BICYCLE BANDAGE

Abstract

The invention relates to a bicycle tire comprising a tread, the tread comprising a rubber composition based on at least one elastomeric matrix comprising 50% to 95% by weight of at least one essentially unsaturated diene elastomer and 5% to 50% by weight of ethylene-propylene-diene copolymer, said EPDM, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg below -56°C; a reinforcing filler comprising silica, and a crosslinking system.

Description

Title of the invention: BICYCLE BANDAGE

[0001] The present invention relates to bicycle tires, in particular to the rubber composition of their tread which is intended to come into contact with the ground when riding.

[0002] Bicycle tire treads must meet a large number of technical requirements, often conflicting, including rolling resistance, grip on both dry and wet surfaces, wear resistance, rigidity of the cured compositions (associated with the ability to keep the handlebars straight after contact with a branch or stone or contact with the ground after a jump), as well as the curing properties and viscosity of the compositions in the raw state (associated with the ease of industrial implementation of the compositions, or processability).

[0003] Ozone is known to have adverse effects on rubber articles, typically producing glazing and / or cracking on the surface of these articles. In the case of bicycle tires, this cracking can be detrimental to the performance of the tire, particularly with regard to its durability, thus potentially reducing the tire's lifespan, but also with regard to maintaining inflation pressure.

[0004] To combat these harmful effects, ozone-blocking waxes, well known to those skilled in the art, are commonly used. However, the use of a large quantity of ozone-blocking wax can cause blooming of the rubber compounds, which is undesirable for users. Furthermore, given the thinness of the layers constituting the bandage, the amount of ozone-blocking wax present may not be sufficient to counteract the effects of ozone.

[0005] Ethylene-propylene-diene (EPDM) copolymers are known for their resistance to ozone degradation. However, the addition of EPDM to bicycle tire tread rubber compositions can degrade other expected tread properties, particularly wear resistance.

[0006] There is therefore a need for bicycle tires with improved ozone resistance, without impacting the tire's other performance characteristics, particularly rolling resistance, which reflects the energy supplied by the cyclist or by the battery when the bicycle is electrically assisted, and wear resistance. Advantageously, it would be worthwhile to maintain good ozone resistance while improving one or more of these other performance characteristics.

[0007] Bicycle tires, due to the nature of these vehicles (weight, wheel size, tire design and geometry, conditions of use, etc.), are subject to very specific constraints. Therefore, simply transposing existing solutions from other fields, such as motorcycle tires, to the field of bicycle tires is not considered feasible by those skilled in the art of bicycle tires.

[0008] Continuing its research, the Applicant unexpectedly discovered that it was possible to improve the performance trade-off between wear resistance and rolling resistance of bicycle tires by using a specific rubber composition in the tread of the tire.

[0009] Thus, the invention relates to a bicycle tire comprising a tread, the tread comprising a rubber composition based on at least: - an elastomeric matrix comprising 50% to 95% by weight of at least one essentially unsaturated diene elastomer and 5% to 50% by weight of ethylene-propylene-diene copolymer, known as EPDM, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg below -56°C, - a reinforcing filler comprising silica, and - a crosslinking system.

[0010] In the present, unless otherwise indicated, the expressions "the composition" or "the composition according to the invention" refer to the rubber composition of the tread of the bicycle tire according to the invention. I- DEFINITIONS

[0011] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0012] By "elastomer matrix", we mean all the elastomers in the composition, including the copolymer defined below.

[0013] Unless otherwise indicated, the rates of units resulting from the insertion of a monomer into a copolymer are expressed as a molar percentage relative to the total monomer units of the copolymer.

[0014] The expression "part by weight per hundred parts by weight of elastomer" (or pce) is to be understood in the context of the present invention as the part, by mass per hundred parts of elastomer present in the rubber composition considered.

[0015] In the present, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0016] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​from greater than a to less than b (i.e., excluding the bounds a and b), while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​from a to b (i.e., including the strict bounds a and b). In the present case, when an interval of values ​​is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably designated.

[0017] When referring to a "major" compound, for the purposes of this invention, it is understood that this compound is the majority among the compounds of the same type in the composition; that is, it is the one that represents the largest quantity by mass among the compounds of the same type. Thus, for example, a major elastomer is the elastomer representing the greatest mass relative to the total mass of the elastomers in the composition. Similarly, a so-called major filler is the one representing the greatest mass among the fillers in the composition. By way of example, in a system comprising a single elastomer, this elastomer is the major component for the purposes of this invention; and in a system comprising two elastomers, the major elastomer represents more than half of the mass of the elastomers. Conversely, a "minor" compound is a compound that does not represent the largest mass fraction among the compounds of the same type.Preferably, by majority, we mean present at more than 50%, preferably more than 60%, 70%, 80%, 90%, and most preferably the "majority" compound represents 100%.

