Elastomeric composition comprising a phenolic compound and a monosaccharide family compound

Abstract

The invention relates to a rubber composition based on at least one elastomer, at least one phenolic compound, the aromatic ring of which is substituted by at least one hydrocarbon substituent, and at least one monosaccharide compound, the molar mass of which is at most equal to 1000 g / mol.

Description

Technical Field

[0001] The present invention relates to elastomer-based rubber compositions, composite materials comprising such compositions, finished or semi-finished products comprising such compositions or such composite materials, and pneumatic tires comprising such compositions or such composite materials. Background Technology

[0002] The reinforcing plies of a pneumatic tire typically consist of a rubber compound and reinforcing cords, which are usually metallic and coated with brass. Because these plies are subjected to high stresses during the rolling process of a pneumatic tire, it is understandable that the adhesion between the rubber compound and the reinforcing elements is a critical performance characteristic.

[0003] Adhesive properties typically utilize specific formulations of rubber compounds, which in particular require high levels of sulfur and zinc oxide, small amounts of stearic acid, the presence of cobalt salts, and the use of accelerators that delay action. However, these high-sulfur vulcanization systems pose a major limitation in the manufacture of semi-finished products, especially in order to avoid premature crosslinking.

[0004] Therefore, it is advantageous for pneumatic tire manufacturers to formulate rubber compositions that eliminate the need for sulfur present in the composition while allowing for good adhesion to reinforcing cables.

[0005] WO 2017 / 081387 and WO 2017 / 081388 disclose a rubber composition and composite material based on a polymer matrix comprising a functionalized diene polymer. This functionalized diene polymer has at least one aromatic group substituted by at least two ortho-hydroxyl functional groups. Crosslinking of the rubber composition is carried out using a vulcanization system or a system based on one or more peroxide compounds. Good adhesion properties between the rubber composition and metals are obtained, but the use of grafted polymers is required. Therefore, it is advantageous to obtain a simpler solution to improve adhesion properties.

[0006] Application JP 2011252107 describes a rubber composition exhibiting good adhesion to metals, comprising a diene elastomer and a cobalt salt. Gallic acid or gallic acid hydrate promotes the dissolution of the cobalt salt. The composition is crosslinked using a sulfur-based system. While exhibiting good adhesive properties, this composition utilizes both sulfur and a cobalt salt.

[0007] Application WO 2019 / 122586 teaches a rubber composition comprising a specific phenolic compound, wherein the crosslinking system does not contain sulfur, and the rubber composition has excellent adhesion to metal reinforcements.

[0008] Documents WO2020 / 058613 and WO2020 / 058614 describe rubber compositions containing high molar masses of polyphenolic compounds, which exhibit excellent adhesion to metal reinforcements. However, this type of compound is expensive, and its availability for use in pneumatic tires is limited. Summary of the Invention

[0009] Continuing their research, the applicant discovered a rubber composition that enables the resolution of the aforementioned problems and exhibits excellent performance in adhesion to metal supports.

[0010] Detailed description of the invention

[0011] The present invention relates to at least one of the embodiments presented in the following points:

[0012] 1. A rubber composition based on at least one diene elastomer, reinforcing filler, crosslinking system, and at least one phenolic compound, said crosslinking system being based on at least one or more free radical polymerization initiators, said phenolic compound having a molar mass of at most 1000 g / mol and comprising a phenolic group substituted by at least one hydrocarbon group, said hydrocarbon group being interrupted and / or substituted by an oxygen atom and optionally interrupted and / or substituted by one or more heteroatoms, said rubber composition further comprising at least one monosaccharide compound selected from aldoses and ketoses.

[0013] 2. The rubber composition according to the preceding embodiment, wherein the phenolic group of the phenolic compound is substituted with at least two hydrocarbon groups, the hydrocarbon groups are optionally interrupted and / or substituted with one or more heteroatoms, at least one hydrocarbon group is interrupted and / or substituted with an oxygen atom, the two hydrocarbon groups are capable of forming a ring together with the carbon atom of the aromatic ring of the phenolic group to which they are attached, the ring being optionally interrupted and / or substituted with one or more heteroatoms.

[0014] 3. The rubber composition according to any of the foregoing embodiments, wherein the phenolic compound corresponds to general formula (I),

[0015]

[0016] in:

[0017] -G1 represents a hydroxyl group, a carboxyl group, an alkoxy group, or a hydrogen atom;

[0018] -G2 represents a hydroxyl, carboxyl, or carbonyl group, or a hydrogen atom;

[0019] -G3 represents hydroxyl, carboxyl, hydrogen carbonyl, carboxyalkyl, carboxyalkylene, alkoxy, amino, aminoalkyl, amide, vinyl, or hydrogen atom;

[0020] At least one of the substituents G1 to G3 contains an oxygen atom, the molar mass of the phenolic compound is at most 1000 g / mol, and at least one monosaccharide compound is selected from aldoses and ketoses.

[0021] 4. The rubber composition according to any of the foregoing embodiments, wherein the phenolic compound is substituted with at least two hydroxyl groups.

[0022] 5. The rubber composition according to any of the foregoing embodiments, wherein the phenolic compound is substituted with at least one carboxyl group.

[0023] 6. The rubber composition according to any of the foregoing embodiments, wherein the phenolic compound is substituted at least at the para position of the hydroxyl group.

[0024] 7. The rubber composition according to embodiment 6, wherein the phenolic compound is substituted with a carboxyl group at the para position of the hydroxyl group.

[0025] 8. The rubber composition according to any one of embodiments 3 to 7, wherein G1, G2 and G3 are independently selected from hydroxyl, carboxyl and hydrogen atoms, preferably independently selected from hydroxyl and carboxyl groups.

[0026] 9. The composition according to any of the foregoing embodiments, wherein the molar mass of the phenolic compound is less than 800 g / mol, preferably less than 600 g / mol, very preferably less than 400 g / mol, and extremely preferably less than 220 g / mol.

[0027] 10. The rubber composition according to embodiment 1, wherein the phenolic compound is selected from 1,4-dihydroxy-2-naphthoic acid, curcumin, resveratrol, daidzein, genistein, apigenin, umbelliferone, L-tyrosine, guaiacol, 2-hydroxy-4-methoxybenzaldehyde, isovanillin, salicylic acid, acetaminophen, 4-hydroxybenzaldehyde, caffeic acid, 5-aminosalicylic acid, 3,4-dihydroxybenzaldehyde, 2,5-dihydroxyterephthalic acid, vanillin, 2,5-dihydroxybenzoic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid, and mixtures thereof.

