JPH0257982B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial application field The present invention has a hole penetrating between the inner and outer wall surfaces,
The present invention relates to a regenerated cellulose hollow fiber membrane having an average pore diameter in the range of 0.02 to 10 μm on the inner and outer wall surfaces. (b) Conventional technology In recent years, membranes with selective permeability have been attracting attention in fields such as seawater desalination, wastewater treatment, artificial kidneys, and the food industry.In particular, the development of hollow fibers that can provide a large surface area per unit volume has been attracting attention. It's progressing. Typical regenerated cellulose hollow fiber membranes made from cellulose copper ammonia solution include:
(1) Uniform wall thickness of several μm to 60 μm over the entire fiber length and entire circumference and outer diameter of 10 μm to several
Hollow fibers made of copper ammonia cellulose fibers that have a uniform perfect circular cross section of 100 μm and have hollow portions extending continuously over the entire length of the stretched and oriented fibers (Japanese Patent Publication No. 50-40168), ( 2) A hollow artificial fibrous body made of copper ammonia regenerated cellulose in which the cross-sectional structure has a porous structure in which the component near the outer surface has a denser pore structure than both the component near the inner surface and the middle part (Special Publication No. 55 -1363), (3) In an electron microscopic observation of a cuprammonium regenerated cellulose tubular body having a hollow core when wet,
The entire cross section and longitudinal section is at most 200 Å
Hollow fiber fibers for dialysis made of copper ammonia regenerated cellulose (Japanese Unexamined Patent Application Publication No. 134920/1983), which are made of copper ammonia regenerated cellulose, which have a substantially homogeneous and dense porous structure with the following microscopic gaps, and have skinless and smooth surfaces on both the inner and outer surfaces.
No.) etc. In both of these hollow fiber membranes, the cuprammonium cellulose spinning dope is directly extruded into the air from an annular spinning hole and allowed to fall under its own weight. The material is manufactured by introducing and filling a non-coagulable liquid into the material, discharging it, and then fully stretching it by its own weight, and then immersing it in a dilute acid solution for solidification and regeneration. Since the average pore diameter of the hollow fibers obtained by such methods is all less than 0.02 μm, they cannot be used in fields such as ultrapure water production, food concentration and purification, pharmaceutical purification, sterilization, and particulate removal. For this reason, the development of hollow fiber membranes with large pore sizes has been desired. (c) Problems to be Solved by the Invention The purpose of the present invention is to provide excellent filtration performance (i.e., filtration performance and filtration capacity) and mechanical properties (i.e., strength) that could not be achieved with conventional hollow fiber membranes as described above. ) A regenerated cellulose hollow fiber membrane is provided. (d) Means for Solving the Problems The hollow fiber membrane of the present invention has an average molecular weight of 5×10 ⁴ to 5 and has a hollow portion continuously extending through the entire fiber length.
×10 ⁵ regenerated cellulose hollow fiber membrane, the hollow fiber membrane is composed of cellulose particles with a diameter of 0.02 to 1 μm, and the hollow fiber membrane has an average pore diameter of 0.02 on both the inner and outer wall surfaces. It has pores of ~10 μm, and is characterized in that the average pore diameter of the pores on the inner wall surface and the outer wall surface is larger than the average pore diameter of the pores on the intermediate portion. In the regenerated cellulose hollow fiber membrane according to the present invention, when producing hollow fibers using a cellulose copper ammonia solution, the cellulose concentration is increased from the outer annular spinning opening.
A 3.5-10.5% by weight cellulose cupric ammonia solution was added as a hollow agent from the central spinning spout to form a cellulose with no hydroxyl groups and a solubility of 10% in a 28% by weight ammonia aqueous solution.
