JPH0739731A - Production of hollow fiber type separation membrane - Google Patents

Abstract

PURPOSE:To provide a method for stably producing a hollow fiber type separa tion membrane wherein request performance such as excellent water permeabil ity, solute permeability and roundness is sufficiently satisfied in a wet and dry type spinning method for using gas as the hollow formation material. CONSTITUTION:Spinning raw liquid is discharged downward from a mouth-piece 1 and simultaneously gas is supplied from the central part of the mouthpiece 1 to form a hollow part. Thereafter the hollow part is introduced into a coagulating bath. In the wet and dry type spinning method, the advanding direction of a hollow fiber 5 is changed by a plurality of guides in the coagulating bath.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a hollow fiber type separation membrane by a dry-wet spinning method.

[0002]

2. Description of the Related Art Conventionally, in dry-wet spinning of a hollow fiber type separation membrane, when a spinning stock solution is discharged from a double tube spinneret, at the same time, a non-coagulable liquid or solvent and a non-solvent are used as hollow forming materials from the center. A hollow portion is formed by introducing an aqueous solution or the like of the mixture. By this manufacturing method, it is possible to stably spin a dialysis hollow fiber membrane having a uniform diameter, a thin membrane thickness, and excellent performance.

However, when assembling the membrane separation module from the hollow fiber type separation membrane thus produced, the non-coagulating liquid or aqueous solution which is the hollow forming material must be removed from the hollow fiber type separation membrane. . As these methods, a method of removing the hollow forming material from the ends by centrifuging a bundle-shaped hollow fiber whose both ends are cut, and a method of washing with an organic solvent or the like after assembling the membrane separation module are taken. However, it is a very complicated and expensive method anyway. In addition, there is a case where a specific CFC that partially destroys the ozone layer is used as the organic solvent, which is a problem from the viewpoint of global environment protection. Furthermore, when used as a blood purification membrane, it is desirable that the amount of residual hollow forming material is as small as possible. However, even if various hollow forming material removing means are used in combination, it is possible to completely remove the hollow forming material. It is difficult.

From the above viewpoint, it is desired to develop a spinning method which does not use a hollow forming material such as a non-coagulating liquid or an aqueous solution. As one of the methods, a spinning method using air or gas as a hollow forming material has already been developed. Has been done.

[0005] As an example of these methods, there is a method (Japanese Patent Publication No. 1-44803) in which the spinning dope is allowed to fall freely into the coagulation bath, and when it has solidified to some extent, it is pulled laterally by a winder. It is necessary to cause the spinning dope to vertically penetrate into the coagulation bath surface only by the downward force obtained at a time, and to penetrate to a depth of 2 to 10 mm below the liquid surface. Since the air travel distance is long, the hollow fiber is vibrated. It tends to occur, and there is a problem in stability during operation such as uneven yarn diameter.

Further, a method of changing the traveling direction of the hollow fiber by a guide installed in the coagulation bath (Japanese Patent Laid-Open No. 5-6
4730), but with this method, since there is only one guide, the angle of change in the direction of travel is small, and in spinning under conditions where the hollow fiber spinning dope coagulates slowly, coagulation is insufficient and it collapses into hollow fibers. There is a problem such as occurrence of. That is,
In order to improve the water permeability and solute permeability of the hollow fiber separation membrane, spinning is effective under spinning conditions where the coagulation rate of the spinning dope is slow, but the problem that spinning is slow due to crushing makes spinning difficult. There is.

As described above, in the dry-wet spinning method using gas as the hollow forming material, a method for stably producing a membrane having satisfactory water permeability and solute permeability has not yet been obtained. is there.

[0008]

The present inventors have found that the hollow fiber membrane does not collapse even when the coagulation rate of the spinning dope is slow, and the performance requirements such as water permeability and solute permeability are wide. In order to obtain a spinning technology that can produce a hollow fiber membrane, as a result of diligent study on a method of reducing the force in the direction in which the hollow fiber is crushed from the guide, as a result of the guide, when changing the traveling direction of the hollow fiber, multiple guides are used. By increasing the change angle of the traveling direction of the hollow fiber before and after the guide using
It was found that the force in the direction of crushing the hollow fiber due to the contact pressure / friction between the guide and the hollow fiber can be reduced, and as a result, spinning can be performed under spinning conditions with a slow solidification rate. Here, since the hollow fibers are in an incompletely solidified state before and after the guide that first comes into contact with the hollow fibers, in particular, the change angle of the hollow fibers before and after the guide should be increased, specifically, 130 ° to 17 °.
When the angle is 0 °, the above effect becomes large, but when the coagulation speed is slower, the coagulation becomes incomplete even in the vicinity of the subsequent guides, so the change angles of the hollow fibers before and after those guides are also important. I knew that. The present inventors have completed the present invention as a result of further studies based on such findings.

