JPH0530491B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of the Invention] The present invention relates to a novel aromatic polyimide semipermeable membrane and a method for manufacturing the same. [Background of the Invention] Conventionally, membranes made of polysulfone or polyethersulfone have been known as semipermeable membranes used in ultrafiltration or reverse osmosis. In recent years, ultrafiltration membranes have been widely used for applications such as concentration and purification in the food industry, and pyrogen-free water production in the pharmaceutical industry, and
A membrane that can be heat sterilized at a temperature of . However, the above-mentioned semipermeable membranes have excellent performance in water permeability and fractionation, hot water resistance,
PH resistance, organic solvent resistance, etc. are not sufficient. On the other hand, semipermeable membranes made of aromatic polyimide have been known as semipermeable membranes with excellent heat resistance and organic solvent resistance. Semipermeable membranes made of aromatic polyimide have excellent properties as mentioned above, but on the other hand, there are problems in that it is difficult to manufacture semipermeable membranes with stable quality, and the water permeation rate is not sufficient for practical use. There was a problem that I couldn't. As a countermeasure to this problem, Japanese Patent Publication No. 61-53089 discloses that a metal salt or a metal complex compound is added to a dope solution containing an aromatic polyimide consisting of biphenyltetracarboxylic acid and diaminodiphenyl ether. A method for manufacturing an aromatic polyimide semipermeable membrane from a prepared dope is disclosed. [Object of the Invention] An object of the present invention is to provide a semipermeable membrane made of aromatic polyimide and a method for producing the same. A particular object of the present invention is to provide an aromatic polyimide semipermeable membrane that has sufficient hot water resistance for heat sterilization and excellent water permeability and fractionability, and a method for producing the same. [Summary of the Invention] The present invention provides an aromatic tetracarboxylic acid component comprising at least 50 mol % of a biphenyltetracarboxylic acid component; (However, n is 1 or 2) It is made of an aromatic polyimide formed from an aromatic diamine component containing at least 50 mol% ^of a bis(aminophenoxy) compound represented by It consists of an aromatic polyimide semi-permeable membrane characterized by a ^m2 -day-Kg/ ^cm2 or more. The aromatic polyimide semipermeable membrane described above comprises (a) an aromatic tetracarboxylic acid component comprising at least 50 mol% of a biphenyltetracarboxylic acid component, and a general formula []: (However, n is 1 or 2) An aromatic polyimide formed from an aromatic diamine component containing at least 50 mol% of a bis(aminophenoxy) compound represented by; (b) a phenolic solvent; and (c) the above 5-100 for the amount of aromatic polyimide
A semipermeable aromatic polyimide characterized by forming a liquid thin film of a solution of a polyimide composition comprising a swelling agent consisting of glycol or its derivative in an amount of % by weight, and then solidifying the liquid thin film by immersing it in a coagulating liquid. It can be advantageously manufactured using a membrane manufacturing method. [Detailed Description of the Invention] The semipermeable membrane of the present invention comprises an aromatic tetracarboxylic acid component containing a biphenyltetracarboxylic acid component as a main component, and a general formula []: (However, n is 1 or 2.) This is a novel semipermeable membrane mainly composed of an aromatic polyimide formed from an aromatic diamine component containing at least 50 mol% of a bis(aminophenoxy) compound represented by: The biphenyltetracarboxylic acid component used in the present invention includes 3,3',4,4'-biphenyltetracarboxylic acid and 2,3,3',4'-biphenyltetracarboxylic acid, or lower versions thereof. Examples include alcohol esters, halogen salts, and acid dianhydrides, including 3,3',4,4'-biphenyltetracarboxylic dianhydride or 2,3,
Particularly preferred is 3',4'-biphenyltetracarboxylic dianhydride. The aromatic tetracarboxylic acid component used in this invention may contain other aromatic tetracarboxylic acid components in addition to the above biphenyltetracarboxylic acid component. At this time, the aromatic tetracarboxylic acid component preferably contains at least 50 mol% or more, particularly 80 to 100 mol%, of a biphenyltetracarboxylic acid component. If the biphenyltetracarboxylic acid component is less than 50 mol%, various properties such as heat resistance of the formed polyimide will decrease.
