JPH08211224A - Phase difference compensating plate and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To obtain a phase difference compensating plate having high performance and excellent durability in which irregularity in phase difference is sufficiently lessened and peeling or production of bubbles is not caused on the adhering plane with a polarizing plate or a liquid crystal cell by specifying the amt. of a solvent contained in a polymer film which constitutes the phase difference compensating plate. CONSTITUTION: This phase difference compensating plate is produced by stretching a polymer film produced by a casting method so that the film has double refraction. The solvent content in the polymer film is specified to <2wt.%. By controlling the solvent content to <2wt.%, preferably in the range from 0.5 to 1.5wt.%, the width of distribution of the solvent amt. in various parts in the film plane is narrowed so that the amt. of the solvent in the film plane is almost made uniform. By controlling the solvent content to <2wt.%, adhesion strength or moisture resistance of an adhesive layer on the adhering interface of a polarizing plate or liquid crystal cell glass surface is hardly decreased while production of compressive stress in the phase difference compensating plate can be lessened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retardation compensating plate used in F-STN type liquid crystal display devices and the like, and a method for manufacturing the same, and more particularly to a retardation compensating plate prepared by stretching a polymer film prepared by a casting method. The present invention relates to a retardation compensating plate having a refractive property and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, STN liquid crystals capable of accommodating an increase in display capacity and a large screen and realizing high contrast have been used in liquid crystal display devices for personal computers and word processors. The liquid crystal display device using the STN liquid crystal has a display color mainly blue or yellow due to the elliptically polarized light due to the birefringence of the STN liquid crystal. The display color is changed to black and white by compensating for the phase difference.

Due to the difference in means for compensating for this phase difference,
The STN type liquid crystal display device includes a D-STN type liquid crystal display device in which a compensating liquid crystal cell having the same configuration as the liquid crystal display cell but having only a phase difference as an opposite phase is used in combination with the liquid crystal display cell, and a compensating liquid crystal cell instead of There is an F-STN system using a retardation compensator made of a refractive film. Of these, F-ST
Since the N method does not require a compensating liquid crystal cell, D-
Compared with the STN system, the display device is excellent in weight reduction and thinning, and is a preferable display device in consideration of cost merit.

The cell structure of a general F-STN type liquid crystal display device is such that a liquid crystal cell and one or two retardation compensating plates are combined in a sandwich structure between two polarizing plates in a parallel Nicol state. That is, the liquid crystal display element is formed by adhering the respective interfaces of the polarizing plate, the retardation compensating plate, and the glass surface of the liquid crystal cell via the adhesive layer.

Birefringent films used as retardation compensating plates for F-STN type liquid crystal display elements have generally been conventionally made of polycarbonate resins, cellulose resins, vinyl chloride resins, acrylic resins, styrene resins, Consists of a polymer film formed by molding a non-crystalline thermoplastic resin such as polyester resin, polysulfone resin, polyether sulfone resin, polyarylate resin, etc. into a film or sheet by the casting method, calendering method, melt extrusion method, etc. Then, by stretching this polymer film in the machine direction and the transverse direction, a retardation compensating plate having birefringence can be obtained.

The birefringent film used as a retardation compensator has not only transparency but also uniform retardation compensation in the film plane, and it is an important item in terms of quality that there is no retardation unevenness. Is. The retardation compensation performance is represented by a retardation value, which is defined by the product of the birefringence (Δn) and the thickness (d) of the retardation compensation plate. It is necessary that the birefringence and the film thickness are uniform so that there is no retardation unevenness in the film plane. Therefore, as a method for molding a polymer film, a casting method having a high film thickness uniformity is generally used.

However, unevenness of retardation often occurs during stretching of the polymer film, and as a countermeasure against this, JP-A-4-204503 discloses the content of a solvent (solvent) in the polymer film during stretching. A method for producing a retardation compensating plate having no retardation unevenness by stretching it at 2 to 10% by weight is disclosed.

However, as disclosed in Japanese Unexamined Patent Publication No. 4-204503, even if the solvent content in the polymer film at the time of stretching is set to 2 to 10% by weight and stretched, the polysulfone resin, etc. The reduction of the retardation unevenness of the retardation compensator obtained by stretching was insufficient.

