초록 ▼

A method of selectively controlling the self-sealing ability of a tire obtained by application of a sealing assembly on a drum and subsequent formation thereon of a precursor of a green tire inclusive of liner and carcass, followed by shaping, curing and molding. The sealing assembly includes: a sel

A method of selectively controlling the self-sealing ability of a tire obtained by application of a sealing assembly on a drum and subsequent formation thereon of a precursor of a green tire inclusive of liner and carcass, followed by shaping, curing and molding. The sealing assembly includes: a self-supporting thermoplastic film of polyamide or polyester and a layer of sealing material possessing viscoelasticity and stickiness features, which is associated with and supported by the self-supporting thermoplastic film. The sealing assembly is easily puncturable by a sharp-pointed element while it maintains such a deformability and stickiness that it helps in the transfer of the sealing material during ejection of the sharp-pointed element and limits the transferred material amount to such an extent that holes bigger than a predetermined value are not sealed.

대표청구항 ▼

1. A self-sealing tyre for vehicle wheels comprising: at least one carcass ply, a tread band applied at a radially external position to said carcass ply at a crown region, at least one liner applied at a radially internal position to said carcass ply, a sealing assembly applied at a position radiall

1. A self-sealing tyre for vehicle wheels comprising: at least one carcass ply, a tread band applied at a radially external position to said carcass ply at a crown region, at least one liner applied at a radially internal position to said carcass ply, a sealing assembly applied at a position radially internal to the liner and axially extending at least over the whole crown region of the tyre,wherein said sealing assembly comprises a self-supporting thermoplastic film of a polyamide or polyester material, a layer of sealing material associated with and supported by said self-supporting thermoplastic film,wherein the self-supporting thermoplastic film is radially internal to the layer of sealing material and said layer of sealing material is placed directly in contact with the liner,wherein said self-supporting thermoplastic film has a thickness ranging from greater than 5 μm to less than 25 μm,wherein the self-supporting thermoplastic film has such a stress relaxation relative to time, that in 10 seconds following achievement of an imposed elongation of 110% to 150%, the thermoplastic film shows a reduction of at least 20% of stress necessary for maintaining such an imposed elongation,wherein the layer of sealing material consists essentially of a synthetic or natural elastomer material, an optional process oil, an optional tackiness agent, an optional reinforcing filler, and an elastomeric block copolymer, wherein each of said synthetic or natural elastomer material is selected from the group consisting of cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, polybutadiene with a high 1,4-cis content, isoprene/isobutene copolymers, halogenated isoprene/isobutene copolymers, 1,3-butadiene/acrylonitrile copolymers, stirene/1,3-butadiene copolymers, stirene/isoprene/1,3-butadiene copolymers, stirene/1,3-butadiene/acrylonitrile copolymers, and mixtures thereof, andwherein said sealing layer has a maximum thickness less than about 6 mm. 2. The tyre as claimed in claim 1, wherein said self-supporting thermoplastic film comprises a polyamide selected from: nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymer, nylon 6/66/610 copolymer, nylon MXD 6, nylon 6T, nylon 6/6T copolymer, nylon 66/PP copolymer, nylon 66/PPS copolymer, alone or in mixtures thereof. 3. The tyre as claimed in claim 1, wherein said self-supporting thermoplastic film comprises polyester selected from: polybutylene terephthalate, polyethylene terephthalate, polyethylene isophtalate, polybutylene terephthalate/tetramethylene glycol copolymer, polyethylene terephthalate/polyethylene isophtalate copolymer, polyarylate and polybutylene naphthalate. 4. The tyre as claimed in claim 1, wherein said self-supporting thermoplastic film has a resistance to puncturing less than about 30N. 5. The tyre as claimed in claim 1, wherein said self-supporting thermoplastic film has a resistance to puncturing less than about 15N. 6. The tyre as claimed in claim 1, wherein said layer of sealing material has a maximum thickness greater than about 2.5 mm. 7. The tyre as claimed in claim 1, wherein the sealing material consists essentially of: 40 phr to 80 phr of a synthetic or natural elastomer material;20 phr to 60 phr of an elastomeric block copolymer;40 phr to 60 phr of process oil;15 phr to 60 phr of at least one tackiness agent; and1 phr to 40 phr of at least one reinforcing filler. 8. The tyre as claimed in claim 7, wherein the elastomeric block copolymer is a stirene-butadiene elastomer. 9. The tyre as claimed in claim 1, comprising two elongated elements of elastomeric material each applied at a respective circumferential edge of the sealing assembly, wherein each elongated element of elastomeric material has an axially internal portion disposed radially internal to the sealing assembly and in contact with said sealing assembly and an axially external portion disposed in contact with the liner. 10. The tyre as claimed in claim 9, wherein the layer of sealing material has an axial extension greater than the axial extension of the self-supporting thermoplastic film and wherein each elongated element of elastomeric material is directly in contact with said layer of sealing material and said self-supporting thermoplastic film. 11. The tyre as claimed in claim 1, wherein the sealing material consists essentially of: 50 phr to 70 phr of said synthetic or natural elastomer material;30 phr to 50 phr of said elastomeric block copolymer;50 phr to 60 phr of process oil;20 phr to 40 phr of at least one tackiness agent; and5 phr to 30 phr of at least one reinforcing filler. 12. The tyre as claimed in claim 1, wherein the self-supporting thermoplastic film has an elongation at yield greater than 5%. 13. The tyre as claimed in claim 1, wherein the self-supporting thermoplastic film has a yield strength from 20 MPa to 60 MPa. 14. The tyre as claimed in claim 1, wherein the self-supporting thermoplastic film has an ultimate elongation greater than 70%. 15. The tyre as claimed in claim 1, wherein the self-supporting thermoplastic film has an ultimate tensile strength from 20 MPa to 150 MPa. 16. The tyre as claimed in claim 1, wherein the self-supporting thermoplastic film has such a stress relaxation relative to time that within 300 seconds following achievement of an imposed elongation of 110% to 150%, the thermoplastic film shows a reduction of at least 35% of stress necessary for maintaining such an imposed elongation.