JPH10323852A - Production of polyether-sulfone resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably and efficiently producing a high quality polyether-sulfone resin film that can improve the stability of filtrate of polyether-sulfone resin solution, without white turbidity, thickening and solidification with a lapse of time and enable a stable casting. SOLUTION: A polyether-sulfone resin film production method comprises the steps of filtering by filter 5 a polyether-sulfone resin solution that is obtained by allowing a polyether-sulfone resin 1 to be dissolved in methylene chloride, casting the filtrate on a substrate, drying the solution so cast, and separating a polyether-sulfone resin from the substrate, and the filtering of the polyether- sulfone resin solution is carried out under a filtering pressure of 5 kg/cm<2> G or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyether which is obtained by filtering a solution obtained by dissolving a polyether sulfone resin in methylene chloride using a filter, casting it on a support, drying it, and peeling it off from the support. The present invention relates to an improvement in a method for producing a sulfone resin film.

[0002]

2. Description of the Related Art As a method for producing a polyethersulfone resin film, a solution in which a polyethersulfone resin solution is extruded from a casting device such as a die, cast on a support such as a metal belt, and dried and peeled. There is a casting method. The film obtained by the solution casting method has a small amount of foreign matter, and can provide a film having excellent thickness accuracy and surface smoothness. In particular, in recent years, a film produced by this solution casting method has been used as a raw material for a retardation film or a liquid crystal display film such as a polarizing protective film.

[0003] In order to obtain a film of a quality that can be used in such applications, foreign substances (such as high molecular weight substances contained in the raw material resin, insoluble substances generated by crosslinking, and dust mixed from the environment) in the polyethersulfone resin solution are used. ) Must be removed to such an extent that there is no problem in the application of the film. Such foreign matter is usually removed by filtering the polyethersulfone resin solution using a filter. If the film is used for optical applications such as liquid crystal display, a filter having a fine aperture of 10 μ or less is used.

[0004]

However, the stability of the filtrate of the resin solution obtained by dissolving the polyethersulfone resin in methylene chloride is low, and the solution may become cloudy, thicken, or solidify over time. As a result, there has been a problem that the resin solution outlet of the casting apparatus is blocked or normal casting is hindered, making it difficult to form a film, and impairing the smoothness and optical properties of the film surface. Also, cloudiness,
Since the thickened and solidified filtrate can no longer be used for film formation, it is necessary to dissolve the resin and repeat the filtration,
There were also problems such as an increase in cost and a decrease in production efficiency.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for solving the above-mentioned problems, and as a result, when filtering a polyethersulfone resin solution, the filtration pressure was reduced to 5%.
It was found that the filtrate of the polyethersulfone resin solution was stabilized by keeping the pressure at or below kg / cm ² G,
The present invention has been reached.

That is, according to the present invention, a polyethersulfone resin solution obtained by dissolving a polyethersulfone resin in methylene chloride is filtered using a filter, cast on a support, dried, and then separated from the support. In the method for producing a polyethersulfone resin film, the filtration pressure of the polyethersulfone resin solution is 5 kg / c.
A method for producing a polyethersulfone resin film, wherein the method is carried out at m ² G or less. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethersulfone resin in the present invention is a polymer comprising the following repeating structural units 5 or 6, a copolymer having them in any ratio, or a composition containing them in any ratio. Things.

[0008]

Embedded image [-Ph-SO ₂ -Ph-O-]

[0009]

[-Ph-SO ₂ -Ph-OAO-] In the formulas (5) and (6), Ph represents a paraphenylene group;
Represents the following formula (7) or (8).

[0010]

Embedded image In the formula, n represents an integer of 1 to 4.

[0011]

Embedded image In the formula, B represents an alkylene group having 1 to 3 carbon atoms, an oxygen atom or a sulfur atom, and m represents an integer of 1 to 3.

These polyether sulfone resins are obtained, for example, by copolycondensation polymerization of 4,4'-dichlorodiphenyl sulfone and bisphenol S, and are aromatic polyether sulfone polymers having a sulfone group and an ether group in a repeating unit. And the like. Furthermore, 4,4'-
Copolymers of dichlorodiphenyl sulfone with 4,4'-dihydroxydiphenyl sulfone and other compounds are also used. Examples of compounds to be copolymerized include 2,2 ′
-Dihydroxydiphenyl, 4,4'-dihydroxydiphenyl, hydroquinone, bisphenol A and the like.

