JPS594402A - Composite hydrophilic membrane - Google Patents

Abstract

PURPOSE:To provide a composite semipermeable membrane having separability for an org. mixture and excellent water permeability by melt sticking an ethylenic polymer introduced with a sulfonic group together with a specific hydrophilic group and a PE microporous membrane contg. a sulfonic group. CONSTITUTION:A microporous film of 140mum thickness is obtd. by a known method from a resin comps. obtd. from directly phthalate, particulate silicic anhydride and powder PE and an aq. dispersion of an ethylenic polymer which is obtd. by hydrolysis and neutralization of a copolymer of 93.5mol% ethylene and 6.3mol% methyl methacrylate and has -COOCH3, -COOH, -COONa group is coated on the film. Such composite film is stretched to 6.25 times area at 80 deg.C, and is caused to react with fuming sulfuric acid under a 35 deg.C condition, and the film is subjected to treatments such as washing, hydrolysis, neutralization, etc. The resulted membrane has a high coefft. of sepn. for a water-ethanol mixture, and a high coefft. of permeation of water.

Description

[Detailed Description of the Invention] Regarding the membrane, specifically, it is a separation membrane obtained by introducing a sulfone group into a composite film in which an ultrathin film containing an ethylene copolymer and a microporous polyethylene membrane are fused together. , particularly regarding suitable composite hydrophilic membranes.

Attempts to separate organic mixtures by decontamination methods have been made for a long time, but there are almost no examples of industrialization.

Despite the recognized superiority of membrane separation processes, the reason why they have not been put into practical use is mainly due to the delay in the development of membranes that can separate organic mixtures, etc. That's why.

The most commonly used method for separating organic mixtures and the like is the distillation method, and this method is almost technically established. However, this method has the disadvantage that it is difficult to employ for separation of substances with close boiling point differences, separation of azeotropic mixture compositions, separation of substances unstable with respect to thermal history, etc. In addition, due to the recent rise in oil prices, there is an urgent need to develop energy-saving separation methods, and membrane separation methods are expected to be one of them.

On the other hand, as we approach the era of oil depletion, there is an urgent need to develop alternative energy sources for oil. Among these, biomass has the characteristics of being renewable because it uses solar energy and having little impact on the natural environment, so there are high expectations for its practical application.

However, ethanol obtained by fermenting biomass resources is an aqueous solution with a concentration of around 10%, and in order to use it as an energy alternative to petroleum, it is necessary to increase the ethanol concentration by some method. but,
If we try to obtain high-concentration ethanol using the conventional distillation method, a large amount of energy will be consumed before converting biomass into the final energy obtained. may lose its value. Among biomass development technologies, the development of concentration technology to replace distillation is one of the most important.

Conventionally, as a method for concentrating ethanol by selectively passing water through a water-organic mixture, especially a water-ethanol mixture, for example, in U.S. Pat. Ethanol was concentrated from the composition by pervaporation, and a separation coefficient of 8.5 was obtained. However, considering the concentration of high-concentration ethanol water, the separation coefficient is low and there are practical problems in terms of heat resistance and chemical stability. Also, Journal.
of Aiembrane Science, l
(1976) 2 7 1 to 2 8 7, polytetrafluoroethylene was used as a polytetrafluoroethylene. A membrane grafted with 7 (N-vinylpyrrolidone) is used to concentrate a water-ethanol azeotrope composition. However, the separation coefficient in this case is 2.9, which is even lower than that of the above-mentioned separation method, and like the above-mentioned membrane, the separation performance is inferior. In addition, Japanese Patent Publication Nos. 54-10548 and 54-10549 also propose a method for separating water-organic mixtures, but there are practical problems in terms of permeation rate.

From the above point of view, the inventors of the present invention
In No. 7, we proposed a separation membrane that separates water and organic compounds with a significantly high separation coefficient, especially in the separation of water-organic mixtures, from a hydrophilic membrane obtained by introducing sulfone groups into a specific ethylene copolymer. did. However, even in this separation membrane, since it is difficult to make an extremely thin membrane, the water permeation rate is low, and there is room for improvement. In other words, if the film thickness is 10 μm or less, sulfonation is in progress. It was difficult to stably sulfonate or remove from the sulfonation bath.

This was a serious problem when considering an industrial continuous manufacturing process.

The present inventors have conducted intensive studies with the aim of further improving a separation membrane with excellent separation properties obtained by introducing a sulfone group into the above-mentioned specific ethylene-based copolymer, and have arrived at the present invention.

It has already been reported in Japanese Patent Publication No. 51-i that a hydrophilic membrane with ion exchange properties can be obtained from a conventional ethylene copolymer film in a short time and uniformly with sulfone groups introduced into the interior.
o35, Special Publication No. 52-29988 and USP-39
It is publicly known from No. 25332 and the like.

It is also known that a hydrophilic membrane having ion exchange properties can be obtained from a film made of a resin composition containing an ethylene copolymer, a sulfonating agent, and a relatively inert thermoplastic resin. It is known from No. 3925332.

Kagaru hydrophilic membranes were developed as electroporous membranes for use as ion exchange, electrolytic separation membranes, dialysis membranes, etc. In addition to excellent ion exchange performance,
It is a unique membrane that has excellent anion barrier properties, low electrical resistance in electrolyte, and maintains the flexibility characteristic of ethylene copolymers.

In addition, although such a hydrophilic film has the characteristic of being extremely chemically stable in aqueous solutions in all regions of strong acidity, neutrality, and alkalinity, it gradually oxidizes and deteriorates due to oxidizing chemicals. There were drawbacks that resulted in various performance issues. In addition, since the hydrophilic membrane has a high water content in an aqueous solution, it has a large area swelling property, and as a result, the membrane strength in an aqueous solution is low. In particular, the lower the electrical resistance in the electrolytic solution and the thinner the membrane, the more limited it is in terms of handling and use due to the drawback of the dogo bow.

In order to improve this drawback, for example, Japanese Patent Laid-Open No. 57-36
In No. 126, based on the total weight of the resin composition, 15
100 parts by weight of a resin composition consisting of at least 30 to 95% by weight of an ethylene copolymer and up to 85% by weight, for example 5 to 70% of a thermoplastic resin relatively inert to the sulfonating agent. On the other hand, a mixture containing 5 to 200 parts by weight of a plasticizer that is compatible with the resin composition and can be extracted at least either before, during, or after sulfonation is formed into a film. After melt molding, cooling and solidifying, a sulfonation reaction is carried out without extracting the plasticizer using a sulfonating agent, or at least a portion of the plasticizer is extracted with a solvent before sulfonation, and then sulfonation is carried out. The present inventors have proposed a method for producing a hydrophilic membrane that is highly flexible and oxidation resistant, has reduced area swelling in an aqueous solution, and has improved strength in an aqueous solution.

Furthermore, in JP-A No. 57-40527, at least one reinforcing material made of woven fabric and/or non-woven fabric is added to the above-mentioned hydrophilic membrane.
We have proposed a composite hydrophilic membrane with extremely high oxidation resistance, extremely low area swelling in electrolyte, and high strength in aqueous solution.

However, even in the manufacturing method of JP-A No. 57-36126, since the raw film before sulfonation is extremely flexible, a certain film thickness is required for continuous productivity and for reaction with the sulfonating agent. And also,
In particular, as the electrical resistance in the electrolyte is lowered, the membrane strength decreases, and in practical terms, the membrane thickness is about 10 μm or less. There was room for improvement.

Furthermore, in the composite hydrophilic membrane disclosed in JP-A No. 57-40527, it is difficult to substantially reduce the thickness of the sulfonated membrane portion of the ethylene copolymer (less than 0.5 times the thickness of the reinforcing material). In order to obtain a film with low electrical resistance, the time required for sulfonation is long (in some cases, pinholes may easily occur), and the resulting film thickness is substantially increased.
Like the hydrophilic membrane obtained by the method of No. 7-36126, there was room for improvement in the water permeation rate.

In addition, when applying a hydrophilic membrane obtained by introducing a sulfone group into an ethylene copolymer to a lead-acid battery diaphragm, it is necessary to combine the previously known hydrophilic membrane and various reinforcing materials such as glass fiber and asbestos. Fibers, alumina fibers, zirconia fibers, etc. are electrically nonconductive and are not affected by sulfuric acid (inorganic fibers such as woven, knitted, and nonwoven fabrics, polyethylene, polypropylene, rubber, nylon, polyester, cellulose, etc. are electrically nonconductive and are not affected by sulfuric acid. Japanese Patent Application Laid-Open No. 140543/1983 proposes a diaphragm that separates an anode and a cathode using a woven, knitted, nonwoven, or continuous porous membrane made of an organic polymer that is not attacked by water. The primary objective is to prevent oxidative deterioration of the hydrophilic membrane by not allowing the hydrophilic membrane to come into direct contact with the electrode, and also to facilitate handling during battery assembly by combining various reinforcing materials with the hydrophilic membrane. Therefore, it is suitable as a diaphragm for lead batteries, but in manufacturing such a diaphragm, since the hydrophilic membrane was manufactured by a conventionally known method such as the above-mentioned U8F-3925332, As mentioned above, it is extremely difficult to make the thickness of a hydrophilic film extremely thin.Also, using a particularly thin hydrophilic film reduces the acid resistance and oxidative deterioration resistance of the hydrophilic film. Substantially, a thickness of about 40 .mu.m as described in the Examples was preferred since the life of the lead battery would be shortened, which would be contrary to the purpose of the invention.

One object of the present invention is to uniformly reduce the thickness of a hydrophilic membrane obtained by introducing a sulfone group into a conventionally known ethylene copolymer compared to a conventional membrane. The object of the present invention is to provide a membrane that has properties suitable for release.