By discharging a hollow agent consisting of a ketone, ammonia and water that does not swell cellulose at a concentration of 20 to 160% by weight or more and a concentration of ammonia to water of 5% or less by weight, It can be produced by causing microphase separation from the interface between the cellulose copper ammonia solution and the hollow agent, followed by solidification and regeneration. Hereinafter, the hollow fiber membrane of the present invention will be explained in detail in relation to its manufacturing method. Hollow fiber membranes manufactured from cellulose cupric ammonia solution by a known method use a non-coagulable liquid for the spinning stock solution as a hollowing agent. Possibly due to this, the average pore size of the obtained hollow fiber membrane is less than 0.02 μm, whereas when spun according to the manufacturing method of the hollow fiber membrane of the present invention, the average pore size is less than 0.02 μm.
Hollow fiber membranes with a wide range of diameters from 0.02 μm or more to 10 μm can be produced, and the pore density per unit area is increased compared to hollow fiber membranes obtained by known methods, and there are also many through holes. Here, "microphase separation" means a state in which a concentrated phase or a dilute phase of cellulose is dispersed and stabilized as particles with a diameter of 0.01 to several μm in a solution. In addition, the occurrence of microphase separation can be observed directly with the naked eye by the devitrification phenomenon of the yarn during spinning, or by replica transmission electron microscopy of the yarn after spinning to determine the occurrence of microphase separation with a diameter of 1 μm or less.
Confirmed by the presence of cellulose particles of 0.02 μm or more. Even when the hollow fiber membrane of the present invention is cut parallel to the membrane surface at any position in the wall thickness direction, through-holes with a pore diameter (approximately 0.02 μm or more) that can be observed with an electron microscope are observed. In addition, the average pore diameter on both the inner and outer walls of the hollow fiber membrane is in the range of 0.02 to 10 μm,
The average pore diameter at the intermediate portion between both wall surfaces is smaller than the average pore diameter at both the inner and outer wall surfaces, as shown in Examples below. By using a mixed solution consisting of ketone, ammonia, and water as the hollowing agent, microphase separation also occurs from the interface between the hollowing agent and the stock solution, followed by coagulation, and as a result, the average pore size of the inner wall increases. It is possible to make it larger. Here, coagulation refers to the solidification of the cellulose copper ammonia solution,
In other words, it means a state in which the viscosity of the solution is 10 ⁴ poise or higher. The hollowing agent suitable for causing microphase separation varies depending on the cellulose concentration, ammonia concentration, and copper concentration in the cellulose cuprammonium solution and is not necessarily the same, so it is necessary to determine each in advance in the spinning stock solution. Must-have. Specifically, the solvent is added dropwise into the cellulose copper ammonia solution, which is the spinning stock solution, while stirring the solution, and the amount of the solution is determined by weight ratio.
A solvent that causes microphase separation without coagulation at 10% or more, preferably 20% or more may be used as the hollowing agent. The occurrence of microphase separation is usually
It takes 10 seconds to several tens of minutes. Therefore, in actual spinning, it is desirable that the molecular weight of the hollowing agent is small. Further, it is more desirable to immerse the discharged fibrous material in the above-mentioned mixed solution consisting of ketone, ammonia and water. By using a mixed solution consisting of ketone, ammonia, and water that causes microphase separation, it is possible to create pores with an average pore diameter of 0.02 μm or more on the outer wall of the hollow fiber membrane, and the average void ratio Prρ can also be reduced. increase In addition, in the production of the hollow fiber membrane of the present invention, it is also possible to use a cellulose copper ammonia solution with an average molecular weight of cellulose molecules of 5 × 10 ⁴ or more, so that the mechanical properties (especially strength) in the dry state are Excellent regenerated cellulose hollow fiber membranes can be produced extremely easily. For example, if the average porosity is
If Prρ (%), the elastic modulus of a hollow fiber membrane obtained using a cellulose cupric ammonia solution in which cellulose with an average molecular weight of 1×10 ⁵ or more is dissolved is 1.5×10 ⁸
(100−Prρ)dyn/cm ² or more. Generally, regenerated cellulose hollow fiber membranes are brittle in a dry state. For this reason, conventional regenerated cellulose hollow fiber membranes are soaked in glycerin or the like to prevent them from drying out. Regenerated cellulose hollow fiber membranes have been obtained by saponifying hollow fibers of cellulose derivatives such as cellulose acetate or cellulose nitrate with an aqueous alkaline solution. The average pore diameter of the hollow fiber membrane obtained by such a method is in the range of 0.01 to 2 μm, and since it is prepared using a cellulose derivative as a starting material, the average molecular weight of the cellulose molecules after regeneration is 4.0×10 ⁴ or less. Therefore, the mechanical properties (eg, strength) of hollow fiber membranes in a dry state are inferior to those of hollow fiber membranes made of synthetic polymers. For example, the tensile modulus is approximately ¹⁰² (100-Prρ)dyn/ ^cm2 . Tensile breaking strength is approximately proportional to the elastic modulus, approximately 1/10 of the elastic modulus.
