JP2007511668A - How to cover copper with patina - Google Patents

Abstract

A process for patinating articles comprising copper or a copper alloy is described. The articles to be patinated are treated with a preferably aqueous patination solution which preferably contains copper ions and zinc ions and are subsequently subjected to a maturing process. This is, in particular, carried out in a temperature- and humidity-controlled chamber.

Description

  The present invention relates to a method for producing patina on an article comprising copper or a copper alloy and a patina solution for use in the method.

  It is generally known that when a copper part is exposed to weathering for long periods of time, a greenish layer with a protective function is formed on its surface. This layer is said to be copper patina. At our tolerance, it usually takes 10-15 years for the copper surface to be completely covered with a green layer. Various methods have been developed in the past to shorten this long period in order to mimic or easily produce natural patina on the copper surface.

Thus, for example, US Pat. No. 3,497,401 discloses a method and reaction solution for producing patina. Here, the copper part is immersed in an acidic aqueous solution containing potassium chlorate and copper sulfate at room temperature. US Pat. No. 5,160,381 also describes a method for producing patina on copper articles. In the multi-stage process described therein, the copper parts that produce patina are treated with an aqueous solution containing copper, sodium, acetate, chloride, sulfate, H ⁺ and OH ⁻ ions after cleaning. After careful cleaning and drying, the copper parts are treated with an aqueous solution of copper carbonate, ammonium chloride, copper acetate, arsenic trioxide, copper nitrate, and hydrochloric acid in a second process step. EP 0 947 701 also relates to the production of patina by treating copper articles with an aqueous copper salt solution again. This method is particularly suitable for pre-oxidized copper surfaces.

  However, the known methods have a number of disadvantages. Thus, components that are toxic and harmful to health, such as arsenic trioxide described above, are used in the preparation of some known patina solutions. It is desirable to avoid the use of such components for environmental reasons and for health. Other methods have limited applications. Thus, some methods are generally not well-suited for the greening of untreated copper surfaces because they require pre-oxidation of the copper parts that are to be bluish.

  With respect to qualitative properties as well, with respect to optical and mechanical aspects, many synthetically produced patinas exhibit defects. They often have unsatisfactory adhesion, in other words, the artificial protective layer peels off even under light mechanical stress.

  Accordingly, it is an object of the present invention to provide a method that avoids the disadvantages of the prior art and solves as many of the problems shown.

  This object is achieved by a method having the features of claim 1. Preferred embodiments of this method are described in the dependent claims 2-20. Furthermore, the present invention encompasses novel patina solutions having the features of claim 21 and claims 22-24 dependent thereon. The wording of all claims is hereby incorporated by reference into this description.

  In the method of the present invention, an article containing copper or a copper alloy is preferably treated with a patina solution containing copper ions and then subjected to an aging step.

  The aging process consists of individual aging stages, including selection of atmospheric humidity and temperature. The setting and control of the two parameters temperature and atmospheric humidity can be easily carried out in particular in the temperature and humidity regulation room provided for this purpose.

  The preferred order of aging steps can be summarized as follows. That is, following treatment of the article with the patina solution, particularly the application of the patina solution to the article to be patinaized, the article is rested at a first rest temperature and a first rest atmospheric humidity for a first rest time. The article is then washed at least once during the wash time at the wash temperature and wash atmospheric humidity, and then again the article is paused at the second and second pause atmospheric humidity for the second pause time. Let

  During the first pause phase, particularly in the temperature and humidity control chamber, the temperature is preferably in the range of 20 ° C. to 70 ° C., in particular 25 ° C. to 55 ° C. (first pause temperature). The atmospheric humidity is preferably in the range of 30% to 90%, in particular 40% to 50% (first resting humidity). These preferred ranges of temperature and atmospheric humidity indicated in the first quiescence phase essentially coincide with the preferred ranges of the second quiescence temperature and second quiescent atmospheric humidity.

  During the washing phase, the temperature in the temperature and humidity control chamber is preferably in the range of 20 ° C to 70 ° C, especially 25 ° C to 55 ° C. The atmospheric humidity during the washing phase is preferably maintained in the range from 30% to 95%, in particular in the range from 65% to 80%. Cleaning is usually performed by spraying water on the treated article. This stage is repeated 4-5 times, preferably at intervals of 90 minutes to 2 hours.

  The first downtime may be 1 week or less, preferably a period of 2 to 3 days. The same applies to the second downtime. The washing time is usually 1 day or less, but can be as short as 5 to 10 hours.

  As mentioned above, the patina solution used is a solution containing copper ions, but its preferred composition will be described in more detail below. Furthermore, it will be emphasized that it is particularly preferred that the article to be bluish has a cleaned and / or roughened surface prior to application of the patina solution. Any grease or oil residue present on the surface and other contaminants can have an adverse effect on the patina adhesion formed. This is particularly suppressed by spraying with broken glass spheres on the surface to be chemically degreased and / or patinaized. Alternatively, for example, an eccentric or belt sander can be used.