Another object of the present invention is to provide a hydrophilic film that has excellent film strength and resistance to oxidative deterioration even if it is thin.

Another object is to provide a membrane with extremely low electrical resistance in an electrolytic solution. Another purpose is to provide a membrane with extremely low electrical resistance in an electrolytic solution (membrane) with low area swelling in an electrolytic solution. The objective is to provide a composite hydrophilic membrane with excellent hydrophilicity, water retention, and water resistance.

To explain the present invention, the composite hydrophilic membrane of the present invention is
It is obtained from an ethylene copolymer or a resin composition containing an ethylene copolymer, and contains -OH groups and 1000R groups (
However, at least one hydrophilic group selected from the group consisting of R=H, C, ~C5 hydrocarbon groups, alkali metals, or ions that can form salts with other carboxyl groups) and at least 0.2 This is a composite hydrophilic membrane characterized in that a semipermeable ultra-thin hydrophilic membrane having milliequivalents/gram of sulfone groups and at least one layer of a polyethylene microporous membrane containing sulfone groups are brocade-fused.

Such a composite hydrophilic membrane has a semi-permeable hydrophilic membrane with an ultra-thin thickness, a luxuriously highly hydrophilic sulfone group, a polyethylene-based microporous membrane as a reinforcing material, and a polyethylene-based microporous membrane as a reinforcing material. The microporous membrane has excellent throughness, and is also excellent in heat resistance, solvent resistance, and mechanical strength, and the entire composite membrane is highly hydrophilic, making it an extremely suitable membrane as a separation membrane. A composite hydrophilic membrane of an ultra-thin hydrophilic membrane having a semi-permeable ultra-thin film containing a hydrophilic group consisting of a salt is preferred because it has high hydrophilicity.

To explain the composite hydrophilic membrane of the present invention in more detail, the composite hydrophilic membrane of the present invention cannot be continuously reacted with a sulfonating agent by conventionally known methods because the film strength is weak and it is too flexible. Ultra-thin films made from ethylene copolymers and microporous polyethylene membranes, which have been difficult to achieve, or polyethylene 4%, which can be made into microporous membranes before, during, or after sulfonation.
A composite film in which at least one layer of M-lipid film is firmly adhered to each other is obtained by sulfonation and, if necessary, treatment such as hydrolysis and/or neutralization. At least one functional group selected from OH group or COOR group Preferably the functional group is carboxylic acid, carboxylate or OH group.
at least 0.2 meq/gram of hydrophilic groups,
Semi-permeable ultra-thin hydrophilic membrane preferably containing 1 to 5 meq/g of sulfonic groups, preferably having a thickness of 10 to
Ultrathin hydrophilic membrane of 0.05 μm, more preferably 5 to 0.05 μm, and even more preferably 1 to 0.05 μm, and a sulfonated polyethylene microporous membrane, preferably at least 0.05 meq/g of sulfone. It is a composite membrane made of a microporous polyethylene film containing a group, and by making the ultrathin film containing an ethylene copolymer extremely thin, it is possible to shorten the length of the film other than sulfonation. The ideal semi-permeable, ultra-thin hydrophilic membrane part has the characteristics of few undesirable side reactions, high separation coefficient and high permeation rate desirable for separation membranes, and has excellent heat resistance, solvent resistance, mechanical strength, and hydrophilicity. This is a composite hydrophilic membrane with extremely ideal separation membrane characteristics, consisting of a reinforcing material part with excellent properties.

In the composite hydrophilic membrane of the present invention, the semi-permeable ultra-thin hydrophilic membrane has the characteristics of a semi-permeable membrane and is a homogeneous membrane without so-called microporous, gas permeable. A membrane having the property of separating water and alcohol in the pervaporation method or pervaporation method, with a sulfonic group content of at least 0.2 milliequivalents/gram, a separation coefficient and a permeation rate of 9 degrees. It is a composite hydrophilic membrane that is particularly excellent as a separation membrane. Furthermore, if the content of sulfonic groups becomes extremely large, the oxidative deterioration resistance will decrease, so it is preferably 1 to 5 milliequivalents/gram.

In the composite hydrophilic membrane of the present invention, the ultra-thin hydrophilic membrane is firmly adhered to and integrated with the microporous membrane. Even if the resistance is low electrical resistance, which could not be obtained by conventional methods, it becomes difficult to freely swell in an aqueous solution, so even if an ultra-thin hydrophilic film is oxidized during use, it will not swell at a relatively early stage. The characteristics of the composite hydrophilic membrane are highly durable (
oxidative deterioration resistance) film. In addition, as mentioned above, the composite hydrophilic membrane of the present invention is obtained by reacting the composite film with a sulfonating agent, so that the microporous surface of the polyethylene microporous membrane having a large surface area is exposed to the sulfonating agent. contact,
As a result, a composite hydrophilic membrane having a microporous membrane whose microporous surface is primarily sulfonated can be obtained.

Since the microporous surface of the polyethylene microporous membrane mainly has sulfone groups, it has a high affinity for liquids with high surface tension, such as water, and is a composite hydrophilic membrane with excellent wettability and liquid retention. (2) A composite hydrophilic membrane with excellent heat resistance because it is difficult to melt thermally; (3) A composite hydrophilic membrane with excellent solvent resistance because it has a significantly low affinity for organic solvents. This is a composite hydrophilic membrane that has properties such as being able to maintain the strength and oxidation resistance of the polyethylene resin used as a reinforcing material because most of the polyethylene resin other than the +41 m porous surface does not have sulfone groups. becomes.

As a result, the composite hydrophilic membrane of the present invention is suitable for separating or concentrating valuable components more selectively than liquid or gaseous mixtures, and is particularly suitable for permeating water more selectively than water-organic mixtures. This makes it suitable as a separation membrane for

Furthermore, as mentioned above, the composite hydrophilic membrane of the present invention has a microporous surface that is highly wettable to liquids with high surface tension such as water, so when used as a diaphragm for secondary batteries, When the amount of liquid in the battery changes and the membrane becomes partially dry, when liquid is added to the battery, it immediately wets and becomes usable with a low resistance value. Furthermore, when the membrane of the present invention is used as a diffusion dialysis membrane, once the membrane is used and the water-containing liquid to be subjected to separation is exhausted and the membrane is once in a dry state, it cannot be washed with alcohol, glycol, etc. Even without pretreatment such as taking care of the surface, it does not repel water-containing liquid (wetting), and its performance as a dialysis membrane quickly recovers.

In addition, as mentioned above, the microporous surface of the composite hydrophilic membrane of the present invention has high liquid-retaining properties and water-retaining properties. It has the advantage of low surface contact resistance.

The ethylene copolymer referred to in the present invention is one that has at least one hydrophilic group selected from the group consisting of -OH and 100OR groups before, during, or after sulfonation reaction, and An ethylene copolymer that can be reacted to form an ultra-thin hydrophilic film having at least 0.2 meq 10 sulfone groups substantially uniformly in the cross-sectional direction of the ultra-thin film, such as the following general formula (I).

(II) (-CH2CHa + (D 1 +CJi2- C+ (If)2 [wherein, R, = T (or -aH8, a2 = -000
Ra.

-C0OR4 or -oH (where island=C, hydrocarbon group of ~C6, R4=H, hydrocarbon group of ~C6, ions that can form salts with alkali metals or other carboxyl groups)) Ethylene copolymers containing units as a main component are preferably used. In this case, those containing 1 to 18 mol % of units represented by formula (II) are preferred.

Ethylene-based copolymers with such a structure consist of ethylene and
Copolymerization with one or more comonomers selected from comonomers that can form the unit represented by formula (II), or at a certain temperature, saponification or neutralization treatment is carried out as necessary after the copolymerization. It can be obtained by doing. In addition, the ethylene copolymer of the present invention may include a copolymer of other monomers other than the above-mentioned ethylene and a comonomer that can form the unit represented by formula (II) within a range that does not depart from the purpose.

Furthermore, the resin composition containing an ethylene copolymer in the present invention is a resin composition containing at least 15% by weight of the above ethylene copolymer and at most 85% by weight of another thermoplastic resin. Things are suitable for use (・
It leaks.

In the present invention, since the film made of ethylene copolymer is extremely thin, it contains fewer comonomer components than a hydrophilic film obtained by introducing sulfone groups into a conventionally known ethylene copolymer film. There is also a characteristic that the desired hydrophilic membrane can be obtained, and conversely, even with a high proportion of comonomer components, there are methods of adding other thermoplastic resins, and microporous membranes / ultra-thin films / The layered structure of the microporous membrane eliminates problems caused by the blocking properties of the film before sulfonation, so the comonomer component can be appropriately selected without departing from the purpose. %, the sulfonation reaction time becomes longer and side reactions other than sulfonation tend to occur, making the ultra-thin hydrophilic membrane brittle and requiring careful handling. Due to the small amount of functional groups (・), the separation performance is low, so there are limitations in terms of use.

On the other hand, if the content exceeds 18 mol%, it becomes necessary to add a large amount of other thermoplastic resin to prevent blocking of the ultra-thin film, or to adopt the above-mentioned layer structure in order to obtain a practical film. The water permeation rate of the composite hydrophilic membrane may be reduced or there may be restrictions on the manufacturing method, so the above-mentioned range of 1 to 18 moles is preferred.

In particular, ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer,
Ethylene-methacrylic acid copolymer metal salt, ethylene-methyl methacrylate-methacrylic acid copolymer metal salt, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid copolymer metal salt At least one type of ethylene-based coelectrolyte selected from the group consisting of the following is preferred from the viewpoint of reactivity with the moldable sulfonating agent and water resistance of the sulfonated membrane.

