JP2002350636A - Polarizer and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizer by which a beautiful picture whose color contrast and hue are not deteriorated and which is not blurred can be realized for a long period of time even when the polarizer is used as a liquid crystal display element under a condition of high temperature and high humidity for a long period of time. SOLUTION: This polarizer is manufactured by impregnating and letting adsorbe a polarizing element in a polymer film in a supercritical state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a polarizer having a high degree of polarization and having a small decrease in the degree of polarization even in an environment under high temperature and high humidity, and a method for producing the same. It relates to an excellent polarizer.

[0002]

2. Description of the Related Art A polarizing film is used for a liquid crystal display and the like. The polarizing film is composed of three layers in which a protective layer such as triacetyl cellulose is laminated on both surfaces of a polarizer to improve moisture resistance. Further, as the polarizer, a uniaxially oriented film in which iodine or a dye is adsorbed and dispersed in polyvinyl alcohol (PVA) is usually used.

However, these PVA-based polarizers not only have poor mechanical properties, but also tend to shrink or expand in size due to heat or moisture, or have a reduced polarizing function. It is a laminated body. The protective layer has no birefringence, high light transmittance, excellent moisture resistance and heat resistance, excellent mechanical properties, smooth surface, adhesion to polarizer Is required to be good. Therefore, conventionally, cellulose triacetate (TAC) has been used as a protective layer.

[0004]

However, such a TAC sheet layer has insufficient moisture-proof properties. For this reason, in a high-temperature and high-humidity environment, for example, in an environment of 80 ° C. and 90 RH%, it takes about 100 hours. The polarizer is deteriorated, and the polarizing function is rapidly reduced. In addition, TAC has a weak mechanical strength and requires the use of two sheets having a thickness of 80 μm or more on both sides. Therefore, in addition to the problem that the polarizing film must be a thick film of about 180 μm,
The production of the TAC sheet also has a serious drawback that a harmful solvent called methylene chloride must be used, which has a great adverse effect on humans and the environment.

Accordingly, Japanese Patent Application Laid-Open No. 4-339821 discloses
JP-A-5-212828, JP-A-10-1304
As disclosed in Japanese Patent Application Laid-Open No. 02-101, Japanese Patent Application Laid-Open No. 10-101907 and the like, it has been proposed to use a water-resistant thermoplastic norbornene-based resin instead of TAC.
However, these proposals have a drawback that the polarizer cannot be prevented from deteriorating because strong adhesion to PVA cannot be obtained. In addition, since the water vapor transmittance is extremely small, a polarizer containing water cannot be used. TA by evaporation of water
Volatilized water accumulates at the interface between C and the protective layer, causing a so-called swelling phenomenon, and cannot be used for optical applications.

That is, there has been no polarizing film made of a PVA polarizer which is excellent in mechanical properties and environmental suitability without deteriorating the properties of the PVA polarizer over a long period of time.

In order to further improve the moisture resistance of the polarizer, a dichroic dye is added to a matrix polymer such as polyester having excellent water resistance instead of using hydrophilic polyvinyl alcohol (PVA) as the matrix polymer. The impregnated and adsorbed polarizer is disclosed in JP-A-58-68008.
JP, JP-A-60-125804, JP-A-60-125804
Japanese Patent Application Laid-Open No. 135185/1990 and Japanese Patent Application Laid-Open No. 5-1110 / 1993.

However, when a polarizing element such as a dichroic dye having a low polarization accuracy is used, the degree of polarization becomes 9
Not only is it as low as less than 9.9%, but even though a matrix resin having excellent water resistance is used, the degree of polarization after exposure to high temperature and high humidity is extremely low at 95% or less. There was no.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polarizer and a polarizer which improve the above disadvantages.

The method for producing a polarizer of the present invention is a method for producing a polarizer, comprising impregnating and adsorbing a polarizing element on a polymer film in a supercritical state to produce a polarizer.

