KR20090037825A - A polarizer and liquid crystal display apparatus used thereof - Google Patents

Abstract

A polarizer having a polyethylene terephthalate film and a liquid crystal display device are provided to improve a mechanical intensity of a liquid crystal panel, and to prevent contact of a liquid crystal panel and a backlight system. A norbornene group resin film is laminated after an adhesive layer is positioned on one surface of a polarization film which is made of polyvinyl alcohol group resin. A polyethylene terephthalate film is laminated on the other surface of the polarization film. Thickness of the polyethylene terephthalate film is 20 ~ 50um. The adhesive layer is formed on an outer surface of the norbornene group resin film. The adhesive layer of the outer surface of the norbornene group resin film of a polarizer is arranged on a rear surface of a liquid crystal cell.

Description

A polarizer and a liquid crystal display apparatus used the same

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

The polarizing plate is usually transparent protection of a cellulose acetate type represented by a transparent protective film, for example, triacetyl cellulose, via an adhesive layer on one or both sides of a polarizing plate made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. It is a structure which laminated | stacked the film. This is bonded to a liquid crystal cell with an adhesive via the other optical film as needed, and makes it a component of a liquid crystal display device.

BACKGROUND ART Liquid crystal displays are thin display devices, such as liquid crystal televisions, liquid crystal monitors, and personal computers, and are rapidly expanding in use. In particular, the market expansion of liquid crystal televisions is remarkable, and the demand for cost reduction is very high. A polarizing plate for liquid crystal television is usually formed by laminating a triacetyl cellulose film (TAC film) with an aqueous adhesive on both sides of a polarizing film made of a polyvinyl alcohol-based resin film, and retardation film via an adhesive on one side of the polarizing plate. Is laminated.

As a retardation film laminated | stacked on a polarizing plate, the stretched processed article of a polycarbonate resin film, the stretched processed article of a cycloolefin resin film, etc. are used, but for liquid crystal televisions, it consists of a cycloolefin resin film with very little retardation unevenness at high temperature. A lot of retardation films are used. The bonded article of the retardation film which consists of such a polarizing plate and a cycloolefin resin film can consider reducing the number of components to comprise, or simplifying a manufacturing process for the improvement of productivity, and reduction of product cost, For example, Unexamined Japan Patent Publication No. Hei 8-43812 (Patent Document 1) discloses a laminated structure of a cycloolefin-based (norbornene-based) resin film / polarizing film / TAC film having a phase difference function.

Moreover, polyvinyl alcohol-type resin is disclosed in Unexamined-Japanese-Patent No. 2005-70140 (patent document 2), Unexamined-Japanese-Patent No. 2005-181817 (patent document 3), and Unexamined-Japanese-Patent No. 2005-208456 (patent document 4). Joining the polarizing film and cycloolefin type protective film which consist of this with a urethane type water-based adhesive agent is described.

In large screen liquid crystal television applications, the demand for thin-walled televisions is becoming thinner, but in this case, the following points are problems as components to be used in liquid crystal panels.

(1) Corresponding to the thin large screen of the liquid crystal panel, it is necessary to reinforce the strength of the panel.

(2) Thinning of the member to be used corresponding to the thinning of the liquid crystal television is required.

(3) The gap between the liquid crystal panel and the backlight system on the back becomes narrow, and it is necessary to prevent circular stains and Newton's rings caused by contact between the liquid crystal panel and the backlight system.

This invention is made | formed in order to solve the said subject, Comprising: It aims at being able to reinforce this, responding to the thinning of the liquid crystal panel applied, and can prevent the contact of the liquid crystal panel and backlight system using the same. It is to provide a polarizing plate and a liquid crystal display using the same.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve such a subject, the norbornene-type resin film is laminated | stacked on one side of the polarizing film which consists of polyvinyl alcohol-type resin via an adhesive bond layer, and the opposite side of the said polarizing film A polarizing plate on which a polyethylene terephthalate film is laminated, wherein the polyethylene terephthalate film is stretched, has a thickness of 20 to 50 µm, and has a haze of a polarizing plate in the range of 0.1 to 40%. It discovered that the polarizing plate which was excellent and excellent in visibility was obtained, and completed this invention.

As for the polarizing plate of this invention, a norbornene-type resin film is laminated | stacked on one side of the polarizing film which consists of polyvinyl alcohol-type resin via an adhesive bond layer, and it extends | stretches to the other side of the said polarizing film, and is 20-50 micrometers of A polyethylene terephthalate film having a thickness and having a haze in the range of 0.1 to 40% is laminated.

It is preferable that the polarizing plate of this invention has an adhesive layer in the outer surface of a norbornene-type resin film.

This invention also relates to the liquid crystal display device provided with the liquid crystal panel which made the polarizing plate of this invention mentioned above arrange | position the adhesive layer side of the outer surface of this norbornene-type resin film on the back of a liquid crystal cell, and bonded it to the liquid crystal cell. to provide.

