Strong and elastic polyurethane, polyurea, polyarylates and electron

Abstract

An essentially isocyanate-free polyurethane, polyurea, polyethylenic oligomer is disclosed which is unusually strong and elastic and which possesses improved solvent solubility. This oligomer is the reaction product of: (1) organic diisocyanate; (2) a stoichiometric deficiency of difunctional materials reactive therewith and consisting essentially of: (A) diol component selected from polycarbonate diol and polyoxyalkylene glycol, this diol component having a molecular weight of from 200 to 2000; (B) dihydric bisphenol-based alkylene oxide adduct containing from 2-6 alkylene groups per molecule; and (C) a diprimary diamine component selected from alkylene diamine and polyoxyalkylene diamine, this diamine component having a molecular weight of from about 60 to 800. Components (A) and (B) are present in a mole ratio of, from 1:1.5 to 1:5 and component (C) is present to supply from 5 to 30 equivalent percent of the total equivalents of component (2). The polyurethane polyurea so-constituted is capped with monohydric ethylenic compound, such as 2-hydroxyethyl acrylate, to provide a molecular weight in the range of about 5,000 to about 30,000. This polyethylenic oligomer is cured by radiation exposure, as from an electron beam, and a polyethylenic cross-linking agent may be used to enhance the cure. The coating compositions are preferably pigmented and diluted to a resin solids content of about 5% to 15%, at which dilution they exhibit superior resistance to precipitation.