JP2005099848A - Method for manufacturing retardation plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a retardation plate by which the retardation plate having more uniform retardation in an in-film-surface direction is stably produced with high productivity even when a thermoplastic resin film with thickness variance is used. <P>SOLUTION: In the method for manufacturing a retardation plate, a thermoplastic resin film obtained by a fusion extrusion molding method is quenched below Tg-20°C right after uniaxially or biaxially drawn within a temperature range of Tg to Tg+60°C, wherein Tg is a glass transition point, so that a thicker part is higher in mean temperature along the thickness than a thin part. Further, in the manufacturing method for a retardation plate, a thermoplastic resin film is uniaxially or biaxially drawn in a state in which the thickest part of the film is 0.1 to 0.6A°C higher in mean temperature along the width than the thinnest part, wherein the thickness difference R of the thermoplastic resin film along the width which is represented by a specific expression is represented as ±A%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a method for producing a retardation plate comprising a uniaxially or biaxially stretched thermoplastic resin film, for example, a method for producing a retardation plate suitable for use in compensating for a phase difference in a liquid crystal display device or the like. About.

  Conventionally, TN (twisted nematic) liquid crystal display devices and STN (super twisted nematic) liquid crystal display devices have been used for various OA devices and display devices. However, the liquid crystal display device has a problem that the display screen is colored due to the phase difference generated in the liquid crystal cell. For this reason, a method of eliminating the above coloration using a retardation film is used.

  As a method for producing the retardation film, a method of uniaxially stretching a thermoplastic resin film can be mentioned. In this case, as a stretching method, longitudinal uniaxial stretching (for example, see Patent Document 1), lateral uniaxial stretching (for example, see Patent Document 2), and the like have been reported.

  The retardation compensation performance of the retardation film is represented by a so-called retardation value. The retardation value is represented by Δn × d where Δn is the anisotropy of the refractive index of the resin film (that is, birefringence) and d is the film thickness.

  On the other hand, in a liquid crystal display device, it is desired that color unevenness and contrast unevenness hardly occur over the entire surface of the display. In order to provide a liquid crystal display device capable of such uniform display, the retardation value is required to be uniform over the entire surface of the retardation film.

Therefore, as a method for producing a retardation plate having a uniform retardation value, a polyarylate and / or polysulfone solution is cast to obtain a raw film, and the content of the solvent in the raw film is based on the solid content. A method for producing a retardation plate by adjusting to 0.5 to 7% by weight and then stretching has been proposed (for example, see Patent Document 3).
JP-A-2-191904 JP-A-2-42406 JP-A-8-122526

  However, in the retardation plate obtained by the manufacturing method described in the above prior art, the retardation value varies if the thickness d of the film varies even if the birefringence Δn is uniform in the width direction. As a result, uneven color and uneven contrast could not be resolved.

  That is, as described above, when the retardation plate is incorporated in the liquid crystal display device, the unevenness of the retardation value is a color unevenness if the difference between two points separated by 1 cm is 3 nm or less. It is said that it is not recognized, and more preferably 1 nm or less. Therefore, when a retardation plate having a thickness of 70 μm and an average retardation value of 700 nm is manufactured, the thickness unevenness is required to be within the range of 70 ± 0.3 μm or less, desirably 70 ± 0.1 μm or less. However, it is very difficult to form a film having such a high thickness accuracy by the casting film forming method. Therefore, it was actually very difficult to obtain a retardation plate having a uniform retardation value by the method described in the prior art.

In addition, since the method described in the above prior art uses the cast film forming method, there is a problem that equipment necessary for film formation is expensive and productivity is poor.
Furthermore, since a solvent is used, it is dangerous to supply the solvent to the extruder, and since most of the solvent volatilizes during extrusion, an effect is seen when using a normal extruder. Absent.

  The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to stabilize a retardation plate with a more uniform retardation value in the entire region in the in-plane direction even if there is a variation in thickness in the film before stretching. It is another object of the present invention to provide a manufacturing method that can be obtained with high productivity.

The method for producing a retardation plate according to the first aspect of the present invention is such that the thermoplastic resin film obtained by the melt extrusion molding method has a glass transition point of Tg and a temperature in the range of Tg to Tg + 60 ° C. The thick part is rapidly cooled to Tg-20 ° C. or less immediately after uniaxial or biaxial stretching so that the average temperature in the thickness direction is higher than that of the thin part.
The manufacturing method of the retardation film according to the invention of claim 2 is the thickness difference R in the width direction represented by the following formula (1) of the thermoplastic resin film.

  Thickness difference R = {(maximum thickness−minimum thickness) / average thickness} / 2 × 100 (%) (1)

Is ± A%, the thickest part of the thermoplastic resin film is uniaxially or biaxially stretched in a state where the average temperature in the thickness direction is higher by 0.1 A to 0.6 A ° C. than the thinnest part. It is characterized by doing.

  In the invention described in claim 1 or 2, preferably, as described in claim 3, the temperature difference between the film before stretching and the film during stretching, that is, (film temperature before stretching)-(film temperature during stretching). ) Is in the range of 20 ° C to 90 ° C.

  In invention of Claims 1-3, Preferably, as a thermoplastic resin film before extending | stretching as described in Claim 4, 0.2-20 weight part of plasticizers with respect to 100 weight part of thermoplastic resins. A thermoplastic resin film containing is used.

Details of the present invention will be described below.
(Manufacturing method of phase difference plate according to invention of claim 1)
As the thermoplastic resin used in the method for producing a retardation plate according to the first aspect of the present invention, an appropriate thermoplastic resin can be used as long as it exhibits birefringence by stretching. Examples include vinyl resin, polycarbonate resin, acrylonitrile resin, olefin resin, polystyrene resin, poly (meth) methyl acrylate resin, polysulfone resin, polyarylate resin, and polyethersulfone resin. it can.

Further, as the prepared thermoplastic resin film, a film obtained by forming a film by a melt extrusion method having excellent productivity is used.
The melt extrusion molding method is not particularly limited, and a thermoplastic resin film obtained by a melt extrusion molding method using various known extruders or the like is used.

