Degussa Aktiengesellschaft

Cerdec Aktiengesellschaft Keramische Farben

Bernd Dorbath

Norbert Giesecke

Klaus-Dieter Fritsche

Kai Dorer

Werner Voelker

Karl A Starz

Wilan Jerke

Wolfgang Zilske

Rainer Schlodder

Franz Simon

Kerstin Ruhnau

Werner Huth

Prior art production of purple pigments based on colloidal gold on stovable/sinterable/fireable support material involves the reduction of a gold compound in the presence of a chemical reducing agent. Purple pigments may be produced more simply according to the invention by intimately mixing and/or grinding the support material and the gold compound in dry form or by bringing an aqueous solution or suspension of a gold compound and a support material into contact and then thermally treating the mixture at a temperature above the decomposition temperature of the gold compound and below the sintering temperature of the support material, wherein the gold compound is converted into colloidal gold.

Process for the production of purple pigments

Purple colors based on colloidal gold on stovable substrates and the use thereof for the production of purple decoration on glass, ceramics and porcelain are known. The production of such purple colors is elaborate. Agents according to the invention should be viewed as pigment precursors, wherein the pigment is formed during firing of the decoration. The agents contain a gold compound, with the exception of gold oxide, which may be decomposed to colloidal gold on firing of the decoration and a finely divided glass flux in a weight ratio of gold to glass flux of between 1:10 and 1:2,000. Preferred agents contain HAuCl.sub.4, Au.sub.2 S.sub.3, AuCN or KAu(CN).sub.2 as the gold compound and a lead-free glass frit as the glass flux. The agents may be obtained by grinding the glass flux with a gold compound. Purple decoration is obtained by applying the agent to the substrate to be decorated and storing at 400.degree. to 1,050.degree. C.

Process and agent for the production of purple decoration

New electromagnetic interference (EMI) shielding pigments based on silver coated carrier pigments are disclosed which have a wider activity spectrum and are more economically available than previously known shielding pigments. The carrier pigments used are platelet shaped, ferro- or ferrimagnetic, Fe-containing, naturally occurring or synthetically produced laminar minerals. The Ag coating amounts to 5 to 25% by weight, based on the carrier pigment. Shielding pigments, which may be prepared by conventional chemical deposition of Ag or by sputtering, may be used for the production of EMI protective coatings and EMI protective films.

EMI shielding pigments, a process for their preparation and their use

Purple pigments based on glass frits having an average particle diameter (D.sub.50 value) of 0.5 to 50 .mu.m, of which the surface has a coating of essentially 0.05 to 5% by weight, based on the pigment, of colloidal gold and, if desired, color-modifying metals from the group consisting of Ag, Cu, Co, Ni, Sn, Ru, Rh, Pd, Os, Ir and Pt in a total quantity below that of the gold. The purple pigments do not require the hitherto necessary calcination step and can be used for pigmenting glazes, enamels, glass colors, decorative colors, plastics, printing inks and lacquers.

Purple pigments, a process for their production and use thereof

Bright, low carat gold-silver-alloy coatings which are ductile and have a thickness up to over 100 .mu.m are obtained from an electrolytic bath containing 0.5 to 25 g/l of gold in the form of alkali gold cyanide, 0.25 to 15 g/l of silver in the form of alkali silver cyanide and 10 to 200 g/l of alkali cyanide as well as 0.001 to 5 g/l of tellurium in the form of a water soluble tellurium compound.

Method and electrolytic bath for the deposition of low carat bright

For the production of low carat rose to gold colored gold alloy coatings there are needed electrolytic baths containing soluble gold cyanide, soluble copper cyanide, potassium carbonate or potassium bicarbonate which produce corrosion resistant coatings of 13-18 carats and no physiologically hazardous cadmium. The baths of the present invention contain, in place of cadmium, 7.5 to 40 grams/liter of zinc as complex zinc cyanide.

Growing community of inventors

Alzenau, Germany

Bernd Dorbath