JPH0259703A - Phase difference plate - Google Patents

Abstract

PURPOSE:To obtain a composite polarizing plate applicable to new applications including a liquid crystal display device by using a thermoplastic high-polymer film or sheet formed by uniaxial stretching. CONSTITUTION:The thermoplastic high-polymer film or sheet is uniaxially stretched to confine the value of retardation within a 80 to 1,200nm range, the deviation width of the retardation to <=10% and the change rate thereof to <=1.8%/cm. Further, the excellent phase difference plate which is optically free from unequal colors is obtd. by using the raw film or sheet having <=0.1%, more preferably <=0.05% deviation width of thickness and preferably <=0.007%/cm change rate thereof. The composite polarizing plate is formed by laminating this phase difference plate on a polarizing plate. The phase difference plate which allows black and white display when used in new applications such as applications of the liquid crystal display body and has improved display quality is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application on III) The present invention relates to a retardation plate that can be applied to liquid crystal display devices and the like.

[Prior art]

A retardation plate is a film or sheet-like material that has birefringence. Since the light transmitted through the retardation plate has different refractive indexes in two directions perpendicular to each other, a phase difference occurs between the orthogonal rays after passing through the retardation plate.

As a retardation plate, there is a so-called 174λ plate which has a function of producing a phase difference of 1/4λ with respect to the wavelength λ of an incident light beam, which is currently commercially available and available in practical quantities. This one
The 74λ plate is a cellulose acetate film subjected to uniaxial general stretching treatment. When a 1/4λ plate is laminated at a 46-degree angle with respect to the optical principal axis of a linear polarizer, it becomes a circularly polarizer and has an anti-glare function that cuts reflected light.
It is used in various anti-glare materials including VDT filters.

In addition to the above-mentioned cellulose resin, vinyl chloride resin (Japanese Patent Publication No. 46
-84477, JP-A-56-Is! 5702, etc.), polycarbonate resin (Special Publication No. 41-1!1)
90, JP-A-56-180708, etc.), acrylonitrile resins (JP-A-56-18074, No. 1, etc.), styrene resins (JP-A-66-126,708, etc.)
(Japanese Patent Application Laid-Open No. 60-245), polyolefin resin
No. 02, etc.) have been proposed, but all of them are so-called 1/4λ plates with a measured retardation value of around 185 nm. Furthermore, the retardation value (R value)
and.

is expressed as the product of the thickness d of the film or sheet and the birefringence Δn of the film, that is, R-, Δnxd.

On the other hand, JP-A-61-186987, JP-A-60-
As described in Japanese Patent Publication No. 26822, a liquid crystal display device (in which the twist angle of liquid crystal molecules is 90 degrees and a pair of 1ζ polarizing plates above and below a liquid crystal cell are arranged so that their absorption axes are perpendicular or parallel) Generally called a TN type liquid crystal display device,
Attempts have also been made to improve display quality by applying retardation plates to watches, calculators, etc.

Furthermore, in recent years, with the increase in display capacity and the demand for enlarged display screens, the twist angle of liquid crystal molecules has been increased to 90 degrees or more, that is,
A liquid crystal display device with an angle of about 180 to 270 degrees has been developed (generally referred to as an STN type liquid crystal display device). However, black-and-white display, which was possible with conventional TN-type liquid crystal display devices, is no longer possible with STN-type liquid crystal display devices due to coloring caused by birefringence of liquid crystal molecules. - For example, the background color is yellow-green and the display color is dark blue. If the display device has such hue, multicolor
In order to solve this problem, which is often subject to restrictions when performing full-color display, for example, as described in Nikkei Microdevice October 1987 issue, p. A method is shown in which an additional achromatic liquid crystal cell is added to the liquid crystal cell as an optical compensator to solve the problem of coloring and enable black-and-white display.

[Problem to be solved by the invention]

The method of adding another achromatic liquid crystal cell to the STN type liquid crystal cell described above as an optical compensation plate eliminates coloring and makes black and white display possible, but (1) it is expensive and less economical;
There are problems such as (2) weight and (3) thickness, and in addition to improving the display performance described above, it is required to solve these problems in combination.