The polarizing plate of this invention can achieve the improvement and thickness reduction of the mechanical strength of the liquid crystal panel applied, and can also prevent the contact of the liquid crystal panel and backlight system using the same. Moreover, the liquid crystal display device of this invention using the polarizing plate of this invention is applicable suitably to the liquid crystal display device for large screen liquid crystal televisions, especially the liquid crystal display device for wall-mounted liquid crystal televisions.

Specifically, the polarizing film used for the polarizing plate of this invention adsorbs and oriented the dichroic dye to the polyvinyl alcohol-type resin film uniaxially stretched. Polyvinyl alcohol-type resin is obtained by saponifying a polyvinyl acetate type resin. As polyvinyl acetate type resin, the copolymer of vinyl acetate and the other monomer copolymerizable with this besides the polyvinyl acetate which is a homopolymer of vinyl acetate, for example, an ethylene-vinyl acetate copolymer, etc. are mentioned. As another monomer copolymerizable with vinyl acetate, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamide which has an ammonium group, etc. are mentioned, for example.

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

What formed such polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method of forming a polyvinyl alcohol-type resin is not specifically limited, It can form into a film by a conventionally well-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 step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye and adsorbing such a dichroic dye (dyeing step), and treating the polyvinyl alcohol-based resin film adsorbed with a dichroic dye with an aqueous solution of boric acid. It is manufactured through the process (boric acid treatment process) to perform, and the process (water washing process) to wash with water after the process by such boric-acid aqueous solution.

In the production of the polarizing film, the polyvinyl alcohol-based resin film is usually uniaxially stretched, but such uniaxial stretching may be performed before the dyeing treatment step, may be performed during the dyeing treatment step, or the dyeing treatment step. It may be performed later. When uniaxial stretching is performed after the dyeing treatment step, such uniaxial stretching may be performed before the boric acid treatment step or may be performed during the boric acid treatment step. Of course, it is also possible to uniaxially stretch in these multiple steps. Uniaxial stretching may be extended | stretched uniaxially between rolls from which a circumferential speed differs, and you may make it uniaxially stretch using a hot roll. Moreover, the dry extending | stretching extending | stretching in air | atmosphere may be sufficient, and the wet extending | stretching extending | stretching in the state swollen with the solvent may be sufficient. A draw ratio is about 3 to 8 times normally.

The dyeing with the dichroic dye of the polyvinyl alcohol-based resin film in the dyeing step is performed by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye, for example. As a dichroic dye, iodine, a dichroic dye, etc. are used, for example. Dichroic dyes include, for example, dichroic direct dyes made of disazo compounds such as C. I. DIRECT RED 39, dichroic direct dyes made of compounds such as tris azo and tetrakis azo. In addition, it is preferable that the polyvinyl alcohol-based resin film is subjected to an immersion treatment with water before the dyeing treatment.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in such an 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 a dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C, and the immersion time (dyeing time) in such an aqueous solution is usually 20 to 1800 seconds.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. The content of the dichroic dye in such an aqueous solution is usually 1 x 10 ^-4 to 10 parts by weight, preferably 1 x 10 ^-3 to 1 part by weight, particularly preferably 1 x 10 ^- per 100 parts by weight of water. ³ to 1 × 10 ^-2 parts by weight. Such aqueous solution may contain inorganic salts, such as sodium sulfate, as a dyeing adjuvant. When using a dichroic dye as a dichroic dye, the temperature of the dye aqueous solution used for dyeing is 20-80 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is 10 to 1800 second normally.

The boric acid treatment step is performed by immersing the polyvinyl alcohol-based resin film dyed with a dichroic dye in an aqueous solution containing boric acid. The amount of boric acid in boric-acid containing aqueous solution is 2-15 weight part normally per 100 weight part of water, Preferably it is 5-12 weight part.

In the case where iodine is used as the dichroic dye in the dyeing step described above, the boric acid-containing aqueous solution used in the boric acid treatment step preferably contains potassium iodide. In this case, the amount of potassium iodide in boric-acid containing aqueous solution is 0.1-15 weight part normally per 100 weight part of water, Preferably it is 5-12 weight part. Immersion time in boric-acid containing aqueous solution is 60-1200 second normally, Preferably it is 150-600 second, More preferably, it is 200-400 second. The temperature of the boric acid containing aqueous solution is 50 degreeC or more normally, Preferably it is 50-85 degreeC, More preferably, it is 60-80 degreeC.

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

In this way, the polyvinyl alcohol-based resin film can be subjected to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment, and water treatment to obtain a polarizing film. The thickness of such a polarizing film is in the range of 5-40 micrometers normally. The polarizing plate of the present invention has a structure in which a norbornene-based resin film is laminated on one side of such a polarizing film via an adhesive layer, and a polyethylene terephthalate film specific on the other side is laminated via an adhesive layer.

