JPS62244404A - Permselective membrane - Google Patents

Abstract

PURPOSE:To prepare a permselective membrane of superb membrane preparing properties, reverse osmosis properties and chlorine resistance by reacting aromatic polycarboxylic acid component with mixed diamine component consisting of piperazine and 4,4'-diaminediphenyl sulfone. CONSTITUTION:Piperazine diamine, 4,4'-diaminodiphenyl sulfone and its derivative are mixed to form a diamine component. Mixture proportion is 5/95-65/35 mol ratio. As aromatic polycarboxylic acid component, terephthalic acid and isophthalic acid are used and reacted with diamine component to prepare copolyamide. Solution copolymerization or interfacial copolymerization is carried out. Polyamide thus prepared is dissolved in an adequate organic solvent to prepare a membrane. To adjust discharge of pore diameter of the membrane, micropore forming agents such as inorganic salt, glycerin and the like may be added to copolyamide solution. The thickness of membrane is adjusted as 0.05-1mu.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is a permselective membrane made of a specific copolyamide, which is particularly suitable for desalinating 114 water or brine water to obtain fresh water. Regarding permeable membranes.

(Prior art) A solution of one or more substances dissolved in a common solvent is pumped through a permselective membrane at a pressure higher than the osmotic pressure of the solution to selectively separate components in the solution. The selective permeation method, which allows water to pass through, and the reverse osmosis method, which allows water to pass through but not salts dissolved in it, are well known from fortune telling.These methods include selective permeation membranes, reverse osmosis membranes, Substantially the same semipermeable membranes are used (hereinafter both will be collectively referred to as selectively permeable membranes). This selectively permeable membrane is made of a polymeric material and has a dense homogeneous structure, either in the form of an ultrathin layer with a support or in the form of hollow fibers, or generally between 0.1 and 0.2 Some have a heterogeneous structure of an anisotropic gel membrane consisting of a dense surface polymer layer with a thickness of microns or less and a porous substructure that acts as a support for this thin layer. The membrane's high water permeability and desalination ability depend on the above-mentioned thin and dense surface polymer layer attached to one side, and membranes with such a heterogeneous structure are also called asymmetric membranes. There is.

Conventionally, cellulose acetate has been used industrially as a polymer for forming selectively permeable membranes, but this cellulose acetate membrane has had problems in terms of hydrolysis resistance, microbial resistance, membrane life, etc. To solve these problems, a selectively permeable membrane made of aromatic polyamide (see Japanese Patent Publication No. 53-43540) is known as a new membrane material to replace cellulose acetate. There is a problem in that it lacks durability against oxidizing chlorine, which is used as a water disinfectant, that is, it lacks chlorine resistance. Next, a reverse osmosis membrane obtained by crosslinking an aromatic diamine compound such as meta-phenylene diamine or para-phenylene diamine with an aromatic polyacid halide 1 or more such as trimesic acid chloride (JP-A-55-1/17] No. 06 (see publication) has been proposed, and the publication discloses that it has extremely good reverse osmosis performance and chlorine resistance. On the other hand, a reverse osmosis anisotropic membrane with good dechlorination properties made of polyamide 1 obtained by reacting a piperazine diamine with an aromatic dicarboxylic acid is known (see JP-A-7IQ-10-271). It is being

(Problems to be Solved by the Invention) The reverse osmosis membrane disclosed in JP-A-55-1471.06 has chlorine resistance, but the chlorine resistance is short-term. It turned out that it could not be used for a long time. In addition, polyamide 1 (using the above piperazine) is N, N-
It is sparingly soluble in organic solvents such as dinotylacetamide and N-methyl-2-pyrrolihen, and only dissolves in pro-benzene solvents such as formic acid and metacresol, which are dangerous to handle. Therefore, it has been found that it is difficult to industrially produce a selectively permeable membrane using this polyamide.

The present inventors have researched the film-forming properties, permselectivity, and chlorine resistance of copolyamides using piperazine-based diamines and 4,4'-diaminosyphenylsulfone. This invention was achieved by discovering that it depends on the chemical structure of the diamine component.
〕is.

=3- (Means for solving the problem) This invention provides a molar ratio of piperazine and 4,4'-diaminodiphenylsulfone and its derivatives from 5/95 to 5/95.
This is a permselective membrane made of a copolyamide obtained by reacting a 65/35 mixed diamine component with an aromatic polycarboxylic acid component.

