JP2010054824A - Polarizing plate and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate having an improved durability in regard to the polarizing plate in which a polyethylene terephthalate film is laminated via an adhesive layer on one side surface of a polarizing film made of a polyvinyl alcohol-based resin and a transparent resin film is laminated via an adhesive layer on the other side surface. <P>SOLUTION: The polarizing plate is prepared by laminating the polyethylene terephthalate film via the adhesive layer on one side surface of the polarizing film made of the polyvinyl alcohol-based resin and laminating the transparent resin film via the adhesive layer on the other side surface, wherein outer peripheral edge parts of the polarizing plate are formed such that the polarizing film is not exposed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate and a method for producing the same.

  A polarizing plate is usually a transparent resin film, for example, a cellulose acetate type typified by triacetyl cellulose, on an adhesive layer on one or both sides of a polarizing film made of a polyvinyl alcohol-based resin having a dichroic dye adsorbed and oriented. The protective film is laminated. This is bonded to a liquid crystal cell with an adhesive via another optical film as necessary to form a component of a liquid crystal display device.

  In a polarizing plate in which protective films are laminated on both surfaces of such a polarizing film, a proposal has been made to prevent the polarizing film from being exposed at the outer peripheral edge for the purpose of improving durability. For example, in JP-A-2006-106016 (Patent Document 1), a cycloolefin-based resin film is laminated on one surface of a polarizing film via an adhesive layer, and the other surface via an adhesive layer. It describes that the polarizing film is formed so as not to be exposed by cutting the outer peripheral end of a polarizing plate formed by laminating a cellulose resin film. In addition, in JP-A-10-206633 (Patent Document 2), when a polarizing plate in which a protective film is laminated on both sides of a polarizing film is chip-cut, the cutting is preheated to a temperature higher than the thermal deformation temperature of the protective film. It is described that, by cutting with a tool, the cut end surface of the protective film is thermally deformed and the edge of the polarizing film underneath is covered. Moreover, in JP-A-2004-21088 (Patent Document 3), a polarizing plate in which a protective film is laminated on both sides of a polarizing film is bonded onto a glass substrate, and in this state, an outer peripheral end of the polarizing plate is attached. In addition, it is described that coating is performed with a water-resistant resin so as to straddle the glass substrate from the upper surface side of the polarizing plate.

Furthermore, there is also a proposal for cutting in order to finish the end face of the laminated film on which the polarizing plate itself and other optical films are laminated. For example, in Japanese Patent Laid-Open No. 2001-54845 (Patent Document 4), in a state where a plurality of laminated films are stacked and the blade surface of the rotary blade faces the outer peripheral end portion, the outer peripheral end portion is attached to the rotary blade. It is described that finishing is carried out by. Japanese Patent Application Laid-Open No. 2003-220512 (Patent Document 5) describes that an outer peripheral end portion of a polarizing plate or the like is continuously rough-cut and finished by a fly-cut method.
JP 2006-106016 A Japanese Patent Laid-Open No. 10-206633 JP 2004-21088 A JP 2001-54845 A JP 2003-220512 A

  The polarizing plate is required to have various configurations in accordance with the characteristics of the liquid crystal display device. Usually, the protective film or optical film disposed on the liquid crystal cell side is required to have retardation characteristics, and the polarizing film is sandwiched between them. Depending on the application, the protective film or optical film placed on the opposite side has surface properties such as glare (behind the mirror surface), hard coat, anti-glare (anti-glare), and anti-reflection. Required.

  Therefore, if a polyethylene terephthalate film is laminated on one side of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer and a transparent resin film is laminated on the other side via an adhesive layer, surface characteristics can be improved. The effects of each of the polyethylene terephthalate film, which is relatively easy to apply, and the transparent resin film having retardation characteristics, can be effectively expressed, and each function film is disposed on each side of the polarizing film. As a result, various types of requests can be widely met.

  However, a polarizing plate in which a polyethylene terephthalate film is laminated on one surface of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer and a transparent resin film is laminated on the other surface via an adhesive layer is Because the polarizing film is sandwiched between protective films with different properties, there are problems with the polarizing plate when the durability test is performed due to differences in physical properties, thermal properties, mechanical properties, etc. Tended to occur. For example, when a heat shock test or the like is performed, there is a problem that a crack or the like is generated in the polarizing plate.

  Therefore, an object of the present invention is to laminate a polyethylene terephthalate film via an adhesive layer on one side of a polarizing film made of a polyvinyl alcohol resin, and a transparent resin film via an adhesive layer on the other side. It is to improve the durability of the polarizing plate. Another object of the present invention is to provide a method by which the polarizing plate can be advantageously produced.

  As a result of diligent research under such a purpose, the present inventors have laminated a polyethylene terephthalate film on one side of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and on the other side. After cutting the polarizing plate with the transparent resin film laminated through the adhesive layer, and cutting the outer peripheral edge, the occurrence of cracks and the like when performing the above durability test It was found to be suppressed. Moreover, when the outer peripheral edge part of the polarizing plate was observed with the microscope, it also discovered that it was preferable for the improvement of durability that the polarizing film was not exposed in the outer peripheral edge part. The present invention has been completed based on such findings.

  That is, according to the present invention, from the first standpoint, a polyethylene terephthalate film is laminated on one surface of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and the other surface is interposed via an adhesive layer. Thus, there is provided a polarizing plate in which a transparent resin film is laminated, wherein the outer peripheral end of the polarizing plate is formed such that the polarizing film is not exposed.

  According to the present invention, from a second standpoint, a polyethylene terephthalate film is laminated on one surface of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and an adhesive layer is interposed on the other surface. The transparent resin film is laminated, and after the polarizing plate is chip-cut in the laminated state, or preferably with at least one of the outer sides, particularly with the adhesive layer formed on the outer side of the transparent resin film, A method of manufacturing a polarizing plate is also provided by cutting the outer peripheral edge.

  Since the polarizing film of the present invention is in a state in which the polarizing film is not exposed at the outer peripheral edge portion, even when a durability test such as a heat shock test is performed, cracks are hardly generated, and even if cracks occur, they are conspicuous. It does not grow to a high level and has excellent durability. According to the method of the present invention, a polarizing plate which is hardly cracked and excellent in durability even when a durability test such as a heat shock test is performed can be produced industrially advantageously.

Hereinafter, the present invention will be described in detail.
<Polarizing plate>
In the polarizing plate of the present invention, a polyethylene terephthalate film is laminated on one surface of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and a transparent resin film is laminated on the other surface via an adhesive layer. It is manufactured by laminating each film in such a laminating manner. And the polarizing plate of this invention is formed in the state which a polarizing film does not expose in the outer peripheral edge part so that it may mention later.

<Polarizing film>
Specifically, the polarizing film comprising the polyvinyl alcohol-based resin contained in the polarizing plate of the present invention adsorbs the dichroic dye by subjecting the polyvinyl alcohol-based resin film to uniaxial stretching and dyeing treatment with a dichroic dye. Oriented.

  The polyvinyl alcohol resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1000-10000 normally, Preferably it is about 1500-5000.

