JPH0565213B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a composite semipermeable membrane useful as a reverse osmosis membrane. In particular, it can contribute to the production of ultrapure water used in semiconductor manufacturing, the desalination of canned water, the recovery of effective substances, and the closure of wastewater. [Prior art] Cellulose acetate has been used in reverse osmosis membranes that have been used industrially for producing ultrapure water for the electronics industry, desalinating canned water, desalinating seawater, recovering valuables, and reusing sewage. Examples of asymmetric membranes made from the above include the lobe-type membranes described in US Pat. Nos. 3,133,132 and 3,133,137. However, this cellulose acetate membrane requires an operating pressure of 30 kg/cm ² or more, which increases the cost of water production in the fields of ultrapure water production for the electronics industry and the desalination of plain water, and also has poor hydrolysis and microbial resistance. There was a problem. Research into new materials to compensate for these shortcomings has been actively conducted mainly in the United States and Japan, but examples include aromatic polyamide, polyamide hydrazide (U.S. Pat. No. 3,567,632), polyamic acid (Japanese Patent Application Laid-Open No.
37282 Publication), crosslinked polyamic acid (Special Publication No. 1986-
3769), polyimidazopyrrolone, polysulfonamide, polybenzimidazole, polybenzimidazolone, polyarylene oxide, etc.
Although a material that improves some of its drawbacks has not been obtained, it is inferior to lobbed cellulose acetate membranes in terms of selective separation and permeability. On the other hand, a composite semipermeable membrane has been developed, which is a type of semipermeable membrane different from the lobe type, in which a microporous support membrane is coated with an ultra-thin membrane (active layer) that substantially controls membrane performance.
For composite membranes, it is now possible to select the optimal material for the active layer and microporous support membrane for each application.
There are advantages such as the ability to dramatically improve the amount of water produced by making the active layer thinner. At present, composite semipermeable membranes with cross-linked aramid active layers that have desalination performance and water generation capacity superior to cellulose acetate membranes have appeared (for example, U.S. Patent No.
4277344 and 4761234). However, although this type of membrane has very high desalination performance, it is not as durable against chlorine, which is commonly used in sterilization, which is extremely important in the process, as cellulose acetate membranes. This drawback can be overcome by advanced pretreatment processes in relatively large-scale plants such as ultrapure water production for the electronics industry, can water desalination, and seawater desalination, and reverse osmosis membranes are now mainstream. However, in the field of small ultra-pure water production equipment, small equipment that uses tap water containing chlorine as water supply, such as home water purifiers, and fields that require the input of chlorine, such as wastewater treatment. The problem is that the active layer quickly changes and the salt removal rate decreases, making it difficult to use the membrane or increasing the cost of water production. That is, it became necessary to develop a composite reverse osmosis membrane having the following characteristics. (i) Chlorine resistance comparable to cellulose acetate membrane (ii) Water permeability (high water production) that can be operated at low operating pressure (usually 15 kg/cm ² or less) (iii) High salt removal rate comparable to cellulose acetate membrane Recently, various studies have been made to satisfy the characteristics of . In recent years, composite membranes using piperazine polyamide in the active layer have been proposed as chlorine-resistant membranes and have attracted attention (for example,
500062, U.S. Patent No. 4259183, PB
Report 80−127574, PB Report 288387). This membrane has good chlorine resistance, can be sterilized by constant addition of chlorine, and can produce a high amount of water at low pressure.
