls for bonding the transparent film and the polarizing film, and
A polarizing plate manufacturing apparatus including an active energy ray irradiation device for irradiating the laminate with active energy rays to cure the adhesive. A polarizing plate manufacturing device in which a transparent film is bonded to one or both sides of a polarizing film.
Conveying means for feeding transportable said polarizing film from a state wound into a roll was continuously fed downward in the vertical direction,
An adhesive coating device for applying an active energy ray-curable adhesive to one or both sides of the polarizing film that is conveyed downward in the vertical direction.
The transparent film continuously unwound from the rolled state is laminated on one side or both sides of the polarizing film via the adhesive, and the laminated body is sandwiched while being conveyed. A pair of bonding rolls for bonding the transparent film and the polarizing film, and
A polarizing plate manufacturing apparatus including an active energy ray irradiation device for irradiating the laminate with active energy rays to cure the adhesive.

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