Rubber composition comprising a hydrocarbon wax based on a pyrolysis fraction

Abstract

The invention relates to a rubber composition based on at least one elastomeric matrix, a reinforcing filler, a crosslinking system and a hydrocarbon wax based on a cut obtained from the pyrolysis of a filler comprising mainly polyethylene, said cut comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms.

Description

Title of the invention: Rubber composition comprising a hydrocarbon wax based on a pyrolysis fraction. Technical field of the invention

[0001] The present invention relates to the field of rubber compositions, in particular rubber compositions for pneumatic tires. Previous art

[0002] Pneumatic tires, and more generally rubber articles such as conveyor belts and non-pneumatic tires, are complex objects made up of a multitude of components. For example, a pneumatic tire is made up of more than 200 different raw materials.

[0003] While some raw materials such as natural rubber are derived from renewable resources, many components of pneumatic tires are still obtained from fossil resources. It is therefore crucial to minimize the use of these resources by using bio-based materials or by recycling used materials.

[0004] However, the recycling of materials, for example from used rubber or plastic articles, is still limited, particularly due to the significant impact of the constituents on tire performance. Indeed, recycling materials can have a negative overall environmental impact due to the degradation of the performance of tires using these materials.

[0005] Much research has been conducted in the field of product recycling for use in tires, particularly on the recovery of oils from the pyrolysis of tire waste. For example, documents EP 0928817, WO 2013 / 170358, and JP2017 / 008214 describe the production of tire-grade carbon black from the pyrolysis of tire tire chips. Other research focuses on the recovery of intermediate products. Document WO 90 / 14409 examines the separation of pyrolysis oils from tire waste by distillation in order to recover valuable chemical compounds, particularly limonene.

[0006] Document CA 3 032 242 describes the catalytic depolymerization of plastics for the manufacture of monomers and waxes. However, the use of the effluents produced is not addressed.

[0007] Continuing its research, the applicant discovered that a rubber composition comprising a hydrocarbon wax obtained from the pyrolysis of a charge composed mainly of polyethylene, it offers improved fatigue resistance performance while preserving other characteristics. Definitions

[0008] The carbon-containing compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass.

[0009] By Cn compound, we mean a compound comprising n carbon atoms. Similarly, by Cn-Cm compounds, we mean a set of compounds comprising from n to m carbon atoms.

[0010] By heteroatom, we mean an atom other than carbon or hydrogen, for example nitrogen, sulfur, oxygen.

[0011] By majority means, in a known way, representing at least 50% by weight. Detailed description of the invention

[0012] The invention relates to a rubber composition based on at least one elastomeric matrix, a reinforcing filler, a crosslinking system and a hydrocarbon wax based on a cut obtained from the pyrolysis of a filler comprising mainly polyethylene, said cut comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms. Rubber composition Elastomer

[0013] The rubber composition according to the invention comprises at least one elastomer, preferably a diene elastomer. By diene elastomer, it should be understood that an elastomer which is derived at least in part (i.e. a homopolymer or a copolymer) from diene monomers (monomers bearing two carbon-carbon double bonds, conjugated or not).

[0014] These diene elastomers can be classified into two categories: "essentially unsaturated" or "essentially saturated". Generally, "essentially unsaturated" means a diene elastomer derived at least in part from conjugated diene monomers, having a proportion of diene motifs or units (conjugated dienes) greater than 15% (mol%); thus, diene elastomers such as butyl rubbers or EPDM-type diene-alpha-olefin copolymers do not fall under the preceding definition and can be described, in particular, as "essentially saturated" diene elastomers (low or very low proportion of diene motifs, always less than 15% (mol%)). diene elastomers included in the rubber composition according to the invention are preferably essentially unsaturated.

[0015] The term diene elastomer, which can be used in rubber compositions according to the invention, is particularly understood to mean:

[0016] a) any homopolymer of a diene monomer, conjugated or not, having from 4 to 18 carbon atoms;

[0017] b) any copolymer of a diene, conjugated or not, having from 4 to 18 carbon atoms and at least one other monomer.

[0018] The other monomer may be ethylene, an olefin or a diene, conjugated or not.

[0019] Conjugated dienes with 4 to 12 atoms are suitable. of carbon, in particular 1,3-dienes, such as 1,3-butadiene and isoprene.

[0020] Suitable olefins are vinylaromatic compounds having 8 to 20 carbon atoms and aliphatic α-monoolefins having 3 to 12 carbon atoms.

[0021] Suitable examples of vinylaromatic compounds include styrene, ortho-, meta-, para-methylstyrene, the commercial "vinyl-toluene" mixture, para-tert-butylstyrene.

[0022] As aliphatic α-monoolefins, acyclic aliphatic α-monoolefins having from 3 to 18 carbon atoms are particularly suitable.

[0023] The diene elastomer is preferably a diene elastomer of the highly unsaturated type, in particular a diene elastomer selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), polybutadienes (BR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers. Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-butadiene-styrene copolymers (SBIR), ethylene-butadiene copolymers (EBR) and mixtures of such copolymers.

