JPH06174923A - Phase difference film - Google Patents

Abstract

PURPOSE:To provide a phase difference film having a R value, i.e., the ratio of the retardation values at specified wavelengths, which is within a specified range. CONSTITUTION:The phase difference film made of a material contg. polyarylate characterizes by the R value of the film which is the ratio (Re(400)/Re(550)) of the retardation value at 400nm (Re(400)) and that at 550nm (Re(550)), is within the range of 1.15 to 1.31. Thus the phase difference film having uniform double refractivity in the same plane and high transparency can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a retardation film. More specifically, the present invention relates to a retardation film having controlled wavelength dependence, which contains polyarylate having R, which is a ratio of retardation values at a specific wavelength, in a certain range as a component.

[0002]

2. Description of the Related Art As an optical film conventionally used in the field of liquid crystal display devices, the ratio of retardation values (R) is preferably a value which depends on the constitution (cell gap) of a liquid crystal cell. For this reason, PVA and PC are currently used, but the reality is that the value of R cannot be controlled sufficiently. In particular, a retardation film is used to improve the display quality of STN liquid crystal display devices.

The present inventors have already proposed a birefringent film using an aromatic polyester as a base film (Japanese Patent Laid-Open No. 63-101107).

In recent years, in order to improve the display quality of STN liquid crystal display devices, studies have been made to improve the responsiveness of STN liquid crystal display devices, but the retardation of the retardation film of polycarbonate which is mainly used at present is used. Since R is about 1.15 in the value ratio (R), the display quality for high-speed response is insufficient, and a larger R value is desired. As a way to overcome these challenges,
A method in which two films are stacked and used (JP-A-3-139
No. 17, Japanese Patent Laid-Open No. 3-13916, etc.) have been proposed.

However, in the above method, the cost is increased, it is difficult to adjust the angle of superposition of two films and the process such as adhesion, and further, the sufficient value of R cannot be obtained. There are problems such as.

The object of the present invention is to solve the above-mentioned conventional problems, and provides a retardation film containing as a component a polyarylate having a sufficient ratio of retardation values in the same plane. Especially.

[0007]

The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, by using a polymer having a specific composition, the retardation value at a specific wavelength can be reduced by one sheet. The inventors have found a retardation film capable of controlling the value of R, which is a ratio, within a certain range, and completed the present invention.

That is, the present invention relates to a retardation film containing a polyarylate, which is a ratio of the retardation value Re (400) at 400 nm to the retardation value Re (550) at 400 nm of R ( Re (400)
/ Re (550)) is 1.15 to 1.31.

[0009]

EXAMPLES The retardation film of the present invention comprises polyarylate, for example polyarylate or polyarylate and polycarbonate.

The polyarylate comprises a bisphenol component and a specific acid component.

Specific examples of the bisphenol component include 2,2-bis (4-hydroxyphenyl) propane, bis (3,5-dimethyl-4-hydroxyphenyl) methane and bis (3,5-dimethyl-4-). Examples thereof include, but are not limited to, hydroxyphenyl) sulfone and 4,4 '-(1-methylisobutylidene) bisphenol. The bisphenol components can be used alone or in combination.

Specific examples of the specific acid component include terephthalic acid and isophthalic acid.
It is not limited to these.

The polyarylate used in the present invention can be obtained by subjecting the bisphenol component and a specific acid component to a polymerization reaction such as an ordinary condensation reaction.

Specific examples of the polyarylate include those prepared from a mixture of 2,2-bis (4-hydroxyphenyl) propane, bis (3,5-dimethyl-4-hydroxyphenyl) methane, terephthalic acid and isophthalic acid. Polyester (hereinafter polyarylate 1
, Bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, polyester produced from a mixture of terephthalic acid and isophthalic acid (hereinafter referred to as polyarylate 2), and bis (3,5-dimethyl-4). -Hydroxyphenyl) sulfone, 2,2-bis (4-hydroxyphenyl) propane, polyester produced from a mixture of terephthalic acid and isophthalic acid (hereinafter referred to as polyarylate 3) and bis (3,5-dimethyl-
4-hydroxyphenyl) sulfone, 4,4 '-(1-
Methylisobutylidene) bisphenol, polyester (hereinafter referred to as polyarylate 4) produced from a mixture of terephthalic acid and isophthalic acid, (3,5-dimethyl-4-hydroxyphenyl) sulfone, 4,4 ′
A polyester made from a mixture of ethylidene bisphenol, terephthalic acid and isophthalic acid (hereinafter
Polyarylate 5) and the like, but are not limited thereto.

