FR2853660A1 - COMPOSITE (METAL / RUBBER) FOR PNEUMATIC - Google Patents

Abstract

Composite (metal / rubber) comprising a matrix of diene elastomer reinforced by a metallic reinforcement adhered to the elastomer matrix via an adhesive interphase, said adhesive interphase being based on a bifunctional coupling agent comprising at least one at least one graftable "Y" function on the metal body, characterized in that said Y function corresponds to the formula: (I) -P (Q) R n (OR) 2-n in which: - P represents phosphorus; Q represents oxygen or sulfur; R 'represents a monovalent hydrocarbon group; n is equal to 0 or 1; - the symbols R, which are identical or different if n is equal to 0, each represent a monovalent hydrocarbon group; hydrogen or an alkali metal selected from Na and K.Use of such a composite for the manufacture of ground connection systems of motor vehicles, in particular tires.

Description

The present invention relates to composites (metal / rubber) and

particular to

  adhesive interphases ensuring, in such composites, the bond between metal and rubber.

  It relates in particular to sulfur-crosslinkable (steel / rubber) composites which can be used for the manufacture of ground connection systems of motor vehicles, in particular tires.

  Tire (metal / rubber) composites are well known and have been described in a very large number of documents. They generally consist of a rubber matrix comprising reinforcing elements (or "reinforcements") metal, usually in the form of son or wire assemblies.

  Subject to very significant constraints during the rolling of the tires, in particular to repeated compressions, flexions or curvature variations, these composites must in a known manner satisfy a large number of technical criteria, sometimes contradictory, such as uniformity, flexibility, endurance in flexion and compression, tensile, wear and corrosion resistance, and maintain such performance at a very high level as long as possible. It is easy to understand that the adhesive interphase between rubber and metal plays a major role in the durability of these performances.

  The traditional method for bonding rubber compositions in particular to carbon steel is to coat the surface of the steel with brass (copper-zinc alloy), the bond between the steel and the composition being provided by sulfurization. brass during vulcanization.

  To ensure optimum adhesion, an adhesion promoter additive such as a cobalt salt is also frequently used in the rubber composition.

  The brass coating has the known disadvantage that the adhesion between the carbon steel and the rubber matrix is likely to weaken over time, due to the progressive evolution of the sulfides under the effect of different stresses encountered, especially thermal and / or mechanical. In addition, the presence of moisture in the tires plays an important role in accelerating the degradation process above.

  Finally, the use of cobalt salt renders the rubber compositions more susceptible to oxidation and significantly increases the cost thereof.

  To overcome these disadvantages of brass, have been proposed new adhesive interphases likely to improve the overall performance in adhesion of metal / rubber composites used in tires. Application W002 / 10265, in particular, describes such composites whose adhesive interphase (metal / rubber) comprises an intermediate metal layer carrying oxides or hydroxides of aluminum, itself covered with an organosilane film. providing as a coupling agent the bond between metal and rubber. 45 P101532 / MICH Compared with conventional brass-reinforced composites, the composites described in this application W002 / 10265 are characterized by a metal-rubber adhesive interphase providing an initial adhesion level at least as good, with significantly improved performances after aging. wet and / or corrosive type. The longevity of the tires is thus substantially improved, in particular that of tires for industrial vehicles usually comprising metal carcass reinforcements subjected to particularly severe driving conditions, especially in a humid and corrosive atmosphere.

  Continuing its research, the Applicant has found a new composite (metal / rubber) which, thanks to a particular adhesive interphase, is also likely to constitute a substitution solution to conventional composites using brass.

  Accordingly, a first object of the invention is a composite (metal / rubber) comprising a matrix of diene elastomer reinforced by a metal reinforcement adhered to the elastomer matrix via an adhesive interphase, said interphase adhesive being based on at least one coupling agent comprising on the one hand at least one function "X" graftable on the diene elastomer, and on the other hand at least one function "Y" graftable on the metal body, characterized in that said function Y corresponds to the formula (1) -P (Q) R '. (OR) 2-.

  in which - P represents phosphorus; Q represents oxygen or sulfur; R 'represents a monovalent hydrocarbon group; n is 0 or 1; the symbols R, which are identical or different if n is equal to 0, each represent a monovalent hydrocarbon group, hydrogen or an alkali metal chosen from Na and K. The invention also relates to the use of such a composite for the manufacture or reinforcement of ground connection systems of motor vehicles, such as pneumatic, internal safety support for tire, wheel, rubber spring, elastomeric joint, other suspension and anti-vibration element, or semifinished products made of rubber intended for such ground connection systems.

