JPH03232523A - Composite membrane - Google Patents

Abstract

PURPOSE:To easily obtain a composite membrane having chlorine resistance and compacting resistance and especially useful as a reverse osmotic membrane by forming an active layer of copolyamide consisting of specified components on the surface of a support layer of a porous base material. CONSTITUTION:An active layer of copolyamide is formed on the surface of a support layer of a porous base material to obtain a composite membrane having satisfactory separating performance. The copolyamide consists essentially of arom. diamine such as 4,4'-diaminobenzophenone, aliphatic diamine such as piperazine and arom. dicarboxylic acid such as isophthaloyl dichloride. The copolyamide is dissolved in a solvent and the resulting soln. is applied to or impregnated into the porous base material. The copolyamide is produced with the diamines and dicarboxylic acid by general soln. polymn. at a low temp.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a permselective membrane, particularly a composite membrane used as a reverse osmosis membrane, an ultrafiltration membrane, or the like.

(Prior Art) A membrane that can selectively permeate a specific component in a liquid mixture such as a solution, emulsion, or suspension and can separate the desired component from other components is called a permselective membrane. collectively called. Examples of selectively permeable membranes include reverse osmosis membranes (RO membranes) and ultrafiltration membranes (υF membranes).Reverse osmosis membranes are capable of separating molecules and ions with small molecular diameters, and are useful for desalination of seawater, It is used in the production of sterile water for pharmaceuticals, ultrapure water for the semiconductor industry, wastewater treatment, and food concentration. Ultrafiltration membranes can separate substances with relatively large molecular diameters such as colloids, proteins, microorganisms, and synthetic polymers from solutions or emulsions, and are used in the food industry, pharmaceutical industry, brewing,
It is used in purification or concentration operations in fields such as fermentation.

Such permselective membranes are usually membranes made of organic polymers with pores. Due to their structure, these films have (1)
A homogeneous membrane made of an organic polymer and having homogeneous and dense pores; (2) A membrane made of an organic polymer with a porous structure is used as a support, and a membrane made of a polymer of the same quality as the support and having dense pores is formed on the surface of the membrane. Asymmetric membrane in which a surface polymer layer with pores is formed; (2
) Using an organic porous membrane such as silica or alumina or an organic porous membrane such as polyethylene or polypropylene as a support, an organic polymer membrane having homogeneous and dense pores similar to (1) is formed on this surface. It is classified as a composite membrane;

Cellulose acetate, aromatic polyamide, and the like are commonly used as organic polymers for these membranes. A permselective membrane using cellulose acetate has excellent water permeation rate and solute removal rate, but is not sufficient in heat resistance, chemical resistance, organic solvent resistance, bacteria resistance, etc.

On the other hand, permselective membranes using aromatic polyamides are susceptible to oxidizing chlorine and lack chlorine resistance.

When the membrane is used as an RO membrane, high pressure is applied to the membrane. For example, desalination of seawater is carried out under high pressure of 50 kg 7 cm 2 or more. Therefore, it is necessary that there is no change in membrane performance under high pressure and that the membrane is less likely to be compacted, that is, that the membrane has excellent compaction resistance.

Hollow fiber membranes, which are asymmetric membranes made of a single material, have a large membrane area per module volume and can downsize the device. Furthermore, since it is made of a single material, it is less likely to contaminate the produced water, which is preferable.

However, modules made of hollow fiber membranes are susceptible to fouling due to their structure. Further, the consolidation resistance depends on the material of the membrane and the form of the membrane, and it is difficult to stably manufacture a membrane having a consolidation resistance above a certain value.

The inventors of the present application have disclosed Japanese Patent Application Laid-Open No. 62-213807, Japanese Patent Application Laid-open No. 62-244403, and Japanese Patent Application Laid-open No. 62-24.
No. 4404 describes a copolyamide consisting of an aromatic diamine, diaminodiphenylsulfone and/or its derivative; an aliphatic diamine, piperazine and/or its derivative; and isophthalic acid, terephthalic acid and/or a derivative thereof. We proposed a permselective membrane using a polymer.

