JPS5824305A - Production of semipermeable membrane of polysulfone resin - Google Patents

Abstract

PURPOSE:To obtain a semipermeable membrane of superior filtration characteristics with good reproducibility by controlling the state in which membrane materials are gelled and solidified by the effect of a solidifying bath from a casting soln. using a high b.p. solvent in such a way that said state enters a specific range. CONSTITUTION:The aliphat. org. acids expressed by the formulaI(where R<1> is hydrogen or a carobxylic group in the case of n=0, hydrogen, methyl group, etc., in the case of n>=1, R<2> is hydrogen, hydroxyl group, etc., R<3> is hydrogen, methyl group, etc.) or their ester or a material expressed by the formula II (where R4-R8 are hydrogen, hydroxyl groups, etc., R9 is carboxylic group, etc. The third group is carboxylic acid amide, alkyl phosphate, etc.) are used as the material which alone does not dissolve polysulfone resin. The concn. of the polysulfone resin in the casting soln. is 5-40wt%, and the thickness is 50- 1,000mu. A glass plate, a metallic plate, etc. are used for the base plate for casting.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a semipermeable membrane made of polysulfone resin,
The present invention relates to a method for producing a membrane that has excellent performance in both r-permeability and water permeation rate.

Specifically, the film is formed through a casting and gelation process using a mixed solvent containing N-methylpyrrolidone as the main solvent and an appropriate amount of a substance that does not dissolve the polysulfone resin alone as a casting solvent. The present invention relates to a method for producing a polysulfone semipermeable membrane.

Polysulfone resin has great strength, heat resistance, acid resistance, alkali resistance, microbial resistance, etc., and is an excellent polymer as a material for semipermeable membranes, but depending on the usual casting method,
It is not possible to obtain a membrane with good irradiation performance. When a film is formed by the casting-gelling method, even though the internal structure of the film becomes porous during the gelling-removal process, the □film on the side that is in contact with the base surface during casting on the polysulfone resin. There is a tendency to form a dense inert surface layer on the surface, making it difficult to obtain a membrane with a high water permeation rate.

Therefore, in order to obtain a semipermeable membrane from polysulfone resin, two
Three special methods have been proposed. For example, there is a method in which a casting base is specially processed and then cast.
8581, as shown in Japanese Patent Application Laid-Open No. 54-57475,
These can only be applied to composite membranes with nine supports using such casting bases as they are. Furthermore, a method of increasing permeability by increasing the wettability of a polysulfone resin membrane with water is shown in JP-A-54-16378, but the aqueous electrolyte solution used for this purpose is an unstable casting solution. However, it is not a practical method because the relationship between the casting solution and the water wettability of the membrane is difficult to predict.

In the so-called wet film forming method that uses the process of casting and immersion in a coagulation bath, a volatile good solvent evaporates from the surface in a short period of time from immediately after casting to immersion in a coagulation bath, and a concentration gradient is created within the casting solution layer. This formation plays an important role in semipermeable membrane formation. On the other hand, good solvents for polysulfone resin are limited to solvents with a relatively high boiling point, and there is almost no concentration gradient in the casting solution layer before immersion in the coagulation bath, and the method of coagulation is the most important. It was acknowledged that the performance of the membrane is determined.

That is, the present invention provides a semi-permeable material with excellent r-permeability by adjusting the conditions such that the gelation and coagulation of the membrane material from a casting solution using a high boiling point solvent falls within a specific range by the action of a coagulation bath. This is a method to obtain membranes with good reproducibility. The properties of such a casting solution are expressed by the "coagulation value" defined below. In this case, water is used as the coagulation bath, and the solvent is selected from those that dissolve the polysulfone resin and are also compatible with water.

The "coagulation value" in the present invention is defined as follows. [
A polymer solution prepared by dissolving 2 g of polysulfone resin in 98 g of casting solvent was maintained at 30 i:1'C, and water was gradually added while stirring, and the amount of water added until the solution became cloudy was measured in g. Therefore, if the membrane is formed using a casting solvent such that the coagulation value falls within a specific range, a semipermeable membrane with good performance can be obtained. Of course, this "coagulation value" is a practical measure, and its appropriate range varies somewhat depending on the membrane material used as the main solvent and solute. When using N-methyl bilidone as the main solvent, when the polysulfone resin is a polymer consisting of repeating units represented by
Appropriate "coagulation value" is 7g or less, 2g or more, preferably 6
g or less and 3I or more. In addition, when the polysulfone resin is a polymer consisting of units represented by , the "coagulation value" is 12. ! 7 or less 1.5. j9 or more, preferably 11.9 or less and 2g or more is appropriate.

N-methylpyrrolidone used as the main solvent is compatible with water and is a good solvent for polysulfone resin. The "substances that do not dissolve polysulfone resin by themselves" used in the implementation are compatible with N-methylpyrrolidone, which is the main solvent, and can be roughly divided into three groups. Contains substances such as

The first group is represented by the following general formula.

z However, when n = Q, R1 is hydrogen or a carboxyl group, and when n≧1, hydrogen, methyl group, ethyl group, hydroxyl group, or carboxyl group, R is hydrogen, hydroxyl group, or carboxyl group, R3 is Hydrogen, methyl group or ethyl group.