Further, in the F-STN type liquid crystal display element, a change or a shock with time due to heat or moisture is caused at each bonding interface between the polarizing plate and the phase difference compensating plate and between the phase difference compensating plate and the liquid crystal cell glass surface. As a result, peeling and air bubbles are a problem in terms of quality, and this cannot be solved even in a retardation compensating plate having a solvent content of 2 to 10% by weight in a polymer film.

Further, a polymer solution dissolved in an organic solvent is cast on a cast substrate to form a film, and then dried to a solvent content such that phase difference unevenness does not occur during stretching on the substrate. Need to raise the drying temperature or lengthen the drying time. When the drying temperature is raised, foaming of the film is likely to occur, and when the drying time is extended at a moderate drying temperature, a huge drying facility is introduced or the production rate is reduced.

As a method for producing a retardation film by such a casting method, Japanese Patent Laid-Open No. 4-282212 discloses a method of casting a polymer solution dissolved in an organic solvent on a support of a running endless metal plate. In the method for producing a retardation film, which is formed into a film-like material, is dried, is peeled off from the support, and is further dried as a film. A method is disclosed in which the tension applied to the film and the drying temperature are regulated under the yield value or less.

However, in the above-mentioned method, if the amount of the residual solvent before the drying is large, only the entire surface can be dried slowly, and in order to achieve the target residual solvent amount, the drying equipment becomes huge or the production rate is significantly increased. The decline is inevitable.

[0013]

DISCLOSURE OF THE INVENTION The present invention has been made by paying attention to the above-mentioned problems, and has a sufficiently small unevenness in phase difference, and moreover, in terms of a bonding surface with a polarizing plate or a liquid crystal cell glass surface. It is an object of the present invention to provide a retardation compensating plate which does not generate peeling or bubbles and has high performance and excellent durability, and a manufacturing method having high productivity.

[0014]

Means for Solving the Problems As a result of studying the above-mentioned problems, the present inventors have found that the unevenness of retardation in the stretching step occurs because the solvent content of the cast film is non-uniform in the film plane. Due to the partial difference in stretchability, the film thickness after stretching, the orientation of the resin,
That is, it was found that the cause was unevenness in birefringence.

Further, as a result of studying the above-mentioned problems, the present inventors have found that the contact surface between the retardation compensating plate or the liquid crystal cell glass surface and the polarizing plate changes with time due to heat or moisture, or peels off or bubbles occur due to shock. Means that the organic solvent contained in the retardation compensator diffuses into the adhesive layer, lowers the mechanical strength of the adhesive layer, promotes the infiltration of moisture in the atmosphere from the end surface of the adhesive layer, and improves the adhesive strength. It was also found that the cause was a decrease in. It was also found that the organic solvent diffuses from the retardation compensating plate to the adhesive layer to cause contraction of the retardation compensating plate, and the stress generated thereby expands the peeling.

The inventors of the present invention conducted further studies to eliminate the influence of the organic solvent by regulating the organic solvent in the retardation compensating plate to a certain level or less in advance, and to eliminate the above-mentioned occurrence of the retardation unevenness. Further, the present invention has been accomplished by finding that the problems of peeling and bubbles can be solved. That is, according to the present invention, the above-mentioned object is that in a retardation compensating plate having birefringence by stretching a polymer film produced by a casting method, the solvent content of the polymer film is 2 It is achieved by a retardation compensating plate characterized by being less than wt%.

In order to achieve the above object, the method for producing a retardation compensating plate according to the present invention is a retardation compensating plate having birefringence obtained by stretching a polymer film produced by a casting method. In the production method of, the polymer film is stretched with a solvent content of less than 2% by weight.

In the present invention, the solvent content of the polymer film formed by the casting method is set to less than 2% by weight, preferably 0.5 to 1.5% by weight, so that each part in the film plane is The distribution width of the solvent content in can be narrowed, and the solvent content in the film plane can be made close to uniform. When the residual solvent amount is 2% by weight or more, the distribution width of the solvent content in the film plane becomes large, and uneven retardation is likely to occur during stretching.

