WO2024121069A1 - Composite for rubber article - Google Patents

Abstract

The invention relates to a composite comprising at least one reinforcing element embedded in a rubber composition, the rubber composition being based on at least one isoprene elastomer, at most 50 phr of a copolymer of ethylene and a 1,3-diene, the ethylene units in the copolymer representing more than 50 mol % of the monomer units of the copolymer, at least 30 phr of a reinforcing inorganic filler, and a crosslinking system.

Description

COMPOSITE FOR RUBBER ARTICLE

Technical field of the invention

The present invention relates to the field of reinforced rubber compositions, and more particularly plies comprising metallic or textile reinforcements embedded in a rubber composition, these plies being intended to be used in particular in tires for vehicles, conveyor belts or belts.

Prior art

The performance of a tire for a vehicle, whether it is pneumatic, i.e. capable of supporting the load of the vehicle by means of a pressurized gas, or non-pneumatic, i.e. capable to support the load of the vehicle without the means of pressurized gas, for example by means of stays, a conveyor belt or a belt are partly linked to the rigidity of certain of their constituents. Indeed, resistance to deformation is an important characteristic making it possible to respond to the stresses to which these objects are subjected.

This need for rigidity is particularly essential in the calendered layers of the crown layers or in the low zones, which are the zones close to the rim, of a tire for a vehicle. In addition to rigidity, the mixtures concerned must meet broader specifications including low hysteresis, adhesion with the reinforcement, raw scalability (i.e. before crosslinking of the rubber composition) and cooked (after crosslinking) as low as possible.

The required levels of rigidity can be obtained by two main levers:

• The increase in the rate of reinforcing filler (black or silica),

• The use of thermosetting resins which constitute a secondary network interpenetrating with the filler-elastomer-vulcanization network.

However, the increase in the reinforcing load rate can lead to an increase in hysteresis and a deterioration in the processability of raw mixtures, in particular due to the increase in raw rigidity and the possible appearance of a decohesion phenomenon. Furthermore, the use of thermosetting resins can constitute an additional source of dissipation which could penalize hysteretic performance. In addition, certain resin-hardener systems used in tires are known to release formaldehyde and must therefore be handled with special precautions. Other ways have been explored to increase the rigidity of the compositions. For example, document WO2014/114607 teaches the use of a highly saturated diene elastomer to increase the rigidity of rubber compositions without degrading the hysteretic properties. As these compositions are mainly intended to be used in tire treads, this document does not address either the adhesion issues or the resistance to cracking of such compositions. However, the presence of reinforcing elements, and therefore interfaces between elements of very different mechanical rigidity and behavior (the reinforcing element and the rubber composition), can cause phenomena that are difficult to predict, particularly with regard to the properties of propagation of cracks, energy dissipation or adhesion.

Document W02020/074806 teaches the use of a blend of natural rubber and a copolymer of ethylene and a 1,3'diene with a carbon black to obtain good cohesion and resistance properties. ozone, which are sought after when used in the sidewalls of vehicle tires.

Continuing its research, the applicant discovered that a composite comprising at least one reinforcing element embedded in a rubber composition, the rubber composition being based on at least one isoprene elastomer, at most 50 phr of a copolymer of ethylene and a 1,3'diene, the ethylene units in the copolymer representing more than 50% by mole of the monomer units of the copolymer, at least 30 phr of an inorganic reinforcing filler, and a crosslinking system allowed very good expression of the stiffness/hysteresis compromise without penalizing the other performances expected for a composition used in a sheet, in particular adhesion and resistance to cracking.

Detailed description of the invention

The invention relates to a composite comprising at least one reinforcing element embedded in a rubber composition, the rubber composition being based on at least one isoprene elastomer, at most 50 phr of a copolymer of ethylene and a 1,3'diene, the ethylene units in the copolymer representing more than 50% by mole of the monomer units of the copolymer, at least 30 phr of a reinforcing inorganic filler, and a crosslinking system.

Preferably, the rubber composition comprises a metal oxide and a stearic acid derivative, the ratio of the level of metal oxide and stearic acid derivative, in phr, being greater than 2. Preferably, the rubber composition comprises less than 10 phr, preferably less than 5 phr of plasticizer.

Preferably, the copolymer of ethylene and a 1,3'diene comprises at least 60 mole% of ethylene units, preferably at least 65 mole% of ethylene units, more preferably at least 70 mole% of units. ethylene.

Preferably, the 1,3'diene units of the copolymer of ethylene and a 1,3'diene are those of a 1,3'diene having 4 to 12 carbon atoms, preferably those of 1, 3'butadiene, isoprene, 1,3-pentadiene, aryl-1,3 ^- butadiene and a mixture of these units.

Preferably, the reinforcing inorganic filler of the rubber composition is silica.

Preferably, the rubber composition comprises from 30 to 150 phr of silica.

Preferably, the rubber composition does not comprise carbon black, or comprises less than 10 phr, preferably less than 5 phr.

Preferably, the reinforcing element comprises a textile or metallic wire element.

Preferably, the metallic wire element is an elementary metallic monofilament or an assembly of several elementary metallic monofilaments.

Preferably, the reinforcing element comprises a textile wire element made of a thermoplastic or non-thermoplastic polymer material.

The invention also relates to a tire for a vehicle comprising a composite according to the invention.

