A reinforced product comprising at least one metal reinforcing element and a rubber composition.

Abstract

The present invention relates to a reinforced product based on at least one metallic reinforcing element embedded in a rubber composition based on at least one epoxidized diene elastomer, a reinforcing filler, and a crosslinking system comprising at least 1 phr of sulfur.

Description

Technical Field

[0001] The present invention relates to the field of reinforced rubber products, particularly reinforced rubber products for pneumatic tires or non-pneumatic tires, and to molded articles comprising such reinforced products.

Background Art

[0002] The reinforcing ply of a pneumatic tire or a reinforced rubber article usually comprises a "calendered" rubber composition and a metallic reinforcing cord. The calendered composition must exhibit very precisely good adhesion to the metallic reinforcing cord, breaking properties, and hysteresis properties, etc., which give the ply good durability and low rolling resistance throughout the life of the tire.

[0003] Thus, the adhesion between the metal cord and the surrounding rubber is an important property for the effectiveness of the reinforcing ply of a pneumatic tire or a reinforced rubber article. Coating compositions comprising a diene elastomer, particularly natural rubber, a reinforcing filler, and a vulcanization system very specific to these compositions are known in the art. This vulcanization system usually comprises a high content of sulfur and zinc oxide, a low content of stearic acid, a "slow" vulcanization accelerator, and a vulcanization retarder. In these systems, the adhesion between the rubber mixture and the metal cord is effected via the vulcanization phenomenon on the brass-coated surface of the cord. Thus, a vulcanization retarder and a "slow" vulcanization accelerator are used to enable sulfur to vulcanize the metal cord before being consumed by vulcanization.

[0004] Many studies have been carried out by manufacturers of pneumatic tires to improve one or more of the performance qualities of the calendered composition and further improve durability.

[0005] International Publication No. WO 2016 / 058943 discloses a reinforced product comprising a rubber composition coating a sheathed reinforcing thread, the composition being based on a vulcanization system comprising a diene elastomer, a reinforcing filler, and a "rapid" vulcanization accelerator according to the terms defined hereinafter, and the composition exhibiting excellent resistance to aging.

[0006] International Publication No. 2019 / 122586 describes a composition containing an adhesion promoter that is substantially free of molecular sulfur and exhibits good adhesion and rigidity performance quality, and this composition can be crosslinked by various crosslinking systems other than vulcanization.

[0007] More recently, International Publication No. 2020 / 058614 teaches a rubber composition based on a crosslinking system comprising at least one elastomer exhibiting an epoxide group, at least one reinforcing filler, a polycarboxylic acid, an imidazole, and at least one specific polyphenol compound, which exhibits excellent adhesive properties and good maintenance of properties over time.

[0008] While compositions utilizing cross-linking systems as an alternative to vulcanization are highly effective, their diverse constituent materials present relatively industrial challenges. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2016 / 058943 [Patent Document 2] International Publication No. 2019 / 122586 [Patent Document 3] International Publication No. 2020 / 058614 [Patent Document 4] U.S. Patent Publication No. 2003 / 120007 [Patent Document 5] European Patent No. 0763564 [Patent Document 6] U.S. Patent No. 6903165 [Patent Document 7] European Patent No. 1,403,287 [Patent Document 8] U.S. Patent Publication No. 2011 / 0098404 [Patent Document 9] International Application No. 97 / 36724-A2 [Patent Document 10] International Application No. 99 / 16600-A1 [Patent Document 11] International Application No. 2006 / 069792-A1 [Patent Document 12] International Application No. 2006 / 069793-A1 [Patent Document 13] International Application No. 2008 / 003434-A1 [Patent Document 14] International Application No. 2008 / 003435-A1 [Patent Document 15] International Application No. 03 / 016215-A1 [Patent Document 16] International Application No. 03 / 016387-A1 [Patent Document 17] International Application No. 02 / 10269 [Patent Document 18] French Patent No. 2 981 298 Specification [Non-patent literature]

[0010] [Non-Patent Document 1] Kautsch.Gummi Kunst., 2004, 57(3), 82 [Non-Patent Document 2] J.Appl.Polym.Sci., 1999, 73, 1733 [Non-Patent Document 3] Macromolecules, 1998, 31, 2822) [Non-Patent Document 4] "The Journal of the American Chemical Society" (Vol. 60, p. 309, February 1938) [Overview of the Initiative]

[0011] The applicant's company has continued this research and has found a reinforcing product based on at least one metal reinforcing element embedded in a rubber composition based on at least one epoxidized diene elastomer, which composition is crosslinked by vulcanization and thus is easily industrially applicable, shows excellent adhesion properties of the composition to the reinforcing element, and particularly improves the durability of the performance quality in terms of properties at break and rolling resistance.

Embodiments for Carrying Out the Invention

[0012] The present invention relates to at least one reinforcing product based on at least one metal reinforcing element embedded in a rubber composition based on at least one epoxidized diene elastomer, a reinforcing filler, and a crosslinking system containing at least 1 phr of sulfur.

[0013] Preferably, the present invention relates to a reinforcing product in which the crosslinking system contains 1 to 5 phr of sulfur, preferably 1 to 4 phr of sulfur, and preferably 1 to 2.5 phr of sulfur.

[0014] Preferably, the present invention relates to a reinforcing product in which the vulcanization system further contains a vulcanization accelerator used at a content between 0.1 and 6 phr, more preferably between 0.5 and 4 phr, and most preferably between 0.5 and 2.5 phr.

[0015] Preferably, the present invention relates to a reinforcing product in which the crosslinking system contains a vulcanization accelerator showing a vulcanization start time called "t0" of less than 3.5 minutes, preferably 3 minutes or less.

