Background
The ophthalmic lenses (spectacle lenses) consist of some base material (substrate) like CR 39, Polycarbonate, Trivex and a surface treatment is given to them to increase their hardness. Currently, there are 2 processes of applying this coating, i.e. Dip coating and Spin coating. The current scratch resistant (Hard) coating on plastic and polycarbonate lenses available in the industry has a scratch resistant property of 4H as per Pencil hardness test. Titan Lens lab has tried improving the hardness of the coating in the past but was able to achieve greater hardness up to 6H, but as soon as we apply Antireflection coating on this surface, the hardness again drops to 4H. Due to this, the lenses get scratched over a shorter period of time and causes scattering of light and blurring of vision. The customer is left with no other option but to replace the lenses within a span of 6 to 8 months. The desire is to have a lens with harder scratch resistant coating which would withstand the normal wear & tear and allow the customers to wear it for a much longer period
Solution Requirements
Must have: Scratch resistant property of 6H even after the antireflection coating is applied without compromising on the optical & physical properties of the lens.
Nice to have: Scratch resistant property of 7H even after the antireflection coating is applied without compromising on the optical & physical properties of the lens Expected deliverables
A process that will ensure a harder scratch resistant coating of 6H which would withstand the normal wear & tear and allow the customers to wear it for a much longer