Radiation Curable Polyene Polythiol Clear Topcoat for Ambient Curing
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Solution Overview
Problem
Automotive refinish coatings lack an effective ambient temperature curing mechanism, as conventional polyisocyanates are not environmentally friendly and require heating ovens, which are not feasible in all settings.
Innovation Solution
A multilayer coating process using polyurethane (meth)acrylates and polythiols that are curable by radiation, specifically through exposure to ultraviolet light or electron beams, allowing for curing at room temperature without the need for heating ovens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyisocyanates are used as curing agents for ambient temperature curing, then curing is achieved, but environmental friendliness deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the curing system by replacing polyisocyanates with radiation-curable polyene/polythiol compositions. This substitution maintains curing effectiveness while eliminating the environmental harm associated with polyisocyanates, as the new system cures through radiation-induced thiol-ene click chemistry rather than isocyanate-based reactions.
Solution Approach 2:
The patent substitutes the chemical curing mechanism (polyisocyanate crosslinking) with a radiation-based curing mechanism (UV or electron beam irradiation). This replacement allows curing to proceed at ambient temperature without the harmful byproducts of polyisocyanate reactions, thereby improving environmental friendliness while maintaining curing reliability.
2Reliability
If heating ovens are used for curing, then curing effectiveness is improved, but device complexity and space requirements worsen
Solution Approach 1:
The patent replaces the thermal curing system (heating ovens) with a radiation curing system (UV lamps or electron beam apparatus). This substitution eliminates the need for complex heating infrastructure and large oven spaces, as radiation curing occurs rapidly at ambient temperature through direct energy absorption by the photoinitiators or polymer chains, thereby reducing device complexity while maintaining curing effectiveness.
Solution Approach 2:
The patent changes the curing temperature parameter from elevated temperatures (150-200°C in ovens) to ambient temperature by introducing radiation as the energy source. This parameter change allows curing to occur without heating ovens, thereby reducing device complexity and space requirements while maintaining effective curing through radiation-induced crosslinking.
3Ease of operation
If ambient temperature curing is implemented, then ease of operation is improved, but curing speed deteriorates
Solution Approach 1:
The patent substitutes slow chemical curing at ambient temperature with rapid radiation-induced curing. The UV or electron beam radiation provides concentrated energy that triggers fast polymerization and crosslinking reactions, achieving high curing speeds while maintaining ambient temperature operation, thereby improving both ease of operation and productivity simultaneously.
Solution Approach 2:
The patent employs periodic or pulsed radiation delivery to achieve rapid curing. By delivering radiation in controlled pulses or continuous streams, the system maintains ambient temperature while achieving fast curing rates through cumulative energy absorption, thereby resolving the contradiction between ease of operation and curing speed.
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 process enables rapid and environmentally friendly curing of clear topcoats on automotive surfaces, achieving high adhesion and hardness while reducing the reliance on polyisocyanates, thus addressing the need for ambient temperature curing in automotive refinish applications.
Implementation Method 1
A clear topcoat composition comprising a polyene/thiol composition... The topcoat is cured by exposure to radiation
Implementation Method 2
curable by radiation, specifically through exposure to ultraviolet light or electron beams
Data Source
AI summary
A process for forming a color-clear multilayer coating on a substrate is disclosed. The clear topcoat comprises a polyene and a polythiol that is radiation curable.