In the present invention, other thermoplastic resins are thermoplastic resins that can be blended relatively uniformly with the ethylene copolymer and are relatively inert to sulfonating agents, such as: polyethylene, polypropylene, 1
, 2-polybutadiene, and polybutene-1. at least one thermoplastic resin,
The hydrophilic film obtained from the ultrathin film containing the thermoplastic resin becomes a composite hydrophilic film that is highly resistant to oxidative deterioration.

In the present invention, the amount of other thermoplastic resins added is at most 85% by weight, and if this value is exceeded,
The reaction time with the sulfonating agent is long, and the rate of water permeation through the separation membrane is low, making it difficult to obtain the desired composite hydrophilic membrane.

In addition, the ions that can form salts with other carboxyl groups in the present invention include, for example, Mg" + Ca
" + Zn" + divalent metal ions such as Ba2+,
In addition to trivalent metal ions such as At3+, -C such as NH4+
It means a cation that can form a salt with the 00- group. Furthermore, the sulfone group of the present invention is similar to the carboxyl group.
It is clear that it can be used in the form of a salt with an alkali metal or other cation other than H. Here, other cations include, for example, Mg'', Ca'',
Zn”, divalent metal ions such as Ba2+, A t
It means a cation that can form a salt with a trivalent metal ion such as 3+ or a sulfonic group such as NH4''.

Next, the microporous polyethylene membrane or the polyethylene resin film that can be used as a microporous membrane in the present invention refers to the ultrathin film containing the ethylene copolymer and the microporous membrane with large micropores. There are no particular restrictions on polyethylene resin films that can be formed into microporous films within a temperature range where the parts do not melt and collapse, and are microporous films that can be strongly thermally bonded and firmly bonded without peeling during sulfonation or use. Alternatively, the composite hydrophilic membrane is a resin film that has a reinforcing effect and has the desired water permeation rate, electrical resistance in the electrolyte, and area swelling rate after the sulfonation reaction, and the desired water permeation rate in the electrolyte. It is obvious that polyethylene should be selected from those that are sufficiently smaller than the electrical resistance and areal swelling rate of After mixing an inorganic powder adsorbed with an organic liquid such as dioctyl tetalate, it is melt-molded into a film, and then the organic liquid alone or the organic liquid and the inorganic powder are extracted from a polyethylene microporous membrane. This method is suitable because the porosity of the microporous membrane from which the polyethylene resin film is obtained before extraction can be freely controlled, the average pore diameter is relatively small, and it can be stretched.

In addition, there are microporous membranes obtained by mixing polyethylene with various other substances to be extracted and melt-molding them into a film to extract the substances to be extracted, or polyethylene resin films before extraction. or a polyethylene resin film that can become a microporous membrane before or during stretching or sulfonation.

Furthermore, the above-mentioned microporous membrane or resin film may contain various resins within the range that does not deviate from the purpose. Various ethylene copolymers added to polyethylene in an amount of at most 50% by weight can be used.

The porosity, average pore diameter, and pore diameter distribution of the microporous membrane may be appropriately selected depending on the manufacturing method and application of the composite hydrophilic membrane, and usually,
Porosity 20-80%, average pore size 0, OO5-10μ
m, preferably 0.0.1 to 1 pm.

A microporous membrane with a small (uniform) pore size distribution can be made into the composite film from a water membrane, and reacted with a sulfonating agent either unstretched or after stretching to introduce sulfone groups onto the microporous surface.

The same applies when converting a polyethylene resin film portion that can become a microporous membrane from a composite film into a microporous membrane. By forming this, the desired composite hydrophilic membrane can be obtained.

The thickness of the microporous membrane portion of the composite hydrophilic membrane is appropriately selected depending on the manufacturing method and application of the composite hydrophilic membrane, and the thickness of the ultra-thin hydrophilic membrane, but is usually 10 μm or more (about 10 μm or more depending on the reinforcing effect and handling). Preferably.

And the ratio of the thickness of the microporous membrane to the thickness of the thin hydrophilic membrane is:
It may be determined appropriately depending on the electrical resistance in the electrolytic solution, the number of layers of the microporous membrane and the ultra-thin hydrophilic membrane, the thickness of the composite hydrophilic membrane, etc., but usually the ultra-thin hydrophilic membrane is thin, and/or electrolysis of a composite hydrophilic membrane is desirable, usually 05 to 10
The desired composite hydrophilic membrane can be obtained at about 0.00.

The composite hydrophilic membrane of the present invention has at least one layer each of an ultrathin film of an ethylene copolymer having the above-mentioned specific chemical structure and a microporous polyethylene film or a polyethylene resin film that can become a microporous membrane. At the interface, the substance constituting at least one layer melts or softens,
It wets the surface of the other substance and solidifies, or two layers of substances form a mutually compatible layer at the interface.
Alternatively, the softened or melted material of one layer may be absorbed into the four parts of the surface of the other layer (inclusion 4), or it may solidify in a structure in which the material is eroded, or by a combination of these, etc. It refers to a state in which the layers are closely and firmly integrated.In practice, it means that the layers do not peel off during mechanical operation, or even during sulfonation or microporous treatment.
It refers to the state in which the two layers are integrated. Such fusion may be achieved by heat, pressure, or a combination thereof.

Furthermore, in the present invention, the fusion between the ultrathin film of the ethylene copolymer and the microporous polyethylene membrane or the polyethylene resin film that can become the microporous membrane is performed uniformly and firmly over the entire surface. preferable. If there are areas that are not bonded or have insufficient adhesive strength, a large amount of sulfone groups may be introduced into the ultra-thin film of the ethylene copolymer having the above-mentioned specific structure during the sulfonation treatment. , the ultra-thin film portion swells violently, causing blisters and uneven processing, which is undesirable.

In addition, the layer structure of the microporous membrane and the ultra-thin hydrophilic membrane of the composite hydrophilic membrane of the present invention is not particularly limited, but usually the ultra-thin hydrophilic membrane/
Microporous membranes, microporous membranes/ultra-thin hydrophilic membranes/wt porous membranes, ultra-thin hydrophilic membranes/microporous membranes/ultra-thin hydrophilic membranes are preferred from the performance and economical standpoints, and especially in separation membrane applications, separation In terms of performance, abrasion resistance, scratch resistance, stain resistance, etc., a composite hydrophilic membrane having a layer structure of a microporous membrane and an ultrathin hydrophilic membrane/microporous membrane is preferred.

In addition, microporous membranes containing polyethylene or polyethylene and ethylene-based copolymers generally do not have hydrophilic properties, so they have poor wettability with aqueous solutions such as electrolytes.
As mentioned above, in the composite hydrophilic membrane of the present invention, although the content of sulfonic groups is small in terms of exchange capacity, the microporous surface is primarily sulfonated, resulting in improved heat resistance and solvent resistance. For the purpose of keeping the handling of the composite hydrophilic membrane more stable in the atmosphere or for applications that require further hydrophilization, conventionally known methods such as 1.
For example, a method of impregnating with hydrophilic compounds such as glycerin, polyethylene glycol, various alcohols, etc. is preferable because it makes it hydrophilic or increases water retention, and it also makes it easier to handle the composite hydrophilic membrane in the atmosphere. Needless to say.

The content of sulfone groups in the microporous membrane described above is determined by the porosity, pore diameter, thickness, and type (high-density polyethylene, medium-density polyethylene, low-density polyethylene, ethylene copolymer, and other organic Or, the blending ratio of inorganic compounds) and the desired effect, but usually the porosity is 50-90% and the average pore diameter is 0401-90%.
A 1μ high-density polyethylene microporous membrane with markedly improved hydrophilicity, heat resistance, and solvent resistance at an exchange capacity of 0.05 milliequivalent or more per 1g of the weight of the microporous membrane part. Therefore, in the composite hydrophilic membrane of the present invention, usually 1
Although it does not exceed milliequivalents/gram, excessive sulfonation may reduce the reinforcing effect of the microporous membrane in terms of its strength, swelling ability in aqueous solution, oxidative deterioration resistance, etc. It is preferable to select a microporous membrane as appropriate, taking into consideration the type, thickness, electrical resistance of the composite hydrophilic membrane, etc., and to avoid excessive sulfonation.

As mentioned above, the composite hydrophilic membrane of the present invention has particularly excellent characteristics as a separation membrane, and can be used, for example, in diffusion dialysis membranes, reverse osmosis membranes, pervaporation separation membranes, gas separation membranes, and other various membrane separation methods. This membrane is particularly suitable as a separation membrane for

An example of using the composite hydrophilic membrane of the present invention as a separation membrane in a pervaporation method and a gas separation method will be described below.

The method of using the composite hydrophilic membrane of the present invention in pervaporation and gas separation methods is to contact the feed side with a liquid or gaseous mixture through the composite hydrophilic membrane of the present invention, and to contact the permeate side with a liquid or gaseous mixture. This is a separation and/or concentration method that utilizes the difference in membrane permeability of mixture components by contacting them with a carrier gas or keeping them under vacuum. A particularly effective mixture in this method at 0.degree. C. is a mixture of water and an organic substance, and water can be permeated with high selectivity in either a liquid or gaseous mixture.

The carrier gas mentioned here is not particularly limited, and if the mixed liquid is a water-organic mixture, for example, air can have a large concentration difference between the supply side and the permeate side, and the permeate component and air can be separated. It is effective because it is easy to carry out (however, if the permeated component contains almost no organic matter and no water is particularly required, it can be released into the atmosphere as it is) and because it is cheap.

The water-organic mixture referred to herein is a liquid or gaseous mixture obtained from a mixture of at least one type of organic substance and water. A method in which a mixture is brought into contact with a separation membrane in a liquid state is called a pervaporation method, and a method in which a mixture is brought into contact with a separation membrane in a gaseous state is called a gas permeation method.