The solvent content of the retardation compensating plate is 2% by weight.
When it is less than 1, the adhesive strength and moisture resistance of the adhesive layer at the adhesive interface with the polarizing plate or the liquid crystal cell glass surface are hardly reduced, and the generation of contraction stress of the retardation compensating plate due to the diffusion and volatilization of the solvent is suppressed. it can. As a result, a liquid crystal display cell having excellent durability can be obtained in which peeling or bubbles do not occur on the bonding surface between the retardation compensation plate and the polarizing plate or the liquid crystal cell glass surface.

When the solvent content is 2% by weight or more, peeling and bubbles are likely to occur at the bonding interface between the retardation compensating plate and the cell glass surface or the bonding interface between the retardation plate and the polarizing plate, and the solvent content is 10% by weight. If it is more than 0.1%, the glass transition temperature (hereinafter abbreviated as Tg) of the polymer film is lowered, so that the orientation is relaxed by heat in a heat resistance evaluation test and the like, which causes a problem that the retardation value (Re) is lowered.

The solvent content in the present invention means that when the weight of the film formed by the casting method is the sum of the solute (solid content) Wg and the contained solvent wg (W + w) g,
It is represented by w / W × 100 (%).

When a polymer film is produced by the casting method in the present invention, the solvent can be efficiently dried by containing a plasticizer. The drying temperature required to dry the solvent in the polymer film depends on the Tg of the polymer film, and heating the polymer film to a temperature above Tg facilitates diffusion of solvent molecules, resulting in quick drying. proceed. Therefore, by adding a plasticizer, Tg
By lowering the temperature, the drying temperature can be lowered and the drying time can be shortened.

The content of the plasticizer is 10% by weight or less, preferably 3 to 5% by weight, based on the polymer film. 1
If it is more than 0% by weight, stress relaxation during stretching becomes remarkable, and it becomes difficult to impart a retardation by stretching.

The plasticizer used in the present invention is not particularly limited as long as it has good compatibility with the resin and does not cause phase separation or bleed-out, and does not cause coloring. . As such a plasticizer, for example, a phthalic acid-based plasticizer, a phosphoric acid-based plasticizer, an adipic acid-based plasticizer, a citric acid-based plasticizer, a glycolic acid-based plasticizer, or the like can be applied. Diethyl phthalate, dicyclohexyl phthalate, butylbenzyl phthalate, tricresyl phosphate, methyl phthal / ethyl glycolate and the like are preferable. Further, two or more kinds of these plasticizers may be mixed and used.

In the method for producing a retardation compensating plate according to the present invention, a polymer solution dissolved in an organic solvent is cast on a cast substrate to form a film, which is then dried to obtain a solvent content of 15
It is characterized in that a polymer film of not more than wt% is formed, then the polymer film is peeled off and secondary drying is carried out, and the solvent content is made less than 2 wt% and stretched.

In the present invention, the polymer film dried and formed on the cast substrate has a solvent content of 15% by weight or less, but the polymer film is dried without a support in the secondary drying step. Therefore, the solvent content is 15% by weight
If it exceeds the range, elongation occurs in the polymer film and the high-quality retardation compensating plate aimed at by the present invention is not provided.

The polymer film to be used in the present invention includes, in addition to polycarbonate resins, styrene resins such as polystyrene and styrene-acrylonitrile copolymers, acrylic resins such as polymethyl methacrylate and polybutyl acrylate, and vinyl chloride resins. Examples thereof include resins, olefin resins such as polyethylene, polysulfone resins, polyethersulfone resins, engineering plastics such as polyphenylene oxide resins, and fibrin resins such as diacetyl cellulose and triacetyl cellulose.

The wavelength distribution of retardation due to the stretched polymer film depends on the birefringence of the polymer film and is evaluated by retardation. Among the polymer films, polysulfone is particularly preferable. Judging from these performances, is preferable as the phase difference compensating plate.

