Dimensionally stable asbestos diaphragms

Claim 1

A method of providing a hydraulically permeable dimensionally stable diaphragm on a foraminous chlor-alkali electrolytic cell cathode, which method comprises: (a) forming a slurry of fibrous asbestos and a particulate thermoplastic fluorine-containing polymer mechanically and chemically resistant to the cell environment by mixing together said asbestos and polymer, said polymer being present in an amount sufficient to prevent substantial swelling of the diaphragm; (b) inserting the cathode to be coated into said slurry and depositing a uniform mixture of asbestos fibers and particulate polymer thereon by means of a vacuum; (c) removing the coated cathode from the slurry and subjecting same to a temperature sufficient to allow the polymer to fuse and flow, without the application of pressure, and cause the polymer to bind adjacent fibers together without forming a continuous polymer coating on the fiber surface; and (d) cooling the diaphragm coated cathode to substantially room temperature whereby there is obtained a diaphragm, dimensionally stable under operating cell conditions, characterized by asbestos fibers bearing a discontinuous fused polymer coating thereon.

Claim 2

A method of providing a hydraulically permeable dimensionally stable diaphragm on a foraminous chlor-alkali electrolytic cell cathode, which method comprises: (a) forming a slurry of fibrous asbestos and a particulate thermoplastic fluorine-containing polymer mechanically and chemically resistant to the cell environment by mixing together said asbestos and polymer, said polymer being present in an amount sufficient to prevent substantial swelling of the diaphragm; (b) inserting the cathode to be coated into said slurry and depositing a uniform mixture of asbestos fibers and particulate polymer thereon by means of a vacuum; (c) removing the coated cathode from the slurry and subjecting same to a temperature sufficient to allow the polymer to fuse and flow, without the application of pressure, and cause the polymer to bind adjacent fibers together without forming a continuous polymer coating on the fiber surface; and (d) cooling the diaphragm coated cathode to substantially room temperature whereby there is obtained a diaphragm, dimensionally stable under operating cell conditions, characterized by asbestos fibers bearing a discontinuous fused polymer coating thereon.

Claim 7

A method of providing a hydraulically permeable dimensionally stable diaphragm on a foraminous chlor-alkali electrolytic cell cathode which method comprises: (a) forming a slurry of fibrous asbestos and a fibrous thermoplastic fluorine-containing polymer mechanically and chemically resistant to the cell environment by mixing together said asbestos and polymer, said polymer being present in an amount sufficient to prevent substantial swelling of the diaphragm; (b) inserting the cathode to be coated into said slurry and depositing a uniform mixture of asbestos and polymer fibers thereon by means of a vacuum; (c) removing the coated cathode from the slurry and subjecting same to a temperature sufficient to allow the polymer to fuse and flow, without the application of pressure, and cause the polymer to bind adjacent fibers together without forming a continuous polymer coating on the asbestos fiber surface; and (d) cooling the diaphragm coated cathode to substantially room temperature whereby there is obtained a diaphragm, dimensionally stable under operating cell conditions, chaaracterized by asbestos fibers bearing a discontinuous polymer coating thereon, said asbestos fibers being bound together by a fused polymer fiber lattice.

Claim 8

A method of providing a hydraulically permeable dimensionally stable diaphragm on a foraminous chlor-alkali electrolytic cell cathode which method comprises: (a) forming a slurry of fibrous asbestos and a fibrous thermoplastic fluorine-containing polymer mechanically and chemically resistant to the cell environment by mixing together said asbestos and polymer, said polymer being present in an amount sufficient to prevent substantial swelling of the diaphragm; (b) inserting the cathode to be coated into said slurry and depositing a uniform mixture of asbestos and polymer fibers thereon by means of a vacuum; (c) removing the coated cathode from the slurry and subjecting same to a temperature sufficient to allow the polymer to fuse and flow, without the application of pressure, and cause the polymer to bind adjacent fibers together without forming a continuous polymer coating on the asbestos fiber surface; and (d) cooling the diaphragm coated cathode to substantially room temperature whereby there is obtained a diaphragm, dimensionally stable under operating cell conditions, chaaracterized by asbestos fibers bearing a discontinuous polymer coating thereon, said asbestos fibers being bound together by a fused polymer fiber lattice.

Claim 12

A method of providing a hydraulically permeable dimensionally stable diaphragm on a foraminous chlor-alkali electrolytic cell cathode which method comprises: (a) forming a slurry of fibrous asbestos and a granular thermoplastic fluorine-containing polymer mechanically and chemically resistant to the cell environment by mixing together said asbestos and polymer, said polymer being present in an amount sufficient to prevent substantial swelling of the diaphragm; (b) inserting the cathode to be coated into said slurry and depositing a uniform mixture of asbestos fibers and polymer granules thereon by means of a vacuum; (c) removing the coated cathode from the slurry and subjecting same to a temperature sufficient to allow the polymer to fuse and flow, without the application of pressure, and cause the polymer to bind adjacent fibers together without forming a continuous polymer coating on the fiber surface; and (d) cooling the diaphragm coated cathode to substantially room temperature whereby there is obtained a diaphragm, dimensionally stable under operating cell conditions, characterized by asbestos fibers bearing a discontinuous polymer coating thereon and fused with polymer at the points of fiber intersection.

Claim 13

A method of providing a hydraulically permeable dimensionally stable diaphragm on a foraminous chlor-alkali electrolytic cell cathode which method comprises: (a) forming a slurry of fibrous asbestos and a granular thermoplastic fluorine-containing polymer mechanically and chemically resistant to the cell environment by mixing together said asbestos and polymer, said polymer being present in an amount sufficient to prevent substantial swelling of the diaphragm; (b) inserting the cathode to be coated into said slurry and depositing a uniform mixture of asbestos fibers and polymer granules thereon by means of a vacuum; (c) removing the coated cathode from the slurry and subjecting same to a temperature sufficient to allow the polymer to fuse and flow, without the application of pressure, and cause the polymer to bind adjacent fibers together without forming a continuous polymer coating on the fiber surface; and (d) cooling the diaphragm coated cathode to substantially room temperature whereby there is obtained a diaphragm, dimensionally stable under operating cell conditions, characterized by asbestos fibers bearing a discontinuous polymer coating thereon and fused with polymer at the points of fiber intersection.