JPS6297981A - Method for making hydrophobic porous membrane hydrophilic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for hydrophilizing a hydrophobic porous membrane used in fields such as water treatment and blood purification.

BACKGROUND ART Hydrophobic porous membranes have excellent barrier properties and chemical resistance, so the fields of their application are rapidly expanding. However, it is difficult for hydrophobic porous membranes to allow water to pass through them, and a hydrophilic treatment is required to allow water and other hydrophilic liquids to pass through them.

As for the method of making hydrophilic materials by surface modification of hydrophobic substances, several methods have been studied, but in contrast to making porous materials with complex surface shapes, hydrophilic materials such as film-like materials with smooth surfaces have been studied. It is not possible to simply apply the conversion method.

Hydrophobic pores [Methods for making membranes hydrophilic include (1) organic solvent wetting/water displacement method, (2) physical adsorption method, and (3) chemical surface modification method. The organic solvent wetting/water displacement method involves wetting the entire surface of a hydrophobic porous membrane such as polyolefin with an organic solvent such as alcohol or ketone that is highly compatible with water, and then applying the This method replaces the organic solvent with water, but with this method, if the water in the pores escapes during storage or use, it becomes impossible to see the water in that area, so the surrounding area of the porous membrane is It is necessary to keep water shining at all times, and handling is complicated.

The physical adsorption method is described in JP-A-54-153872 and JP-A-5.
Although it is described in No. 9-24732, is it a hydrophilic substance such as polyethylene glycol or surfactant? This is a method to impart hydrophilicity to a porous membrane by adsorbing it to the surface of the porous membrane.
It has the advantage of being easy to operate.

However, when blood treatment is performed using a porous membrane adsorbed with surfactant or polyethylene glycol gold, the use of these hydrophilic substances is not recommended because the desorption and elution of the adsorbed substances becomes a problem. .

As a chemical surface modification method, a method is known in which the porous membrane surface is oxidized and modified using an oxidizing agent such as ozone or permanganate or corona discharge, but oxidative deterioration of the membrane substrate is inevitable. However, it has the disadvantage that the strength of the porous membrane is reduced.

[Problem to be Solved by the Invention 3] As mentioned above, organic solvent wetting/water displacement methods and physical adsorption methods have problems such as insufficient hydrophilic life, and oxidation methods have problems such as a decrease in the frequency of t1 membrane substrates. At present, no effective method for imparting hydrophilic properties to hydrophobic porous membranes has been established.

The purpose of the present invention is to solve the problem of drunkenness in the prior art, and to provide a hydrophobic porous membrane that can be hydrophilized over the entire surface contained in the pores without reducing the strength of the membrane. An object of the present invention is to provide a method for making a porous polyolefin membrane hydrophilic.

[Means for solving problems]

In order to solve the above-mentioned problem, the Ministry of the Invention and others conducted a detailed study on a physical adsorption method with a simple process and arrived at the present invention. The gist of the present invention is to provide a method for making a hydrophobic porous membrane hydrophilic, which is characterized by treating the hydrophobic porous membrane with a water-soluble protein. Ethylene, propylene, 4-methyl-1-
Examples include polymers selected from the group of pentene, 3-methyl-1-butene, tetrafluoroethylene, vinylidene fluoride, and co-positional polymers.

Examples of water-soluble proteins include albumin, globulin, prolamin, glutelin, histone, protamine, and hard protein, among which albumin and globulin found in serum, milk, or egg white are particularly preferred. .

The present invention can be carried out by treating the hydrophobic porous M using a solution containing all of the water bathing proteins.

Water or physiological saline can be used as a solvent for dissolving the water bath protein. The appropriate concentration of the protein in the solution is approximately α1 to 10 by weight, and if the concentration is lower than this range, sufficient hydrophilization cannot be achieved. Even if the concentration is higher than this range, the hydrophilization effect will be particularly Proteins that do not increase but are excessively adsorbed or proteins that remain in the pores often deteriorate the water permeability of the porous membrane, which is not preferable. Treatment methods include a method of immersing a hydrophobic porous membrane in the solution, or a method of pressurizing the bath liquid into a modularized hydrophobic porous membrane, but these methods do not necessarily apply. Not limited.

The characteristics of the hydrophilization method of the present invention include (1) water or physiological saline can be used as a solvent, and (2) water-soluble proteins penetrate into the pores of the FjL hydrophobic porous membrane due to surface activity. (3) Since the adsorption power is strong, bathing proteins can be absorbed from the porous membrane even in water or organic solvents. (4) The water-bathable protein is biocompatible;
1J5 and is not harmful to the human body, so even if it were to be desorbed or bathed, no problems would occur.

Example] EXAMPLES The present invention will be specifically explained below with reference to Examples.

In addition, in the examples, water permeability, water permeability, and water permeability in the alcohol hydrophilization method are calculated as follows:
19 Tensile breaking strength was also determined by the following method using the test membrane module of 25℃ while increasing
Water is supplied, and the water pressure when the amount of permeated water becomes 30- and 5011 Find the pressure at the point where it intersects with the axis and use that value as the hydraulic pressure.

