JP2008207050A - Manufacturing method of hollow fiber membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for increasing the cleaning efficiency by using the permeation mechanism of the membrane, by continuously sealing the hollow fiber membrane in the manufacturing process, and provide a cleaning member. <P>SOLUTION: In a method for manufacturing the hollow fiber membrane, the hollow fiber membrane in the manufacturing process is introduced to a decompression vessel, and core liquid is sucked by using the permeation mechanism of the membrane. Elastic members are mounted at an inlet port of the hollow fiber membrane and an outlet port of the hollow fiber membrane of the decompression vessel, and the vessel to be sealed by introducing the hollow fiber membrane therein is used to produce the hollow fiber membrane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a hollow fiber membrane such as an ultrafiltration membrane and a microfiltration membrane.

  In the production of hollow fiber membranes such as ultrafiltration and microfiltration, solution spinning using a solvent as a core solution is generally performed using a tube-in orifice. The solution is spun from the tube-in orifice together with the core liquid into the coagulation tank (cooling tank), solidified and drawn, and then the cleaning process is performed to remove the core liquid (solvent) remaining in the hollow fiber membrane. Then, film processing such as coating is performed. In the main hollow fiber membrane washing step, the hollow fiber membrane is immersed in a hot water tank, and the solvent in the membrane is diluted and removed by dissolution (liquid) diffusion.

However, when a high concentration core solution is used for the hollow fiber membrane, or when the pores of the membrane wall are small, it takes a lot of time for dissolution and diffusion, and the washing process is often prolonged. Further, when the cleaning becomes insufficient, various problems occur in the subsequent drying process and coating process. When the core liquid of the hollow fiber membrane cannot be sufficiently removed as described above, there is a method of cutting the hollow fiber membrane after spinning and press-fitting the cleaning liquid under pressure (see Patent Document 1). However, the thread bundle once cut is sealed in a container and washed by draining under air pressure, and the process is simple. However, there is a problem that it cannot be adopted in a process of applying a continuous treatment to a hollow fiber membrane.
JP-A-9-262445

  Accordingly, an object of the present invention is to provide a method for producing a hollow fiber membrane in which the core liquid and / or solvent of the hollow fiber membrane being produced is efficiently extracted and washed.

In order to achieve the object, the present invention is characterized by any of the following configurations.
(1) A method for producing a hollow fiber membrane in solution spinning using a solvent as a core liquid, wherein after the step of simultaneously spinning and solidifying the solution together with the core liquid, the solidified hollow fiber membrane is guided to a vacuum vessel, A method for producing a hollow fiber membrane, comprising a step of sucking a core liquid and / or a solvent remaining in the hollow fiber membrane.
(2) The method for producing a hollow fiber membrane according to claim 1, wherein the core liquid is sucked online.
(3) The method for producing a hollow fiber membrane according to claim 1 or 2, wherein the vacuum container is vacuumed and sucked in a range of -5 to -85 kPa.
(4) The decompression vessel includes at least a hollow fiber membrane inlet, a hollow fiber membrane outlet, and a vacuum suction port, and the hollow fiber membrane inlet and the hollow fiber membrane outlet are formed of an elastic member, The method for producing a hollow fiber membrane according to any one of claims 1 to 3, wherein the vacuum container is sealed by an elastic member.

  In the present invention, the hollow fiber membrane in the production process is introduced into the vacuum container, the hollow fiber membrane is sealed at both ends of the container, and the container is decompressed between the outer wall side and the inner wall side of the hollow fiber membrane. The core liquid can be permeated to the outer wall side of the hollow fiber membrane and washed using the differential pressure that acts. Furthermore, it becomes possible to efficiently collect a high concentration core liquid. Such a decompression vessel can achieve a sealing mechanism by using elastic members at the inlet of the hollow fiber membrane and the outlet of the hollow fiber membrane.

  The present invention will be specifically described below with reference to the drawings. Note that the present invention is not limited to the following embodiments. FIG. 1 shows an example of a schematic cleaning flow in the manufacturing process of the hollow fiber membrane of the present invention. In FIG. 1, using a dry and wet solution spinning method, the spinning solution is extruded in a hollow fiber form into a coagulation bath (cooling bath) 10 together with a core solution from a spinning pack 9 in which a tube-in orifice is loaded. Then, the hollow fiber membrane 7 is pulled out and subsequently guided to the decompression vessel 1 and wound up through the water washing bath 11. At this time, the decompression container 1 is sucked through the decompression line 13 connected to the suction pump 14.

