JP4760017B2 - Method for producing hollow fiber membrane and method for producing hollow fiber membrane module - Google Patents

Description

  The present invention relates to a hollow fiber membrane and a method for producing a hollow fiber membrane module. More specifically, a hollow fiber membrane having excellent spinnability, in which a hollow portion forming fluid (injection solution) is injected into a central inner tube using a double tube die and a hollow fiber is spun by a wet method or a dry wet method. The present invention relates to a method for producing a hollow fiber membrane module.

  In recent years, hollow fibers made of polymers have been developed and used for various purposes and applications. In particular, hollow fiber polymer separation membranes include various types of membranes such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, gas separation membranes, nitrogen-rich membranes, oxygen-rich membranes, blood purification membranes, and artificial lungs. It has been put to practical use in applications and has recently been used in water purification processes and various water treatment fields. These hollow fiber membranes are generally produced by a spinning method called a wet method or a dry-wet method, and a melt spinning method. As a necessary condition required for the hollow fiber membrane used in the above-described applications, the quality of the obtained hollow fiber membrane is required to be constant.

  Hollow fiber membranes are usually formed using a double tube cap, and in the case of spinning by a liquid injection method in which an injection solution is injected into the hollow inner tube of the double tube cap, the spinning is performed by adjusting the coagulation property of the conventional injection liquid. We are trying to stabilize. However, when emphasizing the performance of the hollow fiber membrane and using a low-coagulation injection solution, the spinning stability is impaired, and problems such as generation of defective yarns and yarn breakage often occur.

  As a method for improving the spinning stability and preventing the generation of defective yarns in the spinning of wet or dry wet hollow fiber membranes employing a liquid injection method, as disclosed in JP-A-9-52028 (Patent Document 1). A technique for degassing and using an injection solution when spinning a hollow fiber membrane has already been disclosed.

However, in the above technique, if there is a place where bubbles are likely to accumulate in the infusion solution supply line, when the hollow fiber membrane is spun for a long time, the bubbles flow as fine bubbles, and there is a defective yarn whose diameter changes significantly. There is a problem that it occurs or causes thread breakage directly under the base. Further, in the method of providing a bubble trap in the infusion solution supply line, when an already completed facility is used, it is necessary to improve the facility, resulting in a deterioration in manufacturing cost. Furthermore, there is a problem in productivity because it is necessary to heat the injection liquid to a predetermined temperature before starting spinning, or to lower the injection liquid temperature to the spinning temperature after discharging from the die.
JP-A-9-52028

  That is, the problem to be solved by the present invention is an improved hollow which improves the stability of spinning and prevents the generation of defective yarns in the spinning of wet or dry wet hollow fiber membranes employing a liquid injection method. It is providing the manufacturing method of a thread membrane and a hollow fiber membrane module.

In order to solve the above-mentioned problems, the present invention has reached the present invention as a result of investigating the causes of the above-mentioned problems and intensively examining them.
(1) In a hollow fiber membrane production method for producing a hollow fiber membrane by wet spinning or dry and wet spinning using a double tube die, the water solubility of the central inner tube of the double tube die is higher than that of air. A method for producing a hollow fiber membrane, comprising supplying an injection solution containing water to the central inner tube after replacing with a high gas.
(2) The method for producing a hollow fiber membrane according to the above (1), wherein the gas having a higher solubility than air has a solubility of 0.1 (g / 100 g, 25 ° C.) or more.
(3) The method for producing a hollow fiber membrane module according to the above (1) or (2), wherein the gas having higher solubility than air is selected from carbon dioxide , ammonia, and sulfur dioxide .
(4) A method for producing a hollow fiber membrane module, comprising a hollow fiber membrane obtained by the method for producing a hollow fiber membrane according to any one of (1) to (3) above.
(5) The method for producing a hollow fiber membrane according to any one of the above (1) to (4), wherein the injection solution contains a good solvent for the hollow membrane material and water.
(6) The method for producing a hollow fiber membrane according to the above (5), wherein the good solvent is selected from dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylimidazolidinone.

