Self-supporting tire for vehicle wheels

Abstract

The present invention relates to a self-supporting tyre (100) for motor vehicles comprising sidewall reinforcing inserts (113A, 113B) having different stiffness. In particular, the stiffness of the sidewall reinforcing inserts on the sides of the tyre which are most stressed during running is less than the stiffness of the sidewall reinforcing inserts on the sides which are less stressed. The tyre of the present invention shows a reduced rolling resistance and better comfort during normal running and an unexpectedly increased mileage in run-flat running.

Description

Technical Field

[0001] This invention relates to a self-supporting tire for vehicle wheels.

[0002] In recent years, tire manufacturers have sought to eliminate the need for bulky spare wheels in vehicles while ensuring the vehicle's ability to continue driving in the event of significant or complete pressure loss from one or more tires.

[0003] Nowadays, spare wheels are often replaced by wheels with reduced cross-sections or repair / inflation kits; however, repair / inflation kits require stopping and performing operations under conditions that can be severe.

[0004] Self-supporting tires are tires that can support the vehicle load under considerable or complete pressure loss, allowing the driver to travel a certain distance to the garage without having to stop to wait for roadside assistance or change / reinflate the tires in potentially dangerous situations.

[0005] When the inflation pressure is significantly lower than the operating pressure or even zero (this is called "run-flat" mode), the tire must be able to travel a certain distance at a certain speed, such as 80 km to 80 km / h.

[0006] This performance, known as "EM" (Extended Mobility), is a requirement imposed by legislation or vehicle manufacturers to enable them to present tires as suitable for run-flat protection.

[0007] When the inflation pressure is close to the operating pressure (in this case, people call it "normal driving" mode), it is desirable for the tires to have the highest possible performance, such as, in particular, handling, low weight, low rolling resistance, and sufficient comfort.

[0008] Ideally, a self-supporting tire should have a structure strong enough to prevent the sidewall structure and inner surface from collapsing or folding back onto itself when the tire is deflated, while exhibiting favorable comfort and rolling resistance when the tire is in normal inflation.

[0009] Several techniques have been used to achieve the above-mentioned support effects without compromising normal operating conditions.

[0010] Therefore, for example, to impart self-supporting characteristics to a tire—that is, the aforementioned ability to maintain short / medium distance travel under reduced or essentially zero inflation pressure (e.g., after a puncture)—it is known to integrate one or more elastomeric sidewall reinforcement inserts into the tire's sidewall structure. These sidewall reinforcement inserts, typically having a lenticular and / or substantially semi-circular profile, are located axially outside the impermeable elastomeric material layer and axially inside each sidewall. When the tire's normal inflation pressure is reduced, for example after a puncture, these elastomeric sidewall reinforcement inserts serve to adequately support the vehicle's load.

[0011] Therefore, a self-supporting tire for a vehicle wheel constructed in this way includes:

[0012] - A carcass structure, the carcass structure comprising at least one carcass layer having opposing lateral edges associated with a corresponding annular anchoring structure;

[0013] - A belt structure applied at a location radially outside the tire carcass structure;

[0014] - A tire crown applied at a position radially outside the belt structure;

[0015] - A pair of sidewall structures, each sidewall structure comprising a sidewall extending in a position axially outside the carcass structure and radially extending between one of the annular anchoring structures and the axially outside portion of the crown;

[0016] - A layer of impermeable elastomeric material applied in the radially internal location of the tire carcass structure is called a liner; and

[0017] - At least one pair of sidewall reinforcement inserts, each sidewall reinforcement insert being incorporated into the corresponding sidewall structure of the tire at a position axially outside the impermeable elastomer material layer and axially inside the sidewall.

[0018] In passenger cars, wheels are typically mounted with a camber angle to allow for maximum contact surface between the tire and the road, especially during cornering, for optimal grip. Camber is positive when the wheel's top is facing outwards from the vehicle, and negative when it's cambered inwards. It's well known that tire grip increases with increased contact surface with the road; therefore, ideally, the wheel should be constantly perpendicular to the road surface, and the tire should not deform under high lateral loads. However, in practice, tire deformation and suspension deflection under load transmission during driving must be considered.

[0019] In modern cars, camber is almost always negative or zero to improve road grip during cornering. Specifically, on the front axle, it is 0° or slightly negative (1°-1.5°) to minimize uneven tire wear. On the other hand, a more pronounced negative camber is preferred for the rear, both to maximize grip when cornering with the car leaning and to improve cornering and reduce understeer.

[0020] With negative camber tires, tire failures generally occur on the side of the tire facing inwards from the vehicle.

[0021] Therefore, self-supporting tires installed on the rear wheels of a vehicle are even more prone to internal loads and damage when in a leak-proof condition. Existing technology

[0022] In the field of self-supporting tires, various implementation schemes have been proposed that aim to give self-supporting capabilities the desired characteristics without unduly compromising ride comfort and fuel consumption at normal inflation pressure.

[0023] According to the method proposed in the prior art, self-support capability is ensured by reinforcing the sidewall structure with inserts of at least one specific rubber at locations on the axially outer side of the liner and the axially inner side of each sidewall.

[0024] Typically, sidewall reinforcement inserts function by supporting low-profile tires. According to existing technology, it is believed that the inserts should be made of a high-modulus material to ensure lift, low hysteresis to minimize rolling resistance, and good elongation at break, primarily to allow for tire mounting / removal from the rim. However, when driving under normal inflation conditions, the presence of a high-modulus sidewall reinforcement insert imposes strong stress and undesirably reduces ride comfort.

[0025] Typically, sidewall reinforcement inserts are used to improve the lifting performance of self-supporting tires, even large-volume sidewall reinforcement inserts. However, due to their large mass, sidewall reinforcement inserts degrade ride comfort and fuel consumption.

[0026] Typically, to determine the optimal trade-off, the reinforcing insert is made of a high-modulus rubber compound. This high-modulus compound is undesirable due to its high rolling resistance and poor comfort, and its thickness is gradually reduced until a minimum leak-proof distance is determined. However, due to the still high rolling resistance and limited leak-proof performance, the final performance is not entirely satisfactory.

[0027] In fact, existing technologies teach that high modulus can be imparted to the elastomeric compounds of reinforcing inserts in different ways, such as by adding large amounts of reinforcing materials and / or by including elastomers with high modulus and / or by increasing the crosslinking density, using large amounts of vulcanizing agents or other crosslinking systems.

[0028] Furthermore, to account for the asymmetry of stress experienced by the tire during driving, particularly under high negative camber angles, various solutions have been proposed in the prior art. In these solutions, the two sidewall reinforcement inserts typically have different properties, with the aim of always reinforcing the sidewall with the highest stress, for example, by using a more rigid material and / or by increasing the thickness of the reinforcement insert or the insert and the associated sidewall. In the description below, sidewall reinforcement inserts for tires with different properties, elastomer compositions, and / or sizes are generally referred to as “asymmetric” reinforcement inserts.

[0029] For example, document EP2735455A1 describes a self-supporting tire with asymmetrical inserts, wherein the thickness B1 of the sidewall reinforcement insert on one sidewall (9A) is greater than the thickness B2 of the sidewall reinforcement insert on the other sidewall (9B), while the sidewall thickness A1 of the first sidewall (10A) is less than the sidewall thickness A2 of the other sidewall. This document teaches that the sidewall material must have a complex modulus of elasticity E*1 of not less than 3 MPa (paragraph 31), and the modulus E*2 of the reinforcement insert material (9) must be even higher (paragraph 39). Examples (Tables 1-1 and 1-2) show E*2 values ​​of 6 or 8 MPa. This specification does not disclose any elastomer compositions in detail.

[0030] Document WO2019086785A1 describes a self-supporting tire comprising a sidewall reinforcing insert made of a high modulus, particularly a complex shear dynamic modulus G* of at least 1.0 MPa (claim 1), preferably at least 1.9 MPa (claim 3), and advantageously from 1.9 MPa to 3.3 MPa (paragraph 25). The tire of the embodiment has a reinforcing insert made of an elastomeric material with a complex modulus G* of 3.15 MPa.

[0031] The sidewall reinforcement inserts described herein can be asymmetrical. In fact, due to the rigidity of the material, the thickness of the inner sidewall reinforcement insert can be reduced compared to the outer side insert, resulting in reduced mass and stress during extreme speed testing. This specification does not disclose any elastomer composition in detail.

[0032] Document WO2005072992A1 describes a self-supporting tire comprising an asymmetric reinforcing insert, wherein the inner sidewall reinforcing insert has a significantly higher modulus than the outer sidewall reinforcing insert, preferably a secant modulus of 5 to 13 MPa (page 4, paragraph 3 and Table 1). The preferred elastomer composition for the reinforcing insert has a high content of polybutadiene (50 phr to 80 phr, page 4, penultimate paragraph). The composition shown herein for the sidewall insert (page 16) has a filler content (carbon black) of 65 phr.

[0033] Document JP3703922B2 describes an asymmetric self-supporting tire with sidewall reinforcement inserts on the more stress-bearing sides—in this case, the outer tire, precisely where the load and therefore the tendency for damage to concentrate is concentrated on the self-supporting tire mounted on the front wheel—compared to the inner tire. The specification does not detail any elastomer composition, nor does it mention the modulus values ​​of the materials.

[0034] In summary, what appears to be reinforced in the prior art is that this type of tire must have rigid sidewall reinforcement inserts to ensure sufficient self-support, and these inserts are typically more rigid and / or thicker on the side of the tire where stress is greatest. Invention Overview

[0036] Based on existing technology, the applicant has conducted research to improve the performance of self-supporting tires, particularly to further reduce rolling resistance and thus reduce fuel consumption, while improving comfort and performance under run-flat conditions.

[0037] The applicant has discovered that the need to give tires even lower rolling resistance and comfort can be reconciled to ensure that the required self-supporting characteristics far exceed the minimum mileage required by automakers.

[0038] Surprisingly, and contrary to what the prior art teaches, this result is achieved by using a rubber compound with a lower modulus than other reinforcing inserts (located on the less stress side of the tire), thereby reducing the stiffness of the sidewall reinforcing inserts, and more particularly the stiffness of the sidewall reinforcing inserts arranged on the side of the tire subjected to the greatest stress. In this specification, "side A" preferably refers to the tire side subjected to less stress during driving, and "side B" refers to the side subjected to the greatest stress.

[0039] Furthermore, the applicant was surprised to find that the aforementioned performance was further improved if the same rubber compound with a lower modulus was also used in a specific inner layer (referred to as the liner) of the self-supporting tire of the present invention.

[0040] In this way, rolling resistance, comfort, and overall performance under run-flat driving conditions can be achieved, which is unexpectedly improved compared to existing self-supporting tires characterized by more rigid asymmetrical inserts, which typically provide greater support to the side of the tire with the greatest stress in existing self-supporting tires.

[0041] Therefore, the object of the present invention is a self-supporting tire for automobile wheels, comprising:

[0042] - A carcass structure, the carcass structure comprising at least one carcass layer having opposing lateral edges associated with a corresponding annular anchoring structure;

[0043] - A belt structure applied at a location radially outside the tire carcass structure;

[0044] - A tire crown applied at a position radially outside the belt structure;

[0045] - A pair of sidewall structures, each sidewall structure comprising a sidewall extending in a position axially outside the carcass structure and radially extending between one of the annular anchoring structures and the axially outside portion of the crown;

[0046] - A single first sidewall reinforcement insert and a single second sidewall reinforcement insert, each insert being incorporated into the corresponding sidewall structure of the tire at an axially inward location within the respective sidewall.

[0047] Its features

[0048] The first sidewall reinforcing insert is composed of an elastomer compound (A) with a shear modulus G′ of at least 1.25 MPa, and

[0049] The second sidewall reinforcing insert is composed of an elastomer material (B) with a shear modulus value G′ less than 1.25 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz, and 9% strain according to the method disclosed in this specification.

