Process for the preparation of allophanates which contain isocyanate groups
AssigneeBayer Aktiengesellschaft
InventorsKalus Koenig, Wolfgang Reichmann, Josef Pedain
Life of this patent
Estimating the term…
Abstract
The present invention relates to a process for the preparation of allophanates containing aliphatically and/or cycloaliphatically bound isocyanate groups by the reaction of organic compounds containing urethane groups with organic polyisocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups, characterized in that the reaction is carried out in the presence of strong acids which form a mixed carbamic acid anhydride with aliphatic or cycloaliphatic isocyanates. The present invention also relates to the allophanates produced therefrom.
Claims13
Process for the preparation of allophanates containing aliphatically and/or cycloaliphatically bound isocyanate groups comprising reacting organic compounds which contain urethane groups with organic polyisocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups, characterized in that the reaction is carried out in the presence of strong acids which form a mixed carbamic acid anhydride with aliphatic or cycloaliphatic isocyanates.
A process for the preparation of isocyanate-containing allophanates comprising reacting compounds of the general formula ##STR2## wherein A represents a group of the kind obtained by removal of the hydroxyl groups from an organic compound with a valency of n which contains hydroxyl groups and which, apart from its hydroxyl groups, is inert towards isocyanate groups:
- R.sub.1 represents a group of the kind obtained by removal of the isocyanate groups from a diisocyanate which has aliphatically and/or cycloaliphatically bound isocyanate groups, and
- n represents an integer of from about 1 to 4,
- with polyisocyanates of the general formula
- R.sub.2 (NCO).sub.n
- wherein
- R.sub.2 represents an aliphatic hydrocarbon group with from about 2 to 20, carbon atoms, a cycloaliphatic hydrocarbon group with from about 4 to 20, carbon atoms or a xylylene group, and
- n represents an integer of either 2 or 3,
- characterized in that the reaction is carried out in the presence of strong acids which form a mixed carbamic acid anhydride with aliphatic or cycloaliphatic isocyanates.
A process for the production of storage stable allophanate polyisocyanates comprising reacting
- (i) organic compounds which contain urethane groups with
- (ii) organic polyisocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups,
- characterized in that the reaction is carried out in the presence of strong acids which form a mixed carbamic acid anhydride with aliphatic or cycloaliphatic isocyanates and any excess isocyanate is removed from the reaction mixture.
Dependencies are inferred from the claim text.