JPS637807A - Production of low-pressure highly-permeable semipermeable composite membrane - Google Patents

Abstract

PURPOSE:To obtain a composite membrane which is excellent in high desalting properties and high permeability and suitable for the production of super-pure water by coating the aq. soln. of a multifunctional water-soluble amino compd. on a porous support and crosslinking it by a multifunction crosslinking agent and thereafter treating it by an alkali aq. soln. CONSTITUTION:An aq. soln. incorporating a water-soluble amino compd. having primary or secondary amino groups not less than at least two pieces in a molecule as an essential component is coated on a porous support. The concn. is 0.1-10wt% and furthermore 0.01-2wt% surfactant is preferably added. Then such a soln. that a multifunctional crosslinking agent having groups reacting with amino groups not less than at least two pieces and containing chlorosulfonyl groups not less than one piece is incorporated in a solvent which is immiscible with water and does not dissolve the porous support is coated thereon. The concn. preferably is 0.01-1wt%. The obtained composite membrane is treated by an alkali aq. soln. to hydrolyze nonreacted sulfonyl halide. The concn. is 0.1-10wt% and treatment time preferably is about 0.5-10hr.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semipermeable membrane for selectively permeating and separating components of a liquid mixture. In addition, it is possible to selectively remove or recover pollutants or effective substances contained in wastewater that causes pollution, such as dyeing wastewater and electrocoating paint wastewater. In particular, the present invention relates to a high-performance semipermeable composite membrane that can be used in the production of ultrapure water used in the production of semiconductors, the softening of hard water, and the food field.

(Prior art) Semipermeable membranes conventionally used industrially include asymmetric membranes made from cellulose acetate, such as those described in US Patent Box 3.1.
There are lob-type membranes described in Patent No. 33.132 and Patent No. 3.133.137. However, this membrane has problems with hydrolysis resistance, microbial resistance, chemical resistance, etc., and in particular, when trying to improve permeability, it is not possible to manufacture a membrane that has both pressure resistance and durability. However, it has not yet been put to practical use in a wide range of applications. Research into new materials that eliminate the drawbacks of these rose acetate asymmetric membranes is being actively conducted mainly in the United States and Japan, but aromatic polyamides, polyamide hydrazides (U.S. Patent Box 3)
．． 567, 632 specification), Polyamide Acid Special Publication 1977
0-121168), cross-linked polyamide acid (Japanese Patent Publication No. 152879/1987), polyimidazopyrrolone,
Although materials such as polybenzimidazole, polybenzimidacylon, and polyarylene oxide that improve the disadvantages of these materials have been obtained, they are inferior to cellulose acetate membranes in terms of selective separation or permeability.

- On the other hand, a composite membrane has been developed in which a lobe-type semipermeable membrane is formed by coating a porous support membrane with an active layer having substantially membrane performance as a semipermeable membrane. In composite membranes, it becomes possible to select the most suitable materials for the active layer and porous support membrane for each application, increasing the degree of freedom in membrane manufacturing technology. It also has the advantage of being able to be stored in a dry state, unlike a lobe-type membrane, which must be constantly stored in a wet state.

There are two types of these composite membranes: one in which the active layer is coated on a porous support via an intermediate layer, and one in which the active layer is coated directly on the porous support membrane. Specific examples of the former are JP-A-49-133282 and JP-A-55-3.
Publication No. 8164, PB Report 80-182090, Japanese Patent Publication No. 59-27202, Japanese Patent Publication No. 56-40403
Although this type of membrane is said to be easier to form during industrial production than the latter type of membrane, although it has been actively researched, it is still difficult to process water when subjected to reverse osmosis treatment under low pressure. Permeability is low and satisfactory membrane performance is not obtained.

On the other hand, market needs for highly permeable semipermeable membranes require membranes that can produce a high amount of water even though they have a low desalination rate, and such technology is in demand.

