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US-12617243-B2 - Self-sealing tyre for vehicle wheels

US12617243B2US 12617243 B2US12617243 B2US 12617243B2US-12617243-B2

Abstract

The present invention relates to a self-sealing tyre for vehicle wheels comprising at least one carcass ply ( 3 ), a tread band ( 7 ) applied in a radially external position with respect to said carcass ply in a crown portion, at least one liner ( 9 ) applied in a radially internal position with respect to said carcass ply, a sealing assembly ( 10, 11 ) applied in a radially internal position with respect to said liner and axially extending at least at a part of the crown portion; wherein said sealing assembly comprises a permanent self-supporting elastomeric layer ( 11 ) having an elongation modulus at 10% lower than 0.8 MPa, said self-supporting elastomeric layer being obtained by vulcanisation of an elastomeric compound having a Mooney ML(1+4) viscosity lower than 30, and a layer of sealing material ( 10 ) associated with and supported by said permanent self-supporting elastomeric layer; wherein said self-supporting elastomeric layer is radially internal to the layer of sealing material and said layer of sealing material is placed substantially in contact with said liner.

Inventors

  • Antonio SUSANNA
  • Raffaella Donetti
  • Thomas HANEL

Assignees

  • PIRELLI TYRE S.P.A.

Dates

Publication Date
20260505
Application Date
20220429
Priority Date
20210430

Claims (18)

  1. 1 . A self-sealing tyre for vehicle wheels comprising: at least one carcass ply, a tread band applied in a radially external position with respect to the carcass ply in a crown portion, at least one liner applied in a radially internal position with respect to the carcass ply, a sealing assembly applied in a radially internal position with respect to the liner and axially extending at least at a part of the crown portion; wherein the sealing assembly comprises a permanent self-supporting elastomeric layer having an elongation modulus at 10% lower than 0.8 MPa, the self-supporting elastomeric layer comprises, before vulcanization, a vulcanisable elastomeric compound, comprising 100 phr of at least one natural or synthetic diene elastomeric polymer selected from the group consisting of natural or synthetic cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, non-halogenated isoprene/isobutene copolymers, 1,3-butadiene/acrylonitrile copolymers, styrene/1,3-butadiene copolymers, styrene/isoprene/1,3-butadiene copolymers, styrene/1,3-butadiene/acrylonitrile copolymers, and mixtures thereof, and having a Mooney ML(1+4) viscosity lower than 30, when measured at 100° C., and a layer of sealing material associated with and supported by the permanent self-supporting elastomeric layer; wherein the self-supporting elastomeric layer is radially internal to the layer of sealing material and the layer of sealing material is placed substantially in contact with the liner.
  2. 2 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has an elongation modulus at 10% lower than 0.6 MPa.
  3. 3 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has an elongation modulus at 10% higher than 0.2 MPa.
  4. 4 . The tyre according to claim 1 , wherein the compound has a Mooney ML(1+4) viscosity lower than 25, when measured at 100° C.
  5. 5 . The tyre according to claim 1 , wherein the compound has a Mooney ML(1+4) viscosity higher than 15, when measured at 100° C.
  6. 6 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has a thickness lower than 2 mm.
  7. 7 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has a thickness higher than 0.1 mm.
  8. 8 . The tyre according to claim 1 , wherein the layer of sealing material has a thickness higher than about 2.0 mm and lower than about 6.0 mm.
  9. 9 . The tyre according to claim 1 , wherein the sealing assembly axially extends for at least 60% of the crown portion of the tyre.
  10. 10 . The tyre according to claim 9 , wherein the sealing assembly axially extends for at least the entire crown portion of the tyre.
  11. 11 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has an elongation modulus at 10% lower than 0.5 MPa.
  12. 12 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has an elongation modulus at 10% higher than 0.3 MPa.
  13. 13 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has a thickness lower than 1 mm.
  14. 14 . The tyre according to claim 1 , wherein the self-supporting elastomeric layer has a thickness higher than 0.2 mm.
  15. 15 . A multilayered ribbon-like composite comprising a sealing assembly, and a removable protective film, wherein the sealing assembly comprises a permanent self-supporting elastomeric layer having an elongation modulus at 10% lower than 0.8 MPa, the self-supporting elastomeric layer comprises, before vulcanization, a vulcanisable elastomeric compound comprising 100 phr of at least one natural or synthetic diene elastomeric polymer selected from the group consisting of natural or synthetic cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, non-halogenated isoprene/isobutene copolymers, 1,3-butadiene/acrylonitrile copolymers, styrene/1,3-butadiene copolymers, styrene/isoprene/1,3-butadiene copolymers, styrene/1,3-butadiene/acrylonitrile copolymers, and mixtures thereof, and having a Mooney ML(1+4) viscosity lower than 30, when measured at 100° C., and a layer of sealing material having a first and a second opposite main surface, wherein the layer of sealing material is associated with and supported by the self-supporting elastomeric layer, at the level of the first surface, and wherein the removable protective film is placed in contact with the second surface of the sealing material.
  16. 16 . The composite according to claim 15 , wherein the removable protective film has a thickness lower than 100 μm.
  17. 17 . The composite according to claim 15 wherein the removable protective film comprises a polymeric material chosen from polyesters, polyamides, polycarbonates, polyvinyl chlorides, and fluorinated polyolefins.
  18. 18 . The composite according to claim 15 , wherein the removable protective film has a thickness lower than 50 μm.

