KR101747559B1 - Polarizing plate - Google Patents

Abstract

The present invention provides a polarizing plate having a protective film on at least one surface of a polarizing film, wherein the polarizing film has a pricking strength per unit film thickness of 5.8 gf / 탆 or more and an end face of the polarizing plate is cut .

Description

POLARIZING PLATE

The present invention relates to a polarizer useful as one of optical components constituting a liquid crystal display or the like.

The polarizing plate is widely used as a polarizing light supplying device in a display device such as a liquid crystal display device and also as a polarizing light detecting device. As a polarizing plate, a protective film is generally bonded to one or both surfaces of a polarizing film by using an adhesive. In recent years, the thickness of a polarizing plate has been required in accordance with the thinness of a liquid crystal display device.

When a polarizing plate is applied to a liquid crystal display device, it is usually cut into a shape such as a rectangular shape and a predetermined dimension in accordance with the liquid crystal cell. From the viewpoint of designability, as the frame of TV or mobile becomes narrower, there is a strong demand for dimensional accuracy of the polarizing plate. In order to satisfy such a demand, it is also considered to finish by cutting the end face (cut face). For example, in JP-A-2001-54845 (Patent Document 1), a plurality of polarizing plates are stacked, and a plurality of polarizing plates are stacked on the end faces, And the end face is finely cut by the rotary blade.

It is known that when the polarizing plate is cut and cut, cracks are generated in the polarizing film due to the cutting blade or the cutting edge. Japanese Patent Application Laid-Open No. 2004-29367 (Patent Document 2) discloses that the elastic modulus of the polarizing plate at the time of cutting is controlled so as to prevent cracking of the polarizer at the time of cutting the polarizing plate. Japanese Patent Application Laid-Open No. 2009-37228 (Patent Document 3) discloses that a peripheral end face is cut by a laser so as to prevent minute cracks from being formed on the polarizing film starting from the mark of full-back cutting.

Patent Document 1: JP-A-2001-54845 Patent Document 2: Japanese Patent Application Laid-Open No. 2004-29367 Patent Document 3: JP-A-2009-37228

As shown in Fig. 5, in the polarizing plate, when the end face is cut, depending on the cutting condition, a problem that the polarizing film is scratched by the cutting tool and falls off (hereinafter also referred to as a "missing crack") There was a case.

An object of the present invention is to provide a polarizing plate in which cracking cracks of the polarizing film do not occur at the time of cutting the end face.

The present invention provides the following polarizing plate.

[1] A polarizing plate having a protective film on at least one surface of a polarizing film,

The penetration strength per unit film thickness of the polarizing film is 5.8 gf /

And the end face of the polarizing plate is cut.

[2] The polarizer according to [1], wherein the polarizing film has a thickness of 10 m or less.

[3] The polarizing plate described in [1] or [2], wherein the polarizing plate comprises the protective film on both surfaces of the polarizing film.

[4] The polarizer according to any one of [1] to [3], wherein the polarizing plate and the protective film are bonded via an active energy ray-curable adhesive.

According to the polarizing plate of the present invention, it is possible to provide a polarizing plate in which the polarizing film is not cracked well during cutting at the end face.

1 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate according to the present invention.
2 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate according to the present invention.
3 is a side view and a front view showing an example of a cutting tool used in the embodiment of the present invention.
Fig. 4 is a schematic perspective view showing an end face machining apparatus having the cutting tool shown in Fig. 3; Fig.
Fig. 5 is a photograph showing an optical microscope photograph of an end face of a polarizing plate in which a missing crack is generated by cutting.

[Polarizer]

1 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate according to the present invention. Like the polarizing plate 2 shown in Fig. 1, the polarizing plate of the present invention may be a polarizing plate with a single-sided protective film having a polarizing film 5 and a first protective film 7 laminated on one side thereof . The first protective film 7 can be laminated on the polarizing film 5 through the first adhesive layer 6.

The polarizing plate according to the present invention may be obtained by further bonding a protective film to the other surface of the polarizing film 5. Specifically, as in the polarizing plate 3 shown in Fig. 2, A first protective film 7 laminated on one surface thereof, and a second protective film 9 laminated on the other surface thereof. The second protective film 9 can be laminated on the polarizing film 5 through the second adhesive layer 8. Hereinafter, when it is not necessary to distinguish the first protective film 7 from the second protective film 9, it is referred to as a "protective film", and the first adhesive layer 6 and the second adhesive layer 8 are distinguished from each other It is referred to as an " adhesive layer ".

The polarizing plate of the present invention is characterized in that the pricking intensity per unit film thickness of the polarizing film (5) is 5.8 gf / 占 퐉 or more and the end face of the polarizing plate is cut. When the penetration strength per unit film thickness of the polarizing film is 5.8 gf / 占 퐉 or more, it is possible to suppress occurrence of a missing crack of the polarizing film 5 at the time of cutting the end face of the polarizing plate. The penetration strength of the polarizing film is preferably 5.8 gf / 탆 or more and 15.0 gf / 탆 or less, more preferably 5.8 gf / 탆 or more and 10.0 gf / 탆 or less, and further preferably 5.8 gf / 탆 or more and 7.0 gf / .

The polarizing plate according to the present invention may be a polarizing plate disposed on the visible (front) side of an image display device such as a liquid crystal cell when introduced into an image display device such as a liquid crystal display device, (Backlight side of the device).

(1) polarizing film

The polarizing film may be one in which the dichroic dye is adsorbed and oriented on the uniaxially stretched polyvinyl alcohol-based resin layer. The thickness of the polarizing film is usually 20 mu m or less, so that the thickness of the polarizing plate can be reduced. In the present invention, a polarizing film having a thickness of 10 mu m or less is preferable, and more preferably, 8 mu m or less. The thinner the polarizing film is, the more easily a cracking crack is likely to occur. Therefore, when the thickness is 10 μm or less, the effect of suppressing the occurrence of cracking cracks according to the present invention becomes more remarkable.

As the polyvinyl alcohol-based resin, saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like.

The degree of saponification of the polyvinyl alcohol resin may be in the range of 80 mol% or more, preferably 90 to 99.5 mol%, and more preferably 94 to 99 mol%. The polyvinyl alcohol resin may be a partially modified polyvinyl alcohol, and examples thereof include polyvinyl alcohol resins such as olefins such as ethylene and propylene; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; An alkyl ester of an unsaturated carboxylic acid and an acrylamide. The average degree of polymerization of the polyvinyl alcohol resin is preferably 100 to 10,000, more preferably 1,500 to 8,000, and still more preferably 2,000 to 5,000.

The dichromatic dye contained in the polarizing film (adsorption orientation) may be iodine or a dichroic organic dye, and conventionally known dyes may be used. The dichroic dye may be used alone, or two or more dichroic dyes may be used in combination.

In the present invention, as the polarizing film, a pricking intensity per unit film thickness of 5.8 gf / [mu] m or more is employed. The pricking intensity per unit film thickness refers to the strength at which the prick jig is vertically pushed against the polarizing film and the polarizing film is split along the stretching axis (absorption axis) thereof. For example, the pricking intensity is measured by a compression tester equipped with a load cell . Examples of the compression tester include a handy compression tester " KES-G5 type " manufactured by KATO TECH CO., LTD. And a small table tester " EZ Test " manufactured by Shimadzu Corporation.

The polarizing film used for the measurement may be one obtained by laminating a protective film to form a polarizing plate, or may be one obtained by removing a protective film from a polarizing plate in which a protective film is laminated with an adhesive or the like. Examples of the method of removing the protective film from the polarizing plate include a method of dissolving the protective film using a solvent if the polarizing film is not damaged or a method of peeling the protective film by immersing in a solution having good affinity with the adhesive, Can be used.

The measurement is carried out by sandwiching a polarizing film between two sample pores having circular holes each having a diameter of 15 mm or less through which the sting jig can pass. It is preferable that the sting jig is a cylindrical rod, and the stinging needle having a spherical or hemispherical tip at its tip in contact with the polarizing film is preferable. The spherical portion or hemispherical portion at the tip end is preferably 0.5 mm or more in diameter and 5 mm or less in diameter. Further, it is preferable that the radius of curvature thereof is larger than 0R and smaller than 0.7R. The stamper speed of the compression tester is preferably 0.05 cm / sec or more and 0.5 cm / sec or less.

The striking strength can be measured by fixing the test piece to a jig and sticking it from the normal direction of the principal surface of the polarizing film to measure the strength when it is split horizontally into the stretching direction (absorption axis direction). The measurement is performed on a test piece of 5 or more polarizing films, and the average value can be obtained as the stamper strength. The puncture strength per unit film thickness can be calculated by dividing the measured puncture strength by the film thickness of the polarizing film used for the measurement. In this method, since the polarizing film is stretched in the transmission axis direction and the breaking strength at the time of splitting in the absorption axis direction can be quantitatively measured, the polarizing film tends to be cracked so far, The strength can be measured.

The penetration strength per unit film thickness can be increased by lowering the draw ratio at the time of producing the polarizing film or by performing the drying treatment at a high temperature of about 50 to 80 캜, more preferably about 50 to 70 캜. If the penetration strength per unit film thickness is less than 5.8 gf / 탆, there is a tendency that a rate of occurrence of a missing crack in the polarizing film at the time of cutting the end face of the polarizing plate tends to be increased.

Since the polarizing plate of the present invention employs a polarizing film having a perforation strength of 5.8 gf / 占 퐉 or more per unit film thickness, the strength of the polarizing film itself is high. Therefore, even if the end face of the polarizing plate is cut, Can be suppressed.

(2) Protective film

A protective film is laminated on at least one surface of the polarizing film. When a protective film (first protective film) is laminated on one side of the polarizing film and another protective film (second protective film) is laminated on the other side, the second protective film is the same as the first protective film Or other resin film may be used. The first protective film and the second protective film may each be a transparent resin film composed of a thermoplastic resin. Examples of the thermoplastic resin include polyolefin-based resins such as a chain-like polyolefin-based resin and a cyclic polyolefin-based resin exemplified by polypropylene-based resins; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; Polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polycarbonate resin; (Meth) acrylic resins; Or a mixture or copolymer thereof, and the like.

The cyclic polyolefin-based resin is generally a resin that is polymerized using a cyclic olefin as a polymerization unit. For example, JP-A-1-240517, JP-A-3-14882, JP-A- -122137, and the like. Specific examples of the cyclic polyolefin-based resin include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of chain olefins such as ethylene and propylene with cyclic olefins (typically, random copolymers ), Graft polymers obtained by modifying these with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Of these, norbornene-based resins using norbornene monomers such as norbornene and polycyclic norbornene-based monomers as the cyclic olefins are preferably used.