In producing the polyarylate 1,
The molar ratio of 2-bis (4-hydroxyphenyl) propane to bis (3,5-dimethyl-4-hydroxyphenyl) methane is usually 2/8 to 8/2, preferably 3/7 to 7 /. 3 and the molar ratio of terephthalic acid to isophthalic acid is usually 2/8 to 8/2, preferably 3
/ 7 to 7/3. The 2,2-bis (4-hydroxyphenyl) propane and bis (3,5-dimethyl-4-)
The ratio with hydroxyphenyl) methane is 2/8 in molar ratio.
When it is in the range of from 8 to 8, the solution stability of the polymer is preferable, and when the ratio of the terephthalic acid to the isophthalic acid is in the range of 2/8 to 8/2 in terms of molar ratio. Is preferable from the viewpoint of polymer solution stability.

The solution viscosity of the polyarylate 1 is η _sp
/ C (32 ° C, 0.32 g / deciliter in chloroform, the same applies hereinafter) is 0.5 to 2.0, preferably 0.6 to 1.5. When the physical properties of polyarylate 1 are within the above range, it is preferable from the viewpoint of film forming properties when casting a film from a polymer solution.

The ratio of terephthalic acid and isophthalic acid in the production of the polyarylate 2 is usually 2 in molar ratio.
/ 8 to 8/2, preferably 3/7 to 7/3.

When the molar ratio is within the above range, it is preferable from the viewpoint of solution stability of the polymer.

The solution viscosity of the polyarylate 2 is η _sp
It is desirable that / c is 0.5 to 2.0, preferably 0.6 to 1.5. When the physical properties of the polyarylate 2 are within the above range, it is preferable in terms of film forming properties when casting a film from a polymer solution.

The ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 2,2-bis (4-hydroxyphenyl) propane in the production of the polyarylate 3 is usually 100 / molar ratio. It is less than 0 to 5/95 or more, and the molar ratio of terephthalic acid to isophthalic acid is usually 2/8 to 8/2, preferably 3/7 to 7/3. The molar ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 2,2-bis (4-hydroxyphenyl) propane is less than 100/0 to 5/95.
In the case of the above range, it is preferable from the viewpoint that the wavelength dependence can be controlled by changing this ratio, and the ratio of the terephthalic acid to the isophthalic acid is in the range of 2/8 to 8/2 in terms of molar ratio. In some cases, it is preferable from the viewpoint of stability of the polymer solution.

The solution viscosity of the polyarylate 3 is η _sp
It is desirable that / c is 0.5 to 2.0, preferably 0.6 to 1.5. When the physical properties of polyarylate 3 are within the above range, it is preferable from the viewpoint of film-forming property when casting from a polymer solution.

The ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 4,4 '-(1-methylisobutylidene) bisphenol in the production of the polyarylate 4 is usually in a molar ratio. Less than 100/0 to 5/95
The above is the ratio of terephthalic acid to isophthalic acid in terms of molar ratio of usually 2/8 to 8/2, preferably 3/7 to 7 /.
It is 3. The bis (3,5-dimethyl-4-hydroxyphenyl) sulfone and 4,4 '-(1-methylisobutylidene) bisphenol have a molar ratio of 100/0.
In the range of less than 5/95 or more, the wavelength dependence can be controlled by changing this ratio, which is preferable.

The solution viscosity of the polyarylate 4 is η _sp
It is desirable that / c is 0.5 to 2.0, preferably 0.6 to 1.5. When the physical properties of the polyarylate 4 are within the above range, it is preferable from the viewpoint of film forming property when casting from a polymer solution.

The ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 4,4'-ethylidene bisphenol in the production of the polyarylate 5 is
The molar ratio is usually less than 100/0 to 5/95 or more, and the ratio of terephthalic acid to isophthalic acid is usually 2 /
It is 8 to 8/2, preferably 3/7 to 7/3. The molar ratio of the bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to the 4,4′-ethylidene bisphenol is
When it is in the range of less than 100/0 to 5/95 or more, the wavelength dependence can be controlled by changing the molar ratio, which is preferable.

The solution viscosity of the polyarylate 5 is η _sp
It is desirable that / c is 0.5 to 2.0, preferably 0.6 to 1.5. When the physical properties of the polyarylate 5 are within the above range, it is preferable from the viewpoint of film forming property when casting from a polymer solution.

The ratio (R) of the retardation values of the polyarylate is generally 1.195 to 1.31, for example, the R value of the polyarylate 1 is 1.20 to 1.22 and the R value of the polyarylate 2 is about 1.31. . In the polyarylate 2, bis (3,5) which is a bisphenol component
By replacing some of the dimethyl-4-hydroxyphenyl) sulfone with other bisphenol components, it is possible to prepare polyarylates 3 to 5 having R values in the range of 1.195 to 1.310, for example.

For example, in the polyarylate 3, the ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 2,2-bis (4-hydroxyphenyl) propane used as the bisphenol other than the above is adjusted. When the molar ratio is in the range of less than 100/0 to 5/95 or more, the value of R can be controlled in the range of 1.195 or more to less than 1.310.

Further, in the polyarylate 4,
The molar ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 4,4 '-(1-methylisobutylidene) bisphenol used as the other bisphenol is less than 100/0 to 5 /. When the range is 95 or more, the value of R can be controlled in the range of 1.220 or more and less than 1.310.

Further, in the polyarylate 5,
When the molar ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone to 4,4'-ethylidene bisphenol used as the other bisphenol is in the range of less than 100/0 to 5/95 or more, The value of R
It can be controlled in the range from 1.200 to less than 1.310.

The retardation film of the present invention is produced, for example, by an extrusion molding method or a casting method from a solution in which the polymer is dissolved in a solvent, and the like, from the viewpoint of film thickness accuracy and surface property. The solution casting method is preferred.

The solution casting method is not particularly limited as long as it is a method generally used when forming a thin film from a polymer material, but a polymer solution obtained by dissolving the polyarylate in a solvent such as methylene chloride is used. It is made by casting on a belt and finally elevating the temperature from about 40 ° C. to near the Tg of the polymer to evaporate the solvent. The coagulation conditions and post-treatment conditions of the film are not particularly limited, and may be those generally used for producing a retardation film.

The retardation film of the present invention thus obtained has a polymer Tg ± 20 ° C., preferably Tg.
The film is stretched 1.05 to 3 times, preferably 1.1 to 2 times in the range of ± 10 ° C. to cause birefringence (Δn), and Re = Δn · d (d
Is the retardation (R
e), the ratio (R) of the retardation values can be increased by using the polyarylates 1 to 5 alone.
The range from 1.195 to 1.310 is obtained.

(Retardation ratio (R)) R = Re (400) / Re (550) (I) where Re (400) is the retardation value at a wavelength of 400 nm and Re (550) is the retardation value at a wavelength of 550 nm. Indicates the foundation value.

The retardation film of the present invention has a thickness (d) of 30 to 200 μm, preferably 50 to 150 μm.

In the present invention, the polyarylate 1 is used.
When it is desired to make R smaller than R when used alone, R can be adjusted by using a polycarbonate having compatibility with polyarylate 1.

By using the polyarylate 1 and the polycarbonate in combination, the value of R can be arbitrarily adjusted within the range of the values of R of the polyarylate 1 and the polycarbonate. Therefore, if desired, the lower limit of the value of R of the polyarylate can be obtained. You can get less than 1.195.

Examples of the polycarbonate include (Teijin Panlite C-1300, Teijin Kasei Co., Ltd.), but are not limited thereto.