[0009]

[Means for Solving the Problems] That is, the present invention is a dry-wet method in which a spinning dope is discharged downward from a spinneret and, at the same time, a gas is supplied from the central part of the spinneret to form a hollow part, and then the spinneret is introduced into a coagulating bath. In the spinning method, the method for producing a hollow fiber type separation membrane is characterized in that the traveling direction of the hollow fibers is changed by a plurality of guides in a coagulation bath.

Examples of the material of the guide used in the present invention include Teflon, Bakelite, and stainless steel, and those whose surface is coated with Teflon, silicon, hard chrome, or the like. It is preferably coated with chromium in a satin finish. However, the material of the guide is not limited to the above. Further, the guide may be a fixed guide or a rotating guide of a type that interlocks with the progress of the hollow fiber, but in the case of a rotating guide having a large number of rotations, the hollow fiber is converted into a coagulating liquid in order to suppress the ripple of the coagulating liquid surface. It is necessary to devise such as setting a threshold between the entry point and the first guide. The shape of the guide is not particularly limited, but in order to reduce the force in the direction of crushing the hollow fiber due to the contact pressure / friction with the hollow fiber, it is preferable that the contact portion with the hollow fiber is a smooth curved shape. . A preferable example thereof is a round bar-shaped guide or the like. Further, although the number of guides is required to be two or more, a plurality of guides are connected / fixed to form one, and the like.

In the present invention, with the plurality of guides in the coagulation bath, the entire guide does not necessarily have to be immersed in the coagulation liquid in the coagulation bath, and the contact portion between the hollow fiber and the guide is coagulated in the coagulation bath. It only needs to be immersed in the liquid. The position of the guide in the coagulation bath is not particularly limited and may be set so that the desired angle of the hollow fiber before and after each guide can be obtained depending on the coagulation speed of the spinning dope.

In the present invention, changing the traveling direction of the hollow fiber by means of the guide means that the hollow fiber traveling in the direction of the guide is brought into contact with the guide and then travels along a part of the outer periphery of the guide to achieve the desired progress. It means to be oriented. Here, the hollow fiber also includes a hollow fiber in an incompletely coagulated state after the spinning dope has entered the coagulation liquid surface in the coagulation bath and is completely coagulated to form the hollow fiber.

In the present invention, the spinneret includes all spinnerets used in the dry-wet spinning method such as so-called double tube spinneret and triple tube spinneret in the dry-wet spinning method.

In the present invention, the term "discharging downward" does not necessarily mean vertical downward, but may be any direction lower than horizontal.

In the present invention, the gas used for forming the hollow portion is not particularly limited as long as it is a gas at room temperature and atmospheric pressure, and it is air or nitrogen of the air component, oxygen, carbon dioxide, argon, or these. Examples thereof include a mixture, but air and nitrogen are preferable from the viewpoint of cost and solubility.

The spinning dope used in the present invention is, for example, a polymer, a solvent, and a non-solvent for controlling the occurrence of phase separation, which are heated and mixed to remove impurities by a filter, but are not particularly limited thereto. Not something.
As a preferable example thereof, there may be mentioned one in which a solvent and a non-solvent for controlling the occurrence of phase separation are added to cellulose acetate and the mixture is heated and mixed to remove impurities by a filter. In this case, the solvent is N-methyl 2-
Pyrrolidone, dimethylacetamide, dimethylformamide, and the like, and nonsolvents include ethylene glycol, triethylene glycol, polyethylene glycol, glycerin, and the like, but the solvent and nonsolvent are not particularly limited thereto.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The membrane performance is measured by the method of Klein et al. (Jou
rnal of Membrane Science
vol1 p371-396 1976).