(2) Water flow: 61 tons of 25°C water from one side of the test membrane module (inside the hollow fiber membrane in the case of a hollow fiber membrane),
Measure the amount of permeated water when the transmembrane pressure is 50 mmHg, and calculate the water permeability (1 mt-hr-IllIH) from the stone.
Find g).

(3) Water permeability by alcohol hydrophilization method: One of the test membrane modules that has not been hydrophilized (in the case of a hollow fiber membrane, the inner part of the hollow fiber membrane) is ethanol f 25 tag
/min for 15 minutes to fully wet the pores of the porous membrane with ethanol, and then add 100 d of water.
/min for 15 minutes to replace the ethanol and gold water present inside the pores. Subsequently, the total water permeability was measured by the nine methods described in (2).

(4) Tensile breaking strength: using a tensile tester with a test length of 100cm
The stress value at tensile breakage was measured at a tensile speed of 50 mm/min, and this fL' was defined as the tensile strength at break.

Example 1 A polyethylene porous flat membrane with a porosity of 70 mm and a membrane thickness of 42 μm was immersed for 2 minutes in a physiological saline bath solution with a serum albumin concentration. Subsequently, the porous membrane was soaked in running water for 48 hours.
After washing for several hours, it is dried at room temperature and under reduced pressure to make it hydrophilic.
An Lz polyethylene porous membrane was obtained. Next, the water permeability pressure and water permeability were measured using the test membrane module, and the results shown in Table 1 were obtained. In Table 1, the water permeability after the hydrophilic treatment is significantly lower than before the hydrophilic treatment, and the water permeability after the hydrophilic treatment is almost the same as that by the alcohol hydrophilic method. It can be seen that the hydrophilic treatment of this example is extremely effective.

Next, for the purpose of evaluating the durability of the hydrophilized product, a flow rate of 950 ml/m was applied using the test membrane module after the hydrophilic treatment.
After soaking in water for 200 hours, it was immersed in ethanol for 1 minute, kept dry under reduced pressure at room temperature, and the water permeability and water permeability were measured in the same manner. . 1st
In the table, the water permeability pressure and water permeability after ethanol washing are almost the same as those immediately after the hydrophilic treatment, and it can be seen that the durability of the hydrophilized product of this example is sufficient.

Example 2 A test membrane module with an effective membrane surface of 165 i was fabricated using a polyethylene ax porous hollow fiber J[-] with a pore content of 68%, a membrane thickness of 60 μm, an inner diameter of 2°, and an IR/1. A water bath solution containing ovalbumin 72 times F [%] from the inside of the thread membrane.
Pressure was applied for 5 minutes at −25 vd/min. Similarly, water was added from the inside of the hollow fiber membrane at a rate of 100-/min.
A polyethylene porous hollow fiber membrane which had been subjected to a hydrophilic treatment was obtained by press-fitting the membrane for 1 minute and drying it at room temperature under reduced pressure.

Next, we measured the permeability pressure using the test membrane module before and after the hydrophilic treatment, and obtained the results shown in Table 1.◎In Table 1, the permeable pressure after the hydrophilic treatment was significantly lower than that before the hydrophilic treatment. It can be seen that it has been sufficiently hydrophilized.

Next, in exactly the same manner as in Example 1, the test membrane module after the hydrophilic treatment was washed with ethanol and dried under reduced pressure at room temperature, and the water permeability pressure and water permeability were measured. In Table 1, the water permeability pressure and water permeability after ethanol washing are almost the same as the values immediately after the hydrophilization treatment, which indicates that the durability of the hydrophilization treated product of this example is sufficient.

Full tensile breaking strength of the membrane before and after hydrophilic treatment.

As a result, it was confirmed that the membrane strength was 7.5 K9/heel 2 in both cases, and the membrane strength did not decrease as a result of the water infestation treatment.

Example 3 Polypropylene porous hollow fiber membrane with porosity 45%, M thickness 22 pm, inner diameter 20011 m and serum globulin full double layer t
% of physiological saline bath solution was used, and the other conditions were the same as in Example 2. Hydrophilization treatment, ethanol washing,
and performance evaluation, and obtained the results shown in Table 1. From Table 1, it can be seen that the hydrophilic treated product of this example had good water permeability pressure and excellent durability.

〔Effect of the invention〕

As is clear from the results of the Examples, the following effects are produced by employing the method of making a hydrophobic porous membrane hydrophilic according to the present invention.

(1) Hydrophilicity can be imparted to 4&n7 to the same extent as with the alcohol hydrophilization method.

(2) Since the rate of desorption of adsorbed nx water bath protein is very slow, it can be used for a long time.

(3) Water-soluble proteins are safe for the human body, so even if they are detached and eluted, no problems will occur.

Claims (1)

[Scope of Claims] 1. A method for making a hydrophobic porous membrane hydrophilic, which comprises treating the hydrophobic porous membrane with a water-soluble protein. 2. The method for making a hydrophobic porous membrane hydrophilic according to claim 1, wherein the water-soluble protein is albumin or globulin.