JPS59179104A - Novel composite semipermeable membrane - Google Patents

Abstract

PURPOSE:To obtain a composite semipermeable membrane having high resistance to chemicals, stains, heat and oxidation by subjecting to a condensation polymerization reaction under heating of a specified aromatic hydroxy compd. contg. fluorine on a microporous membrane in the presence of an acidic catalyst. CONSTITUTION:The composite semipermeable membrane is prepared by condensation polymerization under heating on the microporous membrane of a compd. as represented in the formula in the presence of an acidic catalyst or in the coexistance of a compd. having a condensation polymerization property when needed. The 5-200wt% inorganic acid, which is used for condensation polymerization as an acidic catalyst, is added to 100wt% above-mentioned fluorine compd. The condensation copolymerization of 10-200pts.wt. other monomer having a condensation property with 100pts.wt. above-mentioned fluorine compd. can also be possible. Aldehydes and polyols are exemplified as the monomer. The product is coated on the microporous membrane in a soln. state. The porous membrane, coated or impregnated with the fluorine-contg. compd. soln. and the acidic catalyst, is heated to form the semipermeable membrane.

Description

Detailed Description of the Invention Technical Field The present invention relates to a composite semipermeable membrane, and more specifically, it has excellent semipermeable membrane performance, chemical resistance, stain resistance,
This invention relates to a composite semipermeable membrane with excellent heat resistance and oxidation resistance.

BACKGROUND ART In recent years, membranes have been used for separation in an extremely large number of cases, and various proposals have been made. Among them, reverse osmosis membranes have been used for seawater desalination, concentration of valuables in the food industry, and factory wastewater treatment, etc., but depending on the usage environment, they have different properties such as chemical resistance, oxidation resistance, heat resistance, and pollution resistance. The emergence of a semipermeable membrane with even higher performance has been desired from the viewpoint of performance.

Cellulose acetate-based asymmetric membranes were first developed as reverse osmosis membranes, paving the way for the practical application of membrane separation technology, but this membrane's chemical resistance and heat resistance were insufficient.

Membranes made of synthetic polymers have begun to be investigated in order to solve the problems of low compaction resistance and microbial decomposition resistance. Such membrane materials include asymmetric membranes made of polyamide, polyimide, and polybenzimidazolone, composite membranes made by crosslinking polyamine with acid chloride on a microporous membrane, and polycondensation membranes made by polycondensing furfuryl alcohol with an acid catalyst. Composite membranes made of

Among these synthetic membranes, asymmetric membranes generally do not have sufficient compaction resistance or heat resistance, while composite membranes have these properties. However, the oxidation resistance was generally not sufficient.

DISCLOSURE OF THE INVENTION In view of the above circumstances, the inventors of the present invention have conducted extensive research in order to obtain a semipermeable membrane that completely satisfies the above performance and has excellent separation performance, and has developed a specific fluorine-containing aromatic hydroxy compound. It was discovered that a polycondensation reaction can be carried out in the presence of an acid catalyst to form a film that does not have the above-mentioned drawbacks of conventional methods. That is, the present invention provides a compound CF represented by the following formula on a microporous membrane.

1 Ar(-c-OH)rfl death C.F.

[However, in formula 2, m is 2 or 3, and Ar has 6 to 1 carbon atoms.
5 represents an aromatic hydrocarbon residue. ] in the coexistence of an acidic catalyst and, if necessary, a copolycondensable compound.

Examples of the fluorine-containing aromatic compound used in the present invention include the following.

C! These are compounds known per se, which are generally obtained by the Friedel-Kraf reaction of the following formula.

FI CAr and m are the same as defined above] Inorganic acids such as sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid are used as the acid catalyst used when performing the polycondensation reaction by heating these fluorine-containing compounds. Among these, sulfuric acid is also preferred. The acid catalyst is added in an amount of 5 to 200, preferably 10 to 100, by weight relative to the fluorine-containing compound.

The above-mentioned fluorine-containing compound can also be copolycondensed with other polycondensable monomers. Examples of such copolycondensation components include aldehydes and polyols, and specific examples include the following.

(1) Aldehydes V: glyoxal, glutaraldehyde, benodufuldehyde, furfural, etc. (2) Polyols: glycerin, ethylene glycol, diethylene glycol, inositol, sorbitol, etc. These are 10 to 200 parts by weight based on the above fluorine-containing compound, Preferably 1-( is preferably copolymerized with 20 to 100 base portions. When carrying out the above copolymerization, the above-mentioned fluorine-containing compound is applied to the microporous membrane in a solution state. Such a solvent Examples include lower alcohols, ketones, esters, and ethers.

