JP3046082B2 - Polysulfone resin membrane and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a highly hydrophilic polysulfone resin membrane comprising a cellulose derivative or a blend polymer of cellulose and a polysulfone resin, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, many polymer compounds such as cellulose derivatives such as cellulose acetate, polyacrylonitrile, polymethyl methacrylate and polyamide have been used as materials for artificial membranes. On the other hand, polysulfone resins have been originally used as engineering plastics, but have attracted attention as materials for artificial membranes because of their good heat resistance and solvent resistance. However, polysulfone-based resin membranes are extremely hydrophobic compared to hydrophilic resin membranes such as cellulose, and are "hard to wet once dried".
There are many disadvantages such as "low water permeability" and "the membrane surface is easily contaminated by hydrophobic interaction". Particularly in the pharmaceutical manufacturing process, separation and separation of physiologically active substances such as proteins
When used for purification, etc., the adsorption / denaturation of a physiologically active substance on the membrane surface causes a serious problem because it causes a decrease in the recovery rate and at the same time closes the pores of the membrane and causes a rapid decrease in the filtration rate. I was

In order to solve such a problem, various methods for hydrophilizing a polysulfone-based resin membrane have been proposed. For example, as a method for introducing a hydrophilic group or a hydrophilic polymer into a polysulfone resin, JP-A-53-13679, JP-A-59-196322 and the like, a sulfonic acid group, JP-A-57-196322
In Japanese Patent No. 174104, polyethyleneimine polymers are introduced or grafted into the polymer main chain to make them hydrophilic. In JP-A-62-125802, polyvinylpyrrolidone, a vinyl polymer as a hydrophilic polymer, is blended with a polysulfone resin. However, since both hydrophilic groups and hydrophilic polymers have a slight charge, they are rather counterproductive to solutions containing charged solutes, especially proteins containing ampholytes such as proteins.

[0004] As a polymer having no charge and having excellent hydrophilicity, there is cellulose which is a natural polymer. However, cellulose cannot be blended because cellulose has high hydrophilicity and does not dissolve in a solvent which dissolves a polysulfone resin. Also JP
In Japanese Patent No. 57-50507, a cellulose derivative is blended with a polysulfone-based resin, but there is almost no effect of hydrophilicity as it is, and it is necessary to blend a considerable amount to obtain substantial hydrophilicity. Therefore, it is difficult to obtain a uniform blend with a polymer having a large molecular cohesion such as a polysulfone resin.

[0005]

In any of the methods proposed so far for hydrophilizing a polysulfone-based resin membrane, hydrophilization has not been achieved to a significant extent, or even if hydrophilization has been achieved, charging is not possible. However, this method is not effective for a solution containing a charged solute such as a protein. Accordingly, an object of the present invention is to provide a polysulfone-based resin membrane which has no charge and is highly hydrophilized, and a method for producing the same.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present invention has been achieved. [1] A polysulfone-based resin membrane comprising a blend polymer of a polysulfone-based resin and a cellulose derivative having a degree of hydroxylation of 80% or more and less than 100%.

[2] Polysulfone resin and degree of hydroxylation 10
A polysulfone-based resin membrane comprising a blend polymer with 0% of cellulose. [3] A method for producing a polysulfone-based resin membrane, comprising forming a membrane with a solution in which a polysulfone-based resin and a cellulose derivative are mixed and dissolved, and then hydrolyzing the cellulose derivative to a degree of hydroxylation of 80% or more.

