KR19980020428A - Manufacturing Method of Polyamide Composite Membrane - Google Patents

Abstract

An object of the present invention is to prepare a crosslinked polyamide-based composite tritium membrane obtained by interfacial polymerization of a polyfunctional amine solution and a polyfunctional acid halide solution on a surface of a microporous substrate, and has a carbon number as a solvent of the polyfunctional acid halide solution. The present invention relates to a method for producing a polyamide composite separator comprising mixing structural isomers of 8 or more n-alkanes and saturated and unsaturated hydrogen carbonates having 8 carbon atoms and adding dimethyl ether and butyl ether as additives.

Description

Manufacturing Method of Polyamide Composite Membrane

The present invention relates to a method for producing a crosslinked polyamide-based composite physical film obtained by interfacial polymerization of a polyfunctional amine solution and a polyfunctional acid halide solution on a surface of a microporous substrate.

Recently, due to industrial development and urban concentration of the population, there is a serious need for securing a water source and producing high quality pure water due to water pollution caused by industrial wastewater and household sewage and lack of water due to increase and decrease of precipitation. Therefore, reverse osmosis membrane method, electrodialysis method, evaporation method, freezing method and ion exchange method are used for the removal of pollutants in the water.However, research on reverse osmosis membrane method that can be automated due to low energy consumption and easy operation in case of lack of water resources and pollution of water resources It is actively.

If the COD (Chemical Oxygen Demand) of raw water is 4 ~ 10ppm and TDS is more than 110ppm, it is economical as well as high quality pure water by producing reverse osmosis membrane method and ion exchange method. Can be. In particular, when the concentration of alkylbenzene sulfonate is high when organic matter is contaminated, and when microorganisms are breeding, the contamination of activated carbon and ion exchange resin is severe. Therefore, it is effective to produce high pure water by ion exchange method after treatment with reverse osmosis membrane method.

In addition, when the reverse osmosis membrane method is used, the water quality is better than the quality of river water, ground water and tap water, and thus, pure water with little organic matter and microorganisms can be produced as well as the efficiency of pure water production. Reverse osmosis membranes have a high permeability to water in liquid-liquid systems and do not permeate microorganisms, colloidal particles, salts and organics dissolved in water, and can be removed, and are used as separation membranes applied to solute separation within 10 kPa. The driving force of the separation process by the membrane is classified by pressure such as microfiltration or ultrafiltration and by concentration difference such as gas separation and permeation evaporation. However, in reverse osmosis, pressure difference and concentration difference act as driving force. Reverse osmosis membranes are membranes that can remove monovalent ions or salts that cannot be removed by microfiltration or ultrafiltration membranes. Water supply for large industrial complexes in new power plants and coastal landfills, industrial wastewater treatment, ultrapure water production for semiconductor cleaning, and other It can be considered as a source of water in the process (milk enrichment, extraction of specific substances, manufacturing of pharmaceuticals), etc., and a reverse osmosis system can be actively used in case of water shortage due to continuous deterioration of water and construction of subsequent stages.

In the early 1960s, the first reverse osmosis membrane, asymmetric cellulose diacetate membrane, was developed by Sourirajan in Lobe, and the cellulose diacetate membrane is inexpensive, but vulnerable to microorganisms. It is easily hydrolyzed under strong bases and has a narrow range of temperature and pH, which is used through the modification of cellulose and alloys of various celluloses, but these disadvantages cannot be completely overcome. Since then, studies have been actively conducted on polyamides, polyurethanes, aromatic polysulfones, aromatic polyamides, and the like, to compensate for the disadvantages of cellulose membranes.

Currently, composite membranes having aromatic polysulfone as a porous support membrane and aromatic polyamide as active layers have been developed and commercialized. That is, the composite membrane is composed of a support layer for maintaining mechanical strength and an active layer having selective permeability. The method for producing a composite membrane includes a thin layer dispersion method, an immersion coding method, a vapor deposition method, a Langmuir-Blodgett method, and an interfacial polymerization method. In particular, in the reverse osmosis membrane, an interfacial polymerization method is mainly used for producing a composite membrane. The reverse osmosis composite membrane by the open polymerization method was prepared by reacting an aqueous polyethyleneamine solution with toluene diisocyanate in a nucleic acid. Film Tech Co., Ltd., which developed a composite membrane using a reactive monomer, impregnated a polysulfone-based microporous substrate with an aqueous polyfunctional amine solution such as m-phenylenediamine or p-phenylenediamine, and the polyfunctional acid on the substrate. Interfacial polymerization occurs with the amine by applying the bromide solution. This crosslinked polyamide composite membrane has the best performance among currently known composite membranes for reverse osmosis.

