Bayer Aktiengesellschaft

Gerhard Henes

Dieter Freitag

Ludwig Bottenbruch

Claus H Wulff

Pramod Gupta

Peter Tacke

Werner Mormann

Hans Muller

Ernst Meisert

Wolfgang Krohn

Klaus Brecht

Franz-Josef Bohne

Joachim Zirner

The invention relates to a process for the preparation of aromatic polyester-carbonates wherein, in a first stage, aromatic oligo-esters or oligo-ester-carbonates having hydroxyl end groups are prepared from diaryl esters of aromatic dicarboxylic acids (or their starting materials) and diphenols and, optionally, a diaryl carbonate, by trans-esterification in the melt, and in a second stage these oligo-esters or oligo-ester-carbonates are condensed with phosgene by the phase boundary process to give the polyester-carbonate.

Two stage process for the production of aromatic polyester-carbonate

The instant invention is directed to a process for the production of a cellular polyurethane elastomer having a density of 0.45 to 0.8 g/cm.sup.3, comprising:

Process for the production of cellular polyurethane elastomers

This invention relates to a new process for the production, in inert organic solvents, of physiologically compatible polyisocyanates containing isocyanurate groups which have a monomeric diisocyanate content, based on solids, of at most 0.7%, by weight. The process uses Mannich bases as the trimerizing catalyst at temperatures below 60.degree. C and the reaction is terminated at the desired degree of trimerization by thermally decomposing the catalyst or by deactivating with a catalyst poison.

Process for the production of polyisocyanates containing isocyanurate

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Leverkusen, Germany

Gerhard Henes