[0016] Preferably, the present invention relates to a reinforcing product in which the reinforcing filler mainly contains silica.

[0017] The applicant's company has continued this research and has found a reinforcing product based on at least one metal reinforcing element embedded in a rubber composition based on at least one epoxidized diene elastomer, which composition is crosslinked by vulcanization and thus is easily industrially applicable, shows excellent adhesion properties of the composition to the reinforcing element, and particularly improves the durability of the performance quality in terms of properties at break and rolling resistance. Preferably, the present invention relates to a reinforcing product in which the rubber composition further contains a guanidine compound, preferably diphenylguanidine. Preferably, the content of the guanidine compound is in the range of 0.5 to 3 phr, preferably 0.5 to 2.5 phr, and preferably 0.5 to 2 phr.

[0018] Preferably, the present invention relates to a reinforcing product in which the degree of epoxidation of the epoxidized diene elastomer is in the range of 5% to 40%, preferably 10% to 35%.

[0019] Preferably, the present invention relates to reinforcing products in which the epoxidized diene elastomer is selected from the group consisting of epoxidized natural rubber, epoxidized synthetic polyisoprene, epoxidized polybutadiene having a preferred content of more than 90% cis-1,4 bonds, epoxidized butadiene / styrene copolymers, and mixtures thereof, and preferably selected from the group consisting of epoxidized natural rubber and epoxidized synthetic polyisoprene.

[0020] In a particular configuration, the present invention relates to a reinforcing product according to the present invention, wherein the rubber composition is further selected from the group consisting of polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymer, isoprene copolymer and mixtures thereof, and preferably comprises a non-epoxidized diene elastomer selected from natural rubber and synthetic polyisoprene. In this particular configuration, the content of the non-epoxidized diene elastomer is preferably between 0 and 49 phr, more preferably between 0 and 40 phr, and more preferably between 5 and 25 phr.

[0021] In another specific configuration, the present invention relates to a reinforcing product in which a rubber composition comprises one or more epoxidized diene elastomers for use as a single elastomer.

[0022] Preferably, the present invention relates to a reinforced product in which the rubber composition does not contain a cobalt salt, or contains less than 2 phr, preferably less than 1 phr, preferably less than 0.5 phr, and very preferably less than 0.1 phr, of a cobalt salt.

[0023] Preferably, the present invention relates to a reinforcing product in which the rubber composition does not contain stearic acid or one of its derivatives, or contains less than 2 phr, preferably less than 1 phr, preferably less than 0.5 phr, and very preferably less than 0.1 phr.

[0024] Preferably, the present invention relates to a reinforcing product in which the rubber composition comprises a silica coupling agent, a silica coating agent, and an agent selected from mixtures thereof, wherein the content of the agent ranges from 5% to 20% by weight relative to the amount of silica, preferably from 6% to 18% by weight relative to the amount of silica. Preferably, the silica coupling agent is selected from organosilanes, and in a preferred embodiment, is selected from the group consisting of organosilane polysulfides, polyorganosiloxanes, mercaptosilanes, and blocked mercaptosilanes, and very preferably is selected from the group consisting of organosilane polysulfides. Preferably, the silica coating agent is selected from alkylalkoxysilanes, polyols, polyethers, primary, secondary, or tertiary amines, or polyorganosiloxanes, and very preferably is selected from alkylalkoxysilanes.

[0025] Preferably, the present invention relates to a reinforcing product in which the rubber composition comprises up to 4 phr of zinc oxide, preferably up to 3 phr of zinc oxide, and preferably up to 2.5 phr of zinc oxide.

[0026] Preferably, the present invention relates to a reinforcing product having a total reinforcing filler content of 10 to 200 phr, preferably 10 to 100 phr, and in a preferred embodiment, 25 to 75 phr.

[0027] Preferably, the present invention relates to a reinforced product having a metal surface made of a metal selected from the group consisting of copper, zinc, tin, aluminum, cobalt, nickel, and alloys containing at least one of these metals, more preferably a metal selected from the group consisting of copper, tin, zinc, or alloys containing at least one of these metals. Preferably, the metal of the metal surface of the metal reinforcement is brass.

[0028] The present invention also relates to finished or semi-finished products including the reinforcing product according to the present invention.

[0029] The present invention also relates to a pneumatic or non-pneumatic tire including a reinforcing product according to the present invention.

[0030] (definition) The expression "based on" should be understood to mean a product or composition comprising a mixture of various constituent materials used and / or products of in-situ reactions, some of which are capable and / or intended to react with each other at least partially during various stages of the production of the composition, and thus the product or composition may be fully or partially crosslinked or uncrosslinked.

[0031] The expression "parts by weight per 100 parts by weight (or phr) of elastomer" should be understood within the scope of the meaning of this invention to mean parts by mass per 100 parts by mass of elastomer.

[0032] In this specification, unless otherwise specified, all percentages (%) shown are weight percentages (%).

[0033] Furthermore, any range expressed as "between a and b" represents the range of values ​​greater than a and less than b (i.e., the interval excluding a and b), while any range expressed as "from a to b" means the range of values ​​from a up to b (i.e., including the strict limit values ​​a and b).

[0034] The carbon-containing compounds described herein may be of fossil origin or bio-based origin. In the latter case, they may be partially or completely derived from biomass or obtained from renewable raw materials derived from biomass. This includes, in particular, polymers, plasticizers, and fillers.

[0035] (Reinforcement products) The reinforcing product according to the present invention is based on at least one metal reinforcing element embedded in a rubber composition that is based on a crosslinking system comprising at least one epoxidized diene elastomer, a reinforcing filler, and at least 1 phr of sulfur.