The copolyamide used in this invention has a mixed diamine component of two types of diamine compounds, one of which is a piperazine-based diamine, that is, a six-membered aliphatic diamine represented by the formula %. R is hydrogen or a hydrocarbon group having 1 to 12 carbon atoms.

The piperazine diamines mentioned above include piperazine, 2-
Methylpiperazine, trans-2,5-dimethylpiperazine, cis-2,5-dimethylpiperazine-4=zine, 2,6-dimethylpiperazine, 2,3.5-1-
Dimethylpiperazine, 2,2,3,3,5,5,6.6
-octamethylpiperazine, 2,2,5.5-te1-ramethylpiperazine, 2,2,3,5,5.6-hexamethylpiperazine, 2-ethylpiperazine, 2,5-diethylpiperazine, 2. 3.5-1-ethylbiperazine, 2,2,3,5,5.6-hexamethylpiperazine,
2,3,5.6-te1-diethylpiperazine, 2-n-
Propylpiperazine, 2,6-di-n-propylpiperazine, 2,3.5-1-di-n-propylpiperazine,
2,3,5.6-Chitler [1 propylpiperazine, 2
-n-butylpiperazine, 2,5-di-n-butylpiperazine, 2,5-di-butylpiperazine (.

-Butylpiperazine, 2,3.5-1-di-n-butylpiperazine, 2-pentylpiperazine, 2-decylpiperazine, 2,5-divinylpiperazine, 2,5-diphenylpiperazine, 2-phenylpiperazine, 2,3
, 5, G-tetraphenylpiperazine, 2-naphthylpiperazine, 2,5-dinaphthylpiperazine, 2-tolylpiperazine, 2,5-diethylpiperazine, 2,3
, 5,6-tetra1-lulipiverazine, etc.
Particularly preferred are piperazine and trans-2,5-dimethylpiperazine.

4,7I'-diaminodiphenyl sulfone and its derivatives, which are one of the other diamine compounds, are represented by the formula 1-, where R' is a hydrogen atom or a carbon atom number of 1 to I
27j<hydrogen group, R' is a hydrogen atom or a monovalent organic group having no active hydrogen, and n is 0 or an integer of 1 to 3.

Other derivatives of the above-mentioned 4,4'-diaminodiphenylsulfone include 3,3'-dimethyl-4,4'-
Diaminodiphenylsulfone, N,N'-dimethyl-
Diaminosyphere sulfone, 3,3'-dini-
4,4'-diaminodiphenylsulfone is exemplified, and particularly preferred is lJ: 4,7I'-diaminodiphenylsulfone, and the above-mentioned 4,4'-
Less than an equivalent amount of 3,3'-diaminodiphenylsulfone, which is an isomer thereof, may be added to diaminodiphenylsulfone.

The mixing ratio of piperazine diamine and 4,4'-diaminodiphenylsulfone in the mixed diamine is such that the molar ratio is 5/95 to 65/35, preferably 10/90 to 60/
40, particularly preferably 1.0/90 to /IQ/60. If the piperazine diamine content is less than 5 mol %, not only good permselective performance cannot be obtained, but also the chlorine resistance of the membrane decreases. Furthermore, if the amount of piperazine diamine is more than 65 mol %, film forming properties will be reduced.

The aromatic polycarboxylic acid components of the copolyamide of this invention include phthalic acid, isophthalic acid, terephthalic acid, 4,
4'-diphenyldicarboxylic acid, 1.2-1], 3-1
■、4-51,5-11.6-11,7-11,8-1
Examples include 2.3-12,6-52,7-naphthalene dicarboxylic acid and acid halide compounds thereof.

Aromatic tricarboxylic acids such as 1-rimesic acid and 1-limeric acid and their acid halide compounds; pyromellitic acid, benzophenonetetracarboxylic acid and these acid halide compounds; 3-lylorosulfonylisophthalic acid chloride Compounds having three or more reactive groups with respect to such amines are also included. - Among the acid components, terephthalic acid, isophthalic acid, and acid halide compounds thereof are preferred.

In order to produce a copolyamide by reacting the above mixed diamine component and aromatic polycarboxylic acid component, polymerization methods commonly used for producing polyamides such as melt polymerization method, in-phase polymerization method, interfacial polymerization method, solution polymerization method, etc. Although polymerization methods and the like can be used, solution polymerization methods and interfacial polymerization methods are preferred.