Definitions

The compounds comprising carbon mentioned in the description may be of fossil or biosourced origin. In the latter case, they can be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. This concerns in particular polymers, plasticizers, fillers, etc. Any interval of values designated by the expression "between a and b" represents the domain of values greater than "a" and less than "b" (that is to say limits a and b excluded) while any interval of values designated by the expression "from a to b" mean the range of values going from "a" to "b" (that is to say including the strict limits a and b). The abbreviation "pce" means parts by weight per hundred parts of elastomer (of the total elastomers if several elastomers are present).

By the expression "based on" composition is meant in the present description a composition comprising the mixture and/or the in situ reaction product of the different constituents used, some of these basic constituents (for example the elastomer, the filler or the constituents of the vulcanization system or other additive conventionally used in a rubber composition intended for the manufacture of tires) being capable of, or intended to react with each other, at least in part, during the different phases of manufacturing the composition intended for the manufacture of tires for vehicles.

In the present application, the term “all of the monomer units of the elastomer” or “all of the monomer units of the elastomer” is understood to mean all the repetition units constituting the elastomer which result from the insertion of the monomers. in the elastomer chain by polymerization. Unless otherwise indicated, the contents of a monomer unit or repeating unit in the highly saturated diene elastomer are given in molar percentage calculated on the basis of all the monomer units of the elastomer.

Copolymer of ethylene and a 1,3-diene

The rubber composition of the composite according to the invention comprises at most 50 phr of a copolymer of ethylene and a 1,3-diene, the ethylene units in the copolymer representing more than 50% by mole of the monomer units of the copolymer .

The copolymer of ethylene and a 1,3'diene is a highly saturated, preferably random, diene elastomer which comprises ethylene units resulting from the polymerization of ethylene. In known manner, the expression "ethylene unit" refers to the motif -(CEk' CH ₂ )- resulting from the insertion of ethylene into the elastomer chain. The copolymer of ethylene and a 1,3'diene is rich in ethylene units, since the ethylene units represent more than 50% by mole of all the monomer units of the elastomer.

Preferably, the copolymer of ethylene and a 1,3'diene comprises at least 60 mole% of ethylene units, preferably at least 65 mole% of ethylene units, more preferably at least 70 mole% of ethylene units. . In other words, ethylene units in the copolymer of ethylene and a 1,3'diene preferably represent at least 60% by mole of all the monomer units of the copolymer of ethylene and a 1,3'diene, more preferably at least 65 Mole % of all the monomer units of the copolymer of ethylene and a 1,3'diene. Even more preferably, the ethylene units represent at least 70% by mole of all the monomer units of the copolymer of ethylene and a 1,3'diene.

Preferably, the ethylene units in the copolymer of ethylene and a 1,3'diene represent at most 90% by mole of all the monomer units of the copolymer of ethylene and a 1,3'diene. More preferably, the ethylene units represent at most 85% by mole of all the monomer units of the copolymer of ethylene and a 1,3'diene. Even more preferably, the ethylene units represent at most 80% by mole of all the monomer units of the copolymer of ethylene and a 1,3'diene.

According to an advantageous embodiment, the copolymer of ethylene and a 1,3'diene comprises from 60% to 90 mole% of ethylene unit, particularly from 60% to 85 mole% of ethylene unit, molar percentage calculated on the basis of all the monomer units of the copolymer of ethylene and a 1,3'diene. More advantageously, the copolymer of ethylene and a 1,3'diene comprises from 60% to 80 mole% of ethylene unit, mole percentage calculated on the basis of all the monomer units of the copolymer of ethylene and of 'a 1,3' diene.

According to another advantageous embodiment, the copolymer of ethylene and a 1,3'diene comprises from 65% to 90 mole% of ethylene unit, particularly from 65% to 85 mole% of ethylene unit, molar percentage calculated on the basis of all the monomer units of the copolymer of ethylene and a 1,3'diene. More advantageously, the copolymer of ethylene and a 1,3'diene comprises from 65% to 80 mole% of ethylene unit, mole percentage calculated on the basis of all the monomer units of the copolymer of ethylene and of 'a 1,3' diene.

According to yet another advantageous embodiment of the invention, the copolymer of ethylene and a 1,3'diene comprises from 70% to 90 mole % of ethylene unit, particularly from 70% to 85 mole % of ethylene unit, molar percentage calculated on the basis of all the monomer units of the copolymer of ethylene and a 1,3'diene. More advantageously, the copolymer of ethylene and a 1,3'diene comprises from 70% to 80 mole% of ethylene unit, molar percentage calculated on the basis of all the monomer units of the copolymer of ethylene and of 'a 1,3'diene. The copolymer of ethylene and a 1,3'diene being a copolymer of ethylene and a 1,3'diene, it also comprises 1,3'diene units resulting from the polymerization of a 1,3 'diene. In known manner, the expression "1,3'diene unit" or "diene unit" refers to the units resulting from the insertion of the 1,3'diene by a 1,4 addition, a 1,2 addition or an addition 3.4 in the case of isoprene for example. The 1,3'diene units are those for example of a 1,3'diene having 4 to 12 carbon atoms, such as 1,3'butadiene, isoprene, 1,3-pentadiene, an aryl'l,3'butadiene. Preferably, the 1,3'diene is 1,3'butadiene or a mixture of 1,3-dienes, one of which is 1,3'butadiene. More preferably, the 1,3'diene is 1,3-butadiene, in which case the copolymer of ethylene and a 1,3'diene is a copolymer of ethylene and 1,3'butadiene, of statistical preference.