[0011] The polarizer of the present invention is a polarizer obtained by impregnating and adsorbing a polarizer on a polymer film in a supercritical state.

Here, the polarizing element is a compound having a polarizing property selected from a dichroic dye, iodine, a liquid crystal compound and the like.
^-12 m ² / N or less, a uniaxially oriented polymer compound having a water absorption of 0.5% or less, specifically, a cyclic olefin copolymer (COC), hydrogenated polystyrene, 4-methylpentene polymer, In the present invention, an oriented polymer selected from polycarbonate (PC), polyarylate (PAR), polysulfone (PSu), polyethersulfone (PES), polyester, and modified products thereof is particularly preferred. Further, it is preferable to stretch and orient in the same direction as the original orientation after the impregnation / adsorption because the degree of polarization and the water resistance can be further improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

According to the method of the present invention, a polarizer is produced by impregnating and adsorbing a polarizing element on a polymer film in a supercritical state. According to the method of the present invention, a polarizer having an extremely high degree of polarization is produced. A polarizer having a particularly high degree of polarization such that the degree of polarization generally obtainable by the present invention is generally preferably at least 99.9%, more preferably at least 99.99% by simple warm water immersion / impregnation. And a polarizer capable of maintaining a high degree of polarization of preferably 95% or more, more preferably 97% or more, even after treatment at a high temperature and high humidity of 700 hours at 60 ° C. and 90 RH%. It cannot be obtained. That is, a polarizer excellent in such a high degree of polarization and excellent in moisture resistance can be obtained only by impregnating a polarizing element with a polymer in a supercritical state.

In the present invention, the supercritical state means that when a substance is heated and pressurized, when it exceeds a specific temperature and pressure, it is impregnated with a gas and a liquid. It refers to a specific state that has both diffusivity and permeability, viscosity, and fluidity such as liquid. The specific temperature and pressure vary depending on the substance, and in the case of carbon dioxide gas, 31 ° C., 7.3M
Pa or more, -140 ° C in air, 3.77 MPa or more,
In the case of water, the temperature is 374 ° C., 22.1 MPa or more.

In order to create such a supercritical state, it is necessary to carry out the treatment in a pressurized container such as a closed autoclave. In such a pressurized container, a polarizer and a polymer compound to be impregnated and a substance which becomes a supercritical gas are put together. In general, carbon dioxide or nitrogen, which becomes a supercritical gas at a relatively low temperature and pressure, is preferably used.

In the present invention, "impregnating and adsorbing" broadly refers to putting a second component such as a polarizing element which was not originally present in a polymer film matrix into a matrix. It is. In other words, this means that the polymer film does not contain the second component when the polymer film is formed by melt extrusion or the like, and that the second component is included in the polymer film by post-processing. This refers to attaching the second component by means of impregnation or adsorption of the component.

The form of the polymer film to be treated is as follows:
In many cases, dichroic dyes do not readily impregnate the core of the roll if they are wound into a roll. A method of co-winding with a microporous film, (2) a method of unwinding and processing a film to be processed with a roll-shaped sample winding / winding device, or (3) a method of processing with a cut sample There is a method in which only a film is put into the system for processing, and in the case of the present invention, the method (1) is preferable from the viewpoint of mass processing.

It is also excellent to circulate the supercritical gas through a pressurized vessel with a pressurized pump in order to increase the contact time and the frequency of contact with the supercritical gas containing a polarizing element on the surface of the polymer substance as much as possible. Is the way. Although the processing time depends on the processing mode, it is 0.5 seconds to 1 after the supercritical state.
Time is required, especially in the case of a roll sample.

Here, the polarizing element is at least one compound selected from dichroic dyes, iodine, liquid crystal compounds and the like. In the present invention, dichroic dyes and liquid crystal compounds are particularly preferable.

