JPH0747241A - Production of hollow yarn module - Google Patents

Abstract

PURPOSE:To provide a hollow yarn module having the seal part of a terminal material excellent in heat resistance and chemical resistance by applying an elastomer soln. to the end parts of hollow yarns and further applying a solid elastomer to the coated end parts thereof and bundling the hollow yarns to heat the coated end parts thereof. CONSTITUTION:A soln. of a thermally flowable elastomer is applied to the outer peripheral surface of the end part to be sealed of each of hollow yarn like porous separation membranes to form a film and, subsequently, thermally flowable solid elastomer is applied to the formed film. The elastomer coated end parts of a large number of the hollow yarn like porous separation membranes are superposed one upon another to bundle the hollow yarn like porous separation membranes and the elastomer coated end part of the formed bundled member is heated to melt and fluidize the elastomers to closely fill the gaps between the membranes with the elastomers. At the same time, the end part of the bundled member is molded into the cavity shape of an outer cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hollow fiber module in which a bundle of hollow fiber-like porous separation membranes (hereinafter abbreviated as "hollow fiber") is housed in an outer cylinder, and more specifically, The present invention relates to a method for producing a hollow fiber module having excellent heat resistance, chemical resistance and the like using hollow fibers used as gas separation membranes, dialysis membranes, reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes and the like.

[0002]

2. Description of the Related Art Hollow fibers are separation membranes that utilize the wall of a hollow fiber-like porous material as a selective permeable membrane.
It is used for dialysis membranes, reverse osmosis membranes, ultrafiltration membranes and microfiltration membranes. This hollow fiber is modularized for practical use in order to increase the membrane area per unit volume.

A hollow fiber module is composed of an element in which a bundle of a large number of hollow fibers is housed in a pressure-resistant outer cylinder such as a cylinder, and has a high packing density of a membrane, for example, liquid such as water, juice, liquor or solvent. In addition to being able to miniaturize the filtration device for separating the useful substances of (1) from dust, miscellaneous bacteria, etc., and being excellent in pressure resistance, it is widely used in the semiconductor, food, and other fields. In particular, hollow fibers made of fluororesin such as tetrafluoroethylene resin (PTFE) have been praised for their excellent chemical resistance.

The hollow fiber module includes a closed internal pressure type separation membrane element in which one end of the hollow fiber is heat-sealed and an internal pressure circulation type separation membrane element in which openings at both ends are opened. In these elements, a hollow fiber bundle is housed in an outer cylinder, and at one or both ends of the hollow fiber, the gap between the hollow fibers and the gap between the hollow fiber bundle and the outer cylinder are made of a sealant made of various polymers (terminal. Material).

By the way, in recent years, in various industrial fields including the semiconductor industry, there is an increasing need for ultra-cleaning various chemicals used, for example, strong acids and organic solvents. Terminal materials are also required to have high chemical resistance.

Conventionally, as a method for sealing the gap between the outer cylinder and the hollow fiber bundle and the gap between the hollow fibers, epoxy resin,
A method is known in which a low-viscosity thermosetting resin such as a urethane resin or a silicone resin is injected into a terminal portion, and the mixture is allowed to stand or to be filled in a gap by centrifugal force and then cured by heating to form a sealing portion. (Japanese Patent Publication No. 44-5526, Japanese Patent Publication No. 56)
-40602).

However, these thermosetting resins are not sufficient in terms of heat resistance and chemical resistance, and a solution containing an acid or an alkali or an organic solvent is used as a solvent or a cleaning liquid,
Alternatively, its use in the field of steam sterilization is limited. Of course, it could not be used for the purpose of cleaning strong acid or organic solvent. That is, although the epoxy resin has good heat resistance, it is easily deteriorated by a strong acid, a strong alkali and some solvents, and has a skin sensitizing property, so that its application to the fields of medicine and food is limited. Urethane resin has insufficient heat resistance and is not resistant to strong acid, strong alkali and some solvents. Silicone resins have poor solvent resistance.