It is also possible in principle to use a retardation plate instead of the achromatic liquid crystal cell, but with the conventional 1/4λ plate, (1) the retardage value does not match optically. (
2) The optical axis is not constant.

(3) Due to the large optical color unevenness (uniform black and white display cannot be achieved), it cannot be applied to new uses such as the above-mentioned liquid crystal display device.

[Means to solve the problem]

The present invention was completed as a result of repeated research in view of the above points, and is as follows.

That is, the present invention is a film or sheet formed by uniaxially stretching a thermoplastic polymer film or sheet, which has a retardation value in the range of 80 to 1200 nm, and has a retardation amplitude of 10% or less. The present invention relates to a retardation plate characterized in that the rate of change is 1.85%/em or less, and a composite polarizing plate formed by laminating the retardation plate as a polarizing plate I2.

The retardation plate of the present invention relates to a new retardation plate Cζ that has an appropriate retardation value and optically has little color unevenness. The retardation value used is in the range of 80 to 1,200 nm, preferably adjusted to the range of 200 to 10,001 m. An appropriate retardation value is selected depending on the specific application. For example, retardation values in the range of 200 to 850 nm and those in the range of 476 to 6251 m can be exemplified for use in liquid crystal display devices.

Further, in the present invention, the amplitude of fluctuation (Δk) of the retardation value of the retardation plate is 10% or less, preferably 7% or less, more preferably 6% or less, and the rate of change thereof (G) is 1.8%/cm or less, preferably 1.0%
It has been found that by controlling ζ to less than /d, more preferably 0.6%/ax or less, it is possible to obtain an excellent retardation plate that is optically free from color unevenness.

Furthermore, in order to obtain a retardation plate with optically uniform color as described above, it is preferable that the thickness accuracy of the thermoplastic polymer membrane or sheet used be as uniform as possible;
Specifically, 0ζ has a variation width (ΔX) of thickness (J) of 0.1#
below, preferably 0.07 Jl or less, more preferably 0.06 J or less, and the rate of change (G'
) is 0.0161/ell or less, preferably 0.01
2x/a1 or less, more preferably 0.007z/a
By using a raw film or sheet having a value of + or less, an excellent retardation plate without optical color unevenness can be obtained.

Examples of the thermoplastic resin used in the retardation plate of the present invention include polycarbonate resin, I-limethyl methacrylate, and methacrylic acid obtained by copolymerizing methyl methacrylate as a main component with other ethylene comonomers. Poly(meth)acrylate resins such as methyl copolymers, polystyrene resins such as styrene copolymers obtained by copolymerizing styrene as a main component and other ethylene comonomers, polyacrylonitrile, acrylonitrile copolymers Acrylonitrile resins such as polyethylene terephthalate, ester resins such as polyester copolymers, polyamide resins such as nylon 6 and nylon 66, polyvinyl chloride, vinyl chloride copolymers, etc.
Polyolefin resins such as vinyl chloride resins, polyethylene, polypropylene, ethylene copolymers, and propylene copolymers, polysulfones, gylyethersulfones,
Examples include at least 111 or more resin materials selected from fluororesins, modified products thereof, and blends of these resins with transparent low-molecular compounds such as polymer liquid crystals or low-molecular liquid crystals, or transparent inorganic compounds. .

Among these, preferred resins include polycarbonate resins, polyethylene terephthalate, polyester resins such as polyester copolymers, polysulfone, polyvinyl chloride, polyvinyl chloride resins such as vinyl chloride copolymers,
Examples include acrylonitrile resins.

The following is a description of the method of using the thermoplastic polymer compound described above as a retardation plate. In the retardation plate of the present invention, the thermoplastic polymer is prepared by a known am method, that is, by a bath agent casting method.
It is manufactured by forming a raw film or sheet by a calendering method or an extrusion method, and then stretching it in the -axial direction 6ζ to 1'f.

