Self-sealing tire for vehicle wheels

Abstract

The present invention relates to a self-sealing tire for vehicle wheels, comprising: at least one carcass ply; a tread band applied in a radially external position with respect to said carcass ply in a crown portion; at least one liner applied in a radially internal position with respect to said carcass ply; a sealing assembly applied in a radially internal position with respect to said liner and extending axially at least on a portion of the crown portion; wherein said sealing assembly comprises a permanent multilayer self-supporting film comprising at least two outer polyamide layers and at least one inner polyolefin layer, wherein the residual relaxation strength of said permanent multilayer self-supporting film is between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa, and a sealing material layer associated with and supported by said permanent multilayer self-supporting film; wherein said permanent multilayer self-supporting film is located radially inside said sealing material layer and said sealing material layer is placed in substantial contact with said liner.

Description

Technical Field

[0001] This invention relates to a self-sealing tire for vehicle wheels, which optionally further includes noise reduction elements. The self-sealing tire for vehicle wheels can delay or prevent air loss and subsequent deflation caused by punctures from sharp objects such as nails and / or screws. Background Technology

[0002] Self-sealing tires include at least one layer of sealing elastomer material that adheres to a sharp object that punctures the tire. The sealing polymer material is dragged into the puncture when the sharp object is ejected or removed, thereby sealing the puncture itself and preventing air from escaping from the tire. The sealing material inside the finished tire (molded and vulcanized) is deformable and adhesive, even if it possesses some elasticity.

[0003] In the manufacturing process of self-sealing tires, sealing material can be deposited on the innermost radial sidewall of the vulcanized tire, as described, for example, in US4418093, or the sealing material can be applied during the assembly of the raw tire and the vulcanized tire with other components. However, in the latter case, difficulties in handling and transportation arise due to the sticky and almost non-rigid nature of the sealing material. To overcome these drawbacks, protective and support layers have been introduced on which the sealing material is deposited in a uniform layer. When arranged as the innermost radial layer in a raw tire, these layers facilitate tire manufacturing by preventing any undesirable contact between the material and itself, between the material and handling and assembly equipment, and between the material and other components of the tire, as described in WO2011064698 under the applicant's name.

[0004] In addition, these layers also support the sealing material, which, due to its properties, has low stiffness, thus allowing it to be transported and handled in the factory. Therefore, these layers are also referred to as self-supporting layers.

[0005] The self-supporting protective layer can be temporary and removed after vulcanization, as described, for example, in US2009 / 0084482, or permanent, as it can remain in the final structure of the tire, as occurred, for example, in WO2011064698 under the applicant's name.

[0006] Self-supporting protective layers used in industry for this purpose have various properties and thicknesses.

[0007] US2009 / 0084482 describes a removable protective layer of nylon or a nylon and rubber compound. This protective layer is typically removed after vulcanization and is therefore no longer present in the finished tire.

[0008] Document EP1435301 describes a self-sealing tire obtained by disposing of an elastomer composition comprising polyisobutylene and peroxide on the inner surface of an uncured tire. In one embodiment, a thermoplastic resin protective layer, primarily composed of nylon 11, is disposed radially inside the sealing layer. The thickness of this protective layer is 0.1 mm. The elastomer composition is heated during tire curing, resulting in a decomposition reaction of the polyisobutylene and obtaining the elastomer sealing layer.

[0009] Document US2012 / 0180923 relates to self-sealing tires in which the sealing material layer is protected by a removable thermoplastic layer composed of a block polymer comprising rigid polyamide blocks and soft polyether or polyether / polyester copolymer (Pebax®) blocks. The protective layer prevents the sealing layer from sticking to the drum during assembly and subsequently to the vulcanized film.

[0010] Document US2012 / 234449 describes a self-sealing tire in which a permanent protective layer is based on chlorinated thermoplastic polymers (PVC, PVDC) and high molecular weight plasticizers.

[0011] Document WO2011064698 describes a self-sealing tire that allows selective sealing of orifices with diameters smaller than a predetermined value via a specific sealing assembly. The sealing assembly includes a permanent protective layer of polyamide or polyester and a sealing material layer, the permanent protective layer being disposed at least in the crown portion of the tire to be radially inner within the tire, and the sealing material layer being placed directly on the protective layer to be radially outermost within the tire relative to the protective layer.

[0012] Thanks to the synergy between the thin protective layer and the sealing material, this sealing assembly exhibits excellent performance in the initial sealing phase during puncture and when sharp objects are expelled. Certain sealing assemblies allow for the sealing of punctures under maximum safety conditions, selectively sealing only holes smaller than a predetermined size that do not pose a risk of damaging the tire structure. Summary of the Invention

[0013] According to WO2011064698, self-sealing tires with sealing components including a protective layer of polyamide or polyester are achieving considerable commercial success because they optimally perform selective sealing functions, thereby allowing users to drive safely.

[0014] However, the applicant has observed that protective layers based on polyamide or polyester make it more difficult to recycle tires at the end of their life and / or to recycle semi-finished products including sealing compounds, as these layers are difficult to remove from the sealing compounds.

[0015] Therefore, the applicant has conducted further research aimed at further improving the safety and ecological sustainability of these tires.

[0016] The self-sealing tires we aim to manufacture should, in addition to allowing for easy recycling, provide a sealing capability that is at least considerably (if not improved) comparable to existing systems. Furthermore, during the manufacture of the raw tire, the sealing assembly should possess sufficient self-support to allow for storage of the semi-finished product in the drum and easy unwinding from the drum itself, facilitating the transport of the web. The sealing assembly should engage in a simple and stable manner, possess sufficient deformability to prevent tearing during the expansion step on the build drum, and not elastically return to its original state at the end of the process, thus preventing instability of the raw material and / or detachment of the sealing material from the protective layer or liner. Finally, it should also possess heat resistance that prevents damage during vulcanization and molding.

[0017] In addition, the applicant realized the need for tires that were not too noisy in addition to being self-sealing, and thus conducted research on the production of self-sealing and sound-insulating tires. It was found that a simple combination of a self-sealing system (i.e., a sealing composition with a self-supporting layer) and a noise-reducing element (e.g., made of foam material) did not achieve the desired sealing effect.

[0018] Specifically, the applicant has implemented a tire comprising a sealing system consisting of a layer of sealing elastomer composition applied to the innermost surface of the tire (i.e., the inner surface of the liner), a self-supporting polyamide layer according to WO2011064698, and sound-absorbing polyurethane foam adhered to the layer. This tire sometimes fails to achieve the desired sealing performance. In fact, in dynamic sealing tests, it has been observed that conventional noise-reducing elements interfere with the sealing of perforations.

[0019] The applicant, not wishing to be bound by any explanatory theory, argues that the fracture of the self-supporting polyamide layer caused by puncture leads to contact between the sealing material and the porous material of the noise-reducing element. This, in turn, prevents or at least slows the flow of the sealing material toward the pores, exacerbating the inherent sealant retention of the polyamide. The applicant further argues that the rupture of both the self-supporting polyamide layer and the porous material layer caused by puncture generates fragments of polyamide and porous material. These fragments interfere with the sealing of the pores, inducing the formation of microchannels through which pressurized air contained within the tire can continue to escape.

[0020] Despite numerous limitations imposed by the defects encountered and the lack of prior art teachings, the applicant has found it possible to manufacture a self-sealing tire with a sealing assembly comprising at least two polyamide outer layers and at least one polyolefin inner layer, and having a residual relaxation strength between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa, which unexpectedly exhibits enhanced sealing performance. This results in a reduction in the amount and thickness of sealing material used in the tire while maintaining the same sealing performance, and significant cost savings.

[0021] Furthermore, the applicant has identified no particular manufacturing issues with the novel self-sealing tire, such as instability of the raw semi-finished product, weak joints, or detachment of the sealing material. In addition, the use of polyolefin in the self-supporting layer improves the recyclability of the semi-finished product and / or the tire at the end of its life, significantly improving industrial processes and sustainability.