  And what formed the above polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The film thickness of the polyvinyl alcohol-based raw film (sometimes referred to as “polyvinyl alcohol-based resin film”) is not particularly limited, but is, for example, about 10 μm to 150 μm.

  A polarizing film usually has a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, and a dichroic dye adsorbed. It is manufactured through a step of treating the polyvinyl alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

  Uniaxial stretching may be performed before dyeing, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural stages. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is usually about 3 to 8 times.

  In order to dye the polyvinyl alcohol resin film with the dichroic dye, for example, the polyvinyl alcohol resin film may be immersed in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic dye is used as the dichroic dye. The polyvinyl alcohol-based resin film is preferably subjected to an immersion treatment in water, particularly warm water, before the dyeing treatment.

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

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

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

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 1 to 120 seconds. After washing with water, a drying process is performed to obtain a polarizing film. The drying process is usually performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 100 ° C. The time for the drying treatment is usually about 60 to 600 seconds, preferably about 120 to 600 seconds.

  In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizing film. The thickness of this polarizing film is about 5 to 40 μm. In the present invention, a polyethylene terephthalate film is laminated on one surface of the polarizing film via an adhesive layer, and a transparent resin film is laminated on the other surface via an adhesive layer to form a polarizing plate.

<Polyethylene terephthalate film>
The polyethylene terephthalate film used in the present invention is a film excellent in mechanical properties, solvent resistance, scratch resistance, cost, etc., and the polarizing plate of the present invention using such polyethylene terephthalate has mechanical strength, etc. In addition, the thickness can be reduced.

  Here, polyethylene terephthalate is a resin in which 80 mol% or more of repeating units are composed of ethylene terephthalate. Other copolymer components include isophthalic acid, p-β-oxyethoxybenzoic acid, 4,4′-dicarboxydiphenyl, 4,4′-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid , Dicarboxylic acid components such as sebacic acid, 5-sodium sulfoisophthalic acid, 1,4-dicarboxycyclohexane, such as propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, bisphenol A ethylene oxide adduct, polyethylene glycol And diol components such as polypropylene glycol and polytetramethylene glycol. These dicarboxylic acid components and diol components can be used in combination of two or more if necessary. It is also possible to use an oxycarboxylic acid such as p-oxybenzoic acid in combination with the dicarboxylic acid component or diol component. Such other copolymerization component may contain a dicarboxylic acid component and / or a diol component containing a small amount of amide bond, urethane bond, ether bond, carbonate bond and the like.

  Polyethylene terephthalate is produced by a so-called direct polymerization method in which terephthalic acid and ethylene glycol (and other dicarboxylic acids and / or other diols if necessary) are directly reacted, dimethyl ester of terephthalic acid and ethylene glycol (and If necessary, any production method such as a so-called transesterification reaction in which a dimethyl ester of another dicarboxylic acid and / or another diol) is transesterified can be applied.

  Moreover, you may make a polyethylene terephthalate contain a well-known additive as needed. However, since transparency is required in optical applications, it is preferable to keep the additive amount to a minimum. Known additives include, for example, lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, impact resistance improvers, and the like. Examples of the light absorber include an ultraviolet absorber. For example, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzo Triazol-2-yl) phenol], 2- (5-methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl]- 2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5 Chloro-2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3 Benzotriazole UV absorbers such as 5-di-tert-amyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) -2H-benzotriazole; 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-methoxy 2-hydroxybenzophenone UV absorbers such as benzophenone and 2,2′-dihydroxy-4,4′-dimethoxybenzophenone; phenyl salicylates such as p-tert-butylphenylsalicylate and p-octylphenylsalicylate It includes such ester-based ultraviolet absorbers may be used two or more thereof as needed. When an ultraviolet absorber is included, the amount is usually 0.1% by weight or more, preferably 0.3% by weight or more, and preferably 2% by weight or less.

  The polyethylene terephthalate film used in the present invention can be produced by forming the raw material resin as described above into a film shape and subjecting it to a stretching treatment. The method for producing the stretched polyethylene terephthalate film is arbitrary and is not particularly limited. However, the non-oriented film obtained by melting the raw material resin and extrusion-molded into a sheet shape is higher than the glass transition temperature of polyethylene terephthalate. A method of performing a heat setting treatment after mechanical stretching at a temperature can be mentioned. Stretching may be simultaneous stretching or sequential stretching, but sequential stretching is preferred.

  The temperature at which the stretching is performed is not particularly limited as long as it is equal to or higher than the glass transition temperature of polyethylene terephthalate, but is preferably in the range of 80 to 130 ° C, more preferably in the range of 90 to 120 ° C. preferable.

  Moreover, it is preferable that the draw ratio of the polyethylene terephthalate film in this invention is 2.5-6 times, and it is more preferable that it is 3-5.5 times. This is because when the draw ratio is less than 2.5, the polyethylene terephthalate film tends not to exhibit sufficient transparency. In addition, for example, polyethylene terephthalate may be produced by a two-stage stretching method in which the film is stretched 1.1 to 6 times in the film longitudinal direction (film running direction) and then stretched 2.5 to 6 times in the film width direction. Good.

  From the viewpoint of reducing distortion of the orientation main axis in the polyethylene terephthalate film (displacement with respect to the stretching axis), the film is subjected to the longitudinal direction (the traveling direction of the film), the film after the stretching and before the heat setting treatment. It is preferable to perform a relaxation treatment in the width direction (direction perpendicular to the running direction of the film). The temperature for the relaxation treatment is 90 to 200 ° C, preferably 120 to 180 ° C. Although the amount of relaxation varies depending on the transverse stretching conditions, it is preferable to set the amount of relaxation and the temperature so that the heat shrinkage rate at 150 ° C. of the polyethylene terephthalate film after the relaxation treatment is 2% or less.

  The temperature of the heat setting treatment is usually 180 to 250 ° C, preferably 200 to 245 ° C. In the heat setting process, first, after performing the heat setting process at a constant length, the distortion of the orientation main axis is reduced, and in order to improve the strength such as heat resistance, further in the film longitudinal direction (film running direction) or film width direction It is preferable to perform a relaxation treatment. The amount of relaxation in this case is preferably adjusted such that the heat shrinkage rate at 150 ° C. of the polyethylene terephthalate film after the relaxation treatment is 1 to 10%, more preferably 2 to 5%.

  In the present invention, a polyethylene terephthalate film having a maximum value of distortion of the orientation main axis (shift angle with respect to the stretching axis) of 30 degrees or less, more preferably 10 degrees or less, and further preferably 5 degrees or less is suitably used. When a polarizing plate using a stretched polyethylene terephthalate film having a maximum value of distortion of the orientation main axis exceeding 30 degrees is bonded to a liquid crystal display screen of a liquid crystal display device, coloring failure tends to increase. Further, the lower limit value of the maximum strain value of the orientation axis of the polyethylene terephthalate film is not particularly limited, but is preferably 0 ° or more. The maximum value of the orientation main axis strain of the stretched polyethylene terephthalate film described above is, for example, a retardation film inspection apparatus RETS system (manufactured by Otsuka Electronics Co., Ltd.), a microwave transmission type molecular orientation meter (MOA) (Oji Scientific Instruments ( It is possible to measure by using the product).

