JPH0894834A - Polarizer - Google Patents

Abstract

PURPOSE: To provide a polarizer excellent in polarizing property and durability in a high temp. high humidity state. CONSTITUTION: The polyvinyl alcohol based polarizer dyed with iodine satisfies the relation of (b1 /a1 )(b0 /a0 )>=0.7 when the spectral intensity in 105cm<-1> and 157cm<-1> by Raman spectrum method at the time of irradiating the polarizer with Ar<+> laser of 514.5nm excitation wave length after treated by allowing to stand in the atmosphere of 80 deg.C and 91%RH for 200hr is respectively represented by (a1 ) and (b1 ) and the spectral intensity before the polarizer is treated by allowing to stand is respectively represented by (a0 ) and (b0 ).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol-based polarizer dyed with iodine, and more specifically, a polyvinyl alcohol-based polarizer excellent in optical properties and durability at high temperature and high humidity. Regarding

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used in desk-top electronic calculators, electronic timepieces, word processors, measuring instruments such as automobiles and machines, and accordingly, a polarizer or protective layers on both sides of the polarizer have been provided. The demand for polarizing films is also increasing. In particular, accurate measuring instruments are required to have a polarizer having a high degree of polarization, a high degree of transmission and excellent durability.

At present, one of known typical polarizers is a polyvinyl alcohol film dyed with iodine. This is an aqueous solution of polyvinyl alcohol formed into a film, which is uniaxially stretched to obtain iodine. It is manufactured by dyeing or dyeing with iodine and then uniaxially stretching, and then preferably subjected to a durability treatment with a boron compound.

[0004]

However, in the case of the conventional polyvinyl alcohol-based polarizer as described above, although the polarization performance is sufficiently good, the high temperature
Durability at high humidity is still unsatisfactory, and there is room for improvement.

[0005]

As a result of intensive studies to solve the above problems, the present inventors have found that in a polyvinyl alcohol-based polarizer dyed with iodine, the polarizer is
0 ° C., and the spectral intensity of 105 cm ^-1 and 157cm ^-1 at Ar ⁺ laser irradiation of the excitation wavelength 514.5nm by 200 hours standing after treatment of Raman spectroscopy in an atmosphere of RH 90% as a ₁ and b ₁ respectively , When the spectral intensities before the standing treatment of the polarizer are a ₀ and b ₀ , respectively,
A polarizer satisfying (b ₁ / a ₁ ) / (b ₀ / a ₀ )> 0.7 is excellent in polarization performance and durability at high temperature and high humidity, and further (b ₀ / A ₀ ) <1.1 is satisfied,
The inventors have found that the effects of the present invention can be remarkably obtained, and have completed the present invention.

When the above polarizer is left to stand in an atmosphere of 80 ° C. and 90% RH for 200 hours, an aqueous polyvinyl alcohol solution (coating dry thickness 0.01 μm) is used as an adhesive on both sides of the polarizer before the treatment. The surface was alkali-saponified to neutralize the cellulose triacetate film (8
(0 μm) was used as a sample, the sample was left standing under the above conditions, and then the sample was immersed in cyclohexanone at 20 ° C. for 12 hours to dissolve the cellulose triacetate film on both sides. The spectrum intensity of the single polarizer after completely removing the solvent adhering to the surface by air-drying or the like was taken as the spectrum intensity after the standing treatment. (In removing the cellulose triacetate film, a method of physically removing the film by scraping the film or the like is also possible.) In addition, in the measurement of the spectral intensity of the polarizer before the standing treatment, the production of the polarizer is performed. Due to the above reasons, when a protective layer such as a cellulose triacetate film is laminated on the polarizer, the protective layer is peeled off by the method described above and the spectral intensity of the polarizer alone is measured. (When the protective layer is an acrylic resin, a solvent such as acetone, benzene, or toluene may be used.) The present invention will be specifically described below.

