Compositions: coating or plastic – Coating or plastic compositions – Heavy metal compound containing
Reexamination Certificate
2002-05-08
2004-08-10
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Heavy metal compound containing
C106S286200, C106S286300
Reexamination Certificate
active
06773498
ABSTRACT:
DESCRIPTION
This invention relates to a bright noble metal preparation, in particular a bright gold preparation, for high temperature firing, wherein the preparation applied onto a siliceous article is stoved at 1050 to 1300 ° C., i.e. above the melting point of gold. The resultant decoration is a bright noble metal film. The invention also provides a process for the production of a bright noble metal decoration, in particular a bright gold decoration, on a siliceous support.
Bright noble metal preparations substantially consist of one or more noble metal compound and flux compounds soluble in a liquid carrier medium. The most important noble metal compounds are those of gold, for which reason such preparations are also frequently known as bright gold preparations. The noble metal compounds are conventionally present in the form of organic compounds, in which the noble metal is attached to an organic skeleton via a sulfur or oxygen bridge. Since these materials frequently comprise mixtures of substances, they are known as noble metal resinates and noble metal sulforesinates. The flux compounds comprise in particular resinates and sulforesinates of elements of main groups three to five and of subgroups three to eight of the periodic system. The carrier media usually comprise a combination of at least one solvent and a binder. The liquid carrier medium may be purely organic, organic/aqueous or substantially purely aqueous. The organic media often comprise those based on hydrocarbons, alcohols and sulfur-containing compounds, such as sulfurised terpene hydrocarbons and terpene alcohols as well as sulfurised natural resins. The composition of bright noble metal preparations and the use thereof for the production of bright to matt films containing noble metals on a siliceous substrate, wherein production of the decoration includes firing at a temperature in the range from approx. 500 to 1400° C., are known from numerous documents.
DE-PS 24 35 859 discloses a coating composition containing gold for stoving on ceramic articles at temperatures of 1100 to 1400° C., which composition contains, apart from a gold preparation, 3 to 40 wt. % of one or more non-noble metals and/or one or more additional noble metals having a melting point of above 1400° C. in powder form and up to 10 wt. % of an coupling oxide or glass flux. The coating composition, which is better described as a burnished gold preparation, may additionally contain organic and/or inorganic gold compounds in addition to metallic gold. The substantial constituents of the preparation, namely elemental gold, the non-noble metals and the coupling oxides or glass fluxes, are insoluble in the organic carrier medium. The gold content of such coating compositions is distinctly above that which is conventional for bright gold preparations and decoration of elevated brightness is not obtained. The non-noble metal component comprises Mg, Si, Ti, Mn, Fe, Ni, Zn, Zr and/or Sb. The coupling oxides comprise compounds of B, Al, V, Cr, Sn, Bi and Ce. Cobalt or cobalt compounds are not mentioned as a constituent of the non-noble metal components and coupling oxides.
DE-PS 22 08 915 discloses a burnished and powdered gold preparation which contains a stabilising addition from the group Cassius gold purple, tin oxide, iron oxide and aluminium in order to increase stoving resistance and bismuth borate as flux. The preparation, with which only matt decoration is obtained, contains no compounds of chromium and/or cobalt.
DE-PS 14 21 865 discloses a process for the production of a vitreous ceramic article coated with a noble metal film, wherein the bright noble metal preparation to be used contains a soluble organic noble metal compound and 0.25 to 10 mol per mol of noble metal of a soluble flux and an organic carrier for the noble metal compound and the flux. Stoving is performed at at least 900° C. This document mentions numerous flux-producing non-noble metals, including aluminium, boron, bismuth, chromium, cobalt, indium, silicon, tantalum, titanium and zirconium. The preparation of Example 7, which contains a gold mercaptide and a titanate does not give rise to a gold coloured film of elevated brightness, but instead to a dark grey film. The preparations which contain a gold mercaptide, rhodium resinate, bismuth resinate and chromium resinate optionally together with a tantalum alkoxide (c.f. columns 9 and 10 of DE-AS 14 21 865) also generally give rise to matt films and only in one case (composition d) was a bright, but dark coloured film obtained.
The preparation of Example 1 of DE-AS 14 21 865 based on a gold mercaptide, niobium alcohol and cobalt resinate comprises a typical burnished gold preparation which yields a silk matt, but not bright gold film only after polishing with a glass fibre brush. While the document does indeed teach that the flux-producing element or elements must be present in a certain quantity relative to the noble metal, there is no indication that a combination of cobalt and chromium as the flux-producing elements gives rise to unusual effects.
It is known from DE-PS 38 09 541 that bright noble metal preparations consisting of at least one organo-noble metal compound, an organic carrier and a flux of organic metal compounds may be stoved at 1250° C. and be used for the production of dishwasher-resistant bright noble metal decoration on crockery of siliceous materials, if the flux contains organic silicon compounds having 3 and/or 4 hydrolysable groups on the silicon atom in a quantity of 0.1 to 4 mol of Si per mol of noble metal. The presence of a high concentration of an organosilicon noble metal compound results during firing in the formation of a transparent vitreous layer on the noble metal film, which layer is responsible for the elevated mechanical strength of the decoration, but the decoration itself is very dark and frequently has a reddish or greenish discolouration and thus has only limited applications. The document gives no indication of additionally using a cobalt compound as a flux constituent. While bright decorative layers are indeed still obtained if the content of organosilicon compounds in the flux is reduced below the value according to the claims, these decorative layers adhere poorly to the ceramic substrate.
According to DE-PS 40 03 796, microwave-resistant noble metal decoration, in particular bright gold decoration, stovable at 1180 to 1230° C. is obtained if a bright gold preparation is used, the flux of which contains an organic nickel compound. The flux preferably additionally contains a soluble organic compound of silicon, aluminium, chromium and bismuth. Such preparations do not, however, meet the quality requirements for bright gold decoration.
DE-PS 37 21 000 also discloses a noble metal preparation for the production of microwave-resistant decoration, which preparation has a noble metal content of 60 to 90 wt. % and a non-noble metal content of 10 to 40 wt. %, in each case relative to the total metal content of the preparation. Non-noble metals, used in the form of a resinate and/or sulforesinate, which are mentioned include: Al, Sb, Ba, Bi, B, Ca, Ce, Cr, Co, Si, Ge, Ta, Sn, Ti, Zn and Zr. The gold preparation according to the Examples of this document is stoved at 800° C., the burnished gold preparation at 1250° C. There is no indication that the bright gold preparation may be stoved at a temperature above the melting point of gold. The document also provides no indication that it is convenient to use cobalt and chromium together in a certain quantity as flux in order to obtain a bright noble metal preparation for high temperature firing.
Noble metal preparations according to U.S. Pat. No. 4,418,099 which contain organometallic compounds of elements of groups 4a and b, 5a and b and 6b of the periodic system as flux component and additionally contain a non-metallic lustre pigment, such as mica, give rise under conventional firing conditions (450 to 900° C.) to silk matt noble metal decoration of the burnished gold type. This document gives no indication of how the preparation could b
Groh Hans
Lang Peter
Poth Lutz
Ferro GmbH
Klemanski Helene
Rankin, Hill Porter & Clark LLP
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