Antistatic Coating Composition for Optical Articles
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Solution Overview
Problem
Current antistatic coatings for optical articles, particularly ophthalmic lenses, face challenges in achieving a balance between antistatic properties, abrasion resistance, and low haze, with existing solutions often compromising on one or more of these aspects, especially when multiple layers are applied.
Innovation Solution
A curable coating composition comprising a conductive polymer, colloidal particles of non-conductive oxide, and an epoxysilane binder, which provides a transparent, antistatic, and abrasion-resistant coating with low haze, even when stacked with other functional coatings, and can be formulated to include nanostructured layers for enhanced hydrophobic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ITO layers are used to achieve high optical transparency in anti-static coatings, then transmittance is improved (over 90% or even 95%), but the coating becomes fragile and is readily damaged during bending or other stress inducing conditions
Solution Approach 1:
The patent uses composite materials by combining conductive polymer particles (Baytron P®) with silane-based binder resins to create a coating that integrates antistatic functionality with inherent mechanical strength and adhesion, eliminating the fragility issue of pure ITO coatings while maintaining high optical transmittance
Solution Approach 2:
The patent changes the material parameters from inorganic ITO (metal oxide) to organic conductive polymers (polythiophene-based), which fundamentally alters the mechanical properties while maintaining electrical conductivity, enabling flexibility and stress resistance
2Reliability
If Baytron P® antistatic hard coatings are formulated to achieve excellent adhesion and abrasion resistance, then coating durability is improved, but haze increases and transparency decreases
Solution Approach 1:
The patent optimizes the particle size parameters of Baytron P® conductive polymer to sub-visual ranges (typically below 50 nm), which allows the coating to maintain excellent adhesion and abrasion resistance while becoming optically invisible, thereby achieving both durability and high transparency with low haze
Solution Approach 2:
The patent creates local quality differences by using extremely fine conductive polymer particles that provide mechanical reinforcement and adhesion at the molecular level without creating visible scattering centers, allowing different regions of the coating to fulfill different functions (adhesion vs. transparency)
3Adaptability or versatility
If multiple functional coatings are stacked on optical articles, then additional properties (such as hydrophobicity, anti-reflective properties) are improved, but the complexity of the coating system increases and may compromise antistatic performance
Solution Approach 1:
The patent creates a universal base coating that simultaneously provides adhesion, mechanical strength, and antistatic properties, which can serve as a foundation for additional functional coatings (anti-reflective, hydrophobic) without compromising its own performance, thereby simplifying the overall system architecture
Solution Approach 2:
The patent segments the coating system into distinct functional layers, with the conductive polymer-silane coating serving as a dedicated adhesion and antistatic base layer, allowing other functional coatings to be added independently without interfering with the antistatic mechanism
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 coating composition effectively imparts antistatic and abrasion-resistant properties to optical articles while maintaining high transparency and low haze, ensuring effective charge dissipation and durability, even under multiple layer applications.
Implementation Method 1
a) at least one conductive polymer... capable of quickly dissipating accumulated electrostatic charges
Implementation Method 2
c) at least one binder comprising at least one epoxysilane having at least two hydrolysable groups directly linked to the Si atom of the epoxysilane
Implementation Method 3
b) colloidal particles of at least one non-conductive oxide... providing abrasion resistance
Implementation Method 4
curable coating composition... obtained by depositing and curing a curable coating
Data Source
AI summary
Curable composition providing, upon curing, an abrasion resistant, transparent, antistatic coating comprising: - a) at least one conductive polymer, - b) colloidal particles of at least one non-conductive oxide, - c) at least one binder comprising at least one epoxysilane having at least two hydrolysable groups directly linked to the Si atom of the epoxysilane, and/or its hydrolysis product, said at least one conductive polymer and said colloidal particles of at least one non- conductive oxide being substantially not agglomerated, the content of said conductive polymer in the dry extract of said curable composition ranging from 0.1 to 10% by weight, preferably from 0.2 to 10% by weight and the content of the dry extract of said at least one epoxysilane in the dry extract of said curable composition ranging from 20 to 80 %, preferably 25 to 60 % by weight based on the total weight of the dry extract.