[0050] Preferably, the elastomer compound (B) is prepared by mixing and vulcanizing an elastomer composition, wherein the elastomer composition comprises at least:

[0051] At least one diene elastomer polymer with a phr of -100 phr

[0052] - At least one reinforcing filler, comprising less than 30% by weight relative to the total weight of the composition, and

[0053] - At least one vulcanizing agent with a concentration of at least 0.1 phr.

[0054] Preferably, the first sidewall reinforcement insert is disposed on side A of the tire.

[0055] Preferably, the second sidewall reinforcement insert is disposed on the B side of the tire.

[0056] definition

[0057] The following definitions apply in this specification and the appended claims.

[0058] 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 elastomeric compound suitable for tires and their components.

[0059] 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 possibly accelerators and retarders, are usually added in a downstream step relative to the incorporation and processing of all other components.

[0060] In the final vulcanizable or even further vulcanizable elastomer compound, the individual components of the elastomer composition may be completely or partially altered or no longer individually traceable as modified due to interactions with other components, thermal and / or mechanical processing.

[0061] The term "elastomer compound" refers to a compound that can be obtained by mixing at least one elastomer polymer with at least one of the additives commonly used in the preparation of tire compounds and possibly by heating.

[0062] The term "vulcanizable elastomer compound" refers to an elastomer compound prepared for vulcanization, which can be obtained by incorporating all additives (including vulcanizing additives) into the elastomer compound.

[0063] The term "vulcanized elastomer compound" refers to materials that can be obtained through the vulcanization of vulcanizable elastomer compounds.

[0064] The term "green" refers to materials, compounds, compositions, parts, or tires that have not yet been vulcanized.

[0065] The term "vulcanization" refers to the crosslinking reaction in natural or synthetic rubber induced by sulfur-based and / or peroxide-based vulcanizing agents.

[0066] The term "vulcanizing agent" refers to a product that transforms natural or synthetic rubber into an elastic and resistant material by forming a stable three-dimensional network of intermolecular and intramolecular bonds. Typically, vulcanizing agents are sulfur-based compounds, such as elemental sulfur, polymeric sulfur, and vulcanizing agents like bis[(trialkoxysilyl)propyl] polysulfides, thiuram, dithiodimorpholine, and caprolactam-disulfides. Alternatively, vulcanizing agents can be peroxides containing O / O bonds that can generate reactive free radicals upon heating.

[0067] The term "vulcanization accelerator" refers to compounds that can reduce the duration and / or operating temperature of the vulcanization process, such as TBBS, generally sulfenamides, thiazoles, dithiophosphates, dithiocarbamates, guanidines, and sulfur donors such as thiuram.

[0068] 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. In the case of peroxide vulcanizing agents, an example of an activator is polymethacrylate, such as ethylene glycol dimethacrylate.

[0069] The term "vulcanization retarder" refers to a product that can delay the initiation of the vulcanization reaction and / or inhibit unwanted secondary reactions, such as N-(cyclohexylthio)phthalimide (CTP).

[0070] The term "vulcanizing package" refers to a vulcanizing agent and one or more vulcanizing additives selected from vulcanizing activators, accelerators and retarders.

[0071] The terms “elastomer polymer” or “elastomer” or “rubber” refer to natural or synthetic polymers that, after vulcanization, can be repeatedly stretched to at least twice their original length at room temperature and return to approximately their original length substantially immediately upon removal of the tensile load (as defined in the ASTM D1566-11 standard terminology relating to rubber).

[0072] The term "diene elastomer polymer" refers to an elastomer polymer derived from the polymerization of one or more monomers, at least one of which is a conjugated diene.

[0073] 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, such as silica precipitated from sand with strong acid, preferably amorphous, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicate, kaolin, silicate fibers, their derivatives and mixtures thereof.

[0074] The term "white filler" refers to conventional reinforcing materials used in this field, selected from conventional silica and silicates such as sepiolite, palygorskite (also known as green palygorskite), montmorillonite, halloysite, etc., which may be modified and / or derivatized through acid treatment. Typically, white fillers have surface hydroxyl groups that may be partially derivatized.

[0075] The term "mixing step (1) or first step" refers to a step in the preparation method of an elastomer compound in which one or more additives may be incorporated by mixing and possibly heating, in addition to the vulcanizing agent and vulcanizing bag fed in step (2). Mixing step (1) is also called a "non-productive step". In the preparation of the compound, there may be several "non-productive" mixing steps, which can be represented by 1a, 1b, etc.

[0076] The term "mixing step (2) or second step" refers to the next step in the preparation of an elastomer compound, in which a vulcanizing agent and possibly other additives (of which the vulcanizing agent is in the vulcanizing package) are introduced into the elastomer compound obtained in step (1) and mixed in the material at a controlled temperature, typically below 120°C, to obtain a vulcanizable elastomer compound. Mixing step (2) is also called a "productive step". In the preparation of the compound, there may be several "productive" mixing steps, which can be represented by 2a, 2b, etc.

[0077] The terms complex modulus, elastic modulus, and viscous modulus refer to dynamic properties well known to those skilled in the art.

[0078] The term "dynamic shear modulus" or "sliding modulus" G′ refers to the ratio between the shear stress applied to a vulcanized elastomer sample and the resulting deformation. Details of the experimental measurement methods are reported in this specification.

[0079] The term "dynamic elastic compressive or elongation modulus E′" refers to the ratio between the uniaxial compressive or traction stress applied to a vulcanized elastomer specimen and the resulting deformation. Details of the experimental measurement methods are reported in this specification. The term "axial extension" or "thickness" (Li, insert width) of the sidewall reinforcing insert refers to the extension of these elements measured perpendicular to a plane tangent to the outer surface of the reinforcing insert.

[0080] The term "equatorial plane" in tire terminology refers to the plane perpendicular to the tire's axis of rotation that divides the tire into two symmetrical and equal parts.

[0081] The terms “radial” and “axial”, as well as the expressions “radial inside / outer” and “axial inside / outer”, refer to the directions perpendicular to the tire’s axis of rotation and the directions parallel to the tire’s axis of rotation, respectively.

[0082] The terms “circumferential” and “circumferentially” are used with reference to the direction of the tire’s circumferential extension (i.e., the direction of the tire’s rolling), which corresponds to the direction on a plane that coincides with or is parallel to the tire’s equatorial plane.

[0083] The term "cord" or "reinforced cord" refers to an element consisting of one or more linear elements (hereinafter also referred to as "lines") incorporated into an elastomeric material matrix. Depending on the circumstances and specific application, these linear elements may be made of fabric and / or metallic materials.

[0084] "Reinforcing elements oriented in a substantially circumferential direction" refers to elements that form an angle of a few degrees (e.g., an angle between approximately 0° and 6°) relative to the equatorial plane of the tire.

[0085] The term "camber" or "camber angle" refers to the degree of inclination of the wheel centerline relative to the vertical line of the ground when the front of the vehicle is viewed.

[0086] "Sidewall reinforcement inserts on the inner or outer side" refers to sidewall reinforcement inserts on one side of the tire, which, once installed on the wheel and vehicle, are located on the inner or outer side of the vehicle, respectively.

[0087] In this article, the “A side” or “B side” of a tire refers to the side of the tire that will experience the least or most stress, respectively, once it is installed on a vehicle.

[0088] The term "phr" (an acronym for "parts per 100 parts of rubber") refers to the number of parts by weight relative to 100 parts by weight of total elastomer base material. No additives (such as any elastomer resins or extender oils) are considered when calculating 100 parts by weight of total elastomer base material.

[0089] Unless otherwise stated, all percentages are expressed as weight percentages. Brief description of the attached diagram

[0091] Figure 1 A cross-section of a self-supporting tire for a vehicle wheel according to the present invention is shown schematically. Invention Details

[0093] In this specification, tire components and corresponding elastomer compounds incorporated into the tire side with less stress are marked with the letter A, while tire components and corresponding elastomer compounds incorporated into the tire side with the greatest stress are marked with the letter B.

[0094] Generally, in the case of rear tires, especially if they have a high camber angle, the side with less stress (A) is the outer side, while the side with more stress (B) is the inner side.

[0095] The self-supporting tire according to the invention may have one or more of the preferred features listed below. These can be combined as needed according to application requirements.

[0096] The sidewall reinforcing insert on side (B) may be partially, substantially (e.g., more than 70% of its weight) or preferably entirely composed of a vulcanized elastomer compound (B) having a shear modulus value G′ less than 1.25 MPa, as measured at 70°C, 10 Hz, and 9% strain according to the method disclosed in this specification.

[0097] The characteristics of vulcanized elastomer compounds (B) can be found in the following dynamic and static mechanical properties.

[0098] Preferably, the shear modulus G′ of the vulcanized elastomer compound (B) is preferably less than 1.20 MPa, more preferably less than 1.10 MPa, even more preferably less than 1.05 MPa, even more preferably less than 1.0 MPa or 0.95 MPa, as measured at 70°C, 10 Hz, and 9% strain according to the RPA method disclosed in this specification.

[0099] Preferably, the shear modulus G′ of the vulcanized elastomer compound (B) is in the range of 0.50 to 1.25 MPa, more preferably 0.70 to 1.10 MPa.

[0100] The shear modulus G′ of the vulcanized elastomer compound (B) is preferably greater than 0.50 MPa, and more preferably greater than 0.70 MPa.

[0101] The dynamic compression modulus E′ of the vulcanized elastomer compound (B) is preferably less than 7.50 MPa, more preferably less than 6.00 MPa, and even more preferably less than 5.00 MPa, as measured at 23°C and 10 Hz according to the method disclosed in this specification.

[0102] The dynamic compression modulus value E′ of the vulcanized elastomer compound (B) is preferably in the range of 3.00 to 8.00 MPa, more preferably 3.50 to 7.50 MPa, and even more preferably 4.00 to 6.00 MPa.

[0103] The Tanδ value of the vulcanized elastomer compound (B) is preferably not greater than 0.080, more preferably not greater than 0.072, and even more preferably not greater than 0.060, as measured at 70°C and 10Hz according to the RPA method disclosed in this specification.

[0104] The Tanδ value of the vulcanized elastomer compound (B) is preferably in the range of 0.030 to 0.080, more preferably 0.035 to 0.072, and even more preferably 0.040 to 0.070, as measured at 70°C and 10Hz according to the RPA method disclosed in this specification.

[0105] The elongation at break (AR) of the vulcanized elastomer compound (B) is preferably greater than 150%, more preferably greater than 200%, and even more preferably greater than 230%, as measured according to the method of UNI 6065:2001.

[0106] The tensile strength CR (%) of the vulcanized elastomer compound (B) is preferably at least 5.0 MPa, preferably at least 7.0 MPa, and more preferably at least 8.0 MPa, as measured according to the method of UNI 6065:2001.

[0107] The tensile strength CR (%) of the vulcanized elastomer compound (B) is preferably in the range of 6.0 to 25.0 MPa, more preferably 7.0 to 20.0 MPa, as measured according to the method of UNI 6065:2001.

[0108] The applicant primarily optimizes the stiffness of the elastomer compound (B) for the purposes of this invention by reducing the content of its reinforcing filler, preferably by using a specific white filler to replace at least a portion of the conventional silica, and possibly by selecting a lower stiffness elastomer component.

[0109] Preferably, vulcanized elastomer compound (B) is obtained by mixing and vulcanizing an elastomer composition (B), wherein the elastomer composition (B) comprises at least:

[0110] At least one diene elastomer polymer with a phr of -100 phr

[0111] - At least one reinforcing filler, comprising less than 30% by weight relative to the total weight of the composition.

[0112] - At least one vulcanizing agent with a concentration of at least 0.1 phr.

