Tyre for bicycle

Abstract

The invention relates to a tyre for a bicycle comprising a tread having improved wet grip, the tread comprising a rubber composition based on at least one elastomeric matrix comprising at least one butadiene-styrene copolymer, from 10 to 60 phr of a reinforcing filler comprising silica, and a crosslinking system, the rubber composition of the tread having a glass transition temperature in a range from -30.0°C to -10.0°C.

Description

[0001] BICYCLE BANDAGE

[0002] 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.

[0003] 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 baked compositions, while taking into account the baking properties and viscosity of their composition in the raw state (associated with the ease of industrial implementation of the compositions, or processability).

[0004] Given the environmental challenges associated with transportation, bicycles are increasingly used for both commuting and leisure. This increased use stems from a rise in the number of cyclists, as well as an increase in the frequency with which they ride. In particular, weather conditions are becoming less and less of a deterrent to cycling. In this context, one of the main challenges for bicycle tires is providing good grip on wet surfaces.

[0005] To improve the wet grip of bicycle tires, it is known to increase the tread depth, that is, to increase, within certain limits, the number of grooves, channels, or sipes in the tread. Therefore, the main solutions for improving wet grip lie in modifying the tread pattern or structure.

[0006] However, it is still advantageous to further improve the wet grip of bicycle tires, preferably without degrading other expected properties such as rolling resistance, dry grip and wear resistance.

[0007] Therefore, there is a need for bicycle tires with improved wet grip without compromising other performance characteristics, particularly rolling resistance (which reflects the energy supplied by the cyclist or the battery in the case of an e-bike), the stiffness of the cured compounds (which reflects the ability to keep the handlebars straight after contact with a branch or stone, or with the ground after a jump), dry grip, and wear resistance. Bicycle tires, due to the nature of these vehicles (weight, wheel size, tire design and geometry, usage conditions, etc.), are subject to very specific stresses.The simple transposition of existing solutions from other fields, for example that of motorcycle tires, to the field of bicycle tires is therefore not envisaged by the person skilled in the art of bicycle tires.

[0008] Continuing her research, the Plaintiff unexpectedly discovered that it was possible to improve the wet grip 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:

[0010] - an elastomeric matrix comprising at least one butadiene-styrene copolymer, - 10 to 60 parts per annum of a reinforcing filler comprising silica, and

[0011] - a crosslinking system, in which the rubber composition of the tread has a glass transition temperature in the range of -30.0°C to -10.0°C, preferably -26.0°C to -15.5°C, preferably -25.0°C to -16.0°C.

[0012] In the present, unless otherwise indicated, the expressions "rubber composition" or "composition(s) according to the invention" refer to the rubber composition of the tread of the bicycle tire according to the invention.

[0013] I- DEFINITIONS

[0014] 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.

[0015] By "elastomer matrix" we mean all the elastomers in the composition, including any ethylene-propylene-diene (EPDM) copolymers that may be present.

[0016] Unless otherwise specified, the unit percentages resulting from the insertion of a monomer into a copolymer are expressed as a mole percentage relative to the total monomer units of the copolymer. For the purposes of this invention, the term "part by weight per hundred parts by weight of elastomer" (or pc) means the mass proportion per hundred parts by weight of elastomer present in the rubber composition in question, including any EPDM.

[0017] In this document, unless expressly stated otherwise, all percentages (%) shown are percentages (%) by mass.

[0018] 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 (that is, 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 (that is, including the strict bounds a and b). In this context, when an interval of values ​​is designated by the expression "from a to b," it also and preferentially designates the interval represented by the expression "between a and b."

[0019] The compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they may be partially or entirely derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of previously used materials; that is, they may be partially or entirely produced through a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0020] Unless otherwise specified, the glass transition temperature "Tg" of the ingredients present in a composition is measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM D3418 (1999).

