Title: POLYISOCYANATE POLYADDITION PRODUCTS, A PROCESS FOR PREPARATION THEREOF AND USE THEREOF

 Number/Link: US2013/303720

Applicant/Assignee: Bayer

Publication date: 14-11-2013 (priority PCT/DE)

“Gist”: Use of specific acid-bocked amidines as thermo-latent catalysts for cast elastomers.

Why it is interesting: For the production of solid (non-foamed) cast elastomers it is advantageous to use catalysts which specifically promote the NCO – OH reaction and as little as possible side reactions such as NCO – water, dimerization, trimerization, allophanatization etc. It is also advantageous that the catalyst can be ‘switched on’ at a certain temperature so that elastomer systems with a long open time and short cure time can be formulated. According to the current invention this can be accomplished by using an acid blocked amidine, pref. 1,8-diazabicyclo[5.4.0]undec-7ene (DBU) blocked with (pref.) isocrotonic acid (Z-2-butenoic acid), together with a zeolite as water scavenger. The system has the added advantage that no heavy metals are used.

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)