[0018] The compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of materials already in use, that is to say, they may be partially or totally derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0019] Unless otherwise indicated, all glass transition temperature values ​​“Tg” described herein are measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM D3418 (1999). II- DESCRIPTION OF THE INVENTION II-1 Elastomer Matrix

[0020] By "dienic" elastomer (or indistinctly rubber), whether natural or synthetic Thetic, must be understood in a known way an elastomer consisting at least in part (i.e., a homopolymer or a copolymer) of diene monomer units (monomers carrying two carbon-carbon double bonds, conjugated or not).

[0021] These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". Generally, "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of diene motifs or units (conjugated dienes) greater than 15% (mole percent); thus, diene elastomers such as butyl rubbers or EPDM-type diene-alpha-olefin copolymers do not fall under the preceding definition and can be described in particular as "essentially saturated" diene elastomers (low or very low proportion of diene motifs, always less than 15%).

[0022] Suitable conjugated dienes are conjugated dienes having 4 to 12 carbon atoms, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0023] According to the invention, the composition of the bicycle tire is based on an elastomeric matrix comprising 50% to 95% by weight of at least one essentially unsaturated diene elastomer, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg of less than -56°C, and 5% to 50% by weight of ethylene-propylene-diene copolymer, said EPDM.

[0024] The at least one essentially unsaturated diene elastomer may also include an elastomer other than the at least one butadiene-styrene copolymer having a Tg below -56°C, for example, at least one other essentially unsaturated diene elastomer selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures thereof. Butadiene copolymers are particularly selected from the group consisting of butadiene-styrene copolymers (SBR). The elastomeric matrix may thus include several SBRs provided that at least one of them has a Tg below -56°C.

[0025] Those with a -1,2 unit content (molar %) of between 4% and 80% or those with a cis-1,4 unit content (molar %) greater than 80% are particularly suitable as polybutadiene. Those with a glass transition temperature (Tg, measured according to ASTM D3418-99) of -56°C to -90°C, a styrene content of between 1% and 60% by weight and more particularly between 10% and 40%, a -1,2 unit content (molar %) of the butadiene portion of between 4% and 75%, and a trans-1,4 unit content (molar %) of between 6% and 60% are particularly suitable as butadiene-styrene copolymer. It should be noted that SBR can be prepared as an emulsion (ESBR) or as a solution (SSBR).

[0026] Advantageously, the SBR having a Tg less than -56°C, has a Tg in a range from -56°C to -80°C, preferably from -60°C to -70°C.

[0027] If an SBR other than the SBR having a Tg less than -56°C is used, it can be any SBR having a Tg between -56°C and 0°C.

[0028] The essentially unsaturated diene elastomer can be modified, i.e. either coupled and / or star-shaped, or functionalized, or coupled and / or star-shaped and simultaneously functionalized.

[0029] Thus, the essentially unsaturated diene elastomer can be coupled and / or star-linked, for example by means of a silicon or tin atom that links the elastomer chains together. The essentially unsaturated diene elastomer can simultaneously or alternatively comprise at least one functional group. By functional group is meant a group comprising at least one heteroatom selected from Si, N, S, O, P. Particularly suitable as functional groups are those comprising at least one function such as: a silanol function, an alkoxysilane function, a primary, secondary or tertiary amine function, cyclic or non-cyclic, a thiol function, or an epoxide function.

[0030] Advantageously, the elastomer matrix comprises a mixture of essentially unsaturated diene elastomer.

[0031] In particular, the at least one essentially unsaturated diene elastomer may comprise natural rubber and a butadiene-styrene copolymer having a Tg below -56°C. In this case, the essentially unsaturated diene elastomer of the elastomer matrix advantageously comprises from 50% to 95% by weight, preferably from 70% to 90% by weight, of butadiene-styrene copolymer having a Tg below -56°C, and from 5% to 50% by weight, preferably from 10% to 30% by weight, of natural rubber.

[0032] The at least one essentially unsaturated diene elastomer may also further comprise a polybutadiene. In this case, the essentially unsaturated diene elastomer of the elastomer matrix advantageously comprises from 5% to 40% by weight, preferably from 10% to 30% by weight, of natural rubber, from 20% to 90% by weight, preferably from 40% to 80% by weight, of butadiene-styrene copolymer having a Tg below -56°C, and from 5% to 40% by weight, preferably from 10% to 30% by weight, of polybutadiene.

[0033] The total rate of essentially unsaturated diene elastomer in the elastomer matrix of the composition according to the invention is preferably in the range of 55% to 90% by weight, preferably 60% to 85% by weight.

[0034] Any EPDM can be used in the context of the present invention. However, the use of a specific EPDM may be advantageous in the context of the present invention. The EPDM may be a single EPDM or a mixture of several EPDMs.

[0035] In particular, preferably, the EPDM has an ethylene content ranging from 41% to 75% by weight, preferably from 50% to 71.5% by weight, relative to the weight of the EPDM.

[0036] EPDM also advantageously has a propylene content ranging from 13% to 58% by weight, preferably from 17% to 42% by weight, relative to the weight of EPDM.

[0037] EPDM also advantageously has a diene content ranging from 1% to 12% by weight, preferably from 8% to 11.5% by weight, relative to the weight of EPDM.