  The article to be patinaed is subjected to an aging process, if appropriate after the optional pretreatment of the indicated type, preferably by moving it to the temperature and humidity control chamber described above. Although not absolutely necessary, it is preferred that the patina solution is applied in that chamber.

  The patina solution is preferably applied in finely divided form, particularly preferably sprayed. The temperature (preferably in the temperature and humidity control chamber) is in the range of 30 ° C to 70 ° C, in particular 40 ° C to 55 ° C, during this application. The patina solution is usually applied in at least 2, preferably 4 or 5, processing steps, especially at intervals of about 1 hour.

  Compared to the classic method of greening copper parts, consisting essentially of a single or multiple treatments with aqueous copper salt solution and subsequent air drying steps, especially in the aging process in temperature and humidity control chambers Use has surprisingly been found to provide significant advantages, particularly with respect to the aesthetics and quality of the patina produced. The formed patina gives a uniform and intense color impression.

  Post-treatment of the newly created patina surface can optionally be performed. It is possible to lighten or darken the surface. Since unsealed patina can sometimes react further under the influence of natural weather, the surface can also be sealed if appropriate.

  The method shown is preferably provided for the greening of copper plates, strips, or roofs. However, it can in principle also be applied to all shaped parts or articles comprising copper or copper alloys. Partial paving of shaped parts such as eaves is also possible. Thus, for example, in the case of eaves, the zone of the weld metal band can be strongly bluish, whereas the outside of the channel is only oxidized. This results in a visual impression that the copper parts have been exposed to the atmosphere for several years or decades. Such effects are often used in the visual construction of new buildings, but are used to obtain a comprehensive historical impression, especially in the repair or repair of relatively old designated buildings. The

  Further features of the patina produced by the method of the present invention are resistance to mechanical stress and excellent adhesion.

  These preferred properties are preferred and are also considered due to the patina solution that is the subject of the present invention. It consists of an aqueous solution in which a copper salt, preferably copper nitrate, is present in a proportion of 20% by weight or less, in particular in a proportion of 3% to 5% by weight. Zinc salts, in particular zinc chloride, are preferably present in the solution, preferably in a proportion of 0.1% to 5% by weight, in particular in a proportion of 0.2% to 1% by weight. In addition, the solution may contain various chloride and carbonate additives, particularly sodium chloride, ammonium chloride, calcium chloride, and ammonium carbonate. The pH of the patina solution is preferably in the basic range, in particular in the slightly basic range of pH 7-10.

  Of the components present in the patina solution of the present invention, zinc salts are desired to be particularly emphasized. The addition of zinc salt has a clear effect on the patina adhesion formed. Moreover, such addition produces a bright green appearance.

  Finally, the invention encompasses a patina article comprising copper or the copper alloy itself (claims 25 and 26 and its dependent claims 27 and 28). After completion of the aging process, the article is applied with a green-turquoise patina solution that also contains copper ions, and preferably zinc ions. The patina usually has a thickness of 0.02 to 0.06 mm, especially 0.03 to 0.05 mm.

  Further features of the invention are derived from the following examples in connection with the dependent claims. Here, the provided features and properties may be realized in each case alone or in combination of a plurality thereof.

  To produce the patina solution, the following ingredients are dissolved in 1 L of water: 40 g copper (II) nitrate, 3 g zinc chloride, 8 g calcium chloride, 2 g sodium chloride, and 20 g ammonium chloride.

  The temperature and humidity adjustment chamber has a bottom surface of about 3 × 2.5 m. The surface is thoroughly polished by means of an eccentric sander and a sheet of copper free from grease and other contaminants is placed in a temperature and humidity control chamber. Adjust the temperature and humidity chamber temperature to 50 ° C. At this temperature, the patina solution is sprayed four times on the surface of the copper piece, in each case at one hour intervals. The temperature is maintained at about 45 ° C. for a subsequent first downtime. Adjust atmospheric humidity to about 45%. After the copper sheet is rested for 3 days, the treated copper parts are washed several times. It is sprayed with water for a total of 5 times at 90-minute intervals in each case. During this time, the atmospheric humidity in the humidity control chamber is about 75%, and the temperature in the case of treatment with a patina solution is about 50 ° C. The operating conditions of atmospheric humidity and temperature are then lowered again to 45% and 45 ° C., respectively, and the copper sheet is rested for another 3 days. Then, palpitation is terminated. The copper sheet is completely and uniformly covered with an artificial protective layer.

