Reinforced product comprising at least one metallic reinforcing element and a rubber composition

Abstract

The present invention relates to reinforced products comprising at least one metal reinforcing element embedded into a rubber composition, said rubber composition comprising at least one epoxidized diene elastomer, a reinforcing filler and a crosslinking system, said crosslinking system comprising at least 1 phr of sulfur.

Description

Technical Field

[0001] This invention relates to the field of reinforced rubber products (particularly reinforced rubber products intended for use in pneumatic or non-pneumatic tires) and articles comprising such reinforced products. Background Technology

[0002] The reinforcing ply of pneumatic tires or reinforced rubber products typically comprises a "calendered" rubber composition and metal reinforcing cords. The calendered composition must exhibit very good adhesion properties to the metal reinforcing cords throughout the tire's life, as well as good durability and low rolling resistance at break and hysteresis properties that impart good durability and low rolling resistance to the ply.

[0003] Therefore, the adhesion between the metal cord and the surrounding rubber is a key property for the effectiveness of the reinforcing ply layer in pneumatic tires or reinforced rubber products. Coating compositions are known in the art, comprising diene elastomers (particularly natural rubber), reinforcing fillers, and vulcanization systems highly specific to these compositions. Such vulcanization systems typically contain high levels of sulfur and zinc oxide, low levels of stearic acid, "slow" vulcanization accelerators, and vulcanization retarders. In these systems, adhesion between the rubber mixture and the metal cord is achieved through vulcanization of the brass-coated surface of the cord. Therefore, vulcanization retarders and "slow" vulcanization accelerators are used to enable the metal cord to vulcanize before the sulfur is consumed during vulcanization.

[0004] To improve one or more performance qualities and durability of calendered compositions, pneumatic tire manufacturers have conducted numerous studies.

[0005] Document WO2016 / 058943 discloses a reinforced product comprising a rubber composition coated and covered with reinforcing filaments, the composition being based on a diene elastomer, reinforcing fillers, and a vulcanization system comprising a “fast” vulcanization accelerator as defined below in this application, the composition exhibiting good aging resistance properties.

[0006] Document WO2019 / 122586 discloses a composition that is substantially free of molecular sulfur and contains an adhesion promoter. The composition exhibits good adhesion and stiffness properties and can be crosslinked through various crosslinking systems other than vulcanization.

[0007] Recently, document WO2020 / 058614 teaches a rubber composition based on at least one elastomer with epoxy functional groups, at least one reinforcing filler, a crosslinking system comprising polycarboxylic acids and imidazoles, and at least one specific polyphenol compound. The rubber composition exhibits excellent adhesive properties and good property retention over time.

[0008] Despite being highly effective, this composition, which employs an alternative crosslinking system for vulcanization, exhibits relative industrial invasiveness due to the diversity of its components.

[0009] In the course of further research, the applicant company discovered that reinforced products based on at least one metal reinforcing element embedded in a rubber composition exhibit good adhesion properties between the composition and the reinforcing element, while improving durability, particularly in terms of fracture properties and rolling resistance. The rubber composition is based on at least one epoxide diene elastomer, which is cross-linked by vulcanization and is therefore easy to use in industry. Summary of the Invention

[0010] The present invention relates to at least one reinforcing product based on at least one metal reinforcing element embedded in a rubber composition, the rubber composition being based on at least one epoxy diene elastomer, reinforcing filler, and crosslinking system, the crosslinking system comprising at least 1 phr of sulfur.

[0011] Preferably, the present invention relates to an enhanced product wherein the crosslinking system comprises 1 phr to 5 phr of sulfur, more preferably 1 phr to 4 phr of sulfur, and more preferably 1 phr to 2.5 phr of sulfur.

[0012] Preferably, the present invention relates to an enhanced product wherein the vulcanization system further comprises a vulcanization accelerator used at a concentration between 0.1 phr and 6 phr, more preferably between 0.5 phr and 4 phr, and most preferably between 0.5 phr and 2.5 phr.

[0013] Preferably, the present invention relates to an enhanced product wherein the crosslinking system comprises a vulcanization accelerator with a vulcanization initiation time (denoted as "t0") of less than 3.5 minutes, preferably less than or equal to 3 minutes.

[0014] Preferably, the present invention relates to a reinforced product, wherein the reinforcing filler mainly comprises silica.

[0015] Preferably, the present invention relates to a reinforced product wherein the rubber composition further comprises a guanidine compound, preferably diphenylguanidine. Preferably, the content of the guanidine compound ranges from 0.5 phr to 3 phr, more preferably from 0.5 phr to 2.5 phr, and even more preferably from 0.5 phr to 2 phr.

[0016] Preferably, the present invention relates to a reinforced product wherein the degree of epoxidation of the diene epoxidized elastomer is in the range of 5% to 40%, preferably 10% to 35%.

[0017] Preferably, the present invention relates to a reinforced product wherein the epoxidized diene elastomer is selected from epoxidized natural rubber, epoxidized synthetic polyisoprene, epoxidized polybutadiene with a cis-1,4 bond content preferably greater than 90%, epoxidized butadiene / styrene copolymer, and mixtures thereof, preferably selected from epoxidized natural rubber and epoxidized synthetic polyisoprene.