After this, research into composite membranes using piperazine-based polyamide materials progressed, and a reverse osmosis membrane with improved salt removal rate and water production capacity was developed (for example,
20160, US Pat. No. 4,758,343, US Pat. No. 4,857,363). However, these membranes have a low rejection rate of common salt (sodium chloride), about 50% for the former and about 70-80% for the latter, and although they are suitable for applications such as softening hard water, they are not practical for desalination applications. There are problems, particularly in applications for producing ultrapure water, such as this low desalination rate or the resulting ability to remove organic components. In addition, research has progressed on a reverse osmosis membrane that uses polypiperazine amide material and aims to achieve a high salt removal rate (Japanese Patent Application Laid-open No. 62-49909).This membrane has an improved manufacturing method and has a salt removal rate of 90%. However, it was not as good as the cellulose acetate membrane, which has a desalination rate of about 95%, and was insufficient for desalination purposes. On the other hand, polyethylene diamine amide membranes have been proposed as membranes that also have chlorine resistance (for example,
JP-A-58-24303, JP-A-59-26101, JP-A-59-179103, PB Report 83-
243170). Although this membrane has high desalination properties comparable to cellulose acetate membrane, it has poor water permeability and requires a high operating pressure of 30 kg/cm ² or more to produce a certain amount of water. The performance was not superior to that of . In order to improve water permeability, a copolymer material with an amine composition of piperazine and ethylenediamine was also considered, but it was not possible to achieve both high desalination and high water production. [Problems to be Solved by the Invention] The purpose of the present invention is to provide a high-performance reverse osmosis membrane that has good chlorine resistance, sufficient water permeability even at low operating pressures, high salt removal rate and separation performance, and a method for producing the same. The goal is to provide the following. [Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. (1) In a composite semipermeable membrane consisting of a microporous support membrane and an ultra-thin membrane covering the support membrane, the ultra-thin membrane is mainly composed of polyamide obtained by polycondensing piperazine and ethylenediamine with a difunctional acid halide, and The molar ratio of the structural units of ethylenediamine polyamide to the structural units of polyamide is 0.01 or more and 0.25 or less, and the amount of water produced at an operating pressure of 10 Kg/cm ² is 0.8 m ³ /m ² ·day or more, 1.5 m ³ /m ² - A composite semipermeable membrane characterized by exhibiting a salt rejection rate of 90% or more and 99% or less in 0.05% by weight saline solution. (2) A method for producing a composite semipermeable membrane according to 1 above, wherein the microporous support membrane contains piperazine and ethylenediamine and contains 0.01% by weight or more of a compound represented by the formula [] at 1.0% by weight. % or less, and then coated with an organic solvent solution mainly consisting of a difunctional acid halide, and an interfacial polycondensation reaction to form a polyamide as an active layer. Method. (In the formula, A and A' represent a benzene ring or a naphthalene ring, and may have an alkyl group. X is -O-,
−CH ₂ −. ) As a result of intensive research, the inventors of the present application have developed a composite semipermeable membrane having an ultra-thin membrane (active layer) mainly composed of a copolyamide obtained by reacting piperazine and ethylenediamine as amine components with a bifunctional acid halide. By adjusting the composition ratio of piperazine and ethylenediamine within a certain range and mixing specific additives with the amine component, a reverse osmosis membrane with good salt removal rate and water production amount can be obtained, and the uniformity of membrane performance can be improved. They discovered this and completed the present invention. In the composite semipermeable membrane of the present invention, the main component of the ultra-thin membrane (active layer) covering the microporous support membrane is a copolyamide polycondensed with a bifunctional acid halide, that is, a polypiperazine amide represented by the following formula [ ], polyethylene diamine amide [ ]. (In the formula, R is a substituted or unsubstituted aromatic hydrocarbon.) In order to achieve the object of the present invention, the molar ratio of the structural unit [ ] of polyethylenediamine amide to the structural unit [ ] of polypiperazine amide is
Must be greater than or equal to 0.01 and less than or equal to 0.25. When the molar ratio of the structural unit of formula [] to the structural unit of formula [] is 0.01 or less, water permeability increases and the desalination rate tends to decrease. When the molar ratio of is 0.25 or more, the opposite tendency is shown. In the present invention, the ultra-thin film layer (active layer) is formed by applying an aqueous solution containing piperazine and ethylenediamine to a microporous support membrane, and then applying a solution containing a difunctional acid halide to form an interfacial layer with the amino compound. Although it is formed by a condensation reaction, it is preferable to copolymerize a crosslinked polyamide using a trifunctional or higher functional acid halide in order to increase the strength and insolubility of the ultra-thin film. The difunctional acid halide preferably has a substituted and/or unsubstituted aromatic ring. Aromatic substituents and substitution positions are not particularly limited,
Although it is generally preferable that the substituent is not present, examples of substituents that do not adversely affect performance include lower alkyl groups such as methyl and ethyl groups, methoxy groups,
It can be arbitrarily selected from ethoxy groups, sulfonic acid groups, carboxylic acid groups, halogens such as fluorine, chlorine, bromine, and iodine, and nitro groups. The position of the substituent is not particularly limited, but preferably a position that does not cause steric interference. Preferred bifunctional acid halides include, for example:
Terephthalic acid halide, isophthalic acid halide,
Examples include naphthalenedicarboxylic acid halide, diphenyldicarboxylic acid halide, pyridinedicarboxylic acid halide, benzenedisulfonic acid halide, and chlorosulfonylisophthalic acid halide. However, in view of the performance of the composite reverse osmosis membrane, the bifunctional acid halide is preferably terephthalic acid halide or isophthalic acid halide, and more preferably terephthalic acid halide. Further, as mentioned above, in order to increase the strength and insolubility of the ultra-thin film, it is preferable to include a crosslinked polyamide using a trifunctional or higher functional acid halide, such as trimesic acid halide, benzophenone tetracarboxylic acid halide, trimethic acid halide, pyromethic acid halide, etc. Examples include aromatic polyfunctional acid halides such as halides, but trimesic acid halide is preferred in consideration of membrane performance and film formability. One of the functional groups in this trifunctional or more functional acid halide does not form an amide bond and may be, for example, a carboxylic acid group. Note that the molar ratio of the trifunctional or higher functional acid halide to the bifunctional acid halide is preferably 0.1 to 1.0,
More preferably it is 0.15 to 0.7. The thickness of the ultra-thin film (active layer) formed by the above-mentioned interfacial polycondensation reaction between amine and acid halide is 5n.
