JPS58111832A - Preparation of hydrophilic membrane - Google Patents

Abstract

PURPOSE:To obtain a hydrophilic membrane with improved selective permeability, by a method wherein a film comprising a specific ethylene copolymer is reacted with a sulfonating agent to yield a hydrophilic membrance which is then heat-treated. CONSTITUTION:A film comprising a resin compsn. containing an ethylene copolymer of 97-82mol% ethylene with 3-18mol% monomer of formula[wherein R1 is H, CH3; R2 is OCOR3 (wherein R3 is a 1-5C hydrocarbon group), COOR4 (wherein R4 is H, 1-6C hydrocarbon group, an alkali metal or the other ions capable of forming a salt with a carboxyl group)]or a composite film having at least one layer of said film is reacted with a sulfonating agent to yield an hyrophilic membrance with an electrical resistance of 0.01-5OMEGA.cm<2> in dilute H2SO4. Then the hydrophilic membrance is heat-treated in a state in which at least part of sulfone goups of the hydrophilic membrance is SO3H.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new method for producing a hydrophilic membrane obtained by introducing a sulfone group into an ethylene copolymer. The present invention relates to a new manufacturing method.

Hydrophilic membranes with ion exchange properties, in which ion exchange groups such as sulfone groups are introduced into polymer resin films, are attracting attention for use in Type A as functional polymer membranes with unique permselectivity. There is.

For example, (1) fractional collection of solutes by diffusion dialysis using differences in solute concentration, (solute separation and recovery technology by electrodialysis using electrical energy, and (3) oxidation due to electrode reactions that occur during electrodialysis). Reduction product manufacturing technology, (4) Separation technology using reverse osmosis, pervaporation, etc. (excellent) Technology for use as polymer electrolyte in fuel cell membranes, etc. have been studied in the technical framework, and some have been put into practical use. ing.

In addition, hydrophilic membranes with ion-exchange properties are the backbone of these technologies. The selective permselectivity function of each article, such as intermolecular permselectivity, is utilized.

Previously, it was already known that a hydrophilic membrane having ion-exchange properties with sulfonic groups introduced uniformly throughout the interior could be obtained from an ethylene copolymer film in a short period of time.
Special Publication No. 11f151-41035.

Special Publication No. 52-29988 and U.S.%lI'FlIJl
It is publicly known from Book I, No. J13925332, etc.

Furthermore, a hydrophilic membrane having similar K and ion exchange properties can be obtained from a film made of a resin composition in which an ethylene copolymer and a thermoplastic resin relatively inert to the sulfonating agent are mixed. Also, Zero 1141 Permit Specification-3925332
Publicly known by number.

Also, Japanese Patent Application No. 55-101890, Japanese Patent Application No. 1983-11
No. 4684, IF! ll1i No. 56-157911,
Japanese Patent Application No. 56-96500 proposes a hydrophilic membrane that is an improved version of the hydrophilic membrane obtained by introducing a sulfone group into an ethylene copolymer and a method for producing the hydrophilic membrane.

Such a hydrophilic membrane has excellent ion exchange performance and low electrical resistance in an electrolytic solution, and at the same time has (1) excellent repellency against organic matter, and (2) anion exchange properties. It has excellent permselective properties such as excellent repellency against ions, and (4) can be handled in a dry state with almost no change in membrane performance.
Because the membrane has excellent practical properties such as flexibility, it can be used for ion exchange membranes, electrolytic separation membranes, dialysis membranes, and various battery diaphragms2.
It has the potential to be applied to a wide variety of membership fees.

The present inventors have arrived at the present invention after extensive research aimed at further improving the selective permselectivity of a hydrophilic membrane obtained by introducing a sulfone group into the above-mentioned ethylene copolymer.

Learn more about the purpose of the inventionMKI! Accordingly, an object of the present invention is to provide a material with low electrical resistance in an electrolytic solution and to improve various permselective properties, and secondly, to improve barrier properties against organic substances.