[0036] (Epoxy diene elastomer) Epoxidized elastomers or rubbers (the two terms are synonymous and equivalent in the known sense) are understood to mean any type of elastomer in the sense known to those skilled in the art, whether homopolymer or block, statistical or other copolymer, having elastomeric properties, but meaning epoxide-based (or epoxide-based), i.e., containing epoxide groups. The expressions “epoxide-containing diene elastomers” or “epoxide-based diene elastomers” are used interchangeably.

[0037] Epoxylated diene elastomers are solid at ambient temperature (20°C) by known methods; solid is understood to mean any substance that, under the influence of gravity, does not ultimately exhibit the shape of the container in which it exists after 24 hours at the latest at ambient temperature (20°C).

[0038] The glass transition temperature (Tg) of the elastomers described in this text was measured by known methods using differential scanning calorimetry (DSC), for example, in accordance with ASTM standard D3418 of 1999, unless otherwise specified.

[0039] The rubber composition of the reinforcing product according to the present invention may contain just one epoxidized diene elastomer or a mixture of multiple epoxidized diene elastomers (hereafter referred to in the singular as "epoxidized diene elastomer" to represent the total amount of epoxidized diene elastomers in the composition), and it is possible to use a diene elastomer containing an epoxide group in combination with any type of non-epoxidized elastomer, such as a diene elastomer, or in fact an elastomer other than a diene elastomer.

[0040] The epoxidized diene elastomer is the main component in the rubber composition according to the present invention; that is, it is either the only elastomer or accounts for the largest mass among the elastomers in the composition.

[0041] According to a preferred embodiment of the present invention, the rubber composition comprises, as a compound, an epoxidized diene elastomer as a main component in an amount of 51 to 100 phr, preferably 60 to 100 phr, and in a preferred embodiment, 75 to 95 phr, with one or more other small numbers of non-epoxidized elastomers in an amount of 0 to 49 phr, preferably 0 to 40 phr, and in a preferred embodiment, 5 to 25 phr.

[0042] Preferably, a small number of non-epoxidized elastomers are selected from the group consisting of polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymer, isoprene copolymer, and mixtures thereof, with preference being non-epoxidized diene elastomers selected from natural rubber and synthetic polyisoprene.

[0043] According to another preferred embodiment of the present invention, the composition comprises one or more epoxidized diene elastomers relative to 100 phr of elastomer.

[0044] The degree of epoxidation (mol%) of the epoxidized diene elastomer can vary over a wide range depending on the specific embodiment of the present invention, preferably in the range of 0.1% to 80%, more preferably in the range of 0.1% to 50%, and even more preferably in the range of 0.3% to 50%. If the degree of epoxidation is less than 0.1%, the desired technical effect may be insufficient, while if it exceeds 80%, the intrinsic properties of the polymer deteriorate. For these reasons, the degree of functionalization, particularly epoxidation, is more preferably in the range of 5% to 40%, and advantageously in the range of 10% to 35%.

[0045] It should be understood that epoxidized diene elastomers refer to elastomers that are at least partially (i.e., homopolymers or copolymers) derived from diene monomers (monomers having two conjugated or unconjugated carbon-carbon double bonds), and that these polymers are functionalized, i.e., contain epoxide functional groups.

[0046] The first characteristic of epoxidized diene elastomers is that they are diene elastomers. These diene elastomers are non-thermoplastic by definition in this patent application, exhibit a negative Tg (i.e., below 0°C) in the vast majority of cases, and can be classified by known means into two categories: those called "essentially unsaturated" and those called "essentially saturated." For example, butyl rubber such as EPDM-type diene-α-olefin copolymers falls into the category of essentially saturated diene elastomers, with a low to very low content of diene-derived units, always less than 15% (mol%). In contrast, essentially unsaturated diene elastomers are understood to mean diene elastomers that are at least partially derived from conjugated diene monomers and have a content of more than 15% (mol%) of diene-derived units (conjugated dienes). Within the category of "essentially unsaturated" diene elastomers, "highly unsaturated" diene elastomers are understood to specifically refer to diene elastomers having a content of more than 50% (mol%) of diene-derived units (conjugated dienes).

[0047] It is preferable to use at least one highly unsaturated diene elastomer, particularly one selected from the group consisting of natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), butadiene copolymer, isoprene copolymer, and mixtures thereof. Such copolymers are more preferably selected from the group consisting of butadiene / styrene copolymer (SBR), isoprene / butadiene copolymer (BIR), isoprene / styrene copolymer (SIR), isoprene / butadiene / styrene copolymer (SBIR), and mixtures thereof.

[0048] A second essential characteristic of the epoxidized diene elastomer used in the requirements of the present invention is that it is functionalized by containing epoxide functional groups.

[0049] The epoxide groups present in the diene elastomer are obtained by copolymerization or modification after polymerization, and depending on the preparation method, they are either directly supported by the chain skeleton or supported by side groups, for example, by epoxidation or other modification of the diene functional groups present in the copolymerized elastomer chain.

[0050] Epoxylated diene elastomers can be obtained by known methods, for example, by epoxidation of equivalent non-epoxylated diene elastomers, such as by processes based on chlorohydrin, bromohydrin, or hydrogen peroxide, alkyl hydroperoxide, or peracid (such as peracetic acid or perpic acid); see especially Kautsch. Gummi Kunst., 2004, 57(3), 82. As a result, the epoxide groups are present in the polymer chain. In particular, epoxylated natural rubber (abbreviated as "ENR") can be mentioned, such as ENR-25 and ENR-50 (with degrees of epoxidation of 25% and 50%, respectively) sold by Guthrie Polymer. Epoxylated BR is also well known in itself and is sold by Sartomer, for example, under the name Poly Bd (e.g., Poly Bd 605E). Epoxylated SBR can be prepared by epoxidation techniques well known to those skilled in the art.