In order to form the terminal sealing portion by using a heat-melting resin having excellent heat resistance and chemical resistance instead of these thermosetting resins as the terminal material, there are the following problems. . The advantage of the hollow fiber module is that the membrane area per unit volume can be increased, but for that purpose, it is essential to densely pack a large number of hollow fibers in the outer cylinder.
Therefore, the filling rate of the hollow fibers (the ratio of the total volume of the hollow fibers including the inner cavity to the inner volume of the outer cylinder) is generally required to be 50% or more. However, in general, a heat-melting resin having excellent heat resistance and chemical resistance has a high melting point and a high viscosity, so that it is extremely difficult to finely mold the end sealing portion, and the filling rate of the hollow fiber is increased. It's also difficult.

For example, a fluororesin is suitable as a terminal material because it is excellent in heat resistance and chemical resistance, but since it has a high melting point and a high viscosity, it is almost fluid without pressure even if it is melted. There is no. In order to use the heat-meltable resin as the end material of the hollow fiber, it is necessary to invade the resin into the fine gap, but in the case of the fluororesin, high pressure is required for that purpose. However, since the hollow fiber has low strength, it is not possible to adopt harsh conditions such as high pressure when manufacturing the module.
The hollow fiber can be inserted into the gap by a method such as inserting the hollow fiber into a fluororesin tube or inserting a large number of hollow fibers into a fluororesin molding having a large number of holes. Since it has a high melting point, the porous structure of the hollow fiber is damaged during the sealing and molding, and the characteristics as the separation membrane are likely to be impaired. Therefore, by using a heat-melting resin with excellent heat resistance and chemical resistance, such as fluororesin, injection molding method, extrusion molding method, powder molding method, etc. are used to inject the resin into the fine gaps between the hollow fibers, Molding the material has been extremely difficult.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a hollow fiber module having a high filling rate and having a terminal sealing portion made of a terminal material having excellent heat resistance and chemical resistance. . As a result of intensive studies to overcome the above-mentioned problems of the prior art, the inventors of the present invention use a heat-flowable elastomer (elastomer that flows by heating) as a terminal material, and when molding a terminal sealing portion. After forming a coating film of the elastomer solution on the ends of the hollow fibers, a solid same or different type of heat-flowable elastomer is coated thereon, and then a plurality of these hollow fibers are bundled to form a bundle. By heating the elastomer-coated end portion to melt and flow the elastomer into a predetermined shape,
It has been found that even an elastomer having a viscosity higher than that of a thermosetting resin which has been conventionally used as a terminal material can seal a gap between hollow fibers and a gap between a hollow fiber bundle and an outer cylinder.

According to the method of the present invention, since the terminal sealing portion can be molded at a relatively low temperature and a low pressure, the porous structure of the hollow fiber is the same as in the case of using a high melting point and high viscosity heat fusible resin. It is possible to obtain a hollow fiber module which is excellent in heat resistance and chemical resistance as compared with the case of using a heat-fusible resin. Further, according to the method of the present invention, it is possible to manufacture a hollow fiber module containing hollow fibers at a high filling rate. The present invention has been completed based on these findings.

[0012]

Thus, according to the present invention, the converging body of the hollow fiber-like porous separation membrane is housed in the outer cylinder, and at least one end of the converging body is
A method for producing a hollow fiber module having a structure in which a gap between an outer cylinder and a bundle and a gap between hollow fiber-like porous separation membranes are sealed with a polymer, comprising: (1) sealing of each hollow fiber-like porous separation membrane Applying a solution of a heat-flowable elastomer to the outer peripheral surface of the end to be formed to form a coating film of the elastomer; (2) coating the coating film with a solid heat-flowable elastomer; (3) A step of bundling a plurality of hollow fiber-like porous separation membranes to form a bundle so that the respective elastomer-coated ends overlap each other, and (4) the elastomer-coated ends of the bundle are heated to remove the elastomer. Manufacturing of a hollow fiber module characterized by including a step of melt-flowing to tightly fill the gaps between the hollow fiber-like porous separation membranes with an elastomer and molding the end of the focusing body into the lumen shape of the outer cylinder. The way is It is.

The present invention will be described in detail below. The hollow fiber-like porous separation membrane used in the present invention is not particularly limited, but from the viewpoint of chemical resistance, vinylidene fluoride resin (PV
dF), ethylene-tetrafluoroethylene copolymer (ETF
Fluorine resin hollow fibers such as E) and tetrafluoroethylene resin (PTFE) can be preferably used. Among these, the hollow fiber PTFE porous body having excellent heat resistance and chemical resistance is particularly preferable.

