JPS6148963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aromatic polysulfone semipermeable membrane with excellent permeability and high water permeation rate.

Conventionally, various materials have been proposed for use in semipermeable membranes, and among them, cellulose acetate is well-known as a membrane material with excellent permeability. However, semipermeable membranes made of cellulose acetate have some drawbacks in physical and chemical performance.
Depending on the application, it may not necessarily be suitable. In particular, when used as a semipermeable membrane for blood processing in a dialysis type or hypertype artificial kidney, cellulose acetate semipermeable membranes cannot be sterilized by steam.
Because they must be sterilized using chemicals, they must be thoroughly washed before being used on patients. Additionally, membranes generally must be stored in a wet state, making them inconvenient to handle.

In contrast, semipermeable membranes made of aromatic polysulfone
It can be used for steam sterilization and has high resistance to various chemicals. Furthermore, since a membrane that can be stored in a dry state can be produced, it has great applicability to medical equipment including blood processing.

To produce a semipermeable membrane from a polymeric substance, it is dissolved in a good solvent, cast onto a non-stick substrate (e.g. glass plate) or support (e.g. nonwoven fabric), and a portion of the solvent is evaporated. Generally used is a method in which the membrane is then immersed in a coagulation bath and recovered as a single membrane released from the substrate or as a membrane bonded to a support.

Although polysulfone has excellent physical and chemical properties, it has not been widely used as a semipermeable membrane until now because the intermolecular cohesive force of polysulfone is too large, making casting and solidification difficult. This is because it is difficult to form micropores with appropriate size and uniformity in a stepwise manner. Therefore, as a means of controlling pore formation, a method is used in which a non-solvent, non-volatile salts, etc. are mixed in the casting solution in addition to a good solvent. For example, as a non-solvent, alcohols were used in JP-A-51-42765, polyethylene glycol was used in JP-A-54-26283, and salts were used in JP-A-54-26283.
54-16378 shows the use of sodium acetate, and Japanese Patent Publication No. 52-29712 shows the use of zinc chloride. However, when casting polysulfone membranes, if the amount of these non-solvents and salts is too small, a membrane with poor permeability will be obtained, and if the amount is too large, physical properties such as strength and uniformity will deteriorate. This method tends to yield films with poor quality, and provides a method with poor reproducibility even within reasonable ranges.

In contrast, the present inventors used aprotic polar solvents that are good solvents for aromatic polysulfones, such as N.N.-dimethylformamide, N.N.-dimethylacetamide, and N-methylpyrrolidone, as the main solvent, and used We have found that a method using a solvent mixed with dimethyl sulfoxide, which is a swelling agent, as a casting solvent is a method for producing membranes with good performance with good reproducibility.

The aromatic polysulfone targeted by the present invention is It is a linear polymer consisting of repeating units represented by, and does not have a dissociable group such as a sulfonic acid group in the side chain. Although dimethyl sulfoxide exhibits solubility in certain aromatic polysulfones, it does not have the ability to dissolve the polymer targeted by the present invention and acts as a swelling agent. The present invention will be explained below with reference to Examples.

Example 1 17 parts of polysulfone resin (manufactured by UCC, trade name: UdelP1700) consisting of repeating units shown in
The mixture was dissolved in a mixed solution consisting of 68 parts of N-dimethylformamide and 15 parts of dimethyl sulfoxide, and defoamed by standing at room temperature for 24 hours to obtain a homogeneous solution. This solution was cast onto a horizontally placed glass plate with a smooth surface at a speed of 4 cm/sec using a doctor blade with a gap of 150 μm.
After being left in a room at 60% RH for 30 seconds, it was immersed in water together with the glass plate. The polysulfone on the glass plate turned into a gel and was peeled off naturally from the glass plate in the form of a film, which was collected. For this membrane, a circulating flat membrane ultrafiltration device (effective membrane area 25 cm ² ) was used.
Supply liquid temperature 25℃, supply liquid volume 125ml/min, pressure 0.5
Overperformance was measured under the condition of Kg/cm ² .