As a norbornene-type resin film used for the polarizing plate of this invention, it is a film which consists of thermoplastic resin which has a unit of the monomer which consists of cyclic olefins (cycloolefin), such as a norbornene and a polycyclic norbornene-type monomer, for example. The norbornene-based resin film may be an addition copolymer such as an aromatic compound having a cycloolefin and a cyclic olefin or a vinyl group, in addition to the hydrogenated product of the ring-opening polymer of the cycloolefin and the ring-opening copolymer using two or more cycloolefins. It is also effective to introduce a polar group.

In the case of using a copolymer of a cycloolefin with a chain olefin and an aromatic compound having a vinyl group, as the chain olefin, ethylene, propylene, etc. may be mentioned, and examples of the aromatic compound having a vinyl group include styrene, α-methylstyrene, Nuclear alkyl substituted styrene, etc. are mentioned. In such a copolymer, 50 mol% or less (preferably 15-50 mol%) may be sufficient as the unit of the monomer which consists of cycloolefin. In particular, in the case of using a ternary copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group, the unit of the monomer consisting of the cycloolefin can be made in a relatively small amount as described above. In such a terpolymer, the unit of the monomer which consists of linear olefins is 5 to 80 mol% normally, and the unit of the monomer which consists of an aromatic compound which has a vinyl group is 5 to 80 mol% normally.

Cycloolefin resin is suitable commercially available products, for example, Topas (manufactured by Ticona), Aton (manufactured by JSR Corporation), ZEONOR (manufactured by Nihon Xeon), ZEONEX (Nihon Xeon) Co., Ltd., Apel (made by Mitsui Chemicals), etc. can be used suitably. When forming a cycloolefin resin into a film to form a film, well-known methods, such as a solvent casting method and a melt extrusion method, are used suitably. For example, Esshina (made by Sekisuga Chemical Co., Ltd.), SCA40 (manufactured by Sekisuga Chemical Co., Ltd.), Zeonoa Film (made by OPTES), Aton Film (JSR Co., Ltd.) You may use the commercial item of the film made from cycloolefin resin previously formed into a film), etc. as a transparent protective film.

The norbornene-based resin film is stretched in at least one direction, and optical compensation of the liquid crystal is performed, thereby contributing to enlargement of the viewing angle of the liquid crystal display. The norbornene-based resin film used in the present invention has a refractive index in the direction in which the refractive index in the in-plane slow axis direction of the stretched film is nx, orthogonal to this in the plane (ny phase direction), ny In the case where the refractive index in the thickness direction is nz and the thickness of the film is d, the in-plane retardation value R ₀ and the thickness direction retardation value R _th of the films represented by the following equations (1) and (2) are respectively in-plane. It is preferable that the phase difference value R ₀ is in the range of 40 to 100 nm (more suitably 40 to 80 nm), and the thickness direction retardation value R _th is in the range of 80 to 250 nm (more preferably 100 to 250 nm).

R ₀ = (n _x -n _y ) × d

R _th = [(n _x + n _y ) / 2-n _z ] × d

When the in-plane retardation value R ₀ is less than 40 nm or exceeds 100 nm, the viewing angle compensating ability of the panel tends to be lowered. In addition, when the thickness direction retardation value R _th is less than 80 nm or exceeds 250 nm, there exists a tendency for the viewing angle compensation ability of a panel to fall again. The in-plane retardation value R ₀ and the thickness direction retardation value R _th described above can be measured using, for example, KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.).

In order to obtain the norbornene-based resin film having the refractive index characteristics as described above, in addition to appropriately adjusting the draw ratio and draw speed, various temperatures such as preheating temperature, stretching temperature, heat set temperature, cooling temperature, etc. at the time of stretching, And the pattern may be appropriately selected. By stretching under relatively relaxed conditions, such refractive index characteristics can be obtained. For example, the draw ratio is preferably in the range of 1.05 times to 1.6 times, and more preferably 1.1 times to 1.5 times. Do. In the case of biaxial stretching, the stretching ratio in the maximum stretching direction may be in the above range.

Although the norbornene-type resin film which extended | stretched used for this invention is not specifically limited about the thickness, It is preferable to exist in the range of 20-80 micrometers, and it is more preferable to exist in the range of 40-80 micrometers. When the thickness of the norbornene-based resin film is less than 20 µm, it is because the handling of the film is difficult and a predetermined retardation value tends to be difficult to be expressed, while the thickness of the norbornene-based resin film exceeds 80 µm. In this case, the workability may be lowered, the transparency may be lowered, or the weight of the obtained polarizing plate may be increased.

