JPS61200817A - Production of sulfonated polysulfone composite semipermeable membrane - Google Patents

Abstract

PURPOSE:To obtain a composite semipermeable membrane excellent in chlorine resistance and pH resistance, by applying a solution, which is prepared by dissolving sulfonated polysulfone and a low volatile compound in alkylene glycol alkyl ether, to a support membrane before drying. CONSTITUTION:A sulfonated polysulfone polymer to be used has characteristic values such that the logariathmic viscosity of a solution of 0.5g of the polymer in 100ml of N-methyl-2-pyrrolidone at 30 deg.C is 0.2 or more and the ion exchange capacity of 1g of this polymer is 2.3 miliequivalent or less. As a solvent, alkylene glycol alkyl ether having a 2-4 C alkylene group and an 1-4C alkyl group is pref., but a small amount of an aprotic polar org. solvent may be added. A film forming solution is prepared by adding a low volatile compound dissolved in the solvent and applied to a support membrane before drying.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing a composite semipermeable membrane made of sulfonated polysulfone, and more specifically, the present invention relates to a method for producing a composite semipermeable membrane made of sulfonated polysulfone. The present invention relates to a method for manufacturing a composite semipermeable membrane formed on an outer filtration membrane.

(Prior Art) A linear polysulfone copolymer having 2B and 2B as repeating units has already been described in Canadian Patent No. 847,963, and a sulfonated product of this copolymer has also been described. It is described in Japanese Unexamined Patent Publication No. 55-48222. That is,
This publication states that by dissolving the polysulfone copolymer in concentrated sulfuric acid and sulfonating, substantially all of the repeating units of formula A are sulfonated, but substantially all of the repeating units of formula A are sulfonated. It has been described that a hydrophilic sulfonated polysulfone is produced in which the sulfonated polysulfone remains in a non-sulfonated state.

A sulfonated product of polysulfone consisting of
．． It is described in the specification of No. 709,841, and is published in Japanese Unexamined Patent Publication No. 5
0-99973 and JP-A-51-146379 disclose that by applying a solution of such sulfonated polysulfone onto a dense layer on the surface of an anisotropic ultrafiltration membrane and evaporating the solvent, A method for manufacturing a composite semipermeable membrane for reverse osmosis in which a semipermeable thin membrane is laminated on an ultrafiltration membrane is described. Similarly, office of W
ater Re5archand Technolo
gy Department of the Inte
rior.

In Report No. 2001-20, the above formula C
An anisotropic ultrafiltration membrane consisting of repeating units of formula C is packed in advance with an aqueous lactic acid solution, a solution of a sulfonated polysulfone also consisting of repeating units of formula C above is applied onto this ultrafiltration membrane, and the solvent is removed. A method for obtaining a composite semipermeable membrane by evaporation is described.

(Object of the Invention) However, the present inventors sulfonated a polysulfone consisting only of repeating units of the formula A, and formed a thin semipermeable membrane from the sulfonated polysulfone on a dry support membrane. , a composite semipermeable membrane can be obtained,
It has been found that this composite semipermeable membrane is particularly useful as a reverse osmosis membrane or an ultrafiltration membrane with excellent chlorine resistance and pH resistance.

Furthermore, the present inventors formed a polysulfone copolymer obtained by sulfonating the linear polysulfone copolymer of formulas A and 2B on a dry ultrafiltration membrane as a support membrane. By doing so, it has better physical properties and performance than the conventionally known composite semipermeable membranes mentioned above, and in particular, in favorable cases, it can achieve an extremely high sodium chloride removal rate in the treatment of saline solutions. It has been found that it is possible to obtain a reverse osmosis membrane that has the following properties and has excellent chlorine resistance, ρ11 resistance, and heat resistance.

In addition, the present inventors have discovered that in the production of a composite semipermeable membrane, a thin semipermeable membrane made of the above sulfonated polysulfone or sulfonated polysulfone copolymer is formed on an ultrafiltration membrane as a support membrane. By adding an additive consisting of a certain water-soluble organic or inorganic compound to the membrane-forming solution containing the above polymer, the physical properties of the resulting composite semipermeable membrane, particularly the solute removal rate and The present invention was achieved by discovering that the amount of water permeating through a membrane can be controlled over a wide range.

(Structure of the Invention) The first method for producing a sulfonated polysulfone composite semipermeable membrane according to the present invention is to produce a polymer formed by sulfonating a polysulfone consisting of the following: Preferably, 0.5 g of this polymer is mixed with N-methyl- 2
- for a solution dissolved in 100 ml of pyrrolidone, 30
A sulfonated polysulfone having a logarithmic viscosity measured at °C of 0°2 or more and an ion exchange capacity of 2.3 meq/g or less, and an alkylene which may contain a small amount of an aprotic polar organic solvent. Applying a film-forming solution containing a glycol alkyl ether and a water-soluble and low-volatility compound as an additive to the dried support crotch,
The second method for producing a sulfonated polysulfone composite semipermeable membrane according to the present invention is characterized in that the organic solvent is then evaporated from the membrane forming solution. (hereinafter sometimes referred to as sulfonated polysulfone copolymer), preferably this polymer
．． A sulfonated polysulfone having a logarithmic viscosity of 0.2 or more and an ion exchange capacity of 2.3 milliequivalents/g or less when measured at 30°C for a solution of 5 g dissolved in 100 ml of N-methyl-2-pyrrolidone. A support membrane obtained by drying a membrane-forming solution containing a copolymer, an alkylene glycol alkyl ether that may contain a small amount of an aprotic polar organic solvent, and a water-soluble and low-volatility compound as an additive. The organic solvent is then evaporated from this film forming solution.