The weight ratio of the polyarylate 1 to the polycarbonate is 100/0 to 10/90. When the ratio of polyarylate 1 to polycarbonate is within the above range, the value of R can be controlled to 1.160 to 1.215.

Since the polyarylates 2 to 5 and the polycarbonate are not compatible with each other, when a film is produced from a mixture of these, the film is phase-separated into white turbidity when used as a film, and it may be used as a retardation film. I can't get what I can.

Polysulfones are resins having a large R value of about 1.3, but they have poor compatibility with polycarbonate and do not mix uniformly in a solvent such as methylene chloride. A usable film cannot be produced and cannot be used in combination with polycarbonate.

In the thus obtained retardation film containing the polyarylate of the present invention, the value of R (Re (400) / Re (550)), which is the ratio of retardation values, is the same as that of polyarylate 1 alone or polycarbonate. When used in combination, 1.150 to 1.215 can be obtained. By using polyarylates 2 to 5 respectively, 1.
195 to 1.310 can be obtained.

The retardation film of the present invention, if desired, may be an organic hard coat such as an acrylic or silicon type which is usually used on one or both sides for the purpose of surface protection.
It may have a hard coat layer made of an inorganic hard coat such as SiO ₂ or SiAlON, and further has a gas barrier layer made of an organic barrier such as an ethylene vinyl alcohol copolymer or vinylidene chloride or an inorganic barrier such as SiO _2. May be.

Next, the retardation film of the present invention will be explained based on synthesis examples and examples, but the present invention is not limited thereto.

Synthesis Example 1 (Synthesis of polyarylate 1-a) 2,2-bis (4-hydroxyphenyl) propane 20.
11 g (0.0882 mol), bis (3,5-dimethyl-4-hydroxyphenyl) methane 15.06 g (0.0588 mol), para-t-butylphenol 0.95 g (0.006 mol), sodium hydrosulfite 0.26 g, 5N NaOH aqueous solution 78.2 176.8 ml of water and
The mixture was placed in a 300 ml eggplant-shaped flask, mixed under a nitrogen atmosphere, and cooled to 5 ° C. to prepare an alkaline aqueous solution of dihydric phenol.

On the other hand, 21.32 g of terephthaloyl chloride
(0.105 mol), isophthalic chloride 9.14 g (0.04 mol)
50 mol) and 255 ml of methylene chloride another 3
The mixture was placed in a 00 ml eggplant-shaped flask, dissolved under a nitrogen atmosphere, and cooled to 5 ° C.

137 ml of water and 0.16 g of benzyltributylammonium chloride as a catalyst were placed in a 1 liter separable flask under a nitrogen atmosphere and cooled in the same manner. While vigorously stirring this, the above two solutions were continuously added simultaneously by pumping over 10 minutes.

After completion of the addition, stirring was continued for 2 hours, 0.42 g of benzoyl chloride dissolved in 5 ml of methylene chloride was added, and stirring was continued for 20 minutes, and then the stirring was stopped.

After decanting the aqueous layer, the same amount of water was added and neutralized with a small amount of hydrochloric acid while stirring. After repeating desalting by decanting and washing with water, the solution containing 300 ml of methylene chloride was heated to 40 to 50 ° C, and water in the liquid containing the polymer and methylene chloride was removed by azeotropic dehydration with methylene chloride. The methylene chloride was distilled until the polymer concentration became 15% (weight%, the same applies hereinafter).

The solution viscosity of the obtained polymer is η _sp / c
= 0.90.

Synthesis Example 2 (Synthesis of polyarylate 2-a) Bis (3,5-dimethyl-4-hydroxyphenyl) sulfone 44.98 g (0.147 mol), para-t-butylphenol 0.95 g, sodium hydrosulfite 0.26
g, 15.6 g of NaOH and 260 ml of water were put in a 300 ml eggplant-shaped flask, mixed under a nitrogen atmosphere and cooled to 5 ° C. to prepare an alkaline aqueous solution of a dihydric phenol. On the other hand, terephthalic acid chloride 15.23
g, 15.23 g of isophthalic acid chloride and 255 ml of methylene chloride were placed in another 300 ml eggplant-shaped flask, dissolved under a nitrogen atmosphere and cooled to 5 ° C.

