JPH0829238B2 - Permselective separation membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a permselective membrane made of a specific copolyamide, which is particularly suitable for desalination of seawater or brackish water to obtain fresh water. Regarding the membrane.

(Prior Art) A solution of one or more organic substances dissolved in a common solvent is pressure-fed to a permselective membrane at a pressure higher than the osmotic pressure of this solution, or the permeation side is reduced to a low pressure. The dialysis method and pervaporation separation method, which allow the components to pass through the selective droplets to be separated, and the reverse osmosis method, which allows water to pass selectively from the aqueous solution of the inorganic salt, but does not allow the inorganic salts to pass. In these methods, a selectively permeable membrane or a membrane called a reverse osmosis membrane is used. (Hereinafter, both are collectively referred to as a permselective separation membrane.) Such a permselective separation membrane is generally made of an organic polymer substance.

Its morphology is a homogeneous film consisting of a dense and homogeneous structure, a composite film in which it is applied to a suitable support, or generally 0.1-0.3.
There is a membrane having an asymmetric structure composed of a dense surface polymer layer having a thickness of micron or less and a porous lower structure which is the same material and supports the thin layer. This is generally called an asymmetric membrane. The high water permeability and desalination performance of this asymmetric membrane relies on the thin, dense surface polymer layer described above. Conventionally, cellulose acetate has been industrially used as a material for a selectively permeable separation membrane.
However, this membrane has hydrolysis resistance, microbial resistance, heat resistance,
There was a problem in terms of film life. In the patent, aromatic polyamide is known as a new separation membrane material replacing cellulose for the purpose of improving these points (Japanese Patent Publication No. 53-43).
540). As a result, although the hydrolyzability, microbial degradability, and thermal degradation resistance have been improved, the problem is that it is extremely weak against chlorine (oxidizing chlorine) used as a bactericide for water, that is, it lacks chlorine resistance. is there.

Further, a membrane obtained by cross-linking metaphenylenediamine and paraphenylenediamine with an aromatic polyacid halide such as trimesic acid chloride has been proposed (JP-A-55-147106). It is disclosed that it has not only very good reverse osmosis membrane performance, but also chlorine resistance.

(Problems to be Solved by the Invention) The reverse osmosis membrane disclosed in JP-A-55-147106 has chlorine resistance, but the chlorine resistance is only short-term and long-term. It turned out to be unusable. As described above, no aromatic copolyamide having excellent chlorine resistance and selective permeation is known among aromatic polyamides using aromatic polyamines.

The present inventors have studied the film-forming property, selective permeability, and chlorine resistance of copolyamides using various kinds of aromatic polyamine compounds, and as a result, the above performance depends on the chemical structure of the copolyamide aromatic polyamine compound. The present invention has been made and has led to the present invention.

(Means for Solving the Problems) This invention is mainly composed of an aromatic diamine compound (A) having at least one diphenylsulfone unit and a pyridine ring-containing diamine compound (B), and the mixing molar ratio thereof is
A mixed diamine component of 95/5 to 50/50 is reacted with an aromatic polycarboxylic acid component so as to be substantially equal to each other. Excellent chlorine resistance.

 (A) and (B) are represented by the following general formula.

In particular, from a copolyamide in which the aromatic diamine compound (A) is 3,3′-diaminodiphenyl sulfone and / or 4,4′-diaminodiphenyl sulfone, and the pyridine ring-containing diamine compound (B) is 2,6-diaminopyridine. The selectively permeable separation membrane is excellent in film forming property and chlorine resistance.

The diamine compounds (A) and (B) and the aromatic polycarboxylic acid component used for producing the aromatic copolyamide of the present invention are as follows.

The aromatic diamine compound (A) may be any aromatic diamine compound containing a diphenyl sulfone unit, and representative examples thereof include 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 3 ,
4'-diaminodiphenyl sulfone, 3,3'-dinitro-
4,4'-diaminodiphenyl sulfone, bis [4- (3
-Aminophenoxy) phenyl] sulfone, bis [4-
(4-aminophenoxy) phenyl] sulfone and the like can be mentioned. 3, in terms of selective permeability and chlorine resistance
Particularly preferred are 3'-diaminodiphenyl sulfone and 4,4-diaminodiphenyl sulfone. In the case of using two or more kinds of the above-mentioned diamine compounds, it is possible to mix them at any ratio, but it is possible to use 3,3'-diaminodiphenylsulfone compound and 4,4'-diaminodiphenylsulfone compound. The molar ratio is preferably 50/50 to 0/100 from the viewpoint of salt removal rate. It is also possible to add the above-mentioned diamino compound as a main component, and other components not described in the present specification. However, if it exceeds 50 mol%, it is not preferable from the viewpoint of chlorine resistance.