The sulfonated polysulfone used in the first method of the present invention is a hydrophilic polymer obtained by sulfonating a polysulfone having a repeating unit represented by formula A above. This sulfonated polysulfone is a polysulfone having a repeating unit represented by the above formula A.
~98%! It is obtained by adding it to sulfuric acid and stirring gently for several hours at room temperature. After the reaction, the sulfonated polysulfone can be easily separated as a water-insoluble polymer by pouring the resulting viscous reaction solution into water and filtering it.

In the present invention, such sulfonated polysulfone is
For 1g of dry resin, the ion exchange capacity is 2.3mm! /g or less, and the logarithmic viscosity (hereinafter referred to as sulfonated polysulfone and sulfonated polysulfone copolymer The method for measuring the logarithmic viscosity is the same.) is required to be 0.2 or more, preferably 0.5 or more.

In a polysulfone in which the repeating unit consists only of formula A,
When all of the aromatic rings sandwiched between two ether groups are monosulfonated, the theoretical ion exchange capacity of the sulfonated polysulfone is 2.4 mEq! However, the partially sulfonated polysulfone used in the present invention needs to have an ion exchange capacity of 2.3 milliequivalents/g or less.

When the ion exchange capacity exceeds 2.3 meq/g,
Sulfonated polysulfones now have water solubility, making them unsuitable for use as semipermeable membranes that often treat liquids containing aqueous media. Furthermore, when the logarithmic viscosity is less than 0.2, the molecular weight of the sulfonated polysulfone is too small, making it difficult to form a uniform thin film without defects such as pinholes.

The sulfonated polysulfone copolymer used in the second method of the present invention has the above-mentioned repeating unit A and repeating unit B.
It can be easily obtained by dissolving a linear polysulfone copolymer consisting of the following in concentrated sulfuric acid and stirring at room temperature for several hours. As mentioned above, the degree of sulfonation is
Substantially all of the aromatic rings between the ether bonds in the repeating unit of formula A are monosulfonated, but substantially all of the repeating units of NiB remain in a non-sulfonated state. By using a copolymer with a different ratio of repeating units to B, the degree of sulfonation of linear polysulfone can be easily controlled.

In the present invention, the sulfonated polysulfone copolymer preferably has a linear polysulfone copolymer as a precursor consisting of 10 mol% or more of repeating units A and 90 mol% or less of repeating units B. In addition, in the present invention, this sulfonated polysulfone copolymer also has an ion exchange capacity of 2.3 mm/t/g or less per 1 g of dry resin, and its logarithmic viscosity It is necessary that the value is 0.2 or more, preferably 0.5 or more. This is because when the ion exchange capacity of the sulfonated polysulfone copolymer exceeds 2.3 milliequivalents/g, the copolymer becomes water-soluble. Further, when the logarithmic viscosity is smaller than 0.2, it is difficult to form a uniform thin film without defects such as pinholes.

The sulfonic acid group possessed by the sulfonated polysulfone or sulfonated polysulfone copolymer used in the method of the present invention is represented by the formula -SO3M, where M represents hydrogen, an alkali metal or a tetraalkylammonium.

For example, by sulfonating a polysulfone consisting of a repeating unit represented by formula A, washing the sulfonated polysulfone with water and drying it, a sulfonated polysulfone having free sulfonic acid groups can be obtained. Further, by suspending and treating this sulfonated polysulfone in an aqueous solution, methanol, ethanol solution, etc. of an alkali metal hydroxide or alkali metal alcoholade, the sulfonic acid group can be converted into an alkali metal salt. The same applies to sulfonated polysulfone copolymers. As the alkali metal hydroxide, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. are used, and as the alkali metal alcoholade, for example, sodium methylate, potassium methylate, potassium ethylate, etc. are used. Alternatively, if a sulfonated polysulfone or a sulfonated polysulfone copolymer is similarly treated with a solution deprived of a tetraalkylammonium, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, , the sulfonic acid groups of the polymer can be the corresponding tetraalkylammonium salts.

The composite semipermeable membrane according to the present invention comprises the sulfonated polysulfone or sulfonated polysulfone copolymer, a water-soluble and low volatility compound as an additive, and a small amount of an aprotic polar organic solvent. It can be obtained by dissolving it in a good alkylene glycol alkyl ether to prepare a film-forming solution, coating this on a dried support film, and then evaporating the organic solvent from this film-forming solution.

As the organic solvent for preparing the film forming solution, in the present invention, alkylene glycol alkyl ethers in which the alkylene group has 2 to 4 carbon atoms and the alkyl group has 1 to 4 carbon atoms are particularly preferably used. . This solvent has excellent solubility for both the sulfonated polysulfone and the sulfonated polysulfone copolymer used in the present invention, and is also highly volatile; on the other hand, it is suitable for use as a support film in the present invention. This is because it does not dissolve the polysulfone ultrafiltration membrane that can be formed. Specific examples of such alkylene glycol alkyl ethers include alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether, ethylene glycol dimethyl ether, and ethylene glycol monoethyl ether. Examples include alkylene glycol dialkyl ethers such as glycol methyl ethyl ether and ethylene glycol diethyl ether. In particular, ethylene glycol monomethyl ether is preferably used because it has excellent solubility for sulfonated polysulfone and sulfonated polysulfone copolymers and is highly volatile.

