DD269525A3 - METHOD FOR PRODUCING A SILVER COMPOUND FOR USE IN PRECIOUS METAL PROSPARTS FOR DECORATION PURPOSES - Google Patents

Abstract

The process described for the preparation of a silver compound for use in precious metal preparations for decorative purposes of various products of the ceramic and glass industry allows valuable color effects with relatively low silver use. Another advantage over known production methods of noble metal sulforesinates is the high silver yield in the final product, so that the material and cost for Silberrueckgewinnungsprozesse significantly reduced. The object is achieved according to the invention by the preparation of a special sulfur balm and its reaction with pretreated silver carbonate under defined conditions to the desired silver compound. The invention is applicable to all operations of the ceramic and glass industry for the production of precious metal decorations.

Description

Field of application of the invention

The invention relates to a method for producing an organic silver compound, the use of which in precious metal preparations for the decoration of various products of the ceramic and glass industry valuable color effects are achieved.

Characteristic of the known technical solutions

Ceramic precious metal preparations are complicated, coordinated systems of precious metal, solvent, paint and adhesive components.

The precious metal components cause the desired metallic effect after the decorative firing on the decorated surface and consist of dissolved or suspended precious metal compounds, Edelmetallegi6rungon or mixtures thereof. The solvent and paint components s'jspendiert or dissolved all other components of the preparation and the preparation necessary for the intended decoration type properties, such as viscosity and drying behavior, given.

These components volatilize during drying or burn at temperatures up to 450 ° C during the decorative firing without residues.

The adhesives are either finely suspended silicate fluxes, as used in ceramic paints, or liquid or dissolved organic bismuth, vanadium, chromium, silicon and rhodium compounds. These components form during the decorative firing with volatilization of the organic constituent a layer between the decorated surface and the noble metal layer in the form of the mixtures of the respective metal oxides and bring about the necessary mechanical stability of the decoration.

In polishing precious metal preparations, the use of noble metal compounds soluble in the respective solvents and of finely divided suspensions of solid noble metal carriers or the combination of both. Variants usual.

In bright noble metal preparations, the respective noble metals and all other components are used only and exclusively in liquid form or in the form of compounds soluble in the solvents customary for these preparations. In such preparations, only specially prepared for such purposes precious metal compounds are suitable for this use tuned properties. The respective noble metal compounds must be soluble in the required amount, stable in the dissolved state and compatible with the other components used in the preparation.

It is known that in addition to gold, platinum, palladium and other precious metal compounds silver compounds are used for the preparation of precious metal preparations for decorative purposes.

As noble metal compounds which are used in dissolved form, Sulfuresinate and mercaptides are preferably used.

To shade shades, z. B. in gold preparations, from reddish yellow to golden yellow to achieve the yellowish yellow, the preparations silver compounds are added in quantities that the silver content (based on the gold content in the preparation) is up to 50%.

One consequence of this high proportion of silver is the tendency of the precious metal decoration to become as familiar as silver objects due to the Bi ¹ Jung of silver sulfide.

Object of the invention

The aim of the invention is the preparation of a silver compound with Sulforesinatcharakter, in their use in ceramic precious metal preparations over previously known soluble silver compounds in such preparations, the following advantages are expected:

- Less silver use to z. For example, in the case of bright gold preparations after the décor firing, shades of reddish yellow to golden yellow to greenish yellow can be achieved.

- Eliminating in silver objects as well as in relatively strong silver-containing precious metal preparations on ceramic documents known tarnishing phenomena by the formation of silver sulfide. Hue and shine are preserved.

High yield of the silver compound preparation process of about 97% of the silver used compared to other production values of i ^; ulforesinates such as gold and platinum, which are at 80%. This results in savings in expenses for recovery and new hiring processes.

- Improvements in the material economy by the silver compared to silver-free preparations increased opacity of precious metal decoration, which should be reduced by targeted operation, the consumption of expensive precious metals.

Improvement of the mechanical stability or increase of abrasion resistance compared to silver-free decorations, since silver is itself an adhesive component.

Essence of the invention In bright precious metal preparations, in addition to solvents and lacquer components, only liquid ones can be dissolved Precious metal and adhesive components are used. Very finely divided solids, even in the smallest amounts would

after the firing process on the wafer-thin (about 0.1 to 0.2 μιη layer thickness) and high-gloss noble metal films

Cause filming phenomena, so that the decoration would not meet the demands made of them. at Polished precious metal preparations is the use of precious metal, adhesive and additional components in both liquid and dissolved

as well as in finely divided suspended solid form possible. In practice, very often combinations of both variants

applied.

For the production of silver-containing bright precious metal preparations was the unavoidable task, a liquid or in the

produce soluble silver compound for these preparations typical solvents.