The thickness d _PET polyethylene terephthalate film used in the present invention is preferably in the range of 20 to 60 [mu] m, and more preferably in a range of 30 to 50 [mu] m. When the thickness d _PET of the polyethylene terephthalate film is less than 20 μm, it tends to be difficult to handle (inferior in handleability), and when the thickness d _PET exceeds 60 μm, the merit of thinning tends to be reduced. .

In addition, the in-plane retardation value R _PET of the polyethylene terephthalate film used in the present invention is preferably 1000 nm or more, and more preferably 3000 nm or more. When the in-plane retardation value R _{PET of the} polyethylene terephthalate film is less than 1000 nm, coloring from the front tends to be conspicuous. The upper limit of the in-plane retardation value R _PET of the polyethylene terephthalate film used in the present invention is sufficient up to about 10,000 nm.

The in-plane retardation value R _PET of the polyethylene terephthalate film is represented by the following formula (1).

_{R PET = (n a -n b} ) × d PET (1)
(In the above formula (1), n _a plane slow axis direction of the refractive index of the polyethylene terephthalate film, n _b is the refractive index in the in-plane fast axis direction (perpendicular to the plane slow axis direction), d _PET is the thickness of the polyethylene terephthalate film.)
The polyethylene terephthalate film used in the present invention preferably has a MOR (Maximum Oriented Ratio) value of 1.5 or more, more preferably 2.0 or more, and particularly preferably 2.2 or more. . This is because when a polarizing plate using a polyethylene terephthalate film having an MOR value of less than 1.5 is applied to a liquid crystal display device, the oblique interference unevenness tends to increase. The upper limit of the MOR value of the polyethylene terephthalate film is not particularly limited, but 7 or less is sufficient. Here, the MOR value is a ratio (maximum value / minimum value) between the maximum value and the minimum value of the transmission microwave intensity measured by the transmission type molecular orientation meter, and serves as an anisotropy index. The MOR value can be measured using a microwave transmission type molecular orientation meter (manufactured by Oji Scientific Instruments).

  Moreover, the anti-glare property (haze) may be provided to the polyethylene terephthalate film used in the present invention. The method for imparting antiglare properties is not particularly limited, and is, for example, a method in which inorganic fine particles or organic fine particles are mixed into the raw material resin to form a film, which is opposite to the side on which the polarizing film of the polyethylene terephthalate film is laminated. Examples thereof include a method of forming a glare-proof layer by coating a surface with a coating solution obtained by mixing inorganic fine particles or organic fine particles with a resin binder. Among these, from the viewpoint of reducing the color unevenness (interference unevenness) derived from the polyethylene terephthalate film, the present invention has a configuration further comprising an antiglare layer laminated on the surface opposite to the side on which the polarizing film of the polyethylene terephthalate film is laminated. It is preferable to realize a polarizing plate.

  Typical inorganic fine particles for imparting antiglare properties include silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate, and the like. be able to. As the organic fine particles, resin particles such as crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and polyimide particles can be used.

  In addition, a cellulose-based resin film such as triacetyl cellulose (TAC), an olefin-based resin film, an acrylic-based material is provided on the surface opposite to the side on which the polarizing film of the polyethylene terephthalate film is laminated via an adhesive layer or an adhesive layer. You may make it provide anti-glare property by the method of laminating | stacking the anti-glare protective film chosen from a resin film and a polyester-type resin film. The antiglare protective film is prepared by a method of coating the surface of a base film with a coating solution, a method of forming a resin film by mixing organic fine particles or inorganic fine particles in a resin as a base material, and the like. It can be used suitably. In the case of using such an antiglare protective film, the thickness is preferably in the range of 5 to 120 μm, and more preferably in the range of 20 to 80 μm. Moreover, it is preferable that the haze value of such an anti-glare protective film is in the range of 2 to 45%. This is because the antiglare effect may be impaired when the haze value of the antiglare protective film is less than 2%, and when the haze value of the antiglare protective film is higher than 45%, the screen This is because there is a concern that the visibility may be reduced.

  In the polyethylene terephthalate film used in the present invention, a functional layer other than the antiglare layer can be laminated on one side or both sides as long as the effects of the present invention are not hindered. Examples of the laminated functional layer include a conductive layer, a hard coat layer, a smoothing layer, an easy-sliding layer, an anti-blocking layer, and an easy-adhesion layer. Especially, since this polyethylene terephthalate film is laminated | stacked through a polarizing film and an adhesive bond layer, it is preferable that the easily bonding layer is laminated | stacked.

  The component constituting the easy-adhesion layer is not particularly limited. For example, a polyester resin, a urethane resin, or an acrylic resin having a polar group in the skeleton and a relatively low molecular weight and a low glass transition temperature. Examples thereof include resins. Moreover, a crosslinking agent, an organic or inorganic filler, a surfactant, a lubricant and the like can be contained as necessary.

  The method of forming each functional layer in a polyethylene terephthalate film is not particularly limited, but for example, a method of forming in a film in which all stretching steps have been completed, during a step of stretching a polyethylene terephthalate resin, That is, a method of forming between the longitudinal stretching step and the lateral stretching step, a method of forming immediately before or after being bonded to the polarizing film, and the like are employed. Among these, from the viewpoint of productivity, a method in which a polyethylene terephthalate-based resin is formed after being longitudinally stretched and then stretched laterally is preferably employed.

<Transparent resin film>
In the polarizing plate of the present invention, a transparent resin film is laminated via an adhesive layer on the surface of the polarizing film that is different from the surface on which the polyethylene terephthalate film is laminated. Such a transparent resin film exhibits a function as a so-called protective film or optical film, and particularly preferably exhibits retardation characteristics when it is disposed on the liquid crystal cell side. Such a transparent resin film is, for example, a transparent resin film selected from a cycloolefin resin film, a cellulose resin film, a polycarbonate resin film, a polyolefin resin film, a polyester resin film, and an acrylic resin film. Is preferred. Hereinafter, each of these films will be described.

<Cycloolefin resin film>
The cycloolefin resin film is a transparent resin film made of a cycloolefin resin. Such a cycloolefin-based resin is a thermoplastic resin having a monomer unit made of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene-based monomer. This cycloolefin-based resin can be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a ring-opening copolymer using two or more kinds of cycloolefins, as well as cycloolefins and chain olefins or vinyl groups. An addition copolymer with an aromatic compound having Those having a polar group introduced are also effective.

  In the case of a copolymer of a cycloolefin and a chain olefin or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene, and also an aromatic compound having a vinyl group. Examples include styrene, α-methyl styrene, nuclear alkyl-substituted styrene and the like. In such a copolymer, the monomer unit composed of cycloolefin may be 50 mol% or less, for example, about 15 to 50 mol%. In particular, when a ternary copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group is used, the amount of monomer units composed of cycloolefin can be relatively small. In such a terpolymer, the unit of monomer composed of a chain olefin is usually about 5 to 80 mol%, and the unit of monomer composed of an aromatic compound having a vinyl group is usually about 5 to 80 mol%.