  The composite according to the invention is particularly intended for reinforcements for reinforcing the crown, the carcass or the bead zone of tires intended for tourism vehicles or industrial vehicles chosen from light trucks, "heavy vehicles" - ie, metro, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles -, agricultural or engineering machinery, aircraft, other transport or handling vehicles. It is more advantageously used in carcass reinforcement tires for industrial vehicles such as vans or HGVs, as well as in the crown fittings of tires for both passenger vehicles and industrial vehicles.

  The invention further relates to the ground connection systems and the semi-finished rubber products themselves, when they comprise a composite according to the invention.

  The invention shows in particular all its interest in the carcass reinforcement of the tires for heavy goods vehicles which are expected today, thanks to the technical progress of retreading, that they are capable of enduring more than one million kilometers.

  The invention also relates, per se, to a metal reinforcement covered with an adhesive layer capable of adhering to a rubber matrix based on diene elastomer, said adhesive layer being based on at least one coupling agent comprising on the one hand at least one function "X" graftable on the diene elastomer and on the other hand at least one function "Y" graftable on the metal body, characterized in that said function Y corresponds to the formula (I) above .

  The invention as well as its advantages will be readily understood in the light of the description and the following exemplary embodiments, as well as the schematic figure relating to these examples, which represents a radial section of a carcass reinforcement truck tire. radial.

  I. DETAILED DESCRIPTION OF THE INVENTION

  The composites (metal / rubber) according to the invention consist of a rubber matrix reinforced with a metal body. The adhesive interphase (metal-rubber) is based on at least one phosphorus coupling agent comprising on the one hand at least one function "X" graftable on the diene elastomer, and on the other hand at least one function " Y "graftable on the metal body and corresponding to the formula (1) above. By the term "interphase-based", it is of course necessary to include an interphase comprising said coupling agent or its reaction product in situ (ie, in the composite), its functions X and Y being indeed capable of or intended to react at least partly with metal and rubber, during the different phases of manufacture of the composites, in particular during their vulcanization.

  In the present description, unless expressly indicated otherwise, all percentages (%) indicated are% by weight.

  1-1. Matrix of Rubber The matrix is a rubber composition based (ie, formed) of at least one diene elastomer and comprising, in addition to this diene elastomer, all the usual ingredients such as reinforcing filler, crosslinking system and other additives for use in rubber compositions for ground-engaging systems of motor vehicles such as tires, or semi-finished rubber products for such ground-binding systems.

  A) diene elastomer P10-1532! MICH "Diene" elastomer means in known manner an elastomer derived at least in part (ie a homopolymer or a copolymer) from monomers dienes that is to say from monomers carrying two carbon-carbon double bonds, conjugated or not.

  In general, the term "diene elastomer" is used herein to mean a diene elastomer derived at least in part from conjugated diene monomers having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (%). in moles). Thus, for example, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be referred to as "essentially" diene elastomers. saturated "(rate of low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

  Given these definitions, the elastomer of the composite according to the invention may be any diene elastomer, it being understood that the latter is preferably chosen from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes and the various copolymers. butadiene, the various isoprene copolymers, and mixtures of these elastomers.

  Particularly suitable polybutadienes are those having a 1,2-unit content of between 4% and 80% or those having a cis-1,4 content of greater than 80%. Of the synthetic polyisoprenes, cis-1,4-polyisoprenes are preferred, preferably those having a cis-1,4 bond ratio of greater than 90%. Among the copolymers of butadiene or isoprene, is meant in particular the copolymers obtained by copolymerization of at least one of these two monomers with one or more vinyl-aromatic compounds having from 8 to 20 carbon atoms. Suitable vinyl aromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the commercial mixture "vinyltoluene", para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene. The copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinyl aromatic units. Among the butadiene or isoprene copolymers above, preferably butadiene-styrene copolymers, isoprene-butadiene copolymers, isoprene-styrene copolymers or isoprene-butadiene-styrene copolymers are preferred.

  In summary, a diene elastomer selected from the group consisting of polybutadienes (BR), natural rubber (NR), synthetic polyisoprenes (IR), butadiene-styrene copolymers (SBR), isoprene copolymers is preferably used. butadiene (BIR), isoprene-styrene copolymers (SIR), butadiene-styrene-isoprene copolymers (SBIR) and mixtures of these elastomers.