[Problem that the invention seeks to solve]

As a result of our earnest efforts to obtain a semipermeable composite membrane that has high permeability and can diversify desalination performance even under low-pressure operation, we discovered that a polyfunctional amino membrane having two or more amino groups It was discovered that by treating a composite semipermeable membrane produced by reacting a polyfunctional acid chloride containing two or more acyl halides, sulfonyl halides, etc. with an alkaline aqueous solution, the amount of water produced can be significantly improved. This is what led to the present invention.

[Means for solving problems]

In order to achieve the above object, the present invention consists of the following configuration.

``A method for producing a highly permeable semipermeable composite membrane, characterized in that a semipermeable composite membrane is obtained by the following production steps A, B, and C.

A. A step of coating a porous support with an aqueous solution containing as a main component a water-soluble amino compound having at least two 1 or 2@amino groups in the molecule.

B, at least two groups that are immiscible with water and that react with amino groups dissolved in a solvent that does not dissolve the porous support;
A semipermeable composite membrane is formed by applying a solution containing a polyfunctional amino having at least one chlorosulfonyl group and carrying out a crosslinking reaction.

C8 A step of treating the semipermeable composite membrane with an alkaline aqueous solution.

In the present invention, the water-soluble amino compounds are specifically, for example, amino-modified polyiodohydrin, amino-modified polychlorohydrin, polyethyleneimine, m-phenylene diamino, p-phenylene diamino, 1,3.5-tri- Aminobenzene, 1,2.4-triaminobenzene, 2,
Examples include 5-dimedylbiperazine and piperazine.

The highly permeable semipermeable composite membrane of the present invention is obtained by coating at least one side of a porous support with the water-soluble amino compound aqueous solution, and then evaporating some or all of the water by air drying and/or heat treatment. , by applying a solution mainly consisting of a polyfunctional acid chloride dissolved in a solvent that is immiscible with water and does not dissolve the porous support, allowing a crosslinking reaction to occur, and then drying. It will be done.

The component concentration of the composition for obtaining the highly permeable semipermeable composite membrane of the present invention is from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight, and furthermore, the water-soluble amino compound is 0.5 to 5% by weight. It is effective to add a surfactant to the surface of the porous support to improve wettability and ensure uniform adhesion, and anionic surfactants are particularly preferred. The surfactant is generally used in an amount of about 0.01 to 2% by weight.

In the present invention, a porous support is a layer that does not substantially have separation performance, and is used to give strength to a thin film that does have separation performance, and is a layer that has uniform fine pores or one side. A support having a structure having fine pores that gradually become larger from one side to the other side, and the size of the fine pores on one side is about 100 to 1000 pores, is preferable.

The above porous support is a Millipore filter (VSMP)
You can choose from a variety of commercially available materials, such as tJKlo and Toyo Filter Paper (tJKlo);
968). The material is usually a homopolymer or a blend of polysulfone, cellulose acetate, cellulose nitrate, and polyvinyl chloride. By casting the mold to a thickness of 100 Å and wet coagulating it in an aqueous solution containing 0.5% by weight of sodium dodecyl sulfate and 2% by weight of DMF, the majority of the surface has micropores with a diameter of several hundred angstroms or less. A sexual support is obtained.

In the present invention, the solvent that is immiscible with water and does not dissolve the porous support can be selected depending on the material of the porous support. For example, when polysulfone is used as the porous support, aliphatic hydrocarbons and limited halogenated hydrocarbons can be used, such as n-hexane, carbon tetrachloride, trichlorotrifluoroethane, etc. Particularly preferred is trichlorotrifluoroethane, considering the above-mentioned toxicity and safety.

The concentration of the polyfunctional crosslinking agent when dissolved is 0.01 to 1.
0% by weight, preferably in the range of 0.05 to 0.5% by weight. It is also effective to add hydrochloric acid scavengers such as alkaline gold salts, such as sodium phosphate and sodium hydroxide, to promote the reaction between amino and polyfunctional crosslinking agents.
Furthermore, the combined use of a phase transfer catalyst or an acylation catalyst may also bring about good effects.

