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Anti-discolouring technology for copper alloy coin blank and special preparation for anti-discolouring thereof

A copper alloy and anti-tarnish technology, which is applied in the coating process of metal materials, etc., can solve the problems of discoloration and other problems, and achieve the effect of bright surface, remarkable anti-tarnish performance, and good consistency

Active Publication Date: 2005-09-28
CHINA BANKNOTE PRINTING & MINTING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The present invention reacts the prepared special anti-tarnish preparation with the copper alloy coin blank to produce a dense organic conversion film on the surface of the copper alloy blank, thereby delaying the discoloration time of the copper alloy blank and solving the problem of discoloration between processes and storage, transportation problem

Method used

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  • Anti-discolouring technology for copper alloy coin blank and special preparation for anti-discolouring thereof
  • Anti-discolouring technology for copper alloy coin blank and special preparation for anti-discolouring thereof
  • Anti-discolouring technology for copper alloy coin blank and special preparation for anti-discolouring thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] Copper alloy coin blank cake anti-discoloration process of the present invention:

[0060] 1. Annealing: annealing the copper alloy coin blank to make it reach the required hardness index;

[0061] 2. Pickling: Remove oxides on the surface of the copper alloy coin blank cake with a mixed solution of sulfuric acid and phosphoric acid for 25 minutes;

[0062] 3. Rinsing 1: Rinse the copper alloy coin blank cake for the first time with clean water for 8 minutes;

[0063] 4. Polishing: use SC-880, which is easy to clean, to polish and smooth the copper alloy coin blank cake, and the time is 26 minutes;

[0064] 5. Rinse 2: Rinse the copper alloy coin blank cake for the second time with clean water for 9 minutes;

[0065] 6. Anti-corrosion treatment: immerse the surface-clean, completely non-oxidized copper alloy coin blank cake in the special anti-tarnish preparation for 6 minutes. The surface of the flat cake forms an organic conversion film, that is, Cu-(-C 6 h 5 N ...

Embodiment 2

[0080] Copper alloy coin blank cake anti-discoloration process of the present invention:

[0081] Annealing → Pickling → Rinsing 1 → Polishing → Rinsing 2 → Anti-corrosion treatment → Rinsing 3 → Drying

[0082] After the copper alloy blank cake is annealed to reach the required hardness index, the surface oxide is washed away by acid solution. After leveling, the surface is clean and the metal surface is free of oxidation, and then enters the anti-tarnish preparation, where a chemical reaction occurs rapidly, and an organic conversion film is formed on the surface.

[0083] The anti-tarnishing preparation can adopt commercially available products.

Embodiment 3

[0085] The anti-discoloration process of the copper alloy coin blank cake of the present invention is the same as that in Embodiment 1.

[0086] Its anti-discoloration special preparation is composed of the following ingredients according to the proportion:

[0087] BTA (benzotriazole): 3g / l

[0088] Nonylphenol polyoxyethylene lauryl ether: 5g / l

[0089] Benzoic acid: 1g / l

[0090] Sodium phosphate: 10g / l

[0091] The preparation method of above-mentioned anti-discoloration special preparation is:

[0092] 1. First heat deionized water to 45 degrees Celsius, add nonylphenol polyoxyethylene lauryl ether 3g / l according to the above composition ratio, and add BTA 5g / l after it is completely dissolved;

[0093] 2. Add 1 g / l of benzoic acid according to the above ratio;

[0094] 3. Add sodium phosphate 10g / l according to the above ratio;

[0095] 4. Stir well.

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Abstract

The color change resisting process for copper alloy coin butt includes the steps of annealing, acid pickling, the first rinsing, polishing, the second rinsing, anticorrosion treating, the third rinsing and drying. The cleaned and smoothed coin butt is set inside color change resisting solution to produce chemical reaction forming organic conversion film on the surface. The present invention has copper alloy re-compounding corrosion inhibiting technology, and in the reagent with BTA and other compounds as effective components, the copper alloy butt produces chemical reaction to form compact organic conversion film and has inorganic molecule filling the gaps in complex compound, so as to isolate the butt from air and water and avoid electrochemical corrosion and color change.

Description

Technical field [0001] The invention relates to an anti-discoloration technology of copper alloy coin blank cake and a special preparation for anti-discoloration, which belongs to the surface treatment technology of copper alloy. Background technique [0002] With the development of economic globalization, the cooperation between the world minting industry is getting closer. Southeast Asian and Western developed countries tend to purchase currency flat cakes and print them in their own mints. Copper and copper alloys are favored by the coinage industry for their beautiful color and good machinability. However, the discoloration of the flat cake has always plagued the mint industry, since the flat cake cannot be stored for a long time after the surface treatment is completed, which limits the international supply of the flat cake to a certain extent. [0003] The Shenyang Mint is the base for the production of copper alloy coins in my country, and undertakes the production ...

Claims

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Application Information

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IPC IPC(8): C23C22/07
Inventor 董江刘迪魏立营张吉刚孙立军刘禾
Owner CHINA BANKNOTE PRINTING & MINTING