120 ml of water and 0.11 g of tetrabutylphosphonium bromide as a catalyst were placed in a 1 liter separable flask under a nitrogen atmosphere and cooled in the same manner. While vigorously stirring this, the above two solutions were continuously added simultaneously by pumping over 10 minutes.

After completion of the addition, stirring was continued for 2 hours, 0.3 g of benzoyl chloride dissolved in 5 ml of methylene chloride was added, stirring was continued for 20 minutes, and then the stirring was stopped.

After decanting the aqueous layer, the same amount of water was added and neutralized with a small amount of hydrochloric acid while stirring. After repeating desalting by decanting and washing with water, the solution containing 300 ml of methylene chloride was heated to 40 to 50 ° C, and water in the liquid containing the polymer and methylene chloride was removed by azeotropic dehydration with methylene chloride. The methylene chloride was distilled until the polymer concentration was 18%.

The solution viscosity of the obtained polymer is η _sp / c
= 0.95, Tg determined by TMA method was 290 ° C.

Synthesis Example 3 (Synthesis of polyarylate 3-a) Bis (3,5-dimethyl-4-hydroxyphenyl) sulfone 20.79 g (0.0679 mol), 2,2-bis (4-hydroxyphenyl) propane 15.49 g (0.0679 mol),
Para-t-butylphenol 0.62 g, sodium hydrosulfite 0.48 g, NaOH 13.44 g and water 224.
4 ml was put in a 300 ml eggplant-shaped flask, mixed in a nitrogen atmosphere and cooled to 5 ° C. to prepare an alkaline aqueous solution of dihydric phenol. On the other hand, 13.99 g of terephthalic acid chloride and 1 of isophthalic acid chloride
Another 300 g of 3.99 g and 233 ml of methylene chloride
It was placed in a milliliter eggplant-shaped flask, dissolved in a nitrogen atmosphere, and cooled to 5 ° C.

140 ml of water and 0.14 g of tetrabutylphosphonium bromide as a catalyst were placed in a 1 liter separable flask under a nitrogen atmosphere and cooled in the same manner. While vigorously stirring this, the above two solutions were continuously added simultaneously by pumping over 10 minutes.

After completion of the addition, stirring was continued for 2 hours, 0.42 g of benzoyl chloride dissolved in 5 ml of methylene chloride was added, and stirring was continued for 20 minutes, and then the stirring was stopped.

After decanting the aqueous layer, the same amount of water was added and the mixture was neutralized with a small amount of hydrochloric acid while stirring. After repeating desalting by decanting and washing with water, the solution containing 300 ml of methylene chloride was heated to 40 to 50 ° C, and water in the liquid containing the polymer and methylene chloride was removed by azeotropic dehydration with methylene chloride. The methylene chloride was distilled until the polymer concentration was 18%.

The solution viscosity of the obtained polymer is η _sp / c
= 0.85, Tg determined by TMA method was 240 ° C.

Synthesis Example 4 (Synthesis of polyarylate 4-a) In Synthesis Example 3, 18.33 g of 4,4 '-(1-methylisobutylidene) bisphenol was used in place of 2-bis (4-hydroxyphenyl) propane. Other than that used in Synthesis Example 3
Polyarylate 4-a was obtained in the same manner as in.

The solution viscosity of the obtained polymer is η _sp / c
= 0.88, Tg determined by TMA method was 185 ° C.

Synthesis Example 5 (Synthesis of polyarylate 5-a) Synthesis Example 3 except that 14.53 g of 4,4'-ethylidene bisphenol was used in place of 2-bis (4-hydroxyphenyl) propane in Synthesis Example 3. Polyarylate 5-a was obtained in the same manner as in.

The solution viscosity of the obtained polymer is η _sp / c
= 0.85, Tg determined by TMA method was 170 ° C.