However, depending on the sulfonated polysulfone or sulfonated polysulfone copolymer used, it may be difficult to dissolve it in the alkylene glycol alkyl ether, or it may simply swell. It has been found that the coalescence also dissolves well in a mixed solvent prepared by adding a small amount of an aprotic polar organic solvent to the alkylene glycol alkyl ether. Examples of such aprotic polar organic solvents include dimethyl sulfoxide, N-methyl-2-pyrrolidone, N,
N-dimethylformamide, N,N-dimethylacetamide and the like are preferably used. In such a mixed solvent, the proportion of the aprotic polar organic solvent is preferably 5 parts by weight or less, particularly 3 parts by weight or less, based on 100 parts by weight of the alkylene glycol alkyl ether. In the mixed solvent, when the amount of the aprotic polar organic solvent is more than 5 parts by weight per 1.0 parts by weight of the above alkylene glycol alkyl ether, the membrane forming solution was applied onto a dry polysulfone ultrafiltration membrane as a support membrane. In this case, the ultrafiltration membrane dissolves or swells, making it impossible to obtain a composite semipermeable membrane with good performance.

As described above, using alkylene glycol alkyl ether or a mixed solvent of alkylene glycol alkyl ether and a small amount of the above-mentioned aprotic polar organic solvent as a solvent for the membrane-forming solution is effective in applying the membrane-forming solution to the support membrane, as described below. After that, in the step of evaporating and removing the solvent from this film forming solution, it is advantageous because substantially all the solvent can be removed by heating at room temperature or a small amount, and a uniform thin film without defects can be obtained. be.

The concentration of the sulfonated polysulfone or sulfonated polysulfone copolymer in the membrane forming solution is related to the thickness of the semipermeable membrane made of these polymers in the resulting composite semipermeable membrane, but is usually 0.05 to 10% by weight. The range is preferably 0.1 to 5% by weight, particularly preferably 0.1 to 5% by weight.

In the present invention, the membrane forming solution contains specific additives. Among these additives, organic compounds include polyhydric alcohols, polyalkylene glycols, carboxylic acids,
At least one selected from the group consisting of salts thereof, hydroxycarboxylic acids, and salts thereof is used. These organic compounds as additives must be water-soluble and have low volatility, and must be dissolved in the film forming solution. Polyalkylene glycols, carboxylic acids, salts thereof, and hydroxycarboxylic acids or salts thereof are preferably used. Specific examples include ethylene glycol, propylene glycol, glycerin, 1,4-butanediol, etc. as polyhydric alcohols, diethylene glycol, triethylene glycol, dipropylene glycol, etc. as polyalkylene glycols, and citric acid, sulfur as carboxylic acids. Examples of acids include lactic acid, hydroxybutyric acid, etc. as hydroxycarboxylic acids, and sodium salts, potassium salts, etc. as salts of carboxylic acids and hydroxycarboxylic acids.

Moreover, in the present invention, it is water-soluble and! ! I
T! Inorganic salts dissolved in the J solution can also be used as additives. Examples of such inorganic salts include lithium chloride, lithium nitrate, and magnesium perchlorate.

The concentration of these additives in the film forming solution is usually 0.1
~80% by weight. Although the effects of these additives on the formation of composite semipermeable membranes are not necessarily clear,
It is related to the micropore diameter of the semipermeable membrane formed from sulfonated polysulfone or sulfonated polysulfone copolymer, and when applying the membrane forming solution onto the ultrafiltration membrane that is the supporting membrane, the Solvents and additives appear to modify the surface of the ultrafiltration membrane, and thus, by selecting the type and amount of additives used, the performance of the composite semipermeable membrane, in particular the removal of solutes, can be improved according to the invention. The rate and amount of water permeated through the membrane can be controlled over a wide range.

In the method of the present invention, the membrane forming solution prepared as described above is then applied onto a dry ultrafiltration membrane as a support membrane. As is well known, a dry ultrafiltration membrane is produced by heating a wet ultrafiltration membrane prepared by a wet method to an appropriate temperature to evaporate and dry the water contained in the membrane's micropores. You can get it by doing this. In the present invention, in particular, polysulfone is made of a polysulfone having a repeating unit represented by the formula C, and has a molecular weight cut-off of 1000 to 200000 in a wet state, particularly 5oooo to 200000.
An ultrafiltration membrane of 15000G is preferably used.

In the method of the present invention, as described above, alkylene glycol alkyl ether or a mixed solvent containing a small amount of the aprotic polar organic solvent is used as the solvent for the membrane forming solution, so heating is usually not required. Substantially all of the solvent can be evaporated at room temperature; however, after the membrane-forming solution is applied onto the support membrane, it may be heated if necessary to evaporate the solvent. The heating temperature may be selected appropriately depending on the solvent used, but usually 15
A temperature below 0°C is sufficient. Incidentally, in order to promote evaporation of the solvent after the film-forming solution is applied onto the support film, the film-forming solution may be heated in advance and then applied onto the support film.