[0018] In a particular arrangement, the present invention relates to a reinforced product according to the invention, wherein the rubber composition further comprises a non-epoxydiene elastomer selected from polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymers, isoprene copolymers, and mixtures of these elastomers, preferably selected from natural rubber and synthetic polyisoprene. In this particular arrangement, the content of the non-epoxydiene elastomer is preferably between 0 phr and 49 phr, more preferably between 0 phr and 40 phr, and more preferably between 5 phr and 25 phr.

[0019] In another particular arrangement, the present invention relates to a reinforced product wherein the rubber composition comprises one or more epoxide diene elastomers as the sole elastomer.

[0020] Preferably, the present invention relates to a reinforced product wherein the rubber composition does not contain cobalt salt, or contains less than 2 phr, preferably less than 1 phr, more preferably less than 0.5 phr, and very preferably less than 0.1 phr of cobalt salt.

[0021] Preferably, the present invention relates to a reinforced product wherein the rubber composition does not contain any of the stearic acid or its derivatives, or contains less than 2 phr, preferably less than 1 phr, more preferably less than 0.5 phr, and very preferably less than 0.1 phr of the stearic acid or its derivatives.

[0022] Preferably, the present invention relates to a reinforced product wherein the rubber composition comprises a reagent selected from reagents for coupling silica, reagents for coating silica, and mixtures thereof, wherein the content of the reagent is in the range of 5% to 20% by weight relative to the amount of silica, and preferably 6% to 18% by weight relative to the amount of silica. Preferably, the reagent for coupling silica is selected from organosilanes, preferably organosilane polysulfides, polyorganosiloxanes, mercaptosilanes, and terminal mercaptosilanes, and most preferably organosilane polysulfides. Preferably, the reagent for coating silica is selected from alkylalkoxysilanes, polyols, polyethers, primary amines, secondary amines, or tertiary amines, or polyorganosiloxanes, and most preferably alkylalkoxysilanes.

[0023] Preferably, the present invention relates to a reinforced product wherein the rubber composition comprises up to 4 phr of zinc oxide, preferably up to 3 phr of zinc oxide, and more preferably up to 2.5 phr of zinc oxide.

[0024] Preferably, the present invention relates to a reinforced product wherein the total content of the reinforcing filler is between 10 phr and 200 phr, preferably between 10 phr and 100 phr, and most preferably between 25 phr and 75 phr.

[0025] Preferably, the present invention relates to a reinforced product, wherein the metal reinforcement includes a surface containing a metal selected from copper, zinc, tin, aluminum, cobalt, nickel, and alloys containing at least one of these metals. Preferably, the metal is selected from copper, tin, zinc, or alloys containing at least one of these metals. Preferably, the metal on the surface of the metal reinforcement is brass.

[0026] The present invention also relates to finished or semi-finished products comprising the enhanced products according to the present invention.

[0027] The present invention also relates to pneumatic or non-pneumatic tires comprising reinforced products according to the present invention. Detailed Implementation

[0028] definition

[0029] The term "based on" should be understood to mean that the product or composition contains a mixture of various components used and / or in-situ reaction products, some of which may react at least partially with each other and / or are intended to react with each other during various manufacturing stages of the composition. Therefore, the product or composition may be in a fully or partially crosslinked state or in a non-crosslinked state.

[0030] Within the meaning of this invention, the expression "parts by weight / percentage parts by weight elastomer" (or phr) should be understood as referring to parts by mass / percentage parts by mass elastomer.

[0031] In this application, unless otherwise expressly stated, all percentages (%) shown are weight percentages (%).

[0032] 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 limits a and b), while any numerical interval expressed as "from a to b" represents a range of values ​​from a to b (i.e., including the strict limits a and b).

[0033] The carbon-containing compounds mentioned in the specification can be of fossil or bio-based origin. In the case of bio-based compounds, they can be partially or wholly derived from biomass or obtained from renewable raw materials derived from biomass. This particularly relates to polymers, plasticizers, fillers, etc.

[0034] Enhanced products

[0035] The reinforced product according to the invention is based on at least one metal reinforcing element embedded in a rubber composition, the rubber composition being based on at least one epoxy diene elastomer, reinforcing filler, and crosslinking system, the crosslinking system containing at least 1 phr of sulfur.

[0036] Epoxidized diene elastomer

[0037] Epoxidized elastomers or rubbers (these two terms are known to be synonymous and interchangeable) are understood to mean any type of elastomer with elastomeric properties and epoxide-functionalized (or epoxidized) (i.e., containing epoxy functional groups), as known to those skilled in the art, whether it is a homopolymer, block copolymer, statistical copolymer, or other copolymer. The expressions "diene elastomer containing epoxy functional groups" or "epoxidized diene elastomer" may be used indiscriminately.

[0038] Epoxy diene elastomers are known to be solid at ambient temperature (20°C); solid is understood to mean any substance that, under the influence of gravity and at ambient temperature (20°C), does not have the ability to ultimately take on the shape of the container in which it exists after at least 24 hours.

[0039] For example, and unless otherwise explicitly stated, the glass transition temperature Tg of the elastomers described herein is measured by DSC (differential scanning calorimetry) in a known manner according to the 1999 standard ASTM D3418.

[0040] The rubber composition of the reinforced product according to the invention may contain only one epoxide diene elastomer, or a mixture of multiple epoxide diene elastomers (which will be represented by the singular "epoxide diene elastomer" to indicate the sum of the epoxide diene elastomers in the composition). The diene elastomer containing epoxy functional groups can be used in combination with any type of non-epoxide elastomer (e.g., diene elastomer), and in fact even with elastomers other than diene elastomers.

