Tin Oxide Antistatic Coating for Optical Lenses
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Solution Overview
Problem
Optical articles, particularly ophthalmic lenses, face issues with cosmetic defects and reduced transparency due to antistatic coatings based on materials like ITO, which absorb visible light and become visible over time, compromising their antistatic and reflective properties.
Innovation Solution
Using an antistatic layer comprising at least 30% tin oxide (SnO2) in the conductive layer, deposited under ionic assistance, on substrates with a water uptake rate greater than 0.6% by mass, to prevent cosmetic defects and maintain transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an antistatic layer based on ITO is used, then antistatic properties are achieved, but cosmetic defects and reduced transparency occur over time
Solution Approach 1:
The patent changes the material composition parameter of the antistatic layer from ITO to a tin oxide-based material with at least 30% SnO2 content. This parameter change resolves the contradiction by providing antistatic properties without the cosmetic defects and transparency issues associated with ITO, as tin oxide maintains optical clarity while delivering the required electrical conductivity for antistatic functionality.
Solution Approach 2:
The patent replaces the expensive ITO material with a more cost-effective tin oxide-based composition. This substitution not only reduces manufacturing costs but also eliminates the long-term reliability issues and transparency degradation associated with ITO, providing a sustainable alternative that maintains performance over time.
2Strength
If a hard anti-abrasion coating is deposited on the lens surface, then scratch resistance is improved, but impact resistance decreases due to stiffening
Solution Approach 1:
The patent employs a composite coating structure where a hard anti-abrasion layer is combined with a tin oxide-based antistatic layer. This composite approach allows the hard layer to provide scratch resistance while the tin oxide layer, being more flexible and conductive, compensates for impact resistance by absorbing stress and preventing the overall system from becoming too brittle, thus resolving the contradiction between hardness and impact tolerance.
3Reliability
If the antistatic layer contains high indium oxide content, then conductivity is improved, but visible light absorption increases
Solution Approach 1:
The patent fundamentally changes the material parameter from indium oxide-based (ITO) to tin oxide-based composition with at least 30% SnO2 content. This parameter change resolves the contradiction because tin oxide provides sufficient electrical conductivity for antistatic properties while maintaining high visible light transmission, eliminating the yellowing and light absorption issues inherent in high indium oxide content materials.
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 provides optical articles with stable antistatic and reflective properties over time, preventing cosmetic defects and ensuring high transparency, while maintaining excellent adhesion and antistatic performance.
Implementation Method 1
a material with high conductivity allows charges to be dissipated more quickly
Implementation Method 2
prevent the formation of parasitic reflections that are annoying for the wearer of the lens and those they talk to
Implementation Method 3
the deposition of said electrically conductive layer having been produced under ionic assistance
Data Source
AI summary
The invention relates to an optical article with antistatic and antireflective or reflective properties, comprising a substrate having at least one main surface coated with an antireflective or reflective coating, said coating comprising at least one electrically conductive layer comprising at least 30% by mass of tin oxide (SnO2) relative to the total mass of the electrically conductive layer, the deposition of said electrically conductive layer having been carried out under ionic assistance, and said substrate having a water reabsorption rate greater than or equal to 0.6% by mass relative to the total mass of said substrate, the water reabsorption rate being measured after prior drying of said substrate and then storage of this substrate for 800 hours in an enclosure at 50°C under a relative humidity of 100% and at atmospheric pressure.