Title: THERMOPLASTIC POLYURETHANE WITH REDUCED TENDENCY TO BLOOM FROM A BIO-BASED GLYCOL

 Number/Link: WO2012173911

Applicant/Assignee: Lubrizol

Publication date: 20-12-2012

“Gist”: TPUs with less tendency to “bloom” are prepared from diisocyanate, diol chain extender and a polyester polyol based on 1,3-propanediol and adipic acid.

Why it is interesting:  “Blooming” is an undesirable effect where TPU  becomes ‘hazy’ or ‘fogged’ as a consequence of non-reacted species exuding to the surface. It is known that cyclic esters, which are a by-product of polyester polyol production, contribute greatly to this effect. It is also known that 1,3-propanediol and 1,6-hexandiol based polyesters show less cyclic esters than e.g. DEG based polyesters (see p4 of WO2012125353 to Stepan). So, while still interesting, this case is not surprising.

1,3-propanediol