JP2000321432A - Polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain excellent durability without deterioration in optical characteristics and appearance in a high temp. and high humidity environment by adhering a PVA polarizer and a protective film with a polyurethane-based adhesive. SOLUTION: A PVA polarizer and a protective film consisting of a thermoplastic saturated norbornene resin are adhered with a polyurethane-based adhesive. The PVA polarizer means a PVA film or sheet having a function as a polarizer, and for example, a PVA-iodine polarizer is used which is prepared by adsorbing iodine to a PVA film and uniaxially stretching the film in a boric acid bath. As for the thermoplastic saturated norbornene resin as the protective film for the PVA polarizer, a well-known resin can be preferably used. The polyurethane-based adhesive is diluted with an org. solvent and applied so that the adhesive has a specified thickness after dried. The org. solvent is not especially specified as far as it can uniformly dissolve the resin which constitutes the adhesive, and for example, toluene is used. The dilution concn, is preferably 0.1 to 50 wt.% calculated as the solid content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polarizing plate. More specifically, the present invention relates to a polarizing plate which is used for a liquid crystal display or the like, has excellent adhesion between a polarizer and a protective film, and has excellent durability under high temperature and high humidity.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays (LCDs)
It is often used as a display device for portable information devices and vehicles, and there is a strong demand for the reliability of LCDs in high-temperature and high-humidity environments.

Conventionally, a polarizing plate used for an LCD has been used by sticking to one or both sides of a liquid crystal cell in which liquid crystal is sealed between two electrode substrates on which a transparent electrode is formed, and using stretch-oriented polyvinyl alcohol (hereinafter referred to as PVA). In general, a polarizer prepared by adsorbing iodine or a dichroic dye and having triacetyl cellulose (hereinafter referred to as TAC) adhered to both surfaces as a protective film is used.

Since the above TAC as it is has poor adhesion to a polarizer, it is difficult to use a TAC treated with alkali (hereinafter referred to as saponified T
AC). However, the saponified TAC has a high water absorption, decreases the luminous intensity in a high-temperature and high-humidity environment, causes an increase in transmittance due to fading, and generates a stress in the PVA polarizer to relax the orientation in a high-temperature and high-humidity environment. For saponification of protective film
It has been pointed out that a large phase difference occurs in C and the degree of polarization decreases.

In order to solve the above problems, various polymer films have been proposed as protective films. However, since most of these polymer films are hydrophobic, they have been used in conventional saponified TAC. It has been difficult to obtain sufficient adhesiveness with a PVA-based adhesive.

On the other hand, JP-A-5-212828 proposes a method in which a thermoplastic saturated norbornene resin is used as a protective film, and adhesion with a polarizer is heated and pressed using an acrylic pressure-sensitive adhesive. I have. However, in this method, there is a problem that the degree of polarization is reduced by a heating operation at the time of bonding, fading is unavoidable, sufficient adhesive strength is not obtained, and durability is not always sufficient. .

[0007]

SUMMARY OF THE INVENTION In view of the above, the present inventors have found that the PVA polarizer does not undergo discoloration or fading, has sufficient adhesion to a protective film, and has excellent durability under high temperature and high humidity. As a result of intensive research to obtain a polarizing plate, PV
The present inventors have found that the use of a polyurethane-based adhesive for bonding the A-polarizer to a protective film made of a thermoplastic saturated norbornene-based resin can solve the above-described problems, and have completed the present invention.

The present invention provides a polarizing plate using a thermoplastic saturated norbornene-based resin as a protective film without causing discoloration or fading of a PVA polarizer due to conventional heat compression.
An object of the present invention is to provide a polarizing plate that has excellent adhesion to a protective film and extremely excellent durability in a high-temperature and high-humidity environment.

[0009]

Means for Solving the Problems The polarizing plate of the present invention comprises a PV
The polarizer A and a protective film made of a thermoplastic saturated norbornene resin are bonded with a polyurethane adhesive.

In the present invention, the polarizing plate means a laminated film in which a plastic film or sheet is provided as a protective film on both sides of a PVA film having a function of a PVA polarizer.