[0024] The above diene elastomers can, for example, be block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they can be coupled and / or star-shaped or functionalized with a coupling and / or star-shaped or functionalizing agent, for example epoxy-coated.

[0025] By "isoprene elastomer" is meant a homopolymer or a copolymer of isoprene, in other words a diene elastomer selected from the group consisting of natural rubber (NR) which can be plasticized or peptized, synthetic polyisoprenes (IR), the various isoprene copolymers, in particular isoprene-styrene copolymers (SIR), isoprene-butadiene copolymers (BIR) or isoprene-butadiene-styrene copolymers (SBIR), and mixtures of these elastomers.

[0026] Preferably, the composition according to the invention comprises at least 50 pieces of at least one butadiene elastomer, preferably chosen from the group consisting of polybutadienes, butadiene copolymers and mixtures thereof, preferably chosen from the group consisting of polybutadienes, butadiene-styrene copolymers and mixtures thereof.

[0027] According to a preferred embodiment of the invention, the butadiene elastomer is a butadiene copolymer having a glass transition temperature (Tg) below -20 °C, preferably between -20 °C and -110 °C, more preferably between -60 °C and -110 °C, more preferably between -60 °C and -90 °C. Such elastomers are known to those skilled in the art and are described, for example, in documents WO2015 / 185394 and WO2017 / 168099.

[0028] Preferably and according to this embodiment, the composition according to the invention comprises at least 70 parts, preferably at least 90 parts, of at least one butadiene copolymer, preferably a butadiene-styrene copolymer.

[0029] Preferably, according to any one of the embodiments of the invention, the composition according to the invention further comprises at least 20 parts of an isoprene elastomer selected from the group consisting of natural rubber, synthetic polyisoprenes and their mixtures. Reinforcing load

[0030] The rubber composition according to the invention comprises a reinforcing filler. Any type of reinforcing filler known for its ability to reinforce an elastomeric composition usable for the manufacture of pneumatic tires can be used, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica, or a blend of these two types of filler, in particular a blend of carbon black and silica.

[0031] All carbon blacks are suitable as carbon blacks, particularly those of the HAF, ISAF, and SAF types conventionally used in tires (so-called tire-grade blacks). Among these, carbon blacks of the 100, 200, or 300 series (ASTM grades) are particularly suitable, such as NI 15, N134, N234, N326, N330, N339, N347, and N375, or, depending on the intended application, blacks of higher series (e.g., N660, N683, N772). Carbon blacks could, for example, already be incorporated into an isoprene elastomer in the form of a masterbatch (see, for example, applications WO 97 / 36724 or WO 99 / 16600). The specific surface area BET of carbon blacks is measured according to standard D6556-10 [multipoint method (minimum 5 points) - gas: nitrogen - relative pressure range P / P0: 0.1 to 0.3].

[0032] In this application, the term "reinforcing inorganic filler" shall be understood, by definition, as any inorganic or mineral filler (regardless of its color and of natural or synthetic origin), also called "white" filler, "light" filler or even "non-black filler" as opposed to carbon black, capable of reinforcing on its own, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words suitable for replacing, in its reinforcing function, a conventional carbon black of pneumatic grade; such a filler is generally characterized, in a known way, by the presence of hydroxyl groups (-OH) on its surface.

[0033] Inorganic reinforcing fillers are suitable in particular mineral fillers of the siliceous type, preferably silica (SiO2) or of the aluminous type, in particular alumina (Al2O3).

[0034] The silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenated silica.

[0035] Precipitated silica can be produced from raw materials derived from inorganic sand (silicon dioxide from inorganic sand), from recycled materials such as foundry sands, end-of-life tires and in particular the treads of end-of-life tires comprising mainly silica as a reinforcing filler or from bio-based raw materials such as organic waste from plants, preferably inedible organic waste from plants.

[0036] Among the plants having silicon dioxide in their tissues, we can mention mustard, in particular mustard husks, grasses and more particularly among grasses bamboo leaves, ears of corn, sugar cane bagasse, rice, wheat, in particular rice husks, wheat husks.

[0037] Silica derived from non-renewable raw materials such as natural inorganic sand is usually obtained by heating sand in a glass furnace in the presence of sodium carbonate. The resulting sodium silicate is then dissolved in water, possibly in the presence of a base such as sodium hydroxide. Precipitated synthetic silica is formed from this aqueous solution by controlled treatment of the silicate with an acid (e.g., a mineral acid and / or an acidifying gas such as carbon dioxide). Sometimes, an electrolyte (e.g., sodium sulfate) may be present to promote the formation of precipitated silica particles. The recovered precipitated silica is amorphous precipitated silica.