Representative dichroic dyes / pigments include dichroic dyes / pigments having a biphenyl group, a naphthyl group or an anthraquinonyl group, particularly those having an anthraquinone type, perylene type or phthalone type structure. Are preferred. Specific examples of typical dichroic dyes are described in JP-A-58-68008 and JP-A-60-125804.
JP, JP-A-62-135801, JP-A-5-135801
Japanese Patent Application Laid-Open No. 11110, Japanese Unexamined Patent Application Publication No. 5-1110, and the like.

Unless a dichroic dye having a specific structure is selected, a high degree of polarization and excellent mechanical handling cannot be satisfied. In other words, if a dichroic dye having a low degree of polarization is used, the uniaxial orientation of the matrix polymer must be increased in order to increase the degree of polarization, and the resulting polarizer is apt to be broken, resulting in poor handling. Inferior, polarization property and handleability cannot be satisfied.

A liquid crystal compound is a compound that exhibits fluidity like a liquid, optically anisotropic like a solid, shows birefringence, and has properties of both a liquid and a solid. .

The amount of the polarizing element added to the polymer compound is usually 0.01 to 2% by weight, preferably 0.05 to 2% by weight.
0.5% by weight. Of course, these polarizing elements
In some cases, a combination of more than two kinds of light is preferable because it has a high degree of polarization over the entire required wavelength of light.

As the polymer compound for dispersing the polarizing element, it is preferable to use a polymer compound having a photoelastic coefficient of 30 × 10 ⁻¹² m ² / N or less and a water absorption of 0.5% or less. The glass transition temperature Tg of the resin is preferably 1
It is good to use what is 40 degreeC or more, More preferably, it is 160 degreeC or more.

This is because deformation such as shrinkage or elongation or warpage does not occur even when the processing temperature or the use temperature when assembling as a liquid crystal member is increased. Specifically, cyclic olefin copolymer (COC) (Zeonex and Zeonoa of Zeon Corporation, Arton of JSR Corporation, Appel of Mitsui Chemicals Corporation) Hydrogenated polystyrene, 4-methylpentene polymer (TPX of Mitsui Chemicals Corporation), polycarbonate (PC) , Polyarylate (PAR), polysulfone (PSu), polyethersulfone (PE
S), a polyester selected from the group consisting of polyester and modified products thereof. In the case of the present invention, in particular, a cyclic olefin copolymer (COC), a 4-methylpentene polymer, further, polypropylene terephthalate (PPT), polyethylene naphthalate Polyester compounds such as (PEN), polyethylene terephthalate (PET) and polylactic acid are preferred.

Here, the cyclic olefin copolymer is a high olefin having a norbornene skeleton and a Tg of 140 ° C. or higher.
g polyolefin, a polymer obtained by hydrogenating a polymer obtained by metathesis polymerization with a tetracyclododecene derivative or an unsaturated cyclic compound copolymerizable with the tetracyclododecene, and the like. 60-1
68708, JP-A-62-252406,
JP-A-62-252407, JP-A-63-145
No. 324, JP-A-63-264626, JP-A-2-133413, JP-A-1-240517, and JP-B-57-8815 can be used.

Particularly,-(CH ₂ ) _n C is added to the side chain of the cyclic COC.
Those having an appropriate polar group such as OOR, for example, those having about one in every two to five norbornene groups are most preferred, but many such as those having a polar group in all of the norbornene groups. When a polar group is present, the water vapor transmission rate becomes as large as 200 (g / m ² · day · 80 μm sheet) or more, and the water absorption rate and the humidity expansion coefficient β also increase, which may impair the properties as a protective function. This is an undesirable direction.

Polyarylate (PAr) is a wholly aromatic polyester, and is typically an amorphous high Tg polymer obtained from bisphenol A and an aromatic dicarboxylic acid such as terephthalic acid. Commercially available from Unitika Co., Ltd.

Hydrogenated polystyrene is a high Tg amorphous polymer in which all benzene rings of styrene have been hydrogenated to eliminate double bonds, and are commercially available from Dow.

A typical composition of polysulfone (PSu) is a polymer compound having a sulfone group consisting of bisphenol A and biphenyl sulfone.