The thickness of the thin semipermeable membrane based on the sulfonated polysulfone copolymer in the composite semipermeable membrane thus obtained is determined by the concentration of these polymers in the membrane forming solution and the transfer to the supporting membrane. Although it depends on the coating thickness of the membrane forming solution, it is better to be thinner to increase the water permeation rate of the composite semipermeable membrane, and thicker to increase the strength. Therefore,
In particular, although not limited thereto, semipermeable membranes based on sulfonated polysulfone or sulfonated polysulfone copolymers usually preferably have a membrane thickness in the range of 0.01 to 58 m.

Depending on the type of additive used, additives may remain in the composite semipermeable membrane obtained in this way. water,
Alternatively, these additives can be removed from the membrane by immediate treatment of the aqueous liquid.

(Effects of the Invention) The composite semipermeable membrane according to the first method of the present invention has particularly excellent chlorine resistance and pH resistance, and is suitable for use as a reverse osmosis membrane or an ultrafiltration membrane. The composite semipermeable membrane according to the second method of the present invention also has excellent chlorine resistance and pH resistance, and is suitable for use as a reverse osmosis membrane.
A composite semipermeable membrane obtained from a sulfonated linear polysulfone copolymer in which the repeating unit of B is in the range of 50 to 10 mol% and the repeating unit of NiB is in the range of 50 to 90 mol% is Through this treatment, it has a high removal rate for sodium chloride, and the water permeation rate is sufficiently high for practical use. Furthermore, if necessary, the removal rate of the composite semipermeable membrane can be increased by drying and rewetting operations.

Furthermore, according to the method of the present invention, the performance of the resulting composite semipermeable membrane, particularly the solute removal rate and water permeation rate, can be varied over a wide range by selecting the type and concentration of additives added to the membrane forming solution. Because it can be controlled
It is possible to easily design a membrane suitable for the application.

(Examples) The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way. In the examples, the solute removal rate and water permeation rate of the obtained composite semipermeable membranes were measured at a concentration of 500 unless otherwise specified.
0 ppm sodium chloride aqueous solution at a temperature of 25°C and a pressure of 2
The membrane was processed under the condition of 0 kg/cffl, and each value was determined by the following formula.

Example 1 (1) Production of polysulfone A polysulfone having a repeating unit of the formula AI was produced according to the method described in Japanese Patent Publication No. 46-21458.

That is, 13.2 g (0.12 mol) of hydroquinone was placed in a flask equipped with a stirrer, a nitrogen gas inlet tube, a water drain tube, and a thermometer, and 100 ml of sulfolane and 5 ml of xylene were added to the flask.
Added 0ml. Refluxing was carried out at 150° C. for 1 hour while stirring while heating with a mantle heater, and at this time, 3 ml of fishing rod was taken out.

Next, the temperature was lowered to 110° C., and 34.5 g (0.12 mol) of 4.4°-dichlorodiphenylsulfone and 20.7 g (0.15 mol) of potassium carbonate were added to start the polymerization reaction. After refluxing at 155°C for 50 minutes, the temperature was raised to 200°C while removing water for 50 minutes, and then refluxed for 20 minutes.
Refluxing was continued for 30 minutes at 00-215°C. The amount of water drawn off during this reaction was 3.6 ml.

After confirming that a film could be formed when a portion of the reaction solution was applied to a glass plate and immersed in water, 80 ml of sulfolane was added to the reaction solution, the temperature was lowered to 100° C., and 20 ml of dichloromethane was added.

The reaction mixture thus obtained was poured into pure water to solidify the polysulfone, and the mixture was allowed to stand overnight. This was separated, pulverized with a mixer, washed with pure water and isopropyl alcohol, and then dried at a temperature of 80° C. for 6 hours.

The polysulfone thus obtained is a reddish-colored granular material, and its logarithmic viscosity (hereinafter referred to as the logarithmic viscosity of polysulfone) was measured at 47°C as a solution of 0.5 g of this polymer dissolved in 100 ml of p-chlorophenol. The measurement conditions were the same.) was 1°40.

(2) Production of sulfonated polysulfone 10 g of the polysulfone obtained as described above was added to 80 ml of 97% concentrated sulfuric acid, and the mixture was stirred gently at room temperature for 4 hours to obtain a dark brown viscous reaction liquid.

This was placed in a water bath to solidify the sulfonated polysulfone. After washing with water, it was left overnight in 800 ml of a 0° 5N aqueous sodium hydroxide solution. Next, the polymer was washed until the washing solution became neutral, and then vacuum-dried at 30° C. for 7 hours.

The pale yellow granular sulfonated polysulfone thus obtained has a logarithmic viscosity of 3.0 and an ion exchange capacity of 1.9.
It was 2 milliequivalents/g.

(3) Manufacture of composite semipermeable membrane Consisting of repeating units of the above formula C, with an average molecular weight of 2000
Removal rate of 0 polyethylene glycol is 10%
An anisotropic ultrafiltration membrane made of polysulfone having a molecular weight cut off of 100,000 was left in a dryer at 60° C. for 5 minutes to obtain a dry ultrafiltration membrane.

