Composite hydrophilic membrane and method for manufacture thereof

Claim 1

A composite hydrophilic membrane comprising at least two layers, adhered fast, formed of a very thin semipermeable hydrophilic membrane, the thickness being in the range of 0.05 to 5μ, derived from an ethylenic copolymer or an ethylenic copolymer resin composition and containing at least one hydrophilic group selected from the class consisting of --OH group and --COOR group (wherein, R is hydrogen, a hydrocarbon group of one to five carbon atoms, an alkali metal atom or other ion capable of forming a salt with carboxyl group) and at least 0.2 meq/g of sulfonic group, and a polyethylenic microporous membrane containing a sulfonic group, said composite hydrophilic membrane having the separation factor A/B (A=water and B=ethanol) of above 10 and the permeation rate of water of above 500 g/hr.m 2 .

Claim 15

A method for the manufacture of a composite hydrophilic membrane, which comprises preparing an aqueous dispersion containing an ethylenic copolymer derived from at least two monomers, ethylene and a comonomer of the general formula: ##STR13## wherein, R 1 denotes H or CH 3 and R 2 denotes either OCOR 3 or COOR 4 , provided that R 3 is a hydrocarbon group of one to five carbon atoms and R 4 is H, a hydrocarbon group of one to six carbon atoms, an alkali metal atom, or other ion capable of forming a salt with carboxyl group, applying this aqueous dispersion to a polyethylenic microporous membrane or a polyethylenic resin film, allowing the applied layer of said ethylenic copolymer to adhere fast to said microporous membrane or said resin film to form a composite film, and causing said composite film to be reacted upon by a sulfonating agent; said composite film, prior to sulfonation, may additionally be laminated to any one of, said composite film, itself, said microporous membrane, and said resin film; further, when said resin film is present in the composite, said resin film is converted, at a point after the application of the aqueous dispersion, into a microporous membrane.

Claim 16

A method for the manufacture of a composite hydrophilic membrane, which comprises preparing an aqueous dispersion containing an ethylenic copolymer derived from at least two monomers, ethylene and a comonomer of the general formula: ##STR13## wherein, R 1 denotes H or CH 3 and R 2 denotes either OCOR 3 or COOR 4 , provided that R 3 is a hydrocarbon group of one to five carbon atoms and R 4 is H, a hydrocarbon group of one to six carbon atoms, an alkali metal atom, or other ion capable of forming a salt with carboxyl group, applying this aqueous dispersion to a polyethylenic microporous membrane or a polyethylenic resin film, allowing the applied layer of said ethylenic copolymer to adhere fast to said microporous membrane or said resin film to form a composite film, and causing said composite film to be reacted upon by a sulfonating agent; said composite film, prior to sulfonation, may additionally be laminated to any one of, said composite film, itself, said microporous membrane, and said resin film; further, when said resin film is present in the composite, said resin film is converted, at a point after the application of the aqueous dispersion, into a microporous membrane.

Claim 20

A method for the manufacture of a composite hydrophilic membrane according to any of claims 14-17, wherein the composite hydrophilic membrane has the shape of a hollow fiber.

Claim 21

A method for the manufacture of a composite hydrophilic membrane, which comprises hot laminating and stretching at least one very thin film of either at least one ethylenic copolymer selected from the group consisting of an ethylenic copolymer derived from at least two monomers, ethylene and a comonomer of the general formula: ##STR15## wherein, R 1 denotes H or CH 3 and R 2 denotes either OCOR 3 or COOR 4 , provided that R 3 is a hydrocarbon group of one to five carbon atoms and R 4 is H, a hydrocarbon group of one to six carbon atoms, an alkali metal atom, or other ion capable of forming a salt with carboxyl group, and a saponification derivative of said ethylenic copolymer or a resin composition containing at least 15% by weight of said ethylenic copolymer and at most 85% by weight of another thermoplastic resin and at least one layer of a polyethylenic microporous membrane or a polyethylenic resin film capable of being converted into a polyethylenic microporous membrane, thereby producing a composite film, causing said composite film to react with a sulfonating agent and, when said polyethylenic resin film is present in the composite, said resin film is converted into a polyethylenic microporous membrane at a point after lamination.