[0028] 11. The rubber composition according to embodiment 1, wherein the phenolic compound is selected from acetaminophen, 4-hydroxybenzaldehyde, caffeic acid, 5-aminosalicylic acid, 3,4-dihydroxybenzaldehyde, 2,5-dihydroxyterephthalic acid, vanillin, 2,5-dihydroxybenzoic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid, and mixtures thereof.

[0029] 12. The rubber composition according to embodiment 1, wherein the phenolic compound is selected from caffeic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid and mixtures thereof, preferably selected from caffeic acid, gallic acid and protocatechuic acid.

[0030] 13. The composition according to any of the foregoing embodiments, wherein the content of the phenolic compound is between 0.1 phr and 25 phr.

[0031] 14. The composition according to any of the foregoing embodiments, wherein the monosaccharide compound is selected from trisaccharides, tetrasaccharides, pentoses and hexoses, preferably selected from pentoses and hexoses.

[0032] 15. The composition according to the preceding embodiment, wherein the monosaccharide compound is selected from fructose, allulose, sorbitol, tagatose, allose, arbutin, glucose, mannose, gulose, idole, galactose and taloose, preferably selected from fructose, glucose, mannose and galactose, and most preferably selected from fructose and glucose.

[0033] 16. The composition according to any of the foregoing embodiments, wherein the content of the monosaccharide compound is between 0.1 phr and 15 phr, preferably between 0.1 phr and 10 phr.

[0034] 17. The composition according to any of the foregoing embodiments, wherein the composition is free of cobalt salt or contains less than 1 phr of cobalt salt.

[0035] 18. The rubber composition according to any of the foregoing embodiments, wherein the reinforcing filler comprises carbon black, silica, or a mixture of carbon black and silica.

[0036] 19. The rubber composition according to any of the foregoing embodiments, wherein the content of the reinforcing filler is between 20 phr and 200 phr.

[0037] 20. The rubber composition according to any of the foregoing embodiments, wherein the peroxide compound in the crosslinking system based on one or more peroxide compounds accounts for 0.01 phr to 10 phr.

[0038] 21. The composition according to any of the foregoing embodiments, wherein the composition is free of molecular sulfur or contains less than 1 phr of molecular sulfur.

[0039] 22. A composite material, which is at least based on a component having a metallic surface and the composition according to any one of embodiments 1 to 21.

[0040] 23. The composite material according to the preceding embodiment, wherein the component has a length of at least 1 millimeter.

[0041] 24. The composite material according to any one of embodiments 22 and 23, wherein the component is a thread or cable.

[0042] 25. The composite material according to any one of embodiments 22 to 24, wherein the metal surface of the component is made of a material different from the rest of the component.

[0043] 26. The composite material according to any one of embodiments 22 to 25, wherein the metal surface of the component comprises a metal selected from the group consisting of iron, copper, zinc, tin, aluminum, cobalt, nickel, and alloys comprising at least one of these metals.

[0044] 27. The composite material according to any one of embodiments 22 to 26, wherein the metal on the metal surface is selected from iron, copper, tin, zinc or an alloy containing at least one of these metals, preferably selected from brass, steel, zinc and bronze.

[0045] 28. A finished or semi-finished product comprising the composition according to any one of embodiments 1 to 21 or the composite material according to any one of embodiments 22 to 27.

[0046] 29. A pneumatic tire comprising a composition according to any one of embodiments 1 to 21 or a composite material according to any one of embodiments 22 to 27.

[0047] 30. A pneumatic tire comprising an inner layer, said inner layer comprising a composition according to any one of embodiments 1 to 21 or a composite material according to any one of embodiments 22 to 27.

[0048] definition

[0049] The phrase "composition-based" should be understood to mean that the composition comprises a mixture of various components used and / or in-situ reaction products, some of which are capable of and / or intended to react with each other at least partially at various stages of the manufacture of the composition and in the modification of the initially obtained composition. Therefore, compositions used in this invention can differ in a non-crosslinked state and in a crosslinked state.

[0050] For the purposes of this invention, the expression "parts by weight / 100 parts by weight elastomer" (or phr) should be understood as meaning parts by mass / 100 parts by mass elastomer.

[0051] In this document, all percentages (%) indicated are weight percentages (%) unless otherwise expressly stated.

[0052] Furthermore, any numerical interval expressed as "between a and b" represents a range of values ​​from greater than a to less than b (i.e., excluding the extreme values ​​a and b), while any numerical interval expressed as "a to b" means a range of values ​​from a to b (i.e., including the strict extreme values ​​a and b). In this document, when a numerical interval is expressed as "a to b," it is also preferable to represent the interval represented by the expression "between a and b."

[0053] The carbon-containing compounds mentioned in this specification can be of fossil or bio-based origin. In the latter case, they can be obtained, in whole or in part, from biomass or from renewable raw materials derived from biomass. Polymers, plasticizers, fillers, etc., are particularly relevant.

[0054] elastomer

[0055] The compositions according to the invention comprise at least one diene elastomer, preferably a highly unsaturated diene elastomer.

[0056] To reiterate, the terms "dien elastomer" or "rubber" (these two terms are known to be synonymous and interchangeable) should be understood to mean an elastomer that is at least partially (i.e., a homopolymer or copolymer) derived from a dien monomer (a monomer with two conjugated or non-conjugated carbon-carbon double bonds). In this application, dien elastomers are defined as non-thermoplastic.

[0057] Since diene elastomers have negative Tg (i.e., values ​​less than 0°C) in most cases, they can be classified into two categories in a known manner: those diene elastomers that are referred to as "substantially unsaturated" and those that are referred to as "substantially saturated".

[0058] "Substantially unsaturated" diene elastomers are understood to be diene elastomers that are at least partially derived from conjugated diene monomers and have a diene source (conjugated diene) unit content greater than 15% (mol%). Within the category of "substantially unsaturated" diene elastomers, "highly unsaturated" diene elastomers specifically refer to diene elastomers with a diene source (conjugated diene) unit content greater than 50%.

[0059] Conversely, the term "substantially saturated" diene elastomers refer to elastomers with low or very low (always less than 15% (mol%)) diene source unit content, such as butyl rubber, or EPDM-type copolymers of dienes with α-olefins.

[0060] In light of these definitions, regardless of which category is described above, the term "diene elastomer" that can be used in compositions according to the invention more specifically refers to:

[0061] (a) Any homopolymer containing 4 to 18 carbon atoms of conjugated or non-conjugated diene monomers;

[0062] (b) Any copolymer of a conjugated or non-conjugated diene containing 4 to 18 carbon atoms with at least one other monomer.

[0063] Other monomers can be ethylene, olefins, or conjugated or non-conjugated dienes. Ethylene-butadiene rubber (EBR) can be mentioned as an example of such a copolymer.

