JP2001087631A - Method for preparing film by melt spinning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a hollow fibrous porous film comprising a thermoplastic resin with dense pores and high water permeability suitable for the use in filtration such as turbidity removal. SOLUTION: In a method for obtaining a hollow fibrous porous film by firstly melting a thermoplastic resin and an organic at a high temperature, then extruding the molten material from a spinning orifice for molding a hollow into a liquid bath in hollow fiber structure to cool and harden via the air while injecting into a hollow part a fluid which forms a hollow part, and subsequently extracting and removing the organic liquid, thereby obtaining a hollow fibrous porous films, the method is characterized in that (1) the time for which the extrudate is running in the air is within a range from 0 to 1 second (, provided that 0 is not included) and that (2) the hollow part forming fluid is a liquid having a higher boiling point than the temperature at the spinning orifice, particularly preferably a liquid having a higher boiling point than the temperature at the spinning orifice and a liquid-liquid phase separability from the thermoplastic resin.

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-shaped porous membrane made of a thermoplastic resin having fine pores and high water permeability, which is suitable for filtration such as turbidity.

[0002]

2. Description of the Related Art Filtration operations using porous membranes such as microfiltration membranes and ultrafiltration membranes are carried out in the automobile industry (electrodeposition paint recovery and reuse system), the semiconductor industry (ultra pure water production), the pharmaceutical food industry (sterilization, It has been put to practical use in many fields such as enzyme purification. Particularly in recent years, it has been widely used as a method for producing drinking water and industrial water by turbidizing river water and the like. Above all, hollow fiber porous membranes are particularly widely used because the membrane area that can be filled per unit volume can be increased and the filtration capacity per unit space occupied can be increased.

[0003] As a method for producing a porous membrane, phase separation (phase conversion) is used.
(Akira Takizawa, Membrane, p. 36)
7-418, IPC Co., Ltd., 1992, or supervision by Masakazu Yoshikawa et al., Membrane Technology Second Edition, pp. 77-107,
(IPC, 1997, etc.). Above all, the heat-induced phase separation method in which a polymer is melted with a solvent at a high temperature and then cooled and phase-separated (thermal phase inversion method, which is called a melting method in this specification) is basically a thermoplastic polymer. If it is, it is an excellent film-forming method that can be widely applied to a polymer compound that does not have a suitable solvent at around normal temperature and cannot be subjected to other phase separation methods (Akira Takizawa, Membrane, p404, Inc.) IPC, 1
992). In particular, it is a great advantage of the melting method that it can be applied to a polyolefin polymer compound (polypropylene, polyethylene, etc.) which is inexpensive and has excellent mechanical and chemical strength, although other phase separation methods cannot be taken.

[0004] The process of forming a film by a melting method is as follows.
1) The thermoplastic resin and the solvent are uniformly melted at a high temperature by an extruder or the like, and 2) The melt is extruded from a spinneret into the liquid bath through the air through the spinneret and cooled to phase-separate (polymer rich). Phase) and solidification (coagulation) after generation of the polymer phase. 3) Removal of the solvent in the solidified substance (at this time, the polymer rich phase portion at the time of phase separation becomes a porous membrane skeleton, There is known a method in which a polymer dilute phase portion becomes a pore during separation (JP-A-55-60537, JP-A-55-22398, etc.).

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for producing a hollow fiber-like porous membrane made of a thermoplastic resin having fine pores and high water permeability, which is suitable for filtration such as turbidity. The purpose is to:

[0006]