The water permeation rate when using pure water as the feed liquid is
It was 1260ml/(min・m ²・(Kg/cm ² ). Also,
Ovalbumin aqueous solution (Wako Pure Chemical Industries, Ltd.) Ovalbumin was added to a 1/15-M phosphate buffer solution (PH
7.0) dissolved at a concentration of 2000ppm) as the feed liquid, the water permeation rate is 950ml/
(min・m ²・(Kg/cm ² ), solute permeation rate was 62%.Albumin concentration in the feed solution and permeate was at the peak corresponding to the molecular weight of 45,000 in gel permeation clostogray. It was calculated from the area.Also, blue dextran (average molecular weight 200
1,000, manufactured by Pharmacia Huain Chemicals Co., Ltd.)
When an aqueous solution containing 1000 ppm was used as the feed liquid, the water permeation rate was 200 ml/(min·m ² ·(Kg/cm ² )) and the solute permeation rate was 0%. The blue dextran concentrations in the feed liquid and permeate liquid were determined by ultraviolet absorption spectroscopy (absorption wavelength = 260 nm).

Comparative Example 1 A polysulfone membrane was prepared using the same method as in Example 1, except that 83 parts of N·N-dimethylformamide alone was used as the casting solvent, and its performance was measured. The permeation rate of pure water is 260ml/(min・^m2・
(Kg/cm ² )), and the value is about 1/1 of that of the membrane of Example 1.
It was 5.

Example 2 17 parts of the same polysulfone resin (UdelP1700) used in Example 1 was dissolved in a mixed solution consisting of 68 parts of N.N-dimethylacetamide and 15 parts of dimethyl sulfoxide. The above polysulfone solution was cast onto a polyester fiber nonwoven fabric (MF-180, manufactured by Nippon Vilene Co., Ltd.) using a doctor blade having a gap of 250 μm. Thereafter, a film was formed according to the method of Example 1 to obtain a polysulfone membrane with a support using a polyester nonwoven fabric as a support. The membrane performance of this membrane was measured in the same manner as in Example 1. The permeation rate of pure water is 7960ml/(min・^m2・
(Kg/cm ² )). In addition, the water permeation rate when ovalbumin aqueous solution (concentration 2000 ppm) is used as the feed liquid is 1540 ml/(min・m ²・(Kg/cm ² )), solute permeation rate
It was 4.14%.

Example 3 17 parts of the same polysulfone resin (UdelP1700) used in Example 1 was mixed with 68 parts of N-methylpyrrolidone.
and 15 parts of dimethyl sulfoxide.

The above polyester solution was cast onto a polyester fabric (Taffeta #230 manufactured by Toray Industries, Inc.) using a doctor blade having a gap of 250 μm.
Thereafter, a film was formed according to the method of Example 1 to obtain a polyester film with a support using a polyester fabric as a support. The membrane performance of this membrane was measured in the same manner as in Example 1. The water permeation rate of pure water is 4650ml/(min.
^m2・(Kg/ ^cm2 )). Furthermore, when an aqueous ovalbumin solution (concentration 2000 ppm) was used as the feed liquid, the water permeation rate was 1250 ml/(min·m ² ·(Kg/cm ² )), and the solute permeation rate was 0.34%.

Claims (1)

[Claims] 1. A method for producing a semipermeable membrane made of aromatic polysulfone having no dissociable side chains, comprising 95 to 40% by weight of N·N-dimethylformamide or N-methylpyrrolidone as a casting solvent; A method for producing a semipermeable membrane, characterized in that a mixture with 5 to 60% by weight of dimethyl sulfoxide is used and water is used as a coagulation bath. 2 Aromatic polysulfone A method for producing a semipermeable membrane according to claim 1, which is a polymer represented by repeating units of.