  Further, the thickness of the thermoplastic resin film is not particularly limited. For example, in the case of using for the purpose of compensating a phase difference in a liquid crystal display device, a thickness of about 50 to 100 μm is usually used. Used.

  In the invention according to claim 1, when the glass transition point of the thermoplastic resin film is Tg, the temperature is in the range of Tg ° C. to Tg + 60 ° C., and the thick portion is more in the thickness direction than the thin portion. Uniaxial or biaxial stretching is performed so that the average temperature becomes high.

  The film temperature during stretching is set within the above range. If the film temperature is lower than Tg ° C., the thermoplastic resin film is not sufficiently flexible, and the thermoplastic resin film is easily broken during stretching. Moreover, when the film temperature at the time of extending | stretching is higher than Tg + 60 degreeC, there exists a possibility that the viscosity of a thermoplastic resin may become low and a thermoplastic resin film may be dripped during conveyance.

  The method for adjusting the temperature of the thermoplastic resin film to Tg ° C. to Tg + 60 ° C. is not particularly limited, and appropriate heaters using hot air, microwaves, far infrared rays, etc., temperature adjusting rolls, heat pipe rolls, and metal belts A known method in which these are appropriately combined can be used.

  The average temperature in the thickness direction of the thermoplastic resin film during stretching refers to the average value of the film temperatures obtained by dividing the film into five in the thickness direction and measuring. As this measuring method, cuts are formed so as to be divided into five in the thickness direction from the side of the film, and an integrated thermocouple is inserted into the cut and fixed to form the film temperature. For example, when the thickness of the thermoplastic resin film is 100 μm, four cuts are formed in the thickness direction at a pitch of 20 μm, the integrated thermocouple is inserted, and the film temperature may be measured.

  Therefore, in the thickness direction of the film, the temperature is measured at five portions from the front surface to the back surface. When the thickness of the film is 100 μm or less, the heat conduction rate is fast, and the difference between the film center temperature and the film surface temperature is very small, for example, only about 0.1 ° C. The average temperature may be used.

  In the first aspect of the invention, the film temperature is set so that the thick part of the thermoplastic resin film has a higher thickness direction average temperature than the thin part, and the film is uniaxially or biaxially stretched. In this case, a method for detecting the thick and thin portions in the thickness direction and adjusting the film temperature between the thick and thin portions can be performed as follows.

  The method for detecting the thickness is not particularly limited, and can be performed using a known non-contact thickness meter using laser, radiation (α rays, β rays), ultrasonic waves, or the like. The method for adjusting the film temperature is not particularly limited, and can be performed using a known heater utilizing hot air, microwaves, far infrared rays, or the like.

The stretching method for uniaxial or biaxial stretching is not particularly limited, and a known method such as longitudinal uniaxial stretching with a roll, lateral uniaxial stretching with a tenter, or biaxial stretching in combination of these can be used.
In addition, it does not specifically limit about a draw ratio, For example, when obtaining the phase difference plate for liquid crystal display devices, it is preferable to set it as about 1.1 to 2.0 times.

  In the method for producing a retardation plate according to the first aspect of the present invention, it is further characterized in that the thermoplastic resin film is rapidly cooled to Tg-20 ° C. or less immediately after stretching, thereby relieving stress due to stretching. Accordingly, the in-plane variation of the retardation value can be made more uniform.

  Here, the rapid cooling means that the temperature of the thermoplastic resin film is instantaneously cooled at a speed at which the temperature reaches the temperature at which the molecular orientation is frozen. Accordingly, although the cooling rate varies depending on the thermoplastic resin film, the rate at which the molecular orientation reaches the freezing temperature within 1 second, preferably within 0.5 seconds, and more preferably within 0.25 seconds after the rapid cooling. It is said.

The film temperature after quenching is not particularly limited as long as the molecular orientation is frozen, but the thermoplastic resin film is preferably Tg-20 ° C. or lower, thereby ensuring the molecular orientation. Can be frozen.
In addition, about the method of carrying out the rapid quenching, it will not specifically limit as long as said conditions are satisfy | filled, For example, the method using a cold wind or a temperature control roll etc. can be used.

(Invention of Claim 2)
In the invention according to claim 2, when the thermoplastic resin film is uniaxially or biaxially stretched, when the thickness difference R in the width direction represented by the above-described formula (1) of the thermoplastic resin film is ± A%, The thermoplastic resin film is stretched in a state where the thickest portion has a higher average temperature in the thickness direction by 0.1 A to 0.6 A ° C than the thinnest portion.

  The thermoplastic resin and the thermoplastic resin film that can be used in the invention described in claim 2 are the same as in the case of the invention described in claim 1. In the case of the invention according to claim 1, the thickness direction average temperature measurement method and the method of detecting the thickest part and the thinnest part and measuring the average temperature in the thickness direction in each case It can be done in the same way.

  As described above, the thickness in the thickness direction is the thickest when the average temperature in the thickness direction of the thickest part is 0.1A to 0.6A ° C. higher than the average temperature in the thickness direction of the thinnest part. This is because the difference in retardation value due to thickness variation is compensated by stretching at a temperature higher than that of the thinnest portion.

  As described above, the retardation value is represented by the product of the film thickness and the birefringence Δn. Therefore, if the birefringence Δn is reduced in the thick part of the film and the birefringence Δn is reduced in the thin part of the film, the variation in retardation value due to the difference in thickness can be compensated. Can do.

On the other hand, when the thermoplastic resin film is stretched, the higher the film temperature, the smaller the orientation due to stretching, and the smaller the birefringence Δn.
Therefore, in the invention according to claim 2, by stretching the thickness direction average temperature of the thickest portion by 0.1 A to 0.6 A ° C. higher than the thickness direction average temperature of the thinnest portion. , Variation in the product of the birefringence Δn and the thickness is reduced. When the thickness direction average temperature difference between the thickest part and the thinnest part is less than 0.1 A ° C., a film showing a retardation value proportional to the thickness can be obtained. Uniformity in the inward direction cannot be achieved. When the thickness direction average temperature difference is higher than 0.6 A ° C., the retardation value in the thick part becomes too small, and the retardation value cannot be made uniform.

