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INVENTION
Patent of the Russian Federation RU2160794
COMPOSITION FOR PROTECTION OF SURFACES OF METAL PRODUCTS AT LOCAL TREATMENT
Applicant's name: Joint-stock company of open type "Russian gems"
The name of the inventor: A. Flayte; Yuretskaya G.I.
The name of the patent holder: Joint-stock company of the open type "Russian gems"
Address for correspondence: 195272, St. Petersburg, Utkin Ave 8, Joint Stock Company "Russian Gems", Director of the Research Institute of Jewelry Industry Bakharev V.O.
Date of commencement of the patent: 1998.10.01
The invention relates to means for isolating the surfaces of metal products, mainly jewelry, with local, mainly electrochemical and chemical processing, and is intended for use in the jewelry industry, instrument making, machinery and local industries. The composition contains, by weight: a copolymer of butyl methacrylate with methacrylic acid (with a content of butyl methacrylate in the copolymer 95% by weight) 19,80-26,70; A copolymer of ethylene with vinyl acetate (with a content of vinyl acetate in the copolymer of 26-30% by weight) 0.85-1.00; Toluene 14,50-15,80; Butyl acetate 36.10-39.50; Ethanol 7.20-8.00; Butanol 14,50-15,80; Organic dye 0.10-0.20. The technical result: the composition for protecting the surfaces of metal products under local electrochemical and chemical treatment has been developed and reproduced, having high adhesion and electrical insulating properties and easily removable from metal surfaces after completion of local processing.
DESCRIPTION OF THE INVENTION
The invention relates to means for isolating the surfaces of metal products, mainly jewelry, in the case of local, mainly electrochemical and chemical processing, and is intended for use in the jewelry, instrument-making, machinery and local industries.
Electrochemical processes are required for compositions for the protection (insulation) of the surfaces of metal products, with their local processing, a number of specific requirements. Such compositions should be resistant to electrolytes and electric current; In the layer of the applied composition, there should be no point defects that contribute to the penetration of the electrolyte. Such compositions should also have a high adhesion to the metal of the article. When treated with protective compounds of jewelry, especially those obtained by electroforming, it is necessary that the drying be carried out at room temperature and in a short time. After the application of the electroplating, the removal of the composition should occur easily and without thermal or mechanical impact on the products.
Compositions are known for protecting the surfaces of metal products when they are locally processed, for example, cytop lacquers based on nitrocellulose (1). Nitrocellulose varnishes do not meet the requirement of high adhesion to the metal of the product.
Repeated application and long-term drying require other known formulations, such as bakelite or perchlorovinyl lacquers, as well as acid-resistant varnish BT-783 (2).
The closest in terms of essential features to the claimed is the composition (3) for the insulation of metal surfaces in electrochemical and chemical treatments based on methacryla-40, which also contains glue leuconate, methyl ethyl ketone and toluene with the following component ratio, in wt.%:
Methacryl - 41-45
Glue leuconate - 3-5
Methyl ethyl ketone - 25-28
Toluene - 25-28
In this case, methacryl-40 is used in the above composition as an electrically insulating film-forming substance, adhesive leuconate, being an electrically insulating film-forming substance, is used in this composition to increase the adhesion properties, and methyl ethyl ketone and toluene are used as methacryl solvents.
The composition is used in tool manufacture, however it is ineffective for a number of reasons for protecting the surfaces of such fine-processed products, like jewelry and similar products. Metakril-40 is a copolymer of butyl methacrylate with methyl methacrylate at 40 and 60 wt.% Of monomers, but does not contain any polar groups of the carboxyl type, which worsens the adhesion properties of the protective composition to the metal of the workpiece, especially precious metals, alloys. Glue leuconate, as is known in the literature and practice, is used for bonding rubber with metals, for which the rubber is subjected to hot vulcanization, but for the purposes of the invention, the protective composition must be dried at room temperature, at which adhesion properties of the leuconate adhesive obviously can not occur. The viscosity of the composition is too high and amounts to 150-100 V after IV-4, which negatively affects all its basic properties.
The task for which the invention is directed is the development of a composition for protecting the surfaces of metal products, including precious metal, with local processing, mainly electrochemical and chemical, with high adhesion and electrical insulation properties, which are preserved under drying conditions at room temperature, and easily Removed from the metal surfaces after the local treatment of the products.
The task is achieved due to the fact that the composition for protecting the surfaces of metal products under local electrochemical and chemical treatment contains electrically insulating film-forming substances, one of which is an acrylate-based compound and organic solvents, one of which is toluene, the composition further comprising an organic dye , And as an acrylate-based copolymer of butyl methacrylate with methacrylic acid, as an electrically insulating film-forming agent, an ethylene-vinyl acetate copolymer, and as organic solvents, butyl acetate, ethanol and butanol with the following component ratio, in wt.%:
The copolymer of butyl methacrylate with methacrylic acid (with 95% by weight butyl methacrylate in the copolymer) - 19.80-26.70
The copolymer of ethylene with vinyl acetate (with a content of vinyl acetate in the copolymer is 26-30% by weight) is 0.85-1.00
Toluene: 14.50-15.80
Butyl acetate - 36.10-39.50
Ethanol 7.20-8.00
Butanol - 14.50-15.80
Organic dye - 0.10-0.20
The proposed composition has a high adhesion to metallic surfaces, because the acids it contains contain polar, in this case carboxyl, groups.