  Commercially available thermoplastic cycloolefin resins such as “Topas” sold by Ticona in Germany, “Arton” sold by JSR Corporation, and “ZEONOR” sold by Nippon Zeon Corporation. ) ”And“ ZEONEX ”,“ Apel ”sold by Mitsui Chemicals, Inc. (both are trade names). Such a cycloolefin-based resin is formed into a film, and a known method such as a solvent casting method or a melt extrusion method is appropriately used for forming the film.

The cycloolefin resin film can be given an arbitrary retardation value by stretching. Thereby, an appropriate optical compensation function is provided, which can contribute to the expansion of the viewing angle of the liquid crystal display device. The in-plane retardation value R ₀ of the stretched cycloolefin-based resin film is preferably 40 to 100 nm, and more preferably 40 to 80 nm. When the in-plane retardation value R ₀ is less than 40 nm or exceeds 100 nm, the viewing angle compensation ability for the liquid crystal panel tends to be lowered. The thickness direction retardation R _th for the stretched cycloolefin resin film is preferably 80 to 300 nm, more preferably 100 to 250 nm. When the thickness direction retardation value _Rth is less than 80 nm or more than 300 nm, the viewing angle compensation ability with respect to the liquid crystal panel tends to be reduced as described above. The in-plane retardation value R ₀ and the thickness direction retardation value R _th of the stretched cycloolefin-based resin film are represented by the following formulas (1) and (2), respectively, for example, KOBRA21ADH (Oji Scientific Instruments Co., Ltd.) ))).

_{R 0 = (n x -n y} ) × d (1)
R _th = [( _nx + _ny ) / 2- _nz ] × d (2)
(The above formula (1), (in 2), n _x is stretched in-plane slow axis direction of the refractive index of the cycloolefin resin film, n _y in-plane fast axis direction (in-plane slow axis direction refractive index in the orthogonal direction to) a, the n _z refractive index in the thickness direction of the cycloolefin-based resin film stretched, d is the thickness of the cycloolefin resin film stretched.)
Usually, such stretching of the cycloolefin-based resin film is continuously performed while unwinding the film roll, and the film is stretched in a heating furnace in a traveling direction of the roll or in a direction perpendicular to the traveling direction. As the temperature of the heating furnace, a range approximately 100 ° C. higher than the glass transition temperature from the vicinity of the glass transition temperature of the cycloolefin-based resin is usually employed. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times. Film-formed and stretched cycloolefin resin films are also commercially available. For example, “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd., “Zeonor Film” sold by Optes Co., Ltd. Etc. (both are trade names).

  When the cycloolefin-based resin film is in a roll state, the films tend to adhere to each other and easily cause blocking. Therefore, the protective film is usually bonded to roll.

  Since cycloolefin resin films generally have poor surface activity, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment is performed on the surface bonded to the polarizing film. Is preferred. Among these, plasma treatment and corona treatment that can be performed relatively easily are preferable.

  The thickness of such a cycloolefin-based resin film is preferably thin. However, if it is too thin, the strength is lowered and the processability is inferior. On the other hand, if it is too thick, the transparency is lowered or the weight of the polarizing plate is large. Problems such as becoming. Therefore, the appropriate thickness is, for example, about 5 to 200 μm, preferably 10 to 150 μm, and more preferably 20 to 100 μm.

<Cellulosic resin film>
The cellulose resin film is usually composed of a cellulose resin which is a cellulose part or a complete acetate ester, and examples thereof include a triacetyl cellulose film, a diacetyl cellulose film, and a cellulose acetate propionate film. The triacetylcellulose film includes “Fujitac TD80”, “Fujitac TD80UF” and “Fujitac TD80UZ” sold by Fuji Photo Film Co., Ltd., “KC8UX2M” and “KC8UY” sold by Konica Minolta Opto Co., Ltd. Etc. (both are trade names). The surface of the cellulose resin film may be subjected to a surface treatment such as an antiglare treatment, a hard coat treatment, an antistatic treatment, or an antireflection treatment, depending on the application. Arbitrary retardation values can be imparted to the cellulose resin film by stretching.

  Cellulosic resin films are also in a roll state, and the films tend to adhere to each other and easily cause blocking. Therefore, usually, the roll end part is subjected to uneven processing or a ribbon is inserted to the end part. Rolled. In addition, this cellulose resin film is usually subjected to a saponification treatment in order to enhance the adhesiveness with the polarizing film. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be employed.

  The thickness of such a cellulose-based resin film is preferably thin. However, if it is too thin, the strength decreases and the processability is poor. On the other hand, if it is too thick, the transparency decreases and the weight of the polarizing plate increases. Problems occur. Therefore, an appropriate thickness of the film is, for example, about 5 to 200 μm, preferably 10 to 150 μm, and more preferably 20 to 100 μm.

<Acrylic resin film>
The acrylic resin constituting the acrylic resin film used in the present invention means a material obtained by mixing, melting, and kneading a methacrylic resin and additives added as necessary. By using such an acrylic resin film as a transparent resin film, the mechanical strength of a liquid crystal panel obtained by bonding a polarizing plate to a liquid crystal cell can be further improved, and further thinning of the liquid crystal panel is achieved. It becomes possible.

  The methacrylic resin is a polymer mainly composed of methacrylic acid ester. The methacrylic resin may be a homopolymer of one kind of methacrylic acid ester or a copolymer of methacrylic acid ester with other methacrylic acid ester or acrylic acid ester. Examples of the methacrylic acid esters include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the alkyl group usually has about 1 to 4 carbon atoms. The acrylic ester that can be copolymerized with the methacrylic ester is preferably an alkyl acrylate, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. The number of carbon atoms in the group is usually about 1-8. In addition to these, the copolymer contains an aromatic vinyl compound such as styrene which is a compound having at least one polymerizable carbon-carbon double bond in the molecule, a vinyl cyanide compound such as acrylonitrile, and the like. Also good.

  Such an acrylic resin preferably contains acrylic rubber particles in terms of impact resistance and film-forming property of the film. The amount of acrylic rubber particles that can be contained in the acrylic resin is preferably 5% by weight or more, more preferably 10% by weight or more. The upper limit of the amount of the acrylic rubber particles is not critical, but if the amount of the acrylic rubber particles is too large, the surface hardness of the film is lowered, and when the film is subjected to surface treatment, it is resistant to the organic solvent in the surface treatment agent. Solvent property decreases. Therefore, the amount of acrylic rubber particles that can be contained in the acrylic resin is preferably 80% by weight or less, and more preferably 60% by weight or less.

  The acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylate ester as an essential component. The acrylic rubber particles may have a single-layer structure consisting essentially only of the elastic polymer. It may have a multi-layer structure in which the coalescence is one layer. Specifically, as this elastic polymer, 50 to 99.9% by weight of an alkyl acrylate and at least one kind of other vinyl monomer copolymerizable therewith, 0 to 49.9% by weight, A cross-linked elastic copolymer obtained by polymerization of a monomer comprising 0.1 to 10% by weight of a polymerizable cross-linkable monomer is preferably used.

  Examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like, and the alkyl group usually has about 1 to 8 carbon atoms. Examples of the other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule. Examples thereof include methacrylic acid esters such as methyl acid, aromatic vinyl compounds such as styrene, vinylcyan compounds such as acrylonitrile, and the like. Examples of the copolymerizable crosslinkable monomer include a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule. (Meth) acrylates of polyhydric alcohols such as (meth) acrylate and butanediol di (meth) acrylate, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate and methallyl (meth) acrylate, divinyl Examples include benzene. In this specification, (meth) acrylate refers to methacrylate or acrylate, and (meth) acrylic acid refers to methacrylic acid or acrylic acid.

  In addition to the acrylic rubber particles, the acrylic resin contains normal additives such as ultraviolet absorbers, organic dyes, pigments, inorganic dyes, antioxidants, antistatic agents, surfactants, and the like. Also good. Among these, an ultraviolet absorber is preferably used for improving weather resistance. Examples of the ultraviolet absorber include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (5 -Methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di -Tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5 -Di-tert-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-amyl-2-hydroxypheny ) Benzotriazole ultraviolet absorbers such as -2H-benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) -2H-benzotriazole; 2-hydroxy-4-methoxybenzophenone, 2- Hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4, Examples include 2-hydroxybenzophenone ultraviolet absorbers such as 4′-dimethoxybenzophenone; salicylic acid phenyl ester ultraviolet absorbers such as p-tert-butylphenyl salicylic acid ester and p-octylphenyl salicylic acid ester. It may be used two or more thereof. When the acrylic resin contains an ultraviolet absorber, the amount is usually 0.1% by weight or more, preferably 0.3% by weight or more, and preferably 2% by weight or less.

  As a method for obtaining the acrylic resin film, various generally known methods such as a method using a feed block and a method using a multi-manifold die can be used. Among them, for example, a method of laminating via a feed block, multilayer melt extrusion from a T-die, and forming a film by bringing at least one surface of the obtained laminated film into contact with a roll or a belt is a film having good surface properties. It is preferable at the point obtained. In particular, from the viewpoint of improving the surface smoothness and surface gloss of an acrylic resin film, a method of forming a film by bringing both surfaces of a laminated film-like material obtained by multilayer melt extrusion molding into contact with the roll surface or belt surface Is preferred. In the roll or belt used in this case, the surface of the roll or belt in contact with the acrylic resin is preferably a mirror surface in order to impart smoothness to the acrylic resin film surface.

  The thickness of such an acrylic resin film is preferably thin. However, if it is too thin, the strength is lowered and the processability is inferior. On the other hand, if it is too thick, the transparency is lowered and the weight of the polarizing plate is increased. Problems occur. Therefore, the appropriate thickness is, for example, about 5 to 200 μm, preferably 10 to 150 μm, and more preferably 20 to 100 μm.

<Other transparent resin films>
As the transparent resin film other than the transparent resin film exemplified above, a polyolefin resin film made of a polyolefin resin such as polypropylene can also be used. As such a transparent resin film, a polycarbonate resin film can be used, and a polyester resin film can also be used. As such a polyester resin film, the same one as the above polyethylene terephthalate film may be used, or a different type may be used.

<Adhesive layer>
In the present invention, the polyethylene terephthalate film as described above is laminated on one surface of the polarizing film, and the transparent resin film is laminated on the other surface. Each of these films is laminated via an adhesive layer. Here, the adhesive contained in the adhesive layer used for adhesion between the polarizing film and the polyethylene terephthalate film, and the adhesive contained in the adhesive layer used for adhesion between the polarizing film and the transparent resin film are polyethylene terephthalate film and transparent In consideration of the adhesiveness between the resin film and the polarizing film, different types may be used, or the same type may be used. However, considering the ease of construction, etc., if both the polyethylene terephthalate film and the transparent resin film are adhered to the polarizing film, it is advantageous to use the same adhesive on both sides.

  Examples of such an adhesive used in the present invention include water-based adhesives, that is, adhesive components dissolved in water or dispersed in water from the viewpoint of thinning the adhesive layer. For example, a composition using a polyvinyl alcohol resin or a urethane resin as a main component is a preferable adhesive.

  When a polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin may be partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, or methylol group. Modified polyvinyl alcohol resins such as modified polyvinyl alcohol and amino group-modified polyvinyl alcohol may also be used. In this case, an aqueous solution of a polyvinyl alcohol resin is used as the adhesive. The density | concentration of the polyvinyl alcohol-type resin in an adhesive agent is 1-10 weight part normally with respect to 100 weight part of water, Preferably it is 1-5 weight part.

  In order to improve the adhesiveness, it is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to the adhesive composed of an aqueous solution of a polyvinyl alcohol resin. As the water-soluble epoxy resin, for example, a polyamide polyamine epoxy resin obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a polycarboxylic acid such as adipic acid and epichlorohydrin. Can be suitably used. Commercially available products of such polyamide polyamine epoxy resins include Sumire's Resin 650 (manufactured by Sumika Chemtex Co., Ltd.), Sumire's Resin 675 (manufactured by Sumika Chemtex Co., Ltd.), WS-525 (manufactured by Nippon PMC Corporation). Etc. The addition amount of these curable components and crosslinking agents (when added together as the curable component and the crosslinking agent) is usually 1 to 100 parts by weight, preferably 100 parts by weight, preferably 100 parts by weight of the polyvinyl alcohol resin. 1 to 50 parts by weight. When the addition amount of the curable component or the crosslinking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin, the effect of improving adhesiveness tends to be reduced. This is because the adhesive layer tends to be brittle when the addition amount of the crosslinking agent exceeds 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin.

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

  Polyester-based ionomer urethane resins are known per se. For example, JP-A-7-97504 describes an example of a polymer dispersant for dispersing a phenol-based resin in an aqueous medium. In JP-A-2005-70140 and JP-A-2005-208456, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group is used as an adhesive, and a polarizing film made of a polyvinyl alcohol resin is used as a cycloolefin film. The form which joins a resin film is shown.

  As a method of laminating the above-mentioned polyethylene terephthalate film and transparent resin film to the polarizing film, generally known methods may be used, for example, casting method, Meyer bar coating method, gravure coating method, comma coater method, doctor Examples thereof include a method in which an adhesive is applied to an adhesive surface of a polarizing film and / or a film bonded thereto by a blade method, a die coating method, a dip coating method, a spraying method, etc., and the both are overlapped. The casting method is a method of spreading and spreading an adhesive on the surface of a film to be coated while moving it in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two.

  After apply | coating an adhesive agent by the method mentioned above, a polarizing film and the film bonded by it are pinched | interposed by a nip roll etc., and are bonded together. Moreover, after dripping an adhesive agent between a polarizing film and the film bonded to it, the method of pressurizing this laminated body with a roll etc. and spreading it uniformly can also be used suitably. In this case, it is possible to use metal or rubber as the material of the roll. Furthermore, after dropping an adhesive agent between a polarizing film and the film bonded to it, the method of passing this laminated body between rolls and pressurizing and spreading is also preferably employed. In this case, these rolls may be made of the same material or different materials. The thickness of the adhesive layer after being bonded using the nip roll or the like before drying or curing is preferably 5 μm or less, and more preferably 0.01 μm or more.