In order to obtain a retardation plate with a constant optical axis and little optical color unevenness, the original film or sheet must have good thickness accuracy, be as optically homogeneous as possible, and have a thickness ( 1) The amplitude of deviation (ΔX) is required to be 0.1j or less, and the rate of change in thickness (G) is required to be 0.016 m /ex or less.

The thickness (Jl) of the original film or sheet is 80αX8
A sample of Gcm was taken, and 86 points were evenly selected and measured.It is expressed as the average value of 86 points, and the variation width of thickness (ΔX)
is the difference between the maximum value and minimum value of the 86 points mentioned above, and the rate of change in thickness (G') is the maximum value among the values obtained by dividing the difference between adjacent measurement points by the measurement point interval (distance 1II). refers to value.

Further, it is not preferable that die lines or the like occur on the raw film or sheet during molding. Normally, when forming a film or a plate, minute orientations often occur, and it is also a preferable method to reduce these minute orientations prior to stretching. Heat treatment is effective as a method for achieving fine orientation before stretching.

In order to produce the retardation plate of the present invention, heat treatment is performed at a temperature equal to or higher than the heating deformation temperature of the film or sheet before stretching.

When the heat treatment is carried out, the birefringence index of the original film or sheet becomes substantially O, and it becomes a completely non-oriented film or sheet.

Methods for stretching the raw film or sheet obtained in this way in the uniaxial direction include horizontal uniaxial stretching using a tenter method, inter-roll compression stretching, and longitudinal-axial stretching using rolls with different peripheral speeds. ξ, which adopts the uniaxial stretching method known by the law, is available.

In the present invention, in order to obtain a retardation plate with small fluctuations in retardage and n value, and the rate of change thereof, it is necessary to increase the neck-in rate (defined from the film width A before stretching and the film u% B after stretching). 1oOx(A-B)/A) to 105
% or less, preferably 6% or less, more preferably substantially 0 or less. Therefore, the most effective stretching method in the present invention is a transverse uniaxial stretching method using a tenter method that does not substantially cause neck-in.

The transverse uniaxial stretching by the tenter method consists of eight steps: a preheating step, a stretching step, and a heat treatment step. The preheating step is useful because it has the same role as the heat treatment step to make the birefringence of the film or sheet substantially O. The stretching process is the most important process for producing a retardation plate, and processing conditions vary depending on the type of thermoplastic resin used, thickness, required retardation value, etc., but the retardation of the present invention has minimal optical unevenness. In order to obtain a plate, it is important to perform uniform stretching, and for this purpose it is essential to select the stretching temperature under appropriate conditions.

The stretching temperature must be higher than the temperature at which the apparent yield point disappears in the stress-strain curve of the tensile test. If the stretching temperature is in the temperature range where the yield point appears on the stress curve or below, the stretching will be non-uniform, causing unevenness in the stretched product and the amplitude and rate of change of the letterage will increase.

The stretching ratio is not particularly limited, and varies depending on the class 81 thermoplastic resin to be used, but it is about 1.2 to 6 times, preferably about 1.2 to 4.0 times.

The heat treatment step after stretching is a useful step for improving the dimensional stability of the obtained stretched film or plate and improving the uniformity of retardage buds, and the heat treatment temperature ranges from below the stretching temperature to around the heat distortion temperature. is preferred.

The heating deformation temperature is #f in JISK678618.6.
/cd.

The letterage sheet in the present invention can be measured using a polarizing microscope, a spectrophotometer, etc., and the average value (R) of the letterage sheet is 80wX from a stretched film or sheet.
An 80cm sample was taken, and 86 points were measured at 1 points. (expressed as a percentage), and the rate of change in letterage 1 (G) is the value (expressed as a percentage) obtained by dividing the difference between the measured values of adjacent measurement points by the average value (expressed as a percentage), and the distance between the measurement points (distance 11!). The maximum value among the values divided by t).

This swing width ΔR is 10% or more or G is 1.8%/e
If it is 11 or more, it cannot be used for various optical applications, especially for liquid crystal display devices, due to optical unevenness.

The retardation plate of the present invention can also be applied to liquid crystal display devices etc. by laminating it on one side of a polarizing plate to form a composite polarizing plate.