To explain the present invention, the hydrophilic membrane C0 to C of the present invention
At least one type of ethylene-based copolymer selected from ethylene-based copolymers with a monomer having the structure of 5) (ions that can form salts with hydrocarbon groups, alkali metals, and other carboxylic acid groups) At least one film or skeleton film made of a resin composition containing at least
The composite film in I is reacted with a sulfonating agent to form a hydrophilic film with an electrical resistance of 0.01 to 5 Ω·- in dilute sulfuric acid, and then the hydrophilic film has a small number of sulfonic groups (in both cases, one part is - This is a method for producing a hydrophilic membrane, characterized by heat treatment in a state of 80.H.

A hydrophilic membrane produced by such a production method has significantly improved permselectivity compared to a hydrophilic membrane obtained by introducing a sulfone group into a conventional ethylene copolymer.

Learn more about the method for producing the hydrophilic membrane of the present invention! IKm
To be clear, the present invention involves forming a resin composition containing at least one type of ethylene copolymer into a film, such as a single film or a composite film, by a conventionally known film forming method, and then forming the resin composition into a single film or a composite film. If the resin composition contains a plasticizer, the plasticizer may be extracted with a sulfonating agent before being subjected to a sulfonation reaction, or at least a portion of the plasticizer may be extracted with a solvent before sulfonation. , then subjected to sulfonation reaction, and the electrical resistance in dilute sulfuric acid is 0.01-5Ω・33
, preferably 0.05 to 1Ω・C1m″, and then the wrinkled hydrophilic film is characterized by being heat-treated in such a state that some of the sulfone groups are in the -80,!(0) state. This is a method for producing a hydrophilic membrane with improved selectivity.

The ethylene copolymer referred to in the present invention is -CO
OR4 (however, R, =C, =C5 hydrocarbon group, R4x
Ethylene-based copolymer with a monomer having a structure of H, c, =C6 hydrocarbon groups, alkali metals, and other metal ions (ions that can form ruts with carboxylic acid groups) Within this range, a hydrophilic film having an electrical resistance in dilute sulfuric acid of 0.01 to 5 Ω·C1l'' can be obtained with good productivity and high quality.

In the present invention, the ions that can form salts with other carboxylic acid groups include, for example, MgS++ C
& “ ” + Zn” Ten divalent metal ions.

In addition to hts+ trivalent metal ions, NH4+ and other 0-C
It means a cation that can form a salt with an OO- group.

Furthermore, in the present invention, the ethylene copolymer composition refers to one consisting of at least 1at of ethylene copolymers, one in which a relatively inert thermoplastic resin is added to a sulfonating agent, and one in which a relatively inert thermoplastic resin is added to the sulfonating agent; It contains a plasticizer that is compatible with the cough oil component and that can be extracted from the film and/or hydrophilic membrane using a solvent and/or a sulfonating agent.

In addition, a film made of an ethylene copolymer composition refers to a single film or a multilayer film formed by molding the ethylene copolymer composition using a normal film molding method, or a single film or a multilayer film formed from the ethylene copolymer composition. It is a composite film that combines one or more reinforcing materials such as , woven fabric, non-woven fabric, and microporous membrane.

The thermoplastic resin that is relatively inert to the sulfonating agent used in the present invention may be one that exhibits a relatively slow sulfonation reaction compared to the above-mentioned ethylene copolymer, and is limited to 41. However, materials that can be easily mixed and dispersed using normal plastic processing methods are good because they are easy to produce and obtain films with uniform quality.For example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, Linear low density polyethylene, polypropylene.

Polyolefin resins such as polybutene-1 are preferred.

In addition, in the present invention, the blending ratio of the O thermoplastic resin in the ethylene resin composition containing the thermoplastic resin is preferably at most 855 parts by weight, more preferably 70 parts by weight of the total resin components. It is possible to obtain a hydrophilic membrane with good productivity, which has excellent oxidation resistance in the range of 15% by weight or less to 15% by weight or more and has low electrical resistance in an electrolytic solution.

Further, the plasticizer that is compatible with and extractable from the resin component is a plasticizer that is uniformly dispersed in an amount of at least 5 parts by weight per 100 parts of the resin component in the molten state of the resin component; A thin film can be formed by melt molding, and under the extraction conditions of the plasticizer, the above-mentioned resin components are hardly formed into droplets using a solvent or a sulfonating agent, etc., before, during or after the reaction. Any material that can be quickly extracted from the film or membrane may be used.

