Self-sealing tyre for vehicle wheels

The tyre according to any one of the preceding claims wherein said self-supporting thermoplastic film comprises at least 50%, 60%, 70%, 80% or 90% or more than 90%, 95% or 98% by weight with respect to the weight of the film itself of said at least one or more polyolefins and/or from 1 to 50%, preferably from 10 to 40%, more preferably from 15 to 35% by weight of one or more polar polymers selected from among polyvinyl acetate, ethylene-vinyl acetate copolymers, EVOH, polyvinyl acetate with a high level of hydrolysis, polyvinyl alcohol (PVA, PVOH) or mixtures thereof.

The tyre according to any one of the preceding claims wherein the at least one polyolefin of said self-supporting thermoplastic film is selected from among homopolymers and copolymers of ethylene, of propylene, of C4-C20 alpha-olefin and mixtures thereof, preferably it is a polyethylene selected from among homopolymers of ethylene, copolymers of ethylene with propylene, copolymers of ethylene with a C4-C8 alpha-olefin and copolymers of ethylene with vinyl acetate and mixtures thereof.

The tyre according to any one of the preceding claims wherein said self-supporting thermoplastic film has one or more of the following parameters:

• a) a load for elongation at break greater than 15 MPa, preferably greater than 20 MPa and/or a load for 5% elongation greater than 6 MPa, preferably greater than 8 MPa, more preferably comprised between 9 and 16 MPa, evaluated according to ASTM D882 on a sample with 12.57 mm width deformed at the speed of 500 mm/min at 23° C.;
• b) an elongation at break (AR) greater than 100% in the longitudinal direction, preferably greater than 150%, more preferably equal to or greater than 200%, evaluated according to ASTM D882 on a sample with 12.57 mm width deformed at the speed of 500 mm/min at 23° C.;
• c) a residual elastic force per linear centimetre of width of the film, about 5 minutes after reaching 50% deformation, that is generally less than 3.6 N/cm, preferably less than 3.0 N/cm, more preferably less than 2.8 N/cm, preferably comprised between 2.75 and 1.75 N/cm.

The tyre according to any one of the preceding claims, wherein said self-supporting thermoplastic film, before shaping, has a thickness less than 100 μm, preferably less than 50 μm, more preferably less than 40 μm or 30 μm.

The tyre according to any one of the preceding claims, wherein said sealing composition layer, before shaping, has a thickness less than 8 mm, preferably less than 7 mm, more preferably less than 6 mm.

The tyre according to any one of the preceding claims wherein the sealing composition comprises one or more plasticisers in an overall quantity of less than 200 phr, more preferably less than 100 phr, still more preferably less than 80 phr.

A sealing composite (12) for tyres comprising at least

• a self-supporting thermoplastic film (11) comprising at least 50% by weight with respect to the weight of the film itself of at least one or more polyolefins, wherein the at least one polyolefin is characterised by a fluidity index (MFI) less than 4, preferably less than 2, more preferably less than 1.5, still more preferably less than 1 gram per 10 minutes evaluated according to ASTM D1238 at 190° C./2.16 Kg), and
• a sealing composition layer (10) associated with and supported by said self-supporting thermoplastic film (11).