According to the present invention, there is provided (1) a method in which a thermoplastic resin and an organic liquid are melted at a high temperature, and then the melt is poured into a hollow portion from a spun for forming a hollow fiber into a hollow portion. In a method of extruding into a liquid bath through the air into a hollow fiber shape while injecting, cooling and solidifying, and then extracting and removing the organic liquid to obtain a hollow fiber-shaped porous membrane, the extruded material travels in the air in a time. A hollow fiber-shaped porous membrane made of a thermoplastic resin, wherein the hollow fiber is a liquid having a boiling point not lower than the spinning temperature, which is between 0 and 1 second (however, 0 is not included). (2) a hollow fiber formed of the thermoplastic resin according to the above (1), wherein the hollow part forming fluid is a liquid having a liquid-liquid phase separation ability with the thermoplastic resin at a high temperature. (3) Extruded material in air (4) a method for melt-forming a hollow fiber-like porous membrane made of a thermoplastic resin according to the above (1) or (2), wherein the running time is between 0 and 0.5 seconds (however, 0 is not included); Melting the hollow fiber-shaped porous membrane made of the thermoplastic resin according to the above (1) or (2), wherein the time for the extrudate to travel in the air is between 0 and 0.25 seconds (excluding 0). A membrane method, (5) a method for melt-forming a hollow fiber-like porous membrane comprising a thermoplastic resin according to the above (1) to (4), wherein the liquid bath is substantially composed of water, and (6) a thermoplastic resin made of polyethylene. The present invention also relates to a method for melt-forming a hollow fiber-shaped porous membrane comprising the thermoplastic resin according to the above (1) to (5).

Hereinafter, the present invention will be described in detail. Thermoplastic resin (thermoplastic polymer) is not easily deformed at room temperature and has elasticity and does not show plasticity, but it shows plasticity by appropriate heating, molding becomes possible, and when cooled down, the temperature returns Is a resin that undergoes a reversible change back to an elastic body and does not cause chemical changes such as molecular structure during that time (edited by the Editing Committee of the Chemical Dictionary, compact edition of the Chemical Dictionary 6, Kyoritsu Shuppan, 860 and 867 P. 1963).

[0008] As an example, 12695 chemical products, Kagaku Kogyo Nippo, 1995 thermoplastics section (8
29-882), the Chemical Society of Japan, edited by Chemical Handbook, 3rd revised edition, Maruzen, 809-810, 1980.
Resins and the like described on the page can be mentioned. Specific examples include polyethylene, polypropylene, polyvinylidene fluoride, ethylene vinyl alcohol copolymer, polyamide, polyetherimide, polystyrene, polysulfone, polyvinyl alcohol, polyphenylene ether,
Examples include polyphenylene sulfide, cellulose acetate, and polyacrylonitrile. Among them, polyolefin-based polymers (polyethylene, polypropylene, polyvinylidene fluoride, etc.) are suitable as a raw material for aqueous filtration membranes because of their high water resistance due to hydrophobicity. Furthermore, among these polyolefin-based polymers, since they do not contain a halogen element which is a problem at the time of disposal, and there are few tertiary carbons having high chemical reactivity, chemical deterioration during film washing does not easily occur and long-term use resistance can be expected, Polyethylene, which is inexpensive, is particularly preferred.

When the organic liquid used in the present invention is mixed with a thermoplastic polymer, it is in a liquid-liquid phase separated state at a certain temperature and in a range of the thermoplastic polymer concentration (a thermoplastic polymer dense phase droplet / thermoplastic polymer droplet). 2 of dilute phase or organic liquid dense phase droplet
Phase coexisting state) and has a boiling point not lower than the upper limit temperature of the liquid-liquid phase separation temperature range. It may be a mixed liquid instead of a single liquid. When such an organic liquid and a thermoplastic polymer are mixed in a concentration range in which liquid-liquid phase separation occurs, the thermoplastic polymer is heated at a temperature higher than the upper limit temperature at which a liquid-liquid phase separation state is obtained in the mixed composition. And an organic liquid can be obtained. When the compatibilized material is cooled, a coexistence state (liquid-liquid phase separation state) of two liquid-liquid phases (a thermoplastic polymer concentrated phase droplet and an organic liquid concentrated phase droplet) appears, and a pore structure is generated. The pore structure is fixed by cooling to a temperature at which the plastic polymer solidifies.