The copolymer of ethylene and a 1,3' diene can be obtained according to different synthesis methods known to those skilled in the art, in particular depending on the targeted microstructure of the copolymer of ethylene and a 1,3' diene. Generally, it can be prepared by copolymerization of at least one 1,3'diene, preferably 1,3'butadiene, and ethylene and according to known synthesis methods, in particular in the presence of a catalytic system comprising a metallocene complex. In this respect, we can cite catalytic systems based on metallocene complexes, which catalytic systems are described in documents EP 1 092 731, WO 2004035639, WO 2007054223 and WO 2007054224 in the name of the Applicant. The copolymer of ethylene and a 1,3'diene, including when it is random, can also be prepared by a process using a catalytic system of preformed type such as those described in the documents WO 2017093654 Al, WO 2018020122 Al and WO 2018020123 AL Advantageously, the copolymer of ethylene and a 1,3'diene is random and is preferably prepared according to a semi-continuous or continuous process as described in the documents WO 2017103543 Al, WO 201713544 Al, WO 2018193193 and WO 2018193194.

La présence de motif cyclique saturé à 6 membres, 1,2-cyclohexanediyle, de formule (l) dans le copolymère peut résulter d’une série d’insertions très particulières de l’éthylène et du 1,3" butadiène dans la chaîne polymère au cours de sa croissance. Lorsque le copolymère d’éthylène et d’un 1,3'diène comprend des unités de formule (l) ou des unités de formule (II), les pourcentages molaires des unités de formule (l) et des unités de formule (II) dans l’élastomère diénique fortement saturé, respectivement o et p, satisfont de préférence à l’équation suivante (eq. 1) ou à l’équation (eq. 2), o et p étant calculés sur la base de l’ensemble des unités monomères du copolymère d’éthylène et d’un 1,3'diène. The copolymer of ethylene and a 1,3'diene preferably contains units of formula (I) or units of formula (II). )

The presence of a 6-membered saturated cyclic unit, 1,2-cyclohexanediyl, of formula (l) in the copolymer may result from a series of very specific insertions of ethylene and 1,3" butadiene in the polymer chain during its growth When the copolymer of ethylene and a 1,3'diene comprises units of formula (l) or units of formula (II), the molar percentages of the units of formula (l) and units of formula (II) in the highly saturated diene elastomer, respectively o and p, preferably satisfy the following equation (eq. 1) or the equation (eq. 2), o and p being calculated on the basis of all the monomer units of the copolymer of ethylene and a 1,3'diene.

0 < o+p < 30 (eq. 1) 0 < o+p < 25 (eq. 2)

Preferably, the copolymer of ethylene and a 1,3'diene comprises units of formula (l) in a molar rate greater than 0% and less than 15%, more preferably less than 10 molar%, molar percentage calculated on the basis of all the monomer units of the copolymer of ethylene and a 1,3'diene.

Isoprene elastomer

The rubber composition of the composite according to the invention has the essential characteristic of comprising at least one isoprene elastomer.

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

Preferably, the isoprene elastomer is chosen from the group consisting of synthetic polyisoprenes, natural rubber, isoprene copolymers and their mixtures, preferably from the group consisting of natural rubber, the polyisoprenes comprising a mass ratio cis 1.4 bonds of at least 90%, more preferably at least 98% relative to the mass of isoprene elastomer and their mixtures. Very preferably, the isoprene elastomer is natural rubber.

Preferably, the rubber composition of the composite according to the invention comprises at least 50 phr of isoprene elastomer. Preferably, the level of isoprene elastomer in the rubber composition is greater than 55 phr and less than or equal to 70 phr. The level of copolymer of ethylene and a 1,3'diene useful for the purposes of the invention, in particular of copolymer of ethylene and 1,3-butadiene in the rubber composition preferably varies in a range ranging from 10 to 40 pce.

Advantageously, the rubber composition comprises from 10 to 40 phr of copolymer of ethylene and 1,3'diene, in particular copolymer of ethylene and 1,3'butadiene, and from 60 to 90 phr of isoprene elastomer .

Inorganic filler

The rubber composition of the composite according to the invention comprises at least 30 phr of a reinforcing inorganic filler.

By "reinforcing inorganic filler", must be understood in the present application, by definition, any inorganic or mineral filler (whatever its color and its natural or synthetic origin), also called "white" filler, "clear" filler or even "non-black filler" as opposed to carbon black, capable of reinforcing by itself, without any means other than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words capable of replacing, in its reinforcing function, a conventional tire grade carbon black, such a filler is generally characterized, in a known manner, by the presence of hydroxyl groups (-OH) on its surface.

As reinforcing inorganic fillers, mineral fillers of the siliceous type, in particular silica (S1O2), are suitable in particular. or of the aluminous type, in particular alumina (AI2O3).

Preferably, the reinforcing inorganic filler is silica. The silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface area as well as a CTAB specific surface area both less than 450 m ² /g, preferably 30 to 400 m ² /g. As highly dispersible precipitated silicas (called "HDS"), we will cite for example the silicas "Ultrasil 7000" and "Ultrasil 7005" from the company Degussa, the silicas "Zeosil 1165MP", "1135MP" and "1115MP" from the company Degussa. Rhodia company, “Hi-Sil EZ150G” silica from PPG company, “Zeopol 8715”, “8745” and “8755” silicas from Huber company, silicas with high specific surface area as described in application WO 03/ 16837. The physical state in which the reinforcing inorganic filler is presented is irrelevant, whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, the term reinforcing inorganic filler also means mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and/or aluminous fillers.