It is. Conventional regenerated cellulose hollow fiber membranes obtained from cellulose derivatives may break during handling because their strength in a wet state with water is even lower than in a dry state. Moreover, in the above-mentioned method for producing regenerated cellulose hollow fibers in which cellulose derivatives are regenerated, the production process is long and the production cost is high. As the molecular weight increases, the strength of the hollow fiber membrane increases and its brittleness is improved. Therefore, handling of the hollow fiber membrane becomes easier and damage to the hollow fiber membrane is reduced. The higher the average molecular weight of cellulose, the lower the breakage rate when compared at the same porosity. It is observed that the influence of the average molecular weight on the physical properties of the hollow fiber membrane tends to become saturated as the average molecular weight increases. Therefore, an average molecular weight of 5.0×10 ⁴ or more and 5.0×10 ^{5 or} less is acceptable in terms of practical ease of handling.
A more preferable range is 5.5×10 ⁴ or more and 3×10 ⁵ or less. That is, the hollow fiber membrane of the present invention is characterized in that it is extremely easy to impart sufficient mechanical properties to the hollow fiber membrane even in a dry state that does not contain a swelling agent such as glycerin. As the above-mentioned hollow agent, a mixed solution consisting of a ketone, ammonia and water is used, which does not have a hydroxyl group, has a solubility in a 28% by weight ammonia aqueous solution of 10% by weight or more, and does not swell cellulose.
It is preferable to use a similar mixed solution not only as a hollowing agent but also as a coagulant. By using the above-mentioned mixed solution as both the hollow agent and the coagulant, the normally formed skin layer disappears, and pores with a pore diameter of 0.01 μm or more are formed on both the outer and inner wall surfaces of the hollow fiber. Further, preferred ketones include acetone and methyl ethyl ketone. Further, ammonium sulfate or ammonium acetate may be included in the mixed solution. In the above mixed solution, the concentration of ammonia relative to water is 5% by weight or less, preferably 3% by weight or less, and the concentration of ketone relative to water is 20% by weight or more.
When it is 160% by weight or less, preferably 35% by weight or more and 110% by weight or less, the pore diameter becomes large, the pore density also increases, and the proportion of through holes increases, allowing for stable production with good reproducibility. Ketones that do not swell cellulose are defined as having a swelling rate of +5% to -3 when hollow fibers are immersed in ketones at 20°C for 10 minutes.
