Water-borne epoxy systems

Adhesion is usually improved while flexibility is maintained when using the high molecular weight epoxy emulsion as an upgrader in water-borne thermoplastic systems. 

Waterborne coatings. These are based on two-component epoxy-polyamine/polyamidoamine or epoxy-acrylic latex hybrids. One limitation of the water-borne systems is their poor cure in high humidity conditions. They have made some penetration in industrial maintenance coatings and are expected to grow more significantly in the future. 

Auto, truck, buses, and recreational vehicles - The breakdown of adhesives and sealants for motor vehicles in the U.S. in 1989 was 25% epoxy, 23% PVC, 20% polymethane, 14% elastomers, 10% acrylic, 2% silicone, and 6% miscellaneous. One part systems (PVC plastisol, epo y, polyiuethane, silicone) represented 58% of the products used. Solvent-borne and water-borne products accoimted respectively for 18% and 11% of the market. Hot melts, two part (epoxy and methanes) and miscellaneous products represented 6%, 5% and 2% of the market. Consumption in motor vehicles can be further subdivided between structural adhesives and sealants. 

Anionic coatings systems for water-borne topcoats are emulsion polymers, miniemulsion polymers, polyurethane dispersions, different types of dispersions of acrylic resins in water and amino resins, water-borne polyesters, polyurethanes. Many of the polymers are hydroxyl containing and cured with various melamines and blocked isocyanates. The polymers are mainly stabilized in the water phase by neutralization of anionic groups with volatile amines (2-amino-2-methyl-l-propanol). Cross-linkers like aminoplast resins, alkoxy silanes, blocked epoxy resins, carbodi-imides can be used. 

Most of the important types of modem solvent-borne coatings — epoxies, alkyds, acrylics — are also available in waterborne formulations. In recent years, even urethane polymer technology has been adapted for use in waterborne coatings [1]. However, waterborne paints are not simply solvent-borne paints in which the organic solvent has been replaced with water the paint chemist must design an entirely new system from the ground up. In this chapter, we discuss how waterborne paints differ from their solvent-bome counterparts. 

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