BICYCLE BANDAGE

Abstract

The invention relates to a bicycle tire comprising a tread, the tread comprising a rubber composition based on at least one elastomer 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, known as EPDM, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg of less than -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 comply with a large number of technical requirements, often contradictory, including rolling resistance, grip on both dry and wet ground, wear resistance, rigidity of the cured compositions (associated with the ability to keep the handlebars straight after contact with a branch or a stone or contact with the ground after a jump), at the same time 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, these cracks can be detrimental to the performance of the tire, particularly with regard to its endurance, thus reducing the life of the tire, but also with regard to the maintenance of inflation pressure.

[0004] In order to combat these harmful effects, anti-ozone waxes well known to those skilled in the art are conventionally used. However, the use of a significant amount of anti-ozone wax can cause whitening of the rubber compositions ("blooming" in English) which is not desired by users. Furthermore, given the small thickness of the layers constituting the bandage, the amount of anti-ozone wax present may not prove sufficient to combat the effects of ozone.

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

[0006] There is therefore a need to have a bicycle tire having improved ozone resistance, without impacting the other performances of the tire, in particular the rolling resistance, which reflects the energy supplied by the cyclist or by the battery when the bicycle is electrically assisted, and the wear resistance. Advantageously, it would be interesting to maintain good ozone resistance by improving one or more of these other performances.

[0007] Bicycle tires, due to the nature of these vehicles (weight, size of their wheels, architecture and geometry of the tire, conditions of use, etc.), are subject to very specific constraints. The simple transposition of existing solutions in other fields, for example that of motorcycle tires, to the field of bicycle tires is therefore not envisaged 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 compromise between wear resistance and rolling resistance of bicycle tires by using a specific rubber composition in the tread of the tire.

[0009] Thus, the subject of the invention is a bicycle tire comprising a tread, the tread comprising a rubber composition based on at least: - an elastomer 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, known as EPDM, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg of less than -56°C, - a reinforcing filler comprising silica, and - a crosslinking system.

[0010] In the present document, unless otherwise indicated, the expressions "the composition" or "the composition according to the invention" designate 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 manufacture of the composition; the composition thus being able to be in the totally or partially crosslinked state or in the non-crosslinked state.

[0012] By “elastomer matrix” is meant all of 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] By the expression "part by weight per hundred parts by weight of elastomer" (or pce), it is meant, within the meaning of the present invention, the part, by mass per hundred parts of elastomer present in the rubber composition considered.

[0015] Herein, unless expressly indicated 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 range of values ​​from more than a to less than b (i.e., excluding limits a and b), while any interval of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict limits a and b). In the present document, 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 a "majority" compound is referred to, within the meaning of the present invention, this compound is the majority among the compounds of the same type in the composition, i.e. it is the one that represents the largest quantity by mass among the compounds of the same type. Thus, for example, a majority elastomer is the elastomer representing the largest mass relative to the total mass of the elastomers in the composition. In the same way, a so-called majority filler is the one representing the largest mass among the fillers in the composition. For example, in a system comprising a single elastomer, this is the majority within the meaning of the present invention; and in a system comprising two elastomers, the majority elastomer represents more than half of the mass of the elastomers. On the contrary, a "minority" 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 more preferably the “majority” compound represents 100%.

[0018] The compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. In the same way, the compounds mentioned may also come from the recycling of materials already used, 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 concerns in particular polymers, plasticizers, fillers, etc.

[0019] Unless otherwise indicated, all glass transition temperature "Tg" values ​​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 Elastomeric matrix

[0020] By "diene" elastomer (or indistinctly rubber), whether natural or syn Thetic, must be understood in a known manner to mean 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". "Essentially unsaturated" is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a content of units or patterns of diene origin (conjugated dienes) which is greater than 15% (mol %); thus, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins such as EPDM do not fall within the preceding definition and can be described in particular as "essentially saturated" diene elastomers (low or very low content of patterns of diene origin, always less than 15%).

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

[0023] According to the invention, the composition of the bicycle tire is based on an elastomer matrix comprising from 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 from 5% to 50% by weight of ethylene-propylene-diene copolymer, known as EPDM.

