JP2950709B2 - Method for producing polysulfone resin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a solution casting method,
The present invention relates to a method for producing a high quality polysulfone resin film having excellent transparency and the like.

[0002]

2. Description of the Related Art Polysulfone resin films are excellent in various properties such as mechanical strength, electrical properties, transparency, heat resistance, chemical resistance, and flame retardancy. It is used as an optical filter such as a phase difference plate of a device.

[0003] This kind of polysulfone resin film is generally produced by a melt extrusion method and a solution casting method. The film obtained by the solution casting method has very few fish eyes, is excellent in appearance, surface smoothness, transparency and thickness accuracy, and has relatively low solution viscosity, so foreign matter is removed by a filter with a fine opening. And is superior to the melt extrusion method in these points.

When a polysulfone resin film is produced by a solution casting method, a methylene chloride solution of a polysulfone resin is widely used as a resin solution for casting. Then, the resin solution is cast on a support by a suitable coater, and thereafter, the solvent is evaporated, and the thus formed film is peeled off from the support to obtain a polysulfone resin film (for example, see Japanese Unexamined Patent Publication No. -111511).

[0005]

Methylene chloride is a non-flammable polar solvent having a low boiling point (about 40 ° C.) and good drying efficiency, and is an excellent solvent in this respect. However, when the polysulfone resin is dissolved in methylene chloride, the polysulfone resin contains as an impurity a cyclized product by-produced during its synthesis, which gradually crystallizes in a solution over time to form a methylene chloride. It becomes insoluble and its crystals precipitate in the resin solution in the process.

As a result, if crystals are precipitated in a step before casting on a support, the filter is clogged. Further, when crystals are precipitated in the step after casting on the support, the transparency of the film is reduced, and foaming with crystals as nuclei occurs, which causes problems such as poor appearance.

[0007] Further, methylene chloride has a low moving speed in the resin, and is rapidly evaporated and dried on the surface of the resin solution. Therefore, a so-called film-sintering phenomenon occurs in the initial stage of drying, and particularly, polysulfone having a thickness of 50 µm or more. When a resin film is produced, methylene chloride may be trapped between the film or the film and the support, and the film may be foamed. Therefore, if the drying is carried out with care while preventing the foaming, there is a problem that the drying time becomes longer and the productivity is reduced.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide a polysulfone resin film having excellent appearance, surface smoothness, transparency, and thickness accuracy by a solution casting method. , And a method of manufacturing with high productivity.

[0009]

Means for Solving the Problems A method of manufacturing a polysulfone resin film of the present invention is a process for producing a polysulfone resin film by a solution casting method, a casting resin solution, acetophenone dissolved solution of polysulfone resin <br The above-mentioned object can be achieved.

The polysulfone resin used in the present invention includes a Udel polysulfone resin in which polymer molecules are constituted by paraphenylene linked by sulfone, ether and isopropylidene, and a polymer molecule in which polymer molecules are linked by sulfone and ether. And polyether sulfone resins composed of paraphenylene, and those having a weight average molecular weight (polystyrene conversion) of about 20,000 to 100,000 by GPC measurement method are suitable.

[0011] Then, as casting resin solution, so like polysulfone resin dissolved in acetophenone down, preparing acetophenone solvent solution of polysulfone resin. In this case, it is preferable to adjust the concentration of the polysulfone resin so that the solution viscosity is in the range of 2 × 10 ³ to 1 × 10 ⁵ cps. For example, weight average molecular weight (polystyrene conversion)
When using about 70,000 polysulfone resin,
It is preferable to adjust the resin concentration to about 40% by weight.

[0012] When preparing this of the resin solution may be used in aceto <br/> phenolate down alone, but the boiling point (about 202 ° C.) is relatively high, even more drying time by lowering the boiling point to shorten, and acetophenone down is compatible, without impairing the transparency and storage stability of the resin solution may be mixed with a relatively low boiling solvent. As these solvents, for example, at least one of acetone, methyl ethyl ketone, ethyl acetate, and toluene is suitably used.