Polyethersulfone (PES) is a polymer compound having an ether group and a sulfone group. A typical composition is polyethersulfone, which is a polymer of biphenylsulfone and oxygen. Needless to say, resins and the like selected from mixtures and modified products thereof are also included.

The polycarbonate (PC) resin is a polyester of carbonic acid and glycol or divalent phenol and has a polar group of OCOO. As a typical composition, although described in various documents, a resin having a film forming ability having a Tg of 120 ° C. or more is excellent, and examples thereof include bis (oxyphenyl) ethane (dioxydiphenylethane) and bis (oxyphenyl). ) Isobutane (dioxydiphenylisobutane), bis (oxyphenyl) cyclohexane (dioxydiphenylcyclohexane) and the like.

Needless to say, various additives such as a slipping agent, a stabilizer, an antioxidant, an ultraviolet absorber, a viscosity modifier, an antistatic agent, a colorant, and a pigment are used in combination with any of these polymer compound layers. In particular, it is preferable to add a benzophenone-based, salicylate-based, benzotriazole-based, cyanoacrylate-based, nickel complex-based, or other ultraviolet absorber.

A film formed from these polymer compounds is used as a matrix of a polarizer. The thinner the film, the smaller the thickness is 20 μm or less, preferably 10 μm or less, because the impregnating property and the degree of polarization are increased, and the film is compact. It is also excellent in handleability and is preferable.

The polymer film before the treatment in the supercritical state is preferably a uniaxially stretched film or a film having a rubbing treatment on the surface of the polymer film. As for the degree of uniaxial orientation, the higher the degree of polarization, the better the degree of polarization. Instead, a film having a high degree of amorphous orientation and a structure having an appropriate free volume is excellent, and PET, PEN, PPT In the case of a polymer having crystallinity such as polyester, a birefringence of 0.25
To 0.55, preferably a cyclic olefin copolymer (COC) having no crystal structure, hydrogenated polystyrene, 4-methylpentene polymer, polyether sulfone (PE
In the case of an amorphous polymer such as S), the higher the degree of molecular orientation, the better the degree of polarization.

Further, after the polarizing element is impregnated and adsorbed in the supercritical state, it may be stretched again in the same direction as the orientation before the impregnation to further improve the degree of polarization.

The surface of the polarizer thus obtained is subjected to plasma treatment, corona discharge treatment,
Performs surface treatments such as chemical treatment, surface roughening treatment, etching treatment, and flame treatment, and applies gas barrier coats, hard coats, antireflection coats, conductive layer coats, and even pastes retardation plates and polarization transmission improvement films. Thus, a liquid crystal display element, a touch panel element, or the like can be used.

An example of the production method of the present invention will be described below.
It is not limited to this.

The polymer resin is melted by a conventionally known single-screw, twin-screw, vented or tandem extruder, and the resin flow widened by the manifold in the die is formed into a sheet through the die land. It is molded, and the melt sheet is brought into close contact with a moving cooling medium such as a drum and cooled and solidified to obtain a polymer resin cast sheet / film. At this time, in order to minimize oxygen during melting, the resin to be melted is apt to undergo oxidative decomposition or oxidation reaction, and in order to minimize oxygen during melting, the resin is dried in a vacuum in advance to completely remove the resin. It is important to prevent the oxidation reaction of the resin by noticing, performing vacuum extrusion, or performing nitrogen displacement extrusion, and further adding an antioxidant to the resin. If not, the resin undergoes an oxidation reaction at the time of melting, and not only is the resin denatured to oxidation, gelation, or the like, and becomes a foreign substance,
The molten resin becomes very easy to adhere to a metal material such as a base, and therefore, a fixing streak called a base streak is easily generated, which may make the resin unusable for optical use. For this reason, the material in contact with the molten resin is preferably not a usual chromium plating or nitrided steel but a ceramic material such as TiN having excellent releasability or a SUS material.