The sulfonated polysulfone was dissolved in ethylene glycol monomethyl ether and the pore size was 10. A polymer solution with a concentration of 1.0% by weight was prepared by removing foreign matter using a czm filter paper, and then 10 g of 1゜4-butanediol was added to 90 g of this solution and stirred to obtain a uniform film-forming solution. And so. That is, this membrane forming solution contains partially sulfonated polysulfone 0.9
% by weight, containing 10% by weight of additives.

This membrane-forming solution was applied onto the dry ultrafiltration membrane, left at room temperature to evaporate almost all the solvent, and then heated to 60°C.
A composite semipermeable membrane according to the present invention was obtained by heating at a temperature of 5 minutes.

The performance of this composite semipermeable membrane was a removal rate of 50.0% and a water permeation rate of 5.9 rrr/rrr·day.

Example 2 Example 1 except that lactic acid was used as the additive and the concentration in the film forming solution was 10% by weight.
A composite semipermeable membrane was obtained in the same manner.

The performance of this composite semipermeable membrane was a removal rate of 50.3% and a water permeation rate of 5.9 M/n (day).

Example 3 A composite semipermeable membrane was obtained in the same manner as in Example 1, except that 1,4-butanediol or lactic acid was added as an additive to the membrane forming solution at the concentration shown in Table 1. Ta. The membrane performance of the composite semipermeable membrane thus obtained is shown in Table 1. Table 1 also shows the performance of a composite semipermeable membrane obtained from a membrane forming solution without additives as a comparative example.

When using a membrane-forming solution containing up to 10% by weight of 1,4-butanediol, the water permeation rate can be significantly improved compared to the comparative example without increasing or changing the removal rate. Furthermore, in other examples, the water permeation rate is significantly improved.

Example 4 A composite semipermeable membrane was prepared in the same manner as in Example 1 using the additives shown in Table 2.

In the evaluation of membrane performance, the concentration of the stock solution was 500 pp.
Using m sucrose aqueous solution, temperature 25°C 1 pressure 20k
Permeation experiments were conducted at g/-. The results are shown in Table 2.

Example 5 (Acid resistance) The semipermeable membrane obtained in Example 1 was immersed in distilled water for 2 hours,
Next, after being immersed in a 0.5N hydrochloric acid aqueous solution at 25° C. for 2 hours, the membrane performance was measured with respect to a sodium chloride aqueous solution under the same conditions as in Example 1. The removal rate was 45.0%, and the water permeation rate was 5.8 r//nr·day, which was essentially unchanged compared to before immersion in the hydrochloric acid aqueous solution. Therefore, it is understood that the composite semipermeable membrane of the present invention has excellent acid resistance.

(Alkali resistance) The composite semipermeable membrane obtained in Example I was immersed in distilled water for 2 hours, then in a 0.5N aqueous sodium hydroxide solution at 25°C for 2 hours, and then immersed under the same conditions as Example 1. Membrane performance was measured for an aqueous sodium chloride solution. The removal rate is 4
5.0%, the water permeation rate is 6°0rrr/d・day,
There was virtually no change compared to before immersion in the sodium hydroxide aqueous solution. Therefore, it is understood that the composite semipermeable membrane of the present invention has excellent alkali resistance.

(Chlorine resistance) The composite semipermeable membrane (al) obtained in Example 3 was immersed in distilled water for 2 hours, and then immersed in an aqueous solution containing 1100 pp of chlorine ions at a temperature of 25° C. for 4 weeks. Membrane performance for sodium chloride aqueous solution was measured under the same conditions as in 1. Removal rate was 67.0%, water permeation rate was 3.1rr.
f/nf·day, with virtually no change. Similarly, the removal rate after 4 weeks of immersion in an aqueous solution with a chloride ion concentration of 10,000 ppn+ was 68.0%, and the water permeation rate was 3. On
? It was /--day. We also investigated changes in membrane performance over time, but no substantial changes were observed. Therefore, it is understood that the semipermeable membrane of the present invention has excellent chlorine resistance.

Example 6 (Production of 11-linear polysulfone copolymer)
According to the method described in No. 1458, a linear polysulfone copolymer consisting of 57 mol% of repeating units of formula A and 43 mol% of repeating units of NiB was produced.

That is, 4,4'-dihydroxydiphenylsulfone 15
, Og (0,06 mol) and hydroquinone 8.8 g (
0.08 mol) was placed in a flask equipped with a stirrer, nitrogen gas inlet tube, water drain tube and thermometer, and sulfolane 2
00 ml and 100 ml of xylene were added.

155 while stirring while heating with a mantle heater.
Refluxing was carried out at ℃ for 1 hour, during which time 5.6 ml of water was extracted.

Next, the temperature was lowered to 110°C, and 40.2 g (0.14 mol) of 4,4'-dichlorodiphenylsulfone and 7.6 g (0.20 mol) of potassium carbonate were added to start the polymerization reaction. . After refluxing at 162°C for 1 hour, 2.
The temperature was raised to 200° C. while removing water over a period of 5 hours, and reflux was continued at 200 to 215° C. for 4 hours. The amount of water drawn off during this reaction was 2.0 ml.

After confirming that a film could be formed when a portion of the reaction solution was applied to a glass plate and immersed in water, the temperature was lowered to 100°C and 20 ml of dichloromethane was added. The reaction mixture thus obtained was poured into pure water to solidify the polysulfone copolymer, washed with pure water and then with acetone, and then dried at 80° C. for 6.5 hours.

