Production of polyurea spray elastomer for use in concrete repair and waterproofing, involves reacting a prepolymer derived largely from 2,4-diphenyl-methanedi-isocyanate with an amine component

摘要

A method for the production of polyurea spray elastomers from polyisocyanates and amines, in which the polyisocyanate component is a prepolymer derived from 2,4-diphenylmethanedi-isocyanate (2,4-MDI) or a mixture of 2,4-MDI and 4,4-MDI containing at least 50 wt% 2,4-MDI, optionally together with other MDI-based isocyanates. A method for the production of polyurea spray elastomers (I) by reacting (a) polyisocyanates with (b) amines, in which (a) comprises (ai) reaction products of compounds containing at least two NCO-reactive hydrogens with 2,4-MDI or a mixture of 2,4-MDI and 4,4-MDI containing at least 50 wt 2,4-MDI, optionally together with (aii) mixtures of MDI and polymethylene-polyphenylene-polyisocyanates and/or (aiii) isomers of MDI which may be modified with groups other than urethane, and (b) is a mixture of (bi) polyether-amine(s) and (bii) other prim. or sec. amine(s) as chain extender(s). An independent claim is also included for polyurea spray elastomers (I) obtained by this method.