It can be arbitrarily selected between m and 1000 nm, but
If it is thin, it will easily cause defects, and if it is thick, water permeability will decrease, so from the viewpoint of balance, the thickness should be between 10nm and 300nm.
is preferred. In the present invention, the microporous support membrane is a layer that does not substantially have separation performance, and is used to impart strength to an ultra-thin film layer (active layer) that substantially has separation performance, Preferably, the support film has a structure in which it has uniform fine pores or gradually larger fine pores from one side to the other, and the size of the fine pores is 100 nm or less on one side. The above microporous support membrane is “Millipore Filter VSWP” (trade name) manufactured by Millipore.
``Ultra Filter UK10'' manufactured by Toyo Roshi Co., Ltd.
You can choose from a variety of commercially available materials, such as (trade name), but typically "Office of Saline Water Research and Development Progress Report" No. 359.
(1968).
The materials typically used are homopolymers or blends of polysulfone, cellulose acetate, cellulose nitrate, and polyvinyl chloride.
It is preferable to use polysulfone, which has high chemical, mechanical, and thermal safety. For example, a solution of polysulfone in dimethylformamide (DMF) is cast onto a tightly woven polyester cloth or non-woven cloth to a certain thickness, and then 0.5
By wet coagulation in an aqueous solution containing 2% by weight and 2% by weight of DMF, a microporous support membrane in which most of the surface has fine pores with a diameter of several tens of nanometers or less can be obtained. Next, the film forming method will be explained. In the first step of membrane formation, the microporous support membrane is coated with an aqueous solution containing piperazine and ethylenediamine (hereinafter referred to as composition (A)). A microporous support membrane may also be immersed. The concentration of piperazine and ethylenediamine in this composition (A) is preferably 1 to 10% by weight, but if the concentration is too low, membrane defects are likely to occur, and if it is too high, the water permeability of the composite semipermeable membrane will decrease. , more preferably 2 to 6% by weight. The composition ratio of piperazine and ethylenediamine may be such that the molar ratio of the structural units of polyethylenediamine amide to the structural units of polypiperazine amide is 0.01 or more and 0.25 or less. Ethylenediamine is 0.007 to 0.17 parts by weight, and as mentioned above, if the concentration of ethylenediamine is low, the salt removal rate will be low, and if the concentration is high, the water permeability of the composite semipermeable membrane will be reduced, so ethylenediamine is more preferably 0.05 to 0.1. Parts by weight. Further, it is preferable to add a compound represented by the formula [] to the composition because it improves the coating properties of the composition and the amount of water produced in the composite membrane. (In the formula, A and A' represent a benzene ring or a naphthalene ring, and may have an alkyl group. X is -O-,
−CH ₂ −. ) The compound represented by the formula [] may be cross-linked with -X- or other diradical to form a dimer to a pentamer, or may be a mixture thereof. The concentration of the compound represented by the formula [] is not particularly limited, but if it is included in a large amount in the composition, the active layer is likely to peel off after film formation, so it should be 1.0
It is preferably less than % by weight. Examples of the compound represented by the formula [ ] include the following. (R is a long chain alkyl group such as -C ₁₂ H ₂₅ ) In practice, the alkyl group may include a mixture of alkyl groups other than dodecyl group, or may include two or more alkyl groups. It is also possible to use a mixture of the above compounds. Among these, the formula that gives the highest performance composite membrane []
As a compound expressed by can be given. Furthermore, an alkaline metal compound may be added to the composition (A), which is effective as a scavenger for hydrochloric acid generated during the polymerization reaction for forming the active layer. Such alkaline metal compounds include hydroxides and weakly basic salts of sodium, potassium, etc., and trisodium phosphate is a preferred example. It is effective to add a surfactant to improve the wettability of the composition (A) onto the surface of the microporous support membrane so that the composition (A) can adhere uniformly. Among them, anionic surfactants are effective. is preferred. It can be selected from sodium dodecyl sulfate, sodium alkylbenzene sulfonate, etc., but sodium alkyl diphenyl ether disulfonate having the structure shown above is effective in obtaining good membrane performance. Further, a water-soluble organic solvent that does not deteriorate the microporous support membrane may be added to the composition. After coating the microporous support membrane with the composition (A), a draining step is generally provided to remove excess composition (A). Examples of methods for draining liquid include, for example, holding the membrane surface vertically and letting it flow naturally;
