JPS6075310A - Manufacture of polyquinazolone polymer compound film - Google Patents

Abstract

PURPOSE:To obtain the compound semipermeable film having excellent strength by dissolving a polyquinazolone polymer having a repeating unit expressed by a specified formula into a specified mixed solvent, and coating the obtained soln. on a porous film of a polymer which is insoluble in said solvent. CONSTITUTION:A polyquinazolone polymer having a repeating bisquinazolone unit expressed by the formual (R: quadrivalent aromatic group, R2: alkyl or aromatic group, R3: (p+2)-valent hydrocarbonic group, Z: carboxyl or sulfonic acid group, or its metallic salt group, P: 0 or 1-4 integer) is prepared. A mixed solvent of unsaturated and saturated aliphatic halogenated hydrocarbonic solvents and aliphatic alcohol is also prepared. Said polymer is dissolved into the mixed solvent. Then the obtained soln. is coated on a dry porous film consisting of a polymer which is insoluble in said mixed solvent to obtain the compound film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyquinazolone polymer composite membrane, and a method for producing a composite membrane in which a thin film made of a semipermeable polyquinazolone polymer is firmly supported by a porous support membrane. Regarding.

The present applicant has discovered that membranes made of polyquinazolone polymers have permeable properties as semipermeable membranes for liquid separation (for example, JP-A-56-53703), and that they can also be suitably used for gas separation. (For example, Japanese Unexamined Patent Publication No. 1983
-159505), but the film strength is not sufficient by itself.

In addition, polyquinazolone polymers are difficult to dissolve in ordinary organic solvents, so a membrane-forming solution is prepared by dissolving them in an aprotic polar organic solvent with high solubility such as 1ζN-methyl-2-pyrrolidone. Methods of coating on porous membranes made of various polymers have also been considered, but since the above solvent dissolves the porous membrane and destroys its porous structure, it has not been possible to obtain a satisfactory composite membrane. Ta.

As a result of intensive research by the present inventors to solve the above problems, we have found that polyquinazolone polymers are made from specific aliphatic unsaturated halogenated hydrocarbon solvents, aliphatic saturated halogenated hydrocarbon solvents, and lower aliphatic alcohols. By applying a membrane-forming solution prepared by dissolving a polyquinazolone polymer in such a mixed solvent onto a dry porous support membrane, the porous structure of the support membrane was destroyed. The present invention was developed based on the discovery that it is possible to obtain a composite membrane with excellent strength in which a semipermeable membrane made of a polyquinazolone polymer is reinforced by a support membrane without having to do so.

TIJJ, the present invention is based on the general formula (where R+ is a tetravalent aromatic group, R2 is each independently an alkyl group or an aromatic group, R3 is a (p+2)-valent hydrocarbon group, Z is a carboxyl group, a sulfonic acid group, or its metal base, and p represents 0 or an integer of 1 to 4 for each unit. an aliphatic unsaturated halogenated hydrocarbon solvent in which at least one carbon has one hydrogen atom and at least two halogen atoms in the molecule; an aliphatic saturated halogenated hydrocarbon solvent having one hydrogen atom and at least two halogen atoms in the molecule;
A film-forming solution obtained by dissolving in a mixed solvent with an aliphatic alcohol having 1 to 4 carbon atoms is applied onto a dry porous membrane made of a polymer that does not dissolve in the above mixed solvent, and the solvent is evaporated and removed. The present invention provides a method for producing a polyquinazolone polymer composite membrane.

The polyquinazolone polymer used in the present invention is
It is described in detail in the above-mentioned Japanese Patent Application Laid-open No. 56-5370'3, and is a substantially linear polymer having bisquinazolone units represented by the above general formula (I) as repeating units. The improved manufacturing method is disclosed in, for example, JP-A-57
It is described in the publication No.-12027.

In the general formula (0), R is a tetravalent aromatic group, and it is particularly preferable that it may have a substituent such as an alkyl group. Here, X is a divalent bonding group, and the bonding group here means a valence bond, an alkylene group, or a 2 (West group) consisting of a heteroatom (group) (with a carbon atom), and preferred specific examples include For example, -CH2-1-C(CH3
)2-1-〇-1-3O2-1-〇〇-, etc. can be mentioned.