Description

This application is a national stage entry application under 35 U.S.C. § 371 of International Application No. PCT/IB2022/053984, filed on Apr. 29, 2022, and claims priority to Italian Application No. 102021000010973, filed Apr. 30, 2021; the contents of each application is incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present invention relates to a self-sealing tyre for vehicle wheels, optionally also comprising a noise reducing element. Self-sealing tyres for vehicle wheels are able to delay or prevent the loss of air and the consequent deflation due to a puncture caused by a sharp object such as a nail and/or screw. BACKGROUND ART A self-sealing tyre comprises at least one layer of sealing elastomeric material which can adhere to the sharp object that punctures the tyre. The sealing polymeric material is made so as to be dragged inside the hole when the sharp object is ejected or removed, thereby sealing the hole itself and preventing air escape from the tyre. The sealing material inside the finished tyre (moulded and vulcanised), even though it has a certain elasticity, is deformable and tacky. In the manufacturing process of a self-sealing tyre, the sealing material may be deposited on the radially innermost wall of the already vulcanised tyre, as described for example in U.S. Pat. No. 4,418,093, or it may be applied during the assembly of the green and vulcanised tyre together with the other components. In the latter case, however, due to the tacky and scarcely rigid nature of the sealing material, handling and transport difficulties are encountered. To overcome these drawbacks, protective and support layers have been introduced, on which the sealing material is deposited in a uniform layer. Such layers, when arranged as radially innermost layer in the green tyre, facilitate the manufacture of the tyre, preventing any undesired contact of the material with itself, with the handling and assembly equipment and with the other components of the tyre, such as described for example in WO2011064698 in the name of the Applicant. Furthermore, the aforesaid layers also perform a support function for the sealing material which, by its nature, is not very rigid, allowing it to be transported and handled on the plants. Therefore, said layers are also defined as self-supporting layers. The self-supporting protective layer can be temporary and be removed after vulcanisation, as described for example in US2009/0084482, or permanent as it can remain in the final structure of the tyre, contributing to varying degrees to the sealing of the holes, as occurs for example in WO2011064698 in the name of the Applicant. The self-supporting protective layers used in the industry for this purpose are of various nature and thickness. US2009/0084482 discloses a removable protective layer of nylon or nylon and rubber compounds. The layer is generally removed after vulcanisation and is therefore no longer present in the finished tyre. Document EP1435301 describes a self-sealing tyre obtained by arranging an elastomeric composition comprising poly-isobutylene and peroxides at an internal surface of a non-vulcanised tyre. In one embodiment, a protective layer of thermoplastic resin, consisting predominantly of nylon 11, is disposed on a side radially internal to the sealing layer. The thickness of the layer is 0.1 mm. The elastomeric composition is heated during the vulcanisation of the tyre, causing a decomposition reaction of the polyisobutylene and obtaining an elastomeric sealing layer. Document US2012/0180923 relates to self-sealing tyres in which the sealing material layer is protected by a removable thermoplastic layer consisting of a block polymer, comprising hard blocks of polyamides and soft blocks of polyethers or copolymers of polyethers/polyesters (Pebax®). The protective layer prevents the sealing layer from sticking to the drum during assembly and subsequently to the vulcanisation membrane. Document US2012/234449 describes a self-sealing tyre in which the permanent protective layer is based on a chlorinated thermoplastic polymer (PVC, PVDC) and high molecular weight plasticising agents. Document WO2011064698 describes self-sealing tyres which allow selective sealing of holes with a diameter smaller than a predetermined value, achieved by virtue of a particular sealing assembly. Said assembly comprises a permanent protective layer in polyamide or polyester—arranged at least in the crown portion thereof so as to be radially more internal in the tyre—and a layer of sealing material, placed directly on the protective layer so as to result, in the tyre, in a radially outermost position with respect to the protective layer. This sealing assembly has excellent performance, both in the initial sealing step at the time of perforation and when the sharp object is expelled, by virtue of the cooperation between the thin protective layer and the sealing material. The particular sealing assembly allows t