[0064] More specifically, the statement "dien elastomer that can be used in the compositions according to the invention" is intended to mean:

[0065] (a1) Any homopolymer obtained by polymerization of a conjugated diene monomer containing 4 to 12 carbon atoms;

[0066] (b1) Any copolymer obtained by copolymerization of one or more conjugated dienes with each other or with one or more vinyl aromatic compounds containing 8 to 20 carbon atoms;

[0067] (c1) Terpolymers obtained by copolymerization of ethylene and α-olefins containing 3 to 6 carbon atoms with non-conjugated diene monomers containing 6 to 12 carbon atoms, such as elastomers obtained by copolymerization of ethylene and propylene with non-conjugated diene monomers of the above type (especially, for example, 1,4-hexadiene, ethylidene norbornene or dicyclopentadiene).

[0068] (d1) Copolymers of isobutylene and isoprene (diene butyl rubber), and halogenated forms of such copolymers, particularly chlorinated or brominated forms.

[0069] 1,3-Butadiene, 2-methyl-1,3-butadiene, 2,3-di(C1-C5 alkyl)-1,3-butadiene (e.g., 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, or 2-methyl-3-isopropyl-1,3-butadiene), aryl-1,3-butadiene, 1,3-pentadiene, and 2,4-hexadiene are particularly suitable as conjugated dienes. Examples of suitable vinyl aromatic compounds include: styrene, (o-, m-, or p-)methylstyrene, commercially available mixtures of "vinyltoluene," p-(tert-butyl)styrene, methoxystyrene, chlorostyrene, vinyltrimethylbenzene, divinylbenzene, and vinylnaphthalene.

[0070] The copolymer may contain between 99% and 20% diene units and between 1% and 80% vinyl aromatic units.

[0071] Preferably, at least one type of highly unsaturated diene elastomer is used, particularly diene elastomers selected from natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers. Such copolymers are more preferably selected from butadiene / styrene copolymers (SBR), isoprene / butadiene copolymers (BIR), isoprene / styrene copolymers (SIR), isoprene / butadiene / styrene copolymers (SBIR), and mixtures of such copolymers.

[0072] The following substances are preferably suitable: polybutadiene, especially those with a 1,2-unit content between 4% and 80% or a cis-1,4-unit content greater than 80%; polyisoprene; butadiene / styrene copolymers, especially those with a styrene content between 5% and 50% by weight and more particularly between 20% and 40%, a 1,2-bond content in the butadiene moiety between 4% and 65%, and a trans-1,4-bond content between 20% and 80%; butadiene / isoprene copolymers, especially those with an isoprene content between 5% and 90% by weight and a glass transition temperature of -40°C to -80°C; or isoprene / styrene copolymers, especially those with a styrene content between 5% and 50% by weight and a glass transition temperature of -40°C to -80°C. g Those between -25°C and -50°C.

[0073] In the case of butadiene / styrene / isoprene copolymers, those with a styrene content between 5% and 50% by weight, more particularly between 10% and 40%, an isoprene content between 15% and 60% by weight, more particularly between 20% and 50%, a butadiene content between 5% and 50% by weight, more particularly between 20% and 40%, a butadiene moiety containing 4% to 85% 1,2-units, a butadiene moiety containing 6% to 80% trans-1,4-units, an isoprene moiety containing 5% to 70% 1,2-units plus 3,4-units, and an isoprene moiety containing 10% to 50% trans-1,4-units, and more generally any butadiene / styrene / isoprene copolymer with a Tg between -20°C and 70°C are particularly suitable.

[0074] Elastomers can have any microstructure, which depends on the polymerization conditions used, particularly the presence or absence of modifiers and / or atactic agents, and the amount of modifiers and / or atactic agents used. The elastomers can be prepared, for example, in a dispersion or in solution; they can be coupled and / or star-branched or functionalized by coupling agents and / or star-branching or functionalizing agents.

[0075] For coupling to carbon black, examples that may be mentioned include functional groups containing C-Sn bonds or amination functional groups (e.g., benzophenone); for coupling to reinforcing inorganic fillers (e.g., silica), examples that may be mentioned include silanol functional groups or polysiloxane functional groups with silanol ends (as described in FR 2 740 778 or US 6 013 718), alkoxysilane groups (as described in, for example, FR 2 765 882 or US 5 977 238), carboxyl groups (as described in, for example, WO 01 / 92402 or US 6 815 473, WO 2004 / 096865 or US 2006 / 0089445), or polyether groups (as described in, for example, EP 1 127 909 or US 6 503 973). Other examples of functionalized elastomers may include epoxide-type elastomers (e.g., SBR, BR, NR, or IR).

[0076] The T of the above polymer g It is measured in a known manner by, for example, DSC (Differential Scanning Calorimetry), and unless otherwise expressly stated in this application, according to standard ASTM D3418 (1999).

[0077] Crosslinking system

[0078] Crosslinking typically improves the elastic properties of rubber compositions. Crosslinking systems are designed to react, in particular, with elastomers to induce crosslinking in the rubber composition.

[0079] Preferably, the rubber composition according to the invention is free of molecular sulfur, or contains less than 1 phr, preferably less than 0.5 phr, more preferably less than 0.2 phr of molecular sulfur. Very preferably, the composition does not contain any molecular sulfur as a crosslinking agent.

[0080] The crosslinking system is based on at least one free radical polymerization initiator.

[0081] Free radical polymerization initiators are the source of free radicals required for the polymerization of the rubber compositions according to the present invention. These initiators are well known to those skilled in the art and are described, in particular, in documents such as WO 2002 / 22688 A1 and FR 2899 808 A1, as well as in Denisov et al.'s (Handbook of free radical initiators, John Wiley & Sons, 2003).

[0082] Preferably, according to the invention, at least one free radical polymerization initiator is selected from peroxides, azo compounds, redox (oxidation / reduction) systems and mixtures thereof, and more preferably from peroxides, azo compounds and mixtures thereof. More preferably, at least one free radical polymerization initiator is a peroxide or a mixture of multiple peroxides. It can be any peroxide known to those skilled in the art, such as described, for example, in document WO 2017103387. Among peroxides known to those skilled in the art, organic peroxides are preferred in the case of this invention. The peroxide compound preferably accounts for 0.01 phr to 10 phr.

[0083] The term "organic peroxide" is understood to refer to organic compounds containing -OO- groups (two oxygen atoms connected by a single covalent bond), that is, carbon-containing compounds.

[0084] During cross-linking, organic peroxides decompose at their unstable O-O bonds, generating free radicals. These free radicals enable the formation of cross-linking bonds.