Examples of the pyridine ring-containing diamine compound (B) include 2,3
-Diaminopyridine, 3,4-diaminopyridine, 2,5-diaminopyridine, 2,6-diaminopyridine, 2,3,6-triaminopyridine, 2,6-diamino-4-methylpyridine and the like. .

The preferred pyridine ring-containing amine compound (B) is 2,6-diaminopyridine from the viewpoint of solubility in an aprotic amide solvent, chlorine resistance and salt removal rate. The pyridine ring-containing diamine compound (B) mainly used is one kind, but it is also possible to mix and use two or more kinds according to the application. The pyridine ring-containing diamine compound (B)
The mixing ratio of the aromatic diamine compound (A) and the aromatic diamine compound (A) has a great influence on the physical properties of the copolyamide produced, and the range is (A) / (B) of 95/5 to 50/50 in terms of molar ratio. . When the amount of the pyridine ring-containing diamine compound (B) is more than 50 mol%, it is difficult to control the degree of polymerization and it is difficult to obtain a highly viscous copolyamide. Therefore, it becomes difficult to form a film, a film or the like. Along with this, the solubility of the copolyamide in the aprotic amide solvent also deteriorates. A more preferable amount of the pyridine ring-containing diamine compound (B) is in the range of 10 to 40 mol% with respect to the total amount of diamine components, and particularly preferably in the range of 10 to 30 mol% from the viewpoint of chlorine resistance.

As the aromatic polycarboxylic acid component in the present invention, phthalic acid, isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, 1,2-naphthalene dicarboxylic acid, 1,3
-Naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene Examples thereof include dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid and acid halide compounds thereof (chloride, bromide, etc.). Of these, isophthalic acid dichloride and terephthalic acid dichloride are particularly preferable from the viewpoint of reactivity and solubility in an aprotic amide solvent. Other polycarboxylic acids and trimellitic anhydride, trimesic acid and their acid halide compounds, pyromellitic dianhydride, etc. are mentioned.

The above aromatic polycarboxylic acid components can be mixed and used in any proportion depending on the application. The molar ratio of isophthalic acid dichloride to terephthalic acid dichloride is preferably 50/50 to 100/0 from the viewpoint of solubility in an amide solvent and salt removal rate.

The copolyamide of the present invention can be synthesized by the following solution polymerization method. As the solvent used in the solution polymerization method, various kinds of organic solvents can be used, but an aprotic amide solvent is preferably used.

Preferred solvents include N-methyl-2-pyrrolidone, hexamethylphosphoramide, N, N-dimethylacetamide, N, N-dimethylformamide, and mixed systems thereof. Most preferred is N-methyl-2-pyrrolidone.

The above solvents used for solution polymerization must be sufficiently dehydrated in advance by a dehydrating agent such as distillation or molecular sieve. The water content of the solvent used in the solution polymerization reaction of the present invention is 200 ppm or less, preferably 100 ppm or less, and particularly preferably 50 ppm or less.

It is possible to use various kinds of amine compounds as reagents for trapping hydrogen chloride generated during the polymerization, and aliphatic tertiary amine compounds such as triethylenediamine, triethylamine and N-methylmorpholine, pyridine, α-picoline, β -Picoline, γ-picoline, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-propylpyridine, 4-propylpyridine, and other pyridine-based compounds, N, N-dimethylaniline, N, N-diethylaniline And other N, N-dialkylaniline compounds.

The water content of the acid scavenger used in the polymerization reaction of the present invention is 20
0 ppm or less, preferably 100 ppm or less, particularly preferably 50 pp
m or less. The acid scavenger used is purified by distillation in advance, and further by molecular sieves,
It is preferable to perform sufficient dehydration treatment.