As the material of the outer cylinder of the hollow fiber module such as a cylinder, metal such as stainless steel having excellent heat resistance and chemical resistance, PTFE, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), four A fluororesin such as a fluorinated ethylene-perfluoroalkyl vinyl ether copolymer (PFA) can be used as needed.

The heat-flowable elastomer used as the terminal material in the present invention is not limited in terms of processability, but it has excellent chemical resistance and heat resistance such as chloroprene rubber, butyl rubber, ethylene propylene rubber, and silicone rubber. , Fluororubber and the like can be preferably used. Among these elastomers, fluororubber is particularly preferable. A vulcanizing agent or the like is mixed in the crosslinkable elastomer,
It can be crosslinked when heated.

The hollow fiber module manufacturing method of the present invention will be described in more detail below with reference to the drawings. FIG. 1 is a schematic view showing a cross section of an end sealing portion of a hollow fiber module obtained by the manufacturing method of the present invention. Outer cylinder 1
A large number of hollow fibers 3 housed inside are sealed at their ends by a thermofluidic elastomer 2 to seal the gaps between the hollow fibers 3 and the gaps between the hollow fibers 3 and the outer cylinder 1. The end sealing portion is provided at one end or both ends of the hollow fiber bundle.

The hollow fiber module having such an end sealing portion can be manufactured by the following method. Prepare a predetermined number of hollow fibers. Each hollow fiber is made of, for example, stainless steel in order to maintain the shape of the hollow fiber in the step of forming the terminal sealing portion and facilitate the operation such as storing the hollow fiber bundle in the outer cylinder. It is preferable to insert a support rod made of a heat resistant material such as metal or ceramics into the inner cavity. However, in the method of the present invention, since the pressure is not so much applied during the molding, it is not always necessary to use the supporting rod. It is preferable that the end portion of the support rod is ground by a grinder or the like so as not to damage the hollow fiber when the support rod is inserted into the inner cavity of the hollow fiber and is withdrawn. The openings at both ends of each hollow fiber are usually filled with an adhesive or sealed by heat fusion.

It is desirable that at least the terminal sealing portion of the hollow fiber is subjected to surface treatment such as flame treatment in order to improve the adhesiveness with the heat-meltable polymer. In particular, when using PTFE hollow fibers, it is preferable to perform flame treatment in order to form a tightly sealed portion, except when the obtained hollow fiber module is operated under extremely mild conditions.

(1) Application Step of Heatable Flowable Elastomer Solution The solution of the heatable flowable elastomer may be prepared by adding powder, pellets, bulk, etc. of the elastomer to a solvent and gradually dissolving it with stirring. it can.
The concentration of the solution is not particularly limited, but is usually 1 to 50% by weight, preferably about 5 to 25% by weight, although it varies depending on the selection of the elastomer and the solvent.

This solution is applied to the outer peripheral surface of the end of each hollow fiber to be sealed. The application of the solution includes a method of applying with a brush, a method of immersing the hollow fiber in the solution, and a method of spraying with a sprayer, and is not particularly limited. After applying the solution, the solvent is volatilized to form a dry film. The thickness of the coating is usually
It is about 10 to 100 μm, preferably about 20 to 50 μm.

By forming the elastomer coating in advance, when the next solid elastomer is heated and fluidized, the elastomer can be tightly filled and the voids between the hollow fibers can be completely sealed. .

(2) Coating Process of Solid Heat-Fluid Elastomer The coating film obtained above is coated with a solid heat-fluid elastomer. The solid heat-flowable elastomer may be the same as or different from the one used in the above step. In order to coat the solid heat-flowable elastomer, there are a method of covering the coating with a tube-shaped molding of the elastomer, a method of winding the tape-shaped molding of the elastomer on the coating, and the like. .

The tube of the heat-flowable elastomer is obtained by melt-extruding the heat-flowable elastomer into a tube shape, or
It is produced by any method such as compression molding into a tube.
The tube is cut into appropriate lengths before use. Similarly, the heat-flowable elastomer tape is produced by any method such as melt-extruding the heat-flowable elastomer into a tape shape or compression-molding into a tape shape. Of course,
The sheet may be cut into a tape.