[0041] The epoxide diene elastomer is the main component in the rubber composition according to the invention, i.e., it is the only elastomer, or it is the elastomer with the largest mass in the composition.

[0042] According to a preferred embodiment of the invention, the rubber composition comprises a primary epoxidized diene elastomer of 51 phr to 100 phr, preferably 60 phr to 100 phr, and preferably 75 phr to 95 phr, and blends with one or more other secondary non-epoxidized elastomers of 0 phr to 49 phr, preferably 0 phr to 40 phr, and preferably 5 phr to 25 phr.

[0043] Preferably, the secondary non-epoxy elastomer is a non-epoxy diene elastomer selected from polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymer, isoprene copolymer, and mixtures of these elastomers, preferably selected from natural rubber and synthetic polyisoprene.

[0044] According to another preferred embodiment of the invention, for all elastomers of 100 phr, the composition comprises one or more epoxide diene elastomers.

[0045] The degree of epoxidation (mol%) of the diene epoxidized elastomer can vary considerably according to specific embodiments of the 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%. When the degree of epoxidation is less than 0.1%, there is a risk of insufficient target technical effect, while when the degree of epoxidation is greater than 80%, the inherent properties of the polymer deteriorate. For all these reasons, the degree of functionalization (especially epoxidation) is more preferably in the range of 5% to 40%, and advantageously in the range of 10% to 35%.

[0046] To reiterate, epoxide diene type elastomers should be understood as meaning at least partially (i.e., homopolymers or copolymers) derived from diene monomers (monomers with two conjugated or non-conjugated carbon-carbon double bonds) that have been functionalized, i.e., have epoxy functional groups.

[0047] Therefore, the first characteristic of epoxidized diene elastomers is that they are diene elastomers. These diene elastomers, as defined in this patent application, are non-thermoplastic and have a negative Tg value in most cases (i.e., less than 0°C). They can be classified in a known manner into two categories: those referred to as "fundamentally unsaturated" diene elastomers and those referred to as "fundamentally saturated" diene elastomers. Butyl rubber (e.g., EPDM-type copolymers of dienes and α-olefins) belongs to the category of fundamentally saturated diene elastomers, having a low or very low diene source unit content, always less than 15% (mol%). Conversely, fundamentally unsaturated diene elastomers are understood to mean 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 "fundamentally unsaturated" diene elastomers, "highly unsaturated" diene elastomers are specifically understood to mean diene elastomers with a diene source (conjugated diene) unit content greater than 50% (mol%).

[0048] 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 thereof. More preferably, such copolymers are selected from butadiene / styrene copolymers (SBR), isoprene / butadiene copolymers (BIR), isoprene / styrene copolymers (SIR), isoprene / butadiene / styrene copolymers (SBIR), and mixtures thereof.

[0049] The second essential characteristic of the epoxy diene elastomer claimed in this invention is that it is functionalized and has epoxy functional groups.

[0050] Depending on the preparation method (e.g., epoxidation or any other modification after copolymerization of diene functional groups present in the elastomer chain), the epoxy functional groups present in the diene elastomer are obtained by copolymerization or post-polymerization modification and are carried directly by the chain backbone or by side groups.

[0051] Epoxidized diene elastomers can be obtained, for example, in a known manner by epoxidation of equivalent non-epoxidized diene elastomers, for example by methods based on chloroalcohols or bromoalcohols, or by methods based on hydrogen peroxide, alkyl hydrogen peroxide, or peracids (e.g., peracetic acid or performic acid); see in particular Kautsch. Gummi Kunstst., 2004, 57(3), 82. The epoxy functional group is located in the polymer chain. Epoxidized natural rubber (abbreviated as “ENR”) may be specifically mentioned; such ENR is sold, for example, by Guthrie Polymer under the names ENR-25 and ENR-50 (epoxidation degrees of 20% and 50%, respectively). Epoxidized BR is also known in itself and is sold, for example, by Sartomer under the name Poly Bd (e.g., Poly Bd 605E). Epoxidized SBR can be prepared by epoxidation techniques known to those skilled in the art.

[0052] Diene elastomers with epoxy groups have been described, for example, in US 2003 / 120007 or EP 0763564 and US 6903165 or EP 1403287.

[0053] Preferably, the epoxidized diene elastomer is selected from epoxidized natural rubber (NR) (abbreviated as "ENR"), epoxidized synthetic polyisoprene (IR), epoxidized polybutadiene (BR) with a preferred cis-1,4 bond content of more than 90%, epoxidized butadiene / styrene copolymer (SBR), and mixtures of these elastomers.

[0054] Epoxy diene elastomers can also have side-chain epoxy functional groups. In this case, they can be obtained by post-polymerization modification (see, for example, J. Appl. Polym. Sci., 1999, 73, 1733), or by free radical copolymerization of diene monomers with monomers containing epoxy functional groups, particularly methacrylates containing epoxy functional groups, such as glycidyl methacrylate (this free radical polymerization (especially in bulk, in solution or in dispersion media—particularly in dispersions, emulsions or suspensions) is well known to those skilled in the art of polymer synthesis: see, for example, Macromolecules 1998, 31, 2822)), or by using nitriles containing epoxy functional groups. For example, document US 2011 / 0098404 describes an emulsion copolymerization of 1,3-butadiene, styrene and glycidyl methacrylate.