The reinforcing inorganic filler used, in particular if it is silica, preferably has a BET surface area of between 45 and 400 m ² /g, more preferably between 60 and 300 m ² /g.

Preferably, the rubber composition of the composite according to the invention comprises from 30 to 150 phr, preferably from 35 to 100 phr of silica.

To couple the reinforcing inorganic filler to the elastomer, it is optionally possible to use in a known manner an at least bifunctional coupling agent (or bonding agent) intended to ensure a sufficient connection, of chemical and/or physical nature, between the inorganic filler (surface of its particles) and the elastomer, in particular organosilanes, or bifunctional polyorganosiloxanes.

It is possible to use in particular polysulfurized silanes, called "symmetrical" or "asymmetrical" depending on their particular structure, as described for example in applications W003/002648 (or US 2005/016651) and W003/002649 (or US 2005/016650) .

As examples of polysulfurized silanes, mention will be made more particularly of polysulfides (in particular disulfides, trisulfides or tetrasulfides) of bis-(alkoxyl(Cl-C4)-alkyl( ^Cl_C4 )silyl-alkyl( ^Cl_C4 )), such as for example bis( ^{3_trimethoxysilylpropyl} ) or bis( ^{3_triethoxysilylpropyl} ) polysulfides. Among these compounds, bis( ^{3_triethoxysilylpropyl} ) tetrasulfide, abbreviated TESPT, of formula [(C2H5O)3Si(CH2)3S2]2 or bis-(triethoxysilylpropyl) disulfide, abbreviated TESPD, of formula [(C2H5O)3Si(CH2)3S]2. Mention will also be made, as preferred examples, of polysulphides (in particular disulphides, trisulphides or tetrasulphides) of bis-(monoalkoxyl(Cl-C4)-dialkyl( ^Cl_C4 )silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulphide as described in patent application US 2004/132880.

As a coupling agent other than a polysulfurized alkoxysilane, mention will be made in particular of bifunctional POS (polyorganosiloxanes) or even hydroxysilane polysulfides as described in patent applications WO 02/30939 and WO 02/31041, or even silanes or POS carrying azo'dicarbonyl functional groups, as described for example in patent applications WO 2006/125532, WO 2006/125533, WO 2006/125534.

In the elastomeric compositions according to the invention, the content of coupling agent is preferably in a range ranging from 5 to 60% by weight relative to the quantity of silica, preferably in a range ranging from 15 to 50% by weight per relative to the quantity of silica and preferably ranging from 20 to 40% by weight relative to the quantity of silica. These rates have proven to be particularly advantageous for obtaining the properties of the composites according to the invention.

The rubber composition of the composite according to the invention may also comprise carbon black.

All carbon blacks are suitable as carbon blacks, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks). Among the latter, we will particularly mention the reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as for example the blacks NI 15, N134, N234, N326, N330, N339, N347, N375, or even, depending on the intended applications, higher series blacks (for example N660, N683, N772). The carbon blacks could for example already be incorporated into an isoprene elastomer in the form of a masterbatch (see for example applications WO 97/36724 or WO 99/16600). The BET specific surface area of carbon blacks is measured according to standard D6556-10 [multi-point method (at least 5 points) — gas: nitrogen - relative pressure range P/P0: 0.1 to 0.3].

Preferably, the rubber composition of the composite according to the invention does not comprise carbon black, or comprises less than 10 phr, preferably less than 5 phr.

Reticulation system

The rubber composition of the composite according to the invention comprises a crosslinking system.

The crosslinking system can be based either on sulfur or on sulfur donors and/or peroxide and/or bismaleimides. Preferably, the crosslinking system is a vulcanization system, that is to say a system based on sulfur (or a sulfur donor agent) and a vulcanization accelerator. Any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur can be used as a vulcanization accelerator, in particular accelerators of the thiazole type as well as their derivatives, sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate accelerators. As examples of such accelerators, the following sulfenamide compounds may be cited in particular: ■ N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), ter-butyb2-benzothiazyl sulfenamide ("TBBS") and mixtures of these compounds.

Sulfur is used at a preferential rate of between 0.3 pce and 10 pce, more preferably between 0.3 and 5 pce. The primary vulcanization accelerator is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5 phr.

Preferably, the composition of the composite according to the invention comprises a metal oxide and a stearic acid derivative, the ratio of the level of metal oxide and stearic acid derivative, in pce, being greater than 2. This preferential rate allows good adhesion to the reinforcing element embedded in the rubber composition. The metal oxide is preferably zinc oxide.

The rubber composition of the composite according to the invention preferably comprises a vulcanization accelerator. The vulcanization accelerator is used at a preferential rate such that the sulfur/vulcanization accelerator mass ratio is less than or equal to 5, preferably less than or equal to 4.

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

The crosslinking (or cooking), where appropriate the vulcanization, is carried out in a known manner at a temperature generally between 130°C and 200°C, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the temperature of cooking, the crosslinking system adopted and the crosslinking kinetics of the composition considered.