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

[0025] Particularly suitable as polybutadiene are those having a content (mol%) of -1,2 units of between 4% and 80% or those having a content (mol%) of cis-1,4 greater than 80%. Particularly suitable as butadiene-styrene copolymers are those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418-99) ranging from -56°C to -90°C, a styrene content of between 1% and 60% by weight and more particularly between 10% and 40%, a content (mol%) of -1,2 bonds in the butadiene part of between 4% and 75%, a content (mol%) of trans-1,4 bonds of between 6% and 60%. It should be noted that the SBR can be prepared in emulsion (ESBR) or in solution (SSBR).

[0026] Advantageously, the SBR having a Tg of less than -56°C, has a Tg within 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 below -56°C is used, this may 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-shaped, for example by means of a silicon or tin atom which 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 chosen from Si, N, S, O, P. Particularly suitable 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 not, a thiol function, 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 of less than -56°C. In the 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 of less than -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 the 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 of less than -56°C, and from 5% to 40% by weight, preferably from 10% to 30% by weight, of polybutadiene.

[0033] The total content of essentially unsaturated diene elastomer in the elastomer matrix of the composition in accordance with the invention is preferably within a range from 55% to 90% by weight, preferably from 60% to 85% by weight.

[0034] Any EPDM may be used in the context of the present invention. However, the use of 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] The 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 the EPDM.

[0037] The 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 the EPDM.

[0038] The diene of EPDM may be selected from the group consisting of ethylidene norbornene, dicyclopentadiene and mixtures thereof. Preferably, the diene of 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 level and ASTM D6047 for the diene level.

[0040] The level of EPDM in the elastomer matrix of the composition in accordance with the invention is preferably within a range from 10% to 45% by weight, preferably from 15% to 40% by weight.

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

[0042] The rubber composition of the tread of the bicycle tire according to the invention comprises a reinforcing filler, known for its ability to reinforce 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, 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 silicas, in particular highly dispersible precipitated silicas (known as "HDS"). 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 the commercial HDS silicas, it is possible in particular to use the silicas "Ultrasil ® 5000GR", "Ultrasil ® 7000GR" from the company Evonik, the silicas "Zeosil ® 1085GR", "Zeosil ® 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" from the company Evonik, silica "Zeosil® 175GR" from the company Solvay, silicas "Hi-Sil-Z-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, an at least bifunctional coupling agent (or bonding agent) is used in a well-known manner, intended to ensure a sufficient connection, of a chemical and / or physical nature, 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 comprising a silicon atom, said first functional group being capable of interacting with the hydroxyl groups of an inorganic filler and a second functional group comprising 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 polysulfurized organosilanes (symmetrical or asymmetrical) such as bis(3-triethoxysilylpropyl) tetrasulfide, abbreviated to TESPT, marketed under the name “Si69” by the company Evonik or bis-(triethoxysilylpropyl) disulfide, abbreviated to TES PD, marketed under the name “Si75” by the company Evonik, polyorganosiloxanes, mercaptosilanes, blocked mercaptosilanes, such as S-(3-(triethoxysilyl)propyl) octanethioate marketed by the company Momentive under the name “NXT Silane”. More preferably, the organosilane is a polysulfurized 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 from 0.5% to 15% by weight relative to the quantity of silica.

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

[0049] Advantageously also, the level of reinforcing filler, in the composition, is within a range from 11 to 55 pce, preferably from 20 to less than 50 pce, preferably from 15 to 45 pce.

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

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

[0052] The blacks that can be used in the context of the present invention can be any black conventionally used in tires or their treads (so-called tire grade blacks). Among the latter, mention will be made more particularly of reinforcing carbon blacks of the 100, 200, 300 series, or blacks of the 500, 600 or 700 series (ASTM grades), such as for example blacks NI 15, N134, N234, N326, N330, N339, N347, N375, N550, N683, N772). These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a support for certain of the 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 comprise a plasticizing system. Preferably, the rubber composition of the tread of the bicycle tire according to the invention comprises a plasticizing system, preferably based on at least one plasticizing resin having a glass transition temperature greater than 20°C, called “high Tg”, (also referred to herein as “plasticizing resin” for the sake of simplification of wording).