[0021] The Tg of the rubber compositions is measured using a VA400 viscoanalyzer marketed by Metravib, in accordance with ASTM D5992-96. The response of a crosslinked material sample (double shear geometry, each of the two cylindrical samples being 10 mm in diameter and 2 mm thick) was recorded while subjected to a single alternating sinusoidal shear stress of constant value 0.34 MPa at a frequency of 10 Hz over a temperature sweep from -60°C to 100°C, with the temperature increasing at a rate of 1.5°C / min. The temperature at which the maximum tan(φ) occurred was recorded as the Tg of the composition. II- DESCRIPTION OF THE INVENTION

[0022] II- 1 Rubber Composition

[0023] The rubber composition of the tread of the tire according to the invention has the essential characteristic of exhibiting a Tg within a range from -30.0°C to -10.0°C. The Tg of the rubber composition is, as is well known to those skilled in the art, measured on the composition in the crosslinked state, that is to say after crosslinking of said composition.

[0024] This specific Tg range, combined with a specific rate of reinforcing filler including silica, unexpectedly results in improved wet grip of bicycle tire tread compositions.

[0025] A person skilled in the art knows how to obtain a rubber composition with a specific Tg based on the nature and levels of the ingredients used in the rubber composition, particularly based on the Tg and levels of elastomers, and the Tg and levels of plasticizers (plasticizing resins and / or liquid plasticizer at 23°C) possibly present in the composition.

[0026] In a particularly advantageous manner, especially for grip on wet ground, the rubber composition of the tread of the tire according to the invention has a Tg within a range of -26.0°C to -15.5°C, preferably from -25.0°C to -16.0°C.

[0027] The elastomeric matrix of the rubber composition of the tire tread according to the invention comprises at least one styrene-butadiene rubber compound (SBR). Indeed, SBRs offer the advantage of having very wide temperature ranges, from -90°C to 0°C, which is useful for those skilled in the art who wish to obtain a rubber composition with a specific temperature range. The elastomeric matrix of the rubber composition of the tire tread according to the invention may also comprise one or more other diene elastomers, in particular one or more essentially unsaturated diene elastomers.

[0028] A "diene" elastomer (or, indiscriminately, rubber), whether natural or synthetic, is generally understood to be an elastomer composed at least in part (i.e., a homopolymer or a copolymer) of diene monomer units (monomers bearing two carbon-carbon double bonds, conjugated or not). These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated".In general, "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of motifs or units of diene origin (conjugated dienes) which is greater than 15% (mole percent); thus, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the previous definition and can in particular be described as "essentially saturated" diene elastomers (proportion of motifs of diene origin low or very low, always less than 15%).

[0029] Suitable conjugated dienes are those with 4 to 12 carbon atoms, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0030] Advantageously, the essentially unsaturated elastomer(s) are one or more diene elastomers derived at least in part from conjugated diene monomers, having a diene motif or unit content greater than 30% by mole, preferably greater than 50% by mole. These are preferably essentially unsaturated elastomers selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers, preferably from polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene-styrene copolymers (SBR), and mixtures of these elastomers.

[0031] Those with a -1,2 unit content (molar %) 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 boiling point (Tg) between 0°C and -90°C, a styrene content between 1% and 60% by weight (and more specifically between 10% and 50%), a -1,2 unit content (molar %) of the butadiene moiety between 4% and 75%, and a trans-1,4 unit content (molar %) between 10% and 80% are particularly suitable as butadiene-styrene copolymers. It should be noted that SBR can be prepared as an emulsion (ESBR) or as a solution (SSBR).

[0032] The essentially unsaturated diene elastomer, in particular SBR, can be modified, i.e., either coupled and / or star-shaped, or functionalized, or coupled and / or star-shaped and simultaneously functionalized. Preferably, the SBR in the rubber composition is functionalized with at least one functional group as defined below.

[0033] 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, we mean a group comprising at least one heteroatom chosen 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.

[0034] Advantageously, the elastomeric matrix comprises a mixture of essentially unsaturated diene elastomers. In particular, it may comprise several butadiene-styrene copolymers that may differ in their Tg.

[0035] In particular, at least one essentially unsaturated diene elastomer may comprise natural rubber and one or more butadiene-styrene copolymers. 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, and from 5% to 50% by weight, preferably from 10% to 30% by weight, of natural rubber.