The PVA polarizer means a PVA film or sheet having the function of a polarizer.
PVA / iodine polarizer uniaxially stretched in a boric acid bath after adsorbing iodine on a VA film; PVA / dye-based polarized light uniaxially stretched after diffusing and adsorbing a highly dichroic direct dye on the PVA film Film: a PVA / polyvinylene-based polarizing film having a polyvinylene structure formed by adsorbing iodine on a PVA film and stretching.

In the above-mentioned PVA polarizer, the PVA film or sheet having the function of a polarizer is obtained by stretching a PVA-based film or sheet. PVA is usually obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. However, in the present invention, vinyl acetate is not limited thereto, and a small amount of unsaturated carboxylic acid (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, A copolymerizable component such as a saturated sulfonate may be copolymerized.

The saponification degree is usually preferably from 85 to 100 mol%, more preferably from 98 to 100 mol%.
Further, the average degree of polymerization is not particularly limited as long as the degree of polymerization is such that a film or sheet can be formed and the function of the polarizer is exhibited by stretching, but it is usually preferably 1000 or more, more preferably about 1500 to 5000. It is. P
VA polarizers are manufactured using these PVAs in a conventional manner.

The protective film made of the above-mentioned thermoplastic saturated norbornene resin only needs to be laminated on at least one surface of the PVA polarizer, and a film having high transparency can be provided on the other surface. Of course, a thermoplastic saturated norbornene-based resin may be used on both surfaces of the polarizer.

[0015] At least one surface of the PVA polarizer to which the thermoplastic saturated norbornene resin must be bonded is a surface on the liquid crystal cell side, which has a phase difference under high temperature and high humidity unless the protective film is used. This is because the change cannot be suppressed.

However, since the surface on the opposite side of the polarizer is not affected by the effect of birefringence, the protective film does not necessarily have to be a thermoplastic saturated norbornene resin.
There is no particular limitation as long as the film has high transparency. For example, polycarbonate (PC), polysulfone (PS
u), polyarylate, polyether sulfone, polyethylene terephthalate (PET), polystyrene, PM
Films such as MA and poly-α-methylstyrene are used, and films made of a copolymer containing these monomer units can also be used.

The thermoplastic saturated norbornene resin as the protective film of the PVA polarizer is disclosed in, for example,
It is a known resin disclosed in, for example, JP-A No. 14882, JP-A-3-122137, and the like. In the present invention, these conventionally known thermoplastic saturated norbornene resins can be suitably used.

Examples of the monomers constituting the above-mentioned thermoplastic saturated norbornene resin include, for example, norbornene,
5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-2
-Norbornene, 5,5-dimethyl-2-norbornene, 5-cyano-2-norbornene, 5-methyl-5
Methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-
Norbornene, ethylene-tetracyclododecene copolymer, 6-methyl-1,4: 5,8-dimethano-1,4,
4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-dimethano-1,4
4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-ethylidene-1,
4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimetano-1,
4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,
4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimetano-1,
4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octa Hydronaphthalene, 1,4-dimethano-1,4,4a, 4
b, 5,8,8a, 9a-octahydrofluorene,
5,8-methano-1,2,3,4,4a, 5,8,8a
-Octahydro-2,3-cyclopentadienonaphthalene, 4,9: 5,8-dimethano-3a, 4,4a, 5,
8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3
a, 4,4a, 5,5a, 6,9,9a, 10,10
a, 11,11a-Dodecahydro-1H-cyclopentaanthracene.

The above-mentioned thermoplastic saturated norbornene resin is
For example, (a) a resin obtained by subjecting a ring-opening polymer or a ring-opening copolymer of a norbornene-based monomer to modification such as maleic acid addition or cyclopentadiene addition, if necessary, followed by hydrogenation, (b) norbornene-based resin A resin obtained by addition polymerization of a monomer; (c) a resin obtained by addition polymerization of a norbornene-based monomer and an olefin-based monomer such as ethylene or α-olefin; (d) a norbornene-based monomer and cyclopentene, cyclooctene, 5,6-dihydro Resins obtained by addition polymerization of a cyclic olefin monomer such as dicyclopentadiene, and modified products of these resins.