Although various organic solvents can be used as the solvent in the solution polymerization method, amide solvents are particularly preferred. As the amide solvent, N-methyl-2-pyrrolidone, hexamethylphosphoramide, N,N-dimethylacetamide,
N,N-dimethylformamide and mixtures thereof can be mentioned. The above amide solvents include methylene chloride, chloroform, 2-dichloroethane, 1,
Chlorinated solvents such as 1.2-1-lichloroethane and 1,1,2.2-tetrachloroethane chlorobenzene may be mixed.

The mixing ratio of the amide solvent and the chlorine solvent varies depending on the mixing ratio of the mixed diamine component and the acid component, but it is generally preferable that the molar ratio is in the range of 50,150 to 9,515.

To explain the general solution polymerization method, the above mixed diamine compound is dissolved in the above amide solvent or a mixed solvent of an amide solvent and a chlorine solvent, and polycarboxylic acid halide or its solution is added to this solution and stirred. While reacting. The reaction temperature is preferably -20 to 100°C, more preferably -5 to 70°C. During the above polymerization reaction, in order to neutralize hydrogen chloride produced by polymerization,
and/or various inorganic and organic compounds may be added before, during, and after polymerization to facilitate dissolution of the polymer. Inorganic compounds for these additives include lithium chloride, calcium chloride,
Examples include potassium chloride, lithium carbonate, lithium oxide, lithium hydroxide, calcium hydroxide, and calcium carbonate. Examples of organic compounds include pyridine, triethylenediamine, 1-ethylamine, 1-3-n-propylamine, and triethylamine. r1-Butylamine, N-ethylpiperidine, N-allylpiperidine, N-methylmorpholine, N-ethylmorpholine, N-allylmorpholine, N,N-dimethylaniline, N,N-diethylaniline, N,N- Examples include dimethylpiperazine 1, among which N,N-dimethylaniline, N,N-diethylaniline is used when terephthalic acid halide is used as the acid component, and pyridine, when isophthalic acid halide is used. Triethylamine is preferred. - The additives described in (1) usually have a value of 0.5 to 1.5 of the generated hydrogen chloride.
twice the molar amount, preferably 1.0 times the molar amount. Further, as an additive, a compound having only one group that reacts with an amino group or an acid halide group may be used as a terminal stopper, if necessary. The total concentration of each component in the above solution polymerization reaction is preferably 5 to 35%. 78 after solution polymerization reaction
The copolymer is solidified by mixing the liquid in a coagulation bath of methanol, water, etc. which is compatible with the solvent described in 1-1 and is insoluble with the polymer. After filtering this solid, it is mixed with water. ,
A copolyamide is obtained by repeated washing with methanol etc. and vim.

Next, a general interfacial polymerization method will be explained. Examples of organic solvents for the organic phase used in interfacial polymerization include methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, ], , ],
, 2, Chlorinated hydrocarbons such as 2-tetrachloroethane; aliphatic hydrocarbons such as n-hexane, n-octane, and cyclohexanone; aromatic hydrocarbons such as xylene, benzene, toluene, and mixtures thereof. On the other hand, wood is most preferred for the aqueous phase, but an appropriate amount of a hydrophilic organic solvent such as methanol, ethanol, acetylene, etc. may be added to the water. Substances that 1-wrap with hydrogen chloride generated during interfacial polymerization include sodium hydroxide, 1-lium carbonate, lithium hydroxide, lithium carbonate, potassium hydroxide, and especially 1-lium hydroxide.
-lium and 1-lium carbonate are preferred. These 1~
The amount of the encapsulating agent is 0.5 to 1.5 moles per month of hydrogen chloride generated, and is appropriately selected depending on the type of metal salt. .

A copolyamide can be obtained by mechanically mixing a solution of a polycarboxylic acid halide compound dissolved in the organic solvent, such as an aqueous solution of the mixed diamine component and the hydrogen chloride trapping agent dissolved in water. It is preferable to mechanically mix a part of the organic phase in advance with the aqueous solution of the mixed diamine.

Further, in order to promote dissolution of the mixed diamine in water, a surfactant or a suitable organic solvent that is a good solvent for the mixed diamine can be added. The concentration of mixed diamine in the aqueous solution and the concentration of polycarboxylic acid halide in the organic solvent solution are preferably 0.3 to 10% by weight. This concentration is appropriately selected depending on the solubility of the two diamines described in - in water. The polymer solution obtained by interfacial polymerization is mixed with ethanol, water, etc. to solidify the polymer, as in the case of solution polymerization, and the copolyamide 1 Get it and get it.

