Polycarbonate PU Foams with Reduced VOC Emissions


Number/Link: WO2017/085201 (German)

Applicant/Assignee: Covestro

Publication Date: 26-may-2017

“Gist”: Use of urea reduces the formation of propylenecarbonate from polycarbonate polyols

Why it is interesting: Covestry is betting heavily on polyethercarbonate polyols for use in polyurethane foams, using the carbon-negative footprint as a selling point. The use of polyethercarbonate polyols in PU foams can, however, result in the formation of propylenecarbonate resulting from a retro reaction promoted by conventional amine catalysts. Propylenecarbonate will contribute to the total VOC emissions of foams and other materials. According to this invention, the retro reaction can -surprisingly- be prevented or reduced by using urea or urea-derivatives in the foam formulation. In the examples urea and dimethylaminopropylurea are used together with a tin catalyst,  polyethercarbonate polyols and TDI to produce flexible foams with reduced propylenecarbonate content.




Thermoreversible Polyurea


 Number/Link: W02016/069582

Applicant/Assignee: University of Illinois

Publication date: 6-05-2016

Gist”: Urea bonds prepared from sterically hindered amines and isocyanates

Why it is interesting: The N-C bond in urea is very stable due to conjugation of the lone electron pair of the nitrogen atom with the cabonyl group.  According to this invention, the nitrogen atom can be subsituted with a strongly hindering group such that the coplanarity, and therefore most of the conjugation, of the C-N and C=O bonds is lost. These hindered urea bonds are much less stable and can reversibly depolymerize at relatively low temperatures. Thermoreversible bonds can be useful in a number of smart materials such as self-healing-, “4D printing”- , and reprogrammable shape memory materials. In an example a shape memory material with a Tg of 53°C and a Young’s Modulus of about 2 GPa was prepared by reacting 2-(t-buylamino)ethanol (TBAE) and trimerized hexamethylene diisocyanate (THDI). The ‘permanent shape’ of the material could be re-programmed by forcing the material in a new shape for 72 hours at 60°C.

Polurethane-urea with thermoreverisble urea bonds

Poly(urethane-urea) with thermoreverisble urea bonds

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