The polarizer of the present invention is a uniaxially stretched film of a polyvinyl alcohol resin film, and the polyvinyl alcohol resin is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. The amount of unsaturated carboxylic acid (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, unsaturated sulfonates, etc.
It may contain a component copolymerizable with vinyl acetate.
Further, a polyvinyl butyral resin obtained by reacting a polyvinyl alcohol resin with an aldehyde in the presence of an acid, a so-called polyvinyl acetal resin such as a polyvinyl formal resin, and other polyvinyl alcohol resin derivatives are also included, but are not limited thereto. . Of these, PVA having a high degree of saponification and a high degree of polymerization is preferable because it has good heat resistance. That is, the degree of saponification is preferably 95 mol% or more, more preferably 97 mol% or more, particularly 99 mol% or more, and the degree of polymerization is preferably 1000 or more, more preferably 1,000 to 10,000, especially 200.
Those of 0 to 5000 are practical, but the present invention is not limited thereto.

As the method for producing the above-mentioned polarizer, a stock solution of a polyvinyl alcohol resin dissolved in water or an organic solvent is cast to form a film, which is stretched and dyed with iodine, or stretched and dyeed simultaneously, or iodine is used. A method of treating with a boron compound after dyeing and stretching may be mentioned. Examples of the solvent used in preparing the stock solution include water, as well as polyhydric compounds such as dimethyl sulfoxide (DMSO), N-methylpyrrolidone, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane. Amines such as alcohol, ethylenediamine and diethylenetriamine, and mixtures thereof are used.

The organic solvent may contain a small amount of water, for example, 5 to 30% by weight. The concentration of polyvinyl alcohol in the stock solution is practically 4 to 50% by weight. The polyvinyl alcohol film-forming stock solution obtained using the solvent is formed into a film by an arbitrary method such as a casting method or an extrusion method. The film-forming method is a dry / wet film-forming method, that is, the solution is once discharged from the mouth slit into the air or into an inert atmosphere such as nitrogen, helium, or argon, and then introduced into a coagulation bath for unstretching. Form a film. Alternatively, the film-forming solution discharged from the die may be introduced into the coagulation bath after the solvent is partially dried on a roller, a belt conveyor or the like.

The solvent used in the coagulation bath is miscible with the solvent of the polyvinyl alcohol resin, and examples thereof include alcohols such as methanol, ethanol, propanol and butanol, acetone, benzene and toluene. The polyvinyl alcohol unstretched film obtained as described above is then stretched and dyed.

The dyeing of the film, that is, the adsorption of the polarizing element is performed by bringing the liquid containing the polarizing element into contact with the film. Usually, an aqueous solution of iodine-potassium iodide is used, the concentration of iodine is 0.1 to 2 g / l, the concentration of potassium iodide is 10 to 50 g / l, and the weight ratio of iodine / potassium iodide is 20 to 100. Appropriate. Dyeing time is 3
Practical use is about 0 to 480 seconds. A small amount of an organic solvent compatible with water may be contained in addition to the water solvent.
Moreover, you may make a dye contain as needed.

As the contact means, any means such as dipping, coating and spraying can be applied. The dyed film is
Then, it is stretched in a boron compound. It is desirable that the stretching is performed in the uniaxial direction by 2.0 times or more, preferably 3 times or more. At this time, some stretching (stretching to a degree that prevents shrinkage in the width direction or more) may be performed in the direction perpendicular to the above. Boric acid and borax are practical as the boron compound. The boron compound has a concentration of 0.5 to 2 mol / l in the form of an aqueous solution or a water-organic solvent mixture.
It is practically desirable that a small amount of potassium iodide be coexistent in the liquid for practical use.

As the treatment method, the dipping method is preferable, but of course, the coating method and the spraying method can also be carried out. If necessary, a stretching operation may be performed during the treatment or after the treatment. In addition,
The treatment with the boron compound can be replaced by adding a boron compound in advance to the polyvinyl alcohol resin solution to form a film. In this way
The iodine dyed polyvinyl alcohol-based polarizer used in the present invention can be obtained. In the present invention, the film has an excitation wavelength of Raman spectroscopy after being left standing in an atmosphere of 80 ° C. and 90% RH for 200 hours. 514.5 nm
105 cm ^-1 and 157 cm at Ar ⁺ laser irradiation
^When the spectral intensities of ^-1 are a ₁ and b ₁ and the spectral intensities before the standing treatment are a ₀ and b ₀ , (b ₁ / a ₁ )
The most characteristic feature is that / (b ₀ / a ₀ )> 0.7 is satisfied, and it is necessary to satisfy the above formula by controlling the manufacturing conditions of the polarizer.