[0054] The term “resin” is reserved in the present 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 which may contain other types of atoms, usable in particular as plasticizing agents 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 diluting agents. 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, in particular in pneumatic rubber (5.5. ). They can be aliphatic, cycloaliphatic, aromatic, hydrogenated aromatic, of the aliphatic / aromatic type, i.e. based on aliphatic and / or aromatic monomers. They can be natural or synthetic, based or not on petroleum (if this is the case, also known as petroleum resins). Their Tg is preferably greater than 20°C (most often between 30°C and 95°C).

[0056] In a known manner, these plasticizing resins can also be described as thermoplastic resins in the sense 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 shown below.

[0057] As a reminder, SEC analysis, for example, consists of separating macromolecules in solution according to their size through columns filled with a porous gel; the molecules are separated according to their hydrodynamic volume, the largest being eluted first. The sample to be analyzed is simply previously solubilized in an appropriate solvent, tetrahydrofuran, at a concentration of 1 g / liter. Then the solution is filtered through a 0.45 μm porosity filter, before injection into the apparatus. The apparatus used is, for example, a "Waters alliance" chromatographic chain according to the following conditions: - elution solvent is tetrahydrofuran; - temperature 35°C; - concentration 1 g / liter; - 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 carried out with a series of commercial polystyrene standards with low Ip (less than 1.2), of known molar masses, covering the range of masses to be analyzed. From the recorded data (mass distribution curve of the molar masses) the mass average molar mass (Mw), the number average molar mass (Mn), as well as the polymolecularity index (Ip = Mw / Mn).

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

[0060] The plasticizing resin may have at least one, preferably 2 or 3, 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); - a number-average 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 preferred high Tg plasticizing resins are well known to those skilled in the art and commercially available, for example sold as: - polylimonene resins: by the company DRT under the name "Dercolyte L120" (Mn=625 g / mol; Mw=1010 g / mol; Ip=1.6; Tg=72°C) or by the company ARIZONA under the name "Sylvagum TR7125C" (Mn=630 g / mol; Mw=950 g / mol; Ip=1.5; Tg=70°C); - C5 / vinylaromatic cut copolymer resins, in particular C5 / styrene cut or C5 / C9 cut: 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" from the company DRT, 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 as CPD), dicyclopentadiene homopolymer or copolymer resins (abbreviated as DCPD), terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins, C9-cut homopolymer or copolymer resins, alpha-methyl-styrene 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 cut polymer or C9 cut homopolymer or copolymer resins, preferably the plasticizing resin is selected from the group consisting of terpene homopolymer or copolymer resins.

[0063] The term "terpene" here groups together in a known manner the alpha-pinene, beta-pinene and limonene monomers; preferably a limonene monomer is used, a compound which is present in a known manner 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 vinylaromatic monomers are, for example, styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyltoluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer from a C9 cut (or more generally from a C8 to C10 cut).

[0064] More particularly, mention may be made of plasticizing resins chosen from the group consisting of (D)CPD homopolymer resins, (D)CPD / styrene copolymer resins, polylimonene resins, limonene / styrene copolymer resins, limonene / D(CPD) copolymer resins, C5 / styrene cut copolymer resins, C5 / C9 cut copolymer resins, and mixtures of these resins.

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

[0066] Advantageously, the content of the plasticizing resin having a glass transition temperature greater than 20°C, in the composition in accordance with the invention, is within a range from 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 content is within a range from 6.5% to 18% by weight, preferably from 7% to 15% by weight, relative to the total weight of the rubber composition.

[0067] The content of the plasticizing resin having a glass transition temperature greater than 20°C in the composition in accordance with the invention may be within a range from 10 to 40 pce, preferably from 11 to 30 pce.