Example 1 Cellulose triacetate 2
1.5 parts by weight, N-methyl-2-pyrrolidone 62.8 parts by weight, triethylene glycol 15.7 parts by weight at 170 ° C.
After heating and mixing in the solution to dissolve and vacuum degassing, the pore size is 40 μm
The mixture was filtered through a sinter filter to remove impurities to obtain a cellulose triacetate spinning stock solution. A schematic diagram of the following steps is shown in FIG. Hereinafter, description will be given with reference to FIG. The spinning dope obtained above was discharged downward from the double tube spinneret (1) heated to 160 ° C. at a rate of 1.8 ml / min. on the other hand,
Nitrogen was supplied at 3.0 ml / min from the inner side of the double tube base to form a hollow portion. The hollow fiber-shaped spinning solution was discharged from the spinneret and then run in the air for 0.5 cm (7) to guide it to the coagulation bath. At this time, the angle (6) between the surface of the coagulating liquid (4) and the hollow fiber spinning stock solution (5) was 60 degrees. The spinning stock solution (5) guided to the coagulation bath is directed by a stainless steel satin round bar submerged guide (2) coated with hard chromium having a diameter of 1.6 cm, which is installed 2 cm (9) below the surface of the coagulation liquid. And a hard chromium-coated stainless steel satin round bar dipping guide (3) installed 8 cm below the coagulation liquid surface 18 cm away from the submerged guide to change the course in the liquid surface direction, It was made to run again in the air from the surface of the coagulating liquid separated by 73 cm. At this time, the hollow fiber angle (8) before and after the submerged guide was 134 degrees, and the hollow fiber angle (10) before and after the immersion guide was 153 degrees. After that, the hollow fiber (5) was guided to a rotating roller, run in a second coagulating bath, a water-washing bath, a glycerin bath, and a drier, and finally wound into a cheese by a winder. The winding speed at this time was 75 m / min. This hollow fiber membrane was cut into a length of 30 cm, 800 bundles were collected to prepare a hollow fiber membrane module for evaluation, and the performance as a dialysis membrane was measured. The results are shown in Table 1. In addition, of the 800 hollow fibers of the hollow fiber membrane module for evaluation, the ratio of (minor diameter value) / (major diameter value) of 200 randomly drawn cross sections was measured,
The average value is shown in Table 2 as the roundness of the module.

[0019]

[Table 1]

[0020]

[Table 2]

[Example 2] As in Example 1, a hollow fiber-shaped cellulose triacetate spinning dope was introduced into a submerged guide. A schematic diagram of this step is shown in FIG. Hereinafter, description will be given with reference to FIG. Three immersion guides (3, 12, 13) were used. All were made of stainless steel satin round bar dipping guide coated with hard chrome with a diameter of 1 cm, 8 cm (11), 8 cm (16) and 2 cm below the surface of the coagulating liquid (4) 13 cm, 30 cm and 55 cm away from the submerged guide, respectively.
It was installed at (17). The hollow fiber (5) which passed through the submerged guide (2) was changed in its traveling direction by the three dipping guides, and was again run in the air from the coagulating liquid surface 60 cm away from the die. At this time, the angle (8) of the hollow fibers before and after the submerged guide was 143 degrees, and the angles (10, 14, 15) of the hollow fibers before and after the three immersion guides were 155 degrees and 167, respectively, from the side closer to the die. It was 174 degrees. The obtained hollow fiber membrane was evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

[Example 3] Cellulose triacetate 1
5.0 parts by weight, N-methyl 2-pyrrolidone 68.0 parts by weight, triethylene glycol 17.0 parts by weight at 170 ° C.
After heating and mixing in the solution to dissolve it, and vacuum degassing, the pore size is 4
A cellulose acetate spinning dope was obtained by removing impurities by filtering through a 0 μm sintered filter. 100 parts of this spinning solution
2.2 ml downward from the double tube base heated to ℃
It was discharged at a rate of / min, and nitrogen was supplied at 4.0 ml / min from the inner side of the double pipe die to form a hollow portion. The following steps were the same as in Example 1 to produce a hollow fiber membrane. The obtained hollow fiber membrane is cut into a length of 30 cm, and 800 pieces are bundled,
A hollow fiber membrane module for evaluation was prepared by washing with water, autoclave treatment, glycerin treatment, and glycerin deliquoring, and the performance as a microfiltration membrane was measured.
0 ml / m ² · hour · mmHg, albumin permeability 8
It was 0%. Further, the film pore size was measured by the bubble point method and found to be 0.5 μm.

[Comparative Example 1] In the same manner as in Example 1, a hollow fiber-shaped cellulose triacetate spinning solution was introduced into a submerged guide. A schematic diagram of this step is shown in FIG. Hereinafter, description will be given with reference to FIG. In-liquid guide (2) without using immersion guide
The hollow fiber (5) that has passed through changes the traveling direction to the liquid surface direction,
When running in the air again from the surface of the coagulated liquid 50 cm away from the submerged guide, the hollow portion was crushed and it could not be used as a dialysis membrane. The angle (8) of the hollow fibers before and after the submerged guide at this time was 118 degrees.