Miscellaneous additives

The rubber composition of the composite according to the invention may also comprise all or part of the usual additives usually used in elastomer compositions intended to be used in a vehicle tire, a conveyor belt or a belt, such as for example conditioning agents. implementation, plasticizers, pigments, protective agents such as anti-ozone waxes, chemical antrozonants, anti-oxidants.

All plasticizers conventionally used in tires are suitable as plasticizers. In this respect, we can cite preferably non-aromatic or very weakly aromatic oils chosen from the group consisting of naphthenic oils, paraffinic oils, MES oils, TDAE oils, vegetable oils, ether plasticizers, ester plasticizers.

Preferably, the rubber composition comprises less than 10 phr, preferably less than 5 phr of plasticizer.

The rubber composition can be manufactured in suitable mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art ■ a first working phase or thermo-mechanical mixing (sometimes referred to as a "non- productive") at high temperature, up to a maximum temperature between 110°C and 190°C, preferably between 130°C and 180°C, followed by a second phase of mechanical work (sometimes referred to as the "productive" phase ") at a lower temperature, typically below 110°C, for example between 40°C and 100°C, finishing phase during which the sulfur or the sulfur donor and the vulcanization accelerator are incorporated.

By way of example, the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents, possible conditioning agents are introduced into a suitable mixer such as a usual internal mixer. complementary implementation and other various additives, with the exception of sulfur and vulcanization accelerator. The total duration of mixing, in this non-productive phase, is preferably between 1 and 15 min. After cooling the mixture thus obtained during the first non-productive phase, the sulfur and the vulcanization accelerator are then incorporated at low temperature, generally in an external mixer such as a mixer. cylinders everything is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.

The final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for characterization in the laboratory, or even extruded, to form for example a rubber profile used for the manufacture of semi- finishes such as a reinforcing layer for tires.

Reinforcement element

The composite according to the invention comprises at least one reinforcing element embedded in the rubber composition.

By “embedded” means that the reinforcing element is completely covered by the rubber composition, with the possible exception of the cutting areas of the composite.

By reinforcing element is meant an element allowing the mechanical reinforcement of a matrix in which this reinforcing element is intended to be embedded. The reinforcing element comprises a wire element.

The wire element can be metallic or textile. By wire element, we mean an element having a length at least 10 times greater than the largest dimension of its section whatever the shape of the latter ■ circular, elliptical, oblong, polygonal, in particular rectangular or square or oval. In the case of a rectangular section, the wire element has the shape of a strip.

A metallic wire element may be a metallic elementary monofilament. Such an elementary metallic monofilament comprises a steel core, optionally coated with one or more layers of a coating which may be metallic and/or based on a non-metallic adhesive composition.

The metal coating comprises a metal chosen from zinc, copper, tin, cobalt and alloys of these metals. Examples of alloys of these metals include brass and bronze. The core steel is a carbon steel comprising between 0.1% and 1.2% carbon by mass, not more than 11% by mass of chromium, less than 1% by mass of each of the following elements ■ manganese , silicon, aluminum, boron, cobalt, copper, molybdenum, nickel, niobium, titanium, tungsten, vanadium, zirconium, phosphorus, sulfur, nitrogen, the remainder consisting of iron and unavoidable impurities resulting from processing. The steel can have a pearlitic, ferritic, austenitic, bainitic, martensitic microstructure or a microstructure resulting from a mixture of these microstructures.

The metallic elementary monofilament has a mechanical resistance ranging from 1000 MPa to 5000 MPa. Such mechanical resistance corresponds to the grades of steel commonly encountered in the field of tires, namely, the grades NT (Normal Tensile), HT (High Tensile), ST (Super Tensile), SHT (Super High Tensile), UT ( Ultra Tensile), UHT (Ultra High Tensile) and MT (Mega Tensile), the use of high mechanical strengths possibly allowing improved reinforcement of the matrix in which the reinforcing element is intended to be embedded and a lightening of the matrix thus reinforced.

In the case where the elementary metallic monofilament has a circular section, the diameter of these elementary metallic monofilaments preferably ranges from 0.05 mm to 0.50 mm.

A metallic wire element may be an assembly of several elementary metallic monofilaments as described above, assembled together in a helix, for example by wiring or twisting the elementary metallic monofilaments to form, for example layered cables comprising several concentric layers of monofilaments elementary metallic or stranded cables, each strand comprising several concentric layers of elementary metallic monofilaments. Optionally and as described in WO2005071157, such a metallic wire element comprises a layer based on a polymeric composition, preferably a composition comprising an elastomer, this layer being arranged between two layers of elementary metallic monofilaments of the layered cable or a strand of the stranded cable.

A textile filament element may be an elementary textile monofilament optionally coated with one or more layers of a coating based on an adhesive composition. This elementary textile monofilament is obtained, for example, by melt spinning, solution spinning or gel spinning. Each elementary textile monofilament is made of an organic material, in particular polymeric, or inorganic, such as for example glass or carbon. The polymeric materials can be of the thermoplastic type, such as for example aliphatic polyamides, in particular polyamides 6-6, and polyesters, in particular polyethylene terephthalate. The polymeric materials can be of the non-thermoplastic type, such as for example aromatic polyamides, in particular aramid, and cellulose, natural or artificial, in particular rayon. A textile filament element may be an assembly of several elementary textile monofilaments as defined above. In a first variant, the assembly comprises 2 to 7 elementary textile monofilaments each having a substantially circular section with a diameter ranging for example from 0.10 mm to 0.50 mm. In a second variant, the assembly comprises more than 10 elementary textile monofilaments, preferably more than 100 elementary textile monofilaments and more preferably more than 500 elementary textile monofilaments each having a substantially circular section with a diameter ranging for example from 2 m to 100 pmi . In the first and second variants, the assembly formed is commonly called strand.

