Composite semipermeable membrane and process for producing the same

Abstract

The present invention aims at providing a composite semipermeable membrane in which water permeability and salt-blocking rate cannot deteriorate by long-term storage, and at providing a process for producing the same. The present invention relates to a composite semipermeable membrane having a skin layer formed on the surface of a porous support, the skin layer including a polyamide resin obtained by interfacial polymerization of a polyfunctional amine component and a polyfunctional acid halide component, wherein the porous support contains at least one kind of additives selected from the group consisting of antioxidants, antibacterial agents, antifungal agents, and moisturizers, in an amount of 95% by weight or more with respect to the whole composite semipermeable membrane.

1 . A composite semipermeable membrane having a skin layer formed on the surface of a porous support, the skin layer comprising a polyamide resin obtained by interfacial polymerization of a polyfunctional amine component and a polyfunctional acid halide component, wherein the porous support contains at least one kind of additive selected from the group consisting of an antioxidant, an antibacterial agent, an antifungal agent, and a moisturizer in an amount of 95% by weight or more with respect to the whole composite semipermeable membrane. 
   
   
       2 . The composite semipermeable membrane according to  claim 1 , wherein the composite semipermeable membrane is a dried composite semipermeable membrane. 
   
   
       3 . The composite semipermeable membrane according to  claim 1 , wherein the moisturizer is an organic acid metal salt and/or an inorganic acid metal salt. 
   
   
       4 . The composite semipermeable membrane according to  claim 3 , wherein the organic acid metal salt is at least one kind of organic acid alkali metal salt selected from the group consisting of an alkali metal acetate, alkali metal lactate, and alkali metal glutamate. 
   
   
       5 . The composite semipermeable membrane according to  claim 3 , wherein the inorganic acid metal salt is at least one kind of inorganic acid alkali metal salt selected from the group consisting of an alkali metal hydrogencarbonate, dialkali metal monohydrogen phosphate, and monoalkali metal dihydrogen phosphate. 
   
   
       6 . A process for producing a composite semipermeable membrane comprising:
 forming a skin layer including a polyamide resin obtained by reaction between a polyfunctional amine component and a polyfunctional acid halide component on the surface of a porous support; and   performing a treatment with additives onto the porous support by contact of an aqueous solution including at least one kind of additives selected from the group consisting of an antioxidant, an antibacterial agent, an antifungal agent, and a moisturizer, to a face without the skin layer of the porous support.   
   
   
       7 . The composite semipermeable membrane according to  claim 2 , wherein the moisturizer is an organic acid metal salt and/or an inorganic acid metal salt. 
   
   
       8 . The composite semipermeable membrane according to  claim 7 , wherein the organic acid metal salt is at least one kind of organic acid alkali metal salt selected from the group consisting of an alkali metal acetate, alkali metal lactate, and alkali metal glutamate. 
   
   
       9 . The composite semipermeable membrane according to  claim 7 , wherein the inorganic acid metal salt is at least one kind of inorganic acid alkali metal salt selected from the group consisting of an alkali metal hydrogencarbonate, dialkali metal monohydrogen phosphate, and monoalkali metal dihydrogen phosphate. 
   
   
       10 . The composite semipermeable membrane according to  claim 1 , wherein the porous support contains an antioxidant selected from the group consisting of sodium sulfite, sodium hyposulfite, sodium bisulfite, potassium sulfite, potassium hydrogen hyposulfite, sulfur dioxide, isopropyl citrate, ascorbic acid, alkyl ascorbate, and sodium ascorbate. 
   
   
       11 . The composite semipermeable membrane according to  claim 1 , wherein the porous support contains an antibacterial agent selected from the group consisting of a silver based compound, a copper based compound, a photocatalytic compound, a chitosan, and a catechin. 
   
   
       12 . The composite semipermeable membrane according to  claim 1 , wherein the content of the additive(s) in the porous support is 1 mg/m 2  to 100 g/m 2 . 
   
   
       13 . The process of  claim 6 , further comprising drying the treated composite semipermeable membrane. 
   
   
       14 . The process of  claim 6 , wherein concentration of the additives in the aqueous solution is 100 ppm to 30% by weight.