The copolyamide obtained by the above various polymerization methods is dissolved in a suitable organic solvent, and this copolyamide solution is applied onto a suitable plate such as a glass plate or a metal plate. A selectively permeable membrane can be formed by immersing the organic solvent in a coagulating liquid that is compatible with the organic solvent mentioned above. A selectively permeable membrane can also be formed by evaporating the organic solvent from the plate. Furthermore, hollow fibers can also be formed by spinning the copolyamide solution through a nozzle. Furthermore, a composite sheet can be obtained by coating the copolyamide solution on a suitable porous membrane and forming the membrane as described above.

During the above film formation, a micropore forming agent can be added to the copolyamide solution for the purpose of adjusting the pore size distribution of the film. Examples of the pore-forming agent include inorganic agents such as lithium chloride, magnesium chloride, and calcium chloride, and organic agents such as ethylene glycol, polyethylene glycol, glycerin, and derivatives thereof.

Suitable porous membranes mentioned in 2 above include porous membranes made of polymer compounds such as polyethylene, borisulfone, polypropylene, and polyimide, and porous substances made of inorganic substances such as silica gel, alumina, silica alumina, and zeolite. be. -The coating method for the above porous membrane is as follows:
Any method such as a dipping method, a roll coating method, or a quick coating method may be used. The thickness of the applied film is between 0.05 and 1.0 microns, preferably between 0.1 and 0.
．． Adjusted to be 5 microns.

Also, instead of applying a copolyamide solution to a porous membrane,
It is also possible to form a copolyamide film on the porous membrane by applying a solution of the mixed diamine described in -1 above to the porous membrane and then immersing it in an organic solvent solution of dicarboxylic acid chloride for a predetermined period of time. At this time, in order to increase the strength of the membrane, amines that are active against amines such as 1-rimesic acid chloride, melimellitic acid chloride, pyromellitic acid chloride, penzophenone 1-lacarboxylic acid chloride, and 3-chlorosulfonylisophthalic acid chloride are added. Compounds having three or more reactive groups can be added.

(Function) Since the copolyamide obtained using the mixed diamine component of piperazine diamine and 4,4'-diaminodiphenylsulfone is dissolved in an organic solvent such as dimethylformamide, N-methylpyrrolidone, or dimethylformamide, Good film formability. The obtained permselective membrane has excellent permselectivity and particularly excellent chlorine resistance.

Example 1 4.4'-diaminodiphenylsulfone 1.9.84
g (o, og mole), piperazine 1.72 g (0,
02 mol), 200 mfl-h of N-methylpyrrolidone
Add 28mQ of ethylamine and feed it under a nitrogen stream into four 5tH500mQ flasks equipped with a nitrogen inlet tube, a thermometer, and a stirrer. After stirring for 1 minute, cool the entire reaction system with ice. , Isophthalic acid loli 1-20.3
1 g (0.1 mol) is added under a stream of nitrogen. After reacting for about 60 minutes under water cooling, the mixture was returned to room temperature and the reaction system was further stirred for about 1 hour. After the reaction was completed, the reaction solution was poured into 1500 mQ of methanol to precipitate the copolyamide. This precipitate was crushed several times using a household mixer, filtered, washed with water, etc. to remove unreacted substances and solvent, and finally washed with methanol.
A purified copolyamide was obtained by drying at 40°C and 1 vacuum F for 48 hours. The yield of the obtained purified product was about 82%, the reduced specific viscosity (0.5 g/dQ sulfuric acid, 30 ° C.) was 0.69,
The piperazine content determined by NMR was 21% based on the total diamine content.

Example 2 In Example 1, trans-2 was used instead of piperazine.
, 2.28 g of 5-dimethylpiperazine (0,02
A purified copolyamide was obtained in the same manner as in Example 1, except that the copolyamide was changed to (mol). The yield of the obtained purified product was about 79%, the reduced specific viscosity was 0.64, and the piperazine content was 20% based on the total amount of diamine.

Example 3 A purified copolyamide was obtained in the same manner as in Example 1 except that terephthalic acid chloride was used instead of isophthalic acid chloride. The yield of the obtained purified product was about 80%, and the reduced specific viscosity was 1.35.

Example 4 A purified copolyamide was obtained in the same manner as in Example 2 except that terephthalic acid chloride was used instead of isophthalic acid chloride. The yield of the obtained purified product was about 80%, the reduced specific viscosity was 0.91, and the homopiperazine content was 20% based on the total amount of diamine.