% of ketones. In addition, by adding the ketone to the cellulose cupric ammonia solution in advance to a concentration below the gelling point or below 30% by weight, the spinning speed can be increased, the production time can be shortened, and hollow fiber membranes with good reproducibility can be produced. Obtainable. The principle feature of the production of the hollow fiber membrane of the present invention is that when the hollow fiber is spun using a mixed solution consisting of the above ketone, ammonia, and water as a hollow agent and a coagulation bath, the hollow fiber becomes devitrified. It is clear from this. That is, the most important feature is that it undergoes microphase separation, followed by coagulation, regeneration, and water washing. As a microstructural feature of hollow fiber membranes that have undergone a microphase separation state, in cellulose and cellulose-2 crystals, the orientation of the hollow fiber membranes in the radial direction of the (101) plane perpendicular to the hydrogen bonds is determined by a known method. It is smaller than that of the obtained hollow fiber membrane. Ketones that cause such microphase separation have common properties: they do not have hydroxyl groups, have a solubility in a 28% ammonia aqueous solution of 10% by weight or more, and do not swell cellulose. When spinning using a mixed solution containing an organic solvent with hydroxyl groups,
Microphase separation does not occur, resulting in a transparent hollow fiber membrane, or a skin layer is formed on the outer and inner wall surfaces of the hollow fiber membrane, resulting in a pore diameter of 0.02 μm on the outer wall surface of the hollow fiber membrane.
In most cases it is less than. The smaller the molecular weight of the ketone used, the shorter the time for microphase separation to occur and the better the workability in the post-treatment process, so it is desirable. Note that if the solubility of ketone in a 28% ammonia aqueous solution (amount (weight) dissolved per 100ml of a 28% ammonia aqueous solution) is not 10% by weight or more, microphase separation will not occur or will occur only slightly. However, during actual spinning, a thin skin layer is formed on the outer or inner wall surface of the hollow fiber, and the average pore diameter of the resulting hollow fiber membrane is less than 0.02 μm. The higher the solubility in water, especially the solubility in an alkaline aqueous solution, the better. The cellulose concentration in the cellulose cuprammonium spinning dope is preferably 3.5% by weight or more and 10.5% by weight or less. The cellulose concentration in the spinning stock solution is
If it is less than 3.5% by weight, the viscosity of the stock solution decreases and the spinnability deteriorates, making the spinning state unstable and making it difficult to obtain hollow fiber membranes with good reproducibility. If it exceeds 10.5% by weight, the hollow fibers become hard and transparent, and the porosity and pore density decrease. Therefore, if the cellulose concentration is 3.5% to 10.5% by weight, the performance as a hollow fiber used for microfiltration etc. is sufficiently satisfied. The preferred cellulose concentration is 4% to 10% by weight. The above-mentioned copper ammonia solution is a solution whose main components are copper and ammonia, and is a dark blue solution called a Schweitzer reagent, which means a solvent system that can substantially dissolve cellulose. , including those containing some cations other than copper or solvents other than ammonia. Also,
Cellulose concentration means the weight concentration of cellulose in a copper ammonia solution. The acid for regeneration is
Although not particularly limited, it is desirable to use dilute sulfuric acid (for example, 2% by weight diluted sulfuric acid) in consideration of recovery or corrosion. The regenerated cellulose hollow fiber membrane of the present invention can be used to separate and remove target components in liquid or gas mixtures containing water, such as hollow fiber membranes for artificial kidneys, artificial livers, or artificial pancreases. Although it can be used as other ultrafiltration membranes, the regenerated cellulose hollow fiber membrane of the present invention, which is hydrophilic, has excellent mechanical properties, and is strong, is suitable for bio-related fields (medicine, biochemical industry) or food fermentation fields. . Typical examples of microstructural features and various physical property values of the hollow fiber membrane of the present invention are shown. The average molecular weight of cellulose molecules is 5.75×10 ⁴ , the dynamic elastic modulus at 30°C at a measurement frequency of 110 Hz is 1.3×10 ¹⁰ dyn/cm ² , and the mechanical loss tangent
