The Waterborne Symposium 2025

Abstract
"When considering flexible coatings, polyurethane often comes to mind. Polyurethane's flexibility is derived from its unique structure, featuring a combination of hard and soft segments, as well as hydrogen bonding within the hard segment. While polyurethane possesses diverse chemical structures and finds applications in various coatings, 2K polyurethane commonly grapples with several limitations, including the handling of often toxic isocyanates, sensitivity to moisture, yielding soft coatings, moderate curing speed, and constraints on coating thickness. Additionally, 2K polyurethane often necessitates the use of solvents to reduce viscosity for ease of application, resulting in high volatile organic compounds (VOC) emissions.

Epoxy systems are not typically associated with flexibility, as they are primarily recognized for their excellent mechanical properties, chemical resistance, and adhesion to substrates. Epoxy coatings have found widespread use in applications aimed at protecting substrates, enhancing resistance to various chemicals, and extending the service life of materials and assets. Compared to 2K polyurethane, epoxy presents advantages in terms of ease of handling, lack of moisture sensitivity, and the ability to formulate low VOC and low emission solutions. Furthermore, epoxy can be rendered flexible by incorporating a substantial amount of long-chain not environmentally and not user-friendly phenolic plasticizers. The need for fast return to service is a driving force in the coatings industry, often leading to the use of accelerators that, while speeding up curing, can compromise flexibility.

This paper introduces a novel EHS friendly flexible epoxy technology designed to bridge the performance gaps in current flexible epoxy systems using sustainable bio-based raw material. It yields coatings with rapid curing capabilities while maintaining high flexibility, even at low temperatures. These coatings exhibit high hardness, excellent substrate adhesion, substantial tensile and tear strength, all while maintaining an environmentally and user-friendly product profile. Catering to the demand for rapid return to service with minimal emissions and extended working time. The paper will also delve into key performance attributes and provide comparisons with 2K polyurethane and conventional epoxy systems.
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Co-Authors: Franklin Leal, and Dan Weinmann

Abstract

Epoxy resins have been used for decades in applications demanding excellent adhesion and corrosion resistance, but historically have not been suitable for coatings where ultraviolet (UV) resistance is needed. A direct-to-metal coating, comprised of a novel modified cycloaliphatic epoxy resin combined with a lower yellowing amine curing agent, was designed to deliver superior performance in corrosion resistance and adhesion. Additionally, this epoxy resin system offers improved gloss retention and color stability compared to standard epoxy coatings. Both the resin and curing agent are optimized to minimize dry time while maximizing hardness development. The relationship between epoxy-amine stoichiometry and coating performance was evaluated to further improve the system. Comparative testing with a commercially available epoxy-polyamide DTM coating showed that the novel epoxy system performs well against the competitive material while significantly improving the UV resistance, as determined by gloss and color retention.
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Abstract

"2K coatings are being heralded as an innovative means to increase the move towards 100% solids materials and reduce the need for thermal curing, thus reducing the energy required for the coating process. While the benefits are indisputable, there are issues associated with these technologies that can make them difficult to process in the manufacturing environment. All of these must be dealt with as part of the application process and, if not properly handled, can result in production delays that reduce throughput, reduce quality, and increase costs. Obviously, this runs counter to the objectives of these advanced technologies.
In this presentation we will:
 define induction time and pot life and the relationship between them.
 discuss the implications these pose to the modern manufacturing process.
 identify novel methods to leverage these properties, turning them from adversaries to allies in the application process.
 identify opportunities to minimize waste, reduce rework, increase throughput, and improve the quality of the coating process."