  The specific stretching method in the uniaxial or biaxial stretching in the invention described in claim 2 can be the same method as in the invention described in claim 1, and is not particularly limited.

(Invention of Claim 3)
The invention according to claim 3 is the method for producing a retardation plate according to claim 1 or 2, wherein the temperature difference between the film before stretching and the film during stretching, that is, (film temperature before stretching−film temperature during stretching). The film temperature is 20 ° C. to 90 ° C. When the thermoplastic resin film is cooled when it is stretched, a relatively thick portion is difficult to cool due to a difference in heat capacity, and a thin portion is easily cooled. Accordingly, the relatively thick portion has a higher temperature than the relatively thin portion.

On the other hand, when the thermoplastic resin film is stretched to give birefringence, as described above, the higher the film temperature, the smaller the birefringence Δn.
The retardation value is the product of the film thickness d and the birefringence Δn. Accordingly, the relatively thick part of the thickness becomes relatively high due to the cooling, so that the birefringence Δn after stretching becomes small, and the birefringence index Δn becomes large in the thin part. As a result, the retardation values in the thick part and the thin part can be made closer.

  Thus, in the invention according to claim 3, the retardation values of the relatively thick part and the thin part can be made closer. However, by setting the difference between the film temperature before stretching and the film temperature during stretching in the range of 20 to 90 ° C., the variation in the in-plane direction of the retardation value is further reduced, and the retardation value is further increased. A retardation plate with small variations in the in-plane direction can be obtained. When the temperature difference is less than 20 ° C., the variation in retardation value tends to be proportional to the thickness in the film obtained after stretching, and when it exceeds 90 ° C., the retardation value of the thick portion becomes small. The uniformity of the retardation value may be impaired.

(Invention of Claim 4)
According to a fourth aspect of the present invention, in the method for producing a retardation plate according to the first to third aspects of the present invention, as a thermoplastic resin film before stretching, 100 parts by weight of the thermoplastic resin is used in an amount of 0.1% of the plasticizer. A thermoplastic resin film containing 2 to 20 parts by weight is used.

  By including a plasticizer in the thermoplastic resin film, the plasticizer can be volatilized in at least one of a film forming process, a preheating process, and a stretching process. As a result, since the plasticizer volatilization amount in the relatively thick part and the plasticizer volatilization amount in the relatively thin part are the same, the residual plasticizer amount in the relatively thick part is More than the relatively thin part. Therefore, by stretching in this state, the retardation value can be made uniform in the in-plane direction.

  The plasticizer is not particularly limited, but adipic acid ester, azelite acid ester, benzoic acid ester, isobutyric acid ester, thiobutyric acid ester, brassic acid ester, citric acid ester, glycolic acid ester, itaconic acid ester, oleic acid Ester, phosphate ester, phosphinate ester, tetrahydrophthalate ester, hexahydrophthalate ester, pyromellitic acid ester, ricinoleic acid ester, sebacic acid ester, succinic acid ester, sulfonamide triacetylene, trimellitic acid ester, etc. It is done.

  In the method for producing a retardation plate according to any one of claims 1 to 4, when a polysulfone resin or a polycarbonate resin is used as the thermoplastic resin film, the polysulfone resin or the polycarbonate resin is transparent. Since it is excellent and has wavelength dispersion similar to that of light of liquid crystal, a retardation plate suitable for a liquid crystal display device can be provided.

  When a polysulfone resin is used as the thermoplastic resin, a phthalic acid plasticizer excellent in compatibility with the polysulfone resin is preferably used as the plasticizer.

(Function)
In the first aspect of the invention, when the glass transition point of the thermoplastic resin is Tg, the thicker portion is thinner in the temperature range of Tg-30 ° C to Tg + 60 ° C as described above. Uniaxial or biaxial stretching is performed in a state where the average temperature in the thickness direction is higher than that of the portion. The reason for this is as follows.

  When birefringence is imparted by stretching a thermoplastic resin film, it is generally known that the higher the film temperature, the lower the degree of orientation during stretching and the smaller the birefringence index Δn.

  On the other hand, as described above, the retardation value is the product of the film thickness d and the birefringence Δn. Therefore, by stretching at a relatively high temperature in the thick part, the birefringence index Δn after stretching of the thick part decreases, and conversely, the birefringence index Δn increases in the thin part. Therefore, the retardation value between the thick part and the thin part can be made closer.

  That is, in view of the fact that the thickness variation of the thermoplastic resin film cannot be eliminated, the invention according to claim 1 has a birefringence index Δn obtained by stretching in a portion having a small thickness. It is characterized in that the retardation value is made uniform in the in-plane direction of the film by making it smaller than the birefringence Δn.

  In the first aspect of the present invention, immediately after the thermoplastic resin film is stretched, the film is rapidly cooled to Tg-20 ° C. or less. Here, immediately after stretching, the retardation value is made uniform in the in-plane direction in the manufacturing method according to the first aspect of the invention, but the relatively thick portion is more complex than the relatively thin portion. The refractive index Δn is small. By rapidly cooling the film in that state, the variation in retardation value in the in-plane direction of the film can be reduced. The reason for this is as follows.

  In general, since the stress and the birefringence Δn are proportional, as shown in FIG. 1, immediately after stretching, the stress at the relatively thin portion of the thermoplastic resin film is the stress at the relatively thick portion. Bigger than. When this state is not frozen and the stress is relaxed, the stress relaxation rate is increased and the birefringence is increased in a thin portion having a larger stress state.

That is, when the stress is relaxed after stretching, the birefringence difference is decreased, and the effect of uniformizing the retardation value developed in the stretching process is decreased.
Therefore, in the invention described in claim 3, by immediately cooling the film as described above, stress relaxation after stretching is suppressed, and the stress difference between the thick part and the thin part generated immediately after stretching is reduced. Saved. Therefore, by rapidly quenching, in particular, by rapidly quenching to Tg−20 ° C. or lower as described above, the retardation value variation in the in-plane direction can be surely reduced.

  In the invention according to claim 2, when the thickness difference R in the width direction of the thermoplastic resin film is ± A%, the thickest portion has a thickness direction average temperature of 0.1 A than the thin portion. It is uniaxially or biaxially stretched at a high temperature of ~ 0.6 A ° C.