The polarizing plate constituting the composite polarizing plate of the present invention (in this case, any polarizing plate can be used. For example, a film made of polyvinyl alcohol or a derivative thereof is uniaxially stretched and oriented, and used as a polarizing element. After adsorbing iodine or dichroic dye, non-optically active cellulose films such as cellulose triacetate are laminated on both sides.Furthermore, dehydrochloric acid of polyvinyl chloride film or polyvinyl alcohol Polyene-based polarizing plates obtained by dehydration treatment of polyene-based films, dichroic dyes blended with hydrophobic resins such as polyethylene terephthalate, and -dynamic ζ-oriented polarizing plates can be used. , a polyvinyl alcohol film Cζ, a polarizer that adsorbs iodine or dichroic dye and is oriented on the -axis, and a cellulose film such as cellulose triacetate, which is laminated on both sides as a protective film, has polarization properties, Preferable from the viewpoint of hue characteristics.

Using the retardation plate and polarizing plate of the present invention, the number ζ of forming the composite polarizing plate of the present invention is such that the optical axis of the polarizing plate and the optical axis of the retardation plate are 16 to 76 degrees, preferably 80 to 60 degrees. More preferably, this is achieved by bonding at an angle of 40 to 60 degrees using a pressure-sensitive adhesive or an adhesive.

In addition, there are those in which the protective film on one side of the linear polarizing plate is removed and the polarizer and retardation plate are directly bonded together using an adhesive or adhesive, and the hydrophobic polymer film without a protective film. A structure in which a retardation plate is attached to one side of a linearly polarizing plate made of a combination of dichroic dyes using an adhesive or a pressure-sensitive adhesive is also included in the scope of the composite polarizing plate of the present invention. be.

〔Effect of the invention〕

The retardation plate or composite polarizing plate obtained in this way has good optical performance and can pass the accelerated durability test at 80°C and 60°C x 90% RH. Because of this, it can be used for new applications such as liquid crystal display applications.

An example of application to a liquid crystal display is shown below.

(1) If a retardation plate is placed above the upper polarizing plate of a TN type liquid crystal display in which the twist angle of the liquid crystal molecules is 90 degrees, there will be no rainbow pattern when viewed through polarized sunglasses from any direction. , the display quality is significantly improved compared to the case where a conventional elliptically polarizing plate is used.

(O) If a retardation plate is placed below the upper polarizing plate of a TNW liquid crystal display in which the twist angle of the liquid crystal molecules is 90 degrees, interference colors in the liquid crystal layer can be uniformly eliminated over a large screen. Display quality is significantly improved.

(3) The twist angle of the liquid crystal molecules is 180 to 270 degrees 5
In the TNW liquid crystal display device, the birefringence of the liquid crystal layer ζ
Coloration occurs due to this. The retardation plate of the present invention is attached between the upper polarizing plate or the lower polarizing plate and the liquid crystal cell of an STN type liquid crystal display so that its optical axis is in the range of 80 to 60 degrees, preferably 40 to 69 degrees. As a result, display quality is improved. By arranging the pair of polarizing plates so that their optical axes are orthogonal or nearly perpendicular, or parallel or nearly parallel, black-and-white display is possible.
Display quality improves.

〔Example〕

The present invention will be explained below with reference to Examples. The present invention is not limited to these buds. Note that the retardation value of the retardation plate in Example Cζ was measured using a polarizing microscope 411.
Senarmon compensator equipped with 1sζ (646
1 m), and a halogen lamp was used as the light source. The linear polarizing plate in the example is, for example, Jikai 11861-2.
It was prepared by the method Qζ as described in Publication No. 0008, and iodine was uniaxially adsorbed and oriented as a dichroic dye on polyvinyl alcohol. If necessary, a transparent non-optically active polymer film such as cellulose triacetate is laminated as a protective film.

Example 1 Thickness (X) of original film: 180μIn, △X: 111m% Thickness change rate (G'): Sμm/c
s transparent polycarbonate film (heat deformation temperature 18
50) was used.

