JPS6159764B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel hollow fiber made of a hydrophobic polymer and a method for producing the same, and is particularly suitable for porous hollow fiber membranes, ultrafiltration membranes, and reverse osmosis membranes used for blood purification and dialysis as membranes with selective permselectivity. The present invention provides a hollow fiber and a method for producing the same. In recent years, research has been conducted into methods of separating specific fluid components from fluid mixtures such as blood using diaphragms, and development of fluid separation devices that utilize hollow fiber membranes or capillary membranes as diaphragms is progressing. Such a capillary type fluid separation device is recognized as having advantages over a method using a film-like membrane as a diaphragm in that it can provide a relatively large surface area relative to its volume and that it has high pressure resistance. However, the above device requires a very large number of capillary bundles, so-called hollow filament bundles as separation elements, to be sealed at the end of the container, and the number of hollow filaments used in one device is usually in the thousands to tens of thousands, in some cases. In some cases, the number of seals exceeds that number, but even if only one of the seals leaks, the device cannot be used, making sealing technology an extremely important and difficult problem. There is. Traditionally, products are leak tested.
Leaking products had a very high rate of being discarded as defective products. On the other hand, as hollow filament materials, conventional
Many studies have been conducted on porous semipermeable membranes made of synthetic polymers, which have various advantages, in place of regenerated cellulose, which has been used as a regenerated cellulose. In order to maintain the performance of a porous semipermeable membrane manufactured to provide performance, it is necessary for the porous part to be filled with water-containing liquid, and it is important to know when water will escape from the porous part. It has the characteristic that it does not return to its original performance even if it is returned to the water. Therefore,
When a hollow filament is used as a porous semipermeable membrane made of a hydrophobic synthetic polymer as a separation element of the capillary fluid separation device, it is necessary to provide a large amount of liquid to the filament in order to maintain performance. The above-mentioned difficulty is further exacerbated by sealing such a highly lyophilic hollow filament bundle in a container. Taking these points into consideration, the present inventors have conducted extensive research into a hollow filament that has a high degree of easy sealability and no change in performance, and its liquid-retaining composition, and have arrived at the present invention. Examples of hydrophobic synthetic polymers that can be used in the present invention include vinyl polymers, polyamide polymers, polyester polymers, and copolymers thereof, as well as polyurethane, polysulfone, polycarbonate polymers, and cellulose other than regenerated cellulose. Although derivatives and the like are included, it is necessary to have permselectivity obtained by having an appropriate degree of porous structure. Although various means for imparting a porous structure are known, the present invention is preferably applied to porous membranes formed by diffusion coagulation rather than porous membranes formed from heterogeneous systems such as extraction methods and evaporation methods. . In order to produce permselective hollow fibers from the above-mentioned high molecular weight polymers, a spinning dope is usually prepared by dissolving these polymers in an organic solvent. At this time, the organic solvent is preferably water-soluble, considering the desolvation mechanism and porosity formation mechanism described below. The spinning stock solution is then passed through a hollow spinneret (e.g., a spinneret consisting of an annular orifice with a hollow tube inside the spinneret hole), and is spun in the air, usually for a length of 10 cm or more.
After falling a distance of less than 200 cm, it is guided into a coagulation bath.
As the coagulation bath, any substance that is a non-solvent for the polymer and is compatible with the solvent of the spinning dope can be used alone or as a mixture with a solvent. Preferably a mixture of water and solvent is used. In this process, the hollow fiber wall changes into a porous membrane having selective permselectivity. The subsequent water washing step is for the purpose of removing the solvent, and eventually all the solvent is replaced with water. At this stage, the porous portion is saturated with water. The water-washed yarn then undergoes a post-treatment process and then proceeds to a fluid separation device installation process. Although the post-treatment step usually includes a drying step, it is not preferable to immediately dry the water-washed yarn for the hollow filament made of a synthetic polymer that can be used in the present invention. This is thought to be because the porous portion is gradually immersed in water due to the lack of water contained therein.