Further, R2 is an alkyl group or an aromatic group, preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group or a phenyl group. Two R in the above repeating unit
Although the two are combined, they do not necessarily have to be the same.

Next, R3 is a (p+2)-valent hydrocarbon group, specifically a (p+2)-valent aromatic, aliphatic, or alicyclic hydrocarbon group, or a divalent bonding group in which these hydrocarbon groups are It is a <p + 2) valent hydrocarbon group bonded by X.

In particular, R3 is preferably an aromatic group. Therefore, when p=o in the general formula (1), R3 is preferably a divalent aromatic group, and a specific example of the aromatic group is , for example, can be mentioned. Here, X is the above-mentioned bonding group.

In the above general formula, Z is a carboxyl group, a sulfonic acid group, or an alkali metal base thereof such as sodium or potassium. Therefore, when p is an integer of 1 to 4, for example, when p=1, a preferable trivalent Specific examples of the aromatic group include, for example.

In a polyquinazolone polymer having a repeating unit where p is not O, as the proportion of the repeating unit increases, the polymer becomes more hydrophilic due to the hydrophilic group Z, and in this way, the hydrophilic polyquinazolone polymer A membrane consisting of has a high permeation rate.

In the present invention, the polyquinazolone polymer is dissolved in a mixed solvent of a specific aliphatic unsaturated halogenated hydrocarbon solvent, an aliphatic saturated halogenated hydrocarbon solvent, and an aliphatic alcohol to prepare a film forming solution.

The aliphatic unsaturated halogenated hydrocarbon solvent used in the present invention has two carbon atoms, at least one carbon has one hydrogen atom, and at least two halogen atoms in the molecule, and has high volatility. Specific examples include 1,1-dichloroethylene, 1
．． Examples include 2-dichloroethylene and trichlorethylene, and trichlorethylene is preferably used because it has particularly excellent solubility of polyquinazolone polymers when used as a mixed solvent.

In addition, the aliphatic saturated halogenated hydrocarbon solvent has a carbon number of 1.
or 2, and at least one carbon has at least one hydrogen atom and at least 2
It has two halogen atoms, is highly volatile, and is liquid at room temperature. Specific examples include dichloromethane, chloroform,
Ll-dichloroethane, 1,2-dichloroethane, 1,
Examples include 1,2-1-dichloroethane, LL, 2,2-tetrachloroethane, and pentachloroethane, but chloroform is preferably used because it has particularly excellent solubility for polyquinazolone polymers.

The aliphatic alcohol is a lower aliphatic alcohol having 1 to 4 carbon atoms, and methanol, ethanol, propatool, and butanol can be used, but methanol, ethanol, and propatool, which are highly volatile at room temperature, are preferably used. It will be done.

The mixed solvent in the present invention contains 10 parts by weight or more of the saturated halogenated hydrocarbon solvent, preferably 20 to 40 parts by weight, per 100 parts by weight of the unsaturated halogenated hydrocarbon solvent.
It is adjusted by mixing at a ratio of 0 parts by weight. If the amount of the saturated halogenated hydrocarbon solvent is 10 parts by weight or less, the mixed solvent will not dissolve the polyquinazolone polymer well, and furthermore, phase separation will occur when it is coated on a support! +111, and a uniform thin film cannot be obtained. The reason for this is not necessarily clear, but
Since the unsaturated halogenated hydrocarbon solvent that is present in large amounts in the mixed solvent is highly volatile and has a high evaporation rate, the mixing ratio of the film forming solution changes rapidly during film forming, resulting in a decrease in the solubility of the polyquinazolone polymer. It is thought that this will decrease. Further, by reducing the proportion of the saturated halogenated hydrocarbon solvent to such an extent that the above-mentioned phase separation does not occur, the evaporation rate of the solvent can be increased and film formation can be accelerated. Therefore, the optimum mixing ratio of the unsaturated halogenated hydrocarbon solvent and the saturated halogenated hydrocarbon solvent can be appropriately set by considering the above-mentioned points and depending on the combination of solvents used.

