Title: HYDROLYSIS-RESISTANT POLYURETHANE MOULDED ARTICLES MADE OF POLYESTER POLYURETHANE

 Number/Link: WO2014/095438  (German)

Applicant/Assignee: BASF

Publication date: 26-06-2014

“Gist”: Polyester polyurethane elastomers containing carbodiimides, together with an ionic liquid and an amine catalyst in a specific ratio, show improved hydrolysis resistance.

Why it is interesting: Polyester PU elastomers show higher mechanical properties compared to polyether elastomers but have have a much worse hydrolysis resistance.  It is well known that the hydrolysis resistance can be improved by using sterically hindered carbodiimides (commercially known e.g. as Stabaxol®).  This invention shows that hydrolysis resistance can be even more improved by using a specific molecular ratio (pref. 0.5 : 1 to 2 : 1)  of  ionic liquid to amine catalyst in combination with the carbodiimides. The effect is apparent from the examples where 1-ethyl-3-methylimidazolium ethylsulfate was used as ionic liquid together with ethylenediamine as catalyst.  No theory or explanation for the effect is given and it is not immediately clear to me how this interesting synergy works.

Ionic liquid as used in the invention