The linear polysulfone copolymer thus obtained is
It appeared as pale yellow granules, and its logarithmic viscosity was 0.84.

(2) Production of sulfonated polysulfone copolymer 10 g of the polysulfone copolymer obtained as described above was 97%
The mixture was added to 80 ml of concentrated sulfuric acid to dissolve it, and stirred and reacted at room temperature for 4 hours to obtain a dark brown viscous reaction liquid. This was placed in a water bath to solidify the sulfonated polysulfone copolymer. After washing with water, it was left overnight in 390 ml of 0.5 N aqueous sodium hydroxide solution. Next, the polymer was washed until the washing solution became neutral, and then vacuum-dried at 60° C. for 5 hours.

The pale yellow granular sulfonated polysulfone copolymer thus obtained had a logarithmic viscosity of 0.84 and an ion exchange capacity of 1.2 milliequivalents/g.

(3) Production of composite semipermeable membrane The sulfonated polysulfone copolymer obtained as above was dissolved in ethylene glycol monomethyl ether,
Prepare a 1.0% by weight polymer solution, add glycerin to 90g of this solution so that the concentration is 2.5% by weight,
The mixture was stirred to obtain a uniform film-forming solution.

This membrane-forming solution was applied onto the same dry ultrafiltration membrane as in Example 1, left at room temperature to evaporate almost all welding, and then heated at a temperature of 60°C for 5 minutes to form a membrane according to the present invention. A composite semipermeable membrane was obtained.

The performance of this composite semipermeable membrane is that the removal rate is 82.0% and the water permeation rate is 2.5rr? /rri・day.

Example 7 A composite semipermeable membrane was obtained in the same manner as in Example 6, except that 1,4-butanediol was used as an additive and its concentration in the membrane forming solution was 10% by weight. The performance of this composite semipermeable membrane is that the removal rate is 85.6% and the water permeation rate is 1.
,4n? /m・day.

Example 8 In Example 6, various polysulfone copolymers having different ratios of repeating units of formula A and B repeating units were prepared and sulfonated to obtain sulfonated polysulfone copolymers. Using these, a composite semipermeable membrane was prepared in the same manner as in Example 6.

Table 3 shows the performance of these composite semipermeable membranes.

Comparative Example 1 Polysulfone having a repeating unit of formula C (P manufactured by UCC)
-1700) by the method of No5hay et al. (J.

Applied Polyyn+er Sci,, 20
．． 1885 (1976)).

That is, 60 g of the above polysulfone was dissolved in 3 QOml of 1,2-dichloroethane to prepare a polysulfone solution. Separately, 11.5 ml (0.07 mol) of triethyl phosphate and 83 ml of 1,2-dichloroethane were placed in a 200 ml Erlenmeyer flask with a stopcock, and 6 ml (0.07 mol) of sulfur trioxide solution was added to this while stirring while cooling in a water bath. 16 moles)
was added to prepare a sulfur trioxide solution.

Put 120 ml of 1,2-dichloroethane into a flask equipped with a stirrer, two dropping funnels, and a calcium chloride tube, and while stirring, add the above polysulfone solution from one dropping funnel and the above sulfur trioxide solution from the other dropping funnel. The mixture was added dropwise into the flask over a period of 1 hour, and stirring was continued for 2 hours at room temperature. The precipitated polymer was separated by filtration, washed with isopropyl alcohol and then with pure water.
It was dried at ℃ for 13 hours.

The sulfonated polysulfone copolymer thus obtained had an logarithmic viscosity of 0.91 when measured at 30°C as a 0.15% by weight N-methyl-2-pyrrolidone solution.
The ion exchange capacity was 1.0 meq/g.

A composite semipermeable membrane was prepared in the same manner as in Example 6 using this sulfonated polysulfone. Membrane performance has a removal rate of 84
, 3%, and the water permeation rate was 1.2 mr#·day.

Example 9 Glycerin or A membrane forming solution was prepared by adding and dissolving 1,4-butanediol at various concentrations.

A composite semipermeable membrane was prepared in the same manner as in Example 6 using these membrane forming solutions. Membrane performance is shown in Table 4.

For comparison, Table 4 also shows the performance of a composite semipermeable membrane prepared in the same manner using a membrane forming solution without additives.

Example 10 A 1.0% by weight ethylene glycol monomethyl ether solution of the sulfonated polysulfone copolymer consisting of 43 mol% of repeating units of formula B and 57 mol% of repeating units of formula B obtained in Example 8 was prepared. When preparing a composite semipermeable membrane using the membrane-forming solution, the membrane-forming solution was applied onto a dry ultrafiltration membrane in exactly the same manner as in Example 8, except that the polymer concentration in the membrane-forming solution was changed. A membrane was prepared. Table 5 shows the performance of each of the composite semipermeable membranes thus obtained.

Table 5 Example 11 1 g of the sulfonated polysulfone copolymer consisting of 17 mol % of the repeating units of formula A1 and 83 mol % of the repeating units of NiB obtained in Example 8 was mixed with 99 g of ethylene glycol monomethyl ether and N,N- Dimethylformamide Ig
Further, 2.5 g of glycerin was added thereto, and foreign matter was removed using a 10 ttm filter paper to prepare a uniform membrane forming solution.