This is because, as a result, a change occurs in the predetermined water permeability and selective permeation performance. Fixing the structure by moist heat treatment and then drying it is somewhat effective in maintaining performance, but what is fixed is coarse pores and has little effect on fine pores. A preferred post-treatment in the present invention is immersion replacement treatment by immersion in an aqueous polyhydric alcohol solution. Examples of polyhydric alcohols include glycerin, ethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol, with glycerin being preferred. Hitherto, it is well known that a hollow filament is immersed in an aqueous polyhydric alcohol solution as a liquid replacement treatment. This is mainly used as a preservative to prevent shrinkage due to drying and deterioration of permeability due to pressure of the porous structure. For example, Japanese Patent Publication No. 50-40168 describes a method in which a cuprammonium cellulose hollow filament is washed with water, immersed in a glycerin solution, and then air-dried. However, in line with the above-mentioned purpose, the present inventors treated a hollow filament made of a hydrophobic synthetic polymer with an aqueous polyhydric alcohol solution after spinning and washing it with water, and then solidified it at the end of the bundle of hollow filaments. In the process of intensive research into a technology for sealing the hollow filament bundle in a separation device by impregnating it with a liquid, it was found that, unlike cellulose fibers, hydrophobic synthetic polymer filaments were used during the process. 〓
The above-mentioned immersion replacement treatment plays an extremely important role, and it is impossible to obtain a completely satisfactory product by simply immersing it in a polyhydric alcohol solution and then drying it. It was discovered that only liquid-containing hollow filaments meet this purpose, leading to the present invention. Such hollow filaments are used in capillary type fluid separation devices with a sealed structure obtained by infiltrating a solidifying liquid into the ends of a bundle of parallel hollow filaments housed in a vertically long cylindrical container. A selectively permeable hollow filament made of a hydrophobic synthetic polymer of Contains α (%) at a ratio of 0.925V+10<α<0.925V+50 (1), and the alcohol adhesion rate G
(wt%) is |G/α−0.1155√|<0.12...(2) with respect to the relative dryness D(%) of the separation device manufacturing process atmosphere. be. The volumetric porosity V (%) is expressed as a percentage of the volume of the pores per hollow filament unit polymer volume, and where ρ is the true specific gravity of the polymer and ρ _a is the apparent specific gravity of the hollow filament, V = (ρ- It is expressed as ρ _a )/ρ _a ×100 (%). The apparent specific gravity ρ _a is determined by ρ _a = absolutely dry weight/cross-sectional area of the filament immediately after spinning x length. Polyhydric alcohol adhesion rate G
(wt%) is per unit dry weight of hollow filament,
The liquid retention ratio α (wt%), which is expressed as a percentage of the weight of polyhydric alcohol contained in the liquid, is similarly expressed as a percentage of the weight of the aqueous polyhydric alcohol solution contained per dry weight of hollow filament unit. The relative dryness D (%) is a value calculated from the relative humidity R (%) of the atmosphere in the separation device manufacturing process as D=100-R. A hollow filament for producing a capillary fluid separation device with a sealed structure made of a hydrophobic synthetic polymer hollow filament, which is an object of the present invention, has a composition and amount of liquid that satisfies the above formulas (1) and (2) at the same time. must contain. If the fluid retention conditions are outside the range of equations (1) and (2), for example, the fluid retention rate α is higher than the range of equation (1), or the alcohol adhesion rate G (%) is outside the range of equation (2). If it is higher than the range, the sealing performance of the hollow fiber bundle during the production of the separation device will be impaired, and seal leakage will occur frequently. Conventionally, the method of sealing a hollow filament bundle in a separating device is to rotate a container filled with bundled fibers and feed a solidifying liquid, which is an adhesive, to both ends of the container, thereby applying centrifugal force to the adhesive. There are two known methods: one method in which the adhesive is infiltrated between the bundled yarns to harden it, and another method in which the adhesive is sent to the bottom of the upright bundled yarns and the adhesive is permeated into the bundle by gravity or the like and solidified. The adhesive is generally called a potting material and can be selected from polyurethane, silicone, epoxy resin, etc. If the solidifying liquid penetrates incompletely between the bundled yarns, pinholes are formed which cause leakage of the separation liquid. In general, the chance of seal leakage occurring in the process with dried filament bundles is significantly lower than with high lye