[0085] According to one embodiment, the organic peroxide is selected from dialkyl peroxides, monoperoxycarbonates, diacyl peroxides, peroxyketals, and peroxide esters.

[0086] Preferably, the dialkyl peroxide is selected from dicumyl peroxide, di(tert-butyl) peroxide, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-pentylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, 2,5-dimethyl-2,5-di(tert-pentylperoxy)-3-hexyne, α,α'-di[(tert-butylperoxy)isopropyl]benzene, α,α'-di[(tert-pentylperoxy)isopropyl]benzene, di(tert-pentyl) peroxide, 1,3,5-tris[(tert-butylperoxy)isopropyl]benzene, 1,3-dimethyl-3-(tert-butylperoxy)butanol, and 1,3-dimethyl-3-(tert-pentylperoxy)butanol.

[0087] A mixture of dicumyl peroxide and 1,3- and 1,4-isopropylcumyl peroxide (e.g., from Arkema under the trade name) Selling the DC60 is also advantageous.

[0088] Certain monoperoxycarbonates may also be used, such as OO-tert-butyl O-(2-ethylhexyl) monoperoxycarbonate, OO-tert-butyl O-isopropyl monoperoxycarbonate and OO-tert-pentyl O-(2-ethylhexyl) monoperoxycarbonate.

[0089] Among diacyl peroxides, benzoyl peroxide is the preferred peroxide.

[0090] In the peroxy ketal, the preferred peroxide is selected from 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl 4,4-di(tert-butylperoxy)valerate, ethyl 3,3-di(tert-butylperoxy)butyrate, 2,2-di(tert-amylperoxy)propane, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (or cyclic trimer of methyl ethyl ketone peroxide), 3,3,5,7,7-pentamethyl-1,2,4-trioxacycloheptane, n-butyl 4,4-bis(tert-amylperoxy)valerate, ethyl 3,3-di(tert-amylperoxy)butyrate, 1,1-di(tert-butylperoxy)cyclohexane, 1,1-di(tert-amylperoxy)cyclohexane, and mixtures thereof.

[0091] Preferably, the peroxide ester is selected from tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, and tert-butyl peroxy-3,5,5-trimethylhexanoate.

[0092] Particularly preferred, the organic peroxide is selected from dicumyl peroxide, aryl or diaryl peroxide, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, di(tert-butyl) peroxide, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, 4,4'-di(tert-butylperoxy)valerate, O,O-(tert-butyl)O-(2-ethylhexyl)monoperoxycarbonate, tert-butylperoxyisopropylene carbonate, tert-butyl peroxybenzoate, peroxide-3, 5,5-Trimethylhexanoate tert-butyl ester, 1,3(4)-bis(tert-butylperoxyisopropyl)benzene and mixtures thereof; more preferably selected from dicumyl peroxide, 4,4'-di(tert-butylperoxy)valerate n-butyl ester, O,O-(tert-butyl)O-(2-ethylhexyl) monoperoxycarbonate, tert-butylperoxyisopropylene carbonate, tert-butyl peroxybenzoate, tert-3,5,5-trimethylhexanoate tert-butyl ester, 1,3(4)-bis(tert-butylperoxyisopropyl)benzene and mixtures thereof.

[0093] In a preferred configuration, the rubber composition according to the invention does not contain any crosslinking system other than the crosslinking system described above based on one or more peroxide compounds. The composition preferably does not contain any vulcanization accelerators or activators known to those skilled in the art, or contains less than 1 phr, preferably less than 0.5 phr, more preferably less than 0.2 phr of vulcanization accelerators or activators.

[0094] Reinforced packing

[0095] Any type of reinforcing filler known to be able to enhance rubber compositions that can be used to manufacture pneumatic tires can be used, such as organic fillers like carbon black, reinforcing inorganic fillers like silica, or blends of both, especially blends of carbon black and silica.

[0096] All carbon blacks, especially HAF, ISAF, or SAF type carbon blacks commonly used in pneumatic tires (“tire-grade” carbon black), are suitable as carbon blacks. Within “tire-grade” carbon blacks, more specifically, will be referenced to reinforcing carbon blacks of the 100, 200, or 300 series (ASTM grades), such as N115, N134, N234, N326, N330, N339, N347, or N375, or higher series carbon blacks depending on the target application (e.g., N660, N683, or N772). Carbon blacks may, for example, be incorporated into isoprene elastomers in masterbatch form (see, for example, applications WO 97 / 36724 or WO 99 / 16600).

[0097] As examples of organic fillers other than carbon black, the functionalized polyvinyl organic fillers described, for example, in applications WO-A-2006 / 069792, WO-A-2006 / 069793, WO-A-2008 / 003434 and WO-A-2008 / 003435 can be mentioned.

[0098] In this application, the term "reinforced inorganic filler" should be understood by definition to mean any inorganic or mineral filler (regardless of its color and origin (natural or synthetic)) that, in contrast to carbon black, is also referred to as "white filler," "transparent filler," or even "non-black filler," capable on its own of reinforcing rubber compositions intended for use in the manufacture of pneumatic tires without any means other than intermediate coupling agents; in other words, capable of replacing conventional tire-grade carbon black in terms of reinforcement. Such fillers are typically characterized in a known manner by the presence of hydroxyl (-OH) groups on their surface.

[0099] It is not important what physical state the reinforcing inorganic filler is provided in, whether it is in the form of powder, microspheres, granules, beads, or any other suitable densification form. Of course, "reinforcing inorganic filler" is also understood to mean a mixture of different reinforcing inorganic fillers, especially a mixture of highly dispersible siliceous and / or aluminous fillers as described below.

[0100] Silica-based mineral fillers (especially silica (SiO2)) or alumina-based mineral fillers (especially alumina (Al2O3)) are particularly suitable as reinforcing inorganic fillers. The silica used can be any reinforcing silica known to those skilled in the art, especially those with a BET surface area and CTAB specific surface area both less than 450 m². 2 / g, preferably 30 to 400m 2 / g of any precipitated silica or pyrolytic silica. As highly dispersible precipitated silica (“HDS”), reference will be made to, for example, Ultrasil 7000 and Ultrasil 7005 silica from Degussa, Zeosil 1165MP, 1135MP and 1115MP silica from Rhodia, Hi-Sil EZ150G silica from PPG, Zeopol 8715, 8745 and 8755 silica from Huber, or silica with a high specific surface area as described in application WO 03 / 016837.

[0101] The reinforcing inorganic filler used (especially if it is silica) preferably has a content of 45 μm. 2 / g to 400m 2 Between / g, more preferably between 60m 2 / g to 300m 2BET surface area between / g.