Undesirable. In the present invention, other aromatic tetracarboxylic acid components that can be used together with the biphenyltetracarboxylic acid component include benzophenonetetracarboxylic acid, pyromellitic acid, diphenyl ethertetracarboxylic acid, and 2,2-bis[4- Examples include (dicarboxyphenoxy)phenyl]propane, lower alcohol esters thereof, halogen salts, and acid dianhydrides. The aromatic diamine component used in the present invention contains at least 50 mol% of the bis(aminophenoxy) compound represented by the general formula []. Representative examples of bis(aminophenoxy) compounds represented by the general formula [ ] include 1,4-bis(4-aminophenoxy)benzene and 4,
Mention may be made of 4'-bis(4-aminophenoxy)diphenyl ether. The aromatic diamine represented by the general formula [], that is, the bis(aminophenoxy) compound, can be used in combination with other aromatic diamines. Examples of such aromatic diamines include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 2,2-bis(4-aminophenyl). ) propane, 2,2-bis[4-(4-aminophenoxy)
phenyl]propane, o-, m-, p-phenylenediamine, 3,5-diaminobenzoic acid, 2,6
-diaminopyridine, o-tolidine, 1,4-bis(4-aminophenoxy)benzene, bis[4
-(4-aminophenoxy)phenyl]sulfone,
and 3,7-diamino-2,8-dimethyl-diphenylene sulfone.
Such aromatic diamines used in combination include:
4,4'-diaminodiphenyl ether is particularly preferred. The semipermeable membrane of the present invention can be obtained from an aromatic polyimide formed by polymerizing and imidizing the above-mentioned aromatic tetracarboxylic acid component and aromatic diamine component. That is, a solution of an aromatic polyimide composition in which an aromatic polyimide consisting of the above-mentioned aromatic tetracarboxylic acid component and an aromatic diamine component and a specific swelling agent are uniformly dissolved in a phenolic solvent is used as a film-forming dope solution. The aromatic polyimide semipermeable membrane of the present invention can be easily produced by using the aromatic polyimide semipermeable membrane of the present invention. The above-mentioned phenolic solvent is a solvent whose main component is a phenolic compound, and preferably a solvent that is 100% phenolic compound. It may be a mixed solvent containing 50% by weight or less, especially 30% by weight or less of a solvent such as carbon disulfide, dichloromethane, trichloromethane, nitrobenzene, o-dichlorobenzene, etc. Suitable phenolic compounds used in the production method of the present invention are those having a melting point of 100°C or lower, preferably 80°C or lower, and a boiling point of 300°C or lower, preferably 280°C or lower at normal pressure. For example, phenol, o-, m-, p-
Suitable examples include cresol, 3,5-xylenol, and halogenated phenols in which hydrogen in the benzene nucleus of monovalent phenol is replaced with halogen. Examples of the above halogenated phenols include:
3-chlorophenol, 4-chlorophenol (sometimes abbreviated as p-chlorophenol, PCP), 3-bromophenol, 4-bromophenol, 2-chloro-4-hydroxytoluene,
2-chloro-5-hydroxytoluene, 3-chloro-6-hydroxytoluene, 4-chloro-2-
Hydroxytoluene, 2-bromo-5-hydroxytoluene, 3-bromo-5-hydroxytoluene, 3-bromo-6-hydroxytoluene, 4-
Examples include bromo-2-hydroxytoluene. The film-forming dope solution may be prepared by polymerizing and imidizing the above-mentioned aromatic tetracarboxylic acid component and aromatic diamine component in the above-mentioned solvent, or by preparing a suitable aromatic polyimide powder consisting of the above-mentioned components. It can also be prepared by dissolving it in the above solvent. In the film-forming dope solution, the concentration of aromatic polyimide is preferably 5 to 30% by weight, more preferably 8 to 20% by weight. The swelling agent is a glycol or a derivative thereof, and can be added at any time before or after polymerization and imidization. As the above swelling agent, glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, glycerin, or polymers and oligomers thereof Examples include glycol compounds such as and derivatives, but polyethylene glycol is preferred. The average molecular weight of the polyethylene glycol is preferably 200 to 20,000, more preferably 600 to 1,000. In the production method of the present invention, the amount of the swelling agent used is preferably 5 to 100% by weight, more preferably 20 to 60% by weight of the aromatic polyimide contained in the above dope. The semipermeable membrane of the present invention can be manufactured using the above-mentioned dope according to a known membrane forming method. Examples of the method for manufacturing the semipermeable membrane of the present invention include the following methods. The above-mentioned aromatic tetracarboxylic acid component and aromatic diamine component are polymerized and imidized in one step in p-chlorophenol at a temperature of 140°C or higher in approximately equimolar amounts to obtain a solution of an aromatic polyimide composition,