As a general polymerization method of solution polymerization, a mixture of the diamine compounds (A) and (B) is dissolved in the amide solvent under a nitrogen stream. The concentration of the charged monomer in the solvent is 10 to 50% (wt monomer / vol solvent), preferably
20-40%. Further, a predetermined amount of the scavenger for hydrogen chloride produced during the reaction described above is added to the mixed system. The addition amount of the acid scavenger is not particularly limited, but basically it is preferably 1.0 to 3.0 times mol, and more preferably 1.0 to 2.0 times mol of the theoretically generated hydrogen chloride amount generated during the reaction. The amount of the acid scavenger added depends on the type of the acid scavenger, and therefore the amount cannot be limited.

Dissolving the diamine compound in a solution consisting of the solvent and the acid scavenger, in the case of a uniform solution, for the purpose of improving the solubility of the diamine compound, by adding a suitable solvent, or heating the solution It is also possible to do so. The solvent for promoting the solubility needs to be sufficiently dehydrated in advance by distillation or a desiccant. The heating temperature may be any temperature as long as it does not decompose the solvent used and the amine compound, but the most preferable temperature is room temperature.

Then, the solution is cooled to −10 ° C. to 20 ° C., preferably −5 ° C. to 10 ° C. with a suitable refrigerant. As the refrigerant, water and / or ethylene glycol are generally and preferably,
The method is not particularly limited. Then, the aromatic polycarboxylic acid halide compound and / or the anhydride is added to the cooled solution containing the diamine compound, the acid scavenger and the reaction solvent with stirring, and the stirring is continued for an appropriate time. The form of the aromatic polycarboxylic acid component at the time of addition may be any form such as a solid state (powder form, flake form or pellet form), a solution state dissolved in an appropriate solvent, or a state melted by heating. It is possible.

The addition rate of the aromatic polycarboxylic acid component to the solution may be any rate as long as it does not continuously exceed 70 ° C., but it is preferable to add it as soon as possible from the viewpoint of formation of a high polymer. . Further, the stirring speed at the time of adding the aromatic polycarboxylic acid component affects the degree of polymerization of the produced polymer, and the higher the stirring rate, the higher the degree of polymerization of the obtained polymer, It is preferable in terms of physical properties. After addition of the aromatic polycarboxylic acid component, stirring is continued for about 30 minutes to 1 hour under the above cooling.
The stirring speed at this time may be any speed, but it is preferably as high as possible. After the reaction under cooling as described above, the polymerization reaction is continued at room temperature for about 1 to 2 hours. The stirring speed at this time may be any speed, but it is preferable that the stirring speed is as high as possible in order to obtain a highly viscous polymer.

A suitable substance may be added to the reaction system before, during, and after the polymerization in order to neutralize hydrogen halide generated during the polymerization and / or to facilitate the dissolution of the polymer in the reaction solvent. It is possible. Preferred examples of such inorganic compounds include lithium chloride, calcium chloride, potassium chloride, lithium carbonate, lithium oxide, lithium hydroxide, calcium hydroxide and calcium carbonate. Lithium chloride, calcium chloride, potassium chloride and the like can be added before the polymerization for the purpose of accelerating the dissolution of the polymer, but the others are preferably added after the polymerization for the purpose of neutralizing generated hydrogen halide. Further, as an organic compound having such an effect, propylene oxide is mentioned as a preferable example. The substance can be added before and / or after the polymerization.
If necessary, a terminal terminating agent can be used as the other additive, and as the terminal terminating agent, a compound having only one group that reacts with an amino group and an acid halide group is suitable.

After the polymerization reaction, the obtained solution is mixed with a poor solvent for the polymer such as methanol and water to take out the polymer as a solid. Further, the solid polymer is filtered, and the solvent adsorbed to the polymer is repeatedly washed with water and methanol,
Acid scavengers, hydrochloric acid and oligomers should be removed as much as possible. Thoroughly washed polymer at 130 ℃ -1
The copolyamide of the present invention can be obtained by vacuum drying at 50 ° C.

Next, a general method of interfacial polymerization will be described. The organic solvent of the organic phase used in the interfacial polymerization is preferably an organic solvent which is immiscible with water, and examples thereof include chlorine-based carbonization such as methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, 1,1,2,2-tetrachloroethane, and the like. Examples thereof include hydrogen solvents, aliphatic hydrocarbons such as n-hexane, n-octane and cyclohexanone, aromatic hydrocarbons such as xylene, benzene and toluene, and mixtures thereof.

