Cleremont-Ferrand, France -- An inner coating of polyurethane designed to eliminate noise from automobile tyres is the subject of an international patent application by French manufacturer Michelin.
The innovation was filed with the World Intellectual Property Office (WIPO) under patent number WO/2013/182477 earlier this year and published on the organisation's website in December.
The French firm outlined details of the specific polyurethane foam used in its application.
According to the filing: 'The polyurethane is based on a diphenylmethane diisocyanate (MDI), in particular on 4,4'-diphenylmethane diisocyanate and a polyol which has an ethylene oxide content greater than 50% (% by weight).
"This specific polyurethane formulation makes it possible to obtain a light foam which efficiently absorbs noise.
"It has the advantage of being simple and inexpensive and of being easy to use by direct casting of the reagents in the tyre of the invention."