JPH10165786A - Washing of hollow yarn membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively remove an oleophilic liquid within hollow yarns and to prevent the deterioration of a housing case of hollow yarn bundles by wash ing the interiors of hollow yarns with a washing agent containing perfluorohydrocarbon and chlorofluorinated hydrocarbon of which the ozono sphere disruption coefficient is a specific value or less. SOLUTION: As perfluorohydrocarbon used in this washing agent, fluoride of 5-8C aliphatic saturated hydrocarbon, that is, perfluoropentane, perfluorooctane or perfluorohexane is designated and perfluorohexane is especially pref. An ozonosphere disruption coefficient of chlorofluorinated hydrocarbon is 0.2 or less and dichloropentafluoropropane is designated. The vol. ratio of perfluorohydrocarbon and chlorofluorinated hydrocarbon contained in this washing agent is about 30/ 70-70/30, especially pref., about 40/60-60/40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a hollow fiber membrane used for hemodialysis, and more particularly to a method for cleaning and removing a core liquid from a hollow fiber using a lipophilic liquid such as liquid paraffin as a core liquid. The present invention relates to a method for cleaning the inside of a hollow fiber with a cleaning agent comprising a mixture of a specific chlorofluorohydrocarbon and a perfluorohydrocarbon.

[0002]

2. Description of the Related Art A generally practiced method for producing a hollow fiber membrane is to use a double tube nozzle, extrude a solution of a fiber-forming polymer from an annular portion of the nozzle, and simultaneously flow the solution as a core liquid from a central portion. This is a method for producing a hollow fiber membrane by discharging a lipophilic liquid such as paraffin, forming it into a hollow fiber shape, and forming micropores in the membrane. Next, after washing the hollow fiber membrane with water, the pores of the hollow fiber membrane are impregnated with glycerin using a glycerin-containing aqueous solution, and wound around a bobbin. Thereafter, a fiber bundle obtained by bundling the hollow fibers is loaded into a plastic case to form a hollow fiber membrane module.

[0003] Before or after the molding of the hollow fiber membrane module, the hollow fiber membrane has conventionally been washed with ether, chlorofluorocarbon or the like. However, ether has a low boiling point and a low flash point, so there is a danger of fire.In addition, when washing with ether, glycerin impregnated inside the hollow fiber is washed away, and the hollow fiber after washing is removed. There was a disadvantage that the water permeability of the yarn membrane was reduced. Further, ether easily generates a peroxide by heating, and this peroxide has an adverse effect on the hollow fiber, sometimes deteriorating the hollow fiber. On the other hand, the method of washing with chlorofluorocarbons such as trichlorotrifluoroethane causes the ozone layer destruction, which causes deterioration of the global environment, because the ozone depletion coefficient of trichlorotrifluoroethane is as high as 0.8. It is subject to regulations.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have made intensive studies to overcome these disadvantages of the prior art and arrived at the present invention. That is, an object of the present invention is to selectively remove a lipophilic liquid existing in a hollow fiber without removing glycerin, and to reduce flammability and destruction of the global environment without deterioration of a case accommodating the hollow fiber bundle. An object of the present invention is to provide a cleaning method that solves the problem.

[0005]

That is, the present invention provides a method for washing and removing a core liquid from a hollow fiber spun using a lipophilic liquid as the core liquid. And a method of cleaning a hollow fiber membrane in which the inside of the hollow fiber is cleaned with a cleaning agent containing perfluorohydrocarbon. The present invention also relates to the method for cleaning a hollow fiber membrane, wherein the perfluorohydrocarbon is a fluoride of an aliphatic saturated hydrocarbon having 5 to 8 carbon atoms. Further, the present invention provides the method for cleaning a hollow fiber membrane,
This is a method for cleaning a hollow fiber membrane in which chlorofluorocarbon is dichloropentafluoropropane.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The lipophilic liquid used as the core liquid includes liquid paraffin, isopropyl myristate, etc., which has a good affinity for the detergent used in the present invention and can be dissolved at an arbitrary ratio. I do. Examples of the case material include polystyrene, acrylic resin, and boronic acid.
And the like. After removing most of the lipophilic liquid from the core of the hollow fiber by physical means such as natural dropping or centrifugation of the hollow fiber membrane containing the lipophilic liquid in the core of the hollow fiber, the remaining lipophilic liquid is removed. The cleaning is performed using the cleaning liquid used in the present invention.

[0007] As a cleaning agent for cleaning the core liquid of the hollow fiber,
Dissolves in lipophilic liquid as core liquid, does not dissolve in hollow fiber and glycerin, does not cause deterioration of plastic case by solvent, has low risk of ignition, and does not cause ozone layer depletion problem on earth. Those satisfying such conditions are preferable.