However, this crosslinked polyamide composite membrane has a large drawback in its manufacturing process. It is that nucleic acids or freons are used as the most common solvents of polyfunctional acid halide solutions. Nucleic acid has a low flash point and boiling point, so there is a high risk of explosion or fire, which is inappropriate from an economic point of view due to safety measures. Freon-based solvents, on the other hand, are most commonly used because they are highly safe and easy to manufacture good performance membranes. However, their use has recently become a major environmental pollutant due to the destruction of the ozone layer. Freon is nonflammable, non-toxic, easily evaporated or liquefied, has very specific properties such as having proper lipophilic properties and is used in many applications such as detergents, refrigerants, foaming agents, and the like. However, the Freon system has been designated as having a serious impact on the global environment because of its destruction of the stratospheric ozone layer. Ultraviolet rays whose wavelengths are shorter than 300 nm emitted from the sun are absorbed by the ozone layer and do not reach the ground. This ultraviolet light contains strong energy and is very harmful to living organisms.

Thus, ozone depletion is a serious problem for life on Earth. For this reason, the Vienna Convention on the Protection of Ozone Layers (1985), the Montreal Protocol (1987) and the Helsinki Declaration (1989), which are called by the United Nations Environment Planning (UNEP), were chosen. The use of freon systems is therefore limited on a global scale, and the Helsinki Declaration prohibits the production and consumption of all types of freon systems used for industrial use until AD 2000. In light of this situation, it is urgent to develop alternative materials for freon in composite membrane production.

As a specific example of the use of a freon system in the method for producing a composite osmosis membrane, Japanese Unexamined Patent Publication No. 63-36803 discloses that m-phenylenediamine or p-phenylenediamine is substituted with trimesoyl chloride or isophthaloyl chloride on a polysulfone substrate. A method of interfacial polymerization is shown, wherein trichlorotrifluoroethane is used as a solvent of an acid chloride. Japanese Unexamined Patent Application Publication No. 1-30707 uses piperazine as an amine, but trichlorotrifluoroethane is also used as a reaction solvent. However, Japanese Patent Application Laid-Open No. 62-49909 uses polysulfone microporous substrate to simultaneously crosslink an amano compounds such as polyvinyl alcohol and piperazine using trimezoyl chloride. In this method, n-nucleic acid, cyclonucleic acid, and the like were used as a solvent of trimesoyl chloride. The use of such low-boiling hydrocarbons is a process of evaporating the solvent after contacting a polyfunctional acid halide solution with a reactive monomer or polymer in the composite membrane preparation surface by interfacial polymerization on a substrate. Medium boiling point solvents generally have a low flash point and thus have a safety problem. In Japanese Patent Application Laid-Open Nos. 59-179103 and 63-36803, a high boiling point solvent is used in addition to low boiling point solvents such as trichlorotrifluoroethane and n-nucleic acid as a solvent for the crosslinking agent.

An object of the present invention is to replace the existing solvent that destroys the ozone layer with another solvent, and to have a high flash point, the use of a safe solvent to handle the high reverse osmosis performance (salt removal rate and water permeation) of the composite membrane production method The purpose. Physical properties of the solvent suitable for the purpose of the present invention is easy to handle the solvent with a flash point of 10 ℃ or more, the boiling point is 200 ℃ or less the time required for the evaporation of the solvent is short and the evaporation temperature of the solvent has a low effect on the membrane performance Should not be given.

Hereinafter, the present invention will be described in detail.

In preparing a crosslinked polyamide-based composite osmosis membrane obtained by interfacial polymerization of a polyfunctional amine solution and a polyfunctional acid halide solution on a surface of a microporous substrate, n-alkane having 8 or more carbon atoms as a solvent of the polyfunctional acid halide solution ( In the normal alkane), structural isomers of saturated and unsaturated hydrocarbons having 8 carbon atoms are mixed. Preferred examples of the hydrocarbon solvent include 2,2-dimethylnucleic acid, 2,5-dimethylnucleic acid, hexamethylethane and 2-methylheptane in n-octane, n-nordan, n-decane, n-undecane, n-dodecane and the like. It is preferable to use a solvent in which 0.1 to 30.0% by weight of 4-methylheptane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane and the like are mixed, and particularly preferably 0.1 to 15.0% by weight. It is possible to obtain a higher water permeability by adding 0.1 to 8.0% by weight of ethylmethyl ether and butylethyl ether as additives, and particularly preferably a mixture of 3.0 to 6.0% by weight. The reverse osmosis performance of the membrane prepared with the solvent made in such a range was evaluated by measuring the salt excretion rate and water permeability of a 2,000 ppm saline (NaCl) aqueous solution at a pressure of 25 ° C. and 15 kg / cm ² . The salt rejection rate was calculated by the following equation.

