Title: A POLYESTER POLYURETHANE MATERIAL WITH LONG TERM HYDROLYSIS RESISTANCE

 Number/Link: WO2014114614

Applicant/Assignee: Bayer

Publication date: 31-07-2014

“Gist”: Hydrolysis resistant polyurethane elastomers can be prepared from sterically hindered polyester polyols together with a perchlorate salt.

Why it is interesting: Because of their high mechanical properties and abrasion resistance, polyester-based polyurethane elastomers are a material of choice in e.g. the footwear and automotive industries. Main drawback however is their susceptibility to hydrolysis which causes loss of physical properties in moist environments.  According to the current invention, hydrolysis resistance can be greatly improved by using a specific polyester polyol together with a perchlorate salt (e.g. 0.3% sodium perchlorate on the total composition). The polyester polyol is based on a diacid (e.g. adipic acid) and a mixture of diols one of which contains alkyl side groups (e.g. a mixture of butanediol and neopentylglycol).
The invention is actually a combination of two known ‘tricks’:  the neopentyl glycol will introduce some hydrophobicity and steric hindrance into the polyester backbone, and the perchlorate may have a weak coordination with the hydrolysable ester bonds thus forming a steric protection layer (at least according to Bayer’s own WO2013/030147). Because both effects are known and published I doubt that this is patentable.

Neopentylglycol