[0055] Reinforced packing

[0056] The rubber composition of the reinforced product according to the present invention comprises one or more reinforcing fillers.

[0057] Any type of "reinforcing" filler known to be able to reinforce rubber compositions that can be specifically used in the manufacture of tires can be used, such as organic fillers (e.g., carbon black), inorganic fillers (e.g., silica), or mixtures of both.

[0058] All carbon blacks (especially those conventionally used in tires or their treads) are suitable as carbon blacks. Among carbon blacks, more particular reference will be made to reinforcing carbon blacks of the 100, 200, and 300 series, or carbon blacks of the 500, 600, or 700 series (ASTM D-1765-2017 grade), such as N115, N134, N234, N326, N330, N339, N347, N375, N550, N683, or N772. These carbon blacks can be used commercially available in their standalone state, or in any other form (e.g., as a carrier for some rubber additives used). Carbon blacks can, for example, be incorporated into diene elastomers (especially isoprene elastomers) in masterbatch form (see, for example, applications WO97 / 36724-A2 and WO99 / 16600-A1). Also suitable is carbon black produced from tire recycling, such as carbon black produced from the pyrolysis of pneumatic tires, for example, Enviro CB P550 carbon black from the 500 series manufactured by Scandinavian Enviro Systems.

[0059] As examples of organic fillers other than carbon black, functionalized polyethylene organic fillers may be mentioned, such as those described in applications WO2006 / 069792-A1, WO2006 / 069793-A1, WO2008 / 003434-A1 and WO2008 / 003435-A1.

[0060] "Reinforced inorganic filler" should be understood herein to mean any inorganic or mineral filler (regardless of its color and origin (natural or synthetic)), also referred to as "white" filler, "transparent" filler, or even "non-black" filler in contrast to carbon black, capable of individually reinforcing rubber compositions intended for use in tire manufacturing without the need for methods other than intermediate coupling agents. In a known manner, certain reinforcing inorganic fillers may be characterized in particular by the presence of hydroxyl (-OH) groups on their surface.

[0061] Silica-based mineral fillers (preferably 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 specific surface area and CTAB specific surface area both less than 450 m². 2 / g, preferably at 30m 2 / g to 400m2 / g, especially 60m 2 / g to 300m 2 Any precipitated silica or pyrolytic silica within the range of / g. Any type of precipitated silica can be used, particularly highly dispersible precipitated silica (referred to as "HDS," used to indicate "highly dispersible" or "highly dispersible silica"). These precipitated silicas (whether they are or are not highly dispersible precipitated silica) are well known to those skilled in the art. Reference may be made to, for example, the silica described in applications WO03 / 016215-A1 and WO03 / 016387-A1. In commercial HDS silica, silica from Evonik may be used in particular. 5000GR and 7000GR silica, or from Solvay 1085GR 1115MP 1165MP Premium 200MP and HRS 1200MP silica. As a non-HDS silica, the following commercial silica can be used: from Evonik... VN2GR and VN3GR silica, from Solvay 175GR silica, Hi-Sil EZ120G(-D), Hi-Sil EZ160G(-D), Hi-Sil EZ200G(-D), Hi-Sil 243LD, Hi-Sil 210 and Hi-Sil HDP 320G silica from PPG, and K-160 from Wilmar.

[0062] In this application, the BET specific surface area was 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 according to the method adapted from standard NF ISO 5794-1, Annex E, June 2010 [multi-point (5-point) volumetric method - gas: nitrogen - vacuum degassing: 160°C for 1 hour - relative pressure p / p0 range: 0.05 to 0.17].

[0063] For inorganic fillers (e.g., silica), the CTAB specific surface area is determined, for example, according to Appendix G of standard NF ISO 5794-1, June 2010. This method is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) on the “outer” surface of the reinforcing filler.

[0064] For carbon black, the specific surface area of ​​STSA was determined according to the standard ASTM D6556-2016.

[0065] The physical state of the reinforcing inorganic filler provided is not important, regardless of whether it is in the form of powder, microspheres, granules, beads, or any other suitable densification. Of course, reinforcing inorganic filler is also understood to mean a mixture of different reinforcing inorganic fillers, especially the silica mixture mentioned above.

[0066] Preferably, the total content of reinforcing filler (carbon black and / or reinforcing inorganic filler (e.g., silica)) is between 10 phr and 200 phr, more preferably between 10 phr and 100 phr, and very preferably between 25 phr and 75 phr. The optimal values ​​vary in a known manner depending on the specific target application.

[0067] Preferably, the reinforcing filler in the rubber composition mainly comprises silica. This is primarily understood to mean that silica accounts for more than 50% of the total weight of the reinforcing filler.

[0068] When the reinforcing filler contains silica, preferably mainly silica, the rubber composition of the reinforcing product according to the invention preferably contains a reagent selected from reagents for coupling silica, reagents for coating silica, and mixtures thereof, wherein the reagent content is in the range of 5% to 20% by weight relative to the amount of silica, and preferably 6% to 18% by weight relative to the amount of silica.

[0069] Coupling agents are understood to mean at least bifunctional coupling agents (or binders) intended to provide a satisfactory chemical and / or physical connection between an inorganic filler (its particle surface) and an epoxide diene elastomer. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used. "Bifunctional" is understood to mean a compound having a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the epoxide diene elastomer. For example, such a bifunctional compound may contain a first functional group containing a silicon atom and a second functional group containing a sulfur atom, the first functional group being capable of interacting with the hydroxyl group of the inorganic filler and the second functional group being capable of interacting with the diene elastomer.