The above-mentioned swelling agent is added to this to obtain a film-forming dope. Then, the dope solution is cast onto the surface of a flat substrate with a smooth surface, and a thin film of uniform thickness is formed using a doctor blade; the dope solution is supplied onto the surface of a roll with a smooth outer peripheral surface. A method in which a thin film is formed by casting to a uniform thickness with a doctor knife provided close to the roll surface; Alternatively, the above dope liquid is extruded into a thin film from a T-die and wound around the roll surface to form a thin film. Formation method: Form a liquid thin film in various shapes such as a flat film or a hollow fiber from a dope solution by a method such as forming a hollow fiber from a hollow fiber spinning nozzle, and then immerse the thin film in a coagulation bath. and solidify. The coagulation bath may be any solvent that is compatible with the above-mentioned phenolic solvent and in which polyimide is insoluble, such as water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, or water. Examples include mixed solvents of ethanol and these organic solvents, but pure ethanol or ethanol
An aqueous solution of 30% by volume or more can be suitably used. The thin film produced by the above method consists of a dense layer and a porous layer, and already has sufficient properties as a semipermeable membrane. It is desirable to wash away residual solvent. Furthermore, if necessary, the molecular structure may be stabilized by treatment in hot water before use. [Effects of the Invention] The aromatic polyimide semipermeable membrane of the present invention is easy to manufacture as a semipermeable membrane with stable quality, and has excellent not only hot water resistance but also especially water permeability, so it is widely used in the food industry. It can be suitably used in fields where semipermeable membranes need to be periodically heat sterilized, such as in the pharmaceutical industry. Furthermore, since the manufacturing method of the present invention uses a glycol compound that does not dissolve aromatic polyimide as a swelling agent, the semipermeable membrane has significantly improved fractionation properties compared to conventional polyimide semipermeable membranes. can be obtained. Next, Examples and Comparative Examples of the present invention will be shown. Example 1 A nitrogen inlet pipe, a stirrer and a water drain pipe were attached.
3, 3', 4, in a 300ml three-necked separable flask.
30 mmol (8.8266 g) of 4'-biphenyltetracarboxylic dianhydride (hereinafter abbreviated as s-BPDA) and 30 mmol (8.8266 g) of 1,4-bis(4-aminophenoxy)benzene (hereinafter abbreviated as BAPB).
Millimoles (8.7690 g), 148.6 g of p-chlorophenol (hereinafter abbreviated as PCP), and 9.9 g (60% by weight of polyimide) of polyethylene glycol with an average molecular weight of 600 were prepared and heated in an oil bath at 180°C for 3 hours. , stirred, and polymerized to obtain a reddish-brown, transparent, and viscous polyimide solution. After filtering this polyimide solution under pressure, it was left to stand at 100 to 120°C for 3 hours to defoam.
It was used as a dope liquid. Casting the above dope solution onto a clean glass plate,
A 0.2 mm thick liquid thin film was formed using a doctor blade. The liquid thin film was dried in a dust-free oven at 60° C. for 5 minutes, then immersed in a coagulation bath (ethanol) at room temperature and left overnight. The completely coagulated thin film was washed several times with ethanol and then with water, and then heat-treated in boiling water for 4 hours to obtain a semipermeable film. The semipermeable membrane was immersed in hot water at 150°C in an autoclave, and the change in water permeability before and after the heat treatment was examined to evaluate hot water resistance.
The hot water resistance was measured in three ways: when the semipermeable membrane was held in the hot water for 4 hours, for 8 hours, and for 15 hours. Water permeability was measured by attaching the above semipermeable membrane to a batch type cell and applying pure water and 0.2% by weight of polyethylene glycol with an average molecular weight of 20,000 under a pressure of 1Kg/ ^cm2 .
