JPH02215470A - High-polymer film for blood treatment and blood treatment by using this film - Google Patents

Abstract

PURPOSE:To easily remove the deposits of high mol.wt. and to shorten the time for a treatment by incorporating the hollow fiber comprising a high-polymer film of rubber-like polymers, such as polyurethane, and urethane polymers, having excellent stretchability and high tensile strength into a module. CONSTITUTION:The polyurethane or urethane rubber which can stretch like rubber and has the high tensile strength is used as the film material. The high-polymer material of this high-polymer film once sticks to the film surface and closes the bores to lower the treatment capacity in an initial period of the blood treatment with this material, but the high-polymer material sticking to the film surface can be removed by shearing force or can be removed through the expanded fores as a flow passage is changed to a bypass and only the clogged part is pressurized. The flow passage and pressure are returned to the original state and the treatment is executed with the performance nearly equal to the initial performance after the removal of the high-polymer material. Since the regeneration of the film is executed in a short period of time in the intermediate stage of the blood treatment, the increase of the treatment time by the degraded treatment capacity is prevented. In addition, the reuse by this regeneration is possible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is useful for blood processing as hemodialysis membranes, hemofiltration membranes, plasma separation membranes, plasma component separation membranes, etc. used in the medical field for the treatment of renal failure patients. The present invention relates to a polymer membrane and a blood treatment method using the same.

[Conventional technology]

Blood processing can be divided into dialysis and filtration based on its principle. First, in dialysis, blood and dialysate are brought into contact with each other across a semipermeable membrane, and low molecular weight substances in the blood are removed from the system by utilizing the difference in concentration. On the other hand, filtration uses a membrane having pores of a specific size to screen based on the difference in molecular size. Depending on the size of the pores, this is used for various purposes such as separation of low-molecular weight proteins and high-molecular weight proteins, separation of high-molecular weight proteins, and separation of plasma components from blood.

These membranes are generally used in the form of hollow fibers, which are compact, lightweight, and highly efficient, and are bundled into modules. In addition, polymer materials with relatively poor elasticity are used as materials for these membranes due to their strength requirements, such as cellulose, polyvinyl alcohol, ethylene vinyl alcohol copolymer, polymethyl methacrylate, polycarbonate, and polysulfone. (edited by Junji Kawasaki et al., Advanced Membrane Separation Technology Handbook, pp. 67-73,
(Published in July 1988) [Problem to be solved by the invention] In conventional blood processing, whether by dialysis or filtration, molecules are basically sieved by pores, so particles larger than the pore size are Adhesion of permeating molecules to the membrane surface is unavoidable, and repeated occurrences cause pore blockage, resulting in a significant decrease in throughput. Therefore, a long time was required for blood processing, and reuse was also impossible.

Therefore, the purpose of the present invention is to eliminate the above-mentioned drawbacks of conventional polymer membranes, and to easily remove high molecular weight deposits that cause a reduction in throughput from the membrane surface by a simple operation of applying pressure.
Therefore, it is an object of the present invention to provide a polymer membrane for blood treatment and a blood treatment method that can shorten blood treatment time as a whole and also enable reuse of the membrane.

[Means to solve the problem]

In order to achieve the above object, the present invention uses a polymer that can expand and contract like rubber and has high tensile strength as a membrane material.

That is, according to the present invention, there is provided a polymer membrane for blood treatment that is formed from a rubbery polymer such as polyurethane or urethane-based polymer and has excellent elasticity and high tensile strength.

Further, according to the present invention, blood treatment is performed using a polymer membrane formed from a rubbery polymer such as polyurethane or urethane-based polymer, and when the amount of treatment has decreased to a predetermined value, the flow path is switched to bypass, and the above-mentioned Blood is circulated through the polymer membrane under pressure, and high molecular weight deposits are removed by shearing force caused by the pressure or by expansion of the pores in the membrane due to the pressure. After this operation is performed for a certain period of time, the flow path is closed. There is provided a blood processing method characterized by returning the blood to its original state and performing blood processing again.

Here, the polymer membrane is preferably formed into a hollow fiber shape and used by being incorporated into a module.

[Operation and mode of the invention]

As mentioned above, conventional membranes are made of relatively inelastic polymers such as cellulose, polyvinyl alcohol, polycarbonate, and polysulfone, so pore size fluctuations are small and are suitable for separating specific components. On the other hand, if a high molecular weight substance adheres to it, it becomes difficult to remove it.

Therefore, in the present invention, a polymer that is capable of rubber-like expansion and contraction and has high tensile strength, such as polyurethane or urethane rubber, is used as the membrane material. By using this polymer material, it has the same performance as conventional membranes at the initial stage of blood processing, but even when high molecular weight substances adhere to the membrane surface and the pores are blocked, the throughput decreases. By switching the flow path to a bypass and pressurizing only this part, it is possible to remove the high molecular weight substance adhering to the membrane surface by shearing force or by allowing it to pass through the enlarged pores. After the polymer substance is removed, the flow path and pressure can be returned to their original values, allowing processing to be performed with substantially the same performance as the initial stage. In this way, the membrane can be regenerated in a short period of time during blood processing, which prevents the conventional method from prolonging the process due to a decrease in processing capacity, and also enables reuse.

The material of the membrane is not particularly limited as long as it has excellent elasticity and high tensile strength, but polyurethane alone or a urethane-based polymer is generally used. These may be commercially available products or may be independently synthesized. When synthesized, it is obtained by polyaddition reaction of various glycols and diamines with diisocyanates such as tolylene diisocyanate, diphenylmethylene diisocyanate, hexamethylene diisocyanate, and naphthalene diisocyanate. The raw material monomer is not particularly limited, and has the required elasticity,
Various types and compositions are possible depending on the tensile strength.