For example, a polyvinyl alcohol-based resin having a high degree of polymerization may be selected as the original fabric, or a vertical stretching may be added in the stretching process during the production of the polarizer, or the stretching may be performed in two or more stages. Alternatively, a method of performing a drying treatment after laminating a protective layer such as a cellulose triacetate film can be realized alone or in combination, but the method is not limited thereto. If the above-mentioned leaving treatment method and Raman spectroscopy are further detailed,
First, a polarizer obtained by the above-described method was used as a Raman spectrometer (for example, Jasco NR-18 manufactured by JASCO Corporation).
00M) as an excitation wavelength of 514.5 nm A
Irradiate r ⁺ laser (output 2mW), 105 at this time
cm ^-1 and measured at room temperature the spectral intensity a ₀ and b ₀ of 157cm ^-1 (measuring time; 16 sec × 5 times, measured diameter; 2
00 μm, measurement mode; backscattering). Next, after sticking the cellulose triacetate film on both sides of the polarizer as described above, after leaving it in an atmosphere of 80 ° C. and 90% RH for 200 hours, taking it out and peeling the cellulose triacetate film in cyclohexanone, The Raman spectrophotometer was used again to measure the polarizer alone at 105 cm ⁻¹ and 157 c.
The spectral intensities a ₁ and b ₁ of m ^-1 are measured.

In determining the above-mentioned spectrum intensity, the respective spectrum intensities are read from the peaks of the chart obtained by the above-mentioned measurement method. The determination of the spectrum intensity is carried out by the waveform separation method using the least square method. Waveform separation is performed assuming that each peak is a Lorentz function containing three variables (spectral position, spectrum intensity, half width) and the baseline is a linear function containing two variables (intercept, slope). It determines the strength. Further, the above-mentioned polarizer having a value of (b ₁ / a ₁ ) / (b ₀ / a ₀ ) of 0.7, which is composed of a ₀ , b ₀ , a ₁ and b ₁ , is the polarizer of the present invention. , Preferably 0.7-
It is 1.5. When the value is 0.7 or less, the durability of the polarizer is poor and the object of the present invention cannot be achieved. Further, in the present invention, when the value of (b ₀ / a ₀ ) is less than 1.1,
That is, when the condition of (b ₀ / a ₀ ) <1.1 is satisfied, high temperature
It is particularly useful because it has excellent durability in high humidity.

The polarizer of the present invention has excellent polarization characteristics and durability at high temperature and high humidity, but is usually used as a polarizing film having a protective layer on both sides or one side of the polarizer. It can be used as an elliptically polarizing plate by laminating it with a retardation film using an adhesive or the like.

In order to make the polarizer of the present invention into a polarizing film, a protective film having excellent optical transparency and mechanical strength is adhered to both sides or one side of the polarizer with an adhesive as described above, It can be a polarizing film, as the protective film, conventionally known cellulose acetate film, acrylic film, polyester resin film, polyolefin resin film, polycarbonate film, polyether ether ketone film,
A polysulfone-based film can be used, but a cellulose acetate-based film such as a cellulose triacetate film is preferable. Further, regarding the sticking of the protective layer, an adhesive containing natural or synthetic rubber, urethane resin, acrylic resin, butyral resin, epoxy resin, polyester resin, polyamide resin, polyvinyl alcohol resin, etc. as a main component. Using an agent or an adhesive, it can be attached by an air drying method, a chemical curing method, a heat curing method, a heat melting method or the like.