There are methods such as air blowing. Next, the microporous support membrane coated with composition (A) is air-dried. As a method for this, for example, after removing the excess composition (A) as described above, the film surface is continued to be held vertically and dried at room temperature. The degree of drying may be such that no aqueous solution (composition (A)) is seen on the microporous support membrane. If there are pools or droplets of the aqueous solution (composition (A)), there is a risk that an active layer will be formed on top of the aqueous solution. Drying with hot air is also possible, but care must be taken because excessive drying may impair the reproducibility of membrane performance and reduce water permeability. The temperature of hot air is in the range of 40-150℃, and the drying time is according to the method,
In other words, the drying speed varies depending on the heat introduction method and the type of dryer, so adjust the drying speed from 30 seconds to
Select within 60 minutes. Next, in the process, a water-immiscible organic solvent solution consisting mainly of difunctional acid halides is applied and in
A polyamide, which is an active layer, is formed by an interfacial polycondensation reaction between amines and acid halides in situ.
After removing the excess organic solvent solution of the polyfunctional acid halide by draining, the membrane is left to stand at room temperature and air-dried to obtain a composite semipermeable membrane. The concentration of the acid halide is not particularly limited, but if it is too low, the formation of the active layer made of crosslinked polyamide will be insufficient, which may be a drawback, and if it is too high, it is disadvantageous from a cost standpoint, so it should be 0.1 to
About 0.5% by weight is preferable. Considering the speed of the interfacial polycondensation reaction, approximately 10 seconds is sufficient for applying the water-immiscible organic solvent solution of acid halide, but in order to uniformly form an ultra-thin film (active layer), 30 seconds is sufficient. The above is preferable. In addition, the organic solvent is any solvent as long as it is immiscible with water, dissolves the acid halide and does not destroy the microporous support membrane, and can form a crosslinked polyamide through interfacial polycondensation. It's okay to be. Preferred examples include hydrocarbon compounds,
Examples include cyclohexane and trichlorotrifluoroethane, but in terms of reaction rate and solvent volatility, n-hexane and trichlorotrifluoroethane are preferably selected, and trichlorotrifluoroethane is more preferably selected from n-hexane and trichlorotrifluoroethane in view of the safety issue of flammability. It is fluoroethane. Although the composite semipermeable membrane obtained as described above can be used as is, it is preferable to remove unreacted residues by washing with water or the like. Next, methods for measuring characteristics related to the present invention will be summarized. (i) Rejection rate When an aqueous solution containing a solute is permeated through a membrane, the rejection rate is expressed by the vortex equation. Rejection rate (%) = (1 - permeated water concentration / raw water concentration) x 10
0 The salt concentration of the solution was determined by measuring electrical conductivity, and the concentration of organic matter was determined by a differential refractometer or TOC meter. (ii) Amount of water produced (water permeation rate) The amount of water produced is determined by measuring the weight of water passing through the membrane over time at 25°C, and converting it to the number of m ³ per 1 m ² in 24 hours. [Example] Reference example Taffeta made of polyester fibers measuring 30cm in length and 20cm in width (multifilament yarn of 150 denier in both warp and weft, weaving density: 90 pieces/inch vertically, 67 pieces/inch horizontally, thickness 160μ) ) was fixed on a glass plate, and 16% by weight of polysulfone (Udel-P3500 manufactured by Union Carbide) was placed on top of it.