Examples of plasticizers include Futa Jw-ESTE Class 9 represented by Futa J/@diethyl and dioctyl phthalate, as well as linear dibasic acid esters.

Chlorinated products such as phosphate varnishes, chills, epoxy plasticizers, polyester plasticizers, and chlorinated paraffins *Those commonly used as plasticizers for plastics such as chlorinated fatty acid esters, or those that meet the above requirements. , at least one kind selected from various other additives having plasticizing effect and/or ** effect.

The amount of plasticizer added is preferably as large as possible because the time required for sulfonation is shortened; however, in order to stably form a thin film, it is usually necessary to add plasticizer to at most 100 parts by weight of the resin component. 200 parts by weight of the agent is suitable, preferably 10 to 100 parts by weight.

In addition, in the present invention, the term woven fabric refers to a fabric obtained from inorganic or polymeric fibers by weaving methods such as plain weave, oblique weave, satin weave, leno weave, etc., and the thickness of the threads and the number of threads The fiber material may be selected as appropriate depending on the application, within a range in which the structure of the fabric does not collapse to an extreme degree during adhesion with the resin composition and/or during composting. Agents 1, □, and 11: Any agent may be used as long as it is relatively inert and does not change significantly either physically or chemically during the heat treatment of the present invention, and is not limited to %. , it is necessary to make an appropriate selection depending on the purpose and color of use. For example, polyethylene, polypropylene.

Fluororesin fibers are preferred because they are relatively inert to sulfonating agents and other chemicals and have excellent relative heat resistance.

Also, non-woven fabrics and microporous membranes are the same as woven fabrics,
The material, thickness, effective conductive area, etc. can be selected depending on the application, from a material that does not lose its shape extremely when adhering to the resin composition and/or when handling, and has excellent chemical resistance and heat resistance. You can choose as appropriate.

In the method for producing a hydrophilic film of the present invention, the method for molding the film made of the ethylene copolymer composition includes a molding method performed in ordinary plastic processing, for example, for a single film, compression molding, Flat films or tubular films are produced by extrusion molding, casting, etc., or for multilayer films, various single films are produced individually, and then multi-layered by compression molding, etc. in the desired combination, or A multilayer film may be created by coextrusion. In addition, composite films reinforced with one or more types of reinforcing materials such as woven fabrics, non-woven fabrics, and microporous membranes can be made by forming a single film and then compression molding the reinforcing material and the film or passing it between hot rolls. The compound may be compounded by extrusion lamination, solution or latex-like reinforcing material, etc., and is not particularly limited.
It may be selected appropriately depending on the purpose.

In a film made of a resin composition to which a plasticizer is added per K for introducing sulfone groups into the film,
Depending on the type of plasticizer used, select the appropriate solvent and extract only the plasticizer from the film without dissolving the resin component, or use fuming sulfuric acid alone or with the plasticizer contained without dissolving the plasticizer. , sulfur trioxide, chlorsulfone, etc. are required! ! Depending on the situation, it is preferable to carry out sulfonation using a diluted solution with a solvent or a complex compound such as sulfur trioxide.

The temperature of the reaction with the sulfonating agent is suitably 60° C. or less and the reaction time is suitably within 2 hours; if the reaction exceeds these conditions, undesirable side reactions are likely to occur.

Then, within these conditions, by appropriately selecting the type and degree of sulfonating agent according to the film length, composition, type and presence or absence of reinforcing material, electrical resistance in the desired electrolyte, etc. A sulfone group is introduced so that the film becomes a hydrophilic film having an electrical resistance in dilute sulfuric acid of 0.01 to 5 Ω·(j”).

Then, the hydrophilic membrane obtained by the above method is heat-treated in a state in which at least a part of the sulfone groups bonded to the skeleton hydrophilic group is -80,H, thereby achieving the desired excellent permselectivity. A hydrophilic membrane can be obtained.

Comparing the hydrophilic membranes obtained by the conventional method and the method of the present invention with the same electrical resistance in the electrolyte, it was found that the hydrophilic membrane obtained by the method of the present invention has a high selectivity, especially against organic matter. This means that it has excellent ion permselectivity.

