JPH05317664A - Porous hollow fiber membrane - Google Patents

Abstract

PURPOSE:To provide a low cost porous hollow fiber membrane capable of easily producing by allowing a separation membrane composed of a hydrophobic resin excellent in physical and chemical properties is to contain a hydrophilic PVA based resin excellent in wettability, protein non-adsorptivity, contamination resistance and adhesivity. CONSTITUTION:The porous hollow fiber membrane is formed by using a raw solution composed of a hydrophobic resin, a pore forming agent and a common solvent for them and using a solution containing 1-20wt.% polyvinylalcohol based resin as an internal coagulating solution and/or external coagulating solution and the porous hollow fiber membrane contains 0.5-10wt.% polyvinylalcohol based resin in the membrane.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a porous hollow fiber membrane containing a polyvinyl alcohol (hereinafter abbreviated as PVA) type resin in the membrane, particularly a porous hollow fiber excellent in protein non-adsorption and stain resistance. It is about membranes.

[0002]

2. Description of the Related Art In recent years, a technique using a separation membrane having selective permeability has been remarkably developed and has been put to practical use in medical applications, industrial applications and the like. As a resin for such a separation membrane, a resin of cellulose type, polyimide type, polyamide type, polyacrylonitrile type, PVA type, polysulfone type or the like has been conventionally used. Among them, polysulfone-based hydrophobic resins are excellent in physicochemical properties such as heat resistance and chemical resistance, and have been widely used for various purposes recently.

However, the permeation performance of a separation membrane made of a hydrophobic resin is remarkably reduced when dried, so that the permeation performance is prevented from being lowered by applying a hydrophilizing treatment in which the membrane is impregnated with glycerin or a surfactant. There is. When the dried separation membrane is reused, it is subjected to a moistening treatment with alcohol or a surfactant. Therefore, there are drawbacks that the cost is increased as compared with the separation membrane made of the hydrophilic resin, the handling is troublesome, and the adsorption of proteins and the like, the contamination of the membrane and the clogging are likely to occur.

These drawbacks are largely due to the hydrophobicity of the membrane material. Attempts have been made to solve this drawback by imparting hydrophilicity to the hydrophobic separation membrane, and various problems such as those shown below have been made. A method has been proposed.

(1) Mixing stock solution method A method of forming a film using a stock solution in which a hydrophilic resin such as polyvinylpyrrolidone is mixed, and leaving the hydrophilic resin in the film.
(Unexamined-Japanese-Patent No. 58-104940, 60-9700).
1, gazette 61-93801 gazette, gazette 62-382.
No. 05, No. 63-99325, and Japanese Patent Laid-Open No. 2-1.
No. 15028, etc.)

(2) Membrane surface modification method A method of introducing a hydrophilic group to the membrane surface or grafting a hydrophilic resin onto the membrane surface by subjecting the membrane to physical or chemical treatment (Japanese Patent Laid-Open No. 196322/1984). 60-87803, 62-45303, etc.) (3) Impregnation method After film formation, the film is immersed in a solution of hydrophilic resin to leave the hydrophilic resin in the film (JP-A-61-61). -268032 gazette, the same 61-268032 gazette, the same 63-2291.
08 publication)

[0007]

However, among the methods of (1), the methods disclosed in JP-A-58-104940 and 60-
97001, 61-93801, 62.
-38205 and 63-99325,
Polysulfone, polyamide, polyvinylidene fluoride and other hydrophobic resins such as polyvinylidene fluoride is used to form a film using a stock solution, a method of leaving polyvinylpyrrolidone in the film is described, polyvinylpyrrolidone is not hydrophilic. It is excellent, but it cannot form an ion complex with other substances or easily adsorbs other substances, so it cannot be applied to the formation of ion complexes or applications involving substances that are adsorbed, in terms of adsorptivity, fouling property, peeling property, etc. There is a drawback.

