A tire, the sidewalls of which comprise a varnished film, and a process for forming an varnished film on the outer face of the sidewalls

摘要

The present invention relates to a tire the sidewalls of which comprise a vulcanized elastomeric composition, and a process for forming an even, varnished film on at least one of said sidewalls. According to the invention, the composition comprises in combination:a polymer containing an oxy radical of the formula -O- therein, the polymer having an alkyl group on one side of the oxy radical and, on the other side of the oxy radical, at least one alkene polyoxide block of the formula (CnH2nO)z joined to a hydrogen atom at the chain end thereof, such that the hydrogen atom and the end terminal oxygen of the alkene polyoxide block form an alcohol function, in the amount of between 0.3 and 5 phr (parts by weight per 100 parts elastomer), andan alkali metal salt of an alkylsulphonic or alkylsulphuric acid, in an amount of between 0.5 and 10 phr.The invention also provides process for forming an even, varnished film on sidewalls composed of the composition which involves exposing the sidewalls to an ozone environment of at least 20 parts per 100 million in a chamber for at least 48 hours. The invention applies in particular to the protection of said tire sidewalls against the visible effects of the migration of antioxidants and antiozonants present therein.