[0070] Preferably, the organosilane is selected from organosilane polysulfides (symmetric or asymmetric) (e.g., bis(3-triethoxysilylpropyl)tetrasulfide (abbreviated TESPT) sold by Evonik under the name Si69, or bis(3-triethoxysilylpropyl)disulfide (abbreviated TESPD) sold by Evonik under the name Si75), polyorganosiloxanes, mercaptosilanes, and terminal mercaptosilanes (e.g., S-(3-(triethoxysilyl)propyl)octanethioate sold by Momentive under the name NXT Silane). More preferably, the organosilane is an organosilane polysulfide.

[0071] Covering agents are understood, as is known to those skilled in the art, to be agents that do not provide bonding between the filler and the elastomer matrix. By covalently binding to the surface functional sites of inorganic fillers (e.g., covalently binding to the surface hydroxyl sites of silica in a known manner when the reinforcing inorganic filler is silica), covering agents improve the processability of the composition and reduce the viscosity of the composition in the uncured state.

[0072] Processing aids that can improve the ease of processing compositions in the uncured state by improving the dispersibility of inorganic fillers in a rubber matrix and reducing the viscosity of the composition in a known manner are generally considered as covering agents. These processing aids are, for example, hydrolyzable silanes (e.g., alkylalkoxysilanes (especially alkyltriethoxysilanes)), polyols, polyethers (e.g., polyethylene glycol), primary, secondary, or tertiary amines (e.g., trialkylolamines), or hydroxylated or hydrolyzable POS (e.g., α,ω-dihydroxy polyorganosiloxanes (especially α,ω-dihydroxy polydimethylsiloxanes)).

[0073] Crosslinking system

[0074] The rubber composition of the reinforced product according to the invention comprises a sulfur-based crosslinking system called a vulcanization system, the sulfur-based crosslinking system comprising at least 1 phr of sulfur.

[0075] Sulfur can be provided in any form (especially molecular sulfur or sulfur donors).

[0076] The composition of the enhanced product according to the invention has a low sulfur content. Sulfur is used in a preferred content ranging from 1 phr to 5 phr, preferably from 1 phr to 4 phr, and very preferably from 1 phr to 2.5 phr.

[0077] Preferably, the crosslinking system contains a "fast" vulcanization accelerator, i.e., a vulcanization initiation time (denoted as "t0") of less than 3.5 minutes, preferably a vulcanization accelerator of less than or equal to 3 minutes.

[0078] The t0 value of a given accelerator should be measured in a given rubber composition at a given vulcanization temperature. To compare “slow” or “fast” accelerators based on their t0 values, the composition given herein as a reference composition comprises 100 phr of NR, 47 phr of carbon black N326, 0.9 phr of stearic acid, 7.5 phr of ZnO, 4.5 phr of sulfur, and the accelerator. The t0 of the accelerator was determined at a molar content of 2.3 mmol / 100 parts by weight of elastomer (the commercial reference names of the components shown herein are the same as those used for the components in Example 1). The method for measuring t0 conforms to standard DIN-53529 at 150°C. Within the meaning of this patent application, “t0” means the t0 defined and measured as above.

[0079] For example, Table 1 below gives the t0 of certain accelerators in the proposed formulations using the proposed measurement method. DCBS represents N,N-dicyclohexyl-2-benzothiazole sulfenamide, TBBS represents N-tert-butyl-2-benzothiazole sulfenamide, and CBS represents N-cyclohexyl-2-benzothiazole sulfenamide.

[0080] [Table 1]

[0081] Molar mass (g / mol) 346.56 238.38 264.41 t0(min) 4.8 3.6 3.0

[0082] Preferably, the vulcanization accelerator is selected from thiuram compounds, derivatives of thiocarbamates, sulfenamides, thiophosphates, and mixtures of these vulcanization accelerators, wherein the vulcanization accelerator has a t0 of less than or equal to 3.5 minutes, preferably less than 3 minutes. Very preferably, the rubber composition of the reinforced product according to the invention comprises N-cyclohexyl-2-benzothiazole sulfenamide as a vulcanization accelerator.

[0083] The vulcanization accelerator is used at a preferred concentration between 0.1 phr and 6 phr, more preferably between 0.5 phr and 4 phr, and very preferably between 0.5 phr and 2.5 phr.

[0084] Preferably, the rubber composition of the reinforced product according to the invention contains at least 0.5 phr of zinc oxide, more preferably at least 1 phr of zinc oxide. Preferably, the rubber composition of the reinforced product according to the invention contains at most 5 phr of zinc oxide, more preferably at most 3 phr of zinc oxide.

[0085] additive

[0086] The rubber composition of the reinforced product according to the invention may also contain all or part of the commonly used additives and processing aids known to those skilled in the art and commonly used in rubber compositions for pneumatic tires, such as plasticizers (e.g., plasticizing oils and / or plasticizing resins), fillers (reinforcing fillers or non-reinforcing fillers other than those described above, such as recycled debris or desulfurized debris from the recycling of pneumatic tires), pigments, protective agents (e.g., anti-ozone waxes, chemical anti-ozone agents or antioxidants), anti-fatigue agents or reinforcing resins (e.g., the reinforcing resins described in application WO 02 / 10269).

