Electrostatically applicable coating powder and processes therefor

Abstract

Hitherto, glazing defects have arisen during glazing of ceramic substrates with an electrostatically applicable coating powder. This problem is solved by the coating powder CPAB and the coating method. The electrostatically applicable coating powder CPAB contains 1 to 50 wt. % of a glass-forming composition A which begins softening at 400 to 750° C. and 99 to 50 wt. % of a glass-forming composition B which begins to soften above 750-1,100° C. Preferably, the coating powder consists of 2.5 to 25 wt. % A, 75 to 97.5 wt. % B and 0 to 20 wt. %, specially 2 to 10 wt. % of thermally or chemically activatable adhesive agents. The coating powder CPAB is electrostatically applied as a single powder. Alternately, coating can be applied in two layers, wherein the CPU powder contains at least 5 wt. % of glass-forming composition A as a lower layer and the powder CPO contains at least 50 wt. % of glass-forming composition B as an upper layer.

Dependencies are inferred from the claim text.