JPH10225627A - Method for cleaning hollow-fiber membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively remove oleophilic liq. in a hollow fiber along with refuse, etc., while leaving glycerine, etc., by cleaning the inside of the hollow fiber with a detergent consisting essentially of the aliphatic hydrocarbon having specified b.p. and flash point. SOLUTION: Most of an oleophilic liq. is removed from the core of the hollow fiber of a hollow-fiber membrane contg. the oleophilic liq. such as isopropyl myristate in the hollow fiber by a physical means, e.g. natural falling and centrifugation, and then the remaining oleophilic liq. is cleaned off. Since at least one kind of aliphatic hydrocarbon selected from the group of n-nonane, n-decane and their isomer having 110-240 deg.C b.p. and >=21 deg.C flash point is used as the main component to clean the inside of the hollow fiber, the destruction of the ozone layer or ignition during the cleaning are not caused, the hollow- fiber membrane is deteriorated, the hollow-fiber bundle case is not deteriorated by solvent, and the oleophilic liq. contained in the core is cleaned off during the production of the hollow fiber without removing the glycerine incorporated into the membrane as a pore holding agent.

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 a hollow fiber membrane for cleaning the inside of the hollow fiber with a cleaning agent mainly containing a specific aliphatic hydrocarbon. It relates to a cleaning method.

[0002]

2. Description of the Related Art A generally practiced method for producing hollow fibers is to use a double-tube nozzle, extrude a solution of a fiber-forming polymer from an annular portion of the nozzle, and at the same time, use a liquid paraffin as a core liquid from a central portion. Discharge lipophilic liquids such as
Alternatively, a method of supplying a gas such as nitrogen to form a hollow fiber and form micropores in the hollow fiber membrane to produce a hollow fiber. Next, the hollow fiber is washed with water and then impregnated with glycerin in the pores of the hollow fiber membrane using an aqueous glycerin-containing 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 formation of the hollow fiber membrane module, in order to remove the core liquid inside the hollow fiber or dust, dust, dirt and the like existing inside the hollow fiber, conventional ether, chloride fluoride and the like are used. Cleaning of hollow fiber membranes with fluorinated hydrocarbons and the like has been performed. However, ether has a low boiling point and a low flash point, so there is a risk of fire.In addition, when washing with ether, glycerin impregnated in the pores of the hollow fiber membrane is washed off and removed. However, there is a disadvantage that the water permeability of the hollow fiber membrane is 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, a method of performing a cleaning treatment with a chlorofluorocarbon such as trichlorotrifluoroethane causes ozone depletion, which causes deterioration of the global environment because the ozone depletion coefficient of trichlorotrifluoroethane is as high as 0.8. It is regulated as specified CFC. There are also chlorofluorocarbons such as dichloropentafluoropropane, which have a low ozone destruction coefficient of 0.02. However, this compound not only causes the plastic case containing the hollow fiber bundle to degrade the solvent, but also causes the hollow fiber membrane to deteriorate. Glycerin impregnated into the pores had a disadvantage of being washed away.

[0005]

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 remove dust, dirt, dust, and the like present inside the hollow fiber, and to remove glycerin, polyethylene glycol, and the like impregnated in the pores of the hollow fiber membrane without removing the inside of the hollow fiber. An object of the present invention is to provide a cleaning method which selectively removes an existing lipophilic liquid and eliminates the problem of flammability and destruction of the global environment without deteriorating the case housing the hollow fiber bundle.

[0006]

That is, the present invention provides a method for cleaning the inside of a hollow fiber used for hemodialysis, which has a boiling point of
This is a method for cleaning a hollow fiber membrane, which comprises cleaning the inside of a hollow fiber with a cleaning agent mainly containing an aliphatic hydrocarbon having a flash point of 21 ° C. or higher at 110 to 240 ° C. Further, the present invention is the method for cleaning a hollow fiber membrane, wherein the core liquid is removed from the hollow fiber impregnated with a lipophilic liquid as a core liquid inside the hollow fiber in the method for cleaning a hollow fiber membrane. . Furthermore, the present invention provides the method for cleaning a hollow fiber membrane, wherein the aliphatic hydrocarbon is at least one compound selected from the group consisting of nonane, decane, undecane and dodecane.

[0007]

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 inside the hollow fiber, the remaining lipophilic liquid is removed. The cleaning is performed using the cleaning liquid used in the present invention.

[0008] As a cleaning agent for cleaning the inside 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 cleaning agent used in the present invention has a boiling point of 110
To 240.degree. C., preferably 134 to 179.degree. C. and a flash point of 21.degree. C. or more, preferably 23 to 56.degree. If the boiling point is lower than 110 ° C, the flash point tends to decrease, and the risk of ignition tends to increase significantly.
If the temperature exceeds 240 ° C., the volatility tends to decrease, and removal by aeration drying or drying under reduced pressure tends to be difficult. Examples of the aliphatic hydrocarbon include at least one compound selected from the group consisting of n-nonane, n-decane, n-undecane, n-dodecane, and isomers thereof.