[0038] The diene of the EPDM can be chosen from the group consisting of ethylidene norbornene, dicyclopentadiene and mixtures thereof. Preferably, the diene of the EPDM is ethylidene norbornene, in particular 5-ethylidene-2-norbornene (ENB).

[0039] The ethylene, propylene and diene levels of EPDM can be determined by infrared according to ASTM D3900 for the ethylene and propylene levels and ASTM D6047 for the diene level.

[0040] The EPDM content in the elastomer matrix of the composition according to the invention is preferably in the range of 10% to 45% by weight, preferably 15% to 40% by weight.

[0041] Preferably, the elastomer matrix does not comprise any other elastomer than at least one essentially unsaturated diene elastomer and EPDM, i.e. the total content of essentially unsaturated diene elastomer and EPDM in the elastomer matrix of the composition according to the invention is 100% by weight. II-2 Reinforcing Load

[0042] The rubber composition of the tread of the bicycle tire according to the invention comprises a reinforcing filler, known for its ability to strengthen a rubber composition usable for the manufacture of tires. Such a reinforcing filler typically consists of particles whose average size (by mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, and in particular and more preferably between 20 and 150 nm.

[0043] According to the invention, the reinforcing filler comprises silica. It may further comprise another reinforcing filler, in particular carbon black.

[0044] Any type of precipitated silica may be suitable as a precipitate, in particular highly dispersible precipitated silica (referred to as "HDS" for "highly dispersible" or "highly dispersible silica"). These precipitated silicas, whether highly dispersible or not, are well known to those skilled in the art. Examples include the silicas described in applications WO03 / 016215-A1 and WO03 / 016387-A1. Among commercial HDS silicas, the "Ultrasil® 5000GR" and "Ultrasil® 7000GR" silicas from Evonik, and the "Zeosil® 1085GR" and "Zeosil®" silicas may be used. 1115 MP, Zeosil® 1165MP, Zeosil® Premium 200MP, Zeosil® HRS 1200 MP from Solvay. As non-HDS silica, the following commercial silicas can be used: silicas "Ultrasil ® VN2GR", "Ultrasil ® VN3GR" of the company Evonik, silica "Zeosil® 175GR" of the company Solvay, silicas "Hi-Sil-Z-120", "ZD-12", Hi-Sil EZ160G(-D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” from PPG.

[0045] To couple the silica to the diene elastomer, a coupling agent (or bonding agent) that is at least bifunctional is used in a well-known manner to ensure sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used. By "bifunctional," we mean a compound having a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the diene elastomer. For example, such a bifunctional compound may comprise a first functional group including a silicon atom, said first functional group being capable of interacting with the hydroxyl groups of an inorganic filler, and a second functional group including a sulfur atom, said second functional group being capable of interacting with the diene elastomer.

[0046] Preferably, the organosilanes are chosen from the group consisting of polysulfide organosilanes (symmetric or asymmetric) such as bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT and marketed under the name "Si69" by Evonik, or bis-(triethoxysilylpropyl) disulfide, abbreviated TES PD and marketed under the name "Si75" by Evonik, polyorganosiloxanes, mercaptosilanes, and blocked mercaptosilanes, such as S-(3-(triethoxysilyl)propyl) octanethioate, marketed by Momentive under the name "NXT Silane". More preferably, the organosilane is a polysulfide organosilane.

[0047] The coupling agent content can easily be adjusted by a person skilled in the art. Typically and preferably, the coupling agent content represents 0.5% to 15% by weight relative to the amount of silica.

[0048] Advantageously, the rate of reinforcing filler in the composition is in a range of 8% to 24% by weight, preferably 15% to 24%, preferably 16% to 23% by weight, preferably 17% to less than 20% by weight, relative to the total weight of the rubber composition.

[0049] Advantageously also, the rate of reinforcing charge, in the composition, is in a range from 11 to 55 pc, preferably from 20 to less than 50 pc, preferably from 15 to 45 pc.

[0050] The reinforcing load may comprise more than 50% to 100% by weight, preferably 75% to 100% by weight, preferably 95% to 100% by weight, of silica relative to the total weight of reinforcing filler. In particular, the reinforcing filler can comprise 100% silica by weight. This is especially advantageous when coloring the tread of the bicycle tire using pigments.

[0051] When a black tread is desired, the reinforcing filler in the composition advantageously comprises 0.5% to 5% by weight, preferably 1% to 3% by weight, of carbon black. In this case, the reinforcing filler comprises 95% to 99.5% by weight, preferably 97% to 99% by weight, of silica.

[0052] The blacks usable within the scope of the present invention can be any black conventionally used in tires or their treads (so-called tire-grade blacks). Among the latter, special mention should be made of reinforcing carbon blacks of the 100, 200, and 300 series, or blacks of the 500, 600, or 700 series (ASTM grades), such as NI 15, N134, N234, N326, N330, N339, N347, N375, N550, N683, and N772 blacks. These carbon blacks can be used in isolation, as commercially available, or in any other form, for example, as a carrier for certain rubber additives used. Carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97 / 36724 or WO 99 / 16600). II-3 Plasticizing System

[0053] The rubber composition of the tread of the bicycle tire according to the invention may optionally include a plasticizing system. Preferably, the rubber composition of the tread of the bicycle tire according to the invention includes a plasticizing system, preferably based on at least one plasticizing resin having a glass transition temperature above 20°C, referred to as a "high Tg" resin (also referred to herein as a "plasticizing resin" for the sake of simplicity).