  When the hollow fiber membrane 7 is pulled out from the hollow fiber membrane inlet 2 to the hollow fiber membrane outlet 3 as shown in FIG. 2, the vacuum container 1 of the present invention has a tapered elastic member hollow fiber membrane. When the inside of the decompression vessel 1 is depressurized, an effective differential pressure can be generated between the outer wall surface and the inner wall surface of the hollow fiber membrane 7. . As a result, when the core liquid 8 of the hollow fiber membrane 7 passes through the membrane wall and is extracted from the suction port 4 for decompression, the core liquid is removed and the cleaning water is soaked in the coagulation. The membrane wall is washed by permeating. In addition, when a hollow fiber membrane is introduced in the gas phase, a dehumidifying effect can be expected in which air flows through the membrane wall and lowers the moisture content. Such a permeation mechanism using the decompression vessel 1 can be used for online processing or offline batch processing in the production of hollow fiber membranes. Especially, since this invention can respond to the continuous process of a hollow fiber membrane, an on-line process is preferable.

  Here, the core liquid refers to a hollow portion formed by a hollow fiber membrane in the manufacturing process, a liquid existing on the membrane wall, and fine particles dissolved in the liquid using a solution spinning method or a melt spinning method.

  The reduced pressure range is preferably in the range of −5 to −85 kPa, and more preferably in the range of −30 to −85 kPa. In consideration of pressure resistance, suction time, etc., the decompression containers 1 may be arranged in a large number (stages) and decompressed in stages.

  The decompression vessel 1 is equipped with a hollow fiber membrane inlet 2 and a hollow fiber membrane outlet 3 made of an elastic member in the main body, and the hollow fiber membrane inlet 2 and the hollow fiber due to deformation of the hollow fiber membrane 7 or the like. If an excessive external force is applied when passing through the membrane outlet 3, the hollow fiber membrane inlet 2 and the hollow fiber outlet 3 are deformed to maintain an equilibrium with the external force. That is, even if the outer diameter fluctuation of the hollow fiber membrane 7 occurs, the outer surface of the hollow fiber membrane 7 can be continuously sealed by reversibly deforming. Furthermore, the hollow fiber membrane introduction port 2 and the hollow fiber membrane outlet port 3 are expanded to reduce the yarn clogging of the hollow fiber membrane.

  Elastic members used for the hollow fiber membrane inlet 2 and the hollow fiber membrane outlet 3 are styrene rubber, chloroprene rubber, nitrile rubber, silicone rubber, chlorosulfonated polyethylene rubber having both solvent resistance and mechanical strength. Fluorine rubber, ethylene propylene rubber, urethane rubber, acrylic rubber, fluorosilicone rubber and the like are preferably used.

  The hollow fiber membrane introduction port 2 and the hollow fiber membrane outlet port 3 are preferably formed so as to become smaller in the traveling direction of the hollow fiber membrane 7, and when the hollow fiber membrane is tapered, the insertion of the hollow fiber membrane ( (Induction) is preferable because it becomes easy. When equipped in the container body, it is preferable that the hollow fiber membrane inlet 2 is mounted so as not to be restrained by the container body when the tip of the introduction port 2 of the hollow fiber membrane is deformed. The hollow fiber membrane inlet 2 and the hollow fiber outlet 3 are preferably substantially circular when no load (external force) is applied, and even if they are elliptical enough to maintain sealing properties, there is no problem. Absent.

  Moreover, as shown in FIG. 3, it is preferable to consider the front-end | tip part of the inlet 2 of the hollow fiber membrane, and the outlet 3 so that the balance of a sealing performance and a deformation | transformation external force may be maintained. When the ratio of the land length (L) to the outer diameter (D) of the tip portion is in the range of 0.1 to 10, and the member thickness (t) of the tip portion is in the range of 0.1 to 5 mm, This is preferable because the running property of the hollow fiber membrane is balanced. On the other hand, the components other than the hollow fiber membrane inlet 2 and the hollow fiber membrane outlet 3 of the decompression vessel 1 are of course made up of the same members as the hollow fiber membrane inlet 2 and the hollow fiber membrane outlet 3. However, any material may be used as long as it is selected from plastics, metals, ceramics, etc. in consideration of solvent resistance and mechanical strength.

