Biuretized isocyanates and blocked biuretized isocyanates
The present invention is directed to a biuret group-containing polyisocyanate composition having an isocyanate functionality of at least 4 prepared by a process comprising reacting a polyisocyanate adduct which a) is prepared from an aliphatic and/or cycloaliphatic diisocyanate; b) has an average isocyanate functionality of at least 2.5, and c) contains isocyanurate groups, with a secondary monoamine at an isocyanate to amine equivalent ratio of from about 4:1 to about 14:1 to incorporate biuret groups into said polyisocyanate. The invention is also directed to a blocked biuret group-containing polyisocyanate composition which is prepared by reacting the biuret-containing polyisocyanate with a blocking agent.
1 . A biuret group-containing polyisocyanate composition having an isocyanate functionality of at least 4 prepared by a process comprising reacting a polyisocyanate adduct which
a) is prepared from 1,6-hexamethylene diisocyanate,
b) has an average isocyanate functionality of at least 2.5, and
c) contains isocyanurate groups,
with a secondary monoamine at an isocyanate to amine equivalent ratio of about 4:1 to about 14:1 to incorporate biuret groups into said polyisocyanate.
2 . The composition of claim 1 , wherein said adduct has an average isocyanate functionality of at least 2.8 and no more than 8.
3 . The composition of claim 2 , wherein said adduct has an average isocyanate functionality of at least 3.0 and no more than 6.
4 . The composition of claim 1 , wherein said adduct has an NCO content of from 10 to 25% by weight.
5 . (canceled)
6 . The composition of claim 1 , wherein said monoamine is of the formula:
(R 1 )(R 2 )NH,
wherein R 1 and R 2 are the same or different and represent an aliphatic hydrocarbon radical containing from 1 to 20 carbon atoms.
7 . The composition of claim 6 , wherein said monoamine is dibutylamine.
8 . A blocked biuret group-containing polyisocyanate composition having an isocyanate functionality of at least 4 prepared by a process comprising
A) reacting a polyisocyanate adduct which
a) is prepared from 1,6-hexamethylene diisocyanate,
b) has an average isocyanate functionality of at least 2.5, and
b) contains isocyanurate groups,
with a secondary monoamine at an isocyanate to amine equivalent ratio of about 4:1 to about 14:1 to incorporate biuret groups into said polyisocyanate, and
B) reacting the biuret-containing polyisocyanate with a blocking agent.
9 . The composition of claim 8 , wherein said adduct has an average isocyanate functionality of at least 2.8 and no more than 8.
10 . The composition of claim 9 , wherein said adduct has an average isocyanate functionality of at least 3.0 and no more than 6.
11 . The composition of claim 8 , wherein said adduct has an NCO content of from 10 to 25% by weight.
12 . (canceled)
13 . The composition of claim 8 , wherein said monoamine is of the formula:
(R 1 )(R 2 )NH,
wherein R 1 and R 2 are the same or different and represent an aliphatic hydrocarbon radical containing from 1 to 20 carbon atoms.
14 . The composition of claim 13 , wherein said monoamine is dibutylamine.
15 . The composition of claim 8 , wherein said blocking agent comprises a member selected from the group consisting of phenol, cresol, aliphatic substituted phenols, amides, oximes, hydrazones, and pyrazoles.
16 . The composition of claim 8 , wherein said blocking agent comprises a member selected from the group consisting of dimethylpyrazole, ε-caprolactam and methyl ethyl ketoxime.
17 . The composition of claim 8 , wherein said blocking agent comprises dimethylpyrazole.
18 . The composition of claim 8 , wherein said blocking agent comprises ε-caprolactam.
19 . The composition of claim 8 , wherein said blocking agent comprises methyl ethyl ketoxime.