In the above polymerization, for example, I
r, Os, Ru trichloride hydrate, MoC₁₅, W
C₁₆, ReCl_Five, (C_TwoH_Five)_ThreeAl, (C_TwoH_Five)_ThreeA
1 / TCl _Four, (Π-C_FourH₇)_FourMo / TiCl_Four,
(Π-C_Four H₇)_FourW / TiCl_Four, (Π-C_ThreeH_Five)_ThreeC
r / WCl₆Can be carried out by a standard method.
You.

As the above-mentioned thermoplastic saturated norbornene resin, for example, ZEONO (trade name) manufactured by Zeon Corporation
R "," ZEONEX ", product name" ARTON "from JSR," APE "from Mitsui Petrochemical Company
L] etc. are on the market.

As the number average molecular weight of the thermoplastic saturated norbornene resin decreases, the moisture resistance decreases and the moisture permeability increases, and as the number average molecular weight increases, the film moldability decreases. Therefore, gel permeation chromatography with a toluene solvent is used. (GPC), 25,000-10
It is preferably 10,000, and more preferably 30,000 to 80,000.

As the method for producing the protective film comprising the thermoplastic saturated norbornene-based resin, any known method may be employed, and examples thereof include a solution casting method and a melt molding method. preferable.

In order to form a film by the solution casting method, first, a high boiling solvent such as toluene, xylene, ethylbenzene, chlorobenzene, triethylbenzene, diethylbenzene, isopropylbenzene or the like, or a mixture of these high boiling solvents with cyclohexane, benzene, Tetrahydrofuran,
The above-mentioned thermoplastic saturated norbornene-based resin is preferably mixed with a mixed solvent of a low boiling point solvent such as hexane and octane in an amount of 5 to 60.
It melt | dissolves so that it may become wt%, and a resin solution is obtained.

Next, the obtained resin solution is applied to a bar coater.
It is cast on a heat-resistant film such as polyethylene terephthalate, a steel belt, a metal drum, or the like using a doctor knife, a Meyer bar, a roll, a T-die, a comma coater, and the like, and dried by heating.

Examples of the melt molding method include melt extrusion methods such as T-die and inflation, calender molding, hot press molding method, and injection molding method.

The thickness of the protective film made of the thermoplastic saturated norbornene resin is usually preferably from 5 to 500 μm, more preferably from 10 to 150 μm, and still more preferably from 15 to 100 μm. If the thickness of the protective film is too thin, there is a problem that the strength is reduced and the curl is increased in a durability test of the polarizing plate. Conversely, if the thickness of the protective film is too thick, the transparency decreases, the birefringence increases,
There are problems such as a decrease in moisture permeability and a delay in drying of an aqueous adhesive described later. When the birefringence increases, there occurs a problem that the contrast is reduced in a liquid crystal display.

In order to improve the heat resistance, ultraviolet light resistance, smoothness, etc. of the film, the protective film made of the above-mentioned thermoplastic saturated norbornene resin is not impaired within the range not impairing the effects of the present invention. Antioxidants such as phenols; antistatic agents such as amines; lubricants such as esters of aliphatic alcohols, partial esters or partial ethers of polyhydric alcohols; benzophenones, benzotriazoles, and acrylonitrile UV-absorbing agents such as UV-based nonionic surfactants; leveling agents such as special acrylic resin-based and silicone resin-based; and other various additives.

The above-mentioned thermoplastic saturated norbornene resin and P
For adhesion to the VA polarizer, a polyurethane adhesive is used. The polyurethane adhesive may be a solvent system using an organic solvent as a diluent, or an aqueous system such as an emulsion using water as a diluent, a colloidal dispersion, or an aqueous solution.