In the above method, polyvinylpyrrolidone having excellent compatibility with the hydrophobic resin can be used as the hydrophilic resin to form a film for the first time, and other hydrophilic resins having poor compatibility with the hydrophobic resin can be used. It is not applicable to the organic resin.

Japanese Unexamined Patent Publication (Kokai) No. 2-115028 discloses a polysulfone membrane containing a PVA-based resin which is excellent in stain resistance and protein non-adsorption and a method for producing the same.
Since the VA resin has poor compatibility with polysulfone, it is necessary to adopt a special production method such as adding a large amount of electrolyte to the membrane-forming stock solution to increase the compatibility with polysulfone or forming a membrane in an ice bath. There is an unavoidable increase in cost. Further, since it is a special production method, only a membrane having low permeability is obtained.

In the method (2), the chemical that reacts with the membrane material is often a dangerous substance, requires careful handling, and may cause decomposition of the membrane material or deterioration of the membrane during the reaction. In addition, the reaction is difficult to control and is not suitable for industrial scale implementation. In the method (3), it is difficult to impregnate a hydrophilic polymer into a membrane having a very small pore size, such as a reverse osmosis membrane, a dialysis membrane or an ultrafiltration membrane. Therefore, the applicable separation membrane is limited to a membrane having a relatively large pore size, such as a microfiltration membrane. In addition, it is difficult to control the pore size because it is difficult to stably manufacture the membrane, and it is not suitable for implementation on an industrial scale.

Therefore, an object of the present invention is to provide a separation membrane made of a hydrophobic resin excellent in physicochemical performance with a water wettability,
Hydrophilic P with excellent protein non-adsorption, stain resistance, and peelability
An object of the present invention is to provide a porous hollow fiber membrane containing a VA resin, which is easy to manufacture and inexpensive.

[0012]

Means for Solving the Problems As a result of a thorough study of the above-mentioned conventional method for imparting hydrophilicity to a separation membrane made of a hydrophobic resin, the present inventors have found that in a hollow hollow fiber membrane, a hollow fiber membrane is used. When an internal coagulation liquid and / or an external coagulation liquid containing a PVA-based resin is used in the production of, the PVA-based resin contained in the coagulation liquid at the coagulation stage diffuses inside the film. Surprisingly, the diffused PVA-based resin is not completely extracted even by the washing in the subsequent step, and remains on the inside of the membrane and the inner and outer surfaces of the membrane, and the influence of the interaction between the hydrophobic resin and the PVA-based resin is almost all. Since it is not present, it was found that it can be combined with any hydrophobic resin, and as a result of further intensive studies, the present invention has been achieved.

That is, the present invention uses a stock solution of a hydrophobic resin, a pore-forming agent and their common solvent, and uses 0.1 to 20% by weight of a polyvinyl alcohol resin as an internal coagulating liquid and / or an external coagulating liquid. A porous hollow fiber membrane produced by using a solution containing the polyvinyl alcohol-based resin in an amount of 0.5 to 1
The porous hollow fiber membrane is characterized by containing 0% by weight.

The porous hollow fiber membrane of the present invention is a membrane in the category of microfiltration and ultrafiltration, and has a large number of fine pores having an average pore diameter of 100 Å or more, usually 500 Å or more, on at least one surface of the membrane. And the water permeability is 100 l / (m ↑ 2 ・ hr ・ Kg / cm ↑ 2) or more, usually 50
Means a film of 0 l / (m ↑ 2 · hr / Kg) or more. The film structure is a film having a known structure such as sponge or finger-like. Usually, a film having an asymmetric structure having a dense layer on at least one surface of the film is preferably used.

The porous hollow fiber membrane contains 0.5 to 10% by weight of a PVA-based resin on the inside and outside surfaces of the membrane (hereinafter referred to as the inside of the membrane). If the content of the PVA-based resin is less than 0.5% by weight, sufficient hydrophilicity cannot be obtained, and if it exceeds 10% by weight, the water permeability is lowered and the characteristics of the hydrophobic resin constituting the membrane are deteriorated. Usually, the PVA resin content is 1.0 to
It is 7.0% by weight, preferably 2.5 to 5.0% by weight.