[0036] At least one essentially unsaturated diene elastomer may also further comprise polybutadiene. In this case, the essentially unsaturated diene elastomer of the elastomer matrix may comprise 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; and from 5% to 40% by weight, preferably from 10% to 30% by weight, of polybutadiene. Advantageously, the elastomer matrix does not comprise butadiene or comprises less than 10% by weight, preferably less than 5% by weight, relative to the total weight of the elastomer matrix. Preferably, the elastomer matrix does not comprise butadiene.

[0037] The elastomeric matrix may further comprise one or more ethylene-propylene-diene (EPDM) copolymers.

[0038] Any EPDM material can be used in the context of the present invention. However, the use of a specific type of EPDM may be advantageous in the context of the present invention. The EPDM may be a single type or a mixture of several types.

[0039] In particular, EPDM preferably has an ethylene content of 41% to 75% by weight, preferably 50% to 71.5% by weight, relative to the weight of EPDM. EPDM also advantageously has a propylene content of 13% to 58% by weight, preferably 17% to 42% by weight, relative to the weight of EPDM.

[0040] EPDM also advantageously presents a diene content ranging from 1% to 12% by weight, preferably from 8% to 11.5% by weight, relative to the weight of EPDM.

[0041] The diene in EPDM can be selected from the group consisting of ethylidene norbornene, dicyclopentadiene, and mixtures thereof. Preferably, the diene in EPDM is ethylidene norbornene, in particular 5-ethylidene-2-norbornene (ENB).

[0042] The ethylene, propylene and diene levels of EPDM can be determined by infrared according to ASTM D3900 for ethylene and propylene levels and ASTM D6047 for diene levels.

[0043] The EPDM content in the elastomer matrix of the composition according to the invention is preferably in the range of 5% to 50% by weight, for example 10% to 45% by weight, for example 15% to 40% by weight.

[0044] However, for the purposes of the invention, it may be advantageous for the elastomeric matrix to contain little or no EPDM. Thus, the rubber composition of the tread of the bicycle tire according to the invention advantageously contains no EPDM or less than 4.9% by weight, preferably less than 4% by weight, preferably less than 2% by weight, and preferably less than 1% by weight. Even more preferably, the elastomeric matrix contains no EPDM at all.

[0045] Thus, the elastomeric matrix of the rubber composition of the bicycle tire tread advantageously comprises 50% to 100%, preferably 80% to 100%, preferably 95.1% to 100%, preferably 96% to 100%, preferably 98% to 100%, preferably 99% to 100%, by weight, of essentially unsaturated diene elastomer, including at least one butadiene-styrene copolymer. Preferably, it comprises 100% by weight of essentially unsaturated diene elastomer, including at least one butadiene-styrene copolymer.

[0046] The rubber composition of the tread of the bicycle tire according to the invention comprises 10 to 60 parts per annum of a reinforcing filler, known for its ability to strengthen a rubber composition suitable 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.

[0047] According to the invention, the reinforcing filler comprises silica. It may further comprise another reinforcing filler, in particular carbon black.

[0048] Suitable silicas include any type of precipitated silica, particularly highly dispersible precipitated silicas (known 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 W003 / 016215-A1 and W003 / 016387-A1. Among commercial HDS silicas, the following can be used: "Ulsilsil® 5000GR" and "Ulsilsil® 7000GR" from Evonik, and "Zeosil® 1085GR", "Zeosil® 1115 MP", "Zeosil® 1165 MP", "Zeosil® Premium 200 MP", and "Zeosil® HRS 1200 MP" from Solvay.As non-HDS silica, the following commercial silicas may be used: “Ultrasil ® VN2GR”, “Ultrasil ® VN3GR” silicas from Evonik, “Zeosil® 175GR” silica from Solvay, “Hi-Sil EZ120G(-D)”, “Hi-Sil EZ160G(-D)”, “Hi-Sil EZ200G(-D)”, “Hi-Sil 243LD”, “Hi-Sil 210”, “Hi-Sil HDP 320G” silicas from PPG.