[0051] Diene elastomers having epoxidizing groups are described, for example, in U.S. Patent Publication 2003 / 120007 or European Patent No. 0763564, and U.S. Patent No. 6903165 or European Patent No. 1403287.

[0052] Preferably, epoxidized diene elastomers are selected from the group consisting of epoxidized natural rubber (NR) (abbreviated as "ENR"), epoxidized synthetic polyisoprene (IR), epoxidized polybutadiene (BR) having a cis-1,4-bond content of more than 90%, epoxidized butadiene / styrene copolymer (SBR), and mixtures of these elastomers.

[0053] Epoxylated diene elastomers can exhibit pendant-type epoxide groups. In this case, they can be obtained by post-polymerization modification (see, e.g., J.Appl.Polym.Sci., 1999, 73, 1733), or by radical copolymerization of a diene monomer with an epoxide group-containing monomer, particularly an ester of methacrylic acid containing an epoxide group, such as glycidyl methacrylate (this radical polymerization, especially in bulk, solution, or dispersion media—especially dispersion, emulsion, or suspension—is well known to those skilled in the art of polymer synthesis: see, for example, Macromolecules, 1998, 31, 2822), or by using a nitrile oxide containing an epoxide group. For example, U.S. Patent Publication No. 2011 / 0098404 describes the emulsion copolymerization of 1,3-butadiene, styrene, and glycidyl methacrylate.

[0054] Reinforcement filler The rubber composition of the reinforcing product according to the present invention comprises one or more reinforcing fillers.

[0055] Any type of "reinforcing" filler known for its ability to reinforce rubber compositions, particularly those usable in tire manufacturing, can be used, such as organic fillers like carbon black, inorganic fillers like silica, or mixtures of these two types of fillers.

[0056] All carbon blacks, particularly those conventionally used in tires or their treads, are suitable as carbon blacks. More specifically, we will refer to the 100, 200, and 300 series reinforcing carbon blacks, or the 500, 600, or 700 series blacks (ASTM D-1765-2017 grades) (e.g., N115, N134, N234, N326, N330, N339, N347, N375, N550, N683, or N772 blacks). These carbon blacks can be used in isolated form, as commercially available, or in any other form, for example, as a support for part of the rubber additive used. Carbon blacks may already be incorporated into diene elastomers, particularly isoprene elastomers, for example, in the form of a masterbatch (see, for example, International Applications 97 / 36724-A2 and 99 / 16600-A1). In addition, carbon black produced from tire recycling and black produced from the thermal decomposition of pneumatic tires are also suitable, such as Enviro CB P550 black from Scandinavian Enviro Systems' 500 series.

[0057] Examples of organic fillers other than carbon black include functionalized polyvinyl organic fillers as described in International Applications No. 2006 / 069792-A1, 2006 / 069793-A1, 2008 / 003434-A1, and 2008 / 003435-A1.

[0058] In this specification, “reinforcing inorganic filler” should be understood to mean any inorganic or mineral filler, regardless of its color and origin (natural or synthetic), also called “white” filler, “clear” filler, or “non-black” filler, in contrast to carbon black, that can alone reinforce a rubber composition intended for tire manufacture without any means other than intermediate coupling aids. In known ways, some reinforcing inorganic fillers can be characterized in particular by the presence of hydroxyl (-OH) groups on their surface.

[0059] Silicon-based, particularly silica (SiO2), or alumina-based, particularly alumina (Al2O3), mineral fillers are especially suitable as reinforcing inorganic fillers. The silica used may be any reinforcing silica known to those skilled in the art, in particular precipitated silica or fumed silica exhibiting both BET surface ratio and CTAB surface ratio values ​​in the range of less than 450 m² / g, preferably 30 to 400 m² / g, and especially 60 to 300 m² / g. Any type of precipitated silica, particularly highly dispersible precipitated silica (referred to as "HDS" or "highly dispersible silica"), can be used. These precipitated silicas, whether highly dispersible or not, are well known to those skilled in the art. For example, the silicas described in International Applications 03 / 016215-A1 and 03 / 016387-A1 can be cited. In particular, among commercially available HDS silicas, it is possible to use Evonik's Ultrasil® 5000GR and Ultrasil® 7000GR silica, or Solvay's Zeosil® 1085GR, Zeosil® 1115 MP, Zeosil® 1165 MP, Zeosil® Premium 200 MP, and Zeosil® HRS 1200 MP silica. As non-HDS silica, the following commercially available silicas can be used: Ultrasil® VN2GR and Ultrasil® VN3GR silica 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 silica from PPG, and K-160 from Wilmar.

[0060] In this disclosure, the BET ratio surface is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" (Vol. 60, p. 309, February 1938), more specifically, by a method adapted to the standard NF ISO 5794-1, Appendix E of June 2010 [Multipoint (5-point) volumetric method - Gas: Nitrogen - Degassing under vacuum: 160°C for 1 hour - Relative pressure range p / p0: 0.05~0.17].

[0061] For inorganic fillers such as silica, the CTAB surface ratio was determined according to the standard NF ISO 5794-1, Appendix G, issued in June 2010. This is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) onto the "outer surface" of the reinforcing filler.

[0062] For carbon black, the STA ratio surface is determined according to the standard ASTM D6556-2016.

[0063] The physical state in which the reinforcing inorganic filler is provided is not important, whether it is in the form of a powder, microbeads, granules, beads, or any other suitable high-density form. Of course, it is understood that the reinforcing inorganic filler also means a mixture of different reinforcing inorganic fillers, particularly a mixture of silica as described above.