[0102] Preferably, the total content of reinforcing filler (carbon black and / or reinforcing inorganic filler such as silica) is between 20 phr and 200 phr, more preferably between 30 phr and 150 phr, with the optimal value varying in a known manner depending on the specific target application: for example, the level of reinforcement desired for bicycle tires is certainly lower than the level of reinforcement required for tires capable of sustained high-speed operation (e.g., motorcycle tires, tires for passenger vehicles, or tires for multi-purpose vehicles such as heavy vehicles).

[0103] According to a preferred embodiment of the invention, an organic filler (particularly carbon black) and optionally silica reinforcing filler are used, comprising between 30 phr and 150 phr, more preferably between 50 phr and 120 phr; when silica is present, it is preferably used at a content of less than 20 phr, more preferably less than 10 phr (e.g., between 0.1 phr and 10 phr).

[0104] Alternatively, according to another preferred embodiment of the invention, an inorganic filler (particularly silica) comprising between 30 phr and 150 phr, more preferably between 50 phr and 120 phr, and optionally carbon black, is used as a reinforcing filler; when carbon black is present, it is preferably used in a content of less than 20 phr, more preferably less than 10 phr (e.g., between 0.1 phr and 10 phr).

[0105] In order to couple an enhanced inorganic filler to an elastomer, a coupling agent (or binder) that is at least bifunctional, particularly a bifunctional organosilane or polyorganosiloxane, may be optionally used in a known manner to provide a satisfactory chemical and / or physical connection between the inorganic filler (its particle surface) and the elastomer.

[0106] Silane polysulfides may be used in particular, which are referred to as “symmetric” or “asymmetric” according to their specific structures, as described, for example, in applications WO 03 / 002648 (or US 2005 / 016651) and WO 03 / 002649 (or US 2005 / 016650).

[0107] As examples of silane polysulfides, more particular reference will be made to bis((C1-C4)alkoxy(C1-C4)alkylsilyl(C1-C4)alkyl) polysulfides (especially disulfides, trisulfides, or tetrasulfides), such as, for example, bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl) polysulfides. Among these compounds, the bis(3-triethoxysilylpropyl) tetrasulfide of the formula [(C2H5O)3Si(CH2)3S2]2, abbreviated as TESPT, is used in particular, or the bis(triethoxysilylpropyl) disulfide of the formula [(C2H5O)3Si(CH2)3S]2, abbreviated as TESPD. As a preferred example, reference will also be made to bis(mono(C1-C4)alkoxybis(C1-C4)alkylsilylpropyl) polysulfides (especially disulfides, trisulfides or tetrasulfides), and more particularly bis(monoethoxydimethylsilylpropyl) tetrasulfides, as described in patent application US 2004 / 132880.

[0108] As coupling agents other than alkoxysilane polysulfides, bifunctional POS (polyorganosiloxanes) will be specifically mentioned, or hydroxysilane polysulfides as described in patent applications WO 02 / 30939 and WO 02 / 31041, or silanes or POS with azodicarbonyl functional groups as described in, for example, patent applications WO 2006 / 125532, WO 2006 / 125533 and WO 2006 / 125534.

[0109] In the rubber composition according to the invention, the content of the coupling agent is preferably between 4 phr and 12 phr, more preferably between 4 phr and 8 phr. In another configuration, the rubber composition according to the invention does not contain any coupling agent.

[0110] Those skilled in the art will understand that reinforcing fillers of another property (especially organic properties) can be used as fillers equivalent to the reinforcing inorganic fillers described in this section, provided that the reinforcing filler is covered with an inorganic layer such as silica, or contains functional sites (especially hydroxyl sites) on its surface, such that a bond can be established between the filler and the elastomer in the presence or absence of a covering agent or coupling agent.

[0111] Phenolic compounds

[0112] The compositions according to the invention comprise at least one phenolic compound having a molar mass of at most 1000 g / mol, the phenolic compound comprising a phenolic group substituted by at least one hydrocarbon group, the hydrocarbon group being interrupted and / or substituted by an oxygen atom and optionally interrupted and / or substituted by one or more heteroatoms.

[0113] The term "heteroatom" is intended to refer to an atom with at least one valence that is different from hydrogen and carbon atoms, preferably selected from nitrogen and oxygen atoms.

[0114] Preferably, the phenolic group of the phenolic compound is substituted with at least two hydrocarbon groups, which are optionally interrupted and / or substituted by one or more heteroatoms, and at least one hydrocarbon group is interrupted and / or substituted by an oxygen atom. The two hydrocarbon groups are capable of forming a ring together with the carbon atom of the aromatic ring of the phenolic group to which they are attached, and the ring is optionally interrupted and / or substituted by one or more heteroatoms.

[0115] Preferably, the phenolic compound corresponds to general formula (I).

[0116]

[0117] in:

[0118] -G1 represents a hydroxyl group, a carboxyl group, an alkoxy group, or a hydrogen atom;

[0119] -G2 represents a hydroxyl group, a carboxyl group, or a hydrogen atom;

[0120] -G3 represents hydroxyl, carboxyl, hydrogen carbonyl, carboxyalkyl, carboxyalkylene, alkoxy, amino, aminoalkyl, amide, vinyl, or hydrogen atom;

[0121] At least one of the substituents G1 to G3 contains an oxygen atom, and the molar mass of the phenolic compound is at most equal to 1000 g / mol.

[0122] The term "carboxyl" or "carboxylic acid functional group" refers to a group having the formula -COOH, in which a carbon atom is connected to an oxygen atom via a double bond and to a hydroxyl group -OH via a single bond.

[0123] The term "carboxyalkyl" refers to a compound with the formula –C n H 2n –COOH groups, wherein n is an integer in an advantageous range as follows: 1 to 15, preferably 1 to 10, very preferably 1 to 5, and most preferably 1 to 3.

[0124] The term "alkoxy" refers to an alkoxy group having the formula –OC n H 2n+1 The group, where n represents an integer in the range of 1 to 10, very preferably 1 to 5, and more preferably 1 to 3.

[0125] The term "hydrocarbonyl" refers to a group having the formula -CHO, in which a carbon atom is connected to an oxygen atom via a double bond and to a hydrogen atom via a single bond.

[0126] The term "amino" refers to a group having the formula -NH2.

[0127] The term "aminoalkyl" refers to a compound with the formula –Cn H 2n –NH2 group, wherein n is an integer in an advantageous range as follows: 1 to 15, preferably 1 to 10, very preferably 1 to 5, preferably 1 to 3.

[0128] Preferably, the phenolic compound is substituted with at least two hydroxyl groups. Preferably, G1, G2, and G3 independently represent a hydroxyl or carboxyl group or a hydrogen atom, and more preferably, independently represent a hydroxyl or carboxyl group.

