JP2009175685A - Polarizing plate and liquid crystal display device using the same - Google Patents

Abstract

An object of the present invention is to provide a high mechanical strength even if it is thin, to reinforce the strength of the liquid crystal panel, to reduce the warpage of the liquid crystal panel, and to prevent the generation of static electricity in the process of bonding to the liquid crystal panel. Provided is a polarizing plate with a high product yield and a liquid crystal display device using the same, which suppresses color unevenness when observed obliquely and has excellent visibility.
A polarizing film comprising a polyvinyl alcohol resin and a stretched polyethylene terephthalate film laminated on one side of the polarizing film, comprising a polarizing plate containing an antistatic agent, and a stretched polyethylene terephthalate film of the polarizing film are laminated. A liquid crystal display device comprising a liquid crystal panel in which a polarizing plate of the present invention further having a pressure-sensitive adhesive layer on the outer surface opposite to the formed side is bonded to a liquid crystal cell via the pressure-sensitive adhesive layer.
[Selection figure] None

Description

  The present invention relates to a polarizing plate in which a stretched polyethylene terephthalate film is laminated on one side of a polarizing film made of a polyvinyl alcohol resin, and a liquid crystal display device using the polarizing plate.

  A polarizing plate is usually a protective film (for example, cellulose acetate typified by triacetyl cellulose) through an adhesive layer on one side or both sides of a polarizing film made of a polyvinyl alcohol resin to which a dichroic dye is adsorbed and oriented. System protective film). A polarizing plate having such a laminated structure is bonded to a liquid crystal cell with an adhesive via another optical film as necessary, and is used as a component of a liquid crystal display device.

  Applications of liquid crystal display devices are rapidly expanding as thin display devices such as liquid crystal televisions, liquid crystal monitors, and personal computers. In particular, the market for liquid crystal televisions is remarkably expanding, and the demand for cost reduction is very high. A polarizing plate for a liquid crystal television is usually formed by laminating a triacetyl cellulose film (TAC film) with a water-based adhesive on both sides of a polarizing film made of a polyvinyl alcohol resin to which a dichroic dye is adsorbed and oriented. A retardation film is laminated on the outer surface of one side of the plate via an adhesive.

  As the retardation film laminated on the polarizing plate, a stretched product of a polycarbonate-based resin film or a stretched product of a cycloolefin-based resin film is used. Retardation films composed of very few cycloolefin resin films are frequently used. The laminated product of such a polarizing plate and a retardation film made of a cycloolefin resin film reduces the number of components or simplifies the manufacturing process in order to improve productivity and reduce product cost. For example, JP-A-8-43812 (Patent Document 1) discloses a laminated structure of a cycloolefin-based (norbornene-based) resin film / polarizing film / TAC film having a retardation function. Yes.

JP-A-2005-70140 (Patent Document 2), JP-A-2005-181817 (Patent Document 3) and JP-A-2005-208456 (Patent Document 4) describe polarized light made of a polyvinyl alcohol resin. It is described that a film and a cycloolefin-based protective film are bonded with a urethane-based aqueous adhesive.
JP-A-8-43812 JP-A-2005-70140 JP 2005-181817 A JP-A-2005-208456

  In the use of large-screen liquid crystal televisions, the needs for wall-mounted televisions are becoming thinner, and in this case, the following points are problems as components used for liquid crystal panels.

(1) It is necessary to reinforce the strength of the panel in response to the thin and large screen of the liquid crystal panel.
(2) It is necessary to reduce the thickness of members used in response to the reduction in the thickness of liquid crystal televisions.
(3) The gap between the liquid crystal panel and the backlight system on the back surface is narrowed, and it is necessary to prevent circular unevenness and Newton's ring caused by contact between the liquid crystal panel and the backlight system.

  In order to solve the above problems, it is conceivable to use a stretched polyethylene terephthalate film which is excellent in mechanical strength and cost of the film as a protective film for the polarizing plate. However, since the stretched polyethylene terephthalate film is easily charged, static electricity is likely to be generated in the process of bonding the polarizing plate to the liquid crystal panel, and the orientation of the liquid crystal in the liquid crystal panel is disturbed, or the semiconductor is destroyed and normal display is achieved. Problems such as being unable to do so.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to provide high mechanical strength even when thin, to reinforce the strength of the liquid crystal panel, and to warp the liquid crystal panel. Small, and can prevent the generation of static electricity in the process of bonding to the liquid crystal panel, and the polarizing plate has a high product yield, and the liquid crystal display device using this polarizing plate also has uneven color when observed from an oblique direction. An object of the present invention is to provide a liquid crystal display device that is suppressed and has excellent visibility.

  As a result of intensive studies to solve such problems, the inventors have made a structure in which a stretched polyethylene terephthalate film is laminated on one side of a polarizing film made of a polyvinyl alcohol-based resin, and further include an antistatic agent. Thus, the present inventors have found that a polarizing plate can be obtained that has a high mechanical strength even when it is thin and can prevent the generation of static electricity. That is, the present invention is as follows.

