The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 07, 2020
Filed:
Dec. 18, 2017
Covestro Deutschland Ag, Leverkusen, DE;
Covestro Deutschland AG, Leverkusen, DE;
Abstract
The industrial scale preparation of isocyanates gives rise to distillation bottom streams that are in need of further workup. These distillation bottom streams still also contain, as well as a distillation residue consisting of compounds that can be evaporated without decomposition only with great difficulty if at all (also referred to as residue for short), proportions of the desired target product (i.e. isocyanate to be prepared). The present invention relates to a process that enables recovery, in an efficient manner, of this proportion of isocyanate to be prepared in a distillation bottom stream which is obtained in the workup of the crude liquid process product which contains the isocyanate to be prepared and is formed in an isocyanate preparation process. More particularly, the present invention relates to a drying step in which the isocyanate to be prepared is recovered to form a solid material that has been largely to completely freed of this isocyanate. This drying step is characterized by a minimum content of compounds containing carbodiimide groups of 15% by mass, preferably 20% by mass, more preferably 30% by mass, based on the total mass of the distillation residue fed to the drying apparatus used, where this minimum content can also be adjusted by an in situ carbodiimidization.