METHOD OF PREPARING DISPERSION OF CROSS LINKING AGENTS IN WATER Russian patent published in 2011 - IPC C07C267/00 C08G18/02 C08G18/70 C08G18/28 

FIELD: chemistry.

SUBSTANCE: method involves: (1) reacting a mixture of polyisocyanate and 5-30 wt % mono- or polyisocyanate with a hydrophobic group at 120-180°C in the presence of 0.5-5 wt % carbodiimide catalyst to form a polycarbodiimide containing isocyanate functional groups, with average number of carbodiimide functional groups equal to 1-10, in which the hydrophobic group is an alkyl containing 4-25 carbon atoms which, a fluorinated hydrocarbon, a silicon-containing hydrocarbon or an organosilicon polymer, (2) breaking and/or prolonging the chain from the polycarbodiimide containing isocyanate functional groups by adding a compound in amount of 0.1-1.0 equivalents with respect to content of isocyanate functional groups, where the said compound contains a hydrophilic group and one or more amine and/or hydroxyl functional group simultaneous or subsequent blocking of the remaining isocyanate functional group with a compound containing one or more amine and/or hydroxyl functional groups and, possibly, a hydrophobic group, where the hydrophobic group is an alkyl group containing 4-25 carbon atoms, a fluorinated hydrocarbon, a silicon-containing hydrocarbon or an organosilicon polymer, (3) dispersing the obtained compound in water, and (4) regulating pH of the formed dispersion to a value between 9 and 14 by adding to the obtained dispersion a hydroxide of an alkali metal or a buffer, where the buffer is effective at pH 9-14. The invention also relates to coating mixture containing polycarbodiimide dispersion prepared using the method described above, as well as a curable material obtained by applying said coating mixture onto a substrate.

EFFECT: meeting the requirement for low amount of hydrophilic material needed for dispersing polycarbodiimide, obtaining films or coatings which are less sensitive to water, more resistant to solvents and which have improved properties during attrition testing in wet state, and achieving high cross-link density of the polymer network.

21 cl, 38 ex, 5 tbl