[0022] Therefore, this self-sealing tire includes a sealing assembly comprising a layer of sealing material associated with a permanent multilayer self-supporting membrane.

[0023] More specifically, according to a first aspect, the present invention relates to a self-sealing tire for a vehicle wheel, the self-sealing tire comprising:

[0024] At least one carcass ply,

[0025] A tread band, which is applied in the crown portion at a radially outer position relative to the carcass ply.

[0026] At least one liner, said liner being applied at a radially inward position relative to the carcass ply, and

[0027] A sealing assembly, which is applied at a radially inward position relative to the liner and extends axially over at least a portion of the crown portion;

[0028] The sealing assembly includes a permanent multilayer self-supporting membrane and a sealing material layer. The multilayer self-supporting membrane includes at least two polyamide outer layers and at least one polyolefin inner layer. The residual relaxation strength of the permanent multilayer self-supporting membrane is between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa. The sealing material layer is associated with and supported by the permanent multilayer self-supporting membrane.

[0029] The permanent multilayer self-supporting membrane is located radially inside the sealing material layer, and the sealing material layer is positioned to substantially contact the liner.

[0030] The tensile properties and thickness of the permanent multilayer self-supporting membrane, along with the viscoelastic and viscous properties and thickness arrangement of the sealing material, enable the sealing assembly to respond to the withdrawal of puncture elements and to provide an effective seal in relation to tire size and intended use.

[0031] According to a second aspect, the present invention relates to a multilayer strip-shaped composite comprising a sealing component and a removable protective film, wherein the sealing component comprises:

[0032] A permanent multilayer self-supporting membrane and a sealing material layer, wherein the permanent multilayer self-supporting membrane comprises at least two polyamide outer layers and at least one polyolefin inner layer, wherein the residual relaxation strength of the permanent multilayer self-supporting membrane is between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa, and the sealing material layer has substantially opposing first and second surfaces, the sealing material layer being associated with and supported by the permanent multilayer self-supporting membrane, and

[0033] The removable protective film is positioned to contact the second surface of the sealing material layer. Attached Figure Description

[0034] The accompanying drawings are provided for illustrative purposes only and not for limitation.

[0035] Figure 1 A radial half-section of a self-sealing tire for a vehicle wheel according to the present invention is schematically shown, the self-sealing tire including a sealing assembly;

[0036] Figure 2 It shows the purpose of forming Figure 1 A cross-section of the sealing assembly, which is part of a self-sealing tire;

[0037] Figure 3 It includes Figure 2 A cross-sectional view of a multilayer sealing compound comprising sealing components and a removable protective film.

[0038] Figure 4 A cross-section of a multilayer self-supporting membrane according to a preferred embodiment of the present invention is schematically shown, comprising a polyethylene inner layer 11b and two polyamide outer layers (11c and 11c').

[0039] Figure 5 A radial half-section of a sound-insulating self-sealing tire for a vehicle wheel is schematically shown, the sound-insulating self-sealing tire including a sealing assembly and a noise reduction element according to the invention.

[0040] Figure 6A Cartesian plot of force (MPa) versus time (s) is shown, which illustrates the relaxation curves as described in Example 2 for a multilayer self-supporting membrane used in a sealing assembly 2 comprising two polyamide outer layers and a polyethylene inner layer.

[0041] Figure 7 A Cartesian plot of force (MPa) versus time (s) is shown, which illustrates the relaxation curves as described in Example 2 for the self-supporting layer used in sealing assembly 1 made of Filmon CXS18 polyamide. Detailed Implementation

[0042] definition

[0043] For the purposes of this specification and the following claims, the term "phr" (abbreviation for parts per hundred parts of rubber) refers to the number of parts by weight of a given elastomeric composition component relative to 100 parts by weight of an elastomeric polymer without any incremental oil.

[0044] The term "permanent self-supporting elastomer layer" refers to an elastomer layer that is able to support the weight of the sealing material during tire construction and remain in the final tire structure after vulcanization.

[0045] The term “residual relaxation strength” refers to the residual force observed after 300 seconds on a multilayer self-supporting membrane specimen using the method described in Example 2.

[0046] The term "elastomer composition" refers to a composition comprising at least one diene elastomer polymer and one or more additives, which, through mixing and possibly heating, provides an elastomer compound suitable for use in tires and their components.

[0047] The components of an elastomer composition are typically not introduced into the mixer simultaneously, but rather added sequentially. In particular, vulcanizing additives such as vulcanizing agents and, optionally, accelerators and retarders, are usually added in a downstream step relative to the introduction and processing of all other components.

[0048] In the final vulcanizable elastomer compound, the individual components of the elastomer composition can be altered or modified entirely or partially on an immediate basis, no longer individually traceable, due to interactions with other components and / or thermal and / or mechanical processing. The term "elastomer composition" as used herein refers to the collection of all components used in the preparation of the elastomer compound, regardless of whether they are actually present simultaneously, introduced sequentially, or subsequently traceable in the elastomer compound or in the finished tire.

[0049] The term "elastomeric polymer" refers to a natural or synthetic polymer that, after vulcanization, can be repeatedly stretched to at least twice its original length at room temperature and returns substantially immediately and forcefully to its original length after the tensile strength is removed (according to the definition of rubber in ASTM D1566-11 standard terminology).

[0050] The term "diene polymer" refers to a polymer or copolymer derived from the polymerization of one or more different monomers, wherein at least one of the monomers is a conjugated diene (conjugated diene).

[0051] The term "elastomer compound" refers to a compound obtained by mixing at least one elastomer polymer with at least one additive commonly used in the preparation of tire compounds and optionally heating the mixture.

[0052] The term "expandable vulcanized elastomer compound" refers to materials that can be obtained by vulcanizing vulcanizable and expandable elastomer compounds.

[0053] The term "raw" refers to materials, compounds, components, parts, or tires that have not yet been vulcanized.

[0054] The term "vulcanization" refers to the crosslinking reaction in natural or synthetic rubber induced by a sulfur-based crosslinking agent.

[0055] The term "vulcanizing agent" refers to a product that transforms natural or synthetic rubber into an elastic and durable material by forming a three-dimensional network of intermolecular and intramolecular bonds. Typical vulcanizing agents are sulfur-based compounds, such as elemental sulfur, polymeric sulfur, sulfur donors (such as bis[(trialkyloxysilyl)propyl] polysulfides), thiuram, dithiodimorpholine, and caprolactam-disulfides.

[0056] The term "vulcanization accelerator" refers to compounds that can reduce the duration and / or operating temperature of the vulcanization process, such as TBBS, general sulfonamides, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and sulfur donors (such as thiuram).

[0057] The term "vulcanization activator" refers to a product that can further promote vulcanization, enabling it to occur in a shorter time and possibly at a lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0058] The term "vulcanization retarder" refers to a product that can delay the onset of the vulcanization reaction and / or inhibit unwanted secondary reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0059] The term "vulcanizing package" refers to a vulcanizing agent and one or more vulcanizing additives selected from vulcanization activators, vulcanization accelerators and vulcanization retarders.

[0060] The term "reinforcing filler" refers to reinforcing materials commonly used in this field to improve the mechanical properties of tire rubber, preferably selected from carbon black, conventional silica (e.g., silica from sand precipitated with strong acid, preferably amorphous silica), diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fibers, and mixtures thereof.

[0061] Detailed description of the invention

[0062] The self-sealing tire of the present invention may exhibit one or more of the following preferred features in at least one of the above aspects.

[0063] Advantageously, the sealing assembly is placed at the innermost radial position of the tire to cover at least 60% of its axial (or lateral) extension in the entire circumferentially extending portion of the tire crown.

[0064] Preferably, the sealing components extend symmetrically from both sides of the equatorial plane of the tire.

[0065] Preferably, the sealing assembly extends axially along at least the entire crown portion of the tire.

[0066] Alternatively, the sealing assembly preferably extends beyond the crown portion into the bead structure in the areas of the edges and sidewalls.