  The composites in accordance with the invention are preferentially intended for tires, in particular for carcass reinforcement of tires for industrial vehicles such as P10-1532 / MICH vans or HGVs, as well as for crown fittings of tires intended both for passenger vehicles than industrial vehicles.

  It is then preferred to use matrices based on natural rubber or synthetic polyisoprene. By this is meant rubber matrices in which the diene elastomer is predominantly (i.e., greater than 50% by weight) made of natural rubber, synthetic polyisoprene or a mixture of these elastomers. Advantageously, the diene elastomer consists exclusively of natural rubber, synthetic polyisoprene or a mixture of these elastomers.

  But it is also possible to use, according to another advantageous embodiment of the invention, blends (blends) of these polyisoprenes with other highly unsaturated diene elastomers, in particular with SBR or BR elastomers as mentioned above.

  The rubber matrices of the composites of the invention may contain one or more elastomer (s) diene (s), which (s) last (s) may (s) used in combination with any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers.

  B) Other constituents The rubber matrices of the composites according to the invention also comprise all or part of the additives normally used in rubber matrices intended for the manufacture of ground connection systems of motor vehicles such as tires, such as for example, reinforcing fillers such as carbon black or silica, anti-aging agents, antioxidants, extender oils, plasticizers or agents facilitating the use of the compositions in the green state, a system of crosslinking based on either sulfur, or sulfur and / or peroxide donors, accelerators, vulcanization activators or retarders, methylene acceptors and donors, resins, known adhesion promoter systems of the "RFS" type "(resorcinol-formaldehyde-silica) or metal salts, especially cobalt salts.

  If the chosen phosphorus coupling agent comprises, for example, as function X, an amine function, the rubber composition may advantageously contain a reinforcing resin in order to ensure the connection between the coupling agent and the composition. rubber itself, through this reinforcing resin, the latter can be obtained in situ, during the baking of the rubber composition. The composition then contains, before cooking, the basic constituents of this resin, for example a methylene acceptor such as resorcinol and a methylene donor (curing agent) 40 such as hexamethylenetetramine ("HMT") or else hexamethoxy methylmelamine ("HMMM", still denoted "H3M").

  If the chosen phosphorus coupling agent comprises, for example, as a function X, a mercapto, polysulphide, azide, alkene or activated alkene function, the composition may then contain a simple crosslinking system (for example sulfur, an accelerator of PIO-1532 / MICH vulcanization, a peroxide), the functionalized coupling agent then reacts directly with the rubber during vulcanization.

  To further enhance the performance of the composite of the invention, a particularly preferred embodiment of the invention is to incorporate, to the rubber matrices, a bismaleimide compound. This type of compound, usable without hardener, has a cooking kinetics well adapted to that of tires, it is likely to activate the kinetics of adhesion and further improve, in the composites according to the invention, the endurance in wet aging conditions of adhesive interphases. It will be recalled that the bismaleimides, in a known manner, correspond to the following formula:

O O

N-R '-N

O O

  in which R "is a substituted or unsubstituted hydrocarbon, aromatic or aliphatic, cyclic or acyclic radical, such a radical possibly containing a heteroatom chosen from O, N and S, this radical R" preferably comprises from 2 to 24 carbon atoms, carbon.

  More preferably, a bismaleimide selected from the group consisting of N, N'-ethylene-bismaleimides, N, N'-hexamethylene-bismaleimides, N, N '- (m-phenylene) bismaleimides, N, N' - (pphenylene) is used. ) -bismaleimides, N, N '- (p-tolylene) -bismaleimides, N, N' (methylenedi-p-phenylene) -bismaleimides, N, N '- (oxydi-p-phenylene) bismaleimides and mixtures thereof compounds. Such bismaleimides are well known to those skilled in the art and have been described for example in FR-A-2,611,209 or US-A-4,818,601, EP-A-0 345 825 or US-A-4,803. 250, EP-A-0 564 966, US-A-5,300,585.

  In the case where a reinforcing resin or a bismaleimide is used, it is present in the composite of the invention at a preferential rate of between 0.1 and 20%, more preferably between 1 and 8% by weight of rubber composition. For rates above the maximum values indicated, there is more or less the risk of excessive stiffening of the compositions, and thus of embrittlement of the composites; for rates below the indicated minima, the intended technical effect may be insufficient.