The solvent-based polyurethane adhesive is applied after being diluted with an organic solvent so as to have a predetermined thickness after drying. The organic solvent is not particularly limited as long as the resin constituting the adhesive is uniformly dissolved, for example, toluene,
Methyl ethyl ketone, ethyl acetate and the like can be mentioned. The dilution concentration may be appropriately adjusted depending on the thickness after drying, the appearance of coating, and the like, but preferably the solid concentration is 0.1 to 50% by weight.
It is.

The water-based polyurethane adhesive is diluted with water and applied so as to have a predetermined thickness after drying.
As the diluting solution, a solution obtained by adding an organic solvent to water may be used. Examples of the organic solvent added to water include, for example, n
Alcohols such as butyl alcohol and isopropyl alcohol; ketones such as acetone. The organic solvent is preferably added in order to improve the smoothness and drying property of coating, and the content of the organic solvent is preferably not more than 40% by weight based on the coating solution. The dilution concentration may be appropriately adjusted depending on the thickness after drying, the appearance of the coating, and the like, and is preferably 0.1 to 50% by weight of the solid content.

The polyurethane-based adhesive has a terminal NC.
There is a one-pack type composed of a compound having an O group, and a two-pack type composed of a main agent having a terminal OH group and a curing agent having an NCO group, and is not particularly limited in the present invention. Is preferred.

Examples of the main agent having a terminal OH group include low molecular weight polyols having a molecular weight of 1000 or less, polyether polyols, polyester polyols, and other O
H-based raw materials can be used. Specific examples are shown below, but one or more of these can be used in combination.

Examples of the low molecular polyol include:
Ethylene glycol (EG), diethylene glycol (DEG), dipropylene glycol (DPG), 1,
4-butanediol (1,4-BD), 1,6-hexanediol (1,6-HD), neopentyl glycol (NPG), trimethylolpropane, and the like.

Examples of the above polyether polyol include polyethylene glycol, polyoxypropylene glycol, ethylene oxide / propylene oxide copolymer, polytetramethylene ether glycol and the like.

Examples of the polyester polyol include poly-β-methyl-δ-valerolactone, polycaprolactone, and polyesters from diols / dibasic acids (diols include, for example, EG, DEG, DPG, 1,
4-BD, 1,6-HD, NPG and the like, and dibasic acids include, for example, adipic acid, azelaic acid, sebacic acid,
Isophthalic acid, terephthalic acid, etc.).

Other OH-based raw materials include, for example, castor oil, liquid polybutadiene, epoxy resin, active hydrogen compounds such as polycarbonate diol, acrylic polyol, and neoprene.

Among the above main agents, polyester resins which are polyester polyols are preferable. Examples of such commercially available products include "TM-59" as a solvent system.
3, "TM-225A", "AD-585" (all manufactured by Toyo Morton Co., Ltd.), "Dick Dry LX-903"
(Manufactured by Dainippon Ink and Chemicals, Inc.), and an aqueous system such as “EL-436A” (manufactured by Toyo Morton Co., Ltd.).

The curing agent having an NCO group only needs to have a polyisocyanate structure.
There are NCO modifications. Examples of the NCO monomer include tolylene diisocyanate (TDI), diphenylmethane isocyanate (MDI), hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), and isophorone diisocyanate (IPD).
I), tris (isocyanatephenylmethane), tris (isocyanatephenyl) thiophosphate and the like. Examples of the NCO-modified product include the above-mentioned compound adducts such as trimethylolpropane, HDI burette, HDI trimer, IPDI trimer, urethane prepolymer having an isocyanate terminal, and the like. These curing agents can be used alone or in combination of two or more.

Commercially available curing agents include, for example, "CAT-56", "CAT-RT85",
Examples include “CAT-10”, “TM-225B” (manufactured by Toyo Morton Co., Ltd.), “Dick Dry KL-75” (manufactured by Dainippon Ink and Chemicals), “Takenate A-3” (manufactured by Takeda Pharmaceutical Co., Ltd.), and the like. Examples of the water system include "EL-436B" (manufactured by Toyo Morton Co., Ltd.).