[0067] The "crown portion" of a tire refers to the part of the tire structure corresponding to the area where the tread band exists. As an indicator, the axial extension of the crown portion can be identified by the distance between two segments perpendicular to the tread band, starting from the edge of the tread band itself.

[0068] According to the present invention, the sealing assembly includes a permanent multilayer self-supporting membrane and a sealing material layer, the permanent multilayer self-supporting membrane comprising at least two polyamide outer layers and at least one polyolefin inner layer, having a residual relaxation strength between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa, the sealing material layer being associated with and supported by the permanent multilayer self-supporting membrane.

[0069] Advantageously, the permanent multilayer self-supporting membrane can exhibit residual relaxation strength of any value between 5 MPa and 15 MPa, such as 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa and 15 MPa, including one or two decimal values ​​between the above values.

[0070] According to one aspect of the invention, the sealing assembly comprises a permanent multilayer self-supporting membrane having a tensile strength equal to or less than 50 MPa, preferably equal to or less than 40 MPa.

[0071] According to one aspect of the invention, the sealing assembly comprises a permanent multilayer self-supporting membrane having a tensile strength equal to or greater than 10 MPa, preferably equal to or greater than 20 MPa.

[0072] Advantageously, the permanent multilayer self-supporting membrane can exhibit tensile strengths of any value between 20 MPa and 40 MPa, such as 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, 30 MPa, 31 MPa, 32 MPa, 33 MPa, 34 MPa, 35 MPa, 36 MPa, 37 MPa, 38 MPa, 39 MPa, and 40 MPa, including one or two decimal values ​​between the above values.

[0073] According to one aspect of the invention, the sealing assembly comprises a permanent multilayer self-supporting membrane having a 10% strain strength (Ca0.1) equal to or less than 40 MPa, preferably equal to or less than 30 MPa.

[0074] According to one aspect of the invention, the sealing assembly comprises a permanent multilayer self-supporting membrane having a strain strength (Ca0.1) of 5 MPa or greater, preferably 10 MPa or greater.

[0075] Advantageously, the permanent multilayer self-supporting membrane can exhibit tensile strengths of any value between 10 MPa and 30 MPa, such as 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, and 30 MPa, including one or two decimal values ​​between the aforementioned values.

[0076] For the purposes of this invention, the strength and fracture characteristics, as well as Ca0.1, are evaluated by tensile testing in the longitudinal direction of the machine exit (MD) according to ASTM D882.

[0077] According to one aspect of the invention, the sealing assembly comprises a permanent multilayer self-supporting membrane having a weight per unit area of ​​5 g / m² as measured according to ISO 2286-2:2016. 2 Up to 30g / m 2 Between, preferably between 10 g / m 2 Up to 25g / m 2 Between, more preferably between 13g / m 2 Up to 20g / m 2 between.

[0078] The composition and thickness of the sealing material layer, as well as the thickness of the multilayer self-supporting membrane, are preferably selected within the aforementioned characteristic range in order to provide optimal tack and viscoelastic properties for any use conditions of the tire itself, in relation to the type of tire to be produced.

[0079] In fact, the applicant has noted that the invention is applicable to tires for four-wheeled vehicles intended for road use, such as tires suitable for equipping medium and high displacement cars used for transporting passengers (with cord sizes of 195mm to 245mm), but this does not preclude the invention from being applicable to small car tires or high-performance tires (HP high-performance to UHP ultra-high-performance), wherein the cord size is, for example, 145mm to 355mm. Where necessary, the invention can be applied to tires of different vehicles, such as motorcycle tires.

[0080] Preferably, in the finished tire, the thickness of the multilayer self-supporting film is equal to or less than 50 μm, and more preferably equal to or less than about 40 μm.

[0081] Preferably, in the finished tire, the thickness of the multilayer self-supporting film is equal to or greater than 1 μm, and more preferably equal to or greater than about 5 μm.

[0082] Advantageously, in the finished tire, the thickness of the multilayer self-supporting film is between 5 μm and 40 μm, preferably between about 10 μm and about 30 μm, and more preferably 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0083] The thickness of each polyamide layer in the permanent multilayer self-supporting film is preferably between 10% and 40% of the total thickness of the multilayer self-supporting film, more preferably between 15% and 35%, and even more preferably between 20% and 30%.

[0084] The thickness of each polyolefin layer in the permanent multilayer self-supporting membrane is preferably between 20% and 80% of the total thickness of the multilayer self-supporting membrane, more preferably between 30% and 70%, and even more preferably between 40% and 60%.

[0085] Preferably, in the finished tire, the thickness of the sealing material layer is greater than about 2.0 mm and less than 6.0 mm.

[0086] Preferably, the axial extension of the sealing material layer is smaller than that of the multilayer self-supporting membrane, such that the axially opposite edges of the multilayer self-supporting membrane allow the sealing assembly to adhere laterally to the liner, thereby surrounding and laterally holding the sealing material.

[0087] During tire molding and vulcanization, as the pressure within the mold presses the tire carcass against the inner wall of the mold itself, the axially opposite edges of the multilayer self-supporting membrane retain the sealing material.

[0088] According to the present invention, the sealing assembly comprises a permanent multilayer self-supporting membrane comprising at least two polyamide outer layers and at least one polyolefin inner layer.

[0089] The total amount of polyamide distributed on at least two polyamide outer layers in the multilayer self-supporting film is between 20% w / w and 80% w / w, preferably between 30% w / w and 70% w / w, and more preferably between 40% w / w and 60% w / w.

[0090] The total amount of polyolefin distributed on at least one polyolefin inner layer in the multilayer self-supporting membrane is between 20% w / w and 80% w / w, preferably between 30% w / w and 70% w / w, and more preferably between 40% w / w and 60% w / w.

[0091] polyamide

[0092] As used herein, the term "polyamide" refers to any polymer characterized by an amide group -CO-NH-, which is derived from the condensation polymerization of a dicarboxylic acid and a diamine or from the polymerization of a lactam.

[0093] Preferably, the multilayer self-supporting membrane according to the present invention comprises, alone or in combination, a polyamide selected from the following: nylon 6, nylon 6.6, nylon 4.6, nylon 4.10, nylon 10.10, nylon 11, nylon 12, nylon 6.10, nylon 6.12, nylon 6 / 6.6 copolymer, nylon 6 / 6.6 / 6.10 copolymer, nylon MXD 6, nylon 6T, nylon 6 / 6T copolymer, nylon 6.6 / PP copolymer, and nylon 6.6 / PPS copolymer.

[0094] Nylon 6 is polymerized from caprolactam. It possesses good mechanical properties, abrasion resistance, and heat resistance. Nylon 6.6 is polymerized from adipic acid and hexamethylenediamine. It is one of the most common nylons and offers excellent heat resistance, mechanical properties, and good dimensional stability. Nylon 4.6 is polymerized from 1,4-diaminobutane and adipic acid. It possesses good heat resistance, mechanical properties, and high abrasion resistance. Nylon 11 is polymerized from undecane-11-lactam. It exhibits excellent chemical resistance and biocompatibility. Nylon 12 is polymerized from ω-aminolauric acid or laurolactam. It possesses excellent flexibility, chemical resistance, and moisture resistance. Nylon 6.10 is polymerized from sebacic acid and hexamethylenediamine. Nylon 6.12 is polymerized from dodecanoic acid and hexamethylenediamine. It offers a good balance between mechanical properties and flexibility. Nylon 6 / 66 is a copolymer of nylon 6 and nylon 6.6. It combines the mechanical properties of nylon 6 with the heat resistance and dimensional stability of nylon 6.6. Nylon 6T is polymerized from terephthalic acid and hexamethylenediamine. It is known for its heat resistance and chemical resistance and is used in industrial applications and flame-retardant materials.

[0095] The residual relaxation strength of the polyamide used in the sealing assembly according to the invention is preferably between 20 MPa and 60 MPa, more preferably between 30 MPa and 50 MPa, and even more preferably between 35 MPa and 45 MPa.

[0096] The tensile strength of the polyamide used in the sealing assembly according to the invention is preferably between 40 MPa and 80 MPa, more preferably between 50 MPa and 70 MPa, and even more preferably between 55 MPa and 65 MPa.

