CS240080B1 - The method of decoration or marking of glass crystal products with silver glaze - Google Patents

Abstract

The invention relates to the field of glass and solves the problem of decorating or marking glass ceramic products by glazing. Controlled crystallization of the glass and firing of the decor take place simultaneously during (thermal) heating of the products for a period of 1 to 10 hours to a maximum temperature of 950 °C. When using the method according to the invention, the optimal composition of the glazing mixture and the method of its preparation were designed.

Description

Method of decoration or marking of glass crystalline mass products with silver glazing

Jesení is related to the glass industry and solves the problem of decorating or marking glass ceramic products by glazing.

controlled crystallization of glass and firing of the décor take place simultaneously during (thermal) heating of the products for 1 to 10 hours up to a maximum of 950 ° C. Using the process according to the invention, an optimum composition of the glazing composition and a process for its preparation have been proposed.

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240 080

2 the silver glazing or marking of glass-crystalline articles by applying a glazing composition comprising ocher, silver coloring ions, and carbon to the shaped and cooled glass article. The article 9e heats, while controlled crystallization of the glass and firing of the decor are performed.

Glassy crystalline materials are masses composed of inorganic, interconnected microcrystals dispersed in the base glass. Microcrystals are formed by the controlled crystallization of glass in the presence of nucleation enhancers. A mass with a uniform and fine-grained structure is obtained with a small residual glass phase content.

The process of glass ceramic production consists in melting of the glass material. After melting, the glass is formed into a later product shape by conventional glass forming technology.

The product thus obtained is subjected to thermal exposure at a temperature of 75 ° C ^to 120 ° C, at which a controlled crystallization produces a polycrystalline phase with a simultaneous change in basic properties - color change, reduced coefficient of thermal expansion and increased thermal shock resistance, increased mechanical strength and under.

Products made of glassy crystalline material can be color-coded according to their intended use, eg cooktop plates of electric cookers, or decorated in the case of cooking glass-ceramic dishes - see Z.Strnad: Glassy crystalline materials, Prague 1983 (atr. 110-121,98) ).

Však however, if a different color decoration is to be obtained on a white or otherwise colored glass ceramics background, the decoration technique commonly used in the glass industry can be used - enamels, screen-printed colors, decals, stamping and the like.

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Composition of glazes, enamels, and metal coatings for glassy-crystalline materials, particularly _in a low thermal expansion is shown e.g. in US Patent / 3 313 644. The glass was applied Decorative coloring agent mixture comprising nickel t / (chromium J

The NixCrl object is heated to 900-117 groups of Fe for up to 4 hours to simultaneously stain and glass the glass.

However, the surface of the glass ceramics is dull and the color changes during polishing, which removes residual paste deposits. These techniques result in reliefs of different heights, which cause difficulty in contacting the decorated or marked surface with another object, e.g.

Recently, a method has been used which dyees the glassy crystalline material by glazing. Is it most often done using afAg iont? The glazing composition provides ions capable of diffusing into the glass ceramic surface in exchange for alkali ions from the glass. Because ion exchange depends! for the concentration of active ions in the glazing composition, the concentration of alkali ions in the surface of the material, the treatment temperature and other factors, the low content of alkali ions in the surface of the glassy crystalline materials is balanced by a higher treatment temperature on the glazing composition. The surface layer then aggregates the overfused ions and creates color centers (see Bachtik, Pospíchal: Glass Refining,

Praha 1964, pp. 186-195).

The process of glazing while de-vitrification is disclosed in U.S. Pat. ^{No. 1} / 3775,154, wherein the glazing paste glass is subjected to a thermal exposure of at least 40 ° C. The glaze composition contains at a concentration of 5 to 1E ^

jiva.

In these methods, however, the surface of the glassy crystalline materials is often attacked chemically. The place where the product has a matt etched structure on the article. Another problem remains to wash the annealed glazing composition from the surface of the debris; this is often because the carrier components are melted into the residual glass phase.