FIG. 1 shows an example of this phase diagram. In FIG. 1, the concentration of the thermoplastic polymer is the ratio of the weight of the thermoplastic polymer to the sum of the weight of the thermoplastic polymer and the weight of the organic liquid. The liquid 1 phase region is a compatible region of the thermoplastic polymer and the organic liquid, and the liquid / liquid 2 phase region is a coexisting region of the thermoplastic polymer rich phase (liquid) and the thermoplastic polymer dilute phase (liquid). To
The solidified region indicates a region where the thermoplastic polymer is solidified (a region where the solid thermoplastic polymer and the organic liquid coexist).

After the pore structure is fixed, the organic liquid is removed from the membrane to obtain a hollow fiber-like porous body. At this time, the thermoplastic polymer rich phase portion at the time of liquid-liquid phase separation is cooled and solidified to form a porous structure (porous skeleton), and the thermoplastic polymer dilute phase (organic liquid rich phase) portion becomes a pore portion. . Therefore, the organic liquid referred to in the present invention is a liquid which is a solvent of a thermoplastic polymer at a high temperature, but is a non-solvent at a low temperature (for example, near normal temperature). For example, when the thermoplastic polymer is polyethylene, examples of such an organic liquid include dibutyl phthalate, diheptyl phthalate, dioctyl phthalate,
Phthalic acid esters such as di (2-ethylhexyl) phthalate, diisodecyl phthalate, ditridecyl phthalate,
Sebacic esters such as dibutyl sebacate, adipic esters such as dioctyl adipate, maleic esters such as dioctyl maleate, trimellitic esters such as trioctyl trimellitate, tributyl phosphate, trioctyl phosphate and the like Phosphoric esters,
Examples thereof include propylene glycol dicaprate, glycol esters such as propylene glycol dioleate, glycerin esters such as glycerin trioleate, and the like, alone or in combination of two or more. Furthermore, a liquid that is incompatible with polyethylene alone at high temperatures or a liquid such as liquid paraffin that is compatible with polyethylene at high temperatures alone but does not form a liquid-liquid two-phase separation state due to too high compatibility. , The definition of organic liquid (a liquid that can be in a liquid-liquid phase separation state at a certain temperature and polyethylene concentration range when mixed with polyethylene and has a boiling point not lower than the upper limit temperature of the liquid-liquid phase separation temperature range) Among them, a mixed liquid mixed with the above-mentioned organic liquid examples (such as phthalic esters) can also be mentioned as examples of the organic liquid.

The thermoplastic polymer and the organic liquid are mixed and mixed at a predetermined mixing ratio using a twin screw extruder at a temperature higher than the upper limit temperature of the liquid-liquid phase separation temperature range at the mixing ratio. Can be done. The mixing ratio between the thermoplastic polymer and the organic liquid is disadvantageous because the strength of the obtained film is too low when the ratio of the thermoplastic polymer is too small, and conversely, when the ratio of the thermoplastic polymer is too large. This is disadvantageous because the water permeability of the resulting membrane is too low. The preferred mixing ratio between the thermoplastic polymer and the organic liquid is from 10/90 to 50/50 by weight of the thermoplastic polymer / organic liquid.

The compatible material (melt) is guided to a portion called a head at the tip of the extruder and extruded. By mounting a die for extruding the compatible material into a predetermined shape at the extrusion port in the head, the compatible material can be formed into a predetermined shape and extruded. In the case of the present invention, a spinneret for forming into a hollow fiber (hollow fiber forming spinneret) is attached to the extrusion port of the head. The hollow fiber forming spinneret has an annular hole for extruding the compatible material into a hollow shape (annular shape) and an extruded hole for preventing the hollow portion of the extruded hollow material from closing to form a column. Spouting nozzle having a hole (existing inside the above-mentioned annular hole; the shape is a circular hole) for discharging a hollow part forming fluid to be injected into the hollow part of the hollow material formed on the extrusion side surface It is. The miscible material of the thermoplastic polymer and the organic liquid is injected into the hollow portion through the hole inside the annular hole from the annular hole of the above-described hollow fiber forming spout while receiving the injection of the hollow portion forming fluid into the hollow portion ( (Even in an inert gas such as nitrogen).