retention content filaments. This is thought to be mainly because the wedging liquid generated between the filament bundles with a high liquid retention content impedes the penetration of the potting liquid, and after solidification, the wedging liquid portion becomes hollow, causing seal leakage. . If the liquid retention rate α is less than the range given by equation (1) or if the alcohol adhesion rate G is less than the range given by equation (2), this is undesirable because quality deterioration, especially a significant drop in permeability, occurs. In the case of the porous hollow filament made of the hydrophobic synthetic polymer according to the present invention, there is a limit hydrate retention specific to its volumetric porosity V, and when it contains a liquid with a higher sorption rate, , there is no change in permeation performance, but when it falls below the critical lyophilization rate, permeation performance decreases in proportion to it. However, simply making the fluid contain more than the limit value is not a realistic measure to prevent performance deterioration. This is because the hollow filament used as the separation element used in the present invention has an outer diameter of 100 to 300 μm, so the evaporation rate is high. Even if the retention rate is high, the fluid retention rate will drop below the critical value in a short period of time and performance will begin to deteriorate.
will be done. Therefore, alcohol adhesion rate G
(%) must be greater than the limit value corresponding to the atmospheric conditions of the separation device manufacturing process.
The range shown in formula (2) is a preferable range. The above-mentioned series of behaviors are mainly based on the specificity of the material components and are characteristics of a permselective porous membrane made of a hydrophobic synthetic polymer. More specifically, the major factor is the degree of reversibility of the produced film against changes in dryness and humidity. For example, the above-mentioned membrane made of hydrophilic regenerated cellulose does not exhibit this behavior and recovers its performance by rewetting even after drying to a fairly low retention rate. The hydrophobic synthetic polymer that can be used in the present invention exhibits such reversibility at a significantly low level. Specifically, polymeric materials that have a cross-sectional area increase rate of 20% or less when re-wetted compared to the cross-sectional area cut perpendicular to the axis when the hollow filament is thoroughly washed with water and completely dried are It is hydrophobic and is applicable to the present invention. Examples of such synthetic polymers include vinyl polymers and their copolymers such as polymethyl methacrylate, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, polyvinyl ether, polyacrylamide, polymethacrylamide, polymethyl acrylate, polyvinylidene chloride, and polysulfon. , polyesters such as polycarbonate, cellulose acetate, and polyethylene terephthalate, polyurethane, polyurea, polyamide polymers, polyvinyl alcohol polymers,
Includes ethylene vinyl alcohol copolymer, etc. The present invention is more preferably achieved by further dissolving the above synthetic polymer in a hydrophilic solvent and performing solution spinning. Representative examples of such solvents include dimethyl sulfoxide, dimethylacetamide, dimethylformamide, γ-butyrolactone, methyl ethyl ketone, tetrahydrofuran,
Methyl acetate, dioxane, furfural, formic acid,
Examples include. It is known that there is a group of synthetic polymer/organic compounds that cannot necessarily be said to be solvents at room temperature, but exhibit good compatibility with certain polymers when heated. ing. (For example, Tokko Akira
44-14215, page 3) When such a specific set of synthetic polymers/organic compounds is heated, then formed into a hollow filament, and then brought into contact with water to generate a porous structure,
If the above-mentioned organic compound is water-soluble, it is substantially the same as the water-soluble solvent in the present invention, and the molding method can also be considered to be essentially solution spinning/water washing and solvent removal, and the present invention also applies to these systems. is applicable. The method of wet-spinning a hydrophobic synthetic polymer in a hydrophilic solvent and then applying a solution having the compositional conditions of the present invention to a hollow filament is not a common method. As mentioned above, it is known to immerse a hollow filament in an aqueous polyhydric alcohol solution and to further dry the filament. However, it is extremely difficult to provide a filament with a solution having the compositional conditions of the present invention using such known methods. Because usually
