Hybrid Coating Composition for Plastic Substrates
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Solution Overview
Problem
Current optical coatings for plastic substrates face challenges in achieving good adhesion, high scratch resistance, low thermal stress cracking, and resistance to alkalis and acids, as these properties often conflict with each other.
Innovation Solution
A coating composition comprising a silane derivative of specific formulas, a colloidal inorganic oxide, an epoxy compound with three epoxy groups, and a catalyst system, including a Lewis acid and a thermolabile Lewis acid-base adduct, which provides excellent adhesion, high scratch resistance, and resistance to alkalis and acids while minimizing thermal stress cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a purely inorganic silicate network is used to achieve high hardness and scratch resistance, then scratch resistance is improved, but the coating exhibits high tendency to crack under thermal stress
Solution Approach 1:
The patent applies composite materials by combining inorganic silicate components with organic components (epoxy resin, silane coupling agents) to create an organo-inorganic hybrid coating system. This composite structure integrates the high hardness of inorganic materials with the flexibility and thermal stress resistance of organic materials, resolving the contradiction between scratch resistance and thermal cracking tendency
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating specific ratios of tetraalkoxysilane, organoalkoxysilane, epoxy compound, and silane coupling agent. By adjusting these compositional parameters, the coating achieves optimal balance between hardness (for scratch resistance) and flexibility (for thermal stress resistance), resolving the technical contradiction
2Reliability
If organoalkoxysilanes are added to increase flexibility and reduce thermal stress cracking, then thermal stress resistance is improved, but hardness and scratch resistance decrease
Solution Approach 1:
The patent uses composite materials strategy by formulating a hybrid system where organoalkoxysilanes provide flexibility and thermal stress resistance, while inorganic silicate components and epoxy compounds maintain hardness. The synergistic combination resolves the contradiction between flexibility and hardness
Solution Approach 2:
The patent applies local quality by using silane coupling agents that create different functional regions within the coating - inorganic cross-linked regions for hardness and organic flexible regions for thermal stress resistance. This localized functional distribution resolves the contradiction between hardness and flexibility
3Strength
If the coating composition is optimized for high scratch resistance, then adhesion to different plastic substrates may be compromised due to varying surface properties
Solution Approach 1:
The patent applies universality by incorporating silane coupling agents that can bond to both inorganic substrates (through siloxane bonds) and organic substrates (through organofunctional groups). This multi-functional bonding capability enables the coating to adhere to different plastic substrates while maintaining high scratch resistance
Solution Approach 2:
The patent changes the chemical composition by including specific silane coupling agents with different organofunctional groups that can match various substrate surface properties. This compositional adjustment enables universal adhesion across different plastic substrates while preserving scratch resistance
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 composition achieves very good adhesion to various plastic substrates, high scratch resistance, and high resistance to alkalis with a low tendency to crack under thermal stress, as demonstrated by improved Bayer ratio, cross-cut test results, and nano-indentation hardness.
Implementation Method 1
This process utilizes, for example, tetraalkoxysilanes, which hydrolyze under suitable conditions and subsequently form a three-dimensionally cross-linked silicate structure through condensation of the silanol groups produced by the hydrolysis
Implementation Method 2
subsequently form a three-dimensionally cross-linked silicate structure through condensation of the silanol groups produced by the hydrolysis
Implementation Method 3
a catalyst system, including a Lewis acid and a thermolabile Lewis acid-base adduct
Data Source
AI summary
Composition comprises: a silane derivative (I) and/or its hydrolysis and/or condensate product; a silane derivative (II); a colloidal inorganic oxide, fluoride or oxyfluoride; an epoxide compound containing at least two epoxide group; and a catalyst system comprising a Lewis acid and a thermolatent Lewis-acid base adduct. Composition comprises: a silane derivative of formula (Si(OR1)(OR2)(OR3)(OR4)) (I) and/or its hydrolysis and/or condensate product; a silane derivative of formula ((R6R7) 3 - nSi(OR5) n) (II); a colloidal inorganic oxide, fluoride or oxyfluoride; an epoxide compound containing at least two epoxide group; and a catalyst system comprising a Lewis acid and a thermolatent Lewis-acid base adduct. R1-R5 : alkyl, acyl, alkylacyl, cycloalkyl, aryl or alkylaryl (all optionally substituted); R6 : organic group comprising an epoxide unit, preferably a silane derivative of formula (III); R7 : optionally substituted alkyl, cycloalkyl, aryl or alkylaryl; n : 2 or 3; R12 : H or 1-4C-alkyl; and R13 : 1-10C-alkyl. Independent claims are included for: (1) coating a substrate comprising providing the composition, applying the composition on the substrate and treating the substrate at 75-150[deg] C for hardening the coating; and (2) an article comprising a substrate and the coating on the surface of the substrate, which is obtained by the above process. [Image].