A textile wire element can also be an assembly of several assemblies or strands as defined above. In a variant, the materials in which the elementary textile monofilaments of each assembly or strand are made are identical. In another variant, the materials in which the elementary textile monofilaments of each assembly or strand are made are different, the textile wire element then being commonly called a hybrid textile wire element.

In one embodiment, whether in the case of a metallic or textile wire element, the layer based on a non-metallic adhesive composition is formed by a layer of an adhesion primer making it possible to improve the adhesion of the wire element, for example to an elastomeric matrix. Such adhesion primers are those commonly used by those skilled in the art for the pre-gluing of certain textile fibers (in particular polyester fibers, for example PET, aramid, aramid/nylon). For example, we could use an epoxy-based primer, in particular based on polyglycerol polyglycidyl ether. A primer based on blocked isocyanate can also be used.

In another embodiment, whether in the case of a metallic or textile wire element, the layer based on a non-metallic adhesive composition is formed by a layer based on a resin and a latex of elastomer(s). We will cite adhesive compositions of the RFL type (Resorcinol — Formaldehyde — Latex) but also adhesive compositions such as described in WO2015118041.

In yet another embodiment, whether in the case of a metallic or textile wire element, we may have a layer of an adhesion primer as described above and covering the wire element, this layer of primary of adhesion being itself coated with a layer based on a resin and a latex of one or more elastomers as described above.

In one embodiment, the reinforcing element comprises a wire element and possibly a sheath covering the wire element individually or collectively several wire elements. The sheath may comprise one or more layers, each layer being based on a polymeric composition, for example a [thermoplastic] composition or [as described in WO2010/136389, WO2010/105975, WO2011/012521, WO2011/051204, WO2012 /016757, WO2012/038340, WO2012/038341, WO2012/069346, WO2012/104279, WO2012/104280 and WO2012/104281], In this embodiment, the polymer composition of each layer of the sheath is different from the base composition of the matrix in which the sheathed wire element(s) is intended to be embedded.

In another embodiment, the reinforcing element can be a knitted fabric or a fabric.

A knit is an assembly of wire elements as defined above and comprising stitches formed by one or more of these wire elements. Each stitch includes a loop interwoven with another loop. We can mention, for example, jersey or English rib texture knits for picked-stitch knits and charmeuse or atlas texture knits for warp-stitch knits.

A fabric is an assembly of a first family of wire elements, called warp wire elements, substantially parallel to each other, and a second family of wire elements, called weft wire elements, substantially parallel to each other. Preferably, the wire elements of the first family are substantially perpendicular to the wire elements of the second family.

In the embodiment of the composite in which each reinforcing element is a wire reinforcing element, the wire reinforcing elements are arranged parallel to each other and they are embedded, for example by calendering, in the rubber composition. We then obtain a so-called straight sheet, in which the wire reinforcing elements of the sheet are parallel to each other and are parallel to a main direction of the sheet. Then, if necessary, portions of each straight ply are cut at a cutting angle and these portions are joined together so as to obtain a so-called angled ply, in which the wire reinforcing elements of the ply are parallel to each other. to each other and form an angle with the main direction of the angled sheet, the angle formed with the main direction then being equal to the cutting angle.

Pneumatic

The vehicle tire, another object of the invention, comprises a composite according to the invention. Preferably, the bandage comprises a reinforced sheet made of a composite according to the invention.

The composite and the bandage according to the invention can be in the raw state (that is to say before crosslinking) or in the cooked state (that is to say after crosslinking).

Examples

Preparation of rubber compositions

Seventeen rubber compositions O1 to 017, the details of the formulation of which appear in Tables 1 and 2, were prepared in the following manner ■

The elastomers, the organic or inorganic filler (carbon black or silica) are successively introduced into an internal mixer (final filling rate ■ approximately 70% by volume), whose initial tank temperature is approximately 80°C. as the various other ingredients with the exception of sulfur and the vulcanization accelerator. Thermomechanical work is then carried out (non-productive phase) in one step, which lasts in total around 3 to 4 min, until a maximum “drop” temperature of 165°C is reached. The mixture thus obtained is recovered, cooled and then the sulfur and the vulcanization accelerator are incorporated on a mixer (homo-finisher) at 30 ° C, mixing everything (productive phase) for an appropriate time (for example a ten minutes).

The compositions thus obtained are then calendered either in the form of plates (thickness 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded to form, for example, a profile for a tire.

The rubber compositions, with the exception of the compositions Ol, ^C_6 and 010, contain a highly saturated diene elastomer whose ethylene molar content is greater than 50% and natural rubber, in this case comprising 74 molar% of ethylene units.

Tests and measurements

Measurement of Mooney viscosity (or Mooney plasticity) An oscillating consistometer is used as described in the French standard NF T 43'005 (1991). The Mooney plasticity measurement is carried out according to the following principle ■ the composition in the raw state (before cooking) is molded in a cylindrical enclosure heated to 100°C. After one minute of preheating, the rotor rotates within the test piece at 2 revolutions/minute and the torque useful to maintain this movement is measured after 4 minutes of rotation. Mooney plasticity (ML 1+4) is expressed in "Mooney unit" (UM, with 1 MU=0.83 Newton. meter). The lower the Mooney value, the lower the viscosity before cooking and the better the processability of the composition.