In the polyurethane-based adhesive, two or more of the above-mentioned main agents and curing agents may be used. Examples of additives that can be added to the adhesive include, for example, coupling agents such as silane coupling agents and titanium coupling agents; adhesives such as terpene resins, phenol resins, terpene-phenol resins, rosin resins, and xylene resins. Imparting agents; inorganic fillers such as calcium carbonate, clay, titanium oxide and carbon black; thixotropic agents such as aerosil and disvalon; stabilizers such as ultraviolet absorbers, antioxidants, heat stabilizers and hydrolysis stabilizers. And the like.

If the thickness of the adhesive, that is, the thickness of the adhesive layer between the polarizer and the thermoplastic saturated norbornene-based resin, is too small, the adhesive force becomes insufficient and causes peeling.
If it is too thick, transparency is impaired, which is not preferable. The preferred thickness of the adhesive after drying is 0.01 to 50 μm, and more preferably 0.1 to 30 μm.

As a means for improving the adhesive strength of the above adhesive, a thermoplastic saturated norbornene resin may be subjected to a surface treatment such as a corona treatment.

The method of laminating the PVA polarizer and the protective film may be either wet lamination or dry lamination. However, in the case of a solvent-based adhesive, dry lamination has better adhesion strength. In the case of a water-based adhesive, it is preferable to employ a wet lamination since the conventional polarizing plate manufacturing process can be used as it is.

In the case of wet lamination, for example, in consideration of the thickness after drying, the smoothness of coating, etc., urethane is bonded with water so as to have an appropriate solid content concentration (for example, 0.1 to 50% by weight). After diluting the agent, apply it to the polarizer with a Mayer bar, gravure coater, micro gravure coater, etc., or drip it, laminate it with a protective film while ironing excess adhesive with a roll, and dry with hot air And a method of bonding.

In the case of dry lamination, for example, the urethane adhesive is diluted with a diluting solvent so as to have an appropriate solid content in consideration of the thickness after drying, the smoothness of coating, etc. Coat and dry the polarizer with a roll coater, gravure coater or the like. Drying of the adhesive can be performed by setting the drying temperature in a range from normal temperature to 130 ° C. using a means such as passing through a drying furnace. Lamination with a protective film is performed using a roll at 1 to 10 kg /
The film can be pressed at a pressure of ² cm ² , and if the optical change of the polarizer does not occur at this time, the film may be heated at a temperature of 120 ° C. or less, preferably at 30 to 100 ° C.

The polarizing plate of the present invention uses a thermoplastic saturated norbornene-based resin to maintain good durable optical change characteristics and to improve the adhesion between the PVA polarizer and the protective film, which was a conventional problem, to a polyurethane-based resin. It is an excellent polarizing plate which is improved by using an adhesive and has durability which can prevent foaming and peeling of the protective film under heat and moisture and heat resistance test conditions. Furthermore, the shrinkage of the polarizer is also suppressed,
The decrease in the degree of polarization can also be improved.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described more specifically with reference to the following examples. The present invention is not limited only to the following examples.

Preparation of Polarizer An unstretched PVA film having a saponification degree of 99% and a thickness of 75 μm was washed with water at room temperature, and then stretched 5 times uniaxially. While maintaining the tension of the film, 0.5
The dichroic dye was adsorbed by immersion in an aqueous solution containing 5% by weight of potassium iodide and 5% by weight of potassium iodide. Furthermore, boric acid 10wt
% And potassium iodide of 10 wt% at 50 ° C. for 5 minutes to obtain a PVA polarizer.

Preparation of Acrylic Adhesive and Non-Support Tape 94.8 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid and 0.2 parts by weight of 2-hydroxyethyl methacrylate were added to 0.3 parts by weight of benzoyl peroxide. In the presence, copolymerization was carried out using ethyl acetate as a solvent, and the weight average molecular weight (Mw)
1.2 million, the ratio between the weight average molecular weight and the number average molecular weight (Mw
/Mn)=3.9 to obtain an ethyl acetate solution of an acrylic polymer.

