JP3134465B2 - Manufacturing method of porous polysulfone hollow fiber membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a porous polysulfone hollow fiber membrane. More specifically, the present invention relates to a method for producing a porous polysulfone hollow fiber membrane which has excellent flow characteristics and can be effectively used as an ultrafiltration membrane or the like.

[0002]

2. Description of the Related Art Wet spinning of a polysulfone spinning stock solution using a liquid having coagulability with respect to this spinning stock solution as a core solution,
When producing a porous polysulfone hollow fiber membrane, factors that govern the pore diameter of the hollow fiber membrane and the like include a spinning solution,
Waterfall conditions such as the composition of the core liquid and the coagulation bath, the idle running distance from the nozzle discharge section to the coagulation bath surface, and the atmosphere between them are given. Among these factors, the operation factors other than the composition of the coagulation bath are easy-to-handle operation factors. On the other hand, when using anything other than water as the coagulation bath, the amount of liquid used is relatively large. Often difficult.

However, merely controlling factors other than the composition of the coagulation bath limits the range in which the membrane structure of the obtained hollow fiber membrane, particularly the structure of the outer surface portion, can be controlled. Etc. must be used as a coagulation bath. Therefore, a method of attaching a cylindrical case below the nozzle in the coagulation bath and adjusting the concentration of only the inside of the cylindrical case as a thickener aqueous solution has been previously proposed by the present applicant.
(JP-A-1-192,811).

In this method, an aqueous solution of a thickener such as an aqueous glycerin solution is continuously supplied to the inner peripheral surface side of the cylindrical case, and a coagulation bath to which the hollow fiber membrane comes into contact initially has a certain concentration or more. It is a method of using an aqueous solution. However, the problem with this method is that it is difficult to keep the concentration of the aqueous solution in the case at an extremely high concentration because it is in direct contact with the original coagulation bath water below the cylindrical case. Furthermore, it is not intended at all to eliminate moisture in that part.

[0005] In addition, a method of coagulating to a certain extent using a lower alcohol coagulation bath and then completely coagulating in a separately provided water coagulation bath without regard to the amount of liquid used,
In this process, the hollow fiber membrane that has not been completely coagulated needs to be supported in the air by several rolls, and there is a risk that the hollow fiber membrane will be crushed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a porous polysulfone hollow fiber membrane which is excellent in flow characteristics when producing a porous polysulfone hollow fiber membrane by a wet spinning method in which a discharge liquid of a polysulfone spinning stock solution is coagulated in lower alcohol and then through water. Another object of the present invention is to provide a material which can be effectively used as an ultrafiltration membrane or the like.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In performing wet spinning of the polysulfone spinning stock solution using a liquid having coagulability with respect to the spinning stock solution as a core solution, the liquid discharged from the double annular nozzle is passed through lower alcohol, and then layered in an immiscible state with the lower alcohol. This is achieved by producing a porous polysulfone hollow fiber membrane by passing through solidified water and coagulating.

[0008] The polysulfone spinning solution is prepared by adding about 0.5 to 15% by weight of a thickener such as polyvinylpyrrolidone or polyethylene glycol to a solution of about 10 to 30% by weight of a water-miscible organic solvent such as dimethylformamide or dimethylacetamide. It is prepared by In the wet spinning, a liquid having coagulability with respect to a spinning dope such as water or lower alcohol is used as a core liquid.

[0009] The spinning stock solution discharged together with the core solution from the double annular nozzle is obtained by subjecting the discharged solution to a lower alcohol having a depth of about 20 to 200 mm, preferably about 50 to 100 mm, by a wet spinning method with an idling distance of 0. Preferably, after passing through ethanol, it is passed through water layered immiscible with the lower alcohol and solidified. Since the lower alcohol and water have good miscibility with each other, a diaphragm liquid layer is interposed between them. This diaphragm liquid layer is formed of liquid paraffin (specific gravity 0.87 to 0.89) of about 5 to 50 mm, silicone oil or the like.