[0097] The 10% strain strength (Ca0.1) of the polyamide used in the sealing assembly according to the invention is preferably between 45 MPa and 85 MPa, more preferably between 55 MPa and 75 MPa, and even more preferably between 60 MPa and 70 MPa.

[0098] For the purposes of this invention, strength and fracture properties, as well as Ca0.1, are evaluated by a tensile test performed in the longitudinal direction at the machine exit (MD) according to ASTM D882 standard.

[0099] The polyamide used in the sealing assembly according to the invention preferably has a unit area weight of 5 g / m² as determined according to ISO 2286-2:2016. 2 Up to 30g / m 2 Between, preferably between 10 g / m 2 Up to 25g / m 2 More preferably between 14 g / m 2 Up to 20g / m 2 , .

[0100] Polyolefins

[0101] As used in this article, the term "polyolefin" refers to any thermoplastic polymer derived from the polymerization of unsaturated hydrocarbons containing ethylene or diene functional groups.

[0102] Specifically, the term polyolefin includes olefin homopolymers and copolymers, and mixtures thereof. Specific examples include ethylene, propylene, and butene homopolymers; ethylene-α-olefin, propylene-α-olefin, and butene-α-olefin copolymers; polymethylpentene; and modified polymers thereof.

[0103] Preferably, the multilayer self-supporting membrane according to the present invention comprises materials selected from ethylene, propylene, and C4-C. 20 α-olefins (preferably C4-C) 10 Polyolefins selected from homopolymers and copolymers of α-olefins and mixtures thereof, more preferably homopolymers and copolymers of ethylene and mixtures thereof.

[0104] Preferably, the polyolefin is polyethylene selected from ethylene homopolymer, copolymer of ethylene and propylene, copolymer of ethylene and C4-C8 α-olefin (e.g., butene and hexene), and copolymer of ethylene and vinyl acetate.

[0105] Advantageously, polyolefins are homopolymers of ethylene, commonly known as polyethylene (PE).

[0106] Polyethylene is typically classified according to its density, which is greater than or equal to 0.941 g / cm³. 3 When the density is [not specified], it is high-density polyethylene (HDPE), which has a density of 0.926 to 0.940 g / cm³. 3 Medium-density polyethylene (MDPE) has a density range of 0.915 to 0.925 g / cm³. 3 The density range is linear low-density polyethylene (LLDPE), which has a density of 0.910 to 0.940 g / cm³. 3 Low-density polyethylene (LDPE) has a density range of 0.880 to 0.915 g / cm³. 3 The density within the range is ultra-low density polyethylene (VLDPE).

[0107] Preferably, the polyethylene of the multilayer self-supporting membrane is linear low-density polyethylene (LLDPE), or low-density polyethylene (LDPE), or low-density polyethylene copolymerized with vinyl acetate (LDPE-EVA), or medium-density polyethylene (MDPE), or a mixture thereof.

[0108] Examples of suitable commercially available polyolefins are produced and sold by various manufacturers under different trademarks, such as Clearflex™ or Eraclene™ (Versalis SpA), Escorene™ (Exxon Mobil), Purell™ or Petrothene™ or Hostalen™ (LyondellBasell).

[0109] The polyolefin used in the sealant assembly according to the invention preferably has a residual relaxation strength of less than 10 MPa, a tensile strength of less than 30 MPa, and a 10% strain tensile strength of less than 15 MPa (Ca). 0.1 ).

[0110] For the purposes of this invention, strength and fracture properties, as well as Ca, are evaluated by a tensile test performed longitudinally at the machine exit (MD) according to ASTM D882 standard. 0.1 .

[0111] Other materials / layers

[0112] The permanent multilayer self-supporting membrane used in the sealant assembly according to the invention may include an additional layer comprising, alone or in combination, polymeric materials other than polyamides and polyolefins, such as polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), thermoplastic elastomer polyurethane (TPU), fluorinated polymers (such as polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), and ethylene tetrafluoroethylene (ETFE)), and vinyl polymers (such as ethylene vinyl acetate (EVA) and ethylene vinyl alcohol (EVOH)).

[0113] According to an embodiment of the invention, the additional layer may comprise up to 20% w / w, preferably up to 15% w / w, and more preferably up to 10% w / w, of the permanent multilayer self-supporting film used in the sealant assembly according to the invention.

[0114] The aforementioned polymeric material should preferably have a residual relaxation strength of less than 10 MPa, a tensile strength of less than 30 MPa, and a 10% strain tensile strength of less than 15 MPa (Ca). 0.1 ).

[0115] preparation

[0116] The permanent multilayer self-supporting membrane used in the sealing assembly according to the invention may comprise up to 15 layers, preferably up to 9 layers, and more preferably up to 5 layers, having different chemical compositions.

[0117] The permanent multilayer self-supporting membrane used in the sealing assembly according to the invention can be prepared by a blow molding process (also known as thin film blow molding) widely known in the art. This process is typically carried out according to the following steps.

[0118] 1. Material Extrusion: Each polymeric material constituting a layer in a multilayer film is melted separately in a different extruder. Each extruder may contain different polymeric materials with specific properties.

[0119] 2. Layer Combination: After melting, the different polymeric materials are extruded through an extruder and bonded together. In some cases, rollers or pressure rollers can be used to mechanically bond the layers together. Alternatively, co-extrusion can be used, in which the layers are melted together as they pass through the extruder.

[0120] 3. Bubble Formation: The molten multilayer tube travels through the circumference of the annular extruder, thereby forming plastic bubbles inside. Each layer contributes to the overall performance of the film.

[0121] 4. Cooling and Curing: An air jet or water circulation cooling system is used to cool the multilayer bubbles. This process cures the different polymer layers, resulting in a film composed of different but integrated materials.

[0122] 5. Performance Adjustment: The composition and thickness of each layer can be adjusted to achieve the desired performance in the finished film. Numerous parameters are available, including extrusion flow rate, extrusion ratio, extrusion speed, extruder geometry, and air pressure within the bubbles.

[0123] 6. Cutting and winding: Once the desired size and multi-layer structure are achieved, the film is cut from the plastic bubble and wound onto a roll.

[0124] The different layers of a multilayer self-supporting membrane can be co-crosslinked or non-co-crosslinked. Preferably, the different layers of the multilayer self-supporting membrane are co-crosslinked by methods known to those skilled in the art (such as radiation, peroxides, acid anhydrides, or ionomers).

[0125] Sealing material

[0126] For the purposes of this invention, the composition of the sealing material is not particularly limited: for example, the composition described in document WO2009143895 or document WO2013093608 under the applicant's name can be used.

[0127] As an example, sealing materials may include

[0128] (a) at least one unsaturated styrene thermoplastic elastomer;

[0129] (b) Optionally, at least one diene elastomer;

[0130] (c) At least one crosslinking agent;

[0131] (d) At least one thickener.

[0132] The sealing polymeric material comprises, for example, at least one unsaturated styrene thermoplastic elastomer at 20 to 100 phr; at least one synthetic or natural diene elastomer at 0 to 80 phr; at least one tackifier at 20 to 200 phr, preferably 30 to 150 phr; at least one crosslinking agent at 0.1 to 6 phr; a plasticizer (oil or liquid polymer) at 10 to 200 phr, preferably 20 to 60 phr; and at least one reinforcing filler at 1 to 40 phr, preferably 5 to 30 phr. According to a preferred embodiment, the sealing material may further comprise at least one homogenizing agent at about 1 to about 20 phr. In another embodiment, the sealing material may further comprise at least one plasticizer at 0.05 to 5 phr.

[0133] According to a preferred embodiment, the unsaturated styrene thermoplastic elastomer is a styrene polymer selected from styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / butadiene / isoprene / styrene (SBIS) block copolymers and mixtures thereof, optionally also comprising corresponding diblock thermoplastic elastomers, such as styrene-butadiene (SB) and styrene-isoprene (SI). Particularly preferred are styrene / isoprene / styrene block copolymers or mixtures of one or more unsaturated styrene thermoplastic elastomers comprising at least 50% styrene / isoprene / styrene block copolymers.