The peak value of tanδ (tanδ)max is 0.14, the peak temperature of tanδ Tmax is 262℃, the average pore diameter of the outer wall is 1μm,
The average pore diameter of the inner wall surface is 1.2 μm, and the porosity is 72%. Furthermore, scanning electron micrographs of the outer wall surface, intermediate portion, and inner wall surface of the membrane obtained by the method of the present invention are shown in FIGS. 1, 2, and 3, respectively. Prior to Examples, methods for measuring various physical property values used in the detailed description of the invention are shown below. <Average molecular weight> Calculate the average molecular weight (viscosity average molecular weight) Mv by substituting the intrinsic viscosity number (η) (ml/g) measured in a cupric ammonia solution (20°C) into the following formula (1). . Mv=[η]×3.2×10 ³ (1) <Fixation and orientation parameters of cellulose and -2 crystals> Rigaku Denki X-ray generator (RU-200PL), goniometer (SG-9R), and counter tube A scintillation counter is used for the measurement part, a pulse height analyzer (PHA) is used for the counting part, and the measurement is performed using a symmetrical transmission method using Cu-Kα rays (wavelength λ = 1.5418 Å) made monochromatic with a nickel filter. The water content of a 5 mm long hollow fiber membrane moistened with water is replaced with acetone, and after air drying, approximately 200 fibers are bundled into a cylindrical shape, the diameter of which is defined as Dx (cm). The bundle is crushed under a load of about 100×Dx (Kg) to eliminate hollow parts. That is, the film is apparently transformed into a laminated film state. Operate the X-ray generator at 40 KV x 100 mA, set the scanning speed to 1°/min, the chart speed to 10 mm/min, the time constant to 2 seconds, the divergence slit to 2 mmφ, the receiving slit to be 1.9 mm in length, and 3.5 mm in width. The X-ray diffraction intensity curves in the equator direction and meridian direction in the cross-sectional direction of the hollow fiber membrane after deformation under load are measured. Cellulose crystal has 2θ=12° [reflection from (101) plane], 20° [reflection from (101) plane], 22° [(002)
)
It is characterized by two types of diffraction: reflection from a surface.
Furthermore, cellulose-2 crystals are characterized by two diffraction patterns with 2θ angles of approximately 12° and 21°. A straight line connects the X-ray diffraction intensity curves obtained from the equator line and the meridian direction between 2θ=15° and 35° to form the base line. Then, the distance (intensity) from the apex of the diffraction peak of the (101) plane and the (101) plane to the baseline is measured. The diffraction intensity of the (101) plane in the equator direction is H ₁ ,
If the diffraction intensity of the (101) plane is _H2 , the diffraction intensity of the (101) plane in the meridian direction is _H3 , and the diffraction intensity of the (101) plane is _H4 , then the diffraction intensity ratio A in the equator direction is
H ₂ /H ₁ , and the diffraction intensity ratio B in the meridian direction is H ₄ /
_H3 . The orientation degree parameter OP is calculated by the following formula (2). Orientation degree parameter OP=1-A/B (2) <Average pore radius, pore density> If the number of pores with a pore radius of r to r+dr per ¹ cm2 of porous membrane is expressed as N(r) dr, (N (r) is a pore size distribution function), the average pore radius ₃ , and the pore density N are given by the following equations (3) and (4). = ^∞ / ₀ r ₃ N (r) dr / ^∞ / ₀ r ₂ N (r) dr (3
) N=∫ ^∞ ₀ N(r)dr (4) The moisture inside the hollow fiber membrane in a wet state was replaced with acetone, and then air-dried. Electron micrographs are taken using a scanning electron microscope. Sampling of the wall thickness is done by embedding the hollow fiber membrane in epoxy resin and measuring from the outer wall surface using a glass knife attached to an ultramicrotome (LKB (Sweden) Ultratome 8800 model). 1.
A sample with a thickness of about 1 μm was cut out parallel to the fiber axis direction of the hollow fiber membrane at a position of 8 to 1/2.2. Calculate the pore size distribution function N(r) from the photograph using a known method,
Substitute this into equation (3). In other words, enlarge and print a scanning electron micrograph of the area where you want to determine the pore size distribution to an appropriate size (for example, 20 cm x 20 cm), and then draw 20 test lines (straight lines) at equal intervals on the resulting photograph.