[0038] Silica derived from bio-based raw materials such as those mentioned above can, for example, be obtained by burning the bio-based raw material to recover the ash, which consists mainly of silicon dioxide. This can be done, for example, with rice husks, and in a process equivalent to that described above for silica derived from other raw materials. Whether mineral or recycled, rice husk ash is generally treated with a strong base, such as sodium hydroxide, to form an aqueous silicate solution (e.g., sodium silicate). Precipitated synthetic silica is then formed by the controlled addition of an acid (e.g., a mineral acid and / or an acidifying gas such as carbon dioxide). An electrolyte (e.g., sodium sulfate) may be present in this solution to promote the formation of precipitated silica particles derived from rice husks. The recovered precipitated silica is amorphous. Silica derived from rice husk ash is commonly referred to as RHA silica (Rice Husk Ash Silica). Bio-based silicas are available from suppliers such as Solvay, Evonik, Quechen, Wilmar International, and Wuxi.

[0039] In summary, the synthesis of a precipitation silica usable within the framework of the invention can be carried out from a sodium silicate entirely obtained from bio-based raw materials, or recycled or of non-renewable origin, but also from a mixture of bio-based and / or recycled and / or non-renewable raw materials (such as commonly used sands).

[0040] Preferably, the precipitated silica, whether obtained from mineral, recycled or bio-based raw materials, has a specific surface area BET and a specific surface area CTAB both less than 450 m2 / g, preferably within a range of 30 to 400 m2 / g, in particular 60 to 300 m2 / g.

[0041] Any type of precipitated silica can be used, in particular 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.

[0042] Examples include the silicas described in applications WO03 / 016215-A1 and WO03 / 016387-A1. Among the commercial HDS silicas, the following can be used in particular: “Ultrasil ® 5000GR”, “Ultrasil ® 7000GR” from Evonik, “Zeosil ® 1085GR”, “Zeosil® 1115 MP”, “Zeosil® 1165MP”, “Zeosil® Premium 200MP”, “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, “K160”, “K185”, “K195” silicas from Wilmar International.

[0043] The physical state in which the reinforcing inorganic filler is presented is irrelevant, whether it is in the form of powder, microbeads, granules, or balls or any other suitable densified form. Of course, the term "reinforcing inorganic filler" also refers to mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers.

[0044] The reinforcing inorganic filler used, in particular if it is silica, preferably has a BET surface area of ​​between 45 and 400 m2 / g, more preferably between 60 and 300 m2 / g.

[0045] Preferably, the reinforcing filler of the rubber composition according to the invention comprises from 10 to 150 parts per annum, preferably from 50 to 130 parts per annum, of silica. In a preferred arrangement, the reinforcing filler comprises predominantly silica and preferably is made of silica.

[0046] To couple the reinforcing inorganic filler to the elastomer, optionally a coupling agent (or bonding agent) at least bifunctional can be used in a known manner to ensure a sufficient connection, of a chemical and / or physical nature, between the inorganic filler (surface of its particles) and the elastomer, in particular organosilanes, or bifunctional polyorganosiloxanes.

[0047] In particular, polysulfide silanes, called "symmetric" or "asymmetric" depending on their particular structure, can be used, as described for example in applications WO03 / 002648 (or US 2005 / 016651) and WO03 / 002649 (or US 2005 / 016650).

[0048] Examples of polysulfurized silanes include, in particular, the polysulfides (notably disulfides, trisulfides or tetrasulfides) of bis-(alkoxyl(Cl-C4)-alkyl(Cl-C4)silyl-alkyl(Cl-C4)), such as, for example, the polysulfides of bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl). Among these compounds, the tetrasulfide of bis(3-triethoxysilylpropyl), abbreviated TESPT, with the formula [(C2H5O)3Si(CH2)3S2]2, or the disulfide of bis-(triethoxysilylpropyl), abbreviated TESPD, with the formula [(C2H5O)3Si(CH2)3S]2, are used in particular. We will also cite as preferential examples the polysulfides (in particular disulfides, trisulfides or tetrasulfides) of bis-(monoalkoxyl(Cl-C4)-dialkyl(Cl-C4)silylpropyl), more particularly the tetrasulfide of bis-monoethoxydimethylsilylpropyl as described in US patent application 2004 / 132880.

[0049] As a coupling agent other than polysulfurized alkoxysilane, mention shall be made in particular of bifunctional POS (polyorganosiloxanes) or polysulfurized hydroxysilanes as described in patent applications WO 02 / 30939 and WO 02 / 31041, or silanes or POS bearing azo-dicarbonyl functional groups, as described for example in patent applications WO 2006 / 125532, WO 2006 / 125533, WO 2006 / 125534.

[0050] In rubber compositions according to the invention, the content of coupling agent is preferably in a range of 5 to 18% by weight relative to the amount of silica, preferably in a range of 8 to 12% by weight relative to the amount of silica.

[0051] A person skilled in the art will understand that, as an equivalent charge to the reinforcing inorganic charge described in this paragraph, a reinforcing charge of another nature, in particular organic, could be used, provided that this reinforcing charge is covered with an inorganic layer such as silica, or has functional sites on its surface, in particular hydroxyl sites, allowing the bond to be established between the charge and the elastomer in the presence or not of a coating or coupling agent.