[0054] The term "resin" is reserved in this application, by definition known to those skilled in the art, for a compound which is solid at room temperature (23°C), as opposed to a liquid plasticizing compound such as an oil.

[0055] Plasticizing resins are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but potentially containing other types of atoms, usable in particular as plasticizing or tackifying agents in polymer matrices. They are generally by nature miscible (i.e., compatible) at the rates used with the polymer compositions for which they are intended, so as to act as true diluents. They have been described, for example, in the work entitled "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), whose Chapter 5 is devoted to their applications, particularly in pneumatic rubber (5.5). They can be aliphatic, cycloaliphatic, aromatic, hydrogenated aromatic, or of the aliphatic / aromatic type, i.e., based on aliphatic and / or aromatic monomers. They can be natural or synthetic, petroleum-based or not (if so, also known as petroleum resins). Their Tg is preferably above 20°C (most often between 30°C and 95°C).

[0056] As is known, these plasticizing resins can also be described as thermoplastic resins in that they soften upon heating and can thus be molded. They can also be defined by a softening point or temperature.The softening temperature of a plasticizing resin is generally about 50 to 60°C higher than its Tg value. The softening point is measured according to ISO 4625 (Ring and Bail method). The macrostructure (Mw, Mn and Ip) is determined by size exclusion chromatography (SEC) as described below.

[0057] As a reminder, SEC analysis, for example, consists of separating macromolecules in solution according to their size using columns filled with a porous gel; the molecules are separated according to their hydrodynamic volume, with the largest being eluted first. The sample to be analyzed is simply pre-solubilized in a suitable solvent, tetrahydrofuran, at a concentration of 1 g / liter. The solution is then filtered through a 0.45 µm porosity filter before being injected into the instrument. The instrument used is, for example, a Waters Alliance chromatographic system under the following conditions: - the elution solvent is tetrahydrofuran; - temperature 35°C; - concentration 1 g / litre; - flow rate: 1 ml / min; - injected volume: 100 pl; - Moore calibration with polystyrene standards; - set of 3 "Waters" columns in series ("Styragel HR4E", "Styragel HR1" and "Styragel HR 0.5"); - detection by differential refractometer (for example "WATERS 2410") which can be equipped with operating software (for example "Waters Millennium").

[0058] A Moore calibration is performed with a series of commercial polystyrene standards with a low Ip value (less than 1.2), of known molar masses, covering the range of masses to be analyzed. The average mass molar mass (Mw), the average number molar mass (Mn), and the polymolecularity index (Ip = Mw / Mn).

[0059] All molar mass values ​​indicated in this application are therefore relative to calibration curves made with polystyrene standards.

[0060] The plasticizing resin may have at least one, preferably two or three, more preferably all of the following characteristics: - a Tg greater than 25°C (in particular between 30°C and 100°C), more preferably greater than 30°C (in particular between 30°C and 95°C); - a softening point above 50°C (in particular between 50°C and 150°C); - an average number molar mass (Mn) between 300 and 2000 g / mol, preferably between 400 and 1500 g / mol; - a polymolecularity index (Ip) less than 3, preferably 2 (reminder: Ip = Mw / Mn with Mw average molar mass by weight).

[0061] The above-mentioned preferred high Tg plasticizing resins are well known to those skilled in the art and are commercially available, for example sold with regard to: - polylimonene resins: by the company DRT under the name "Dercolyte L120" (Mn=625 g / mol; Mw=1010 g / mol; Ip=l.6; Tg=72°C) or by the company ARIZONA under the name "Sylvagum TR7125C" (Mn=630 g / mol; Mw=950 g / mol; Ip=l.5; Tg=70°C); - C5 / vinylaromatic copolymer resins, in particular C5 / styrene or C5 / C9: by Neville Chemical Company under the names "Super Nevtac 78", "Super Nevtac 85" or "Super Nevtac 99", by Goodyear Chemicals under the name "Wingtack Extra", by Kolon under the names "Hikorez T1095" and "Hikorez Tl 100", by Exxon under the names "Escorez 2101" and "Escorez 1273"; - limonene / styrene copolymer resins: by DRT under the name "Dercolyte TS 105" of the DRT company, by ARIZONA Chemical Company under the names "ZT115LT" and "ZT5100".

[0062] The plasticizing resin having a glass transition temperature above 20°C may be selected from the group comprising or consisting of cyclopentadiene homopolymer or copolymer resins (abbreviated CPD), dicyclopentadiene homopolymer or copolymer resins (abbreviated DCPD), terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins, C9-cut homopolymer or copolymer resins, alpha-methylstyrene homopolymer or copolymer resins, and mixtures thereof. Preferably, the plasticizing resin is selected from the group consisting of terpene homopolymer or copolymer resins, terpene homopolymer or copolymer resins, and mixtures thereof. C5 cutting polymer or C9 cutting homopolymer or copolymer resins, preferably the plasticizing resin is chosen from the group consisting of terpene homopolymer or copolymer resins.