Using the pervaporation method and gas separation method described above, hydroxyl or carboxylic acid salts can be selectively produced, especially over water-organic mixtures (. has at least one hydrophilic group selected from OH groups). A composite hydrophilic membrane having an ultra-thin hydrophilic membrane is preferred; furthermore, the higher the content of sulfonic groups in the ultra-thin hydrophilic membrane, the better the separation coefficient and water permeation rate, and the more selective it is than the water-organic mixture. It permeates water at a high temperature and permeation rate, separating water and organic matter.

Then, by the above-mentioned pervaporation method, the separation coefficient α ”
(A=water, B-ethanol-A/) is 2 or more, A/B is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, and the water permeation rate is 200 g/
1lpjX2 or more, preferably 5009/h11m" or more, especially when the thickness of the ultra-thin hydrophilic membrane portion is 1 μm or less, the separation membrane can easily separate water and ethanol at 1000g/hr, rn2 or more. Also, at high temperatures Even under these conditions, the composite hydrophilic membrane of the present invention has excellent heat resistance, so a higher permeation rate can be achieved by increasing the temperature.

The reason why the composite hydrophilic membrane of the present invention allows water to permeate highly selectively even from ethanol water, which has an extremely high affinity with water, such as ethanol, is due to the presence of active sulfone groups and other functional groups.
Preferably, the hydrophilic groups break up the water-ethanol interaction, and at the same time water dissolves and diffuses into the ultra-thin hydrophilic membrane, whereas ethanol is hardly soluble in the membrane and does not dissolve in the feed liquid. It is presumed that this was because he wanted to remain on his side.

By the above method, various water-organic compound azeotropic mixtures that could not be separated by conventional distillation methods, for example,
In addition to the water-ethanol mixed solution, water-propanol, water-ingbanol, water-8ec-butanol, water-t
ert-butanol, water-diacetone alcohol, water-
Tetrahydrofuran, water-dioxane, water-pyridine,
Highly purified organic components can also be easily obtained from azeotropic mixture compositions such as water-hexylamine.

Further, in the separation method using the gas permeation method described above, by keeping the permeation side in an absolutely dry state, organic components hardly pass through the membrane, and water is allowed to pass through the membrane with high selectivity.

Although this separation method has the characteristic of having a higher separation coefficient than the pervaporation method, it has the disadvantage that the water permeation rate is rather low. Applications where the purpose can be achieved even if the amount of water permeated is relatively small, such as applications that separate water without losing odor, applications that separate water from products that emit a bad odor without releasing the odor, or applications that achieve the purpose even if the amount of water permeated is relatively small, or extremely high. It is especially suitable for applications that require a high separation factor.

The water-organic compound mixture that can be applied to the composite hydrophilic membrane of the present invention is a liquid or gaseous mixture obtained from a mixture of at least one type of organic substance and water, and is not particularly limited. It's not something you can do. Examples of such organic substances include monohydric alcohols such as methanol, ethanol, propatool, butanol, pentanol, hexanol, and octano-cyclohexanol, dihydric alcohols such as ethylene glycol, and glycerin. trihydric alcohols such as acetone, methyl ethyl ketone, ketones such as cyclohexane, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, methylamine rub, ethyl cellosolve, formic acid, acetic acid, propionic acid, acrylic acids, methacrylic acid, crotonic acid,
Maleic acid, maleic acid half ester, organic acids represented by maleic anhydride, amines represented by methylamine, ethylamine, ethylenediamine, methyl acetate, ethyl acetate, vinyl acetate, acrylic ester, methacrylic ester, crotonic acid Esters, esters represented by maleic diester, hydrocarbons represented by butane, pentane, hexane, octane, cyclohexane, cyclohexene, benzene, toluene, xylene, styrene, ethylbenzene, acetamide, N-methylacetamide, N, N-dimethylacetamide, nitrobenzene, dimethylformamide, nitrogen-containing solvents represented by nitroethane, dimethyl sulfoxide, sulfur-containing solvents represented by carbon disulfide, chloroform, carbon tetrachloride, monochlorobenzene, monochloroacetic acid, 1,1
．． 1-) In addition to halogen-containing solvents represented by dichloroethane, other organic substances that are gaseous, liquid, or solid at room temperature may be used.

Then, in the water-organic compound mixture (・te).

For mixtures that form a homogeneous mixed solution at room temperature, either the gas permeation method or the pervaporation method can be easily applied. In addition, membrane separation is not very effective in practical use in water-organic compound mixture systems that are heterogeneous at room temperature, but it is used for purposes such as aroma preservation, such as concentrating coffee and fruit juices. The method for separating water using the above method can be applied to special applications such as applications where the purpose is to separate malodorous components or toxic substances without releasing them to the outside.

Since the composite hydrophilic membrane of the present invention has excellent solvent resistance, it goes without saying that water can be efficiently and durablely separated from various water-organic compound mixtures containing trace amounts of water of 1% by weight or less. It is especially suitable for removing trace amounts of water from organic solvents containing stabilizers and other additives without losing the stabilizers and other additives.

In addition, in order to use the composite hydrophilic membrane of the present invention to transmit water with high selectivity by pervaporation method or gas separation method, it is necessary to use the composite hydrophilic membrane of the present invention because the water permeation rate is high. In order to keep the water vapor concentration on the permeate side low, the flow rate of the carrier gas should be increased or the degree of vacuum should be sufficiently low, and the mixture should be sufficiently stirred to keep the concentration polarization on the feed side low. is desirable.

When the water vapor concentration on the permeation side approaches the vapor pressure of water, both the separation coefficient and the water permeation rate decrease, so the above precautions are required, especially for water-organic mixtures with a high water content.

In addition, depending on the type of counter ion of the carboxyl group and/or sulfone group of the composite hydrophilic membrane of the present invention, the affinity for water or organic matter and the dissociation property in an aqueous solution will naturally change, so the separation performance will naturally change. It is desirable to select the type of counter ion appropriately depending on the method, type of mixture, and purpose. For example, in order to concentrate low-concentration ethanol water obtained by fermenting biomass by pervaporation method, B a
By selecting a counter ion with a relatively low degree of dissociation, such as the 2+ ion, a high separation coefficient can be maintained; conversely, in a region where the water permeation rate decreases, such as the azeotrope composition of ethanol water, the K+ It is desirable to maintain a high water permeation rate by selecting a counterion with a large amount of coordinating water, such as Na + ion or Na + ion.

Then, by using the composite hydrophilic membrane of the present invention, waste heat, which has conventionally been of relatively low value, such as heat in the atmosphere, heat from heated waste water, or reaction heat generated during fermentation, is utilized from the ethanol. It has now become possible to produce highly concentrated ethanol with extremely low energy.

Furthermore, to describe an example of the use of the composite hydrophilic membrane of the present invention, it has the characteristic that it can be applied to the separation of mixtures containing inorganic gas components such as He-air or He-CH2.

In addition, the composite hydrophilic membrane of the present invention is particularly capable of synthesizing an ester from an alcohol and an organic acid through the catalytic action of -8O8I, and by the above-mentioned pervaporation method, it is possible to synthesize an ester from an alcohol and an organic acid on the feed liquid side. It is also possible to bring a mixed solution of organic acids into contact with each other and allow the water generated by the esterification reaction to quickly permeate to the permeate side to advance the reaction equilibrium in the desired direction. It has the characteristic that it can be used in various reaction systems that utilize permeability.

In addition, the composite hydrophilic membrane of the present invention is characterized by low electrical resistance in an electrolytic solution, and because the semipermeable ultra-thin hydrophilic membrane is backed and the membrane strength is strongly maintained at °C, for example, The resulting film has an electrical resistance value of 0.01Ω and Cm2 in an alkali, which was difficult to achieve with conventionally known films.

In addition to the properties of the separation membrane described above, the composite hydrophilic membrane of the present invention has properties of the ethylene copolymer film having sulfone groups: (2) it has excellent cation exchange performance and barrier performance against anions; has a small electrical resistance in an electrolyte (e.g. 5 to 0.010 in an alkaline solution).
・Cm2), (3) has a barrier property against zinc ions in alkali, (4) has a low permeability coefficient for methanol, and (5) is difficult to pass lipophilic compounds. In addition to its uses (11) cation exchange membrane uses (electrodialysis, diaphragms, electrolytic separation membranes, electroosmotic diaphragms, etc.), (21) for various batteries such as Ni-Zn alkaline secondary batteries (7) (lator-1 (3) ) Fuel cell diaphragms used in fuel-dissolved fuel cells, (4) Smoke casings, etc., with low electrical resistance properties, rear properties against anions, performance of semipermeable membranes, and lipophilic compounds (rear properties). Needless to say, it can be used for a variety of purposes, including

Specifically, the cation transfer number is 0.90 or more and the permeability of zinc ions to the electrodialysis membrane is 2000 μy-/hr-c.
i or less and the electrical resistance in alkali is 20・aIIL
2 or less, preferably 1 Ω/2 or less, the separator K for nickel-zinc alkaline batteries, and a membrane with low electrical resistance and electrolyte diffusion coefficient to the diaphragm for electroosmotic dehydration, has a high water permeation rate and The composite hydrophilic membrane of the present invention has a high membrane strength and can be used for smoke casing applications.As mentioned above, the composite hydrophilic membrane of the present invention has low electrical resistance in various electrolytes, excellent cation exchange performance,
The fact that the semi-permeable ultra-thin hydrophilic membrane in the composite hydrophilic membrane of the present invention has barrier properties against anions and zinc ions in alkali and also has excellent separation performance as a separation membrane. This strongly suggests that the structure has the following characteristics: (1) there are no pin poles, (2) the thickness is thin and uniform, and (2) the sulfone groups are uniformly distributed.