A fiber-reinforced polysulfone support membrane (hereinafter abbreviated as FR-PS support membrane) was formed by casting dimethylformamide (DMF) solution to a thickness of 200μ at room temperature (20℃), immediately immersing it in pure water, and leaving it for 5 minutes. ). FR− obtained in this way
The pure water permeability coefficient between PS supports (thickness 210~215μ) is
0.005 to 0.01 when measured at a pressure of 1Kg/cm ² and a temperature of 25℃
g/ ^cm2・sec・atm. Example 1 A composition having 2.0% by weight of piperazine, 0.2% by weight of ethylenediamine, 0.1% by weight of sodium dodecyl diphenyl ether disulfonate, and 1.0% by weight of trisodium phosphate was applied to a FR-PS support membrane for 1 minute. The support membrane was stood vertically, and after removing excess aqueous solution from the surface of the support membrane, it was dried at 70°C for 30 seconds. Next, apply a trichlorotrifluoroethane solution containing 0.18% by weight of terephthalic acid chloride and 0.12% by weight of trimesic acid chloride so that the surface is completely wet, and then remove the excess solution by turning the membrane vertically. After that, it was washed with distilled water. Using the thus obtained composite semipermeable membrane as raw water, 500 ppm saline solution adjusted to pH 6.5, 10 Kg/cm ² ,
Reverse osmosis tests were conducted at 25°C. As a result, salt rejection rate is 96.0%, water permeation rate is 0.83
It showed a performance of m ³ /m ² ·day. Subsequently, the raw water was changed to 0.1% isopropyl alcohol aqueous solution and a reverse osmosis test was conducted under the same conditions. The results showed an exclusion rate of 56%.

[Formula] Sodium dodecyl diphenyl ether disulfonate Example 2 Ethylenediamine in the composition of Example 1 was 0.1
% by weight, a film was formed in the same manner as in Example 1, and a reverse osmosis test was conducted. As a result, the salt rejection rate was 95.5%,
It exhibited a water permeation rate of 1.00m ³ /m ² ·day. Example 3 A film was formed in the same manner as in Example 1 except that sodium dodecyl diphenelether disulfonate in the composition of Example 2 was changed to methylene bis(sodium naphthalene sulfonate) shown in the following formula, and a reverse osmosis test was conducted. I went. As a result, salt rejection rate is 95.9%, water permeation rate
It showed a performance of 0.90m ³ /m ² ·day.

[Formula] Example 4 Using the composition of Example 1, 1
Applied for minutes. After standing the support membrane vertically and removing excess aqueous solution from the surface of the support membrane, it was incubated at 80°C.
Dry for 30 seconds. Then terephthalic acid chloride 0.24
% by weight, and a trichlorofluoroethane solution containing 0.06% by weight of trimesic acid chloride was applied so that the surface was completely wetted, the membrane was then held vertically and excess solution was drained off, and then washed with distilled water. did. The reverse osmosis test results showed a salt removal rate of 92.9% and a water permeation rate of 1.25 m ³ /m ² ·day. Example 5 2.0% by weight of piperazine, 0.2% by weight of ethylenediamine, 0.1% by weight of methylene bis(sodium naphthalene sulfonate), and 0.04% by weight of sodium dodecyl diphenyl ether disulfonate in the FR-PS support membrane.
% by weight, 1.0% by weight of trisodium phosphate was applied for 1 minute. The support membrane was stood vertically, and after removing excess aqueous solution from the surface of the support membrane, it was dried at 80° C. for 30 seconds. Next, terephthalic acid chloride 0.30% by weight, trimesic acid chloride
A trichlorotrifluoroethane solution containing 0.20% by weight was applied so that the surface was completely wetted and maintained for 1 minute. Next, the membrane was turned vertically to remove excess solution by draining, and then washed with distilled water. Using the thus obtained composite semipermeable membrane as raw water, 500 ppm saline solution adjusted to pH 6.5, 10 Kg/cm ² ,
Reverse osmosis tests were conducted at 25°C. As a result, desalination rate is 95.7%, water permeation rate is 0.92
It showed a performance of m ³ /m ² ·day. Comparative Example 1 A membrane was formed in the same manner as in Example 1 except that a composition containing 1.0% by weight of piperazine, 0.1% by weight of sodium dodecyl phenyl ether disulfonate, and 1.0% by weight of trisodium phosphate was used, and a reverse osmosis test was performed. I went to As a result, the salt removal rate was 66.0%, and the water permeation rate was 1.57 m ² /m ² ·day. Comparative Example 2 A composition containing 2.0% by weight of piperazine, 0.1% by weight of sodium dodecyl diphenyl ether disulfonate, and 1.0% by weight of trisodium phosphate, and a composition containing 0.30% by weight of terephthalic acid chloride and 0.20% by weight of trimesic acid chloride. A film was formed using a fluoroethane solution in the same manner as in Example 1, and 500 ppm saline solution adjusted to pH 6.5 was used as raw water.