  The polarizing plate of the present invention has a structure in which a polarizing film made of a polyvinyl alcohol resin and a stretched polyethylene terephthalate film are laminated, and includes an antistatic agent.

  The polarizing plate of the present invention preferably further includes a protective film or an optical compensation film laminated on the side opposite to the side on which the stretched polyethylene terephthalate film of the polarizing film is laminated.

  The polarizing plate of the present invention preferably further has a pressure-sensitive adhesive layer on the outer surface of the polarizing film opposite to the side on which the stretched polyethylene terephthalate film is laminated.

In the polarizing plate of the present invention, the pressure-sensitive adhesive layer preferably contains an antistatic agent.
In the polarizing plate of the present invention, it is preferable that the surface of any film constituting the polarizing plate is coated with a layer containing an antistatic agent.

  The present invention also provides a liquid crystal display device including a liquid crystal panel in which the polarizing plate of the present invention is bonded to a liquid crystal cell via an adhesive layer.

  The polarizing plate of the present invention can achieve improvement of mechanical strength, thinning and prevention of warpage of the applied liquid crystal panel, and the liquid crystal display device using such a polarizing plate of the present invention has a high yield, Color unevenness due to the retardation of the stretched polyethylene terephthalate film is also suppressed, and can be suitably applied to a liquid crystal display device for large-screen liquid crystal televisions, particularly a liquid crystal display device for liquid crystal televisions that can be wall-mounted.

  Specifically, the polarizing film used in the polarizing plate of the present invention is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film. The polyvinyl alcohol-based resin can be obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers copolymerizable therewith, such as ethylene-vinyl acetate copolymer, etc. Is mentioned. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. These polyvinyl alcohol resins may be modified. For example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes may be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is in the range of 1000-10000 normally, Preferably it exists in the range of 1500-5000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known appropriate method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 10-150 micrometers.

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

  In the production of the polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched, but this uniaxial stretching may be performed before the dyeing treatment step or during the dyeing treatment step, It may be performed after the dyeing process. When uniaxial stretching is performed after the dyeing treatment step, the uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, uniaxial stretching can be performed in these plural stages. Uniaxial stretching may be performed uniaxially between rolls having different peripheral speeds, or may be performed uniaxially using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 3 to 8 times.

  Dyeing of the polyvinyl alcohol resin film with the dichroic dye in the dyeing process is performed, for example, by immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine, a dichroic dye or the like is used. Examples of dichroic dyes include C.I. I. Dichroic direct dyes composed of disazo compounds such as DIRECT RED 39 and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo are included. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

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

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

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

  In the subsequent washing process, the polyvinyl alcohol-based resin film after the boric acid treatment described above is washed with water, for example, by immersing it in water. The water temperature in the water washing treatment is usually 5 to 40 ° C., and the immersion time is usually 1 to 120 seconds. After the water washing treatment, a drying treatment is usually performed to obtain a polarizing film. The drying process is preferably performed using, for example, a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually 30 to 100 ° C, preferably 50 to 80 ° C. The time for the drying treatment is usually 60 to 600 seconds, preferably 120 to 600 seconds.

  In this way, the polyvinyl alcohol resin film is uniaxially stretched, dyed with a dichroic dye, treated with boric acid and washed with water to obtain a polarizing film. The thickness of this polarizing film is usually in the range of 5 to 40 μm. The polarizing plate of the present invention has a structure in which a stretched polyethylene terephthalate film is laminated on one side of such a polarizing film.

  The stretched polyethylene terephthalate film used in the present invention is a film excellent in mechanical properties, solvent resistance, scratch resistance, cost, etc. The polarizing plate of the present invention using such a stretched polyethylene terephthalate film is a mechanical In addition to excellent strength and the like, the thickness can be reduced. Whether or not the polyethylene terephthalate film used for the polarizing plate is stretched can be confirmed by, for example, a retardation value in the film plane.

  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 glycol 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 glycol 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 component 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 stretched 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. By performing the stretching treatment in this manner, the mechanical strength of the polyethylene terephthalate film can be increased. 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 heat setting after mechanical stretching at temperature can be mentioned. The stretching treatment applied to polyethylene terephthalate may be uniaxial stretching or biaxial stretching.

  Although the temperature at the time of extending | stretching will not be restrict | limited especially if it is the temperature more than the glass transition temperature of a polyethylene terephthalate, It is preferable to exist in the range of 80-130 degreeC, and it is more preferable to be in the range of 90-120 degreeC. preferable.

  In addition, the stretch ratio of the stretched polyethylene terephthalate film in the present invention is preferably 1.1 to 6 times, more preferably 3 to 5.5 times in the longitudinal direction and the width direction of the film. This is because when the draw ratio is less than 1.1 times, the stretched polyethylene terephthalate film tends not to exhibit sufficient transparency.

