JPS645927B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a composite semipermeable membrane, and more particularly to a composite semipermeable membrane that has excellent semipermeable membrane performance and has excellent chemical resistance, stain resistance, heat resistance, and oxidation resistance. It is something. BACKGROUND ART In recent years, membranes have been used in many cases for separation, and various proposals have been made. Among them, reverse osmosis membranes have been used for seawater desalination, concentration of valuables in the food industry, 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, heat resistance, compaction resistance, and microbial decomposition resistance were In order to solve this problem, membranes made of synthetic polymers have begun to be considered. 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 are excellent in these properties but generally do not have sufficient oxidation resistance. DISCLOSURE OF THE INVENTION In view of the above circumstances, the present inventor conducted intensive studies to obtain a semipermeable membrane that completely satisfies the above performance and has excellent separation performance. The present inventors have discovered that a polycondensation reaction can occur in the presence of a polycondensate to form a film that does not have the above-mentioned drawbacks of the conventional film, and has completed the present invention. That is, the present invention provides a compound represented by the following formula on a microporous membrane. [However, in the formula, m is 2 or 3, and Ar has 6 to 6 carbon atoms.
Represents 15 aromatic hydrocarbon residues. ] is a composite semipermeable membrane obtained by heating and polycondensing the following in the presence 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.

【formula】

[Formula] (X=O, SO ₂ , −CH ₂ −,

【formula】)

【formula】

【formula】

[Formula] These are compounds known per se, generally obtained by the Friedel-Crafts reaction of the following formula. [Ar and m are the same as defined above] Inorganic acids such as sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid are used as acid catalysts used when performing polycondensation reactions by heating these fluorine-containing compounds. Sulfuric acid is most preferred. The acid catalyst is added in an amount of 5 to 200% by weight, preferably 10 to 100% by weight, based on 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: glyoxal, glutaraldehyde, benzaldehyde, furfural, etc. (2) Polyols: glycerin, ethylene glycol, diethylene glycol, inositol,
Sorbitol etc. These are 10 to 10% of the above fluorine-containing compounds.
It is preferable to copolymerize 200 parts by weight, preferably 20 to 100 parts by weight. When carrying out the above copolymerization,
The above-mentioned fluorine-containing compound is applied to the microporous membrane in a solution state. Such solvents include lower alcohols,
Ketones, esters, ethers, N-methylpyrrolidone, etc. can be used, but 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.
It is. As a microporous membrane for applying this solution,
Heat resistant over 100℃, surface pore diameter 100~2000
Å, preferably 200-1000Å, water permeability coefficient 1-100
×10 ^-3 , preferably 5 to 50 × 10 ^-3 g/cm ²・sec・
As long as it satisfies the ATM conditions, it does not matter whether it is an organic polymer or an inorganic polymer, but those with an asymmetric structure are preferable. The back side of the porous membrane can also be reinforced with a woven or nonwoven fabric. Examples of such porous membrane materials include polysulfone, polyethersulfone, chlorinated polyvinyl chloride, regenerated cellulose, polytetrafluoroethylene, polyvinylidene fluoride, and polyamide. 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 heat-treated to cause a polycondensation reaction. The heating conditions are 100 to 200°C, preferably 130 to 180°C, and 10 to 200°C.
It is desirable to heat treat for 60 minutes, preferably 20-40 minutes. This heat treatment is preferably carried out in stages, for example at 100-130°C for 10 minutes and then at 140-130°C.
Preferably, the heating is carried out at 180°C for 10 to 30 minutes. By this heat treatment, the dehydration polycondensation reaction of the fluorine-containing compound proceeds to provide a semipermeable membrane. The semipermeable membrane thus obtained is useful not only as a water treatment separation membrane with excellent chemical resistance, heat resistance, oxidation resistance, and pollution resistance, but also as a gas separation membrane and an organic liquid mixture separation membrane. . Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Polysulfone microporous membrane (surface pore diameter 200-1500 Å,
A material with a water permeability coefficient of 3×10 ^-2 g/cm ²・sec・atm, reinforced with polyethylene terephthalate nonwoven fabric on the back side) was immersed in a 1:1 (volume ratio) mixture of ethanol and water for 10 minutes. The water in the porous membrane was replaced with a solvent. After that, fluorine-containing compound 3 represented by the following formula
g (meta-substituted product: para-substituted product = 95:5 molar ratio)
After dissolving in 30 g of ethanol, 70 g of water and 2 g of sulfuric acid were added to ensure sufficient dissolution. After the polysulfone microporous membrane was immersed in the solution for 10 minutes, the surface of the membrane was covered with a polyethylene sheet, and a roll press was applied over the membrane to remove excess solution adhering to the membrane surface. After that, the membrane was heated at 100℃ for 10 minutes, and
A composite membrane was obtained by heat treatment at 150°C for 30 minutes. Use this as a stock solution of 0.5% sucrose,
42.5Kg/cm ² , reverse osmosis test was conducted at 25℃.
It exhibited semi-permeability with an exclusion rate of 98% and water permeability of 49.2/m ² hr. The composite membrane was treated with the following 100ppm chlorous acid aqueous solution with pH 5.5.
Although it was immersed in the liquid for 3 days, no change in performance was observed. 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.

【table】

Claims (1)

[Claims] 1. A compound represented by the following formula on a microporous membrane [However, in the formula, m is 2 or 3, and Ar has 6 to 6 carbon atoms.
Represents 15 aromatic hydrocarbon residues. ] A composite semipermeable membrane obtained by heating and polycondensing the following in the presence of an acidic catalyst and, if necessary, a copolycondensable compound.