JPH0380528B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a hollow fiber membrane composed of a high-molecular polymer.
This invention relates to a hollow fiber membrane winding body used in a dialysis device. Conventional technology In recent years, research has been conducted on treatment methods that use porous membranes to separate specific components from liquid mixtures such as seawater, industrial wastewater, sewage wastewater, and blood, depending on their use and purpose, and have led to the production of pure water and sterile water. It is applied to blood purification, food concentration, etc. When actually using porous membranes for these applications, the inlet and outlet for the liquid to be treated, the outlet for the permeate, and the inlet and outlet for the dialysate must be set in various ways depending on the application. It takes the form of a so-called module, in which a porous membrane is housed in a combined container. In this case, it is useful to use a porous membrane in the form of hollow fibers because a wide membrane area can be utilized. A variety of polymer-based materials have already been put into practical use as membranes with functions such as separation, concentration, and dialysis, but cellulose ester-based materials in particular can be fabricated using a wide variety of membrane methods. It is a useful material that can produce films with a wide range of functions depending on the film forming method. As mentioned above, the hollow fiber membrane is used in the form of a module, and the larger its performance, especially its ultraspeed and dialysis rate, the more compact it can be.
In particular, there is a strong demand for miniaturization of hollow fiber hemodialysis modules used to rescue patients with renal failure from the viewpoint of reducing the amount of extracorporeally circulating blood. In addition, along with this, an increase in ultra-limit overspeed and a decrease in film thickness are required. Based on such requests, for example,
Although various efforts have been made as seen in Publication No. 56-307, a module with sufficient characteristics has not yet been obtained. The reason for this is that in order to obtain a hollow fiber membrane with a high ultimate overspeed, it is necessary to increase the porosity of the membrane, which results in a decrease in the mechanical strength of the hollow fiber. This is unavoidable, and the same can be said when trying to make the film thinner. Therefore, when assembling such hollow fiber membranes into modules, they must be handled with extreme care, as even the slightest trouble can damage the hollow fiber membranes.
During use, leakage occurs from the damaged area, and the hollow fiber membrane's original functions are not fully demonstrated.
If used as a module for an artificial kidney, it may lead to a situation in which human life is lost. Purpose of the Invention The present inventors have completed the present invention as a result of intensive research to solve such problems. That is, the present invention reduces the water permeation rate at 37°C in a hollow fiber ultrafiltration membrane to L (ml/m ²
mmHghr), the yield strength in tension is S (g weight)
When, during membrane spinning, the ratio of the number of hollow fibers (A) represented by the following general formula (1) and hollow fibers (B) represented by general formula (2) as shown in general formula (3) is This is a hollow fiber-shaped dialysis membrane wound body characterized in that it is wound up with doubling yarns. L≧S, L≧15, L+S≧30 (1) L≦20, S≧17 (2) S _A・n ^A +S _B・n ^B ≧18 (n ^A +n ^B ), 0.34≧n ^B /n ^A ≧0.14 8≧n ^A +n ^B (3) (where n ^A is the number of hollow fibers (A), n ^B is the number of hollow fibers (B). S _A is the number of hollow fibers (A), and S _B is the number of hollow fibers (A). This is the yield strength of the hollow fiber (B).) Constitution of the Invention The hollow fiber ultrafiltration membrane as used in the present invention is a hollow fiber porous membrane whose main component is a high molecular weight polymer, such as polyethylene, polypropylene, polychlorinated These materials include vinylene polyvinyl acetate, polyester, nylon, cellulose, cellulose ester, polyvinyl alcohol, polymethyl methacrylate ethylene-vinyl acetate copolymer, and among others, cellulose ester materials are preferred for the reasons mentioned above. The present invention also includes cases where these materials are used in combination and fillers and additives are used. In obtaining the hollow fibers of the present invention, all conventional membrane-spinning methods can be employed. That is, melt spinning, dry spinning, wet spinning, and semi-dry/wet spinning (air gap spinning) can all be used. After membrane-forming and spinning, the wound body of the present invention is unwound and unwound during module production, converged to a predetermined length and shape, and then stored in a container and adhesively fixed with its end opened according to the purpose. To obtain the present invention, hollow fibers (A) and hollow fibers (B) are combined within the range of general formula (3) and wound. There are two methods: obtaining yarn (A) and hollow fiber (B), doubling and winding the yarn, and using different spinning methods to obtain hollow fiber (A) and hollow fiber (B), but the method is limited to either method. It's not a thing. Specifically speaking, hollow fibers (A) and (B) are obtained by a wet spinning method, hollow fibers (A) are obtained by a method of doubling and winding, and hollow fibers (A) are obtained by a melt spinning method, and hollow fibers (A) are obtained by a dry spinning method. There are methods such as obtaining B) and winding up the yarn, but the method is not limited to these methods. For example, when employing the same spinning method, the same spinning process can be employed by changing the thickness of the hollow fibers (A) and hollow fibers (B). In addition, when using a wet spinning method, multiple spinning stock solutions with different compositions are discharged from separate nozzles, subjected to the same coagulation, water washing, and post-processing, and then wound up, and immediately before winding up the doubling solution. is advantageous, but is not limited to this. Although the present invention is limited to the ranges of formulas (1), (2), and (3) described above, when creating a module using only hollow fibers outside the range of formula (1), the ultimate overspeed of the module is It is too small to achieve the purpose of the present invention. On the other hand, when only the hollow fiber membrane (A) represented by formula (1) is used, it is not practical due to its poor mechanical properties and is easily damaged during module production. For example, even if it were possible to manufacture a module, using such hollow fibers would only be possible if the hollow fibers had a large membrane thickness, and the number of hollow fibers to be housed in the module case would be reduced, resulting in a small, high-performance module. This deviates from the purpose of the present invention, which is to provide the following. When only the hollow fibers (B) represented by formula (2) are used, the hollow fibers are less likely to be damaged during module production, but the ultimate overspeed is small, which is contrary to the purpose of the present invention. A wound body that achieves the object of the present invention can be obtained only when the hollow fibers (A) and hollow fibers (B) are combined and wound at the ratio shown by formula (3). In other words, if S _A・n ^A + S _B・n ^B < 18 (n ^A + n ^B ), the hollow fiber membrane is likely to be damaged during module manufacture;
Further, in the case of 0.34<n ^B /n ^A or 0.14>n ^A /n ^B , the mechanical properties and the extreme overspeed are unbalanced, and a module that meets the purpose of the present invention cannot be obtained. If n ^A + n ^B > 8, the hollow fibers are likely to be damaged during spinning and winding, which is undesirable. Effects of the Invention The thus-obtained wound body of the present invention is a compact module that exhibits high performance, and is extremely useful as it is less likely to be damaged during steps such as release and casing adhesion related to module production. Examples Next, the contents of the present invention will be explained in detail by examples. Comparative Example 1 A spinning dope consisting of 26 parts by weight of cellulose diacetate, 60 parts by weight of N-methyl-2-pyrrolidone, and 14 parts by weight of ethylene glycol was discharged from an 8-hole double tube nozzle using liquid paraffin as a core material.
After passing through the hollow part for 0.01 seconds, N-methyl-2-
It was introduced into a coagulation bath consisting of 21 parts by weight of pyrrolidone, 4 parts by weight of ethylene glycol, and 75 parts by weight of water, passed for 3.9 seconds, then passed through a water washing bath, and further concentrated to 49 parts by weight.
% glycerin aqueous solution for 5.1 seconds, and after passing through a zone with an ambient temperature of 70°C, the yarn was doubled.
It was wound onto a bobbin at a speed of m/min. In this process, the amount of core material discharged was always constant so that the inner radius of the yarn obtained was 200 μm. On the other hand, by changing the amount of dope discharged, yarns with a film thickness of 5 μm to 27 μm were obtained.
The obtained thread was released, the internal liquid was removed, it was stored in a cylindrical case, and both ends were glued with resin and cut open to create a dialysis module, and the water permeation rate was measured. The results are shown in Table 1 along with other properties of the hollow fiber.
Shown below. Comparative Example 2 The same operation as in Comparative Example 1 was carried out using a spinning dope consisting of 33 parts by weight of cellulose diacetate, 54 parts by weight of N-methyl-2-pyrrolidone, and 13 parts by weight of ethylene glycol. The results are shown in Table-1. Example A membrane was formed and spun using the method of Comparative Example 1 using an 8-hole or 4-hole nozzle and using the dope having the composition used in Comparative Example 1 and Comparative Example 2 in combination. The same operation as in Comparative Example 1 was performed using the obtained rolled body. The results are shown in Table-1. Comparative Example 3 The same operation as in Example was carried out by changing the proportion of the dope used. The results are shown in Table-1. Comparative Example 4 The same operation as in Comparative Example 2 was attempted using a 12-hole nozzle, but when the winding body was released, there were many damaged parts of the hollow fibers, making it impossible to put it to practical use. It can be seen from Table 1 that the present invention is extremely useful.

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Claims (1)

[Claims] 1. When the water permeation rate at 37°C in a hollow fiber ultrafiltration membrane is L (ml/m ² mmHghr), and the yield strength under tension is S (g weight), During spinning, the hollow fibers (A) represented by the following general formula (1) and the hollow fibers (B) represented by the following general formula (2) are mixed in the ratio shown by the following general formula (3) with respect to their number. A hollow fiber membrane wound body characterized by being wound. L≧S, L≧15, L+S≧30 (1) L≦20, S≧17 (2) S _A・n ^A +S _B・n ^B ≧18 (n ^A +n ^B ), 0.34≧n ^B /n ^A ≧0.14, 8≧n ^A +n ^B (3) (where n ^A is the number of hollow fibers (A) n ^B is the number of hollow fibers (B). S _A is the number of hollow fibers (A), S _B is the number of hollow fibers (A) 2. The wound body according to claim 1, wherein the hollow fiber is mainly composed of a cellulose ester material.