Moisture Curable Coating Composition for Flexible Substrates
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Solution Overview
Problem
Low temperature, moisture-curable coating compositions for flexible substrates face challenges in achieving flexibility and crack resistance while maintaining hardness and aesthetic appeal, as existing compositions often result in brittle films prone to chipping and thermal cracking.
Innovation Solution
The development of coating compositions incorporating a hydrolyzable functional group containing compound, an ungelled secondary amine-containing Michael addition reaction product, and a cyclic diamine, which allows for flexible, crack-resistant coatings with increased hardness and high gloss, cured at low temperatures without significant solvent content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silane based materials are used to form hard, highly crosslinked films, then coating hardness is improved, but flexibility deteriorates causing chipping or thermal cracking
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system by using isocyanate-functional silicones instead of traditional silane crosslinkers. This parameter change allows the coating to achieve crosslinking (for hardness) while maintaining flexibility through different molecular mechanisms - the isocyanate groups form flexible urethane linkages rather than rigid siloxane bonds, resolving the contradiction between hardness and flexibility
Solution Approach 2:
The patent creates a composite coating system combining hydrolyzable functional group containing compounds (for moisture curability and base coating properties) with isocyanate-functional silicones (for crosslinking and flexibility). This composite approach integrates multiple material advantages: the hydrolyzable compounds provide moisture-cure capability while the isocyanate-functional silicone provides flexible crosslinking, achieving both hardness and flexibility simultaneously
2Temperature
If traditional moisture curable compositions are used, then low temperature curing is achieved, but coating flexibility is lost due to embrittlement
Solution Approach 1:
The patent changes the curing mechanism parameter from silane hydrolysis/condensation (which produces rigid crosslinks) to isocyanate addition polymerization (which produces flexible urethane linkages). This parameter change enables low-temperature curing to proceed while forming a flexible polymer network that resists embrittlement and cracking, simultaneously achieving low-temperature cure and flexibility
3Strength
If high crosslink density is achieved for hardness, then coating strength is improved, but crack resistance deteriorates on flexible substrates
Solution Approach 1:
The patent changes the crosslinking chemistry parameter from silane-based condensation (forming rigid Si-O-Si bonds with high brittleness) to isocyanate-based addition polymerization (forming flexible N-H...O hydrogen-bonded networks). This parameter change allows achieving high crosslink density for strength while the flexible nature of the isocyanate-derived network maintains crack resistance on flexible substrates
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 coatings that are resistant to cracking, maintain flexibility, and achieve high gloss, while being capable of curing at low temperatures, making them suitable for substrates that bend or flex, such as elastomeric parts and consumer electronics.
Implementation Method 1
Some coating compositions are based on the hydrolysis and condensation of silane based materials that form a crosslinked Si—O—Si matrix
Implementation Method 2
Some coating compositions are based on the hydrolysis and condensation of silane based materials that form a crosslinked Si—O—Si matrix
Implementation Method 3
coating compositions comprising: (a) a hydrolyzable functional group containing compound; and (b) a cyclic diamine
Data Source
AI summary
Disclosed are low temperature, moisture curable coating compositions, related coated substrates, and methods for coating a substrate. The coating compositions include an ungelled, secondary amine-containing Michael addition reaction product of reactants including a compound comprising more than one site of ethylenic unsaturation, and an aminofunctional silane.