Further, the amount of the alcohol mixed in the mixed solvent used in the present invention is 1 to 500 parts by weight, preferably 5 to 200 parts by weight, based on 100 parts by weight of the total amount of the unsaturated and saturated halogenated hydrocarbon solvents. The optimum mixing ratio is appropriately selected depending on the combination of both halogenated hydrocarbon solvents and alcohol used. If the amount of alcohol is too small, the polyquinazolone polymer will swell and will not dissolve well in the mixed solvent, which is not preferable, while if it is too large, the solubility will be poor, which is not preferable.

In the present invention, a film forming solution is obtained by dissolving a polyquinazolone polymer in a mixed solvent of an unsaturated or saturated halogenated hydrocarbon solvent such as "Nipart" and the above-mentioned alcohol, and this solution is dried to form a suitable porous film. The polymer is coated onto a membrane, the solvent is evaporated off, the polymer is coagulated, and a membrane is formed. The polymer concentration in the membrane forming solution is usually in the range of 0.05 to 10% by weight,
Preferably it is 0.1 to 5% by weight.

In the method of the present invention, a membrane-forming solution with a relatively low polymer concentration is used, so by applying the membrane-forming solution onto the dry porous membrane and drying it two or more times, a uniform layer can be formed on the porous crotch. Preferably, a thin film is formed.

As the porous membrane used in the present invention, a porous membrane made of any polymer such as polyamide or polyimide can be used as long as it is not dissolved in the above-mentioned mixed solvent.
For example, as described in JP-A No. 57-159508, a porous membrane that can be preferably used is made of an aromatic polyamide having repeating units represented by the following general formula (II). fraction molecular weight is 1000
A dry porous membrane obtained by drying an ultrafiltration membrane having a density of about 10,000 to 10,000, preferably about several thousand can be mentioned.

Further, in the present invention, it is preferable to use a dry membrane in which the porous membrane is obtained as a wet membrane, then immersed in an aqueous solution of a polyhydric alcohol, its ester derivative or ether derivative, and then dried. Such polyhydric alcohols, their ester derivatives, or ether derivatives do not dissolve the membrane, can at least partially replace the water in the micropores of the wet membrane, and can suppress the shrinkage of the micropores during drying, and their molecular weight is preferably 1000 or less, particularly 600 or less. Preferred specific examples include diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, glycerin, glycerin monoacetate, glycerin diacetate, triethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and the like. Further, the concentration of the aqueous solution of the polyhydric alcohol, its ester derivative or ether derivative is 1 to 60% by weight, particularly 5 to 30% by weight.
is desirable.

A dry film can be obtained by immersing the wet film in an aqueous solution of the polyhydric alcohol, its ester derivative, or ether derivative, and then drying at a temperature at which the polyhydric alcohol substantially remains in the film. . The drying temperature is 0 to 100°C, especially at room temperature of 20 to 30°C.
It is preferable to dry for 5 hours or more.

By applying a membrane-forming solution onto the dense layer of the dry porous membrane obtained in this way and evaporating the solvent, a composite membrane in which a semipermeable membrane made of polyquinazolone polymer is formed on the porous membrane is formed. obtain. Since the mixed solvent is highly volatile, it does not require heating to evaporate, and can be naturally evaporated at rich or ambient temperatures. Furthermore, since the polyamide preferably used in the present invention does not dissolve in the above-mentioned mixed solvent, it can be used as a composite material having a semipermeable membrane of a homogeneous, pinhole-free, thin film of polyquinazolone-based polymer without destroying its porous structure. membrane can be obtained. Since such a composite membrane is reinforced with a porous membrane and has sufficient strength, it is suitable for use as a liquid separation membrane such as a reverse osmosis membrane or an ultrafiltration membrane, or as a gas separation membrane.

Examples of the present invention are listed below, but the present invention is not limited to the same extent by these Examples.

