The Study On New Phosphate Pickling Agent For Car Paint

The new phosphate pickling agent is studied through lowing temperature used, reducing the dosage of heavy metal nickel to decrease harm to environment, and reducing the quantity of phosphate dregs. This is important in practical production. However, it has not been widely used due to unstable quality of phosphate film at present. The additive is appended in phosphate pickling agent in order to improve liquor activity, naturally react and build good phosphate in lower temperature. The characteristics of low-temperature phosphate is studied and analysed.The reactivity of low-temperature phosphate pickling agent is improved throuh increasing zinc content, total acidity, accelerator concentration, fluorin content, and lowing free acidity and adding other additive. At the same time, the nickel is decreased in phosphate pickling agent to present environment. The manganese is added to ensure anti-erosion capability of phosphate film. The experimental result shows the new phosphate solution has been confected, which it is lower temperature, lower phosphate dregs, good anti-erosion capability.The capability of phosphate film has been tested. The film appearance is good, the film mass is 2~3g/m2, P ratio is 88%( required over 80%), its crystal is grainy, steel plate's crystal size is 3m, znic plate's is 7m, both are less than 10m. The quality of phosphate film is good.The quantity of phosphate dregs is 2.57g/m2, this is lower about 30% than ordinary phosphate. It is good that the steel, zinc and aluminium can be reacted with the phosphate solution.It's main requirment which the phosphate film quality scaled that there is good both phosphate film and electrophoresis deposition(ED) coat. The ED coat's adhesion is grade 0. Its resistance to impact is over 50kg.cm. Its Erichsen number is 6mm(required over 5mm). Its hardness is over 2H. Its single-side corrosion width of salt spray test is less than 2mm. Its second adhesion dipping into water is up to grade. These results have shown that both the phosphate film and the ED coat are good.It is very important to phosphate film quality that the phosphate film can match for composite coat, including ED coat, primer coat, base coat and clear coat. The test result shows that the coat's adhesion is grade 0, its hardness is over H, QMS value is over 50, water resisting test is grade 0, salt spray test is over 480hrs, acid spot resistance andstone resistance test are all up to grade, light exposure test is over 2000hrs.