By immersing a hollow filament with an outer diameter of 100 to 300μ in an aqueous polyhydric alcohol solution, the liquid retention rate shows a value of at least 300% or more, and the volumetric porosity V is usually 70 to 180%. For this reason, the range of equation (1) is greatly exceeded. In this case, if the alcohol concentration is high, moisture will be absorbed from the atmosphere and the liquid retention rate will further increase, but if the alcohol concentration is low, water will evaporate and the liquid retention rate will fall below the critical liquid retention rate over time. Therefore, only through carefully controlled substitution treatment under hydrate conditions and subsequent special post-treatment can a hydrate having compositional conditions within the scope of the present invention be provided. The hollow filament of the present invention is produced by dissolving a hydrophobic synthetic polymer in a hydrophilic solvent, using a hollow die, and dissolving the hydrophobic synthetic polymer in a hydrophilic solvent.
After dry-wet spinning in the aqueous solvent solution and rinsing with water, (i) immersion in a bath consisting of an aqueous solution of water-soluble polyhydric alcohol for sufficient immersion replacement treatment, and (ii) at least The filament surface is brushed with a water-soluble polyhydric alcohol aqueous solution having a concentration lower than that of the filament, and (iii) immediately or indirectly, the external liquid on the filament surface is scraped, and then the filament is wound up. You can get it. In the above method, the atmospheric conditions in the winding chamber are preferably controlled to constant temperature and humidity. moreover,
It is preferable that the atmospheric conditions be close to or match the atmospheric conditions of the subsequent sealing process. This〓〓〓〓
In such a case, the hollow filament has a volume porosity V (%) measured by the method described above, and an aqueous solution of a water-soluble polyhydric alcohol with a retention ratio α (%) of 0.925V+10<α<0.925V+50. Contains in proportion and polyhydric alcohol adhesion rate G
(%) is the relative dryness D of the sealing process atmosphere
(%), it is preferable to adjust so that |G/α−0.1155√|<0.12. However, in principle, the filament suspension immediately after spinning is not subject to strong constraints. The point is that the filament hydrate during the sealing process is subject to the above restrictions, and for example,
Immediately after spinning, the yarn is given a slightly higher amount of hydrated water,
One advantageous embodiment of the present invention is that the liquid retention conditions of the present invention can be adjusted by performing a light drying treatment in a post-process. However, adding too much water-soluble polyhydric alcohol is fatal to producing the filament of the present invention, and there are almost no methods for modifying it in a post-process. The concentration of the water-soluble polyhydric alcohol in the bath solution for the fluid retention replacement treatment is determined by determining the fluid retention rate α (%) and the polyhydric alcohol adhesion rate G (%) in advance, which are necessary to obtain the filament of the present invention. It is preferable to set and adjust the concentration C ₁ to around C ₀ =G/α, preferably slightly higher than C ₀ . Sufficient fluid retention treatment means that the composition of the filament fluid retention solution after treatment is very close to the bath solution concentration C ₁ . Furthermore, in the final step of the treatment, a high temperature section can be provided to perform heat treatment for dimensional stabilization. Then, it is effective to carry out the brushing treatment with a bath liquid having a concentration that does not exceed at least C ₁ and generally is lower than C ₀ . The brushing treatment refers to a light treatment that replaces the fluid retained on the surface of the filament (external retained fluid). Specifically, these methods include immersing the filament in the bath liquid for a processing time of about 0.1 seconds to 10 seconds, directly bringing the filament into fluid contact with the bath liquid, and indirectly contacting the filament with the bath liquid by rotating a roller. It can be done. The filament is then subjected to a scraping process in which the external fluid retention on the surface is directly or indirectly wiped off. The direct method is accomplished by contacting the thread path with an external fluid absorbing or suction device such as a sponge, cloth, or suction hole, and wiping the surface. The indirect method is a method in which the filament is run on a multistage roller and the roller surface is wiped to scrape the external liquid transferred from the filament to the roller surface. Scraping with a sponge, cloth, etc. has poor long-term durability, and an indirect method using multistage rollers is preferable. A preferred fluid retention distribution of the filaments of the present invention is such that about 90% or more of the total fluid retention is present in the porous walls of the hollow filament. Therefore, in the case of a filament that has been immersed in a normal bath solution, approximately 50% or more of the filament is externally hydrated, so it is necessary to remove a large amount of the hydrated liquid by scraping. Normally, in multi-roll scraping, the amount of liquid transferred to one roll is 10 to 50 times the external amount of liquid on the filament surface.
