Cycloaliphatic aldimine mixture
A mixture of isomeric aldimines of the formulae (Ia), (Ib) and (Ic) in which the ratio of the trans,trans isomer (Ia) to the sum of the cis,trans isomer (Ib) and the cis,cis isomer (Ic) is in the range of 5/95 to 30/70, and its use as latent hardener for moisture-curing isocyanate-functional polyurethane compositions. The inventive mixture of isomeric aldimines enables polyurethane compositions with very low content of monomeric isophorone diisocyanate and excellent stability under outdoor wheathering conditions and high UV load, which cure quickly to an elastic material of low surface tack and good mechanical properties, particularly in terms of high tensile strength and modulus of elasticity at high elongation. Such compositions are particularly suitable as elastic adhesives and/or sealants or elastic coatings, particularly for outdoor use such as on roofs, floors or ships.
1 . Mixture of isomeric aldimines of the formulae (Ia), (Ib) and (Ic),
wherein the ratio of the trans, trans isomer (Ia) to the sum of the CIS, trans isomer (Ib) and the cis, cis isomer (Ic) is in the range of 5/95 to 30/70
wherein each Y is independently selected from the group consisting of:
a branched C 3 to C 7 alkyl,
a moiety of the formula (II),
wherein
R 1 and R 2 are the same or different C 1 to C 4 alkyls, or are joined together to form a C 4 to C 6 alkylene, and
R 5 is H or a C 1 to C 17 alkyl optionally containing one or more ether groups, and
a moiety of the formula (III),
wherein
R 1 and R 2 are the same or different C 1 to C 4 alkyls, or are joined together to form a C 4 to C 6 alkylene, and
R 3 and R 4 are the same or different C 1 to C 8 alkyls optionally containing ether oxygen, or are joined together to form a C 4 to C 6 alkylene optionally containing ether oxygen.
2 . The mixture of isomeric aldimines according to claim 1 , wherein the ratio of the trans, trans isomer (la) to the sum of the cis, trans isomer (lb) and the cis, cis isomer (Ic) is in the range of 15/85 to 25/75.
3 . The mixture of isomeric aldimines according to claim 1 , wherein Y is a branched C 3 to C 7 alkyl.
4 . The mixture of isomeric aldimines according to claim 1 , wherein Y is a moiety of the formula (II),
wherein
R 1 and R 2 are the same or different C 1 to C 4 alkyls, or are joined together to form a C 4 to C 6 alkylene, and
R 5 is H or a C 1 to C 17 alkyl optionally containing one or more ether groups.
5 . The mixture of isomeric aldimines according to claim 1 , wherein Y is a moiety of the formula (III),
wherein
R 1 and R 2 are the same or different C 1 to C 4 alkyls, or are joined together to form a C 4 to C 6 alkylene, and
R 3 and R 4 are the same or different C 1 to C 8 alkyls optionally containing ether oxygen, or are joined together to form a C 4 to C 6 alkylene optionally containing ether oxygen.
6 . The mixture of isomeric aldimines according to claim 5 , wherein R 1 and R 2 are both methyl and R 3 and R 4 are joined together to form a 3-oxa-1,5-pentylen group, which is part of a morpholine ring.
7 . A latent hardener for moisture-curing polyurethane compositions comprising the mixture of isomeric aldimines according to claim 1 .
8 . The latent hardener for moisture-curing polyurethane compositions according to claim 7 , further comprising at least one further aldimine of the formula (VII),
wherein
n is 2 or 3,
A is the residue of a di- or triamine after the removal of the amine groups, wherein the di- or triamine is selected from the group consisting of hexane-1,6-diamine, 2-methylpentane-1,5-diamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 4 (2)-methylcyclohexane-1,3-diamine, 1,3-bis(aminomethyl) cyclohexane, 1,4-bis(aminomethyl) cyclohexane, 1,3-bis(aminomethyl) benzene, 1,2-diaminocyclohexane, polyoxypropylene diamines with an average molecular weight M n in the range of 200 to 4′000 g/mol and polyoxypropylene triamines with an average molecular weight M n in the range of 380 to 5′000 g/mol,
and Y is the same substituent in the formulae (la), (lb) and (Ic) and in the formula (VII).
9 . Moisture-curing polyurethane composition comprising
at least one polyisocyanate and/or isocyanate-functional polymer obtained from the reaction of at least one monomeric diisocyanate and at least one polyol, and
a mixture of isomeric aldimines according to claim 1 .
10 . The moisture-curing polyurethane composition according to claim 9 , containing an isocyanate-functional polymer with an NCO-content in the range of 1 to 10 weight-% obtained from at least one polyether polyol.
11 . The moisture-curing polyurethane composition according to claim 9 , containing an amount of monomeric diisocyanates of below 0.1 weight-% in relation to the total composition.
12 . A cured composition, obtained from the moisture-curing polyurethane composition according to claim 9 after its contact with moisture.
13 . Elastic coating, adhesive or sealant containing the cured composition according to claim 12 .
14 . Primer, paint or varnish containing the cured composition according to claim 12 .