Various products are commercially available as the cyclic polyolefin-based resin. Examples of commercially available products of the cyclic polyolefin resin include those sold under the trade names "TOPAS" (registered trademark) and JSR (trade name), which are produced by TOPAS ADVANCED POLYMERS GmbH and sold in Japan by Polyplastics Co., "Zeonoa" (registered trademark) and "Zeonex" (registered trademark) sold by "Aton" (registered trademark), Nippon Zeon Co., ).

Further, a commercially available product of the film-formed cyclic polyolefin-based resin film may be used as a protective film. Examples of commercially available products include "Aton film" (a registered trademark of Aton) sold by JSR Corporation under the trade name of "Allen", "Essen" (registered trademark) sold by Sekisui Chemical Co., , &Quot; SCA40 ", and " ZEONOAFILM " (registered trademark) sold by Nippon Zeon Co.,

The film-formed cyclic polyolefin-based resin film may be stretched in the same manner as uniaxial stretching or biaxial stretching, or may be formed as a retardation film to which an arbitrary retardation value is imparted by forming a liquid crystal layer or the like on the film.

The cellulose ester resin is usually an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, copolymers thereof and those obtained by modifying a part of the hydroxyl groups with other substituents may also be used. Of these, cellulose triacetate (triacetylcellulose: TAC) is particularly preferable. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate include "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", "Fujitac (registered trademark) TD80UZ And TAC films " KC8UX2M ", " KC2UA ", and " KC4UY " manufactured by Konica Minolta Co.,

Similarly, the cellulose ester-based resin film produced may be stretched in the same manner as uniaxial stretching or biaxial stretching, or may be formed as a retardation film having an arbitrary retardation value by forming a liquid crystal layer or the like on the film.

The (meth) acrylic resin is usually a polymer containing methacrylic acid ester as a main component. The methacrylic resin may be a homopolymer of one kind of methacrylic acid ester or a copolymer of methacrylic acid ester and other methacrylic acid ester or acrylic acid ester. Examples of the methacrylic ester include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, and the number of carbon atoms of the alkyl group is usually about 1-4. Further, examples thereof include cyclohexyl methacrylate such as cyclohexyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclohexyl methacrylate and the like, methacrylic acid aryl such as phenyl methacrylate, cyclohexyl methacrylate such as cyclohexylmethacrylate, Methacrylic acid aralkyl such as benzyl acrylate, benzyl methacrylate and the like may be used.

Examples of the other polymerizable monomer that can form the (meth) acrylic resin include polymeric monomers other than acrylic acid ester, methacrylic acid ester and acrylic acid ester. Specific examples of the acrylic acid ester include acrylic acid methyl ester, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2- Ethylhexyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, and other acrylic acid alkyl esters having 1 to 8 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 4. In the (meth) acrylic resin, the acrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.

Examples of the polymerizable monomer other than the methacrylate ester and the acrylate ester include monofunctional monomers having one polymerizable carbon-carbon double bond in the molecule and at least two polymerizable carbon-carbon double bonds in the molecule Although a functional monomer can be mentioned, a monofunctional monomer is preferably used. Specific examples of monofunctional monomers include styrene-based monomers such as styrene,? -Methylstyrene, vinyltoluene, halogenated styrene and hydroxystyrene; Vinyl cyanide such as acrylonitrile and methacrylonitrile; Unsaturated acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic anhydride; Maleimides such as N-methylmaleimide, N-cyclohexylmaleimide and N-phenylmaleimide; Allyl alcohol such as methallyl alcohol and allyl alcohol; Other monomers such as vinyl acetate, vinyl chloride, ethylene, propylene, 4-methyl-1-pentene, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone and N- do.

Specific examples of the polyfunctional monomer include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate and trimethylolpropane triacrylate; Alkenyl esters of unsaturated carboxylic acids such as allyl acrylate, allyl methacrylate, and allyl cinnamate; Polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate and triallyl isocyanurate, and aromatic polyalkenyl compounds such as divinyl benzene. The polymerizable monomers other than the methacrylic acid ester and the acrylic acid ester may be used singly or in combination of two or more.

The preferable monomer composition of the (meth) acrylic resin is 50 to 100% by weight of the methacrylic acid alkyl ester, 0 to 50% by weight of the alkyl acrylate and 0 to 50% by weight of the other polymerizable monomers, By weight, more preferably 50 to 99.9% by weight of an alkyl methacrylate ester, 0.1 to 50% by weight of an alkyl acrylate ester, and 0 to 49.9% by weight of other polymerizable monomers.

The (meth) acrylic resin may have a cyclic structure in the main chain of the polymer in view of increasing the durability of the film. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone ring structure. Specifically, a cyclic imide structure such as a cyclic acid anhydride structure such as anhydroglutaric acid structure and anhydrous succinic acid structure, a glutarimide structure and a succinimide structure, a lactone ring structure such as butyrolactone and valerolactone . The larger the content of the ring structure in the main chain, the higher the glass transition temperature of the (meth) acrylic resin. The cyclic acid anhydride structure or the cyclic imide structure may be introduced by copolymerization of monomers having a cyclic structure such as maleic anhydride or maleimide, a method of introducing a cyclic acid anhydride structure by a dehydration-demethanol condensation reaction after polymerization A method of introducing a cyclic imide structure by reacting an amino compound, and the like. The resin (polymer) having a lactone ring structure can be prepared by preparing a polymer having a hydroxyl group and an ester group in a polymer chain, and then, by heating, the hydroxyl group and the ester group in the obtained polymer are reacted with a catalyst To form a lactone ring structure to form a lactone ring structure.

Examples of the polymer having a hydroxyl group and an ester group in the polymer chain include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) (Meth) acrylate having a hydroxyl group such as n-butyl acrylate, n-butyl acrylate and n-butyl acrylate and t-butyl 2- (hydroxymethyl) acrylate as a part of the monomer. A more specific method for preparing a polymer having a lactone ring structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-254726.

The (meth) acrylic resin can be prepared by radical polymerization of the monomer composition containing the monomer as described above. The monomer composition may contain, if necessary, a solvent or a polymerization initiator.

The first protective film and the second protective film may be a protective film having an optical function such as a brightness enhancement film.

The brightness enhancement film is used for the purpose of improving brightness in a liquid crystal display or the like. Examples of the brightness enhancement film include a reflection type polarized light separation sheet designed to have a plurality of thin film films having different refractive index anisotropies, An orientation film of a cholesteric liquid crystal polymer, and a circularly polarized light separation sheet in which the alignment liquid crystal layer is supported on a film base.

Surface treatment layers (coating layers) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer may be formed on the surface of the first protective film and the second protective film opposite to the polarizing film. For forming the surface treatment layer on the surface of the protective film, known methods can be used.

The first protective film and the second protective film may be the same protective film or may be different protective films. Examples of the case where the protective film is different include a combination in which the kind of the thermoplastic resin constituting the protective film is at least different; At least different combinations of the presence or absence of the optical function of the protective film or its kind; At least different combinations of the presence or absence of the surface treatment layer formed on the surface or the like.

Thickness of the first protective film and the second protective film is preferably thin from the viewpoint of thinning of the polarizing plate, but if it is too thin, the strength is lowered and the workability is poor. Therefore, the thickness of the first protective film and the second protective film is preferably 5 to 90 占 퐉 or less, more preferably 60 占 퐉 or less, further preferably 50 占 퐉 or less.

(3) Adhesive layer

The lamination of the polarizing film and the first protective film and the lamination of the polarizing film and the second protective film are respectively performed through the adhesive layer. Examples of the adhesive for forming the adhesive layer include an active energy ray curable adhesive that can be cured by irradiation with an active energy ray such as ultraviolet rays, visible light, electron beams, X-rays or the like, a solution obtained by dissolving an adhesive component in water, . INDUSTRIAL APPLICABILITY According to the present invention, it is possible to suppress the occurrence of a missing crack in a polarizing film regardless of the type of adhesive. When an active energy ray curable adhesive is used as an adhesive, the elasticity of the active energy ray curable adhesive is often higher than the elasticity of the water-based adhesive. In the end face of the polarizing plate, The effect of the present invention that the occurrence of the cracks in the polarizing film can be suppressed because the peeling easily occurs between the film and the adhesive or between the adhesive and the polarizing film, This is more remarkable when the line-hardening adhesive is used as an adhesive.

When an active energy ray-curable adhesive is employed, the adhesive layer becomes the cured layer. As the adhesive, an active energy ray curable adhesive containing an epoxy compound curable by cationic polymerization as a curable component is more preferable, and an ultraviolet curable adhesive containing an epoxy compound as a curable component is more preferable. The epoxy compound referred to herein means a compound having an average of at least one, preferably two or more epoxy groups in the molecule. The epoxy compound may be used alone, or two or more epoxy compounds may be used in combination.

Examples of the epoxy compound suitably usable include a hydrogenated epoxy compound obtained by reacting epichlorohydrin with an alicyclic polyol obtained by subjecting an aromatic ring to a hydrogenation reaction in an aromatic ring of an aromatic polyol (a glycidyl ester of a polyol having an alicyclic ring Diesters); Aliphatic epoxy compounds such as aliphatic polyhydric alcohols or polyglycidyl ethers of alkylene oxide adducts thereof; And an alicyclic epoxy compound which is an epoxy compound having at least one epoxy group bonded to an alicyclic ring in the molecule.

The active energy ray-curable adhesive may further contain a (meth) acrylic compound that is radically polymerizable as a curable component. Examples of the (meth) acrylic compound include (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule; (Meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth) acryloyloxy groups in the molecule.

When the active energy ray-curable adhesive contains an epoxy compound cured by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. As the cationic polymerization initiator, for example, an aromatic diazonium salt; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-arene complexes and the like. When the active energy ray-curable adhesive contains a radically polymerizable curable component such as a (meth) acrylic compound, it preferably contains a photo radical polymerization initiator. Examples of the photo radical polymerization initiator include an acetophenone-based initiator, a benzophenone-based initiator, a benzoin ether-based initiator, a thioxanthone-based initiator, xanthone, fluorenone, camphorquinone, benzaldehyde and anthraquinone.

The active energy ray curable adhesive may contain a cationic polymerization accelerator such as oxetane and polyol, a photosensitizer, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, , An antistatic agent, a leveling agent, a solvent, and the like.