The method for producing a porous hollow fiber membrane of the present invention uses a solution containing a PVA-based resin as an internal coagulation liquid and / or an external coagulation liquid (hereinafter referred to as a coagulation liquid), and PVA is used during coagulation.
Since the PVA-based resin is diffused inside the film and the PVA-based resin is left inside the film or on the inner and outer surfaces, any resin can be used as the hydrophobic resin forming the stock solution. Further, as a stock solution, a conventionally known technique can be directly adopted. Conventionally, an undiluted solution comprising a hydrophobic resin, a solvent and a pore forming agent has been generally used, and the above undiluted solution can also be used in the present invention.

As the hydrophobic resin, a conventionally known film-forming resin can be used. Examples of such hydrophobic resin include polysulfone, polyether sulfone, polyamide, polyimide, polyacrylonitrile, polystyrene, polyvinylidene fluoride, polyvinyl chloride, polymethyl methacrylate and the like.

The pore-forming agent is used for controlling the pore size of the membrane, and the kind and the amount of addition are different depending on the membrane material and the solvent. For example, water, alcohols, glycols, esters, glycerin, organic acids, Polyethylene glycol,
Non-solvents, poor solvents, swelling agents and the like of hydrophobic resins such as inorganic salts and the like or a mixture of two or more kinds thereof, and inorganic fine particles such as ZnO and silica are used. The solvent is not particularly limited as long as it can dissolve the hydrophobic resin and the pore-forming agent and can dissolve the PVA-based resin.

The coagulating liquid is, for example, a nonsolvent or a poor solvent alone or a mixed solution of two or more kinds with respect to hydrophobic resins such as water, alcohols, glycols, esters and glycerin, or a mixture of these with a solvent. A system in which a PVA resin is added to the solution is used.

Examples of the PVA-based resin added to the coagulation liquid include PVA, copolymers of vinyl alcohol and vinyl compounds such as vinyl acetate, styrene and itaconic acid, and graft polymers. Furthermore, by using a PVA-based resin having a charged group, it is possible to impart not only hydrophilicity but also ion exchangeability and ion selective permeability. The average molecular weight of the PVA resin is preferably 10,000 or more. When the average molecular weight is less than 10,000, the diffusion rate is high and the particles are relatively uniformly dispersed in the film, but they are easily extracted by washing, and it is difficult to increase the residual amount in the film. Further, if a high molecular weight PVA-based resin is used, the diffusion rate becomes slow and it is likely to remain in the film, but the viscosity of the coagulating liquid increases so much that it may be difficult to form the film, or the cleaning may take a long time.

Therefore, PVA added to the coagulating liquid
The molecular weight of the system resin is appropriately determined depending on the type of hydrophobic resin and the membrane structure. Normally, a membrane with a small pore size such as an ultrafiltration membrane has a relatively low molecular weight, and a pore size such as a microfiltration membrane. A relatively high molecular weight film is used. Further, two or more kinds of PVA-based resins having different average molecular weights can be mixed and used.

When the PVA-based resin is added to the internal coagulation liquid, it is easy to control the concentration of the PVA-based resin in the coagulation liquid, and the PVA-based resin can be efficiently left in the film even with a small addition amount. However, since the viscosity of the solution may affect the spinnability, the amount of PVA-based resin that can be added may be limited. On the contrary, when the PVA-based resin is added to the external coagulation liquid, the amount of the PVA-based resin that can be added is arbitrary. It is also possible to localize the PVA-based resin on the inner surface side by adding the PVA-based resin to the internal coagulating liquid and on the outer surface side by adding the PVA-based resin to the external coagulating liquid. Above P
The VA-based resin can be localized by adjusting the molecular weight and the addition amount of the PVA-based resin. Whether the PVA-based resin is added to the internal coagulation liquid or the external coagulation liquid, or both of them can be selected in consideration of the spinning method, process control, cost, film characteristics and the like.