  When a hollow fiber membrane is produced by the spinning method of the present invention, there is almost no occurrence of yarn breakage immediately after the start of spinning or during spinning, so that stable spinning can be performed for a long time. Accordingly, the performance and quality of the hollow fiber membrane are improved, and the workability and productivity are remarkably improved. It also leads to a reduction in manufacturing costs.

  The present invention will be described in detail below.

  The hollow fiber membrane of the present invention is spun by a wet method using a double tube die or a so-called dry wet method in which the hollow fiber membrane is once discharged into the air and then introduced into a coagulation bath and solidified.

  In the present invention, the material of the hollow fiber membrane is not particularly limited as long as it can be molded into a hollow fiber membrane, and examples thereof include polymer materials such as cellulose, polyamide, polysulfone, polyolefin, and polyacrylonitrile.

  In the present invention, in the spinning method of the hollow fiber membrane, an injection solution is injected into the central inner tube of the double-tube type die to obtain a hollow fiber membrane, and the solubility in water is higher than that of air in the central inner tube. It is important to supply a gas. Thereby, when the injection solution is injected thereafter, at least a part of the air in the injection solution is replaced with a gas higher than the air.

  Hereinafter, the manufacturing method of the present invention will be specifically described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an infusion solution supply line and a central inner tube of a double tube die showing an embodiment of the present invention. In FIG. 1, 1 is a double pipe cap, 2 is an injection liquid supply line, 3 is a gas supply line, 4 is a double inner pipe central inner pipe, 5 is an injection liquid supply line opening / closing valve, and 6 is a gas supply line opening / closing valve. Indicates.

  The gas supply line opening / closing valve 6 is opened, and a gas having a solubility in water higher than that of air is caused to flow from the injection liquid supply line 2 to the double pipe cap central inner pipe 4. The pressure at this time is preferably 0.005 to 0.05 MPa, and more preferably 0.02 to 0.04 MPa. Then, the infusate supply line 2 and the double tube cap inner tube 4 are replaced with a gas having higher solubility than air.

  The gas having a higher solubility in water than air is preferably a gas having a solubility in water of 0.1 (g / 100 g: 25 ° C.) or more, and examples thereof include carbon dioxide, ammonia, and sulfur dioxide. However, carbon dioxide is particularly preferable from the viewpoint of safety and health and economy.

  Next, the gas supply line opening / closing valve 6 is closed, the injection liquid supply line opening / closing valve 5 is opened, and the injection liquid is caused to flow through the injection liquid supply line 2 and the double pipe inner pipe 4. The injection solution usually comprises a good solvent and a non-solvent for the hollow membrane material, and varies depending on the polymer forming the hollow fiber membrane. Examples of the good solvent include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and N-methyl-2. -Pyrrolidone, dimethylimidazolidinone, and the like that can generally be substituted with water are preferably used. Examples of the non-solvent include water, alcohols, aliphatic ketones, glycerin, polyethylene glycol and the like, but water is particularly preferable from the viewpoint of safety and health and economy. Since the double tube cap inner tube 4 is filled with a gas whose solubility in water is higher than that of air, when the injection solution flows, it is dissolved in the injection solution and discharged from the cap. Bubbles in the tube 4 are removed. By spinning the film-forming solution at the same time as the injection solution is discharged, the spinning stability in the region where the formation of the yarn directly under the die is started is significantly improved, and defective yarns are generated or yarn breakage occurs immediately under the die. Etc. significantly decrease.

  As described above, according to the production method of the present invention, bubbles are not generated from the injection liquid in the known wet spinning method or dry wet spinning method using a double pipe die, and stable spinning is possible for a long time. Thus, a hollow fiber membrane of good quality can be obtained.