[0134] Preferably, the block copolymer has a styrene content of about 10% to about 30%, more preferably about 12% to about 18%.

[0135] Preferably, the "diblock" percentage of the block copolymer is less than 70%, and even more preferably less than 60%.

[0136] Preferably, the percentage of "diblock" is between 15% and 55%.

[0137] Diblock percentage refers to the percentage of block polymers consisting of only two segments (i.e., a polystyrene segment and an elastomer segment).

[0138] Although such "diblocks" are primarily present in block polymers consisting mainly of three segments (styrene-elastomer-styrene) and are considered impurities due to the incomplete efficiency of "living polymerization," the applicant believes that the presence of diblocks can be advantageously modulated to improve the quality of the sealing composition.

[0139] A higher percentage of diblocks is thought to correspond to greater viscosity of the sealant, but lower modulus and lower cohesion.

[0140] Particularly preferred are styrene / isoprene / styrene block copolymers, wherein the styrene content is equal to or less than 20%, more preferably between 14% and 20%.

[0141] These copolymers, for example, are based on the Europrene of Polimeri Europa. ® SOL T190, T9133, Vector from DexcoPolymers ® 4113, 4114, Kraton of Kraton ® The names D1111, D1112, and D1107J are for sale.

[0142] According to a preferred embodiment, the synthetic or natural diene elastomer included in the sealing material may be selected from those elastomer materials commonly used for crosslinking with sulfur or peroxides and particularly suitable for tire manufacturing, i.e., selected from elastomer polymers or copolymers having unsaturated chains having a glass transition temperature (Tg) generally below 20°C, preferably in the range of 0°C to 110°C. These polymers or copolymers may be of natural origin or obtained by solution polymerization, emulsion polymerization, or gas-phase polymerization of one or more conjugated dienes, optionally mixed with at least one comonomer selected from a monovinyl aromatic compound and / or a polar comonomer in an amount not exceeding 60% by weight. The conjugated diene generally contains 4 to 12 carbon atoms, preferably 4 to 8 carbon atoms, and may be, for example, selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene, or mixtures thereof. 1,3-Butadiene or isoprene are particularly preferred.

[0143] The polar comonomers that may be used may be selected, for example, from: vinylpyridine, vinylquinoline, acrylic acid and alkyl acrylates, nitrile or mixtures thereof, such as methacrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile or mixtures thereof.

[0144] Preferably, the synthetic or natural diene elastomer contained in the sealing material may be selected, for example, from: cis-1,4-polyisoprene (natural or synthetic rubber, preferably natural rubber), 3,4-polyisoprene, polybutadiene (especially high-content 1,4-cis polybutadiene), optional 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, or mixtures thereof.

[0145] The tackifiers advantageously used in this invention can be selected from hydrocarbon resins with a number average molecular weight between several hundred and several thousand and provide tack when the resin is mixed with natural or synthetic rubber.

[0146] Various types of synthetic resins can be used as resins. The number-average molecular weight (Mn) mentioned above can be measured according to techniques known in the art, such as by gel permeation chromatography (GPC). In particular, hydrocarbon resins, phenolic resins, carbon-based resins, xylene-based resins, and natural resins (such as rosin-based or terpene-based resins) can be used as tackifiers.

[0147] Examples of commercially available hydrocarbon resins include aromatic petroleum-based resins, such as PETCOAL manufactured by Tosoh Co., Ltd.; C5 / C9 hydrocarbon-based resins, such as PETROTACK manufactured by Tosoh Co.; and C5 hydrocarbon-based resins, such as Escorez. ® 1102 (manufactured by Exxon Mobil).

[0148] Examples of phenolic resins include resins having alkylphenol-formaldehyde groups and rosin-modified derivative resins, resins having alkylphenol-acetylene groups, and modified alkylphenol and terpene-phenol resins. Specific examples indicated by brand include commercial products such as RESINA SP-1068 (manufactured by SI GROUP Inc.), which is an octylphenol-formaldehyde resin; and KORESIN (manufactured by BASF), which is a p-t-butylphenol-acetylene resin.

[0149] Examples of carbon-based resins include indene-indene resins. Specific examples include commercial products represented by the following brands, such as NOVARES C resin (manufactured by RUTGERS CHEMICAL GmbH), which are synthetic indene-oxygen indene resins (e.g., NOVARES C10, C30, and C70).

[0150] Examples of natural resins are rosin resins and terpene resins, which can be used as is or modified: examples of these categories include DERCOLYTE rosin resin manufactured by DRT, and DERTOLINE, GRANOLITE, and HYDROGRAL resins derived from rosin acids manufactured by DRT.

[0151] Examples of xylene-based resins include xylene-formaldehyde resins.

[0152] The above adhesives can be used alone or in combination.

[0153] In the presence of compounds or peroxides containing zinc and fatty acids, a suitable crosslinking agent is sulfur or sulfur-containing molecules.

[0154] Examples of specific sulfur-containing molecules that can be used as crosslinking agents in sealing materials used to manufacture self-sealing tires are elemental sulfur, thiurams (such as tetraisobutylthiuram disulfide or tetrabenzylthiuram disulfide), or dithiophosphates (such as zinc dibutyl dithiophosphate), or dithiocarbamates (such as zinc dimethyl dithiocarbamate), together with zinc oxide or zinc-containing compounds, fatty acids and thioamides (such as Nt-butyl-2-benzothiazolylsulfonamide (TBBS) or N-cyclohexyl-2-benzothiazolylsulfonamide (CBS)), or thiazoles (such as 2,2'-dithiobis(benzothiazolyl) (MBTS)).

[0155] Specific examples of peroxides that can be used as crosslinking agents in sealing materials used to manufacture self-sealing tires are organic peroxides such as dimethyl peroxide (DCP), 2,5-dimethyl-2,5-di-t-butyl-peroxyhexane (DBPH), bis(2,4-dichlorobenzoyl)peroxide (DCBP), and di-t-butylperoxide.

[0156] Preferably, peroxide is used as a crosslinking agent, more preferably 2,5-dimethyl-2,5-di-t-butyl-peroxyhexane (DBPH).

[0157] A specific example of usable DBPH is a mixture of 45% DBPH with calcium carbonate and silica sold by Arkema under the trade name Luperox 101XL45.

[0158] The amount of peroxide is preferably in the range of about 0.1 phr to about 6 phr.

[0159] The presence of peroxides, sulfur, or other crosslinking agents allows for partial chemical crosslinking of the sealing composition during tire vulcanization, thereby improving the dynamic sealing properties of the sealing material layer.

[0160] At least one reinforcing filler may be advantageously added to the above-described sealing elastomer composition, typically in an amount from 0 phr to 120 phr, preferably from 10 phr to 50 phr. The reinforcing filler may be selected from those commonly used in crosslinked products (particularly tires), such as carbon black, silica, alumina, aluminosilicate, calcium carbonate, kaolin, or mixtures thereof. Carbon black, silica, and mixtures thereof are particularly preferred.

[0161] According to a preferred embodiment, the carbon black reinforcing filler can be selected from those having a density of not less than 20 μm. 2 Those fillers with a surface area of ​​ / g (as determined by statistical thickness surface area (STSA) according to ISO 18852:2005).

[0162] According to a second aspect of the invention, the composite comprises a sealing component as described above and a removable protective film covering the surface of the sealing material opposite to the surface to which the multilayer self-supporting film is bonded. This protective film maintains the integrity of the sealing material and prevents the sealing component from adhering to itself while being wound onto a spool or to machine parts during the unwinding step. The protective film is then typically removed before the cutting stage without compromising the integrity of the sealing material.

[0163] Typically, the thickness of the protective film is less than 100 μm, preferably less than 50 μm.

[0164] Preferably, the protective film is wider than the multilayer self-supporting film and also wider than the sealing material; more preferably, it is wider than the total width of the semi-finished product.