  In addition, from the viewpoint of reducing distortion of the orientation main axis in the stretched polyethylene terephthalate film (displacement relative to the stretch axis), the film is subjected to the longitudinal direction (the running direction of the film) after the stretching and before the heat setting treatment, It is preferable to perform relaxation treatment in the width direction of the film (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 relaxation amount varies depending on the transverse stretching conditions, it is preferable to set the relaxation amount and the temperature so that the heat-shrinkage rate at 150 ° C. of the stretched 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 treatment, first, after performing the heat setting treatment 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 stretched polyethylene terephthalate film after the relaxation treatment is 1 to 10%, more preferably 2 to 5%.

  In the stretched polyethylene terephthalate film used in the present invention, the misalignment angle of the orientation main axis with respect to the stretching direction (maximum strain of the orientation main axis) is 30 degrees or less (preferably 10 degrees or less, more preferably 5 degrees or less). One of the features. When the maximum value of the distortion of the orientation main axis is larger than 30 degrees, a sufficient color unevenness suppressing effect cannot be obtained when pasted on the screen of the liquid crystal display device. Further, the lower limit of the maximum value of the distortion of the orientation main axis of the stretched polyethylene terephthalate film is not particularly limited, but is preferably 0 degree 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 of the stretched polyethylene terephthalate film used in the present invention is preferably in the range of 20 to 60 μm, and more preferably in the range of 30 to 50 μm. When the thickness d _PET of the stretched 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 decrease. is there.

  The stretched 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 further preferably 2.2 or more. Preferably, it is 3.0 or more. This is because when a polarizing plate using a stretched 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 stretched 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 a 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).

The in-plane retardation value R _PET of the stretched 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 is less than 1000 nm, coloring from the front tends to be conspicuous. The in-plane retardation value R _PET of the stretched 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 is the refractive index in the in-plane slow axis direction of the oriented polyethylene terephthalate film, n _b is perpendicular to the plane fast axis direction (in-plane slow axis direction of the oriented polyethylene terephthalate film Direction), d _PET is the thickness of the stretched polyethylene terephthalate film.)
The polyethylene terephthalate film used in the present invention may be provided with an easy adhesion layer. The method for forming the polyethylene terephthalate film provided with the easy-adhesion layer is not particularly limited. For example, a method for forming an easy-adhesion layer on a film that has undergone all the stretching steps, A method of forming an easy-adhesion layer during the step, that is, between the longitudinal stretching step and the lateral stretching step, a method of forming an easy-adhesion layer 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 an easy-adhesion layer is formed after longitudinal stretching of polyethylene terephthalate and then lateral stretching is preferably employed. The easy adhesion layer can be applied to both surfaces of the polyethylene terephthalate film or to one surface bonded to a polarizing film made of a polyvinyl alcohol resin via an adhesive.

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

  Further, the stretched polyethylene terephthalate film used in the present invention may be provided with antiglare properties (haze). The method for imparting antiglare properties is not particularly limited, and is, for example, the method of mixing inorganic fine particles or organic fine particles into the raw material resin to form a film, opposite to the side of the stretched polyethylene terephthalate film on which the polarizing film is laminated. For example, a method of forming a glare-proof layer by coating a coating solution prepared by mixing inorganic fine particles or organic fine particles with a resin binder on the surface of the surface.

  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 resin is provided on the opposite side of the stretched polyethylene terephthalate film to the side on which the polarizing film is laminated via an adhesive layer or an adhesive layer. You may make it provide glare-proof property by the method of laminating | stacking the anti-glare protective film which consists of a polyester-type resin film and a polyester-type resin film. The antiglare protective film is produced 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. Can be suitably used. 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 possibility that whitening may occur and visibility may deteriorate.

  Further, the surface of the stretched polyethylene terephthalate film opposite to the side on which the polarizing film is laminated may be subjected to a surface treatment such as an antiglare treatment, a hard coat treatment, or an antistatic treatment. In addition, a coat layer made of a liquid crystalline compound or a high molecular weight compound thereof may be formed. Note that substantially the same effect can be obtained by using a stretched polyethylene naphthalate film instead of the stretched polyethylene terephthalate film.

  In the polarizing plate of the present invention, a protective film or an optical compensation film may be laminated on the side of the polarizing film opposite to the side on which the stretched polyethylene terephthalate film is laminated. Examples of the protective film or the optical compensation film include transparent films such as a cellulose resin film such as a triacetyl cellulose film (TAC film), an olefin resin film, an acrylic resin film, and a polyester resin film. Moreover, you may make it laminate | stack the optical functional film mentioned later on such a transparent film.

  The cellulose-based resin film is a film of a cellulose part or a completely esterified product, and examples thereof include a film made of cellulose acetate ester, propionate ester, butyrate ester, mixed ester thereof and the like. More specifically, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like can be given. As such a cellulose ester film, suitable commercially available products such as Fujitac TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac TD80UF (manufactured by Fuji Film Co., Ltd.), Fujitac TD80UZ (manufactured by Fuji Film Co., Ltd.), KC8UX2M (Manufactured by Konica Minolta Opto), KC8UY (manufactured by Konica Minolta Opto), and the like.