[0129] Advantageously, the phenolic compound is substituted with at least one carboxyl group.

[0130] Advantageously, the phenolic compound is substituted at least at the para-position of the hydroxyl group. The term "substituted at the para-position" means, as those skilled in the art know, that the aromatic ring of the phenolic compound is substituted at position 4, and the hydroxyl group is considered to be at position 1, with positions 1 to 6 corresponding to the carbon atoms constituting the aromatic ring. Surprisingly, the applicant has found that the adhesive properties of the compositions according to the invention are particularly improved when the phenolic compound is substituted at least at the para-position of the hydroxyl group. The adhesive properties are particularly advantageous when the phenolic compound is substituted with a carboxyl group at the para-position of the hydroxyl group.

[0131] Regardless of the preferred embodiment, the molar mass of the phenolic compound is at most 1000 g / mol, preferably less than 800 g / mol, preferably less than 600 g / mol, very preferably less than 400 g / mol, very preferably less than 220 g / mol, very preferably less than 200 g / mol, or even 180 g / mol.

[0132] Among the phenolic compounds used in this invention, 1,4-dihydroxy-2-naphthoic acid, curcumin, resveratrol, daidzein, genistein, apigenin, umbelliferone, L-tyrosine, guaiacol, 2-hydroxy-4-methoxybenzaldehyde, isovanillin, salicylic acid, acetaminophen, 4-hydroxybenzaldehyde, caffeic acid, 5-aminosalicylic acid, 3,4-dihydroxybenzaldehyde, 2,5-dihydroxyterephthalic acid, vanillin, 2,5-dihydroxybenzoic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid, and mixtures thereof may be mentioned.

[0133] Among these compounds, particularly preferred compounds include acetaminophen, 4-hydroxybenzaldehyde, caffeic acid, 5-aminosalicylic acid, 3,4-dihydroxybenzaldehyde, 2,5-dihydroxyterephthalic acid, vanillin, 2,5-dihydroxybenzoic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid, and mixtures thereof. Preferably, the compound is selected from caffeic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid, and mixtures thereof, and more preferably from caffeic acid, gallic acid, and protocatechuic acid.

[0134] Very preferably, the phenolic compound is gallic acid.

[0135] The rubber compositions according to the invention advantageously contain 0.1 phr to 25 phr, preferably 2 phr to 15 phr, of a phenolic compound. Below 0.1 phr, the phenolic compound has no significant effect on the adhesive properties of the rubber compositions according to the invention. Above 25 phr, no further significant improvement has been observed.

[0136] Monosaccharide compounds

[0137] The rubber composition according to the invention comprises at least one monosaccharide compound selected from aldoses and ketoses.

[0138] Monosaccharides are carbohydrate monomers. Aldose is a monosaccharide in which the carbonyl functional group is an aldehyde. Ketoose is a monosaccharide in which the carbonyl functional group is a ketone.

[0139] It has been found that in rubber compositions crosslinked using a peroxide-based crosslinking system, the combination of specific phenolic compounds with monosaccharide compounds enables excellent adhesion to metal parts.

[0140] Preferably, the monosaccharide compound is selected from trisaccharides, tetrasaccharides, pentoses, and hexoses, and more preferably from pentoses and hexoses. Preferably, the monosaccharide compound is selected from fructose, allulose, sorbitol, tagatose, allose, adroose, glucose, mannose, gulose, idole, galactose, and taloose, and more preferably from fructose, glucose, mannose, and galactose, and very preferably from fructose and glucose.

[0141] Preferably, the content of monosaccharide compounds is between 0.1 phr and 15 phr, more preferably between 0.1 phr and 10 phr.

[0142] Various additives

[0143] The rubber composition according to the invention may also include all or part of the common additives known to those skilled in the art that are typically used in rubber compositions for pneumatic tires (particularly inner layer compositions, as defined herein), such as, for example, plasticizers (plasticizing oils and / or plasticizing resins), reinforcing or non-reinforcing fillers other than those described above, pigments, protective agents (e.g., anti-ozone waxes, chemical anti-ozone agents or antioxidants), anti-fatigue agents or reinforcing resins (as described, for example, in application WO 02 / 10269).

[0144] In addition to coupling agents, these compositions may also contain coupling activators, agents for coating inorganic fillers, or more generally processing aids that improve the processability of the composition in its unprocessed state in a known manner by improving the dispersion of the filler in the rubber matrix and reducing the viscosity of the composition. These agents are, for example, hydrolyzable silanes such as alkylalkoxysilanes (e.g., octyltriethoxysilane or Octeosilane), polyols, polyethers, primary, secondary, or tertiary amines, or hydroxylated or hydrolyzable polyorganosiloxanes.

[0145] Surprisingly, the compositions according to the invention achieve very good adhesion to reinforced cables without the use of cobalt salts. Therefore, the compositions according to the invention preferably do not contain cobalt salts known to those skilled in the art (whose known function is to improve adhesion), or contain less than 1 phr, preferably less than 0.5 phr, more preferably less than 0.2 phr, and very preferably less than 0.1 phr of cobalt salt.

[0146] Preparation of rubber composition

[0147] The rubber composition according to the invention is prepared in a suitable mixer using preparation stages known to those skilled in the art:

[0148] - The thermomechanical processing or kneading stage, which can be carried out in a single thermomechanical step, involves introducing all necessary components, particularly the elastomer matrix, phenolic compounds, fillers, and optional other additives, into a suitable mixer such as a standard closed mixer (e.g., a 'Banbury' type). The filler can be introduced into the elastomer in one or multiple portions during thermomechanical kneading. Where the filler (particularly carbon black) has already been wholly or partially introduced into the elastomer in masterbatch form (as described, for example, in applications WO 97 / 36724 or WO 99 / 16600), the masterbatch is kneaded directly, and where appropriate, other elastomers or fillers not in masterbatch form present in the composition, along with optional other additives, are introduced.

[0149] Thermomechanical kneading is carried out at high temperatures, up to 110°C to 200°C, preferably between 130°C and 185°C, for a period of time typically between 2 and 10 minutes.

[0150] -The mixture obtained in the first stage is then cooled to a lower temperature, typically less than 120°C, such as between 40°C and 100°C, and then a second stage of machining can be carried out in an open mixer such as a two-roll mill.

[0151] As is known to those skilled in the art, an optional crosslinking system will be added during the first or second stage. Typically, a peroxide-based crosslinking system will be added during the second stage.

[0152] The resulting final composition is then calendered, for example, into sheets or plates for laboratory characterization, or extruded into rubber semi-finished products (or molded elements).

[0153] The composition can be in an unprocessed state (before crosslinking) or in a cured state (after crosslinking), or it can be a semi-finished product that can be used in pneumatic tires.