[0063] The term "terpene" here includes in a known way the alpha-pinene, beta-pinene and limonene monomers; preferably a limonene monomer is used, a compound which is known to exist in the form of three possible isomers: L-limonene (levorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or dipentene, racemic of the dextrorotatory and levorotatory enantiomers. Suitable examples of vinylaromatic monomers include styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, and any vinylaromatic monomer derived from a C9 cut (or more generally from a C8 to C1 cut).

[0064] In particular, we can mention the plasticizing resins chosen from the group consisting of homopolymer (D)CPD resins, (D)CPD / styrene copolymer resins, polylimonene resins, limonene / styrene copolymer resins, limonene / D(CPD) copolymer resins, C5 / styrene copolymer resins, C5 / C9 copolymer resins, and mixtures of these resins.

[0065] All the above plasticizing resins are well known to those skilled in the art and are commercially available, for example sold by DRT under the name "Dercolyte" for polylimonene resins, by Neville Chemical Company under the name "Super Nevtac", by Kolon under the name "Hikorez" or by Exxon Mobil under the name "Escorez" for C5 / styrene cut resins or C5 / C9 cut resins, or by Struktol under the name "40 MS" or "40 NS" (mixtures of aromatic and / or aliphatic resins).

[0066] Advantageously, the proportion of the plasticizing resin having a glass transition temperature above 20°C in the composition according to the invention is in the range of 6% to 20% by weight, relative to the total weight of the rubber composition of the tread of the bicycle tire according to the invention. Preferably, this proportion is in the range of 6.5% to 18% by weight, and more preferably 7% to 15% by weight, relative to the total weight of the rubber composition.

[0067] The proportion of the plasticizing resin having a glass transition temperature above 20°C in the composition according to the invention can be in a range from 10 to 40 parts per cent, preferably from 11 to 30 parts per cent.

[0068] Although not necessary for the implementation of the present invention, the plasticizing system of the rubber composition according to the invention may include a liquid plasticizer at 23°C, referred to as a "low Tg" plasticizer, that is to say, one which by definition has a Tg below -20°C, preferably below -40°C. According to the invention, the composition may optionally include from 0 to 30 parts per cent of a liquid plasticizer at 23°C or from 0% to 20% by weight relative to the total weight of the rubber composition of the tread of the bicycle tire according to the invention.

[0069] When a liquid plasticizer at 23°C is used, its level in the composition according to the invention can be in the range of 4 to 20 parts per cent, or 5% to 15% by weight relative to the total weight of the rubber composition of the tread of the bicycle tire according to the invention.

[0070] Any liquid plasticizer at 23°C (or extending oil), whether aromatic or non-aromatic, known for its plasticizing properties with respect to diene elastomers, is usable. At room temperature (23°C), these plasticizers or oils, with varying degrees of viscosity, are liquids (that is to say, substances that eventually take the shape of their container), unlike plasticizing resins, which are solid at room temperature.

[0071] Particularly suitable are liquid plasticizers at 23 °C selected from the group comprising or consisting of liquid diene polymers, polyolefinic oils, naphthenic oils, paraffinic oils, DAE oils, MES (Medium Extracted Solvates) oils, TDAE (Treated Distillate Aromatic Extracts) oils, RAE (Residual Aromatic Extract oils), TRAE (Treated Residual Aromatic Extract) oils and SRAE (Safety Residual Aromatic Extract oils), mineral oils, vegetable oils, ether plasticizers, ester plasticizers, phosphate plasticizers, sulfonate plasticizers and their mixtures C.

[0072] Preferably, the liquid plasticizer at 23 °C is chosen from the group comprising or consisting of TDAE oils, vegetable oils and their mixtures. II-4 Crosslinking System

[0073] The crosslinking system can be any type of system known to those skilled in the art in the field of tire rubber compositions. In particular, it can be based on sulfur, and / or peroxide, and / or bismaleimides.

[0074] Preferably, the crosslinking system is sulfur-based; this is then referred to as a vulcanization system. Advantageously, the vulcanization system comprises molecular sulfur and / or at least one sulfur-donating agent. At least one vulcanization accelerator is also preferably present, and, optionally and also preferably, various known vulcanization activators such as zinc oxide, stearic acid, or equivalent compounds such as stearic acid salts and transition metal salts, guanidine derivatives (in in particular diphenylguanidine), or known vulcanization retardants.

[0075] Sulfur is used at a preferential rate of between 0.5 and 12 parts per liter, in particular between 1 and 10 parts per liter. The vulcanization accelerator is used at a preferential rate of between 0.5 and 10 parts per liter, more preferably between 0.5 and 5.0 parts per liter.

