CZ20021055A3 - Method for obtaining colored coating on small glass objects - Google Patents

Abstract

Small glass articles of artificial jewellery are preheated to a temperature ranging from 50 to 100 degC, subsequently a coloring mixture based on sol-gel is applied to the surface thereof in an amount of 5 to 20 ml per one square mete of the surface. The coloring mixture contains 10 to 70 parts by weight of a primary colorless sol-gel based substance, 10 to 70 parts by weight of a solvent based on organic compounds being selected from the group consisting of alcohols, and 1 to 7 parts by weight of a coloring concentrate. The small glass articles move vigorously within an open and exhausted area until organic substances are removed by spontaneous vaporization from the coloring mixture and the mixture preliminary hardens. Subsequently final hardening of the colored coating on the small glass articles at temperatures ranging from 140 to 250 degC takes place on a mechanical device.

Description

Technical field

The invention relates to a process for obtaining a colored coating on small glass articles, in particular jewelery, in which a sol-gel-based coloring composition is applied to the pre-cleaned and preheated glass articles, in particular jewelery articles.

BACKGROUND OF THE INVENTION

Small glass colored objects, especially jewelery, are obtained in various ways. Either the glass is dyed directly in the mass, so that the desired coloring is obtained depending on the glass composition, the range of which is limited by the coloring properties of the coloring components.

Alternatively, the small glass blank is melted from a particular type of glass, e.g., alabaster, crystal, transparent, milky, richly colored, or opaque glass, and the glass is further surface-treated with a color coating. Washing and surface treatment to remove dust and impurities, including organic ones, are required prior to refining. The resulting colored coating may be metallic shiny, iridescent, natural colors, matte, etc.

Various methods are used to obtain colored coatings, such as reducing the metal layers, waxing, and depositing the precious metals and organic metal compounds. Furthermore, synthetic dyes, dissolved in solvents, most commonly nitrocellulose lacquers, dipping and spraying are used. This colored coating is normally applied by dipping into a bath of nitrocellulose lacquers or spraying them. This gives a glossy colored surface.

A colored coating is also used, wherein the carrier element of the colored pigment is shellac. Advantage is cost, easy process, disadvantage is low resistance to mechanical damage, solubility in sprays, i.e. essentially ethanol and organic solvents, low light fastness.

It is known to use aqueous dye solutions which are affordable, easy to apply, hygienically safe, but the products lack brilliance, and in particular for edge products, the paint is trapped in a thinner layer while the thick layer peels under mechanical stress.

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Epoxy dyes are also used, but are intended for a narrow range of glass products, and in particular for saturated undercoats. However, this application is not suitable for industrial application, since the products have to be threaded by hand, which is laborious and relatively expensive. After application of the paint remains peel, which reduces the aesthetic appearance and quality.

It is known to apply a sol-gel-based composition to the surface of glass bottles in aqueous solutions, which has been tried unsuccessfully to apply to small glass jewelery blanks. These prior art sol-gel compositions are very difficult to apply to small jewelery blanks because the water evaporates for a long time and hydrolysis occurs. The rate of evaporation of the water in the machinery from the sol-gel mixture is essentially unsolvable with a quantity of about half a million tiny glass objects. The previously known sol-gel compositions cannot be applied to the required amount and surface of the tinted glass articles.

The object of the present invention is to obtain new colors and shades by the sol-gel method for the mass upgrading of small glass jewelery articles.

SUMMARY OF THE INVENTION

These disadvantages are eliminated or substantially reduced in the process of obtaining a color coating on small glass especially jewelery articles according to the invention, which is characterized in that the glass objects are preheated to a temperature of 50 to 140 ^° C throughout the mass, after this uniform preheating is inserted to the dyeing device, where the dyeing composition is metered onto the surface of the dyeing composition as the glassware is intensively moved in the open and exhausted space of the dyeing device in the first phase until organic alcohol from the sol-gel dye mixture flows. In this first process stage, the dye mixture is pre-cured under the effect of heat, and in a second process stage the final curing of the color coating is carried out on another machine.

The second step of shaping the dye composition is carried out at temperatures of 140 to 250 ° C.

The staining composition is metered onto the preheated glass blanks in the first phase in an amount of 5 to 20 ml of staining composition per m ² of glass article surface.

The dye composition contains up to 70 parts of a colorless sol-gel base, up to 70 parts of an organic solvent based alcohol group, 1 to 7 parts of a coloring concentrate.

The main advantage of the present invention when using a sol-gel-based dye composition is a significant improvement in the quality of the decorative color coating which is uniformly applied over the entire surface of small glass articles, especially jewelery, including their edges. The color coating obtained according to the invention has a high brilliance and lightfastness, resistance to mechanical damage, chemical resistance to water and sweat, to acids, bases and organic solvents in parmigas and deodorants. The color coating is also resistant to petrol and toluene in dry cleaning of jewelery small items, even during normal washing in automatic washing machines.