The polyethylene terephthalate film used for the polarizing plate of this invention is extended | stretched, has a thickness of 20-50 micrometers, and haze exists in the range of 0.1 to 40%. It is characterized by the above-mentioned. In the polarizing plate of this invention, a norbornene-type resin film is laminated | stacked on one side of the polarizing film which consists of polyvinyl alcohol-type resin via an adhesive bond layer, and such a polyethylene terephthalate film is laminated | stacked on the other side of the said polarizing film It is provided with the structure which consists of a structure which consists of a structure which responds to thickness reduction of the liquid crystal panel applied, and has the effect that the contact of the liquid crystal panel and a backlight system using the same can be prevented.

Polyethylene terephthalate is resin in which 80 mol% or more of a repeating unit consists of ethylene terephthalate. As another copolymerization component, isophthalic acid, p- (beta) -oxyethoxy benzoic acid, 4,4'- dicarboxy diphenyl, 4,4'- dicarboxy benzophenone, bis (4-carboxyphenyl) ethane, adipic acid, Dicarboxylic acid components such as sebacic acid, 5-sodium sulfoisophthalic acid and 1,4-dicarboxycyclohexane, for example, propylene glycol, butadidiol, neopentyl glycol, diethylene glycol, cyclohexanediol, and ethylene of bisphenol A Diol components, such as an oxide adduct, polyethyleneglycol, polypropylene glycol, polytetramethylene glycol, are mentioned. These dicarboxylic acid components and glycol components can be used in combination of 2 or more type as needed. Moreover, it is also possible to use together oxycarboxylic acids, such as p-oxybenzoic acid, with the said dicarboxylic acid component and the glycol component. Such other copolymerization components may include a compound containing a small amount of an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like.

As a manufacturing method of polyethylene terephthalate, arbitrary manufacturing methods, such as the so-called direct polymerization method which directly reacts terephthalic acid and ethylene glycol, and the so-called transesterification reaction which transesterifies dimethyl ester of terephthalic acid and ethylene glycol, are applicable. Moreover, a well-known additive can be contained as needed. For example, a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistant agent, an impact resistance improving agent, or the like may be contained. However, since transparency is required for optical applications, it is preferable to keep the amount of the additive added to a minimum.

The stretched polyethylene terephthalate film can be manufactured by shape | molding the said raw material resin into a film form, and performing an extending | stretching process. Stretching is uniaxial stretching stretching in the MD direction (flow direction) or TD direction (direction perpendicular to the flowing direction), biaxial stretching stretching in both the MD direction and the TD direction, stretching in both the MD direction and the non-TD direction. Oblique stretching; and the like. By extending | stretching process in any extending | stretching, the polyethylene terephthalate type resin film with high mechanical strength can be obtained. Especially, since a uniaxial stretched film tends to hardly appear interference interference when the polarizing plate of this invention is installed in a liquid crystal panel, it is preferable. The production method of the uniaxially stretched polyethylene terephthalate film is optional and is not particularly limited. However, a non-oriented film obtained by melting the raw material resin and extruding it into a sheet is tentered at a temperature above the glass transition temperature. After lateral stretching (stretching in the TD direction), a method of performing heat fixing treatment is mentioned. In this case, the stretching temperature is 80 to 130 ° C, preferably 90 to 120 ° C, and the draw ratio is 2.5 to 6 times, preferably 3 to 5.5 times. If the draw ratio is low, the polyethylene terephthalate resin film tends not to exhibit sufficient transparency. In the case of biaxial stretching, for example, an unoriented film extruded into a sheet is longitudinally stretched (drawn in the MD direction) with a tenter at a temperature higher than the glass transition temperature, and then transversely stretched (in the TD direction). The method, the method of longitudinally extending | stretching simultaneously, etc. are mentioned.

Moreover, from a viewpoint of reducing the deformation | transformation of the orientation main axis in a polyethylene terephthalate film, it is preferable to relax a film to a long side direction after the above-mentioned lateral stretch, before heat-setting. The temperature to relax is 90-200 degreeC, Preferably it is 120-180 degreeC. Although the amount of relaxation varies depending on the lateral stretching conditions, it is preferable to set the amount of relaxation and the temperature so that the thermal contraction rate at 150 ° C. of the film after the relaxation treatment is 2% or less.

The temperature of heat setting treatment is 180-250 degreeC normally, Preferably it is 200-245 degreeC. First, the heat fixation treatment is performed at the above-mentioned temperature at a regular length, and the relaxation treatment is performed so that the ratio of relaxation in the width direction of the film is 1 to 10% (preferably 2 to 5%). It is preferable to In this way, deformation of the orientation main axis is reduced, and an elongated polyethylene terephthalate film excellent in heat resistance can be obtained. In this invention, the polyethylene terephthalate film whose maximum value of the deformation | transformation of an orientation principal axis is 10 degrees or less, More preferably, it is 8 degrees or less, More preferably, it is 5 degrees or less, can be used suitably. When the polyethylene terephthalate film in which the maximum value of the deformation | transformation of an orientation principal axis exceeds 10 degree is used, when a polarizing plate using such a polyethylene terephthalate film is bonded to the liquid crystal display screen of a liquid crystal display device, color defects tend to become large. In addition, the maximum value of the deformation | transformation of the orientation main axis of the polyethylene terephthalate film mentioned above can be measured, for example using a retardation film inspection apparatus RETS system (made by Otsuka Denshi Co., Ltd.).