In the present invention, the polyfunctional crosslinking agent is one having at least two or more groups that react with amino groups, and specifically includes the following.

In the above-mentioned aromatic polyfunctional crosslinking agent, A is essential,
Although it is preferable to use A alone, a combination of A+B or A+C may also be used.

When forming an ultra-thin film using interfacial polycondensation using these multifunctional crosslinking agent solutions, the amino group in the amino compound represented by m-phenylene diamino and the amino group represented by 5-chlorosulfonylisophthalic acid chloride are combined. The reaction of the sulfonyl halide is slow, and it is expected that the acyl halide will react preferentially, leaving some unreacted sulfonyl halide in the ultra-thin film. These sulfonyl halides can be easily hydrolyzed in an alkaline aqueous solution, forming an ultra-thin film of sulfone! As a result, it is expected that the amount of water produced will be dramatically improved.

Conversely, even if an amino compound containing a sulfone rli group is used, high water formation can be expected. For example, 4,4-diaminodiphenyl ether-2,2-disulfonic acid, 3
,3-dimethyl-4,4-diaminodiphenyl-6,6
-disulfonic acid and the like.

The alkaline hydrolysis according to the present invention includes a method of immersing a composite semipermeable membrane in an alkaline aqueous solution.

As the alkali, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium bicarbonate, and potassium bicarbonate may be used alone or in a mixture of two or more.
Particularly preferred is sodium hydroxide. The immersion temperature is usually room temperature, the concentration is 0.1 to 10% by weight, and the immersion time is several minutes to several hours, preferably 0.5%.
~10 hours is good.

〔Example〕

The invention will be explained in more detail by the following examples. In the examples, the rejection rate of common salt as selective separation performance was determined by conventional means by measuring electrical conductivity. In addition, as permeation performance, water permeation rate was determined by the amount of water permeation per unit area and unit time.

Reference example: Taffeta made of polyester fibers with large serrations of 3Qcm in length and +20cm in width (multifilament yarn of 150 denier in warp and weft, weaving density 90 pieces/inch in length, 67 pieces/inch in width, thickness 160μ) was fixed on a glass plate, and 15% of polysulfone (trade name: Udel P-3500, manufactured by Union Carbide Co., Ltd.) was placed on top of it.
A fiber-reinforced polysulfone support membrane (hereinafter abbreviated as FR-PS support membrane) was formed by casting a dimethylformamide (DMF) solution to a thickness of 200μ at room temperature (20°C), immediately immersing it in pure water, and leaving it for 5 minutes. The FR-PS support film thus obtained (thickness 210~
The pure water permeability coefficient of 215 μ) is 9/-1 temperature 2 for pressure 1
0.005-0.01Q/c4- measured at 5°C
It was sec-atm.

Example 1 The FR-PS support film obtained in Reference Example was immersed in an aqueous solution containing m-phenylenediamino 2fflffi%/v for 1 minute. Next, this support film was taken out and air-dried for 1 minute at room temperature, and then a solution containing 0.06% by weight of a mixture of trinasic acid chloride and 5-chlorosulfonylisophthalic acid chloride (weight ratio 9:1) was applied to Freon. Make it react. It was then air-dried. Then N/100-
It was immersed in NaOH aqueous solution for 1 hour. In this way 1q
The composite membrane was heated at a pressure of 15kq10yf and raw water at 0.15%.
As a result of a reverse osmosis test with an aqueous NaCl2 solution at 25°C, the salt removal rate was 97.5% after 15 hours, and the water permeation ff11.
It showed a performance of 5 Trll/2·day.