[0010] The method of washing and removing dust, dust, dirt or lipophilic liquid existing inside the hollow fiber with the cleaning agent mainly containing aliphatic hydrocarbon of the present invention is not particularly limited. That is, a method in which the hollow fiber membrane is immersed in the cleaning agent, a method in which the cleaning liquid flows into the hollow fiber membrane and then falls naturally.
There is a method in which the cleaning liquid is passed through the inner surface or inner / outer surface of the hollow fiber. In this case, the speed of the washing solution is 100-1000ml
/ Min / module is preferred. 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 inside the hollow fiber is performed by aeration, centrifugation,
Drying under reduced pressure is performed.

An embodiment of the present invention will be described below with reference to an embodiment.

Example 1 Cellulose using liquid paraffin as a core liquid
Spinning a hollow fiber of striacetate (pore diameter of hollow fiber)
70Å). Next, the hollow fiber is washed with water and then treated with a 50% by weight aqueous glycerin solution to fill the pores of the hollow fiber with glycerin and dried (glycerin amount: 10 g / module). The obtained hollow fibers are bundled into 1,000 bundles, the hollow fiber bundles are loaded inside a case for hemodialysis machine made of polycarbonate, and both ends of the hollow fiber bundles are fixed with urethane adhesive to form a module. Manufactured. After removing the liquid paraffin as much as possible in advance by gravity, the nonane isomer mixture (boiling point 134
138138 ° C., flash point 23 ° C.) for 10 minutes. Table 1 shows the lipophilic liquid amount, residual solvent amount, glycerin amount, and membrane performance of the membrane. As is clear from Table 1, glycerin in the pores of the hollow fiber membrane was not removed, and only the liquid paraffin remaining inside the hollow fiber could be removed. Then, at 60 ° C
The dried air was passed through for 10 minutes to remove the nonane isomer mixture, and a hemodialyzer with excellent membrane permeability was obtained.

[0013]

[Table 1]

The measuring method of the measuring items in Table 1 is as follows. [Amount of lipophilic liquid: mg / module] A 40% aqueous ethanol solution was circulated inside and outside the module hollow fiber at 37 ° C for 5 hours, and the amount of lipophilic liquid in the aqueous solution was measured by gas chromatography. [Residual solvent amount: mg / module] Example 1-7 A 40% aqueous ethanol solution was circulated inside and outside the module hollow fiber at 37 ° C for 5 hours, and the residual solvent amount in the aqueous solution was measured by gas chromatography. Comparative Example 1-2 A module was placed in a closed container and heated at 75 ° C. for 3 hours. The amount of the residual solvent in the gas in the closed container was measured by gas chromatography. [Amount of glycerin: g / module] An aqueous solution of 40% ethanol was circulated at 37 ° C. for 5 hours inside and outside the module hollow fiber, and the amount of glycerin in the aqueous solution was measured by high performance liquid chromatography. [Leak] After applying a pressure of 0.5 atm to the dialysate side of the module for 5 seconds, the module was submerged in water and observed for the occurrence of bubbles. [UFR, water permeability: ml / hr.mmHg · m ² ] The measurement was performed according to the UFR measurement method 4C method (STOP method) of “Dializer performance evaluation standard” (Japan Society for Artificial Organs).

[0015]

Example 2 In place of the nonane isomer mixture used as a detergent in Example 1, n-nonane (boiling point 151 ° C.,
(Flash point 31 ° C.) at normal temperature for 10 minutes at a rate of 500 ml / min. Table 1 shows the lipophilic liquid amount, residual solvent amount, glycerin amount, and membrane performance of the membrane. As is clear from Table 1, glycerin in the pores of the hollow fiber membrane was not removed, and only the liquid paraffin remaining inside the hollow fiber could be removed. Next, the module was aerated with dry air at 40 ° C. for 5 minutes, and then dried by passing normal temperature air for 5 minutes. As a result, n-nonane was removed and a hemodialyzer with excellent membrane permeability was obtained. .

[0016]

Example 3 In place of the nonane isomer mixture used as a detergent in Example 1, n-decane (boiling point 174 ° C.,
(Flash point 46 ° C.) at room temperature for 10 minutes at a rate of 500 ml / min. Table 1 shows the lipophilic liquid amount, residual solvent amount, glycerin amount, and membrane performance of the membrane. As is clear from Table 1, glycerin in the pores of the hollow fiber membrane was not removed, and only the liquid paraffin remaining inside the hollow fiber could be removed. Next, the module was aerated with dry air at 60 ° C. for 10 minutes, and allowed to stand at a reduced pressure of 0.8 mmHg for 20 minutes to perform drying.As a result, n-decane was removed and a hemodialyzer having excellent membrane permeability was obtained. Obtained.