As a substance that traps hydrogen chloride generated during interfacial polymerization, sodium hydroxide, sodium carbonate, lithium hydroxide, lithium carbonate, potassium hydroxide, etc. are used. Sodium and sodium carbonate are preferred. The amount of the additive is
It is usually used in an amount of 0.5 to 1.5 times the molar amount of hydrogen chloride generated and is determined according to the metal species.

A general interfacial polymerization operation will be described. A solution in which the diamine compounds (A) and (B) and the above hydrogen chloride trapping agent are dissolved in water, and a solution in which the polycarboxylic acid halide compound is dissolved in the above organic solvent. Are mechanically mixed to obtain the polymer of the present invention. At this time, a part of the organic phase not containing the polycarboxylic acid halide is mechanically mixed with the aqueous phase containing the diamine compounds (A) and (B) in advance, and the organic phase containing the polycarboxylic acid halide is contained therein. It is preferable to add the solution of the solvent with stirring.

In order to accelerate the dissolution or dispersion of the diamine compounds (A) and (B) used in the present invention, it is possible to heat the aqueous phase or add a surfactant to the aqueous phase. . Generally, the concentrations of the polycarboxylic acid halide and the diamine compound in the organic phase and the aqueous phase are preferably 0.3 to 10% by weight. This concentration is the diamine compound (A)
Depending on the solubility of (B) and (B) in water, an appropriate concentration must be selected.

The solution obtained after the polymerization reaction is mixed with methanol, water and the like to form a precipitate, and then filtration and washing with water are repeated several times, and then dried at 130 to 150 ° C. for about 24 hours to obtain the present invention. Can be obtained.

An asymmetric membrane is obtained by dissolving the copolyamide obtained by the present invention in a suitable organic solvent, coating the solution on a suitable plate (glass, metal plate), and immersing the solution in a poor solvent for the copolyamide. be able to. At this time, as the micropore-forming agent, glycol-based organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin and their derivatives and / or lithium chloride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, It is also possible to add an inorganic compound such as strontium chloride or magnesium perchlorate to the organic solvent to form an asymmetric film.

It is also possible to obtain a homogeneous film by evaporating the organic solvent from the plate coated with the solution containing no micropore-forming agent composed of an organic compound or an inorganic compound having a high boiling point.

Furthermore, it is also possible to form a hollow fiber form by spinning these solutions, or to form a composite film by coating the solution of the copolyamide obtained in the present invention on a suitable porous film. It is possible. The porous film used is a porous film obtained from a polymer compound, for example, an organic porous film such as polyethylene, polysulfone, polypropylene, or polyimide, or an inorganic porous film such as silica gel, alumina, silica alumina, or zeolite. The substance is suitable. As this coating method, any method such as a dipping method, a roll coating method, a quick coating method may be used. The thickness of the applied polymer is 0.05-1.0 micron,
The coating conditions should be controlled so that it is preferably 0.1 to 0.5 micron. It is also possible to form a thin film on the support by coating or by the so-called interfacial polymerization method as follows. That is, after applying the solution of the diamine compound (A) and (B) of the present invention on the porous membrane,
It is also possible to form a copolyamide film of the present invention, a so-called composite film, on the porous film by immersing it in an organic solvent in which a polycarboxylic acid component is dissolved for a predetermined time. It is also possible to form the composite film on the porous film by reversing the above order, that is, by coating the solution of the polycarboxylic acid component on the porous film and immersing it in the solution of the diamine compound. Examples of the porous membrane material used include polymer compounds such as polyethylene, polypropylene, polysulfone, polyether, polysulfone ether, polyamide and polyimide. It is also possible to form the copolyamide film of the present invention on a porous film material made of an inorganic compound such as silica gel, alumina, silica-alumina, or zeolite.

In order to increase the strength of the film during the formation of the composite film, it is reactive against amines such as trimesic acid chloride, trimellitic acid chloride, 5-chlorosulfonylisophthalic acid chloride, pyromellitic acid chloride and benzophenone tetracarboxylic acid chloride. The compound having 3 or more groups may be added in any proportion.

