Liquid coating composition and coating method for forming hard-coat film on plastics

Abstract

Abstract The invention provides a liquid coating composition for forming a transparent and hard coating film on a plastic member such as a polycarbonate or polymethyl methacrylate plate. The liquid composition comprises 100 parts by weight of an organotrialkoxysilane R 1 Si(OR 2 ) 3 , where R 1 is a C 1 - or C 2 -alkyl group and R 2 is a C 1 -, C 2 - or C 3 -alkyl group, 5-20 parts by weight of an organotrialkoxysilane R 3 Si(OR 2 ) 3 , where R 3 is an organic group containing epoxy group, 50-200 parts by weight of an aqueous colloidal silica sol in which the content of SiO 2 is 10-40 wt %, and 0.5-3 parts by weight of a dicarboxylic acid (CF 2 ) n (COOH) 2 , where n is an integer from 1 to 5, preferably hexafluoroglutaric acid. On a surface of a plastic member a coating film of this composition is partially cured at 70°-150° C. to turn into a fairly hard but still pliable film. Then the plastic member can be shaped so as to bend the coated surface without suffering from cracking or peeling of the partially cured film. After that the film is treated with an aqueous alkali solution and then further cured at 80°-150° C.

Inventors

• 👤 Toshikazu Nagashima
• 👤 Haruki Kuramashi
• 👤 Yoshihiro Nishida
• 👤 Masahiro Hirukawa

Bibliographic Details