[0017]

Example 4 A dodecane isomer (bp 179) was used in place of the nonane isomer mixture used as a detergent in Example 1.
(Flash point: 56 ° C) at room temperature at a rate of 500 ml / min for 10 minutes. Lipophilic liquid amount of membrane, residual solvent amount, glycerin amount,
Table 1 shows the film performance. As is clear from Table 1, glycerin in the pores of the hollow fiber membrane was not removed, and only the liquid paraffin remaining inside the hollow fiber could be removed. Next, the module was aerated with dry air at 60 ° C. for 10 minutes, and allowed to stand at a reduced pressure of 0.8 mmHg for 20 minutes to perform drying.As a result, dodecane isomers were removed, and hemodialysis with excellent membrane permeability was performed. A bowl was obtained.

[0018]

Comparative Example 1 Washing was carried out using ethyl alcohol instead of the nonane isomer mixture used as the detergent in Example 1. Table 1 shows the lipophilic liquid amount, residual solvent amount, glycerin amount, and membrane performance of the membrane. As is clear from Table 1, even the glycerin inside the hollow fiber was removed, and a hollow fiber membrane having significantly reduced membrane performance was obtained.

[0019]

Comparative Example 2 Washing was carried out using dichlorofluoropropane instead of the nonane isomer mixture used as a detergent in Example 1. Table 1 shows the lipophilic liquid amount, residual solvent amount, glycerin amount, and membrane performance of the membrane. As is clear from Table 1, the case for the hemodialyzer made of polycarbonate was cracked and could not be washed.

[0020]

Example 5 The module obtained by washing in Example 2 was replaced with an aqueous glycerin solution. The amount of lipophilic liquid in the membrane,
Table 1 shows the residual solvent amount, glycerin amount, and membrane performance. Table 1
As is clear from the above, a hemodialyzer excellent in membrane permeation performance was obtained.

[0021]

EXAMPLE 6 Instead of the liquid paraffin used as the core liquid in Example 1, isopropyl myristate was used. Instead of the nonane isomer mixture used as a detergent, n-nonane was used at room temperature at 500 ml / min. The solution was passed at a speed of 10 minutes for 10 minutes. Lipophilic liquid amount of membrane, residual solvent amount, glycerin amount,
Table 1 shows the film performance. As is clear from Table 1, glycerin in the pores of the hollow fiber membrane was not removed, and only isopropyl myristate remaining inside the hollow fiber could be removed. Next, drying was performed by passing dry air at 40 ° C. for 5 minutes. As a result, n-nonane was removed, and a hemodialyzer having excellent membrane permeability was obtained.

[0022]

Example 7 Cupraammonium rayon was used in place of cellulostriacetate used as a hollow fiber in Example 1, and isopropyl myristate was used in place of liquid paraffin used as a core liquid. And
N instead of the nonane isomer mixture used as a detergent
-Nonane was passed at a rate of 500 ml / min for 10 minutes at room temperature.
Table 1 shows the lipophilic liquid amount, residual solvent amount, glycerin amount, and membrane performance of the membrane. As is clear from Table 1, glycerin in the pores of the hollow fiber membrane was not removed, and only isopropyl myristate remaining inside the hollow fiber could be removed. Next, drying was performed by passing dry air at 40 ° C. for 5 minutes. As a result, n-nonane was removed, and a hemodialyzer having excellent membrane permeability was obtained.

The cleaning agent used in the method of the present invention has no risk of depletion of the ozone layer and ignition during the cleaning process. Further, the performance of the hollow fiber membrane was not reduced by the washing operation, and the case for housing the hollow fiber bundle did not deteriorate in the solvent. Further, even in the washing of the module using glycerin as a pore holding agent for the hollow fiber membrane, the glycerin filled in the pores of the hollow fiber membrane was not removed, and the core contained in the core during the production of the hollow fiber was not removed. The oily liquid can be washed away.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 13/02

Claims (3)

[Claims] When the inside of a hollow fiber used for hemodialysis is washed, the boiling point is 110 to 240 ° C and the flash point is 21 ° C.
A method for cleaning a hollow fiber membrane, comprising cleaning the inside of the hollow fiber with the above-described cleaning agent mainly containing an aliphatic hydrocarbon. 2. The method for cleaning a hollow fiber membrane according to claim 1, wherein the core liquid is washed off from the hollow fiber impregnated with a lipophilic liquid as the core liquid inside the hollow fiber. 3. The method according to claim 1, wherein the aliphatic hydrocarbon is at least one compound selected from the group consisting of nonane, decane, undecane and dodecane.
The method for cleaning a hollow fiber membrane described in the above.