The hollow part forming fluid is, of course, non-reactive with the extrudate (thermoplastic polymer and organic liquid), but in addition, is a liquid when discharged from the spinneret. This is necessary in order to maintain the roundness of the cross-sectional shape of the extruded hollow object. When the hollow part forming fluid is a gas (for example, nitrogen gas or air), it is difficult to maintain the roundness of the cross-sectional shape of the hollow object after being extruded from the spinneret. Since the hollow part forming fluid is discharged from the inside of the spinneret, it is necessary to use a liquid having a boiling point equal to or higher than the spinning point temperature as the hollow part forming fluid in order to ensure that the liquid is also liquid at the time of discharging.

As the characteristics of the fluid forming the hollow portion, in addition to the fact that the boiling point is not lower than the spinning temperature, when mixed with a liquid having a capability of liquid-liquid phase separation with a thermoplastic polymer at a high temperature, that is, when mixed with a thermoplastic polymer, Liquid-liquid phase separation at a certain temperature and thermoplastic polymer concentration range (thermoplastic polymer dense phase droplets /
By using a liquid capable of forming a thermoplastic polymer dilute phase, that is, a two-phase coexistence state of an organic liquid dense phase droplet, the water permeability of the obtained porous membrane can be remarkably improved. In this case, the temperature of the hollow part forming fluid when discharged from the spinning nozzle for forming a hollow fiber does not necessarily need to be a temperature at which the thermoplastic polymer and the liquid-liquid phase separation state are obtained, but a temperature at which the liquid-liquid phase separation state is obtained. It may be higher or lower than the range. Examples of such a fluid for forming a hollow portion include the same examples as those of the above-described organic liquid. The boiling point of the hollow part forming fluid may be lower than the upper limit temperature of the liquid-liquid phase separation temperature region, unlike the above-mentioned organic liquid, as long as the boiling point is higher than the spinning temperature.

The compatible material extruded into the air is guided to a liquid bath and cooled to a temperature at which the thermoplastic polymer in the extruded material solidifies. The compatibilized material extruded from the spinneret is cooled during passage from the spinneret outlet into the liquid bath, thereby causing liquid-liquid phase separation to occur, generating a pore structure, and then solidifying,
The hole structure is fixed. The composition of the liquid bath is not particularly limited as long as it has no reactivity with the extrudate (thermoplastic polymer and organic liquid), and may be the same as the organic liquid in the extrudate. However, the temperature needs to be lower than the solidification temperature of the thermoplastic polymer in the extrudate composition. Since the important function of the liquid bath is the function of cooling the extrudate, water, which has a high cooling capacity, that is, a liquid having a large heat capacity, is preferable as the composition of the liquid bath.

The time required for the compatible substance extruded from the spinneret into the air to enter the liquid bath, that is, the air travel time, is from zero to one.
Up to seconds (but not including zero). When the air travel time is zero, the extruded surface of the spinneret comes into contact with the liquid surface of the liquid bath. Since the spinning temperature is set to a temperature higher than the compatibility temperature of the thermoplastic polymer and the organic liquid, that is, the liquid-liquid phase separation temperature range in the mixed composition, the liquid bath is set to a temperature lower than the solidification temperature of the thermoplastic polymer. Inevitably higher temperatures. Therefore, when the air traveling time is zero, the spinneret is always cooled by the liquid in the liquid bath, and the temperature control of the spinneret becomes unstable, which is not suitable. On the other hand, if the air traveling time is too long, the porosity of the outer surface decreases, and the water permeability of the membrane decreases, which is not preferable. The air travel time is preferably between zero and 0.5 seconds (but not including zero), and more preferably between zero and 0.25 seconds (but not including zero). The aerial traveling time is measured by the following formula based on the winding speed and the aerial traveling distance (distance between the spouting surface and the liquid bath surface) when the hollow fiber is wound without tension at the liquid bath outlet. Can be obtained by

[0018]

(Equation 1)