Next, regarding the method for manufacturing the composite hydrophilic membrane of the present invention, R4=E
, O, ~C6 hydrocarbon groups, alkali metals, or ions that can form salts with other carboxyl groups)] and an aqueous dispersion containing an ethylene copolymer of ethylene and a monomer having the structure A microporous polyethylene film or a polyethylene resin film that can become a microporous polyethylene film before sulfonation and/or sulfonation is coated with the ethylene copolymer coating. A composite hydrophilic membrane is prepared by firmly adhering to a film to form a composite film, making the resin film a microporous membrane before and/or during sulfonation, and then reacting the composite film with a sulfonating agent. This is the manufacturing method.

In this method, the method of applying the aqueous dispersion to the microporous membrane or the resin film is, for example, a coating method using a tool such as a coach-in-blonde or an air knife, since a coating film with a particularly uniform thickness can be formed. Particularly effective methods include a method of spraying the aqueous dispersion with an air gun, or a method of immersing the microporous membrane in the aqueous dispersion at a temperature of 0.degree. In addition, the method of forming a coating film (ultra-thin film) from an aqueous dispersion and firmly adhering it to a microporous membrane or the composite film can be carried out using the usual methods, such as evaporating water at room temperature or hot, heat treatment, or hot press. Then, a composite film can be obtained.

Furthermore, before applying the aqueous dispersion to the microporous membrane or the resin film, ethanol, propyl alcohol, ethylene glycol, chrycerin, or other wettability-improving compound may be added to the aqueous dispersion and/or the microporous membrane or the resin film. Addition or coating is preferred from the viewpoints of uniform thickness, pinhole resistance, and adhesive strength.

In addition, in order to obtain particularly ultra-thin hydrophilic films, it is particularly effective to dilute the aqueous dispersion with water and apply it at a low concentration, and/or to stretch it in at least one axis before sulfonation. In this method, the thickness of the semipermeable ultrathin hydrophilic membrane is 0.
．． Composite hydrophilic membranes with a diameter of about 0.05 μm can be produced.

In particular, when ultra-thin hydrophilic films are thin, for example, 1 μm or less, a film obtained only by diluting the aqueous dispersion with water, etc., and a film obtained by stretching may be used. Comparing the membranes, the latter membrane has superior separation performance, and the stretching method described above is superior to 1. It is particularly effective for producing a composite hydrophilic membrane having an extremely thin hydrophilic membrane.

In addition, in a stretched composite film, the porosity and average pore diameter of the polyethylene microporous membrane increase compared to the unstretched film, so the reactivity with the sulfonating agent increases and the sulfonation There are two characteristics: an increase in water permeation rate and a decrease in electrical resistance in the electrolyte.

By appropriately selecting the microporous membrane or the resin film, the area stretching ratio in the temperature range of usually 50 to 130'C can be increased to 2 times or more, more preferably 4 times or more.
The desired composite hydrophilic membrane can be obtained by stretching the resin film twice or more to sulfonate it or, if necessary, making the resin film into a microporous membrane and then sulfonating it.

And even if the thickness of the ultra-thin hydrophilic film is extremely thin,
The reinforcing effect of the microporous membrane makes it a practical membrane with excellent mechanical strength and oxidative deterioration resistance.

In this production method, the aqueous dispersion of an ethylene copolymer is one in which the above-mentioned ethylene copolymer is dispersed in water alone or in a state containing a surfactant, and there are no particular restrictions. Although the average particle size of dispersed particles is about 0.01 to 0.05 μm, the desired composite hydrophilic membrane can be obtained.

Also, in this method, from among ethylene and copolymers, those that form an aqueous dispersion are suitable. Preferably, the ethylene copolymers are ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymers, etc. acid methyl copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid copolymer metal salt, ethylene-methyl methacrylate-methacrylic acid copolymer metal salt, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid At least one ethylene copolymer selected from the group consisting of acid copolymers and ethylene-acrylic acid copolymer metal salts.

By the above method, the layer structure of the composite hydrophilic membrane is usually changed to ultra-thin hydrophilic membrane/microporous membrane or ultra-thin hydrophilic membrane/
From the economical and practical standpoints, it is preferable to manufacture with a microporous membrane/ultra-thin hydrophilic membrane or a micro-porous membrane/ultra-thin hydrophilic membrane/fllf porous membrane.

When a highly stretched and oriented ethylene copolymer film was reacted with a sulfonating agent using a conventionally known method, there was a problem that the film would shrink during sulfonation, but according to the present invention, the film shrinks during sulfonation. Because it is backed with a microporous membrane that resists shrinkage force or a reinforcing material made of the resin film, even when sulfonated, it is fixedly supported by the reinforcing material, and when stretched, the film shrinks rapidly and becomes sulfonated. It is something that can be done.

The reaction with the sulfonating agent carried out to obtain the composite hydrophilic membrane of the present invention will be explained in detail. It is sufficient to react with a sulfonating agent such as diluted 1 or a complex compound of sulfur trioxide, and it is particularly preferable to react with fuming sulfuric acid containing 5 to 30% by weight of sulfur trioxide. be. The temperature and time of the sulfonation reaction are not particularly limited, but the temperature condition is 60°C or less, and the time is within 2 hours at most, preferably within 1 hour, except for sulfonation. This is suitable because there are few side reactions, and by appropriately selecting the conditions within these conditions, the desired composite aqueous membrane can be stably obtained. After reacting with the sulfonating agent, the reaction solution adhering to the membrane is diluted, thoroughly washed with water, neutralized with an alkaline reagent such as potassium carbonate or potassium hydroxide, thoroughly washed with water, and dried. It is practically convenient to handle. Furthermore, it is also effective to hydrolyze the ester with acid or alkali, if necessary, in order to obtain the composite hydrophilic membrane that is the object of the present invention. Furthermore, in the method for producing the composite hydrophilic membrane of the present invention, as proposed in Japanese Patent Application No. 56-15798, after the reaction with the sulfonating agent, treatment with a suitable bleaching agent or oxidizing agent is carried out for a short time. It goes without saying that the method of producing a composite hydrophilic membrane having the desired electrical resistance in the electrolytic solution can be applied.

Can be done.

This method for producing a composite hydrophilic membrane maintains the properties unique to the sulfonated membrane of an ethylene copolymer as described above, can significantly reduce the thickness of the ultra-thin hydrophilic membrane, and Since the porous membrane is suitably sulfonated, the membrane is particularly suitable as a separation membrane with excellent heat resistance, solvent resistance, and hydrophilicity.

In particular, a composite hydrophilic membrane manufactured in the form of a hollow fiber is suitable because it has a large membrane surface area per unit volume.

To explain the method for manufacturing a hollow composite hydrophilic membrane, the above-mentioned ethylene copolymer is coated on the inside and/or outside of a hollow fiber-like microporous ethylene membrane or a polyethylene resin film that can be used as a microporous membrane. It can be obtained by applying an aqueous dispersion, adhering the ethylene copolymer coating film and the hollow fiber microporous membrane or the resin film, and then reacting with a sulfonating agent.

As a method for applying an aqueous dispersion of an ethylene copolymer, for example, a hollow microporous membrane or the resin film is immersed in the aqueous dispersion, and the aqueous dispersion is flowed inside the hollow threads. The method is particularly effective in terms of productivity and uniformity of application.

At that time, the method of diluting the aqueous dispersion with water etc. and applying it repeatedly is better than the method of applying the aqueous dispersion at a high temperature once. It is effective for obtaining membranes.

The desired composite hydrophilic membrane in the form of hollow fibers can be obtained by sulponizing the composite film produced by the above method as it is or by stretching it in accordance with a conventional method.

To explain the law, CH22/R as a comonomer component.

C [However, in formula 17, R, = H, CH3, R2 = oc
o bird.

\R2 -C0OR,4 (However, R3= C, -C, hydrocarbon group.

An ethylene copolymer of ethylene and a monomer having the structure R4 = H, C, ions capable of forming salts with hydrocarbon groups, alkali metals or other carboxyl groups, or the ethylene A resin composition containing at least one type of ethylene copolymer selected from saponified products of copolymers, or at least 15% by weight of the ethylene copolymer and at most 85% by weight of other thermoplastic resins. Ultra-thin film and microporous polyethylene film, or before and/or during sulfonation and/or
or at least one layer each of a polyethylene resin film that can become a polyethylene microporous membrane after sulfonation;
A composite film can be produced by hot laminating and reacting the composite film with a sulfonating agent.

In this method, the method of adhering the film containing the ethylene copolymer and the microporous membrane or the resin film is such that at least the film or the hydrophilic membrane is bonded to each other before and/or after sulfonation. It is essential not to separate from the porous membrane, and the hot lamination method, which adheres with slight pressure at a temperature of about 70 to 130 degrees Celsius, has strong adhesive strength and makes it easy to obtain a composite hydrophilic membrane. , is particularly effective.

Then, the composite film having a polyethylene microporous membrane is stretched in the same manner as in the above method, within a temperature range of, for example, 50 to 130, at which the microporous portions of the microporous membrane can be stretched without thermally fusing.
By stretching the membrane at a temperature range of ℃, preferably at a stretching ratio of 2 times or more, preferably 4 times or more, and reacting with a sulfonating agent, the desired semipermeable ultra-thin hydrophilic membrane can be obtained. A composite hydrophilic membrane can be obtained.

In addition, in the composite film containing the polyethylene resin film, the polyethylene film is made into a microporous film before and/or after stretching and/or after sulfonation, and by reacting with a sulfonating agent, the desired A composite hydrophilic membrane can be obtained.

In this production method, a film containing an ethylene copolymer is selected from various thermoplastic resins relatively inert to sulfonating agents, such as polyethylene, bo-1nopropylene, 1,2-polybutadiene, and polybutene-1. By containing at least one selected thermoplastic resin, it is possible to obtain a composite hydrophilic membrane that is particularly resistant to oxidative deterioration. Here, the blending amount of the thermoplastic resin is at most 85% by weight, and if this value is exceeded, the sulfonation time becomes long and at the same time it is difficult to obtain a composite hydrophilic membrane with a high water permeation rate. A value of % by weight or less is appropriate.

