Heat transfers

Claim 1

A heat transfer comprising a temporary support and a label carried on said support, said label comprising a layer of a polyurethane resin system including (a) a thermoplastic polyurethane elastomer which is the product of the reaction of (1) 1 mole of an essentially linear hydroxyl terminated polyester either of the formula: ##STR6## R is an alkylene radical of 2 to 8 carbon atoms and R 1 is an alkylene radical of 4 to 10 carbon atoms, or of the formula: ##STR7## wherein: R 11 is an alkylene radical of 4 to 8 carbon atoms, said linear polyester having an average molecular weight of 600 to 3000 and an acid number less than 10; (2) from 1.1 to 3.1 moles of diphenyl diisocyanate having an isocyanate group on each phenyl nucleus; and (3) from 0.1 to 2.1 moles of at least one free glycol of from 2 to 10 carbon atoms; the combined average hydroxyl number molecular weight of the polyester and the free glycol being 450 to 1200, and the molar amount of the polyester and glycol combined being essentially equivalent to the molar amount of the diisocyanate compound; (b) an acid or acid yielding catalyst; and (c) as a cross-linking agent a compound containing at least two N-alkoxymethyl groups; said layer of the polyurethane resin system being substantially noncross-linking at ambient temperatures with said polyurethane remaining uncured, and when the layer of the polyurethane resin system is placed in contact with an article to be marked and subjected to heat and pressure the polyurethane is rapidly cross-linked into an inert, insoluble, extensible and wear-resistant form to provide a substantially permanent marking on the article.