Dual-Cure Coating Formulations for Adhesion and Stress Control
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Solution Overview
Problem
Existing coating technologies face challenges with adhesion, mechanical properties, and residual stress due to off-stoichiometric formulations, which result in non-optimized polymeric networks with less crosslinking and unreacted monomers, leading to poor durability and environmental concerns.
Innovation Solution
A method involving the application of compounds with specific ratios of thiol groups, carbon-carbon double bonds, and epoxide groups, followed by dual curing steps to form covalent bonds, ensuring high crosslink densities and minimal residual stress, resulting in durable and environmentally friendly coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If off-stoichiometric formulations are used to simplify manufacturing, then ease of manufacture is improved, but mechanical properties and adhesion deteriorate due to non-optimized polymeric networks with less crosslinking
Solution Approach 1:
The invention changes the stoichiometric ratio parameter of functional groups (thiol:ene:epoxide) from conventional off-stoichiometric formulations to a specific off-stoichiometric range (0.8:1:0.2 to 1.2:1:0.2). This parameter optimization ensures maximum crosslinking density while maintaining ease of manufacture, resolving the contradiction between formulation simplicity and mechanical properties.
2Loss of substance
If off-stoichiometric formulations are used to reduce material costs, then loss of substance is reduced, but reliability deteriorates due to unreacted monomers leaching into the environment
Solution Approach 1:
The invention optimizes the stoichiometric ratio of functional groups to achieve near-complete conversion of reactive groups. By carefully balancing the thiol:ene:epoxide ratio (0.8:1:0.2 to 1.2:1:0.2), the formulation minimizes unreacted monomers while maintaining material efficiency, thus resolving the contradiction between reducing substance loss and ensuring environmental reliability.
3Productivity
If conventional curing processes are used to reduce manufacturing time, then productivity is improved, but adhesion deteriorates due to insufficient reactivity retention
Solution Approach 1:
The invention segments the curing process into two distinct stages: first a rapid initial cure that achieves quick productivity, then a secondary curing step that ensures complete reaction and maximum adhesion. This segmentation allows the system to benefit from both fast initial setting and complete final curing, resolving the contradiction between productivity and adhesion strength.
Solution Approach 2:
The invention performs preliminary action by incorporating a latent catalyst system that remains dormant during initial curing but activates later to complete the reaction. This preliminary setup enables fast initial productivity while ensuring complete adhesion development in the secondary curing stage, resolving the contradiction between curing speed and adhesion quality.
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 achieves excellent adhesion strength, mechanical properties, and reduced residual stress, with high conversion of functional groups and tunable glass transition temperature, extending the usage range and compatibility with various substrates.
Implementation Method 1
a method involving the application of compounds with specific ratios of thiol groups, carbon-carbon double bonds, and epoxide groups, followed by dual curing steps to form covalent bonds
Implementation Method 2
followed by dual curing steps to form covalent bonds, ensuring high crosslink densities and minimal residual stress
Data Source
AI summary
An object with a coating comprising: a) covalent bonds formed by reaction of a thiol group and a carbon-carbon double bond, b) covalent bonds formed by reaction of a thiol group and epoxide group, c) covalent bonds formed by a reaction of a carbon-carbon double bond and an epoxide group, said coating comprising a first primer coating and a second coating, said coating comprising covalent bonds between said first and second coatings, said first primer coating comprising covalent cross links between compounds, in the first coating the fraction (r3=ta/tc) of unreacted thiol groups (ta) to thiol groups which have reacted to form a covalent bond (tc) does not exceed 0.11, wherein the half height peak width of tan delta does not exceed 30° C. Advantages of the dual cure composition is that excellent strength is obtained and that the second curing is slow compared to the first initial curing.