Example 3: coating for metal strip

The polysilazane used are organopolysilazane and polysiloxane, with the average number and molecular weight of 150-150000. The coating can be used for aluminum, zinc and other metal strips. The coating has good acid resistance, alkali resistance, solvent resistance, acid rain resistance, bird contamination resistance and weather resistance. For example, immerse 0.5mm thick aluminum plate in 20% concentration of total hydrogen polysiloxane solution, then exit at 120 cm / min, then preheat to 250 ℃ in forced air drying furnace, and keep at this temperature for 60 s, after cooling, form a clear, transparent and crack free coating. The scratch resistance of the coating was tested first, i.e. the coating was wiped back 5 times with a force of 3N with grade 00 steel wool. The scratch resistance of the coating was very good. After 25 cycles of exposure test, there is no white rust on the coating, and its adhesion (DIN EN ISO 2409-2013) is grade 0.