[0113] The elastomer composition (B) comprises at least one diene elastomer polymer of at least 100 phr.

[0114] Diene elastomer polymers may be selected from those commonly used in vulcanizable elastomer compositions particularly suitable for the production of tires, namely solid elastomer polymers or copolymers with unsaturated chains having a glass transition temperature (Tg) typically below 20°C, preferably in the range of 40°C to -110°C.

[0115] These polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas-phase polymerization of one or more conjugated dienes, wherein the conjugated dienes are optionally mixed with at least one comonomer selected from monoolefins, monovinyl aromatics and / or polar comonomers in an amount not exceeding 60% by weight.

[0116] Conjugated dienes typically contain 4 to 12, preferably 4 to 8, carbon atoms, and can be selected from, for example, 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, and mixtures thereof.

[0117] Monoolefins can be selected from ethylene and α-olefins that typically contain 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof.

[0118] The monovinyl aromatic hydrocarbons that may optionally be used as comonomers typically contain 8 to 20, preferably 8 to 12, carbon atoms, and may be selected from, for example: styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl, or arylalkyl derivatives of styrene, such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolyl-styrene, 4-(4-phenylbutyl)styrene, and mixtures thereof. Styrene is particularly preferred.

[0119] The optional polar comonomers may be selected from, for example, acrylic and alkyl acrylates, acrylonitrile or mixtures thereof, such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile and mixtures thereof.

[0120] Diene elastomer polymers can be selected from, for example: cis-1,4-polyisoprene (natural or synthetic, preferably natural rubber), 3,4-polyisoprene, polybutadiene (especially polybutadiene with a high 1,4-cis content), optionally 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.

[0121] The elastomer composition (B) may optionally comprise at least one polymer of one or more monoolefins and olefin comonomers or derivatives thereof. The monoolefin may be selected from, for example, ethylene and α-olefins typically containing 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof. Among these copolymers, ethylene / propylene (EPR) or ethylene / propylene / diene (EPDM) copolymers are preferred.

[0122] The polymers described above may optionally be functionalized along the main chain or at its ends.

[0123] Functional groups can be introduced into elastomers by methods known in the art, such as during the production of the elastomer polymer, by copolymerization with at least one corresponding functionalized monomer containing at least one ethylene unsaturation; or by grafting at least one functionalized monomer onto the elastomer polymer in the presence of a free radical initiator (e.g., an organic peroxide) and subsequently modifying the elastomer polymer.

[0124] Alternatively, functionalization can be introduced by reacting with a suitable terminator or coupling agent. In particular, diene elastomer polymers obtained by anionic polymerization in the presence of organometallic initiators (especially organolithium initiators) can be functionalized by reacting the residual organometallic groups derived from the initiator with a suitable terminator or coupling agent, such as amines, amides, imines, carbodiimides, alkyltin halides, substituted benzophenones, alkoxysilanes, aryloxysilanes, alkyl dithiols, alkyl dithiols, carboxyalkyl thiols, carboxyalkyl thiols, and thiodiols.

[0125] Useful examples of terminators or coupling agents are known in the art and described, for example, in patents EP2408626, EP2271682, EP3049447A1, EP2283046A1, EP2895515A1, EP451604, US4742124, WO2015086039A1 and WO2017211876A1.

[0126] Preferably, the at least one functionalized elastomer polymer is obtained from polybutadiene (especially polybutadiene with a high 1,4-cis content), styrene / 1,3-butadiene copolymer, styrene / isoprene / 1,3-butadiene copolymer, styrene / 1,3-butadiene / acrylonitrile copolymer, and mixtures thereof.

[0127] The elastomer composition (B) may comprise two or more elastomer polymers as defined above in the form of a mixture.

[0128] Preferably, the elastomeric composition (B) contains less than 50 phr, more preferably less than 30 phr, and even more preferably less than 20 phr of polybutadiene. Preferably, the elastomeric composition (B) does not contain polybutadiene.

[0129] Preferably, the elastomer composition (B) comprises:

[0130] -70 to 100 phr synthetic or natural polyisoprene or mixtures thereof

[0131] Polybutadiene from -0 to 30 phr.

[0132] More preferably, the elastomer composition (B) comprises:

[0133] -80 to 100 phr synthetic or natural polyisoprene or mixtures thereof

[0134] Polybutadiene from -0 to 20 phr.

[0135] The term "polyisoprene" refers to isoprene polymers and copolymers.

[0136] The term "polybutadiene" refers to butadiene polymers and copolymers.

[0137] The elastomer composition (B) for tires according to the invention comprises at least one reinforcing filler, preferably less than 27% by weight, more preferably less than 25% by weight or 20% by weight relative to the total weight of the composition.

[0138] Preferably, the reinforcing filler is present in a total amount ranging from 5% to 30% by weight, more preferably from 5% to 26% by weight or from 10% to 20% by weight, relative to the total weight of the composition.

[0139] Preferably, the reinforcing filler is selected from carbon black, white filler, silicate fiber, its derivatives and mixtures thereof.

[0140] In one embodiment, the reinforcing filler comprises carbon black.

[0141] Preferably, the carbon black is selected from materials with a surface area (e.g., determined by STSA-statistical thickness surface area according to ISO 18852:2005) of not less than 20 m². 2 / g, preferably about 40-50m 2 Those with / g.

[0142] Carbon black may be, for example, N234, N326, N330, N375 or N550, N660 sold by Birla Group (India) or Cabot Corporation, preferably N550 or N660.

[0143] In one embodiment, the reinforcing filler is a white filler selected from hydroxides, oxides and hydrated oxides, salts and hydrated salts of metals, silicate fibers, derivatives thereof, and mixtures thereof.

[0144] In one embodiment, the reinforcing filler may comprise silica, for example, selected from pyrolytic silica, precipitated amorphous silica, wet silica (hydrated silica), anhydrous silica (anhydrous silica), or mixtures thereof.

[0145] The BET surface area (measured according to ISO standard 5794 / 1) of the silica used in this invention is 10 m². 2 / g to 300m 2 / g, preferably 30m 2 / g to 250m 2 / g, more preferably 40m 2 / g to 190m 2 / g.

[0146] Commercial examples of suitable silica include Zeosil 1165MP, Zeosil 1115MP, Zeosil 185GR, and Efficium from Solvay; Newsil HD90 and Newsil HD200 from Wuxi; K160 and K195 from Wilmar; H160AT and H180AT from IQE; Zeopol 8755 and 8745 from Huber; Perkasil TF100 from Grace; Hi-Sil EZ 120G, EZ 160G, and EZ 200G from PPG; and Ultrasil 7000GR and Ultrasil 9100GR from Evonik. Another example of suitable silica is rice husk silica as described in WO2019229692A1.

[0147] In one embodiment, the reinforcing filler comprises silica mixed with carbon black.

[0148] In one embodiment, the reinforcing filler comprises modified silica.

[0149] Silica can be modified, for example, by reacting with silsesquioxanes (as in WO2018078480A1), by reacting with pyrroles (as in WO2016050887A1), or by reacting with a silanizing agent, such as bis(triethoxysilylpropyl)tetrasulfide (TESPT), 3-aminopropyltriethoxysilane (APTES), 3-glycidoxypropyltriethoxysilane, triethoxy(octyl)silane, triethoxy(ethyl)silane, triethoxy-3 -(2-imidazoline-1-yl)propylsilane, triethoxy-p-tolylsilane, triethoxy(1-phenylvinyl)silane, triethoxy-2-thiophenylsilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 3-(triethoxysilyl)propyl isocyanate, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, isobutyltriethoxysilane, n-octadecyltriethoxysilane, (3-chloropropyl)triethoxysilane, triethoxysilane, and 3-(triethoxysilyl)propionitrile.

[0150] Commercial examples of suitable silanizing agents include Si69, Dynasilan AMEO, and Dynasilan GLYEO from Evonik.

[0151] Modified silica can be siloxane silica or alkyl silica.

[0152] Silyl sulfide alkylated silica is silica prepared by reacting silica (e.g., pyrolytic silica, precipitated amorphous silica, wet silica (hydrated silica), anhydrous silica (anhydrous silica) or mixtures thereof) or metal silicates (e.g., aluminum silicate, sodium silicate, potassium silicate, lithium silicate or mixtures thereof) with at least one silyl sulfide alkylating agent.

[0153] The term "silyl alkylating agent" refers to an organic derivative of silicon containing a mercapto, sulfide, disulfide, or polysulfide group, which is capable of reacting with the OH group of silicon dioxide.

[0154] A suitable commercial example of siloxane-alkylated silica is Agi lon 400 silica from PPG.

[0155] In one embodiment, the reinforcing filler comprises modified silica mixed with carbon black.

[0156] In one embodiment, the reinforcing filler comprises silicate.

[0157] In one embodiment, the silicate is a layered silicate, such as bentonite, halloysite, synthetic lithium soapstone, soapstone, vermiculite, or hydrotalcite.

[0158] In one embodiment, the silicate is a modified layered silicate similar to that described below for modified silicate fibers.

[0159] In one embodiment, the silicate is silicate fiber. These fibers typically have a nanoscale size and a needle-like morphology.

[0160] The silicate fibers are preferably selected from sepiolite fibers, palygorskite fibers (also known as green palygorskite), wollastonite fibers, malachite fibers, and mixtures thereof.

[0161] In one embodiment, the reinforcing filler comprises silicate fibers mixed with carbon black.

[0162] In one embodiment, the silicate fiber is a modified silicate fiber.

[0163] In one embodiment, the modified silicate fiber may be, for example, a fiber modified by acid treatment and partial removal of magnesium, such as those described and exemplified in patent application WO2016 / 174629A1.

[0164] In one embodiment, the modified silicate fiber can be, for example, a fiber modified by depositing amorphous silica on a surface, such as those described and exemplified in patent application WO2016 / 174628A1.

[0165] In one embodiment, the modified silicate fiber can be an organically modified fiber, for example, by reacting with a quaternary ammonium salt, such as sepiolite fiber sold by Tolsa under the name Pangel B5, which is modified by reacting with tartroylbenzyldimethylammonium chloride.

[0166] In one embodiment, the modified silicate fiber can be a fiber modified by reacting with a silanizing agent selected from, for example, monofunctional or bifunctional silanes having one, two, or three hydrolyzable groups, such as bis-(3-triethoxysilyl-propyl)disulfide (TESPD), bis-(3-triethoxysilyl-propyl)tetrasulfide (TESPT), 3-thio-octanoyl-1-propyl-triethoxysilane (NXT), Me2Si(OEt)2, Me2PhSiCl, Ph2SiCl2.

[0167] In one embodiment, the reinforcing filler comprises modified silicate fibers mixed with carbon black.

[0168] In a preferred embodiment, the reinforcing filler comprises sepiolite fibers.

[0169] In a preferred embodiment, the reinforcing filler comprises a white filler prepared as described in WO2019106562A1.

[0170] Particularly preferred are the reinforcing filler M2 prepared according to Example 1 of the applicant's patent application WO2019106562A1, the reinforcing filler M4A prepared according to Example 2, and the reinforcing filler M6 prepared according to Example 3. These white materials (charges) will be referred to below as:

[0171] SilSep1 (reinforcing filler M2 prepared according to Example 1 of patent application WO2019 / 106562A1), SilSep2 (reinforcing filler M6 prepared according to Example 3 of patent application WO2019 / 106562A1), and SilSep3 (reinforcing filler M4A prepared according to Example 2 of patent application WO2019 / 106562A1).

[0172] In a preferred embodiment, the reinforcing filler comprises carbon black, silica, and sepiolite fibers.

[0173] In a more preferred embodiment, the reinforcing filler comprises carbon black ranging from 0 to 10 phr, silica ranging from 5 to 20 phr, and sepiolite fibers ranging from 5 to 20 phr.

