Epoxy Resin for Powder Coating

Details:

Epoxy resins, under the name of ethoxyline resins, were patented in Europe by P. Schlack in 1939 and introduced in the United States in the late 1940s. These resins, which are produced by the condensation of bisphenol A and epichlorohydrin, contain terminal epoxy groups and may contain many hydroxyl pendant groups, depending on molecular weight.

Epoxy resins are not used alone for coatings, normally being crosslinked.

Epoxy resins, based upon bisphenol A (or F) and epichlorhydrin, cured at room temperature by aliphatic polyfunctional amines and polyamides are used in heavy duty coatings for ships, oil rigs, and storage tanks, as well as water pipes. The epoxy resin-containing component of the paint is mixed with the polyamine-containing component prior to application. This is a two pack system. They also form the basis of the two pack adhesive (Araldite) available from most hardware stores.

Epoxy resins also react at elevated temperatures with aromatic amines, cyclic anhydrides, aminoplasts, and phenolplasts. In these applications, epoxy resin is present with the cross-linking agent in the coating and no mixing prior to application is required. This is a one pack coating. Epoxy resins have been used with acrylic coating resins, as powder coatings, and as high solids coatings. Epoxy resins are used as intermediates in UV coatings. Electrodepostion automobile primers are based upon epoxy resins crosslinked with polyisocyanate. Epoxy resins are used as additive resins in some coatings to improve properties such as adhesion and resistance.

Cycloaliphatic epoxy resins are used in cationic UV curable coatings and inks.

Epoxy resins reacted with fatty acids derived from oils produce epoxy esters, which can be air drying or non-air drying. The latter find usage in machinery coatings and are normally crosslinked with an aminoplast.