[0154] Curing can be carried out in a manner known to those skilled in the art at a temperature typically between 130°C and 200°C for a sufficient time under pressure, said time being, for example, between 5 minutes and 90 minutes, depending in particular on the curing temperature, the crosslinking system employed, the crosslinking kinetics of the composition under consideration, or the size of the pneumatic tire.

[0155] Composite materials

[0156] The present invention also relates to a composite material, which is at least based on a component having a metal surface and a rubber composition according to the invention.

[0157] The statement that a composite material is “at least based on a component and a composition according to the invention” should be understood to mean that the composite material comprises the component and the composition, which is capable of reacting with the surface of the component during various stages of the preparation of the composite material, particularly during the crosslinking of the composition or during the preparation of the composite material prior to the crosslinking of the composition.

[0158] The component may be entirely or partially made of metal.

[0159] The metal surface of the component constitutes at least a portion (advantageously all) of the surface of the component and is intended to contact the composition according to the invention.

[0160] The composition according to the invention covers at least a portion of the component, advantageously covering the entire component.

[0161] The component is advantageously partially or entirely made of metal, with the metal portion comprising at least a metal surface. Preferably, the component is made entirely of metal.

[0162] According to a first variant of the invention, the metallic surface of the component is made of a material different from the rest of the component. In other words, the component is made of a material that is at least partially (advantageously entirely) covered by a metallic layer forming the metallic surface. The material at least partially (advantageously entirely) covering the metallic surface is metallic or non-metallic in nature, preferably metallic.

[0163] According to a second variant of the invention, the component is made of the same material, in which case the component is made of the same metal as the metal surface.

[0164] According to one embodiment of the invention, the metal surface comprises a metal selected from iron, copper, zinc, tin, aluminum, cobalt, nickel, and alloys comprising at least one of these metals. The alloy may be, for example, a binary or ternary alloy, such as steel, bronze, and brass. Preferably, the metal on the metal surface is iron, copper, tin, zinc, or an alloy comprising at least one of these metals. More preferably, the metal on the metal surface is steel, brass (Cu-Zn alloy), zinc, or bronze (Cu-Sn alloy), even more preferably brass or zinc, and very preferably brass.

[0165] In this application, the statement "the metal on the metal surface is the metal shown below" is equivalent to saying that the metal surface is made of the metal shown below. For example, the statement "the metal on the metal surface is brass" means that the metal surface is made of brass. Since some metals oxidize when in contact with surrounding air, metals other than stainless steel can be partially oxidized.

[0166] When the metal surface is made of steel, the steel is preferably carbon steel or stainless steel. When the steel is carbon steel, its carbon content is preferably between 0.01% and 1.2%, or between 0.05% and 1.2%, or between 0.2% and 1.2%, particularly between 0.4% and 1.1%. When the steel is stainless steel, it preferably contains at least 11% chromium and at least 50% iron.

[0167] The component can have any shape. Preferably, the component is in the form of a thread or cable.

[0168] According to a specific embodiment of the invention, the component has a length of at least 1 millimeter. Length refers to the longest dimension of the component. As a component having a length of at least 1 millimeter, examples of reinforcing elements used in pneumatic tires of vehicles, such as filamentous elements (monofilaments or cables) and non-filamentous elements, can be mentioned.

[0169] According to a particularly preferred embodiment of the invention, the composite material is a reinforcing structure in which the components constitute reinforcing elements and the composition according to the invention coats the reinforcing elements.

[0170] According to a particularly preferred embodiment, the composite material is a reinforcing product comprising reinforcing elements and calendered rubber inlaid with the reinforcing elements, each reinforcing element consisting of a component defined prior to any embodiment of the invention, and the calendered rubber comprising a rubber composition according to the invention. According to this embodiment, the reinforcing elements are generally arranged side-by-side along a main direction. For the envisioned application in pneumatic tires, the composite material can thus constitute the reinforcement of the pneumatic tire.

[0171] The composite material according to the invention can be in an unprocessed state (before the rubber composition crosslinks) or a cured state (after the rubber composition crosslinks). The composite material is cured after the component is brought into contact with the rubber composition according to the invention.

[0172] This composite material can be prepared by a method including the following steps:

[0173] - Prepare two layers having the composition according to the invention,

[0174] - By placing the component between the two layers, the component is sandwiched between the two layers.

[0175] - Curing of composite materials under appropriate conditions.

[0176] Alternatively, composite materials can be made by placing a component on a portion of a layer and then folding the layer itself to cover the component, thereby clamping the component over the entire length of the layer or a portion of the layer length.

[0177] The layer can be obtained by calendering. During the curing process of the composite material, the rubber composition is cross-linked.

[0178] When a composite material is intended to be used as a reinforcement in a pneumatic tire, the curing of the composite material is typically carried out during the curing of the outer tire of the pneumatic tire.

[0179] Finished or semi-finished products

[0180] The subject matter of this invention also includes a finished or semi-finished product comprising a composition or composite material according to the invention. The term "finished product" refers to an article that can be used, for example, as a conveyor belt. The term "semi-finished product" refers to an article intended to be incorporated into a finished product, such as, for example, a reinforcing plywood layer for a pneumatic tire.

[0181] pneumatic tires

[0182] Another subject of the invention is a pneumatic tire having the essential characteristics of comprising a composition or composite material according to the invention. The pneumatic tire can be in an unprocessed state (before the rubber composition crosslinks) or a cured state (after the rubber composition crosslinks). Typically, during the manufacture of a pneumatic tire, the composition or composite material is placed in the structure of the pneumatic tire in an unprocessed state (i.e., before the rubber composition crosslinks) prior to the step of curing the pneumatic tire.

[0183] This invention particularly relates to pneumatic tires intended for use on vehicles such as passenger vehicles, SUVs (sports utility vehicles), two-wheeled vehicles (especially motorcycles), aircraft, or industrial vehicles selected from trucks, heavy-duty vehicles (i.e., subways, buses, heavy road transport vehicles (trucks, tractors, trailers) or off-road vehicles (e.g., heavy agricultural vehicles or engineering vehicles)).

[0184] Three zones can be defined within an inflatable tire:

[0185] • The radially outer region in contact with ambient air, which is essentially composed of the tread and outer sidewall of the pneumatic tire. The outer sidewall is an elastomeric layer located outside the carcass reinforcement relative to the inner cavity of the pneumatic tire between the crown and the bead, thereby completely or partially covering the area of ​​the carcass reinforcement extending from the crown to the bead.

[0186] • The radially inner region in contact with the inflating gas, which typically consists of a gas-tight layer (sometimes referred to as the inner gas-tight layer or liner) that is airtight to the inflating gas.