The concentration of the polyethersulfone resin in the polyethersulfone resin solution obtained by dissolving the polyethersulfone resin in methylene chloride is not particularly limited.
It is about t%. The viscosity of the resulting polyethersulfone resin solution depends on the molecular weight of the polyethersulfone resin used, but is preferably about 15 to 200 poise.

The filtration of the polyethersulfone resin solution is usually performed using a filter such as a stainless steel or other metal fiber filter or a glass fiber filter. These are not particularly limited, including the model, as long as they are made of a material that is not attacked by the solvent.

[0015] In the present invention, the filtration pressure is 5 kg / c
It is performed at m ² G or less. If it exceeds this, the stability of the filtrate of the polyethersulfone resin solution will be impaired, and it may become cloudy, thicken, or solidify over time. 5 kg of filtration pressure
/ Cm ² G or less can be maintained by adjusting the filtration accuracy of the filter, the filtration area, and the supply amount of the resin solution to the filter. These are determined in consideration of the size and amount of foreign substances present in the resin solution, quality requirements of the film, and filtration time. When the degree of increase in the filtration pressure is large and exceeds 5 kg / cm ² G during the filtration, the amount of the resin solution supplied to the filter is reduced, or the filtration pressure is reduced by switching the filter to another filter. Do.

Another factor affecting the filtration pressure is the viscosity of the resin solution. Although it is possible to lower the filtration pressure by lowering the viscosity of the solution, use of a resin solution having too low a viscosity tends to impair the surface smoothness during film formation. The viscosity of the resin solution is 15 poise or more, preferably 20 poise.
It is desirable to make it more than poise.

The polyethersulfone resin solution obtained by filtration is cast on a support such as a stainless steel belt by a known method, dried, and then separated from the support to form a polyethersulfone resin film. obtain.

[0018]

According to the present invention, the stability of the filtrate of the polyethersulfone resin solution is improved, and it does not cause cloudiness, thickening and solidification over time, and as a result, stable casting becomes possible. A high-quality polyethersulfone resin film can be stably and efficiently manufactured.

[0019]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1 Using the apparatus shown in FIG. 1, dissolution of a polyether sulfone resin solution, filtration, and production of a film were performed. Dissolve the polyether sulfone resin 2 in methylene chloride 3
And dissolve it with stirring. Next, this resin solution is sent to the filter 5 by the pump 4 to perform filtration. Pressure gauge 6
To see the pressure of the filtration. The filtrate is stored in the filtrate tank 7,
The liquid is sent to the casting device by the pump 8. The filtrate is cast from a lip die 9 onto a stainless endless casting belt 11 rotating between drums 10, and hot air (hot air inlet 13, hot air outlet 1).
In step 4), the film is dried, peeled off, and the film is wound around the winding drum 12.

The repeating structural units represented by the above formulas (5) and (6)
Wherein the ratio of repeating structural units 5 is 82.4 mol%, and a N, N-dimethylformamide solution of this resin (1.0 g of resin)
/ 100 ml) at 25 ° C. using an Ostwald-type viscosity tube, and 45 kg of a polyether sulfone resin having a reduced viscosity of 0.38 dl / g was dissolved in methylene chloride 1 in a dissolution tank.
Dissolved in 05 kg.

Next, the resin solution was poured into a 1
The solution was filtered at a rate of 00 liter / h using a stainless steel fiber filter (filtration accuracy: 5 μ, manufactured by Fuji Filter Industry Co., Ltd.). Thereafter the filtration pressure reached 5.0 kg / cm ² G, the filtration pressure is performed while controlling the supply amount of the resin solution to the filter so as not to exceed 5.0 kg / cm ² G, to complete the filtration.

The filtrate of the resin solution was allowed to stand for 24 hours, then cast on a mirror-finished 1 mm-thick stainless belt using a lip die, dried with hot air at 60 ° C. for 30 minutes, and peeled off.
A polyethersulfone resin film having a thickness of 100 μm was obtained. The resulting film was visually transparent without clouding or whitening, and had good surface smoothness. A part of the filtrate was collected in a sample container, sealed, allowed to stand at room temperature, and the state change with time was observed. After one month, no clouding, thickening, and solidification were observed.

