Polyisocyanate mixtures comprising cycloaliphatic structural elements
View Patent ↗The present invention relates to innovative polyisocyanate mixtures comprising cycloaliphatic structural elements and containing exclusively linear-aliphatically attached free isocyanate groups, to a process for preparing them and to their use as a starting component in the production of polyurethane plastics, more particularly as a crosslinker component in polyurethane coating materials and coatings.
1. Process for preparing polyisocyanate mixtures comprising cycloaliphatic structural elements and also linear-aliphatically attached free isocyanate groups, the process comprising reacting:
A) a polyisocyanate component having an average functionality of 2.0 to 5.0 and a linear-aliphatically attached isocyanate group content (calculated at NCO; molecular weight=42) of 8.0% to 27.0% by weight
with
B) 2 to 80% by weight, based on the total amount of components A) and B), of at least one hydroxyurethane which is based on a cycloaliphatic di- and/or polyisocyanate, is free from isocyanate groups, optionally contains urea groups, has a number-average molecular weight of 260 to 8000 g/mol and has an average OH functionality of 1.0 to 6.0
wherein the linear-aliphatically attached isocyanate group content of the resultant polyisocyanate mixtures is 4.0 to 26.0% by weight and the average NCO functionality is 1.9 to 8.0.
2. Process according to claim 1 , wherein the isocyanate groups contained in the polyisocyanate mixtures are exclusively linear-aliphatically attached.
3. Process according to claim 1 , wherein component A) comprises polyisocyanates with uretdione, isocyanurate, allophanate, biuret and/or iminooxadiazinedione structures based on hexamethylene diisocyanate.
4. Process according to claim 1 , wherein component B) comprises hydroxyurethanes having a number-average molecular weight of 290 to 5000 g/mol.
5. Process according to claim 1 ,wherein component B) comprises hydroxyurethanes having an average OH functionality of 2.0 to 3.2.
6. Process according to claim 1 , wherein component B) comprising hydroxyurethanes prepared using cycloaliphatic isocyanates selected from the group consisting of isophorone diisocyanate, 1,3-diisocyanato-2(4)-methylcyclohexane, 4,4′- and 2,4′-diisocyanatodicyclohexylmethane and polyisocyanates based on those diisocyanates.
7. Process according to claim 1 , wherein component B) comprises hydroxyurethanes prepared using isocyanate-reactive compounds selected from the group consisting of 1,3- and 1,4-butanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, 2-(methylamino)ethanol, diethanolamine, n-propanol, isopropanol and dibutylamine.
8. Process according to claim 1 , wherein component B) is used in an amount of 6% to 50% by weight, based on the total amount of components A) and B) based on solids content.
9. A polyisocyanate mixture obtained by a process according to claim 1 .
10. A polyisocyanate mixture according to claim 9 , wherein the isocyanate groups contained are proportionally or completely blocked.
11. A polyurethane composition produced from the polyisocyanate mixtures of claim 9 .
12. A coating composition produced from the polyisocyanate mixtures according to claim 9 .
13. A substrate coated with coating compositions according to claim 12 .