[0174] In an even more preferred embodiment, the reinforcing filler comprises carbon black ranging from 0 to 6 phr and SilSep1 and / or SilSep2 and / or SilSep3 in total amounts ranging from 10 to 20 phr.

[0175] The applicant has observed that the balance between rolling resistance and leak-proof driving is particularly advantageous when some or all of the conventional silica in the elastomer composition (B) is replaced by SilSep1, SilSep2 and / or SilSep3.

[0176] The elastomer composition (B) for tire rubber according to the present invention may contain 0.1 to 10 phr of vulcanizing agent.

[0177] Preferably, the composition contains at least one vulcanizing agent at a concentration of at least 0.2 phr, 0.5 phr, 0.8 phr, or 1 phr.

[0178] Preferably, the composition comprises at least one vulcanizing agent in amounts of 0.1 to 10 phr, 0.2 to 10 phr, 1 to 10 phr, or 1.5 to 5 phr.

[0179] At least one vulcanizing agent is preferably selected from sulfur, or alternatively, the vulcanizing agent (sulfur donor) is, for example, bis[(trialkoxysilyl)propyl] polysulfide, thiuram, dithiodimorpholine, and caprolactam-disulfide, and mixtures thereof. Alternatively, the vulcanizing agent is a peroxide containing an OO bond and capable of generating reactive free radicals upon heating.

[0180] Preferably, the vulcanizing agent is sulfur, preferably selected from soluble sulfur (crystalline sulfur), insoluble sulfur (polymerized sulfur), (iii) oil-dispersed sulfur and mixtures thereof.

[0181] Commercial examples of vulcanizing agents suitable for the elastomer composition (B) of the present invention are Redball Superfine sulfur and Crystex from International Sulfur Inc. TM OT 33AS sulfur and Eastmann Crystex TM HS OT20 sulfur.

[0182] In the elastomer composition (B) of the present invention, the vulcanizing agent may be used with auxiliaries known to those skilled in the art, such as vulcanization activators, accelerators and / or retarders.

[0183] The elastomer composition (B) may optionally contain at least one vulcanization activator.

[0184] The vulcanization activator suitable for the elastomer composition (B) of the present invention is a zinc compound, particularly ZnO, ZnCO3, or a zinc salt of a saturated or unsaturated fatty acid containing 8 to 18 carbon atoms, preferably formed in situ in the elastomer composition (B) by a reaction of ZnO and a fatty acid or a mixture thereof. For example, zinc stearate, preferably formed in situ in the elastomer composition (B) from ZnO and a fatty acid, or magnesium stearate formed from MgO, or a mixture thereof, is used.

[0185] The vulcanization activator may preferably be present in the elastomer composition (B) of the present invention in an amount of 0.2 phr to 15 phr, more preferably 1 phr to 5 phr.

[0186] The preferred activator is derived from the reaction of zinc oxide and stearic acid.

[0187] An example of an activator is Aktiplast ST, a product sold by RheinChemie.

[0188] The elastomer composition (B) may further contain at least one vulcanization accelerator.

[0189] Commonly used vulcanization accelerators may be selected, for example, from dithiocarbamates, guanidines, thioureas, thiazoles, sulfenamides, sulfenamides, thiurams, amines, xanthates, or mixtures thereof.

[0190] Preferably, the accelerator is selected from mercaptobenzothiazole (MBT), N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), and mixtures thereof.

[0191] Commercial examples of accelerators suitable for the elastomer composition (B) of the present invention are N-cyclohexyl-2-benzothiazolyl-sulfenamide. (CBS or CZ), and N-tert-butyl-2-benzothiazole sulfenamide, sold by Lanxess NZ / EGC.

[0192] The vulcanization accelerator can be used in the elastomer composition (B) of the present invention in an amount preferably from 0.05 phr to 10 phr, preferably from 0.1 phr to 7 phr, and more preferably from 0.5 phr to 5 phr.

[0193] The elastomer composition (B) may optionally contain at least one vulcanization retarder.

[0194] The vulcanization retarder suitable for the elastomer composition (B) of the present invention is preferably selected from urea, phthalic anhydride, N-nitrosodiphenylamine, N-cyclohexylthiophthalimide (CTP or PVI) and mixtures thereof.

[0195] A commercial example of a suitable delaying agent is Lanxess's N-cyclohexylthiophthalimide VULKALENTG.

[0196] The vulcanization retarder may be present in the elastomer composition (B) of the present invention in an amount preferably from 0.05 phr to 2 phr.

[0197] The elastomer composition (B) of the present invention may contain one or more vulcanization retarders as defined above in the mixture.

[0198] Depending on the elastomer composition (B), those skilled in the art can adjust the composition and crosslinking conditions of the vulcanization package to give the vulcanized elastomer compound (B) a degree of crosslinking commensurate with the shear modulus value G′ set according to the invention.

[0199] The elastomer composition (B) may further contain at least 0.05 phr, preferably at least 0.1 phr, 0.5 phr, or 0.7 phr, more preferably at least 1 phr or 2 phr of at least one silane coupling agent, which is capable of interacting with silica-based reinforcing fillers and binding them to the elastomer polymer during vulcanization.

[0200] Preferably, the silane coupling agent is present in an amount of at least 7% by weight, more preferably at least 9% by weight, relative to the weight of the white filler.

[0201] Preferably, the elastomer composition (B) comprises at least one silane coupling agent in amounts of 0.1 phr to 20.0 phr or 0.5 phr to 10.0 phr, or even more preferably 1.0 phr to 5.0 phr.

[0202] Preferably, the coupling agent is selected from those having at least one hydrolyzable silane group, which can be represented, for example, by the following general formula (III):

[0203] (R′)3Si-C n H 2n -X (III)

[0204] Wherein the groups R′ may be the same or different from each other, and are selected from: alkyl, alkoxy or aryloxy groups or halogen atoms, provided that at least one of the groups R′ is an alkoxy or aryloxy group; n is an integer from 1 to 6; X is selected from nitroso, mercapto, amino, epoxide, vinyl, imide, chlorine, -(S) m C n H2n The groups in -Si-(R′)3 and -S-COR′, where m and n are integers from 1 to 6, and the group R′ is as defined above.

[0205] Particularly preferred silane coupling agents are bis(3-triethoxysilylpropyl)tetrasulfide, 3-thio-octanoyl-1-propyl-triethoxysilane (NXT), and bis(3-triethoxysilylpropyl)disulfide. These coupling agents may be added as is or in mixture with an inert filler (e.g., carbon black) to facilitate their incorporation into the elastomer composition (B).

[0206] An example of a silane coupling agent is TESPT: bis(3-triethoxysilylpropyl)tetrasulfide Si69 sold by Evonik.

[0207] The elastomer composition (B) may further comprise one or more additional ingredients commonly used in the art, such as plasticizing oils, resins, antioxidants and / or anti-ozonants (anti-aging agents), waxes, adhesives, etc.

[0208] For example, the elastomer composition (B) of the present invention may further contain at least one plasticizing oil to further improve the processability of the compound.

[0209] The preferred dosage range for the plasticizer is 0.5 to 10 phr, more preferably 1 to 7 phr.

[0210] The term "plasticized oil" refers to processed oils derived from petroleum, mineral oil, vegetable oil, synthetic oil, or combinations thereof.

[0211] Plasticizing oil can be a petroleum-derived processed oil selected from paraffin (saturated hydrocarbons), cycloalkanes, aromatic polycyclic aromatic hydrocarbons and their mixtures.

[0212] Suitable examples of petroleum-derived processed oils are aromatic, alkane, and naphthenic oils, such as industrially known MES (mild extraction solvate), DAE (distillate aromatic extract), TDAE (treated distillate aromatic extract), TRAE (treated residual aromatic extract), and RAE (residual aromatic extract).

[0213] Plasticized oils can be oils derived from natural or synthetic sources of glycerol and fatty acid esters, including triglycerides, diglycerides, monoglycerides, or mixtures thereof.

[0214] Examples of suitable vegetable oils are sunflower oil, soybean oil, flaxseed oil, rapeseed oil, castor oil, and cottonseed oil.

[0215] Plasticizing oil can be a synthetic oil selected from alkyl or aryl esters of phthalic acid or phosphoric acid.

[0216] The elastomer composition (B) according to the invention may further comprise at least one resin.

[0217] The resin is a non-reactive resin, preferably selected from hydrocarbon resins, phenolic resins, natural resins, and mixtures thereof.

[0218] The amount of resin used is preferably 0.5 to 10 phr, more preferably 1 to 5 phr.

[0219] The elastomer composition (B) may optionally contain at least one wax. The wax may be, for example, a mixture of petroleum wax or paraffin wax.

[0220] Commercial examples of suitable waxes include Repsol n-chain alkane mixtures from Rhein Chemie and 654 microcrystalline wax.

[0221] The wax may be present in the elastomer composition (B) of the present invention in a total amount of typically 0.1 phr to 5 phr, preferably 0.5 phr to 3 phr.

[0222] The elastomer composition (B) may optionally contain at least one antioxidant.

[0223] The antioxidant is preferably selected from N-isopropyl-N′-phenyl-p-phenylenediamine (IPPD), N-(-1,3-dimethyl-butyl)-N′-phenyl-p-phenylenediamine (6PPD), N,N′-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine (77PD), N,N′-bis-(1-ethyl-3-methyl-pentyl)-p-phenylenediamine (DOPD), N,N′-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine, and N,N′-diphenyl-p-phenylenediamine (…). N,N′-xylyl-p-phenylenediamine (DTPD), N,N′-di-β-naphthyl-p-phenylenediamine (DNPD), N,N′-bis(1-methylheptyl)-p-phenylenediamine, N,N′-di-sec-butyl-p-phenylenediamine (44PD), N-phenyl-N-cyclohexyl-p-phenylenediamine, N-phenyl-N′-1-methylheptyl-p-phenylenediamine, and mixtures thereof, preferably N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine (6-PPD).

[0224] Commercial examples of suitable antioxidants are 6PPD from Solutia / Easyman or Santoflex manufactured by Flexsys.

[0225] The antioxidant may be present in the elastomer composition (B) in a total amount preferably from 0.1 phr to 6 phr, more preferably from 0.5 phr to 4 phr.

[0226] In the self-supporting tire of the present invention, the sidewall reinforcement insert (A) is preferably composed of vulcanized elastomer rubber compound (A).

[0227] The characteristics of vulcanized elastomer compound (A) can be found in the following dynamic and static mechanical properties.

[0228] The shear modulus G′ of the vulcanized elastomer compound (A) is preferably at least 1.30 MPa, more preferably at least 1.40 MPa, and even more preferably at least 1.60 MPa.

[0229] Preferably, the shear modulus G′ of the vulcanized elastomer compound (A) is in the range of 1.25 to 3.5 MPa, more preferably 1.40 to 2.5 MPa.

[0230] Preferably, the dynamic compression modulus E′ of the vulcanized elastomer compound (A) is preferably greater than 7.5 MPa, more preferably greater than 8.00 MPa, and even more preferably greater than 8.50 MPa, as measured at 23°C and 10 Hz according to the method disclosed in this specification.

[0231] Preferably, the dynamic compression modulus E′ of the vulcanized elastomer compound (A) at 23°C and 10Hz ranges from 7.50 to 15.00 MPa, more preferably from 8.00 to 10.00 MPa, and even more preferably from 8.00 to 9.50 MPa.

[0232] Preferably, the Tanδ value of the vulcanized elastomer compound (A) is greater than 0.040, more preferably greater than 0.045, and even more preferably greater than 0.050, as measured at 70°C and 10Hz according to the RPA method disclosed in this specification.

[0233] Preferably, the Tanδ value of the vulcanized elastomer compound (B), measured at 70°C and 10Hz according to the RPA method disclosed in this specification, is lower than the Tanδ value of the vulcanized elastomer compound (A).