Such copolyamides have excellent chlorine resistance, and hollow fiber membranes manufactured using such membrane materials have good RO membrane properties. However, this hollow fiber membrane had insufficient separation performance and compaction resistance.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to provide excellent chlorine resistance and consolidation resistance,
An object of the present invention is to provide a composite membrane useful as a permselective membrane, particularly as an R○ membrane.

(Means and effects for solving the problems) The composite membrane of the present invention is a composite membrane having a support layer made of a porous base material and an active layer formed on the surface of the support layer, the active layer contains a copolyamide whose constituent components are a diamine component mainly consisting of an aromatic diamine and an aliphatic diamine, and an aromatic dicarboxylic acid component, thereby achieving the above object.

Examples of the porous base material forming the support layer in the composite membrane of the present invention include polyester fibers, polyamide fibers, polyamideimide fibers, polyimide fibers, acrylic fibers,
A woven or nonwoven fabric sheet or tube made of organic fibers such as polypropylene fibers and polyethylene fibers; or inorganic fibers such as glass fibers and carbon fibers is used. Such a base material may be coated with an organic polymer compound such as polysulfone or polysulfone ether in advance. These base materials have pores with a pore diameter of 0.1 μm or more. Although the thickness of the base material is not particularly limited, it is preferably 300 μm or less.

As the aromatic diamine compound used in the copolymerized polyester which is the main component of the active layer of the composite membrane of the present invention, the following are used. 0-lm- or p-phenylenediamine, 1.3.5-phenylenediamine, 2
．． 4-diaminophenol, 3,5-diaminophenol, 0- or p-toluenediamine, 4-chloro-1
, 2-phenylenediamine, 5-C' 0-p-phenylenediamine, 4.5-dichlorophenylenediamine, 3.3-diaminodiphenylmethane, 4.4-diamino-3,3-dimethyldiphenylmethane, 4.4゜-Diamino-3,3°, 5,5-tetramethyldiphenylmethane, 4,4-diamino-3-ethyldiphenylmethane, 4,4-diamino-3,3'-diethyldiphenylmethane, 4,4-diamino-5,5' , 6.6-titramethyldiphenyl) 9 :/, 2.2'-his(3-aminophenyl)propane, 2,2°-bis(4-aminophenyl)propane, 4°4'-diaminodiphenylmethane, 4.4-diaminodibenzyl, 4.4'-methylenebis(2-chloroaniline), 4.4-diaminobenzophenone, 3,4-diaminodiphenyl ether, 2
, 4°-diaminodiphenyl ether, 4.4-diaminodiphenyl ether, 4° 4-diaminobenzanilide, 4.4-diaminobenzenesulfoanilide, 3.3
-diaminodiphenylsulfide, 4,4°-diaminodiphenylsulfide, 3.3-diaminodiphenylsulfone, 4.4°-diaminodiphenylsulfone, 3.
4-diaminodiphenylsulfone, 3.3°-dinitro-4,4-diaminodiphenylsulfone, 4.4°-diamino-3,3°-dihydroxydiphenylamine, 3
．． 3°-diamino-4,4°-dihydroxydiphenylamine, bis(4-(3-aminophenoxy)phenylcosulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 1,3-bis(4-amino phenoxy)benzene, 1.4-bis(4-aminophenoxy)benzene, 2.2-bis[4-(4-aminophenoxy)
phenyl]propane, 4.4°-bis(4-aminophenoxy)biphenyl, 2.2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and the like. In particular, 4,4-diaminobenzophenone, 4
．． 4°-Diaminobenzenesulfoanilide, 3,3-diaminodiphenylsulfide, 44°-diaminodiphenylsulfide, 3,3°-diaminodiphenylsulfone, 4,4-diaminodiphenylsulfone, 3,4°-
Diaminodiphenylsulfone, bis(4-(3-aminophenoxy)phenylcosulfone), and bis[4-(4-aminophenoxy)phenyl]sulfone are preferred from the viewpoint of polymer solubility.

Furthermore, 3.3'-diaminodiphenylsulfone, 4.
Diaminodiphenylsulfone or its derivatives such as 4-diaminodiphenylsulfone, 3.4°-diaminodiphenylsulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenylcosulfone) is preferred.

Two or more of these aromatic diamines may be used in combination.

In this case, the mixing ratio is not particularly limited.

