Title: POLYURETHANE-BASED EXPANDABLE POLYMER PARTICLES

 Number/Link: WO2014/006182  (German)

Applicant/Assignee: BASF

Publication date: 9-01-2014

“Gist”: Microgranules of TPU/PS copolymer containing pentane can be expanded into insulation panels using standard EPS equipment.

Why it is interesting: Contrary to polystyrene, thermoplastic polyurethane cannot be ‘imbued’ with a physical blowing agent like pentane to make steam-expandable particles. This is due a.o. to the high diffusion rate of pentane (e.g.) in TPU.  BASF have now found that by using a TPU/PS copolymer, expandable particles can be prepared which can be used in standard EPS (expandable polystyrene) equipment to make insulation panels. The TPU used is based on 4,4′-MDI, polyTHF and butanediol such that the vicat softening point is below 80°C.   The TPU, in the form of microgranules (0.5-2mm), is swollen in styrene containing dicumylperoxide, dispersed in water and heated to polymerisation.  A blowing agent like (pref) pentane is added to the dispersion as well. The resulting particles are expandable and can be used to make insulation panels of 50-150 kg/m³.

Expandable Polystyrene.