[0076] Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used as an accelerator, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Examples of such accelerators include the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-ter-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-ter-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds. II-5 Possible Additives

[0077] The rubber compositions of the tread of the tire according to the invention may optionally also include all or part of the usual additives commonly used in elastomer compositions for tires, such as pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, etc. II-6 Preparation of compositions

[0078] The compositions according to the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first thermomechanical working or mixing phase (the so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents, including the elastomeric matrix, the reinforcing filler, and any other miscellaneous additives, with the exception of the crosslinking system, are introduced into a suitable mixer such as a standard internal mixer (for example, a "Banbury" type mixer). The incorporation of the filler into the elastomer can be carried out in one or more stages by thermomechanical mixing. In cases where the filler is already incorporated, in whole or in part, into the elastomer in the form of a masterbatch, as described, for example, in applications WO 97 / 36724 or WO 99 / 16600, the masterbatch is directly mixed, and where applicable, other elastomers or fillers present in the composition that are not in the form of masterbatch, as well as any other miscellaneous additives other than the crosslinking system. The non-productive phase can be carried out at high temperature, up to a maximum temperature between 110°C and 200°C, preferably between 130°C and 185°C, for a duration generally between 2 and 10 minutes. - a second mechanical working phase (the so-called "productive" phase), which can be carried out in an external mixer such as a roller mixer, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 120°C, for example between 40°C and 100°C. The crosslinking system is then incorporated, and the whole is then mixed for a few minutes, for example between 5 and 15 min.

[0079] Such phases have been described for example in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

[0080] The final composition thus obtained is then calendered, for example, into a sheet or plate, particularly for laboratory characterization, or extruded (or co-extruded with another rubber composition) into a semi-finished (or profile) rubber product usable, for example, as a bicycle tire tread. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

[0081] The composition can be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), can be a semi-finished product that can be used in a tire.

[0082] The crosslinking of the composition can be carried out in a manner known to those skilled in the art, for example at a temperature between 130°C and 200°C, under pressure. II-7 Bicycle Bandage

[0083] According to the invention, the tire is intended to equip any type of bicycle without particular limitation, whether or not it has an electric assist motor. Advantageously, the bicycle tire is a tire for road bikes, mountain bikes, or hybrid bikes; preferably, the bicycle tire is a tire for road bikes. The bicycle tire can be a bicycle tire.

[0084] The term "tire" refers to a pneumatic or non-pneumatic tire. Pneumatic bicycle tires typically consist of a carcass reinforcement layer anchored in two beads by folding it around two beads. The beads are radially extended by the carcass ply, which is itself extended by the tread. A pneumatic tire is, by definition, designed to contain compressed air when it is mounted on the bicycle wheel. A non-pneumatic tire, on the other hand, can come in various forms, for example, a solid or non-solid tire. As an example describing a non-pneumatic bicycle tire, we can cite application FR3042736A1. According to the invention, the tire according to the invention is preferably a pneumatic tire.

[0085] The tire according to the invention may be a tubeless tire, that is, mounted directly on a rim without an inner tube, or a tube-type tire requiring an inner tube. The tire according to the invention may also be a non-pneumatic tire, either solid or airless.

[0086] The width of the bicycle tire according to the invention can be within a range of 20 to 70 mm, preferably from 25 to 50 mm. The width of the tire is measured with the tire mounted and under the pressure recommended by the manufacturer in the case of pneumatic tires.

[0087] The tread thickness of the bicycle tire according to the invention can be in the range of 0.5 to 5 mm, preferably 1 to 2 mm. III- EXAMPLES III-1 Measurements and tests used

[0088] Mechanical properties (after baking): Tensile test

[0089] These tensile tests allow the determination of elastic stresses and fracture properties. Unless otherwise specified, they are carried out in accordance with French standard NF T 46-002 of September 1988. Processing the tensile recordings also allows the plotting of the modulus curve as a function of elongation. The modulus used here is the nominal (or apparent) secant modulus measured at first elongation, calculated by referring to the initial cross-section of the specimen. The nominal secant modulus (or apparent stresses, in MPa) is measured at first elongation at 10%, 100%, and 300% elongation, denoted MSA10, MSA100, and MSA300, respectively.

[0090] The MSA300 / MSA100 reinforcement index usually used to indicate the wear resistance of a rubber composition could not be used in the present case because the crosslinked formulations tested broke before reaching 300% elongation.

[0091] The MSA100 / MSA10 reinforcement index was therefore used instead, as it is also a good descriptor of wear resistance, particularly in the field of bicycle tires.

[0092] The MSA100 / MSA10 reinforcement performance results are expressed as a base of 100, with 100 being assigned to the control. A result greater than 100 indicates that the composition of the example considered exhibits improved resistance to wear and tear. Dynamic properties

[0093] The dynamic properties tan(φ)max are measured at a temperature of 23°C on a viscoelastic analyzer (Metravib VA4000), according to ASTM D 5992-96. The response of a cross-linked composite sample (cylindrical specimen 4 mm thick and 400 mm² cross-section) was recorded under sinusoidal loading in alternating simple shear at a frequency of 10 Hz, under the defined temperature conditions, for example, 23°C, according to ASTM D 1349-99. A strain amplitude sweep was performed from 0.1 to 50% (forward cycle), then from 50% to 0.1% (reverse cycle). The results used are the loss factor tan(φ). For the reverse cycle, the maximum observed value of tan(φ), denoted tan(φ)max at 23°C, is indicated.