(Function) A copolyamide obtained by reacting an aromatic polycarboxylic acid component with a mixed diamine component composed of an aromatic diamine compound containing at least one diphenylsulfone unit and a pyridine ring-containing diamine compound has good film-forming properties. The membrane has excellent reverse osmosis performance and chlorine resistance.

Furthermore, the permselective membrane composed of a copolyamide using a diaminodiphenyl sulfone compound and diaminopyridine as the polyamine component has particularly excellent chlorine resistance and selective permeation performance.

The present invention is described in detail in the following examples, but the present invention is not limited to these examples. Various physical properties of the copolyamide and the membrane were measured by the following methods.

(Manufacturing method of asymmetric membrane) The polymer obtained in the present invention was used as a 20% solution of N, N-dimethylacetamide or N-methyl-2-pyrrolidone (5%
(Containing LiCl) and coated on a glass plate at a thickness of 300 microns. Evaporate the solvent by heating in a constant temperature bath at 110 degrees for 10 minutes. After cooling, it is dipped in water to form an asymmetric film. This was peeled from the glass surface and subjected to the following reverse osmosis membrane experiment and chlorine resistance test.

(Reverse osmosis membrane test method and chlorine resistance test) Using a normal continuous pump type reverse osmosis device,
Using an aqueous solution containing 000ppm NaCl, the operating pressure is 55
It was performed at kg / cm ² . In addition, the chlorine resistance test of the membrane was carried out by adding sodium hypochlorite and hydrochloric acid to the above aqueous solution,
The same operation was repeated as an aqueous solution having a chlorine concentration of about 10 ppm. The reverse osmosis performance was measured about 20 hours after the start of the operation, and the chlorine resistance was evaluated by the difference from the time when no chlorine was added. That is,
The smaller the difference in reverse osmosis performance between when chlorine is not added and when chlorine is added, the better the chlorine resistance.

(Calculation of Water Permeation Rate (FR) and Salt Removal Rate (Rj)) The water permeation rate in the examples is 1 m ³ , and is shown as the amount of water that permeates the membrane per day. The salt removal rate was calculated by the following equation.

(Comparative Example 1) Synthesis of poly (isophthaloyl metaphenylenediamine) and evaluation of reverse osmosis performance.

A homogeneous solution containing 10.80 g (0.10 ml) of meta-phenylenediamine purified by distillation and 150 ml of dehydrated and purified N-methylpyrrolidone in a 500-ml four-necked round bottom equipped with a nitrogen inlet tube, thermometer, and stirring blade. And In an ice-cooled system,
While stirring, 0.1 mol of isophthalic acid chloride (20.30
g) was added at once in powder form. N the reagent attached to the container
Washed off with 10 ml of methylpyrrolidone.

The reaction system was stirred under ice cooling for about 1 hour and further at room temperature for 2 hours. The reaction solution was poured into about 1500 ml of methanol to obtain a polymer solid. The solid obtained by filtration was crushed and washed with a home mixer. Then, the purified product was dried under reduced pressure at 130 ° C. for 24 hours. Logarithmic viscosity of the polymer was _{1.35 (0.5g / dl-H 2} SO 4). Further, when an asymmetric membrane was prepared and a reverse osmosis experiment was performed according to the method described above, the water permeability and the salt removal rate were 84.0% respectively.
/ m ² · day and 61.5%.

(Comparative Example 2) Synthesis of poly (terephthaloyl metaphenylenediamine) and film-forming property evaluation.

Comparative Example 1 except that terephthalic acid chloride was used instead of isophthalic acid chloride in Comparative Example 1.
The copolyamide was synthesized in the same manner as in. Attempts were made to make asymmetric membranes according to the method described above, but no asymmetric membrane that could withstand reverse osmosis experiments was obtained.

(Comparative Examples 3 and 4) Synthesis of poly (isophthaloyl metaphenylenediamine / 2,6-diaminopyridine (90/10 and 70/30)) copolymer and evaluation of reverse osmosis performance.

Comparative Example 1 was the same as Comparative Example 1 except that a mixture of metaphenylenediamine and 2,6-diaminopyridine (amount of 2,6-diaminopyridine = 10 and 30 mol%) was used instead of metaphenylenediamine. , The copolyamide was synthesized.