First, a sample piece of JIS No. 6 Il was taken from the original film and subjected to a tensile test at a temperature near the heating deformation temperature. The temperature at which the apparent yield point disappears at the stress-distortion edge was approximately 166°C (The stress-strain curve is shown in Figure 1.) The stretching was carried out using a tenter setup (J (
2 m width and Xeys length) was used for transverse uniaxial stretching.

The raw film was heated to 19018 IC in the preheating process to make the birefringence of the raw film 0.4X1G-4, and then stretched 1.8 times horizontally uniaxially at 1700 in the stretching process to 140
A stretched film with a thickness of 100 μm was obtained by heat treatment at °C. The stretched film has an R of 540 nm% and an ΔR of 4.
6%, G was 0.67%/egg, and it was a homogeneous retardation plate with little optical 1ζ unevenness.

This retardation plate was attached to one surface of a polarizing plate using an acrylic adhesive so that the optical axis was set at about 46 degrees to obtain a composite polarizing plate of the present invention.

Furthermore, when this retardation plate is bonded between the liquid crystal cell and the upper polarizing plate of a liquid crystal display device in which the twist angle of the liquid crystal molecules is 200 degrees, it becomes possible to display almost black and white with a white background and a black display area. , There was no rainbow pattern uniform color unevenness (a liquid crystal display device with good display quality was obtained.

Example 2 The raw film of Example 1 was subjected to transverse uniaxial stretching using tenter equipment. The raw film is heated to 195C in the preheating process, and the birefringence of the raw film is 0.24 x 10-
' After that, in the stretching process, horizontal uniaxial -ζ 1.6 times stretching was carried out at 175C, heat treatment was carried out at 140C, and the thickness was 120C.
A μ-vortex stretched film was obtained.

The stretched film has a k of 280 nm%, ΔR of 8.6%,
G was 0.48%/(Fll) The retardation plate was optically homogeneous with little unevenness.

This retardation plate was attached to one surface of a polarizing plate using an acrylic adhesive so that the optical axis was set at 46 degrees, thereby obtaining a composite polarizing plate of the present invention.

Furthermore, when this retardation plate was laminated with an adhesive between the liquid crystal cell of a liquid crystal display device in which the twist angle of the liquid crystal molecules is 200 degrees and the upper polarizing plate, the background color was white and the display area was It became possible to display almost black and white, and there was no rainbow-like color unevenness, and a liquid crystal display device with good display quality was obtained.

Example 8 The raw film of Example 1 was subjected to transverse uniaxial stretching using tenter equipment. The raw film was heated to 198°C in the preheating process, and the birefringence of the raw film was set to 0.85 A stretched film with a thickness of 82 μm was obtained by heat treatment. The stretched film has an R of 88 Onm.
A homogeneous retardation plate with sΔR of 6.6% and G of 0.76%/ell with little optical unevenness is used as a liquid crystal cell of a liquid crystal display device in which the twist angle of liquid crystal molecules is 200 degrees. When used by bonding between the upper polarizing plates with an adhesive, it is possible to display a nearly black and white display with a white background and a black display area, and there is no rainbow-like color unevenness, resulting in a liquid crystal display with good display quality. The device was obtained.

Comparative Example 1 Thickness as original film x > tso μm, Δ1
26 ums
A stretched film was obtained.

The stretched film has an R of 685 nm and a ΔR of 11.4.
%, G was 1.455%/cm, and only a retardation plate with large optical unevenness and inferior homogeneity compared to Example 1 was obtained.

Comparative Example 2 was conducted to obtain a stretched film with a thickness of 100 μm. The stretched film has an R of t o t o nm.

ΔR was 10%, G was 1.4%/eta, and the optical fishing table ζ unevenness was thick (and compared to Example 1, only a retardation plate with inferior homogeneity was obtained.

Comparative Example 8 Using the same original fabric as in Example 1, preheating it at a temperature of 170°C, it was vertically rolled between rolls with different circumferential speeds.
The axis is tensile stretched to a thickness of approximately %μm (neck-in rate 1).
8%) was obtained. Cough stretched film has an R of 6
76Cm, ΔR 12.5%, G 1.60%/a
+, and the optical unevenness was thick (only a retardation plate with inferior homogeneity compared to Example 1 was obtained).