Hereinafter, the present invention will be described in detail. In the membrane of the present invention, the polysulfone resin accounts for 50% of the composition of the membrane.
Or more. The polysulfone resin used in the present invention is usually of the formula (I) or (II)

[0009]

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[0010]

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Although those comprising a repeating unit of the formula (1) are preferred, those containing a functional group or alkyl groups may be used and are not particularly limited. On the other hand, examples of the cellulose derivative used in the present invention include cellulose esters such as acetyl cellulose and cellulose ethers such as cellulose methyl ether. Cellulose esters are preferred because of ease of hydrolysis. The membrane of the present invention is formed into a hollow or flat membrane by a known technique using a solution in which a polysulfone resin and a cellulose derivative are dissolved at a certain mixing ratio, and then the cellulose derivative is hydrolyzed to a degree of hydroxylation of 80% or more. It is obtained by doing. Incidentally degree hydroxide formula cellulosic polymer _{[C 6 H 7 O 2 (OR} ) 3-m (OH) m ] _n m = 0,1,2,3 _n: natural number R: elements other than hydrogen atoms Or when represented by the compound

[0012]

(Equation 1)

The value is expressed by the following formula, and can be determined by quantifying the hydrolyzate. The organic solvent used for the stock solution is not particularly limited as long as it dissolves the polysulfone resin and the cellulose derivative.Examples of such a solvent include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and dimethylacetamide. Sulfoxide and the like.

[0014] The concentration of the polysulfone resin in the membrane-forming stock solution may be in the range of being capable of forming a membrane and having performance as a membrane, and is 10 to 50% by weight. Further, in order to obtain high water permeability and a large molecular weight cut-off, the polymer concentration should be lowered, and in this case, it is desirably 10 to 20% by weight. The concentration of the cellulose derivative may be within a range where sufficient hydrophilicity can be obtained after hydrolysis, and the degree of hydrophilization can be freely adjusted by adjusting the hydrolysis rate, but preferably 1 to 15% by weight. It is also possible to add a fourth component for the purpose of controlling the viscosity of the stock solution and the state of phase separation, which may be optionally performed depending on the required water permeability and molecular weight cut off.

A film is formed by a known technique using the stock solution prepared under the above conditions. In the case of a flat membrane, the stock solution is spread on a flat substrate and then immersed in a coagulation bath. For the hollow fiber membrane, an injection liquid is used to maintain the hollow form. The best composition of the injection solution may be appropriately determined according to the required water permeability and the molecular weight cut off, or a gas may be injected. Similarly, the coagulant in the coagulation bath is not particularly limited as long as the best composition is appropriately determined depending on the required membrane performance in both the flat membrane and the hollow fiber membrane. In the case of a hollow fiber membrane, the distance from the spinneret to the coagulation bath is 0 cm or more and 150 c.
m, and more preferably 0 cm or more and 30 cm or less from the viewpoint of spinning stability.

The flat membrane or hollow fiber membrane produced as described above has almost no hydrophilic effect as it is,
A significant hydrophilicity can be achieved only by hydrolyzing the cellulose derivative to a degree of hydroxylation of 80% or more by the method described below. After the solvent is sufficiently removed from the flat membrane or the hollow fiber membrane by a water washing treatment, the membrane is immersed in a hydrolysis treatment solution. The hydrolysis treatment solution may be any one as long as the ester bond portion of the cellulose derivative is replaced with a hydroxyl group by hydrolysis at the ether bond portion, and an acidic or alkaline solution for cellulose esters,
Cellulose ethers are acidic solutions. Needless to say, the degree of hydroxylation can be freely adjusted depending on the concentration, the processing time, and the processing temperature.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0018]

[Example 1] Dimethylacetamide (hereinafter abbreviated as DMAC)
An acetylation degree of 55 was added to a mixed solvent of 77.5 g and 2.5 g of water.
5 g of cellulose acetate (Wako Pure Chemical) at room temperature
Aromatic polysulfone resin represented by the formula (I) (AMOCO P
-3500: hereinafter abbreviated as PS) 15 g, further dissolved at 60 ° C. for 5 hours, and subjected to vacuum degassing to obtain a membrane forming stock solution. After spreading on a glass plate while keeping the temperature at 40 ° C. using a baker type applicator according to an ordinary method, the mixture was coagulated in a water bath at 60 ° C., and then the solvent was sufficiently removed by washing with water to obtain a flat membrane. 5
It was immersed in a 1% NaOH 0% ethanol aqueous solution at 0 ° C. for 7 hours to carry out a hydrolysis treatment. Table 1 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation was determined by quantification of the hydrolyzate. The protein adsorption was measured by the following method.