The above-mentioned polysulfone is a polymer having a sulfone group in the molecule, for example, polyallylsulfone obtained by condensation polymerization of sulfonyl chloride compounds such as 4-phenoxysulfonyl chloride, 4,4'-.
Polysulfone obtained by condensation polymerization of dihalogen diphenyl sulfone such as dichlorodiphenyl sulfone and sodium salt of diol such as bisphenol A, obtained by condensation polymerization of dihalogen diphenyl sulfone and diphenyl ether such as 4,4′-dichlorodiphenyl sulfone Polyether sulfone is preferably used. The glass transition temperature of the polysulfone is 190 ° C., and in addition to the above, it gives a polymer film excellent in transparency, heat resistance and the like.

The polysulfone-based resin may contain a low molecular weight polymer of polysulfone as in the plasticizer. These low molecular weight polymers exhibit the action of a plasticizer compounded in the polymer film, and have a glass transition temperature of 100 to 150 ° C., preferably 110, at a solvent content of polysulfone formed by a casting method. ~ 1
By setting the temperature in the range of 45 ° C., the drying temperature can be lowered and the drying time can be shortened. The plasticizer and the low molecular weight polymer of polysulfone may be added alone or in combination.

Further, the solvent is not particularly limited as long as it dissolves the polymer and does not cause a decrease in transparency due to crystallization during casting or an uneven film thickness. For example, when casting a polysulfone resin, anisole, dioxane, tetrahydropyran, methylene chloride, N-methylpyrrolidone, acetophenone or the like is used as a solvent. In particular, anisole is preferable because it has a small interaction with the polysulfone resin and can reduce the energy required for drying and removing the solvent.

In addition, when preparing a casting solution of the above-mentioned polymer, in addition to the above-mentioned solvent if necessary, it is compatible with these solvents to improve transparency and storage stability of the polymer solution such as polysulfone resin. Solution viscosity can be adjusted by using a poor solvent that does not impair the solution. The polymer solution viscosity is 1 × 10 ³ to
It is preferable to adjust it in the range of 1 × 10 ⁵ CPS in order to maintain a good coating appearance by leveling and to obtain smoothness of the coating film. If a poor solvent having a boiling point not higher than that of the solvent used is used, the temperature during drying can be lowered.

For example, in the case of preparing an anisole solution of polysulfone resin, anisole may be used alone, but the boiling point (about 154 ° C.) of anisole is lowered to further shorten the drying time and improve the coatability. In order to reduce the viscosity of the anisole solution and to improve the appearance of the coated product, it is compatible with the poor solvent, that is, anisole, and does not impair the transparency and storage stability of the polysulfone resin solution. ,
It has a lower boiling point than anisole and the solubility of polysulfone resin is lower than that of anisole (less than 1% by weight).
Solvents can be mixed. Examples of such a poor solvent include acetone, methyl ethyl ketone, ethyl acetate, toluene, phenol, and the like, and one kind or a mixture of two or more kinds thereof can be used.

When the above poor solvent is mixed with anisole,
The poor solvent is used in a range of 60% by weight or less based on the total weight of the solvent (mixture of anisole and the poor solvent). When the amount of the poor solvent exceeds 60% by weight, the solubility of polysulfone deteriorates, which causes generation of fish eyes and the like, which is not preferable.

When preparing a dioxane solution of a polysulfone resin, dioxane may be used alone,
In order to lower the boiling point of dioxane (about 102 ° C) and further shorten the drying time to improve the coatability, and to reduce the viscosity of the dioxane solution to improve the appearance of the coating. Poor solvent, that is, it is compatible with dioxane, does not impair the transparency and storage stability of the polysulfone resin solution, has a lower boiling point than dioxane, and the solubility of the polysulfone resin is lower than dioxane (1 wt% (Less than) solvents can be mixed. Examples of such a poor solvent include acetone, methyl ethyl ketone, ethyl acetate, toluene, phenol, and the like, and one kind or a mixture of two or more kinds thereof can be used.

When dioxane is mixed with the above poor solvent,
The poor solvent is used in the range of 60% by weight or less based on the weight of the total amount of the solvent (mixture of dioxane and poor solvent). When the poor solvent exceeds 60% by weight, as in the case of the above anisole,
This is not preferable because the solubility of polysulfone deteriorates and causes the generation of fish eyes and the like.