When asymmetric membranes were made and reverse osmosis experiments were conducted according to the method described above, the water permeation rates were 58.6 and 62.0 /
The m ² · day and salt removal rates were 67.7 and 73.5%, respectively. However, as shown in the table, all of the present membranes have poor chlorine resistance.

(Comparative Examples 5 and 6) Synthesis of poly (terephthaloyl metaphenylenediamine / 2,6-diaminopyridine (90/10 and 70/30)) copolymer and evaluation of film forming property.

Comparative Examples 3 and 4, except that terephthalic acid chloride was used instead of isophthalic acid chloride
The copolyamide was synthesized in the same manner as 3 and 4. The logarithmic viscosity of the copolyamide is 1.23 and 1.06, respectively.
It was _{(0.5g / dl-H 2 SO} 4). Attempts were made to make asymmetric membranes according to the method described above, but no asymmetric membrane that could withstand reverse osmosis experiments was obtained.

Example 1 1.09 g (0.01 mol) of 2,6-diaminopyridine and 22.35 g (0.09 mol) of 4,4′-diaminodiphenyl sulfone were added to 300 ml of 4 equipped with a nitrogen introducing tube, a thermometer and a stirrer. Place in a two-necked flask under a nitrogen stream. Furthermore, pyridine 20ml (0.25mol), N-methylpyrrodone (NMP) 150ml in this system
Is added and heated to about 40 ° C. to dissolve the monomer. After dissolution, stirring with stirring, 20.30 g of isophthalic acid chloride
(0.10mol) is added rapidly under a nitrogen stream. The reaction system is stirred for about 60 minutes at room temperature, and this solution is added to 1500 ml of methanol to precipitate the polymer. A series of purification steps of crushing the polymer with a household mixer, filtration, and washing with water and methanol were repeated several times to remove unreacted substances in the polymer and remove the solvent. Subsequently, the polymer was dried at about 150 ° C. under vacuum for about 48 hours. The reduced viscosity of the obtained polymer (ηsp /
c) was 0.63 (0.5 g / dl NMP, 30 ° C). The content of 2,6-diaminopyridine determined by proton NMR was 5 mol% based on the total amount of amines in the copolyamide. According to the reference example, the production of the obtained polymer asymmetric membrane, the reverse osmosis experiment, and the chlorine resistance test were carried out, and the results were good as shown in the table.

(Example 2) In Example 1, 2,6-diaminopyridine and 4,4 '
-The amount of diaminodiphenyl sulfone was 3.27 g (0.03 mo
l) and 17.39 g (0.07 mol) except that the same procedure as in Example 1 was carried out.

The polymer obtained had a reduced viscosity of 0.52 (0.5 g / dl NMP, 30
℃). The content of 2,6-diaminopyridine determined by proton NMR was 25 mol% with respect to the total amount of amines in the copolyamide. According to the method described above, the obtained polymer asymmetric membrane was manufactured, reverse osmosis experiment, and chlorine resistance test were conducted, and the results in the table were obtained.

(Examples 3 and 4) The same procedure as in Examples 1 and 2 was repeated except that 3,4'-diaminodiphenyl sulfone was used instead of 4,4'-diaminodiphenyl sulfone in Examples 1 and 2. .

The reduced viscosities of the obtained polymers are 0.60 and 0.50, respectively.
(0.5 g / dl NMP, 30 ° C). The 2,6-diaminopyridine content determined by proton NMR was 5,20 mol% based on the total amount of amines. Preparation of the resulting polymer asymmetric membrane, reverse osmosis experiment, according to the method described above,
And, the chlorination test was conducted and the results shown in the table were obtained.

(Examples 5 to 8) Examples 1 to 4 were performed in the same manner as Examples 1 to 4 except that terephthalic acid dichloride was used instead of isophthalic acid dichloride.

The reduced viscosity of the obtained polymer was as shown in the table. The content of 2,6-diaminopyridine determined by proton NMR was 5,18,7,15 mol%, respectively. According to the above-mentioned method, the obtained polymer asymmetric membrane was manufactured, reverse osmosis experiment and chlorine resistance test were conducted, and the results in the table were obtained.

(Example 9) In the same manner as in Example 2 except that a mixed acidic component of isophthalic acid dichloride and terephthalic acid dichloride (isophthalic acid dichloride amount = 50 mol%) was used in place of isophthalic acid dichloride. It was done.