[0068] Although this is not necessary for the implementation of the present invention, the plasticizing system of the rubber composition according to the invention may comprise a plasticizer that is liquid at 23°C, known as a “low Tg” plasticizer, i.e. which by definition has a Tg of less than -20°C, preferably less than -40°C. According to the invention, the composition may optionally comprise from 0 to 30 pce of a plasticizer that is liquid 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 may be within a range from 4 to 20 pce, or from 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, can be used. At room temperature (23°C), these plasticizers or these oils, more or less viscous, are liquids (that is to say, as a reminder, substances having the capacity to eventually take the shape of their container), in contrast in particular to plasticizing resins which are by nature solid at room temperature.

[0071] Particularly suitable are liquid plasticizers at 23°C chosen from the group comprising or consisting of liquid diene polymers, polyolefin oils, naphthenic oils, paraffinic oils, DAE oils, MES (Medium Extracted Solvated) 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 mixtures thereof 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 may be any type of system known to those skilled in the art in the field of tire rubber compositions. It may in particular be based on sulfur, and / or peroxide and / or bismaleimides.

[0074] Preferably, the crosslinking system is sulfur-based, in which case it is 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, also preferably, various known vulcanization activators may be used, such as zinc oxide, stearic acid or equivalent compound such as stearic acid salts and transition metal salts, guanidine derivatives (in particular diphenylguanidine), or known vulcanization retarders.

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

[0076] Any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur may 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, but are not limited to, the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated as "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-tert-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 bandage according to the invention may optionally also comprise all or part of the usual additives usually used in elastomer compositions for tires, such as, for example, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, etc. II-6 Preparation of compositions

[0078] The compositions in accordance with the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first phase of working or thermomechanical mixing (so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents, in particular the elastomeric matrix, the reinforcing filler, any other various additives, with the exception of the crosslinking system, are introduced into a suitable mixer such as a conventional internal mixer (for example of the "Banbury" type). The incorporation of the filler into the elastomer can be carried out in one or more stages by thermomechanical mixing. In the case 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, it is the masterbatch which is directly kneaded and where appropriate the other elastomers or fillers present in the composition which 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 of between 110°C and 200°C, preferably between 130°C and 185°C, for a duration generally of between 2 and 10 minutes. - a second phase of mechanical work (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 everything 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, in the form of a sheet or plate, in particular for characterization in the laboratory, or extruded (or co-extruded with another rubber composition) in the form of a semi-finished (or profiled) rubber usable, for example, as a tread for a bicycle tire. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

[0081] The composition may be either in the raw state (before crosslinking or vulcanization), or in the cured state (after crosslinking or vulcanization), and may be a semi-finished product which may 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 bandage is intended to equip any type of bicycle without any particular limitation, whether or not they have an electrically assisted motor. Advantageously, the bicycle bandage is a bandage for a road bike, mountain bike or all-terrain bike, preferably, the bicycle bandage is a road bike bandage. The bicycle bandage may be a bicycle bandage.

[0084] A tire is a pneumatic or non-pneumatic tire. Pneumatic tires for bicycles are usually made up of a layer of carcass reinforcement anchored in two beads by turning around two bead wires. The beads are radially extended by the carcass ply itself extended by the tread. A pneumatic tire is intended, by definition, to contain compressed air when it is mounted on the bicycle wheel. A non-pneumatic tire, for its part, can come in different forms, for example a solid tire or not. As an example describing a non-pneumatic tire for a bicycle, we can cite application FR3042736A1. According to the invention, the tire according to the invention is preferably a pneumatic tire.

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

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

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

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

[0089] These tensile tests allow the determination of the yield stresses and the properties at break. Unless otherwise indicated, they are carried out in accordance with the French standard NF T 46-002 of September 1988. Processing of the tensile recordings also allows the modulus curve to be plotted as a function of the elongation. The modulus used here is the nominal (or apparent) secant modulus measured at first elongation, calculated by referring to the initial section of the test piece. The nominal secant modulus (or apparent stresses, in MPa) is measured at first elongation at 10%, 100% and 300% elongation, denoted MSA10, MSA 100 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, this also being a good descriptor of wear resistance, particularly in the field of bicycle tires.

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

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

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

[0095] In the following examples, the rubber compositions were produced as described in point II.6 above. In particular, the “non-productive” phase was carried out in a 0.4 liter mixer for 3.5 minutes, for 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 cylinder 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 Rubber composition tests

[0097] The examples presented below are intended to compare the performance compromise between wear resistance and rolling resistance of compositions in accordance with the present invention (C1 to C4) with control compositions (T1 and T2).