[0187] • The inner region of a pneumatic tire, that is, the region between the outer region and the inner region. This region includes layers or ply layers referred to herein as the inner layers of the pneumatic tire. These layers are, for example, the carcass ply, the tread ply, the belt ply, or any other layer that does not come into contact with ambient air or the inflation gas of the pneumatic tire.

[0188] The compositions defined in this specification are particularly suitable for the inner layer of pneumatic tires.

[0189] Therefore, the present invention also relates to a pneumatic tire comprising an inner layer, said inner layer comprising a composition or composite material according to the present invention. According to the present invention, the inner layer may be selected from carcass ply, crown ply, bead filler, crown base, release layer, tread base layer, and combinations thereof. Preferably, the inner layer is selected from carcass ply, crown ply, bead filler, crown base, release layer, and combinations thereof. Detailed Implementation

[0190] Example

[0191] The following procedure is used to prepare different rubber compositions: The diene elastomer, followed by all other components of the mixture, is sequentially introduced into a closed mixer (final fill factor: approximately 70% by volume), with an initial container temperature of approximately 60°C. A thermomechanical process is then performed in one step until a maximum “drip” temperature of 150°C is reached. The resulting mixture is then recovered and cooled in an open mixer (all finishing machines) at 30°C, mixing all substances.

[0192] The resulting rubber compositions are shown in Table 1.

[0193] Table 1

[0194] NR(1) 100 100 100 100 100 Carbon black (2) 60 60 60 60 60 Dicumyl peroxide (3) 2 2 2 2 2 Gallic acid(3) 0 15 0 15 15 Glucose (3) 0 0 1.5 1.5 0 Fructose (3) 0 0 0 0 1.5

[0195] All compositions are given in phr format.

[0196] (1) Natural rubber

[0197] (2)N347

[0198] (3) Supplied by Sigma-Aldrich.

[0199] It should be noted that composition "T1" contains neither the specific phenolic compound nor the monosaccharide compound. Composition "T2" contains only the specific phenolic compound, while composition "T3" contains only the monosaccharide compound, in this case an aldose with 6 carbon atoms. Composition "C1" contains both the specific phenolic compound and the ketose compound, and composition "C2" contains both the specific phenolic compound and the aldose compound.

[0200] The bonding quality between the rubber composition and the component is determined by testing based on the standard ASTM D2229, in which the force required to extract individual filament segments with metallic surfaces from the crosslinked rubber composition is measured. For this purpose, the composite material is prepared in the form of a specimen comprising, on one hand, a metal reinforcement of type 2.30NF22, and on the other hand, an elastomer mixture containing the crosslinked rubber composition, the metal reinforcement being commonly used as reinforcement for components with metallic surfaces in the pneumatic tire industry.

[0201] Sample preparation

[0202] The rubber composition was used to prepare composite materials in the form of test specimens according to the following scheme:

[0203] A rubber block is prepared, consisting of two sheets, one applied to the other before curing. Both sheets are composed of the same rubber composition. During the preparation of this block, reinforcements are embedded between the two unprocessed sheets, spaced equidistantly and with their ends extending sufficiently long over either side of the sheets for subsequent tensile testing. The block, including the reinforcements, is then placed in a mold suitable for the target test conditions, determined by those skilled in the art; for example, in this case, depending on the composition, the block is cured for 25 to 90 minutes at a pressure of 5.5 tons and a temperature of 170°C.

[0204] The reinforcement consists of two 0.3 mm thick brass-coated steel wires of 2.30NF22 cable. The thickness of the brass coating ranges from 200 nm to 1 μm.

[0205] The sample thus prepared using the composition according to the invention corresponds to the composite material according to the invention.

[0206] Adhesion test

[0207] At the end of curing, the specimen, which is thus composed of cross-linked blocks and reinforcements, is placed in the fixture of a suitable tensile testing machine, so that each segment can be tested individually at a given speed and a given temperature (e.g., in this case, at 100 mm / min and ambient temperature).

[0208] The adhesion level is characterized by measuring the “peeling” force of the reinforcement that peels off each segment from the specimen.

[0209] The results are expressed as a base of 100 relative to the control sample, which contains a reinforcement having the same properties as the test sample and contains the rubber composition “T1” shown in Table 1.

[0210] A value larger than that of the control sample (arbitrarily set to 100) indicates an improvement, namely, a greater peel force than that of the control sample (whose value is arbitrarily set to 100).

[0211] Table 2

[0212] Adhesion 100 145 110 448 214

[0213] Table 2 shows the results of adhesion tests performed on the control sample and the sample according to the invention.

[0214] By comparing T2 and T1, it can be noted that the use of gallic acid alone can improve the adhesion between the material and the reinforcement.

[0215] The combination of a specific phenolic compound (gallic acid in this case) with a monosaccharide compound (glucose or fructose in the examples) can greatly improve the adhesion between the rubber composition and the reinforcement.

Claims

1. A rubber composition based on at least one diene elastomer, reinforcing filler, crosslinking system, and at least one phenolic compound, said crosslinking system being based on at least one or more free radical polymerization initiators, said phenolic compound having a molar mass of at most 1000 g / mol and comprising a phenolic group substituted with at least one hydrocarbon group, said hydrocarbon group being interrupted and / or substituted by an oxygen atom and optionally interrupted and / or substituted by one or more heteroatoms, said rubber composition further comprising at least one monosaccharide compound selected from aldoses and ketoses, wherein, The phenolic compounds are selected from caffeic acid, gallic acid, protocatechuic acid, 4-hydroxyisophthalic acid, 2,3,4-trihydroxybenzoic acid, 3-O-methylgallic acid, 4,5-dihydroxyphthalic acid, 2,4,5-trihydroxybenzoic acid and mixtures thereof.

2. The composition according to claim 1, wherein, The content of phenolic compounds ranges from 0.1 phr to 25 phr.

3. The composition according to claim 1, wherein, The monosaccharide compounds are selected from trisaccharides, tetrasaccharides, pentoses, and hexoses.

4. The composition according to claim 3, wherein, The monosaccharide compounds are selected from fructose, allulose, sorbose, tagatose, allose, azoose, glucose, mannose, gulose, idooose, galactose, and taloose.

5. The composition according to claim 1, wherein, The content of the monosaccharide compound is between 0.1 phr and 15 phr.

6. A composite material, which is at least based on a component having a metallic surface and a composition according to any one of claims 1 to 5.

7. A finished or semi-finished product comprising the composition according to any one of claims 1 to 5 or the composite material according to claim 6.

8. A pneumatic tire comprising the composition according to any one of claims 1 to 5 or the composite material according to claim 6.

Images