In this method, stretching of the composite film is necessary to obtain an ultra-thin hydrophilic membrane, but by stretching in the same manner as the above method, an ultra-thin hydrophilic membrane can be obtained, and at the same time, especially polyethylene, polypropylene, 1,2
- When a composition containing a type of ethylene copolymer such as polybutadiene polypropylene-1, which is a blend of a sulfonating agent and a relatively inert thermoplastic resin, is used as a hydrophilic film, stretching is difficult. It works very effectively and maintains oxidation resistance even after the introduction of sulfonic groups, even though the membrane is thin.

It is presumed that such an effect is obtained because the thermoplastic resin, which is relatively inert to the sulfonating agent in the blend composition, is arranged in a fibrous form by stretching, thereby increasing the reinforcing effect. In addition, in conventionally known methods, ethylene copolymers that are difficult to implement as sulfonated membranes, such as those with a low co/mer component ratio, such as less than 3 mol%,
Even in ethylene copolymers in the region of 1 mol% or more,
In the production method similar to the above method, in the region where the comonomer component ratio is small, it can be carried out by making the film made of the resin composition containing the ethylene copolymer thinner, so that the ethylene comonomer component ratio is substantially reduced. The desired composite hydrophilic membrane can be obtained from the system copolymer. In particular, in films made of resin compositions containing ethylene-based copolymers with extremely high comonomer component ratios, polymers that are relatively inert to sulfonating agents, such as polyolefin resins such as polyethylene, may be used. Crosslinking by mixing in large amounts and/or by electron beam irradiation is particularly preferred in order to improve the solubility resistance to sulfonating agents and the like and the oxidative deterioration resistance.

The composite hydrophilic membrane obtained by this method has various shapes as described above, such as film, tube, hollow fiber, and bag, and is an extremely useful membrane used for the various purposes described above. becomes.

It is also effective to add an inorganic filler such as titanium oxide, aluminum oxide, etc. to the hydrophilic membrane and/or the microporous membrane to improve other properties such as membrane strength.

To explain yet another manufacturing method, a polyethylene resin composition (
1) and one-half hydrocarbon group as a comonomer component, R
4=H, C, ~C6 hydrocarbon group.

selected from ethylene-based copolymers of ethylene and monomers having the structure of ions capable of forming salts with alkali metals or other carboxyl groups); or at least 15% by weight of the ethylene-based copolymer and at most 85% by weight of another thermoplastic resin, the layer structure is ( 1
) / (II) or (1) / (II)
/ It can be produced by forming the composite film (I) into a microporous membrane after molding and/or during sulfonation and/or after sulfonation, and then sulfonation.

With this method, a composite film consisting of (1) and (II) can be produced in one step, for example, by ordinary extrusion molding, so it is characterized by excellent productivity.

In the present invention, the polyethylene 1-based resin composition (+) that can become a microporous membrane during and/or after molding into a film is a polyethylene resin that can become a microporous membrane as described in the above manufacturing method. This means that the resin composition containing extractable substances before or during sulfonation and forming a microporous membrane after film formation contains the polyethylene described in JP-A-51-74057. or a polyethylene resin composition that contains other extractable inorganic or organic substances and that can form a microporous membrane after extracting the inorganic or organic substances, or other methods, for example, It is a resin composition containing polyethylene or a polyethylene and ethylene copolymer that undergoes phase separation upon stretching to form a microporous membrane. In the present invention, the formation of the microporous membrane is carried out as appropriate depending on the properties of the resin composition (1).

It goes without saying that stretching the multilayer film is also effective in this method as well as in the above method.

In addition, the type of ethylene copolymer and the sulfonation method in this method are the same as the method described above.

The content of sulfonic groups in the ultrathin hydrophilic membrane and microporous membrane in the present invention is based on the weight of the dry membrane in a potassium salt state.

In addition, in the present invention, the content of sulfonic groups, electrical resistance in alkali, cation transfer number, separation coefficient, water permeation rate,
The porosity of the microporous membrane, the average pore diameter of the microporous membrane, the area swelling area in alkali, the permeability of Zn ions, the electrical resistance in dilute sulfuric acid, and the permeability coefficient of methanol were measured by the following methods.

Content of sulfonic groups (milliequivalents/gram) Sulfonic acid (
-8O3H) type membrane with a certain amount of calcium chloride (IN)
It is placed in an aqueous solution to achieve equilibrium, and the hydrogen chloride generated in the solution is reduced to 0. Titrate with IN aqueous solution of caustic soda (potency = f) using phenolphthalein as an indicator, and calculate the value X (mark) as the dry weight W (2) in the potassium salt state.
Electrical resistance in alkali (Ω・crn2) 31
Measuring device (J
The voltage drop due to the sample was measured using a mercury oxide electrode when a constant DC current with a current density of 5 mA/α2 was applied at 23°C between the electrodes (according to IS C2313), and the voltage drop was measured using a mercury oxide electrode. The value calculated from the formula is the electrical resistance. (Immerse the sample in a 31% by weight potassium hydroxide aqueous solution for 24 hours or more before measurement) R1 - Electrical resistance of the sample (Ω・ctn2) ■, = Voltage drop when the sample is not set (g) ■, = Sample Voltage drop when set (g) Using potassium chloride as the cation transporter electrolyte, the membrane potential was determined according to the usual method under the conditions that the concentration on both sides of the sample was maintained at 0.2 Mlo, IM, and the liquid temperature was maintained at 23°C. was measured and calculated using the Nernst equation.

Separation coefficient A sample is set in the apparatus shown in Figure 1, and a water-organic mixture is charged to the feed liquid side using the pervaporation method*1 (pervaporation method), and the water is separated by reducing the pressure on the permeate side.
α water - organic matter, which is a value calculated from the following formula = Separate water using the above method and convert the permeation amount (g) of water per unit time (hr) and unit membrane area (m2).

calculated value.

The larger this value is, the better the separation rate is, and the more productive the membrane separation is.

*Calculated from Kagaku Special Issue, 69 ('76) P, 109.

Average pore diameter of microporous membrane (μm) Calculated by averaging the major and minor diameters of 200 pores observed in scanning electron micrographs of the surface of the microporous membrane Area swelling ratio in alkali (%) 2? Drying area Sa of film area SW in 31% by weight aqueous potassium hydroxide solution at °C (measured after 24 hours of storage) is a value showing the percentage increase in the ratio of zinc oxide dissolved in a 31% by weight potassium hydroxide aqueous solution at a ratio of 409/(l) (solution A) and 31% without zinc oxide. A cell is assembled by contacting a wt% potassium hydroxide aqueous solution (liquid B) through the sample.After being left in a constant temperature room at 23°C for 24 hours, an electrolyte solution is extracted from liquid B, and determined by atomic absorption spectrometry.
Measure the permeated zincate ion, calculate the amount per hour per 1 cm of sample, and convert the value to the amount of zinc as the zinc ion permeability. (μg/hr, ., n2) The sample was set in a measuring device (based on JISC2313) filled with dilute sulfuric acid with a specific gravity of 1.2 (at 23°C), and a constant DC current of 25 rnA/cm2 was applied between the electrodes. Measure the voltage drop due to the sample when electricity is applied, and use the value calculated from the following formula as the electrical resistance in sulfuric acid. (Before measurement, the sample is immersed in dilute sulfuric acid with a specific gravity of 1.2 (at 23°C) for 24 hours or more) (v, -v8) RI2=---(Ω'cm2) 0,025 R,=Sample in sulfuric acid Electrical resistance (Ω・cm2) R8 = Voltage drop when no sample is set (V) ■4-Voltage drop when sample is set (V) Examples 1 to 3 Density polyethylene (density = 0.950') 7cm3
．． 1 containing finely divided silicic acid anhydride (50% by weight) by a conventionally known method from the resin composition obtained from Ml = 1).
40 μm thick polyethylene microporous membrane (porosity -55
% average pore size; 002 μm), and then molded K
, saponification of 93.5 mol% ethylene and 6.5 mol% methyl methacrylate copolymer (saponification degree = 95 mol%)
and -000 obtained by neutralization (degree of neutralization -35 mol%)
0) I, , -C! 00H, and -〇〇〇Na group-containing aqueous dispersion of ethylene copolymer (solid content = 40
% by weight, average particle size = 0.2 μm) was applied using coach-in-blonde.

Next, after heating at 90°C for 1 hour to form an ethylene copolymer coating film, the other microporous membrane described above was applied to the coating film side for 11 hours.
A composite film having a layer structure of microporous membrane/ethylene copolymer/microporous membrane was obtained by bonding under pressure at a temperature of 0°C.

Next, the above composite film was stretched at an area stretching ratio of 6.25 times (length x width = 2.
5 x 2.5) and free sulfur trioxide
It was reacted with fuming sulfuric acid containing % by weight at 35°C, and then washed, hydrolyzed, neutralized, etc. in the order of concentrated sulfuric acid, diluted sulfuric acid, water, potassium hydroxide aqueous solution, and water to form an ultra-thin hydrophilic film. A strongly adhered composite hydrophilic membrane was obtained.

In addition, in the microporous membrane of the above composite hydrophilic membrane, most of the anhydrous fine powder silicic acid is extracted by treatment in an aqueous potassium hydroxide solution, and -COOCHa in the ultra-thin hydrophilic membrane is hydrolyzed. Almost all other carboxyl groups remained in the ultrathin hydrophilic film as carboxylic acid potassium salts. As shown in Table 1, the results show that the ultra-thin hydrophilic membrane part has properties as a semipermeable cation exchange membrane, the polyethylene microporous membrane is sulfonated, and the tensile strength in water is 5009/1. A composite hydrophilic membrane with a width of cm or more was obtained.