Toluene is added to and diluted with the above-mentioned acrylic polymer in ethyl acetate solution to make a 13 wt% toluene solution of the above-mentioned acrylic polymer. An isocyanate crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) 2
A solution obtained by adding a part by weight and stirring is applied on a release film, and at a temperature of 60 ° C. × 5 minutes and a temperature of 100 ° C. × 5 to prevent foaming.
After two-minute drying, a release film of a light release type is further laminated on the adhesive surface and temporarily fixed, and two types of non-support tapes having a thickness (average value) of 20 μm and 25 μm after drying are obtained. Produced.

Preparation of protective film Thermoplastic saturated norbornene-based resin film (1) Ethylene-tetracyclododecene copolymer (trade name: APEL # 6015, manufactured by Mitsui Petrochemical Co., Ltd .; hereinafter APE)
L) in a 30 wt% cyclohexane solution,
The resin was cast on a PET substrate, dried at 60 ° C. for 5 minutes and dried at 120 ° C. for 5 minutes in two stages, and then peeled off from the substrate to obtain a thermoplastic saturated norbornene resin film (1). The thickness after drying was 50 μm.

Thermoplastic saturated norbornene resin film (2) A 30 wt% toluene solution of a hydrogenated ring-opening polymer of a norbornene monomer (trade name: ZEONEX # 490K, manufactured by Zeon Corporation) is prepared. And cast on a PET substrate at 60 ° C. for 5 minutes at 120 ° C.
After drying in two stages for 5 minutes, the film was peeled off from the substrate to obtain a thermoplastic saturated norbornene resin film (2).
The thickness after drying was 50 μm.

Thermoplastic saturated norbornene resin film (3) Hydrogenated ring-opening polymer of norbornene monomer (JS
R ARTONH) was prepared at 35 wt% in toluene and cast on a PET substrate at 60 ° C. for 5 minutes for 120 minutes.
After drying in two stages for 5 minutes at ℃, peeled off from the substrate,
A thermoplastic saturated norbornene resin film (3) was obtained. The thickness after drying was 50 μm.

Polycarbonate (PC) resin film PC resin (trade name: Panlite L-1 manufactured by Teijin Chemicals Ltd.)
225ZE ") in a 30 wt% methylene chloride solution, cast on a PET substrate, dried at 60 ° C. for 5 minutes, 100 ° C. for 5 minutes, and 130 ° C. for 5 minutes, and then peeled off from the substrate Thus, a polycarbonate (PC) resin film was obtained. The thickness after drying was 50 μm.

Polysulfone (PSu) Resin Film A 30 wt% anisole solution of PSu resin (trade name: UDEL, P-3500, manufactured by Teijin Amoko Engineer Plastics Co., Ltd.) was prepared, cast on a PET substrate, and cast at 60 ° C. for 5 hours. For 5 minutes, 120 ° C. for 5 minutes, and 170 ° C. for 5 minutes, and then peeled off from the substrate.
u) A resin film was obtained. The thickness after drying was 50 μm.

Surface treatment of protective film The surface of the polarizer of each of the above films was applied with 40 W / m ^2.
/ Min corona treatment.

Example 1 An isocyanate-based curing agent solution (trade name: CAT-56, manufactured by Toyo Morton Co.) was added to 100 parts by weight of a polyester resin solution (trade name: TM-593, manufactured by Toyo Morton Co.). After blending 18 parts by weight, the mixture was diluted with ethyl acetate so that the solid content concentration became 30% by weight to obtain a polyurethane adhesive solution. After applying this adhesive solution to the PVA polarizer with a bar coater,
It dried at 1 degreeC for 1 minute, and provided the adhesive layer of thickness 3 micrometers after drying. The above-mentioned thermoplastic saturated norbornene-based resin film (1) was heat-laminated on the pressure-sensitive adhesive layer of the polarizer using a roll heated to 80 ° C. to form a laminate of the polarizer / thermoplastic saturated norbornene-based resin film (1). I got Separately,
The above-mentioned adhesive solution is applied to another thermoplastic saturated norbornene-based resin film (1) under the same conditions as above and dried to form an adhesive layer having a thickness of 3 μm, and the polarizer / thermoplastic saturated norbornene-based resin thus obtained is obtained. On the polarizer side of the resin film (1) laminate, heat lamination was performed under the same conditions as described above to obtain a polarizing plate. The polarizing plate was further cured at 40 ° C. for 2 days and then used for evaluation.