  Thus, the order in which the polyethylene terephthalate film and the transparent resin film are laminated on the polarizing film is not particularly limited, and the method of laminating the other film after laminating one of the films on the polarizing film. Or a method of laminating both films on the polarizing film substantially simultaneously.

  Further, the surface of the adhesive layer may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment, etc., in order to improve adhesion. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  The laminated body joined via the aqueous adhesive is usually subjected to a drying treatment, and the adhesive layer is dried and cured. The drying process can be performed by blowing hot air, for example. The drying temperature is appropriately selected from the range of about 40 to 100 ° C, preferably 60 to 100 ° C. The drying time is, for example, about 20 to 1200 seconds. The thickness of the adhesive layer after drying is usually about 0.001 to 5 μm, preferably 0.01 μm or more, preferably 2 μm or less, more preferably 1 μm or less. If the thickness of the adhesive layer becomes too large, the appearance of the polarizing plate tends to be poor.

  After the drying treatment, sufficient adhesive strength may be obtained by performing curing at a temperature of room temperature or higher for at least half a day, usually several days or longer. Such curing is typically performed in a state of being wound in a roll. A preferable curing temperature is in the range of 30 to 50 ° C, more preferably 35 ° C or more and 45 ° C or less. When the curing temperature exceeds 50 ° C., so-called “roll tightening” is likely to occur in the roll winding state. The humidity during curing is not particularly limited, but is preferably selected so that the relative humidity is in the range of about 0% RH to 70% RH. The curing time is usually about 1 to 10 days, preferably about 2 to 7 days.

  Moreover, a photocurable adhesive agent can also be used for the adhesive agent used for the adhesive bond layer of the polarizing plate of this invention. When the photocurable adhesive is used in this way, the polarizing film is not particularly exposed at the outer peripheral edge of the polarizing plate as compared with the case of using another adhesive such as the aqueous adhesive. It will be advantageous. This is because when a photocurable adhesive is used, it is not necessary to perform a drying process, and the phenomenon that the end face of the polarizing plate becomes uneven in the thickness direction due to expansion or contraction of the film due to the drying process can be avoided. It is. When the end faces of the polarizing plates are uneven as described above, it is difficult to make the polarizing film unexposed even if the following cutting process is performed. Such a phenomenon that the end faces of the polarizing plate are uneven is particularly noticeable when a polyethylene terephthalate film is used. Therefore, the photocurable adhesive is applied to the adhesive layer in the polarizing plate of the present invention including the polyethylene terephthalate film. It is particularly effective to adopt

  Examples of such a photocurable adhesive include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator (that is, an epoxy-based photocurable adhesive). In this case, the photocurable adhesive is cured by irradiating with active energy rays. The light source of the 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, the low-pressure mercury lamp, the medium-pressure mercury lamp, the high-pressure mercury lamp, the ultrahigh-pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferable.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW. / Cm ² is preferable. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when the irradiation intensity is 6000 mW / cm ² or less, the heat radiated from the light source and the time of curing of the photocurable adhesive There is little risk of yellowing of the epoxy resin or deterioration of the polarizing film due to heat generation. The light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive to be cured and is not particularly limited. However, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10. It is preferably set to be 10000 mJ / m ² . When the cumulative amount of light to the photo-curable adhesive is 10 mJ / m ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and 10,000 mJ / m. ^{By being 2} or less, the irradiation time does not become too long, and good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 μm, preferably 0.01 μm to 2 μm, and more preferably 0.01 μm to 1 μm.

  When curing a photo-curable adhesive by irradiation with active energy rays, the polarizing film such as the degree of polarization, transmittance and hue, and the functions of the polarizing plate such as transparency of the polyethylene terephthalate film and transparent resin film are not deteriorated. It is preferable to carry out curing.

<Adhesive layer>
In the polarizing plate of the present invention, an adhesive layer for bonding the polarizing plate to the liquid crystal cell is formed on the outside of the transparent resin film (that is, the surface opposite to the side laminated with the polarizing film). Preferably it is. As the pressure-sensitive adhesive used for such a pressure-sensitive adhesive layer, a conventionally known appropriate pressure-sensitive adhesive can be used without particular limitation, and examples thereof include an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer can be provided by a method of using such a pressure-sensitive adhesive in the form of, for example, an organic solvent solution, applying it on a transparent resin film with a die coater or a gravure coater, and drying it. Can be provided also by a method of transferring a sheet-like pressure-sensitive adhesive formed on a plastic film (referred to as a separate film) to a transparent resin film. Although there is no restriction | limiting in particular also about the thickness of an adhesive layer, Generally it is preferable to exist in the range of 2-40 micrometers.

  Moreover, the optical functional film may be stuck to the outer surface of the polarizing plate of this invention through the said adhesive layer. Examples of the optical functional film include, in addition to the above-described optical compensation film based on the cellulose-based film or the cycloolefin-based film, an optical compensation film in which a liquid crystal compound is applied to the substrate surface and oriented, Reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, retardation film made of polycarbonate resin, film with anti-glare function with uneven surface, surface with anti-reflection treatment Examples thereof include a film, a reflective film having a reflective function on the surface, and a transflective film having both a reflective function and a transmissive function. Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the substrate surface and oriented are WV film (Fuji Film Co., Ltd.), NH film (Shin Nippon Oil Co., Ltd.), NR Examples include films (manufactured by Nippon Oil Corporation). For example, DBEF (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan) is a commercially available product corresponding to a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties. Etc. Moreover, as a commercial item corresponding to the phase difference film which consists of cyclic polyolefin resin, for example, Arton Film (made by JSR Corporation), Essina (made by Sekisui Chemical Co., Ltd.), Zeonore Film (made by Optes Co., Ltd.) Etc.

<Use of polarizing plate>
The polarizing plate of the present invention is bonded to a liquid crystal cell via the above-mentioned pressure-sensitive adhesive layer, and a liquid crystal panel in which the polarizing plate is bonded to the liquid crystal cell is provided in the liquid crystal display device. In this case, the polarizing plate of the present invention is bonded to the back side or the front side of the liquid crystal cell, or to both the back side and the front side. In this way, the liquid crystal display device includes the liquid crystal panel in which the polarizing plate of the present invention is bonded to the liquid crystal cell, so that the liquid crystal display device has sufficient mechanical strength while supporting the thinning, and further the back surface of the liquid crystal panel By disposing the polyethylene terephthalate film side of the polarizing plate of the present invention on the side, contact between the liquid crystal panel and the backlight system can be prevented. In such a liquid crystal display device, an appropriate configuration of a conventionally known liquid crystal display device can be adopted, and the configuration requirements (light diffusing plate, backlight, etc.) that the liquid crystal display device normally has other than the liquid crystal panel are particularly limited. You can prepare without doing.