[0234] Preferably, a vulcanized elastomer compound (A) is obtained by mixing and vulcanizing an elastomer composition (A), wherein the elastomer composition (A) comprises at least:

[0235] At least one diene elastomer polymer with a phr of -100 phr

[0236] - At least one reinforcing filler, comprising at least 25% by weight relative to the total weight of the composition.

[0237] - At least 0.1 phr of the at least one vulcanizing agent.

[0238] The elastomer composition (A) comprises at least 100 phr of at least one diene elastomer polymer as defined above for the elastomer composition (B).

[0239] Preferably, the elastomer composition (A) contains polybutadiene in an amount greater than 20 phr, more preferably greater than 30 phr, and even more preferably greater than 40 phr.

[0240] Preferably, the elastomer composition (A) comprises:

[0241] -20 to 70 phr synthetic or natural polyisoprene or mixtures thereof, and

[0242] Polybutadiene ranging from -30 to 80 phr.

[0243] More preferably, the elastomer composition (A) comprises:

[0244] -30 to 60 phr synthetic or natural polyisoprene or mixtures thereof, and

[0245] Polybutadiene with a phr of -40 to 70.

[0246] The term "polyisoprene" refers to isoprene polymers and copolymers.

[0247] The term "polybutadiene" refers to butadiene polymers and copolymers.

[0248] The elastomer composition (A) contains, with respect to the total weight of the elastomer composition (A), preferably at least 25% by weight, more preferably at least 28% by weight or 30% by weight, at least one reinforcing filler as defined above.

[0249] Preferably, in the elastomer composition (A), the reinforcing filler is present in a total amount of 25% to 40% by weight, more preferably 27% to 35% by weight, relative to the total weight of the elastomer composition (A).

[0250] The elastomer composition (A) may further comprise one or more other components, and the amounts thereof are as described above for the elastomer composition (B).

[0251] Depending on the elastomer composition (A), those skilled in the art can adjust the composition and crosslinking conditions of the vulcanizing package to impart a degree of crosslinking to the vulcanized elastomer compound (A) commensurate with the shear modulus value G′ set according to the present invention.

[0252] In a preferred embodiment, the self-supporting tire of the present invention is characterized in that,

[0253] The sidewall reinforcing insert on side (A) is composed of an elastomeric material (A) having a shear modulus G′ of at least 1.30 MPa, preferably at least 1.40 MPa, more preferably at least 1.60 MPa, while the sidewall reinforcing insert on side (B) is composed of an elastomeric material (B) having a shear modulus G′ of less than 1.10 MPa, preferably less than 1.05 MPa, more preferably less than 1.0 MPa or 0.95 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz, and 9% strain according to the method disclosed in this specification.

[0254] In the self-supporting tire according to the invention, the sidewall reinforcement insert on the (B) side and the sidewall reinforcement insert on the (A) side may have the same maximum thickness (Li-A = Li-B) or different maximum thicknesses.

[0255] In one embodiment of the self-supporting tire of the present invention, the sidewall reinforcement inserts on sides (A) and (B) have the same thickness. In such an embodiment, depending on the desired performance, the tire's cross-sectional height, its load and speed index, the two reinforcement inserts may have a maximum axial extension Li, for example, from a minimum of 3 mm to a maximum of 14 mm, preferably 5 mm to 12 mm, and more preferably 7 mm to 10 mm, measured in a direction perpendicular to a plane Ti tangent to the outer surface of the sidewall reinforcement insert.

[0256] For example, in the case of a conventional self-supporting tire with a nominal section height of 80 mm, the thickness of the sidewall reinforcement insert typically ranges from 3 to 5 mm, from 5 to 7 mm in the case of a nominal section height of 100 mm, and from 7 to 10 mm in the case of a nominal section height of 130 mm.

[0257] In one embodiment of the self-supporting tire of the present invention, the reinforcing inserts on the inner and outer sides may have different maximum thicknesses.

[0258] In the first case, the maximum axial extension of the sidewall reinforcement insert on side (B) is preferably at least 5%, preferably at least 10%, greater than the maximum axial extension of the sidewall reinforcement insert on side (A), especially in the case of a poor camber angle, to further improve rolling resistance.

[0259] In such an implementation, the sidewall reinforcement insert on the (B) side may have a maximum axial extension, for example, from a minimum of 4 mm to a maximum of 14 mm, preferably from a minimum of 5 mm to a maximum of 12 mm, while the sidewall reinforcement insert on the (A) side may have a maximum axial extension, for example, from a minimum of 3 mm to a maximum of 13 mm, preferably from a minimum of 4 mm to a maximum of 11 mm.

[0260] In the second case, the maximum axial extension of the sidewall reinforcement insert on side (B) is preferably at least 5%, and preferably at least 10%, smaller than the maximum axial extension of the sidewall reinforcement insert on side (A) to improve flat-running performance, especially at very high camber angles.

[0261] In such an implementation, the sidewall reinforcement insert on the (B) side may have a maximum axial extension, for example, from a minimum of 3 mm to a maximum of 13 mm, preferably from a minimum of 4 mm to a maximum of 12 mm, while the sidewall reinforcement insert on the (A) side may have a maximum axial extension, for example, from a minimum of 4 mm to a maximum of 14 mm, preferably from a minimum of 5 mm to a maximum of 13 mm.

[0262] In the tires of the present invention, particularly when the elastomer composition (B) contains particularly low amounts of reinforcing filler and / or high modulus elastomer polymer, the maximum axial extension of the sidewall reinforcing insert on the (B) side can be increased in the total thickness, for example by 1 mm, up to a maximum of 14 mm, preferably not exceeding 11 mm, and more preferably not exceeding 10 mm.

[0263] Sidewall reinforcement inserts (A) and (B) can be arranged inside the sidewall structure of each sidewall of the tire, from the bead portion to the shoulder portion.

[0264] In one embodiment of this tire, the sidewall reinforcement insert is located axially inside the tire carcass structure.

[0265] In one embodiment of this tire, the sidewall reinforcement insert is disposed at a location axially outside the tire carcass structure.

[0266] Examples of sidewall-reinforced inserts (A) and (B) are Figure 1 The components (113A) and (113B) are shown.

[0267] A preferred embodiment of the self-supporting tire of the present invention includes:

[0268] - Carcass structure, the carcass structure having opposing side edges associated with a corresponding annular anchoring structure;

[0269] - A belt structure applied at a location radially outside the tire carcass structure;

[0270] - A tire crown applied at a position radially outside the belt structure;

[0271] - A pair of sidewall structures, each sidewall structure comprising a sidewall extending in a position axially outside the carcass structure and radially extending between one of the annular anchoring structures and the axially outside portion of the crown;

[0272] - A layer of impermeable elastomeric material extending at the innermost radial position of the tire and at least at the tread is called the liner; and

[0273] - A pair of sidewall reinforcing inserts, each insert being incorporated into the corresponding sidewall structure at a position axially inward of each sidewall and axially outward of the impermeable elastomer material layer, characterized in that...

[0274] The sidewall reinforcement insert on side (A) comprises an elastomer compound (A) with a shear modulus G′ of at least 1.25 MPa.

[0275] Meanwhile, the sidewall reinforcement insert on side (B) comprises an elastomer compound (B) with a shear modulus value G′ less than 1.25 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz, and 9% strain according to the method disclosed in this specification.

[0276] In a preferred embodiment, the liner extends from one bead structure to another bead structure.

[0277] When applicable, all preferred embodiments described above for tires of the present invention generally also specifically characterize tires of the present invention including the liner.

[0278] The self-supporting tire according to the invention may further include a liner.

[0279] Lining (see) Figure 1 The element (112a) in the figure is an elastomeric material layer arranged in a position on the radially outer side of the liner, i.e., between the liner and the carcass structure, preferably for the entire extension of the liner.

[0280] In one embodiment of the tire of the present invention, the liner and the underliner extend only for the tread portion.

[0281] In one embodiment of the tire of the present invention, the underliner and liner extend from one bead structure to another bead structure.

[0282] In one embodiment of the tire of the present invention, at least the underliner extends from one bead structure to another bead structure.

[0283] In one embodiment of the tire of the present invention, the liner extends through the tread portion, while the underliner extends from one bead structure to another.

[0284] Typically, the liner consists of an elastomer compound with a high content of reinforcing fillers and therefore a high viscosity, in order to protect the liner from any movement of the carcass cords during tire construction and tire configuration.

[0285] In a preferred embodiment of the self-supporting tire of the present invention, the applicant has found that the liner can advantageously comprise the aforementioned vulcanized elastomer compound (B), low-modulus compound, low content of reinforcing filler and reduced viscosity or preferably composed thereof, and has unexpected advantages, particularly in terms of increased flat running distance with the same low rolling resistance (see Table 3 for the performance and related comments of tires PN4 and PN5).

[0286] Therefore, in a preferred embodiment, the self-supporting tire of the present invention comprises:

[0287] - Carcass structure, the carcass structure having opposing side edges associated with a corresponding annular anchoring structure;

[0288] - A belt structure applied at a location radially outside the tire carcass structure;

[0289] - A tire crown applied at a position radially outside the belt structure;

[0290] - A pair of sidewall structures, each of the pair of sidewall structures including a sidewall extending in a position axially outside the carcass structure and radially extending between one of the annular anchoring structures and the axially outside portion of the crown;

[0291] - A layer of impermeable elastomer material extending at least at the crown of the tire at its innermost radial position is called the liner;

[0292] - A pair of sidewall reinforcement inserts, each insert being embedded in the corresponding sidewall structure at an axially inward location in each sidewall, and

[0293] - An elastomeric material layer, referred to as the underliner, is located radially outside the liner, radially inside the carcass structure, and axially inside the sidewall reinforcement insert, and preferably extends beyond the extent of the liner's extension.

[0294] Its features

[0295] The sidewall reinforcement insert on side (A) is composed of an elastomer compound (A) with a shear modulus G′ of at least 1.25 MPa, and

[0296] The sidewall reinforcement insert and the liner on side (B) are composed of an elastomer compound (B) with a shear modulus value G′ less than 1.25 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz and 9% strain according to the method disclosed in this specification.

[0297] Preferably, when present, the thickness of the underlayer liner is 0.4 mm to 2 mm, more preferably 0.5 mm to 1 mm.

[0298] In one embodiment of the tire of the present invention, the side reinforcement insert is located between the underliner and the tire carcass structure.

[0299] In a more preferred embodiment, the self-supporting tire according to the present invention comprises:

[0300] - Carcass structure, the carcass structure having opposing side edges associated with a corresponding annular anchoring structure;

[0301] - A belt structure applied at a location radially outside the tire carcass structure;

[0302] - A tire crown applied at a position radially outside the belt structure;

[0303] - A pair of sidewall structures, each sidewall structure comprising a sidewall extending in a position axially outside the carcass structure and radially extending between one of the annular anchoring structures and the axially outside portion of the crown;

[0304] - A layer of impermeable elastomer material extending at least at the crown of the tire at its innermost radial position is called the liner;

[0305] - A pair of sidewall reinforcement inserts, each insert being embedded in the corresponding sidewall structure at an axially inward location in each sidewall, and

[0306] - An elastomeric material layer, referred to as the underlay, is located radially outside the liner, radially inside the carcass structure, and axially inside the sidewall reinforcement insert, and preferably extends beyond the extension of the liner.

[0307] Its features

[0308] The sidewall reinforcement insert on side (A) is composed of an elastomer compound (A) with a shear modulus G′ of 1.30 MPa, preferably at least 1.40 MPa, and more preferably at least 1.60 MPa.

