AN IMPROVED PROCESS FOR OBTAINING A TRANSPARENT, PROTECTIVE COATING ON BI-ASPHERIC/PLANOCONVEX LENSES MADE OF OPTICAL GRADE PLASTICS FOR USE IN INDIRECT OPHTHALMOSCOPY

摘要

The present invention relates to an improved process for obtaining a transparent, scratch resistant protective coating on bi-aspheric and planoconvex lenses made of optical grade transparent plastics such as polycarbonate (PC) and polymethylmethacrylate (PMMA). The process comprises synthesis of the coating composition having an appropriate viscosity followed by coating deposition of the composition on bi-aspheric or planoconvex lenses made of PC or PMMA by angle dependent dip coating or spin coating respectively. This method is useful for simultaneous coating deposition on both surfaces of bi-aspheric lenses by angle dependant dip coating using withdrawal speeds from 0.5 mmls till 3 mmls, to yield transparent, protective coatings on bi-aspheric lenses made of PC or PMMA. The coated PC or PMMA lenses are thermally treated either at about 130°C for 1 hr or at 80°C for 6 hr preceded by a ultraviolet radiation exposure in case of the latter substrate.