[Comparative Example 2] As in Comparative Example 1, a hollow fiber membrane was prepared using a cellulose triacetate spinning dope. However, the heating temperature of the double pipe base is changed from 160 ℃ to 140 ℃.
Changed to ° C. The obtained hollow fiber membrane was evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2. As a result of increasing the coagulation rate by lowering the temperature of the double pipe die, it is possible to produce a hollow fiber membrane, but the performance and roundness of the obtained membrane are reduced.

[Comparative Example 3] In the same manner as in Example 3, a hollow fiber-shaped cellulose triacetate spinning solution was introduced into a submerged guide. This step is the same as in Comparative Example 1, and its schematic diagram is shown in FIG. Hereinafter, description will be given with reference to FIG. The hollow fiber (5) that passed through the submerged guide (2) changed its traveling direction to the liquid surface direction without using the immersion guide, and when it was made to run in the air again from the coagulation liquid surface 50 cm away from the submerged guide, it was hollow. The part was crushed and it was impossible to use it as a microfiltration membrane. At this time, the angle (8) of the hollow fiber before and after the submerged guide is 1
It was 18 degrees.

[0026]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, in the dry-wet spinning method using gas as the hollow forming material, the hollow fiber type which sufficiently satisfies the required performances such as water permeability, solute permeability and roundness. It is intended to provide a method for stably producing a separation membrane. That is, according to the present invention, by using a plurality of guides, the traveling distance in the air is shortened, and the angle in the advancing direction of the hollow fibers before and after the guides is increased to reduce the load force of the hollow fibers by the guides and the solidification speed. The hollow fiber can be stably spun under slow conditions. Also, as a result, it has excellent performance such as water permeability and solute permeability.
Further, it is possible to provide a hollow fiber type separation membrane having a small roundness of the yarn diameter and a high roundness.

[Brief description of drawings]

FIG. 1 is a process schematic diagram of an example of the manufacturing method of the present invention in Examples 1 and 2 (when two round bar guides are used).

FIG. 2 is a process schematic diagram of an example of the manufacturing method of the present invention in Example 3 (when four round bar guides are used).

[FIG. 3] Comparative Examples 1 to 3 (when one round bar guide is used)
FIG. 6 is a process schematic diagram of an example of the manufacturing method of FIG.

[Explanation of symbols] 1 mouthpiece 2 satin round bar submerged guide 3 satin round bar immersion guide 4 coagulating liquid 5 hollow fiber 6 angle between hollow fiber and coagulating liquid surface 7 air travel distance of hollow fiber 8 hollow before and after liquid guide Thread angle 9 Depth of submerged guide 10 Angle of hollow fiber before and after dipping guide 11 Depth of dipping guide 12 Sashimi round bar second dipping guide 13 Satin round bar third dipping guide 14 Hollow fiber before and after second dipping guide Angle 15 Hollow fiber angle before and after the 3rd immersion guide 16 Depth of the 2nd immersion guide 17 Depth of the 3rd immersion guide

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[Procedure amendment]

[Submission date] August 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

[Table 1] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 4, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

Example 1 Cellulose triacetate 2
1.5 parts by weight, N-methyl-2-pyrrolidone 62.8 parts by weight, triethylene glycol 15.7 parts by weight at 170 ° C.
After heating and mixing in the solution to dissolve and vacuum degassing, the pore size is 40 μm
The mixture was filtered through a sinter filter to remove impurities to obtain a cellulose triacetate spinning stock solution. A schematic diagram of the following steps is shown in FIG. Hereinafter, description will be given with reference to FIG. The spinning dope obtained above was discharged downward from the double tube spinneret (1) heated to 160 ° C. at a rate of 1.8 ml / min. on the other hand,
Nitrogen was supplied at 3.0 ml / min from the inner side of the double tube base to form a hollow portion. The hollow fiber-shaped spinning solution was discharged from the spinneret and then run in the air for 0.5 cm (7) to guide it to the coagulation bath. At this time, the angle (6) between the surface of the coagulating liquid (4) and the hollow fiber spinning stock solution (5) was 60 degrees. The spinning stock solution (5) guided to the coagulation bath is directed by a stainless steel satin round bar submerged guide (2) coated with hard chromium having a diameter of 1.6 cm, which is installed 2 cm (9) below the surface of the coagulation liquid. , And about 18 cm at a horizontal distance from the submerged guide.
Separated, the course is changed in the liquid level direction by a stainless steel satin round bar dipping guide (3) coated with hard chrome with a diameter of 1 cm installed at 6.4 cm (11) below the coagulating liquid level,
It was made to run again in the air from the surface of the coagulating liquid which was about 47 cm away from the mouthpiece. At this time, the hollow fiber angle (8) before and after the submerged guide was 134 degrees, and the hollow fiber angle (10) before and after the immersion guide was 153 degrees. After that, the hollow fiber (5) was guided to a rotating roller, run in a second coagulating bath, a water-washing bath, a glycerin bath, and a drier, and finally wound into a cheese by a winder. The winding speed at this time was 75 m / min. This hollow fiber membrane is cut into a length of 30 cm,
A hollow fiber membrane module for evaluation was prepared by bundling 0 pieces, and the performance as a dialysis membrane was measured. The results are shown in Table 1.
In addition, the hollow fiber 800 of the hollow fiber membrane module for evaluation described above.
The (minor axis value) / (major axis value) ratio of 200 cross-sections randomly drawn out of the books was measured, and the average value thereof is shown in Table 2 as the roundness of the module.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