  As described above, the retardation value is the product of the film thickness d and the birefringence Δn. Therefore, in the invention according to claim 2, since the temperature is increased in the relatively thick part, the birefringence Δn after stretching becomes small, and the birefringence index Δn becomes large in the thin part, Both retardation values can be brought close to each other.

  That is, according to the second aspect of the present invention, if the thickest portion has a thickness direction average temperature higher than the thinnest portion by 0.1 A to 0.6 A ° C. as described above, The birefringence index Δn of the relatively thick part can be made smaller than the birefringence index Δn of the thin part, thereby achieving a uniform retardation value in the in-plane direction of the film.

  In the invention according to claim 3, the film temperature difference before stretching and during stretching is uniaxially or biaxially stretched so as to be in the range of 20 to 90 ° C. as described above. When the thermoplastic resin film is cooled when it is stretched, a relatively thick portion of the thermoplastic resin film is hardly cooled due to a difference in heat capacity, and a relatively thin portion is easily cooled. Therefore, the relatively thick portion has a higher temperature than the relatively thin portion.

On the other hand, as described above, when birefringence is imparted by stretching a thermoplastic resin film, it is known that the birefringence Δn decreases as the film temperature increases.
Therefore, due to the cooling, the temperature is relatively high in the thick portion, so that the birefringence Δn is small, and the birefringence Δn is large in the thin portion. The retardation value between the thick part and the thin part can be made closer.

  In the invention according to claim 4, since a thermoplastic resin film containing 0.2 to 20 parts by weight of a plasticizer with respect to 100 parts by weight of the thermoplastic resin is used as the film before stretching, the retardation in the in-plane direction of the film is used. The value can be made more uniform. The reason is considered as follows.

  When a plasticizer-containing thermoplastic resin film is used, the plasticizer volatilizes from any part of the film in the film forming process, the preheating process, the stretching process, and the like. That is, the plasticizer volatilizes from the film surface in the same manner in both the thick and thin portions of the film. Therefore, after volatilization, the absolute content of the plasticizer in the thickness direction in the thick part is greater than the absolute content of the plasticizer in the thin part of the film. In general, it is known that when a large amount of plasticizer is contained, stress relaxation increases even if stretched, and as a result, residual stress decreases.

  Therefore, when the plasticizer is volatilized as described above, since more plasticizer is contained in the relatively thick part, Δn after stretching becomes small in the thick part, thereby reducing the in-plane of the film. The retardation value in the direction can be made uniform more effectively.

In the first aspect of the invention, since the thermoplastic resin film obtained by the melt extrusion molding method is used, the retardation plate can be stably produced with a uniform retardation value while reducing the cost of the retardation plate with high productivity. In addition, by rapidly (immediately) cooling immediately after the stretching process, in-plane uniformity of the retardation value is maintained, and a retardation plate with less variation in retardation value is obtained. According to the invention described in claims 1 to 4, even when there is uneven thickness in the thermoplastic resin film before stretching, the uniformity of the retardation value in the in-plane direction of the film is enhanced. A phase difference plate can be obtained.
Therefore, when the retardation plate obtained by the method for producing a retardation plate according to the inventions according to claims 1 to 4 is used in, for example, a monochrome liquid crystal display device, a clear monochrome image can be obtained, When used in a color liquid crystal display device, it is possible to obtain a high-quality color display in which hue inversion hardly occurs.

  In particular, in the method of manufacturing a retardation film according to any one of claims 1 to 3, even when the thermoplastic resin film has a thickness variation, the temperature of the relatively thick portion in each stretching step Since the temperature is higher than that of the relatively thin portion, the birefringence Δn is relatively low after stretching in the thick portion, thereby reducing variations in the retardation value in the in-plane direction of the film. be able to.

  According to the invention described in claim 4, since the thermoplastic resin film contains a plasticizer, the plasticizer volatilizes prior to stretching or in the stretching process, and contains a plasticizer in a relatively thick portion. The amount is greater than the plasticizer content in the relatively thin portion. Therefore, when birefringence is imparted to the film by stretching, the birefringence Δn of the relatively thick portion is reduced, and the retardation value in the in-plane direction of the film can be further uniformed.

Hereinafter, the present invention will be described in more detail by describing examples of the present invention. In Examples and Comparative Examples below, in Examples 1 to 4 and Comparative Examples 1 to 4, 7, and 8, the manufacturing apparatus shown in FIG. 2 was used. In Examples 5 to 8 and Comparative Examples 5, 6, and 9, the manufacturing apparatus shown in FIG. 3 was used.

Furthermore, in Examples 1 and 2 and Comparative Examples 1 and 3, the thickness of the thermoplastic resin film was measured before stretching, the entire surface temperature of the thermoplastic resin film immediately after stretching was measured with a radiation thermometer, and the thickest The film temperature difference between the part and the thin part was determined. Furthermore, in all Examples and Comparative Examples, since the film thickness is 100 μm or less, the film surface temperature was set to the thickness direction average temperature.

In the manufacturing apparatus shown in FIG. 2, as shown in FIG. 2, a film forming process, a preheating (temperature control) process, and a stretching process are performed. The part for carrying out the film forming process includes an extruder (not shown), a T-die mold 1 connected to the subsequent stage of the extruder, a metal roll 3, a rubber roll 2, and rolls 4 and 5. Is provided.

In order to carry out the preheating (temperature control) step, an oven 27 provided with a hot air device 22 and rolls 6 to 12 which are disposed in the oven 27 and allow the thermoplastic resin film to pass therethrough are provided. . In order to carry out the stretching step, a longitudinal uniaxial stretching machine having rolls 13 to 16 and an air cooling device 21 are arranged.

On the other hand, in the manufacturing apparatus shown in FIG. 3, a film forming process, a preheating (temperature control) process, a stretching process, and a rapid cooling process are performed. In the manufacturing apparatus shown in FIG. 3, the apparatus for performing the film forming process, the preheating (temperature control) process, and the stretching process is the same as the manufacturing apparatus shown in FIG. Accordingly, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

In order to carry out the rapid cooling step, air cooling devices 24 and 24 are arranged above and below the stretched thermoplastic resin film 20. Moreover, in order to dry the thermoplastic resin film 20 after completion | finish of a rapid cooling process, the rolls 17 and 18 are arrange | positioned in the most downstream of this manufacturing apparatus.