Examples of aliphatic diamine compounds include ethylenediamine, 1
, 2-propylene diamine, 1,3-7' propylene diamine, diethylene triamine, triethylene tetramine, hexamethylene diamine, N,N-diethylethylene diamine, diaminodiethylene diamine; bis(aminopropyl) piperazine; 1
, 4-diaminocyclohexane, 1,3-diaminocyclohexane and other alicyclic polyamine compounds; homopiperazine, piperazine, 2-methylpiperazine, trans
-2,5-dimethylpiperazine, cis-2,5-dimethylpiperazine, 2.6-dimethylpiperazine, 2.3
．． 5-) Dimethylpiperazine, 2°2, 3.3.5.5
．． 6.6. -octamethylpiperazine, 2,2°5.
5-tetramethylpiperazine, 2.2.3.5.5.6
-beef samethylpiperazine, 2-ethylpiperazine, 2
．． 5-diethylpiperazine, 2,3.5-triethylpiperazine, 2.2.3.5.5.6-ethylbiperazine, 2,3°5.6-tetoethylbiperazine, 2-
Propylpiperazine, 2,6-dipropylpiperazine,
2,3.5-tripropylpiperazine, 2,3,5.6
-tetra-n-propylpiperazine, 2-butylpiperazine, 2,5-di-n-butylpiperazine, 2,5-di-tert-butylpiperazine, 2,3゜5-trif-n
-Butylpiperazine, 2-pentylpiperazine, 2-decylpiperazine, 2.5-divinylpiperazine, 2.5
-diphenylpiperazine, 2-phenylpiperazine, 2
, 3,5.6-titraphenylpiperazine, 2-naphthylpiperazine, 2,5-dinaphthylpiperazine, 2-tolylpiperazine, 2,5-ditolylpiperazine, 2,3
．． Examples include aliphatic cyclic polyamines such as 5.6-titratolylbiperazine and dipiperidylbroban. In particular, piperazine, 2-methylpiperazine
s-2,5-dimethylpiperazine is preferred; these diamine compounds improve the solubility of the copolyamide in amide and glycol solvents and facilitate the preparation of composite membranes. It is preferable to use these aliphatic diamine compounds alone. However, it is also possible to use a mixture of two or more types depending on the purpose of the membrane and the required properties.

The mixing ratio of the aromatic diamine compound and the aliphatic diamine compound is determined by the characteristics of the composite membrane as an RO membrane, the chemical properties,
and have a significant effect on physical properties. The mixing ratio is usually 95.5 to 50:50 in terms of molar ratio, and more preferably 90:1.
It is preferable that it is 0-60:40. Furthermore, in consideration of the solubility of the copolyamide in an amide solvent during the preparation of a composite membrane, it is preferable that the aliphatic cyclic diamine compound is contained in the total diamine compound in an amount of 5 to 60 mol%, and more preferably It is contained in an amount of 5 to 40 mol%. If the content of the aliphatic cyclic diamine compound is 60 mol% or more, the solubility of the obtained copolyamide in amide-based solvents or glycol-based solvents will decrease significantly, making it difficult to form a uniform and thin active layer in the composite membrane. , the performance of the membrane decreases.

Aromatic dicarboxylic acid components include 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-su7thalene dicarboxylic acid, 1.7-naphthalene dicarboxylic acid, 1.8
- Naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid and halides of these acids (e.g. chloride, bromide) are used. In particular, isophthalic acid dichloride or terephthalic acid dichloride,
It is preferably used from the viewpoint of solubility in aprotic amide solvents such as N-methylpyrrolidone and N,N-dimethylacetamide used in the preparation of copolyamides. Two or more of these aromatic polycarboxylic acids may be used in combination, and the mixing ratio thereof is not particularly limited.

Particularly preferably, the copolyamide contains 3,3- and/or 4,4-diaminodiphenylsulfone as aromatic diamine compound and aliphatic diamine compound.
piperazine, 2-methylpiperazine, and trans
At least one selected from -2,S-dimethylpiperazine is prepared using isophthalic acid dichloride and/or terephthalic acid dichloride as an aromatic dicarboxylic acid compound.