As shown in FIG. 2, the end of the hollow fiber coated with the coating is covered with a tube 4 or wrapped with a tape 5. The tape wrapped around the hollow fiber is usually
Both ends are heat-fused and temporarily fixed on a hot plate, or are melt-fused with an organic solvent to be temporarily fixed. The thickness of these tubes or tapes depends on the outer diameter of the hollow fiber,
Determine as appropriate in consideration of the number of used tubes and the inner diameter of the outer cylinder.

(3) Step of Creating Converging Body A plurality of hollow fibers coated with the elastomer in the above step are bundled so that their coated ends overlap each other to form a converging body.

(4) Heat-molding step The elastomer-coated end of the bundle is heated to melt and flow the elastomer so that the gaps between the hollow fiber-like porous separation membranes are tightly filled with the elastomer, and the inside of the outer cylinder is closed. The end of the focusing body is molded into a cavity shape.

Specifically, the end of the hollow fiber bundle covered with the elastomer is set in a heating device having a predetermined shape, and the elastomer is melted and fluidized by heating to mold it into the shape shown in FIG. In this way, the end portion 6 having a predetermined shape sealed with the heat-flowable elastomer is formed. On this occasion,
A vulcanizing agent may be blended with the heat-flowable elastomer and the temperature conditions and the like may be adjusted to obtain a crosslinked molded article.

The hollow fiber bundle having the end portion 6 formed in a predetermined shape is inserted into the outer cylinder 1 as shown in FIG. 4 (a). Next, the tip of the end portion 6 is cut along a surface 7 perpendicular to the hollow fiber bundle to open the hollow fiber. The support rod inserted into the inner cavity of each hollow fiber is pulled out to obtain the hollow fiber module shown in FIG. 4 (b). This cross section is as shown in FIG. According to the above method, a hollow fiber module in which one end of the hollow fiber bundle is opened and the other end is closed can be obtained. To obtain a hollow fiber module in which both ends of the hollow fiber bundle are opened, one end is sealed. After molding, other terminals may be similarly sealed or molded, or both ends may be simultaneously sealed and molded.

In order for the hollow fiber module of the present invention to operate normally as a filtration device, the adhesiveness between the sealed end material and the hollow fiber is important. When the hollow fiber comes off from the terminal material, the undiluted solution that has passed through the hollow fiber lumen and the filtered solution that has permeated through the wall surface of the hollow fiber are mixed, and it is meaningless to seal with the terminal material. Especially, PT with excellent chemical resistance
Since the FE hollow fiber has a poor affinity with other polymers, it is necessary to increase the adhesive strength as much as possible. For that purpose, it is desirable to treat the surface of the hollow fiber in advance to increase the affinity with the elastomer. .

The surface treatment method of the hollow fiber is, for example,
There is the above-mentioned flame treatment method (Japanese Patent Publication No. 63-23215). Specifically, for example, the propane gas flow rate is set at the center of a six-port burner (six burners are evenly arranged on the same circumference, and each burner port faces the central point through which the hollow fiber passes). 15-18 liters / minute, supply air flow rate 12
The flame was concentrated at liter / minute, and the hollow PTFE fiber was passed through at 7 m / minute. By performing such flame treatment, the adhesive strength between the PTFE hollow fiber and the elastomer of the terminal material can be increased.

The hollow fiber module of the present invention can maintain the same high hollow fiber filling rate as the conventional product. According to the production method of the present invention, a heat-flowable elastomer having excellent chemical resistance such as fluororubber, which has been conventionally considered to be difficult to be finely molded due to its high viscosity, is used as a sealant at the end of a hollow fiber module. Therefore, it is possible to greatly improve heat resistance and chemical resistance as compared with a sealing agent which is conventionally used such as epoxy resin, silicone resin or urethane resin. In particular, if fluororubber is used as the heat-flowable elastomer, it can be used for separation / concentration applications in which a strongly acidic or strongly alkaline solution or any solvent is used as a solvent, and steam sterilization can be repeated. A hollow fiber module is obtained. Furthermore, chemical-resistant, heat-meltable resin having excellent heat resistance, for example,
Compared to a hollow fiber module in which the terminal sealing part is made under harsh conditions using a resin with a high melting point and high viscosity, such as a fluororesin, the hollow fiber does not suffer heat damage or pressure damage. It is possible to fabricate a module that maintains the original sharing performance of.