The thickness of the adhesive layer formed from the active energy ray-curable adhesive is, for example, about 0.01 to 10 mu m, preferably about 0.01 to 5 mu m, and more preferably 2 mu m or less (for example, 1 mu m or less).

As the water-based adhesive, for example, an adhesive composition using a polyvinyl alcohol resin or a urethane resin as a main component is preferable. The thickness of the adhesive layer formed from the water based adhesive is usually 1 占 퐉 or less.

When a polyvinyl alcohol resin is used as the main component of the adhesive, the polyvinyl alcohol resin may be a partially saponified polyvinyl alcohol or a completely saponified polyvinyl alcohol, or may contain a carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, Or modified polyvinyl alcohol resins such as modified polyvinyl alcohol and amino group-modified polyvinyl alcohol. The polyvinyl alcohol resin may be a polyvinyl alcohol copolymer obtained by saponifying a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, as well as a copolymer of vinyl acetate and another monomer copolymerizable therewith It may be.

An aqueous adhesive containing a polyvinyl alcohol resin as an adhesive component is usually an aqueous solution of a polyvinyl alcohol resin. The concentration of the polyvinyl alcohol resin in the adhesive is usually 1 to 10 parts by weight, preferably 5 parts by weight or less, based on 100 parts by weight of water.

In order to improve the adhesiveness, it is preferable to add a curing component such as a polyaldehyde, a melamine compound, a zirconia compound, a zinc compound, a glyoxal and a water-soluble epoxy resin or a crosslinking agent to the adhesive composed of an aqueous solution of a polyvinyl alcohol resin Do. As the water-soluble epoxy resin, for example, epichlorohydrin is reacted with polyamide amine obtained by the reaction of a polyalkylene polyamine such as diethylene triamine and triethylene tetramine with a dicarboxylic acid such as adipic acid The resulting polyamide polyamine epoxy resin can be suitably used. Examples of commercially available products of such polyamidepolyamine epoxy resins include "Sumireze Resin (registered trademark) 650" and "Sumirease Resin (registered trademark) 675" manufactured by DAOKA CHEMICAL INDUSTRIES, LTD. WS-525 ". The addition amount of these curable components or crosslinking agent (the total amount when the curable component and the crosslinking agent are added together) is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight per 100 parts by weight of the polyvinyl alcohol resin . When the addition amount of the curable component or the crosslinking agent is less than 1 part by weight based on 100 parts by weight of the polyvinyl alcohol resin, the effect of improving the adhesiveness tends to be small. When the addition amount of the curable component or the cross- If the amount is more than 100 parts by weight based on 100 parts by weight of the base resin, the adhesive layer tends to be tacky.

When a urethane resin is used as the main component of the adhesive, examples of suitable adhesive compositions include a mixture of a polyester-based ionomer-type urethane resin and a compound having a glycidyloxy group. The polyester-based ionomer-type urethane resin is a urethane resin having a polyester skeleton in which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomeric urethane resin is suitable as an aqueous adhesive since it emulsifies directly in water without using an emulsifier to form an emulsion.

(4) Cutting of the end face

In the polarizing plate of the present invention, the end face is subjected to cutting processing. The cutting method of the end face is not particularly limited as long as it is a method using a cutting tool. According to the polarizing plate of the present invention, it is possible to suppress the occurrence of a missing crack in the polarizing film that occurs when the end face is cut using a cutting tool. Polishing marks are formed on the edge of the polarizing plate by the cutting process of the end face. Although the polishing marks differ depending on the cutting method and conditions, for example, when the end face of the polarizer is observed, cutting scratches may occur at an angle of 15 DEG or more and 90 DEG or less with respect to the thickness direction of the polarizer.

[Polarizing plate production method]

The polarizing plate can be produced, for example, by the following method.

(a) a polyvinyl alcohol-based resin film having a polarizing property as a polarizing film (hereinafter, also referred to as a " polarizing film ") may be formed as a single-layer film from a polyvinyl alcohol-based resin film, And then the end face is cut.

[b] A coating solution containing a polyvinyl alcohol-based resin is coated on at least one side of the base film to form a polyvinyl alcohol-based resin layer, and the resulting laminated film is subjected to a predetermined treatment to form a polyvinyl alcohol- A polarizing film, a protective film is bonded to the obtained polarizing laminated film, the base film is peeled, and then the end face is cut.

In this method, after the base film is peeled, a protective film may be bonded to the other side. In this case, the cutting of the end face is performed after the protective film is bonded to the other face.

(Production method [a])

In the production method [a], a polarizing film can be produced from a polyvinyl alcohol-based resin film obtained by film-forming the above-mentioned polyvinyl alcohol-based resin as a starting raw material. As a method of producing a film of a polyvinyl alcohol-based resin, a known method such as melt extrusion method, solvent casting method and the like can be adopted. The thickness of the polyvinyl alcohol-based resin film before stretching is, for example, about 10 to 150 mu m.

Production method [a] includes, for example, a step of uniaxially stretching a polyvinyl alcohol resin film; A step of staining a polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye; A step of treating a polyvinyl alcohol resin film adsorbed with a dichroic dye with an aqueous solution of boric acid; And a step of washing with water after treatment with an aqueous boric acid solution.

The uniaxial stretching of the polyvinyl alcohol resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. In the case where uniaxial stretching is carried out after dyeing, this uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed in these plural stages.

The uniaxial stretching may be performed between rolls having different circumferential speeds, or may be carried out using heated rolls. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state in which a polyvinyl alcohol resin film is swollen with a solvent. The draw ratio is usually about 4 to 17 times, preferably about 4.5 times or more, and more preferably about 8 times or less.

As a method for dyeing a polyvinyl alcohol resin film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol resin film in an aqueous solution (dyeing solution) containing a dichroic dye is employed. It is preferable that the polyvinyl alcohol resin film is subjected to an immersion treatment (swelling treatment) with respect to water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally employed. The content of iodine in the dyeing aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the dyeing aqueous solution is usually about 20 to 40 캜. The immersion time (dyeing time) for the dyeing aqueous solution is usually about 20 to 1800 seconds.

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

The boric acid treatment after dyeing with the dichroic dye can be performed by immersing the dyed polyvinyl alcohol resin film in an aqueous solution of boric acid.

The amount of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution of boric acid contains potassium iodide. The amount of potassium iodide in the boric acid aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. To the aqueous solution of boric acid, sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid or the like may be added as a pH adjusting agent. The immersion time for the boric acid aqueous solution is usually about 60 to 1200 seconds, preferably about 150 to 600 seconds, more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 占 폚 or higher, preferably 50 to 85 占 폚, and more preferably 60 to 80 占 폚.

The polyvinyl alcohol resin film after boric acid treatment is usually subjected to water washing treatment. The water washing treatment can be carried out, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The water temperature in the water washing treatment is usually about 5 to 40 캜. The immersion time is usually about 1 to 120 seconds.

After washing with water, drying treatment is carried out to obtain a polarizing film. The drying treatment can be performed using a hot-air dryer or a far-infrared heater. The temperature of the drying treatment is usually about 30 to 100 占 폚, preferably 50 to 80 占 폚. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

By the drying treatment, the water content of the polarizing film is reduced to a practically acceptable level. The water content thereof is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. If the moisture content exceeds 20% by weight, the thermal stability of the polarizing film may be poor.

In the production method [a], by lowering the draw ratio in the stretching step, the sticking strength per unit film thickness of the polarizing film can be improved.

The first protective film is bonded to at least one surface of the polarizing film using an adhesive, and the polarizing plate can be manufactured by curing the adhesive. If necessary, the second protective film may be bonded to the other surface of the polarizing film.

A method for bonding a first protective film and a second protective film to a polarizing film using an active energy ray-curable adhesive or an aqueous adhesive, comprising the steps of: applying an adhesive to one or both of bonding surfaces of two films to be bonded, And then the two films are overlapped with each other. The coating of the adhesive can be carried out by, for example, a softening method, a Meyer bar coating method, a gravure coating method, a comma coater method, a doctor blade method, a die coating method, a dip coating method or a spraying method. The flexible method is a method in which a film to be joined is moved in a substantially vertical direction, in a substantially horizontal direction, or in an inclined direction between them, and an adhesive is applied to the surface of the film so as to perform diffusion application. The film laminate formed by superimposing through the adhesive layer is usually pressed from above and below through a nip roll (bonding roll) or the like.

In joining the protective film to the polarizing film, the joining surfaces of the protective film and / or the polarizing film can be easily subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment and saponification treatment It is preferable to carry out the plasma treatment, the corona treatment or the saponification treatment. For example, when the protective film is composed of a ring-shaped polyolefin-based resin, a plasma treatment or a corona treatment is usually performed on the bonding surface of the protective film. When the protective film is made of a cellulose ester resin, the bonding surface of the protective film is usually saponified. As the saponification treatment, a method of immersing in an aqueous alkaline solution such as sodium hydroxide or potassium hydroxide may be mentioned.

When an aqueous adhesive is used, it is preferable to carry out a drying step of drying the film laminate to remove water contained in the adhesive layer made of an aqueous adhesive after bonding the above-mentioned film. The drying can be performed, for example, by introducing the film laminate into a drying furnace. The drying temperature (temperature of the drying furnace) is preferably 30 to 90 占 폚. If it is less than 30 DEG C, the protective film tends to be easily peeled from the polarizing film. If the drying temperature exceeds 90 ° C, there is a fear that the polarization performance of the polarizing film is deteriorated by heat. The drying time can be about 10 to 1000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, more preferably 150 to 600 seconds.

After the drying step, the polarizing plate may be cured at room temperature or slightly higher temperature, for example, at a temperature of about 20 to 45 DEG C for about 12 to 600 hours. The curing temperature is generally set to be lower than the drying temperature.

In the case of using an active energy ray-curable adhesive, the above-mentioned film is bonded, and then a curing step of curing the adhesive layer comprising the active energy ray curable adhesive is performed. The curing of the adhesive layer can be performed by irradiating the film laminate with an active energy ray. The active energy ray is usually irradiated from the first protective film side. The active energy ray is preferably ultraviolet ray.

A light source of an active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, a low energy mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, A wave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The active energy ray irradiation intensity for the adhesive layer made of the active energy ray-curable adhesive is appropriately determined according to the composition of the adhesive, but is set so that the irradiation intensity in the wavelength range effective for activation of the polymerization initiator is 0.1 to 6000 mW / cm ² . When the irradiation intensity is not less than 0.1 mW / cm ² , the reaction time is not excessively long. When the irradiation intensity is not more than 6000 mW / cm ² , the heat and active energy radiated from the light source. It is less likely to cause deterioration of the polarizing film.