Necessary electrical insulation characteristics of the composition are provided by high specific resistivity of the initial film-forming substances. Thus, p v of copolymer of butyl methacrylate with methacrylic acid (copolymer BMK-5 OST 6-01-75) is (1.08-1.38) · 10 13 Ohm · m, and p v of copolymer of ethylene with vinyl acetate (Savilen, TU 301-05-56-90) is in the range 10 17 -10 18 Ohm · m, while the film-forming closest analogue (methacryl-40) has a resistivity p v of only in the range (0.9-3.4 ) · 10 12 Ω · m.
An organic dye, for example Rhodamine 6G, provides the possibility of visual control of the application of the proposed protective composition to specified areas to be isolated during local treatment. As an organic dye, in addition to the basic dyes with color cations, which include Rhodamine 6G, colorants soluble in alcohols, fats, esters and other similar organic solvents (for example, fat-soluble blue anthraquinone, alcohol-soluble bordeaux C, etc.) can be used.
The drying time at room temperature of the applied protective composition is within 5-10 minutes. In this case, the composition layer is obtained evenly, which can not be achieved by using the composition - the closest analogue, because of the practically identical volatility of the solvents used in it.
The technical result of the invention consists in achieving the task that has not been achieved with the help of the closest analogue, namely: a composition for protecting the surfaces of metal products under local electrochemical and chemical treatment has been developed and reproduced. It has high adhesion and electrical insulating properties and is easily removed from metal surfaces after completion of the local Processing, which is confirmed by the data of Table No. 1 ("Properties of Protective Compositions Depending on the Presence and Ratio of Local Treatment of Surfaces of Metal Products"), which explains the essence of the invention.
- TABLE -
Table 1 shows the protective compositions NN 1-10, wherein the composition No. 1 corresponds to the closest analog, the compositions NN 2-6 of the inventive composition, and the compositions NN 7-10 are performed with a violation of the component ratio governed by the essence of the invention. It can be seen from the table that composition N 5 is the best for achieving the objective of the invention (see also "Example of concrete performance and application of the formulation"), and the yield beyond the regulated limits leads to a deterioration in the properties of the composition and makes it generally unsuitable for use.
An example of a specific design and application of the formulation
1. Manufacture of protective composition (see example N 5 in Table No. 1). 155.5 g (179 ml) of toluene, 361 g (410 ml) of butyl acetate, 74.5 g (94 ml) of ethanol, 149.8 g (184 ml) of butanol and 2.0 g Rhodamine 6G (as an organic dye). Stirring of these components was carried out for 1.0 min, a capacity was set in a water bath with t = 40-50 ° C. and, with constant stirring, a red color mixture of 248 g of butyl methacrylate copolymer with methacrylic acid 9.2 g of a copolymer of ethylene with vinyl acetate. As the composition reached the homogeneity state, it was cooled to room temperature (20-22 ° C).
2. Applying a protective compound to the surface of the product.
A brooch made of a low-melting alloy of tin, lead, and antimony was used as a sample for local gilding.
The brooch was coated with a layer of silver on top of the nickel sublayer. Before applying the protective compound for local gilding and in cyanide electrolyte, the surface of the product was degreased with ethyl alcohol, dried at room temperature, after which a protective composition was applied to the areas not subject to gilding in two layers. The drying time of each layer at room temperature was 10 minutes.
3. Treatment of the product after application of protective composition and drying.
After drying, the product was electrochemically degreased in a solution containing 30 g / l of Na 3 PO 4 , Na 2 CO 3 and NaOH at room temperature and U 
4 V for 1.0 min, washed with water t 40 ° C, then the product was decapitated in a 50% solution of hydrochloric acid, washed in cold water and subjected to local gilding in a cyanide electrolyte at D k = 0.6 A / dm 2 for 3.7 minutes. The product was then removed from the bath, washed with water and dried. The volume of the protective coating was produced by washing in acetone.
As a result, only specified parts of products were gilded, the protective layer did not have electrical breakdowns, there was no electrolyte entering the protective layer, and the protective layer itself was easily removable after the previous operations.
The positive results of using compositions that correspond to the regulated intervals of the content of the components are directly related to the fact that their viscosity is within (within B3-4) 60-94 s.
The invention for its use does not require the use of expensive equipment, non-standard equipment, scarce materials and components.
The proposed composition and technological process of its manufacture and application can be easily and repeatedly reproduced in the conditions of industrial production.
INFORMATION SOURCES
1. Electroplating in mechanical engineering. Handbook ed. M.A. Schluger M., Mechanical Engineering, 1985, vol. I, p. 89-90.
2. Ginberg A.M. Galvanotechnics, Sudpromgiz, 1965, p. 46-47,
3. The author's certificate of the USSR N 1601224, MKI 5 C 25 D 5/02, BI. N 39 of 23.10.90.
CLAIM
A composition for the protection of metal surfaces in a local electrochemical and chemical treatment comprising electroinsulating film-forming substances, one of which is an acrylate-based compound, and organic solvents, one of which is toluene, characterized in that the formulation further comprises an organic dye, and as The acrylate-based compound contains a copolymer of butyl methacrylate with methacrylic acid, as an electrically insulating film-forming agent, an ethylene-vinyl acetate copolymer, and butyl acetate, ethanol and butanol as organic solvents with the following component ratio, by weight:
The copolymer of butyl methacrylate with methacrylic acid (with a content of butyl methacrylate in the copolymer is 95 mass%) - 19.80 - 26.70
The copolymer of ethylene with vinyl acetate (with a content of vinyl acetate in the copolymer is 26 to 30% by weight) is 0.85 to 1.00
Toluene - 14.50 - 15.80
Butyl acetate - 36.10 - 39.50
Ethanol - 7.20 - 8.00
Butanol - 14.50 - 15.80
The organic dye is 0.10-0.20
print version
Date of publication 03.01.2007gg
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