Title: POLYURETHANE ON THE BASIS OF SOFT THERMOPLASTIC POLYURETHANE

 Number/Link: US2014/0094571

Applicant/Assignee: BASF

Publication date: 3-04-2014 (priority PCT/DE)

“Gist”: A soft TPU is crosslinked using isocyanate dissolved in another TPU.

Why it is interesting: Crosslinking thermoplastic polyurethane parts to improve certain mechanical- and creep properties is known. In this case the crosslinking agent is an isocyanate with a functionality larger than 2, preferably an MDI prepolymer.  The isocyanate is dissolved in another TPU by melt blending in a twin-screw extruder at a temperature below 160°C and pelletizing. Pellets of a soft, polyester-based, TPU with a hardblock content less than 5% are mixed with the isocyanate-containing pellets, injection moulded and post-cured to crosslink the moulded part.

TPU phone case.