  Moreover, as an optical compensation film comprising a cellulose resin film, for example, a film in which a compound having a retardation adjusting function is contained in a cellulose film, a film in which a compound having a retardation adjusting function is applied to the surface of the cellulose film, a cellulose film Examples thereof include a film obtained by uniaxially stretching or biaxially stretching a film. Moreover, in the polarizing plate of this invention, the cellulose acetate type-resin film provided with the phase difference characteristic is also used suitably, As a commercial item of the cellulose acetate type-resin film provided with this phase difference characteristic, WV BZ 438 ( FUJIFILM Co., Ltd.), WV EA (Fuji Film Co., Ltd.), KC4FR-1 (Konica Minolta Opto Co., Ltd.), KC4HR-1 (Konica Minolta Opto Co., Ltd.), and the like.

  Alternatively, the cycloolefin resin film may be uniaxially stretched or biaxially stretched to form an optical compensation film. The cycloolefin resin film is a film made of a thermoplastic resin having a monomer unit made of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer. The cycloolefin-based film may be a hydrogenated product of a ring-opening polymer using a single cycloolefin or a ring-opening copolymer using two or more kinds of cycloolefins. It may also be an addition copolymer with an aromatic compound having a vinyl group. Further, those having a polar group introduced into the main chain or side chain are also effective.

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

  Cycloolefin-based resins may be commercial products such as Topas (manufactured by Ticona), Arton (manufactured by JSR Corporation), ZEONOR (manufactured by Nippon Zeon Co., Ltd.), ZEONEX (manufactured by Nippon Zeon Corporation). ) And Apel (Mitsui Chemicals) can be preferably used. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, for example, Essina (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa Film (manufactured by Optes Co., Ltd.), Arton Film (manufactured by JSR Co., Ltd.), etc. A commercially available cycloolefin resin film may be used as the transparent protective film.

The cycloolefin-based resin film as the optical compensation film is desirably stretched in at least one direction. 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 exceeds 300 nm, the viewing angle compensation ability for the 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 (2) and (3), respectively, for example, KOBRA 21ADH (Oji Scientific Instruments ( It is possible to measure using

_{R 0 = (n x -n y} ) × d (2)
R _th = [( _nx + _ny ) / 2- _nz ] × d (3)
(The above formula (2), (in 3), 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.)
The preferable refractive index characteristics as described above include various adjustments such as preheating temperature during stretching, stretching temperature, heat setting (film strain reduction treatment after stretching) temperature, cooling temperature, etc. in addition to appropriately adjusting the stretching ratio and stretching speed. It can be applied by appropriately selecting the temperature (including the temperature pattern). By performing stretching under relatively loose conditions, the above preferable refractive index characteristics can be obtained. For example, the stretching ratio is preferably 1.05 to 1.6, and more preferably 1.1 to More preferably, it is 1.5 times. In the case of biaxial stretching, the stretching ratio in the maximum stretching direction may be in the above range.

  If the stretched cycloolefin-based resin film is too thick, the processability becomes inferior, and problems such as a decrease in transparency and an increase in the weight of the polarizing plate tend to occur. Therefore, the thickness of the stretched cycloolefin-based resin film is preferably in the range of 40 to 80 μm.

  The present invention provides a polarizing plate containing an antistatic agent while having a structure in which a stretched polyethylene terephthalate film is laminated on one side of a polarizing film as described above. The polarizing plate of the present invention is preferably realized to contain an antistatic agent by forming a coating layer containing an antistatic agent on the surface of any film constituting the polarizing plate. Here, examples of the film constituting the polarizing plate include a stretched polyethylene terephthalate film, a protective film, and an optical compensation film. In this case, as the coating layer, a layer obtained by curing an ultraviolet curable resin composition containing (A) polyfunctional (meth) acrylate, (B) photopolymerization initiator and (C) antistatic agent is suitably used. However, the present invention is not limited to this, and examples thereof include a layer obtained by applying a mixed coating solution of a water-soluble resin such as a polyvinyl alcohol resin and a water-soluble antistatic agent and then drying and curing.

  The (A) polyfunctional (meth) acrylate suitably used for forming the coating layer is a compound having at least two (meth) acryloyloxy groups in one molecule. In the polyfunctional (meth) acrylate, the number of (meth) acryloyloxy groups in one molecule is usually up to about 9, and particularly when the number of (meth) acryloyloxy groups is 3 or more in one molecule, This is preferable because the hardness of the cured film tends to be improved.

  Specific examples of the polyfunctional (meth) acrylate include 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, glycerin di (meth) acrylate, glycerin methacrylate acrylate, trimethylolpropane di (meth) ) Bifunctional compounds such as acrylate, glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) Trifunctional compounds such as acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) Tetrafunctional compounds such as acrylates, further dipentaerythritol penta (meth) acrylate, 5 or more functional compounds such as dipentaerythritol hexa (meth) acrylate. These can be used alone or in combination of two or more.