Examples include aliphatic organic acids such as formic acid, acetic acid, pionic acid, methyl formate, ethyl formate, methyl acetate, ethyl acetate, lactic acid, and ethyl lactate, or esters thereof.

The second group is represented by the following general formula.

However, R4 to R8 are each independently hydrogen, a hydroxyl group, a carboxyl group, or a methoxyl group, and R9 is a carboxyl group or a sulfoxyl group.

For example, benzoic acid, salicylic acid, benzenesulfonic acid,
These include terephthalic acid and trimellitic acid.

The third group includes compounds belonging to carboxylic acid amides, phosphoric acid alkyl esters, etc., such as N-methylformamide, N-methylacetamide, trimethyl phosphate, and trimethyl phosphate. Only one type of these "substances that do not dissolve the polysulfone resin when used alone" may be used, but two or more types can also be used at the same time. In the mixed solvent thus prepared, it is necessary to use at least 20% by weight of N-methylpyrrolidone, which is the main solvent.

In the casting solution, the concentration of polysulfone resin is 5% by weight
A suitable amount is 40% by weight or less, and desirably 10% by weight or more and 30% by weight or less, thereby making it possible to obtain a dope suitable for casting.

The appropriate casting thickness of this casting solution is 50μ or more, 1000μ
μ or less, practically preferably from 100 μm to 500 μm.

The casting base can be any material that allows the upper surface of the cast solution to form a uniform plane, such as glass plates, metal plates, plastic sheets that are not affected by solvents, woven fabrics, non-woven fabrics, ceramics, etc. A porous plate or the like can be used.

The membrane produced by the method of the present invention can be obtained by peeling from a casting base, or can be obtained as a membrane with a support using a porous substrate as a support.

The present invention will be explained below with reference to Examples.

Example 1 Polysulfone resin (Vict
rex 300p (manufactured by ICI) was dissolved in a mixed solution of 63 parts of N-methylpyrrolidone and 20 parts of acetic acid,
A homogeneous polymer solution was obtained by standing to defoam.

This solution was cast using a doctor blade with a gap of 180 μm on a horizontally placed smooth glass plate as a base of 4 cb. After being left at room temperature for 30 seconds, the base was immersed in water at 17°C to gel the polymer. It was made into a film. The produced film was peeled off from the substrate and collected, and the film performance was measured.

Membrane performance was measured as follows. That is, using a circulating flat membrane ultrafiltration device (effective membrane area 25 d), the feed liquid temperature was 25 d.
°C, supply liquid amount 125 m1/min, pressurization o, s kg/
The water permeation rate was measured using distilled water as a feed liquid under conditions of Cl. Also, an aqueous ovalbumin solution (
The liquid permeation rate and solute permeation rate were measured using a 1/15M phosphate buffer solution (p) (dissolved at a concentration of 2000 ppm in 7.0) of reagent albumin manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.

As a result, the water permeation rate was 4.6713/min・fni! , liquid permeation rate of ovalbumin solution 71OrILl! /min・m2
It was found that the solute permeability was 0% and that it had excellent filtration performance.

Note that the solvent used in this example (N-methylpyrrolidone 63
The measured value on the coagulation side of /acetic acid 20) for the polysulfone resin was s, 4 (jy).

Examples 2 to 5 and Comparative Examples 1 to 6 Films were formed in the same manner using 17 parts of the same polysulfone resin used in Example 1 and 83 parts of various solvents, and the film performance was measured. The solvent composition, coagulation value, and membrane performance are shown in Table 1, including the results of Example-1.

However, in the table, γ-BL stands for γ-butyrolactone, DMSO stands for dimethyl sulfoxide, and DMF stands for N,N-dimethylformamide.

Polysulfone resin (Udel p170) consisting of repeating units shown in Examples 5 to 14 and Comparative Examples 7 to 14
A polymer solution was obtained by dissolving 17 parts of N-methylpyrrolidone (manufactured by UCC) in 83 parts of a solvent containing N-methylpyrrolidone as a component, and a film was formed in the same manner as in Example 1, and the film performance was evaluated. It was measured. The solvent composition, coagulation value, and membrane performance are shown in Table 2.

Example-14 Polysulfone resin (Victrex
Instead of a polymer solution obtained by dissolving 17 parts of 300p (manufactured by ICI) in a mixed solution of 63 parts of N-methylpyrrolidone and 20 parts of acetic acid, 14 parts of the same polysulfone resin was dissolved in 71 parts of N-methylpyrrolidone and propionic acid. A film was formed in the same manner except that a polymer solution obtained by dissolving in 15 parts of a mixed solution was used, and the film performance was measured using an aqueous Alpine solution. As a result, the liquid permeation rate was 880 (rIll/min・
ff12), and the solute permeability was 0.32%.

The coagulation value of the mixed solvent used in this example was 10.70.
(g).