[0064] Preferably, the total reinforcing filler content (reinforcing inorganic fillers such as carbon black and / or silica) is 10 to 200 phr, more preferably 10 to 100 phr, and very preferably 25 to 75 phr, with the optimal content varying depending on the specific application in question, as is known.

[0065] Preferentially, the reinforcing filler of the rubber composition contains silica as its main component. "Main component" is understood to mean that silica accounts for more than 50% of the total weight of the reinforcing filler.

[0066] When the reinforcing filler contains silica, preferably as the main component, the rubber composition of the reinforcing product according to the present invention preferentially contains additives for coupling silica, additives for covering silica, and additives selected from mixtures thereof, wherein the content of the additives ranges from 5% to 20% by weight relative to the amount of silica, preferably from 6% to 18% by weight relative to the amount of silica.

[0067] A coupling aid is understood to mean a coupling aid (or binder) that is at least bifunctional and intended to provide a chemically and / or physically satisfactory connection between an inorganic filler (on the surface of its particles) and an epoxidized diene elastomer. In particular, organosilanes or polyorganosiloxanes that are at least bifunctional are used. "Bifunctional" is understood to mean a compound having a first functional group that can interact with the inorganic filler and a second functional group that can interact with the epoxidized diene elastomer. For example, such a bifunctional compound may include a first functional group containing a silicon atom that can interact with the hydroxyl group of the inorganic filler, and a second functional group containing a sulfur atom that can interact with the diene elastomer.

[0068] Preferentially, organosilanes are selected from a group consisting of organosilane polysulfides (symmetric or asymmetric), such as bis(3-triethoxysilylpropyl)tetrasulfide (abbreviated as TESPT), sold by Evonik under the name Si69, or bis(3-triethoxysilylpropyl)disulfide (abbreviated as TESPD), sold by Evonik under the name Si75, polyorganosiloxanes, mercaptosilanes, and blocked mercaptosilanes such as S-(3-(triethoxysilyl)propyl)octanthioate, sold by Momentive under the name NXTsilane. More preferentially, organosilanes are organosilane polysulfides.

[0069] The term "coating agent" is understood to mean an auxiliary agent that does not provide bonding between the filler and the elastomer matrix in a manner known to those skilled in the art. By covalently bonding to the surface functional sites of the inorganic filler, for example, to the surface hydroxyl sites of silica if the reinforcing inorganic filler is silica, in a manner known, the coating agent improves the processability of the composition and reduces its viscosity in the uncured state.

[0070] Processing aids that can improve the ease of processing in the uncured state by improving the dispersibility of inorganic fillers in the rubber matrix and reducing the viscosity of the composition, as done by known methods, are generally considered to be coatings, and these processing aids are, for example, hydrolyzable silanes, such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (especially polyethylene glycol), primary, secondary or tertiary amines (especially trialkanolamines), or hydroxylated or hydrolyzable POS, such as α,ω-dihydroxypolyorgansiloxanes (especially α,ω-dihydroxypolydimethylsiloxanes).

[0071] (Bridge-linking system) The rubber composition of the reinforcing product according to the present invention includes a sulfur-based crosslinking system, called a vulcanizing system, which contains at least 1 phr of sulfur.

[0072] Sulfur can be provided in any form, particularly in the form of molecular sulfur or a sulfur donor.

[0073] The reinforcing product composition according to the present invention has a low sulfur content. Sulfur is used in a content in the range of 1 to 5 phr, preferably in the range of 1 to 4 phr, and very preferably in the range of 1 to 2.5 phr.

[0074] Preferably, the crosslinking system includes a “rapid” vulcanization accelerator, i.e., a vulcanization accelerator having a vulcanization start time of less than 3.5 minutes, preferably 3 minutes or less, referred to as “t0”.

[0075] The t0 value of a given accelerator must be measured in a given rubber composition at a given vulcanization temperature. To compare "slow" or "fast" accelerators according to their t0 value, a reference composition is provided, comprising NR100 phr, carbon black N326 47 phr, stearic acid 0.9 phr, ZnO 7.5 phr, sulfur 4.5 phr, and an accelerator, whose t0 should be determined by a molar content of 2.3 mmol per 100 parts by weight of elastomer (the commercial references for the components shown here are the same as those used in Example 1). The method for measuring t0 is in accordance with standard DIN-53529 and at 150°C. Within the scope of the meaning of this patent application, "t0" means the t0 defined and measured above.

[0076] For example, in the proposed formulation, the t0 of a specific accelerator according to the proposed measurement method is shown in Table 1 below. DCBS represents N,N-dicyclohexyl-2-benzothiazole sulfenamide, TBBS represents N-tert-butyl-2-benzothiazole sulfenamide, and CBS represents N-cyclohexyl-2-benzothiazole sulfenamide.

[0077] [Table 1] TIFF0007836301000001.tif21140

[0078] Preferably, the vulcanization accelerator is selected from the group consisting of thiuram compounds, thiocarbamate derivatives, sulfenamides, thiophosphates, and mixtures thereof, and its t0 is 3.5 minutes or less, preferably less than 3 minutes. Most preferably, the rubber composition of the reinforced product according to the present invention comprises N-cyclohexyl-2-benzothiazole sulfenamide as the vulcanization accelerator.

[0079] The vulcanization accelerator is used in preferred concentrations of 0.1 to 6 phr, more preferably 0.5 to 4 phr, and most preferably 0.5 to 2.5 phr.