  Polyfunctional (meth) acrylate is produced by, for example, a dehydration condensation reaction between a polyhydric alcohol and (meth) acrylic acid in the presence of an acid catalyst such as p-toluenesulfonic acid and a polymerization inhibitor such as hydroquinone monomethyl ether. Can do. More specifically, a polyhydric alcohol, (meth) acrylic acid, an acid catalyst and a polymerization inhibitor are mixed in an organic solvent, and the solid content concentration is 30 wt% or more, preferably 30 to 60 wt%. After preparing the liquid, the temperature was raised to the reflux temperature while stirring, the temperature was kept in that state, and the reaction was terminated when the amount of water produced reached 90 to 100% of the theoretical amount. It can manufacture by performing a sum treatment and a solvent removal treatment.

  The (B) photopolymerization initiator suitably used for forming the coating layer may be any one that initiates a radical reaction upon irradiation with ultraviolet rays. Specific examples include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (such as Lucilin TPO (manufactured by BASF)), 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 (Ciba・ Specialty Chemicals Co., Ltd.), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (Irgacure 907 (manufactured by Ciba Specialty Chemicals Co., Ltd.) ) Etc.). In particular, when the polyvinyl alcohol resin or polyethylene terephthalate film to which the ultraviolet curable resin composition is applied contains an ultraviolet absorber, ultraviolet rays are irradiated through the transparent substrate containing the ultraviolet absorber, so that the visible region is visible. Further, a phosphorus-based photopolymerization initiator having absorption is also preferably used.

  Such (B) photoinitiator is 0.01-30 weight part with respect to the ultraviolet curable resin composition used suitably for formation of a coating layer, Preferably it is 0.01-10 weight part. (B) When the content of the photopolymerization initiator is less than 0.01 part by weight, the uncured part tends to increase, and when it exceeds 30 parts by weight, the molecular weight of the polymer increases. This is because the film quality tends to become brittle.

  Examples of the antistatic agent (C) preferably used for forming the coating layer include conductive substances such as metal oxides and conductive polymers, and ionic compounds such as surfactants and ion conductive polymers. Examples of the metal oxide include conductive double oxide sols such as antimony oxide, zinc antimonate, antimony tin oxide, titanium antimony oxide, titanium tin oxide, phosphorus tin oxide, and zinc aluminum. Examples of the conductive polymer include polythiophene, polyacetylene, polyvinylene, and polyphenylene.

Further, (C) the antistatic agent has an antistatic performance of the obtained polarizing plate, and has a surface resistance value of 10 ¹¹ Ω / □ order or less when the separator protecting the pressure-sensitive adhesive layer is peeled off. The coating layer is formed as described above, and when the coating layer is formed as described above, in the ultraviolet curable resin composition suitably used for forming the coating layer, (A) polyfunctional (meta ) It is preferably 0.05 to 80 parts by weight, more preferably 0.5 to 80 parts by weight with respect to 100 parts by weight of acrylate. (C) When the content of the antistatic agent is less than 0.05 parts by weight with respect to 100 parts by weight of the (A) polyfunctional (meth) acrylate, there is a tendency that sufficient antistatic ability does not appear. (A) When it exceeds 80 weight part with respect to 100 weight part of polyfunctional (meth) acrylate, it exists in the tendency for film forming to become difficult. In addition, the surface resistance value of the polarizing plate mentioned above points out the value measured using the surface specific resistance measuring apparatus Hirest-up MCP-HT450 (made by Mitsubishi Chemical Corporation).

  On the surface of any film constituting the polarizing plate, the ultraviolet curable resin composition containing (A) polyfunctional (meth) acrylate, (B) photopolymerization initiator, and (C) antistatic agent as described above. The coating film is subjected to a drying treatment if necessary, and then the coating film is irradiated with ultraviolet rays and cured to form a coating layer containing an antistatic agent. Although the thickness of a coating layer is not specifically limited, It is preferable that it is 0.01-30 micrometers. This is because when the thickness of the coating layer is less than 0.01 μm, sufficient antistatic ability tends not to be exhibited, and when it exceeds 30 μm, the film quality tends to become brittle.

Although the wavelength range of the ultraviolet rays with which the coating film of the ultraviolet curable resin composition is irradiated is not particularly limited, it is suitably in the range of about 320 to 450 nm. Dose at that time is preferably 100 to 2000 mJ / cm ^2, more preferably 500 mJ / cm ² or more. In particular, two continuous ultraviolet irradiations are preferable, and the total irradiation amount is preferably in the above range.

  As a light source for ultraviolet irradiation, a high-pressure mercury lamp, a metal halide lamp, or the like can be used. However, when the transparent substrate contains an ultraviolet absorber, a metal halide lamp that contains a large amount of visible light components is preferably used. A V bulb (manufactured by Fusion) or the like is also preferably used as an ultraviolet light source containing a large amount of visible light components. In addition, when performing continuous ultraviolet irradiation twice, the light source used for the second irradiation does not need to have many visible light components, for example, a D bulb (made by Fusion) etc. is mentioned as a suitable thing.

  In the polarizing plate of the present invention, as a method of laminating a stretched polyethylene terephthalate film and / or a transparent film on the surface of the polarizing film, a method of adhering using an adhesive is usually employed. From the viewpoint of thinning the adhesive layer, the adhesive used for laminating these films includes an aqueous one, that is, an adhesive component dissolved in water or dispersed in water. . For example, a composition using a polyvinyl alcohol resin or a urethane resin as a main component can be mentioned as a preferred adhesive. In addition, when bonding a film on both surfaces of a polarizing film, the same kind of adhesive agent may be used and a different kind of adhesive agent may be used, respectively.

