Copper gold powder is easy to oxidize and turn black, green and blue when used in aqueous system. Let's take a look at copper and gold powder and analyze the reasons for its easy oxidation:
Copper-gold powder is referred to as gold powder for short. It is an alloy formed by a certain proportion of copper, zinc and a small amount of other metal elements. The flaky powder made by smelting, atomizing, ball milling, and classification is actually flaky copper-zinc alloy powder. It is widely used in metal powder materials for coating and printing, and has good hiding power and metallic luster. Its use and configuration method is simple. After the gold powder is mixed into the varnish, it becomes a golden ink or gold paint with excellent golden luster. It is widely used in packaging and printing, coating, textile and other industries, through plastic, paper, fabric printing, bronzing or finishing It plays a decorative role in various appliances and environmental arrangements, increasing the aesthetic effect of products and packaging.
However, the current domestic use of copper and gold powder in water-based systems requires attention to the following issues:
1. There are special requirements for varnish, otherwise it is easy to produce oxidation darkening and greening;
2. The two-component packaging adopts the method of ready-to-use and ready-to-use, and is used up within the prescribed time.
This is because the following factors exist in the aqueous system:
1. The water-based system contains dissolved oxygen. Oxidation and copper ions are very easy to react. Some people add antioxidants to the system, which can only be temporary, because it is necessary to ensure that the packaging barrel is completely sealed without the combination of oxygen and copper ions. Unrealistic, then even if you can completely remove oxygen in the process of processing gold paint, when it is used, when it is evenly stirred, it will also contact with empty oxygen, and the dissolved oxygen will increase in the system;
2. The resin in the aqueous system will have some active ingredients such as sulfur ions and chloride ions after the processing is completed. These substances easily react with copper ions to form copper oxides in a humid environment. The common ones are: black Copper oxide: CuO (copperite); red cuprous oxide: Cu2O (cuprite); indigo copper sulfide: CuS (indigo copper, sapphire); black cuprous sulfide: CU2S (glow Copper ore); basic copper carbonate (there are 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 (there are two isomers): green to dark green Cu2 (OH) 3Cl (Chlorite); light green Cu2 (OH) 3Cl (Vice Azurite); blue copper sulfate CuSO4 5H2O (chalcolith); green basic copper sulfate: CuSO4 3Cu (OH) 2 (aqueous copper sulfate); white cuprous chloride: CuCl (cuprous chloride) Mine); white tin oxide: SnO2 (tin stone), etc. These copper rusts with different compositions will destroy the waterborne gold paint system.
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