Although N-methyl biglidone and the like can be used, lower alcohols are particularly preferred. The solution concentration of the above fluorine-containing compound is 0.5 to 10% by weight, preferably 1 to 7% by weight.
Weight%. The microporous membrane to which this solution is applied is 1
Has heat resistance of 00℃ or higher, surface pore diameter 100~200O
A, preferably 200-100OX, water passage coefficient 1-1
00 x 10-”, preferably 5 to s o x t o-
As long as it satisfies the conditions of ``f fil・sec-htm'', organic poly-7- or inorganic polymers may be used, but those with an asymmetric structure are preferable. It is also possible to reinforce with non-woven fabric.

Examples of such porous membrane materials include polysulfone, polyethersulfone, chlorinated polyvinyl chloride, recycled cell p-sulfate, polytetrafluoropoethylene, polyvinylidene fluoride, polyamide, and the like.

Among these, particularly preferred are polysulfone and polyethersulfone.

After coating or impregnating the above-mentioned fluorine-containing compound solution and acid catalyst on the above-mentioned porous membrane, it can be drained if necessary, and then subjected to a heat treatment to carry out a polycondensation reaction. The heating conditions [100 to 200°C,
The heat treatment is preferably carried out at 130 to 180°C for 10 to 60 minutes, preferably 20 to 40 minutes. It is preferable to carry out this heat treatment in stages.1. <, for example 100~
] At 30℃ for 10 minutes, then at 140-180℃
It is preferable to carry out for 0 to 30 minutes. Through this heat treatment,
The dehydration polycondensation reaction of the fluorine-containing compound proceeds to provide a semipermeable membrane. The semipermeable membrane thus obtained can be used not only as a separation membrane for water treatment, but also as a gas separation membrane, an organic liquid mixture separation membrane, and has excellent chemical resistance, heat resistance, oxidation resistance, and pollution resistance. is also useful.

Hereinafter, the present invention will be described in more detail with reference to Examples. <Explain.

Example 1 Polysulfone microporous membrane (surface pore diameter 200-1500X,
Water permeability coefficient 3
1 cI in a 1=1 (volume ratio) mixture of ethanol and water
The microporous membrane was immersed for 0 minutes to replace the water in the microporous membrane with the solvent.

Thereafter, a fluorine-containing compound represented by the following formula (meta-substituted product: para-substituted product, = 95:5 molar ratio) was dissolved in 30% of ethanol and 70% of water was dissolved. and sulfuric acid 22 were added to sufficiently dissolve the mixture.

After immersing the polysulfone microporous membrane in the solution for 1 minute, the surface of the membrane was covered with a polyethylene sheet, and a plupress was applied over it to remove excess adhesion to the membrane surface.
The Tita solution was removed.

Thereafter, the film was heated at 100°C for 10 minutes and then for 15 minutes.
A composite membrane was obtained by heat treatment at 0° C. for 30 minutes. Use this as a stock solution of o, sq6 sucrose, 42,
A reverse osmosis test was conducted at 5 Ky/cfI and 2 s°C, and the rejection rate was 98 cm, and the water permeability was 49.2 t/1-h.
It showed a semipermeability of r.

The composite membrane was soaked in a 1100 ppp hypochlorous acid aqueous solution with a pH of 5.5.
No change in performance was observed after 3 days of immersion.

Examples 2 to 4 Equimolar amounts of the following copolycondensation compounds were added to the fluorine-containing compound used in Example 1, and composite membranes were obtained in the same manner. Their membrane performance was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Procedural amendment (formality) July 7th, 1988 Commissioner of the Patent Office 1. Display of incident Patent Application No. 58-53738 No. 2, Title of the invention Novel composite semipermeable membrane 3 Person making the amendment Relationship to the case Patent applicant 1-11 Minamihonmachi, Higashi-ku, Osaka (30 Teijin Ltd. Representative Tomoo Sue Toku

Claims (1)

[Claims] Compound CF represented by the following formula on a microporous membrane. 1.A r (C-OH)m 1 CF, Pa. [However, in the formula, m is 2 or 3, and Ar has 6 to 15 carbon atoms.
represents an aromatic hydrocarbon residue. ] in the coexistence of an acidic catalyst and, if necessary, a copolycondensable compound.