[0014] acetophenone down, acetone described above, methyl ethyl ketone, ethyl acetate, in the case of mixing a low boiling point solvent such as toluene is used in an amount of 60 wt% or less of the entire solvent. If the low boiling point solvent exceeds 60% by weight, the solubility of the polysulfone resin becomes poor.

A plasticizer may be added to the polysulfone resin solution, if necessary, to improve the flexibility of the film. Examples of the plasticizer include phthalic acid, phosphoric acid, adipic acid, citric acid, and glycolic acid, and particularly, butylbenzyl phthalate, tricresyl phosphate, and methylphthalylethyl glycolate are preferable. is there.

[0016] acetophenone dissolved solution of polysulfone resin prepared in this manner by known solution casting method,
With a comma coater, lip coater, doctor blade coater, bar coater, roll coater, etc., the film is cast on an endless band or drum-shaped support, and the solvent is evaporated by heating and drying. And continuously obtain a long polysulfone resin film. In addition, a short polysulfone resin film can be obtained by a batch method using a sheet-like support.

The material of the support may be a metal such as copper or stainless steel, a synthetic resin, a material in which the surface of the metal or synthetic resin is coated with glass or ceramic, or a material in which the surface of the support is coated with a silicon resin or the like. What has been release-treated with a fluororesin or the like is used.

The heating and drying of cast resin solution on a support, at a heating rate such that the film-like material does not foam, Asetofe <br/> Bruno emission temperature above the boiling point, for example, up to 220 to 230 ° C. It is performed by heating.

Thus, a polysulfone resin film is manufactured. The thickness of the film varies depending on the application, but is generally about 10 to 250 μm. This film is used as it is without stretching. The film is used after being subjected to a process such as stretching.

[0020]

[Action] In the process for preparing the polysulfone resin film by a solution casting method, a casting resin solution, the use of acetophenone dissolved solution of polysulfone resin, by the action of the acetone <br/> Tofeno down, this resin Crystallization of the existing cyclized product (impurity) in the resin solution is suppressed,
Precipitation of crystals in the resin solution does not occur, and as a result, foaming of the film and reduction in transparency are prevented.

Further, acetophenone emissions are all the shifting speed in the polysulfone resin, and since the slow evaporation drying of the surface of the resin solution, hardly occurs so-called membrane-covered phenomenon in dry initial, in particular, 50 [mu] m or more thickness Even in the case of producing a film of the above, foaming in the film-like material is prevented, and therefore, it is possible to increase the heating rate and to rapidly heat and dry, thereby shortening the drying time.

[0022]

EXAMPLES Examples and comparative examples of the present invention will be described below. Example 1 Udel polysulfone resin (P-3500: manufactured by Amoco Japan) having a weight average molecular weight (in terms of polystyrene) of about 70,000 was dissolved in acetophenone to prepare an acetophenone solution of a polysulfone resin having a solid content of 15% by weight. did.

This solution is applied on a polyester film by a roll coater and placed in a heating oven at 170 ° C. to a temperature of 230 ° C. at a heating rate as high as possible to prevent foaming of the applied film. The temperature was raised and the film was dried until the amount of the residual solvent in the film became 1% by weight or less. Thereafter, the film was peeled off to obtain a polysulfone resin film having a thickness of 50 μm.

The above drying time was 1 minute and the drying was completed in a short time. The haze of the obtained film was 0.1.
16%, having a smooth surface and excellent transparency.
Excellent thickness accuracy.

[0025] The polysulfone resin used in Example 1 was dissolved in a mixed solvent of an equal weight of acetophenone and methyl ethyl ketone, solid concentration of 30 wt% of polysulfone resin acetophenone, was prepared methyl ethyl ketone mixed-solution.