The amount of PVA resin added to the coagulation liquid is 0.1.
-20% by weight, usually 1-10% by weight is preferred. PVA
If the amount of the system resin added is less than 0.1% by weight, a sufficient hydrophilic effect cannot be imparted to the hydrophobic film. If the amount of PVA-based resin added exceeds 20% by weight, it is difficult to wash and remove the excess PVA-based resin, and it is uneconomical.

The porous hollow fiber membrane of the present invention can be formed by a known method such as a dry-wet method or a wet method. A dry-wet method is usually used to obtain a membrane having excellent permeability. In the wet method, the film discharged from the nozzle is directly immersed in the external coagulating liquid. On the other hand, in the dry-wet method, the film discharged from the nozzle is passed through gas (generally in air) and then immersed in an external coagulating liquid. In the dry-wet method, the distance between the discharge surface of the nozzle and the surface of the external coagulation liquid, that is, the running distance in air (called dry zone length) is preferably 0.1 to 100 cm, and usually 1 to 50 cm. If the dry zone length is less than 0.1 cm, the tip of the nozzle may come into contact with the external coagulating liquid due to slight waviness of the external coagulating liquid. On the other hand, the dry zone length is 100
If it exceeds 10 cm, in the multi-hole spinning, the hollow fiber membranes stick to each other due to the shaking of the yarn.

When the dry zone is humidified to a relative humidity of 80% or more in the dry-wet method, a large number of large pores having a large pore size are easily formed on the outer surface of the membrane by promoting microphase separation and mild solidification due to moisture in the air. can do. This effect is also recognized when the dry zone length is as short as 0.1 cm.

The hollow fiber membrane coagulated with the external coagulation liquid is then washed with water or treated with warm water at 40 to 70 ° C. or less to extract and remove the solvent, non-solvent, swelling agent and excess PVA-based resin contained in the membrane. To be done. When extracting the inorganic particles such as Zno and silica contained in the film to form the micropores, it is necessary to perform a special extraction treatment. Excess PVA-based resin is extracted and removed from the membrane by these treatments. However, even with the above treatment, the PVA-based resin cannot be completely extracted and remains in the film. In the present invention, PV remaining in the film
By controlling the amount of A-based resin, hydrophilicity is imparted to the hydrophobic film. It is speculated that the reason why the PVA-based resin remains in the film is that the PVA-based resin diffuses into the film during the coagulation stage and is incorporated into the film by coagulation and immobilized.

Next, if necessary, hot water treatment at 80 ° C. or higher is performed. Performing hot water treatment in advance improves washing efficiency and improves stability to heat. For example, when performing high-pressure steam sterilization treatment, it is possible to prevent shrinkage of the hollow fiber membranes, etc. It is effective for application. Further, if necessary, in order to prevent the PVA-based resin remaining in the film during use from being eluted, the PVA-based resin in the film may be insolubilized by subjecting the film to a physical or chemical treatment. For the insolubilization treatment, known techniques such as dry heat treatment at 100 ° C. or higher, acetalization with aldehyde, and UV irradiation are used.

The hollow fiber membrane which has undergone the above-mentioned treatment is wound on a frame or the like and dried. After the dried hollow fiber membranes are bundled and housed in the housing, both ends thereof are fixed to the housing with a thermosetting resin such as polyurethane resin to be modularized.

[0029]

EXAMPLES Next, the porous hollow fiber membranes of the present invention will be described in more detail by way of examples. The water permeability is an effective length of 15c.
A module of m was prepared, and the dry film was subjected to a water pressure of 1 Kg / cm ↑ 2 from the inside of the film with pure water at 25 ° C., and the amount of pure water that had permeated the film was measured. It is a value obtained by calculating the amount of water permeation, and the fractional particle size shows the size of particles that prevent 90% or more. The residual amount of the PVA-based resin in the film was calculated by extracting the hydrophobic resin with a solvent and then measuring the weight of the remaining undissolved substance.