[0087] The formulation of the rubber composition of the reinforced product according to the invention can minimize (actually even eliminate) the use of cobalt salt while maintaining excellent adhesive properties. Therefore, in a preferred arrangement, the rubber composition of the reinforced product according to the invention does not contain cobalt salt, or contains less than 2 phr, preferably less than 1 phr, more preferably less than 0.5 phr, and very preferably less than 0.1 phr of cobalt salt.

[0088] Furthermore, the formulation of the rubber composition of the reinforced product according to the invention can minimize (actually even eliminate) the use of stearic acid or one of its derivatives. Therefore, the rubber composition of the reinforced product according to the invention does not contain stearic acid or one of its derivatives, or contains less than 2 phr, preferably less than 1 phr, more preferably less than 0.5 phr, and very preferably less than 0.1 phr of stearic acid or one of its derivatives.

[0089] The rubber composition of the reinforced product according to the invention may additionally contain guanidine compounds, preferably diphenylguanidine. It has been observed that the presence of guanidine compounds (preferably diphenylguanidine) can further improve the adhesion properties of the rubber composition to the metal reinforcement.

[0090] Preferably, the content of guanidine compounds ranges from 0.5 phr to 3 phr, more preferably from 0.5 phr to 2.5 phr, and even more preferably from 0.5 phr to 2 phr.

[0091] Reinforcing element

[0092] The reinforced product according to the invention is based on at least one metal reinforcing element embedded in a rubber composition.

[0093] The statement “based on at least one metal reinforcing element embedded in a rubber composition” should be understood to mean that the reinforced product comprises the reinforcing element and the composition, and that the composition may react with the surface of the reinforcing element during various stages of the manufacturing process of the reinforced product (particularly during the crosslinking of the composition or during the manufacturing process of the reinforced product prior to the crosslinking of the composition).

[0094] The metal reinforcing element is a filament element. It may be entirely or partially metallic.

[0095] In a particular arrangement, the reinforcing element comprises a metallic surface.

[0096] The metallic surface of the reinforcing element constitutes at least a portion of the surface of the element, preferably the entire surface of the element, and is intended to be in direct contact with the rubber composition. Preferably, the reinforcing element is a metal reinforcing element, i.e., it is made of a metallic material.

[0097] The rubber composition is coated on at least a portion of the reinforcing element, preferably the entire element.

[0098] According to a first variant of the invention, the metal surface of the reinforcing element is made of a material different from the rest of the reinforcing element. In other words, the reinforcing element is made of a material that is at least partially (preferably completely) covered by a metal layer constituting the metal surface. The material that is at least partially (preferably completely) covered by the metal surface is a metallic or non-metallic (preferably metallic) material.

[0099] According to a second alternative of the 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.

[0100] Metal surfaces can improve, for example, the processability of reinforcing components, or enhance the usability of products and / or pneumatic tires themselves, such as adhesive properties, corrosion resistance, or aging resistance.

[0101] According to one embodiment of the invention, the metal surface comprises a metal selected from 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 bronze and brass. Preferably, the metal on the metal surface is copper, tin, zinc, or an alloy comprising at least one of these metals. More preferably, the metal on the metal surface is brass (Cu-Zn alloy), zinc, or bronze (Cu-Sn alloy), and even more preferably brass.

[0102] Because some metals oxidize when exposed to ambient air, metals may be partially oxidized.

[0103] According to a preferred embodiment, the reinforcing product according to the invention comprises a plurality of reinforcing elements as defined above and calendered rubber in which the reinforcing elements are embedded, said calendered rubber being composed of a rubber composition of the reinforcing product according to the invention. According to this embodiment, the reinforcing elements are typically arranged side-by-side along the main direction. Therefore, for applications contemplated in tires, the reinforcing product according to the invention can constitute a tire reinforcement.

[0104] Embedding is understood to mean that the metal reinforcing element is in direct contact with the rubber composition on its entire surface.

[0105] The reinforced product according to the invention can be in an uncured state (before crosslinking the rubber composition) or in a cured state (after crosslinking the rubber composition). The reinforced product according to the invention is cured after the reinforcing element comes into contact with the rubber composition.

[0106] The enhanced product according to the invention can be manufactured by a method including the following stages:

[0107] - Two layers for producing a rubber composition

[0108] - The reinforcing element is sandwiched between two layers by placing one or more reinforcing elements between the two layers.

[0109] -The reinforced product according to the invention is cured under appropriate conditions.

[0110] Alternatively, the reinforced product according to the invention can be manufactured by providing a reinforcing element on a portion of a layer, and then folding the layer itself to cover the reinforcing element, thereby sandwiching the reinforcing element between the layers over its entire length or a portion thereof.

[0111] The layers can be produced by calendering. During the curing of the reinforced product according to the invention, the rubber composition undergoes cross-linking.

[0112] When the reinforcing product according to the invention is intended to be used as a reinforcement for a pneumatic tire, the curing of the reinforcing product according to the invention is typically carried out during the curing of the pneumatic tire.

[0113] Finished or semi-finished products and tires

[0114] Another subject of the invention is finished or semi-finished products comprising the reinforced product according to the invention. The finished or semi-finished product can be any article comprising the reinforced product. For example, and in a non-limiting manner, references may be made to balls, conveyor belts, shoe soles, or pneumatic or non-pneumatic tires.