This solution is applied onto a polyester film by a roll coater and placed in a heating oven at 170 ° C. to 230 ° C. at a heating rate as high as possible to prevent foaming of the applied film. The temperature was raised and the solvent was dried until the amount of the residual solvent became 1% by weight or less. Thereafter, the film was peeled off to obtain a polysulfone resin film having a thickness of 100 μm.

The drying time is as short as 3 minutes, the haze of the obtained film is 0.21%, the surface is smooth, the transparency is excellent, and the thickness accuracy is also excellent.

Example 3 The acetophenone solution of the polysulfone resin used in Example 1 was applied on a stainless steel plate using a lip coater.
This is placed in a heating oven at 170 ° C. and heated at a heating rate as high as possible to prevent foaming of the applied film.
The temperature was increased to 30 ° C., and the film was dried until the amount of the residual solvent became 1% by weight or less.
A μm polysulfone resin film was obtained.

The above drying time is as short as 3 minutes, the haze of the obtained film is 0.22%, the surface is smooth, the transparency is excellent, and the thickness accuracy is also excellent.

Example 4 The acetophenone solution of the polysulfone resin used in Example 1 was applied on a glass-coated stainless steel plate using a lip coater, and then placed in a heating oven at 170 ° C. to foam the applied film. The temperature was raised to 230 ° C. at a heating rate as fast as possible so that no residual solvent was generated, dried until the residual solvent amount became 1% by weight or less, and then the film was peeled off to obtain a polysulfone resin film having a thickness of 100 μm. Was.

The above drying time is as short as 3 minutes, the haze of the obtained film is 0.19%, the surface is smooth, the transparency is excellent, and the thickness accuracy is also excellent.

Comparative Example 1 The polysulfone resin used in Example 1 was dissolved in methylene chloride to prepare a methylene chloride solution of the polysulfone resin having a solid content of 15% by weight.

This solution is applied on a polyester film by a roll coater and placed in a heating oven at 30 ° C. to a temperature of 200 ° C. at a heating rate as fast as possible to prevent foaming of the applied film. The temperature was raised and the film was dried until the amount of the residual solvent in the film became 1% by weight or less. Thereafter, the film was peeled off to obtain a polysulfone resin film having a thickness of 50 μm.

The above drying time was 6 minutes, which was longer than that of Example 1, and the haze of the obtained film was 0.54.
% Was higher than that of Example 1.

Comparative Example 2 In Comparative Example 1, the solid content concentration of the solution was changed to 30% by weight, and the thickness of the polysulfone resin film was changed to 100 μm.
Changed to m. Other than that, it carried out similarly to the comparative example 1.

In this case, the drying time was 10 minutes, which was longer than that of Comparative Example 1, and the haze of the obtained film was haze.
Was 0.58%, which was slightly higher than Comparative Example 1.

[0045]

[Effect of the Invention] described above as method for producing a polysulfone resin film of the present invention is a process for producing a polysulfone resin film by a solution casting method, a casting resin solution, use acetophenone solvent solution of polysulfone resin < Therefore, even if the thickness of the film is 50 or more, a polysulfone resin film having excellent quality such as appearance, surface smoothness, transparency, and thickness accuracy can be obtained with good productivity. Can be manufactured.

The polysulfone resin film obtained according to the present invention has excellent quality as described above and excellent properties such as mechanical strength, electrical properties, heat resistance, chemical resistance, and flame retardancy. Can be used for a wide range of applications. In particular, this film can be suitably used as an optical filter such as a retardation plate of a liquid crystal display device by subjecting the film to a process such as stretching.

Claims (2)

(57) [Claims] 1. A method for producing a polysulfone resin film by a solution casting method, wherein the casting resin solution is
Method of manufacturing a polysulfone resin film, which comprises using acetophenone solvent solution of polysulfone resin. To 2. A acetophenone dissolved solution according to claim acetone, methyl ethyl ketone, ethyl acetate, at least one solvent of toluene, characterized in that it is contained in an amount of 60 wt% or less of the entire solvent 1 A method for producing the polysulfone resin film according to the above.