The polyethylene terephthalate film in the range of 20-50 micrometers in thickness is used for the polarizing plate of this invention. When the polyethylene terephthalate film whose thickness is less than 20 micrometers is used, handling of a film is difficult, and when the polyethylene terephthalate film whose thickness exceeds 50 micrometers is used, the advantage of thinning becomes small.

Moreover, the polyethylene terephthalate film whose haze exists in 0.1 to 40% of range is used for the polarizing plate of this invention. When the haze uses less than 0.1% polyethylene terephthalate film, since the surface irregularities are less, the effect of preventing the occurrence of stains due to contact with the backlight system is small, and the polyethylene tere with haze of more than 40% When a phthalate film is used, there exists a tendency for light diffusion to be too strong and front brightness and visibility to fall. In addition, the haze of the polyethylene terephthalate film mentioned above is defined as ratio of the diffusivity with respect to total light transmittance, as prescribed in JISK7136, and can be measured with a commercially available haze meter.

As a method of imparting haze to a polyethylene terephthalate film, a method of mixing inorganic fine particles or organic fine particles in polyethylene terephthalate, which is a raw material resin, and a method of coating a coating liquid obtained by mixing inorganic fine particles or organic fine particles with a resin binder on the surface of the film Although these etc. are mentioned, It is not limited to these. Examples of the inorganic fine particles include silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate and the like. As the organic fine particles, heat resistant resin particles such as crosslinked polyacrylic acid particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and polyimide particles can be used.

Further, the polyethylene terephthalate film used in the present invention is preferably not less than the in-plane retardation value R ₀ 1000nm, and is more preferably not less than 3000nm. If the in-plane retardation value R ₀ of less than 1000nm using a polyethylene terephthalate film, there is a tendency for the coloring from the front striking. In addition, the upper limit of the in-plane retardation value R ₀ of the polyethylene terephthalate film used in the present invention is sufficient to approximately 10000nm.

The polyethylene terephthalate film having the characteristics described above is excellent overall in terms of mechanical properties, solvent resistance, scratch resistance, cost, and the like, and can be particularly suitably used in the polarizing plate of the present invention.

The polyethylene terephthalate film used for the manufacturing method of this invention may be provided with the reverse adhesion layer, and the formation method of the polyethylene terephthalate film provided with such a reverse adhesion layer is not specifically limited. For example, the method of forming in the film which completed all the extending processes, the process of extending | stretching a polyethylene terephthalate type resin, ie, forming in between a longitudinal stretch process and a lateral stretch process, and just before being adhere | attached with a polarizing film Or a method of forming after bonding is employed. Especially, from a viewpoint of productivity, the method of longitudinally extending | stretching a polyethylene terephthalate and forming and then transversely stretching is employ | adopted preferably. The reverse adhesive layer can be provided on one side of the polyethylene terephthalate or on one side that is bonded to the polarizing film made of a polyvinyl alcohol-based resin via an adhesive. Although the component which comprises a reverse adhesion layer is not specifically limited, For example, polyester-based resin, urethane-type resin, acrylic resin, etc. which have a polar group in frame | skeleton, and are comparatively low molecular weight and low glass transition temperature are mentioned. Moreover, if necessary, a crosslinking agent, an organic filler or an inorganic filler, a surfactant, a lubricant, and the like may be contained. Surface treatments such as an antiglare treatment, a hard coat treatment, an antistatic treatment and the like may be applied to the surface opposite to the surface to be bonded to the polarizing film in the polyethylene terephthalate film. Moreover, the coating layer which consists of a liquid crystalline compound, its high molecular weight compound, etc. may be formed. Moreover, even if a polyethylene naphthalate film is used instead of a polyethylene terephthalate film, almost the same effect can be obtained.

The polarizing plate of this invention bonds a norbornene-type resin film to one side of the above-mentioned polarizing film via an adhesive agent, and also bonds a polyethylene terephthalate film to the other surface of the said polarizing film via an adhesive agent. The polarizing plate of this invention may use the same kind of adhesive agent on both surfaces of a polarizing film, and may use a different kind of adhesive agent, respectively. As an adhesive agent, the thing of the aqueous system, ie, what melt | dissolved the adhesive component in water, or disperse | distributed to water is mentioned from a viewpoint of thinning an adhesive bond layer. For example, the composition using polyvinyl alcohol-type resin or urethane resin as a main component is mentioned as a preferable adhesive agent.

When a polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin is, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetacetyl group-modified polyvinyl alcohol, Modified polyvinyl alcohol-based resins such as methylol group-modified polyvinyl alcohol and amino group-modified polyvinyl alcohol may be used. In this case, an aqueous solution of polyvinyl alcohol-based resin is used as the adhesive. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.