In the present invention, the electrical resistance in dilute sulfuric acid before heat treatment is preferably 0.01 to 5 Ω・Cal", and %K
O.05 to 1Ω·ell” is suitable.

If the resistance in dilute sulfuric acid exceeds 50.cats, the effect of heat treatment will be small, and if it is less than 0, oiΩ.-, it will be difficult to handle the film during heat treatment.
~5Ω・-8 Preferably, 0.05 to 1Ω・C3I snow is desirable.

In addition, it is necessary that at least a part of the sulfone groups bonded to the axillary aqueous groups be in the -80,H state, for example, all of the sulfone groups should be in the -80,H state for K to be heat-treated in the hydrophilic membrane. In the state of metal salt, the effect of heat treatment is difficult to expect.

Further, the heating temperature is preferably in the range of 50 to 250°C, and preferably 100 to 200°C.

If the temperature is below 50°C, the processing time will be unnecessarily long, and if the temperature is below 50°C,
On the other hand, it is necessary to control the temperature of ζ exceeding 0℃, so it is necessary to control the temperature to be short and wearable, so the above-mentioned temperature conditions of 50 to 250℃, preferably 100 to 200℃, are preferable from the viewpoint of quality stability and productivity. becomes.

In addition, the time required for heating depends on the heat treatment method (conduction heating method, radiation heating method, convection heating method*), the thickness of the hydrophilic film, the composition, and the type and presence of reinforcing material.

This is determined appropriately depending on the electrical resistance in the electrolyte of the hydrophilic membrane before and after the heat treatment, but it is generally recommended to heat the membrane for a period of about 30 seconds to 60 minutes to ensure quality stability and productivity. It is desirable for the following reasons.

In addition, in the production method of the present invention, heat treatment after sulfonation means: (1) After sulfonation treatment, the sulfonation agent is washed with sulfuric acid, water, etc., and then heat treated; (2) After sulfonation treatment, the sulfonation agent is heated; After washing with sulfuric acid and water, etc., drying and then heat-treating. After sulfonation treatment, wash the sulfonating agent with sulfuric acid and water, etc., then treat the sulfone group with an alkaline chemical, etc., and then heat-treat. It is preferable to perform the IjK treatment by washing and drying, converting at least a portion of the sulfonate into -8O, H groups with an acid, and then heat-treating the ethylene copolymer used. It can be selected as appropriate depending on the content of ester groups and the heat treatment method. It goes without saying that the heat treatment method of the present invention can be carried out by any of the above-mentioned heat transfer heating methods, radiant heating methods, and convection heating methods, which may be selected as appropriate depending on the method for treating the hydrophilic film before heat treatment. Good.

Although it is not currently clear why the hydrophilic membrane obtained by the production method of the present invention has superior permselectivity compared to the hydrophilic membrane obtained by conventional methods, the present inventors It is assumed that this is due to the following reasons.

When a considerable amount of sulfone groups are introduced into a film containing an ethylene copolymer, an electroporous hydrophilic film with low electrical resistance in an electrolytic solution can be obtained from K.
It is conventionally known.

The above hydrophilic film is made of -OH or -C00
Because it has M and -80, M groups (M=H, ion II that can form alkali metal or other carboxylic acid groups and sulfonic group ζ salts), it is easy to permeate water, Il aqueous substances, and cations; It has selective permeability that makes it difficult for lipophilic substances and large anions to pass through.

In the present invention, by heat-treating the hydrophilic film having -80,H groups, the -80,H groups undergo some chemical change, resulting in partial hydrophobization and/or partial crosslinking of the woodphilic film. It is presumed that this improves the selective permselectivity of the hydrophilic membrane.

For example, to describe the case where the selective permeability of hydrophilic substances is improved, the above-mentioned partial hydrophobization and/or partial cross-linking can be applied to substances with different hydrophilic strengths or different molecular or ion sizes. It is surmised that the influence was different, and that the selective permselectivity of the hydrophilic membrane obtained by the conventional method was expressed to a greater extent.