Example 1 Polysulfone (UDEL P-1700 manufactured by Amoco) 2
0% by weight, polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd.
# 600, molecular weight 600) 36% by weight and dimethylformamide 44% by weight were mixed and heated and stirred to prepare a uniform transparent stock solution. This stock solution exhibited the property of causing phase separation at 33 ° C or higher. The above stock solution was allowed to stand at 28 ° C. for 16 hours to be defoamed, then, from a double annular nozzle having an outer diameter of 1.6 mm and an inner diameter of 0.8 mm, 3% by weight of polyvinyl alcohol (PVA-217 manufactured by Kuraray) and dimethylformamide. 8
With an internal coagulating liquid of 0% by weight and 17% by weight of water at 28 ° C, extruded into air adjusted to 50 ° C and a relative humidity of 100%, after running in air for 10 cm, in an external coagulating liquid consisting of water at 50 ° C It was dipped in and solidified.

Then, dimethylformamide, polyethylene glycol and excess PVA in the membrane were extracted by washing with hot water at 50 ° C. and washing with hot water at 95 ° C., and then wound on a frame. Then, the membrane is immersed in a solution of 0.2% by weight of glutaraldehyde and 2% by weight of sulfuric acid at 60 ° C. for 60 minutes to crosslink the PVA, and then glutaraldehyde and sulfuric acid are removed by washing, and then 50 ° C. To obtain a hollow fiber membrane having an outer diameter of 1.3 mm and an inner diameter of 0.8 mm.

This hollow fiber membrane has a large number of micropores of about 0.1 to 2 μm on the outer surface from the scanning electron microscope photograph (hereinafter referred to as SEM photograph) of 5000 times the outer surface of the membrane shown in FIG. Present and 5000 of the inner surface of the membrane shown in FIG.
Approximately 0.05-0.1μ on the inner surface from a double SEM photograph
There are a large number of micropores. 3 is a cross section of the central part of the film, FIG. 4 is a cross section of the outer surface side of the film, and FIG. 5 is a 5000 × SEM photograph showing a cross section of the inner surface side of the film. 3 to 5
As a result, the cross-sectional structure of the film was a relatively dense structure on the outer surface side and the inner surface side, and an asymmetric sponge structure with a rough central portion.

The water permeability of this hollow fiber membrane in the dry state is 35.
001 / (m ↑ 2 · hr · Kg / cm ↑ 2), and the fractional particle diameter was 0.1μ. The residual amount of PV resin in the hollow fiber membrane was 3.8% by weight. This membrane is dry and moisturizing 5
No change in water permeability was observed even after repeated times, and permanent hydrophilicity was observed.

Comparative Example 1 Polysulfone (UDEL P-1700 manufactured by Amoco) 2
Only 0% by weight was dissolved in dimethylformamide, and 5% by weight of polyvinyl alcohol (PVA-217 manufactured by Kuraray Co., Ltd.) was added to this solution, and the solution became cloudy and completely separated into phases. No film could be formed with this stock solution.

Comparative Example 2 The same stock solution as in Example 1 was used with an outer diameter of 1.6 mm and an inner diameter of 0.8 mm.
From the double annular nozzle of No. 2, extruded into the air adjusted to 50 ° C. and relative humidity of 100% together with the internal coagulation liquid of 28 ° C. consisting of 80% by weight of dimethylformamide and 20% by weight of water, and after running in air for 10 cm, 50 It was solidified by immersing it in an external coagulating liquid consisting of water at ℃. Then, dimethylformamide and polyethylene glycol are extracted and removed by washing with warm water at 50 ° C. and washing with hot water at 95 ° C., soaked in a solution of sodium lauryl sulfate 0.1% by weight, wound on a frame, and warmed at 50 ° C. Dried to an outer diameter of 1.3 mm,
A hollow fiber membrane having an inner diameter of 0.8 mm was obtained.

