Transparent Antistatic Coating via Silane Sol-Gel Network
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Solution Overview
Problem
Existing transparent antistatic coatings for optical articles, such as eyeglass lenses, face challenges in maintaining high transparency and mechanical properties like abrasion resistance while providing effective antistatic performance, as additives used to enhance conductivity often compromise these qualities.
Innovation Solution
A curable composition comprising a silicon-containing binder, an alkali salt, and a Brønsted acid is used, which forms a synergistic network that enhances antistatic properties without degrading transparency or mechanical strength, achieved through the specific formulation of silane derivatives and the controlled use of alkali salts and Brønsted acids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive polymers or specific additives are added to aqueous based hard coating compositions to improve antistatic properties, then charge dissipation capability is enhanced, but abrasion resistance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters by introducing a specific silane compound with epoxide groups and alkoxysilane groups that reacts with the aqueous binder to form a crosslinked network. This network structure provides both antistatic conductivity and mechanical strength, resolving the contradiction between improving antistatic properties and maintaining abrasion resistance
Solution Approach 2:
The invention creates a composite coating system combining the aqueous binder, silane compound, and optional conductive additives. The silane-modified binder forms a crosslinked matrix that provides structural integrity and abrasion resistance, while the conductive additives embedded within this matrix provide antistatic properties without compromising the mechanical strength of the coating network
2Reliability
If transparent antistatic coatings are applied to optical articles to reduce electrostatic charge, then dust attraction is reduced, but transparency may be compromised
Solution Approach 1:
The invention uses a clear aqueous binder and transparent silane compounds that form a crosslinked network with optical properties matching the substrate. The coating maintains high transparency by using materials with refractive indices compatible with optical articles while incorporating conductive components at concentrations that provide antistatic properties without compromising light transmission
3Illumination intensity
If vapor deposited metal or metal-oxide coatings are used to achieve transparent antistatic properties, then transparency is improved, but mechanical durability under thermal stress and bending deteriorates
Solution Approach 1:
The invention employs a sol-gel process where the silane compound undergoes hydrolysis and condensation reactions to transition from a molecular state to a crosslinked gel network. This phase transition creates a robust three-dimensional network structure that provides mechanical durability and flexibility, unlike rigid vapor-deposited metal coatings that are prone to cracking under thermal stress and bending
Solution Approach 2:
The invention creates a composite coating system where the silane-modified binder forms a flexible, adherent matrix that combines the advantages of organic polymers (flexibility, adhesion) with inorganic crosslinked networks (hardness, thermal stability). This composite structure maintains transparency while providing superior mechanical durability compared to vapor-deposited coatings
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 results in optical articles with high transmittance, low haze, excellent antistatic properties, and maintained abrasion resistance, with charge decay times significantly reduced, demonstrating a balance of performance criteria.
Implementation Method 1
The binder is a silicon-containing or silan compound that yields a hard coating composition, generally named 'Sol-Gel' coating composition
Implementation Method 2
These silicon-containing coatings or 'Sol-Gel' coatings rely on reaction of hydrolysis and condensation of various silane derivatives
Implementation Method 3
A curable composition comprising a silicon-containing binder, an alkali salt, and a Brønsted acid is used, which forms a synergistic network that enhances antistatic properties
Data Source
AI summary
The present invention relates to a curable composition providing upon curing a transparent antistatic coating comprising a silica organosol, a salt comprising an alkali cation and a Bronsted acid. The invention further relates to optical articles comprising a substrate at least partially coated with a transparent antistatic coating formed by depositing onto substrate and curing the above curable composition. The obtained optical articles exhibit enhanced antistatic properties, high optical transparency, low haze and good mechanical properties, in particular a good abrasion resistance.