(Example 1) Using the manufacturing apparatus shown in FIG. 2, a polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) was put into a hopper of a single screw extruder (not shown). Polysulfone having a thickness of 75 μm ± 5.0 μm having a cross-sectional shape in the width direction shown in FIG. 4 is melt-extruded from a T-die 1 at an extrusion temperature of 340 ° C., nipped by a metal roll 3 having a surface temperature of 165 ° C. An unstretched film 19 was obtained.

The unstretched film 19 is guided between the rolls 4 and 5 to an oven 24 maintained at a temperature of 200 ° C. in which the rolls 6 to 12 are arranged, and the rolls 13 to 16 are arranged in a range of 190 ° C. to 290 ° C. The film was stretched uniaxially at a draw ratio of 1.15 times using a stretching machine maintained at a temperature of 1, and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 70 μm ± 6.0 μm.

The temperature setting in the stretching machine is such that the region where the end on the thick side of the both ends in the film width direction (Tg direction) runs is 200 ° C., and the region where the end on the thin side runs is 190 ° C. The hot air was discharged. Therefore, the stretching machine is provided with nozzles that generate hot air at different temperatures in at least two places in the TD direction. In addition, when the whole surface of the film just after extending | stretching was measured with the radiation thermometer, the thickness direction average temperature in the 76-micrometer-thick part was 4.0 degreeC higher than the thickness direction average temperature of the 64-micrometer-thick part.

A retardation plate sample having a width of 500 mm and a length of 1000 mm was cut out from the central portion of the film obtained as described above. When the retardation value at 633 nm of this retardation plate sample was measured at 1 cm intervals in both the width direction and the length direction, the average retardation value was 455 nm, and the maximum variation in retardation value (film The in-plane retardation maximum value-retardation minimum value) was 5.0 nm, and the difference in retardation value between two points 1 cm apart was 1.7 nm at the maximum.

Example 2 The manufacturing apparatus shown in FIG. 2 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 340 ° C., and the surface temperature The metal roll 3 and the rubber roll 2 at 165 ° C. were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is placed between rolls 4 and 5 and placed in an oven 24 maintained at a temperature of 220 ° C. where rolls 6 to 12 are arranged, and then rolls 13 to 16 are arranged at 180 ° C. The film was stretched uniaxially at a stretching ratio of 1.3 times by a stretching machine 25 kept at a temperature and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 74 μm ± 2.5 μm.

In addition, when the whole surface of the film immediately after stretching was measured with a radiation thermometer (not shown), the thickness direction average temperature of the 74.5 μm thick portion was larger than the thickness direction average temperature of the 69.5 μm thick portion. Was also 0.9 ° C higher.

A retardation plate sample having a width of 500 mm and a length of 1000 mm was cut out from the center of the obtained film 20. When this sample was evaluated in the same manner as in Example 1, the average value of the retardation value was 526 nm, and the maximum variation of the retardation value (maximum retardation value in the film surface−minimum retardation value in the film surface). The difference in retardation value between two points separated by 2.8 nm and 1 cm was 1.3 nm at the maximum.

Example 3 The manufacturing apparatus shown in FIG. 2 was used. In the same manner as in Example 2, an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm was obtained.

The unstretched film 19 is placed between the rolls 4 and 5 and placed in an oven 24 maintained at a temperature of 220 ° C. where the rolls 6 to 12 are disposed, and then the rolls 13 to 16 are disposed at 200 ° C. The film was stretched uniaxially at a stretching ratio of 1.3 times with a stretching machine 25 kept at a temperature and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 73 μm ± 2.5 μm.

About the obtained film 20, the retardation plate sample was cut out similarly to the retardation plate sample of Example 1, and was evaluated. The average retardation value was 402 nm, the maximum variation in retardation value was 3.0 nm, and the maximum difference in retardation value between two points 1 cm apart was 1.3 nm.

Example 4 The manufacturing apparatus shown in FIG. 2 was used. A polycarbonate resin pellet (manufactured by Teijin Kasei Co., Ltd., trade name: Panlite, glass transition point 150 ° C.) is put into a hopper of a single screw extruder, melt extruded from a T-die 1 at an extrusion temperature of 250 ° C., and a metal having a surface temperature of 130 ° C. The roll 3 and the rubber roll 2 were nipped and cooled to obtain a polycarbonate unstretched film 19 having a thickness of 78 μm ± 2.0 μm.

The unstretched film 19 is placed between the rolls 4 and 5 and placed in an oven 24 maintained at 170 ° C. where the rolls 6 to 12 are arranged, and then the rolls 13 to 16 are arranged at 150 ° C. The film was stretched uniaxially at a stretch ratio of 1.3 times with a stretching machine 25 maintained at a temperature of 1, and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 68 μm ± 2.5 μm.

From the obtained film 20, a retardation plate sample was cut out and evaluated in the same manner as in Example 1. The average retardation value was 565 nm, the maximum variation in retardation value was 3.6 nm, and the maximum difference in retardation value between two points 1 cm apart was 1.6 nm.

(Example 5) In Example 5, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 340 ° C., and the surface temperature The metal roll 3 and the rubber roll 2 at 165 ° C. were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

190 degreeC temperature which introduce | transduces the said unstretched film 19 between the rolls 4 and 5 in the oven 24 set to the atmospheric temperature 235 degreeC which arrange | positions the rolls 6-12, and arrange | positions the rolls 13-16 The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to a polysulfone stretched film.

Next, in the rapid cooling step, the polysulfone stretched film obtained as described above is blown with cold air, and the surface temperature is cooled to 100 ° C. in 1.0 second to obtain a polysulfone stretched film 20 having a thickness of 70 ± 2.5 μm. It was.

A retardation plate sample was cut out from the stretched polysulfone film 20 obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 487 nm, the maximum variation in retardation value was 2.5 nm, and the difference in retardation value between two points 1 cm apart was 1 nm at maximum.

