BIURET GROUP-CONTAINING POLYISOCYANATES OR BLOCKED BIURET GROUP-CONTAINING POLYISOCYANATES Russian patent published in 2011 - IPC C08G18/78 C08G18/79 C08G18/80 C07C275/62 C09D175/04 

FIELD: chemistry.

SUBSTANCE: polyisocyanate contains biuret groups, has functionality on isocyanate groups of not less than 4 and not more than 10 and is obtained using a method which includes (A) reaction of a polyisocyanate adduct with a secondary monoamine of formula (R¹)(R²)NH, with the ratio of the isocyanate equivalent to the amine equivalent ranging from approximately 4:1 to approximately 14:1 to introduce biuret groups into said polyisocyanate, and (B) reaction of the polyisocyanate containing biuret groups with a blocking reagent. The polyisocyanate adduct (a) is obtained from 1,6-hexamethylenediisocyanate, (b) has average functionality on isocyanate groups of not less than 2.5 and not more than 8, and (c) contains isocyanurate groups. The blocking reagent is selected from a group comprising phenol, cresol, amides, oximes, hydrazones, pyrazoles and phenols which are substituted with long aliphatic chains.

EFFECT: obtaining blocked polyisocyanates which combine relatively low viscosity and low molecular weight with high functionality on isocyanate groups and high reactivity relative to binders used in coatings, as well as which are stable during storage with respect to increase in viscosity and are virtually colourless, which is especially important for systems which form transparent coatings.

9 cl, 6 ex, 5 tbl