%. Therefore, several rolls or more are required to obtain the filament of the present invention. The hydrated liquid transferred onto the roll is scraped off by a scraper blade that is placed in close contact with the roll surface so as not to damage it, and falls out of the system. The lower the polyhydric alcohol concentration in the solution, the lower the solution viscosity and generally the better the scraping efficiency. Therefore, in order to give a solution with a retention rate α (%) and an adhesion rate G (%), C ₀ = slightly higher than G/α is required in advance.
After performing retention fluid replacement treatment with a bath solution with a concentration of C ₁ , brushing treatment with a bath solution with a concentration lower than C ₀ reduces the polyhydric alcohol concentration in the external retention solution and reduces the adhesion of alcohol. It is preferable to control the amount, increase the scraping efficiency, and reduce the final external liquid retention rate. This also has the advantage that the liquid retention rate can be kept extremely uniform during the production process.
The filament thus wound is preferably stored at an ambient temperature and humidity such that subsequent moisture absorption and evaporation are minimized. If the product has significantly absorbed moisture during storage before sealing, do not leave it in the sealing atmosphere for a long time.
It needs to be aged. On the other hand, it is not preferable to place the product in an atmosphere that causes water to evaporate significantly, as this will cause quality deterioration. Regarding temperature control, normal room temperature (10℃~30℃)
In the range around ℃), there is almost no effect on physical properties〓〓〓〓
Since it is not given, there is no need to consider it. In general, water permeability is an extremely important quality factor in the fluid separation device that is the object of the present invention, and it is necessary to control the value within a strictly controlled certain range for the product. The biggest factor governing water permeability is the spinning conditions in the spinning process in which the spinning dope is formed into a porous semipermeable membrane hollow filament. , the filament is spun. However, as mentioned above, in the post-process, for example, the quality deteriorates due to significant evaporation of water.
In particular, a decrease in water permeability is a serious drawback as a product. Water permeability coefficient retention is a method for testing this point. This is about the amount of filament immediately after spinning.
Soak 20 pieces in glycerin to the specified length,
A simple fluid separation device obtained by solidifying both ends of each filament with an epoxy potting agent and inserting it into a commercially available circular tube made of polymethyl methyl methacrylate, which has holes for inlet and outlet for the reflux liquid and has been processed to a predetermined length. The effective membrane area, membrane thickness, operating pressure, etc. are standardized, the water permeability coefficient is measured, and D ₀ (ml/
hr・mmHg・^m2 ). Next, for the product separation device, the water permeability coefficient obtained by measurement corresponding to the above conditions was defined as D ₁ , and W=D ₁ /D ₀ ×100 (%) was defined as the water permeability coefficient retention rate. Generally, the water permeability coefficient retention rate is preferably 90% or more, and values lower than this are not preferred from the viewpoint of quality and production control. As described above, the present invention reduces the incidence of sealing defects that frequently occurred in the past, without degrading the fluid separation device.