  The hollow fiber membrane produced by the present invention is applicable to blood treatment applications such as artificial kidneys, plasma separation membranes, and extracorporeal circulation adsorption carriers, and water treatment fields such as endotoxin removal filters.

A method for producing a module using the obtained hollow fiber membrane is as follows.
First, the hollow fiber membrane is cut to a required length, bundled in a necessary number, and then put into a cylindrical case. Then, a temporary cap is put on both ends, and a potting agent is put on both ends of the hollow fiber membrane. At this time, the method of adding the potting agent while rotating the module with a centrifuge is a preferable method because the potting agent is uniformly filled. After the potting agent is solidified, both ends are cut so that both ends of the hollow fiber membrane are open, and a hollow fiber membrane module is obtained. This is followed by gamma irradiation for sterilization.

  Examples are shown below, but the present invention is not limited thereto.

Example 1
Carbon dioxide was blown at a pressure of 0.03 MPa for 2 minutes into the central inner tube of the core-sheath hollow fiber double pipe cap with an inner diameter of 0.25 mm and a slit width of 0.1 mm, and the air in the supply line of the injection solution was blown. Replaced with carbon dioxide. Next, 18 parts by weight of polysulfone (Udelpolysulfone (registered trademark) P-3500, manufactured by Solvay) and 9 parts by weight of polyvinylpyrrolidone (K30, manufactured by BASF) from the sheath of the double tube cap, 72 weights of N, N′-dimethylacetamide In addition to a mixed solvent of 1 part by weight of water and 1 part by weight of water, the film-forming stock solution obtained by dissolution is discharged, and a solution consisting of 58 parts by weight of N, N′-dimethylacetamide and 42 parts by weight of water is injected from the core. Injected.

The discharged yarn is passed through a dry section through a coagulation bath filled with a solution composed of dimethylacetamide and water, and a washing bath filled with water, taken up at a speed of 45 m / min by a take-up machine, and wound through a dancer roll. It was wound up with a take-up machine. Within 24 hours from the start of spinning, the occurrence of yarn breakage during spinning was 0.3 times (n = 3), and the spinnability was good. Further, even in the long-time spinning for 2 weeks, the occurrence of yarn breakage was 0.3 times (n = 3), and the spinnability was good.
Comparative Example 1
Spinning was performed in the same manner as in Example 1 except that carbon dioxide was not blown into the injection liquid supply line and the injection liquid was discharged as it was. Within 24 hours from the start of spinning, occurrence of yarn breakage during spinning was 2.5 times (n = 4). Furthermore, the occurrence of yarn breakage was 3.0 times (n = 4) even when spinning for 2 weeks.

It is sectional drawing of an injection liquid supply line and a double pipe cap hollow part formation fluid line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Double pipe type nozzle 2 Injection liquid supply line 3 Gas supply line 4 Double pipe type nozzle central inner pipe 5 Injection liquid supply line opening / closing valve 6 Gas supply line opening / closing valve

Claims (6)

In a hollow fiber membrane production method for producing a hollow fiber membrane by wet spinning or dry-wet spinning using a double tube die, a gas having a higher solubility in water than the air in the central inner tube of the double tube die. A method for producing a hollow fiber membrane, comprising supplying an injection solution containing water to the central inner tube after the replacement.   The method for producing a hollow fiber membrane according to claim 1, wherein the solubility of a gas having higher solubility than air is 0.1 (g / 100 g, 25 ° C) or more. The method for producing a hollow fiber membrane module according to claim 1 or 2, wherein the gas having higher solubility than air is selected from carbon dioxide , ammonia, and sulfur dioxide .   A method for producing a hollow fiber membrane module, comprising a hollow fiber membrane obtained by the method for producing a hollow fiber membrane according to claim 1.   The method for producing a hollow fiber membrane according to any one of claims 1 to 4, wherein the injection solution contains a good solvent for the hollow membrane material and water.   6. The method for producing a hollow fiber membrane according to claim 5, wherein the good solvent is selected from dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylimidazolidinone.

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