When preparing a tetrahydropyran solution of a polysulfone resin, tetrahydropyran may be used alone, but the boiling point of tetrahydropyran (about 88
(° C) to further shorten the drying time to improve the coatability, and to reduce the viscosity of the tetrahydropyran solution to improve the appearance of the coating, a poor solvent, that is, It is compatible with tetrahydropyran, does not impair the transparency and storage stability of the polysulfone resin solution, has a lower boiling point than tetrahydropyran, and the solubility of the polysulfone resin is lower than tetrahydropyran (less than 1% by weight). Solvents can be mixed. Examples of such a poor solvent include acetone, methyl ethyl ketone, ethyl acetate, toluene and phenol.
One kind or a mixture of two or more kinds can be used.

When tetrahydropyran is mixed with the poor solvent, the poor solvent is used in an amount of 60% by weight or less based on the total weight of the solvent (a mixture of tetrahydropyran and the poor solvent). When the amount of the poor solvent exceeds 60% by weight, the solubility of the polysulfone-based resin is deteriorated as in the case of anisole, which causes generation of fish eyes and is not preferable.

As the casting method in the present invention, a band type casting method or a drum type casting method may be used. It may also be cast on a long support film or sheet.

As the method for stretching the polymer film or sheet obtained by the casting method in the present invention, either longitudinal uniaxial stretching with a roll or lateral uniaxial stretching with a tenter can be used. Alternatively, sequential biaxial stretching or simultaneous biaxial stretching by a combination of these may be used. The stretching of the polymer film is a method in which the film is directly connected to a cast film forming apparatus and is provided in-line with a stretching device, and the film or sheet is once wound after the cast film forming,
Any of the methods of applying the film to a stretching device anew may be used.

[0041]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A polysulfone resin was dissolved in anisole to prepare a 35 wt% solution. Further, the resin 1
3 parts by weight of diethyl phthalate was mixed as a plasticizer with respect to 00 parts by weight. The resulting solution was cast on a polyimide support film using a comma coater,
It was dried at 3 ° C, 180 ° C and 210 ° C for 3 minutes each. The dried film has a thickness of 75 μm and the residual solvent amount is 1.9% by weight.
Met. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 130 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensating plate. The performance of the obtained retardation compensator is shown in Tables 1 and 5.

(Comparative Example 1) A 35 wt% anisole solution of polysulfone resin was cast on a polyimide support film using a comma coater, and the temperature was kept at 150 ° C for 180 ° C.
It was dried at 3 ° C and 210 ° C for 3 minutes each. The dried film had a thickness of 75 μm and the residual solvent amount was 5.3% by weight.
The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 130 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensating plate. The performance of the obtained phase difference compensator is
The results are shown in Table 1 and Table 5.

Example 2 A 35 wt% solution of polysulfone-based resin in anisole was prepared. Further, 5 parts by weight of dioctyl phthalate was added to the resin as a plasticizer. The resulting solution was cast on a polyimide support film using a comma coater, and then heated at 150 ° C, 180 ° C, 210 ° C.
It was dried at 5 ° C for 5 minutes each. The thickness of the film after drying is 75
μm, and the residual solvent amount was 0.7% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 130 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensating plate. The performance of the obtained retardation compensator is shown in Tables 1 and 5.

(Comparative Example 2) A 35% by weight solution of polysulfone-based resin in anisole was cast on a polyimide supporting film using a comma coater, and the temperature was kept at 150 ° C for 180 ° C.
It was dried at 5 ° C. and 210 ° C. for 5 minutes each. The dried film had a thickness of 75 μm and the residual solvent amount was 2% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated at 90 ° C. and stretched 1.7 times in the width direction to obtain a retardation compensating plate. The performance of the obtained retardation compensator is shown in Tables 1 and 5.

[0046]

[Table 1]

(Examples 3 and 4) Anisole solution (35% by weight) of polysulfone resin was cast on a polyimide supporting film using a comma coater, and solvent content (0.8% by weight and 1.6% by weight) was cast. ) Different polysulfone-based resin films were obtained.

