WO2017005287A1 - Antique brass-tarnished gemstone setting - Google Patents

Abstract

The invention relates to a method for partly artificially tarnishing a gemstone setting. The antique brass tarnishing is characterized by an appearance that corresponds to a natural aging progression and is protected by a protective layer. The invention also relates to products produced by the method.

Description

 Gemstone setting with antique brass discoloration

Field of the invention

The invention relates to a process for the production of an artificial "antique brass discoloration" on a blank of a gemstone setting, as well as the products which are produced by this process. The "antique brass discoloration" is protected from environmental influences by a protective layer.

PRIOR ART For the design of gemstone casings, it is often desirable that the metallic parts assume a characteristic appearance created by weathering and aging. In particular, gold receives a characteristic partially matt, darker appearance due to weathering and aging. The natural aging process takes much too long for the production of jewelry. Therefore, it is desirable to artificially produce this effect.

In jewelery production, a jewelery base is often made of a low-cost material, for example brass, a copper-zinc alloy or pure zinc. Brass has a gold-like appearance and is cheaper than gold. Natural aging of the gold or brass results in partial surface discoloration. By wearing on the skin, as is usually the case with jewelery, the desired "Vi ntage effect", would become very unsightly as a result of the reaction with sweat after a short time, it is therefore desirable to develop a brass discoloration, which in particular in the jewelry sector the decorative demands of a "vintage effect" and the wearing requirements, especially a protection against skin sweat, is sufficient.

From US 7,018,677 B2 and US 8,007,866 B2, the artificial production of an aging effect of copper is already known. The artificial production of the natural aging effect of gold is not described. In US 8,956,510 B2 the coating of jewelry is described. Although the manufacture of coatings is well known for jewelry, it does not cite the generation of a natural aging effect of gold. US 2009/0139264 A1 describes the production of an antique gold effect for jewelery. Signs are engraved on the jewelry surface and the jewelry weathers only during use. All of these methods are expensive because they require a multilayer buildup. Object of the present invention is to realize an artificial "antique brass discoloration" on a gemstone setting, which is also friendly to the skin, does not react with sweat, has good adhesion and protects against mechanical erosion, such as scratches.

Description of the invention

Surprisingly, it has been found that the natural "Vi ntage effect" of the gold or brass can be artificially produced by the "antique brass discoloration" by the inventive method and the surface of the gemstone version by the use of a protective varnish does not react with sweat and is protected against mechanical erosion, for example scratches. For jewelery, this is of great importance, since the gemstone settings by the coating meet the wearing requirements. The subject of the present application is therefore a process for the partial discoloration of a gemstone socket, characterized by the following steps: a) partial application of a masking to the gemstone socket,

 b) aftertreatment of the gemstone socket with an oxidizing agent,

 c) removal of the mask from the gemstone setting and

 d) applying a protective varnish.

According to the invention are preferred jewelry in which the gemstone mount is made of brass or a brass-containing alloy, since brass is well suited for processing technical reasons and has a gold-like appearance. Brass and all other metals and alloys mentioned herein are used in the purity known to those skilled in the art.

Step a):

On the gemstone mount a partial masking is applied. The masking serves to leave areas of the surface of the gemstone setting free to be able to process them for the desired aging effect. The masking must be sufficiently resistant to oxidants. According to the invention, a stripping lacquer is preferably used for the masking. Peel-off coatings have the advantage that they can be applied to the material like a protective skin and then removed again without residue. Particularly preferred for the masking PVC Abziehlacke be used. Peel-off properties, such as adhesiveness, can be altered by monomeric and polymeric plasticizers. To apply the Abziehlackes there are a variety of ways, for example, there is the possibility of spraying or liquid application. The methods are the specialist well known. However, it is also possible to use as masks other paints and in general materials which can be applied as a mask and removed without residue and have sufficient resistance to oxidizing agents. The masking is preferably applied according to the invention with a stencil. The template can be made of a variety of materials, such as plastic, metal or textile. The template releases those areas that are to be further processed, the others remain covered.

