Development and Process of Extinction Aluminum Electrophoretic Paint

[China Aluminum Industry Network] Electrophoretic coating was introduced from foreign countries earlier and it has been developed in China for nearly 30 years. Extinction electrophoresis is less than 10 years. At present, China's extinction electrophoresis profile manufacturers are: South China, Asia, Guangzhou, Australia, the United States, Hao Mei, Jinqiao, YKK, Ropes Gold, Donghua, Zhejiang East, Furama, Cambridge, Jianmei, Huajia Day. The following is for everyone to introduce: 1. The change of application technology of extinction electrophoretic coating: Pigment method The addition of pigments to the bright aluminum electrophoretic paint makes the electrophoretic coating rougher, thereby achieving the purpose of extinction. Acid treatment After lacquer electrophoretic coating, soaking in the acid solution, the surface of the electrophoretic coating film becomes rough due to the effect of acid, and then baked to obtain a matt coating film. Wax treatment Adding a waxy substance such as polyethylene to the glossy paint, due to the insolubility of the coating resin and the wax, the phase separation during baking after electrophoretic coating, and the roughness increased to achieve the purpose of extinction Resin Method (Phase 1) The gel particles of the polymer are preliminarily made into parts of the paint. When the paint is baked after electrophoresis, the heat level is suppressed by this part of the gel particles, and the roughness increases, thereby forming an extinction coating film. Resin Method (Phase 2) Based on the resin method (phase 1), combined with the phase separation technique of the wax treatment method, the resin method (second phase) extinction technique was developed. 2. Coating process requirements: Suspension Horizontal hanging Electrophoresis configuration Ideal process: coloring → washing → hot water washing → pure water washing → draining → electrophoresis Equipment should have the conditions: Pure water tanks and hot water tanks can be recycled; Hot water tank can be heated to 70 ~ 80 °C, hot water tank set filter; Slots and accessories Polar ratio: 1/1~1/2; Pole pitch: 250mm or more Cathode hood: about 50mm away from the electrode Overflow port to auxiliary tank piping structure: It should be ensured that the foam generation during circulation is minimized Note: The overflow of the main tank surface should be uniform to prevent air bubble retention. The tank capacity setting: In order to ensure a short update cycle, the tank body should be reduced as much as possible. For example: When the monthly output is 1000 tons, the ED tank volume is 60-80m3 Pump flow 3 to 3.5 times/hr Cycle speed Usually: 20~30cm/min When powered on: 20~30cm/min Coating before electrophoresis Must be completely dry (the drain tank can be heated) Electrophoresis process Electrophoresis → RO1 Wash → RO2 Wash → Drain → Bake Production conditions Production Interval: >7 minutes Washing times Must be washed twice other RO2 water wash needs temperature control (at low temperature) Refinishing method Can be directly supplied from the barrel, or through the mixing tank; When direct supplements are added, they should be added to overflow areas or places where the subtank circulation is strong; Mixing ratio in the mixing tank: bath / supplementary paint = 10/1 to 2/1; Additional pump: diaphragm pump or gear pump. Solvent replenishment: Solvent can't be mixed with lacquer; add special pipeline or add directly to the main tank or vice tank where the circulation is strong. Ion exchange The anion and cation exchange can be carried out continuously or separately. Before ion exchange treatment, please confirm whether the Yin and Yang towers are regenerated and cleaned. Refined liquid speed (SV): Yin Tower: 20 ~ 25; Yang Tower: 50 ~ 70 Dry curing Baking temperature range: 170~220°C Standard baking conditions: 180°C×30min Hot water wash 75~80°C×4min Drain >1 minute Pure water wash 3 to 5 minutes Drain >1 minute Infiltration before electrophoresis >1 minute Electrophoretic voltage 150~200V Power on time 3 to 5 minutes Post-infiltration 0 to 1 minute RO1 3 to 5 minutes RO2 4 to 6 minutes Drain >20 minutes Pre-baking workpiece status Must be completely dry bake 180°C X 30 minutes