This membrane was moistened with an aqueous solution of 0.1% by weight of sodium lauryl sulfate, washed with water, and then the water permeability was measured to find that it was 3600 l / (m ↑ 2 · hr · Kg / cm ↑).
2), and the fractional particle size was 0.1 μm. However, when the film was dried and then measured again, the water permeability was almost zero.

Example 2 Using the hollow fiber membranes obtained in Example 1 and Comparative Example 2, an internal pressure type lab module having an effective length of 30 cm and an effective membrane area of 500 cm ↑ 2 was produced. This module was used to carry out total internal pressure filtration of tap water, and the water permeability was 300 l / (m ↑ 2 ・ h
r ・ Kg / cm ↑ 2), transmembrane pressure difference 1k
The permeated liquid was backwashed for 1 minute at g / cm ↑ 2, and the water permeability recovery property was examined. As a result of repeating the above test three times, Comparative Example 2
The module using the hollow fiber membrane has a water permeability of 21%, 1
Whereas only 5% and 8% were recovered, the module using the hollow fiber membrane of Example 1 had a water permeability of 88%, 85%,
It was recovered to 87%, and it was confirmed that the hollow fiber membrane of Example 1 had remarkably excellent releasability by backwashing with the permeated liquid.

Next, the hollow fiber membranes obtained in Example 1 and Comparative Example 2 were placed in a 0.1% by weight solution of γ-globulin at 25 ° C. for 24 hours.
As a result of examining the adsorptivity by immersion for a time, the γ-globulin adsorption rate was 35% in the hollow fiber membrane of Comparative Example 2, whereas the hollow fiber membrane of Example 1 was only 1.5%. It was confirmed that the hollow fiber membrane of Example 1 was excellent in protein non-adsorption.

Example 3 Polysulfone (UDEL P-1800 manufactured by Amoco) 2
0% by weight, polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd.
# 600, molecular weight 600) 10% by weight, dimethylformamide 58.5% by weight, amorphous silica (manufactured by Tokuyama Soda Co., Ltd.)
Fineseal B) 11.5 wt% was mixed to prepare a white stock solution in which amorphous silica was uniformly dispersed.

This stock solution was heated at 30 ° C. and had an outer diameter of 2.6 mm,
30 ° C composed of 6% by weight of polyvinyl alcohol (PVA-217 manufactured by Kuraray), 75% by weight of dimethylformamide and 19% by weight of water from a double annular nozzle having an inner diameter of 1.5 mm.
Extruded into the air adjusted to 40 ° C and 100% relative humidity together with the internal coagulation liquid of 3 and after running in the air for 10 cm, 3
It was immersed in an external coagulating liquid consisting of water at 0 ° C. to coagulate.

Next, dimethylformamide, polyethylene glycol and excess PVA resin were extracted and removed by washing with warm water at 50 ° C. and washing with hot water at 95 ° C.
It was rolled up on the frame. Further, after cross-linking the PVA-based resin in the same manner as in Example 1, the sulfuric acid and glutaraldehyde were washed and removed, and then treated with a 15 wt% sodium hydroxide aqueous solution heated at 90 ° C. for 2 hours. Amorphous silica is extracted, sodium hydroxide is removed by washing, and dried with warm air at 50 ° C to give an outer diameter of 1.9 mm and an inner diameter of 1.2 m.
m hollow fiber membrane was obtained.

The water permeability of this hollow fiber membrane is 9500 l / (m
↑ 2 ・ hr ・ Kg / cm ↑ 2), fraction particle size is 0.3μ
Met. The residual amount of PVA in the hollow fiber membrane was 4.8% by weight. This membrane showed no change in water permeability even after repeated drying and moistening, and showed permanent hydrophilicity.