The molten resin sheet is brought into close contact with a cooling drum to be cooled and solidified, but a casting method is preferred in which the center and the end of the thermoplastic resin sheet land substantially simultaneously. For this purpose, the shape of the die, the extrusion direction, the melt viscosity of the polymer, and the like are important, but the drum temperature control is also important. The molten sheet is heated to a temperature close to the glass transition temperature Tg;
It is important that the drum is kept in contact with a drum maintained at a temperature of not more than 0 ° C. and cooled without slipping. This is because when the sheet slides on the drum, molecular orientation occurs, resulting in a so-called retardation of 5 nm or more, which is not optically isotropic.

For this purpose, when the melt is brought into close contact with a cooling drum and cooled, the sheet is selected from an air knife, an air chamber, a press roll method, a liquid paraffin coating method, a static application method and the like. It is important to cast by a method such as a method for improving adhesion.

As the casting position, it is most preferable that the direction in which the molten material is extruded is extruded in the horizontal direction, and that the first contact point to the cooling drum is near the top of the cooling drum. Even if it is not necessarily such a casting position, the flow direction of the so-called land in the die and the traveling direction of the sheet extruded under the atmosphere are almost the same or a narrow angle formed by the flowing direction and the traveling direction. This is because when the angle is within 30 degrees, a surface defect called a base streak hardly occurs over time. The surface roughness Ry of the moving cooling medium is preferably 0.4 μm or less, more preferably 0.2 μm or less, with a mirror-finished roll.
Ultra-smoothness of not more than μm is important for improving adhesion and smoothness of the sheet.

However, when it is desired to cast at a high speed or the like, a rough roll having a surface roughness Ry of about 1 to 4 μm obtained by applying a reverse electric field to the chromium plating to form a microcrack drum may be used.

The total thickness of these cooled sheets can be measured by β-ray, IR absorption method or the like. The polymer resin sheet and film thus obtained can be obtained not only as a sheet and a film with little oxidative modification on the surface, but also as having no surface defects and excellent optical isotropy, as well as thickness uniformity and surface smoothness. Excellent sheets and films having a thickness of about 1 to 50 μm can be obtained.

The thus obtained polymer resin sheet or film is uniaxially stretched in the width direction or the longitudinal direction to form a sheet or film having anisotropy, and then the uniaxially oriented sheet / film is combined with a dichroic dye, A polarizing element such as iodine or a liquid crystal compound is charged into an autoclave, and carbon dioxide gas,
A polarizer having a high degree of polarization and heat and moisture resistance by impregnating and adsorbing a polarizing element on the oriented polymer sheet or film by heating and pressurizing so that gases such as oxygen, nitrogen, and air are in a supercritical state. Is to manufacture.

The surface of the polarizer thus obtained is subjected to plasma treatment, corona discharge treatment, chemical treatment, surface roughening treatment,
Surface treatment such as etching treatment and flame treatment, coating such as gas barrier coat, hard coat, anti-reflection coat, conductive layer coat, and lamination such as retardation plate and polarization transmission enhancement film etc. It can be used for applications such as touch panel elements.

[0048]

[Measurement method of physical properties] Next, the method of measuring physical properties used in the present invention will be described below. 1. Film thickness unevenness: Using a film thickness nest tester “KG601A” manufactured by Anritsu Corporation, the thickness of a film sampled 30 mm wide and 10 m long in the longitudinal direction of the film is continuously measured. The transport speed of the film was 3 m / min. The maximum thickness value Tmax (μ
m), the minimum value Tmin (μm) was used to determine R = Tmax−Tmin, and from R and the average thickness Tave (μm) having a length of 10 m, the thickness unevenness (%) was calculated as R / Tave × 100. 2. Thermal properties (Tm, Tg, Tmc): Sample weight 10 using a DSC-II type measuring device manufactured by PerkinElmer.
mg, the temperature was increased at a rate of 20 ° C./min under a nitrogen gas flow, Tg was the temperature at which baseline deviation started, and Tcc was the exothermic peak when the temperature was further increased. The peak temperature was defined as the melting point Tm. After holding at Tm + 20 ° C. for 1 minute, the melt was cooled at a cooling rate of 20 ° C./min, and the exothermic peak temperature based on crystallization was defined as Tmc. 3. Water vapor transmission rate: According to JIS-K7129 B method
It was measured at 40 ° C. and 90 RH%. Unit is g / m ² · 24
Time and sheet.