Example 1 A methylene chloride solution of polyarylate 1-a obtained in Synthesis Example 1 was mixed, cast on a SUS plate, allowed to stand at room temperature for 1 hour, peeled off the film, and exposed with a 4-side fixing jig. It was dried under the conditions shown in 1 to obtain a film having a thickness of about 100 μm.

A 11 cm × 11 cm sample was made from this film, and a stretching test device (Toyo Seiki Seisakusho, X4HD-H) was used.
T) at the temperature shown in Table 1, and a microscopic polarization spectrophotometer (TFM-120 AFT) manufactured by Oak Manufacturing Co., Ltd.
Retardation value at 0 nm (Re (400)) and 55
The retardation value (Re (550)) at 0 nm was measured. The physical properties of the obtained film were determined under the conditions of a stretching speed of 10 cm / min (100% / min) and a stretching ratio of 1.2 times. The results are shown in Table 1.

Examples 2 to 5 A solution prepared by dissolving 100 g of a polycarbonate resin (Teijin Panlite C-1300, manufactured by Teijin Kasei Co., Ltd.) in 300 ml of methylene chloride was prepared, and the polyarylate 1 obtained in Synthesis Example 1 was prepared. It was mixed with the methylene chloride solution of -a at the ratio shown in Table 1. These solutions were cast on a SUS plate, allowed to stand at room temperature for 60 minutes, peeled off the film, sandwiched between four-piece fixing jigs and dried under the conditions shown in Table 1 to obtain a film of about 100 μm.

A 11 cm × 11 cm sample was cut from this film, and a stretching tester (Toyo Seiki Seisakusho, X4HD-
HT) at the temperature shown in Table 1, and manufactured by Oak Manufacturing Co., Ltd.
The retardation values (Re (400) and Re (550)) were measured using a microscopic polarization spectrophotometer (TFM-120 AFT). The physical properties of the obtained film were determined under the conditions of a stretching speed of 10 cm / min (100% / min) and a stretching ratio of 1.2 times. The results are shown in Table 1.

[0068]

[Table 1]

Example 6 A solution of the polyarylate 2-a obtained in Synthesis Example 2 in methylene chloride was mixed, cast on a SUS plate, allowed to stand at room temperature for 1 hour, peeled off, and exposed with a 4-side fixing jig. It was dried under the conditions shown in 2 to obtain a film having a thickness of about 100 μm.

A 11 cm × 11 cm sample was prepared from this film, and a stretching tester (Toyo Seiki Seisakusho, X4HD-H) was used.
T) at the temperature shown in Table 2 and using a microscopic polarization spectrophotometer (TFM-120 AFT) manufactured by Oak Manufacturing Co., Ltd.
Retardation value at 0 nm (Re (400)) and 55
The retardation value (Re (550)) at 0 nm was measured. The physical properties of the obtained film were determined under the conditions of a stretching speed of 10 cm / min (100% / min) and a stretching ratio of 1.2 times. The results are shown in Table 2.

Example 7 A solution of the polyarylate 3-a obtained in Synthesis Example 3 in methylene chloride was mixed in the proportions shown in Table 2, cast on a SUS plate, allowed to stand at room temperature for 1 hour, and then the film was peeled off. The film was dried with an edge fixing jig under the conditions shown in Table 2 to obtain a film having a thickness of about 100 μm.

A 11 cm × 11 cm sample was made from this film, and a stretching test device (Toyo Seiki Seisakusho, X4HD-H) was used.
T) at the temperature shown in Table 2 and using a microscopic polarization spectrophotometer (TFM-120 AFT) manufactured by Oak Manufacturing Co., Ltd.
Retardation value at 0 nm (Re (400)) and 55
The retardation value (Re (550)) at 0 nm was measured. The physical properties of the obtained film were determined under the conditions of a stretching speed of 10 cm / min (100% / min) and a stretching ratio of 1.2 times. The results are shown in Table 2.

Examples 8 to 9 Physical properties of the obtained film were determined in the same manner as in Example 7 except that the proportion of bisphenol of polyarylate 3-a in Synthesis Example 3 was changed to the ratio shown in Table 2. The results are shown in Table 2.