Usually, an acrylic pressure-sensitive adhesive layer is further provided on one surface of the polarizing film, and the polarizing film is attached to a glass substrate such as a liquid crystal display device for mounting. A known one is used as the acrylic pressure-sensitive adhesive, and as a constituent component of the acrylic resin which is a main component of the acrylic pressure-sensitive adhesive, a main monomer component having a low glass transition temperature, a soft main monomer component, and a high glass transition temperature are hard. A comonomer component and, if necessary, a small amount of a functional group-containing monomer component are included.

Specifically, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-acrylic acid acrylate
Ethylhexyl, lauryl acrylate, benzyl acrylate, cyclohexyl acrylate, etc. Alkyl alkyl esters of alkyl groups having about 2 to 12 carbon atoms, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, Benzyl methacrylate, cyclohexyl methacrylate, and other main monomer components such as alkyl methacrylate having an alkyl group of about 4 to 12 carbon atoms, and the above-mentioned comonomer components include methyl acrylate, methyl methacrylate, ethyl methacrylate, Examples thereof include methacrylic acid alkyl esters having an alkyl group having 1 to 3 carbon atoms such as propyl methacrylate, vinyl acetate, acrylonitrile, methacrylonitrile, and styrene.

In addition to the above, the functional group-containing monomer component is a monocarboxylic acid such as acrylic acid, methacrylic acid or crotonic acid, a polyvalent carboxylic acid such as maleic acid, fumaric acid, citraconic acid, glutaconic acid or itaconic acid, and Carboxyl group-containing monomers such as anhydrides, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxylpropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, and the like. In addition to hydroxyl group-containing monomers such as N-methylolacrylamide, (meth) acrylamide, dimethylaminoethyl methacrylate, glycidyl methacrylate, allyl glycidyl ether and the like can be mentioned.

Among the functional group-containing monomer components,
It is particularly preferable to use a carboxyl group-containing monomer. The content of the main monomer component cannot be unconditionally specified depending on the type and content of the comonomer component or the functional group-containing monomer component to be contained, but it is generally preferable to contain the main monomer in an amount of 50% by weight or more. . The acrylic resin of the present invention is easily produced by a method well known to those skilled in the art, such as radical copolymerization of a main monomer, a comonomer, and optionally a functional group-containing monomer in an organic solvent.

The organic solvent used for the above polymerization is
Aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. . Specific examples of the polymerization catalyst used for the radical polymerization include azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide and the like which are ordinary radical polymerization catalysts.

The above acrylic resin is mixed with 0.001 to 5% by weight of additives such as a cross-linking agent and a coupling agent (silicone, aluminum, titanium), if necessary, and finally the pressure-sensitive adhesive of the present invention. Becomes Examples of the cross-linking agent include isocyanate compounds, epoxy compounds, aldehyde compounds, amine compounds, metal salts, metal alkoxides, metal chelate compounds, ammonium salts and hydrazine compounds. The amount of the cross-linking agent to be blended is about 0.001 to 8 parts by weight with respect to 100 parts by weight of the acrylic resin.

In order to use the polarizer of the present invention for elliptically polarizing plate applications, the above-mentioned polarizing film may be used to form a laminate having a structure of polarizing film / acrylic pressure-sensitive adhesive layer / retardation film. As the retardation film, polyvinyl alcohol-based resin, saponified ethylene-vinyl acetate copolymer, polyvinyl chloride-based resin, polymethylmethacrylate-based resin, polycarbonate-based resin, polystyrene-based resin, polyester-based resin, cellulose-based resin, poly Examples include molecularly oriented films made of polymers such as acrylate-based resins, polysulfone-based resins, and polyethersulfone-based resins. Incidentally, in the above retardation film, if necessary, a protective film excellent in optical transparency and mechanical strength is attached to both sides or one side of the retardation film via an adhesive by a method similar to that of the polarizing film. You may wear it. Like the above-mentioned polarizing film, the elliptically polarizing plate also has an acrylic pressure-sensitive adhesive layer provided on the outside of the retardation film and is attached to a glass substrate such as a liquid crystal display device for mounting.