Next, the polymer obtained here is dissolved in an aprotic solvent such as N-methylpyrrolidone, vinylpyrrolidone, dimethylsulfoxide, dimethylformamide, dimethylacetamide, etc. to obtain a dope solution. This dope solution is spun using a known hollow fiber spinning method. That is, a double circular tube nozzle was used to push the core liquid from the inside and the dope liquid from the outside vertically downward with a plunger at a constant speed, and the dope liquid was solidified by immersing it in a coagulation tank for a certain period of time. Then wind it onto a drum. This fiber is washed and heat treated to obtain a desired hollow fiber. From the experimental results, (a) the longer the chain length of the glycol monomer, the more the elongation of the hollow fiber increases, but the tensile strength decreases; and (b) the use of diamine or aromatic diamine with a short chain length as the monomer. . It was found that (c) the elongation of silicone-based glycols and silicone-based amines increases as the chain length increases.

This stretchable hollow fiber is incorporated into a module for use in hemodialysis or hemofiltration, depending on the size of its pores.

When this module is used to actually process blood, the throughput begins to gradually decrease as the process progresses. Therefore, when the blood pressure has decreased to a predetermined value, the flow path is switched to bypass, and the blood is circulated while being pressurized within a range that does not cause hemolysis. By this operation, a strong shearing force acts on the inner wall surface of the expanded hollow fiber, thereby removing high molecular weight deposits. At the same time, since the pore size on the inner wall surface of the hollow fiber is also expanded, high molecular weight deposits are removed even through these pores. As described above, by using a polymer having excellent elasticity and high tensile strength, it is possible to remove high molecular weight deposits by a simple operation of applying pressure. Next, after performing this operation for a certain period of time, the flow path is returned to its original state and blood processing is performed again, and the processing amount has recovered to approximately the same value as the initial value.

As described above, by performing blood processing using a module using hollow fibers made from a polymer having excellent elasticity and high tensile strength according to the present invention, it is possible to easily recover from a decrease in performance, thereby reducing blood processing time. It becomes possible to shorten the time and reuse the membrane module.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples.

Examples 1 to 3 Preparation of one polymer membrane hollow fiber Diphenylmethylene diisocyanate (MDI) and various polyols (polyethylene glycol or silicone oil modified with amino at both ends or silicone oil modified with hydroxyl groups at both ends)
These were combined and reacted at a molar ratio of 8:2 to synthesize polymers, which were used to produce hollow fibers. The polymer synthesis conditions were as follows: the reaction temperature was 60°C in all cases, the reaction time was 5 hours only in the case of amino-modified silicone oil, and 12 hours in the case of the others (catalyst nidibutyl tin laurate), and the solvent was tetrahydrofuran. The hollow fiber production conditions are that the dope solvent is N-methylpyrrolidone,
The coagulation liquid was water at room temperature for both the core liquid and the outer liquid, and spinning was carried out using a double circular tube nozzle using other conventional methods. The hollow fibers (inner diameter 0.6 m+s) obtained here all showed a maximum elongation of 300% or more, and returned to their original length when the stress was removed.

Comparative Example A commercially available polysulfone was spun under the same conditions as above. The obtained hollow fibers had an elongation of at most 20%, and in this case, even after stress was removed, they did not return to their original length.

Processing Example A mini-module of 250 mm x 15 mmφ was prepared using each of the hollow fibers obtained in Examples 1 to 3 and Comparative Example.

The inner wall surface area of each hollow fiber in the mini module is 200C.
-It was. Add 4 ce/ rabbit blood to each module.
Charging was continued for 60 minutes at a sending pressure of 100 g and 11 g. Thereafter, the delivery pressure was increased to 500+amt 1 g for 1 minute (blood flow rate was 4 cc/min). Thereafter, the module was removed from the flow path and washed with 1000 cc of physiological saline.

After air-drying these modules at room temperature for 24 hours, the weight of solid matter adhering to the inner wall surface of the hollow fibers was measured.

The results are shown in the table below.

From the above results, it can be seen that in the case of hollow fibers with high elasticity, the amount of solid matter attached is small. This is considered to be because by increasing the pressure inside the hollow fiber, shearing force acts on the membrane surface, and at the same time, the pores expand, thereby removing solids to the outside.

〔Effect of the invention〕

As described above, the polymer membrane for blood treatment of the present invention is made from a rubbery polymer such as polyurethane or urethane-based polymer, which has excellent elasticity and high tensile strength. When blood processing is carried out by incorporating hollow fibers of polymer membranes into modules, even if the throughput decreases due to adhesion of high molecular weight substances to the membrane surface during treatment, high molecular weight substances can be easily added by the simple operation of pressurization. The kimono can be removed, thus reducing the overall processing time and allowing the polymer membrane to be reused.

Claims (4)

[Claims] (1) A polymer membrane for blood treatment that has excellent elasticity and high tensile strength and is formed from a rubbery polymer such as polyurethane or urethane-based polymer. (2) The polymer membrane for blood treatment according to claim 1, wherein the polymer membrane has a hollow fiber shape. (3) Performing blood treatment with a polymer membrane made from rubber-like polymers such as polyurethane and urethane-based polymers,
When the throughput has decreased to a predetermined value, the flow path is switched to bypass, blood is circulated under pressure through the polymer membrane, and the high molecular weight is increased by the action of shear force due to the pressurization or by the expansion of the pores in the membrane due to the pressurization. A blood processing method characterized in that after removing deposits and performing this operation for a certain period of time, the flow path is returned to its original state and blood processing is performed again. (4) The blood processing method according to claim 3, wherein the polymer membrane is a hollow fiber, which is bundled into a module.