Claim 22

A method for the manufacture of a composite hydrophilic membrane, which comprises hot laminating and stretching at least one very thin film of either at least one ethylenic copolymer selected from the group consisting of an ethylenic copolymer derived from at least two monomers, ethylene and a comonomer of the general formula: ##STR15## wherein, R 1 denotes H or CH 3 and R 2 denotes either OCOR 3 or COOR 4 , provided that R 3 is a hydrocarbon group of one to five carbon atoms and R 4 is H, a hydrocarbon group of one to six carbon atoms, an alkali metal atom, or other ion capable of forming a salt with carboxyl group, and a saponification derivative of said ethylenic copolymer or a resin composition containing at least 15% by weight of said ethylenic copolymer and at most 85% by weight of another thermoplastic resin and at least one layer of a polyethylenic microporous membrane or a polyethylenic resin film capable of being converted into a polyethylenic microporous membrane, thereby producing a composite film, causing said composite film to react with a sulfonating agent and, when said polyethylenic resin film is present in the composite, said resin film is converted into a polyethylenic microporous membrane at a point after lamination.

Claim 25

A method for the manufacture of a composite hydrophilic membrane, which comprises joining and molding: (a) a polyethylenic resin composition (I) capable of being converted, on being molded in the shape of a film or a sheet, into a microporous membrane and (b) a resin composition (II) containing either; at least one ethylenic copolymer selected from the group consisting of an ethylenic copolymer derived from at least two monomers, ethylene and a comonomer of the general formula: ##STR17## wherein, R 1 denotes H or CH 3 and R 2 denotes either OCOR 3 or COOR 4 , provided that R 3 is a hydrocarbon group of one to five carbon atoms and R 4 is H, a hydrocarbon group of one to six carbon atoms, an alkali metal atom, or other ion capable of forming a salt with a carboxyl group; and a saponification derivative of said ethylenic copolymer or a resin composition containing at least 15% by weight of said ethylenic copolymer and at most 85% by weight of another thermoplastic resin and at least one layer of a polyethylenic microporous membrane or a polyethylenic resin film capable of being converted into a polyethylenic microporous membrane, thereby producing a composite film having a layer combination of (I)/(II) or (I)/(II)/(I), sulfonating said composite film and converting said layer of resin composition (I), at a point after molding into a microporous membrane.

Claim 26

A method for the manufacture of a composite hydrophilic membrane, which comprises joining and molding: (a) a polyethylenic resin composition (I) capable of being converted, on being molded in the shape of a film or a sheet, into a microporous membrane and (b) a resin composition (II) containing either; at least one ethylenic copolymer selected from the group consisting of an ethylenic copolymer derived from at least two monomers, ethylene and a comonomer of the general formula: ##STR17## wherein, R 1 denotes H or CH 3 and R 2 denotes either OCOR 3 or COOR 4 , provided that R 3 is a hydrocarbon group of one to five carbon atoms and R 4 is H, a hydrocarbon group of one to six carbon atoms, an alkali metal atom, or other ion capable of forming a salt with a carboxyl group; and a saponification derivative of said ethylenic copolymer or a resin composition containing at least 15% by weight of said ethylenic copolymer and at most 85% by weight of another thermoplastic resin and at least one layer of a polyethylenic microporous membrane or a polyethylenic resin film capable of being converted into a polyethylenic microporous membrane, thereby producing a composite film having a layer combination of (I)/(II) or (I)/(II)/(I), sulfonating said composite film and converting said layer of resin composition (I), at a point after molding into a microporous membrane.

Claim 29

A method for the manufacture of a composite hydrophilic membrane according to any one of claims 22-24, wherein the stretching is made at an area stretching ratio of at least 2.