The polarizer of the present invention can be used in a polarizing film or an elliptically polarizing plate as described above, and the polarizing film or the elliptically polarizing plate is an instrument for electronic desk calculators, electronic timepieces, word processors, automobiles and machinery. Liquid crystal display devices such as sunglasses, sunglasses, eye protection glasses, stereo glasses, display elements (CR
(E.g., T, LCD) and the like, and is particularly useful for liquid crystal display devices such as measuring instruments for automobiles and machinery.

[0026]

[Operation] The polarizer of the present invention is excellent in polarization characteristics because the Raman spectroscopic measurement values before and after standing for 200 hours in an atmosphere of 80 ° C. and 90% RH show a specific relationship, and are excellent in high temperature and high humidity. It has excellent durability in the state, and has high utility value as a polarizing film or elliptical polarizing plate.It is used for electronic desk calculators, electronic watches, word processors, liquid crystal display devices such as instruments of automobiles and machinery, sunglasses, eye protection glasses, It is used for three-dimensional glasses, a reflection reducing layer for display elements (CRT, LCD, etc.), and is particularly useful for liquid crystal display devices such as measuring instruments for automobiles and machines.

[0027]

EXAMPLES Next, the polarizer of the present invention will be described in more detail with reference to Examples. The degree of polarization referred to in the present invention is expressed by the following equation. [(H ₁₁ −H ₁ ) / (H ₁₁ + H ₁ )] ^1/2 × 100 (%) where H ₁₁ is the same when the two polarizer samples are superposed on each other. Transmittance (%) measured with a spectrophotometer in the state of overlapping
H ₁ is the transmittance (%) measured in a state where the two samples are superposed so that the orientation directions of the polarizers are orthogonal to each other.

Example 1 Polyvinyl alcohol having an average degree of polymerization of 1700 and an average degree of saponification of 99.5 mol% was dissolved in water to obtain an aqueous solution having a concentration of 5.0% by weight. The solution was cast on a polyethylene terephthalate film and dried to obtain a film having a film thickness of 60 μm. This film was cut to a width of 10 cm and mounted on a chuck. Iodine 0.2 g / l, potassium iodide 6
It was immersed in an aqueous solution of 0 g / l at 30 ° C. for 4 minutes. Then, it was immersed in an aqueous solution having a composition of boric acid 70 g / l and potassium iodide 30 g / l for 5 minutes at 55 ° C., and first stretched 2.2 times and then 1.7 times, and further 1. The film was stretched 5 times, washed with water at 20 ° C. for 10 seconds, and air-dried for 24 hours to obtain a stretched film. And
Cellulose triacetate film (Fujitac F, manufactured by Fuji Photo Film Co., Ltd.) whose surface has been alkali treated and neutralized with acid in advance
T-UV 80, 80 μm thick) was applied on both sides of the stretched film using a polyvinyl alcohol adhesive (3% aqueous solution, dry coating thickness 0.01 μm) and then dried at 100 ° C. for 1 minute to obtain a polarizing film.

Next, the polarizing film was immersed in cyclohexanone at 20 ° C. for 12 hours to completely remove the cellulose triacetate film to obtain a polarizer of the present invention. The polarizer (20 mm × 20 mm) was irradiated with an Ar ⁺ laser having an excitation wavelength of 514.5 nm using a Raman spectrometer (Jasco NR-1800M manufactured by JASCO Corporation) under the conditions described in the text. 105 cm ^-1 and 157 cm
The spectrum intensity of ^-1 was measured at room temperature to be 37.8.
The values were 1 (a ₀ ) and 29.88 (b ₀ ). Furthermore, the above-mentioned cellulose triacetate film was again adhered to both sides of the polarizer as a protective layer with a polyvinyl alcohol adhesive in the same manner as in the above-mentioned method, and a three-layer laminate of cellulose triacetate / polarizer / cellulose triacetate (polarizing film ) Got. Then the 3
After the layered laminate was left standing in an atmosphere of 80 ° C. and 90% RH for 200 hours to obtain a treated three-layered laminate, the laminate was immersed in cyclohexanone at 20 ° C. for 12 hours to form the protective layer. The removed polarizer was used as a simple substance, and the Raman spectrophotometer was used to measure the polarizer again at 105 cm ⁻¹ and 157 cm.
The spectral intensity of ^-1 was measured to be 30.94 (a
₁ ) and 28.38 (b ₁ ), and from these measured values (b
₀ / a ₀₎ and _{(b 1 / a 1) /} (b 0 / a 0) was calculating the values of 0.79 and 1.16.