(Embodiment 6) The manufacturing apparatus shown in FIG. A polycarbonate resin pellet (manufactured by Teijin Kasei Co., Ltd., trade name: Panlite, glass transition point 150 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 250 ° C., and the surface The metal roll 3 and the rubber roll 2 having a temperature of 130 ° C. were nipped and cooled to obtain a polycarbonate unstretched film 19 having a thickness of 75 μm ± 2.0 μm.

The unstretched film 19 is guided between the rolls 4 and 5 to the oven 24 set at an atmospheric temperature of 200 ° C. where the rolls 6 to 12 are arranged, and then the rolls 13 to 16 are arranged at 155 ° C. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set at a temperature of 1 to obtain a stretched polycarbonate film.

Immediately in the rapid cooling step, the polycarbonate stretched film was cooled by cold air blown out from the air cooling device 21 to obtain a polycarbonate stretched film 20 having a surface temperature of 80 ° C. in 1.0 seconds and a thickness of 67 ± 2.5 μm. .

A retardation plate sample was cut out from the center of the stretched polycarbonate film obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 455 nm, the maximum variation in retardation value was 2.7 nm, and the difference in retardation value between two points 1 cm apart was 1 nm at maximum.

Example 7 In Example 7, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) was put into a hopper of a single screw extruder (not shown), and diisononyl phthalate (100 parts by weight of the thermoplastic resin) 3.0 parts by weight of a boiling point of 403 ° C. is press-fitted into a single screw extruder (not shown) with a plunger pump (not shown), melt-extruded from the T-die 1 at an extrusion temperature of 290 ° C., and a surface temperature of 140 ° C. The metal roll 3 and the rubber roll 2 were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is passed through the rolls 4 and 5, and is introduced into an oven 24 set at an atmospheric temperature 200 ° C. in which the rolls 6 to 12 are arranged, and a temperature of 155 ° C. in which the rolls 13 to 16 are arranged. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to a polysulfone stretched film.

Next, cold air is blown from the air cooling device 21 to the polysulfone stretched film obtained as described above in the rapid cooling step, the surface temperature is 80 ° C. in 1.0 second, and the polysulfone is unstretched with a thickness of 71 ± 2.5 μm. Film 20 was obtained.

From the polysulfone unstretched film 20 obtained as described above, a retardation plate sample was cut out in the same manner as in Example 1 and evaluated. The average retardation value was 389 nm, the maximum variation in retardation value was 2.3 nm, and the difference in retardation value between two points 1 cm apart was 0.8 nm at maximum.

Example 8 In Example 8, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) was put into a hopper of a single screw extruder (not shown), and diethyl phthalate (100 parts by weight of the thermoplastic resin) 3 parts by weight of a boiling point of 298 ° C. is press-fitted into a single screw extruder (not shown) with a plunger pump (not shown), melt-extruded from the T-die 1 at an extrusion temperature of 290 ° C., and a metal roll having a surface temperature of 140 ° C. 3 and the rubber roll 2 were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is guided between the rolls 4 and 5 and introduced into an oven 24 set at an atmospheric temperature 220 ° C. in which the rolls 6 to 12 are arranged, and a temperature of 175 ° C. in which the rolls 13 to 16 are arranged. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to a polysulfone stretched film.

Next, the polysulfone stretched film obtained as described above in the rapid cooling step is blown with cold air from the air cooling device 21 to bring the surface temperature to 80 ° C. in 1.0 second, and the polysulfone stretched film having a thickness of 71 ± 2.5 μm. 20 was obtained.

A retardation plate sample was cut out from the stretched polysulfone film 20 obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 395 nm, the maximum variation in retardation value was 2.0 nm, and the maximum difference in retardation value between two points 1 cm apart was 0.6 nm.

(Example 9) 100 parts by weight of a polysulfone resin (manufactured by Acomo Corporation, trade name: UDEL P3500, glass transition point 190 ° C.) and 1 part by weight of diethyl phthalate (boiling point 295 ° C.) were mixed by a tumbler, and a single screw extruder Was melt-extruded from a T-die at 290 ° C. and cooled through a nip roll composed of a metal roll and a rubber roll having a surface temperature of 140 ° C. to produce an unstretched polysulfone film having an average thickness of 75 ± 2 μm.

The unstretched film was stretched uniaxially at a stretch ratio of 1.4 times with a roll stretching machine at a preheating zone temperature of 180 ° C. and a stretching zone temperature of 175 ° C. After volatilizing the diethyl, it was rapidly cooled to 50 ° C. or less in 0.5 seconds by an air cooling device to obtain a stretched polysulfone film having a thickness of 68 ± 2.5 μm.

A retardation plate sample having a width of 500 mm and a length of 1000 mm was cut out from the center of the obtained polysulfone stretched film. The retardation value of this retardation plate sample at 633 nm was measured at 1 cm intervals in both the width direction and the length direction. As a result, the average retardation value was 435 nm, the maximum variation (retardation maximum value−retardation minimum value) was 4.1 nm, and the maximum difference in retardation values between two points 1 cm apart was 0. It was 7 nm.

(Comparative Example 1) When setting the temperature in the stretching machine, the region where the end on the thick side of the both ends in the film width direction (Tg direction) travels is 190 ° C, and the region where the end on the thin side travels Except having discharged hot air so that it might become 200 degreeC, it carried out similarly to Example 1, and obtained the polysulfone stretched film 20.

Since the temperature was set as described above, the entire surface of the film immediately after stretching was measured with a radiation thermometer. The thickness direction average temperature in the 76 μm thick portion was 4.0 ° C. than the thickness direction average temperature in the 64 μm thick portion. It was low.

A retardation plate sample was cut out from the film obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value is 449 nm, the maximum variation in retardation value (maximum retardation value in the film plane−minimum retardation value) is 18.0 nm, and the retardation value between two points 1 cm apart is 1 The difference was a maximum of 5.5 nm.

Comparative Example 2 The apparatus shown in FIG. 2 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 340 ° C., and the surface temperature The metal roll 3 and the rubber roll 2 at 165 ° C. were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is placed between the rolls 4 and 5 and placed in an oven 24 maintained at a temperature of 220 ° C. where the rolls 6 to 12 are disposed, and then the rollers 13 to 16 are disposed. The film was stretched uniaxially at a stretching ratio of 1.3 times with a stretching machine 25 kept at a temperature, and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 72 μm ± 2.5 μm.