[0032]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Example 1] Outer diameter 2.8 mm, inner diameter 2.0
mm hollow fiber made of PTFE porous body
630 pieces cut into a length of 00 mm were prepared. On the other hand, 630 pieces of stainless steel rods having a diameter of 1.9 mm cut into 1000 mm were prepared and inserted into the inner cavities of each hollow fiber. Next, both ends of each hollow fiber were heat-sealed using a high temperature heat sealer. A hollow fiber module was produced by the following steps.

(1) VdF fluororubber [manufactured by Daikin Industries, Ltd., trade name Daiel G-1001] mixed with a vulcanizing agent and a vulcanization aid, and dissolved in a solvent to give a rubber solution (concentration 2
0% by weight) was prepared. For each of the 630 hollow fibers, apply the rubber solution to the outer peripheral surface up to 50 mm from the end,
After that, the solvent was evaporated to dryness (film thickness of about 50μ
m). (2) A fluororubber having the same formulation as described above was extruded by a melt extruder into a tube having an outer diameter of 4.4 mm and an inner diameter of 3.5 mm, and 630 pieces cut into a length of 50 mm were prepared. In the portion of 630 hollow fibers coated with the rubber solution,
The rubber tube was covered.

(3) 630 rubber-coated hollow fibers were bundled as shown in FIG. 5 to form a bundle. (4) The rubber coated end of this bundle is set in a heating device having a predetermined shape and heated to 110 ° C.
It was molded into 8 mm, and then vulcanization was allowed to proceed at 160 ° C.
Then, the same operation as above was repeated for the other end of the hollow fiber. (5) The obtained molded product was taken out of the heating device and then inserted into an outer cylinder having an inner diameter of 88 mm. After cutting both ends, the stainless rod was pulled out to open both ends of each hollow fiber. In the obtained hollow fiber module, the gap between the outer cylinder and the hollow fiber bundle and the gap between the hollow fibers were tightly sealed with vulcanized rubber, and the hollow fibers were evenly arranged.

Example 2 In the same manner as in Example 1, 630 PTFE hollow fibers having both ends heat-sealed were prepared. (1) VdF fluororubber [G-1
001] was mixed with a vulcanizing agent and a vulcanization aid to prepare a solution, which was applied to the end of the hollow fiber and dried as in Example 1. (2) A tape having a thickness of 0.5 mm was cut with a roll mixer to prepare a rubber having the same formulation as described above, and cut into 10 mm × 50 mm to obtain a tape. The length of the hollow fiber and 50 m of the rubber tape were applied to the part of 630 hollow fibers coated with the rubber solution.
The tape was wound so that the directions of the m width were aligned, and the wound tape was melted and temporarily fixed on a hot plate heated to 110 ° C. by the method shown in FIG. 6 and then bundled into a bundle. (3) Subsequent operations were performed in the same manner as in Example 1,
A similar hollow fiber module was obtained.

[Example 3] As a heat-flowable elastomer, a VdF fluororubber [Daiel G-704 manufactured by Daikin Industries, Ltd.] mixed with an acid acceptor was used, and a temporary tape wrapped around a hollow fiber was used. A hollow fiber module in which the hollow fibers were evenly arranged was obtained in the same manner as in Example 2 except that the fixing was performed by dissolution with methyl ethyl ketone.

[Comparative Example 1] In the same manner as in Example 1, 630 PTFE hollow fibers having both ends heat-sealed were prepared. (1) Outer diameter 4.4 mm, inner diameter 3.5 mm, length 50 mm
630 tubes of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) were prepared and covered on the ends of the hollow fibers. (2) 630 FEP-coated hollow fibers were bundled into a bundle, and the end portion of the FEP-coated hollow fiber was set in a heating device and heated to 290 ° C. to form a diameter of 88 mm. (3) Next, the same operation was repeated for the other end, and then the molded product was inserted into the outer cylinder. (4) Both ends were cut, the stainless steel rod was pulled out, and both ends of the hollow fiber were opened, whereby a hollow fiber module end-capped with FEP was obtained. Since this hollow fiber module was sealed and molded at a high temperature, the porous structure of the hollow fiber was impaired and the separation performance was significantly deteriorated.