As described above, a liquid having a boiling point equal to or higher than the spinning temperature, particularly a liquid capable of forming a liquid-liquid phase-separated state from a thermoplastic polymer, is used as the hollow forming fluid, and then the liquid is discharged from the spinning hole. By guiding the compatible substance to the liquid bath after a certain idle running time, it becomes possible to form a membrane having dense pores and high water permeability. The hollow fiber-like material coming out of the liquid bath forms a porous structure (porous skeleton) by cooling and solidifying the thermoplastic polymer rich phase portion generated during liquid-liquid phase separation during cooling and solidifying. The thermoplastic polymer dilute phase (organic liquid rich phase) portion is a pore portion filled with the organic liquid.
By removing the organic liquid clogging the pores, the porous membrane disclosed in the present invention can be obtained.

The removal of the organic liquid in the film is performed by extracting and removing the organic liquid without dissolving or deteriorating the thermoplastic polymer with a volatile liquid that dissolves the organic liquid to be removed, followed by drying to remove the volatile liquid remaining in the film. It can be carried out by volatilizing and removing the liquid. Examples of such volatile liquids for organic liquid extraction include hydrocarbons such as hexane and heptane, methylene chloride,
Chlorinated hydrocarbons such as carbon tetrachloride, methyl ethyl ketone and the like can be mentioned.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
The present invention is not limited to this. The average pore size, porosity, pure water permeability, breaking strength and breaking elongation, and viscosity average molecular weight were determined by the following measurement methods. Average pore size: Measured according to the method described in ASTM: F316-86 (also known as half-dry method). The measurement was performed at 25 ° C. at a pressure increase rate of 0.01 atm using ethanol as a liquid to be used. The average pore diameter [μm] is obtained from the following equation.

[0022]

(Equation 2)

The surface tension of ethanol at 25 ° C. is 2
1.97 dynes / cm (Chemical Handbook Basic Edition, 3rd revised edition, edited by The Chemical Society of Japan, page II-82, Maruzen Co., Ltd., 19)
1984), so that the average pore diameter [μm] = 62834 / (half dry air pressure [Pa]). Porosity: The porosity was determined by the following equation.

[0024]

(Equation 3)

Here, the term “wet membrane” refers to a membrane in which the pores are filled with water but the hollow portions are not filled with water.
Specifically, a sample membrane having a length of 10 to 20 cm is immersed in ethanol to fill the hole with ethanol, and then repeatedly immersed in water 4 to 5 times to sufficiently replace the inside of the hole with water. Was shaken about five times while holding one end of the hand, and shaken about five times again while holding the hand at the other end to remove water in the hollow portion. The dried film was obtained by drying the wet film at 80 ° C. until the weight became constant after measuring the weight of the wet film. The film volume was determined from film volume [cm ³ ] = π {(outer diameter [cm] / 2) ² − (inner diameter [cm] / 2) ² } (film length [cm]). When the weight of one membrane was too small and the error in weight measurement became large, a plurality of membranes were used.

Pure water permeability: One end of a wet hollow fiber membrane having a length of about 10 cm, which has been immersed in ethanol and then immersed in pure water several times, is sealed, and an injection needle is inserted into the hollow portion at the other end. Under the injection needle, pure water at 25 ° C. is injected into the hollow portion at a pressure of 0.1 MPa, and the amount of pure water permeating from the outer surface is measured, and the pure water permeability is calculated from the following equation. Were determined.

[0027]

(Equation 4)

Here, the effective membrane length refers to the net membrane length excluding the portion where the injection needle is inserted. Breaking strength and breaking elongation: Using a tensile tester (Autograph AG-A type manufactured by Shimadzu Corporation), the distance between the hollow fibers and the chuck was 50 m.
The tensile strength at break and the elongation at break were determined by the following formulas from the load and displacement at the time of breaking at a tensile speed of 200 mm / min.