The copolyamide is prepared by a common low temperature solution polymerization method using the diamine component and dicarboxylic acid component described above. For example, equimolar amounts of the mixed diamine component of the above-mentioned aromatic diamine and aliphatic diamine and an aromatic dicarboxylic acid component (preferably aromatic dicarboxylic acid dichloride) are dissolved in an appropriate solvent, and the mixture is heated to a temperature below 50°C. Polymerize at a temperature of As a solvent, N,N-dimethylacetamide,
Aprotic amide solvents such as N-methyl-2-pyrrolidone are preferred. The obtained copolyamide is
A solution of 0.5 g/d I of N-methyl-2-pyrrolidone at 30'C is 0.5 to 2.01, especially 0.5 to 1
．． Preferably, it has a reduced viscosity of 5.5. A more preferable reduced viscosity is 0.6 to 1.0. Reduced viscosity is 0.
If the reduced viscosity is 5 or less, the film-forming ability of the copolyamide decreases, making it impossible to form an active layer on a porous substrate. The viscosity of the solution in which the polyamide is dissolved becomes high, making it difficult to uniformly apply or soak the copolyamide solution onto the substrate, and the performance of the composite membrane deteriorates.

The method for manufacturing the composite membrane of the present invention will be described below.

First, a film-forming solution containing the copolyamide, its solvent, and optionally a non-solvent and a metal salt is prepared, and the porous base material is coated with or impregnated with this. As a method for applying the film-forming liquid, any method known to those skilled in the art can be used, such as roll coating, spray casting, application using a bob, and mechanical extrusion application. Non-solvent is
The copolyamide acts as a pore-forming agent when forming the active layer, and the metal salt makes the pore structure of the active layer dense and uniform.

As the solvent for the above copolyamide, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and 2-pyrrolidone are used. Others: 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, dimethyl sulfoxide, tetraethylene glycol, molecule ff1200
The above polyethylene glycols, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, etc. can also be used. It is also possible to use a mixture of two or more of these solvents in an appropriate ratio, or to use a mixture with another alcoholic solvent. However, considering the solubility of the copolyamide, it is preferable that 50% by weight or more of the solvent is an amide solvent. In particular, N,N-dimethylacetamide and N
The mixed solvent with -methyl-2-pyrrolidone improves the water permeability and salt removal properties of the membrane, providing a membrane suitable as an RO membrane. If a polymer soluble in amide solvents such as polysulfone or polysulfone ether is used as the porous substrate, tetraethylene glycol, molecule 120
0 or more polyethylene glycol, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether,
Preferably, a glycol solvent such as triethylene glycol monoethyl ether is used.

As the non-solvent for the copolyamide contained in the film forming solution, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol and its derivatives, glycerin, polyglycerin and its derivatives, etc. are used. Among the above-mentioned non-solvents, polyglycerin is preferred because it improves the water permeability and salt removability of the membrane. The number average molecular weight of polyglycerin is preferably 200 to too much, and furthermore, by using polyglycerin having a number average molecular weight of 250 to 750, a membrane with a high salt removal rate can be obtained. When polyglycerin with a molecular weight of 1000 or more is used, it is difficult to remove the polyglycerin from the active layer afterwards, thereby increasing the plasticity of the resulting membrane. Furthermore, undesirable properties as a membrane occur, such as susceptibility to thermal decomposition. On the other hand, if the molecular weight is less than 200, sufficient pores will not be formed in the active layer, making it impossible to obtain good RO membrane properties. Two or more types of polyglycerin having different number average molecular weights may be used as a mixture.It is preferable that 50% by weight or more of the non-solvent is polyglycerin or a derivative thereof.Polyglycerin is a poor solvent for copolyamide. It may also be used in combination with an alcohol or glycol solvent.Commercially available polyglycerin usually contains about 10% water.When using polyglycerin containing water, the active layer contains It is not possible to provide a good pore structure and the pressure resistance of the membrane is reduced.Therefore, it is preferable that the water content of polyglycerin is 1% or less.

The amount of non-solvent added depends on the type and amount of organic and inorganic compounds contained in the film forming solution, but is usually 5 to 40% by weight, preferably 10 to 20% by weight based on the copolyamide.
It is. If the amount of the non-solvent is 40% by weight or more, the copolyamide phase separates in the membrane forming solution, the system tends to become non-uniform, and a good active layer cannot be obtained.