[0165] Preferably, the protective film comprises a polymeric material, more preferably composed of a polymeric material such as polyester, polyamide, polycarbonate, or polyvinyl chloride, which typically forms an anti-stick layer with silicone or fluorinated polymers, or the protective film is made of polytetrafluoroethylene, which does not require anti-stick treatment. Preferably, the protective film is made of polyester, more preferably of silicone-coated polyester (i.e., silicone-treated anti-stick polyester).

[0166] Noise reduction components

[0167] The self-sealing tire according to the invention preferably includes a noise reduction element applied to the radial inner surface of a multilayer self-supporting membrane.

[0168] The term "noise reduction element" refers to an element that has the ability to attenuate noise once associated with the radially inner surface of the tire, which is generated during use by a cavity (cavity noise) defined between the tire and the rim on which the tire is mounted.

[0169] This cavity noise is generated when the air within the internal annular chamber vibrates as the tire rolls on the road. This is because the air is cyclically compressed during the tread compression phase, generating sound waves that are amplified through resonance. The cavity noise is then transmitted through the rim, hub, suspension, and frame to the vehicle's passenger compartment and is perceived as very annoying by passengers.

[0170] The frequency at which air resonates within the tire chamber is inversely proportional to the tire's circumference and, among other factors, depends on the shape of the chamber itself and the nature and shape of the material lining it. Indicatively, the resonant frequency ranges from approximately 50 Hz to 400 Hz, and is typically around 180-220 Hz for passenger car tires with diameters ranging from approximately 600 mm to 800 mm.

[0171] The ability to attenuate chamber noise is typically imparted to an element by the type of material or the material used to manufacture the element and / or by the size of the element and / or by the number of elements inserted into the chamber. Such noise-reducing elements are typically composed of porous material strips or blocks, such as foamed polymeric materials, which effectively reduce noise and are compatible with use in tires.

[0172] During use, the noise reduction material inserted into the tire cavity is subjected to very significant mechanical and thermal stress.

[0173] In fact, during the rolling process, on the one hand, they are constantly stretched due to tire deformation, and on the other hand, they are heated to a temperature far higher than the ambient temperature due to the heat generated by the tread when used on the road.

[0174] Therefore, for specific applications, the noise reduction materials used typically exhibit good thermal and mechanical properties, so that they do not degrade and / or deform due to the combined effects of heat and stress.

[0175] Furthermore, since the air used to inflate tires may contain moisture, and this moisture may condense and be absorbed by the porous material of the noise-reducing element, resulting in reduced noise attenuation, the noise-reducing material typically has a low water absorption rate and is resistant to hydrolysis during use. Advantageously, the porous material of the noise-reducing element may undergo waterproofing and / or mildew-proofing treatments.

[0176] Preferably, the noise-reducing material is characterized by a water absorption rate of less than 6 kg / m³ according to UNI EN 12088 (RH > 95% - after 28 days). 2 More preferably less than 4 kg / m 2 Even better, less than 3 kg / m 2 .

[0177] Furthermore, since noise reduction materials must be easily deformable during driving to avoid peeling and must not affect driving performance (such as handling stability), these materials are preferably lightweight, low-density, and flexible.

[0178] Preferably, the density of the noise reduction material is no greater than 60 kg / m³. 3 Preferably not greater than 40 kg / m 3 More preferably, not more than 35 kg / m 3 Preferably, the density of the noise-reducing material is not less than 5 kg / m³. 3 More preferably not less than 10 kg / m 3 The density of the noise reduction material was measured according to ISO 845:2009 standard.

[0179] Preferred expanded polymeric materials for manufacturing noise-reducing components are expanded polyurethane foam, such as ether-based polyurethane foam and ester-based polyurethane foam; expanded polyolefins, such as expanded polyethylene, expanded polypropylene and mixtures thereof; and expanded rubbers, such as expanded chloroprene rubber (CR sponge), expanded ethylene-propylene rubber (EPDM sponge), expanded nitrile rubber (NBR sponge), etc.

[0180] The expanded polymer material can be open-cell or closed-cell. Preferably, the expanded polyolefin material is closed-cell, and optionally perforated. Preferably, the polyurethane material is open-cell. The cells can have variable sizes, typically divided into large cells with an average size greater than 1.5 mm and micro cells with an average size less than 1.5 mm.

[0181] Useful examples of expanded polymeric materials are described in WO2013182477A1, EP2457748A1, EP1661735A1, EP1876038A1 and EP2457720A1, and are also described in WO2016051371A1 and WO2017163219A1 belonging to the applicant.

[0182] Other features and advantages will become apparent from the detailed description of preferred, but not exclusive, embodiments of the self-sealing tire for vehicle wheels and the composite comprising sealing components according to the invention.

[0183] The following references are for illustrative purposes only and are therefore non-limiting. Figure 1 The accompanying diagram provides the following description, where "X" represents the equatorial plane of the finished tire 1. For simplicity, Figure 1 Only a portion of the tire is shown; the remaining portion, not shown, is identical and arranged symmetrically with respect to the equatorial plane “X”.

[0184] Figure 1 Reference numeral 1 in the figures indicates a self-sealing tire for a vehicle wheel, which typically includes a carcass structure 2, the carcass structure comprising at least one carcass ply 3 having opposing end flanges that respectively engage with a corresponding annular anchoring structure 4, the annular anchoring structure 4 optionally associated with an elastomeric filler 4a, the elastomeric filler being integrated in an area 5 typically identified by the name "bead". The at least one carcass ply 3 comprises a plurality of fabric or metal reinforcing cords arranged parallel to each other and at least partially covered by a layer of elastomeric material.

[0185] The carcass structure 2 is associated with a belt structure 6, which includes one or more belt layers that overlap radially with each other and with respect to the carcass ply 3, the belt layers having typical metal-reinforced cords.

[0186] The reinforcing cords may have a cross orientation relative to the circumferential unfolding direction of the tire 1.

[0187] The tread belt 7 is applied at a position radially outward relative to the belt structure 6 and is made of an elastomeric composition such as other semi-finished products constituting the tire 1.

[0188] The respective sidewalls 8, made of an elastomer composition, are further applied to the axially outer position on the side surface of the carcass structure 2, each sidewall extending upward from one of the side edges of the tread band 7 at the corresponding annular anchoring structure to the bead 5.

[0189] Furthermore, preferably, the radial inner surface of the tire 1 is lined internally by a substantially airtight layer of elastomeric material or so-called liner 9.

[0190] exist Figure 1 In the embodiment shown, tire 1 is a tire for motor vehicles.

[0191] Typically, in this case, the belt structure 6 also includes at least one radial outer layer comprising fabric cords or metal cords or a fabric / metal combination arranged at approximately zero degrees relative to the circumferential unfolding direction of the tire.

[0192] According to an embodiment of the invention, tire 1 is used in a motor vehicle. The profile of the straight portion of the motor vehicle tire (not shown) has a high lateral curvature because it must allow sufficient contact area under all tilt conditions of the motor vehicle. The lateral curvature is defined by the ratio of the distance f between the tread ridge measured on the equatorial plane of the tire and the line passing through the laterally opposite ends of the tread itself to the width C defined by the distance between the laterally opposite ends of the tread itself. A tire with a high lateral curvature means a tire whose lateral curvature ratio (f / C) is at least 0.20. Preferably, for the rear tire, (f / C) is between 0.20 and 0.5; for the front tire, (f / C) is between 0.35 and 0.6.

[0193] The self-sealing tire 1 according to the invention further includes a sealing polymeric material layer 10 disposed at the crown portion of the tire 1 and located radially inward relative to the liner 9. The sealing polymeric material layer 10 extends over the entire circumferential extent of the tire 1. The sealing material layer 10 preferably has a maximum thickness "t1" at the equatorial plane "X" of the finished tire 1 (i.e., the molded and vulcanized tire), and tapers towards the axial end of the crown portion. Figure 1 Preferably, the maximum thickness "t1" is between 2 mm and 6 mm, more preferably between about 2.5 mm and 5 mm.