In the same manner as in Example 6, this membrane forming solution was applied onto a dry ultrafiltration membrane at a temperature of 25°C, and after evaporating almost all the solvent at a temperature of 25°C, it was heated at 60°C for 5 minutes. The solvent was removed to obtain a composite semipermeable membrane.

The performance of this composite semipermeable membrane is that the removal rate is 92.8% and the water permeation rate is 0.5 n? /rd day.

Example 12 A polysulfone copolymer consisting of 57 mol% of repeating units and 43 mol% of NiB repeating units was prepared in the same manner as in Example 6 except that resorcinol was used instead of hydroquinone. . This was sulfonated in the same manner as in Example 6 to obtain a sulfonated polysulfone copolymer having a logarithmic viscosity of 0.93 and an ion exchange capacity of 0.98 meq/g.

A composite semipermeable membrane was prepared in the same manner as in Example 6 using this copolymer. The membrane performance is a removal rate of 90.3% and a water permeation rate of 1.8 rd/n?・It was day.

Example 13 In Example 6, a polysulfone copolymer consisting of 57 mol% of repeating units and 43 mol% of repeating units of NiB was prepared in the same manner as in Example 6, except that catechol was used instead of hydroquinone. This was prepared and sulfonated in the same manner as in Example 6 to obtain a sulfonated polysulfone copolymer having a logarithmic viscosity of 1.02 and an ion exchange capacity of 1.03 milliequivalents/g.

Using this copolymer, a film thickness of 0 was obtained in the same manner as in Example 6.
．． A composite semipermeable membrane with a 3 μm semipermeable membrane was obtained.

The performance of this composite semipermeable membrane is that the removal rate is 90.1% and the water permeation rate is 1.8n? /rrr・day.

Example 14 Repeating unit A + 43 mol% obtained in Example 8 and 2 B
10 g of a polysulfone copolymer consisting of 57 mol% of repeating units was dissolved in 97% concentrated sulfuric acid, and reacted with stirring for 4 hours to obtain a dark brown viscous reaction mixture. 10 after completion of reaction
The reaction mixture was placed in a water bath to coagulate the polymer, washed with pure water until the washing solution became neutral, and incubated at 60°C for 7
After drying for an hour, the logarithmic viscosity was 1.03, and the ion exchange capacity was 1.
A sulfonated polysulfone copolymer with a weight of 0 meq/g was obtained.

1.0 g of this sulfonated polysulfone copolymer was dissolved in 99.5 g of ethylene glycol monomethyl ether, and 2.5 g of glycerin was further added and dissolved therein to prepare a film forming solution. A composite semipermeable membrane was prepared in the same manner as in Example 6 using this membrane forming solution.

The performance of this composite semipermeable membrane is that the removal rate is 90.3% and the water permeation rate is 1.7r+? /m・day.

Example 15 (Evaluation of heat resistance) After immersing the composite semipermeable membrane obtained in Example 6 and the composite semipermeable membrane (b) obtained in Example 8 in hot water at 95°C for 30 minutes, the removal rate and The water permeation rate was measured. Furthermore, the operation of immersing in hot water for 30 minutes was repeated, and the removal rate and water permeation rate were measured in the same manner.

As a result, the performance of the composite semipermeable membrane of Example 6 was as follows: before this hot water treatment, the removal rate was 82.0%, and the water permeation rate was 2.5n? /
During hot water immersion 5 times for n-r days, the removal rate was 82.3-82.6%, and the water permeation rate was 2.4-2.5n?
/rr?・There was no substantial change in the number of days.

Furthermore, the performance of the composite semipermeable membrane (b) of Example 8 was as follows: before this hot water treatment, the removal rate was 94.0%, the water permeation rate was 1°5,
f/, f day, during 5 hot water immersions, the removal rate was 95.5 to 95.8%, the water permeation rate was 1.2 to 1°4 cd/m day, and substantially There was no change.

(Acid resistance) A composite semipermeable membrane obtained in the same manner as the composite semipermeable membrane ('b) of Example 8 was immersed in distilled water for 2 hours, and then 0.5
After being immersed in an aqueous N-hydrochloric acid solution for 2 hours, the membrane performance with respect to an aqueous sodium chloride solution was measured under the same conditions as in Example 1. As shown in Table 6, the composite semipermeable membrane of the present invention has
It is understood that the membrane performance does not change before and after immersion, indicating that it has excellent acid resistance.

(Alkali resistance) A composite semipermeable membrane obtained in the same manner as the composite semipermeable membrane (b) of Example 8 was immersed in distilled water for 2 hours, and then 0.5
After being immersed in an aqueous N-sodium hydroxide solution for 2 hours, the membrane performance with respect to an aqueous sodium chloride solution was measured under the same conditions as in Example 1. As the results are shown in Table 6, it is understood that the composite semipermeable membrane of the present invention has excellent alkali resistance, with membrane performance unchanged before and after immersion.

