Abstract:
The invention relates to novel compounds containing uretdione groups, to a process for preparing them by dimerizing aliphatic and/or cycloaliphatic isocyanates containing exclusively secondary and/or tertiary isocyanate groups and also to the use of uretdione polyisocyanates obtainable by this process from diisocyanates containing exclusively secondary and/or tertiary isocyanate groups as a starting component for polyurethane polymers, in particular as an isocyanate component in the preparation of uretdione powder coating crosslinkers.
Abstract:
Blocked polyisocyanates and one-component stoving systems containing these blocked polyisocyanates, and the preparation thereof and their use for the preparation of lacquers, paints, adhesives and elastomers, wherein blocked polyisocyanates are prepared by reacting polyisocyanates with secondary amines corresponding to the formula wherein R1—R4 can be identical or different and denote hydrogen, C1–C6-alkyl or cycloalkyl, R5 denotes C1–C10-alkyl, C3–C10-cycloalkyl, y denotes a number from 2 to 8, and B represents wherein R6–R8 can be identical or different and independently of one another denote C1–6-alkyl and/or C3–C6-cycloalkyl, R9 denotes hydrogen or C1–6-alkyl or C3–C6-cycloalkyl.
Abstract:
The invention relates to a process for preparing polyisocyanates having a high uretdione group content by phosphine-catalysed isocyanate oligomerization in the presence of organic carbonates and/or nitriles.
Abstract:
The invention relates to the use of cycloalkylphosphines as catalysts for isocyanate dimerization and to a process for preparing polyisocyanates containing uretdione groups.
Abstract:
Storage-stable blocked polyisocyanates prepared by reacting one or more polyisocyanates with one or more biuretizing agents and optionally, catalysts such that in the blocked end product there are 5-45 equivalent percent of biuret groups according to formula (I) based on the sum total of all free and blocked NCO groups; optionally modifying the resulting biuret polyisocyanates with the aid of isocyanate-reactive compounds and/or catalysts, with further reaction of free NCO groups; and subsequently blocking at least 95 mol percent of the remaining free NCO groups with a blocking agent according to the formula R1R2NH, where R1 and R2 independently of one another are aliphatic or cycloaliphatic C1-C12 alkyl radicals. The blocked polyisocyanates can be used to make polyurethane polymers and coating compositions, which can be used to coat substrates.
Abstract:
The invention relates to particular mixtures of polyisocyanates which are blocked with 3,5-dimethylpyrazole, and to the use thereof as crosslinking component in single-component stoving lacquers, especially automotive clear lacquers.
Abstract:
The invention relates to a method of preparing an aliphatic polyisocyanate by conversion of an aliphatic diisocyanate to a polyisocyanates in the presence of a catalyst, wherein the catalyst contains a saline compound having 5 to 97.1 wt. % of a 1,2,3- and/or a 1,2,4-triazolate (calculated as C2N3, molecular weight 66) in the anion, the isocyanates thus prepared and the polyurethane paints and coatings containing them.
Abstract:
The present invention relates to water dispersible polyisocyanate mixtures prepared from aliphatic, cycloaliphatic, araliphatic and/or aromatic diisocyanates and having a) an average isocyanate functionality of at least 2.0, b) a content of 5.0 to 25.0 wt. %, based on resin solids, of isocyanate groups (calculated as NCO; molecular weight=42) and c) a content of 2 to 50 wt. %, based on resin solids, of ethylene oxide units calculated as C2H2O; molecular weight 44) incorporated within polyether chains containing an average of 5 to 35 ethylene oxide units, wherein at least 60 mole % of the polyether chains are connected via allophanate groups to two polyisocyanate molecules which are each prepared from at least two diisocyanate molecules. The present invention also relates to a process for the preparation of these water dispersible polyisocyanate.
Abstract:
A process for the purification of organic isocyanates or isocyanate mixtures in which the amount of chlorine compound(s) present is reduced by mixing the isocyanate(s) or isocyanate mixtures with a gel-type or macroporous, anion-exchanging organic material having tertiary and/or quaternary amino groups. The process renders possible a purification of the isocyanates from chlorine-containing compounds which is milder than in conventional processes and is therefore particularly suitable for temperature-sensitive isocyanates.
Abstract:
The present invention relates to a powder coating composition for the production of non-yellowing flexible coatings which is solid below 30.degree. C. and liquid above 120.degree. C. and contains a mixture of A) a polyisocyanate component which i) has a content of blocked isocyanate groups (expressed as NCO, molecular weight=42) of 3.0 to 14.0% by weight, ii) has a functionality, based on the blocked isocyanate groups, of 1.9 to 2.3 and iii) and contains at least one .epsilon.-caprolactam-blocked polyisocyanate based on the reaction product of 4,4'-diisocyanatodicyclohexyl methane with a polyol component having an average molecular weight of 90 to 400 and containing at least 50% by weight, based on the weight of the polyol component, of one or more (cyclo)aliphatic diols containing 4 to 12 carbon atoms, B) a polyol component containing at least one polyhydroxy polyacrylate having an OH number of 40 to 120 and C) an organotin catalyst for the reaction between hydroxyl groups and blocked isocyanate groups, wherein components A) and B) are present in quantities which correspond to an equivalent ratio of blocked polyisocyanate groups to hydroxyl groups of 0.5:1 to 1.2:1. The present invention also relates to the a heat-resistant substrate which is coated with this powder coating composition.