In order to investigate the durability of the polarizer, the above polarizing film was subjected to 500 under conditions of 65 ° C. and 95% RH.
After standing for a period of time, the single-body transmittance and the polarization degree after that were measured by a spectrophotometer to be 44.0% and 98.8%, and the single-body transmittance and the polarization degree of the polarizing film before the standing treatment were 42.8% and 42.8%. % And 99.9%, the simple substance transmittance change and the polarization degree change were 1.2% and −1.1%, respectively.

Example 2 Example 1 was repeated except that polyvinyl alcohol having an average degree of polymerization of 2600 and an average degree of saponification of 99.5 mol% was used in Example 1 except that the first draw ratio was changed to 2 in the drawing step. Perform the same operation as above, and use a Raman spectrometer to
_{When 0} , b ₀ , a ₁ and b ₁ were measured, a ₀ = 42.2
3, b ₀ = 36.32, a ₁ = 27.42, b ₁ = 22.
At 53, from these measured values, (b ₀ / a ₀ ) and (b ₁ /
The values of a ₁ ) / (b ₀ / a ₀ ) were calculated to be 0.86 and 0.95. In addition, in order to investigate the durability of the polarizer, it was left for 500 hours under the conditions of 65 ° C. and 95% RH as in Example 1, and then the single transmittance and the polarization degree were measured with a spectrophotometer. Then, 44.1% and 99.
At 1%, the single-piece transmittance and polarization degree of the polarizing film before the standing treatment were 42.3% and 99.9%, and the single-piece transmittance change and the polarization degree change were 1.8% and -0.8%. It was

Example 3 In Example 1, polyvinyl alcohol having an average degree of polymerization of 4000 and an average degree of saponification of 99.5 mol% was used, and in the stretching step, first stretched 3 times and then stretched 1.7 times 2 Example 1 except that the stretching treatment was performed only on the steps and the drying temperature after the cellulose triacetate film lamination was changed to 60 ° C.
Perform the same operation as above, and use a Raman spectrometer to measure a ₀ ,
When b ₀ , a ₁ and b ₁ were measured, a ₀ = 35.27,
b ₀ = 31.69, a ₁ = 39.63, b ₁ = 27.05
From these measured values, (b ₀ / a ₀ ) and (b ₁ / a ₁ ) /
The value of (b ₀ / a ₀ ) was calculated to be 0.90 and 0.76. In addition, in order to investigate the durability of the polarizer, it was left for 500 hours under the conditions of 65 ° C. and 95% RH as in Example 1, and then the single transmittance and the polarization degree were measured with a spectrophotometer. As a result, 44.1% and 99.3% of the polarizing film before the standing treatment had a single transmittance and a polarization degree of 4 respectively.
From 2.2% and 99.9%, the simple substance transmittance change and the polarization degree change were 1.9% and -0.6%, respectively.

Comparative Example 1 In Example 1, the stretching treatment was carried out only once, 5.6 times, and the drying temperature after lamination of the cellulose triacetate film was 60.
The same operation as in Example 1 was performed except that the temperature was changed to 0 ° C., and a ₀ , b ₀ , a ₁ and b ₁ were measured by the Raman spectrophotometer, and a ₀ = 12.15, b ₀ = 22. 92, a ₁ = 1
4.72, b ₁ = 18.73, and from these measured values (b ₀
The values of / a ₀ ) and (b ₁ / a ₁ ) / (b ₀ / a ₀ ) were calculated to be 1.89 and 0.67. Further, in order to examine the durability of the polarizer, the same as in Example 1 was used at 65 ° C. and 95 ° C.
The sample was allowed to stand under the condition of% RH for 500 hours, and then the single-body transmittance and the degree of polarization were measured by a spectrophotometer.
At 9.3% and 77.1%, the single-piece transmittance and polarization degree of the polarizing film before the standing treatment were 41.8% and 99.8%, respectively, and the single-piece transmittance change and the polarization degree change were 7.5% and It was −22.7%.