Example 4 Polysulfone (UDEL P-1700 manufactured by Amoco) 1
8% by weight, polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd.
# 600, molecular weight 600) 36% by weight and dimethylformamide 46% by weight were mixed and dissolved to obtain a stock solution. This stock solution exhibited the property of causing phase separation at 37 ° C or higher. 32
This undiluted solution kept at ℃, outside diameter 1.0mm, inside diameter 0.5m
From a double annular nozzle of m, polyvinyl alcohol (PVA-205 manufactured by Kuraray) 3% by weight, dimethylformamide 81% by weight, and water 16% by weight together with an internal coagulating liquid heated to 32 ° C, 50 ° C, relative humidity 100. Extruded into the air adjusted to 50%, and after running in the air for 10 cm, 50
It was dipped and solidified in an external coagulating liquid consisting of water at ℃.

Then, dimethylformamide, polyethylene glycol and excess PVA-based resin were extracted and removed by washing with warm water at 50 ° C. and washing with hot water at 95 ° C. and wound on a frame. Then, after cross-linking the PVA-based resin in the same manner as in Example 1, the glutaraldehyde and sulfuric acid were washed and removed, and dried with warm air at 50 ° C. to form a hollow fiber membrane having an outer diameter of 0.45 mm and an inner diameter of 0.32 mm. Got The water permeability of this membrane is 7,000 l / (m ↑ 2 ・ hr ・ Kg / cm ↑ 2
), And the fractional particle size was 0.2 μm. The residual amount of PVA in the hollow fiber membrane was 3.4% by weight. This membrane showed no change in water permeability due to repeated drying and moistening, and permanent hydrophilicity.

Next, in vitro evaluation was performed using ACD-added bovine blood using the above hollow fiber membrane. As a result, excellent filtration performance was obtained with a water permeability: QF max = 40 ml / min (blood flow rate: QB = 100 ml / min) and a blood protein permeability of 95% or more.

Example 5 Polysulfone (UDEL P-3500 manufactured by Amoco) 1
8% by weight, polyethylene glycol (manufactured by Sanyo Kasei Co., Ltd.
# 600, molecular weight 600) 34% by weight, water 0.1% by weight
Was mixed and dissolved with dimethylformamide to obtain a stock solution. This stock solution showed a property of phase separation at 21 ° C. or higher. 18 ° C
This undiluted solution kept at 1.0 mm outer diameter, 0.5 mm inner diameter
Extruded into the air adjusted to 40 ° C and relative humidity of 100% together with the internal coagulating liquid of 75% by weight of dimethylformamide and 25% by weight of water from the double annular nozzle of 40 ° C. It was immersed and solidified in an external coagulating liquid consisting of a 12% by weight aqueous solution of polyvinyl alcohol (PVA-205).

Next, dimethylformamide, polyethylene glycol and excess PVA-based resin were extracted and removed by washing with warm water at 50 ° C. and washing with hot water at 95 ° C. and wound on a frame. Then, after cross-linking the PVA-based resin in the same manner as in Example 1, glutaraldehyde and sulfuric acid were washed and removed, and dried with warm air at 50 ° C. to obtain a hollow fiber membrane having an outer diameter of 0.8 mm and an inner diameter of 0.5 mm. Got The water permeability of this membrane in the dry state is 1600 l / (m ↑ 2 · hr · Kg / cm ↑ 2),
The fractional particle size was 0.02μ. In addition, P in the hollow fiber membrane
The residual amount of VA was 2.6% by weight, no change in water permeability was observed due to repeated drying and moistening, and permanent hydrophilicity was observed.

Example 6 The composition of the internal coagulation liquid was anion-modified PVA (Kuraray KL
-506) A hollow fiber membrane was produced in the same manner as in Example 1 except that 3% by weight, 79% by weight of dimethylformamide, and 18% by weight of water were used. The water permeability of the obtained hollow fiber membrane in the dry state is 2800 l / (m ↑ 2 ・ hr ・ Kg / cm ↑ 2
), And the fractional particle size was 0.08μ. The residual amount of PVA in the hollow fiber membrane was 2.8% by weight, and the amount of ionic groups of anion groups was 0.1 meq. This membrane showed no change in water permeability due to repeated drying and moistening, and permanent hydrophilicity.