This was carried out using an aqueous solution. The results are shown in Table 1. Further, the semipermeable membrane was treated in hot water at 200°C for 4 hours, and the tensile strength and elongation at break of the semipermeable membrane were measured, and the retention rates are shown in Table 1. Example 2 30 mmol of s-BPDA, 24 mmol (7.0161 g) of BAPA, 6 mmol (1.2014 g) of 4,4'-diaminodiphenyl ether (hereinafter abbreviated as DADE), 143.7 g of PCP, average molecular weight 600
A semipermeable membrane was obtained in the same manner as in Example 1, except that 6.39 g of polyethylene glycol (40% by weight of polyimide) was used and coagulated by immersion in a 60% by volume ethanol aqueous solution. The hot water resistance of the semipermeable membrane was evaluated in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 1 A dope solution consisting of 20 parts by weight of polysulfone (manufactured by UCC, Udel P1800), 40 parts by weight of diethylene glycol, and 80 parts by weight of N-methyl-2-pyrrolidone,
It was cast onto a clean glass plate, and a 0.2 mm thick liquid thin film was formed using a doctor blade. The liquid thin film was dried for 30 seconds in a dust-free oven at room temperature, then immersed in a coagulation bath (ice water) and left for 24 hours to obtain a semipermeable film. The hot water resistance of the semipermeable membrane was evaluated in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 A liquid thin film was formed in the same manner as Comparative Example 2 except that polyethersulfone (Victrex 200P, manufactured by ICI) was used instead of polysulfone, and the liquid thin film was placed in a dust-free oven at room temperature for 1 minute. Then, the temperature was raised to 60°C and dried for 5 minutes, then immersed in a coagulation bath (ice water) and left for 24 hours to obtain a semipermeable membrane. The hot water resistance of the semipermeable membrane was evaluated in the same manner as in Example 1. However, the semipermeable membranes treated for 8 hours and 15 hours could not be measured because they deteriorated. The results are shown in Table 1.

[Table] Example 3 30 mmol of s-BPDA, 30 mmol of BAPB, 148.6 g of PCP, 6.60 g of polyethylene glycol with an average molecular weight of 600 (40% by weight of polyimide)
An aromatic polyimide semipermeable membrane was obtained in the same manner as in Example 1, except that the liquid thin membrane was immersed in a 60% by volume aqueous ethanol solution at 0° C. and solidified without drying. The water permeability of the semipermeable membrane was measured. To measure water permeability, the above semipermeable membrane was attached to ^a batch type cell, and pure water and average molecular weight
The experiment was carried out using a 0.2% by weight aqueous solution of polyethylene glycol 20,000. The results are shown in Table 2. Example 4 30 mmol of s-BPDA, 30 mmol of BAPB, 148.6 g of PCP, 6.60 g of polyethylene glycol with an average molecular weight of 600 (40% by weight of polyimide)
An aromatic polyimide semipermeable membrane was obtained in the same manner as in Example 3, except that the liquid thin membrane was immersed in a 50% by volume ethanol aqueous solution at 0° C. to solidify without drying. The water permeability of the above semipermeable membrane was measured in the same manner as in Example 3. The results are shown in Table 2. Example 5 30 mmol of s-BPDA, 30 mmol of BAPB, 148.6 g of PCP, 8.25 g of polyethylene glycol with an average molecular weight of 600 (50% by weight of polyimide)
An aromatic polyimide semipermeable membrane was obtained in the same manner as in Example 3, except that the liquid thin membrane was immersed in a 50% by volume ethanol aqueous solution at 0° C. to solidify without drying. The water permeability of the above semipermeable membrane was measured in the same manner as in Example 3. The results are shown in Table 2. Example 6 After drying the liquid thin film produced in Example 5 for 5 minutes in a dust-free oven at 60°C, an aromatic polyimide semipermeable membrane was prepared in the same manner as in Example 5, except that it was immersed in a coagulation bath. Obtained. The water permeability of the above semipermeable membrane was measured in the same manner as in Example 3. The results are shown in Table 2. Example 7 The water permeability of the aromatic polyimide semipermeable membrane produced in Example 1 was measured in the same manner as in Example 3. The results are shown in Table 2. Comparative Example 3 Commercially available polysulfone semipermeable membrane (ULVAC ST-15 manufactured by Albac Service Co., Ltd., molecular weight cut off 20000)
The water permeability was measured in the same manner as in Example 3. The results are shown in Table 2.