Examples 4 to 6 The composite hydrophilic membranes of Examples 1 to 3 were set using the pervaporation device shown in Figure 1, and the pressure on the permeate side was 1 mmH5F temperature was 4
The separation performance of 5 Q Vot% ethanol water was measured under the condition of 0°C, and as shown in Table 2, the separation performance was extremely excellent.

Table 2 Example 7 The composite hydrophilic membranes of Examples 1 to 3 were heated at 115° C. for 30 minutes, but the electrical resistance in alkali did not change and the heat resistance was good.

In addition, the polyethylene porous membrane used in Examples 1 to 3 from which finely powdered silicic acid was extracted was heated under the above conditions, and the electrical resistance in alkali increased by more than 10 times. Example 8 The composite hydrophilic membranes of Examples 1 to 3 were immersed in toluene,
Although it was heated for 5 hours at a temperature of 60°C, the weight did not change at all and the solvent resistance deteriorated.Examples 1 to 3
The polyethylene microporous membrane obtained by extracting fine powder silicic acid from the polyethylene microporous membrane used in
% weight loss.

Example 9 The composite hydrophilic membranes of Examples 1 to 3 exhibited surface tension equivalent to that of water in a wetting test with water.

In addition, the surface tension of the polyethylene microporous membrane used in Examples 1 to 3 from which finely powdered silicic acid was extracted showed a value of 33 dyne/crn in a wetting test, and did not have hydrophilicity. Ta.

Example 10 The composite hydrophilic membranes of Examples 1 to 3 were set in the apparatus shown in Figure 1.
At 40°C and the pressure on the permeate side is I WMHf, 1
-"Y° When the azeotropic mixture compositions of lovanol, 2-glopanol, and hyacetone were separated, all of them had a separation coefficient of 10 or more and a water permeation rate of -s
It showed a value of 1 kg/hr-7712 or more, which is excellent in practical use, and was able to separate water with high selectivity even from an azeotrope.

Example 11 The composite hydrophilic membranes of Examples 1 to 3 were set in the apparatus of FIG.
When apple juice was concentrated twice under conditions of a temperature of 40°C and a pressure on the permeate side of 1 mmHr, the average permeation rate of all composite hydrophilic membranes was 2 ks + 7 m2・hr or more, and the sugar and Almost all of the flavor preserving components remained in the concentrated juice.

The aqueous dispersion of the ethylene copolymer used in Example 1 was diluted and applied to the polyethylene microporous membrane formed in Example 1, heated at 90°C for 1 hour, and then heated at 115°C. Then, they were bonded under pressure to obtain a composite film having a layer structure of microporous membrane/ethylene copolymer/microporous membrane.

The above composite film was stretched at a temperature of 80°C using a tenter method at an area stretching ratio of 4 times (length x width = 2x2), and then sulfonated at 35°C for 5 minutes using a method similar to Example 1. Washing, hydrolysis, neutralization, etc. were performed to obtain a composite hydrophilic membrane in which the ultrathin hydrophilic membrane had sulfone groups of 0.08 milJ/N/g and was firmly adhered to the microporous membrane.

The separation performance of 90 Vot% ethanol water was measured under the same conditions as in Examples 4 to 6. As shown in Table 3, the separation performance was excellent with a high permeation rate for high concentration ethanol water. there were.

Furthermore, the tensile strength of the above composite hydrophilic membrane in water is 70
0 f/cm was medium or higher, which was good.

The aqueous dispersion of the ethylene copolymer used in Example 1 was diluted with water and applied to one side of the polyethylene perforated membrane obtained by molding in Example 1, followed by heat treatment at 115°C for 30 minutes. After that, the membrane was sulfonated at 35°G for 10 minutes in the same manner as in Example 1, followed by washing, hydrolysis, neutralization, etc., so that the ultrathin hydrophilic membrane firmly adhered to the microporous membrane. A composite hydrophilic membrane having a layer structure of an ultra-thin hydrophilic membrane/microporous membrane was obtained.

The results are shown in Table 4. Even in the composite hydrophilic membrane with the above layer structure, 90
The separation performance of Vat% ethanol water was excellent.

In addition, the content of sulfone groups in the microporous membrane is O, 1O milliequivalents/gram, and like the composite hydrophilic membrane of Example 1, it has excellent heat resistance, solvent resistance, and hydrophilicity. The tensile strength of the membrane in water was greater than 5'00 f/crn width.

Example 15 The composite hydrophilic membrane of Example 14 was set in the apparatus of FIG.
1.1 of 100cc containing 00ppm water. , 1-trichloroethane was charged, and the pressure on the permeate side was 51 at 20℃.
When dehydrated for 1 hour under ffAHg conditions, the water content decreased to 40 ppm, 1/10 of the initial content.

In addition, 1,1. ．． 1-) The permeability of dichloroethane is 10
mg, and the added stabilizers (dioxane, butylene oxide, nitromethane) are almost completely lost. It was also demonstrated that it selectively permeates water.

Also, 1,1.1-1! The above composite hydrophilic membrane could be used without any damage even in highly soluble organic solvents such as Jchloroethane.

Examples 16 to 19 Latex containing partially neutralized (degree of neutralization = 30%) ethylene-linked copolymer of 95 mol of ethylene and 5 mol of methacrylic acid copolymer (solid content = 40% by weight)
A mixture of 95 parts by weight and 1 part of isopropyl alcohol was applied to a 200 μm thick microporous membrane formed in the same manner as in Example 1 using coach-in-blonde, and aged at 90°C for 1 hour. A composite film was obtained.

Next, in the same manner as in Example 1, the mixture was reacted with a sulfonating agent, washed, neutralized, washed and dried to obtain a composite hydrophilic membrane. As shown in Table 5, the result was a composite hydrophilic membrane with characteristics as a cation exchange membrane, low electrical resistance, low area swelling in the electrolytic solution, and excellent mechanical strength.

In addition, since the microporous membrane is sulfonated, Example 1
Like the composite hydrophilic membranes in ~3, it has good heat resistance.

It was a composite hydrophilic membrane with excellent solvent resistance and hydrophilicity.

Example 2O The Zn ion barrier properties required for alkaline battery separators having Zn electrodes, typified by Ni-Zn alkaline batteries, were measured for the composite hydrophilic membranes of Examples 18 and 19, and the results are shown in Table 6. As shown, the amount of permeation of KZn ions was small, and it had suitable performance as a separator for alkaline batteries having Zn electrodes. Table 6 Example 21 Dilute sulfuric acid required for various battery diaphragms using dilute sulfuric acid as an electrolyte The low electrical resistance in dilute sulfuric acid was measured for the composite hydrophilic membrane of Example 16.17, and the results are shown in Table 7. It was suitable as a diaphragm for various batteries, having characteristics such as being hydrophilic and having a small area swelling rate in dilute sulfuric acid.

Table 7 Example 22 A copolymer of 94.2 mol% ethylene and 5.8 mol% methyl meth-ilylate was saponified (degree of saponification = 60 mol%).
) and one COOC obtained by neutralization (degree of neutralization = 30 mol%)
20% by weight of high-density polyethylene (density -〇, 955 F/polarized a
, MI=7) in a kneader at a temperature of 190°C for 60 minutes, and then 1. tN of 43 parts by weight, It! + Paraffin (manufactured by Kokusan Kagaku Himashiki Co., Ltd.) was added, and the mixture was further kneaded at 190°C for 30 minutes. Next, the above resin composition was extruded through a die at a temperature of 180° C. using an extruder to obtain a film having a thickness of 3 μm.

The film was then immersed in 1,1,1-trichloroethane to extract the rough-in liquid.

In addition, the dioctyl tstalate used in Example 1, the anhydrous fine powder K = sulfuric acid powder high density polyethylene (density 1 = 0
．． 950 #/d MI = 1) by a conventionally known method, and further, most of the anhydrous fine powder silicic acid was extracted with an aqueous potassium hydroxide solution.
Porosity = 65% Average pore size = 0.15 μm 200
A microporous membrane with a thickness of μm was molded. Next, the front bar thin film and the microporous membrane were bonded together under pressure at 100°C with a pressure of about IK9/C11, and cooled for 1 liter.
A composite film was obtained.

Next, the above 'rN composite film was subjected to /1iLI! at 100°C by the ten-tar method. Stretched under J conditions at an area stretching ratio of 4 times copying x width = 2 x 2), the material was subjected to sulfonation 1, washing, hydrolysis, neutralization, etc. in the same manner as in Example 1, and after drying, A composite hydrophilic membrane with a layered structure of ultra-thin hydrophilic/microporous membrane was obtained. As shown in Table 8, the above composite hydrophilic membrane maintains excellent cation exchange performance even after drying, has low electrical resistance in alkali, small area swelling rate in alkali, and has a lower composite hydrophilic membrane than Example 1. Heat resistant like membrane,
The membrane was excellent in hydrophilicity and tensile strength in water, and was also excellent in barrier properties against Zn ions, and had excellent properties as a separator for Ni-Zn alkaline batteries. Furthermore, when the ethanol water separation performance of the above composite hydrophilic membrane was measured under the same conditions as in Example 12, the separation coefficient was 15 and the water permeation rate was 1'9/hr-m'', which was excellent. It had excellent performance.

Example 23 Anhydrous fine powder silicic acid (specific surface area 200 m27g, average particle size 16 mμ) 14vo1% and dioctyl phthalate (D
OP) 64 vol 1% was mixed into a powder using a Henschel mixer, 22 voj % high density polyethylene powder (MI=1) was added thereto, and the mixture was mixed again using a Henschel mixer. The above mixture was kneaded using an extruder and pelletized.

