Electrolytic cell membrane and method of preparation by plasma polymerization of polyamide or polytetrafluoroethylene thin films onto polymeric substrates
First Claim
1. An improved hydraulically impermeable cation exchange membrane consisting essentially of:
- a substrate selected from the group of a film of copolymer having the repeating structural units of the formula ##STR4## in which R'"'"' is fluorine, or perfluoroalkyl of 1 to 10 carbon atoms;
Y is fluorine or trifluoromethyl;
m is 1, 2 or 3;
n is 0 or 1;
x is fluorine, chlorine or trifluoromethyl; and
x'"'"' is x or CF3 --CF2 --a O--;
wherein a is 0 or an integer from 1 to 5;
the units of formula (I) being present in an amount to provide a copolymer having an --SO3 H equivalent weight of about 1000 to 1400;
copolymers of tetrafluoroethylene and hexafluoropropylene having grafted thereon a 50-50 mixture of styrene and alpha methylstyrene which has been sulfonated;
oran insoluble, infusible copolymeric matrix formed from at least 20 percent by weight of a polyvinyl aromatic compound and not more than 80 percent of a monovinyl aromatic compound with a reinforcing material therein and no more than 70 percent by weight of a monovinyl aromatic compound without a reinforcing material therein, sulfonate groups chemically bonded to the aromatic nuclei of the matrix and a solvating liquid in gel relationship with the matrix, the sulfonate groups being present in an amount no more than four equivalents or sulfonate groups for each mole of polyvinyl aromatic compound and not less than one equivalent of sulfonate groups for each 10 moles of poly- and monovinyl aromatic compound the solvating liquid being at least 25 percent by volume of the resin; and
a top coating deposited upon the surface of at least one side of said substrate by plasma polymerization to produce a thin pinhole free coating in the range of 50 to 2000 Angstroms having a chemical makeup selected from the group of polyamide or polytetrafluoroethylene.
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Accused Products
Abstract
Disclosed is an improved hydraulically impermeable cation exchange membrane for an electrolytic cell and a method for the preparation of such a membrane using a copolymeric substrate and applying to the surface thereof by means of plasma polymerization, a very thin top coating of a second polymeric material to drastically reduce the permeability of the substrate material with a minimal effect upon the bulk properties of the resultant membrane. Such top coatings may be applied over the basic substrate or over surface treated substrates to enhance the chemical resistivity of the membrane to chemical breakdown occasioned by the electrolyte within the electrolytic cell.
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Citations
5 Claims
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1. An improved hydraulically impermeable cation exchange membrane consisting essentially of:
- a substrate selected from the group of a film of copolymer having the repeating structural units of the formula ##STR4## in which R'"'"' is fluorine, or perfluoroalkyl of 1 to 10 carbon atoms;
Y is fluorine or trifluoromethyl;
m is 1, 2 or 3;
n is 0 or 1;
x is fluorine, chlorine or trifluoromethyl; and
x'"'"' is x or CF3 --CF2 --a O--;
wherein a is 0 or an integer from 1 to 5;
the units of formula (I) being present in an amount to provide a copolymer having an --SO3 H equivalent weight of about 1000 to 1400;copolymers of tetrafluoroethylene and hexafluoropropylene having grafted thereon a 50-50 mixture of styrene and alpha methylstyrene which has been sulfonated;
oran insoluble, infusible copolymeric matrix formed from at least 20 percent by weight of a polyvinyl aromatic compound and not more than 80 percent of a monovinyl aromatic compound with a reinforcing material therein and no more than 70 percent by weight of a monovinyl aromatic compound without a reinforcing material therein, sulfonate groups chemically bonded to the aromatic nuclei of the matrix and a solvating liquid in gel relationship with the matrix, the sulfonate groups being present in an amount no more than four equivalents or sulfonate groups for each mole of polyvinyl aromatic compound and not less than one equivalent of sulfonate groups for each 10 moles of poly- and monovinyl aromatic compound the solvating liquid being at least 25 percent by volume of the resin; and a top coating deposited upon the surface of at least one side of said substrate by plasma polymerization to produce a thin pinhole free coating in the range of 50 to 2000 Angstroms having a chemical makeup selected from the group of polyamide or polytetrafluoroethylene. - View Dependent Claims (2, 4)
- a substrate selected from the group of a film of copolymer having the repeating structural units of the formula ##STR4## in which R'"'"' is fluorine, or perfluoroalkyl of 1 to 10 carbon atoms;
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3. A method for the preparation of an improved hydraulically impermeable cation exchange membrane comprising the steps of:
- selecting a substrate material from a group of
copolymers having the repeating structural units of the formula ##STR5## in which R1 is fluorine, or perfluoroalkyl of 1 to 10 carbon atoms;
Y is fluorine or trifluoromethyl;
m is 1, 2 or 3;
n is 0 or 1;
x is fluorine, chlorine or trifluoromethyl; and
x1 is x or CF3 --CF2 --a O--, wherein a is 0 or an integer from 1 to 5;
the units of formula (I) being present in an amount to provide a copolymer having an --SO3 H equivalent weight of about 1000 to 1400;copolymers of tetrafluoroethylene and hexafluoropropylene having grafted thereon a 50-50 mixture of styrene and alpha methylsytrene which has been sulfonated;
oran insoluble, infusible copolymeric matrix formed from at least 20 percent by weight of a polyvinyl aromatic compound and not more than 80 percent of a monovinyl aromatic compound with a reinforcing material therein and no more than 70 weight percent by weight of a monovinyl aromatic compound without a reinforcing material therein, sulfonate groups chemically bonded to the aromatic nuclei of the matrix and a solvating liquid in gel relationship with the matrix, the sulfonate groups being present in an amount no more than four equivalents or sulfonate groups for each mole of polyvinyl aromatic compound and not less than one equivalent of sulfonate groups for each 10 moles of poly- and monovinyl aromatic compound the solvating liquid being at least 25 percent by volume of the resin; and applying a top coating selected from the group of polyamide or polytetrafluoroethylene to the surface of at least one side of said substrate by means of plasma polymerization to produce a thin pinhole free coating in the range of 100 to 2000 Angstroms. - View Dependent Claims (5)
- selecting a substrate material from a group of
Specification