In order to improve adhesiveness, it is preferable to add curable components, such as glyoxal and a water-soluble epoxy resin, and a crosslinking agent to the adhesive agent which consists of aqueous solution of polyvinyl alcohol-type resin. As a water-soluble epoxy resin, epichlorohydrin is made to react with the polyamide amine obtained by reaction of polyalkylene polyamines, such as diethylene triamine and triethylene tetraamine, and dicarboxylic acids, such as adipic acid, for example. The polyamide polyamine epoxy resin obtained can be used suitably. Commercially available products of such polyamide polyamine epoxy resins include Sumirez resin 650 (manufactured by Sumica Chemtex Co., Ltd.), Sumirez resin 675 (manufactured by Sumika Chemtex Co., Ltd.), WS-525 (manufactured by Nippon PMC Co., Ltd.), and the like. Can be mentioned. The addition amount (total amount when adding together) of these curable components and a crosslinking agent is 1-100 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resins, Preferably it is 1-50 weight part. 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 the adhesion tends to be small, and the addition amount of the curable component and the crosslinking agent is polyvinyl alcohol. It is because an adhesive bond layer tends to break when it exceeds 100 weight part with respect to 100 weight part of system resin.

Moreover, when using urethane resin as a main component of an adhesive agent, the mixture of the polyester-type ionomer type urethane resin and the compound which has glycidyloxy group is mentioned as an example of a suitable adhesive composition. The polyester ionomer-type urethane resin here is a urethane resin which has a polyester frame | skeleton, and a small amount of ionic component (hydrophilic component) is introduce | transduced in it. Such ionomer-type urethane resin is suitable as an aqueous adhesive since it emulsifies in water directly without using an emulsifier, and turns into an emulsion. Polyester-based ionomer-type urethane resin itself is well-known, for example, Unexamined-Japanese-Patent No. 7-97504 describes as an example of the polymeric dispersing agent for disperse | distributing a phenolic resin in an aqueous medium, In addition, the above-mentioned Unexamined-Japanese-Patent No. 2005-70140 (patent document 2) and Unexamined-Japanese-Patent No. 2005-208456 (patent document 4) are mentioned of the compound which has polyester-type ionomer type urethane resin and glycidyloxy group. The aspect which bonds a cycloolefin resin film to the polarizing film which consists of polyvinyl alcohol-type resin using an adhesive as an adhesive agent is disclosed.

As a method of bonding the norbornene-based resin film and the polyethylene terephthalate film mentioned above to a polarizing film, what is generally known may be sufficient, for example, the casting method, the Mayer coating method, the gravure coating method. And a method in which an adhesive is applied to an adhesive surface of a polarizing film and / or a film bonded thereto by a comma coating method, a doctor blade method, a die coating method, a dip coating method, a spraying method, or the like, and the two are overlapped. The casting method is a method of flowing and spreading an adhesive downward on the surface while moving a film, which is a coated object, in a substantially vertical direction, a substantially horizontal direction, or an inclined direction therebetween. After apply | coating an adhesive agent, a polarizing film and the film bonded to this are pinched together with a nip roll etc., and are bonded. In addition, after dropping the said photocurable adhesive agent between a polarizer and a protective film, it is possible to use a metal, rubber | gum, etc. as a material of a roll in the method which presses with a roll etc. and presses and expands uniformly. Moreover, in the method of letting the said photocurable adhesive agent dripped between a polarizer and a protective film between a roll and a roll, and pressing and expanding, such rolls may be the same material, and may be a different material.

Moreover, in order to improve adhesiveness, the surface of an adhesive bond layer may be suitably subjected to surface treatments such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment, and the like. As a saponification process, the method of immersing in aqueous solution of alkalis, such as sodium hydroxide and potassium hydroxide, is mentioned.

The norbornene-based resin film and the polyethylene terephthalate film are laminated on the polarizing film via the adhesive layer, respectively, and then dried to cure the adhesive layer. This drying process is performed by, for example, attaching hot air, and the temperature is usually in the range of 40 to 100 ° C, and preferably in the range of 60 to 100. In addition, a drying time is 20 to 1200 second normally.

The thickness of the adhesive bond layer after drying is 0.001-5 micrometers normally, Preferably it is 0.01-2 micrometers, More preferably, it is 0.01-1 micrometer. When the thickness of an adhesive bond layer is less than 0.001 micrometer, adhesion may become inadequate, and when the thickness of an adhesive bond layer exceeds 5 micrometers, there exists a possibility that the appearance defect of a polarizing plate may arise.

