Patent Title: COMPOSITION FOR TRANSPARENT SHAPED BODIES BASED ON POLYURETHANE

 Number/Link: WO2016/113295

Applicant/Assignee: Covestro

Publication date: 21-07-2016

“Gist”: Use of amino-chelate-tin complex as delayed action catalyst for transparent PU elastomers

Why it is interesting: Lenses for eyeglasses are increasingly made from transparent organic polymers like polyurethane elastomers. The production requires a specialized casting process into glass moulds, followed by an exact tempering over many hours. According to this invention polyurethane elastomers, useful for the production of eyeglass lenses, can be made form a composition containing a polyol, a cycloaliphatic or araliphatic diisocyanate, an internal mould release agent and a thermo-latent catalyst. The catalyst is an inorganic metal complex comprising Sn (preferred) and at least one tert-amine containing chelating ligand. The composition is said to have a longer ‘open-time’ as the catalyst-free system.

Example of thermo-latent catalyst according to the invention