Photocurable Coating Composition for Optical Articles
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Solution Overview
Problem
Current antireflective coatings for optical articles face challenges in achieving both mar resistance and low refractive index, with existing solutions either compromising on mechanical strength or requiring high-temperature curing that can deform substrates, and often failing to maintain low reflectance.
Innovation Solution
A photocurable coating composition comprising porous and/or hollow inorganic oxide fine particles, hydrolytic condensates of bissilane compounds, and a compound capable of generating acid upon light exposure, which cures at temperatures up to 90°C, providing both mar resistance and low refractive index without substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If hollow silica particles are mixed with fluorinated alkyl-containing silicone binder, then antireflection properties are achieved, but mar resistance deteriorates due to particle floating and weak binding
Solution Approach 1:
A silane-modified polyethylene glycol acts as an intermediary coupling agent between the hollow silica particles and the fluorinated silicone binder. The silane groups bond to the silica surface while the polyethylene glycol chain provides compatibility with the silicone binder, preventing particle floating and enhancing mar resistance without compromising antireflection properties
Solution Approach 2:
The invention creates a composite coating system integrating hollow silica particles, silane-modified polyethylene glycol, and fluorinated alkyl-containing silicone. This composite structure combines the low refractive index of hollow silica with the adhesive strength and flexibility of the silane-polyethylene glycol-binder system, achieving both antireflection and mar resistance
2Strength
If hollow inorganic oxide particles are integrated with hydrolyzable silane compounds, then mar resistance is improved, but curing temperature must exceed 100°C causing substrate deformation
Solution Approach 1:
The invention changes the curing parameter from high-temperature thermal curing (>100°C) to low-temperature photocuring. The silane-modified polyethylene glycol contains photopolymerizable groups that undergo crosslinking upon UV irradiation, enabling cure at temperatures below 100°C that prevent substrate deformation while maintaining mar resistance
Solution Approach 2:
The invention replaces the thermal curing mechanism with a photocuring mechanism. Instead of using heat to drive the crosslinking reaction of silane compounds, UV light initiates polymerization of the photopolymerizable groups in the silane-modified polyethylene glycol, achieving the same crosslinked network formation at lower temperatures
3Reliability
If perfluoroalkyl groups are used in silane compounds, then alkali resistance and water repellency are improved, but crosslink density decreases reducing mar resistance
Solution Approach 1:
The invention creates a composite system where perfluoroalkyl-containing silane compounds provide alkali resistance and water repellency, while silane-modified polyethylene glycol with photopolymerizable groups provides crosslinking for mar resistance. The two components work synergistically without compromising either property
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 solution achieves a uniform, high-hardness coating with improved mar resistance and antireflection properties, suitable for various optical applications without the need for high-temperature curing, maintaining low reflectance and preventing substrate deformation.
Implementation Method 1
a compound capable of generating an acid upon light exposure
Implementation Method 2
The antireflection principle requires that the antireflective film have a low refractive index
Implementation Method 3
hollow inorganic fine particles are devised for the purpose of taking air into the structure of a cured coating
Implementation Method 4
hydrolytic condensates of bissilane compounds
Data Source
AI summary
A photocurable coating composition is provided comprising (1) porous or hollow inorganic oxide fine particles, (2) a hydrolytic condensate of a bissilane compound or a cohydrolytic condensate of a bissilane compound and another hydrolyzable organosilicon compound, and (3) a photoacid generator. Due to the presence of voids in the resin, the cured coating has a low refractive index.