UV-Curable Hard Coating Composition for Ophthalmic Lenses
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Solution Overview
Problem
Current UV-curable ophthalmic substrate coatings lack the abrasion and scratch resistance provided by conventional thermally-cured coatings, and there is a need for UV-curable hard coatings that can be cured quickly with comparable abrasion resistance.
Innovation Solution
A UV-curable coating composition combining non-hydrolyzed epoxy(alkoxy)silanes with dispersions of inorganic nanoparticles and acrylate monomers, along with a photoinitiator, which can be cured by UV light without a hydrolysis step, resulting in a low viscosity coating with improved stability and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If UV-curable compositions are used to eliminate thermal curing, then curing time and energy requirements are reduced, but abrasion resistance is compromised
Solution Approach 1:
The patent uses composite materials by combining UV-curable acrylate monomers with inorganic nanoparticles (silica, alumina, titania) to create a coating that achieves both fast curing and high abrasion resistance. The inorganic particles reinforce the UV-cured polymer matrix, providing mechanical strength comparable to thermally-cured coatings while maintaining the speed advantage of UV curing.
Solution Approach 2:
The patent changes the chemical composition parameters by using non-hydrolyzed epoxy(alkoxy)silanes instead of traditional hydrolyzed silane precursors. This parameter change allows the coating to achieve crosslinking and curing at lower temperatures and faster rates while maintaining network integrity and abrasion resistance without requiring extended thermal exposure.
2Ease of manufacture
If solvent-free UV-curable coatings are used, then application simplicity and speed are improved, but abrasion resistance is reduced compared to solvent-based thermally-cured coatings
Solution Approach 1:
The patent compensates for the lack of solvent-based processing by incorporating high concentrations of inorganic nanoparticles into the solvent-free UV-curable formulation. These nanoparticles provide the abrasion resistance that would otherwise be achieved through solvent-based thermally-cured coatings, while the UV-curing process maintains the application simplicity and speed advantages of solvent-free systems.
Solution Approach 2:
The patent replaces the thermal curing mechanism (which requires heat treatment ovens and extended processing time) with a photopolymerization mechanism using UV light. This substitution eliminates the need for thermal processing infrastructure while achieving comparable or superior coating performance through the combined action of UV-cured polymer matrix and inorganic particle reinforcement.
3Stability of the object's composition
If non-hydrolyzed epoxy(alkoxy)silanes are used instead of hydrolyzed silanes, then coating stability and viscosity are improved, but the curing mechanism becomes more complex
Solution Approach 1:
The patent introduces photoinitiators as intermediary substances that mediate the curing process. These photoinitiators absorb UV light and generate reactive species that trigger the polymerization and crosslinking of the non-hydrolyzed epoxy(alkoxy)silanes. This intermediary mechanism simplifies the overall process by enabling curing at lower temperatures and avoiding the need for complex hydrolysis conditions, while maintaining coating stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting coatings exhibit abrasion resistance comparable to conventional thermally-cured sol-gel coatings, with the ability to be applied via various methods such as spin coating or inkjet coating, and demonstrate enhanced stability and constant viscosity.
Implementation Method 1
at least one free radical photoinitiator, cationic photoinitiator, or a combination thereof
Implementation Method 2
curing the photocurable composition coating with UV irradiation
Data Source
AI summary
The UV-curable coating compositions disclosed herein are provided for use as coatings for plastic (organic glass) substrates, and ophthalmic lenses, in particular. The compositions may be applied by a variety of means, including spin coating and inkjet coating. The coating compositions exhibit abrasion resistance comparable to conventional thermally-cured sol-gel coatings.