[0194] The multilayer self-supporting membrane 11 according to the invention is arranged at a radially inward position relative to and in contact with the sealing polymeric material layer 10. For example... Figure 4 As shown, the multilayer self-supporting membrane 11 according to the present invention comprises a polyethylene inner layer 11b and two polyamide outer layers 11c and 11c'. The multilayer self-supporting membrane 11, like the sealing polymer layer 10, extends over the entire circumferential extension of the tire 1 and has a width (i.e., axial extension range) slightly larger than that of the sealing polymer layer 10.

[0195] Preferably, in the finished tire, the thickness "t2" of the multilayer self-supporting film 11 is preferably between 5 μm and 40 μm, and more preferably between about 10 μm and about 30 μm.

[0196] The sealing polymer layer 10 and the multilayer self-supporting membrane 11 form a sealing assembly 12. When a sharp element (such as a nail or screw) penetrates the tire and traverses the sealing polymer layer 10 and the multilayer self-supporting membrane 11, the sealing assembly 12 is able to adhere to the penetrating object and flow into the hole when the object is removed, thereby sealing the hole itself and preventing air from escaping from the tire.

[0197] The sealing assembly 12 is easily punctured by sharp elements, while maintaining such deformability and adhesiveness to facilitate the transfer of sealing material when a sharp element is ejected. The perforations thus sealed by the multilayer self-supporting membrane 11 are clearly visible on the surface of the sealing assembly 12.

[0198] During the construction of the green tire 1, the axially opposite edges 11a of the multilayer self-supporting film 11 adhere to the radially inner surface of the liner 9. Two annular strips (not shown) made of an elastomeric material may also be provided, each positioned close to one edge of the sealing assembly 12. The axially inner portion of each elongated element of the elastomeric material is stacked on the sealing assembly 12 and positioned at the radially innermost position within the sealing assembly 12. The axially outer portion of each elongated element of the elastomeric material is in direct contact with the liner 9 and secures the sealing assembly 12 to the tire by co-crosslinking with the liner during vulcanization.

[0199] The construction of the precursor of the green tire 1, including the sealing component 12 as described above, is preferably carried out by assembling the corresponding semi-finished product on one or more molded supports (not shown).

[0200] The carcass structure and belt structure are usually manufactured separately in their respective workstations so that they can be assembled together at a later time.

[0201] More specifically, the construction of the carcass structure first provides a continuous band for the formation of the sealing assembly 12, the continuous band comprising a sealing material layer 10 disposed on and supported by a multilayer self-supporting membrane 11, the width of the multilayer self-supporting membrane 11 such that the axially opposite edges 11a of the multilayer self-supporting membrane 11 are exposed. Figure 2 ).

[0202] The sealing material layer 10 has a thickness "t3" between about 3 mm and about 8 mm before the sealing assembly 12 is bonded to the front of the tire 1 and before it is shaped.

[0203] The multilayer self-supporting membrane 11 has a thickness “t4” equal to or less than 50 μm, preferably less than 40 μm, before the sealing assembly 12 is bonded to the precursor of the tire 1 and before its shaping.

[0204] The sealing assembly 12 is cut to size, preferably obliquely (tilted), and wrapped around the radially outer surface of the building drum, so that the multilayer self-supporting membrane 11 is in the radially innermost position. Due to the adhesiveness of the sealing composition, the opposite ends of the sealing assembly 12 are flanged together; preferably, the joint is covered and reinforced by, for example, tape (joint) (to avoid leakage of the sealing material during vulcanization).

[0205] The liner 9 and one or more carcass ply 3 are applied to the sealing assembly 12 to form a so-called "carcass sleeve," which is typically basically cylindrical. An annular anchoring structure 4 is fitted to the bead 5 or formed on the opposite end flanges of one or more carcass ply 3, and the carcass ply then folds back around the annular anchoring structure 4 to close them in a ring.

[0206] A so-called "outer sleeve" is manufactured on a second drum or auxiliary drum. The outer sleeve includes reciprocatingly superimposed belt layers 6 and tread strips 7 optionally applied at radially outer positions of the belt layers 6. The outer sleeve is then picked up from the auxiliary drum for connection to the carcass sleeve. For this purpose, the outer sleeve is arranged coaxially around the carcass sleeve, and then one or more carcass plies 3 are formed into a ring configuration by mutual axial approach of the bead 5 and simultaneous introduction of fluid into the carcass sleeve under pressure, thereby causing radial expansion of the carcass plies 3 until they adhere to the inner surface of the outer sleeve.

[0207] The assembly of the carcass sleeve and the outer sleeve can be performed on the same drum used to manufacture the carcass sleeve; in this case, it is called a "single-stage construction process" or "single-level process." A so-called "two-stage" construction process is also known, in which the carcass sleeve is first manufactured using a so-called "first-stage drum," and the assembly between the carcass sleeve and the outer sleeve is performed on a so-called "second-stage drum" or "forming drum," transferring the carcass sleeve picked up from the first-stage drum and the outer sleeve picked up from the auxiliary drum to the "second-stage drum" or "forming drum."

[0208] Following the construction of the raw tire 1, molding and vulcanization processes are typically performed to determine the tire's structural stability through the crosslinking of the elastomer composition, and to impart the desired tread pattern on the tread belt 7 and any distinguishable graphic markings on the sidewalls 8. During vulcanization between the elastomer macromolecules, covalent bond modes develop, which, depending on their density, prevent their flow, thus making the material increasingly insoluble, non-melting, and elastic. After vulcanization, the sealing material layer 10 achieves optimal deformability, viscosity, and cohesiveness characteristics.

[0209] During the vulcanization process, despite the use of high temperatures, the multilayer self-supporting membrane 11 and the sealing material 10 remain intact, without damaging the vulcanized membrane, and achieve optimal sealing performance.

[0210] exist Figure 3 In the middle, a removable protective film 14 is used to cover it. Figure 2 The sealing assembly 10 is used to obtain a multilayer composite 15. For example, the multilayer composite 15 can be prepared by extruding the sealing material 10 onto a protective film 14 and mechanically bonding it with a multilayer self-supporting film 11 to obtain a strip composite, which is cooled and typically stored wound on a roll.

[0211] like Figure 5 As shown, tire 1 may ultimately include a noise-reducing material or element 13 made of an expanded polymeric material, said noise-reducing material or element 13 being applied, for example, by adhesive bonding to the radially inner surface of a multilayer self-supporting film 11, extending across the entire circumference of the tire and applied axially symmetrically with respect to the equatorial plane X at at least 40% to up to 90% of the tire's tread width. The noise-reducing element or layer 13 may be adhered to the radially inner surface of the multilayer self-supporting film 11 by bonding with a suitable adhesive (such as an acrylic adhesive) or by snap-fit ​​or press-fit, such that the noise-reducing layer is larger than the tire's inner diameter.

[0212] The present invention will be further illustrated below with several preliminary examples. These embodiments are for illustrative purposes only and do not limit the present invention in any way.

[0213] Multiple examples

[0214] Example 1

[0215] For testing purposes, different tires (size 215 / 55R17) were manufactured, each including different sealing components.

[0216] The sealing assembly 1, which is obtained in accordance with the teachings of WO2011064698 and includes a polyamide self-supporting layer of Filmon CXS18 with a nominal thickness of 15 μm, is used as a reference.

[0217] The sealing assembly 2 comprises a 15 μm multilayer self-supporting membrane made of two polyamide outer layers (each representing 25 wt%) and a polyethylene inner layer (representing 50 wt%).

[0218] Sealing assemblies 1-2 comprise the sealing compositions listed in Table 1 below.

[0219] Table 1

[0220] Components Quantity (phr) IR 50 SBR 30 SIS 20 NC 12 Resin 1 40 Resin 2 7 Oil 45 antioxidants 2 peroxide 0.6

[0221] IR: cis-1,4-polyisoprene, exported from Nizhnekamskneftechim, Russia;

[0222] SBR: Styrene-butadiene copolymer, from International Specialty Products (ISP).