[0052] In a preferred arrangement in which the rubber composition according to the invention comprises an isoprene elastomer, the rubber composition preferably comprises at least 25 parts per cubic inch of carbon black. Crosslinking system

[0053] The rubber composition according to the invention preferably comprises a sulfur-based crosslinking system including a metal oxide, a stearic acid derivative, and a vulcanization accelerator. This is referred to as a vulcanization system. The sulfur may be supplied in any form, in particular as molecular sulfur or as a sulfur-donating agent.

[0054] Sulfur is used preferably at a rate of 1 to 20 pc, preferably from 1 to 10 pc.

[0055] Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used as an accelerator, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Examples of such accelerators include the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-ter-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-ter-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds.

[0056] The crosslinking system may also optionally include a vulcanization retarder. Hydrocarbon wax

[0057] The rubber composition according to the invention comprises a hydrocarbon wax based on a cut obtained from the pyrolysis of a charge comprising mainly polyethylene, said cut comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms.

[0058] By hydrocarbon wax, we mean a wax which is made up only of carbon and hydrogen atoms.

[0059] Such properties enable the rubber composition according to the invention to achieve the desired performance.

[0060] Said hydrocarbon wax is based on a fraction obtained from the pyrolysis of a filler consisting mainly of polyethylene. The method of obtaining the wax gives it rubber composition properties that differ from similar waxes in terms of structure.

[0061] Preferably, the charge comprising mainly polyethylene which is pyrolyzed comprises at least 60% by weight of polyethylene, preferably at least 70% by weight of polyethylene, preferably at least 80% by weight of polyethylene, preferably at least 90% by weight of polyethylene and most preferably is made of polyethylene.

[0062] Preferably, the hydrocarbon wax has alkene functions at the end of the chain.

[0063] The hydrocarbon wax used in the invention can be obtained by a process comprising at least:

[0064] a) A pyrolysis step of the charge comprising mainly polyethylene allowing to obtain at least one pyrolysis effluent;

[0065] b) A step of separating the pyrolysis effluent into an intermediate effluent comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms, at least one effluent of light compounds and at least one effluent of heavy compounds.

[0066] Such a process may, for example, correspond to the process described in document CA 3 032 242. Pyrolysis step a)

[0067] The charge, consisting mainly of polyethylene, feeds a pyrolysis stage preferably operated at a temperature between 300 and 600°C, allowing the production of a pyrolysis oil.

[0068] Pyrolysis is defined as the thermal decomposition of compounds in an inert or oxygen-poor atmosphere, that is to say, one containing less than 5% in volume, preferably less than 3% by volume and preferably less than 2% by volume of oxygen, preferably in an inert atmosphere.

[0069] The pyrolysis step is preferably carried out at a pressure of less than 1 bar under an inert atmosphere, for example under a nitrogen atmosphere.

[0070] The pyrolysis step can be carried out in a pyrolysis reactor, and can be operated continuously, semi-continuously or in batch mode. Such reactors are well known to those skilled in the art.

[0071] Preferably, the pyrolysis step of the process for obtaining hydrocarbon wax comprises microwave-assisted pyrolysis. The thermal power required for pyrolysis is, in this case, supplied by microwave radiation.

[0072] Preferably in this configuration, the power delivered by the microwave device of microwave thermally assisted pyrolysis is between 0.1 and 10 kW / kg load, preferably between 0.1 and 5 kW / kg load, preferably between 0.5 and 4 kW / kg load and preferably between 1 and 4 kW / kg load.

[0073] When the pyrolysis step is operated continuously or semi-continuously, it can be implemented in several zones. Step b) of pyrolysis oil separation

[0074] The pyrolysis oil is then treated in a separation step so as to obtain a wax comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms.

[0075] Any separation method known to those skilled in the art can be implemented. Since pyrolysis oil is a hydrocarbon effluent, such a separation is well known to those skilled in the art and presents no difficulty.

[0076] For example, pyrolysis oil is treated in a first separation step, called topping, to separate the lightest fraction comprising compounds having at most 16 carbon atoms. Such a separation step can be carried out by any means known to those skilled in the art, for example by evaporation in a distillation column, in an evaporator such as a scraped-film evaporator, or by any other means.

[0077] The effluent comprising the heavier compounds is treated in a second separation stage so as to separate the fraction comprising the compounds having 16 to 28 carbon atoms.

[0078] Finally, the residual fraction is treated in a final separation step, called stemming, so as to separate the fraction comprising the compounds having more than 36 carbon atoms. Other additives

[0079] The rubber composition according to the invention may preferably include additives commonly used in elastomeric compositions particularly intended for the manufacture of vehicle tires, such as, for example, pigments, protective agents, such as anti-ozone waxes, anti-ozonants or chemical antioxidants, plasticizing agents other than those described above, anti-fatigue agents, reinforcing resins, or acceptors (for example, a novolac phenolic resin) or donors (for example, HMT or H3M) of methylene.