[0080] Preferably, the rubber composition for the reinforcing product according to the present invention contains at least 0.5 phr of zinc oxide, preferably at least 1 phr of zinc oxide. Preferably, the rubber composition for the reinforcing product according to the present invention contains up to 5 phr of zinc oxide, preferably up to 3 phr of zinc oxide.

[0081] (Additives) The rubber composition of the reinforced product according to the present invention may also include all or some of the common additives and processing aids known to those skilled in the art and particularly used in rubber compositions for pneumatic tires, such as plasticizers (plasticizing oils and / or plasticizing resins), fillers (for example, regenerated or desulfurized crumb resulting from the recycling of pneumatic tires, other reinforcing or non-reinforcing), pigments, protective agents such as anti-ozone waxes, chemical anti-ozone agents or antioxidants, anti-fatigue agents or reinforcing resins (for example, those described in International Application No. 02 / 10269).

[0082] The formulation of the rubber composition for the reinforcing product according to the present invention minimizes the use of cobalt salts, and in fact makes it possible to eliminate their use altogether, while maintaining excellent adhesive properties. Accordingly, in a preferred configuration, the rubber composition for the reinforcing product according to the present invention contains no cobalt salts, or less than 2 phr, preferably less than 1 phr, preferably less than 0.5 phr, and very preferably less than 0.1 phr.

[0083] Furthermore, the formulation of the rubber composition for the reinforcing product according to the present invention makes it possible to minimize, or even eliminate, the use of stearic acid or one of its derivatives. Accordingly, the rubber composition for the reinforcing product according to the present invention either does not contain stearic acid or one of its derivatives, or contains less than 2 phr, preferably less than 1 phr, preferably less than 0.5 phr, and very preferably less than 0.1 phr.

[0084] The rubber composition of the reinforcing product according to the present invention may further contain a guanidine compound, preferably diphenylguanidine. It has been observed that the presence of a guanidine compound, preferably diphenylguanidine, makes it possible to further improve the adhesion properties of the rubber composition to the metal reinforcing material.

[0085] Preferably, the content of guanidine compounds is in the range of 0.5 to 3 phr, more preferably 0.5 to 2.5 phr, and more preferably 0.5 to 2 phr.

[0086] (Reinforcement elements) The reinforcing product according to the present invention is based on at least one metal reinforcing element embedded in a rubber composition.

[0087] The phrase "based on at least one metal reinforcing element embedded in a rubber composition" should be understood to mean a reinforced product comprising the reinforcing element and the composition, and the composition may react with the surface of the reinforcing element at various stages of the manufacture of the reinforced product, particularly during the crosslinking of the composition or before the crosslinking of the composition during the manufacture of the reinforced product.

[0088] The aforementioned metal reinforcing element is a thread-like element. The metal reinforcing element can be made entirely or partially of metal.

[0089] In a particular configuration, the reinforcing element includes a metal surface.

[0090] The metal surface of the reinforcing element constitutes at least a portion, preferably all, of the surface of the element and is intended to be in direct contact with the rubber composition. Preferably, the reinforcing element is made of metal, i.e., composed of a metallic material.

[0091] The rubber composition coats at least some, and preferably all, of the reinforcing elements.

[0092] According to a first alternative embodiment of the present invention, the metal surface of the reinforcing element is made of a different material from the rest of the reinforcing element. In other words, the reinforcing element is made of a material that is at least partially covered, and preferably completely covered, by the metal layer constituting the metal surface. The material that is at least partially covered, and preferably completely covered, by the metal surface is metallic or non-metallic, and is preferably metallic.

[0093] According to a second alternative embodiment of the present invention, the reinforcing element is made of the same material, in which case the reinforcing element is made of the same metal as the metal surface.

[0094] Metal surfaces can improve, for example, the processing characteristics of reinforcing elements, or the usage characteristics of the reinforcing product and / or the pneumatic tire itself, such as adhesion properties, corrosion resistance, and aging resistance.

[0095] According to one embodiment of the present invention, the metal surface comprises a metal selected from the group consisting of copper, zinc, tin, aluminum, cobalt, nickel, and alloys containing at least one of these metals. The alloy can be a binary or ternary alloy, such as bronze and brass. Preferably, the metal of the metal surface is copper, tin, zinc, or an alloy containing at least one of these metals. More preferably, the metal of the metal surface is brass (Cu-Zn alloy), zinc, or bronze (Cu-Sn alloy), and more preferably, again, brass.

[0096] Some metals are prone to oxidation when in contact with the outside air, so these metals may be partially oxidized.

[0097] In a preferred embodiment, the reinforcing product according to the present invention comprises a plurality of reinforcing elements as defined above and calendered rubber in which the reinforcing elements are embedded, wherein the calendered rubber consists of a rubber composition of the reinforcing product according to the present invention. In this embodiment, the reinforcing elements are generally arranged side by side along the principal direction. In applications envisioned in tires, the reinforcing product according to the present invention can constitute a reinforcing material for a tire.

[0098] "Embedded" is understood to mean that the metal reinforcing element is in direct contact with the rubber composition across its entire surface.

[0099] The reinforcing product according to the present invention can be in an uncured state (before crosslinking of the rubber composition) or a cured state (after crosslinking of the rubber composition). The reinforcing product according to the present invention is cured after the reinforcing element is brought into contact with the rubber composition.

[0100] The reinforcing product according to the present invention is A step of manufacturing two layers of rubber composition, The process involves a step of sandwiching a reinforcing element between two layers by depositing reinforcing material between the two layers, The steps include, as appropriate, curing the reinforcing product according to the present invention, It can be manufactured by a process that includes this.

[0101] Alternatively, the reinforcing product according to the present invention can be manufactured by depositing reinforcing elements on a part of a layer, then folding the layer itself to cover the reinforcing elements, and sandwiching them over its entire length or a part thereof.