Furthermore, the number of cavities in the active layer increases, and the pressure resistance of the membrane decreases significantly.

In order to further improve the pore structure of the active layer, the membrane forming solution contains:
Metal salts may also be added. As metal salts, alkali metal salts or alkaline earth metal salts are used. Alkali metal salts include chlorides, bromides, nitrates, acetates, and sulfates of lithium, sodium, or potassium. In particular, chlorides of these alkali metals or chlorides are preferred because they have excellent hydrate power, solubility in membrane forming solutions, and stability at high temperatures. When using an amide solvent, lithium chloride or a hydrate such as lithium chloride l-hydrate is preferably used. Alkaline earth metal salts include magnesium or calcium chlorides, bromides, nitrates, acetates, and the like. In particular, magnesium chloride and calcium chloride are preferred from the viewpoint of solubility in the membrane forming solution and stability. Hydrates such as magnesium chloride hexahydrate, calcium chloride dihydrate, and calcium chloride hexahydrate are also preferred.

The amount of these metal salts added depends on the type of salt, the type of solvent, and the desired performance of the membrane.

Preferably, the weight of the copolyamide is not more than 10% by weight. To improve the solubility of the metal salt, a small amount of water may be added to the membrane-forming solution, for example up to 10% by weight of the membrane-forming solution. The water added here also functions to adjust the porosity of the active layer.

The above ingredients are mixed at room temperature for 20 minutes under an inert atmosphere such as nitrogen.
A film forming solution is prepared by mixing and stirring at 00'C, preferably 50 to 150C. This film-forming solution was used under the above conditions for 2 to 1
It is preferable to stir for 6 hours to obtain a uniform dispersion. However, at high temperatures of 150° C. or higher, the copolyamide and solvent are likely to decompose (so it is necessary to shorten the stirring time).

The amount of copolyamide in the film-forming solution is preferably 10 to 35% by weight, particularly 20 to 30% by weight, based on the total weight of the film-forming solution.If it is 35% by weight or more, the viscosity of the film-forming solution increases If the amount is too high and below 10% by weight, it will be difficult to form an active layer.

After the obtained film-forming solution is sufficiently defoamed under reduced pressure, it is uniformly applied or impregnated onto a porous substrate. Application of such a film-forming liquid is generally performed in the atmosphere. However, it is also possible to control the RO membrane properties of the active layer by mixing alcohol or glycol compound vapor or water vapor into the atmosphere in an inert atmosphere such as nitrogen, helium, or argon. At this time, it is also preferable to heat the atmosphere to room temperature or higher. The temperature of the atmosphere depends on the temperature of the solvent in the film forming solution, but is preferably below the boiling point of the solvent, preferably 40 to
The temperature is 120°C.

The base material to which the film-forming solution has been applied as described above is heated to evaporate an appropriate amount of the solvent to form an active layer on the base material. The thickness of this active layer is preferably 0.01 to 50 μm. The heating temperature depends on the type of solvent, but N,
When using N-dimethylacetamide, 100 to 1
The temperature is 50°C, preferably 100-120°C. The heating time depends on the heating temperature, but is 5 to 30 minutes in the temperature range of 100 to 120°C.

Furthermore, the base material on which the active layer is formed is immersed in a poor solvent (gelling solvent) for the copolyamide to coagulate the copolyamide. As a result, the copolyamide of the active layer has a uniform and dense structure, and exhibits excellent RO membrane properties. When the thickness of the active layer is greater than 1 μl, only the surface of the active layer has a dense structure, and the active layer takes the form of an asymmetric membrane. In this case, the actual active layer is about 1 μl on the surface of the active layer. The gelling solvent used here is water or alcohol. Furthermore, a mixed solvent in which an amide solvent such as N,N-dimethylacetamide is added to water is also preferably used. The type of gelling solvent and the immersion temperature have a large effect on the RO membrane properties of the resulting composite membrane.

For example, when using a mixed solvent of water and N,N-dimethylacetamide, 0 to 30°C, preferably 0 to 15°C.
It is preferable to immerse at a temperature of .

Subsequently, the resulting composite membrane is washed with water or immersed in water to remove any solvent, nonsolvent, or metal salt remaining in the active layer. The water temperature at this time is preferably 0 to 40°C.

