JPS63178805A - Production of semipermeable compound film - Google Patents

Abstract

PURPOSE:To produce semipermeable compound film having improved salt- excluding rate by allowing hydrocarbon solns. having different concns. of a polyfunctional reagent to contact with a layer of an aq. soln. of an amine compd. coated on a porous supporting body while carrying out the contact in two stages. CONSTITUTION:For example, after coating the surface of a fiberreinforced polysulfone supporting body with aq. soln. of a compd. having >=2 reactive amino groups such as metaphenylenediamine, by dipping the supporting body in the soln., a hydrocarbon soln. of a polyfunctioanl reagent such as trimesic chloride in the soln. of 1,1,2-trichloro-1,2,2-trifluoroethane is coated on the supporting body (first stage treatment). Further, a hydrocabon soln. of the polyfunctional reagent diluted to lower concn. than in the first stage treatment is coated on the surface of the film, then the film is dried, thusobtg. a compound film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a semipermeable composite membrane suitable for ultraviolet, r=passage, reverse osmosis, and the like.

[Prior Art] Conventionally, a composite membrane has been developed as a semipermeable membrane of a different type from a lobe type, in which a porous support is coated with an active layer that substantially exhibits membrane performance. In composite membranes, it becomes possible to select the optimal materials for the active layer and porous support 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 the lobe type, which must be stored in a wet state at all times.

Among such composite membranes, composite membranes in which the active layer is made of polyamide or polyurea have high membrane performance, particularly water permeability, and have therefore become the mainstream in the development of semipermeable composite membranes. The method for manufacturing the composite membrane is described in US Pat. No. 3,191,815, US Pat. No. 3,744,642, and US Pat.
440, 4.277, 344, and Japanese Patent Publication No. 56-500062, a step of coating a porous support with an aqueous solution containing a compound having an amino group and There is a method that consists of contacting a hydrocarbon-based solution containing a functional reaction reagent with the aqueous phase described above.

[Problems to be Solved by the Invention] However, the membrane performance of these composite membranes was not fully satisfactory.

The present inventors have conducted studies on improving the performance of such semipermeable composite membranes, and particularly aimed to provide a method for producing a semipermeable composite membrane with improved salt rejection.

[Means for solving problems] In order to achieve the above object, the present invention consists of the following configuration.

"In a method for obtaining semipermeable composite membranes by interfacial polycondensation,
After coating the porous support with an aqueous solution containing a compound having two or more reactive amino groups, ◎ a hydrocarbon solution containing a polyfunctional reaction reagent is brought into contact with the aqueous solution layer of (a) ( (1) production of a semipermeable composite membrane characterized by: (1) further contacting its surface with a hydrocarbon solution containing a diluted polyfunctional reaction reagent (2nd stage treatment); Method. The porous support used in the present invention is a support having micropores of several tens to several thousand angstroms on its surface, and is polysulfone or polyvinyl chloride.

Known materials made of chlorinated vinyl chloride, polycarbonate, polyacrylonitrile, cellulose ester, etc. are included. Among these, porous polysulfone supports are particularly effective in the present invention.

Porous polysulfone membranes are produced by making polysulfone into a solution in an aprotic polar solvent such as dimethylformamide, casting it onto a woven or nonwoven fabric made of polyester fibers, and then coagulating (gelling) the solution in a medium consisting essentially of water. This is done by so-called wet film forming, etc. The porous polysulfone thus obtained has micropores on the surface having a size of several tens to several hundred angstroms and increasing in size from the front surface to the back surface.

In the present invention, a compound having two or more reactive amino groups (hereinafter abbreviated as an amino compound) refers to a compound that reacts with a polyfunctional acid chloride or isocyanate compound to form a polymer having an amide bond or a urea bond. For example, meta-phenylene diamino, para-phenylene diamino, 3,5-diaminobenzoic acid, 2.5
-, 5-diaminobenzenesulfonic acid, metaxylidene diamino, baraxylidene diamino, 4,4°-diaminobenzanilide, piperazine, aminomethylpiperidine, ethylene diamino, 1,3,5-triaminobenzene, etc. .

