PURPOSE: To make easy the regeneration of material of a product having silicate coating film, by detecting a substandard product having silicate coating film by that time the product attains a prescribed temp., then by treating the product with acid or alkali.
CONSTITUTION: Substandard product is checked until it attains 150°C then it is treated with acid or alkali. As the acid for removing the coating film is used HCl, H2SO4, H3PO4, HNO3 independently or in mixture. Acid concn. is set at 3W50wt% and the treating temp. at 30W80°C. Aqueous HNO3 soln. is preferably used for the material made of metal, and is very preferable for the material made of Al. As the aqueous alkali soln., NaOH, KOH, or Ca(OH)2 is used independently or in mixture. The concn. and the temp. are respectively 5W30% and 30W80°C. Substandard product is immersed in the aqueous soln., or the soln. is sprayed to the product.
YAMAKAWA SEISHIROU
YAMADA NORIYUKI