[0094] It should be noted that, as is well known to those skilled in the art, the value of tan(φ)max at 23°C is representative of hysteresis. The tan(φ)max performance results at 23°C are expressed as a base of 100, with 100 being assigned to the control. A result greater than 100 indicates that the composition of the example considered is less hysteretic at 23°C, reflecting lower rolling resistance of the tread with such a composition. III-2 Preparation of compositions

[0095] In the following examples, the rubbery compositions were produced as described in section II.6 above. In particular, the "non-productive" phase was carried out in a 0.4-liter mixer for 3.5 minutes, at an average paddle speed of 50 revolutions per minute, until a maximum drop temperature of 160°C was reached. The "productive" phase was carried out in a roller tool at 23°C for 5 minutes.

[0096] The crosslinking of the composition was carried out at a temperature between 130°C and 200°C, under pressure. III-3 Tests of Rubber Compositions

[0097] The examples presented below are intended to compare the performance trade-off between wear resistance and rolling resistance of compositions according to the present invention (Cl to C4) with control compositions (Tl and T2).

[0098] The control composition Tl is a reference composition for road bicycle treads. It comprises 10 parts natural rubber, 40 parts 98% 1,4-cis neodymium polybutadiene (Tg = -110°C), 50 parts tin functionalized SBR with 15% styrene motif and 30% 1,2-butadiene motif (Tg = -64°C), 20 parts "Tudalen 11" oil from Hansen und Rosenthal ChemPharm, 60 parts "Zeosil 1165MP" silica from Solvay, 4.8 parts TESPT "Si69" liquid silane from Evonik, 5 parts 2,4,6-tris(l-phenylethyl)phenol (SPC) "Kumanox" from Kumho as an antioxidant, 3 parts cyclic acetal "Vulkazon AFS / LG" from Lanxess as an antioxidant, 7 parts anti-ozone wax "VARAZON 4959" from Sasol Wax, 2 parts black pigment "MICROLEN BK 0062 MCN" from BASF, 2 parts Diphenylguanidine "Perkacit DPG" from Flexsys, 3.5 parts industrial grade zinc oxide (Umicore), 2 parts stearic acid "Pristerene 4931" from Uniqema, 2 parts sulfur and 2 parts N-cyclohexyl-2-benzothiazol-sulfenamide "Santocure CBS" from Flexsys, as a vulcanization accelerator.

[0099] Table 1 presents the other compositions tested (in pc), as well as the results obtained. In addition to the ingredients listed in Table 1, the tested formulations all contain 3 parts per million of 2,4,6-tris(l-phenylethyl)phenol (SPC) "Kumanox" from Kumho, 1.5 parts per million of cyclic acetal "Vulkazon AFS / LG" from Lanxess, 1.5 parts per million of ozone-blocking wax "VARAZON 4959" from Sasol Wax, 2 parts per million of black pigment "MICROLEN BK 0062 MCN" from BASF, 1.5 parts per million of diphenylguanidine "Perkacit DPG" from Flexsys, 3.5 parts per million of industrial-grade zinc oxide (Umicore), 2 parts per million of stearic acid "Pristerene 4931" from Uniqema, 3.5 parts per million of sulfur, and 2 parts per million of N-cyclohexyl-2-benzothiazol-sulfenamide. Santocure CBS » from the company Flexsys, as a vulcanization accelerator.

[0100] The control composition T2 differs from composition Cl only in the nature of the SBR used. The SBR in composition T2 is not in accordance with the invention in that its Tg is not less than -56°C.

[0101] Compositions C2 to C4 conform to the invention and differ from composition Cl by the silica content (at constant proportion of coupling agent relative to the mass of silica), by the presence of liquid plasticizer at 23°C or by the plasticizing resin content respectively.

[0102] The results of the wear resistance and rolling resistance performance are expressed as a percentage based on 100 relative to the control composition TL. A value greater than 100 indicates an improvement in the performance concerned.

[0103] The performance trade-off between wear resistance and rolling resistance can be considered as the arithmetic mean of the results presented in base 100.