A retardation plate sample was cut out from the obtained film 20 in the same manner as in Example 1 and evaluated. The average retardation value was 370 nm, the maximum variation in retardation value was 15.0 nm, and the maximum difference in retardation value between two points 1 cm apart was 4.1 nm.

Comparative Example 3 The apparatus shown in FIG. 2 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 340 ° C., and the surface temperature The metal roll 3 and the rubber roll 2 at 165 ° C. were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is placed between rolls 4 and 5 and placed in an oven 24 maintained at a temperature of 200 ° C. where rolls 6 to 12 are arranged, and then rolls 13 to 16 are arranged at 230 ° C. The film was stretched uniaxially at a stretching ratio of 1.3 times with a stretching machine 25 kept at a temperature, and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 70 μm ± 2.5 μm.

In addition, when the whole surface of the film immediately after stretching was measured with a radiation thermometer (not shown), the thickness direction average temperature of the 72.5 μm thick portion was more than the thickness direction average temperature of the 67.5 μm thick portion. Was also 0.6 ° C lower.

A retardation plate sample was cut out from the obtained film 20 in the same manner as in Example 1 and evaluated. The average retardation value was 487 nm, the maximum variation in retardation value was 26.1 nm, and the maximum difference in retardation value between two points 1 cm apart was 6.7 nm.

Comparative Example 4 The manufacturing apparatus shown in FIG. 2 was used. A polycarbonate resin pellet (manufactured by Teijin Kasei Co., Ltd., trade name: Panlite, glass transition point 150 ° C.) is put into a hopper of a single screw extruder, melt extruded from a T-die 1 at an extrusion temperature of 250 ° C., and a metal having a surface temperature of 130 ° C. The roll 3 and the rubber roll 2 were nipped and cooled to obtain a polycarbonate unstretched film 19 having a thickness of 78 μm ± 2.0 μm.

The unstretched film 19 is placed between the rolls 4 and 5 in an oven 24 maintained at 185 ° C. where the rolls 6 to 12 are arranged, and then the rolls 13 to 16 are arranged at 185 ° C. The film was stretched uniaxially at a stretch ratio of 1.3 times with a stretching machine 25 maintained at a temperature of 1, and allowed to cool to room temperature (20 ° C.) to obtain a film 20 having a thickness of 68 μm ± 2.5 μm.

From the obtained film 20, a retardation plate sample was cut out and evaluated in the same manner as in Example 1. The average retardation value was 398 nm, the maximum variation in retardation value was 16.3 nm, and the maximum difference in retardation value between two points 1 cm apart was 4.5 nm.

Comparative Example 5 In Comparative Example 5, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 340 ° C., and the surface temperature The metal roll 3 and the rubber roll 2 at 165 ° C. were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

190 degreeC temperature which introduce | transduces the said unstretched film 19 between the rolls 4 and 5 in the oven 24 set to the atmospheric temperature 235 degreeC which arrange | positions the rolls 6-12, and arrange | positions the rolls 13-16 The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to a polysulfone stretched film.

Next, the polysulfone stretched film obtained as described above was introduced into an oven 26 set to an atmospheric temperature of 170 ° C., and slowly cooled so that the surface temperature reached 170 ° C. 1 minute after stretching, and a thickness of 72 ± A stretched polysulfone film 20 having a thickness of 2.5 μm was obtained.

A retardation plate sample was cut out from the stretched polysulfone film 20 obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 370 nm, the maximum variation in retardation value was 10 nm, and the maximum difference in retardation value between two points 1 cm apart was 3.5 nm.

Comparative Example 6 In Comparative Example 6, the manufacturing apparatus shown in FIG. 3 was used. A polycarbonate resin pellet (manufactured by Teijin Kasei Co., Ltd., trade name: Panlite, glass transition point 150 ° C.) is put into a hopper of a single screw extruder (not shown), melt extruded from a T-die 1 at an extrusion temperature of 250 ° C., and the surface The metal roll 3 and the rubber roll 2 having a temperature of 130 ° C. were nipped and cooled to obtain a polycarbonate unstretched film 19 having a thickness of 78 μm ± 2.0 μm.

The unstretched film 19 is passed through the rolls 4 and 5, and is introduced into an oven 24 set at an atmospheric temperature 200 ° C. in which the rolls 6 to 12 are arranged, and a temperature of 155 ° C. in which the rolls 13 to 16 are arranged. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to a polycarbonate stretched film.

Next, the polycarbonate stretched film obtained as described above was introduced into an oven 26 set to an atmospheric temperature of 170 ° C., and slowly cooled so that the surface temperature reached 170 ° C. 1 minute after stretching, and the thickness was 69 ±. A stretched polycarbonate film 20 of 2.5 μm was obtained.

A retardation plate sample was cut out and evaluated from the stretched polycarbonate film 20 obtained as described above in the same manner as in Example 1. The average retardation value was 375 nm, the maximum variation in retardation value was 9.3 nm, and the maximum difference in retardation value between two points 1 cm apart was 3.2 nm.

Comparative Example 7 In Comparative Example 7, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) is put into a hopper of a single screw extruder (not shown), and 100 parts by weight of the thermoplastic resin is diisononyl phthalate ( 3 parts by weight of a boiling point of 403 ° C. is press-fitted into a single screw extruder (not shown) with a plunger pump (not shown), melt-extruded from the T-die 1 at an extrusion temperature of 260 ° C., and a metal roll having a surface temperature of 140 ° C. 3 and the rubber roll 2 were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is guided between the rolls 4 and 5 and introduced into an oven 24 set at an atmospheric temperature 185 ° C. in which the rolls 6 to 12 are arranged, and a temperature of 185 ° C. in which the rolls 13 to 16 are arranged. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to 2 to obtain a stretched polysulfone film 20 having a thickness of 72 ± 2.5 μm.

A retardation plate sample was cut out from the stretched polysulfone film 20 obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 348 nm, the maximum variation in retardation value was 13.5 nm, and the maximum difference in retardation value between two points 1 cm apart was 3.7 nm.

