Bayer Aktiengesellschaft

Klaus Jost

Stefan Penninger

Peter Heitk&auml;mper

Rolf-Volker Meyer

Christian Wamprecht

Hans-Joachim Scholl

Bernhard Jansen

Rudolf Sundermann

Joachim Wagner

Eduard Mayer

Gunter Hammen

Christian Wolfrum

Thomas M&uuml;nzmay

The present invention relates to polyurethane cast elastomers which are prepared from higher molecular weight polyhydroxy compounds, durene diisocyanate and low molecular weight chain-lengthening and/or crosslinking agents. These elastomers are particularly useful for the production of moldings exposed to high mechanical stresses.

Polyurethane cast elastomers based on durene diisocyanate

Durene diisocyanate is prepared by reacting durene with nitric acid in sulfuric acid, catalytic hydrogenation of the dinitrodurene that is formed, and phosgenation of the resultant durene diamine in a conventional manner. The intermediate products dinitrodurene and durene diamine do not have to be worked up in a complicated manner as solid products, but can be worked up in dissolved form. The intermediate products dinitrodurene and durene diamine do not have to be isolated and purified in a complicated manner. but can be processed directly after preparation. Another advantage of this process is that only a single organic solvent need be used for the overall preparation process. Separation and re-use of spent acid in the conversion of durene with nitric acid also renders the process of the present invention significantly less environmentally harmful than the known processes of the prior art.

Process for the preparation of durene diisocyanate

Process for the preparation of isocyanates

The present invention relates to mixtures of cycloaliphatic diisocyanates corresponding to formula 1) ##STR1## wherein R represents a saturated, linear, aliphatic hydrocarbon residue having 8 to 15 carbon atoms. The present invention also relates to a process for the preparation of these diisocyanate mixtures and to their use for the production of polyisocyanate addition products.

Mixtures of cycloaliphatic diisocyanates, a process for their

Diisocyanates containing carboxylic acid ester groups corresponding to the formula: ##STR1## in which R and R.sup.1 represent specified groups are produced by phosgenation of the corresponding diamines, optionally present in the form of an ammonium salt. These diisocyanates are useful as starting materials in the production of plastics containing urethane and/or urea groups and as starting materials for the production of intermediate products used for the production of such plastics.

Diisocyanates and processes for their production and use

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Dormagen, Germany

Klaus Jost