METHOD OF PREPARING OPTICAL SURFACES OF METALLIC BLANKS FOR DEEP DRAWING Russian patent published in 1995 - IPC

FIELD: metal pressure forming. SUBSTANCE: method comprises steps of applying on an optical surface of a blank a film on a base of water solution of polyvinyl alcohol and drying that film. The above mentioned solution contains ethanol; polyhydric alcohol, selected from group, containing ethylene glycol, propylene glycol, glycerine; 1,2,3= benzotriazole or its methyl= carboxyl= derivatives and synthanol with subsequent ratio of components (%); polyvinyl alcohol (9,9-15,1); ethanol (1,9-3.1); polyhydric alcohol, selected from the group, containing ethylene glycol, propylene glycol, glycerine, (1,9-12,1); 1,2,3= benzotriazole or its methyl= or carboxyl=derivatives-(0.5-2.0); synthanol(0.0-1.1); water- the balance. Drying process is being performed at temperature no more, than 30 C. EFFECT: enhanced quality of optical surface of the product, enlarged functional possibilities of using such coating. 1 cl