(Examples 5 and 6) A solution of polysulfone-based resin in dioxane (25% by weight) was cast on a polyimide support film using a comma coater to obtain a solvent content (0.8% by weight and 1.6% by weight). ) Different polysulfone-based resin films were obtained.

(Comparative Examples 3 to 6) Anisole solutions (35% by weight) of polysulfone resin were cast on a polyimide support film using a comma coater, and the solvent contents were 2.5% by weight and 4.5% by weight, respectively. % And 7.3% by weight and 1
A 2.2 wt% polysulfone-based resin film was obtained.

(Comparative Examples 7 to 10) A dioxane solution (25% by weight) of a polysulfone resin was cast on a polyimide supporting film using a comma coater, and the solvent contents were 2.5% by weight and 4.5% by weight, respectively. % And 7.3% by weight and 1
A 2.2 wt% polysulfone-based resin film was obtained.

The polysulfone films of Examples 3 to 7 and Comparative Examples 3 to 10 were longitudinally uniaxially stretched by a stretching machine. Before stretching, the film thicknesses of the respective films were almost the same, and they did not have birefringence. On the other hand, the retardation compensation performance after stretching was as shown in Table 2.

[0052]

[Table 2]

(Example 7) The weight average molecular weight in terms of styrene obtained by copolycondensation of 4,4'-dichlorophenylsulfone and sodium salt of bisphenol A was 7 ×.
Dissolve 10 ⁴ polysulfone-based resin in anisole 3
A 5 wt% solution was prepared. Further, 3 parts by weight of diethyl phthalate was added as a plasticizer to 100 parts by weight of the above resin in the solution. The resulting solution was cast on a polyimide support film using a comma coater,
It was dried at 180 ° C. and 210 ° C. for 3 minutes each. The film after drying had a thickness of 75 μm and the residual solvent amount was 1.9 wt%, and the Tg at the residual solvent amount of 1.9 wt% was 126 ° C.
Met. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 130 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensating plate. The performance of the obtained retardation compensation plate is shown in Table 3.

(Comparative Example 11) A 35 wt% anisole solution of polysulfone resin prepared in the same manner as in Example 7 was cast on a polyimide support film using a comma coater at 150 ° C, 180 ° C and 210 ° C. It was dried for 3 minutes each. The dried film had a thickness of 75 μm and the residual solvent amount was 5.3% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 130 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensating plate.
The performance of the obtained retardation compensation plate is shown in Table 3.

Comparative Example 12 A 35 wt% anisole solution of a polysulfone resin prepared in the same manner as in Example 7 was cast on a polyimide support film using a comma coater, and the temperature was 150 ° C., 180 ° C. and 210 ° C. It was dried for 3 minutes each. The dried film had a thickness of 75 μm and a residual solvent amount of 3.6% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 140 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensating plate.
The performance of the obtained retardation compensation plate is shown in Table 3.

(Example 8) A 35% by weight anisole solution of a polysulfone resin prepared in the same manner as in Example 7 was added.
Furthermore, 3 parts by weight of dioctyl phthalate was added as a plasticizer to 100 parts by weight of the above resin. The obtained solution was cast on a polyimide support film using a comma coater and dried at 150 ° C., 180 ° C. and 210 ° C. for 5 minutes each. The dried film had a thickness of 75 μm, the residual solvent amount was 0.7% by weight, and the Tg at the residual solvent amount of 1.9% by weight was 125 ° C. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 150 ° C. and stretched 1.4 times in the width direction to obtain a retardation compensation plate.
The performance of the obtained retardation compensation plate is shown in Table 3.

Comparative Example 13 A 35 wt% anisole solution of a polysulfone-based resin prepared in the same manner as in Example 7 was cast on a polyimide support film using a comma coater, and the temperature was changed to 150 ° C., 180 ° C. and 210 ° C. It was dried for 10 minutes each. The dried film had a thickness of 75 μm and the residual solvent amount was 1.9% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 160 ° C. and stretched 1.3 times in the width direction to obtain a retardation compensating plate.
The performance of the obtained retardation compensation plate is shown in Table 3.