As a result, the wood-loving film obtained by the method of the present invention can be used for all the various uses of wood-loving films obtained by conventional methods.

For example, it can be efficiently used in electrolytic separation membranes, dialysis membranes, various separation membranes, battery diaphragms, polymer electrolyte WI44II for fuel cells, and the like.

In carrying out the present invention, it is practically convenient to carry out the above-mentioned heat treatment, then neutralize with an alkaline chemical or the like, wash thoroughly with water, and dry before handling.

Furthermore, under the above conditions, it goes without saying that the K used in the present invention can be processed in any other desired manner, for example, in other shapes than a continuous film, such as a tube, a single bag, a hollow fiber, and the like.

In addition, for the purpose of improving oxidation resistance, chemical resistance, etc., before or after heat treatment, three-dimensional crosslinking before sulfonation or chemical treatment after sulfonation (Japanese Patent Application No. 56-1579
It is also possible to implement other methods (see No. 8).

In the following Examples and Comparative Examples, the selective permselectivity of the hydrophilic membrane obtained by the method of the present invention will be explained using methanol, which has large hydrophilicity and has a relatively small molecular diameter (normally, water with a large electrical resistance in the electrolytic solution). The present invention will be explained in more detail by describing the improvement of the barrier properties of the hydrophilic membrane (which is permeable to harmful birds).

Throughout this specification, the measurement conditions and test methods for each physical property value are as follows.

(11 Electrical resistance in dilute sulfuric acid (Ω・013) Specific gravity is 1.2
Measuring device (JI8C) filled with dilute sulfuric acid (at 23℃)
2313)) Set the sample, and place the 25 mm between the electrodes.
Measure the voltage drop across the sample when a constant DC current of mA/cm'' is applied, and use the value calculated from the following formula as the electrical resistance in dilute sulfuric acid. 2
Immerse in dilute sulfuric acid at (AZ23℃) for 24 hours or more - Electrical resistance of sample in dilute sulfuric acid (Ω・3Ω) ■l = Voltage drop when sample is not set (V) v = When sample is set When the voltage drop (V) specific gravity is 1.2 (at 23℃
) dilute sulfuric acid 11(A) and methanol of dilute sulfuric acid FC4vol IG with specific gravity 1.2 (ai 23℃) mixed solution (
B) was brought into contact with the sample through the sample, and at a temperature of 23°C (B)
The permeation coefficient of methanol is calculated by measuring the amount of methanol permeated from the liquid (A) to the liquid (A) according to a conventional method.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples, 1 to 4 A copolymer of 94.2 (-) ethylene and 5.8% methyl methacrylate was subjected to nanization (degree of saponification = 60 mol%) and neutralization (neutralization). degree = 30 mole attack) and obtained 100
0C! H,, -000H and -00ON, ethylene-based copolymers (MI = 1.0) for 80 weight squares, 20 weight arc high density polyethylene (density = 0.
955 f/am'', MI = 7) was kneaded in a kneader at 190°C for about 30 minutes, and then, 43 parts by weight of liquid paraffin (13i Sankagaku Kinki Co., Ltd. (manufactured by S.A. Co., Ltd.) and further mixed for about 30 minutes at 190°C.Then, the resin composition was thermoplasticized in an extruder at a temperature of 180°C, extruded through a circular die, and A film with an original film thickness of %40J and a thickness of 1 ml was obtained by quenching with water at .degree.

Then, the above film was heated to 1.1. t-)Immerse in RitaO ethane for about 10 minutes to extract liquid paraffin, then place in fuming sulfuric acid containing 12% free sulfur trioxide and treat at 135°C for 7 minutes) Concentrated sulfuric acid, dilute sulfuric acid, water The membrane was sequentially washed, neutralized with an aqueous potassium hydroxide solution, washed with water, and dried to obtain a hydrophilic membrane. The electrical resistance of this hydrophilic membrane in dilute sulfuric acid was %0.15"Q-ex"〇This hydrophilic membrane was then treated with an aqueous solution of IN hydrochloric acid,
Most of the -80, groups were changed to -80,H groups, washed with distilled water, and then dried at room temperature.