[0080] In a preferred arrangement, the rubber composition according to the invention may comprise from 20 to 100 parts of plasticizing hydrocarbon resin.

[0081] The term "resin" is reserved in this application, by definition, for a compound which is solid at room temperature (20°C), as opposed in particular to a liquid plasticizing agent such as an oil.

[0082] Hydrocarbon resins are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but potentially containing other types of atoms, and are particularly useful as plasticizing or tackifying agents in polymer matrices. They are inherently miscible (i.e., compatible) at the ratios used with the polymer compositions for which they are intended, so as to act as true diluents. They have been described, for example, in the book entitled "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 30°C, specifically between 30°C and 95°C.

[0083] Examples of such hydrocarbon resins include those selected from the group 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, and alpha-methyl- homopolymer or copolymer resins. styrene and mixtures of these resins. Among the above copolymer resins, we can mention more particularly those chosen from the group consisting of (D)CPD / vinylaromatic copolymer resins, (D)CPD / terpene copolymer resins, terpene phenol copolymer resins, (D)CPD / C5 cut copolymer resins, (D)CPD / C9 cut copolymer resins, terpene / vinylaromatic copolymer resins, terpene / phenol copolymer resins, C5 cut / vinylaromatic copolymer resins, and mixtures of these resins.

[0084] The term "terpene" here includes in a known way the alpha-pinene, beta-pinene and limonene monomers; preferably a limonene monomer is used, a compound which is known to exist in the form of three possible isomers: L-limonene (levorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or dipentene, racemic of the dextrorotatory and levorotatory enantiomers. Suitable examples of vinylaromatic monomers include styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, and any vinylaromatic monomer derived from a C9 cut (or more generally from a C8 to C1 cut).

[0085] In particular, we can mention the 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.

[0086] C5 resins are commercially available, for example, sold by Eastman under the names "Piccotac 1105" or "Impera R1507", by Exxon under the name "Escorez 1102", by Kolon under the name "Hikorez Al 100", or by Cray Valley Total under the name "Wingtack 98". C5-C9 resins are commercially available, for example, sold by Exxon under the name "OPPERA 373", by Eastman under the name "Piccotac 8090", and by Cray Valley Total under the name "Wingtack STS". Preparation of rubber compositions

[0087] The rubber composition according to the invention is manufactured in suitable mixers, using preparation phases well known to those skilled in the art:

[0088] - a thermomechanical working or mixing phase, which can be carried out in a the only thermomechanical step during which, in a mixer, one introduces A suitable internal mixer, such as a standard Banbury-type mixer, is used to mix all the necessary components, including the elastomeric matrix, hydrocarbon resin, fillers, and any other additives. The filler can be incorporated into the elastomer in one or more stages by thermomechanical mixing. If the filler, particularly carbon black or silica, 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, and any other elastomers or fillers present in the composition that are not in masterbatch form, as well as any other additives, are incorporated.

[0089] Thermomechanical mixing is 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.

[0090] - a second phase of mechanical work is then carried out in a mixer external such as a roller mixer, after cooling the mixture obtained during the first phase to a lower temperature, typically below 120°C, for example between 40°C and 100°C.

[0091] The crosslinking system will be added during the second phase.

[0092] The final composition thus obtained can then be calendered, for example in the form of a sheet or plate, in particular for characterization in the laboratory, or extruded in the form of a semi-finished (or profile) of rubber.

[0093] The composition can be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), can be a semi-finished product that can be used in a tire.

[0094] The cooking can be carried out, in a manner known to those skilled in the art, at a temperature generally between 130°C and 200°C, under pressure, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the cooking temperature, the crosslinking system adopted, the crosslinking kinetics of the composition considered or the size of the tire. Vehicle bandage

[0095] The present invention also relates to vehicle bandages comprising a rubber composition based on at least one elastomer and a hydrocarbon wax according to the invention.

[0096] The vehicle tire can be pneumatic or non-pneumatic. By non-pneumatic, it is understood that this tire is capable of supporting the vehicle's load by means other than a pressurized inflation gas, for example by means of guy wires.

[0097] The vehicle tire according to the invention shall be chosen from, without limitation, tires intended to equip a two-wheeled vehicle, a passenger vehicle, a "heavy load" vehicle (i.e., a subway, a bus, off-road vehicles, heavy load transport vehicles such as trucks, tractors or trailers), an aircraft, construction equipment, a heavy agricultural vehicle or a handling vehicle.

[0098] A vehicle tire typically comprises a crown, two sides, and two ridges, each side connecting each ridge to the crown. Each ridge includes at least one circumferential reinforcing element, generally in the form of a rod.

[0099] The vehicle tire also includes a carcass reinforcement anchored in each bead and extending into each sidewall and the top. The carcass reinforcement includes a carcass layer comprising a portion wrapped around each circumferential reinforcement element.