Comparative Example 8 In Comparative Example 8, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) was put into a hopper of a single screw extruder (not shown), and diethyl phthalate (100 parts by weight of the thermoplastic resin) 3 parts by weight of a boiling point of 298 ° C. is press-fitted into a single screw extruder (not shown) with a plunger pump (not shown), melt-extruded from the T-die 1 at an extrusion temperature of 260 ° C., and a metal roll having a surface temperature of 140 ° C. 3 and the rubber roll 2 were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is guided between the rolls 4 and 5 and introduced into an oven 24 set at an atmospheric temperature 185 ° C. in which the rolls 6 to 12 are arranged, and a temperature of 185 ° C. in which the rolls 13 to 16 are arranged. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to 2 to obtain a stretched polysulfone film 20 having a thickness of 72 ± 2.5 μm.

A retardation plate sample was cut out from the stretched polysulfone film 20 obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 357 nm, the maximum variation in retardation value was 12.8 nm, and the maximum difference in retardation value between two points 1 cm apart was 3.3 nm.

Comparative Example 9 In Comparative Example 9, the manufacturing apparatus shown in FIG. 3 was used. A polysulfone resin pellet (Amoco, trade name: UDEL P3500, glass transition point 190 ° C.) was put into a hopper of a single screw extruder (not shown), and diethyl phthalate (100 parts by weight of the thermoplastic resin) 3 parts by weight of a boiling point of 298 ° C. is press-fitted into a single screw extruder (not shown) with a plunger pump (not shown), melt extruded from a T-die 1 at an extrusion temperature of 260 ° C., and a metal roll having a surface temperature of 140 ° C. 3 and the rubber roll 2 were nipped and cooled to obtain an unstretched polysulfone film 19 having a thickness of 83 μm ± 2.0 μm.

The unstretched film 19 is guided between the rolls 4 and 5 and is introduced into an oven 24 set at an atmospheric temperature 205 ° C. in which the rolls 6 to 12 are arranged, and a temperature of 175 ° C. in which the rolls 13 to 16 are arranged. The film was stretched uniaxially at a stretching ratio of 1.3 by a stretching machine 25 set to a polysulfone stretched film.

Next, the stretched polysulfone film obtained as described above was introduced into an oven 26 set at an atmospheric temperature of 170 ° C., stretched, and then slowly cooled to reach 170 ° C. after 1 minute, and a thickness of 72 ± 2 A polysulfone stretched film 20 having a thickness of 5 μm was obtained.

A retardation plate sample was cut out from the stretched polysulfone film 20 obtained as described above in the same manner as in Example 1 and evaluated. The average retardation value was 295 nm, the maximum variation in retardation value was 8.0 nm, and the maximum difference in retardation value between two points 1 cm apart was 2.5 nm.

Comparative Example 10 A polysulfone retardation plate having a thickness of 66 ± 2.5 μm was obtained in the same manner as in Example 9 except that 3 parts by weight of diethyl phthalate was used and there was no volatilization step.

The retardation value of the obtained polysulfone retardation plate was measured in the same manner as in Example 9. As a result, the average retardation value was 485 nm, the maximum variation was 12 nm, and the maximum difference in retardation values between two points 1 cm apart was 6 nm.

Comparative Example 11 A polysulfone retardation plate having a thickness of 69 ± 2.5 μm was obtained in the same manner as in Example 9 except that it was allowed to cool at 20 ° C. without a quenching step.

The retardation value of the obtained polysulfone retardation plate was measured in the same manner as in Example 9. As a result, the average retardation value was 275 nm, the maximum variation was 7 nm, and the maximum difference in retardation values between two points 1 cm apart was 4.5 nm.

The results of the conditions and retardation values of Examples 1 to 9 and Comparative Examples 1 to 11 are shown in Tables 1 to 4 below. In addition, the film temperature difference in the following Tables 1-4 shows (film temperature of the thickest part immediately after extending | stretching)-(film temperature of the thinnest part immediately after extending | stretching).

In the invention according to claim 1, it is a diagram for explaining a process in which the retardation value is made uniform by the rapid cooling process, and the magnitude of stress in the thick part and the thin part in the relaxation process after stretching and stretching. The figure for demonstrating. The schematic block diagram for demonstrating the manufacturing apparatus used in Examples 1-4 and Comparative Examples 1-4, 7, and 8. FIG. The figure which shows schematic structure of the manufacturing apparatus used in Examples 5-8 and Comparative Examples 5, 6, and 9. FIG. It is a cross-sectional view of the polysulfone unstretched film obtained in Example 1, and is a cross-sectional view for explaining variation in thickness in the width direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... T die 2 ... Rubber roll 3 ... Metal roll 4-18 ... Roll 19 ... Unstretched film 20 ... The thermoplastic resin film 21 after extending | stretching ... Air cooling device 22 ... Hot air apparatus

Claims (4)

When the thermoplastic resin film obtained by the melt extrusion molding method has Tg as the glass transition point, the temperature in the range of Tg to Tg + 60 ° C. and the thick part has a higher average temperature in the thickness direction than the thin part. Thus, immediately after carrying out uniaxial or biaxial stretching, it rapidly cools to Tg-20 degrees C or less, The manufacturing method of the phase difference plate characterized by the above-mentioned. The thickness difference R in the width direction represented by the following formula (1) of the thermoplastic resin film
Thickness difference R = {(maximum thickness−minimum thickness) / average thickness} / 2 × 100 (%)... (1) is ± A%, the thickest part of the thermoplastic resin film is the thickest part. A method for producing a retardation plate, wherein the film is stretched uniaxially or biaxially in a state where the average temperature in the thickness direction is higher by 0.1 A to 0.6 A ° C. than the thinnest portion. The temperature difference between the film before stretching and the film during stretching = (film temperature before stretching) − (film temperature during stretching) is in the range of 20 ° C. to 90 ° C. 3. A method for producing a phase difference plate. The thermoplastic resin film containing 0.2 to 20 parts by weight of a plasticizer with respect to 100 parts by weight of the thermoplastic resin is used as the thermoplastic resin film before stretching. Manufacturing method of the phase difference plate.

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