Example 9 A 35 wt% anisole solution of a polysulfone resin prepared in the same manner as in Example 7 was added,
Further, 5 parts by weight of diethyl phthalate was added as a plasticizer to 100 parts by weight of the above resin. The resulting solution was cast on a polyimide support film using a comma coater and dried at 150 ° C for 10 minutes. The film after drying had a thickness of 75 μm and the residual solvent amount was 1.9% by weight.
Tg was 110 ° C. The film thus obtained is subjected to a horizontal uniaxial tenter stretching machine heated to 110 ° C.,
It was stretched 1.7 times in the width direction to obtain a retardation compensation plate. The performance of the obtained retardation compensation plate is shown in Table 3.

Comparative Example 14 A 35 wt% anisole solution of polysulfone resin prepared in the same manner as in Example 7 was cast on a polyimide support film using a comma coater and dried at 180 ° C. for 10 minutes. The dried film had a thickness of 75 μm and the residual solvent amount was 4.2% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated to 130 ° C. and stretched 1.7 times in the width direction to obtain a retardation compensation plate. The performance of the obtained retardation compensation plate is shown in Table 3.

(Comparative Example 15) A 35 wt% anisole solution of a polysulfone resin prepared in the same manner as in Example 7 was further added as a plasticizer to 100 parts by weight of the above resin.
0 parts by weight of diethyl phthalate were added. The resulting solution was cast on a polyimide support film using a comma coater and dried at 150 ° C for 6 minutes. The dried film had a thickness of 75 μm and the residual solvent amount was 2% by weight. The film thus obtained was applied to a transverse uniaxial tenter stretching machine heated at 90 ° C. and stretched 1.7 times in the width direction to obtain a retardation compensating plate. The performance of the obtained retardation compensation plate is shown in Table 3.

[0061]

[Table 3]

As shown in Table 3, by adding a plasticizer to the polysulfone resin, the Tg was set to 100 to 150 ° C. to shorten the time required to dry the residual solvent amount to less than 2% by weight or to dry the resin. The temperature can be lowered. By thus adding the plasticizer, it is possible to obtain a retardation plate having extremely little unevenness in retardation.

Example 10 Anisole solution (35% by weight) of polysulfone resin was cast on a supporting film of polyethylene terephthalate using a comma coater and dried by hot air at 140 ° C. to have a solvent content of 10% by weight.
I got a cast film of. Then, the cast film was peeled off from the support film while suppressing the elongation, and the tension of the transfer cast film was set to 3 by a dryer provided with a gradient of a drying temperature of 150-170-200 ° C.
Secondary drying was carried out while maintaining at kg / m. The solvent content of the cast film after the secondary drying was 1.5% by weight. The performance of the obtained retardation compensation plate is shown in Table 4.

(Comparative Example 16) Using the same polysulfone-based resin anisole solution as in Example 5, the coating speed was increased by a comma coater and primary drying was performed to obtain a cast film having a solvent content of 19% by weight. Subsequent drying gave a cast film having a solvent content of 6.0% by weight.
During the secondary drying, the transfer cast film had a large elongation, the film width was narrowed, and vertical wrinkles were generated, and the obtained cast film could not be used as a product. The results are shown in Table 4.

Comparative Example 17 Using the same polysulfone-based resin anisole solution as in Example 5, the primary drying temperature was adjusted to 1
A cast film having a solvent content of 19% by weight was obtained at 20 ° C., and then the secondary drying temperature was 90-100-100.
The temperature was changed to a temperature gradient of ° C and the tension of the transfer cast film was lowered to 1 kg / m for secondary drying. The solvent content after secondary drying was 8.2% by weight, and a cast film that was hardly stretched was obtained. The results are shown in Table 4.

[0066]

[Table 4]

As described above, when the content of the solvent is less than 2% by weight, the retardation compensating performance having no or very little retardation can be obtained.