Draw a book. Each straight line crosses a number of holes. Measure the length of the straight line that exists within the hole when it crosses the hole, and find this frequency distribution function. Using this frequency distribution function, for example stereology (e.g.
N using the method of “Quantitative Morphology” by Norio Suwa (Iwanami Shoten)
(r). Note that the average pore diameter is 2 ₃ . <Average porosity Prρ> The moisture inside the hollow fiber membrane in a wet state is replaced with acetone, and the hollow fiber membrane obtained by air drying is then dried in a vacuum to reduce the moisture content to 0.5% or less. When the inner diameter of the hollow fiber after drying is D _i (cm), the outer diameter is D _p (cm), the length of the hollow fiber is l (cm), and the weight is w (g), Prρ is calculated by the following formula (5 ) is given. Prρ (%) = {1-w/0.375×π( ^D2 / ₀ - ^D2 / ₁ ×l}×100
(5) <Tmax, dynamic elastic modulus> The moisture inside the hollow fiber membrane in a wet state was replaced with acetone, and then the hollow fibers with a length of 5 cm obtained by air drying were heated using Rheo-Vibron manufactured by Toyo Baldwin Co., Ltd.
Using a DDV-c type, the peak value of tan δ (tan δ) max and tan δ were determined from the tan δ-temperature curve and the dynamic elastic modulus-temperature curve at a measurement frequency of 110 Hz and an average heating rate of 10°C/mm under dry air. Read the peak position Tmax and dynamic elastic modulus at 30℃. (F) Examples Hereinafter, the hollow fiber membrane of the present invention will be specifically described with reference to Examples. Examples 1 to 5 Cellulose linter (average molecular weight 2.35×10 ⁵ )
was dissolved in a copper ammonia solution having an ammonia concentration of 6.8% by weight and a copper concentration of 3.1% by weight, prepared by a known method, at the concentrations shown in Table 1, and subjected to filtration and devacuolization to obtain a spinning stock solution. The spinning stock solution was discharged at a rate of 1.25 ml/min from the outer annular spinning spout (outer diameter 2 mmφ), while the ratio of acetone to water was 101.1% by weight.
Then, a mixed solution of ammonia and water with a ratio of 1.1% by weight was used as a hollow agent at the central spinning outlet (outer diameter 0.4 mmφ).
At a speed of 1.77 ml/min, the mixture was directly discharged into a mixed solution (coagulant) containing 101.1% by weight of acetone and water and 1.1% by weight of ammonia and water, respectively, and at a speed of 11 m/min. Winding ivy. then 2% by weight
It was regenerated with an aqueous sulfuric acid solution and then washed with water. The moisture content of the obtained hollow fiber membrane was replaced with acetone, and then the membrane was air-dried under tension. The physical properties and microstructure of the membrane were measured. Table 1 shows the results.

[Table] Immediately after being discharged, the transparent blue fibrous material gradually turns white, causes microphase separation, and then coagulates to maintain its fibrous shape.
Immediately after discharge and microphase separation has occurred, the fibrous material is practically liquid. This means that, for example, the area where microphase separation has occurred roughly corresponds to the area where the fiber diameter becomes thinner when the winding speed is increased.
It was also confirmed that when a solid rod was brought into direct contact with the area where microphase separation had occurred, it adhered to the rod in liquid form. Example 6 The spinning dope used in Example 3 was spun at 1.25 ml/min from the outer annular spinning spout, while the ratio of methyl ethyl ketone to water was 43.2% by weight, and the ratio of ammonia to water was 0.8% by weight. % mixed solution was directly discharged from the central spinneret at 1.77 ml/min into a mixed solution containing 101.1% by weight of acetone and water and 1.1% by weight of ammonia and water.