[Table] Example 8 3 mmol of s-BPDA, 27 mmol of BAPB (7.8931 g), 3 mmol of DADE (0.6007 g)
g), aromatic polyimide was prepared in the same manner as in Example 1, except that 146.2 g of PCP and 6.50 g of polyethylene glycol (40% by weight of the polyimide) with an average molecular weight of 600 were used, and the liquid thin film was coagulated without drying. A semipermeable membrane was obtained. The water permeability of the above semipermeable membrane was measured in the same manner as in Example 3. The results are shown in Table 3. Example 9 3 mmol of s-BPDA, 24 mmol of BAPB, 6 mmol of DADE, 143.7 g of PCP, and
Polyethylene glycol with an average molecular weight of 600 is 6.39
An aromatic polyimide semi-permeable membrane was obtained in the same manner as in Example 8, except that g (40% by weight of polyimide) was used. The water permeability of the above semipermeable membrane was measured in the same manner as in Example 3, and the results are shown in Table 3. Further, the semipermeable membrane was treated in hot water at 250°C for 4 hours, and the tensile strength and elongation at break of the semipermeable membrane were measured, and the retention rates are shown in Table 3. Comparative Example 4 Same as Example 8 except that 30 mmol of s-BPDA, 3 mmol (6.0072 g) of DADE, 124.0 g of PCP, and 6.9 g of polyethylene glycol (50% by weight of polyimide) having an average molecular weight of 1000 were used. Similarly, an aromatic polyimide semipermeable membrane was obtained. The water permeability of the above semipermeable membrane was measured in the same manner as in Example 3, and the results are shown in Table 3. Further, the semipermeable membrane was treated in hot water at 250°C for 4 hours, and the tensile strength and elongation at break of the semipermeable membrane were measured, and the retention rates are shown in Table 3.

[Table] Comparative example
4-100 2.1
1.5 17 53 3

Claims (1)

[Scope of Claims] 1. An aromatic tetracarboxylic acid component comprising at least 50 mol% of a biphenyltetracarboxylic acid component, and the general formula []: (However, n is 1 or 2) It is made of an aromatic polyimide formed from an aromatic diamine component containing at least 50 mol% ^of a bis(aminophenoxy) compound represented by An aromatic polyimide semipermeable membrane characterized in that it has a permeability of m ² ·day·Kg/cm ² or more. 2. The aromatic polyimide semipermeable membrane according to claim 1, wherein the bis(aminophenoxy) compound represented by the general formula [] is 1,4-bis(4-aminophenoxy)benzene. 3. The aromatic polyimide semipermeable membrane according to claim 1, wherein the aromatic tetracarboxylic acid component consists essentially of only a biphenyltetracarboxylic acid component. 4. The aromatic polyimide semipermeable membrane according to claim 1, wherein the aromatic diamine component consists essentially of a bis(aminophenoxy) compound represented by the general formula []. 5. Claim 1, characterized in that the aromatic diamine component consists essentially of a mixture of a bis(aminophenoxy) compound represented by the general formula [] and 4,4'-diaminodiphenyl ether. aromatic polyimide semipermeable membrane. 6 (a) an aromatic tetracarboxylic acid component comprising at least 50 mol % of a biphenyltetracarboxylic acid component, and a general formula []: (However, n is 1 or 2) An aromatic polyimide formed from an aromatic diamine component containing at least 50 mol% of a bis(aminophenoxy) compound represented by; (b) a phenolic solvent; and (c) the above 5-100 for the amount of aromatic polyimide
A semipermeable aromatic polyimide characterized by forming a liquid thin film of a solution of a polyimide composition comprising a swelling agent consisting of glycol or its derivative in an amount of % by weight, and then solidifying the liquid thin film by immersing it in a coagulating liquid. Membrane manufacturing method.