[0309] The sidewall reinforcing insert and the liner on side (B) preferably comprise an elastomer compound (B) with a shear modulus value G′ of less than 1.10 MPa, more preferably less than 1.05 MPa, and more preferably less than 0.95 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz, and 9% strain according to the method disclosed herein.

[0310] In this preferred embodiment, the maximum axial extension of the inner and outer sidewall reinforcement inserts of the tire, measured in a direction perpendicular to the plane Ti tangent to the outer surface of the sidewall reinforcement insert, is between 4 mm and 14 mm, more preferably between 5 mm and 12 mm.

[0311] In a preferred embodiment of the self-supporting tire of the present invention, a vulcanized elastomer compound (B) is obtained by mixing and vulcanizing an elastomer composition (B), said elastomer composition (B) comprising at least:

[0312] At least one diene elastomer polymer with a phr of -100 phr

[0313] - At least one reinforcing filler, relative to the total weight of the elastomer composition, comprises less than 30% by weight, preferably less than 27% by weight, more preferably less than 25% by weight or 20% by weight.

[0314] - At least 0.1 phr of the at least one vulcanizing agent.

[0315] In a particularly preferred embodiment, the reinforcing filler comprises sepiolite and silica fibers.

[0316] In the self-supporting tire according to the invention, additional tire components, such as a sound insulation system, sealant, or sensor, may optionally be applied to the innermost radial surface of the liner.

[0317] Preferably, the self-supporting tire of the present invention is non-directional, i.e., no preferred rolling direction is etched on the tire sidewall, and the tread pattern is designed so that the tread performance is of the same order of magnitude as a tire used in one of the two possible rolling directions. In fact, using a non-directional tire allows for simplified production. A single non-directional tire model according to the invention can be used on the same axle. On the other hand, if the tire is directional, it is necessary to make the tires according to the invention different depending on whether they are mounted on the left or right side of the vehicle.

[0318] Preferably, the self-supporting tire of the present invention is mounted on a vehicle by positioning the reinforcing insert on the side having the lowest modulus (B) toward the side subjected to the greatest strain (B side).

[0319] For example, in the case of a rear tire with a high negative camber angle, the tire should be installed such that the reinforcing insert on the side with the lower modulus (B) faces inward toward the interior of the vehicle.

[0320] On the other hand, in the case of a front tire with zero or near-zero camber, the tire can be mounted such that the reinforcing insert on the side with the lowest modulus (B) is positioned toward the outside of the vehicle.

[0321] Preferably, the self-supporting tire of the present invention is a tire for automobiles.

[0322] In one embodiment, the self-supporting tire of the present invention is a rear tire mounted on a vehicle, wherein side (B) (i.e., the side including the sidewall reinforcement insert) faces inward, the sidewall reinforcement insert comprising an elastomeric compound (B) with a shear modulus G′ value of less than 1.25 MPa.

[0323] In another embodiment, the self-supporting tire of the present invention is a front tire that can be mounted on a vehicle, wherein side (B) (i.e., the side including the sidewall reinforcement insert) preferably faces outward, the sidewall reinforcement insert comprising an elastomeric compound (B) with a shear modulus G′ value of less than 1.25 MPa.

[0324] The self-supporting tire of the present invention is suitable for four-wheeled vehicles used on roads, as a tire suitable for equipping small general-purpose cars, medium and high-powered passenger cars (maximum cord size, for example, from 145 mm to 355 mm).

[0325] These tires are preferably mounted on rims having a bearing diameter of 13 inches or greater, preferably no greater than 24 inches, and more preferably 16 to 23 inches. Typically, the tires according to the invention can be tires for passenger vehicles, including automobile tires (e.g., high-performance tires defined below) and tires for light transport vehicles (e.g., vans, campervans, pickup trucks) with a gross vehicle weight typically equal to or less than 3500 kg under full load. Therefore, tires for heavy transport vehicles are excluded.

[0326] The self-supporting tire of the present invention may be an HP (high performance) or UHP (ultra-high performance) tire, which is designed to equip vehicles used for primary transportation of people, such as cars, vans, family cars, SUVs (sports utility vehicles) and / or CUVs (cross-traffic vehicles), and generally allows for high-speed driving.

[0327] High-performance tires and ultra-high-performance tires, especially those that allow speeds of at least 160 km / h, above 200 km / h, and up to 300 km / h.

[0328] In this specification, when referring to tires for passenger cars, this includes both automobile tires (such as the high-performance tires defined above) and tires for light transport vehicles (such as vans, campervans, and pickup trucks) with a gross vehicle weight of 3500 kg or less when fully loaded. Therefore, tires for heavy transport vehicles are excluded.

[0329] Examples of such tires are those belonging to the “T,” “U,” “H,” “V,” “Z,” “W,” and “Y” categories according to ETRTO standards (European Tire and Rim Technology Organization), and especially racing tires (racing tires) for high-powered four-wheeled vehicles. Typically, tires in these categories have a section width equal to or greater than 185 mm, preferably 195 mm to 385 mm, and more preferably 195 mm to 355 mm. These tires are preferably mounted on rims having a support diameter equal to or greater than 13 inches, preferably no greater than 24 inches, and more preferably between 16 inches and 23 inches.

[0330] SUVs and CUVs refer to vehicles with a raised profile, typically four-wheel drive, and an engine displacement generally greater than or equal to 1800cc, more preferably 2000cc to 6200cc. Preferably, these vehicles have a mass greater than 1,400kg, more preferably 1500kg to 3000kg.

[0331] The tire of this invention can be used as a summer or winter or "all-season" tire (a tire that can be used in all seasons).

[0332] Description of tires according to the present invention

[0333] Other features and advantages of the self-supporting tire according to the invention will become apparent from the following description of a preferred embodiment given by non-limiting example, with reference to the appendix. Figure 1 Please note that the accompanying diagram is not drawn to scale.

[0334] Figure 1 This is a radial cross-sectional view of a preferred embodiment of the self-supporting tire according to the present invention.

[0335] exist Figure 1 In the figures, reference numeral (100) indicates a self-supporting tire for a vehicle wheel according to a preferred embodiment of the invention. The letters A and B represent the A side and B side of the tire, respectively.

[0336] exist Figure 1 In the embodiment shown, the tire (100) is a type used for motor vehicles.

[0337] exist Figure 1 In this context, "a" indicates the axial direction, and "X" indicates the radial direction; specifically, XX represents the outline of the equatorial plane. For simplicity, Figure 1 Only a portion of the tire is shown; the rest, not shown, are identical and arranged symmetrically with respect to the equatorial plane “XX”.

[0338] The tire (100) for a four-wheeled vehicle includes at least one carcass structure, the carcass structure including at least one carcass layer (101) having opposing end flaps that engage with a corresponding annular anchoring structure (102), the annular anchoring structure (102) being referred to as a bead core, the bead core possibly being associated with a filler strip (104).

[0339] The tire region including the bead core (102) and the filler strip (104) forms a bead structure (103), which is intended to anchor the tire to the corresponding mounting rim (not shown).

[0340] The carcass structure is typically radial, meaning that the reinforcing element of at least one carcass ply (101) lies on a plane including the axis of rotation of the tire and substantially perpendicular to the tire's equatorial plane. The reinforcing element is typically composed of fabric cords. Each bead structure is associated with the carcass structure by folding the opposing lateral edges of at least one carcass ply (101) rearward around an annular anchoring structure (102) to form a shape such that… Figure 1 The so-called tire body wing (101a) shown.

[0341] In one embodiment, a second carcass layer (applied at an axially outer position of the first carcass layer) can be used. Figure 1 (Not shown in the image), providing the connection between the carcass structure and the bead structure.

[0342] Wear-resistant strips (105), possibly made of elastomeric material, are arranged in the outer position of each bead structure (103).

[0343] The carcass structure is associated with a belt structure (106) comprising one or more belt layers (106a), (106b) which are arranged radially relative to each other and relative to the carcass layer, and typically have fabric and / or metal reinforcing cords bonded within a layer of elastomeric material.

[0344] These reinforcing cords can have a cross orientation relative to the circumferential direction of the tire (100). The “circumferential” direction refers to the direction that is generally facing the direction of rotation of the tire.

[0345] At least one zero-degree reinforcement layer (106c), commonly referred to as a “0° belt”, may be applied at the radially outermost position of the belt layers (106a) and (106b), which typically incorporate a plurality of elongated reinforcing elements, typically metal or fabric cords, oriented in a substantially circumferential direction, thereby forming an angle of a few degrees (e.g., between about 0° and 6°) with a direction parallel to the tire equatorial plane, and are coated with an elastomeric material.

[0346] The tire (100) may also include an additional belt layer (not shown) disposed between the carcass structure (101) and the radially innermost belt layer of the aforementioned belt layers (106a) and (106b), and include a plurality of reinforcing cords having an inclined orientation of 90° relative to the circumferential direction of the tire (100) or relative to the equatorial plane XX of the tire (100).

[0347] The crown (109) is applied at a radially outer position in the belt layer structure (106).

[0348] Furthermore, corresponding sidewalls (108) of elastomeric material are applied at axially external locations on the side surfaces of the carcass structure, each sidewall extending from one of the side edges of the tread (109) at the corresponding bead structure (103).

[0349] A rubber layer (112), commonly referred to as a “liner,” may be present in a radially inner location of the carcass layer (101), providing the tire with the necessary airtightness for inflation. According to a preferred embodiment of the invention, an elastomeric material layer, namely a base liner (112a), may also be provided in a radially outer location of the liner (112).

[0350] The liner (112a) may be composed of a vulcanized elastomer compound (B) with a shear modulus value G′ less than 1.25 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz, and 9% strain according to the method disclosed in this specification.

[0351] The sidewall (108) of the tire (100) also includes a pair of corresponding sidewall reinforcement inserts (113A) and (113B).

[0352] The sidewall reinforcement insert (113) is incorporated into the sidewall structure (108) at a location on the axially outer side of the liner (112a) and on the axially inner side of the carcass layer (101).

[0353] exist Figure 1 In the embodiment shown, the tire sidewall reinforcement inserts (113A) and (113B) have the same maximum axial extension L. i This is in the plane T that is tangent to the outer surface of the corresponding sidewall reinforcing insert (113). i Measured in the vertical direction.

[0354] The tire sidewall reinforcement insert (113B) is composed of a vulcanized elastomer compound (B) with a shear modulus value G′ less than 1.25 MPa, while the tire sidewall reinforcement insert (113A) is composed of a vulcanized elastomer compound (A) with a shear modulus value G′ of at least 1.25 MPa, wherein the modulus G′ is measured at 70°C, 10 Hz, and 9% strain according to the method disclosed in this specification.

[0355] In the radially outer position, the tread (109) has a rolling surface (109a) designed to contact the ground. This is achieved through a lateral notch ( Figure 1 (Not shown) Circumferential grooves (of various shapes and sizes) connecting to define a plurality of blocks distributed on a rolling surface (109a) are typically formed on the surface (109a), which, for simplicity, is... Figure 1 The middle part is represented as smooth.

[0356] Optionally, a strip of elastomeric material (110) (often referred to as a “micro-sidewall”) may be provided in the connection region between the sidewall (108) and the crown (109), which is typically obtained by co-extrusion with the crown (109) and allows for improved mechanical interaction between the crown (109) and the sidewall (108).

[0357] The rigidity of the tire sidewall (108) can be improved by providing a reinforcing layer (120) to the bead structure (103), commonly referred to as the outer bead wrap or additional strip insert.

[0358] The outer bead wrap (120) is a reinforcing layer that is wound around the corresponding bead core (102) and filler strip (104) to at least partially surround the bead core and the filler strip. The reinforcing layer is disposed between the at least one carcass layer (101) and the bead structure (103). Typically, the outer bead wrap is in contact with the at least one carcass layer (101) and the bead structure (103).

[0359] The outer sheath fabric (120) typically includes multiple fabric cords incorporated within an elastomer material layer.