Example 4 The thickness of the original film is x>taoμm, △X
A stretched film with a thickness of 100 μm was obtained in the same manner as in Example 1, except that a transparent polycarbonate film (heat deformation temperature: 186° C.) with G′ of 16 pm and G′ of 2.2 μ/a was used. The stretched film has an R of 546 nm, △
The R was 7.65%, the G was 0.98%/clM, and the retardation plate had little optical unevenness. This retardation plate was permanently attached to one surface of a polarizing plate using an acrylic adhesive so that the optical axis was set at 45 degrees to obtain a composite polarizing plate of the present invention. Furthermore, this retardation plate is f
When applied to an I&crystal display device, a good quality liquid crystal display device with almost black and white display was obtained.

Example 6 As a raw film, the thickness is x > ts oμm.

Δxi! 14 μm, G' is 2.0/jm/ex transparent polycarbonate film (heat deformation temperature 182℃
), and in the same manner as in Example 1, it was determined that the temperature at which there is no apparent yield point on the curve curve was about 160°C.

Stretching was carried out using pressure roll equipment (diameter 260-s, surface length 700 m)
) was used for compression stretching. The original film was preheated to 150°C in a heating oven, and the birefringence of the original film was set to 0.5 x 10'', and then passed between pressure rolls at 165°C to perform longitudinal-axis lζ 1.7 times stretching. Thickness: 60μm.

A stretched film with a width of 880 cm (neck-in rate of 4%) was obtained. The stretched film has Rb' 89 Qrlm.

ΔR was 7.00!6, G was 0.65%/1, and the phase 2i was optically homogeneous with little unevenness. This retardation plate was attached using an acrylic adhesive so that the optical axes of one side of the polarizing plate overlapped by about 46 degrees to obtain a composite polarizing plate of the present invention.

When this retardation plate was applied to a liquid crystal display device in the same manner as in Example 1, a liquid crystal display device with almost black and white display and good quality was obtained.

Comparative Example 4 Example 6 (using the same original film, without preheating the original film, passing it between pressure rolls at 145 ° C.
The film was axially stretched 1.8 times (neck-in rate: 8%) to obtain a stretched film with a thickness of about 140 itn. The stretched film has an R of 610 mm, a ΔR of 14%, and a G of 1.85%.
/ cg, cracks due to stretching unevenness were observed, and the optical serration unevenness was large (compared to Example 6, only a retardation plate with inferior homogeneity was obtained).

Example 6 ■As an anti-film, thickness *(x>4ooμm.

Example 1 A polyester copolymer film (PZTG6768, Eastman Chemical Co., heat distortion temperature 81C) with Δ2 of 26 umqG' of 8.2 pm/am was used.
Using the same method as above, the temperature at which the apparent yield point disappears is approximately 10
It was determined that the temperature was 5°C. The film was preheated at a temperature of 186°C, and then transversely uniaxially stretched at a temperature of 122°C by the tenter method-ζ to obtain a stretched film with a thickness of about 240 μm. The stretched film has an R of 485 mm,
ΔR was 6.8%, G was O, aO%/cm, and it was a homogeneous retardation plate with little optical unevenness. This retardation plate was attached to one side of a polarizing plate using an acrylic adhesive so that the optical axis was approximately 46 degrees (ζ) to obtain a composite polarizing plate of the present invention.Furthermore, this retardation plate When this was applied to a liquid crystal display device in the same manner as in Example 1, a liquid crystal display device of good quality with almost black and white display was obtained.

Comparative example 6 In Example 6, the thickness (-) is 400 μm.

A stretched film was obtained in the same manner as in Example 6, except that a raw film having ΔX of 45 a m% and G' of 6 μm/eWL was used. The stretched film has an R of 52
5 nm, ΔR 10.8%, G 1.415%/eM
The optical unevenness was large (compared to Example 6, it could only be obtained using a retardation plate with inferior homogeneity).