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The glazing may also be carried out in a separate firing after the prior devitrification of the article, as described, for example, in a patent

U.S. Pat. No. 3,528,847. The glass 9e is first vitrified at a temperature of 850 to 85 ° C

1200 ° C and the surface of the glass ceramic is coated with a glazing paste consisting of a coloring ion, selected from the group consisting of TiCl 3, mercury. (str / bfo? fthoriurnj ^ o ^ dhahl ¹ ·· '

HgvfAg and tfiT further are from a carrier selected from the group consisting of

2 ° 3 _L ^ ity jirtconi ya

The plasticizer and wetting agent. Thereafter, the product is heated to a temperature of 500 to 850 ° C for a period of time sufficient to exchange alkali metal ions for coloring metal ions, which are converted to metal atoms under reducing conditions. This method requires dual heating. The color is strongly dependent on the devitrification and glazing temperature, and is difficult to reproduce.

The above-mentioned disadvantages are eliminated or substantially reduced by the method of glazing glass ceramics, which is characterized in that the product of silica, alumina and zinc-based glass is covered with a glazing composition consisting of 3 to 22% by weight of silver chloride, 8% of ocher and 0.5 to 1.5% of carbon. The ocher consists in weight concentration of 40 to 62% silica, 20 to 33% alumina and 20 to 29% ferric oxide. The ocher is annealed at a temperature of 300 to 600 ° C for 0.5 to 1.5 hours before mixing with the other components of the glazing composition. The product is heated at a temperature of up to 95 ° C for 1 to 10 hours.

This method is economically advantageous, controlled crystallization as well as firing of the decor simultaneously taking place at relatively low maximum temperatures compared to the prior art methods. Using the process according to the invention, an optimum composition of the glazing composition as well as a process for its preparation based on the available raw materials have been found using conventional glazing compositions and processes. If the procedure is followed, the color is thermally stable and easy to reproduce, does not create relief on the surface of the object and is easy to read. The glazing mixture is capable of regeneration, which ensures the use of precious metals, in this case silver.

An exemplary embodiment of □ as the starting glass for the product was a silica, alumina and zinc glass based on β-tin or zirconium nucleation. After melting »formed

- 4 240 080 and cooling the glass product, the glazing paste is applied by hand, screen printing, decals, stamping and the like to the surface of the product. The ocher is first calcined, e.g. at 35 ° C for 0.5 hour. The ocher is then mixed with the other components of the glazing composition, e.g. at a concentration of 86% by weight of ocher, 1% by weight of carbon and to achieve a lighter color, e.g. 12 & silver chloride. The mixture is wet-ground in ethyl alcohol, dried, homogenized and mixed with, for example, a screen printing oil using the screen printing method. The glazing paste thus obtained is applied to the surface of the product which is heated in the case of the above lighter coloration in total

2.5 hours up to 820 ° C, in the case of a darker color 6.0 hours up to 820 ° C. The heat treatment can take place in one or two stages. The particular method of heat treatment is chosen according to the type of glass, the content of the active component of the glazing, but also according to the size of the product in order to avoid its deformation or cracking.

After the heat treatment, the annealed glazing composition is removed from the decorated or labeled surfaces by a conventional mechanical procedure in an aqueous environment: only water can be used precisely because of the insolubility and the relative chemical stability of the sulfur trichloride by aggCT at these temperatures. Loose metallic silver also has coloring effects. The washed and dried mixture is added to the newly produced glazing mixture and, after homogenization, is ready for reuse.

Claims (1)

SUBJECT OF THE INVENTION 240 080 A method of decorating or marking glassware products with silver glazing, wherein a glazing composition comprising ocher, silver coloring ions and carbon is applied to a shaped and cooled glass product, and the product is heated while controlled crystallization of the glass and firing of the décor is carried out. characterized in that the silica, alumina and zinc glass products are coated with a glazing composition consisting in a concentration by weight of 3 to 22% silver chloride, 85 to 88% ocher and 0.5 to 1.5% carbon, wherein the ocher consisting of 40 to 62% by weight of silica, 20 to 33% of alumina and 20 to 29% of iron oxide, are annealed at a temperature of 300 to 600 ° C for 0.5 to 1 before mixing with the other components of the glazing composition. , 5 hours, and the product ee heated for 1 to 10 hours to a temperature of up to 950fc.