After bonding, curing at least half a day, usually several days or more, at a temperature below room temperature may be sufficient to obtain sufficient adhesive strength. Preferable curing temperature is the range of 30-50 degreeC, More preferably, it is 35-45 degreeC. When curing temperature exceeds 50 degreeC, what is called "tighten up" easily occurs in roll winding state. In addition, the humidity at the time of curing may be appropriate, and the relative humidity may be in the range of 0 to 70% RH. The curing time is usually 1 to 10 days, preferably 2 to 7 days.

Moreover, a photocurable adhesive agent can also be used for the adhesive agent in the polarizing plate of this invention. As a photocurable adhesive agent, the mixture of a photocurable epoxy resin, a photocationic polymerization initiator, etc. are mentioned, for example. In such a case, a photocurable adhesive agent is hardened by irradiating an active energy ray. Although the light source of an active energy ray is not specifically limited, The active energy ray which has light emission distribution in wavelength 400nm or less is preferable, Specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave Mercury lamps and metal halide lamps are preferable here.

Light irradiation intensity | strength with respect to a photocurable adhesive agent is suitably determined by the composition of the said photocurable adhesive agent, Although it does not specifically limit, It is preferable that irradiation intensity of the wavelength range effective for activation of a polymerization initiator is 0.1-6000 mW / cm <2>. The irradiation intensity is 0.1 mW / cm 2 or more, the reaction time is not too long, and is 6000 mW / cm 2 or less, and yellowing of the epoxy resin and deterioration of the polarizer due to heat generation during curing of the thermosetting and photocurable adhesives radiated from the light source. There is little concern about it. Although the irradiation time with respect to a photocurable adhesive agent is controlled by every photocurable adhesive agent to harden, it does not restrict | limit, but the accumulated light quantity expressed by the product of the said irradiation intensity and irradiation time is set to 10-10000mJ / m <^2> . It is preferable to be set. Accumulated light amount with respect to a photocurable adhesive agent is 10 mJ / m <^2> or more, a sufficient quantity of active species derived from a polymerization initiator can be produced | generated, and hardening reaction can be advanced more reliably, Furthermore, since it is 10000 mJ / m <^2> or less, irradiation time does not become too long And good productivity can be maintained.

When hardening a photocurable adhesive agent by irradiation of an active energy ray, it is preferable to perform hardening on condition that the various functions of a polarizing plate, such as polarization degree, a transmittance | permeability, a color, and transparency of a protective film, do not fall.

In the polarizing plate of the present invention, it is preferable that the norbornene-based resin film has an adhesive layer on its outer surface (the side opposite to the side bonded to the polarizing film). As an adhesive used for such an adhesive layer, a conventionally well-known suitable adhesive can be used without a restriction | limiting especially, For example, an acrylic adhesive, a urethane type adhesive, a silicone type adhesive etc. are mentioned. Especially, an acrylic adhesive is used preferably from a viewpoint of transparency, adhesive force, reliability, rework property, etc. The pressure-sensitive adhesive layer may be formed by a method of using such a pressure-sensitive adhesive, for example, in the form of an organic solvent solution, applying it to a base film with a die coater, a gravure coater, or the like, and drying the mold. It can also be formed by the method of transferring the sheet-like adhesive formed on the plastic film (called a separate film) which was made into a base film. 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.

When the adhesive layer mentioned above is formed in the outer surface of a norbornene-type resin film, it is preferable that an optical functional film sticks through the said adhesive layer. As an optical functional film, the reflective polarizing film which apply | coats a liquid crystalline compound to the surface of a base material, for example, transmits an oriented optical compensation film, polarized light of some kind, and reflects the polarized light which shows the opposite property to this. , Retardation film made of polycarbonate resin, retardation film made of cyclic polyolefin resin, film with anti-glare function having irregular shape on the surface, film with surface antireflection function, reflective film with reflection function on surface, reflection function And a semi-transmissive reflective film having both a transmissive function and the like. As a commercial item corresponded to the optical compensation film in which the liquid crystalline compound is apply | coated to the base material surface, and is orientated, WV film (made by Fujifilm Co., Ltd.), NH film (made by Shin-Nihon Sekiyu Co., Ltd.), NR film (New) Nippon Sekiyu Co., Ltd.) etc. are mentioned. As a commercial item which corresponds to the reflection type polarizing film which transmits some kind of polarized light and reflects the polarized light which shows the opposite property, it can be obtained from DBEF (made by 3M, Japan, Sumitomos Reem Co., Ltd.). And the like). Moreover, as a commercial item corresponded to the retardation film which consists of cyclic polyolefin type resin, for example, an aton film (made by JSR Corporation), Essina (made by Sekisui Chemical Co., Ltd.), a Zeano film (Co., Ltd.) Optes manufacture) etc. are mentioned.