Tensile tests

The tests were carried out in accordance with the French standard NF T 46'002 of September 1988. All traction measurements were carried out under normal conditions of temperature (23±2°C) and humidity (50±5% d relative humidity), according to the French standard NF T 40'101 (December 1979).

We measured in second elongation (that is to say after accommodation) the nominal secant modulus calculated by referring to the initial section of the specimen (or apparent stress, in MPa) at 10% elongation denoted MAio, on samples cooked for 60 minutes at 150°C.

Dynamic properties (after cooking)

The dynamic properties tan(d)max at 23°C are measured on a viscoanalyzer (Metravib VA4000), according to standard ASTM D 5992'96. We record the response of a sample of reticulated composition (cylindrical test piece 4 mm thick and 400 mm ² in section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, under the defined conditions of temperature for example at 23°C according to standard ASTM D 1349' 99. A deformation amplitude scan is carried out from 0.1 to 50% (forward cycle), then from 50% to 1% (return cycle). The results used are the loss factor tan(d). For the return cycle, we indicate the maximum value of tan(d) observed, denoted tan(d)max.

We recall that, in a manner well known to those skilled in the art, the value of tan(d)max at 23°C is representative of the hysteresis of the material and therefore of the rolling resistance ■ plus tan(d)max at 23 °C is lower, the more the rolling resistance is reduced and therefore improved.

Adhesion tests

Strips are manufactured consisting of three metal wires with a diameter of 0.32 mm placed parallel to each other embedded in a polyamide 6'6 sheath so as to obtain a strip 0.46 mm thick and 1.45 mm thick. of width. The strip is covered with RFL glue then embedded in the rubber composition tested.

To test the adhesion of the rubber composition tested on the strip, a measurement was carried out according to the ASTM D2229 standard.

The adhesion levels are characterized by measuring the so-called tearing force (denoted Fmax) to tear the strip from the test piece. The results are expressed in base 100, a value greater than 100 indicating a pull-out force greater than the reference specimen. copolymer of ethylene and a 1,3'diene

The copolymer of ethylene and a 1,3'diene used in the following examples is prepared according to the following procedure ■

In a 70 L reactor containing methylcyclohexane (64 L), ethylene (5600 g) and 1,3'butadiene (2948 g), butyloctylmagnesium (BOMAG) in solution in the methylcyclohexane and the catalytic system is added. . The Mg/Nd ratio is 6.2. The volume of the solution of the catalytic system introduced is 840 mL, the concentration of the solution of the catalytic system in Nd being 0.0065 M. The reaction temperature is regulated to a temperature of 80 ° C and the polymerization reaction starts. The polymerization reaction takes place at a constant pressure of 8.3 bars. The reactor is supplied throughout the polymerization with ethylene and 1,3'butadiene in the molar proportions 73/27. The polymerization reaction is stopped by cooling, degassing the reactor and adding ethanol. An antioxidant is added to the polymer solution. The copolymer is recovered after stripping with steam and drying to constant mass. The polymerization time is 225 minutes. The weighed mass (6,206 kg) makes it possible to determine the average catalytic activity of the catalytic system expressed in kilogram of polymer synthesized per mole of neodymium metal and per hour (kg/mol.h). The copolymer has an ML value (1+4) at 100°C equal to 62.

The catalyst system is a preformed catalyst system. It is prepared in methylcyclohexane from a metallocene, [Me2Si(Flu)2Nd( -BH4)2Li(THF)] at 0.0065 mol/L, from a co-catalyst, butyloctylmagnesium (BOMAG) whose ratio molar BOMAG/Nd is equal to 2.2, and a preformation monomer, 1,3'butadiene whose molar ratio 1,3-butadiene/Nd is equal to 90. The medium is heated to 80°C over a period from 5 a.m. He is prepared according to a preparation method in accordance with paragraph II.1 of patent application WO 2017093654 Al.

The copolymer of ethylene and a 1,3-diene obtained, a copolymer of ethylene and 1,3-butadiene, is an ethylene-butadiene elastomer, designated under the term “EBR” hereinafter.

Example 1

In this example, we vary the proportion of EBR in the NR-EBR blend. We evaluate the way in which the rigidity/hysteresis compromise evolves (MAio/tan(§) ratio). The results are expressed in base 100, the value of 100 being assigned, for each series comprising a given silica content, to the rigidity/hysteresis compromise of the composition not comprising EBR.

A result greater than 100 indicates that the composition of the example considered presents a stronger ratio than the control.

[Table 1]

(1) Copolymer of ethylene and 1,3'butadiene containing 74% by mole of ethylene unit, 19% of butadiene unit in the form of 1,2 and 1.4 units and 7% by mole of unit 1,2- cyclohexanediyl, of Tg -44°C

(2) “Zeosil 1165 MP” from SolvayRhodia in the form of micropearls, CTAB 160 m ² /g, precipitated silica

(3) Silane liquid triethoxysilylpropyltetrasulfide (TESPT) “Si69” from the company Evonik

(4) Diphenylguanidine “Perkacit DPG” from the company Flexsys

(5) N-(1,3-dimethylbutyl)’N’-phenyl-p-phenylenediamine “Santoflex 6PPD” from the company Flexys

(6) Stearic acid “Pristerene 4931” from the company Uniqema

(7) Industrial grade Zinc Oxide from Umicore (8) N-cyclohexyl-2-benzothiazol-sulfenamide “Santocure CBS” from the company Flexsys

We see that the association of an inorganic filler with a blend of natural rubber and an EBR allows a very good expression of the stiffness/hysteresis compromise, this expression being all the more marked as the inorganic filler content is high.

