TPU Shrink Wrap


Number/Link: WO2017/108920

Applicant/Assignee: BASF

Publication Date: 29-jun-2017

“Gist”: Shape memory TPU is used as shrink wrap

Why it is interesting: A thermoplastic polyurethane with a shape-memory is prepared from a diisocyanate, a chain extender and a polyol comprising an ‘aromatic polyester block’, especially a polyethylenetherephthalate block. The composition is chosen such that the TPU has a melting point between 160 and 230ºC and another phase transition between 30 and 80ºC (the “switching temperature”). Films of this material are then stretched at a temperature higher than the switching temperature but below melt temperature and then cooled in stretched state. The stretched films are said to be useful as shrink wrap, especially for foodstuffs. No examples are given.
A surprising application for TPU but hardly a surprising TPU invention i.m.o.

Shrink-wrapped Helicopters (Wikipedia)


Highly Tuneable Shape Memory Polyurethanes


 Number/Link: WO2016/126703

Applicant/Assignee: Texas A&M University

Publication date: 11-08-2016

Gist”: SMPUs are made from combinations of different diisocyanates and chain extenders and different levels of crosslinking using thiol-ene click chemistry

Why it is interesting: This invention is about shape memory polyurethanes with tuneable glass transition temperature and stiffness. In a first step a low mole weight TPU is prepared from a diisocyanate and a short chain diol including some trimethylolpropane allyether (TMPAE) and allylalcohol as chain stopper. The TPU is then blended with a polythiol and a photoinitiator to allow for UV curing. The Tg can be tuned from 30 and 105°C by combining different types of chain extenders and di-iso’s ranging from DEG-HDI to CHDM-H12MDI.  The modulus (in the rubber state) can be  varied between 0.4 to 20 MPa by controlling the level of crosslinking through the amount of TMPAE and amount and type of polythiol.  The SMPUs are said to be especially useful for biomedical applications.

Reaction scheme of the invention

Reaction scheme of the invention

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