Patent ID: 7163995

Claim:
A polyisocyanate composition with a high mean functionality, obtained by polycondensation of diisocyanate or triisocyanate monomers, comprising: (a) from 0.5% to 30% by mass, relative to the total mass of the components a), b) and c), of compounds bearing a single uretidinedione functional group having a molecular mass of not more than twice the average molecular mass of the isocyanate monomers having the highest molecular mass; (b) from 0.5% to 45% by mass, relative to the total mass of the components a), b) and c), of compounds bearing a single isocyanurate functional group with a molecular mass of not more than three times the average molecular mass of said isocyanate monomers having the highest molecular mass; the molar ratio of (a)/(b) being between 0.02 and 2, (c) at least 40% by mass, relative to the total mass of the components a), b) and c), of a mixture of polyisocyanate compounds having a molecular mass at least equal to three times the average molecular mass of the isocyanate monomers having the smallest molecular mass and bearing at least two isocyanate functional groups, and said mixture comprising (i) compounds bearing at least two isocyanurate functional groups, excluding those comprising uretidinedione functions, (ii) compounds bearing at least two uretidinedione functional groups, excluding those comprising isocyanurate functions and for which the number of monomer units is less than 5, (iii) compounds bearing at least one isocyanurate functional group and at least one uretidinedione functional group, having a molecular mass greater than three times the highest molecular mass of the above isocyanate monomer compounds; said mixture having a ratio: carbonyl functional groups belonging to a uretidinedione ring/carbonyl functional groups belonging to an isocyanurate ring+carbonyl functional groups belonging to a uretidinedione ring, at least equal to 4%; d) from 0 to 25% by mass, relative to the mass of the components a), b), c), d) and e), of compounds bearing at least one isocyanate functional group that are different than a), b) and c); and e) from 0 to 10% by mass, relative to the mass of the components a), b), c), d) and e), of impurities; said polysocyanate composition having a functional of greater than 3.