  The above-mentioned light diffusion plate is an optical member having a function of diffusing light from a backlight. For example, a light diffusion agent is provided by dispersing particles as a light diffusion agent in a thermoplastic resin. In addition, the surface of the thermoplastic resin plate is formed with irregularities to impart light diffusivity, the surface of the thermoplastic resin plate is provided with a resin composition coating layer in which particles are dispersed, and the light diffusibility is imparted. Used. The thickness of the light diffusion plate is not particularly limited, but is preferably in the range of 0.1 to 5 mm. Further, between the light diffusion plate and the liquid crystal panel, a prism sheet (also called a condensing sheet, such as BEF (manufactured by 3M), etc.), a brightness enhancement sheet (same as the above-described reflective polarizing film). It is also possible to dispose a sheet exhibiting other optical functionality, such as a light diffusion sheet (such as DBEF described above). A plurality of types of sheets exhibiting other optical functionalities can be arranged as necessary. Further, as the light diffusing plate, for example, a light diffusing function such as a laminated integrated product of a prism sheet having a cylindrical shape on the surface and a light diffusing plate (for example, those described in JP-A-2006-284497) It is also possible to use an optical sheet in which other functions are combined.

  Thus, the polarizing plate of the present invention is suitably used in the constitution of backlight / light diffusing plate / light diffusing sheet / brightness improving sheet / polarizing plate / liquid crystal cell / polarizing plate. The “rear side” of the liquid crystal cell and liquid crystal panel described above means the backlight side when the liquid crystal panel is mounted on the liquid crystal display device, and the “front side” of the liquid crystal cell and liquid crystal panel means the liquid crystal panel. Means the viewing side when mounted on a liquid crystal display device.

<Outer peripheral edge of polarizing plate and method for manufacturing polarizing plate>
A polarizing plate is usually manufactured in the form of a roll material or a sheet material having a large shape, and in order to obtain a polarizing plate having a desired shape and transmission axis, a cutting tool having a sharper blade is used. It is cut (chip cut). For this reason, in the polarizing plate chip (polarizing plate having a sheet shape) obtained by cutting, a state in which the polarizing film is exposed to the outside at the outer peripheral end portion occurs.

  In FIG. 1, a polyethylene terephthalate film is laminated on one side of a polarizing film made of a polyvinyl alcohol resin and adsorbed and oriented with iodine through an adhesive layer, and transparent on the other side through an adhesive layer. A polarizing plate in which a cycloolefin-based resin film (norbornene-based resin film, “ZEONOR FILM” manufactured by Optes Co., Ltd.), which is a resin film, is laminated, and an acrylic pressure-sensitive adhesive layer is formed on the outside of the transparent resin film The photomicrograph of the outer peripheral edge part (cut surface) of the state cut | disconnected with the super cutter was shown. The boundary and composition of each layer at this time are displayed on the outer side of the photograph with an extension line and characters of the layer boundary. “PET” represents a polyethylene terephthalate film, “PVA” represents a polarizing film, “COP” represents a cycloolefin-based resin film (transparent resin film), and “adhesive” represents an adhesive layer. In this photograph, the boundary of each layer can be clearly identified, and it can be seen that the polarizing film is exposed at the outer peripheral edge. In the present invention, the outer peripheral end of the polarizing plate refers to a cut surface (outer peripheral end surface) generated when the polarizing plate is produced as described above. There are a total of 4) peripheral edges.

  When the polarizing plate chip in this state is subjected to a durability test such as a heat shock test, the commonly used polarizing plate, that is, both surfaces of the polarizing film are made of the same kind of resin film (for example, a cellulose resin film). Compared with the protected polarizing plate, defects such as peeling and cracking tend to occur.

  In contrast, FIG. 2 shows a photomicrograph of the outer peripheral end (cut surface) in a state where the outer peripheral end is continuously cut by the fly-cut method from the state of FIG. The layer structure at this time is the same as in FIG. 1, and the lower side of the figure is a polyethylene terephthalate film and the upper side of the figure is an adhesive layer, but it is difficult to identify each layer (ie, the polarizing film is not exposed). . This is because, for example, the polarizing film and the layers of the cycloolefin resin film and the polyethylene terephthalate film arranged on both sides thereof are relatively hard, so that they can be scraped cleanly by cutting, but the viscoelastic and soft adhesive layer is completely It is presumed that the film was not scraped off and hung down to the polarizing film side, or chips of the adhesive layer adhered to cover the end face of the polarizing film. In this state, it was found that defects such as peeling and cracking are less likely to occur even when subjected to a durability test such as a heat shock test as described above.

  As described above, in the present invention, from the viewpoint of the production method of the polarizing plate, a polyethylene terephthalate film is laminated on one side of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and an adhesive is placed on the other side. A transparent resin film is laminated through the layers, and the polarizing plate in the state thus laminated is chip-cut, and then the outer peripheral edge is cut. As a method for cutting the outer peripheral end, for example, as disclosed in Patent Document 4 (Japanese Patent Laid-Open No. 2001-54845), a method of cutting the outer peripheral end of the polarizing plate with a rotary blade, As disclosed in the above-mentioned Patent Document 5 (Japanese Patent Laid-Open No. 2003-220512), a method of continuously cutting the outer peripheral edge of the polarizing plate by a fly-cut method is preferably employed. It seems that the components of the adhesive layer uniformly cover the outer peripheral end by cutting the outer peripheral end surface by such a method, but this prevents the polarizing film from being exposed to the outside. Can do. Therefore, as a more preferable production method of the polarizing plate of the present invention, an adhesive layer is further formed on the outside of the transparent resin film, and thus the polarizing plate in a state where the adhesive layer is formed is chip-cut, and then the outer periphery thereof. A method of cutting the end portion can be mentioned.

  In addition, from the standpoint of the polarizing plate itself, the polarizing film exposed to the outside at the outer peripheral end in a chip-cut state is not exposed by subsequent processing. That is, the outer peripheral edge of the polarizing plate of the present invention is formed in a state where the polarizing film is not exposed. By adopting such a configuration, it is possible to suppress problems in durability tests such as a heat shock test. In order to prevent the polarizing film from being exposed at the outer peripheral end of the polarizing plate, a method of cutting the outer peripheral end as described above is effective. In the above description, it was estimated that the constituent components of the pressure-sensitive adhesive layer covered the polarizing film at the outer peripheral edge by this cutting process, so that the polarizing film was not exposed. The means for not exposing the surface of the polarizing film is not limited to this, and includes, for example, a mode in which chips of a layer (film) other than the pressure-sensitive adhesive layer cover the end face of the polarizing film.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

<Example 1>
(A) Production of Polarizing Film A polyvinyl alcohol film having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was immersed in pure water at 30 ° C., and then the weight of iodine / potassium iodide / water It was immersed at 30 ° C. in an aqueous solution having a ratio of 0.02 / 2/100. Then, it was immersed at 56.5 ° C. in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100. Subsequently, the film was washed with pure water at 8 ° C. and then dried at 65 ° C. to obtain a polarizing film made of a polyvinyl alcohol resin in which iodine as a dichroic dye was adsorbed and oriented. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

(B) Production of Polarizing Plate On one surface of the polarizing film obtained as described above, a polyethylene terephthalate film with a thickness of d _{PET of} 37 μm (in-plane retardation value R _PET : 1900 nm, maximum value of strain on the orientation main axis: 4 degrees, MOR: 2.0) was subjected to corona treatment on the bonding surface, and then bonded and bonded through an adhesive layer made of an epoxy-based photocurable adhesive.

