Method of producing cation-exchange membrane having roughed surface

A method of producing a cation-exchange membrane having a roughed surface and high strength said membrane being capable of reducing electrolysis voltage and maintaining current efficiency when used as a membrane in an electrolysis cell, said method comprising mixing silica powder having an average particle diameter of 0.01-20.mu., with water to give a suspended or pasty mixture, supporting the resultant mixture on art paper or filter paper, drying the mixture to form silica powder, adhering the silica powder with heating and pressing on surface of a cation-exchange membrane having cation-exchange group and/or group convertible into the cation-exchange group, thereafter dissolving out thus silica powder formed on the surface of membrane with caustic alkali aqueous solution and treating the obtained roughed surface of the cation-exchange membrane with boiling aqueous solution of 1-10 weight% caustic soda.

A method of producing a cation-exchange membrane having a roughed surface and high strength said membrane being capable of reducing electrolysis voltage and maintaining current efficiency when used as a membrane in an electrolysis cell, said method comprising mixing silica powder having an average particle diameter of 0.01-20.mu., with water to give a suspended or pasty mixture, supporting the resultant mixture on art paper or filter paper, drying the mixture to form silica powder, adhering the silica powder layer with heating and pressing on surface of membrane composed of perfluorocarbon polymer having cation-exchange group and/or group convertible into the cation-exchange group, removing with dissolving the silica powder layer formed on the surface of said membrane with caustic alkali aqueous solution, and heating the cation-exchange membrane having thus obtained roughed surface in a mixed solution of caustic alkali aqueous solution and lower alcohole of C.sub.1 -C.sub.3 at a temperature from 40.degree. C. to the boiling point of the lower alcohol of C.sub.1 -C.sub.3.

A cation-exchange membrane having a roughed surface and high strength said membrane being capable of reducing electrolysis voltage and maintaining current efficiency when used as a membrane in an electrolysis cell, which is obtainable by a process comprising the step of mixing silica powder having an average particle diameter of 0.01-20.mu., with water to give a suspended or pasty mixture, step of supporting the resultant mixture on art paper or filter paper, step of drying the mixture to form silica powder layer, step of adhering with heating and pressing said silca powder layer on surface of membrane composed of perfluorocarbon polymer having cation-exchange group and/or group convertible into the cation-exchange group, and step of removing the silica powder layer formed on the surface of said membrane with caustic alkali aqueous solution.

A cation-exchange membrane having a roughed surface and high strength said membrane being capable of reducing electrolysis voltage and maintaining current efficiency when used as a membrane in an electrolysis cell, which is obtainable by a process comprising the step of mixing silica powder having an average particle diameter of 0.01-20.mu., with water to give a suspended or pasty mixture, step of supporting the resultant mixture on art paper or filter paper, step of drying the mixture to form silica powder, step of adhering the silica powder with heating and pressing on surface of a cation-exchange membrane having cation-exchange group and/or group convertible into the cation-exchange group, step of thereafter dissolving out thus silica powder formed on the surface of membrane with caustic alkali aqueous solution and step of treating the obtained roughed surface of the cation-exchange membrane with boiling aqueous solution of 1-10 weight% caustic soda.

A cation-exchange membrane having a roughed surface and high strength said membrane being capable of reducing electrolysis voltage and maintaining current efficiency when used as a membrane in an electrolysis cell, which is obtainable by a process comprising the step of mixing silica powder having an average particle diameter of 0.01-20.mu., with water to give a suspended or pasty mixture, step of supporting the resultant mixture on art paper or filter paper, step of drying the mixture to form silica powder layer, step of adhering with heating and pressing on surface of membrane composed of perfluorocarbon polymer having cation-exchange group and/or group convertible into the cation-exchange group, step of removing with dissolving the silica powder layer formed on the surface of said membrane with caustic alkali aqueous solution, and step of heating the cation-exchange membrane having thus obtained roughed surface in a mixed solution of caustic alkali aqueous solution and lower alcohol of C.sub.1 -C.sub.3 at a temperature from 40.degree. C. to the boiling point of the lower alcohol of C.sub.1 -C.sub.3.