Step b):

In method step b), the free areas of the masked gemstone casing are treated with an oxidizing agent. Potassium permanganate is preferably used as the oxidizing agent. For the treatment with the potassium permanganate, the gemstone collection is immersed, for example, in an aqueous potassium permanganate solution or sprayed with an aqueous potassium permanganate solution. The uncovered areas react with the oxidizing agent and are thereby discolored brownish.

Step c): Subsequently, the masking is removed with a solvent, for example ethyl acetate.

Step d): In process step d), a protective lacquer is applied to the gemstone casing. The protective varnish prevents the metal parts from reacting with the sweat of the skin and also improves the resistance of the metal layers. According to the invention, varnish is understood as meaning a liquid or pulverulent coating material which is applied thinly to objects and is built up by chemical or physical processes, for example evaporation of the solvent, to form a continuous, solid layer. Paints often contain binders, fillers, pigments, solvents, resins and / or acrylates and additives, such as biocides. Suitable examples are acrylic lacquers, epoxy lacquers or polyurethane lacquers.

Acrylic paints are manufactured on the basis of acrylic resins. Acrylic resins are synthetic resins and are considered particularly durable. Acrylic resins are based on polymers or copolymers of acrylic acid or methacrylic acid and their esters. They are often copolymerized with other unsaturated monomers, such as styrene or acrylonitrile. Acrylic paints are either dissolved in solvents or dispersed in water and applied to the coated gemstone mount. Acrylic coatings have a high weather resistance and are UV-resistant and are therefore particularly well suited according to the invention. Epoxy paints often contain the two components epoxy resin and hardener. Epoxy resins are polyadducts of epichlorohydrin with bisphenol derivatives, for example A, F or S. These are crosslinked with a hardener. Usually, the two components epoxy resin and hardener are mixed shortly before processing. Epoxy coatings are characterized by high chemical and mechanical resistance, but are not optimal in terms of UV resistance.

For polyurethane coatings, the urethane group is characteristic. They are commercially available as one-component and multicomponent coatings, for example the hardener is already mixed with the base coat in the case of one-component lacquer and the hardener and base coat are separated in the two-component lacquer. Polyurethane coatings are particularly hard, abrasion resistant and resistant to water, oils and chemicals.

According to the invention, a polyurethane varnish is preferably used as the protective varnish. Polyurethane paints have good adhesion properties and are resistant. Two-component polyurethane acrylic resin paints have proven to be advantageous, in particular the products DE 4259x from Hesse and Lignal, since they are saliva and sweat resistant according to DIN 53160. They can be applied without thermal aftertreatment and are lightfast.

Before applying the masking a) the gemstone socket can optionally be cleaned or degreased. Degreasing is the removal of adhering fats, oils or other contaminants with degreasing agents. The cleaning or degreasing of, for example, brass has the advantage that the adhesion of the protective coating d) is improved.

The cleaning can be done mechanically, with solvents, for example ethyl acetate, or else with ultrasound, for example with the Evolution WP-K device from German Sonic. Another option for pretreatment is electrolytic degreasing. In electrolytic degreasing, the gemstone socket is in an electrolytic solution and is then cleaned by applying a current. In electrolytic degreasing, a distinction is made between cathodic and anodic degreasing. The cathodic degreasing proceeds under hydrogen evolution and the anodic degreasing under evolution of oxygen. The cathodic degreasing is preferably used because it can be achieved in the jewelry bodies such as brass very good cleaning. For degreasing of brass parts is especially the cathodic, alkaline electrolytic degreasing. To further improve the adhesion of the resist d), prior to application of the resist to, for example, brass, the brass surface may optionally be treated with acid to remove oxide layers. Sulfuric acid has proven to be advantageous for the cleaning of brass jewel casings. To enhance the Vi ntage- effect can be roughened, for example brass optional before applying the partial masking a) the surface of the gemstone. The gemstone socket thus receives a surface that corresponds to a surface caused by weathering and aging. The brass is preferably dipped in nitric acid.

The optional cleaning or degreasing and the optional roughening of the surface of the gemstone setting can be done in any order. Another object of the application are products which are obtainable by the process according to the invention. The preferred embodiments of the process lead to inventively preferred products.