With a silver addition to Polieredelmetallpräparaten in liquid or dissolved form are advantages in the To achieve processing properties. Compared to known gold preparations, which silver compounds in dissolved form to obtain hue nuances of

reddish yellow or golden yellow to pale yellowish, is required for the use of the silver compound according to the invention less silver. Higher combustion or liquefaction temperatures of the organic constituents of the

related silver compound are the cause of this effect. It diffuses less silver into the ceramic or glassy one

Surface and is thus lost to a lesser extent the metallic opacity of the precious metal decoration. According to the invention the task of ationszwecke in noble metal preparations for decorative ^r-soluble silver compound is

produced by the following essential solution:

- As the organic starting component, a sulfur balm is prepared, in a defined composition and according to a synthesis path according to the invention.

- This sulfur balm is reacted with specially processed silver carbonate and thereby obtained the organic silver compound.

To obtain a reaction with silver carbonate, it is necessary to prepare a special sulfur balm. On the basis of hitherto known sulfur balsam compositions, as used for the synthesis of gold, platinum and rhodium, it is not possible to make the silver sales economically and the properties of the silver compound the requirements for use in precious metal preparations for decoration purposes.

The pretreatment of the silver carbonate according to the invention is necessary in order for the reaction with the sulfur balm to be alkali-free, finely divided powder without agglomerates which has the purity and surface area necessary for the reaction with sulfur balm.

Ausführun ^ sbelsplel

The first step in the introduction of the desired silver compound is the preparation of the organic starting component, the sulfur balm, having the following composition:

Designation of the component proportion (% by mass)

Venetian larch turpentine 44

Sulfur powder 11

Portuguese turpentine oil 45

These starting components are concentrated in 2.5-3 hours at temperatures up to 19O ⁰ C to 68-72% of the initial amount. During the reaction, the temperature and the evaporation loss should be checked regularly, the reaction sequence should be monitored, if necessary influenced, and the time of the reaction termination be determined.

The following table shows the temperature curve and the loss of steam as a function of the reaction time on a sulfur balm for the reaction with silver carbonate:

Time temperature evaporation loss (Minutes) ( ⁰ C) (Wt .-%) 0 20 0 30 140 0 60 165 9.5 90 164 10.6 120 168 17.2 135 172 26.9 150 176 30.0 160 183 31.9

The resulting sulfur balm is viscous and must be diluted with Portuguese turpentine oil. There is a Addition of 70% of the mass of the sulfur balm, which is thus available for reaction with silver carbonate available. Before the reaction with sulfur balm to the desired silver compound, the silver carbonate is threefold Slurry and decant washed in distilled water, rinsed with alcohol and dried so that it as

homogeneous and loose powder is present.

This pretreatment is necessary to have a silver carbonate that is free of alkali ion. In addition, by the Flushing with alcohol in the subsequent drying prevents the formation of agglomerates and for the Implementation with sulfur balm necessary surface size achieved. The reaction of sulfur balsam with silver carbonate is carried out by mixing both components in a ratio of 10: 1

in a bakeable and chilled vessel at a temperature of 5O ⁰ C over a reaction period of two to three hours.

The silver crude resin solution obtained according to the invention is precipitated in gasoline, separated from the liquid constituents, and dried

and the silver content determined.

The present powdery amorphous silver compound, the silver content is 50-55%, is in the respective Listed noble metal preparation, such as in a glossy gold for brushing with a golden yellow color after the Decoration firing:

Designation of the component Proportion (% by mass) Gold resinate (60% gold) 20, - Silver in the form of the compound described (53% silver) 1.13 liquid VjOs carrier (2% V ₂ O ₅ ) 8.55 Liquid Rh ₂ O _{3 support} (3.2% Rh ₂ O ₃ ) 1.73 liquid Cr ₂ O ₃ carrier (2.32% Cr ₂ O ₃ ) 0.89 f! üss>! gjrBi ₂ O _{3 support} (8.27% Bi ₂ O ₃ ) 1.61 Solvent mixture 26, - Resin solution in essential oils 40, -

The characteristics of the bright gold preparation, viscosity, evaporation and stoving temperature of the silver-containing preparations are influenced by the inventive addition of the silver compound, but compensated by varying the formulation proportions of solvents and resin solution to the proportions in silver-free preparations.

Claims (3)

1. A process for the preparation of a silver compound for use in precious metal preparations for decorative purposes of silikatiscr s products, in particular of glass and porcelain products, characterized in that silver carbonate is reacted with a sulfur balm in the ratio 1:10 at 5O ⁰ C. 2. The method according to item 1, characterized in that the sulfur balm prepared by heating and evaporating the starting components of the components Venetian larch turpentine 40-45% Sulfur powder 10-15% Portuguese turpentine oil 40-46%
consists. 3. The method according to item 1, characterized in that the silver carbonate is used as a homogeneous, finely divided powder without agglomerates.