On the other hand, high density polyethylene (density = 0.955 g/cm3,
MI "" 7) 20% by weight in a kneader at 180%
Resin composition 10 was melt-kneaded at a temperature of ℃ and then recorded at ℃.
40 parts by weight of dioctyl phthalate was added to 0 parts by weight, and the mixture was melt-kneaded, cooled, and pulverized to obtain a mixture containing an ethylene copolymer.

A composite film having a layer structure of (1)/(n) is produced by producing a mixture (II) containing the above polyethylene resin pellets (I) and the above ethylene copolymer using two extruders equipped with multilayer dies. [Thickness of (I) = 200 μm, (
II) thickness = 40 μm].

Next, the composite film was immersed in 1.1.1-trichloroethane to extract dioctyl phthalate, and then stretched with a tenter at an area stretching ratio of 9 times. below,
By performing sulfonation, washing, hydrodynamic neutralization, etc., most of the ester groups of ethylene-acrylic acid ester are hydrolyzed, and the content of sulfone groups is 3.8 milliequivalents/
A composite hydrophilic membrane having an ultra-thin hydrophilic membrane with a thickness of 4.5 μm was obtained.

The polyethylene microporous membrane has a sulfone group content of 0.20 meq/g and is sulfonated in 1 minute.

The above composite hydrophilic membrane was set in the apparatus shown in Figure 1, and heated to 40°C.
When tangerine juice was concentrated twice under the temperature conditions of 2 [111) 1 g of pressure on the permeate side, the pressure permeation rate of water was as good as 1 kg/hr·1 m2 or more.

In addition, most of the sugar and aroma components remained on the concentration side, proving that the above composite hydrophilic membrane is useful for concentrating natural fruit juice containing aroma preservation components.

Example 24 Polyethylene resin (Belene) (1) prepared in Example 23
) and a mixture (II) containing an ethylene copolymer, and hot pressed at a temperature of 120°C to obtain a composite film having a layer structure of (1)/(n) [ Thickness of (I) = 200 μm.

(II) thickness = 40 μm] was molded.

Hereinafter, extraction of diocpurphthalate, stretching, sulfonation treatment, etc. were carried out in the same manner as in Example 23, and Example 2
A composite hydrophilic membrane almost equivalent to No. 3 was obtained.

As a result of concentrating tangerine juice in the same manner as in Example 23,
Similar to Example 23, the above-mentioned composite wood-philic membrane was a practical membrane for concentrating natural fruit juice containing aroma-preserving ingredients.

Example 25 Anhydrous fine powder silicic acid impregnated with liquid paraffin and powdered high-density polyethylene (density -0,959/cm3゜Ml)
= 1) Resin composition (I) obtained from (liquid paraffin/silicic acid/high density polyethylene-40VoQ%/
10 vol% 150vC'l1%) and ethylene vinyl acetate copolymer (■) (vinyl acetate content -7.8 mol%)
M 1 = 25) was produced from an extruder equipped with a multilayer die into a multilayer film having a layer configuration of (I)/(n)/(1) [thickness of (I) = 150μ, thickness of (II) - 40μ]
Extrusion molded.

Next, the above composite film was subjected to 1. 1,1-) After immersing in dichloroethane to extract liquid paraffin, the film was stretched with a tenter at an area stretching ratio of 6.5 times.

Hereinafter, a composite hydrophilic membrane having an ultrathin hydrophilic membrane with a sulfonic group content of 23 milliequivalents/gram, which is sulfonated, washed, hydrolyzed, neutralized, washed and dried, and in which most of the acetate ester is hydrolyzed. I got it.

This composite hydrophilic membrane has a cation transfer number of 0.93 and an electrical resistance in alkali of 12Ω・Cm2, making it excellent as a cubion exchange membrane. Furthermore, it has the property of immediately getting wet when immersed in water, and its wet state. It was a composite hydrophilic membrane with high tensile strength.

Example 26 Hollow fiber-like high-density polyethylene microporous membrane (outer diameter 1.4
Inner diameter Q, 7 inches, porosity 70%, 1 uniform pore diameter 0.
15 μm) was used in Example 1 as the aqueous dispersion containing the ethylene copolymer (containing 5% by weight of ethanol).
A hollow fiber-like composite film with ultrathin films bonded thereto was obtained by immersing it in the solution and heat-treating it at 100°C for 30 minutes. Next, the above composite film was sulfonated, washed, hydrolyzed, and neutralized, and the sulfonic group content of the ultrathin hydrophilic membrane with a thickness of 3 μm was 28 milliequivalents/gram, and the polyethylene microporous A composite hydrophilic membrane was obtained in which the content of sulfonic groups in the membrane was 0.06 milliJ equivalent/gram. The ethanol water separation performance of the hollow fiber composite hydrophilic membrane described above was good, having almost the same value as that of the flat membrane composite hydrophilic membrane of Example 14.

Example 27 The composite hydrophilic membrane of Example 14 was added to an aqueous HCI solution of about 1
After immersion for an hour and washing with water, the sample was set in the apparatus of step 1, and the same mole number of ethanol and acetic acid was supplied to the feed side under conditions of 60°C and a pressure of 2 t1 mHg on the permeate side to carry out an esterification reaction.

The permeate is mostly water and contains ethyl acetate, ethanol, acetic acid and water -0.7°2.0.
1.9. It was present in an amount of 0.3 mol and was effective as a catalyst for the composite hydrophilic membrane h'-esterification reaction, and was also removed from the anti-+5 liquid in a highly selective manner from the hydraulic force produced by the esterification reaction.

Comparative Example 1 When an attempt was made to sulfonate the ultrathin film containing the ethylene copolymer of Example 22 in the same manner as in Example 22, the film was cut when taken out from the fuming sulfuric acid bath, and the desired ultrathin film was not produced. A thin hydrophilic membrane could not be obtained.

Comparative Example 2 A 40 μm thick film was formed from the resin composition containing the ethylene copolymer of Example 22 in the same manner as in Example 22, and treated in the same manner as in Example 22 to remove the sulfone group. A hydrophilic membrane with an amount of 2.3 milliJ equivalents/gram was obtained.

When the separation performance of the above hydrophilic membrane was measured under the same conditions as in Example 22, the water permeation rate was 509/m2·hr, which was significantly lower than that of the composite hydrophilic membrane of Example 22. .

[Brief explanation of drawings]

FIG. 1 shows an example of an apparatus for carrying out the invention. 1... Vacuum pump 2... Trap 3... Constant temperature chamber 4... Stirrer 5... Supply chamber
6...Transmission chamber 7・°・Membrane 8...
・Perforated plate 9... Supply liquid (water-organic compound mixture) Applicant: Asahi Dow Co., Ltd. Agent Yutaka 1) Yoshio

Claims (1)

[Scope of Claims] (11 Obtained from an ethylene copolymer or a resin composition containing an ethylene copolymer, -0H group and 1000R group (however, TL=H, Cj, ~C6 At least one selected from the group consisting of ions that can form salts with hydrocarbon groups, alkali metals, or other carboxyl groups.
A semi-permeable ultra-thin hydrophilic membrane having hydrophilic groups of seeds and at least 0.2 meq/g of sulfone groups and a polyethylene microporous membrane containing sulfone groups are each fused in at least one layer. Composite hydrophilic membrane. (2) The ethylene copolymer has the following general formula (1), (
II): + cH, -CJ(11-)-(I)1 ■ +CHg CJ(II) ■ 9 [In the formula, R, = I (or -CH81R9' = -Q
C! OR,. -GOOR4 or 10H (However, R, = O, -'-0
, a hydrocarbon group I R4=)1. C, - "Ions that can form salts with hydrocarbon groups, alkali metals or other carboxyl groups of C"] Claim 1, which is an ethylene copolymer whose main component is a unit represented by: The composite hydrophilic membrane according to paragraph 3. (3) The resin composition containing an ethylene copolymer contains at least 15% by weight of the ethylene copolymer and at most 85% by weight of the ethylene copolymer.
The composite hydrophilic membrane according to claim 11 or (2), which contains % by weight of other thermoplastic resin. (4) The ethylene copolymer is an ethylene-vinyl acetate copolymer. Coalescence, saponified ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid copolymer metal salt, ethylene-methyl methacrylate-methacrylic acid copolymer At least one ethylene copolymer selected from the group consisting of metal salts, ethylene-ethyl acrylate copolymers, ethylene-acrylic acid copolymers, and ethylene-acrylic acid copolymer metal salts. Claim No. 1
) Composite hydrophilic membrane described in section 2. (5) Other thermoplastic resins include polyethylene, polypropylene, 1,2-polybutadiene, polybutene-
1. The composite hydrophilic membrane according to claim 3, which is at least one thermoplastic resin selected from the group consisting of 1. (6) Claims (1) to 3 are semipermeable ultrathin hydrophilic membranes containing 1 to 5 milliequivalents/gram of sulfonic groups.
The composite hydrophilic membrane according to any one of item (5). (7) The composite according to claim 11 to (6), wherein the content of sulfonic groups in the microporous polyethylene thread membrane is at least 0.05 mm/g. Hydrophilic membrane. (8) The composite hydrophilic membrane according to any one of claims 1 to 7, wherein the ultra-thin hydrophilic membrane has a thickness of 10 to 0.05 μm. 9) The composite hydrophilic membrane according to any one of claims 11 to (7), wherein the ultra-thin hydrophilic membrane has a thickness of 51 μm or less. θ0 The ultra-thin hydrophilic membrane has a thickness of 1 μm or less The composite hydrophilic membrane according to claim (9). (11) Any one of claims (1) to 00 in which the shape is hollow fiber-like (. is flat). Composite hydrophilic membrane described in section.