Example 1 According to the method described in JP-A-57-159508, in the general formula (II), 70 mol% of m-phenylene group and 30 mol% of p-phenylene group were prepared.
and the intrinsic viscosity of the N-methyl-2-pyrrolidone solution at 30°C is 1.83.
The polymer was dissolved in methyl-2-pyrrolidone to a concentration of 12% by weight, and 41.7 parts by weight of lithium chloride and 167 parts by weight of dioxane were added to N-methyl-2-pyrrolidone for 100 parts by weight of this polymer. A membrane forming solution was prepared by dissolving the mixture.

After coating this film-forming solution on a glass plate at room temperature, it was immediately poured into water at 0°C and soaked for 24 hours until the thickness was approximately 150 μm.
An ultrafiltration membrane of m was obtained. This membrane was naturally dried at a temperature of 25° C. for 12 hours to obtain a dry porous membrane.

Separately, polyquinazolone 1 having 80 mol% bisquinazolone units and 20 mol% bisquinazolone units
g was dissolved in a mixed solvent of 15 g of trichlorethylene and 3 g of methanol, and 15 g of chloroform was added thereto and stirred, followed by pressure filtration using a filter paper with an average pore size of 10 μm to obtain a membrane forming solution.

This was applied onto the above porous membrane to a thickness of 55 μm in an air atmosphere at 25° C., and the solvent was naturally evaporated twice to obtain a composite membrane according to the present invention.

The above composite membrane was attached to a reverse osmosis tester so that the polyquinazolone polymer synovial fluid side was in contact with the stock solution, and 5000 p.
When a salt aqueous solution of pm was treated at 25°C and 40 kg/cal, the salt removal rate was 99% and the water permeation rate was 0.
The speed was 03m/rrr/day.

Example 2 70 mol% of the bisquinazolone units (III) and 3
1 g of polyquinazolone having 0 mol % of the bisquinazolone units (IV) was dissolved in a mixed solvent consisting of 15 g of 1-lichloroethylene, 15 g of chloroform, and 6 g of methanol, and the solution was prepared in the same manner as in Example 1. .

The membrane performance of the composite membrane obtained from this BiA solution in the same manner as in Example 1 was as follows: salt removal rate of 99%, water permeation rate of 0°1 m
/ r+(・day.

Example 3 After dissolving 1 g of polyquinazolone consisting only of the bisquinazolone unit (II[) in a mixed solvent consisting of 18 g of trichlorethylene, 12 g of chloroform, and 3.6 g of methanol, a film-forming solution was obtained in the same manner as in Example 1. .

The membrane performance of the composite membrane obtained from this membrane forming solution in the same manner as in Example 1 was as follows: salt removal rate of 99%, water permeation rate of 0°02 I/M.
Person who is day:.

Example 4 Gas permeability was measured using the composite membrane obtained in Example 1.

The results are shown in Table 1.

Table 1: Gas permeability coefficient (CC(STP)/cm ・
sec · cm II g ) was determined by a high vacuum method at 25°C, and the separation coefficient α was calculated from the permeability coefficient of the gas/the permeability coefficient of nitrogen at 25°C.

patent applicant Nitto Electric Industry Co., Ltd. Representative Sanbe Hijikata

Claims (1)

[Claims] General formula (wherein R+ is a tetravalent aromatic group, R2 is each independently an alkyl group or an aromatic group, I is a (p + 2)-valent hydrocarbon group, Z is a carboxyl group, represents a sulfonic acid group or its metal base, and p represents 0 or an integer from 1 to 4 for each unit.) A polyquinazo 1:1 polymer having bisquinazo 1:1 units as repeating units, represented by The number of carbon atoms is 2,
and an aliphatic unsaturated halogenated hydrocarbon solvent in which at least one carbon has one hydrogen atom and at least two halogen atoms in the molecule; At least 1 carbon
A film-forming solution prepared by dissolving an aliphatic saturated halogenated hydrocarbon solvent having one hydrogen atom and at least two halogen atoms in the molecule and an aliphatic alcohol having 1 to 4 carbon atoms as described above. A method for producing a polyquinazolone polymer composite membrane, which comprises coating a dry porous crotch made of a polymer that does not dissolve in a mixed solvent, and evaporating and removing the solvent.