Comparative Example 1 Example 1 was repeated except that the filtration was carried out by adjusting the supply amount to the filter at 100 liter / h without adjusting the supply amount.
Filtration was performed in the same manner as described above. The pressure at the end of filtration is 8.3k
g / cm ² G. After leaving the filtrate of the resin solution for 24 hours, it was cast on a mirror-finished 1 mm-thick stainless steel belt using a lip die, dried with hot air at 60 ° C. for 30 minutes, and peeled off to obtain a 100 μm-thick polyethersulfone resin film. Obtained. The obtained film was entirely cloudy and partially whitened and uneven in thickness. A part of the filtrate was collected in a sample container and observed to be turbid when observed. After sealing the sample, the sample was allowed to stand at room temperature to observe a change in state over time. Cloudiness and thickening progressed, and after 3 days, it became jelly-like and lost fluidity.

Example 2 Filtration was performed in the same manner as in Example 1 except that the filtration area of the filter was doubled. In this case, the supply amount to the filter is kept at 100 liter / h, and the filtration pressure at the end is 4.
It increased to 7 kg / cm ² G. After leaving the filtrate of this resin solution for 24 hours, the mirror-finished 1 mm
Cast on a stainless steel belt with hot air at 60 ° C.
After drying for a minute, the film was peeled off to obtain a polyethersulfone resin film having a thickness of 100 μm. The resulting film was visually transparent without clouding or whitening, and had good surface smoothness. A part of the filtrate was collected in a sample container, sealed, and allowed to stand at room temperature to observe a change in state over time. After one month, no clouding, thickening, and solidification were observed.

Comparative Example 2 Filtration was carried out in the same manner as in Example 1 except that a stainless steel fiber filter (manufactured by Fuji Filter Industrial Co., Ltd.) having a filtration accuracy of 3 μm was used. Filtration pressure is 5 kg / cm ²
After exceeding G, it was supplied at 50 liter / h. The pressure at the end of filtration rose to 11.7 kg / cm ² G. After allowing the filtrate of the resin solution to stand overnight, a film-like solid was observed on the surface of the filtrate. When a part of the filtrate was collected in a sample container and observed, it was found that the filtrate was thickened and was becoming jelly-like. The filtrate of this resin solution is mirror-finished using a lip die.
An attempt was made to cast on a stainless steel belt having a thickness of mm, but clogging occurred at the exit of the die, and normal casting could not be performed. In addition, the part of the film that was partially cast did not become a normal film due to severe irregularities on the film surface.

Example 3 Filtration was performed in the same manner as in Comparative Example 2 except that the filtration area of the filter was doubled. The feed rate to the filter was started at 100 l / h, after which the filtration pressure was 5 kg / cm ²
The amount of the resin solution supplied to the filter was adjusted so as not to exceed G. The filtrate of the resin solution was allowed to stand for 24 hours, then cast on a mirror-finished 1 mm thick stainless steel belt using a lip die, dried with hot air at 60 ° C. for 30 minutes, and then peeled off.
A 00 μm polyethersulfone resin film was obtained.
The resulting film was visually transparent without clouding or whitening, and had good surface smoothness. A part of the filtrate was collected in a sample container, sealed, and allowed to stand at room temperature to observe a change in state over time. After a lapse of one month, no cloudiness, thickening and solidification were observed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an apparatus for producing a polyethersulfone resin film used in Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dissolution tank 2 Polyether sulfone resin 3 Methylene chloride 4 Pump 5 Filter 6 Pressure gauge 7 Filtration tank 8 Pump 9 Lip die 10 Drum 11 Endless casting belt 12 Winding drum 13 Hot air inlet 14 Hot air outlet

Claims (3)

[Claims] A polyether sulfone resin solution obtained by dissolving a polyether sulfone resin in methylene chloride is filtered using a filter, cast on a support, dried, and then peeled from the support. A method for producing a sulfone resin film, wherein the filtration of the polyether sulfone resin solution is performed at a filtration pressure of 5 kg / cm ² G or less. 2. The filtration pressure of 5 kg / cm ² G by reducing the supply amount of the polyether sulfone resin solution to the filter.
2. The method according to claim 1, wherein the temperature is held below. 3. The method according to claim 1, wherein the polyethersulfone resin is a polymer having the following repeating structural unit (1) or (2), a copolymer having the same, or a composition containing them. [-Ph-SO ₂ -Ph-O-] [2] [-Ph-SO ₂ -Ph-OAO-] (In the formulas 1 and 2, Ph is paraphenylene.) Group
A represents the following formula (3) or (4). ) (In the formula, n represents an integer of 1 to 4.) (In the formula, B represents an alkylene group having 1 to 3 carbon atoms, an oxygen atom or a sulfur atom, and m represents an integer of 1 to 3.)