Next, this hydrophilic membrane was dried for 1 hour in a hot air dryer at 150°C.
Heat treatment was performed taking into account the treatment time.

As shown in Table 1, the result was a hydrophilic membrane with extremely excellent methanol barrier properties despite having low electrical resistance in dilute sulfuric acid.

Table 1 1 Example 4 1 G 1.55 4.8 X
l O = Comparative Examples 1 to 4 Examples 1 to 4 were obtained by variously modifying the sulfonation conditions of Example 1.
A hydrophilic membrane having almost the same electrical resistance in dilute sulfuric acid as in Example 4 was prepared, and the methanol barrier property was measured. It was inferior. (The hydrophilic membranes of Comparative Examples 1 to 4 were not subjected to the heat treatment performed in Examples 1 to 4.) Table 2 Examples 5 to 7 92.3 moles of ethylene and 7.7 moles of acrylic 400 parts by weight of copolymer with ethyl acid (MI = 2), MI to high density polyethylene (density = 0.965 f/am)
= 13) 60% by weight was melt-kneaded in a kneader in a similar manner to Example 1, and then 100% of the above resin mixture was melt-kneaded.
Adding 66.7 parts by weight of liquid paraffin to the parts by weight,
The resin composition was then extruded using an extruder equipped with a circular die to obtain a film having a thickness of 30 μm.

After extracting the plasticizer in the same manner as in Example 1, sulfonation treatment was carried out at 35°C for 15 minutes, followed by washing with concentrated sulfuric acid, diluted sulfuric acid with 1 water, and potassium hydroxide aqueous solution. After the treatment, the membrane was washed with water and dried to obtain a hydrophilic membrane.

The electrical resistance of this hydrophilic membrane in dilute sulfuric acid was O.SOΩ1/2.

Next, 1 Example of this hydrophilic membrane! It was similarly treated with an aqueous hydrochloric acid solution to convert most of the -80 and -80 groups into -80sH groups, washed with distilled water, and then dried at room temperature.

Next, this hydrophilic membrane was heat-treated in a hot air dryer at 150°C for varying treatment times.

As shown in Table 3, although the electrical resistance in the desired acid was small, the membrane was a hydrophilic membrane with extremely excellent methanol barrier properties.Table 3 Comparative Examples 5 to 7 Sulfone of Example 5 Examples 5-
A hydrophilic membrane having almost the same electrical resistance in dilute sulfuric acid as in Example 7 was prepared, and the methanol barrier property was measured. It was inferior. (The hydrophilic membranes of Comparative Examples 5 to 7 were not subjected to the heat treatment performed in II II Examples 5 to 7.) Table 4 Examples 8 to 12 In a similar manner to Example 1, electrolysis in dilute sulfuric acid was performed. resistance is O, l
A, t-hydrophilic membranes were heat-treated under the conditions shown in Table 5, and as a result, hydrophilic membranes with excellent methanol barrier properties were obtained. These hydrophilic membranes were more comfortable and had superior permselectivity than hydrophilic membranes obtained by the conventional method having electrical resistance in Oka's dilute sulfuric acid.

Table 5 Examples 13 to 16 92.9 moles of ethylene and 7.1 moles of vinyl acetate! = (F) 40 made of copolymer (MI=2.5)
am-thick film (Example 13.14) and a 40 μm film made of the ethylene copolymer used in Example 1.
・ A thick film (Example 15.16) was sulfonated by a conventionally known method, and the sulfone group was in the state of -5o-.Heat-treated under the conditions shown in Table 6. As a result of actual testing, it was found that the hydrophilic membrane was more comfortable to wear and had superior methanol barrier properties compared to hydrophilic membranes obtained by conventional methods.

Example 17 The composition ratios of the ethylene copolymer and high-density ethylene used in Example 5 were changed to 80% by weight and 20% by weight, respectively, and 43 parts by weight of dioctyl was added to 100 parts by weight of the resin component. 7 tallate was added to the above resin mixture, and 50 μm
A thick film was created. The above film was irradiated and crosslinked using an electron beam irradiation device so that the gel fraction = 15%, and then two sheets of the film were coated with polypropylene woven fabric [50 denier M (multifilament) - 50 mesh weave]. They were stacked like a sandwich and bonded under pressure at a temperature of 120°C. After cooling the composite film, 1°1, l −)
1-liquid paraffin was extracted by immersion in rift tetraloethane for 30 minutes, dried at room temperature, and sulfonated to give an electrical resistance of 0.20 in dilute sulfuric acid. A hydrophilic membrane of am was prepared.