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

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

[0100] The control composition T2 differs from the composition C1 only by the nature of the SBR used. The SBR of the composition T2 is not in accordance with the invention in that its Tg is not less than -56°C.

[0101] Compositions C2 to C4 are in accordance with the invention and differ from composition C1 by the silica content (at a constant proportion of coupling agent relative to the mass of silica), by the presence of liquid plasticizer at 23°C or by the content of plasticizing resin respectively.

[0102] The results of the wear resistance and rolling resistance performances 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 to be 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 Resistance rolling (base 100 / r Tl) 168 261 318 246 182 Compromise 130 178 214 170 141

[0105] (1) Natural rubber (2) Polybutadiene neodymium 98% 1.4 cis - Tg = -110°C (3) SBR 1: Tin-functionalized solution SBR with 15% styrene units and 30% 1,2-polybutadiene units of the butadiene part (Tg = -64°C) (4) SBR 2: Tin-functionalized solution SBR with 21% styrene units and 62% polybutadiene 1,2 units of the butadiene part (Tg = -25 °C) (5) EPDM “Keltan 3960” from Arlanxeo with 56% ethylene motif and 11% ENB pattern (6) Polylimonene resin “Dercolyte L120” from DRT (Tg = 72°C) (7) Trioctyl phosphate (tri-2-ethylhexyl phosphate) “Disflamoll TOF” from Lanxess (8) Silica “Zeosil 1165MP” from Solvay (9) Liquid silane triethoxysilylpropyltetrasulfide (TESPT) “Si69” from Evonik

[0106] It has been found that the compositions in accordance with the invention have an ozone resistance equivalent to that of the reference composition.

[0107] Furthermore, the results presented in Table 1 above show that all the compositions in accordance with the invention also make it possible to improve rolling resistance by a factor greater than 1.7 compared to the reference composition Tl without too much impact on wear resistance, or even by improving it.

[0108] The control composition T2 certainly shows an improvement in rolling resistance, but at the expense of wear resistance performance. The performance compromise of composition T2 is lower than the compositions in accordance with the invention.

Claims

Claims

1. A bicycle tire comprising a tread, the tread comprising a rubber composition based on at least: - an elastomer 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, known as EPDM, said essentially unsaturated diene elastomer comprising at least one butadiene-styrene copolymer having a Tg of less than -56°C, - a reinforcing filler comprising silica, and - a crosslinking system.

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

3. A bandage according to any preceding claim, wherein the butadiene-styrene copolymer has a Tg in a range from -56°C to -80°C, preferably from -60°C to -70°C.

4. A tire according to any one of the preceding claims, wherein 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.

5. A tire according to any one of the preceding claims, wherein the EPDM has a propylene content ranging from 3% to 58% by weight, preferably from 17% to 42% by weight, relative to the weight of the EPDM.

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

7. A tire according to any preceding claim, 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. A tire according to any one of the preceding claims, wherein the level of EPDM in the elastomer matrix is in a range from 10% to 45% by weight, preferably from 15% to 40% by weight.

9. A bandage according to any preceding claim, 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. A tire according to any preceding claim, wherein the level of reinforcing filler in the rubber composition is in a range from 11 to 55 phr, preferably from 20 to less than 50 phr, preferably from 15 to 45 phr.

11. A tire according to any preceding claim, 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-methyl-styrene homopolymer or copolymer resins and mixtures thereof, preferably the plasticizing resin is selected from the group consisting of terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins or C9 cut copolymer.

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

13. A tire according to claim 11 or 12, wherein the level of the plasticizing resin in the rubber composition is in a range from 10 to 40 phr, preferably from 11 to 30 phr.

14. A bandage according to any preceding claim, wherein the crosslinking system is based on molecular sulfur and / or at least one sulfur donor agent.

15. A tire according to any preceding claim, wherein the bicycle tire is a road bike, mountain bike or hybrid bike tire, preferably the bicycle tire is a road bike tire.