[0074]

[Table 2]

Example 10 A solution of polyarylate 4-a obtained in Synthesis Example 4 in methylene chloride was mixed in the proportions shown in Table 3, cast on a SUS plate, allowed to stand at room temperature for 1 hour, and then the film was peeled off. The film was dried with an edge fixing jig under the conditions shown in Table 3 to obtain a film having a thickness of about 100 μm.

A 11 cm × 11 cm sample was made from this film, and a stretching tester (X4HD-H, Toyo Seiki Seisakusho, Ltd.) was used.
T) at the temperature shown in Table 3 and using a microscopic polarization spectrophotometer (TFM-120 AFT) manufactured by Oak Manufacturing Co., Ltd.
Retardation value at 0 nm (Re (400)) and 55
The retardation value (Re (550)) at 0 nm was measured. The physical properties of the obtained film were determined under the conditions of a stretching speed of 10 cm / min (100% / min) and a stretching ratio of 1.2 times. The results are shown in Table 3.

Examples 11 to 12 Physical properties of the obtained film were determined in the same manner as in Example 10 except that the proportion of bisphenol of polyarylate 4-a in Synthesis Example 4 was changed to the ratio shown in Table 3. The results are shown in Table 3.

[0078]

[Table 3]

Example 13 A solution of the polyarylate 5-a obtained in Synthesis Example 5 in methylene chloride was mixed, cast on a SUS plate, allowed to stand at room temperature for 1 hour, peeled off the film, and exposed with a 4-side fixing jig. It was dried under the conditions shown in 4 to obtain a film having a thickness of about 100 μm.

A 11 cm × 11 cm sample was made from this film, and a stretching test device (Toyo Seiki Seisakusho, X4HD-H) was used.
T) and stretched at the temperature shown in Table 4 using a microscopic polarization spectrophotometer (TFM-120 AFT) manufactured by Oak Manufacturing Co., Ltd.
Retardation value at 0 nm (Re (400)) and 55
The retardation value (Re (550)) at 0 nm was measured. The physical properties of the obtained film were determined under the conditions of a stretching speed of 10 cm / min (100% / min) and a stretching ratio of 1.2 times. The results are shown in Table 4.

Examples 14 to 15 Physical properties of the obtained film were determined in the same manner as in Example 13 except that the proportion of bisphenol of polyarylate 5-a in Synthesis Example 5 was changed to the ratio shown in Table 4. The results are shown in Table 4.

[0082]

[Table 4]

[0083]

According to the present invention, it is possible to provide a plastic film having uniform birefringence in the same plane and high transparency.

Claims (7)

[Claims] 1. A retardation film containing a polyarylate, which has a retardation value Re (400) at 400 nm and a retardation value R at 550 nm.
The ratio R (Re (400) / Re (550)) of e (550) is 1.
A retardation film having a thickness of 15 to 1.31. 2. The polyarylate is 2,2-bis (4-
A compound prepared from a mixture of hydroxyphenyl) propane, bis (3,5-dimethyl-4-hydroxyphenyl) methane, terephthalic acid and isophthalic acid.
The retardation film described. 3. The retardation film according to claim 1, wherein the material containing polyarylate is a mixture of polyarylate and polycarbonate. 4. The polyarylate comprises a bisphenol component and an acid component, and the bisphenol component has a molar ratio of bis (3,5-dimethyl-4-hydroxyphenyl) sulfone and one or more other bisphenol components. 5. The retardation film according to claim 1, wherein the retardation film is 5/95 to 100/0 and the acid component is terephthalic acid and isophthalic acid. 5. The other bisphenol component,
The retardation film according to claim 4, which is 2,2-bis (4-hydroxyphenyl) propane. 6. The other bisphenol component,
The retardation film according to claim 4, which is 4,4 '-(1-methylisobutylidene) bisphenol. 7. The other bisphenol component,
The retardation film according to claim 4, which is 4,4'-ethylidene bisphenol.