It was wound up at a speed of m/min. Note that, as in Examples 1 to 5, the transparent blue fibrous material immediately after discharge gradually turned white, and microphase separation occurred. Thereafter, it was regenerated with a 2% by weight aqueous sulfuric acid solution, and then washed with water. The results of measuring each physical property and microstructure of the hollow fiber membrane after drying are shown below. Average molecular weight is 5.72×
10 ⁴ , the average pore diameter on the outer wall surface is 0.85 μm, the average pore diameter on the inner wall surface is 0.91 μm, the average pore diameter in the middle part is 0.35 μm, the porosity is 63%, the crystalline region is composed of cellulose type crystals, (101) The plane orientation parameter is 0.11
The dynamic elastic modulus at 30℃ is 1.25×10 ¹⁰ dyn/
cm ² and Tmax were 265°C. Comparative Example 1 The spinning dope used in Example 3 was fed at a rate of 1.25 ml/min from the outer annular spinning spout, while trichlorethylene (a non-coagulable liquid with respect to the spinning dope) was fed at a rate of 1.77 ml/min from the central spinning spout. minutes, respectively, directly into a mixed solution of 101.1% by weight of acetone and water and 1.1% by weight of ammonia and water.
It was wound up at a speed of 5 m/min. In addition, since the hollow agent is non-coagulable with respect to the spinning dope and is not a thread that causes microphase separation in the spinning dope, microphase separation does not occur, and the transparent blue-like fibrous material immediately after discharge is almost It didn't change. In addition, the spinning state was very unstable, and only slab-like hollow fibers could be spun. After that, it was regenerated with a 2% by weight sulfuric acid aqueous solution,
After that, I washed it with water. Table 2 shows the results of evaluating each physical property and microstructure of the hollow fiber membrane obtained by drying the hollow fiber membrane except for the slab-like portion.

[Table] * Comparative example that cannot be evaluated due to small pore diameter 2 The spinning dope used in Example 3 was fed at 1.25 ml/min from the outer annular spinning spout, while the ratio of methanol and water was 101.1% by weight, and ammonia A mixed solution of 1.1% by weight of water and
Each sample was directly discharged at a rate of 1.77 ml/min into a mixed solution containing 101.1% by weight of acetone and water and 1.1% by weight of ammonia and water, and wound up at a speed of 11 m/min. Although the hollowing agent was a coagulable liquid with respect to the above-mentioned spinning dope, no microphase separation occurred. Thereafter, it was regenerated with a 2% by weight aqueous sulfuric acid solution, and then washed with water. Table 2 shows the results of measuring the physical properties and microstructure of the hollow fiber membrane after drying. Note that the average pore diameter was so small that no pores could be observed using a scanning electron microscope. Therefore, the average pore size is
It is less than 0.02 μm. Examples 7 to 13 The spinning dope prepared in Example 3 was fed at a rate of 1.25 ml/min from the outer annular spinning spout, while the ratio of acetone to water and the ratio of ammonia to water were
The mixed solution with the concentration shown in the table is 1.77
It was discharged at a rate of 11 m/min into a mixed solution having the acetone/water ratio and ammonia/water ratio shown in Table 3, respectively, and wound up at 11 m/min. In Examples 7 to 13, the transparent blue fibrous material immediately after discharge gradually turned white, and microphase separation occurred. Thereafter, it was regenerated with a 2% by weight aqueous sulfuric acid solution, and then washed with water. Table 3 shows the results of measuring the physical properties and microstructure of the hollow fiber membrane after drying.