The irradiation time of the active energy ray is preferably determined in accordance with the composition of the adhesive but is preferably set so that the integrated amount of light expressed as the product of the irradiation intensity and irradiation time is 10 to 10000 mJ / cm ² . When the accumulated light quantity is 10 mJ / cm ² or more, a sufficient amount of active species originating from the polymerization initiator can be sufficiently generated to allow the curing reaction to proceed more surely. When the total light quantity is 10,000 mJ / cm ² or less, irradiation time is not excessively long, Lt; / RTI >

The irradiation of the active energy ray is preferably carried out under the condition that the functions of the polarizing plate such as the degree of polarization, transmittance and hue of the polarizing film, and transparency of the protective film are not deteriorated.

In laminating the first protective film and the second protective film with respect to the polarizing film, either one of the protective films may be laminated on the polarizing film, and then the other protective film may be laminated, or the laminated protective film may be laminated substantially simultaneously with the polarizing film .

The end face of the polarizing plate with a one side protective film or the polarizing plate with a two side protective film manufactured as described above is cut. By the cutting process, the dimensional precision can be increased, and the pressure-sensitive adhesive released from the gap between the polarizing film and the separator (peeling film), which is usually laminated on the polarizing plate, can be cut off by pressing at the time of cutting. The method of cutting is not particularly limited as long as it is a method using a cutting tool, and a specific example will be described later.

(Production method [b])

In the production method [b], a polyvinyl alcohol-based resin layer that becomes a polarizing film can be formed by coating a base film with a polyvinyl alcohol-based resin. For example, a resin layer forming step, a stretching step, a dyeing step, The polarizing plate can be manufactured through a process, a peeling process, and a cutting process of an end face.

When the second protective film is laminated on the other surface of the polarizing film, a second bonding step of bonding the second protective film to the other surface of the polarizing film may be performed after the peeling step. When the protective film is laminated on both surfaces, the second protective film may be laminated in the first bonding step and the first protective film may be laminated in the second bonding step. In the case of carrying out the second joining step, the step of cutting the end face is performed after the second joining step.

(Resin layer forming step)

This step is a step of coating a coating solution containing a polyvinyl alcohol resin on at least one side of a base film and then drying to form a polyvinyl alcohol resin layer to obtain a laminated film. This polyvinyl alcohol-based resin layer is a layer which becomes a polarizing film through a stretching process and a dyeing process. The polyvinyl alcohol-based resin layer can be formed by coating a coating liquid containing a polyvinyl alcohol-based resin on one or both surfaces of a base film and drying the coating layer. The method of forming the polyvinyl alcohol-based resin layer by such coating is advantageous in that it is easy to obtain a polarizing film of a thin film.

The base film may be composed of a thermoplastic resin and is preferably composed of a thermoplastic resin excellent in transparency, mechanical strength, heat stability, stretchability, and the like. Specific examples of such a thermoplastic resin include polyolefin-based resins such as a chain-like polyolefin-based resin and a cyclic polyolefin-based resin; Polyester-based resin; (Meth) acrylic resins; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; Polycarbonate resin; Polyvinyl alcohol-based resin; Polyvinyl acetate resin; Polyarylate resins; Polystyrene type resin; Polyether sulfone type resin; Polysulfone resins; Polyamide based resin; Polyimide resin; And mixtures and copolymers thereof.

The base film may be a single layer structure composed of one resin layer made of one kind of thermoplastic resin or two or more kinds of thermoplastic resins, or a multilayer structure in which a plurality of resin layers made of one kind or two or more kinds of thermoplastic resins are laminated.

Examples of the chain-like polyolefin-based resin include a homopolymer of a chain-like olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more kinds of chain-like olefins. A base film made of a chain-like polyolefin-based resin is preferable because it is easy to stably stretch at a high magnification. Among them, the base film is preferably made of a polypropylene resin (a polypropylene resin which is a homopolymer of propylene or a copolymer mainly composed of propylene), a polyethylene resin (a polyethylene resin which is a homopolymer of ethylene or a copolymer mainly comprising ethylene ) Is more preferable.

One of the examples suitably used as the thermoplastic resin constituting the base film is a copolymer mainly composed of propylene, which is a copolymer of propylene and other monomers copolymerizable therewith. Other monomers copolymerizable with propylene include, for example, ethylene and? -Olefin. As the? -olefin, an? -olefin having 4 or more carbon atoms is preferably used, and more preferably an? -olefin having 4 to 10 carbon atoms. Examples of the? -Olefin having 4 to 10 carbon atoms include straight chain monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene; Branched monoolefins such as 3-methyl-1-butene, 3-methyl-1-pentene and 4-methyl-1-pentene; Vinylcyclohexane and the like. The copolymer of propylene and other monomer copolymerizable therewith may be a random copolymer or a block copolymer.

The content of other monomers is, for example, 0.1 to 20% by weight, preferably 0.5 to 10% by weight, in the copolymer. The content of the other monomers in the copolymer can be determined by performing infrared (IR) spectrum measurement according to the method described on page 616 of "Polymer Analysis Handbook" (published by Kinokuniya Bookstore, 1995).

Of these, propylene homopolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer or propylene-ethylene-1-butene random copolymer are preferably used as the polypropylene type resin.

The stereoregularity of the polypropylene resin is preferably substantially isotactic or syndiotactic. A base film made of a polypropylene resin having substantially stereospecificity of isotacticity or syndiotacticity is relatively easy to handle and has excellent mechanical strength under a high temperature environment.

The polyester-based resin is a resin having an ester bond, and is generally composed of a polycondensation product of a polycarboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or its derivative, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethylterephthalate, dimethyl naphthalenedicarboxylate and the like. As the polyhydric alcohol, a dihydric diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

As a representative example of the polyester-based resin, polyethylene terephthalate which is a polycondensation product of terephthalic acid and ethylene glycol can be mentioned. Polyethylene terephthalate is a crystalline resin, but it is easy to carry out a treatment such as stretching in a state before crystallization treatment. If necessary, it may be subjected to crystallization treatment at the time of drawing or after heat treatment after stretching. Further, copolymerized polyesters having a lowered crystallinity (or made amorphous) by copolymerizing different types of monomers with the skeleton of polyethylene terephthalate are also suitably used. Examples of such resins include copolymers obtained by copolymerizing cyclohexane dimethanol or isophthalic acid. These resins are also excellent in stretchability and therefore can be suitably used.

Specific examples of the polyester resin other than the polyethylene terephthalate and the copolymer thereof include polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, Hexanedimethyl terephthalate, polycyclohexanedimethanol naphthalate, and mixtures and copolymers thereof.

The (meth) acrylic resin is a resin mainly composed of a compound having a (meth) acryloyl group. Examples of the (meth) acrylic resin include poly (meth) acrylic acid esters such as polymethyl methacrylate; Methyl methacrylate- (meth) acrylic acid copolymer; Methyl methacrylate- (meth) acrylic acid ester copolymer; Methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer; (Meth) acrylate-styrene copolymer (MS resin and the like); A copolymer of a compound having an alicyclic hydrocarbon group and methyl methacrylate (e.g., methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) have. As the (meth) acrylic resin, a polymer containing as a main component a poly (meth) acrylic acid alkyl ester having 1 to 6 carbon atoms in the alkyl group is preferable, and methyl methacrylate as a main component (50 to 100 wt% 100% by weight) is more preferable.

The polycarbonate resin is an engineering plastic composed of a polymer having a monomer unit bonded thereto through a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy and transparency. The polycarbonate resin may be a resin called a modified polycarbonate such as a polymer skeleton modified to lower the photoelastic coefficient or a copolymerized polycarbonate improved in wavelength dependency. Suitable commercially available products can be used for the polycarbonate resin. Examples of commercially available products include all of trade names such as "Panlite (registered trademark)" manufactured by Dainippon Ink & Chemicals, Inc., "Yuplon (registered trademark)" manufactured by Mitsubishi Engineering Plastics, Sumikastar Theory Polycarbonate ), &Quot; SD Polycar (registered trademark) " by Dow Chemical Company, and " Caliba (registered trademark) "

Among them, a polypropylene resin is preferably used from the viewpoint of stretchability and heat resistance.

As to the cyclic polyolefin-based resin and the cellulose ester-based resin used as the base film, the description about the protective film is cited. The chain polyolefin resin, polyester resin, (meth) acrylic resin and polycarbonate resin described above in relation to the base film can also be used as a constituent material of the protective film.

In addition to the thermoplastic resin, any appropriate additives may be added to the base film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a colorant.

The thickness of the base film can be appropriately determined, but is generally from 1 to 500 mu m, more preferably 300 mu m or less, further preferably 200 mu m or less, from the viewpoint of workability such as strength and handling property, 150 [mu] m is most preferable.

The tensile modulus of the base film is preferably from 100 MPa to 1500 MPa at 80 캜, more preferably from 140 MPa to 1000 MPa, further preferably from 150 MPa to 500 MPa. If the tensile modulus is too small, defects such as wrinkles tend to occur due to insufficient hardness of the base film at the time of stretching, and if it is excessively high, the workability in stretching becomes poor.

The coating liquid containing the polyvinyl alcohol resin to be coated on the base film is preferably a polyvinyl alcohol resin solution obtained by dissolving a polyvinyl alcohol resin powder in a good solvent (e.g., water). The coating liquid may contain an additive such as a plasticizer and a surfactant if necessary. As the plasticizer, a polyol or a condensate thereof can be used. Examples of the plasticizer include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The blending amount of the additive is preferably 20% by weight or less of the polyvinyl alcohol resin.

The method of applying the coating liquid on the base film may be a wire bar coating method; A roll coating method such as reverse coating and gravure coating; Die coating method; Comma coat method; Lip coating method; Spin coating method; Screen coating method; Fountain coating method; Dipping method; Spray method, and the like. When the coating solution is coated on both surfaces of the base film, the coating solution may be sequentially applied one by one using the above-described method, or may be coated on both surfaces of the base film simultaneously using a dipping method, a spray coating method, or other special apparatus .

The drying temperature and the drying time of the coating layer (the polyvinyl alcohol-based resin layer before drying) are set according to the type of the solvent contained in the coating liquid. The drying temperature is, for example, 50 to 200 占 폚, preferably 60 to 150 占 폚. When the solvent includes water, the drying temperature is preferably 80 DEG C or higher. The drying time is, for example, 2 to 20 minutes.