  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.

  It is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin and a crosslinking agent to the adhesive composed of an aqueous solution of a polyvinyl alcohol resin in order to increase the adhesiveness. 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 component and crosslinking agent (when added together, the total amount) is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. . When the addition amount of the curable component and 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, and the curable component, 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 ionomer type urethane resins are known per se. For example, JP-A-7-97504 describes an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium. In JP-A-2005-70140 (Patent Document 2) and JP-A-2005-208456 (Patent Document 4), a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group is used as an adhesive. A form in which a cycloolefin resin film is bonded to a polarizing film made of a polyvinyl alcohol resin is shown.

  As a method of laminating the above-mentioned stretched polyethylene terephthalate film (and a protective film or an optical compensation film, if necessary) to the polarizing film, generally known methods may be used. For example, casting method, Mayer bar coat Apply an adhesive to the adhesive surface of the polarizing film and / or the film to be bonded to it by the method, gravure coating method, comma coater method, doctor blade method, die coating method, dip coating method, spraying method, etc. The method to match is mentioned. 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.

  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 into 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 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 in the polarizing plate of this invention. Examples of the photocurable adhesive include those obtained by adding a radical polymerization initiator and / or a cationic polymerization initiator to an epoxy resin, an acrylic resin, an okitacene resin, a urethane resin, a polyvinyl alcohol resin, or the like. Especially, what added the cationic polymerization type initiator to the mixture of the alicyclic epoxy resin and the epoxy resin which does not have an alicyclic structure is preferable. 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 curing time of the photo-curable adhesive are reduced. 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 when cured and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is It is preferably set to be 10 to 10,000 mJ / m ² . When the integrated light quantity to the photocurable 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 10000 mJ / m. ^{By being 2} or less, irradiation time does not become too long, and favorable 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 or more, preferably 2 μm or less, more preferably 1 μm or less.

  When curing a photo-curable adhesive by irradiation with active energy rays, various functions of the polarizing plate, such as the degree of polarization, transmittance and hue of the polarizing film, and transparency of the stretched polyethylene terephthalate film, protective film, and optical compensation film It is preferable to perform the curing under the condition that does not decrease.

  The polarizing plate of the present invention has an outer surface opposite to the side on which the stretched polyethylene terephthalate film of the polarizing film is laminated (if the protective film or the optical compensation film is laminated, the polarization of the protective film or the optical compensation film). A pressure-sensitive adhesive layer for bonding the polarizing plate to the liquid crystal cell is preferably formed on the surface opposite to the side laminated on the film. As the pressure-sensitive adhesive used in such a pressure-sensitive adhesive layer, conventionally known appropriate pressure-sensitive adhesives can be used without particular limitation. For example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. And polyvinyl ether pressure-sensitive adhesives. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, weather resistance, heat resistance, and the like. The pressure-sensitive adhesive layer can be provided by a method in which such a pressure-sensitive adhesive is used, for example, in the form of an organic solvent solution, which is applied to a base film with a die coater or a gravure coater, and dried. 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 the base 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.

  The acrylic pressure-sensitive adhesive is not particularly limited, but (meth) acrylate such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, (2-ethylhexyl (meth) acrylate) ) Acrylic ester base polymer and a copolymer base polymer using two or more of these (meth) acrylic esters are preferably used. These base polymers are copolymerized with polar monomers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Examples thereof include monomers having a polar functional group such as a carboxyl group, a hydroxyl group, an amide group, an amino group, and an epoxy group, such as acrylate and glycidyl (meth) acrylate.

  These acrylic pressure-sensitive adhesives can of course be used alone, but usually a crosslinking agent is blended. As the crosslinking agent, a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, Examples thereof include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are widely used as organic crosslinking agents.

  The energy ray curable adhesive has the property of being cured by irradiation with energy rays such as ultraviolet rays and electron beams, and has adhesiveness even before irradiation with energy rays to adhere to an adherend such as a film. It is a pressure-sensitive adhesive that has the property of being adhered and cured by irradiation with energy rays to adjust the adhesion. As the energy ray curable adhesive, it is particularly preferable to use an ultraviolet curable adhesive. The energy beam curable pressure-sensitive adhesive generally comprises an acrylic pressure-sensitive adhesive and an energy beam polymerizable compound as main components. Usually, a crosslinking agent is further blended, and if necessary, a photopolymerization initiator and a photosensitizer can be blended.

  In addition to the above base polymer and cross-linking agent, the pressure-sensitive adhesive composition includes, for example, natural products and the like in order to adjust the pressure-sensitive adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. Appropriate additives such as synthetic resins, tackifier resins, antioxidants, ultraviolet absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, photopolymerization initiators, and the like can also be blended. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.

