Curable epoxy-based coatings on substrates using a polythiol

A multilayer coating system with an epoxy-based primer layer and optional acrylic topcoat layer, using a specific polythiol and catalyst combination, addresses performance improvements in curable formulations, ensuring high adhesion and resistance to environmental factors.

WO2026125644A1 Publication Date: 2026-06-18ARKEMA FRANCE SA
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
ARKEMA FRANCE SA
Filing Date
2025-12-11
Publication Date
2026-06-18

AI Technical Summary

⚠Technical Problem

There is a need to improve curable formulations, particularly in thermosetting and epoxy-containing resins, by enhancing the performance characteristics of curing agents and catalysts in multilayer coating systems, especially when combined with substrates and topcoat layers.

⚗Method used

A multilayer coating system comprising a substrate, an epoxy-based primer layer, and an optional pigmented acrylic topcoat layer, where the primer layer is formed by curing a composition of an epoxy-containing compound, a substantially ester-free curing agent comprising a polythiol with specific sulfhydryl moieties and optionally a dithiol, and a curing enhancement catalyst, with a controlled molar ratio of epoxy to sulfhydryl moieties.

🎯Benefits of technology

The system achieves high adhesion stability, hardness, and resistance to humidity-induced color changes, with the primer layer exhibiting at least 90% cross-hatch adhesion stability and the topcoat layer maintaining adhesion under various conditions, including humidity accelerated weathering.

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Abstract

The present disclosure describes a multilayer coating comprising (I) a substrate, (II) an epoxy-based primer layer, and (III) an optionally but preferably pigmented acrylic topcoat layer, wherein the epoxy-based primer layer (II) is made by curing a curable composition comprising: (a) an epoxy-containing compound that is at least partially aromatic and is at least 90% difunctional, based on the total weight of all epoxy-containing compounds; (b) a substantially ester-free curing agent comprising a polythiol having at least three sulfhydryl moieties and comprising a cyclic isocyanurate ring structure containing 3 nitrogen atoms and 3 carbon atoms, with at least 2 of the three ring nitrogens having a pendant group containing from 2 to 8 carbon atoms and a sulfhydryl moiety; and (c) a curing enhancement catalyst. Methods of making the multilayer coatings are described herein, as well as desirable characteristics of the layers and / or the multilayer coating.
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