Bayer Aktiengesellschaft

Harald Mertes

Josef Pedain

Reinhard Halpaap

Lutz Schmalstieg

Hans-Josef Laas

Frank Richter

Martin Brahm

Jurgen Schwindt

Dieter Mager

Karsten Danielmeier

Hans-Ulrich Meier-Westhues

Siegfried Oeckl

Thomas Klimmasch

Eberhard K&ouml;nig

Eberhard Arning

Carl-Gerd Dieris

Joachim Sch&uuml;ll

Bernd Steinhilber

Reinhard Jahn

The present invention relates to an improved process for the continuous preparation of polyisocyanates with a biuret structure comprising the steps of continuously reacting excess amounts of organic diisocyanates having exclusively aliphatically and/or cycloaliphatically bound isocyanate groups with organic diamines having exclusively aliphatically and/or cycloaliphatically bound primary amino groups at temperatures above 170&deg; C. and adding acid before or during the reaction.

Process for the preparation of polyisocyanates with a biuret structure

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.

Dimethylpyrazole-blocked isocyanate mixtures

Light-fast polyisocyanates having good solubility in non-polar solvents

The present invention relates to a process for the production of polyisocyanates containing allophanate groups and having aliphatically and/or cycloaliphatically bound isocyanate groups by reacting organic compounds containing urethane groups with organic polyisocyanates containing aliphatically and/or cycloaliphatically bound isocyanate groups in the presence of tin compounds and to the use of these polyisocyanates, optionally blocked with blocking agents for isocyanate groups, as an isocyanate component in the production of polyurethanes, in particular polyurethane coatings.

Process for the production of light-stable polyisocyanates containing allophanate groups

The invention relates to olefinically unsaturated polyisocyanates containing allophanate groups and having an NCO content of 6 to 20% by weight, an iodine value of 15 to 150, a content of hydrocarbon chains containing 12 to 30 carbon atoms of 100 to 700 mg/g and a content of allophanate groups of 10 to 300 mg/g, to a process for their production by reaction of a polyisocyanate component containing urethane groups with excess polyisocyanates, and to a one-component coating composition containing these olefinically unsaturated polyisocyanates as binders.

Olefinically unsaturated polyisocyanates

The present invention relates to a polyisocyanate mixture containing isocyanate trimers provided that i) 30 to 100 mole percent of the trimers are iminooxadiazine diones B and ##STR1## ii) 0 to 70 mole percent of the trimers are isocyanurates A iii) less than 10 mole percent of the polyisocyanate mixture is of the uretone imine structural type, and iv) the ratio of the sum of the mole percents of trimers A and B to the mole percent of uretdiones is greater than 4:1 wherein R.sup.1, R.sup.2 and R.sup.3 are the same or different and represent the groups obtained by removing an isocyanate group from an aliphatic, cycloaliphatic, aromatic and/or araliphatic isocyanate having an NCO content of less than 70% and/or their oligomers. The present invention also relates to a process for the preparation of these isocyanate trimers, mixtures of these isocyanate trimers with other polyisocyanates and compositions containing these isocyanate trimers, in which the isocyanate groups may optionally be blocked with blocking agents, and compounds containing two or more isocyanate-reactive groups.

Isocyanate trimers containing iminooxadiazine dione groups, their

The present invention relates to polyisocyanate mixtures which are reaction products of 4,4'-diphenylmethane diisocyanate as the isocyanate component, are liquid at greater than 5.degree. C. and have an NCO content of 14.5 to 24% by weight and an allophanate group content (calculated as C.sub.2 HN.sub.2 O.sub.3, molecular weight = 101) of 7.7 to 14.5% by weight; a process for the production of these polyisocyanate mixtures by reacting 4,4'-diphenylmethane diisocyanate as the exclusive isocyanate component with one or more monohydric alcohols having 4 to 16 carbon atoms at an NCO/OH equivalent ratio of 5:1 to 8.5:1 and at a temperature of up to 160.degree. C. to form urethane groups and during or subsequent to urethane formation, converting the urethane groups to allophanate groups in the presence of a catalyst which promotes allophanate formation; and the use of these polyisocyanate mixtures as the polyisocyanate component in two-component polyurethane coating compositions.

Polyisocyanate mixtures which are liquid at greater than 5.degree. C

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Bridgeville, PA, United States of America

Harald Mertes