The present invention provides a hollow filament and a method for manufacturing the same, and is extremely useful in increasing production efficiency of fluid separation devices. Example 1 Commercially available radical polymerized methyl methacrylate polymer (weight average molecular weight 120,000, isotacticity 14%,
29% heterotactic, 52 syndiotactic
%) and 55 parts of a methyl methacrylate polymer having a weight average molecular weight of 430,000, 93% isotacticity, 5% heterotacticity, and 2% syndiotacticity obtained by polymerization with a Grignard catalyst, and dimethyl sulfoxide (DMSO ) and dissolved at 120°C to prepare a spinning stock solution. This spinning stock solution was transferred to a stock solution tank of a spinning device kept at 95°C. The spinning device is equipped with a nozzle consisting of an annular orifice with an outer diameter of 2.0 mm and an inner diameter of 1.6 mm, which has a hollow tube inside the nozzle hole. Air is injected from the hollow tube under a slight constant pressure while spinning is performed using a gear pump. The stock solution was extruded and spun. After the spun filament passes about 30 cm vertically downward through air at a temperature of about 5 to 10 degrees Celsius,
The mixture was introduced into a coagulation bath consisting of a 30% dimethyl sulfoxide aqueous solution, and then thoroughly removed with a water washing bath. The raw solution discharge rate is 1.0 cc/min, and the take-up speed is approximately 20 cc/min.
m/min. After leaving the water washing bath, the filament was then led to a glycerin bath filled with a 60% glycerin aqueous solution at 40°C, where it was thoroughly subjected to liquid immersion replacement treatment. The yarn was then placed in a brushing tank (immersion length 30 cm) filled with a glycerin aqueous solution at 45°C with a concentration of 40%.
After passing through it, it was brought into contact with the surfaces of seven rotating rollers, and then wound up with a winding machine. A scraper blade was attached to the surface of each roller in close contact so as not to scratch the surface, and the retained liquid transferred onto the roll was removed over time. The temperature and humidity around the winding section were maintained at RH 60% and 25°C, and the wound filament was also kept under the same conditions. Next, under the above atmospheric conditions, a 150 denier processed polyester yarn was wound around each hollow filament in a helical shape at a winding rate of 0.5 turns/10 mm to a length of 30 mm.
We made a filament bundle of 8,000 cm. The filament at this time has a volume porosity of 120%,
The fluid retention rate was 136% and the glycerin adhesion rate was 90%.
Next, under conditions of RH 60% and 25°C, this bundle was placed in a cylindrical case, an end mold was attached to allow the solidifying liquid to flow in, and the bundle was set horizontally in a centrifugal casting machine. The case was then rotated, and a pottein material containing polyurethane as a main component was poured into the end mold to seal the end. Regarding the multiple separators thus obtained, 600
The seal leakage was determined by the mmAq pressure test, and the sealing yield was 100%. In addition, the water permeability coefficient retention rate measured by the method detailed in the text was 98.
%showed that. Examples 2 to 3 The same spinning solution as in Example 1 was used until the washing bath.