The chlorofluorocarbon used in the cleaning agent of the present invention is a chlorofluorocarbon having an ozone depletion potential of 0.2 or less. Such chlorofluorocarbons include dichloropentafluoropropane. The ozone depletion potential is the destructive power of the ozone layer when trichlorofluoromethane is set to 1.0. Dichloropentafluoropropane has an ozone depletion potential of 0.02, and does not cause social problems such as environmental destruction. The perfluorohydrocarbon used in the cleaning agent of the present invention includes
Examples thereof include fluoropentane, perfluorooctane, and perfluorohexane, and particularly preferred is perfluorohexane.

The volume ratio of the perfluorohydrocarbon to the chlorofluorohydrocarbon contained in the cleaning agent of the present invention is from 30/70 to
A range of 70/30, especially 40/60 to 60/40 is preferred. If the volume ratio of the perfluorohydrocarbon is less than 30%, the plastic case tends to cause solvent deterioration. If the volume ratio exceeds 70%, the solubility in the lipophilic liquid decreases, and the detergency decreases. Tend to.

The method of washing and removing the lipophilic liquid contained in the core of the hollow fiber with the cleaning agent of the present invention is not particularly limited. That is, there are a method of immersing the hollow fiber membrane in the cleaning agent, a method of allowing the cleaning liquid to flow into the inside of the hollow fiber membrane and allowing it to fall naturally, and a method of passing the cleaning liquid through the inner surface or inner and outer surfaces of the hollow fiber. Further, the washing method of the present invention can be used for washing the hollow fiber bundle in a state before the hollow fiber bundle is incorporated in the case or in the state of the module after the hollow fiber bundle is incorporated in the case. May be. Further, the washing temperature is usually at room temperature, but may be carried out in a heated state of 50 ° C. or lower for improving the washing property. Drying after washing of the lipophilic liquid contained in the core of the hollow fiber is performed by aeration, centrifugal operation, drying under reduced pressure, and the like.

[0011]

EXAMPLES Examples of the present invention will be described below with reference to examples.

Example 1 Cellulose using liquid paraffin as a core liquid
A hollow fiber of striacetate was spun. Next, the hollow fiber is washed with water and then treated with a 50% glycerin aqueous solution to fill the pores of the hollow fiber with glycerin and dried. The obtained hollow fibers are bundled into 1,000 bundles, and the hollow fiber bundles are loaded into a case for hemodialysis machine made of polycarbonate, and both ends of the hollow fiber bundles are fixed with urethane adhesive to make a module. Was manufactured. After removing the liquid paraffin as much as possible by gravity, a mixture of perfluorohexane and dichloropentafluoropropane (volume ratio 50/50) was passed through the hollow fiber for 10 minutes.

As a result, glycerin inside the hollow fiber was not removed, and only liquid paraffin remaining inside the hollow fiber could be removed. After washing, drying was performed by passing dry air at 60 ° C. for 10 minutes. As a result, a mixture of perfluorohexane and dichloropentafluoropropane was removed, and a hemodialyzer having excellent membrane permeability was obtained.

[0013]

Comparative Example 1 When washing was performed using ethyl alcohol instead of the mixture of perfluorohexane and dichloropentafluoropropane used as the cleaning agent in Example 1, glycerin inside the hollow fiber was removed. As a result, a hollow fiber membrane having significantly reduced membrane performance was obtained.

[0014]

COMPARATIVE EXAMPLE 2 Instead of a mixture of perfluorohexane and dichloropentafluoropropane used as a cleaning agent in Example 1, cleaning was performed using only a dichlorofluoropropane solution. The hemodialyzer case was cracked and could not be washed.

When washing was performed using only the perfluorohexane solution instead of the mixture of perfluorohexane and dichloropentafluoropropane used as the cleaning agent in Example 1, the fluid used as the core solution was washed. Paraffin was not sufficiently removed from the hollow fiber membrane.

[0016]

According to the method of the present invention, the lipophilicity contained in the core during the production of the hollow fiber was obtained without removing the glycerin filled in the hollow fiber as a pore retaining agent for the hollow fiber membrane. The liquid can be washed away. Further, the cleaning agent used in the present invention has no risk of destruction of the ozone layer and ignition during the cleaning process, and prevents deterioration of the performance of the hollow fiber membrane due to the cleaning operation and solvent deterioration of the case accommodating the hollow fiber bundle. be able to.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 13/08

Claims (3)

[Claims] When a core liquid is washed and removed from a hollow fiber spun using a lipophilic liquid as a core liquid, it contains perfluorohydrocarbon and fluorinated hydrocarbon having an ozone layer destruction coefficient of 0.2 or less. A method for cleaning a hollow fiber membrane, comprising cleaning the inside of the hollow fiber with a cleaning agent. 2. The perfluorohydrocarbon has 5 to 8 carbon atoms.
The method for cleaning a hollow fiber membrane according to claim 1, wherein the method is a fluoride of an aliphatic saturated hydrocarbon. 3. The method for cleaning a hollow fiber membrane according to claim 1, wherein the chlorofluorohydrocarbon is dichloropentafluoropropane.