Example 7 A polyvinyl chloride film (manufactured by Sunroid VIPCHA 150 m, manufactured by Tatsunaka Plastic Industries) with a thickness (X > 250 μm, 1ΔX of 164 m, and G' of 8.5 μm, 1 cm) was used as the original film. The temperature at which the apparent upper yield point disappears was determined to be approximately 850 using the same method as in 1.The film was preheated at a temperature of 1200°C and then transversely uniaxially stretched using a tenter method at a temperature of %°C. Approximately 14
A stretched film of 0 μm was obtained. The stretched film had an R of about 31Qnm1ΔR of 7.2% and a G of 0.66% per unit, and was a homogeneous retardation plate with little optical unevenness. This retardation plate was attached to one surface of a polarizing plate using an acrylic adhesive so that the optical axis was set at about 46 degrees to obtain a composite polarizing plate of the present invention. Furthermore, when this retardation plate was applied to an Iζ liquid crystal display device at as in Example 2,
A liquid crystal display device with good display quality was obtained.

Comparative Example 6 In Example 7, the thickness (→ is 260 μm 1ΔX is ao
A stretched film was obtained in exactly the same manner as in Example 7, except that a raw film having um%c' of 4.8 μm 2 /eyx was used. The stretched film has an R of 2% nm%ΔR
was 12.8%, G was 1.62%/foil, and the optical unevenness was thick (and compared to Example 7, only a retardation plate with inferior homogeneity was obtained.

Example 8 As a raw film, thickness (j) is 200 μm.

A polysulfone film (heat deformation temperature 174°C) with ΔX of 16 um and SG' of 2.7 um/eM is used,
Using the same method as in Example 1, it was determined that the apparent upper yield point was approximately 200°C.
After preheating at a temperature of ℃, the film was stretched at a temperature of 210℃ using a tenter method to obtain a sheet with a thickness of approximately 6 μm.
A stretched film of m was obtained. The stretching 7 (Rum is 780
It was a homogeneous retardation plate with nrn%ΔR of 7.5%, G of O, and SO%/α with little optical -ζ unevenness. This retardation plate was attached to one surface of a polarizing plate using an acrylic adhesive so that the optical axis was set at about 46 degrees to obtain a composite polarizing plate of the present invention. Furthermore, when this retardation plate was applied to a pot liquid crystal display device in the same manner as in Example 8, a liquid crystal display device of good quality with nearly black and white display was obtained.

Comparative Example 7 In Example 8, the thickness z> is 200 μm and ΔX is 2
A stretched film was obtained by carrying out the same process as in Example 1 except that a raw film having a thickness of 7 μm and a G′ of 4.0 μm/tan was used. The stretched film has an R of 790 nm% and an ΔR of 12
．． 6%, G is 1.61%/α, and the optical unevenness is large.
A retardation plate with inferior homogeneity compared to Example 8 was obtained.

[Brief explanation of the drawing]

FIG. 1 shows the stress-strain curves of the polycarbonate films used in Examples 1-8. Figure 1 Procedural amendment (voluntary) 5゜ Column for detailed explanation of the invention of the specification subject to amendment. On November 24, 1989, ``150°C'' on page 22, line 4 of the 6° amendment was amended to ``140°C.'' Engineering. "Approximately 10.5 μm" in the fifth line from the bottom of Display Specification No. 28 in the case. Patent Application No. 2/2/22 of 1986 is amended to "approximately 105 μm." 2゜Relationship with the case of person amending 3゜retardation film over the title of the invention

Claims (3)

[Claims] (1) A film or sheet formed by uniaxially stretching a thermoplastic polymer film or rate, with a retardation value in the range of 80 to 1200 nm,
The retardation amplitude is 10% or less, and
A retardation plate characterized in that the rate of change is 1.3%/cm or less. (2) As the thermoplastic polymer film or sheet, a thermoplastic polymer film or sheet having a thickness (x) variation of 0.1x or less and a rate of change of 0.015x/cm or less is used. The retardation plate according to claim 1, characterized in that: (3) A composite polarizing plate obtained by laminating the retardation plate according to claim 1 on a polarizing plate.