  When the polarizing plate of the present invention has an adhesive layer as described above, the adhesive layer may contain an antistatic agent so that the polarizing plate contains an antistatic agent. . As a method for adding an antistatic agent to the pressure-sensitive adhesive layer, a method using an ion conductive composition composed of an electrolyte salt and an organopolysiloxane and a composition containing an acrylic copolymer (see, for example, Patent No. 3012860), A method of blending an organic salt-based antistatic agent (see, for example, JP-T-2004-536940), a method of containing a salt comprising a quaternary ammonium cation having 4 to 20 carbon atoms and a fluorine atom-containing anion ( For example, refer to JP 2004-114665 A) and a method of containing an ion conductive polymer.

For example, when an ion conductive composition is used for an acrylic pressure-sensitive adhesive as an antistatic agent, examples of the cation component constituting the ion conductive composition include a pyridinium cation. The pyridinium cation has a total carbon number of 8 or more, more preferably 10 or more, and particularly preferably 12 or more, from the viewpoint of compatibility with the acrylic resin. Specific examples of the pyridinium cation include N-methyl-4-hexylpyridinium cation and N-hexyl-4-methylpyridinium cation. On the other hand, it is preferable that the anion component constituting the ion conductive composition satisfies the fact that it becomes an ionic liquid, and in particular, the anion component containing a fluorine atom is capable of obtaining an ionic compound having a low melting point. And hexafluorophosphate anion [PF ₆ ⁻ ], bis (trifluoromethanesulfonyl) imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ] and the like.

  The ion conductive composition is preferably contained in a proportion of about 0.1 to 10 parts by weight, more preferably 0.2 to 3 parts by weight, especially 0.3. It is more preferable to make it contain in the ratio of -1.5 weight part. By containing 0.1 parts by weight or more of the ion conductive composition with respect to 100 parts by weight of the acrylic pressure-sensitive adhesive, it is preferable because the antistatic performance is improved.

Also in this case, the surface resistivity of the pressure-sensitive adhesive layer when the separator protecting the pressure-sensitive adhesive layer of the polarizing plate was peeled off was measured using a surface specific resistance measuring device Hirest-up MCP-HT450 (manufactured by Mitsubishi Chemical Corporation)). By using and measuring, antistatic performance can be evaluated. If the surface resistance value thus measured is on the order of 10 ¹¹ Ω / □ or less, it can be said that the antistatic performance is good.

  The pressure-sensitive adhesive layer can be provided by a method in which the above-mentioned pressure-sensitive adhesive is used, for example, in the form of an organic solvent solution, which is applied to a base film with a die coater or a gravure coater, and dried. It can also be provided by a method of transferring a sheet-like pressure-sensitive adhesive formed on a plastic film (referred to as a separate film) to a base 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.

  An optical functional film may be attached to the outer surface of the polarizing plate via the pressure-sensitive 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, A reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, a retardation film made of polycarbonate resin, a film with an antiglare function that has an uneven surface, and a surface antireflection treatment Examples thereof include an attached 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 the optical compensation film in which a liquid crystal compound is coated on the substrate surface and oriented include WV film (manufactured by FUJIFILM Corporation), NH film (manufactured by Nippon Oil Corporation), 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 that corresponds 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 retardation film which consists of cyclic polyolefin resin, for example, Arton Film (made by JSR Corporation), Essina (made by Sekisui Chemical Co., Ltd.), Zeonoor Film (made by Optes Co., Ltd.) Etc.

  When the said polarizing plate is arrange | positioned at the front side of a liquid crystal panel, you may provide the glare-proof protective film for preventing the reflection of external light in the visual recognition side outermost surface. The antiglare protective film can be produced by, for example, a method of forming a coating film containing organic fine particles or inorganic fine particles on the surface of the resin film, a method of forming a film by mixing inorganic fine particles or organic fine particles with a resin, etc. It is not limited to. Examples of the method for forming the coating film include a method in which a coating solution containing a binder component made of a curable resin composition and organic fine particles or inorganic fine particles is applied to the surface of the resin film. Examples of the resin used as the base material of the antiglare protective film include cellulose resins such as triacetyl cellulose (TAC), olefin resins, acrylic resins, polyester resins, and the like, and the polarizing plate of the present invention is used. In some cases, stretched polyethylene terephthalate may be used as the base material.

  The present invention also provides a liquid crystal display device including a liquid crystal panel in which the above-described polarizing plate of the present invention is bonded to a liquid crystal cell via an adhesive layer. 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 the back side and the front side. Such a liquid crystal display device of the present invention includes a liquid crystal panel in which the polarizing plate of the present invention is bonded to the back surface of the liquid crystal cell, and thus has sufficient mechanical strength while supporting thinning. By disposing the stretched polyethylene terephthalate film side of the polarizing plate of the present invention on the back side of the liquid crystal panel, a liquid crystal display device capable of preventing contact between the liquid crystal panel and the backlight system is provided. In the liquid crystal display device of the present invention, for the portions other than the above-described features, an appropriate configuration of a conventionally known liquid crystal display device can be adopted, and the configuration requirements (light diffusing plate) that the liquid crystal display device normally includes other than the liquid crystal panel The backlight is not particularly limited.