A reverse osmosis test was conducted under the conditions of 10Kg/cm ² and 25°C. I did a reverse osmosis test. As a result, desalination rate
It exhibited a performance of 87.0% and a water permeation rate of 1.58 m ³ /m ² ·day. Examples 6 to 8 After applying the composition to the support film in Example 5 and removing excess composition, drying was carried out at 70, 90, and 100°C.
The film was formed in the same manner. Adjusted to PH6.5
A reverse osmosis test was conducted using 500 ppm saline as raw water at 10 kg/cm ² and 25°C, and the performance shown in Table 1 was obtained.

[Table] Example 9 In Example 5, the weight ratio of terephthalic acid chloride and trimesic acid chloride was not changed, but the total concentration was changed to 0.3% by weight, and the film was formed in the same manner.
Use 500ppm saline solution adjusted to PH6.5 as raw water,
As a result of reverse osmosis test under the conditions of Kg/cm ² and 25℃,
It exhibited a desalination rate of 95.0% and a water permeation rate of 1.05 m ³ /m ² ·day. Examples 10 and 11 After applying the trichlorotrifluoroethane solution of terephthalic acid crotide and trimesic acid chloride in Example 5, the holding time was 10 seconds,
The time was changed to 20 seconds, and the film was formed in the same manner thereafter. Use 500ppm saline solution adjusted to PH6.5 as raw water, 10Kg/cm ² ,
Table 2 shows the results of a reverse osmosis test conducted at 25°C.

[Table] Example 12 Using the composition of Example 3, 1
Applied for minutes. After standing the support membrane vertically and removing excess aqueous solution from the surface of the support membrane, it was incubated at 70℃ for 30 minutes.
Dry for seconds. Then terephthalic acid claride 0.4
A trichlorotrifluoroethane solution containing 0.1% by weight of trimesic acid chloride was applied so that the surface was completely wetted and maintained for 1 minute. Next, the membrane was turned vertically to remove excess solution by draining, and then thoroughly washed with water. Similar reverse osmosis test results showed a salt rejection rate of 92.8% and a water permeation rate of ^1.15m3 / ^m2 .
showed the performance of the day. Example 13 Composition of Example 5 and terephthalic acid chloride
Using a trichlorotrifluoroethane solution containing 0.275% by weight and 0.225% by weight of trimesic acid chloride, a membrane was formed in the same manner as in Example 5, and a reverse osmosis test was conducted. The results showed a salt rejection rate of 96.3% and a water permeation rate of 0.81 m ³ /m ² ·day. Comparative Example 3 A film was formed in the same manner as in Example 1 using a composition containing 2.0% by weight of piperazine, 1.2% by weight of ethylenediamine, 0.1% by weight of sodium dodecyl diphenyl ether disulfonate, and 1.0% by weight of trisodium phosphate, and a reverse osmosis test was performed. I went to As a result, desalination rate
It showed performance of 96.0% and water permeation rate of 0.20m ³ /m ² ·day. Example 14 Using the membrane obtained in Example 5, PH was added in addition to common salt.
Magnesium chloride 1500ppm, magnesium sulfate 2000ppm, sodium sulfate 2000ppm adjusted to 6.5
Using this as raw water, a reverse osmosis test was conducted under the conditions of 10 kg/cm ² and 25°C. The obtained performance is shown in Table 3.

[Table] Example 15 Using the membrane obtained in Example 5, the membrane was operated for 600 hours under the same test conditions by adding sodium hypochlorite to the raw water to adjust the residual chlorine to 10 ppm and adjusting the pH to 6.5. The performance before and after adding chlorine shows a salt rejection rate of 96.2%.
