FIELD: electrolytic baths of chlorine-alkali type and preparation of cathode unit. SUBSTANCE: cathode unit of diaphragm electrolyzer has perforated cathode element, fibrous layer basically made of current-conducting fibers applied on it and diaphragm including 3.0-25.0 per cent by weight of polymer fluoride, 20.0-95.0 per cent by weight of mixture of fibers of polytetrafluoroenthylene and mineral fibers, 0-50.0 per cent by weight of gel of oxohydroxide of at least one metal of group IVA, IVB, VB and VIB or from lanthanide and actinide series. Process of preparation of cathode unit includes following operations: precipitation of cathode layer on elementary cathode by way of filtration from aqueous dispersion, removal of aqueous medium, vacuum filtration through obtained cathode layer, removal of liquid medium, sintering of complex and its treatment with aqueous solution of hydroxide of alkaline metal. In this case aqueous solution after second filtration has fibers of polytetrafluoroethylene, mineral fibers and binder based on polymer in the form of particles. EFFECT: improved operational characteristics of diaphragm and increased efficiency of electrolytic baths. 14 cl, 2 tbl