[0049] To couple silica to the diene elastomer, a well-known coupling agent (or bonding agent) is used, at least bifunctional, to ensure sufficient chemical and / or physical connection between the inorganic filler (the surface of its particles) and the diene elastomer. Organosilanes or polyorganosiloxanes, at least bifunctional, are particularly used. "Bifunctional" means a compound possessing 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 might include a first functional group comprising a silicon atom, which is capable of interacting with the hydroxyl groups of an inorganic filler, and a second functional group comprising a sulfur atom, which is capable of interacting with the diene elastomer.

[0050] Preferably, 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 TESPD 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.

[0051] 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.

[0052] Silica advantageously presents a specific surface area BET within a range of 140 to 200 m² 2 / g, preferably from 150 to 170 m 2 / g, preferably from 155 to 168 m 2 / g.

[0053] Its specific surface area BET of silica is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" (Vol. 60, page 309, February 1938), and more specifically according to a method adapted from the standard NF ISO 5794-1, Annex E of June 2010 [multipoint volumetric method (5 points) - gas: nitrogen - degassing under vacuum: one hour at 160°C - relative pressure range w / in: 0.05 to 0.17],

[0054] Advantageously, the rate of reinforcing charge, in the composition, is within a range of 25 to less than 55 pc, preferably 30 to 50 pc, preferably 35 to less than 50 pc.

[0055] The reinforcing filler may include carbon black at a rate of less than 10 parts per cubic centimeter, preferably less than 5 parts per cubic centimeter. Advantageously, the composition includes no carbon black or less than 1 part per cubic centimeter.

[0056] The reinforcing filler may comprise more than 50% to 100% by weight, preferably 80% to 100% by weight, preferably 95% to 100% by weight, of silica relative to the total weight of the reinforcing filler. In particular, the reinforcing filler may comprise 100% by weight of silica. This is especially useful when you want to color the tread of the bicycle tire using pigments.

[0057] The plasticizing system of the rubber compound in the tread of the bicycle tire according to the invention may comprise at least one plasticizing resin having a glass transition temperature above 20°C, referred to as a "high Tg" (also called a "plasticizing resin" herein for the sake of simplicity). As stated above, plasticizing resins are useful compounds for adjusting the Tg of the rubber compound. The term "resin" is reserved in this application, by definition known to those skilled in the art, for a compound that is solid at room temperature (23°C), as opposed to a liquid plasticizing compound such as an oil.

[0058] Plasticizing resins are polymers well known to those skilled in the art, primarily carbon- and hydrogen-based but potentially containing other types of atoms. They are particularly useful as plasticizing or tackifying agents in polymer matrices. They are generally inherently miscible (i.e., compatible) with the polymer compositions for which they are intended, acting as true diluents. They were described, for example, in the book "Hydrocarbon Resins" by R. Mildenberg, M. Zander, and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), Chapter 5 of which is devoted to their applications, particularly in pneumatic rubber (5.5. "Rubber Tires and Mechanical Goods"). 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, 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).

[0059] These plasticizing resins are known to be thermoplastic resins because they soften upon heating and can therefore be molded. They can also be defined by their 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.

[0060] As a reminder, SEC analysis, for example, involves 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:

[0061] - elution solvent is tetrahydrofuran; - temperature 35°C;

[0062] - concentration 1 g / litre;

[0063] - flow rate: 1 ml / min;

[0064] - injected volume: 100 pl;

[0065] - Moore calibration with polystyrene standards;

[0066] -set of 3 "Waters" columns in series ("Styragel HR4E", "Styragel HR1" and "Styragel HR 0.5");

[0067] - detection by differential refractometer (for example "WATERS 2410") which can be equipped with operating software (for example "Waters Millennium").

[0068] A Moore calibration is performed using a series of commercial polystyrene standards with a low Ip value (less than 1.2) and known molar masses, covering the range of masses to be analyzed. From the recorded data (mass distribution curve of molar masses), the mass average molar mass (Mw), the number average molar mass (Mn), and the polymolecularity index (Ip = Mw / Mn) are deduced.

[0069] All molar mass values ​​indicated in this application are therefore relative to calibration curves made with polystyrene standards.

[0070] The plasticizing resin may exhibit at least one, preferably two or three, and more preferably all of the following characteristics:

[0071] - 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);

[0072] - a softening point above 50°C (in particular between 50°C and 150°C);

[0073] - an average number molar mass (Mn) between 300 and 2000 g / mol, preferably between 400 and 1500 g / mol;

[0074] - a polymolecularity index (Ip) less than 3, preferably 2 (reminder: Ip = Mw / Mn with Mw average molar mass by weight).

