公开(公告)号：US20220267500A1

公开(公告)日：2022-08-25

申请号：US17625271

申请日：2020-07-06

申请人： COVESTRO INTELLECTUAL PROPERTY GMBH & CO. KG

发明人： Michael Merkel ,  Anna Grosse Daldrup ,  Christoph Eggert ,  Stefan Groth ,  Markus Meuresch ,  Monika Groetzner ,  Stefan Nolte

IPC分类号： C08G18/02 ,  B01D5/00 ,  B01D1/22 ,  B01D3/14

摘要： The invention relates to a method for producing polyisocyanates having a low monomer content, said method comprising the following steps: (i) modifying at least one monomeric diisocyanate to obtain a mixture containing at least one polyisocyanate and unconverted monomeric diisocyanate, (ii) separating the mixture obtained in step (i) into at least one gaseous stream containing monomeric diisocyanate and a liquid stream depleted of monomeric diisocyanate, (iii) partially condensing the gaseous stream from (ii) in at least one condenser, so that a liquid condensate and an uncondensed vapour stream are obtained, (iv) post-condensing the uncondensed vapour stream obtained in step (iii) in at least one post-condenser, so that a post-condensate and an uncondensed waste gas are obtained, and (v) delivering the uncondensed waste gas from step (iv) to the suction side of a vacuum pump, characterised in that the at least one post-condenser in step (iv) is operated at a post-condenser temperature, and the at least one condenser in step (iii) is operated at a condenser temperature, wherein the post-condenser temperature is lower by ≥1 to ≤168 K than the condenser temperature.