Example 7 20% by weight of polyimide (2080D manufactured by Upjohn) and 20% by weight of ethylene glycol were mixed and dissolved in dimethylformamide to obtain a stock solution. This stock solution was kept at 30 ° C., and polyvinyl alcohol (PVA-20 manufactured by Kuraray Co., Ltd.
5) 30 ° C consisting of 4% by weight, dimethylformamide 70% by weight, ethylene glycol 6% by weight, water 20% by weight
Was extruded into the air of 50 ° C. and a relative humidity of 100% together with the internal coagulating liquid of Example 1, and after running in the air for 10 cm, it was immersed in an external coagulating liquid of water at 50 ° C. to coagulate.

Then, dimethylformamide, polyethylene glycol and excess PVA were extracted by washing with warm water at 50 ° C. and washing with hot water at 95 ° C. and wound on a frame. Then, the PVA was crosslinked by immersing it in a solution of glutaraldehyde (0.2% by weight) and sulfuric acid (2% by weight) at 60 ° C for 60 minutes to wash and remove the glutaraldehyde and sulfuric acid, and then with warm air at 50 ° C. After drying, a hollow fiber membrane having an outer diameter of 1.3 mm and an inner diameter of 0.8 mm was obtained. The water permeability of this membrane is 1300 l / (m ↑ 2 · hr · Kg / cm ↑ 2),
The fractional particle size was 0.02μ. In addition, P in the hollow fiber membrane
The residual amount of VA was 3.5% by weight, no change in water permeability was observed due to repeated drying and moistening, and permanent hydrophilicity was observed.

[0051]

Industrial Applicability As described above, the porous hollow fiber membrane of the present invention contains PVA in a hydrophobic resin-based membrane by a slight operation using a coagulating liquid containing a specific amount of PVA-based resin. It is possible to provide 0.5 to 10% by weight of the resin, and it is possible to provide a porous hollow fiber membrane which is excellent in hydrophilicity and protein non-adsorbability in addition to the properties of the hydrophobic membrane. Therefore, the filtration performance can be easily recovered by backwashing or the like, so that stable filtration performance can be obtained.

Since the PVA-based resin is also excellent in blood compatibility, when the porous hollow fiber membrane of the present invention is applied to medical purposes, protein attachment can be suppressed and stable filtration performance can be obtained. The antithrombotic action can suppress the adhesion of platelets to the membrane surface and deactivate the coagulation system.

Further, as a PVA-based resin, anion-modified P
When a PVA-based resin having a charged group such as VA is selected, in addition to the hydrophilic effect, it is possible to improve the stain resistance and the separation performance by an electric action, and impart the ion selective permeability and the ion exchange property.

[Brief description of drawings]

FIG. 1 is a 5000 × SEM photograph showing the structure of the outer surface of the porous hollow fiber membrane obtained in Example 1.

FIG. 2 shows the structure of the inner surface of the porous hollow fiber membrane 50.
It is a SEM photograph of 00 times.

FIG. 3 is a 5000 × SEM photograph showing the structure of the central portion of the cross section of the porous hollow fiber membrane.

FIG. 4 is a 5000 × SEM photograph showing a cross-sectional structure of the outer surface side of the porous hollow fiber membrane.

FIG. 5 is a 5000 × SEM photograph showing a cross-sectional structure on the inner surface side of the porous hollow fiber membrane.

Claims (1)

[Claims] 1. An internal coagulation liquid and / or an external coagulation liquid is prepared by using a stock solution containing a hydrophobic resin, a pore-forming agent and a common solvent thereof, and containing 0.1 to 20% by weight of a polyvinyl alcohol resin. A porous hollow fiber membrane produced by using as a membrane, wherein the porous hollow fiber membrane contains polyvinyl alcohol-based resin in an amount of 0.5 to 10% by weight. ..