Comparative Example 1 10.80 g (0.10 mol) of metaphenylenediamine and 50 mQ of N-methylpyrrolidone were placed in a four-eye round bottom flask with a capacity of 500 mQ equipped with a nitrogen inlet tube, a thermometer, and a stirring blade. After stirring to make it homogeneous, it was cooled to 0°C, and while stirring, 20.30 g (0,] mol) of powdered isophthalic acid chloride was added at once to remove the isophthalic acid that had adhered to the inner wall of the container. Acid chloride with N
-Methylpyrrolidone] Wash off with OmQ. When isophthalic acid chloride is added, the temperature of the reaction system rises to about 50°C, so the reaction system is stirred for about 1 hour while being cooled, and then returned to room temperature and stirred for another 2 hours to complete the reaction. The obtained solution was poured into 1500 m Q of methanol to precipitate the polyamide. The precipitate was filtered, pulverized in a home mixer filled with water, washed, and dried under reduced pressure for 24 hours to obtain a purified polyamide. The yield to polyamide 1 is approximately 8
5%, and the reduced specific viscosity was 1.35.

Comparative Example 2 A purified polyamide was obtained in the same manner as in Comparative Example 1 except that terephthalic acid chloride was used instead of isophthalic acid chloride. The yield of this polyamide was about 73%, and the reduced specific viscosity was 1.94.

Comparative Example 3 A copolyamide was obtained in the same manner as in Comparative Example 1, except that a mixed diamine compound of metaphenylene diamine and 2,4-diaminobenzenesulfonic acid (molar ratio 10 mol%) was used.

The yield of this copolyamide was 82%, and the reduced specific viscosity was 0.9.
It was 0.

Comparative Example 4 Comparative Example 3 except that terephthalic acid chloride was used instead of isophthalic acid chloride 1- in Comparative Example 3.
A copolyamide was obtained in the same manner as above. The yield of this copolyamide was about 83%, and the reduced specific viscosity was 1.13.

Comparative Example 5 8.6 g (0.10 mol) of piperazine, 8.4 g (0.21 mol) of sodium hydroxide, and 300 cc of water were supplied to a 2Q cylinder and uniformly dissolved, and this solution was cooled with water. While stirring, add 300m of cyclohexanone Q
1 to 20.3 g of isophthalic acid salt dissolved in (0
, 10 mol) and stirred for about 5 minutes to react. This reaction product was purified in the same manner as in Example 1, and the yield of the purified product was 67%, and the reduced specific viscosity was 0.91. .

Comparative Example 6 A polyamide was obtained in the same manner as in Comparative Example 5, except that terephthalic acid chloride was used instead of isophthalic acid chloride. The yield was 68%, and the reduced specific viscosity was 0.98.

Comparative Example 7 0.86 (0.01 mol) of piperazine, 4.32 g (0.04 mol) of metaphenylenediamine, 4.8 g (0.12 mol) of sodium hydroxide and 160 mQ of water were fed into the cylinder of IQ. 10.15 g of isophthalic acid chloride (0.05 g
mol) was added thereto and reacted by stirring for about 60 minutes, and 300 cc of n-hexane was added to the reaction product to precipitate it, and the product was purified in the same manner as in Example 1 to obtain a copolyamide. The yield of this copolyamide was 74%, and the reduced specific viscosity was 1.34.

Comparative Example 8 A copolyamide was obtained in the same manner as in Comparative Example 7, except that terephthalic acid chloride was used instead of isophthalic acid chloride. The yield of this copolyamide is 7
1%, and the reduced specific viscosity was 1.26.

Comparative Example 9 In Comparative Example 1, 4 was used instead of metaphenylenediamine.
A polyamide was obtained in the same manner as in Comparative Example 1 except that ,4'-diaminodiphenylsulfone was used. The yield of this polyamide was 88%, and the reduced specific viscosity was 0.81.

Comparative Example 10 A polyamide was obtained in the same manner as Comparative Example 1 except that terephthalic acid chloride was used instead of isophthalic acid chloride in Comparative Example 9. The yield of this polyamide is 88%
, and the reduced specific viscosity was 1.30.

The polyamides obtained in each of the above examples and comparative examples were
2 by dissolving in N,N-dimethylacetamide or N-methyl-2-pyrrolidone containing 5% by weight of lithium chloride.
0% solution, this polyamide solution was applied to a glass plate with a thickness of 300 microns, and heated for 30 minutes in a constant temperature bath at 110°C.
The solvent was evaporated by heating for a minute, and after cooling, the glass plate was immersed in water to form a thin film on the glass plate, and then peeled off from the glass surface to produce an asymmetric film. The reverse osmosis membrane performance of these asymmetric membranes is shown in Table 1 below.