Next, an optical compensation film (in-plane retardation value) made of a stretched norbornene resin having a thickness of 73 μm as a cycloolefin resin film, which is a transparent resin film, on the surface opposite to the side on which the polyethylene terephthalate film of the polarizing film is laminated. R ₀ : 63 nm, thickness direction retardation value R _th : 225 nm) is subjected to corona treatment on the bonding surface, and then bonded through an adhesive layer made of an epoxy-based photocurable adhesive. I got a plate. Thereafter, the polarizing plate obtained above was cured at 40 ° C. for 7 days. Furthermore, it was set as the polarizing plate with an adhesive by forming an acrylic adhesive layer in the outer side of the said transparent resin film (norbornene-type resin film) of this polarizing plate.

(C) Chip cut of polarizing plate The polarizing plate with the adhesive prepared above was cut into chips of 41 cm × 30 cm with a super cutter (manufactured by Hadano Seiki Seisakusho), and then the cut surface ( A chip-cut polarizing plate whose end face was polished was obtained by continuously cutting the outer peripheral edge) with an apparatus described in JP-A No. 2003-220512 (Patent Document 5). When the outer peripheral edge of the polarizing plate was observed with a microscope having a magnification of 500 times, the polarizing film was not exposed, and it was difficult to distinguish the polarizing film layer.

(D) Heat shock test The polarizing plate (chip cut polarizing plate) obtained as described above was bonded to glass on the pressure-sensitive adhesive layer side, and the pressure was 5 kg / cm ² (about 0.5 MPa in an autoclave at 50 ° C. ) For 20 minutes. The polarizing plate thus bonded to the glass was subjected to a heat shock test that was repeated 300 times, with the process of holding at -35 ° C for 1 hour and holding at 70 ° C for 1 hour as one cycle. As a result, no crack occurred at the end of the polarizing plate.

<Comparative Example 1>
The adhesive-attached polarizing plate produced by the same method as in Example 1 (A) and (B) was cut with a super cutter (manufactured by Hadano Seiki Co., Ltd.) to obtain a chip-cut polarizing plate. When the heat shock test was performed under the same conditions as in Example 1 (D) by directly bonding the chip-cut polarizing plate to glass on the pressure-sensitive adhesive layer side without polishing the end face, a probability of 6/10 was obtained. Cracks occurred at the ends of the polarizing plate (that is, 6 polarizing plates out of 10 polarizing plates).

<Example 2>
(B-2) Production of Polarizing Plate A polyethylene terephthalate film having a thickness d _{PET of} 37 μm (in-plane retardation value R _PET : 1900 nm, orientation on one surface of a polarizing film produced by the same method as in (A) of Example 1 The maximum value of distortion of the main shaft: 4 degrees, MOR: 2.0) was subjected to corona treatment on the bonding surface, and then bonded and bonded through an adhesive layer made of an epoxy-based photocurable adhesive. .

  Next, on the surface opposite to the side on which the polyethylene terephthalate film of the polarizing film is laminated, a film having a thickness of 80 μm made of triacetyl cellulose subjected to saponification treatment as a cellulose resin film that is a transparent resin film, After the corona treatment was performed on the bonding surface, a polarizing plate was obtained by bonding through an adhesive layer made of an epoxy-based photocurable adhesive. Thereafter, it was cured at 40 ° C. for 7 days. Furthermore, it was set as the polarizing plate with an adhesive by forming an acrylic adhesive layer in the outer side of the said transparent resin film (triacetyl cellulose film) of this polarizing plate.

(C-2) Chip cut of polarizing plate The polarizing plate with the adhesive prepared above was cut into a size of 41 cm × 30 cm with a super cutter (manufactured by Hadano Seiki Seisakusho), and then cut. A chip-cut polarizing plate whose end face was polished was obtained by continuously cutting the surface (outer peripheral edge) with an apparatus described in JP-A-2003-220512 (Patent Document 5). When the outer peripheral edge of the polarizing plate was observed with a microscope having a magnification of 500 times, the polarizing film was not exposed, and it was difficult to distinguish the polarizing film layer.

(D-2) Heat Shock Test The polarizing plate (chip-cut polarizing plate) obtained as described above was bonded to glass on the pressure-sensitive adhesive layer side, and the pressure was 5 kg / cm ² (about 0) in a 50 ° C. autoclave. .5 MPa) for 20 minutes. The polarizing plate thus bonded to the glass was subjected to a heat shock test that was repeated 300 times, with the process of holding at -35 ° C for 1 hour and holding at 70 ° C for 1 hour as one cycle. As a result, no crack occurred at the end of the polarizing plate.

<Comparative example 2>
The adhesive-attached polarizing plate produced by the same method as (B-2) of Example 2 was cut with a super cutter (manufactured by Hadano Seiki Seisakusho Co., Ltd.) to obtain a chip-cut polarizing plate. The chip-cut polarizing plate was subjected to a heat shock test under the same conditions as in (D-2) of Example 2 by bonding it to glass on the pressure-sensitive adhesive layer side without polishing the end face. The crack occurred at the end of the polarizing plate with the probability (that is, three polarizing plates out of 10 polarizing plates).

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a microscope picture of the outer periphery edge part (cut surface) of the state which cut | disconnected the polarizing plate with the super cutter. It is a microscope picture of the outer periphery edge part (cut surface) of the state which cut | disconnected the polarizing plate with the super cutter, and was further cut by the fly cut method.

Claims (8)

  A polarizing plate in which a polyethylene terephthalate film is laminated on one surface of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and a transparent resin film is laminated on the other surface via an adhesive layer, The polarizing plate is characterized in that an outer peripheral end portion of the polarizing plate is formed in a state where the polarizing film is not exposed.   The transparent resin film is a transparent resin film selected from a cycloolefin resin film, a cellulose resin film, a polycarbonate resin film, a polyolefin resin film, a polyester resin film, and an acrylic resin film. Polarizing plate.   The polarizing plate of Claim 1 or 2 with which the adhesive layer is formed in the outer side of the said transparent resin film.   The polarizing plate according to claim 1, wherein the adhesive layer contains a photocurable adhesive as an adhesive.   A polyethylene terephthalate film is laminated on one side of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and a transparent resin film is laminated on the other side via an adhesive layer. A method for producing a polarizing plate, comprising: cutting a chip of the polarizing plate and then cutting an outer peripheral end portion thereof.   The transparent resin film is a transparent resin film selected from a cycloolefin resin film, a cellulose resin film, a polycarbonate resin film, a polyolefin resin film, a polyester resin film, and an acrylic resin film. Manufacturing method of this polarizing plate.   The polarized light according to claim 5 or 6, wherein an adhesive layer is formed on the outer side of the transparent resin film, and the polarizing plate in a state where the adhesive layer is thus formed is chip-cut, and then the outer peripheral edge is cut. A manufacturing method of a board.   The said adhesive bond layer is a manufacturing method of the polarizing plate in any one of Claims 5-7 containing a photocurable adhesive agent as an adhesive agent.