Salt Exclusion Rate (%) = (1-C _P / C _F ) × 100

Where C _F is the NaCl concentration in the feed water and C _P is the NaCl concentration in the permeate. The composite separator prepared according to the present invention has a salt excretion rate similar to that of the composite separator prepared by the conventional method, but has a higher water permeation rate.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example and a comparative example.

Example 1

Cast 10% by weight solution of dimethylformamide and polysulfone on a polyester nonwoven fabric to a thickness of about 100 μm, immediately immerse it in a water bath at 30 ° C. to solidify it, and then rinse the nonwoven reinforced polysulfone microporous substrate sufficiently with water. After substituting the solvent and water in, it was dried at room temperature. The polysulfone microporous substrate thus obtained was immersed in an aqueous solution of m-phenylenediamine having a concentration of 4.0% by weight for 20 hours, and then 1.0% by weight of trimezoyl chloride solution (solvent; n-octane: 2-methylheptane: ethylmethyl ether). = 85.0: 10.0: 5.0 wt%) was applied for 5 minutes. The composite membrane thus prepared was dried at room temperature. The salt rejection rate and water permeation rate of the thus prepared composite membrane showed 99.2% and 1145 L / m ² · day, respectively.

Example 2

A polyester nonwoven fabric-reinforced composite membrane was manufactured in the same manner as in Example 1, except that n-nonane: 2,2dimethylnucleic acid: butylethyl ether = 80.0: 15.0: 5.0 wt% was used as a solvent of the trimesoyl chloride solution. . The salt rejection rate and water permeation rate of this composite membrane were 99.3% and 1145 L / m ² · day, respectively.

Example 3

A polyester nonwoven fabric-reinforced composite membrane was manufactured in the same manner as in Example 1, except that n-decane: 2,5dimethylnucleic acid: ethylmethyl ether = 80.0: 14.0: 6.0% by weight as a solvent of the trimesoyl chloride solution. . The salt rejection rate and water permeation rate of this composite membrane were 99.2% and 1160 L / m ² · day, respectively.

Comparative Example 1

A polyester nonwoven fabric-reinforced composite membrane was prepared in the same manner as in Example 1 except that only n-octane was used as a solvent of the trimesoyl chloride solution. The salt rejection rate and water permeation rate of this composite membrane were 99.3% and 910 L / m ² · day, respectively.

Comparative Example 2

A polyester nonwoven fabric-reinforced composite membrane was manufactured in the same manner as in Example 1 except that only Freon was used as a solvent of the trimesoyl chloride solution. The salt rejection rate and water permeation rate of this composite membrane were 99.2% and 860 L / m ² · day, respectively.

Claims (4)

In the method for producing a crosslinked polyamide-based composite osmosis membrane obtained by interfacial polymerization of a polyfunctional amine solution and a polyfunctional acid halide solution on a surface of a microporous substrate, n having a carbon number of 8 or more as a solvent of the polyfunctional acid halide solution -A method for producing a polyamide-based composite separator, characterized in that the alkanes and the structural isomers of saturated and unsaturated hydrogen carbonates having 8 minor atoms are mixed and ethylmethyl ether and butylethyl ether are added as additives. The solvent of claim 1 wherein the solvent of the polyfunctional acid halide solution is a mixture of n-octane, 2-methylheptane and methylethyl ether, the weight percent of 2-methylheptane is 0.1-30.0 and the weight percent of ethylmethyl ether is 0.1 Method for producing a polyamide-based composite separator, characterized in that ~ 8.0. The solvent of claim 1 wherein the solvent of the polyfunctional acid halide solution is a mixture of n-nonane, 2,2-dimethylnucleic acid and butylethyl ether, the weight percent of 2,2-dimethylnucleic acid is 0.1-30.0 and Weight% is 0.1-8.0 The manufacturing method of the composite membrane characterized by the above-mentioned. The solvent of claim 1 wherein the solvent of the polyfunctional acid halide solution is a mixture of n-decane, 2,5 dimethylnucleic acid and methylethyl ether, the weight percent of 2,5-dimethylliquid acid is 0.1-30.0 and the weight of ethylmethyl ether A method for producing a polyamide composite separator, characterized in that the% is 0.1 ~ 8.0.