96.8%, water permeation rate ^0.86m3 / ^m2・day is ^0.80m3 /
It was warm for m ² days. Furthermore, when the residual chlorine was set to 100 ppm and the membrane was operated for 60 hours, the salt rejection rate was 96.7% and the amount of water produced was 0.80 m ³ /m ² ·day, with no deterioration and the membrane had good chlorine resistance. Example 16 The raw water was made into 2.0% hydrogen peroxide solution, pH 6.5, and Example 5
Using the membrane obtained in the above, the membrane was operated at 3 kg/cm ² at 25° C. for 60 hours, and an aqueous peroxide resistance test was conducted. Evaluation pressure 10
Kg/cm ² , salt 500ppm, PH6.5, reverse osmosis performance before and after an aqueous peroxide test evaluated under the conditions of 96.0% salt removal rate, 95.9% water permeation rate, and 0.85%, respectively.
m ³ /m ² ·day was 0.87 m ³ /m ² ·day, showing good resistance. Example 17 The membrane obtained in Example 13 was cut into appropriate sizes,
The ultrathin film was peeled off by immersion in methylene chloride. This was filtered by suction filtration through a glass filter. The sample thus obtained was analyzed by ^C13 -NMR spectrum. As a result, the molar ratio of units derived from terephthalic acid and units derived from trimesic acid was 59:41, which was in good agreement with the molar ratio of 61:39 in the trichlorotrifluoroethane solution, which was the charging ratio. [Effects of the Invention] The composite semipermeable membrane of the present invention is a reverse osmosis membrane that has good chlorine resistance and provides a high salt removal rate and a sufficient amount of fresh water even at low operating pressures. Therefore, the composite semipermeable membrane of the present invention can be used in various applications such as small ultrapure water production equipment, small equipment that uses tap water containing chlorine as a supply water such as home water purifiers, and wastewater treatment applications. Can be used in the field.

Claims (1)

[Claims] 1. A composite semipermeable membrane consisting of a microporous support membrane and an ultra-thin membrane covering the support membrane, wherein the ultra-thin membrane is mainly composed of polyamide obtained by polycondensing piperazine and ethylenediamine with a difunctional acid halide. , and the molar ratio of the structural units of ethylenediamine polyamide to the structural units of piperazine polyamide is 0.01.
above, 0.25 or below, and the operating pressure is 10Kg/cm ^{2
The amount} of water produced ^in
m2・day or less, the salt elimination rate of 0.05% by weight saline solution is
A composite semipermeable membrane characterized by a performance of 90% or more and 99% or less. 2. The composite semipermeable membrane according to claim 1, wherein the polyamide obtained by polycondensing piperazine and ethylenediamine with a difunctional acid halide is further crosslinked with a trifunctional acid halide. 3. The composite semipermeable membrane according to claim 1, wherein the microporous support membrane is made of polysulfone. 4. The composite semipermeable membrane according to claim 1, wherein the difunctional acid halide is at least one selected from terephthalic acid and isophthalic acid. 5. The composite semipermeable membrane according to claim 2, wherein the trifunctional acid halide comprises trimesic acid. 6. A method for producing a composite semipermeable membrane according to claim 1, wherein the microporous support membrane contains piperazine and ethylenediamine and contains 0.01% by weight or more and 1.0% by weight of a compound represented by the formula []. A method for producing a composite semipermeable membrane, comprising: coating with an aqueous solution containing the following, and then coating with an organic solvent solution mainly consisting of a bifunctional acid halide, and forming a polyamide that will become an active layer by interfacial polycondensation reaction. . (In the formula, A and A' represent a benzine ring or a naphthalene ring, and may have an alkyl group. X is -O-,
−CH ₂ −. 7. The method for producing a composite semipermeable membrane according to claim 6, wherein the total concentration of piperazine and ethylenediamine in the aqueous solution is 1 to 10% by weight. 8. The method for producing a composite semipermeable membrane according to claim 6, wherein the difunctional acid halide is at least one selected from terephthalic acid and isophthalic acid. 9 A solution consisting mainly of difunctional acid halides is
The method for producing a composite semipermeable membrane according to claim 6, further comprising trimesic acid. 10. The method for producing a composite semipermeable membrane according to claim 6, wherein the solution mainly consisting of a difunctional acid halide is used at a concentration of 0.1 to 0.5% by weight. 11. The method for producing a composite semipermeable membrane according to claim 6, wherein the microporous support membrane is made of polysulfone. 12 The compound represented by formula [] is The method for producing a composite semipermeable membrane according to claim 6.