[0100] The crown comprises a tread intended to come into contact with the ground during the rolling of the vehicle tire, as well as a crown reinforcement arranged radially between the tread and the carcass reinforcement. The crown reinforcement comprises a working reinforcement including at least one working layer. The crown reinforcement also comprises a reinforcing reinforcement arranged radially outside the working reinforcement, the reinforcing reinforcement being axially delimited by two axial edges and comprising at least one reinforcing wire element wound circumferentially helically so as to extend axially from one axial edge to the other axial edge of the reinforcing reinforcement along a principal direction of the wire element(s) of each reinforcing wire element.

[0101] Thus, the invention also relates to a vehicle tire having a sidewall, as described above, said sidewall comprising at least one rubber composition according to the invention.

[0102] The invention also relates to a vehicle tire whose tread comprises a rubber composition according to the invention. Measurement methods: Mooney plasticity

[0103] The Mooney plasticity test is performed according to the following principle and in accordance with ASTM D-1646. The raw composition is molded in a cylindrical chamber heated to a given temperature, usually 100°C. After one minute of preheating, an L-type rotor rotates within the specimen at 2 revolutions per minute, and the torque required to maintain this movement is measured after 4 minutes of rotation. Mooney plasticity (ML 1+4) is expressed in "Mooney unit" (MU, with 1 MU = 0.83 Newton.meter).

[0104] Traction tests

[0105] The tests were carried out in accordance with French standard NF T 46-002 of September 1988. All tensile measurements were carried out under normal temperature (23±2°C) and humidity (50+5% relative humidity) conditions, according to French standard NF T 40-101 (December 1979).

[0106]

[0107] The nominal secant modulus calculated by referring to the initial section of the specimen (or apparent stress, in MPa) at 100% and 300% elongation, respectively noted MAio o and MA3 oo, was measured in the second elongation (i.e. after accommodation) on samples baked for 25 minutes at 150°C.

[0108]

[0109] The results are expressed on a base of 100, with the value 100 assigned to the control. A result greater than 100 indicates that the composition of the example considered exhibits greater rigidity than the control.

[0110]

[0111] The tensile stresses (in MPa) and the strains at break (in %) were also measured at 23°C + 2°C, according to standard NF T 46-002, on raw samples or on samples baked for 25 minutes at 150°C or 90 minutes at 160°C. The energy at break is equal to the product of the elongation at break and the tensile stress.

[0112] Dynamic properties

[0113] The dynamic properties G* and tan(d) are measured on a viscoanalyzer (Metravib VA4000), according to ASTM D 5992-96. The response of a cross-linked composition sample (cylindrical specimen 4 mm thick and 400 mm² cross-section) is recorded, subjected to sinusoidal loading in alternating simple shear, at a frequency of 10 Hz, under defined temperature conditions, for example at 0°C, 23°C and 60°C according to ASTM D 1349-99. A strain amplitude sweep is performed from 0.1 to 100% (forward cycle), then from 100% to 1% (reverse cycle). The results used are the complex dynamic shear modulus G* and the shear loss modulus G”, as well as the value of tan(d). For the return cycle, the value of G* and the value of G” at 10% strain are indicated, along with the maximum observed value of tan(d). The value of G’’ measured at 23°C is an indicator of rolling resistance. A low value denotes a lower contribution of the composition to rolling resistance. Efflorescence test#:

[0114] The efflorescence test measures the propensity of an ozone-blocking wax to migrate excessively after a long period of storage. The test procedure is broken down as follows.

[0115] After cutting, 2.5 mm thick test tube-shaped plates are baked at 70°C for 12 hours in air. They are then baked at 40°C in air for 4, 6, and 8 weeks. After removal from the oven and a 15-minute return to room temperature, a mechanical stimulus consisting of scraping the test tube with a metal blade is applied to reveal the efflorescence of the wax.

[0116] The extent of the efflorescence phenomenon (white discoloration on the surface) is then assessed using a subjective scale that is representative of the final appearance of the samples. The values ​​on this subjective scale range from 0 to 3 and correspond to the following aspects for the samples: 0-No efflorescence / 1-Slight efflorescence / 2-Moderate efflorescence / 3-Total efflorescence. The lower the value, the better the efflorescence performance. Fatigue measurement

[0117] Fatigue resistance, expressed in number of cycles or in relative unit (ur), is measured in a known manner on 12 specimens subjected to repeated low-frequency tensile stresses up to an elongation of 75%, at 23°C, using a Monsanto apparatus (type "MFTR") until the specimen breaks, according to ASTM D4482-85 and ISO 6943 standards.