[0104] [Tables 1] Compositions T2 Cl C2 C3 C4 NR(1) 15 15 15 15 15 BR(2) 15 15 15 15 15 SBR 1(3) - 40 40 40 40 SBR 2(4) 40 - - - - EPDM(5) 30 30 30 30 30 Plasticizing resin(6) 15.5 15.5 15.5 15.5 35 Liquid plasticizer(7) 6.5 6.5 6.5 - 6.5 Silica(8) 35 35 15 35 35 Coupling agent(9) 2.8 2.8 1.2 2.8 2.8 Performance Wear resistance (base 100 / r Tl) 92 96 111 94 101 Rolling resistance (base 100 / r Tl) 168 261 318 246 182 Compromise 130 178 214 170 141

[0105] (1) Natural rubber (2) Neodymium polybutadiene 98% 1,4 cis - Tg = -110°C (3) SBR 1: Tin functionalized SBR solution with 15% styrene motifs and 30% polybutadiene motifs 1,2 of the butadiene part (Tg = -64°C) (4) SBR 2: Tin functionalized SBR solution with 21% styrene motifs and 62% polybutadiene motifs 1,2 of the butadiene part (Tg = -25 °C) (5) EPDM “Keltan 3960” from the company Arlanxeo with 56% ethylene pattern and 11% of ENB pattern (6) Polylimonene resin “Dercolyte L120” from the company DRT (Tg = 72°C) (7) Trioctyl phosphate (tri-2-ethylhexyl phosphate) “Disflamoll TOF” from the Lanxess company (8) Silica “Zeosil 1165MP” from the Solvay company (9) Liquid silane triethoxysilylpropyltetrasulfide (TESPT) “Si69” from the Evonik company

[0106] It has been found that the compositions according to the invention exhibit ozone resistance equivalent to that of the reference composition.

[0107] Furthermore, the results presented in Table 1 above show that all The compositions according to the invention also make it possible to improve rolling resistance by a factor of more than 1.7 compared to the reference composition Tl without significantly impacting wear resistance, or even improving it.

[0108] While the T2 control composition does offer improved rolling resistance, this comes at the expense of wear resistance performance. The performance trade-off of composition T2 is lower than that of compositions according to the invention.

Claims

Demands

1. Bicycle tire comprising a tread, the tread comprising a rubber composition based on at least: - an elastomeric matrix comprising from 50% to 95% by weight of at least one essentially unsaturated diene elastomer and from 5% to 50% by weight of ethylene-propylene-diene copolymer, said EPDM, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg below -56°C, - a reinforcing filler comprising silica, and - a crosslinking system.

2. Bandage according to claim 1, wherein the at least essentially unsaturated diene elastomer comprises: - 50% to 95% by weight, preferably 70% to 90% by weight, of butadiene-styrene copolymer, and - 5% to 50% by weight, preferably 10% to 30% by weight, of natural rubber.

3. Bandage according to any one of the preceding claims, wherein the butadiene-styrene copolymer has a Tg in the range of -56°C to -80°C, preferably -60°C to -70°C.

4. Bandage according to any one of the preceding claims, wherein the EPDM has an ethylene content of 41% to 75% by weight, preferably 50% to 71.5% by weight, relative to the weight of the EPDM.

5. Bandage according to any one of the preceding claims, wherein the EPDM has a propylene content of 13% to 58% by weight, preferably 17% to 42% by weight, relative to the weight of the EPDM.

6. Bandage according to any one of the preceding claims, wherein the EPDM has a diene content of 1% to 12% by weight, preferably 8% to 11.5% by weight, relative to the weight of the EPDM.

7. Bandage according to any one of the preceding claims, wherein the diene of the EPDM is selected from the group consisting of ethylidene norbornene, dicyclopentadiene and mixtures thereof, preferably the diene of the EPDM is ethylidene norbornene.

8. Bandage according to any one of the preceding claims, wherein the EPDM content in the elastomer matrix is ​​in the range of 10% to 45% by weight, preferably 15% to 40% by weight.

9. Bandage according to any one of the preceding claims, wherein the reinforcing filler comprises more than 50% to 100% by weight, preferably 75% to 100% by weight, of silica relative to the total weight of reinforcing filler.

10. Bandage according to any one of the preceding claims, wherein the rate of reinforcing filler in the rubber composition is in the range of 11 to 55 pc, preferably 20 to less than 50 pc, preferably 15 to 45 pc.

11. A bandage according to any one of the preceding claims, wherein the rubber composition further comprises at least one plasticizing resin having a Tg greater than 20°C, which is preferably selected from the group consisting of cyclopentadiene homopolymer or copolymer resins, dicyclopentadiene homopolymer or copolymer resins, terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins, C9-cut homopolymer or copolymer resins, alpha-methylstyrene homopolymer or copolymer resins and mixtures thereof, preferably the plasticizing resin being selected from the group consisting of terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins, or homopolymer or copolymer resins of Cup C9.

12. Bandage according to claim 11, wherein the rate of the plasticizing resin in the rubber composition is in the range of 6% to 20% by weight, preferably 6.5% to 18% by weight, preferably 7% to 15% by weight, relative to the total weight of the rubber composition.

13. Bandage according to claim 11 or 12, wherein the rate of plasticizing resin in the rubber composition is in the range of 10 to 40 parts per annum, preferably 11 to 30 parts per annum.

14. Bandage according to any one of the preceding claims, wherein the crosslinking system is based on molecular sulfur and / or at least one sulfur-donating agent.

15. Bandage according to any one of the preceding claims, wherein the bicycle bandage is a road bike, mountain bike or all-terrain bike bandage, preferably, the bicycle bandage is a road bike bandage.