The material was spun under the conditions shown in Table 1, and subsequent steps were performed under the conditions shown in Table 1. A fluid separation device was constructed under the same atmospheric conditions as in Example 1, and the results shown in Table 1 were obtained. This shows that hollow filaments containing liquids outside the scope of the present invention (Comparative Examples 1 to 4) have a low sealing treatment yield or a marked decrease in water permeability coefficient retention. . Examples 4-5 Sulfopropylmethyl methacrylate Na salt
Add 24 parts of dimethyl sulfoxide to 5 parts of radically polymerized methyl methacrylate polymer copolymerized with 2.5 moles and 1 part of methyl methacrylate before polymerization polymerized with a Grignard catalyst, and dissolve at 120°C to prepare a spinning stock solution. did. This spinning stock solution was spun under the same spinning conditions as in Example 1, except for the conditions listed in Table 2, and the hollow filament obtained was then wound at a constant pitch on a rotating drum covered with double-sided adhesive tape. A blind-shaped sheet with both ends fixed with double-sided adhesive tape was obtained, and a hollow filament bundle was obtained by winding the sheet into a nozzle shape. This bundle was sealed in a cylindrical case by centrifugal casting in the same manner as in Example 1, to obtain a plurality of fluid separators. These were subjected to the same tests as in Example 1, and the results shown in Table 2 were obtained. Comparative Examples 5 and 6 show that conditions outside the scope of the present invention are not preferable. Example 6 Polyacrylonitrile copolymer (copolymer component P
- 12 parts of sodium styrene sulfonate (0.5 mol%) was dissolved in 88 parts of a mixture of water and dimethyl sulfoxide in a weight ratio of 7:93 to prepare a spinning stock solution and maintained at 70°C. A mixture of water and DMSO at a weight ratio of 45:55 was quantitatively injected into this solution using a cap consisting of an annular orifice with a hollow capillary inside the cap hole, as in Example 1. The material was spun into water at 25°C in the same manner. After washing with water, the solution was sufficiently hydrated in a 60% glycerin aqueous solution at 40°C, and then brushed in a 40% aqueous solution at the same temperature.
The filament wound through the scraper roll had a volumetric porosity of 140%, a liquid retention rate of 160%, and a glycerin adhesion rate of 104%. This filament
When a fluid separator similar to that in Example 1 was made using 8000 tubes, the sealing yield was 98% and the water permeability coefficient retention rate was 98%. On the other hand, the volume porosity obtained by omitting the scraping process was 140%, and the liquid retention rate was 140%.
A fluid separator made using a filament with a glycerin adhesion rate of 202% and a glycerin adhesion rate of 135% has a sealed processing yield of 38%.
%, and the water permeability coefficient retention rate was 100%. Example 7 Cellulose diacetate was mixed with tetramethylene sulfone in a blender, dried, and then chipped. This was melt spun to create a hollow filament. After washing this hollow filament with water, it was immersed in an aqueous glycerin solution, and then subjected to treatments such as brushing and scraping, thereby making it possible to obtain a hollow filament that fully achieved the object of the present invention.

[Table] 〓〓〓〓

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[Table] 〓〓〓〓

Claims (1)

[Scope of Claims] 1. A hollow filament for use as a separation element in a capillary fluid separation device is completely washed with water, and the cross-sectional area cut perpendicular to the axis when it is completely dried is compared with the cross-sectional area when it is re-wetted. It is a permselective hollow filament made of a polymeric material with a cross-sectional area increase rate of 20% or less, and has a retention rate α of an aqueous solution of water-soluble polyhydric alcohol with respect to the volume porosity V (%).
(%) is contained in a ratio of 0.925V+10<α<0.925V+50, and the polyhydric alcohol adhesion rate G (%) is |G/α−0.1155 with respect to the relative dryness D (%) of the sealing process atmosphere. A permselective hollow fiber characterized by √｜<0.12. 2. After completely washing the hollow filament with water, add a polymeric material in a hydrophilic solution such that the cross-sectional area when re-wetted is 20% or less compared to the cross-sectional area cut perpendicular to the axis when completely dry. After dissolving, solution spinning is performed using a hollow nozzle, and after washing with water, (i) immersion in a solution consisting of an aqueous solution of water-soluble polyhydric alcohol and sufficient immersion replacement treatment, and (ii) at least a concentration lower than the above solution concentration. A separation element in a capillary fluid separation device, characterized in that the surface of the filament is brushed with an aqueous solution of water-soluble polyhydric alcohol, and then (iii) the external liquid on the surface of the filament is scraped and then wound up. Method for producing permselective hollow fibers for use as