The reduced viscosity of the obtained polymer was 0.55 (0.5 g / dl NMP, 30
℃). The content of 2,6-diaminopyridine determined by proton NMR was 23 mol% with respect to the total amount of amine. According to the method described above, the obtained polymer asymmetric membrane was subjected to a reverse osmosis test and a chlorine resistance test, and the results shown in the table were obtained.

(Example 10) In Example 6, except that an equimolar mixed diamine component of 3,3'-diaminodiphenyl sulfone and 4,4'-diaminodiphenyl sulfone was used in place of 4,4'-diaminodiphenyl sulfone. Were performed in the same manner as in Example 6. The obtained polymer yield was about 90%, and the reduced viscosity of the polymer was 0.63 (0.5 g / dl NMP, 30 ° C). The content of 2,6-diaminopyridine determined by proton NMR was 18% based on the total amount of amine.

According to the above-mentioned method, the production of the obtained polymer asymmetric membrane, the reverse osmosis experiment and the chlorine resistance test were conducted,
The results in the table were obtained.

(Examples 11 and 12) In Example 2, bis [4- (4-aminophenoxy) phenyl] sulfone (abbreviated as 4se) or bis [4- (3 was used instead of 4,4'-diaminodiphenylsulfone.
The same procedure as in Example 2 was repeated except that -aminophenoxy) phenyl] sulfone (abbreviated as 3se) was used.

The reduced viscosities of the obtained polymers are 0.78 and 0.69 (0.5 g
/ dl NMP, 30 ° C). Note that it was determined by proton NMR
The content of 2,6-diaminopyridine was 23 with respect to the total amount of amine.
And 25 mol%. According to the method described above, the obtained polymer asymmetric membrane was subjected to a reverse osmosis test and a chlorine resistance test, and the results shown in the table were obtained.

(Examples 13 and 14) In Example 6, bis [4- (4-aminophenoxy) phenyl] sulfone (abbreviated as 4se) or bis [4- (3) was used in place of 4,4'-diaminodiphenylsulfone.
The same procedure as in Example 6 was carried out except that -aminophenoxy) phenyl] sulfone (abbreviated as 3se) was used.

The reduced viscosities of the obtained polymers are 0.88 and 0.75 (0.5 g
/ dl NMP, 30 ° C). Note that it was determined by proton NMR
The content of 2,6-diaminopyridine in both copolyamides is
It was 25 mol% based on the total amount of amine. According to the method described above, the obtained polymer asymmetric membrane was subjected to a reverse osmosis test and a chlorine resistance test, and the results shown in the table were obtained.

In Table 1, I is isophthalic acid chloride, T is terephthalic acid chloride, 3s is 3,3'-diaminodiphenyl sulfone, 4s is 4,4'-diaminodiphenyl sulfone,
m is metaphenylenediamine, mp is 2,6-diaminopyridine, 4se is bis [4- (4-aminophenoxy) phenyl] sulfone, and 3se is bis [4- (3-aminophenoxy) phenyl] sulfone.

As shown in the table, the copolyamide of the present invention showed good solubility in N-methyl-2-pyrrolidone (NMP), and it was easy to prepare an asymmetric membrane from the solution. When the reverse osmosis performance and the chlorine resistance were evaluated using the asymmetric membrane, both showed better performance than the comparative example.

(Effect of the Invention) The copolyamide obtained by the present invention has excellent solubility in amide solvents, and the asymmetric membrane obtained from the solution exhibits excellent reverse osmosis performance and durability against oxidative chlorine.

Claims (2)

[Claims] 1. An aromatic diamine compound (A) having at least one diphenylsulfone unit and a pyridine ring-containing diamine compound (B), which is a mixture molar ratio (A) / (B) = 95/5. A permselective separation membrane comprising an aromatic copolyamide obtained by reacting an aromatic polycarboxylic acid component with a mixed diamine component of about 50/50. 2. The aromatic diamine compound (A) is 3,3'-diaminodiphenyl sulfone and / or 4,4'-diaminodiphenyl sulfone, and the pyridine ring-containing diamine compound (B) is 2,6-diaminopyridine. The selectively permeable separation membrane according to claim 1, characterized in that