Examples 15 and 16 In Example 2, the casting base surface was replaced with a glass plate,
Polyester non-woven fabric (HF180, manufactured by Nippon Vilene Co., Ltd.) and polyester woven fabric (taffeta≠230, manufactured by Toshi Co., Ltd.)
Table 3 shows the results of measuring the membrane performance of a composite membrane obtained using an aqueous albumin solution prepared using a membrane with a support in the same manner as in Example 2, except that each of these membranes was used. -17° A film was formed in the same manner as in Example 4, except that a doctor blade with a gap of 250 μm was used instead of a doctor blade with a gap of 180 μm, and the film performance was measured. As a result, the distilled water permeation rate was 7.48 (,g/Tr
When a 0 ovalbumin solution with Bm21cg/aft) was used as the feed liquid, the liquid permeation rate was 640 (7!/min m2), and the solute permeation rate was 0.
It was 06 (%).

Examples 18 and 19 In Example 6, a polyester nonwoven fabric (MF180 manufactured by Nippon Vilene Co., Ltd.) and a polyester woven fabric (Taffeta+230 manufactured by Toshi Co., Ltd.) were used instead of glass for the casting base surface, and a gap of 150 μ was used. A film was formed in the same manner except that a doctor blade with a gap of 250 μm was used instead of a doctor blade with a gap of 250 μm. The membrane performance of the resulting composite membrane with the nonwoven fabric and woven fabric was measured using an albumin aqueous solution.

The membrane performance is shown in Table 4 ○Table 4 Example-20 In Example-6, polysulfone resin (Udel P
A film was formed in the same manner, except that 1.4 parts of the same polysulfone resin was used instead of 1700 U (manufactured by CC).
Membrane performance was measured using an albumin aqueous solution. As a result, the liquid permeation rate was 830 (-7 min.m2) and the solute permeation rate was 833%.

Patent Applicant: Daicel Chemical Industries, Ltd. Procedural Amendment (Voluntary) Commissioner of the Patent Office Kazuo Wakasugi 1 Case Description 1982 Patent Application No. 12121 Part 6 2 Title of Invention Method for Manufacturing Polysulfone Resin Semipermeable Membrane 3 Relationship to the case of the person making the amendment Patent applicant address 1-4 Teppocho, Sakai City, Osaka Date of amendment order Date of amendment 5 No number of inventions increased by amendment 6 ``Inventory of attached documents'' of the application subject to amendment column and “Detailed Description of the Invention” column 7 of the specification Contents of the amendment (1) In the “List of Attached Documents” column of the application [(1) Description 1 copy (2) Drawings 1 copy (3 ) 1 copy of the application" shall be changed to ``(1) 1 copy of the specification (2) 1 copy of the application."

(2) "Trimethyl phosphate, trimethyl phosphate" on page 9, line 8 from the bottom of the specification is changed to "trimethyl phosphate, triethyl phosphate."

(3) 4th line from the bottom of page 17 of the specification Let rHFtsoJ be “MF180”.

that's all

Claims (5)

[Claims] (1) In a semipermeable membrane manufacturing method that consists of casting a solution of polysulfone resin dissolved in a solvent onto a horizontal substrate and immersing it in a gelling bath, N-methylpyrrolidone and polysulfone alone are used as the casting solvent. Method 0 for producing a polysulfone resin semipermeable membrane characterized by using a mixed solvent with a substance that does not dissolve the resin (2) The substance used in the casting solvent, which does not dissolve the polysulfone resin by itself, has the general formula % (where R1 is hydrogen or a carboxyl group when n = Q, and hydrogen or a carboxyl group when R≧1). , a methyl group, an ethyl group, a hydroxyl group, or a carboxyl group, R2 is hydrogen, a hydroxyl group, or a carboxyl group, and R3 is hydrogen, a methyl group, or an ethyl group, or an ester thereof. A method for producing a polysulfone semipermeable membrane according to item 1. (3) The substance used in the casting solvent, which does not dissolve the polysulfone resin by itself, has the general formula The method for producing a polysulfone semipermeable membrane according to claim 1, wherein the polysulfone semipermeable membrane is an aromatic organic acid represented by the following group. (4) The substances used in the casting solvent that do not dissolve polysulfone resin by themselves are N-methylformamide, N-
The method for producing a polysulfone semipermeable membrane according to claim 1, characterized in that methylacetamide, trimethyl phosphate, or triethyl phosphate is used. (5) A solvent composition in which the polysulfone resin is a polymer consisting of repeating units represented by 0 and whose coagulation value is 1.5 g or more and 12.9 or less is used as the casting solvent, and a water bath is used as a gelling bath. Claims 1 or 2 characterized in that
0 (6) The method for producing a polysulfone semipermeable membrane according to item 0 or 3 or 4. The polysulfone resin is a polymer consisting of repeating units represented by, and the coagulation value for the polymer is 2 g or more and 7 g or less. A method for producing a polysulfo/semipermeable membrane according to claim 1, 2, 3, or 4, characterized in that a solvent composition is used as a casting solvent and a water bath is used as a gelling bath.