[0118] The result is expressed in relative units (ur). A value greater than that of the control, arbitrarily set at 100, indicates an improved result, i.e., better fatigue resistance of the rubber samples. Resistance to ozone attack

[0119] The ozone resistance of the materials is measured according to the following method: after baking and then drying at 77 °C in air for 14 days, 10 specimens are placed on a trapezoid at different elongations ranging from 10% to 100% in 10% elongation increments along the major axis of the specimen (specimen length). The specimens referred to as B15 are made from an MFTR plate (called Monsanto), the two ridges at the ends of which serve to hold the specimen in place. The B15 specimens have the following dimensions: 78.5 mm * 15 mm * 1.5 mm. After 3 and 8 days of exposure to a temperature of 38 °C and an ozone concentration of 50 ppm (parts per hundred million), each surface is visually analyzed using photography. Binocular microscope. Each surface is scored out of 20 based on its color: all black = score of 20 (intact specimen), fracture of the specimen = score of 0, and between these two extremes, the number and depth of cracks give the specimen shades of gray (measurement assisted by computer processing). This scoring out of 20 takes into account all specimens, regardless of the deformation. The higher the score, the better the ozone performance. Cooking time

[0120] The times t0 and t90 are determined from a cooking rheogram at 150 or 160°C according to DIN 53529. The value alpha is determined according to the following calculation: alpha(t) = (C(t) - Cmin) / (Cmax - Cmin) where C is a pair from the rheogram and t is a time. t0 is the time such that alpha(t0) = 0. t90 is the time such that alpha = 0.90. Examples Example 1 - Synthesis of hydrocarbon wax

[0121] A pyrolysis step as described in document CA 3 032 242 is fed with a charge comprising 100% by weight of polyethylene (high-density polyethylene, or HDPE) in the form of granules with a largest dimension between 3 and 5 mm. The microwave pyrolysis step is carried out under an inert nitrogen atmosphere with a power of approximately 600 W. Pyrolysis is stopped when the temperature of the pyrolysis outlet gases falls below 50°C.

[0122] The pyrolysis effluent undergoes a first fractionation step in a scraped-film evaporator to predominantly separate compounds containing fewer than 16 carbon atoms. The raffinate, comprising the heavier compounds, is separated in a second scraped-film evaporator to predominantly separate compounds containing fewer than 28 carbon atoms. The raffinate from this second separation step is treated in a third separation step in a scraped-film evaporator to separate compounds predominantly containing more than 36 carbon atoms. The extract collected after this final separation, constituting the hydrocarbon wax, comprises at most 5% by weight of compounds containing at most 24 carbon atoms and at most 5% by weight of compounds containing at least 38 carbon atoms.

[0123] The characteristics of the hydrocarbon wax obtained are presented in Table 1. Example 2 - Rubber compositions

[0124] The rubber compositions detailed in Tables 2 and 3 are manufactured by introducing all the constituents onto an internal mixer, with the exception of the vulcanizing system. The vulcanizing agents (sulfur and accelerator) are introduced onto an external mixer at low temperature (the (rollers constituting the mixer being at 30 °C). The compositions are baked under press at 160°C for compositions A-0, Al and A-2 and 150°C for compositions A-3 and A-4.

[0125] To make these compositions, different waxes are used, the characteristics of which are indicated in the table below.

[0126] [Tables 1] Linear hydrocarbon rate (%) Proportion < C 30 (%) Proportion between C 30 and C 38 (%) Proportion > C 38 (%) Wax C32(l) 64.8 27.6 63.8 8.6 Wax C36 (2) 55.4 13.4 56.2 30.4 Wax from the example 1 20.1 34.2 61.5 4.3

[0127] (1) Repsol C32 Redezon 500 anti-ozone wax

[0128] (2) Repsol C36 Redezon 7236 ozone-blocking wax

[0129] Tables 2 and 3 show different rubber compositions putting implemented the waxes presented in Table 1 as well as the measurement results obtained.

[0130] The results are expressed on a base of 100, with the value 100 assigned to the control (A-0 for Table 2 and A-3 for Table 3). A result greater than 100 indicates a value higher than the control value.

[0131] [Tables2] Composition A-0 A-1 A-2 Natural Rubber (3) 50 50 50 Polybutadiene (4) 50 50 50 Carbon Black (5) 55 55 55 Oil (6) 15 15 15 Antioxidant A (7) 3 3 3 Antioxidant B (8) 1.5 1.5 1.5 Stearic Acid 1 1 1 Zinc Oxide 2 2 2 C32 Wax (1) 1.5 0 0 C36 Wax (2) 0 7.5 0 Example Wax 1 0 0 1.5 Sulfur 2 2 2 Accelerator (9) 1 1 1 Results (base 100) t0 at 160°C 100 100 100 t90 at 160°C 100 100 100 Mooney ML 1+4 100 97 99 Modulus 100% 100 100 100 Modulus 300% 100 93 100 G* 10% return to 23°C 100 92 92 G” 10% return to 23°C 100 94 94 MFTR at 23°C 100 116 126 Efflorescence 6 weeks (score between 0 and 3) 1 1 1 Efflorescence 8 weeks (score between 0 and 3) 1 1 1

[0132] Table 2 References

[0133] (3) Natural rubber

[0134] (4) Neodymium Polybutadiene “Synteca 44” from Syntheos

[0135] (5) Cabot Company ASTM N660 Carbon Black

[0136] (6) TDAE oil “Vivatec500” from British Petroleum (BP)

[0137] (7) Antioxidant “Vulkanox 4020” from the company Lanxess

[0138] (8) Antioxidant “Naugard Q” from the company Chemtura

[0139] (9) Tert-Butyl-Benzothiazyl-Sulfenamide (TBBS) “DelacS” of the company Chemtura.

