Additive for chromium electrolytes

Abstract

The fluorine surfactant-free, long-term-stable and biodegradable additive for chromium electrolytes lowers the surface tension and hence improves the chromium deposition process, especially in the application for the electrolytical chromium-plating. Preferred additives are CH 3 (CH 2 ) n SO 3 H and the salts thereof with n from 10 to 18. These additives are also useful as component in polymer mordants as pretreatments for polymer metallizations.

1 - 9 . (canceled) 
     
     
         10 . Additive for chromic acid solutions, being free of fluorine surfactants and biodegradable and having in a chromic acid solution which contains the said additive a surface tension of ≦30 mN/m, and having in the application in the electrolytical chromium-plating, determined at 45° C. and 6000 Ah of charge passage, in the chromic acid solution which contains the said additive a stability of ≦4 h. 
     
     
         11 . Additive according to claim  1 , comprised in a chromic acid solution and used in the electrolytical chromium-plating, this chromic acid solution has a current density of 35 A/dm 2  to 60 A/dm 2 . 
     
     
         12 . Additive according to claim  1 , comprising at least one surfactant from the group consisting of long-chain alkylmonosulphonic acids, long-chain alkyldisulphonic acids, long-chain alkylpolysulphonic acids, salts of the long-chain alkylmonosulphonic acids, salts of the long-chain alkyldisulphonic acids and salts of the long-chain alkylpolysulphonic acids. 
     
     
         13 . Additive according to claim  1 , comprising at least one surfactant being CH 3 (CH 2 )nSO 3 H or salts thereof, where n is 10 to 18. 
     
     
         14 . Method of use of an additive according to claim  1  as a smoothing agent in chromium electrolytes. 
     
     
         15 . Method of use according to claim  5 , wherein the concentration of the additive is between 0.05 g/l and 20 g/l. 
     
     
         16 . Method of use of an additive according to claim  1  as an additive in polymer mordants as pretreatments for polymer metallizations. 
     
     
         17 . Method of use of an additive according to claim  3  as a smoothing agent in chromium electrolytes.