[0115] A fundamental characteristic of pneumatic or non-pneumatic tires (another subject of the invention) is that they contain a reinforcing product according to the invention. The tire can be in an uncured state (before the crosslinking rubber composition) or in a cured state (after the crosslinking rubber composition). Typically, during tire manufacturing, the reinforcing product is placed in the tire structure in an uncured state (i.e., before the crosslinking rubber composition) before the tire curing stage.

[0116] The tire according to the invention includes a reinforcing layer composed of a reinforcing product according to the invention, preferably selected from carcass plies, crown plies, bead fillers, and combinations thereof. Furthermore, the rubber composition of the reinforcing product according to the 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 is neither in contact with ambient air nor with the inflation gas. Such an inner layer is, for example, a crown underlayer, a release layer, edge rubber, and combinations thereof. In this application, "edge rubber" is understood to mean a layer in the tire that is configured to directly contact the ends of reinforcing layers, the ends of reinforcing elements, or other edge rubbers.

[0117] This invention relates in particular to tires intended for mounting on motor vehicles of the passenger vehicle type, SUVs (sports utility vehicles), two-wheeled vehicles (especially motorcycles), aircraft, or industrial vehicles and other vehicles selected from trucks, heavy vehicles (i.e., subways, buses, heavy road transport vehicles (trucks, tractors, trailers) or off-road vehicles (e.g., heavy agricultural vehicles or civil engineering equipment)).

[0118] Therefore, the present invention relates particularly to a pneumatic or non-pneumatic tire comprising a crown, two beads, and two sidewalls, the crown comprising a crown reinforcement formed of two crown ply layers with reinforcing elements and covered by the tread, the beads being intended to contact the rim and each comprising a circumferential reinforcing element, the sidewalls each extending radially inward from the axial end of the crown to the bead, the tire further comprising a carcass reinforcement anchored to each bead and extending from the bead through the sidewalls to the crown, at least one of the two crown ply layers with reinforcing elements being composed of a reinforcing product according to the present invention.

[0119] In another particular arrangement, the invention relates to a pneumatic or non-pneumatic tire comprising a crown, two beads, and two sidewalls. The crown includes a crown reinforcement formed of two crown ply layers with reinforcing elements and covered by the tread. The beads are intended to contact the rim and each includes a circumferential reinforcing element. The sidewalls each extend radially inward to the axial end of the crown to the bead. The tire further includes a carcass reinforcement anchored to each bead and extending from the bead through the sidewall to the crown. At least the carcass reinforcement is constructed of a reinforcing product according to the invention.

[0120] Example

[0121] Preparation of rubber composition

[0122] The following test was conducted as follows: Diene elastomer (epoxidized or non-epoxidized), reinforcing fillers, and various other components besides the vulcanization system were continuously introduced into a closed mixer (final fill percentage: approximately 70% by volume) with an initial container temperature of approximately 60°C. Then, thermomechanical processing (non-production stage) was performed in a phase lasting approximately 3 to 4 minutes until the maximum "discharge" temperature of 165°C was reached.

[0123] The resulting mixture is recovered and cooled, and then sulfur and accelerator (sulfenamide) are introduced into a 30°C mixer (homogenizer) to mix all the substances (production stage) for an appropriate time (e.g., between 5 and 12 minutes).

[0124] The resulting composition is then calendered in the form of rubber sheets (2 mm to 3 mm thick) or rubber films, and then cured at 150°C for 15 minutes before its physical or mechanical properties are measured.

[0125] Measurement methods

[0126] Adhesion test

[0127] Sample preparation

[0128] The prepared rubber composition was used to prepare a composite material in the form of a sample according to the following steps:

[0129] The metal / rubber composite material used in this test is a block of rubber composition consisting of two sheets, each 200 mm × 4.5 mm in size and 3.5 mm thick, bonded together before curing; the resulting block has a thickness of 7 mm. During the manufacture of this block, reinforcements (e.g., 15 in number) are embedded between the two uncured sheets; only reinforcements of a predetermined length (e.g., 4.5 mm) are in free contact with the rubber composition that will bond during curing; the remaining length of the reinforcement is separated from the rubber composition (e.g., using a plastic or metal film) to prevent any adhesion outside the predetermined contact area. Each reinforcement extends through the rubber block, maintaining at least one free end with sufficient length (at least 5 cm, e.g., between 5 cm and 10 cm) to allow for subsequent tensile testing of the reinforcement.

[0130] Each metal reinforcement consists of two steel wires twisted together, each with a diameter of 30 / 100 mm and containing 0.7% carbon; the brass coating contains 63% copper.

[0131] The block, which consists of 15 reinforcing bodies, is then placed in a suitable mold and cured at 150°C for 15 minutes under a pressure of about 15 bar.

[0132] Measurement of tearing force

[0133] At the end of the curing and aging of the above blocks, each reinforcement was pulled from the rubber block using a tensile testing machine according to the method described in standard ASTM D 2229-02; the pulling speed was 100 mm / min; thus, the adhesion was characterized by the force required to tear the reinforcement from the specimen at ambient temperature; the tear force is expressed as the average of 15 measurements corresponding to 15 reinforcements of the composite material.

[0134] The greater the force value, the better the adhesion between the cord and the rubber composition.

[0135] Tear force was measured in air at 77°C at t=0 and 21 days later. The humidity of the air was not controlled and corresponded to the humidity of the ambient air (i.e., between 30% and 50%).

[0136] The results are expressed in base 100, where 100 corresponds to a sample formed using the considered composition and the aforementioned metal reinforcement.