In Table 1, acid component 1 is isophthalic acid chloride,
'r is telophthalic acid chloride, 43 of the diamine component (f) is /l, /l'-diaminodiphenylsulfone,
rn is metaphenylenediamine, ρ of diamine component (2)] P is piperazine, d m p is 1-rance-2,5
-dimethylpiperazine, nl! i is metaphenylenediamine-4-sulfonic acid, and the molar ratio of the diamino component (
%) is the molar ratio of diamine component (2) to all diamine components (1) and (2). Film forming property: ◎ is very good.
○ indicates good+r, △ indicates defective, and X indicates impossible. The water permeation rate and salt removal rate indicate the performance of the reverse osmosis membrane.
A saline solution at 25°C containing 000 ppm is passed as a stock solution;
The difference between the salt concentration in the stock solution and the salt concentration in the permeated water is expressed as a percentage salt removal rate (%) (the larger the number, the better the salt removal performance).
1. Eye 1. ．． "With X4J" means the above 35,000 ppm
A chlorine-containing saline solution containing 5 [) yen + 111 chlorine in the saline solution was supplied as a stock solution, and the water permeation amount and salt removal rate after 10 hours were shown.

The amount of chlorine absorbed is 150° after freezing and crushing polyamide.
C1 0.5g of fine powder of 10 microns or less dried in a vacuum chamber for about 15 hours was used as a chlorine source to add hypoxic acid,
(S and P) - (Added to 500 cc of a chlorine aqueous solution with a chlorine concentration of 220 ppm and pH 5 obtained by mixing phosphoric acid, 1 potassium dihydrogen phosphate, and 2 potassium 1 hydrogen phosphate as a buffer for adjustment. Then, in a constant temperature bath at 40°C, the chlorine absorption rate was determined from the change in chlorine concentration in the chlorine aqueous solution over time. The value obtained by subtracting this value is the chlorine absorption rate of the polyamide itself, and is expressed as the molar ratio of the amount of chlorine absorbed per mole of polyamide one hour after the start of the chlorine absorption rate measurement test.The smaller the amount of chlorine absorbed, the better the chlorine resistance of the polyamide. is excellent.

Examples 5 to 12 The molar ratio of perazine in the mixed diamine in Example 1 was changed from 20 mol% to 10.30,/l0160 mol%, and the mixed diamine in Example 4 was The molar ratio of trans-2,5-dimethylpiperazine in is 20 mol%, 10.30.4
A copolyamide was obtained in the same manner as in Example 1 or Example 4 except that the content was changed to 0.60 mol%. The yield of these copolyamides is 80-90%, and the reduced specific viscosity is 0.70-
It was in the range of 1.0. And these polyamides are
Even if the amount of piperazine mixed increases to 60 mol% based on the total amount of mixed diamine, N-methylpyrrolidone or N,N
The film-forming properties were good, with a dissolution amount of 20% by weight or more in the -dimethylacetamide solvent. The performance test results of the above copolyamide are shown in Table 2 below.

(Blank below) =25- Table 2 ■ Examples 13 to 14 In Example 1 or Example 4, 3,3'-diaminodiphenylsulfone (35) was added to 4,4'-diaminodiphenylsulfone (4s). In addition, 4 in the mixed diamine
A copolyamide was obtained in the same manner as in Example 1 or Example 4, except that the molar ratio % of 5/3S/viverane was 56/24/20. These copolyamides had a solubility of 20 weight percent or more in a solvent of N-methylpyrrolidone or N,N-dimethylacetic acid, and had good film-forming properties. The performance of the above copolyamide membrane is shown in Table 3 below.

(Blank below) Table 3 (Effects of the Invention) The selectively permeable membrane according to the present invention not only has excellent membrane formability and reverse osmosis performance, but also has particularly chlorine resistance, and can desalinate seawater and shrubs. suitable for

Patent applicant: Toyobo Co., Ltd. Agent: Patent Attorney Takehiro Sakano Yoshi 1st completed Tsukasa

Claims (1)

[Scope of Claims] [1] Molar ratio of piperazine diamine to 4,4'-diaminodiphenylsulfone and its derivatives: 5/95
A selective permselective membrane made of a copolyamide obtained by reacting a mixed diamine component of ~65/35 with an aromatic polycarboxylic acid component. [2] The permselective membrane according to claim 1, wherein the piperazine diamine is piperazine or trans-2,5-dimethylpiperazine, and the aromatic polycarboxylic acid component is isophthalic acid chloride or terephthalic acid chloride. .