Most of the sulfone groups are in the -8o, H state at 150℃0
Heat treatment was performed for 3 minutes under temperature conditions, and the electrical resistance in dilute sulfuric acid was 0.630. A wood-loving membrane with a methanol permeability coefficient of 4.8 X l Oam/win was obtained.

This hydrophilic membrane has the following characteristics compared to hydrophilic membranes obtained by conventional methods:
It was comfortable to wear and had excellent selective permselectivity. Gel fraction (temperature) The value obtained by dissolving the resin in boiling p-xylene and calculating the proportion of the undissolved portion from the above formula. , weight of only the resin part without inorganic filler etc. Example 18 Implementation I! From the ethylene copolymer used in 1IIIl,
A film with a thickness of 40 μm was created.

Also, on the other hand, dioctyl 7 tallate, anhydrous finely divided silicic acid and powdered high-density polyethylene (density=ois).

t/♂, MI=1) A microporous membrane with a thickness of 200 meters was formed using a conventionally known method from the resin/resin composition obtained. They were stacked in a sandwich shape and bonded under pressure at a temperature of 110°C.

Next, the above composite film was heated by tenter method for 10
After being stretched 3x3 times at a temperature of 0°C, it was subjected to 1 sulfonation treatment, and the electric resistance in dilute sulfuric acid was 0.18Ωd- as a wood-loving film, with the major m of sulfone groups being -80 and 150 in the H state.
When heat-treated for 3 minutes at a temperature of ℃, 1! The resulting hydrophilic membrane had an air resistance of 0.410.32 and a methanol permeability coefficient of 5.1XtOcm/+nin.

Compared to hydrophilic membranes obtained by conventional methods, this hydrophilic membrane has
It was comfortable to wear and had excellent selective permeability.

Comparative Example 8 All the sulfone groups in the hydrophilic membrane before heat treatment prepared in Example 8 were 1 at a temperature of -80°C and 200°C.
As a result of heat treatment for 3 hours and 3 hours, the electrical resistance in dilute sulfuric acid slightly increased, but the methanol permeability coefficient hardly changed, and the permselectivity was not improved.

Claims (1)

[Claims] A hydrocarbon group of R, = H, a hydrocarbon group of C to C6,
Contains at least one type of ethylene copolymer selected from ethylene copolymers with monomers having the structure (ions that can form salts with alkali metals and other carboxylic acid groups) A film made of a resin composition or a monopoly film having at least one layer of resin composition is reacted with a sulfonating agent to form a hydrophilic film having an electrical resistance of 0.01 to 5Ω·CIII in dilute sulfuric acid, and then ,
At least a portion of the sulfone groups O of the wood-philic film are -80,H
1. A method for producing a hydrophilic membrane, characterized by heat-treating it in Form 1. (2) Electrical resistance in dilute sulfuric acid is 0.05 to 1Ω・cam
A method for producing a hydrophilic membrane according to claim (1). (3) Claims (1) or (2) characterized in that the heat treatment is performed under a temperature condition of 50 to 250°C.
A method for producing a hydrophilic membrane as described in . (4) The resin composition contains less ethylene copolymer (
The method for producing a hydrophilic membrane according to any one of claims S (1) to (S), which contains one type of thermoplastic resin and another thermoplastic resin. Claims (1) to (4) wherein the composite film comprises a film made of the resin composition and one or more reinforcing materials selected from woven fabrics, nonwoven fabrics, and microporous membranes.
A method for producing a hydrophilic membrane according to any one of Item 1. ) The film made of the resin composition is a film made of a mixture of a resin component containing at least 111111 or more of the ethylene copolymer and a plasticizer that is compatible with and extractable from the resin component. A method for producing a hydrophilic membrane according to any one of claims (1) to (a).