Comparative Example 2 In Example 1, polyvinyl alcohol having an average degree of polymerization of 2600 and an average degree of saponification of 99.5 mol% was used, and the stretching treatment was performed 5.1 times only once, after the cellulose triacetate film was laminated. except for changing the drying temperature to 60 ° C., the same procedure as in example 1, a ₀ by Raman spectrometer,
When b ₀ , a ₁ and b ₁ were measured, a ₀ = 28.00,
b ₀ = 38.09, a ₁ = 21.06, b ₁ = 28.64.
From these measured values, (b ₀ / a ₀ ) and (b ₁ / a ₁ ) /
The calculated values of (b ₀ / a ₀ ) were 1.36 and 0.62. In addition, in order to investigate the durability of the polarizer, it was left for 500 hours under the conditions of 65 ° C. and 95% RH as in Example 1, and then the single transmittance and the polarization degree were measured with a spectrophotometer. As a result, 49.1% and 81.3% showed that the polarizing film before the standing treatment had a single transmittance and a polarization degree of 4%.
From 1.0% and 99.9%, the change in the single transmittance and the change in the degree of polarization were 8.1% and -18.6%.

Comparative Example 3 In Example 1, polyvinyl alcohol having an average degree of polymerization of 4000 and an average degree of saponification of 99.5 mol% was used, and the stretching treatment was performed only 5.1 times, and after the cellulose triacetate film was laminated. except for changing the drying temperature to 60 ° C., the same procedure as in example 1, a ₀ by Raman spectrometer,
When b ₀ , a ₁ and b ₁ were measured, a ₀ = 34.56,
b ₀ = 41.70, a ₁ = 36.41, b ₁ = 25.46
From these measured values, (b ₀ / a ₀ ) and (b ₁ / a ₁ ) /
The value of (b ₀ / a ₀ ) was 1.21 and 0.58. In addition, in order to investigate the durability of the polarizer, it was left for 500 hours under the conditions of 65 ° C. and 95% RH as in Example 1, and then the single transmittance and the polarization degree were measured with a spectrophotometer. As a result, the single-piece transmittance and the polarization degree of the polarizing film before the standing treatment were 47.6% and 85.6%, respectively.
From 1.3% and 99.8%, the simple substance transmittance change and the polarization degree change were 6.3% and -14.2%.

[0036]

The polarizer of the present invention is 80 ° C., 90% RH.
The Raman spectroscopic measurement values before and after standing in the atmosphere for 200 hours show a specific relationship, and thus have excellent polarization characteristics and excellent durability in high temperature and high humidity conditions. Highly useful for electronic desk calculators, electronic clocks, word processors, liquid crystal display devices for measuring instruments such as automobiles and machinery, sunglasses, eye protection glasses, stereoscopic glasses, reflection reduction layers for display elements (CRT, LCD, etc.), etc. It is used and is particularly useful for liquid crystal display devices such as automobiles and measuring instruments of machinery.

Claims (2)

[Claims] 1. A polyvinyl alcohol-based polarizer dyed with iodine is irradiated with Ar ⁺ laser having an excitation wavelength of 514.5 nm by Raman spectroscopy after the polarizer is left standing in an atmosphere of 80 ° C. and 90% RH for 200 hours. 105 of the hour
The spectral strength of cm ^-1 and 157cm ^-1, respectively a
₁ and b ₁ and the spectral intensities before the polarizer standing treatment are a ₀ and b ₀ , respectively, (b ₁ / a ₁ ) / (b ₀
/ A ₀ )> 0.7 is satisfied. 2. The polarizer according to claim 1, wherein (b ₀ / a ₀ ) <1.1 is satisfied.