Then, the retardation compensating plates of Examples 1 to 9 and the retardation compensating plates of Comparative Examples 1 to 16 were all bonded to a polarizing plate via an adhesive layer under the same adhesive condition, and the retardation compensating plate was further bonded. All the retardation plate surfaces of the laminate of the polarizing plate and the polarizing plate were bonded to the glass surface via the adhesive layer under the same bonding conditions. Tables 5 and 6 show the results of the heat resistance and moisture resistance accelerated tests of these polarizing plates-retarders-glass laminates.

[0069]

[Table 5]

[0070]

[Table 6]

In Table 2, ◯ ... None, Δ ... Slight occurrence, X ... Significant occurrence.

[0072]

As can be understood from the above description, according to the retardation compensating plate and the manufacturing method thereof according to the present invention, the solvent content of the polymer film constituting the retardation compensating plate is limited to less than 2% by weight. As a result, a phase difference compensator with high performance and excellent durability, which has sufficiently little phase difference unevenness, and does not cause peeling or bubbles on the bonding surface with the polarizing plate or the liquid crystal cell glass surface. Can be provided.

Further, according to the retardation compensating plate and the method for producing the same according to the present invention, the polymer film constituting the retardation compensating plate contains the plasticizer, and the solvent content is limited to less than 2% by weight. By so doing, the solvent can be dried at a lower temperature and efficiently, the phase difference unevenness is sufficiently small, and further, peeling or bubbles are not generated on the adhesive surface with the polarizing plate or the liquid crystal cell glass surface, It is possible to provide a retardation compensator having excellent performance and durability.

Further, according to the retardation compensating plate and the method for producing the same according to the present invention, the polymer film constituting the retardation compensating plate has a solvent content of less than 2% by weight and a solvent content of 2%.
Glass transition temperature (Tg) of less than 100% by weight is 100 to 15
By limiting the temperature to 0 ° C., the solvent can be dried at a lower temperature and efficiently, the phase difference unevenness is sufficiently small, and peeling or bubbles are generated on the bonding surface with the polarizing plate or the liquid crystal cell glass surface. It is possible to provide a phase difference compensator having high performance and excellent durability.

Further, in the casting process of the polymer film, by providing the two-step heating means as described above, the unevenness of the phase difference is further reduced, and the peeling is caused at the adhesive surface to the polarizing plate or the liquid crystal cell glass surface. It is possible to provide a phase difference compensating plate that does not generate air bubbles or bubbles and has high performance and excellent durability.

Claims (7)

[Claims] 1. A retardation compensating plate having birefringence obtained by stretching a polymer film produced by a casting method, wherein the polymer film has a solvent content of less than 2% by weight. And a phase difference compensator. 2. A retardation compensating plate having birefringence obtained by stretching a polymer film produced by a casting method, wherein the polymer film contains a plasticizer, and the solvent content is 2 A retardation compensating plate characterized by being less than weight%. 3. A method for producing a retardation compensating plate having birefringence by stretching a polymer film produced by a casting method, wherein the solvent content of the polymer film is less than 2% by weight and stretched. A method for manufacturing a phase difference compensating plate, comprising: 4. A method for producing a retardation compensating plate having birefringence by stretching a polymer film produced by a casting method, comprising adding a plasticizer to the polymer film, and further comprising a solvent content. Of less than 2% by weight and stretching. 5. A method for producing a retardation compensating plate by stretching a polysulfone-based resin film produced by a casting method, wherein the solvent content of the polysulfone-based resin film is less than 2% by weight and the solvent content is 2 A method for producing a retardation compensating plate, which has a glass transition temperature (Tg) of less than 100% by weight of 100 to 150 ° C. 6. The method for producing a retardation compensating plate according to claim 6, wherein the polysulfone-based resin film produced by the casting method is a film produced by a casting method of an anisole solution of the polysulfone-based resin. . 7. A polymer solution dissolved in an organic solvent is cast on a cast substrate to form a film, and then dried to form a polymer film having a solvent content of 15% by weight or less, The retardation compensating plate according to claim 2, claim 4, claim 5 or claim 6, wherein the polymer film is peeled off, secondarily dried and stretched with a solvent content of less than 2% by weight. Manufacturing method.