Phosgene-Free Polyisocyanate with PDMS Backbone

Patent Title: MULTI-FUNCTIONAL CARBAMATE HAVING SOFT-SEGMENTS, POLYISOCYANATE OBTAINED VIA SUBSEQUENT NON-PHOSGENE SYNTHESIS METHODS, URETHANE PREPOLYMER AND ELASTOMERIC URETHANE HAVING SOFT-SEGMENTS DERIVED THEREFROM, AND PREPARATION METHOD THEREOF

 Number/Link: US20180186918

Applicant/Assignee:  Great Eastern Resins Industrial

Publication date: 5 July 2018

Gist”: Biscarbamate with PDMS softblock backbone is heat-cracked into diisocyanates

Why it is interesting: The invention relates to isocyanate-capped “softblock” siloxanyl prepared without using phosgene and polyurethanes derived therefrom. The invention is accomplished by reacting relatively high MW polydimethylsiloxanediamines with diphenylcarbonate.  The resulting biscarbamate is heated under reduced pressure to produce the diisocyanate and to remove the phenol by-product.  The isocyanates can be reacted with polyols and/or chain extenders to produce highly hydrophobic polyurethanes with low surface tension and good chemical resistance.

biscarbamate

Biscarbamate with PDMS backbone

 

“Green” Isocyanate: Renewable and Phosgene-Free

Title: POLYISOCYANATES FROM FUSED BICYCLIC POLYOLS AND POLYURETHANES THEREFROM

 Number/Link: WO2014/062631

Applicant/Assignee: IOWA STATE UNIVERSITY

Publication date: 24-04-2014

Gist”: Isocyanates from acyl azides derived from isosorbide

Why it is interesting:  Fused bicyclic polyols are reacted with anhydrides to form polyacids which are converted to acyl halides which in turn are converted to acyl azides.  The acyl azides rearrange to isocyanates (Curtius Rearragment).  For example isosorbide is reacted with succinic anhydride, then with thionylchloride (SOCl2) to form the di-acylchloride and then with sodium azide (NaN3) to form the di-acylazide which rearranges into the di-isocyanate under liberation of nitrogen. The isocyanate can be reacted with more isosorbide to form a polyurethane. Clever chemistry but hard to judge if it is industrially viable.

Completely renewable polyurethane according to the invention . Click to enlarge.