Claims (28)

  A method of producing a patina on an article comprising copper ions, in particular by means of an aqueous patina solution, comprising copper or a copper alloy, wherein the article is treated with a patina solution, and preferably the article is coated with the patina solution. And subjecting the article thus treated to an aging step.   2. A method according to claim 1, characterized in that during the aging step, temperature and atmospheric humidity are selected, preferably adjusted in a temperature and humidity adjustment chamber. The aging process is the next aging stage:
1) suspending the treated article at a first pause temperature and a first pause atmospheric humidity for a first pause time;
2) the treated article is washed at least once during a washing time at a washing temperature and washing atmospheric humidity, and 3) the treated article is washed at a second pause temperature and second during a second pause time. 3. A method according to claim 1 or 2, comprising resting at a resting atmospheric humidity.   The resting temperature is in the range of 20 ° C. to 70 ° C., in particular 25 ° C. to 55 ° C., and the resting atmospheric humidity is in the range of 30% to 90%, in particular 40% to 50%. Item 4. The method according to Item 3.   5. A method according to claim 3 or 4, characterized in that the second quiescent temperature essentially corresponds to the first quiescent temperature and the second quiescent atmospheric humidity essentially corresponds to the first quiescent atmospheric humidity.   The cleaning temperature is in the range of 20 ° C to 70 ° C, in particular 25 ° C to 55 ° C, and the cleaning atmospheric humidity is in the range of 30% to 95%, in particular 65% to 80%. Item 6. The method according to any one of Items 3 to 5.   The method according to any one of claims 3 to 6, characterized in that the first downtime and the second downtime are each one week or less, preferably 2 to 3 days.   The method according to any one of claims 3 to 7, wherein the washing time is 1 day or less, preferably 5 to 10 hours.   The patina according to the preceding claim, characterized in that the patina solution contains at least one copper salt, preferably copper nitrate, in a proportion of 1.5% to 20% by weight, in particular in a proportion of 3% to 5% by weight. The method according to any one.   A method according to any preceding claim, wherein the patina solution comprises at least one zinc salt, preferably zinc chloride.   11. Process according to claim 10, characterized in that the patina solution contains zinc salt in a proportion of 0.1% to 5% by weight, in particular in a proportion of 0.2% to 1% by weight.   A process according to any of the preceding claims, characterized in that chloride and carbonate additives, in particular sodium chloride, ammonium chloride, calcium chloride and / or ammonium carbonate, are present in the patina solution.   The method according to any one of the preceding claims, wherein at least one surface treatment selected from the group consisting of surface cleaning and surface roughening is performed prior to the processing of the article.   14. Method according to claim 13, characterized in that the cleaning procedure is degreasing, in particular chemical degreasing.   15. A method according to claim 13 or 14, characterized in that the roughening treatment is a grinding or spraying treatment, in particular sandblasting with glass.   A method according to any of the preceding claims, characterized in that the patina solution is applied in a finely divided form, in particular sprayed.   Process according to any of the preceding claims, characterized in that a treatment temperature in the range of 30 ° C to 70 ° C, in particular 40 ° C to 55 ° C, is selected in the treatment of the article using the patina solution.   A method according to any of the preceding claims, characterized in that the patina solution is applied in at least two, preferably 4-5, processing steps.   The method according to any one of the preceding claims, wherein a post-treatment of at least one surface selected from the group consisting of surface sealing, lightening and darkening is performed after the aging step.   8. A method according to any preceding claim, wherein the article producing the patina is selected from the group consisting of plate-like materials, strip materials, molded parts and ornaments.   A patina solution that produces patina in an article containing copper or a copper alloy, preferably in the form of an aqueous copper salt solution, the solution comprising zinc ions.   22. A patina solution according to claim 21, characterized in that it contains zinc salts, in particular zinc chloride, preferably in a proportion of 0.1% to 5% by weight, in particular in a proportion of 0.2% to 1% by weight. .   23. The at least one copper salt, preferably copper nitrate, is present in a proportion of 1.5% to 20% by weight, in particular in a proportion of 3% to 5% by weight. Patina solution.   24. The patina solution according to any of claims 21 to 23, characterized in that chloride and carbonate additives, in particular sodium chloride, ammonium chloride, calcium chloride and / or ammonium carbonate are present in the solution.   A patina article comprising copper or a copper alloy that can be produced by the method according to any of claims 1-20.   A patina article comprising copper or a copper alloy produced by the method according to claim 1. 27. A patina article comprising the copper or copper alloy of claim 25 or 26, which has the following structure:
1) a substrate containing copper or a copper alloy selected from the group consisting of a plate-like material, a band-like material, a molded part and a decorative article, and 2) at least one patina which is located on the substrate and contains copper ions and zinc ions,
A patina article characterized by comprising:   28. The patina product according to any one of claims 25 to 27, wherein the patina has a thickness of 0.02 to 0.06 mm, particularly 0.03 to 0.05 mm.