[0360] The tire's reinforcing ring structure or bead (103) may include an additional protective layer, commonly referred to by the term "bead wrap" (121) or protective strip, and has the function of increasing the rigidity and integrity of the bead structure (103).

[0361] The bead wrap (121) typically comprises multiple cords incorporated within a rubber layer of an elastomeric material. These cords are typically made of textile or metallic materials.

[0362] Elastomer material layers or sheets may be arranged between the belt structure and the carcass structure (not shown).

[0363] The tire (100) described above can be constructed by assembling corresponding semi-finished products of components suitable for forming a tire on a forming drum (not shown) by at least one assembly device.

[0364] At least a portion of the components intended for forming the tire carcass structure can be constructed and / or assembled on the forming drum. More specifically, the forming drum is adapted to first receive the liner, followed by the underliner and sidewall reinforcement inserts, and then the carcass structure. Thereafter, a device (not shown) coaxially engages one of the annular anchoring structures surrounding each end flap, positioning the outer sleeve, including the belt structure and the tire crown, in a coaxially centered position around the cylindrical carcass sleeve, and shaping the carcass sleeve according to the annular configuration by radial expansion of the carcass structure so that it is applied against the radially inner surface of the outer sleeve.

[0365] After the raw tire is constructed, it is typically molded and vulcanized to determine the structural stability of the tire through the crosslinking of the elastomer composition, as well as to impart the desired tread pattern on the tread and any distinguishing graphic symbols on the sidewall.

[0366] The following embodiments are provided for illustrative and non-limiting purposes only. Example

[0367] Evaluation methods

[0368] Static mechanical properties (CA1 load, CR tensile strength, AR% elongation at break at 100% elongation) were measured according to UNI 6065:2001 standard for elastomer material samples vulcanized at 23°C for 10 minutes at 170°C.

[0369] Compression dynamic mechanical properties E′ and Tanδ Measurements were performed using an Instron Model 1341 dynamic apparatus in a tension-compression mode as described herein. Test pieces of cross-linked material with a cylindrical shape (length = 25 mm; diameter = 14 mm) were preloaded and compressed to 25% of their initial length with longitudinal strain, and held at a predetermined temperature of 23°C for the entire duration of the test. The test pieces were subjected to dynamic sinusoidal stress with an amplitude of ±3.5% relative to their preloaded length at a frequency of 10 Hz. Dynamic mechanical properties are expressed as dynamic elastic modulus (E′) and Tanδ (loss factor). The Tanδ value is calculated as the ratio between the viscous dynamic modulus (E′) and the dynamic elastic modulus (E′).

[0370] Dynamic mechanical properties of shear dynamic modulus G′ and Tanδ Use materials such as ASTM D6601-19 Figure 1The Alpha Technologies RPA2000 oscillating chamber rheometer (rubber process analyzer) with the chamber geometry described above was evaluated using the following methods:

[0371] 1) Obtaining a volume ranging from 4.6 to 5 cm³ by stamping a sheet of the green vulcanizable elastomer composition to be characterized with a thickness of at least 5 mm. 3 The test sample is approximately cylindrical.

[0372] 2) Preheat the chamber of the RPA device to 170°C;

[0373] 3) Load the sample into the chambers of the RPA device and seal the chambers. Insert two films between the sample of the green vulcanizable elastomer composition and each chamber of the RPA device to protect the chamber itself: a 25-micron nylon 6.6 cast film in contact with the rubber compound, and a 23-micron polyester film in contact with the chamber of the RPA device;

[0374] 4) Then, the sample was vulcanized at 170℃ for a fixed time of 10 minutes, and the vulcanization curve was recorded at the same time. That is, the sample was subjected to sinusoidal strain with an amplitude of 7% and a frequency of 1.67Hz throughout the entire vulcanization duration.

[0375] 5) Then the chamber temperature of the RPA device is raised to 70°C. After the chamber temperature is set to 70°C for 10 minutes, a series of dynamic measurements are performed by applying sinusoidal stress to the sample in a torsional manner at a fixed frequency of 10Hz and an amplitude gradually increased from 0.3% to 10% for each condition.

[0376] 6) Dynamic measurements were performed by applying sinusoidal stress to the sample in a torsional manner at a fixed frequency of 10 Hz and an amplitude of 9% at 70 ℃. The results were expressed as the average values ​​measured over the 20 measurement cycles, in the form of shear modulus G′ and Tanδ (the ratio between viscous modulus G″ and G′, Tanδ = G″ / G′).

[0377] Rolling resistance (RR) assessment

[0378] Rolling resistance (RR) was measured on sample tires manufactured in accordance with UNECE reg.117Rev.4 Annex 6 - ISO 28580:2018 (paragraph 4b (torque method)) - Notification No. 2011-237 (Korea). The rolling resistance coefficient is expressed in N / kN.

[0379] Then, a relative rolling resistance index is assigned to the tires tested in this way. This index is equal to the ratio of the rolling resistance measured for the tire in question relative to a reference tire. The lower the value of this index, the lower the rolling resistance of the tested tire, and therefore the better its performance.

[0380] The results of the tests conducted are reported in Tables 3 and 4. In these tables, a decrease in the rolling resistance value (e.g., from 100 to 92) indicates improved performance, while an increase in the value (e.g., from 100 to 104) indicates deterioration.

[0381] Evaluation of travel distance under deflation conditions (leakage protection test)

[0382] The BMW 5 Series is equipped with four tires, a reference tire, a comparative tire, or the tire of the present invention, depending on the tire group under consideration (see Example 2 below, PN1-PN5).

[0383] A flat-road test was performed on each tire group by fully deflating the left rear tire and driving at a speed not exceeding 80 km / h on a mixed route until the tire showed obvious damage. However, if no damage occurred, the test was stopped after 120 km.

[0384] The test was repeated twice for each tire group, and the results were averaged.

[0385] To compare tire performance, for each group of tires being compared, the "RF" distance index 100 is designated as the reference tire.

[0386] The relative “RF” index is then assigned to the other tires in the same group. This relative “RF” index corresponds to the ratio between the distance measured for the test tire under flat driving conditions and the distance of the reference tire, which has been set to 100, in a close comparison.

[0387] The results are shown in Tables 3 and 4.

[0388] In these tables, maintaining or moderately reducing the value in flat driving results (e.g., from 100 to 75) indicates fairly or perfectly acceptable performance, even if it deteriorates slightly. An increase in the value (e.g., from 100 to 120) indicates improved performance, i.e., longer distance, while a significant decrease in the value (e.g., less than 65) indicates unacceptable performance.

[0389] Example 1: Preparation of Elastomer Compounds

[0390] The compositions described in Table 1 below are prepared as elastomeric compositions for sidewall reinforcing inserts and for bottom liners:

[0391] Table 1: Elastomer Compositions (phr)

[0392] NR --- 80 80 --- IR 40 20 20 90 BR 60 --- --- --- SBR --- --- --- 10 CB 32.0 --- --- 52.0 SilSep1 --- --- 16.0 --- SilSep3 --- 15.0 --- --- SilSep2 20.0 --- --- --- silicon dioxide --- 18.0 --- 5.0 stearic acid 2.0 2.0 2.0 1.0 Zinc oxide 4.0 3.6 4.0 3.0 TESPT 50% on CB 5.0 6.0 4.0 --- TMQ 1.0 1.0 1.0 --- 6-PPD 2.0 2.0 2.0 1.5 TBBS 2.5 1.9 1.9 3.0 Isobutyl TUADS 0.5 -- 0.3 --- Insoluble sulfur 67% 2.3 3.6 3.6 3.4 All Phrases 171.3 153.1 134.8 168.9 Total filler (%) 32％ 24％ 13％ 34％

[0393] in

[0394] IR: Synthetic polyisoprene (SKI-3Nizhnekamskneftekhim); NR: Natural rubber (Standard Thai Rubber STR 20-Thaiteck Rubber); BR: Polybutadiene (Europrene) Europe); SBR: Europrene 1500 from Versalis; CB: Birla Carbon N550; Silica: ZEOSIL 1115HP (Solvay); SilSep1: White filler in M2 microspheres prepared according to Example 1 of patent application WO2019106562A1; SilSep2: White filler in M6 microspheres prepared according to Example 3 of patent application WO2019106562A1: Stearic acid: STEARINA N (SOGIS); Zinc oxide: ZnO-80 (RheinChemie); TESPT: A mixture of bis(triethoxysilylpropyl)tetrasulfide (TESPT 50%) loaded on carbon black (50%), produced by Evonik Industries AG, Germany; TMQ (anti-aging): Polymerized NAUGARD Q (CHEMTURACORPORATION);

[0395] 6-PPD (antioxidant): N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (Santoflex™ 6PPD-Eastman); TBBS (accelerator): N-tert-butyl-2-benzothiazolylsulfonamide ( NZ / EGC-Lanxess); Isobutyl TUADS (isobutyl thiuram disulfide) accelerator: produced by RTVanderbilt; Sulfur (vulcanizing agent): 67% oleate of insoluble sulfur (Solfotecnica).

[0396] Starting with the elastomer compositions shown in Table 1, the corresponding elastomer compounds are prepared according to the following method.

[0397] In the first step (1), all components except the vulcanizing agent and accelerator are introduced. Mixing continues for a maximum of 5 minutes, reaching a temperature of approximately 145°C. Subsequently, in the second test (2) conducted again using an internal mixer, the vulcanizing agent and accelerator are added, and mixing continues for approximately 4 minutes while maintaining the temperature below 100°C. The rubber compound is then unloaded. After cooling and at least 12 hours from preparation, some samples of the rubber compound are vulcanized in a press at 170°C for 10 minutes to obtain specimens suitable for mechanical characterization.

[0398] Characterization of rubber compounds

[0399] The main static and dynamic properties of the above-mentioned elastomer compounds, measured by the above method, are shown in Table 2 below:

[0400] Table 2

[0401]

[0402]

[0403] Example 2: Production of self-supporting tires

[0404] To evaluate the performance of self-supporting tires with sidewall reinforcement inserts of different stiffness according to the present invention in terms of rolling resistance and maximum mileage under deflation conditions, a group of eight tires having the characteristics shown in Tables 3 and 4 were prepared for each of tires PN1-PN5, compared with reference tires and comparison tires with reinforcement inserts of equal stiffness.

[0405] Each tire type includes two sidewall reinforcement inserts on the axially outer side of the impermeable elastomer material layer (liner) and on the axially inner sidewall. The sidewall reinforcement inserts may differ in their rubber composition, but they have the same thickness (Li-B equals Li-A) and the same shape, as outlined in Table 3 below. In vehicle testing, asymmetric self-supporting tires are assembled with the sidewall reinforcement inserts (inserts B) of the lower module facing inwards. Tire groups PN1-PN5 are then compared under the same operating conditions.

[0406] Preparation of sample tires PN1-PN5

[0407] The applicant produced a sample of a self-supporting tire with a size of 245 / 45R18 100Y XL, wherein the butyl rubber liner extends only at the tread and the underliner extends from the bead to the bead, as follows:

[0408] -PN1: Refers to a self-supporting pneumatic tire, which includes a sidewall reinforcement insert on side A and a sidewall reinforcement insert on side B, both of which are composed of composition C1, have the same shape and size, and have a maximum thickness (Li) of 7 mm, and have a liner composed of composition C4 with a maximum thickness of 0.9 mm.

[0409] -PN2: Compared to a self-supporting pneumatic tire, it includes a sidewall reinforcement insert on side A and a sidewall reinforcement insert on side B, both of which are composed of composition C2, are the same in shape and size as the previous one, and have a liner composed of composition C4.

[0410] -PN3: Compared to a self-supporting tire, it includes a sidewall reinforcement insert that is the same in shape and size as the previous one, but wherein the sidewall reinforcement insert on side A is composed of composition C1, and the sidewall reinforcement insert on side B is composed of composition C2 and has a liner composed of composition C4.

