Hydrophilic material and process for producing the same

Abstract

The present invention relates to a hydrophilic substance production method characterized in that polyvinylpyrrolidone-containing material wetted with an aqueous solution of a cationic polymer is treated with radiation. The invention makes it possible to produce material for blood treatment that prevents adsorption of blood platelets.

Description

[0001] The present invention relates to a hydrophilic substance and a production method thereof, particularly to a hydrophilic substance with resistance to adsorption of blood platelets, and a production method thereof. Consisting of a cationic polymer component, it is suited to uses that take advantage of good features of a cationic polymer.PRIOR ART[0002] A variety of polymer materials are presently used in the medical field. When used in artificial blood vessels, catheters, artificial kidneys, or other products that directly contact with blood, serious problems can arise with adhesion of blood components, such as plasma protein and blood platelets, and resultant formation of blood clots. A separation membrane used for blood purification, for example, may suffer problems with blood residue on the membrane that results from the activation of blood platelets. To avoid such blood residue, hydrophilic substances that do not adsorb blood platelets significantly have been strongly sough...

AI Technical Summary

Benefits of technology

[0004] Blending with a hydrophilic polymer, such as polyvinylpyrrolidone, alone is not significantly effective in controlling the activation of blood platelets. The present invention aims to eliminate the defect of conventional materials to provide a method to produce a hydrophilic substance that does not suffer heavy adhesion of blood platelets.

[0017] The hydrophilic substance of the invention is not limited to particular forms, and may be used in the form of a tube, bead, fabric, nonwoven fabric, cut fiber, flat membrane, or hollow fiber membrane. Said hydrophilic substance may also be molded into a specific form after being dissolved in a solvent, or may be used as coatings. Hollow fiber membrane, however, is preferred considering that said substance may be used to perform the function of an artificial kidney and should have a large surface area for contact with blood to achieve a high processing efficiency.

[0022] Production of a membrane from said feedstock is not limited to particular methods, and any known method can be used. A useful method is to discharge said feedstock from a double-annular nozzle with a liquid being injected into the inside, allow the product to run through a dry step, and then feed it to a solidification bath. In doing this, as the humidity in the dry step can have significant influence, excessive densification likely to be caused by drying in the neighborhood of the outer surface may be prevented by supplying water through the outer surface of the membrane while it is running through the dry step, in order to provide a product that is low in permeability and diffusion resistance when used for dialysis. If the relative humidity is too high, however, water would act to form a dense layer on the outer surface, which will result in a product that is high in permeability and diffusion resistance when used for dialysis. To avoid this, the relative humidity in the dry step should preferably be in the range of 60% to 90%. To suit the process, the liquid to be injected should preferably consist mainly of the solvent that is used to prepare the feedstock. When dimethylacetamide is used, for instance, the liquid to be injected should preferably be an aqueous solution of 45 wt % to 80 wt %, more preferably 60 wt % to 75 wt %.

[0027] Such cationic polymers as branched polyethyleneimines and dialkylaminoethyl dextrans are preferred because of their low toxicity, high availability and easy handling.

[0031] Thus, irradiating polyvinylpyrrolidone-containing material wetted with a solution of a cationic polymer is thought to act to introduce said cationic polymer into said polyvinylpyrrolidone-containing material. Preventing excessive crosslinking from taking place in said polyvinylpyrrolidone while maintaining the hydrophilic properties of said polyvinylpyrrolidone results in low adhesiveness to blood platelets.

[0035] Hydrophilic material produced by the production method of the present invention can serve effectively for blood purification.

Problems solved by technology

Blending with a hydrophilic polymer, such as polyvinylpyrrolidone, alone is not significantly effective in controlling the activation of blood platelets.

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