The polyvinyl alcohol-based resin layer may be formed on only one side of the base film or on both sides. It is possible to suppress the curling of the film that may occur during the production of the polarizing laminated film and to obtain two polarizing plates from one polarizing laminated film, Do.

The thickness of the polyvinyl alcohol-based resin layer in the laminated film is preferably 3 to 60 占 퐉, more preferably 3 to 30 占 퐉, and still more preferably 5 to 20 占 퐉. Within this range, it is possible to obtain a polarizing film having a satisfactory dyeability of the dichroic dye, excellent polarizing performance and a sufficiently small thickness. If the thickness of the polyvinyl alcohol-based resin layer exceeds 60 탆, the thickness of the polarizing film may exceed 20 탆, and if the thickness of the polyvinyl alcohol-based resin layer is less than 3 탆, It tends to get worse.

Prior to the coating of the coating liquid, in order to improve the adhesion between the base film and the polyvinyl alcohol-based resin layer, at least the surface of the base film on which the polyvinyl alcohol-based resin layer is formed is subjected to a corona treatment, a plasma treatment, ) Processing may be performed.

Further, in order to improve the adhesion between the base film and the polyvinyl alcohol-based resin layer prior to coating of the coating solution, a polyvinyl alcohol-based resin layer may be formed on the base film through a primer layer or an adhesive layer.

The primer layer can be formed by coating a coating solution for forming a primer layer on the surface of a base film, followed by drying. The coating solution for forming a primer layer preferably contains a component exhibiting a strong adhesion to some extent to both the base film and the polyvinyl alcohol-based resin layer. The coating solution for forming a primer layer usually contains such a resin component and a solvent. As the resin component, a thermoplastic resin having excellent transparency, thermal stability, stretchability and the like is used, and examples thereof include (meth) acrylic resin, polyvinyl alcohol resin and the like. Among them, a polyvinyl alcohol-based resin which gives good adhesion is preferably used.

Examples of the polyvinyl alcohol-based resin include a polyvinyl alcohol resin and derivatives thereof. As the derivatives of the polyvinyl alcohol resin, polyvinyl formal, polyvinyl acetal, etc., polyvinyl alcohol resins modified with olefins such as ethylene and propylene; Modified with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid and crotonic acid; An alkyl ester of an unsaturated carboxylic acid; Acrylamide, and the like. Of the above-mentioned polyvinyl alcohol resins, polyvinyl alcohol resins are preferably used.

As the solvent, a general organic solvent or an aqueous solvent capable of dissolving the resin component is usually used. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene and xylene; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Esters such as ethyl acetate and isobutyl acetate; Chlorinated hydrocarbons such as methylene chloride, trichlorethylene and chloroform; Ethanol, 1-propanol, 2-propanol and 1-butanol. However, when a primer layer is formed using a coating solution for forming a primer layer containing an organic solvent, the base film may be dissolved, so it is preferable to select a solvent in consideration of the solubility of the base film. Considering the environmental impact, it is preferable to form the primer layer from the coating solution containing water as a solvent.

To the coating solution for forming a primer layer, a crosslinking agent may be added to increase the strength of the primer layer. The crosslinking agent is appropriately selected from among well-known ones such as an organic type and an inorganic type, depending on the type of the thermoplastic resin to be used. Examples of the crosslinking agent include epoxy-based, isocyanate-based, dialdehyde-based, and metal-based crosslinking agents.

As the epoxy crosslinking agent, any one of a one-liquid curing type and a two-liquid curing type may be used, and ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or tri-glycidyl ether, -Hexanediol diglycidyl ether, trimethylol propane triglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane) triisocyanate, isophorone diisocyanate, Keto oxime block water or phenol block water.

Examples of dialdehyde crosslinking agents include glyoxal, malondialdehyde, succindialdehyde, glutaraldaldehyde, maleindialdehyde, phthalaldehyde and the like.

Examples of the metal-based crosslinking agent include metal salts, metal oxides, metal hydroxides, and organometallic compounds. Examples of the metal salt, metal oxide and metal hydroxide include salts of metals having a valence of 2 or more such as magnesium, calcium, aluminum, iron, nickel, zirconium, titanium, silicon, boron, zinc, copper, vanadium, chromium, , Oxides and hydroxides.

The organometallic compound is a compound having at least one structure in which the organic group is directly bonded to the metal atom or the organic group is bonded through the oxygen atom or the nitrogen atom. The organic group means a monovalent or multivalent group containing at least a carbon element, and may be, for example, an alkyl group, an alkoxy group, an acyl group, or the like. The term " bond " means not only a covalent bond but also a coordinate bond by coordination with a chelate-type compound.

Suitable examples of the organometallic compound include an organic titanium compound, an organic zirconium compound, an organoaluminum compound, and an organosilicon compound. The organometallic compound may be used alone, or two or more of them may be used in combination.

Examples of the organic titanium compound include titanium ortho esters such as tetra n-butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate and tetramethyl titanate; Titanium chelates such as titanium acetylacetonate, titanium tetraacetylacetonate, polytitanacetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolamine and titanium ethylacetoacetate; And titanium acylate such as polyhydroxy titanium stearate.

Examples of the organic zirconium compounds include zirconium n-propionate, zirconium n-butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium acetylacetonate bis ethylacetoacetate and the like .

Examples of the organoaluminum compounds include aluminum acetylacetonate and aluminum organic acid chelate. Examples of the organosilicon compound include compounds in which the ligands exemplified in the organic titanium compound and organic zirconium compound are bonded to silicon.

In addition to the above crosslinking agent (low molecular weight crosslinking agent), a high molecular weight crosslinking agent such as methylol melamine resin and polyamide epoxy resin may also be used. Examples of commercially available products of polyamide epoxy resins include "Sumireze Resin (registered trademark) 650 (30)" and "Sumireze Resin (registered trademark) 675", each of which is sold under the trade name of Daoka Chemical Industry Co., .

When a primer layer is formed from a polyvinyl alcohol resin, a polyamide epoxy resin, a methylol melamine resin, a dialdehyde crosslinking agent, a metal chelate compound crosslinking agent and the like are suitably used as a crosslinking agent.

The ratio of the resin component and the crosslinking agent in the coating solution for forming a primer layer may be appropriately determined according to the kind of the resin component, the kind of the crosslinking agent and the like, in the range of about 0.1 to 100 parts by weight of the crosslinking agent relative to 100 parts by weight of the resin component, It is preferably selected in the range of about 0.1 to 50 parts by weight. The coating solution for forming a primer layer preferably has a solid concentration of about 1 to 25% by weight.

The thickness of the primer layer is preferably about 0.05 to 1 mu m, more preferably 0.1 to 0.4 mu m. If the thickness is smaller than 0.05 占 퐉, the effect of improving the adhesion between the base film and the polyvinyl alcohol-based resin layer is small, and if it is thicker than 1 占 퐉, it is disadvantageous for making the polarizing plate thinner.

The method of coating the primer layer-forming coating solution onto the base film may be the same as the coating solution for forming the polyvinyl alcohol-based resin layer. The primer layer is coated on the surface (one side or both sides of the base film) on which the coating solution for forming the polyvinyl alcohol-based resin layer is coated. The drying temperature and the drying time of the coating layer composed of the coating solution for forming the primer layer are set in accordance with the type of the solvent contained in the coating solution. The drying temperature is, for example, 50 to 200 占 폚, preferably 60 to 150 占 폚. When the solvent includes water, the drying temperature is preferably 80 DEG C or higher. The drying time is, for example, 30 seconds to 20 minutes.

When a primer layer is formed, the order of coating on the base film is not particularly limited. For example, in the case of forming a polyvinyl alcohol resin layer on both sides of a base film, a primer layer is formed on both sides of the base film, A primer layer and a polyvinyl alcohol resin layer are sequentially formed on one side of a base film, and then a primer layer, a polyvinyl alcohol resin layer May be formed in this order.

(Drawing step)

This step is a step of obtaining a stretched film comprising a stretched base material film and a polyvinyl alcohol-based resin layer by subjecting a laminated film comprising a base film and a polyvinyl alcohol-based resin layer to stretching treatment. The stretching magnification of the laminated film can be appropriately selected in accordance with the desired polarization characteristics, but is preferably not less than 4 times and not more than 17 times, more preferably not less than 4.5 times and not more than 8 times the original length of the laminated film. If the stretching magnification is 4 times or less, the polyvinyl alcohol-based resin layer is not sufficiently oriented, so that the degree of polarization of the polarizing film may not be sufficiently increased. On the other hand, when the draw ratio exceeds 17 times, it becomes difficult to obtain a high sticking strength. Further, the film tends to be broken at the time of stretching, and the thickness of the stretched film becomes thinner than necessary, which may lower the workability and handling property in the subsequent step. The stretching treatment is usually uniaxial stretching.

The stretching treatment is not limited to stretching in one stage but may be performed in multiple stages. In this case, all of the multistage stretching process may be performed continuously before the staining process, and the second and subsequent stretching processes may be performed simultaneously with the staining process and / or the crosslinking process in the staining process. In this case, it is predicted that the film is stretched in the dyeing step described later, and the stretching magnification in the stretching step can be made more than 1 time and 3.5 times or less. In the case where the stretching treatment is performed in such a multi-stage, it is preferable that the stretching treatment is performed so that the front ends of the stretching treatment are combined so that the stretching ratio exceeds 4.5 times.

The stretching treatment may be longitudinal stretching in which stretching is performed in the longitudinal direction of the film (film transport direction), transverse stretching or oblique stretching in stretching in the film width direction, or the like. Examples of the longitudinal stretching method include inter-roll stretching, stretching using a roll, stretching using a chuck (clip), and the transverse stretching method includes a tenter method and the like. Any of the wet drawing method and the dry drawing method can be employed for the drawing treatment, but a dry drawing method is preferable because a drawing temperature can be selected in a wide range.

The stretching temperature is set to be equal to or higher than a temperature at which the entirety of the polyvinyl alcohol resin layer and the base film can be stretched to exhibit fluidity and is preferably set to a temperature of -30 ° C to + 30 ° C (melting point or glass transition temperature) More preferably in the range of -30 ° C to + 5 ° C, and more preferably in the range of -25 ° C to + 0 ° C. When the base film is composed of a plurality of resin layers, the phase transition temperature means the highest phase transition temperature among the phase transition temperatures indicated by the plurality of resin layers.

