Patent Title: METHOD FOR MODIFYING AT LEAST PENTAMETHYLENE DIISOCYANATE BY MEANS OF SPIROCYCLIC AMMONIUM SALTS AS CATALYST

 Number/Link:WO2018/153801 (German)

Applicant/Assignee:  Covestro

Publication date: 30 August 2018

“Gist”: PDI is trimerized using a spirocyclic ammonium salt

Why it is interesting: The oligomerization of diisocyanates by trimerization or dimerization is well known.  Diisocyanates are partially trimerized using a catalyst which is “killed” when the desired conversion is reached. The remaining monomer is then removed. In this invention pentamethylenediisocyanate is trimerized using a spirocyclic ammonium salt as catalyst, which apparently results in a desirable amount of asymmetric trimer (i.e. iminooxadiazinedione groups) as opposed to symmetric trimer (isocyanurate groups).  In the examples 5-azo-spiro[4,5]decane hydrogendifluoride is used as catalyst.

Spirocyclic ammonium salt used as catalyst in the invention