[0102] The layers can be manufactured by calendering. During the curing of the reinforced product according to the present invention, the rubber composition is crosslinked.

[0103] When the reinforcing product according to the present invention is intended to be used as a reinforcing material for a pneumatic tire, the curing of the reinforcing product according to the present invention generally occurs during the curing of the pneumatic tire.

[0104] (Finished or semi-finished products, and tires) Another subject of the present invention is a finished or semi-finished product comprising a reinforcing product according to the present invention. The finished or semi-finished product may be any article comprising a reinforcing product. Examples, but not limited to, include balls, conveyor belts, shoe soles, or pneumatic or non-pneumatic tires.

[0105] Another subject of the present invention, pneumatic or non-pneumatic tires, are essentially characterized by including a reinforcing product according to the present invention. The tire can be in an uncured state (before crosslinking of the rubber composition) or a cured state (after crosslinking of the rubber composition). Generally, during tire manufacturing, the reinforcing product is deposited in the tire structure in an uncured state (i.e., before crosslinking of the rubber composition) before the tire curing stage.

[0106] The tire according to the present invention includes a reinforcing layer comprising a reinforcing product according to the present invention, which is preferentially selected from carcass plies, crown plies, bead fillers, and combinations thereof. Furthermore, the rubber composition of the reinforcing product according to the present invention can be used as an inner layer of a pneumatic or non-pneumatic tire, the inner layer being a layer of the tire that does not come into contact with ambient air or expansion gas. Such an inner layer is, for example, a crown foot layer, a decoupling layer, an edge rubber, and combinations thereof. In this specification, “edge rubber” is understood to mean an edge of a reinforcing layer, an edge of a reinforcing element, or a layer positioned within the tire in direct contact with another edge rubber.

[0107] The present invention relates in particular to tires intended for use on passenger cars, SUVs (Sport Utility Vehicles), two-wheeled vehicles (especially motorcycles), aircraft, and also to vans, heavy vehicles, namely underground trains, buses, heavy road transport vehicles (tanleys, tractors, trailers), or off-road vehicles, heavy agricultural vehicles, or earthmoving machinery and other selected industrial vehicles.

[0108] Accordingly, the present invention relates in particular to a pneumatic or non-pneumatic tire comprising a crown covered with a tread and including a crown reinforcement formed from two crown plies of a reinforcing element, two beads intended to contact a rim, each including a circumferential reinforcing element, and two sidewalls, each extending radially inward, i.e., to the axial end of the crown up to the bead, wherein the tire further comprises a carcass reinforcement engaged with each of the beads and extending from the bead through the sidewall to the crown, and at least one of the two crown plies of the reinforcing element is made of the reinforcing product according to the present invention.

[0109] In another specific configuration, the present invention relates to a pneumatic or non-pneumatic tire comprising a crown covered with a tread and including a crown reinforcing body formed from two crown plies of reinforcing elements, two beads intended to contact a rim, each including a circumferential reinforcing element, and two sidewalls, each extending radially inward, i.e., to the axial end of the crown up to the bead, wherein the tire further comprises a carcass reinforcing body engaged with each of the beads and extending from the bead through the sidewall to the crown, and at least the carcass reinforcing body is made of the reinforcing product according to the present invention. [Examples]

[0110] (Preparation of rubber composition) The following tests are carried out by sequentially introducing various components other than diene elastomers (epoxidized or non-oxidized), reinforcing fillers, and vulcanizing systems into an internal mixer with an initial container temperature of approximately 60°C (final filling volume: approximately 70% by weight). Subsequently, thermomachining (non-productive stage) is performed in one stage, lasting a total of approximately 3-4 minutes until a maximum "dropping" temperature of 165°C is reached.

[0111] The mixture obtained in this way is collected and cooled, then sulfur and an accelerator (sulfenamide) are placed on a 30°C mixer (homofinisher), and everything is mixed for an appropriate time (e.g., between 5 and 12 minutes) (production stage).

[0112] The compositions thus obtained are then calendered in the form of plaques (2-3 mm thick) or thin rubber sheets, followed by a curing step at 150°C for 15 minutes, after which their physical or mechanical properties are measured.

[0113] (Measurement method) (Adhesion test) ( Preparation of test specimens ) The prepared rubber composition is used to create composite materials in the form of test specimens, according to the following protocol.

[0114] The metal / rubber composite used in this test was a block of rubber composition formed by bonding two plaques measuring 200 mm × 4.5 mm (millimeters) and 3.5 mm thick before curing, resulting in a block with a thickness of 7 mm. During the construction of this block, for example, 15 reinforcing members were trapped between the two uncured plaques, so that only a predetermined length of the reinforcing member, for example 4.5 mm, was in free contact with the rubber composition to which this length would be bonded during curing, while the remaining length of the reinforcing member was isolated from the rubber composition (e.g., using a plastic or metal film) to prevent bonding outside the predetermined contact zone. Each reinforcing member penetrated the rubber block, and at least one sufficient length of its free end (at least 5 cm, e.g., 5-10 cm) was held to allow for subsequent tensile testing of the reinforcing member.

[0115] Each metal reinforcement consists of two threads of 30 / 100 mm diameter, 0.7% carbon steel, twisted together, and the brass coating contains 63% copper.

[0116] Then, the block containing 15 reinforcing materials is placed in a suitable mold and cured at 150°C for 15 minutes under a pressure of approximately 15 bar.

[0117] (Measurement of tearing force) Once the hardening and aging of the above block is complete, each reinforcing material is pulled out of the rubber block using a tensile testing machine according to the method described in standard ASTM D 2229-02, with a pull rate of 100 mm / min. Thus, the adhesion is characterized by the force required to tear the reinforcing material from the test specimen at ambient temperature, and the tearing force represents the average of 15 measurements corresponding to 15 reinforcing materials of the composite.