Pre-heating of glass blanks throughout the mass allows easy and quick application and repeatability of the application of the dye mixture. Intensive movement of objects with the applied dye mixture ensures uniform coloring, including edges and holes. The open and exhausted space allows rapid dilution of the solvents and contributes to the fact that the still uncured color coating does not stick and rub on the large amount and surface of the treated glass objects. The defined curing temperature range is optimal for individual product types due to curing speed.

Preferably, the pre-curing of the dye composition is carried out discontinuously, the final curing continuously.

Long-term tests have found a defined concentration of the applied dye composition on the surface of articles as well as the composition of the dye composition for this dyeing technology. From the point of view of technology, especially of automated machine production, it is important to find the optimum concentration of the coloring composition so that the coloring composition adheres to the glass objects, retains it during the process, does not rub and resists the mechanical coating of small glass objects. The experimentally tested range of defined pre-heating temperatures ensures uniform application of the dye mixture and shortens the dyeing cycle due to wiping. The intensive mixing of the workpieces in the open space contributes to accelerating the evaporation of the diluent from the dye mixture and preventing abrasion of the still uncured dye surface. This also makes it easy to change colors in operation without unnecessary downtime.

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Examples

Glass blanks, such as rocailles or tubes, made of crystal or opal glass, with a diameter of, for example, 1.4 to 12 mm, with an internal hole, are rinsed with water to remove their mechanical impurities. It is then dried.

The seed beads are heated to 50 to 100 ° C throughout the mass, depending on the size of the glass article and the type of glass. The heated objects are placed in a production facility where they are intensively mixed and are in constant motion, in an open and exhausted space. Depending on the surface area of the glass article, 60-100 ml of the dye mixture is dispensed into the apparatus per m ² of solution surface.

The preformed coloring composition contains

- sol-gel base substance, eg the trade name ORMOGLASS or ORMOSOL, DE,

- organic solvent based on alcohols, eg ethyl alcohol or isopropyl alcohol,

- concentrated dyeing components manufactured by HERAUS, DE, suitable for sol-gel base substance.

A coloring composition is prepared consisting of 10 to 70 parts of a colorless sol-gel base, up to 70 parts of an organic solvent, up to 7 parts of a coloring concentrate.

The staining composition is chosen so that the glass objects are sufficiently colored throughout the entire area and the hole and to prevent damage to the color layer, for example by abrasion.

The individual components are mixed prior to the cold dyeing themselves and dispensed evenly onto the pre-heated small glass blanks while moving intensively.

The dye mixture is vigorously stirred during dyeing to ensure uniform application of the dye, rapid evaporation of the diluent, but at the same time no sticking. In a very short time, in the order of seconds or minutes, for example from 2 to 90 seconds, the organic solvent will evaporate and the silica gel will partially cure, allowing subsequent safe handling for the next final curing process.

On another machine, such as a heating furnace, a final curing operation is performed in the temperature range of 140 to 250 ^° C depending on the product type.

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This procedure allows the mass dyeing of small glass articles, for example in an amount of 20,000 to 50,000 pieces of small glass blanks per kg of such colored article. Usually, for example, 5 to 7 kg of small glass jewelery blanks are dyed.

The method according to the invention makes it possible to perfectly color uniformly the entire surface of the products, including the edges.

Thus, a colored layer having a thickness of about 0.1 to 10 microns, preferably about 1 micron, is obtained.

The method of the present invention achieves a wide variety of transparent colors. For visually saturated colors it can be used as a base for saturated white glasses, eg chalk, opal, or semi-cloudy alabaster, satin glass, etc.

The examples are not exhaustive and other embodiments of the invention are possible within the scope of the claims.

Industrial applicability

The method is suitable for machine mass production of small glass jewelery articles such as rocailles, glass tubes, chatons, fire polishes, machine cut stones, cut beads and other shaped jewelery articles.

Claims (4)

PATENT CLAIMS A method for obtaining a colored coating on small glass articles, comprising applying a sol-gel dye composition to pre-cleaned and preheated small glass articles, wherein the glass articles are preheated to a temperature of 50 to 100 ^° C in The whole mass, after uniform preheating, is placed in the dyeing machine, where the sol-gel-based dye mixture is dosed onto their surface while moving intensively in the open and exhausted space until the organic substances from the alcohol group escape from the dyeing mixture. the dye mixture pre-cures under the influence of heat, and then the final curing of the color coating is carried out on another machine. Method according to claim 1, characterized in that the final curing of the color coating is carried out at temperatures of 140 to 250 ° C. Method according to claim 1 or 2, characterized in that the coloring mixture is dosed on the preheated glass blanks in an amount of 5 to 20 ml of coloring mixture per 1 m ^{2 of} surface of the glass objects. Method according to claim 1 or 2 or 3, characterized in that the coloring composition comprises 10 to 70 parts of sol-gel base colorless substance, 10 to 70 parts of organic alcohol based diluent, 1 to 7 parts of coloring concentrate.