PERMATRAN-WI manufactured by MOCON
A was used. 4. Light transmittance: Total light transmittance of visible light in a wavelength range of 300 to 700 nm was measured using a spectrophotometer U-3410 (manufactured by Hitachi, Ltd.), and the light transmittance at 550 nm was adopted. 5. Retardation: The sample was set under a polarizing microscope, the sample was rotated by 45 ° from the extinction position, and the value at which the polarization interference color was eliminated by a compensator was defined as retardation. The unit is nm. 6. Adhesive force (kg / cm): strength (k) required for peeling determined by T-peel peeling test according to JIS Z0237
g) divided by the width of the test piece. 7. Degree of polarization V: two polarizers were placed in the optical path of a spectrophotometer with the molecular orientations parallel to each other and placed in the optical path of the spectrophotometer. The measured light transmittance at the maximum absorption wavelength of visible light (T =), and the two polarizers Is calculated from the light transmittance (T⊥) at the same wavelength measured by superimposing so that the molecular orientations are orthogonal to each other using the following equation.

The degree of polarization V = {[(T = -T}) / (T = +
T⊥)] × 100 (%) Photoelastic coefficient (photoelastic modulus): A sample was 20 mm wide,
Cut to length 100mm, while applying a load in the long side direction,
The retardation using a laser wavelength of 633 nm is measured and calculated from the slope of the approximate straight line. The unit is 10
⁻¹² m ² / N. 9. Water absorption: After standing at 25 ° C for 100 hours at 100 RH% for 24 hours, the equilibrium water content W of this polymer was measured using a trace moisture meter, and the weight W ₀ after absolute drying at 105 ° C for 24 hours was measured in the same manner. The water absorption weight is calculated from the following equation.

Water absorption = (W−W ₀ ) / W ₀ × 100
(%)

[0052]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples in order to make the present invention easier to understand.

Example 1 As a polymer compound, polyethylene terephthalate (PE)
Using T), according to a conventional method, the raw material is vacuum-dried to remove water and dissolved oxygen, and then supplied to a 150 mm vacuum extruder in which the space from the raw material hopper to the extruder is replaced with nitrogen to obtain 28
Melted at 5 ° C. After passing the melt through a filter for removing foreign substances of 5 μm or more, a cast having a distance of 50 mm between the LD and a T-die die having a 1200 mm wide crow die shape (set so that the resin flow direction is horizontal). Extruded on top of drum.

At this time, the narrow angle between the direction of flow of the resin at the die land and the molten resin sheet was 0 degree.

In order to improve the adhesion between the drum and the resin sheet, a mirror chrome plating drum (drum diameter: 1800) maintained at 30 ° C. while applying an electrostatic charge to the ground point
mm, maximum surface roughness Rt: 0.1 μm,
The mixture was adhered and cooled and solidified at a speed of min. The thickness of the film thus obtained is 15 μm, the thickness unevenness is as small as 3% or less in both the longitudinal direction and the width direction, and even when the frequency analysis of the thickness unevenness is caused by the landing vibration of 3 to 10 Hz. The film has no thickness unevenness, is excellent in thickness uniformity, and is excellent in flatness, and has no surface defects such as craters and base lines, and has a light transmittance of 89% or more in the range of 400 to 700 nm. The sheet was transparent and completely amorphous, and had excellent optical isotropy.