Example 2 An isocyanate-based curing agent solution (trade name: TM-225B manufactured by Toyo Morton Co., Ltd.) was added to 16 parts by weight of a polyester resin solution (trade name: TM-225A manufactured by Toyo Morton Co., Ltd.). After mixing 1 part by weight, the mixture was diluted with ethyl acetate to a solid content concentration of 30 wt% to obtain a polyurethane adhesive solution. After applying this adhesive solution to the PVA polarizer with a bar coater,
It dried at 1 degreeC for 1 minute, and provided the adhesive layer of 5 micrometers in thickness after drying. The above-mentioned thermoplastic saturated norbornene-based resin film (2) is heat-laminated on the pressure-sensitive adhesive layer of the polarizer using a roll heated to 80 ° C. to form a laminate of the polarizer / thermoplastic saturated norbornene-based resin film (2). I got Separately,
The adhesive solution is applied to another thermoplastic saturated norbornene-based resin film (2) under the same conditions as above and dried to form an adhesive layer having a thickness of 5 μm, and then the polarizer / thermoplastic saturated norbornene-based resin obtained above is obtained. On the polarizer side of the resin film (2) laminate, heat lamination was performed under the same conditions as above to obtain a polarizing plate. The polarizing plate was further cured at 40 ° C. for 2 days and then used for evaluation.

Example 3 An isocyanate-based curing agent solution (trade name: CAT-10, manufactured by Toyo Morton Co.) was added to 100 parts by weight of a polyester resin solution (trade name: AD-585, manufactured by Toyo Morton Co., Ltd.). After blending 8 parts by weight, dilute with ethyl acetate so that the solid concentration becomes 30 wt%,
A polyurethane adhesive solution was obtained. This adhesive solution was applied to the PVA polarizer using a bar coater, and then dried at 80 ° C. for 1 minute to provide an adhesive layer having a thickness of 7 μm after drying. The PC resin film was thermally laminated to the pressure-sensitive adhesive layer of the polarizer using a roll heated to 80 ° C. to obtain a laminate of the polarizer / PC resin film. Separately, the above-mentioned adhesive solution is applied to another thermoplastic saturated norbornene-based resin film (1) under the same conditions as above and dried to form an adhesive layer having a thickness of 7 μm. The laminate was heat-laminated on the polarizer side under the same conditions as above to form a polarizing plate. The polarizing plate was further cured at 40 ° C. for 2 days and then used for evaluation.

Example 4 Polyester resin solution (trade name: Dick Dry LX-9, manufactured by Dainippon Ink and Chemicals, Inc.)
03)) 1 part by weight of an isocyanate-based curing agent solution (product name: KL-75 manufactured by Dainippon Ink and Chemicals, Inc.) was blended with 8 parts by weight, and diluted with ethyl acetate so that the solid content concentration became 30 wt%. Thus, a polyurethane adhesive solution was obtained. This adhesive solution was applied to the PVA polarizer using a bar coater, and then dried at 80 ° C. for 1 minute.
m of the adhesive layer was provided. The PSu resin film was heat-laminated on the pressure-sensitive adhesive layer of the polarizer using a roll heated to 70 ° C. to obtain a laminate of the polarizer / PSu resin film. Separately, the above-mentioned adhesive solution is applied to another thermoplastic saturated norbornene-based resin film (1) under the same conditions as above and dried to form an adhesive layer having a thickness of 10 μm, and the polarizer / PSu resin film already obtained The laminate was heat-laminated on the polarizer side under the same conditions as above to form a polarizing plate. The polarizing plate was further cured at 40 ° C. for 2 days and then used for evaluation.