General process description

The gemstone frame is optionally cleaned or degreased. For degreasing of brass parts is especially the cathodic, alkaline electrolytic degreasing. In this degreasing, the solution contains, for example, caustic soda and surfactants. The degreasing is carried out for a period of at least 1 minute, a temperature of 35Ό - 55Ό and a current density of at least 3 A / dm ^2, for example with the 1018 agent IWG-Plating Vienna. Thereafter, the gemstone socket is cleaned with deionized water.

In order to remove oxide layers from the brass surface, treatment of the gemstone casing with 5-15% sulfuric acid (% by weight) has proven to be advantageous. The gemstone socket is immersed in the sulfuric acid according to the invention for about 1 minute. Thereafter, the gemstone socket is cleaned with deionized water.

To optionally roughen the surface of the brass gemstone casing, the brass is immersed in nitric acid (about 55 to 65% by weight) for at least 20 seconds.

In process step a), a masking is partially applied to the gemstone socket. There are various possibilities for this, for example by spraying or by liquid application, in that according to the invention a stencil is preferably used. For masking, for example, peelable coatings, for example Redowax 1 12 from Erne or Galvanolack GC 1 10 from Adhesive Products, are suitable on account of their adhesion properties.

In process step b), the masked gemstone casing is aftertreated with an oxidizing agent by being immersed for at least 20 seconds in an aqueous potassium permanganate solution (about 10 to 15% by weight) with a solution temperature of about 70 ° to 90 °. The masked Gemstone socket receives by the reaction with the oxidizing agent at the left by the masking sites a brownish discoloration.

In step c) of the process, the masking is removed with a solvent, for example ethyl acetate.

In process step d), a protective varnish is applied to the gemstone casing in order to prevent, for example, the reaction of skin sweat with the gemstone casing. As a protective varnish, acrylic varnish, epoxy varnish, for example Duralit 1516-754 S from Rohm and Haas or also polyurethane varnish can be used. A two-component polyurethane-acrylic resin paint, for example DE 42597-0040 from Hesse & Lignal, has proved to be advantageous.

Inventive Example (FIG. 1)

A gemstone setting made of brass received in the following way an "antique brass discoloration".

The gemstone frame made of the FRMSBR alloy from AGS Alpha Guss Metals and Alloys GmbH Pforzheim was degreased electrolytically with the agent 1018 from IWG-Plating Wien for 5 minutes at a temperature of 45 ° and a current density of 5 A / dm ² . Thereafter, the degreased brass parts were washed with deionized water.

For removal of oxide layers, the brass jewelery frame was dipped in 10% sulfuric acid (wt.%) For about 1 minute. Thereafter, the gemstone socket was washed again with deionized water. Subsequently, the gemstone socket was immersed in nitric acid (60% by weight) for about 30 seconds.

On the acid-treated gem stone mount the masking was partially applied with the stripping Redowax 1 12 from Erne.

Subsequently, the masked gemstone socket was immersed in an aqueous 10% potassium permanganate solution (wt%) at about 80 ° C for about 30 seconds.

The stripping lacquer was removed with the solvent ethyl acetate.

The gemstone socket was coated with the protective coating by being dipped in the two-component polyurethane-acrylic resin paint DE 42597-0040 from Hesse & Lignal and dried at about 25 ° C. for a period of about 14 hours.

Claims

Claims Gemstone setting with antique brass discoloration 1 . Process for the partial discoloration of a gemstone socket, characterized by the following steps: a) partial application of a masking to the gemstone socket,  b) aftertreatment of the gemstone socket with an oxidizing agent,  c) removal of the mask from the gemstone setting and  d) applying a protective varnish. 2. The method according to claim 1, characterized in that the gemstone mount is made of brass or a brass-containing alloy. 3. The method according to at least one of the preceding claims, characterized in that for the masking in step a) a stripping is used. 4. The method according to at least one of the preceding claims, characterized in that the masking in step a) is applied with a template. 5. The method according to at least one of the preceding claims, characterized in that for the post-treatment in step b) potassium permanganate is used as the oxidizing agent. 6. The method according to at least one of the preceding claims, characterized in that a polyurethane varnish is used as the protective varnish in step d). 7. Gemstone socket, obtainable by a method according to at least one of the preceding claims.