The concentration of the amino compound in the amino compound aqueous solution is 0.
1 to 10% by weight, preferably 0.5 to 5.0% by weight. Further, the amino compound aqueous solution may contain a surfactant, an organic solvent, etc. as long as they do not interfere with the reaction between the amino compound and the polyfunctional reaction reagent.

The aqueous solution of the amino compound may be coated on the surface of the porous support as long as the aqueous solution is coated uniformly and continuously on the surface.
The coating may be carried out by any known coating method, such as coating the surface of a porous support with the aqueous solution or immersing the porous support in the aqueous solution.

The polyfunctional reaction reagent used in the first stage treatment of the present invention may be any reagent that can form a polyamide or polyurea by reacting with the amino compound, such as trimesic acid halide, benzophenonetetracarboxylic acid halide, and trimesic acid halide. Mellitic acid halide, pyrometic acid halide, isophthalic acid halide, terephthalic acid halide, naphthalenedicarboxylic acid halide, diphenyldicarboxylic acid halide, pyridinedicarboxylic acid halide, benzenedisulfonic acid halide, benzenedisulfonic acid halide,
Examples include tolylene diisocyanate, bis(P-isocyanate phenyl)methane, etc.; however, considering solubility in membrane forming solvents and performance of composite reverse osmosis membranes, trimesic acid chloride, isophthalic acid chloride, terephthalic acid chloride, and mixtures thereof are recommended. Preferred is trimesic acid chloride, particularly from the viewpoint of durability and introduction of a crosslinked structure.

The solvent for the polyfunctional reaction reagent needs to be inert to the amino compound and the polyfunctional reaction reagent, and insoluble or sparingly soluble in water. Furthermore, the solvent is preferably inert to the porous support. Typical examples of such solvents include liquid hydrocarbons and halogenated hydrocarbons, such as pentane, hexane, heptane, 1,
There is 1,2-trichloro-L2,2-trifluoroethane. The concentration of the polyfunctional reaction reagent is preferably from 0.01 to
It is 10% by weight, more preferably 0.02 to 2% by weight.

The method for contacting the polyfunctional reaction reagent with the aqueous amino compound solution phase may be carried out in the same manner as the method for coating the porous support with the aqueous amino compound solution.

In the present invention, the diluted polyfunctional reagent that is brought into contact with the surface of the membrane formed by the reaction between the amino compound and the polyfunctional reagent (i.e., the second stage treatment) reacts with the amino compound to form a polyamide or a polyfunctional reagent. Any material that can form urea may be used, but trimesic acid chloride, isophthalic acid chloride, terephthalic acid chloride, and mixtures thereof are preferred in view of solubility in the membrane forming solvent and performance of the composite reverse osmosis membrane. From the viewpoint of properties, trimesic acid chloride is preferred from the viewpoint of introducing a crosslinked structure.

Further, the concentration of the polyfunctional reaction reagent in the second stage treatment is preferably in the range of 1/10 or more and 8/10 or less of the concentration in the first stage treatment. This is to further improve the salt rejection rate. In addition, the solvent for the polyfunctional reaction reagent that is brought into contact with the surface of the film formed by the reaction between the amino compound and the polyfunctional reagent is inert to the amino compound and the polyfunctional reaction reagent, and is inert to water. It only needs to be insoluble, and specifically includes hydrocarbons and alcohols. Typical examples of the solvent include pentane, hexane,
Examples include heptane, 1,1.2-trichloro-1,2,2-trifluoroethane, methyl alcohol, ethyl alcohol, normal propyl alcohol, and isopropyl alcohol, and a mixture of these may be used. Furthermore, ketones such as acetone and methyl ketone, and ethers such as dioxane, tetrahydrolane and diethyl ether, which adversely affect the membrane and porous support when used alone, can also be used when mixed with the above-mentioned solvents.

Methods of contacting the solvent with the membrane include coating the surface of the membrane with the solvent, immersing the membrane in the solvent, spraying the solvent onto the surface of the membrane, etc. The solvent comes into contact with the entire surface of the membrane. Any method is acceptable as long as it can be done. The temperature of the solvent is not particularly limited, but is generally 10
'C to 10°C lower than the boiling point of the solvent. The contact time of the solvent with the membrane varies depending on the temperature of the solvent, but is preferably about 10 seconds to 10 minutes.

