Unreinforced membrane, electrochemical cell and electrolysis process

In an unreinforced fluorinated cation-exchange polymer membrane which is impermeable to hydraulic flow of liquid, said membrane comprising at least first and second layers of fluorinated polymer whose functional groups are --CFZ--COOM groups or --CFQ--SO.sub.3 M groups, where M is H, Na, K or NH.sub.4, Z is F, CF.sub.3 or CF.sub.2 Cl, and Q is F, Cl, C.sub.1 to C.sub.10 perfluoroalkyl or CF.sub.2 Cl, adjacent said layers being in adherent contact with one another, said first layer being of polymer whose functional groups are --CFZ--COOM groups and said second layer being of polymer whose functional groups are --CFQ--SO.sub.3 M groups, the improvement wherein said membrane has, as the sole support elements, sacrificial elements partially embedded in the outer surface of said second layer such that after removal of said sacrificial elements, there are voids at the outer surface of said second layer characterized by a void content of 20 to 70%, and each said polymer with --CFZ--COOM groups has an equivalent weight of 670 to 1500 and each said polymer with --CFQ--SO.sub.3 M groups has an equivalent weight of 600 to 1500.

In an unreinforced fluorinated polymer membrane which is impermeable to hydraulic flow of liquid, said membrane comprising at least first and second layers of fluorinated polymer whose functional groups are --CFZ--COOR groups or --CFQ--SO.sub.2 X groups, where R is lower alkyl, X is F or Cl, Z is F, CF.sub.3 or CF.sub.2 Cl, and Q is F, Cl, C.sub.1 to C.sub.10 perfluoroalkyl or CF.sub.2 Cl, adjacent said layers being in adherent contact with one another, said first layer being of polymer whose functional groups are --CFZ--COOR groups and said second layer being of polymer whose functional groups are --CFQ--SO.sub.2 X groups, the improvement wherein said membrane has, as the sole support elements, sacrificial elements partially embedded in the outer surface of said second layer such that after removal of said sacrificial elements, there are voids at the outer surface of said second layer charcterized by a void content of 20 to 70%, and each said polymer with --CFZ--COOR groups has an equivalent weight of 670 to 1500 and each said polymer with --CFQ--SO.sub.2 X groups has an equivalent weight of 600 to 1500.

In an unreinforced fluorinated polymer membrane which is an unreinforced film impermeable to hydraulic flow of liquid, said membrane comprising at least first and second layers of fluorinated polymer whose functional groups are --CFZ--COOR groups or --CFQ--SO.sub.2 X groups, where R is lower alkyl, X is F or Cl, and Z is F, CF.sub.3 OR CF.sub.2 Cl, and Q is F, Cl, C.sub.1 to C.sub.10 perfluoroalkyl or CF.sub.2 Cl, adjacent said layers being in adherent contact with one another, said first layer being of polymer whose functional groups are --CFZ--COOR groups and said second layer being of polymer whose functional groups are --CFQ--SO.sub.2 X groups, the improvement wherein said membrane has voids at the outer surface of said second layer characterized by a void content of 20 to 70%, and each said polymer with --CFZ--COOR groups has an equivalent weight of 670 to 1500 and each said polymer with --CFQ--SO.sub.2 X groups has an equivalent weight of 600 to 1500.