[0137] A value greater than 100 indicates the result of the improvement, that is, the tear force is greater than the tear force of the sample at t=0 days.

[0138] Tensile test

[0139] These tensile tests determine the elastic stress and fracture properties of the rubber composition. Tests were conducted according to French standard NF T 46-002 of September 1988. Elongation at break (in percentage) was measured at 23°C.

[0140] At t=0 days, the elongation at break was measured at 77°C in air after 7 days and at 77°C in air after 21 days. The humidity of the air was not controlled and corresponded to the humidity of the ambient air (i.e., between 30% and 50%).

[0141] Results are expressed as a base of 100, assigning a value of 100 to the elongation at break of the sample under consideration at t=0 days. A result greater than 100 indicates that the composition under consideration has a greater elongation at break than the same composition at t=0 days.

[0142] Rolling resistance index

[0143] The rolling resistance caused by the specimen is estimated by measuring the energy loss of the sample after the sixth rebound when initial energy is applied at a temperature of 60°C, as described in standard DIN 53-512 of April 2000. This measurement is denoted as P60 and is calculated as follows: P60(%) = 100 × (E0 - E1) / E0, where E0 represents the initial energy and E1 represents the recovered energy.

[0144] Losses at 60°C were measured at t=0 days later, at 77°C in air, and at 77°C in air after 21 days. Air humidity was not controlled and corresponded to ambient air humidity (i.e., between 30% and 50%).

[0145] Results are expressed as a base of 100, assigning a value of 100 to the loss of the sample under consideration at 60°C at t=0 days. A result greater than 100 indicates that the composition under consideration has a greater loss at 60°C than the same composition at t=0 days, resulting in greater rolling resistance.

[0146] Table 2 shows the results of different tests.

[0147] Composition T1 is a prior art calendering composition, for example, as shown in documents WO2016 / 058943 and FR 2981298.

[0148] [Table 2]

[0149]

[0150]

[0151] (1) Natural rubber (gelling)

[0152] (2) ENR 1: 25 mol% epoxidized natural rubber ENR-25 from Guthrie Polymer; ENR 2: 15% epoxidized natural rubber from Muang Mai Guthrie, prepared by the epoxidation of natural rubber;

[0153] (3) ASTM grade N326 (Cabot);

[0154] (4) 160 MPa silica from Rhodia, 1165 MPa Zeosil;

[0155] (5) Dynasylan Octeo from Degussa;

[0156] (6) Industrial-grade zinc oxide from Umicore;

[0157] (7) Pristerene 4931 stearin from Uniqema;

[0158] (8) N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (Santoflex 6-PPD) from Flexsys;

[0159] (9) CTP, N-(cyclohexylthio)phthalimide; sold by Lanxess under the name Vulkalent G or by Duslo under the name Duslin P;

[0160] (10) N,N-Dicyclohexyl-2-benzothiazole sulfenamide (Santocure DCBS from Flexsys);

[0161] (11) N-cyclohexyl-2-benzothiazole sulfenamide (Santocure CBS from Flexsys);

[0162] (12) Diphenylguanidine.

Claims

1. A reinforced product based on at least one metal reinforcing element embedded in a rubber composition, the rubber composition being based on at least one epoxy diene elastomer of 51 phr to 100 phr, reinforcing fillers, and a crosslinking system, the crosslinking system comprising 1 phr to 2.5 phr of sulfur, the rubber composition comprising less than 0.5 phr of stearic acid and up to 2.5 phr of zinc oxide, the epoxy diene elastomer having an epoxidation degree in the range of 5 mol% to 15 mol%.

2. The enhanced product according to claim 1, wherein, The vulcanization system also includes a vulcanization accelerator, which is used at a concentration between 0.1 phr and 6 phr.

3. The enhanced product according to claim 1 or 2, wherein, The reinforcing filler mainly contains silica.

4. The enhanced product according to claim 1, wherein, The rubber composition also contains guanidine compounds.

5. The enhanced product according to claim 4, wherein, The concentration of guanidine compounds ranges from 0.5 phr to 3 phr.

6. The enhanced product according to claim 1, wherein, Epoxidized diene elastomers are selected from epoxidized natural rubber, epoxidized synthetic polyisoprene, epoxidized polybutadiene, epoxidized butadiene / styrene copolymers, and mixtures of these elastomers.

7. The enhanced product according to claim 1, wherein, The rubber composition further comprises a non-epoxy diene elastomer selected from polybutadiene, natural rubber, synthetic polyisoprene, butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

8. The enhanced product according to claim 1, wherein, The rubber composition contains one or more epoxide diene elastomers as the sole elastomer.

9. The enhanced product according to claim 1, wherein, The rubber composition contains less than 2 phr of cobalt salt.

10. The enhanced product according to claim 1, wherein, The rubber composition contains less than 0.1 phr of stearic acid.

11. The enhanced product according to claim 3, wherein, The rubber composition contains a reagent selected from reagents for coupling silica, reagents for coating silica, and mixtures thereof, wherein the content of the reagent is in the range of 5% to 20% by weight relative to the amount of silica.

12. A finished or semi-finished product, said finished or semi-finished product comprising the reinforced product according to any one of claims 1 to 11.

13. A pneumatic or non-pneumatic tire, wherein the pneumatic or non-pneumatic tire comprises a reinforced product according to any one of claims 1 to 11.

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