[0223] SIS: Styrene-isoprene-styrene block copolymer, from Polimeri Europa's Europrene ® SOL T190;

[0224] NC: Carbon black N234 from Cabot Corporation;

[0225] Peroxide: Luperox 101 XL45 from Arkema;

[0226] Oil: Mineral oil (MES - Mild Extraction Solventization) from Shell's Catenex SNR;

[0227] Resin 1: Escorez from ExxonMobil ® 1102;

[0228] Resin 2: Struktol from Struktol Corporation ® 40MS;

[0229] Antioxidant: Santoflex from Eastman ® 6PPD.

[0230] Before the tire is constructed, the sealing material layer has a thickness of approximately 4.0 mm, and the sealing assembly is arranged radially inward relative to the liner (e.g., Figure 1 As shown in the image).

[0231] Summer tires with or without noise reduction components (215 / 55R17 Pirelli Cinturato P7) TM In the case of -P7), the sealing assembly 1-2 is constructed and vulcanized. The noise reduction element consists of six blocks with dimensions of 120 x 180 x 30 mm and two blocks with dimensions of 120 x 240 x 30 mm, the blocks having a density of 30 ± 2 kg / m³. 3 It is made of polyurethane material Cirene 30 (Cires SpA) as specified in ISO 845:2009 and applied to the radial inner surface of the self-supporting layer.

[0232] Install the molded and vulcanized tire onto a standard rim and inflate it to a pressure of 2.4 bar.

[0233] The tire is punctured at the tread using 15 sharp elements (nails) with a diameter of 3-5 mm and a length of 60 mm. The sharp elements are arranged randomly, including pins and grooves.

[0234] Tires without noise reduction components undergo both cold static and hot dynamic tests. Tires with noise reduction components undergo only hot dynamic tests.

[0235] Cold static test

[0236] In the cold static test, a tire with nails inserted was placed in a climate chamber at -21°C for 24 hours to acclimatize. The tire was then removed from the climate chamber and 15 nails were removed. For each nail, air leakage from the hole was assessed using a soapy water solution.

[0237] The results are summarized in Table 2 below.

[0238] Table 2

[0239]

[0240] As can be clearly seen from the data shown in Table 2, the tire with sealing component 2 according to the present invention has significantly improved sealing performance compared with the reference object with sealing component 1.

[0241] Thermal dynamics test

[0242] In the thermal dynamics test, the studded tire rolled on a 2.8m diameter disc at a speed of 120km / h under a 550kg load. The test simulated a 500km road trip, alternating between 10-minute cycles with zero drift angle and 10-minute cycles with drift angles fluctuating from -6° to +6°. The drift speed was 1° / s, and 25 oscillations were performed for each drift cycle. The tire did not leak air throughout the test. At the end of the test, 15 studs were removed, and air leakage from the holes was assessed using a soapy water solution.

[0243] The results are summarized in Table 3 below.

[0244] Table 3

[0245]

[0246] As can be clearly seen from the data shown in Table 3, the tire with sealing component 2 according to the present invention has the same sealing performance as the reference tire with sealing component 1 in the absence of noise reduction element, but has significantly improved sealing performance in the presence of noise reduction element.

[0247] Example 2

[0248] To characterize the multilayer self-supporting membrane of sealing assembly 2 relative to the self-supporting layer of sealing assembly 1 used in Example 1, tensile tests were performed on two specimens, each measuring 300 x 20 mm, at a temperature of 23°C and a relative humidity of 46% according to ASTM D882, at a tensile speed of 500 mm / min, to measure the breaking strength and 10% deformation strength (Ca0.1).

[0249] The results are summarized in Table 4 below.

[0250] Table 4

[0251] Fracture strength Ca0.1 Multilayer self-supporting membrane of sealing component 2 30MPa 20 Self-supporting membrane of sealing assembly 1 63MPa 66

[0252] In addition, stress relaxation tests were performed on specimens of the same size using a Zwic 1445 force gauge. Before testing, the specimens were conditioned at 23°C for at least 4 hours. The specimens were mounted on the instrument fixtures with an initial distance of 200 mm between the fixtures. A preload of 0.5 N was applied first at a speed of 20 mm / min, followed by a deformation rate (elongation) of 30% at a speed of 500 mm / min. The residual relaxation strength was then measured after 300 seconds of relaxation.

[0253] The results are summarized in Table 5 below. Figure 6 and Figure 7 middle.

[0254] Table 5

[0255] Residual strength after 300 seconds Multilayer self-supporting membrane of sealing component 2 10MPa Self-supporting membrane of sealing assembly 1 40MPa

[0256] The low residual strength and low Ca0.1 of the multilayer self-supporting membrane according to the invention describe the material's lower rigidity and toughness. The lower rigidity of the sealing assembly 2 allows the sealing composition to flow more at the puncture site when the nail is removed.

[0257] Similarly, the low residual strength after 300 seconds of relaxation indicates that the material is less elastic, thus reducing the elastic recovery of the membrane as it returns to its equilibrium position when the nail is pulled out (which drags and pushes the sealant away from the perforation), and therefore allowing a larger amount of sealant composition to remain in the hole.

Claims

1. A self-sealing tire for a vehicle wheel, the self-sealing tire comprising: At least one carcass ply; A tread band, which is applied in the crown portion at a radially outer position relative to the carcass ply; At least one liner, said liner being applied at a radially inward position relative to said carcass ply; a sealing assembly being applied at a radially inward position relative to said liner and extending axially over at least a portion of the crown portion; The sealing assembly includes a permanent multilayer self-supporting membrane and a sealing material layer. The multilayer self-supporting membrane includes at least two polyamide outer layers and at least one polyolefin inner layer. The residual relaxation strength of the permanent multilayer self-supporting membrane is between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa. The sealing material layer is associated with and supported by the permanent multilayer self-supporting membrane. The permanent multilayer self-supporting membrane is located radially inside the sealing material layer, and the sealing material layer is positioned to be in substantially contact with the lining.

2. The self-sealing tire according to claim 1, wherein the tensile strength of the permanent multilayer self-supporting membrane is between 10 MPa and 50 MPa, preferably between 20 MPa and 40 MPa.

3. The self-sealing tire according to claim 1, wherein the 10% strain strength (Ca0.1) of the permanent multilayer self-supporting membrane is between 5 MPa and 40 MPa, preferably between 10 MPa and 30 MPa.

4. The self-sealing tire according to any one of claims 1 to 3, wherein the thickness of the permanent multilayer self-supporting film is equal to or less than 50 μm, preferably equal to or less than about 40 μm.

5. The self-sealing tire according to claim 4, wherein the thickness of the permanent multilayer self-supporting film is equal to or greater than 1 μm, preferably equal to or greater than about 5 μm.

6. The self-sealing tire according to any one of claims 1 to 5, wherein the thickness of the sealing material layer is greater than about 2.0 mm and less than about 6.0 mm.

7. The self-sealing tire of claim 1, wherein the sealing assembly extends axially over at least 60% of the crown portion of the tire.

8. The self-sealing tire of claim 7, wherein the sealing assembly extends axially over at least the entire crown portion of the tire.

9. A multilayered ribbon-like composite, the composite comprising: Sealing components, and Removable protective film The sealing assembly comprises a permanent multilayer self-supporting membrane and a sealing material layer. The permanent multilayer self-supporting membrane comprises at least two polyamide outer layers and at least one polyolefin inner layer. The residual relaxation strength of the permanent multilayer self-supporting membrane is between 1 MPa and 20 MPa, preferably between 5 MPa and 15 MPa. The sealing material layer has a substantially opposing first and second surface. The sealing material layer is associated with and supported by the permanent multilayer self-supporting membrane at the level of the first surface. The removable protective film is positioned to contact the second surface of the sealing material layer.

10. The composite of claim 9, wherein the thickness of the removable protective film is less than 100 μm, preferably less than 50 μm.

11. The composite according to claim 9 or 10, wherein the removable protective film comprises a polymeric material selected from polyester, polyamide, polycarbonate, polyvinyl chloride and fluorinated polyolefin.

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