[0010] Specifically, a cylindrical case is attached to a water coagulation bath, and liquid paraffin and lower alcohol are poured into the cylindrical case in this order, and the lower alcohol formed therewith a liquid paraffin layer is interposed. Spinning is performed by passing a spinning stock solution discharged in the form of a hollow fiber membrane through the aqueous overlay solution.

[0011]

According to the method of the present invention, the pore size of the outer surface structure is large, the flow rate characteristics are excellent, and the porous material can be effectively used as an ultrafiltration membrane without a large-scale modification of the coagulation bath apparatus. A porous polysulfone hollow fiber membrane is obtained. The properties also differ depending on the type of core liquid used, and compared with the case where only water is used as the coagulation bath, when the water core liquid is used, even if the pore diameter (fraction molecular weight) is the same. The flow characteristics are remarkably improved. When the ethanol core liquid is used, the flow characteristics are further improved, and an improvement in the pore diameter (fraction molecular weight) is also observed. Accordingly, a hollow fiber membrane for ultrafiltration having a wider range of characteristics can be obtained.

[0012]

Next, the present invention will be described with reference to examples.

COMPARATIVE EXAMPLES 1-2 A spinning dope comprising 15% by weight of polysulfone, 1% by weight of polyvinylpyrrolidone and 84% by weight of dimethylformamide was prepared by discharging a core liquid having a diameter of 0.5 mm, a spinning liquid discharging section having an inner diameter of 1.0 mm and an outer diameter of 2.0 mm. Discharge from the double annular nozzle together with the water core liquid,
Wet spinning with a run distance of 0 mm (Comparative Example 1) or dry / wet spinning with a run length of 100 mm (Comparative Example 2) was performed. Water is used as the coagulation bath, and the spinning speed is 10 m / min for each.

Comparative Examples 3 and 4 In Comparative Examples 1 and 2, ethanol was used instead of water as the core liquid.

With respect to the polysulfone hollow fiber membrane obtained in each of the above comparative examples, the inner and outer surface structures were observed by an electron microscope, and pure water permeation flux {unit: cm ³ / cm ² · (kg / cm ² ) · hr} and the molecular weight cut off with polyethylene glycol. The results are shown in Table 1 below. In addition, the molecular weight cut off was 6000 in all cases, and in Comparative Example 4 , spinning could not be performed because the dope was out. Table 1 Comparative example Inner surface structure Outer surface structure Pure water permeation flux 1 Dense Dense 0.5 2 孔 Holes with a pore diameter of about 1 μm are scattered 2 3 Large porosity Dense 〃

Examples 1-2 Using the spinning dope of each comparative example and the double annular nozzle,
Using the core liquid as water (Example 1) or ethanol (Example 2), wet spinning with an idle distance of 0 mm (spinning speed 10 m / min) was performed. At this time, a pipe with an inner diameter of 80 mm was attached to the water coagulation bath, and liquid paraffin (10 mm deep) and ethanol
(Depth 100 mm) in this order, and the discharged liquid was allowed to pass through the layered liquid formed therein and solidified. The polysulfone hollow fiber obtained in each of these examples has properties as shown in Table 2 below. Table 2 Example Inner surface structure Outer surface structure Pure water permeation flux Fractional molecular weight 1 Dense Large porosity 5 6000 2 Large porosity 〃 30 50000

Claims (2)

(57) [Claims] When wet spinning a polysulfone spinning stock solution using a liquid having coagulability with respect to the spinning stock solution as a core solution, a liquid discharged from a double annular nozzle is passed through lower alcohol and then mixed with the lower alcohol. A method for producing a porous polysulfone hollow fiber membrane, comprising passing through non-miscible layered water and solidifying. 2. A cylindrical case is attached to a water coagulation bath, and liquid paraffin and lower alcohol are poured into the cylindrical case in this order, and the discharged liquid is passed through the layered liquid formed therein. Item 4. The method for producing a porous polysulfone hollow fiber membrane according to Item 1.