【table】

[Table] Example 14 The spinning dope prepared in Example 3 was spun at 1.25 ml/min from the outer annular spinning spout, and the ratio of methyl ethyl ketone to water was 67.3% by weight, and the ratio of ammonia to water was 0.9. Mixed solution of 67.3% by weight of methyl ethyl ketone and water and 0.9% of ammonia and water by weight at 1.5ml/min from the central spinneret (outer diameter 0.4mmφ) as a hollow agent. (coagulant) and wound up at a speed of 10 m/min. In addition, the transparent blue-like fibrous material immediately after discharge gradually turns white, causing microphase separation,
Subsequently, coagulation occurred and the fiber shape was maintained. Thereafter, it was regenerated with a 2% by weight aqueous solution, and then washed with water. The moisture in the obtained hollow fibers was replaced with acetone, and then air-dried under tension. The physical properties and microstructure of the obtained hollow fiber membrane were measured. The results are shown in Table 4.

【table】

[Table] Example 15 Cellulose linter (average molecular weight 2.3×10 ⁵ ) was prepared by a known method, ammonia concentration 6.8 wt%,
It was dissolved at 8.5 wt% in a copper ammonia solution with a copper concentration of 3.1 wt%. This spinning stock solution was passed through the outer spinning spout (outside diameter 2 mmφ) of the annular spinning spout at 1.5 ml/min, while a mixed solution containing acetone and water at a ratio of 67.3 wt% and ammonia and water at a ratio of 0.9 wt% was spun into the hollow chamber. The agent is directly discharged from the central spinning spout (outer diameter 0.4 mmφ) at 2.0 ml/min into a mixed solution (coagulant) containing acetone and water at a ratio of 67.3 wt% and ammonia and water at a ratio of 0.9 wt%, respectively. The material was wound at a speed of 10 m/min. Thereafter, it was regenerated with a 2wt% sulfuric acid aqueous solution, and then washed with water. Water in the obtained hollow fiber membrane was replaced with acetone, and then air-dried under tension. 100 hollow fiber membranes obtained by the above method were molded into a module. Using the module, bovine serum was separated by vertical filtration. For comparison, a similar test was conducted using a cellulose acetate (CDA) hollow fiber membrane manufactured by Asahi Medical. The results are shown in Table 5. In addition, hollow fiber membranes obtained by the above method and
The strength and elongation of CDA hollow fiber membranes were measured. The results are also shown in Table 5. Table 5 shows that the hollow fiber membrane of the present invention has a higher filtration rate than the CDA hollow fiber membrane. Furthermore, the hollow fiber membrane of the present invention has greater strength and elongation than the CDA hollow fiber membrane. The water filtration rate of the hollow fiber membrane of the present invention is 725 ml/m ² , hr, mmHg,
The water filtration rate of CDA hollow fiber membrane is 450ml/m ² , hr, mm
It was Hg.

[Table] (F) Effects of the Invention The regenerated cellulose hollow fiber membrane of the present invention has a high average molecular weight, and therefore has high tensile breaking strength and elongation despite having a relatively large average pore diameter. It also has a large filtration capacity and excellent filtration performance. Moreover, the manufacturing method is stable and industrially advantageous. The regenerated cellulose hollow fiber membrane of the present invention can separate and remove target components in liquid or gas mixtures containing water.
For example, membranes for artificial kidneys, artificial livers, and artificial pancreases,
It is also useful as an ultrafiltration membrane. moreover,
It can be widely used in biological fields (medicine, biochemical industry) or food fields.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are scanning electron micrographs of the outer wall surface, intermediate portion, and inner wall surface of the regenerated cellulose hollow fiber membrane of the present invention.

Claims (1)

[Claims] 1. A regenerated cellulose hollow fiber membrane having an average molecular weight of 5 x ¹⁰⁴ to 5 x ¹⁰⁵ and having a hollow portion continuously extending through the entire fiber length, the hollow fiber membrane having a diameter of 0.02 to 1μ.
m of cellulose particles, and the hollow fiber membrane has pores with an average pore diameter of 0.02 to 10 μm on both the inner and outer wall surfaces, and the average pore diameter of the pores on the inner and outer wall surfaces is medium. A regenerated cellulose hollow fiber membrane having high mechanical properties characterized by having a larger average pore diameter than the average pore diameter of the membrane.