Furthermore, by heat-treating the composite membrane in water; an aqueous solution of an organic compound such as methanol or ethanol; or an aqueous solution of an inorganic compound such as sodium chloride, potassium chloride, magnesium chloride, or calcium chloride,
The RO membrane properties and compaction resistance of the membrane are improved. The temperature of the water or aqueous solution at this time is preferably 30 to 100°C.

The heating time depends on the heating temperature; at low temperatures of 30 to 50 degrees Celsius, it will take more than 12 hours, and at high temperatures around 100 degrees Celsius, it will take 30 hours.
About a minute is preferable.

The composite membrane thus obtained is used as a permselective membrane by being modularized by forming it into a tubular, seaweed-shaped, or pleated shape by any method.

As described above, the composite membrane of the present invention has an active layer having a uniform and dense micropore structure formed on the surface of the support layer made of a porous base material, and has excellent permselectivity and RO membrane, U
It is suitable as a permselective membrane such as an F membrane. In particular, the composite membrane of the present invention has excellent water permeability, salt removability, and compaction resistance, and is suitably used as an RO membrane.

In this way, the composite membrane of the present invention can be used as an RO membrane for desalination of seawater, production of sterile water for pharmaceuticals, production of ultrapure water for the semiconductor industry, wastewater treatment, food concentration, etc.: UF membrane It can be used in fields such as food industry, pharmaceutical industry, brewing, and fermentation.

(Examples) Examples of the present invention will be described below, but the present invention is not limited to these Examples.

The reduced viscosity of the copolyamide, the separation performance of the composite membrane, and the compaction resistance were evaluated by the following methods.

(1) Measurement of reduced viscosity The reduced viscosity was measured under the following conditions.

Solvent 2N-methyl-2-pyrrolidone (manufactured by Mitsubishi Kasei ■) Solution concentration: 0.5g polymer/dl Solvent measurement temperature: 30
°C Viscosity tube: Ubbelohde viscosity tube (2) Separation performance evaluation Using a flat membrane reverse osmosis performance continuous evaluation device, under the following conditions:
The water permeation rate and salt removal rate of the membrane were measured.

Supply liquid: 3.5% saline Supply pressure: 55 kg/am2 Supply liquid temperature = 25°C Recovery rate: 5% or less The amount of liquid permeated for 3 minutes 2 hours after the start of measurement was defined as the water permeation rate. The salt removal rate was determined from the salt concentrations of the feed solution and permeate solution according to the following formula. The salt concentration of the canned liquid was determined by a conventional method using a conductivity meter.

p Salt removal rate (%)-(L--)XIQOr In the formula, cp represents the salt concentration in the permeate, and Cf represents the salt concentration in the feed liquid.

(3) Evaluation of consolidation resistance After heat treating the composite membrane in 80°C warm water for 20 minutes, (2
Reverse osmosis performance was evaluated under the same conditions as in section ). and,
The water permeation rate 2 hours after the start of measurement is PR+, the water permeation rate after that time is FRt, and the consolidation coefficient m obtained from the following formula is:
The compaction resistance of the membrane was evaluated. Evaluation time (1) is approximately 100
It's time.

FRt/FR1''(t/2)-'' The closer the m value is to 0, the better the consolidation resistance of the membrane is. Practically speaking, m is preferably 0.03 or less.

Fire 1''■1 (A) Preparation of copolyamide Into a 5oox reaction vessel equipped with a nitrogen inlet tube, a thermometer and a stirrer, under a nitrogen stream, 5°375k of anhydrous piperazine was added.
g (62.4 mol) and 61.97 kg (249.6 mol) of 4,4°-diaminodiphenylsulfone. Subsequently, 50 kg of pyridine (6
24 mol), N-methylpyrrolidone 47 as reaction solvent
Add 01 and stir thoroughly to make a homogeneous solution. After cooling this solution to about 5°C, isophthalic acid dichloride 6
3.342 kg (312 mol) was added to start the polycondensation reaction.

The polymerization was completed by stirring at a low temperature of about 5° C. for about 30 minutes and then at room temperature for about 30 minutes.