This invention also provides also about the liquid crystal display device provided with the liquid crystal panel which made the polarizing plate of this invention mentioned above arrange | position the adhesive layer side of the outer surface of a norbornene-type resin film on the back of a liquid crystal cell, and bonded it to the liquid crystal cell. do. 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 of the liquid crystal cell, and has sufficient mechanical strength while corresponding to thinning, and furthermore, the polarizing plate of the present invention on the back side of the liquid crystal panel. By arrange | positioning the polyethylene terephthalate film side of the liquid crystal display device which can prevent the contact of a liquid crystal panel and a backlight system. In the liquid crystal display device of the present invention, with respect to 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 requirement that the liquid crystal display device is usually provided in addition to the liquid crystal panel (light diffusing plate) , Backlight, etc.) are not particularly limited. Moreover, although a polarizing plate is normally formed also in the front side of a liquid crystal cell, a liquid crystal panel is not specifically limited about the polarizing plate formed in the front side of such a liquid crystal cell, A conventionally well-known suitable polarizing plate can be used. In addition, the "back side" of the above-mentioned liquid crystal cell and a liquid crystal panel means the backlight side when a liquid crystal panel was mounted in a liquid crystal display device, and the "front side" of a liquid crystal cell and a liquid crystal panel is referred to as a liquid crystal display device. Means the viewing side when mounted on the.

Although an Example is given to the following and this invention is demonstrated to it in more detail, this invention is not limited to these Examples. In addition, unless otherwise indicated,% and the part which show content-usage-amount are a basis of weight in an Example. In the following examples, the in-plane retardation value and the thickness direction retardation value of the stretched film refer to values measured using KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). In addition, haze refers to the value measured using the haze meter HM-150 type (made by Murakamishiki Saigi Jutsugenkyu Sho) based on JISK7136.

<Example 1>

An aqueous solution in which the weight ratio of iodide / potassium iodide / water is 0.02 / 2/100 after immersing a polyvinyl alcohol film having a thickness of 75 µm with an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% or more in pure water at 30 ° C. Was immersed at 30 ° C. Thereafter, the solution was immersed at 56.5 ° C. in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 12/5/100. Subsequently, after wash | cleaning with the pure water of 8 degreeC, it dried at 65 degreeC and obtained the polarizing film in which iodine adsorption-orientated to polyvinyl alcohol. Stretching was mainly performed in the iodine dyeing and boric acid treatment process, and the total draw ratio was 5.3 times.

A stretched norbornene-based resin film (in-plane retardation value R ₀ : 55 nm, thickness direction retardation value Rth: 124 nm) having a thickness of 68 μm was prepared, and a corona treatment was performed on the adhesive surface thereof. Separately, a stretched polyethylene terephthalate film having a thickness of 37 µm and a haze of 17% (maximum value of strain of the orientation major axis: 2 degrees, in-plane retardation value R ₀ : 3800 nm) was prepared, and the adhesive surface was subjected to corona treatment.

The corona-treated surface of the norbornene resin film is bonded to one surface of the polarizing film obtained as described above, and the corona-treated surface of the stretched polyethylene terephthalate film is bonded and bonded to the other surface via a photocurable adhesive. Adhesion was obtained to obtain a polarizing plate. Such a polarizing plate is hard to tear, and is also light in weight compared with a normal polarizing plate. The 25-micrometer-thick acrylic adhesive layer was formed in the outer surface of the extending | stretching norbornene-type resin film of such a polarizing plate. The polarizing plate arrange | positions the outer surface side of the stretched norbornene-type resin film which formed such an adhesive layer on the back surface of a liquid crystal cell, arrange | positions a commercially available polarizing plate on the front surface of a liquid crystal cell, assembles a liquid crystal panel, and commercially diffuses this, A liquid crystal display device was manufactured in combination with a plate and a backlight. When the display of the liquid crystal display was visually observed, spots due to contact with the backlight did not appear.

Comparative Example 1

The polarizing plate was obtained like Example 1 except having used the surface saponification triacetyl cellulose film instead of the stretched polyethylene terephthalate film in Example 1. This polarizer was easy to tear. As in Example 1, after forming the pressure-sensitive adhesive layer, the liquid crystal panel was assembled on the rear surface of the liquid crystal cell to fabricate a liquid crystal display, and when the display was observed, spots due to contact with the backlight were observed. .

The disclosed embodiments and examples are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is shown by above-described not description but Claim, and it is intended that the meaning of a claim and equality and all the changes within a claim are included.

Claims (3)

A norbornene-based resin film is laminated on one side of a polarizing film made of polyvinyl alcohol resin via an adhesive layer, stretched on the other side of the polarizing film, has a thickness of 20 to 50 µm, and a haze The polarizing plate in which the polyethylene terephthalate film in the range of 0.1 to 40% is laminated | stacked. The polarizing plate of Claim 1 which has an adhesive layer in the outer surface of a norbornene-type resin film. The liquid crystal display device provided with the liquid crystal panel which made the polarizing plate of Claim 2 arrange | position the adhesive layer side of the outer surface of this norbornene-type resin film on the back surface of a liquid crystal cell, and bonded it to the liquid crystal cell.