[0140] It is observed that the composition according to the invention has properties equivalent to compositions comprising commercial waxes, both in its behavior during cooking and in its properties after cooking, while exhibiting better resistance to fatigue.

[0141] [Tables3] Composition A-3 A-4 SBR(1 0 ) 100 100 Carbon black ( 11 ) 4 4 Silica ( 12 ) 110 110 Resin ( 13 ) 64 64 Oil (14) 11 11 Silane (15) 11 11 DPG (16) 2.4 2.4 Antioxidant A (17) 3.8 3.8 Antioxidant B (8) 1.6 1.6 Stearic acid 3 3 Zinc oxide 0.9 0.9 C32 Wax (1) 2.6 0 Example wax 1 0 2.6 Vulcanization system 3.2 3.2 Results (base 100) t90 at 160°C 100 107 Mooney ML 1+4 100 96 Modulus 100% 23°C 100 88 Modulus 300% 23°C 100 94 G* 10% return at 23°C 100 91 Tan D max return 23 °C 100 100 Tensile strength 23 °C 100 103 Deformation at break 23 °C 100 103 Efflorescence 6 weeks (score between 0 and 3) 1 1 Efflorescence 8 weeks (score between 0 and 3) 1 1 Ozone resistance after 14 days of aging at 77°C in air Reading 3 days (score out of 20) 16 16 Reading 8 days (score out of 20) 12 12

[0142] Table 3 References

[0143] (10) SBR styrene and butadiene copolymer with a Tg of -65°C

[0144] (11) Cabot Company ASTM N234 Carbon Black

[0145] (12) Silica “Zeosill 165MP” from the Solvay company

[0146] (13) “OPPERA PR 383” resin from Exxon Mobil

[0147] (14) High oleic sunflower oil from CARGILL

[0148] (15) Silane “SI69” of the company EVONIK

[0149] (16) Diphenyl guanidine “DPG” from AKROCHEM

[0150] (17) Antioxidant “Santaflex 6PPD” from FLEXSYS

[0151] It is observed that the composition according to the invention has properties equivalent to compositions comprising commercial waxes, both in its behavior during firing and in its properties after firing, and has good breaking properties.

Claims

Demands

1. Rubber composition based on at least one elastomeric matrix, a reinforcing filler, a crosslinking system and a hydrocarbon wax based on a cut obtained from the pyrolysis of a filler comprising mainly polyethylene, said cut comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms.

2. Composition according to the preceding claim wherein the pyrolysis charge comprises at least 60% by weight of polyethylene, preferably at least 70% by weight of polyethylene, preferably at least 80% by weight of polyethylene, preferably at least 90% by weight of polyethylene and most preferably is made of polyethylene.

3. Composition according to any one of the preceding claims wherein the hydrocarbon wax has alkene functions at the end of the chain.

4. Composition according to any one of the preceding claims wherein the hydrocarbon wax is obtained by a process comprising at least: a. A pyrolysis step of the feedstock comprising predominantly polyethylene enabling the production of at least one pyrolysis effluent; b. A separation step of the pyrolysis effluent into an intermediate effluent comprising at most 5% by weight of compounds comprising at most 24 carbon atoms and at most 5% by weight of compounds comprising at least 38 carbon atoms, at least one effluent of light compounds and at least one effluent of heavy compounds.

5. Composition according to any one of the preceding claims wherein the pyrolysis step of the process for obtaining hydrocarbon wax includes microwave thermally assisted pyrolysis.

6. Composition according to any one of the preceding claims wherein the reinforcing filler comprises from 10 to 150 parts, preferably from 50 to 130 parts, of silica.

7. Composition according to any one of the preceding claims comprising from 20 to 100 pieces of plasticizing hydrocarbon resin.

8. Composition according to any one of the preceding claims comprising at least 50 pc of a butadiene elastomer.

9. Composition according to the preceding claim wherein the butadiene elastomer is a butadiene copolymer having a glass transition temperature Tg below -20°C, preferably between -20°C and -110°C.

10. Composition according to the preceding claim comprising at least 70 parts, preferably at least 90 parts, of at least one butadiene copolymer, preferably a butadiene-styrene copolymer.

11. Composition according to any one of the preceding claims further comprising at least 20 pieces of an isoprene elastomer selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof.

12. Composition according to the preceding claim comprising at least 25 pieces of carbon black.

13. Vehicle bandage comprising a rubber composition according to any one of the preceding claims.

14. Vehicle tire comprising a tread of a rubber composition according to any one of claims 1 to 10.

15. Vehicle bandage having an outer sidewall, said outer sidewall comprising at least one composition according to claim 11 or claim 12.