When the stretching temperature is lower than -30 占 폚 of the phase transition temperature, high-magnification stretching exceeding 4.5 times is not easily attained, or the fluidity of the base film is too low to make the stretching process difficult. If the stretching temperature exceeds + 30 ° C of the phase transition temperature, the fluidity of the base film becomes too large and the stretching tends to become difficult. The stretching temperature is within the above range, more preferably 120 deg. C or more, from the viewpoint of easy high-rate stretching exceeding 4.5 times. When the stretching temperature is 120 ° C or more, even if stretching at a high magnification ratio exceeding 4.5 times, there is no difficulty in stretching treatment.

The stretching treatment may be performed while heating the laminated film. Examples of the heating method include a zone heating method (for example, heating in a drawing zone such as a heating furnace heated to a predetermined temperature by blowing hot air); A method of heating the roll itself when the roll is stretched; A heater heating method (a method in which an infrared heater, a halogen heater, a panel heater, and the like are disposed above and below a laminated film and heated by radiant heat). In the roll-to-roll stretching method, the zone heating method is preferable from the viewpoint of the uniformity of the stretching temperature. In this case, the two nip roll pairs may be provided in a stretched drawing zone or outside the stretching zone, but it is preferable that the two nip rolls are provided outside the stretching zone to prevent adhesion between the laminated film and the nip roll.

The stretching temperature means the atmospheric temperature in the zone (for example, in the heating furnace) in the case of the zone heating method, and the heating temperature means the atmospheric temperature in the furnace when heating is performed in the furnace. In the case of heating the roll itself, it means the surface temperature of the roll.

Prior to the stretching step, a preheating treatment step for preheating the laminated film may be formed. As the preheating method, the same method as the heating method in the stretching treatment can be used. In the case where the stretching treatment method is inter-roll stretching, the preheating may be performed at any timing before passing through the nip roll on the upstream side, during passing, or after passing. When the stretching treatment method is thermal roll stretching, preheating is preferably performed at a timing before passing through the thermal roll. In the case of stretching using the chucking method, the preheating is preferably performed at a timing before widening the distance between the chucks. The preheating temperature is preferably in the range of -50 占 폚 to 占 0 占 폚 of the stretching temperature, and more preferably in the range of -40 占 폚 to -10 占 폚 of the stretching temperature.

Further, a heat fixation treatment step may be formed after the stretching treatment in the stretching step. The heat fixation treatment is a process of performing heat treatment at a crystallization temperature or higher while maintaining the end portion of the stretched film in a state of being held in a state of being held by a clip. By this heat setting treatment, the crystallization of the polyvinyl alcohol-based resin layer is promoted. The heat-setting treatment temperature is preferably in the range of -0 to -80 占 폚 of the stretching temperature, and more preferably in the range of -0 to -50 占 폚 of the stretching temperature.

(Dyeing process)

This step is a step of obtaining a polarizing laminated film by dyeing a polyvinyl alcohol-based resin layer of a stretched film with a dichroic dye and forming the polarizing film by adsorption alignment. A polarizing laminated film obtained by laminating a polarizing film on one side or both sides of a base film through this step is obtained. The dyeing step can be carried out by immersing the entire drawn film in a solution (dyeing solution) containing a dichroic dye. As the dyeing solution, a solution obtained by dissolving the dichroic dye in a solvent can be used. As the solvent of the dyeing solution, generally water is used, but an organic solvent compatible with water may be further added. The concentration of the dichroic dye in the dyeing solution is preferably 0.01 to 10 wt%, more preferably 0.02 to 7 wt%, and still more preferably 0.025 to 5 wt%.

In the case of using iodine as the dichroic dye, it is preferable to further add iodide to the dyeing solution containing iodine since the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. The concentration of iodide in the dyeing solution is preferably 0.01 to 20% by weight. Among iodides, it is preferable to add potassium iodide. When potassium iodide is added, the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably in the range of 1: 6 to 1:80, more preferably 1: More preferably in the range of 7 to 1:70.

The immersion time of the stretched film to the dyeing solution is usually in the range of 15 seconds to 15 minutes, preferably 30 seconds to 3 minutes. The temperature of the dyeing solution is preferably in the range of 10 to 60 占 폚, and more preferably in the range of 20 to 40 占 폚.

Further, the stretched film may be subjected to further stretching treatment during the dyeing step. Examples of the embodiment in this case include: 1) a mode in which, in the drawing step, the drawing process is performed at a lower magnification than the target, and then the drawing process is performed so that the total drawing magnification becomes the target magnification during the dyeing process in the dyeing process (2) In the case where the crosslinking treatment is carried out after the dyeing treatment, as described later, (2) the stretching process is performed at a lower magnification than the target in the stretching process, And then the stretching treatment is carried out during the crosslinking treatment so that the final total draw ratio becomes the target magnification.

The dyeing step may include a cross-linking treatment step which is carried out subsequent to the dyeing treatment. The crosslinking treatment can be carried out by immersing the dyed film in a solution (crosslinking solution) containing a crosslinking agent. As the crosslinking agent, conventionally known materials can be used, and examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. The crosslinking agent may be used alone or in combination of two or more.

Specifically, the crosslinking solution may be a solution in which a crosslinking agent is dissolved in a solvent. As the solvent, for example, water may be used, but it may further include an organic solvent compatible with water. The concentration of the crosslinking agent in the crosslinking solution is preferably in the range of 1 to 20 wt%, and more preferably in the range of 6 to 15 wt%.

The crosslinking solution may comprise iodide. By adding iodide, the polarization performance in the plane of the polarizing film can be made more uniform. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. The concentration of iodide in the crosslinking solution is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight.

Further, the crosslinking solution may contain other components such as a pH adjusting agent. As the pH adjusting agent, sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid, and the like may be added.

The immersing time of the dyed film to the crosslinking solution is usually 15 seconds to 20 minutes, preferably 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably in the range of 10 to 90 占 폚.

The crosslinking treatment may be carried out simultaneously with the dyeing treatment by blending the crosslinking agent into the dyeing solution. Further, the stretching treatment may be performed during the crosslinking treatment. The specific embodiment in which the stretching treatment is carried out during the crosslinking treatment is as described above.

After the dyeing step, it is preferable to carry out a cleaning step and a drying step before the first bonding step to be described later. The cleaning process usually includes a water cleaning process. The water washing treatment can be performed by immersing the film after the dyeing treatment or after the crosslinking treatment in purified water such as ion-exchanged water and distilled water. The water washing temperature is usually in the range of 3 to 50 캜, preferably 4 to 20 캜. The immersion time is usually from 2 to 300 seconds, preferably from 3 to 240 seconds.

The cleaning step may be a combination of a water cleaning step and a cleaning step with an iodide solution. In addition to water, a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, and propanol may suitably be contained in the washing liquid used in the water washing step and / or the washing treatment with the iodide solution. The iodide is potassium iodide, and the concentration of potassium iodide in the iodide solution is usually 0.5 to 10 wt%.

As the drying step performed after the cleaning step, any suitable method such as natural drying, air blow drying, and heat drying can be employed. For example, in the case of heat drying, the drying temperature is usually 20 to 95 캜, and the drying time is usually about 1 to 15 minutes.

(First bonding step)

This step is a step of bonding a first protective film to a polarizing film of a polarizing laminated film, that is, a surface of the polarizing film opposite to the base film side to obtain a bonded film. When the polarizing laminated film has a polarizing film on both sides of the base film, the protective film is usually bonded onto the polarizing film on both sides. In this case, these protective films may be the same kind of protective film or different kinds of protective films.

(Peeling process)

This step is a step of obtaining a polarizing plate with a one side protective film by peeling off a base film from a bonding film obtained by bonding the first protective film. Through this process, a polarizing plate with a one-sided protective film on which a first protective film is laminated on one side of the polarizing film is obtained. When the polarizing laminated film has polarizing films on both sides of the base film and a protective film is bonded to both of the polarizing films, two polarizing laminated films from the one polarizing laminated film are peeled .

The method of peeling off the base film can be peeled off in the same manner as the peeling process of a separator (peeling film) which is performed in a usual polarizing plate with a pressure-sensitive adhesive. The base film may be peeled off immediately after the first bonding step, or may be peeled off once in a roll form after the first bonding step and then unwound in a subsequent step.

(Second bonding step)

This step is a step of bonding the other protective film on the polarizing film of the polarizing plate with one-side protective film, that is, the side opposite to the protective film bonded in the first joining step, with an adhesive to obtain a polarizing plate. In the case of carrying out the second bonding step, the second protective film may be bonded in the first bonding step, and in this case, the first protective film is bonded in this step.

(Cutting process)

The end face of the polarizing plate with a one side protective film or the polarizing plate with a two side protective film manufactured as described above is cut. By the cutting process, the dimensional precision can be increased, and the pressure-sensitive adhesive released from the gap between the polarizing film and the separator (peeling film), which is usually laminated on the polarizing plate, can be cut off by pressing at the time of cutting. The method of cutting is not particularly limited as long as it is a method using a cutting tool, and a specific example will be described later.

In the production method [b], by lowering the draw ratio in the stretching step in general, the perforation strength per unit film thickness of the polarizing film can be improved.

[Cutting method of end face]

Hereinafter, a method of cutting the end face of the polarizing plate of the present invention will be described in detail, but the method of cutting is not limited to these methods as long as it is a method using a cutting tool.

The method of cutting the end face of the polarizing plate according to the present embodiment includes the following steps:

[a] a first step of superposing a plurality of rectangular polarizing plates to obtain a polarizing plate laminate, and

[b] A cutting tool having a cutting edge, which rotates about a rotation axis, relative to the polarizing plate laminate along the longitudinal direction of the end face of the obtained polarizing plate laminate, is relatively moved to cut the end face of the polarizing plate laminate 2 Process

. Hereinafter, each step will be described in detail.

[First Step]

This step is a step of stacking a plurality of rectangular polarizing plates to obtain a polarizing plate laminate. The " rectangular shape " is square or rectangular, and its size is not particularly limited. And is usually obtained by cutting a long polarizing plate. Although the number of the overlapped polarizing plates is not particularly limited, according to this embodiment, the end faces of the respective polarizing plates can be integrally processed in a good finishing state, even when the polarizing plate laminate has a considerable height.

4, which is a drawing for explaining the second step to be described later for cutting the end face of the polarizing plate laminate, the polarizing plate laminate W obtained by superposing a plurality of polarizing plates has four exposed end faces And each of the end faces is composed of the exposed end faces of the polarizing plates superimposed. The plurality of polarizing plates are superimposed such that their four sides are arranged. The overlapping of the polarizing plates can be performed automatically or manually.

