Polymer compositions based on butoxylated melamine-formaldehyde resin modified with urethane prepolymers with isocyanate end-groups

Butoxylated melamine-formaldehyde resins (BMF) and two grades of urethane oligomers with isocyanate end-groups (PUR-izo) based on toluilene diisocyanate and oligooxypropylenediol or oligooxyalkylenetriol have been obtained. Physicochemical properties of these products were determined (Tables 1, 2) and basing on the IR and H-1 NMR spectra their chemical structures were determined (Figs 1-6). Varnish coatings have been prepared from BMF and PUR-izo, differing with the type and the content (3-10 weight %) of the oligourethane modifiers. The effects of these two factors on the functional properties of coatings have been determined. It has been stated that the coatings showed very good adhesion to the substrate, high impact strength and their elasticity and hardness were much better than of unmodified BMF resin (Table 3). There was also found the cured BMF-PUR-izo compositions showed good thermal stability (Table 4) and excellent chemical resistance.