[0411] -PN4: The self-supporting tire of the present invention includes a sidewall reinforcing insert that is the same in shape as the aforementioned R, but with a maximum thickness Li increased by 14%, and respectively, the sidewall reinforcing insert on side A is composed of composition C1; and the sidewall reinforcing insert on side B is composed of composition C3 and has a liner composed of composition C4;

[0412] -PN5: The self-supporting tire of the present invention includes a sidewall reinforcing insert that is the same in shape as the aforementioned R but with a maximum thickness Li increased by 14%, wherein the sidewall reinforcing insert on side A is composed of composition C1; and the sidewall reinforcing insert on side B is composed of composition C3 and has a liner composed of composition C3.

[0413] All of the above-mentioned tires are produced by assembling green parts and then molding and vulcanizing them.

[0414] Table 3 below shows the main characteristics of self-supporting tires PN1-PN5, their relative performance under deflation conditions, rolling resistance, and maximum mileage, as evaluated according to the above method:

[0415] Table 3

[0416] Composition of insert A (outer side) C1 C2 C1 C1 C1 Composition of insert B (inner side) C1 C2 C2 C3 C3 Relative thickness of insert 100 100 100 114 114 Composition of the lining C4 C4 C4 C4 C3 relative RR 100 93 92 95 95 relative to RF 100 17 36 119 203

[0417] Insert B has the same thickness as insert A; the relative thickness of the insert represents the thickness Li of the insert, which is remeasured by setting the thickness of the insert of tire PN1 to 100; RR represents the relative rolling resistance reparameterized by setting the rolling resistance of tire PN1 to 100; RF (leakage protection) represents the maximum mileage under deflation / flat running conditions, a relative value reparameterized by setting the flat running of tire PN1 to 100.

[0418] Table 3 shows the effects of replacing conventional rigid elastomer compound (C1) with softer rubber compound (C2, C3) as the sidewall reinforcement insert of the inner sidewall B in a self-supporting tire, replacing conventional rigid elastomer compound (C4) with softer rubber compound (C3) as the liner, and changing the thickness of the sidewall reinforcement insert on the performance of interest.

[0419] In particular, by comparing compositions C1 with C2 and C3 (Tables 1 and 2), it was observed that by changing the elastomer composition (e.g., by replacing polybutadiene with natural rubber and polyisoprene), by modifying and reducing fillers (from 32% to 25% and 15% respectively), and by adjusting the vulcanization system, the stiffness was significantly reduced in terms of dynamic compression / elongation modulus E′, dynamic shear modulus G′, and hysteresis (see E′ at 23°C, G′ at 70°C, and Tan D in Table 2).

[0420] Similarly, when the soft rubber compound C3 was compared with the conventional rubber compound C4 for the liner (Tables 1 and 2), it was observed that the rigidity was significantly reduced, particularly in terms of the dynamic shear modulus G′, and the hysteresis was reduced (see G′, Tan D at 70°C in Table 2).

[0421] Considering the corresponding tire data, Table 3 shows that for the same shape and size, using the same soft compound C2 for both inserts (PN2 vs. PN1), there is an interestingly significant reduction in rolling resistance; however, this is accompanied by a marked deterioration in flat driving distance, which drops from 100 to 17.

[0422] When soft rubber compound C2 was used only on the B-side insert (PN3 vs. PN1) – placed on the inner side where the stress was greatest – and the inserts were of the same shape and size, a surprising partial but insufficient recovery of the flat running distance was observed, which increased from 17 to 36, and the rolling resistance was also significantly reduced.

[0423] By using soft rubber compound C3 only for the inserts on the B side (PN4 vs. PN1) – placed on the inner side where the stress is greatest – and by increasing the thickness of the two sidewall reinforcing inserts by a limited 14% while maintaining the same shape, a surprising increase in flat travel distance from 100 to 119 was observed, which in any case was associated with a good reduction in rolling resistance from 100 to 95.

[0424] Finally, in the best implementation PN5, if in tire PN4, all other conditions being equal, the conventional rigid elastomer composition of the liner C4 is replaced by the softer elastomer composition C3 (PN5 vs. PN4), a further significant increase in flat running distance (119 to 203) is surprisingly observed, which is associated with the same significant reduction in rolling resistance (95).

[0425] In Table 4 below, PN5 and PN4 are directly compared:

[0426] Table 4

[0427]

[0428]

[0429] The rolling resistance and flat running distance of tire PN4 were set at 100. Table 4 more clearly shows the unexpected effect of the liner composition in further improving run-flat performance while still maintaining excellent rolling resistance. For this embodiment (self-supporting tire PN5), the test endpoint was reached under run-flat conditions without any visible damage to the tire.

[0430] In summary, the tests above revealed that by reducing the stiffness of the reinforcing insert on the sidewall of the self-supporting tire with the highest stress, and preferably also reducing the stiffness of the underlayment, and by increasing the thickness of the insert to a limited extent, very favorable results can be achieved in terms of the overall tire performance. This is because, compared with existing self-supporting tires (characterized by placing and / or having a large-volume, asymmetrical, and more rigid insert on the side with the highest stress), there is a significant improvement in mileage under flat driving conditions, and, more importantly, a significant improvement in rolling resistance and comfort.

Claims

1. A self-supporting tire for an automobile wheel (100), comprising: - Carcass structure, the carcass structure includes at least one carcass layer (101), the at least one carcass layer having opposing lateral edges associated with a corresponding annular anchoring structure (102); - A belt structure (106) applied at a position radially outside the carcass structure; - A crown (109) applied at a position radially outside the belt structure; - A pair of sidewall structures, each sidewall structure comprising a sidewall (108) extending in a position axially outside the carcass structure and radially extending between one of the annular anchoring structures (102) and an axially outside portion of the crown (109); - A single first sidewall reinforcement insert and a single second sidewall reinforcement insert (113A and 113B), each of the first and second sidewall reinforcement inserts being incorporated into the corresponding sidewall structure of the tire at a position axially inward of the corresponding sidewall (108). Its features The first sidewall reinforcement insert (113A) is made of an elastomeric compound A having a shear modulus value G consists of an elastomer having a modulus of elasticity A of at least 1.25 MPa, and The second sidewall reinforcement insert (113B) is composed of an elastomeric compound B having a shear modulus value G less than 1.00 MPa, said shear modulus G measured at 70°C, 10 Hz, 9% strain.

2. The tire according to claim 1, wherein the elastomer compound B is prepared by mixing and vulcanizing the elastomer composition, the elastomer composition comprising at least: At least one diene elastomer polymer with a phr of -100 phr - At least one reinforcing filler, comprising less than 30% by weight relative to the total weight of the elastomer composition, and - At least one vulcanizing agent with a concentration of at least 0.1 phr.

3. Tyre according to claim 1 or 2, wherein the value of the shear modulus G of the elastomeric compound B is less than 1.20 MPa, said modulus being measured at 70°C, 10 Hz, 9% strain. less than 1.20 MPa, said modulus being measured at 70°C, 10 Hz, 9% strain.

4. The tire according to claim 3, wherein the shear modulus value G of the elastomer compound B is... Less than 1.10 MPa.

5. The tire according to claim 4, wherein the shear modulus value G of the elastomer compound B is... Less than 1.0 MPa.

6. The tire according to claim 1 or 2, wherein the elastomer compound B is characterized by one or more of the following properties: - Dynamic compressive modulus E measured at 23°C and 10Hz The value is less than 7.50 MPa; - Tan measured at 70℃ and 10Hz The value is no greater than 0.

080.

7. The tire according to claim 6, wherein the elastomer compound B is characterized by one or more of the following properties: -Dynamic compressive modulus E The value is less than 6.00 MPa; - Tan The value is no greater than 0.

072.

8. The tire according to claim 1 or 2, wherein the elastomer compound B is prepared by mixing and vulcanizing the elastomer composition, the elastomer composition comprising at least: -70 to 100 phr synthetic or natural polyisoprene or mixtures thereof Polybutadiene from -0 to 30 phr, and - At least one reinforcing filler, comprising less than 27% by weight of the total weight of the elastomer composition.

9. The tire of claim 8, wherein the elastomer compound B is prepared by mixing and vulcanizing the elastomer composition, the elastomer composition comprising at least: -70 to 100 phr synthetic or natural polyisoprene or mixtures thereof Polybutadiene from -0 to 30 phr, and - At least one reinforcing filler, comprising less than 20% by weight of the total weight of the elastomer composition.

10. The tire according to claim 1 or 2, wherein the shear modulus G of the elastomer compound A is... It should be at least 1.30 MPa.

11. The tire according to claim 10, wherein the shear modulus G of the elastomer compound A is... It should be at least 1.60 MPa.

12. The tire according to claim 1 or 2, wherein the elastomer compound A is characterized by one or more of the following properties: - Dynamic compressive modulus E measured at 23°C and 10Hz The value is greater than 7.5 MPa; - Tan measured at 70℃ and 10Hz The value is greater than 0.

040.

13. The tire according to claim 12, wherein the elastomer compound A is characterized by one or more of the following properties: -Dynamic compressive modulus E The value is greater than 8.50 MPa; - Tan The value is greater than 0.

050.

14. The tire according to claim 1 or 2, wherein the elastomer compound A is prepared by mixing and vulcanizing an elastomer composition, the elastomer composition comprising at least: Synthetic or natural polyisoprene or mixtures thereof, ranging from -20 to 70 phr. Polybutadiene from -30 to 80 phr, and - At least one reinforcing filler, comprising at least 25% by weight of the total weight of the elastomer composition.

15. The tire of claim 14, wherein the elastomer compound A is prepared by mixing and vulcanizing an elastomer composition, the elastomer composition comprising at least: Synthetic or natural polyisoprene or mixtures thereof, ranging from -20 to 70 phr. Polybutadiene from -30 to 80 phr, and - At least one reinforcing filler, comprising at least 30% by weight of the total weight of the elastomer composition.

16. The tire according to claim 1 or 2, wherein the first sidewall reinforcement insert (113A) and the second sidewall reinforcement insert (113B) have the same maximum axial extension Li measured in a direction perpendicular to a plane Ti tangent to the outer surface of the sidewall reinforcement insert.

17. The tire of claim 16, wherein the maximum axial extension Li is 3 mm to 14 mm.

18. The tire of claim 17, wherein the maximum axial extension Li is 7 mm to 10 mm.

19. The tire according to claim 1 or 2, further comprising: - A non-porous elastomer material layer (112), referred to as the lining, extends at the innermost radial position of the tire and at least at the tread. Its features The first sidewall reinforcing insert (113A) is composed of a shear modulus value G Composed of elastomer compound A with a strength of at least 1.25 MPa, and The second sidewall reinforcing insert (113B) is composed of a shear modulus value G. The composition is an elastomer compound B with a shear modulus of less than 1.25 MPa, wherein the shear modulus G is... Measurements were taken at 70°C, 10Hz, and 9% strain.

20. The tire of claim 19, further comprising: - A non-porous elastomer material layer (112), referred to as the lining, extends at the innermost radial position of the tire and at least at the crown. - An elastomeric material layer (112a) is referred to as the underliner, which is located radially outside the liner, radially inside the carcass structure, and axially inside the sidewall reinforcement insert, and extends beyond the extension of the liner. Its features The first sidewall reinforcing insert (113A) is composed of a shear modulus value G Composed of elastomer compound A with a strength of at least 1.25 MPa, and The second sidewall reinforcing insert (113B) and the substrate (112a) are composed of a shear modulus value G. The composition is an elastomer compound B with a shear modulus of less than 1.25 MPa, wherein the shear modulus G is... Measurements were taken at 70°C, 10Hz, and 9% strain.

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