Comparative Example 2 In the same manner as in Example 1, 630 PTFE hollow fibers having both ends heat-sealed were prepared. (1) VdF fluororubber [G-1001] with a vulcanizing agent,
A mixture of vulcanization aids with a roll mixer with a thickness of 1 mm
As the sheet, two strip-shaped sheets having a width of 50 m and a weight of 350 g were prepared. (2) Each end of each hollow fiber was placed on the sheet so that both ends thereof were orthogonal to the longitudinal direction of each sheet. (3) The belt-shaped sheet was rolled up so that the end of each hollow fiber was on the inside, to prepare a preliminary shaped product. (4) After that, when the same procedure as in Example 3 was carried out, the rubber was not completely filled in a part of the gap between the hollow fibers to form a channel. In addition, the arrangement of the hollow fibers was uneven.

[0040]

EFFECT OF THE INVENTION According to the production method of the present invention, a hot-fluid elastomer having excellent heat resistance and chemical resistance is used as a sealant to produce a hollow fiber module in which hollow fibers are densely packed. You can According to the present invention, there is provided a hollow fiber module which can be used even in a field requiring chemical resistance such as semiconductor industry.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section of an end sealing portion of a hollow fiber module of the present invention.

FIG. 2 is a diagram showing a method of coating a solid elastomer on an end portion of a hollow fiber after applying an elastomer.

FIG. 3 is a view showing a hollow fiber bundle in which a heat-flowable elastomer is heated and melted to form an end sealing portion.

FIG. 4 is a diagram showing a hollow fiber bundle housed in an outer cylinder and a method of cutting an end portion to form a hollow fiber module.

FIG. 5 is a view showing a bundled body in which end portions of a plurality of hollow fibers are covered with tubes made of a heat-flowable elastomer and then bundled.

FIG. 6 is a view showing a state in which a tape made of a heat-fluidizable elastomer is wound around the outer peripheral surface of the end portion of the hollow fiber and then temporarily fixed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Heated fluid elastomer 3 Hollow fiber 4 Heated fluid elastomer tube 5 Heated fluid elastomer tape 6 Terminal part 7 sealed by heat fluidized elastomer 7 Cut part

Claims (6)

[Claims] 1. A bundle of hollow fiber-shaped porous separation membranes is housed in an outer cylinder, and at least one end of the bundle has a gap between the outer cylinder and the bundle and a hollow fiber-shaped porous separation membrane. A method for producing a hollow fiber module having a structure in which mutual gaps are sealed with a polymer, comprising: (1) a solution of a heat-flowable elastomer on the outer peripheral surface of the end of each hollow fiber-shaped porous separation membrane to be sealed. To form a coating of the elastomer, (2) coating the coating with a solid, heat-fluidizable elastomer, and (3) a plurality of such that the respective elastomer coated ends overlap each other. A step of bundling the hollow fiber-shaped porous separation membranes to form a bundle, and (4) heating the elastomer-coated end of the bundle to melt and flow the elastomer to form a gap between the hollow fiber-shaped porous separation membranes. Closely filled with elastomer A method of manufacturing a hollow fiber module, which comprises the step of filling and consolidating the end of the bundle into the inner cavity shape of the outer cylinder. 2. The solid heat-flowable elastomer is formed by molding the elastomer into a tube shape, and in the step (2), the tube is covered on the coating film. 1. The manufacturing method according to 1. 3. The solid heat-flowable elastomer is a tape-shaped molding of the elastomer, and
The manufacturing method according to claim 1, wherein the tape is wound around the coating film in the step (2). 4. The heat-flowable elastomer used in steps (1) and (2) is crosslinkable, and in step (4), the elastomer is melted and fluidized and crosslinked. The manufacturing method according to any one of claims 1 to 3, wherein: 5. The method according to claim 1, wherein the heat-flowable elastomer used in the steps (1) and (2) is a fluororubber. 6. The method according to claim 1, wherein the hollow fiber-shaped porous separation membrane is a hollow fiber-shaped tetrafluoroethylene resin porous body.