[0029]

(Equation 5)

Here, the film cross-sectional area [cm ² ] = π {(outer diameter [cm] / 2) ² − (inner diameter [cm] / 2) ² }. Elongation at break [%] = 100 (displacement at break [mm]) / 50 Viscosity average molecular weight: viscosity average molecular weight (Mv) is 135 ° C.
The intrinsic viscosity ([η]) of the decalin solution was measured by using the following formula (J. Brandrupand).
E. FIG. H. Immergut (Editors), Pol
ymer Handbook (2nd Ed.), IV
-7 pages, John Wiley & Sons, New
York, 1975).

[Η] = 6.8 × 10 ⁻⁴ × (Mv) ^0.67 The outline of the film forming flow in the example is shown in FIG.

[0032]

Example 1 High-density polyethylene (manufactured by Mitsui Chemicals, Hyzex Million 030S, viscosity average molecular weight: 450,000) 2
0 parts by weight and 80 parts by weight of a mixed organic liquid having a weight ratio of diisodecyl phthalate (DIDP) to di (2-ethylhexyl) phthalate (DOP) of 3 to 1 (DIDP / DOP = 3/1). , Twin screw extruder (TE manufactured by Toshiba Machine Co., Ltd.)
(M-35B-10 / 1V) and mixed by heating.
30 ° C.), a ring for extruding a compatible material with an outer diameter of 1.58 mm / inner diameter of 0.83 mm on the extrusion surface of the spinning hole for hollow fiber molding attached to the extrusion opening in the head (230 ° C.) at the tip of the extruder. The compatible material was extruded from the hole.

The inside of the annular hole for extruding the compatible material is set to 0.
DOP was discharged as a hollow part forming fluid from the circular hole for discharging the hollow part forming fluid of 6 mmφ, and was injected into the hollow part of the hollow fiber extrudate. The hollow fiber extruded material extruded from the spinneret into the air is placed in a 39 ° C. water bath through an air traveling distance of 1.5 cm, passed through about 2 m of water, solidified by cooling, and then tension is applied to the hollow fiber material. 16 without calling
The film was wound out of the water bath at a speed of m / min. The air travel time at this time is determined as 0.06 seconds based on the air travel distance and the winding speed.

Next, the obtained hollow fiber material was repeatedly immersed in methylene chloride at room temperature for 30 minutes five times to extract and remove DIDP and DOP in the hollow fiber material, and then dried at 50 ° C. for half a day to obtain a residue. The methylene chloride was removed by evaporation. Table 1 shows the physical properties (average pore size, porosity, yarn diameter, pure water permeability, breaking strength, breaking elongation) of the obtained membrane.

[0035]

Example 2 A film was formed in the same manner as in Example 1 except that the in-air traveling distance was 4.5 cm (the in-air traveling time was 0.1 cm).
17 seconds). Table 1 shows the physical properties (average pore size, porosity, yarn diameter, pure water permeability, breaking strength, breaking elongation) of the obtained membrane.

[0036]

Comparative Example 1 A film was formed in the same manner as in Example 1 except that the air travel distance was set to 52 cm (the air travel time was 2.0 cm).
Seconds). Various physical properties (average pore diameter, porosity, yarn diameter,
Table 1 shows pure water permeability, breaking strength, and breaking elongation.

[0037]

Comparative Example 2 A film was formed in the same manner as in Example 1 except that the hollow portion forming fluid was air (the air running time was 0.06
Seconds). Various physical properties (average pore diameter, porosity, yarn diameter,
Table 1 shows pure water permeability, breaking strength, and breaking elongation. The hollow fiber membrane obtained in Comparative Example 2 is the hollow fiber membrane obtained in another example (the hollow fiber membrane obtained in Example 1-4 and Comparative Example 1).
Unlike that, the cross-sectional shape did not exhibit a perfect circular shape, but was clearly elliptical.

[0038]

Example 3 18 parts by weight of high-density polyethylene (Suntech SH800, viscosity average molecular weight 250,000) manufactured by Asahi Kasei Corporation as polyethylene, and DIDP and DO as organic liquids
3: 1 in weight ratio with P (DIDP / DOP = 3/1)
Using 82 parts by weight of a mixture of
A film was formed in the same manner as in Example 1 except that the film thickness was changed. (Aerial running time is 0.17 seconds).