The radioisotope-labeled protein was adjusted to 0.01 mg / ml in a phosphate buffer (pH = 7.0,
The test solution was dissolved at an ionic strength of 0.15). 1 × 10 ^-3 m ² /
After a test film having a constant membrane area was immersed in a test solution of a constant mass at 38 ° C. for 1 hour at a ratio of 100 g, the test film was washed in water for 15 hours to sufficiently wash off non-adsorbed proteins.
Thereafter, the amount of the adsorbed protein was directly quantified using a Geiger counter.

[0020]

Example 2 A flat film was obtained in the same manner as in Example 1.
This flat membrane is placed in a 50% ethanol 1N NaOH 50% ethanol solution.
It was immersed for 15 hours to perform a hydrolysis treatment. Table 1 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0021]

Comparative Example 1 A flat film was obtained in the same manner as in Example 1. However, no hydrolysis treatment was performed. Table 1 shows the degree of hydroxylation, water permeability, molecular weight cut-off, and the amount of various proteins adsorbed.
The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0022]

Comparative Example 2 A flat film was obtained in the same manner as in Example 1.
The flat membrane was immersed in a 50% ethanol 1% NaOH 50% ethanol solution for 4 hours to perform a hydrolysis treatment. Table 1 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0023]

Example 3 The same membrane-forming stock solution as in Example 1 was used as the injection solution for DMAC.
Using water / water = 1/1, discharge from a spout consisting of an annular orifice having an inner diameter of 0.64 mm and an outer diameter of 1.04 mm,
The solution was passed through a water bath at 60 ° C., which was placed at a height of 1 cm, washed with water by a usual method, and wound around a scalpel to obtain a hollow fiber membrane. This hollow fiber membrane was immersed in a 50% ethanol 1% NaOH 50% aqueous ethanol solution for 4 hours to carry out a hydrolysis treatment. Table 2 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0024]

Example 4 A hollow fiber membrane was obtained in the same manner as in Example 3. This hollow fiber membrane was immersed in a 50% ethanol 1% NaOH 50% ethanol solution for 10 hours to perform a hydrolysis treatment. Table 2 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0025]

Comparative Example 3 A hollow fiber membrane was obtained in the same manner as in Example 3. However, no hydrolysis treatment was performed. Table 2 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0026]

Comparative Example 4 A hollow fiber membrane was obtained in the same manner as in Example 3. This hollow fiber membrane was immersed in a 50% ethanol 1% NaOH 50% ethanol solution for 2 hours to carry out a hydrolysis treatment. Table 2 shows the hydrolysis time, the degree of hydroxylation, the water permeability, and the adsorption amounts of various proteins. The degree of hydroxylation and the amount of protein adsorption were measured in the same manner as in Example 1.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

The polysulfone resin membrane of the present invention comprising a blend polymer of a polysulfone resin and a cellulose derivative or cellulose has excellent hydrophilicity and biocompatibility of cellulose which is a natural polymer, and excellent heat resistance of polysulfone. It is a completely new film that has both chemical resistance. In particular, this membrane is excellent in biocompatibility and protein non-adsorptive properties.
It has sufficient performance for use in general industrial fields such as food production.

Claims (3)

(57) [Claims] 1. A polysulfone-based resin membrane comprising a blend polymer of a polysulfone-based resin and a cellulose derivative having a degree of hydroxylation of 80% or more and less than 100%. 2. A polysulfone resin membrane comprising a blend polymer of a polysulfone resin and cellulose having a degree of hydroxylation of 100%. 3. A method for producing a polysulfone-based resin membrane, comprising forming a membrane with a solution in which a polysulfone-based resin and a cellulose derivative are mixed and dissolved, and then hydrolyzing the cellulose derivative to a degree of hydroxylation of 80% or more.