  The light diffusing plate is an optical member having a function of diffusing light from a backlight. For example, a light diffusing agent is provided by dispersing particles as a light diffusing agent in a thermoplastic resin, Used are those in which irregularities are formed on the surface of a plastic resin plate to impart light diffusibility, and a coating layer of a resin composition in which particles are dispersed is provided on the surface of a thermoplastic resin plate to impart light diffusibility. It is done. 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.

  The polarizing plate of the present invention is suitably used in the configuration of backlight / light diffusion plate / light diffusion sheet / brightness enhancement sheet / liquid crystal cell. 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.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present 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. In the following examples, the in-plane retardation value R ₀ and the thickness direction retardation value R _th of an optical compensation film made of a stretched norbornene resin are values measured using KOBRA 21ADH (manufactured by Oji Scientific Instruments). Point to. Moreover, the surface resistance value showing antistatic performance refers to the value measured using the surface specific resistance measuring apparatus Hirest-up MCP-HT450 (made by Mitsubishi Chemical Corporation).

<Example 1>
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 ratio of iodine / potassium iodide / water was 0.02 / 2. / 100 aqueous solution at 30 ° C. 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 in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

  On one side of the polarizing film obtained as described above, a uniaxially stretched polyethylene terephthalate film having a thickness of 40 μm was subjected to corona treatment on the bonding surface, and then bonded via an adhesive.

Next, on the opposite side of the polarizing film on which the stretched polyethylene terephthalate film is laminated, an optical compensation film (in-plane retardation value R ₀ : 63 nm, thickness direction retardation value) made of a biaxially stretched norbornene resin having a thickness of 73 μm. R _th : 225 nm) was subjected to corona treatment on the bonding surface, and then adhered via an adhesive to obtain a polarizing plate. In addition, the optical compensation film consisting of a uniaxially stretched polyethylene terephthalate film and a biaxially stretched norbornene resin was bonded so that their slow axes were orthogonal to the stretch axis of the polarizing film.

Next, an adhesive (25 μm thick) layer containing an antistatic agent was provided on the surface of the optical compensation film made of the biaxially stretched norbornene resin of the back side polarizing plate. This pressure-sensitive adhesive layer contains 3 parts of an ionic conductive composition (N-hexyl-4-methylpyridinium bis (trifluoromethanesulfonyl) imide) as an antistatic agent with respect to 100 parts of an acrylic pressure-sensitive adhesive. It formed using the containing adhesive. About the obtained polarizing plate, when the surface resistance value of the adhesive when the separator on the surface of the adhesive was peeled was measured, it was 6.0 × 10 ⁹ Ω / □, indicating a high antistatic ability.

<Example 2>
Instead of forming a pressure-sensitive adhesive layer containing an antistatic agent, a coating layer (thickness: 3 μm) containing an antistatic agent on the surface of the stretched polyethylene terephthalate film of a polarizing plate comprising a stretched polyethylene terephthalate film / polarizing film / optical compensation film A polarizing plate was produced in the same manner as in Example 1 except that was formed. For the formation of the coating layer, pentaerythritol triacrylate and polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate) are dissolved in ethyl acetate at a solid content concentration of 60/40 at a weight ratio of 60/40. An ultraviolet curable resin composition containing a leveling agent was used. Irgacure 184 (manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator is 5 parts with respect to the resin composition, and antimony pentoxide as an antistatic agent is 75 parts by weight with respect to the resin composition. In addition, a coating solution was prepared. This coating solution was applied so that the coating thickness after drying was 3 μm, dried for 3 minutes in a dryer set at 60 ° C., and then strength 20 mW / cm ² from the photocurable resin composition layer side. Was irradiated with light from the high-pressure mercury lamp so that the amount of light converted to h-ray was 200 mJ / cm ^2, and the ultraviolet curable resin composition layer was cured to form a coating layer containing an antistatic agent.

When the surface resistance value was measured in the same manner as in Example 1, it was 1 × 10 ¹⁰ Ω / □, indicating a high antistatic ability.

  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.

Claims (6)

  A polarizing plate comprising a structure in which a polarizing film made of a polyvinyl alcohol-based resin and a stretched polyethylene terephthalate film are laminated, and containing an antistatic agent.   The polarizing plate according to claim 1, further comprising a protective film or an optical compensation film laminated on the side opposite to the side on which the stretched polyethylene terephthalate film of the polarizing film is laminated.   The polarizing plate of Claim 1 or 2 which further has an adhesive layer in the outer surface on the opposite side to the side by which the stretched polyethylene terephthalate film of the polarizing film was laminated | stacked.   The polarizing plate according to claim 3, wherein the pressure-sensitive adhesive layer contains an antistatic agent.   The polarizing plate according to any one of claims 1 to 4, wherein a coating layer containing an antistatic agent is formed on the surface of any film constituting the polarizing plate.   A liquid crystal display device provided with the liquid crystal panel in which the polarizing plate in any one of Claims 3-5 is bonded to the liquid crystal cell through the adhesive layer.