Copper powder is referred to as gold powder. It is an alloy formed by a certain proportion of copper, zinc and a small amount of other metal elements. The flaky powder is obtained by smelting, atomizing powder, ball milling and grading. It is actually a sheet of copper-zinc alloy powder. It is widely used in metal powder materials for coatings and printing, and has good hiding ability and metallic luster. Its use configuration method is simple. After the gold powder is transferred into the varnish, it is a golden ink or gold paint with excellent golden luster. It is widely used in packaging printing, coating, textile and other industries, through plastic, paper, fabric printing, bronzing or finishing. It plays a decorative role in various utensils and environmental arrangements, increasing the aesthetic effect of products and packaging. However, at present, the use of copper gold powder in the aqueous system in China has the following problems: First, varnish has special requirements, otherwise it will easily produce oxidative darkening and greening; Second, the two-component packaging adopts the current distribution method and is used at the specified time. Finish. This is because the following factors exist in the aqueous system:
1. The aqueous system contains dissolved oxygen. Oxidation and copper ions are very easy to react. Some people use antioxidants in the system. This can only be temporary, because the package is completely sealed and no oxygen is combined with copper ions. Unrealistic, then even if you can completely remove oxygen during the processing of gold paint, when used, when it is evenly stirred, it will also contact with air oxygen, and the system will increase dissolved oxygen;
2. The resin in the aqueous system will have some active components such as sulfur ions and chloride ions after processing. These materials can easily react with copper ions to form copper oxides in a humid environment. Common ones are: black Copper oxide: CuO (black copper ore); red cuprous oxide: Cu2O (copper ore); indigo copper sulfide: CuS (antimony ore, square blue copper ore); black copper sulfide: CU2S (hui Copper ore); basic copper carbonate (three types): dark green CuCO3 Cu(OH)2 (malachite, stone green); blue 2CuCO3 Cu(OH)2 (blue copper ore, azurite); blue 2CuCO3 3Cu(OH)2; basic copper chloride (with two isomers): green to dark green Cu2(OH)3Cl (copperite); pale green Cu2(OH)3Cl (secondary Green copper ore); blue copper sulfate CuSO4 5H2O (cholesteric); green basic copper sulfate: CuSO4 3Cu(OH) 2 (copper sulfate copper); white copper chloride: CuCl (copper chloride) Mine); white tin oxide: SnO2 (cassiterite) and the like. These various types of copper rust will destroy the waterborne gold paint system.
This is why copper gold powder is easily oxidized, blackened, and blue in aqueous systems.