[0075] 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:

[0076] - 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);

[0077] - 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 Koi on under the names "Hikorez T1095" and "Hikorez T1100", by Exxon under the names "Escorez 2101" and "Escorez 1273";

[0078] - 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".

[0079] 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-methyl-styrene homopolymer or copolymer resins and their mixtures. Preferably, the plasticizing resin is chosen from the group consisting of terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins or C9-cut homopolymer or copolymer resins, preferably the plasticizing resin is chosen from the group consisting of terpene homopolymer or copolymer resins.

[0080] The term "terpene" here includes the known monomers alpha-pinene, beta-pinene and limonene; preferentially, a limonene monomer is used, a compound known to exist in the form of three possible isomers: L-limonene (levorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or dipentene, a 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 Cs to C10 cut).

[0081] 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.

[0082] Preferably, the plasticizing resin comprises or is one or more terpene resins, preferably it comprises or is one or more polylimonene resins. All the above-mentioned 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 or C5 / C9 cut resins, or by Struktol under the names "40 MS" or "40 NS" (mixtures of aromatic and / or aliphatic resins).

[0083] The proportion of the plasticizing resin having a glass transition temperature above 20°C in the rubber composition can be in the range of 5.0% to 20.0% by weight relative to the weight of the rubber composition of the tread of the bicycle tire according to the invention. Preferably, this proportion is in the range of 5.1% to 15.0% by weight, and more preferably 5.2% to 14.0% by weight, relative to the total weight of the rubber composition.

[0084] The proportion of the plasticizing resin having a glass transition temperature above 20°C in the composition according to the invention can be in the range of 10 to 40 parts per cent, preferably 11 to 30 parts per cent.

[0085] 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. In particular, the composition according to the invention may optionally include from 0 to 30 parts per cent of liquid plasticizer at 23°C.

[0086] When a liquid plasticizer at 23°C is used, its level in the composition according to the invention can be in the range of 5 to 30 parts per cent, preferably 15 to 25 parts per cent.

[0087] Any plasticizer that is liquid at 23°C (or extending oil), whether aromatic or non-aromatic, known for its plasticizing properties with respect to diene elastomers, is suitable. At room temperature (23°C), these plasticizers or oils, with varying degrees of viscosity, are liquids (that is, substances that can eventually take the shape of their container), unlike plasticizing resins, which are solid at room temperature.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.

[0088] Preferably, the liquid plasticizer at 23°C is chosen from the group comprising or consisting of TDAE oils, vegetable oils and their mixtures.

[0089] The crosslinking system used in the rubber compound can be any type of system known to those skilled in the art in the field of tire rubber compounds. It may, in particular, be sulfur-based, and / or peroxide-based, and / or bismaleimide-based.

[0090] Preferably, the crosslinking system is sulfur-based; this is then referred to as a vulcanization system. Advantageously, the vulcanization system is based on molecular sulfur and / or at least one sulfur-donating agent. At least one vulcanization accelerator is also preferably present, and optionally, 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 particular diphenylguanidine), or known vulcanization retarders may be used.

[0091] Sulfur is used at a preferential rate of between 0.5 and 12 parts per thousand (ppm), particularly between 1 and 10 ppm. The vulcanization accelerator is used at a preferential rate of between 0.5 and 10 ppm, more preferably between 0.5 and 5.0 ppm.

[0092] Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used as an accelerator, including thiazole-type accelerators and their derivatives, sulfenamide-type accelerators, thiurams, dithiocarbamates, dithiophosphates, thioureas and xanthates. 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.

[0093] 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.

[0094] II-2 Preparation of compositions

[0095] Rubber compositions according to the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art:

[0096] - 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.Where the filler is already fully or partially incorporated into the elastomer as a masterbatch, as described, for example, in applications WO 97 / 36724 or WO 99 / 16600, the masterbatch is mixed directly. If necessary, other elastomers or fillers present in the composition that are not in masterbatch form are then incorporated, along with 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.