For a lower inorganic filler content, the stiffness/hysteresis compromise no longer changes significantly as a function of the proportion of NR and EBR in the NRRBR blend.

Example 2

In this example, we evaluate the way in which the rigidity/hysteresis compromise (MAio/tan(§) ratio) evolves by varying the proportion of EBR in the NR-EBR blend for a set of compositions comprising carbon black, and a set of compositions comprising silica. The compositions C ^_ 14 and C ^_ 17 are adjusted so as to present substantially the same MAio rigidity and the same rigidity/hysteresis compromise.

The results are expressed in base 100, the value of 100 being attributed to the stiffness/hysteresis ratio and to the stiffness MAio of composition 04. A result greater than 100 indicates that the composition of the example considered has greater rigidity ( or a higher ratio) than the control.

[Table 2]

(1) to (8) idem Table 1

(9) AS TM N347 grade carbon black

(10) Cobalt salt (11) Cyclohexylthiopthalimide (PVI)

(12) N-ter-butyl’2-benzothiazyl sulfenamide from the company Flexsys

In Table 2, the compositions were adjusted so that the stiffness at 10% strain (MA10) was similar for the silica-based blends and the carbon black-based blends. The results are expressed in base 100, based on composition 04.

We see that the stiffness at 10% deformation and the stiffness/hysteresis compromise of compositions 14 (carbon black) and 04 (silica) are similar. We observe that the association of an inorganic filler with a blend of natural rubber and an EBR allows a better expression of the stiffness/hysteresis compromise than the association of an organic filler with a blend of natural rubber and a EBR. [Table 3]

The data presented in Table 3 are also shown in Figure 1.

The cracking speed increases as a function of the restitution energy. These speeds increase in approximately the same way as long as the EBR content is less than 50 phr. The cracking speed increases notably faster when the EBR content reaches 50 phr.

Example 3

In this example, the adhesion properties of different compositions are evaluated. Different rubber blocks are tested with the compositions presented in Table 4.

For compositions ^C_1 to ^C_4 , the reference specimen is the specimen made of the rubber composition not comprising EBR ( ^C_l ). For compositions ^C_6 and ^C_8 , the reference specimen is the specimen made of the rubber composition not comprising EBR (06). For compositions 14 and 016, the reference specimen is the specimen made of rubber composition 014.

[Table 4]

It can be seen that for the compositions tested, the level of adhesion is not significantly impacted by the presence of EBR.

Claims

[Claim 1] Composite comprising at least one reinforcing element embedded in a rubber composition, the rubber composition being based on at least one isoprene elastomer, at most 50 phr of a copolymer of ethylene and a 1 ,3'diene, the ethylene units in the copolymer representing more than 50% by mole of the monomer units of the copolymer, at least 30 phr of a reinforcing inorganic filler, and a crosslinking system. [Claim 2] Composite according to the preceding claim in which the rubber composition comprises a metal oxide and a stearic acid derivative, the ratio of the level of metal oxide and stearic acid derivative, in pce, being greater than 2. [Claim 3] Composite according to any one of the preceding claims in which the rubber composition comprises less than 10 phr, preferably less than 5 phr of plasticizer. [Claim 4] Composite according to any one of the preceding claims in which the copolymer of ethylene and a 1,3'diene comprises at least 60 mole% of ethylene unit, preferably at least 65 mole% of ethylene unit , more preferably at least 70 mole% of ethylene units. [Claim 5] Composite according to any one of the preceding claims in which the 1,3'diene units of the copolymer of ethylene and a 1,3'diene are those of a 1,3'diene having 4 to 12 carbon atoms, preferably those of 1,3'butadiene, isoprene, 1,3-pentadiene, an aryl-1,3-butadiene and a mixture of these units. [Claim 6] Composite according to any one of the preceding claims wherein the reinforcing inorganic filler of the rubber composition is silica. [Claim 7] Composite according to the preceding claim in which the rubber composition comprises from 30 to 150 phr of silica. [Claim 8] Composite according to one of claims 6 or 7 in which the rubber composition comprises a coupling agent whose content is in a range ranging from 5 to 60% by weight relative to the quantity of silica, preferably in a range ranging from 15 to 50% by weight per relative to the quantity of silica and preferably ranging from 20 to 40% by weight relative to the quantity of silica. [Claim 9] Composite according to any one of the preceding claims in which the rubber composition does not comprise carbon black, or comprises less than 10 phr, preferably less than 5 phr. [Claim 10] Composite according to any one of the preceding claims in which the reinforcing element comprises a textile or metallic wire element. [Claim 11] Composite according to the preceding claim in which the metallic wire element is an elementary metallic monofilament or an assembly of several elementary metallic monofilaments. [Claim 12] Composite according to claim 10 in which the reinforcing element comprises a textile wire element made of a thermoplastic or non-thermoplastic polymer material. [Claim 13] Vehicle tire comprising a composite according to any one of the preceding claims.