  The concentration of dimethyl sulfoxide solvent was measured by preparing a calibration curve and measuring the refractive index using an Abbe differential refractometer.

  Examples will be described below, but the present invention is not limited thereby.

<Example 1>
An acrylonitrile homopolymer having an intrinsic viscosity of 3.1 (dl / g) was dissolved in a dimethyl sulfoxide solvent at 80 ° C. to obtain a membrane spinning solution having a polymer concentration of 13% by weight. From the spinning pack in which the tube-in-orifice shown in FIG. 1 is loaded, this spinning solution is filled with a core liquid (85% by weight dimethyl sulfoxide aqueous solution) into a hollow fiber at the same time, and 16% by weight dimethyl sulfoxide as a cooling liquid at 10 ° C. It extruded to the cooling bath which has aqueous solution, and it was made to cool and solidify. Subsequently, the hollow fiber membrane was guided to the decompression vessel 1 at a speed of 6 m / min, and the decompression line connected to the decompression vessel 1 was sucked at −50 kPa, and then wound up through the water washing bath 11 at 60 ° C. The decompression vessel 1 has a hollow fiber membrane inlet 2 and a hollow fiber membrane outlet 3 made of silicone rubber (tip shape D = 3.0 mmφ, L = 5.0 mm, t = 1.0 mm) made of stainless steel pipe. The one attached to the main body was used. 8 hours after spinning, the washing solution in the water washing bath 11 was sampled, and the dimethyl sulfoxide concentration was measured with a differential refractometer. As a result, the dimethyl sulfoxide concentration was 12%.

<Comparative Example 1>
Using the same spinning solution as in Example 1, a 60 ° C. water-washing bath 12 was installed in place of the vacuum vessel 1 of Example 1 at the same speed as shown in FIG. Washed in two stages. Similarly, the dimethyl sulfoxide concentration was 28% as a result of measuring the dimethyl sulfoxide concentration of the washing solution in the water washing bath 11 with a differential refractometer 8 hours after spinning. Although the passage distance of the hollow fiber membrane was the same as in Example 1, the cleaning concentration was about twice as high.

It is a schematic flowchart which shows one embodiment of the manufacturing process of the hollow fiber membrane concerning this invention. It is a typical sectional side view which shows the washing | cleaning principle of the vacuum container and hollow fiber membrane concerning this invention. It is a schematic diagram which shows the front-end | tip part of the pressure reduction container concerning this invention. It is a schematic flowchart of the manufacturing process of the hollow fiber membrane which shows a comparative example.

Explanation of symbols

1: Depressurization vessel 2: Hollow fiber membrane inlet 3: Hollow fiber membrane outlet 4: Decompression suction port 5: Depressurization vessel body 6: Hollow fiber membrane inlet and hollow fiber membrane outlet Part 7: Hollow fiber membrane 8: Core liquid (hollow part)
9: Spin pack 10: Coagulation bath (cooling bath)
11: Washing bath 12: Washing bath 13: Decompression line 14: Suction pump 15: Winder A: Suction direction B: Pull-out direction of the hollow fiber membrane L: 5.0 mm
D: 3.0mmφ
t: 1.0 mm

Claims (4)

A method for producing a hollow fiber membrane in solution spinning using a solvent as a core liquid, wherein after the step of simultaneously spinning and solidifying the solution together with the core liquid, the solidified hollow fiber membrane is guided to a vacuum vessel to form a hollow fiber membrane. A method for producing a hollow fiber membrane, comprising a step of sucking a core liquid and / or a solvent remaining therein. The method for producing a hollow fiber membrane according to claim 1, wherein the core liquid is sucked online. The method for producing a hollow fiber membrane according to claim 1 or 2, wherein the vacuum vessel is vacuumed and sucked in a range of -5 to -85 kPa. The decompression container includes at least a hollow fiber membrane inlet, a hollow fiber membrane outlet, and a vacuum suction port, and the hollow fiber membrane inlet and the hollow fiber membrane outlet are constituted by elastic members, The method for producing a hollow fiber membrane according to any one of claims 1 to 3, wherein the vacuum container is sealed.

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