After the reaction is complete, the reaction solution is poured into too much water to precipitate the polymer. Next, the resulting polymer is pulverized and the pulverized product is washed four times with pure water to remove the components in the polymer. Unreacted substances, solvent, etc. were removed. Approximately 80 to 10
The polymer was dried with hot air at 0''C for about 48 hours. The yield of the obtained polymer was almost 100%. The reduced viscosity (ηsp/C) was 1.15.

(B) Preparation of composite membrane 20 parts by weight of the copolyamide prepared above, 78 parts by weight of N,N-dimethylacetamide, and 2 parts by weight of lithium chloride were mixed to prepare a membrane forming solution. This film-forming solution was applied to a polyester woven fabric as a porous substrate at room temperature. At this time, the thickness of the film-forming solution after being cast was about 300 μm. The film coated with this film forming solution was placed in a hot air dryer at 110'C and left to dry for 10 minutes. Next, this membrane was placed in water (gelling solvent) at 25° C. and left for 2 hours to obtain a composite membrane of the present invention. Furthermore, this composite membrane was
Heat treatment was performed by immersing the sample in water at ℃ for about 20 minutes.

The results of evaluating the separation performance and compaction resistance of the obtained composite membrane are shown in the table below. The table below also shows the results for the composite membranes obtained in Examples 2 to 6 below. From the table, it can be seen that the composite membrane obtained here has excellent RO membrane properties.

Except that ice water at 0.5°C was used as the main gelling solvent for L-dish.
A composite membrane was obtained in the same manner as in Example 1. The obtained composite membrane showed excellent separation performance and compaction resistance.

A composite membrane was obtained in the same manner as in Example 1, except that a 45% N,N-dimethylacetamide aqueous solution was used as the gelling solvent. The obtained composite membrane showed excellent separation performance and compaction resistance.

Preparation of Togarashi Takumi Do (A) Copolyamide As a copolymerization monomer, 8.062 g of anhydrous piperazine was added to
The copolyamide was prepared in the same manner as in Example 1, except that 54.23 kg (218.4 mol) of 4,4-diaminodiphenylsulfone and 63.3 kg (312 mol) of terephthalic acid dichloride were used. I got it. The yield and reduced viscosity of the obtained copolyamide were 99% and 0.79, respectively.

(B) Preparation of composite membrane 20 parts by weight of the copolyamide prepared above, 76.5 parts by weight of N,N-dimethylacetamide, 2 parts by weight of anhydrous polyglycerin (number average molecular weight 480, manufactured by Itamoto Yakuhin ■) and calcium chloride. A composite membrane was obtained in the same manner as in Example 1, except that 1.5 parts by weight of hexahydrate was mixed to prepare a membrane forming solution.

The obtained composite membrane showed excellent separation performance and compaction resistance.

Except for using ice water at 0.5°C as the gelation solvent,
A composite membrane was obtained in the same manner as in Example 4. The obtained composite membrane showed excellent separation performance and compaction resistance.

A composite membrane was obtained in the same manner as in Example 4, except that a 45% N,N-dimethylacetamide aqueous solution was used as the gelation solvent. The obtained composite membrane showed excellent separation performance and compaction resistance.

A membrane-forming solution similar to that used in Example 1 was extruded from a nozzle at 110° C. and gelatinized by immersing it in water at 5° C. to obtain a hollow fiber membrane. This hollow fiber membrane is inferior to the composite membrane of the present invention in both separation performance and compaction resistance.

A hollow fiber membrane was obtained by extruding the same membrane forming solution as in Example 2 through a nozzle at 110°C and immersing it in water at 5°C to gel it. Compared to the composite membrane of the present invention, this hollow fiber membrane has
Both separation performance and consolidation resistance are poor.

(The following is a blank space) (Effects of the Invention) The composite membrane of the present invention has such a high salt removal rate and water permeability, has excellent consolidation resistance, and is suitably used as a reverse osmosis membrane. Furthermore, since the composite membrane of the present invention has excellent separation performance and pressure resistance, it can be suitably used as a permselective membrane such as an ultrafiltration membrane.

that's all

Claims (1)

[Claims] 1. A composite membrane having a support layer made of a porous base material and an active layer formed on the surface of the support layer, the active layer comprising:
A composite membrane containing a copolyamide whose constituent components are a diamine component mainly consisting of an aromatic diamine and an aliphatic diamine, and an aromatic dicarboxylic acid component.