[Example 2] As in Example 1, a hollow fiber-shaped cellulose triacetate spinning dope was introduced into a submerged guide. A schematic diagram of this step is shown in FIG. Hereinafter, description will be given with reference to FIG. Three dipping guides (3, 12, 13)
Using. All are made of stainless steel satin round bar dipping guide coated with hard chrome with a diameter of 1 cm. Horizontal distance from the submerged guide is about 13 cm, about 30 cm, about 55 c.
8 cm (11), 8 cm (1) below the surface of the coagulating liquid (4) at a distance of m
6) It was installed at 2 cm (17). The hollow fiber (5) having passed through the submerged guide (2) was changed in its traveling direction by the three dipping guides, and was again run through the air from the coagulating liquid surface about 62 cm away from the die. At this time, the angle (8) of the hollow fibers before and after the submerged guide was 143 degrees, and the angles (10, 14, 15) of the hollow fibers before and after the three immersion guides were 155 degrees and 167, respectively, from the side closer to the die. It was 174 degrees.
The obtained hollow fiber membrane was evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[Comparative Example 1] In the same manner as in Example 1, a hollow fiber-shaped cellulose triacetate spinning solution was introduced into a submerged guide. A schematic diagram of this step is shown in FIG. Hereinafter, description will be given with reference to FIG. The hollow fiber (5) that passed through the submerged guide (2) changed its traveling direction to the liquid surface direction without using the immersion guide, and was run again in the air from the coagulating liquid surface about 57 cm away from the mouthpiece. Was crushed and could not be used as a dialysis membrane. The angle (8) of the hollow fibers before and after the submerged guide at this time was 118 degrees.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[Comparative Example 3] In the same manner as in Example 3, a hollow fiber-shaped cellulose triacetate spinning solution was introduced into a submerged guide. This step is the same as in Comparative Example 1, and its schematic diagram is shown in FIG. Hereinafter, description will be given with reference to FIG. The hollow fiber (5) that passed through the submerged guide (2) changed its traveling direction to the liquid surface direction without using the immersion guide, and was run again in the air from the coagulating liquid surface about 57 cm away from the mouthpiece. Was crushed and could not be used as a microfiltration membrane. The angle (8) of the hollow fibers before and after the submerged guide at this time was 118 degrees.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a process schematic diagram of an example of the manufacturing method of the present invention in Examples 1 and 3 (when two round bar guides are used).

FIG. 2 is a process schematic diagram of an example of the manufacturing method of the present invention in Example 2 (when four round bar guides are used).

[FIG. 3] Comparative Examples 1 to 3 (when one round bar guide is used)
FIG. 6 is a process schematic diagram of an example of the manufacturing method of FIG.

[Explanation of symbols] 1 mouthpiece 2 satin round bar submerged guide 3 satin round bar immersion guide 4 coagulating liquid 5 hollow fiber 6 angle between hollow fiber and coagulating liquid surface 7 air travel distance of hollow fiber 8 hollow before and after liquid guide Thread angle 9 Depth of submerged guide 10 Angle of hollow fiber before and after dipping guide 11 Depth of dipping guide 12 Sashimi round bar second dipping guide 13 Satin round bar third dipping guide 14 Hollow fiber before and after second dipping guide Angle 15 Hollow fiber angle before and after the 3rd immersion guide 16 Depth of the 2nd immersion guide 17 Depth of the 3rd immersion guide

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location D01F 6/00 B 7199-3B

Claims (1)

[Claims] 1. A dry-wet spinning method in which a spinning dope is discharged downward from a spinneret and at the same time a gas is supplied from the central part of the spinneret to form a hollow portion, and then the spinning solution is introduced into a coagulating bath. A method for producing a hollow fiber type separation membrane, characterized in that the traveling direction of the hollow fiber is changed by a guide.