(Example 5) 100 parts by weight of a polyester resin (trade name: EL-436A, manufactured by Toyo Morton Co.) and 30 weight parts of an isocyanate-based curing agent (trade name: EL-436B, manufactured by Toyo Morton Co.) After blending the parts, the mixture was diluted with water so that the solid content concentration became 10 wt%, applied to the thermoplastic saturated norbornene resin film (3) with a Meyer bar # 8, and wet-laminated on one surface of the PVA polarizer. Similarly, on the other side of the PVA polarizer,
A polarizing plate was obtained by wet laminating a thermoplastic saturated norbornene resin film (3). The polarizing plate was left in a thermostat at 45 ° C. for 72 hours, and water of the urethane-based adhesive was dried and cured. The thickness of the adhesive layer after curing was 1 μm.

(Comparative Example 1) The release film on the light release side of a 20 μm-thick non-support tape having an acrylic pressure-sensitive adhesive layer prepared above was peeled off, and the PVA polarizer was heated to 80 ° C.
For heat lamination. Next, the remaining release film was peeled off, and a thermoplastic saturated norbornene-based resin film (1) was thermally laminated on the peeled surface under the same conditions to obtain a laminate. Further, a thermoplastic saturated norbornene-based resin film (1) was laminated on the other polarizer surface of the laminate under the same conditions to obtain a polarizing plate.

Preparation of Evaluation Test Specimen and Durability Test The side of the thermoplastic saturated norbornene resin film of the polarizing plate of each of the above Examples and Comparative Examples was lightly peeled off from the non-support tape of 25 μm acrylic adhesive prepared above. Was peeled off and laminated to produce a polarizing plate pressure-sensitive adhesive sheet. 11. The polarizing plate pressure-sensitive adhesive sheet is subjected to a Thomson punching machine so that the angle of the absorption axis of the polarizer forms an angle of 45 degrees with the side.
I punched a 1-inch rectangle. Further, the remaining release film was peeled off, and the adhesive surface was affixed to 1.2 mm thick soda lime glass using a desktop laminator. The attached glass plate is left at room temperature for 1 hour and then at 50 N / cm ² for 2 hours.
An autoclave treatment was performed for 0 minutes, and after completion, the sample was allowed to stand at room temperature for 1 hour, and subjected to a durability test (left at 90 ° C. dry for 500 hours, and left at 60 ° C. and 95% RH for 250 hours).

After the durability test, the degree of polarization and the color difference were measured to evaluate the optical characteristics, and the appearance characteristics were evaluated by visual observation. The degree of polarization and color difference were measured at the midpoint of each of the four sides of the 12.1 inch test piece and at a position 10 mm from the end,
The average value of these four points was determined. The degree of polarization is JIS K7
The total light transmittance was measured in accordance with No. 105, and the degree of polarization was determined by the following equation. Degree of polarization (%) = {(Y ₀ −Y ₉₀ ) / (Y ₀ + Y ₉₀ )}
^1/2 × 100 (where Y ₀ is the total light transmittance when the parallel axes of the two polarizing plates are aligned in parallel, and Y ₉₀ is when the parallel axes of the two polarizing plates are orthogonalized. The color difference is measured in accordance with JIS Z 8729 at each point with a C light source, and the color difference is calculated using a Hunter's color difference formula (E _H ).
It was calculated from the L, a, and b values. The results are shown in Table 1.

[0066]

[Table 1]

From Table 1, it can be seen that the examples of the present invention show stable polarization degree and color difference in any of the durability tests.
In addition, it can be seen that there is no problem in appearance characteristics, and that it has extremely excellent durability.

[0068]

The polarizing plate of the present invention is as described above,
It has excellent optical properties, does not deteriorate optical properties and appearance properties even under high temperature and high humidity, and has excellent durability.

Claims (3)

[Claims] 1. A polarizing plate, wherein a polyvinyl alcohol polarizer and a protective film made of a thermoplastic saturated norbornene resin are adhered with a polyurethane adhesive. 2. The polarizing plate according to claim 1, wherein the polyurethane-based adhesive is of a two-component type, and the main component is made of a polyester-based resin. 3. The polyurethane adhesive according to claim 1, wherein the polyurethane adhesive is an aqueous polyurethane adhesive.
The polarizing plate of the above.