The extruded PET sheet is stretched in the width direction.
It was supplied to a tenter as a heat treatment machine, stretched 2.8 times in the width direction at a stretching temperature of 88 ° C., then cooled once to 70 ° C. or lower, and heat-set at 180 ° C. for 7 seconds. The film thus obtained is co-wound with a melt-blown nonwoven fabric having a basis weight of 2 g / m ² and a thickness of 20 μm made of a PP material and formed into two products in a roll form having a width of 1050 mm and a length of 1000 m. I took it.

This product roll and a dye can containing a dichroic dye as a polarizing element are inserted into a large autoclave, and after sealing, heating is performed so that carbon dioxide becomes supercritical (1).
(20 ° C.) and pressure (10 MPa). At this time, the treatment was performed for 30 minutes by circulating a supercritical gas with a piston in order to improve the impregnation of the two-color dye into the polymer film as much as possible.

The PET polarizer thus obtained was peeled off from the non-woven fabric, and the degree of polarization was measured to be 99.96%. Further, the polarizer is heated at 60 ° C. and 90 RH% to 700
When the polarization degree after the time treatment was measured, the polarization degree was 97.
% And excellent polarization performance.

Such an excellent polarizer can be used not only for a liquid crystal display substrate such as a mobile phone display screen or a personal computer display screen, especially for a liquid crystal display such as a large-screen color display but also for an optical display such as an organic electroluminescence (organic EL display). It can be usefully used for applications with strict characteristics. COMPARATIVE EXAMPLE 1 As used in Example 1, the stretched and oriented PET film was not impregnated with the dichroic dye in a supercritical state. After uniformly adding and blending, the mixture was melt-extruded in the same manner as in Example 1 and then closely adhered to a cooling drum and cooled, and stretched and heat-treated in the width direction to obtain a polarizer.

When the degree of polarization of the polarizer thus obtained was measured, it was 98.16%. Furthermore, when the degree of polarization of this polarizer after treatment at 60 ° C. and 90 RH% for 700 hours was measured, the degree of polarization was only 92%, indicating that the polarizer had polarization performance.

When such a polarizer is used as a liquid crystal display device, it has serious drawbacks such as poor color contrast, poor hue, and no black screen.

[0062]

According to the present invention, even when a polarizer is used as a liquid crystal display element for a long period of time under high temperature and high humidity conditions, the color contrast does not deteriorate, the hue does not deteriorate, and a blurred screen is obtained. A polarizer that realizes a beautiful screen for a long period can be manufactured.

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Claims (10)

[Claims] 1. A method for producing a polarizer, comprising producing a polarizer by impregnating and adsorbing a polarizer on a polymer film in a supercritical state. 2. The method according to claim 1, wherein the polarizing element is at least one selected from dichroic dyes, iodine and liquid crystal compounds. 3. The polymer has a photoelastic coefficient of 30 × 10 <sup>−12.
3. The</sup> method for producing a polarizer according to claim 1, wherein the polarizer has a m ² / N or less and a water absorption of 0.5% or less. 4. The method according to claim 1, wherein the polymer is a cyclic olefin copolymer (C).
OC), hydrogenated polystyrene, 4-methylpentene polymer, polycarbonate (PC), polyarylate (PA
R), a polymer selected from polysulfone (PSu), polyethersulfone (PES), polyester and modified products thereof.
Or the manufacturing method of the polarizer of 3. 5. The method according to claim 1, wherein the polymer film is a uniaxially stretched film. 6. The method according to claim 1, wherein the polymer film is a film having a rubbed surface.
5. The method for producing a polarizer according to 3 or 4. 7. The method for producing a polarizer according to claim 1, wherein the film is stretched in the same direction as the original orientation after the impregnation / adsorption. 8. A polarizer comprising a polymer film impregnated and adsorbed on a polymer film in a supercritical state. 9. The polarizer according to claim 8, wherein the degree of polarization is 99.9% or more. 10. The polarizer according to claim 8, wherein the degree of polarization after treatment at 60 ° C. and 90 RH% for 700 hours is 95% or more.