Patent Title: URETHANE DECOMPOSING METHOD AND URETHANE DECOMPOSING AGENT

 Number/Link:  US2016/0257800

Applicant/Assignee: Obihiro University

Publication date: 8-09-2016 (priority PCT/JP)

“Gist”: Prepolymer from ether-ester polyol and aliphatic isocyanate

Why it is interesting: There is a growing trend in current surgerical practice to replace sutures and staples with adhesives. These tissue adhesives need to have a particular set of properties, like the correct viscosity, hardening speed, biodegradability and toxic and allergenic properties. Current surgical adhesives are often cyanoacrylates, which react very fast, are brittle and show poor biodegradability, or protein-based adhesives which are costly and form weak bonds. According to this invention an improved polyurethane tissue adhesive can be prepared from an isocyanate-ended prepolymer based on an aliphatic isocyanate and a polyol.  The polyol is prepared from a starter polyol or amine which is reacted with a mixture of an alkoxide and about 10-20% of a  lactide (or glycolide or cyclic acid anhydride).  The lactide is randomly copolymerized with the alkoxide using DMC catalysis. The polyol is then reacted with an aliphatic isocyanate, pref. HDI or IPDI in a NCO/OH ratio of about 8:1. After that monomeric isocyanate is removed by thin film distillation down to less than 1% free monomer.
The adhesives are said to be fast, non-toxic, non-allergenic and biodegradable.

L-Lactide