[Second Step]

This step is a step of cutting the end face of the polarizing plate laminate obtained in the first step by a cutting tool to obtain an end face machining polarizing plate.

The end face machining device used in the second step of cutting the end face of the polarizing plate laminate relating to the present embodiment will first be described with reference to the drawings. Fig. 3 is a side view (Fig. 3 (a)) and a front view (Fig. 3 (b)) showing an example of a cutting tool included in the end surface machining device used in the second step, Is a schematic perspective view showing an example of an end face machining apparatus having a cutting tool shown in Fig.

As shown in Fig. 4, for example, the end face machining device used in the second process is a device that presses the polarizing plate stacked body W from above and below so that the polarizing plate stacked body W itself does not move during the cutting process, (Cutting rotary body) 10, which is rotatable about a rotation axis as a rotation center, for cutting an end face of the polarizing plate laminate W, .

The supporting portion 30 includes a plate-shaped substrate (moving means for the polarizing plate stacked body W) 31; A frame-shaped frame 32 disposed on the substrate 31; A rotation table (33) disposed on the substrate (31) and rotatable about a central axis; And a cylinder 34 provided at a position opposite to the rotary table 33 in the frame 32 and capable of being moved up and down. The polarizing plate stacked body W is fixed by being sandwiched by the rotary table 33 and the cylinder 34 via the jig 35.

On both sides of the substrate 31, two cutting tools 10 are installed facing each other. The cutting tool 10 is movable in the direction of the rotation axis in accordance with the size of the polarizing plate laminate W and the substrate 31 is movable so as to pass between the two cutting tools 10. In the cutting process, after the polarizing plate laminate W is fixed to the support portion 30 and the position of the cutting tool 10 in the rotation axis direction is appropriately adjusted, the cutting tool 10 is rotated about the rotation axis thereof , The substrate 31 is moved so that the polarizing plate stacked body W passes between opposing cutting tools 10. The cutting tool 10 is moved relative to the polarizing plate laminate W along the longitudinal direction of the end face of the polarizing plate laminate W (parallel to the longitudinal direction) It is possible to carry out the cutting operation in which the cutting edge is brought into contact with the exposed end face of the polarizing plate stacked body W facing each other and the end faces thereof are cut off.

Referring to Fig. 3, the cutting tool 10 may be a rotatable body fixed to the support table 10a and rotatable about an axis of rotation A. 3 and the like, the cutting tool 10 has a disk shape, but the shape is not limited thereto. The rotation axis A extends in a direction orthogonal to the end face of the polarizing plate laminate W to be cut.

The cutting tool 10 has an installation surface S perpendicular to the rotation axis A (and thus parallel to the end surface of the polarizing plate laminate W to be cut). On the mounting surface S, there are provided a first cutting portion group including cutting portions 1a, 1b, and 1c and a second cutting portion group including cutting portions 1d, 1e, and 1f, And a cutting edge (B) for cutting off the cutting edge (B). Each cutting portion is disposed around the rotating shaft (A). Each cutting portion protrudes from the mounting surface S toward the end face of the polarizing plate laminate W to be cut and the cutting edge B is disposed on the top face of the protruding cut portion. The cutting edge B of each cutting portion is normally arranged so as to extend parallel to the mounting surface S (and thus the end face of the polarizing plate laminate W to be cut).

3 (b), the cutting portions 1a, 1b, and 1c constituting the first cutting portion group are formed by cutting the cutting tool 10 in the rotating direction (the direction of the arrow shown in FIG. 3 (b) , The end face of the polarizing plate laminate W is contacted in this order to cut the end face. The cutting portions 1a, 1b, and 1c are arranged such that the distance from the mounting surface S to the cutting edge B (the cutting edge The projecting height of the cutting edge B of the cutting portion 1b is larger than the projecting height of the cutting edge B of the cutting portion 1a and the height of the cutting edge B of the cutting portion 1b is larger than the projecting height of the cutting edge B of the cutting portion 1a, 1c is larger than the projecting height of the cutting edge B of the cutting portion 1b. Similarly, as for the second cutting section group, the cutting sections 1d, 1e, and 1f constituting the second cutting section group rotate the cutting tool 10 in the rotating direction, And abuts on the end face to cut the end face. The cutting portions 1d, 1e, and 1f are arranged so that the projecting height of the cutting edge B becomes larger as the cutting portion located on the downstream side in the rotational direction of the cutting tool 10, that is, The projecting height of the cutting edge B of the cutting portion 1e is larger than the projecting height of the cutting edge B of the cutting portion 1d and the projecting height of the cutting edge B of the cutting portion 1f is larger than the projecting height of the cutting portion 1e Is greater than the projecting height of the cutting edge (B).

3 (b), the cutting portions 1a, 1b, and 1c constituting the first cutting portion group are arranged such that the cutting portions located on the downstream side in the rotational direction of the cutting tool 10 The distance from the rotary shaft A to the cutting edge B in the cutting portion 1b is set so that the distance from the rotary shaft A to the cutting edge B is shorter than the distance from the rotary shaft A to the cutting edge B, And the distance from the rotation axis A to the cutting edge B in the cutting portion 1c is shorter than that in the cutting portion 1b. Similarly to the second cutting section group, the cutting sections 1d, 1e, and 1f constituting the second cutting section group are arranged such that the cutting sections located on the downstream side in the rotational direction of the cutting tool 10 are arranged so that the rotational axis A ) To the cutting edge B is shortened. That is, the distance from the rotation axis A to the cutting edge B in the cutting portion 1e is shorter than that in the cutting portion 1d, and the distance from the rotation axis A in the cutting portion 1f to the cutting edge B Is shorter than that at the cutting portion 1e.

It is preferable that the respective cutting portions disposed on the mounting surface S are disposed at equal intervals around the rotating shaft A from each other.

In the cutting tool 10 shown in Fig. 3, the cutting portions 1a, 1b, 1d, and 1e other than the last cutting portion (the cutting portion at the most downstream side in the rotational direction) in each cutting portion group are roughly cut And these cutting edges B can be made of, for example, polycrystalline diamond. The last cutting portions 1c and 1f in each cutting group are for finishing, and these cutting blades B can be made of, for example, single crystal diamond. However, the material of the cutting edge B is not limited to these.

The size of the cutting tool 10 is set such that the diameter (shortest diameter) of the circle drawn by the cutting tool 10 due to the rotation of the cutting tool 10 is smaller than that of the polarizer plate laminate As long as it is equal to or greater than the height of the wafer W, as shown in Fig.

4, the method of cutting the end face in this step will be described. First, the above-described end face machining apparatus is used to rotate the polarizing plate laminate W through the jig 35 to the rotary table 33 and the cylinder 34 so that the two cutting tools 10 are arranged on the outer sides of the two opposing end faces of the polarizing plate laminate W. [ At this time, the cutting tool 10 is moved in the same position (for example, as passing through the center in the thickness direction of the polarizing plate stacked body W) at a position where the rotation axis A passes through the end face of the polarizing plate laminate W Position).

Subsequently, after the position of the cutting tool 10 in the direction of the rotational axis A is appropriately adjusted, the two cutting tools 10 are rotated around the rotational axis A thereof while the ends of the polarizer plate laminate W By relatively moving the cutting tool 10 relative to the polarizing plate laminate W along the longitudinal direction of the side surface of the polarizing plate laminate W, So as to cut the end face. 3, when the position of the cutting tool 10 is fixed, the substrate 31 is moved horizontally so that the polarizing plate stacked body W passes between the opposed cutting tools 10 The above-described relative movement is performed. At this time, the rotation direction of the cutting tool 10 is usually the opposite direction to the moving direction of the polarizing plate laminate W. 4, when the polarizing plate laminate W is moved in the leftward direction, the rotational direction of the cutting tool 10 on the inner side is a clockwise direction as viewed from the side of the polarizing plate laminate W, (10) is in the counterclockwise direction as viewed from the side of the polarizing plate laminate (W). As a result, the end faces of the respective polarizing plates can be cut to a satisfactory finished state.

The relative movement described above can also be performed by horizontally moving the cutting tool 10 by using a moving means (not shown) while the position of the polarizing plate laminate W is fixed. However, from the viewpoint of drive control of the end face machining apparatus, it is preferable to fix the position of the cutting tool 10 and perform the cutting while horizontally moving the polarizing plate laminate W.

4, the two opposite end faces of the polarizing plate laminate W are simultaneously cut by using the two cutting tools 10 for one polarizing plate laminate W, Which is very advantageous in terms of processing efficiency. However, it is also possible to perform cutting processing using one cutting tool for one polarizing plate laminate W.

In the cutting operation by the relative movement of the cutting tool 10, first, the cutting portions 1a and 1d located at the outermost side of the cutting tool 10 come into contact with the end face of the polarizing plate stacked body W , The end face is cut off. When the relative movement proceeds, the cut portions 1b and 1e provided inside the cutting portions 1a and 1d are in contact with the polarizing plate stacked body W. The cutting portions 1b and 1e cut the end face cut by the cutting portions 1a and 1d deeper because the projecting height of the cutting edge B is larger than that of the cutting portions 1a and 1d. In this manner, the cut portions 1a, 1b, 1d, and 1e cut the end face of the polarizing plate laminate W deeply and gradually. Finally, the cutting portions 1c and 1f provided inside the cutting portions 1b and 1e and having the projecting height of the cutting edge B larger than that of the cutting portions 1b and 1e, Cut the side and cut. The relative movement described above is usually performed from one end to the other end of the two end faces of the polarizing plate laminate W, whereby the entire surface of the two end faces can be cut.

After finishing the cutting of the two opposing end faces, the polarizing plate laminate W is rotated 90 degrees by the rotary table 33, and then the end faces of the other two end faces are processed in the same manner as described above I do.

In the above description, the rotating body rotatable about the rotating shaft A is used as the cutting tool 10, but the cylindrical rotating body which is rotatable about the stacking direction of the polarizing plate stacked body W is cut It can also be used as a tool. A plurality of cutting blades are arranged along the direction of the axis of rotation on the side surface of the cylindrical rotating body and the end surface of the polarizing plate is cut by contacting the polarizing plate stacked body W on the side of the cylindrical rotating body while rotating.