[0097] - 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.

[0098] Such phases have been described, for example, in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300, and WO00 / 05301. The resulting final composition 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 profiled) 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.

[0099] The composition can be either in its raw state (before crosslinking or vulcanization), or in its cooked state (after crosslinking or vulcanization), and can be a semi-finished product that can be used in a tire.

[0100] 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.

[0101] II-3 Bicycle Bandage

[0102] According to the invention, the tire is designed to fit any type of bicycle without any particular limitation, whether or not it has an electric assist motor. Advantageously, the bicycle tire is a tire for (preferably) road bikes, mountain bikes, or hybrid bikes. A hybrid bike can be a "gravel" or "cyclocross" bike. A mountain bike can be a touring mountain bike, an all-mountain bike, a cross-country (or XC) mountain bike, a down-country (or DC) mountain bike, a trail bike, or a gravity bike.

[0103] The term "tire" refers to a tire, whether pneumatic or non-pneumatic. Pneumatic bicycle tires typically consist of a carcass reinforcement layer anchored in two beads by folding it around two wires. The beads are radially extended by the carcass ply, which is itself extended by the tread. A pneumatic tire is designed, by definition, to contain compressed air when mounted on the bicycle wheel. A non-pneumatic tire, on the other hand, can take various forms, for example, a solid or non-solid tire. As an example describing a non-pneumatic bicycle tire, we can cite French patent application FR3042736A1. According to the invention, the tire according to the invention is preferably a pneumatic tire.

[0104] The tire according to the invention can 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 can also be a non-pneumatic tire, either solid or airless.

[0105] The width (or cross-section) of the bicycle tire according to the invention can be within a range of 20 to 80 mm, preferably from 30 to 75 mm. The width of the tire is measured on the mounted tire and under the pressure recommended by the manufacturer in the case of pneumatic tires according to ETRTO 2024, "Cycle Tyres", Section B.2, cross-section value "(s)".

[0106] III- EXAMPLES

[0107] III- 1 Measurements and tests used

[0108] Dynamic properties

[0109] The dynamic properties (Tg and integral of the observed tan(φ) value from -30°C to 0°C (Int. tan(φ) [-30°C ; 0°C])) of the rubber compositions were measured on a VA400 viscoanalyzer marketed by Metravib, in accordance with ASTM D5992-96. The response of a crosslinked material sample (double shear geometry, each of the two cylindrical samples 10 mm in diameter and 2 mm thick) was recorded while subjected to a single alternating sinusoidal shear stress of constant value 0.34 MPa and a frequency of 10 Hz over a temperature sweep from -60°C to 100°C, with the temperature increasing at a rate of 1.5°C / min. The temperature at which the maximum tan(φ) appeared was recorded as the glass transition temperature, Tg.

[0110] It should be noted that, as is well known to those skilled in the art, the integral of the tan(φ) value observed from -30°C to 0°C is representative of wet grip. The performance results for Int. tan(φ) [-30°C; 0°C] are expressed as a base of 100, with 100 being assigned to the control compound TL. A result greater than 100 indicates that the compound exhibits better wet grip.

[0111] III-2 Preparation of compositions

[0112] In the following examples, the rubber compounds were prepared as described in section II.2 above. Specifically, the "non-productive" phase was carried out in a 0.4-liter mixer for 3.5 minutes, at an average paddle speed of 50 rpm, 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.

[0113] 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

[0114] The examples presented below are intended to compare the wet surface adhesion performance of compositions according to the present invention (Cl to C3) with control compositions (Tl to T2).

[0115] Table 1 presents the compositions tested (in pieces), as well as the results obtained. In addition to the ingredients listed in Table 1, the tested formulations all contain 1.5 parts per annum of cyclic acetal "Vulkazon AFS / LG" from Lanxess, 2 parts per annum of ozone-blocking wax "VARAZON 4959" from Sasol Wax, 2 parts per annum of black pigment "MICROLEN BK 0062 MCN" from Sun Chemical, 1.5 parts per annum of diphenylguanidine "Perkacit DPG" from Flexsys, 3.5 parts per annum of industrial-grade zinc oxide from Umicore, 2 parts per annum of stearic acid "Pristerene 4931" from Uniqema, 3.5 parts per annum of sulfur and 2 parts per annum of N-cyclohexyl-2-benzothiazol-sulfenamide "Santocure CBS" from Flexsys, as a vulcanization accelerator.