[0118] The greater the force value, the higher the degree of adhesion between the cord and the rubber composition.

[0119] The tear force measurement is performed at t=0, 21 days later in air at 77°C. The humidity of the air is not controlled and corresponds to the humidity of the outside air, i.e., 30% to 50%.

[0120] The results are expressed on a base of 100, where a value of 100 corresponds to the composition under consideration and the specimen formed using the metal reinforcement described above. Values ​​greater than 100 indicate improved results, i.e., a tear force greater than that of the specimen at t=0.

[0121] (Tensile test) These tensile tests allow for the measurement of the elastic stress and fracture properties of the rubber composition. The tests were conducted in accordance with the French standard NF T 46-002 of September 1988. Elongation at fracture (in %) was measured at 23°C.

[0122] Measurements of elongation at fracture are performed at t=0, 7 days after setting the sample in air at 77°C, and 21 days after setting the sample in air at 77°C. The humidity of the air is not controlled and corresponds to the humidity of the surrounding air, i.e., between 30% and 50%.

[0123] The results are expressed on a baseline of 100, where a value of 100 is assigned to the elongation at break of the sample under consideration at t=0. A result greater than 100 indicates that the composition under consideration exhibits a greater elongation at break than the same composition at t=0.

[0124] (Rolling resistance meter) The rolling resistance induced by the test composition is estimated by measuring the energy loss at a temperature of 60°C, which is the energy recovered on the sixth rebound of a sample with an initial energy applied, as described in the standard DIN 53-512 of April 2000. This measurement is denoted as P60 and is calculated as follows: P60(%) = 100 × (E0 - E1) / E0 Here, E0 represents the initial energy and E1 represents the restored energy.

[0125] Loss measurements at 60°C were performed at t=0, 7 days later at 77°C in air, and 21 days later at 77°C in air. The humidity of the air was not controlled and corresponded to the humidity of the surrounding air, i.e., between 30% and 50%.

[0126] The results are expressed relative to 100, where a value of 100 is assigned to the loss value at 60°C for the sample under consideration at t=0. A result greater than 100 indicates that the composition under consideration exhibits a greater loss at 60°C at t=0 than the same composition, and therefore induces greater rolling resistance.

[0127] The results of different tests are shown in Table 2.

[0128] Composition T1 is a prior art calendering composition, such as those presented in International Publication No. 2016 / 058943 and French Patent No. 2 981 298.

[0129] [Table 2] TIFF0007836301000002.tif166144 (1) Natural rubber (peptized) (2) ENR 1: 25 mol% epoxidized natural rubber manufactured by Guthrie Polymer, ENR-25; ENR 2: 15% epoxidized natural rubber manufactured by Muang Mai Guthrie, produced by epoxidizing natural rubber; (3) ASTM Grade N326 (manufactured by Cabot); (4) Silica 160 MP, Zeosil 1165 MP, manufactured by Rhodia; (5) Octeo, Degussa to Dynasylan; (6) Zinc oxide (industrial grade), manufactured by Umicore; (7) Stearin, Pristerene 4931, from Uniqema; (8) N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (Santoflex 6-PD), manufactured by Flexsys; (9) CTP, N-(cyclohexylthio)phthalimide; sold by Lanxess under the name Vulkalent G, or by Duslo under the name Duslin P; (10) N,N-dicyclohexyl-2-benzothiazole sulfenamide (Santocure DCBS from Flexsys); (11) N-cyclohexyl-2-benzothiazole sulfenamide (Santocure CBS, Flexsys); (12) Diphenylguanidine

Claims

1. A reinforced product based on at least one metal reinforcing element embedded in a rubber composition based on a crosslinking system comprising at least one epoxidized diene elastomer, a reinforcing filler, and 1 to 2.5 phr of sulfur, A reinforcing product wherein the rubber composition comprises one of stearic acid or its derivatives with a concentration of less than 0.5 phr and zinc oxide with a concentration of 0.5 to 2.5 phr, and the epoxidized diene elastomer is the main component of the rubber composition.

2. The reinforcing product according to claim 1, wherein the vulcanization system further comprises a vulcanization accelerator used in a content of 0.1 to 6 phr.

3. The reinforcing product according to any one of claims 1 to 2, wherein the reinforcing filler contains silica as its main component.

4. The reinforcing product according to any one of claims 1 to 3, wherein the rubber composition further comprises a guanidine compound.

5. The reinforcing product according to claim 4, wherein the content of the guanidine compound is in the range of 0.5 to 3 phr.

6. The reinforcing product according to any one of claims 1 to 5, wherein the epoxidized diene elastomer is selected from the group consisting of epoxidized natural rubber, epoxidized synthetic polyisoprene, epoxidized polybutadiene, epoxidized butadiene / styrene copolymer, and mixtures thereof.

7. The reinforcing product according to any one of claims 1 to 6, wherein the rubber composition does not contain a cobalt salt or contains less than 2 phr.

8. The reinforcing product according to claim 3, wherein the rubber composition comprises a silica coupling agent, an agent for coating silica, and an agent selected from mixtures thereof, wherein the content of the agent ranges from 5% by weight to 20% by weight relative to the amount of silica, or the reinforcing product according to any one of claims 4 to 7, wherein these are dependent on claim 3.

9. A finished product or a semi-finished product comprising the reinforcing product described in any one of claims 1 to 8.

10. A pneumatic or non-pneumatic tire comprising a reinforcing product according to any one of claims 1 to 8.

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