Example 2 A mixture of trinasic acid chloride and 5-chlorosulfonylisophthalic acid chloride (weight ratio 1:1) was used at 0.5 weight percent as a crosslinking agent solution, and 1 weight percent solution of piperazine was used instead of m-phenylene diamino. Film formation and reverse osmosis test were conducted in the same manner as in Example 1 except that . As a result, the salt removal rate was 50.9%, and the water permeation was ω4.4Tn! /Tn2
・Showed the performance of the day.

Example 3 A mixture of trinasic acid chloride and 5-chlorosulfonylisophthalic acid chloride (weight ratio 9:1) was used at 1.0% by weight as the crosslinking agent solution, and a 1% by weight solution of polyethyleneimine was used as the amino compound. A film was formed in the same manner as in Example 1. Reverse osmosis test requires operating pressure of 40kq/ar
t, raw water 0.5% Na (4) Result of conducting under aqueous solution conditions, 15 hours salt rate 97.1%, water permeation m2.2m
+”/mzs day performance.

Example 4 A mixture of trimesic acid chloride, isophthalic acid chloride, and 5-chlorosulfonylisophthalic acid chloride (weight ratio 2:1) was used as a crosslinking agent solution at 0.06
Using weight%, m-phenylenediamino and 1,3,5-triaminobenzene (weight ratio 3:1) were used as amino compounds.
) was formed into a film in the same manner as in Example 1 except that a 2% by weight solution was used.
A reverse osmosis test was performed. As a result, desalination rate was 99.5%.
It showed performance of water permeation amount of 1.1TIN3/Tr12·day.

Comparative Example 1 In contrast to Example 1, 5-chlorosulfonylisophthalic acid chloride as a crosslinking agent component was changed to O wt %, and the others were as in Example 1.
Film formation and reverse osmosis tests were conducted in the same manner as above. As a result, the desalination rate was 98. O%, water permeation amount 1゜0Tn! /Tr12·day.

Comparative Example 2 With respect to Example 2, 5-chlorosulfonyl chloride as a crosslinking agent component was changed to 0% by weight, and membrane formation and reverse osmosis tests 1 to 1 were conducted in the same manner as in Example 2, except that the content was 0% by weight. As a result, the desalination rate was 62.2.
%, water permeation m 1 , and performance of 3 m”/m 2 ·day.

〔Effect of the invention〕

The composite membrane of the present invention is for permselective separation of liquid mixtures, and in particular can be used for the production of kansui and ultrapure water used in the production of semiconductors.
At the same time, it has become possible to provide a membrane with high salinity and high permeability, which was previously difficult to achieve.

Claims (5)

[Claims] (1) A method for producing a highly permeable semipermeable composite membrane, which comprises obtaining a semipermeable composite membrane by the following production steps A, B, and C. A. A step of coating a porous support with an aqueous solution containing as a main component a water-soluble amino compound having at least two primary or secondary amino groups in the molecule. B, at least two groups that are immiscible with water and that react with amino groups dissolved in a solvent that does not dissolve the porous support;
A step of applying a solution containing a polyfunctional crosslinking agent having one or more chlorosulfonyl groups and causing a crosslinking reaction to obtain a semipermeable composite membrane. C. Treating the semipermeable composite membrane with an alkaline aqueous solution. (2) The highly permeable semipermeable composite according to claim (1), wherein the multifunctional crosslinking agent has two or more functional groups consisting of an acyl halide and a sulfonyl halide in one molecule. Membrane manufacturing method. (3) The highly permeable semipermeable composite according to claim (1), wherein the multifunctional crosslinking agent has two or more functional groups consisting of an isocyanate group and a sulfonyl halide in one molecule. Membrane manufacturing method. (4) The polyfunctional crosslinking agent has one or more aromatic rings and two or more functional groups consisting of sulfonyl halide in one molecule, A method for producing a highly permeable semipermeable composite membrane. (5) The alkali is sodium hydroxide, potassium hydroxide,
The method for producing a highly permeable semipermeable composite membrane according to claim (1), wherein the compound is one or more compounds selected from ammonium hydroxide, sodium bicarbonate, and potassium bicarbonate.