The physical properties (average pore size, porosity,
Table 1 shows the yarn diameter, pure water permeability, breaking strength, and breaking elongation.

[0040]

Example 4 A film was formed in the same manner as in Example 3 except that 19 parts by weight of polyethylene and 81 parts by weight of the organic liquid were used, and the traveling distance in the air was 6 cm (the traveling time in the air was 0.23 seconds). ). Table 1 shows the physical properties (average pore size, porosity, yarn diameter, pure water permeability, breaking strength, breaking elongation) of the obtained membrane.

[0041]

[Table 1]

[0042]

According to the present invention, it is possible to provide a method for producing a hollow fiber-like porous membrane made of a thermoplastic resin having fine pores and high water permeability, which is suitable for filtration applications such as turbidity.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a phase diagram of a thermoplastic polymer and an organic liquid.

FIG. 2 is a schematic diagram of a film forming flow in an example.

[Explanation of symbols]

 B: Compatible material at the time of spout ejection B: Cooling process in the aerial traveling section and liquid bath C: Solidified material from liquid bath 1: Polyethylene hopper 2: Polyethylene supply port DESCRIPTION OF SYMBOLS 3 ... Organic liquid supply flow path 4 ... Organic liquid supply port 5 ... Biaxial kneading extruder 6 ... Conduit 7 ... Head 8 ... Constant gear pump drive part 9 ... Constant gear pump DESCRIPTION OF SYMBOLS 10 ... Spout for hollow fiber formation 11 ... Hollow part forming fluid supply flow path 12 ... Mixed extrudate of polyethylene and organic liquid 13 ... Hollow part forming fluid 14 ... Airborne traveling part 15.・ ・ Water bath 16 ・ ・ ・ Roll 17 ・ ・ ・ Winding roll

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[Procedure amendment]

[Submission date] October 7, 1999 (1999.10.
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

As described above, a liquid having a boiling point equal to or higher than the spinning temperature as a fluid for forming a hollow portion, particularly a liquid capable of forming a liquid-liquid phase separation state with a thermoplastic polymer, is used, and the fluid is discharged from the spinning hole. By guiding the compatible substance to the liquid bath after a certain idle running time, it becomes possible to form a membrane having dense pores and high water permeability. The hollow fiber-like material coming out of the liquid bath forms a porous structure (porous skeleton) by cooling and solidifying the thermoplastic polymer rich phase portion generated during liquid-liquid phase separation during cooling and solidifying. The thermoplastic polymer dilute phase (organic liquid rich phase) portion is a pore portion filled with the organic liquid.
By removing the organic liquid that is jammed in the hole portion multi-hole film.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2 ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 13, 1999 (1999.10.
13)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA06 GA07 MA01 MC22 NA04 NA10 NA16 PA01 PB24 PC02 4F074 AA02 AA17 AA24 AA32 AA38 AA42 AA43 AA49 AA71 AA74 AA77 AA87 CB31 CB34 CB37 CC22X CC29Y DA03 BA30 BA45 BA45

Claims (2)

[Claims] 1. After melting a thermoplastic resin and an organic liquid at a high temperature, the melt is injected into a hollow portion from a spinning hole for forming a hollow fiber into a hollow portion, and the liquid is passed through the air into a hollow fiber shape. In a method in which the extrudate is extruded into a bath, cooled and solidified, and then the organic liquid is extracted and removed to obtain a hollow fiber-like porous membrane, the extrudate travels in the air for a time of 0 to 1 second (however, 0 is included). And the hollow portion forming fluid is a liquid having a boiling point not lower than the spinning temperature,
A method for melt-forming a hollow fiber-like porous film made of a thermoplastic resin. 2. The heat according to claim 1, wherein the hollow part forming fluid is a liquid having a boiling point not lower than the spinning temperature, and having a capability of liquid-liquid phase separation with a thermoplastic resin at a high temperature. A method for melt-forming a hollow fiber-shaped porous film made of a plastic resin.