[0116] [Table 1]

[0117] (1) Natural rubber

[0118] (2) SBR “Sprintan® SLR 4602” from the company Resinex (Tg = -25°C)

[0119] (3) SBR with 40% styrene motifs and 16% polybutadiene 1,2 motifs in the butadiene part, 14% cis motif in the butadiene part and 70% trans motif in the butadiene part (Tg = -30°C)

[0120] (4) SBR “Sprintan® SLR 3402” (Tg = -62°C)

[0121] (5) EPDM “Keltan 3960” from Arlanxeo with 56% ethylene pattern and 11% ENB pattern

[0122] (6) Polylimonene resin “Dercolyte L120” from the company DRT (Tg = 72°C)

[0123] (7) Paraffinic oil “Tudalen 1968” from the company Klaus Dahleke (8) TDAE oil “Flexon 630” from the company Shell

[0124] (9) Silica “Zeosil 1165MP” from the Solvay company

[0125] (10) Liquid silane triethoxysilylpropyltetrasulfide (TESPT) “Si69” from the company Evonik. Furthermore, the results presented in Table 1 above show that all compositions according to the invention, having both a reinforcing filler content of silica of 10 to 60 pce and a Tg of -30.0°C to -10.0°C, greatly improve adhesion on wet ground compared to compositions whose Tg is not between -30.0°C and -10.0°C, or compared to a composition not including 10 to 60 pce of reinforcing filler including silica.

Claims

1. Demands 1. Bicycle tire comprising a tread, the tread comprising a rubber composition based on at least: - an elastomeric matrix comprising at least one butadiene-styrene copolymer, - 10 to 60 pieces of a reinforcing filler comprising silica, and - a crosslinking system, in which the rubber composition of the tread has a glass transition temperature in the range of -30.0°C to -10.0°C.

2. Bandage according to claim 1, in which the glass transition temperature of the rubber composition is in a range from -26.0°C to -15.5°C.

3. Bandage according to claim 1, wherein the glass transition temperature of the rubber composition is in a range from -25.0°C to -16.0°C.

4. Bandage according to any one of the preceding claims, wherein the reinforcing filler comprises more than 50% to 100% by weight, preferably 80% to 100% by weight of silica relative to the total weight of reinforcing filler.

5. Bandage according to any one of the preceding claims, wherein the rate of reinforcing filler in the rubber composition is in the range of 25 to less than 55 pc, preferably 30 to 50 pc, preferably 35 to less than 50 pc.

6. Bandage according to any one of the preceding claims, wherein the silica has a specific surface area BET in the range of 140 to 200 m² 2 / g, preferably from 150 to 170 m 2 / g, preferably from 155 to 168 m 2 / g.

7. Bandage according to any one of the preceding claims, wherein the reinforcing filler comprises carbon black at a rate of less than 10 pc, preferably less than 5 pc.

8. Bandage according to any one of the preceding claims, wherein the rubber composition comprises from 5.0% to 20.0% by weight, preferably of 5.1% to 15.0% by weight, of at least one plasticizing resin having a Tg greater than 20°C, relative to the weight of the rubber composition.

9. Bandage according to claim 8, wherein the plasticizing resin is 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 is selected from the group consisting of terpene homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins or C9-cut homopolymer or copolymer resins.

10. Bandage according to any one of claims 8 to 9, 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.

11. Bandage according to any one of the preceding claims, wherein the elastomeric matrix of the rubber composition does not comprise ethylene-propylene-diene copolymer or comprises less than 4.9% by weight, preferably less than 4% by weight.

12. Bandage according to any one of claims 1 to 10, wherein the elastomeric matrix of the rubber composition does not comprise an ethy-1-ene-propy-1-ene-diene copolymer.

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

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

15. Bandage according to any one of the preceding claims, wherein the width of the bandage is in a range of 20 to 80 mm, preferably 30 to 75 mm.

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