Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
136 words
A diaphragm for use in a chlor-alkali electrolysis cell, said diaphragm consisting essentially of fibers having a cross-sectional dimension of 0.3 to 5 microns, said fibers being composed of a fluorine-containing addition polymer selected from the group consisting of the homopolymers of chlorotrifluoroethylene and copolymers of chlorotrifluoroethylene with at least one compatible unsaturated C 2 to C 4 monomer, units of chlorotrifluoroethylene accounting for at least 80 percent of the monomeric units of said copolymer which exhibits the property of developing, while in service in the hostile environment of a chlor-alkali cell, a surface portion of composition different from that of the bulk of said fiber and effective after a period of use of approximately 2 weeks to increase substantially the burst strength and to prolong substantially the service life of said diaphragm in said cell.
Claim 2
Dependent Claim
136 words
A diaphragm for use in a chlor-alkali electrolysis cell, said diaphragm consisting essentially of fibers having a cross-sectional dimension of 0.3 to 5 microns, said fibers being composed of a fluorine-containing addition polymer selected from the group consisting of the homopolymers of chlorotrifluoroethylene and copolymers of chlorotrifluoroethylene with at least one compatible unsaturated C 2 to C 4 monomer, units of chlorotrifluoroethylene accounting for at least 80 percent of the monomeric units of said copolymer which exhibits the property of developing, while in service in the hostile environment of a chlor-alkali cell, a surface portion of composition different from that of the bulk of said fiber and effective after a period of use of approximately 2 weeks to increase substantially the burst strength and to prolong substantially the service life of said diaphragm in said cell.
Claim 3
Dependent Claim
16 words
A diaphragm as defined in claim 1, wherein said addition polymer is a homopolymer of chlorotrifluoroethylene.
Claim 4
Dependent Claim
19 words
A diaphragm as defined in claim 1, wherein said addition polymer is a copolymer containing chlorotrifluoroethylene and vinylidene fluoride.
Claim 5
Dependent Claim
26 words
A diaphragm as defined in claim 3, wherein said addition polymer is one containing about 1 monomer unit of vinylidene fluoride per 24 units of chlorotrifluoroethylene.
Claim 6
Dependent Claim
49 words
A diaphragm as defined in claim 1, said diaphragm having been produced by a method involving the deposition of first and second layers, whereby the deposition of the second layer acts to correct flaws or defects in the first layer and produce a more nearly uniform and homogeneous structure.
Claim 7
Dependent Claim
57 words
A polychlorotrifluoroethylene diaphragm made of fibers about micron-sized in cross-section and having exterior plies lower in molecular weight than the bulk of said diaphragm but substantially increased burst strength and service life, said diaphragm being produced by exposure of said diaphragm to hot caustic solution for a time and at a temperature sufficient to produce said layers.
Claim 8
Dependent Claim
57 words
A polychlorotrifluoroethylene diaphragm made of fibers about micron-sized in cross-section and having exterior plies lower in molecular weight than the bulk of said diaphragm but substantially increased burst strength and service life, said diaphragm being produced by exposure of said diaphragm to hot caustic solution for a time and at a temperature sufficient to produce said layers.
Claim 9
Dependent Claim
30 words
The method of making a diaphragm according to claim 6, wherein said exposure is done by subjecting the diaphragm to cell operating conditions for a period of about 2 weeks.
Claim 10
Dependent Claim
31 words
The method of making a diaphragm according to claim 6, wherein said exposure is done by subjecting the diaphragm to hot caustic under superatmospheric conditions outside the cell before inserting it.
Claim 11
Dependent Claim
43 words
The method of making a diaphragm according to claim 6, wherein said exposure is done by subjecting the diaphragm to cell operating conditions which are superatmospheric in pressure at correspondingly higher temperature to shorten the period of "in situ" formation of the plies.