[Display device]

The polarizing plate produced by the present invention can be used for various display devices. The display device is an apparatus having a display element, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, an electron emission display device (such as a field emission display device (FED) (Display device (SED)), an electronic paper (a display device using electronic ink or an electrophoretic device, a plasma display device, a projection display device (e.g., a grating light valve (GLV) display device, a digital micromirror device And a piezoelectric ceramic display. The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct viewing type liquid crystal display device, and a projection type liquid crystal display device. These display devices may be a display device for displaying a two-dimensional image or a stereoscopic display device for displaying a three-dimensional image. Thus, the polarizing plate is usually laminated on the liquid crystal cell through the adhesive layer or the pressure-sensitive adhesive layer.

[ [Example]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. For example, the corona treatment was carried out by the following method.

<Corona treatment>

The corona treatment was performed by a corona discharge device manufactured by Kasuga Electric Co., Ltd. Specifically, a corona surface treatment frame "STR-1764", a high frequency power source "CT-0212" and a high pressure transformer "CT-T02W" were used.

[Example 1]

(1) Resin layer formation process

As the base film, a non-oriented polypropylene (PP) film (melting point: 163 占 폚) having a thickness of 90 占 퐉 was used and the surface thereof was subjected to corona treatment to form a primer layer on the corona-treated surface. The primer layer was prepared by dissolving polyvinyl alcohol powder (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization 1100, degree of saponification 99.5 mol%, trade name &quot; Z-200 &quot;) in hot water at 95 캜, And 5 parts by weight of a crosslinking agent (manufactured by Daoka Chemical Co., Ltd., trade name: Sumireze Resin (registered trademark) 650) was added to 6 parts by weight of polyvinyl alcohol powder. For forming the primer layer, this mixed aqueous solution was coated on the corona-treated surface of the base film with a small-diameter gravure coater, and this was dried at 80 DEG C for 10 minutes. The thickness of the primer layer was 0.2 탆.

Subsequently, a polyvinyl alcohol aqueous solution having a concentration of 8% by weight was prepared by dissolving polyvinyl alcohol powder (trade name "PVA124" manufactured by Kuraray Co., Ltd., average degree of polymerization: 2400, degree of saponification: 98.0 to 99.0 mol%) in hot water at 95 ° C. The obtained aqueous solution was coated on the primer layer using a lip coater and dried at 80 DEG C for 20 minutes to produce a three-layer laminated film comprising a base film, a primer layer and a resin layer.

(2) Stretching process

The laminated film was subjected to 4.6-fold free-end uniaxial stretching at 160 캜 using a vertical uniaxial stretching apparatus of a floating type to obtain a stretched film.

(3) Dyeing process

After that, the stretched film was dipped in a dyeing solution which is a mixed aqueous solution of iodine and potassium iodide at 30 占 폚 for about 180 seconds, and then the excess iodine solution was washed with pure water at 10 占 폚. Subsequently, the substrate 1 was immersed in a crosslinking solution 1 of an aqueous boric acid solution at 78 DEG C for 120 seconds, and subsequently immersed in a crosslinking solution 2 at 70 DEG C containing boric acid and potassium iodide for 60 seconds. Thereafter, it was washed with pure water at 10 캜 for 10 seconds, and finally dried at 40 캜 for 300 seconds. By the above steps, a polarizing film was formed from the resin layer to obtain a polarizing laminated film. The mixing ratio of each solution is as follows.

<Dyeing solution>

Water: 100 parts by weight

Iodine: 0.6 parts by weight

Potassium iodide: 10 parts by weight

&Lt; Crosslinking solution 1 &

Water: 100 parts by weight

Boric acid: 9.5 parts by weight

&Lt; Crosslinking solution 2 &

Water: 100 parts by weight

Boric acid: 5.0 parts by weight

Potassium iodide: 6 parts by weight

(4) First bonding step

As the first protective film, a ring-shaped polyolefin-based resin film having a thickness of 23 占 퐉 (trade name "Zeonoiafilm ZF14-023" manufactured by Nippon Zeon Co., Ltd.) was prepared, and the joint surface was subjected to corona treatment. An ultraviolet curable adhesive was coated on the corona-treated surface of the first protective film by a microgravure coater and bonded to the opposite side of the polarizing film of the polarizing laminated film produced in the above (3). Thereafter, an ultraviolet ray was irradiated from the side of the protective film so that the accumulated light quantity was 250 mJ / cm ² using a ultraviolet ray irradiator with a belt conveyor equipped with an ultraviolet lamp "D bulb" manufactured by Fusion UV Systems, And cured. Thus, a five-layer film comprising a base film, a primer layer, a polarizing film, an ultraviolet curable adhesive layer, and a first protective film was obtained. The thickness of the adhesive layer after curing was 1.0 占 퐉.

The above ultraviolet ray-curable adhesive is prepared by mixing and degassing the following components. The photocationic polymerization initiator obtained in the form of a 50% propylene carbonate solution was used. The blending amount (2.25 parts) shown below is a solid amount.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 75 parts

20 parts of 1,4-butanediol diglycidyl ether

5 parts of 2-ethylhexyl glycidyl ether

Triarylsulfonium hexafluorophosphate based light-ion polymerization initiator 2.25 parts

(5) Peeling step and second bonding step

The base film was peeled off from the film of the five-layer structure produced in the above (4) to obtain a polarizing plate with a one-side protective film. The base film was easily peeled off. Next, the same protective film as used in the above (4) was used as the second protective film, and the same UV-curable adhesive was applied to the corona-treated surface using a microgravure coater, and this was coated on the polarizing plate Bonded to the primer layer surface. Next, ultraviolet rays were irradiated from the side of the second protective film under the same condition as the above (4) to cure the adhesive layer to obtain a polarizing plate with a double-side protective film. The thickness of the adhesive layer after curing was 1.0 占 퐉.

(6) End face machining process

The polarizing plate with a double-sided protective film obtained in the above (5) was cut into a size of 100 mm x 60 mm, and 100 sheets of polarizing plates with a protective film on both sides after cutting were laminated in four sides to obtain a polarizing plate laminate (W). Next, except that the first cutting group and the second cutting group have five cutting portions, the polarizing plate stacked body W is formed by using the same end face machining device as the end face machining device shown in Figs. 3 and 4 After being fixed to the end face machining device, cutting was performed on all four end faces. The cutting conditions of the four end faces were all the same.

In each cutting section group, the five cutting sections are arranged so that the projecting height of the cutting edge B becomes larger as the cutting section located on the downstream side in the rotating direction of the cutting tool 10 becomes. The five cutting portions are arranged such that the distance from the rotational axis A to the cutting edge B becomes shorter as the cutting portion located on the downstream side in the rotational direction of the cutting tool 10 becomes shorter. Each of the cutting sections constituting the first cutting section group and the second cutting section group is disposed at an equal distance apart from each other around the rotational axis A and is provided at a position facing the cutting edge B through the rotational axis A, And two cutting portions having the same distance from the rotation axis A to the cutting edge B are disposed.

Concretely, the polarizing plate laminate W is horizontally moved while the cutting tool 10 is rotated about the rotational axis A thereof while the position of the cutting tool 10 is fixed, The cutting tool 10 is relatively moved relative to the polarizing plate laminate W in parallel with the longitudinal direction of the end face of the cutting edge B so that the cutting edge B of each cutting edge is brought into contact with the two end faces facing each other, Is cut at the same time. 4, the polarizing plate laminate W was moved in the leftward direction, and the rotating direction of the cutting tool 10 on the inner side was clockwise as viewed from the polarizing plate laminate W side. The relative movement was performed from one end of the end face to the other end. By this relative movement once, five steps of cutting are performed by the five kinds of cutting portions whose projection heights of the cutting edge B are different.

Subsequently, the polarizing plate laminate W was rotated 90 degrees by the rotary table 33, and the remaining two end faces were cut at the same time in the same manner as described above.

[Example 2]

Except that the stretching magnification in the stretching step of the above (2) was changed to 5.2 times and the drying condition in the dyeing step of (3) was changed to 50 seconds of drying for 150 seconds and then of 65 seconds of drying for 150 seconds A polarizing plate with a double-sided protective film was produced in the same manner as in Example 1.

[Example 3]

As a first protective film and a second protective film of the above-mentioned (4) and (5), a 25 탆 TAC film ("Konica Minolta Tac Films KC2UA (25 탆)" manufactured by Konica Minolta Advanced Layer Co., Ltd.) A polarizing plate with a double-side protective film was produced in the same manner as in Example 1. [

[Comparative Example 1]

A polarizing plate with a double-side protective film was produced in the same manner as in Example 1, except that the stretching magnification in the stretching step (2) was changed to 5.2 times.

[Comparative Example 2]

A polarizing plate with a double-side protective film was produced in the same manner as in Example 1, except that the stretching magnification in the stretching step (2) was changed to 5.4 times.

&Lt; Measurement of penetration strength per unit film thickness of polarizing film >

In Example 1 and Comparative Examples 1 and 2, the polarizing film was peeled off from the polarizing laminated film obtained after the dyeing step of (3), and a piece having a length of 100 mm and a width of 30 mm was cut out and used as a sample for piercing test. The stabbing test was carried out using a small tabletop machine "EZ Test" manufactured by Shimadzu Corporation equipped with a needle having a diameter of 1 mmφ and 0.5 R at a measuring temperature of 23 ± 3 ° C and a sticking rate of 0.33 cm / Lt; / RTI &gt; The stamper strength measured by the sting test was determined by conducting a sting test on 12 test samples. The thickness of the polarizing film was measured with a contact type film thickness meter (trade name &quot; DIGIMICRO MH-15M &quot;, manufactured by Nikon Corporation), and the penetration strength per unit film thickness was determined. The results are shown in the column of &quot; thickness of polarizing film &quot; and &quot; sting intensity &quot; in Table 1.

<Machinability of end face>

It was visually confirmed whether or not the polarizing film was cracked in the end face machining step (6) of Example 1 and Comparative Examples 1 and 2. The results are shown in the column of &quot; presence / absence of missing cracks &quot; in Table 1.

A first polarizer, a first polarizer, a second polarizer, a second polarizer, a second polarizer, a second polarizer, and a second polarizer. The present invention relates to a cutting tool and a method of manufacturing the same, and more particularly, to a cutting tool having a cutting tool, B: cutting edge, S: mounting surface.

Claims (4)

A polarizing plate comprising a protective film on at least one surface of a polarizing film,
The penetration strength per unit film thickness of the polarizing film is 5.8 gf /
Wherein the polarizing film has a thickness of 10 mu m or less,
And the end face of the polarizing plate is cut. delete The polarizing plate according to claim 1, wherein the polarizing plate comprises the protective film on both surfaces of the polarizing film. The polarizing plate according to claim 1, wherein the polarizing plate and the protective film are bonded via an active energy ray-curable adhesive.

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