(Chlorine resistance) After immersing the composite semipermeable membrane +a) obtained in Example 9 in distilled water for 2 hours, and then immersing it in an aqueous solution containing 1100 pp of chlorine ions at a temperature of 25°C for 4 weeks, Membrane performance was measured for an aqueous sodium chloride solution under the same conditions. Removal rate is 90.6%, water permeation rate is 1.8m/rr!
・There was virtually no change on the day. Similarly, when the chloride ion concentration is 110,000 pp, the removal rate is 88.
3%, and the water permeation rate was 2.2 rrr/d·day. We also investigated changes in membrane performance over time, but no substantial changes were observed. Therefore, it is understood that the semipermeable membrane of the present invention has excellent chlorine resistance.

(Drying resistance) The composite semipermeable membrane (b) obtained in Example 8 was immersed in distilled water for 2 hours, then immersed in 0.5 N hydrochloric acid aqueous solution at 25°C for 2 hours, and washed with distilled water. Thereafter, the membrane was dried at a temperature of 25° C. for 2 hours. After this dry membrane was immersed in water and re-wetted, the membrane performance was as follows: removal rate 99.5%, water permeation rate 0.3n?
It was 10r/day.

Reference Example The polysulfone ultrafiltration membrane having the repeating unit represented by the formula C used in Example 1 had a removal rate of 0 when a 0.5% aqueous sodium chloride solution was treated at a temperature of 25°C and a pressure of 20 kg/cnf. .2%, water permeation rate is 17. I
n? /rr?・However, when this ultrafiltration membrane was immersed in ethylene glycol monomethyl ether and then immersed for 6 minutes at 60°C, the membrane performance was as follows: removal rate was 2.0%, water permeation rate was 0.9n (/ffr).・It was day.

In addition, after immersing the ultrafiltration membrane in ethylene glycol monomethyl ether containing 1% (1%) of glycerin,
It was immersed for 6 minutes at 0°C. The membrane performance was a removal rate of 0.8% and a water permeation rate of 9.3 m/day.

Claims (11)

[Claims] (1) Repeating unit A ▲There are mathematical formulas, chemical formulas, tables, etc.▼A A sulfonated polysulfone obtained by sulfonating a polysulfone consisting of the same, and an alkylene glycol alkyl ether that may contain a small amount of an aprotic polar organic solvent. A sulfonated polysulfone characterized in that a membrane-forming solution containing a water-soluble and low-volatility compound as an additive is applied onto a dried support membrane, and then an organic solvent is evaporated from this membrane-forming solution. A method for manufacturing a composite semipermeable membrane. (2) Sulfonated polysulfone has 0.5g of N-
A patent claim characterized in that a solution dissolved in 100 ml of methyl-2-pyrrolidone has a logarithmic viscosity of 0.2 or more and an ion exchange capacity of 2.3 milliequivalents/g or less when measured at 30°C A method for producing a sulfonated polysulfone composite semipermeable membrane according to item 1. (3) The sulfone according to claim 1, wherein the sulfonic acid group of the sulfonated polysulfone is represented by the formula -SO_3M (where M represents hydrogen, an alkali metal, or tetraalkylammonium). A method for producing a polysulfone composite semipermeable membrane. (4) Claim 1, characterized in that the additive is at least one selected from the group consisting of polyhydric alcohols, polyalkylene glycols, carboxylic acids, salts thereof, hydroxycarboxylic acids and salts thereof. A method for producing a sulfonated polysulfone composite semipermeable membrane. (5) The method for producing a sulfonated polysulfone composite semipermeable membrane according to claim 1, wherein the additive is an inorganic salt. (6) Repeating unit A ▲There are mathematical formulas, chemical formulas, tables, etc.▼A and Repeating unit B ▲There are mathematical formulas, chemical formulas, tables, etc.▼A_1 A sulfonated polysulfone copolymer made by sulfonating a linear polysulfone copolymer consisting of A membrane forming solution containing an alkylene glycol alkyl ether, which may contain a small amount of an aprotic polar organic solvent, and a water-soluble and low-volatility compound as an additive, is applied onto a dried support membrane. 1. A method for producing a sulfonated polysulfone composite semipermeable membrane, which comprises coating the membrane-forming solution, and then evaporating an organic solvent from the membrane-forming solution. (7) The sulfonated polysulfone composite half according to claim 6, wherein the linear polysulfone copolymer consists of 10 mol% or more of repeating units A and 90 mol% or less of repeating units B. Method for producing a permeable membrane. (8) Sulfonated polysulfone has 0.5g of N-
A patent claim characterized in that a solution dissolved in 100 ml of methyl-2-pyrrolidone has a logarithmic viscosity of 0.2 or more and an ion exchange capacity of 2.3 milliequivalents/g or less when measured at 30°C A method for producing a sulfonated polysulfone composite semipermeable membrane according to item 6. (9) Claim 6, characterized in that the sulfonic acid group possessed by the sulfonated polysulfone copolymer is represented by the formula -SO_3M (where M represents hydrogen, an alkali metal, or tetraalkylammonium). The method for producing the sulfonated polysulfone composite semipermeable membrane described above. (10) Claim 6, characterized in that the additive is at least one selected from the group consisting of polyhydric alcohols, polyalkylene glycols, carboxylic acids, salts thereof, hydroxycarboxylic acids and salts thereof. A method for producing a sulfonated polysulfone composite semipermeable membrane. (11) The method for producing a sulfonated polysulfone composite semipermeable membrane according to claim 6, wherein the additive is an inorganic salt.