[Examples] The present invention will be specifically explained below using Examples, but the present invention is not limited thereto.

Example 1 Taffeta made of polyester fibers with a length of 30 cm and a width of 20 cm (multifilament yarn of 150 denier in both warp and weft, weaving density of 90 pieces/inch in length,
6 horizontal lines/inch, thickness 16-〇-Oμ) was fixed on a glass plate, and polysulfone (
A 15% by weight solution of Udel 3500 (manufactured by Union Carboid) in dimethylformamide (DMF) was added to
A fiber-reinforced polysulfone support (hereinafter abbreviated as FR-PS support) was prepared by casting at room temperature (20'C) to a thickness of 0 μm, immediately immersing it in pure water, and leaving it for 5 minutes. The FR-PS support thus obtained (
The pure water permeability coefficient of 210 to 215μ thick is 5 to 1 pressure.
/cnf, 0.005-0.0 measured at a temperature of 25°C
1C1/ri-sec-atm.

FR-PS support with 2% by weight of metaphenylenediamino
It was immersed in an aqueous solution for 2 minutes. After removing the excess aqueous solution from the surface of the FR-PS support, a solution of 0.1% by weight of trimesic acid chloride dissolved in 1°1,2-trichloro-1,2,2-trifluoroethane was added until the surface was completely covered. It was coated so that it was wet and left to stand for 1 minute. Next, after turning the membrane vertically and removing the excess solution by draining, the membrane surface was further coated with 0.05% by weight of trimesic acid chloride in 1.1.2-trichloro-1,2,2-trifluoroethane. The surface was coated with the dissolved solution so that the surface was completely wetted, and the film was allowed to stand for 30 seconds.The film was then held vertically to drain the liquid, and then dried at room temperature. The composite membrane thus obtained was heated to 56% using 3.5% synthetic seawater with a reverse osmotic pressure of 25 ka/-.
kg/CITf, reverse osmosis test under the conditions of 25°C, rejection rate 99.4%, water permeation rate 0°71-/Tr1
A performance of 2 days was obtained.

Comparative Example 1 In Example 1, 1,1.2-trichloro-1,2,
The same procedure was performed except that coating with a solution of 0.05% by weight of trimethoyl chloride dissolved in 2-trifluoroethane was not performed, and the results showed a rejection rate of 99.0% and a water permeation rate of 0.7511'/Tn2·day. was gotten.

Examples 2 to 5, Comparative Examples 2 to 3 In Example 1 and Comparative Example 1, the compounds shown in Table 1 were used instead of metaphenylene diamino as the amino compound and trimerisic acid chloride as the polyfunctional reaction reagent. As a result of carrying out the same procedure, the reverse osmosis performance shown in Table 1 was obtained.

As shown in the above examples, the present invention has a salt rejection rate of 0.3 to 0.5 compared to the conventional composite membrane manufacturing method.
% improved.

[Effect of the invention 1] The present invention makes it possible to provide a method for manufacturing a semipermeable composite membrane in which the salt rejection rate is improved by 0.3 to 0.5% compared to conventional methods for manufacturing a composite membrane. Ta.

Claims (2)

[Claims] (1) In a method for obtaining a semipermeable composite membrane by interfacial polycondensation, after (a) coating a porous support with an aqueous solution containing a compound having two or more reactive amino groups, (b) polycondensation, A hydrocarbon solution containing a functional reaction reagent (a)
(c) The surface is further brought into contact with a hydrocarbon solution containing a diluted polyfunctional reaction reagent (second stage treatment).
, A method for producing a semipermeable composite membrane, characterized by: (2) The hydrocarbon solution of (c) is 1/1/2 of the solution of (b).
Claim No. (1) characterized in that the polyfunctional reaction reagent has a concentration in a range of 10 or more and 8/10 or less.
A method for producing a semipermeable composite membrane as described in Section 1.