  I-2. Metal reinforcement By "body" or "reinforcement" is meant here, in a known manner, any reinforcing element capable of reinforcing the rubber matrix. This reinforcement can be in various forms, preferably in the form of a wire (monofilament), a film (for example a strip or a tape) or a son assembly, these wires are twisted between them ( for example, in the form of a cable) or substantially parallel to each other (for example in the form of a son packet, a continuous fiber or a set of short fibers).

  P10-1532 / MICH In the composites and tires of the invention, this reinforcement is more preferably in the form of a unitary yarn or a son assembly, for example a cable or a strand made with devices and methods of wiring or stranding known to those skilled in the art, which are not described here for the simplicity of the presentation.

  "Metal" reinforcement means any reinforcement, whether it is entirely metallic or not, of which at least the surface or external part intended to come into contact with the rubber, is made of metal.

  The metal, or surface metal where appropriate, of the metal reinforcement is preferably selected from Fe, Cu, Zn, Al, Sn, Ni, Co, Cr, Mn, the oxides, hydroxides and alloys of these elements, more preferably from Fe, Cu, Zn, Al, Sn, their oxides, hydroxides and alloys.

  The invention is preferably implemented with a reinforcement made of steel, in particular of carbon perlitic (or ferrito-pearlitic) steel, hereinafter referred to as "carbon steel", or else of stainless steel (by definition, steel comprising at least 11% of chromium and at least 50% of iron) as described for example in the applications EP-A-648 891 or WO98 / 41682.

  But it is of course possible to use other steels or other alloys.

  When a carbon steel is used, its carbon content is preferably between 0.35% and 1.2%, especially between 0.5% and 1.1% (% by weight of steel); it is more preferentially between 0.6% and 1.0%, even more preferentially between 0.68% and 0.95%; these levels represent a good compromise between the mechanical properties required for the tire and the feasibility of the wires. It should be noted that in the applications where the highest mechanical strengths are not necessary, advantageously carbon steels having a carbon content of between 0.50% and 0.68% may be used. 55% to 0.60%, such steels being ultimately less expensive because easier to draw.

  The person skilled in the art knows how to adapt the composition of the steel according to his own particular needs, for example by using microalloyed carbon steels containing specific addition elements such as Cr, Ni, Co, V, or various other known elements (see, for example, Research Disclosure 34984 - "Micro-alloyed steel cord constructions for tires" - May 1993, Research Disclosure 34054 - "High tensile strength steel cord constructions for 35 tires" -August 1992).

  As indicated above, the metal or steel used, whether in particular carbon steel or stainless steel, may itself be coated with an intermediate metal layer improving for example the properties implementation of the metal reinforcement 40 and / or its constituent elements, or the properties of use of the reinforcement and / or the composite themselves such as adhesion properties, corrosion resistance or resistance to aging.

  According to a preferred embodiment, the steel used is covered with an intermediate layer 45 of aluminum, zinc, copper, oxide and / or hydroxide or an alloy of these elements.

  P10-1532 / MICH Among the aluminum alloys, those preferably selected from the AI-Mg, Al-Cu, Al-Ni, Al-Zn binary alloys and the ternary alloys of Al and two of the Mg elements are preferably used. Cu, Ni, Zn, more particularly an Al-Zn alloy.

  Among the zinc alloys, those selected from ZnCu, Zn-Al, Zn-Mg, Zn-Co, Zn-Mo, Zn-Fe, Zn-Ni, ZnSn and the ternary alloys of Zn and Zn are preferably used. two of the elements (for example Zn-Cu-Ni or Zn-Cu-Co), more particularly a Zn-Cu alloy (brass) or a Zn-Al alloy as mentioned above. Of the copper alloys, the preferred binary alloys are those of Cu-Zn (above-mentioned brass) and Cu-Sn (bronze).

  Furthermore, oxides and / or hydroxides of aluminum which can be used have for example been described in the above-mentioned application W002 / 10265, in particular aluminas A1203, aluminum hydroxides [Al (OH) a Ob with 0 <a <3 and b = (3-a) / 2], aluminum trihydroxides Al (OH) 3, and any mixture of such oxides or hydroxides. Among the oxides and / or hydroxides of zinc, there will be mentioned in particular ZnO and Zn (OH) 2. Oxides and / or hydroxides of iron may also be considered, such as Fe 2 O 3, Fe 3 O 4 and FeO (OH). When an intermediate metal layer is deposited on the metal reinforcement or on the individual elements constituting this reinforcement, in particular when it is an assembly, it is possible to use any deposition method capable of applying, continuously or discontinuously, a metal coating on a metal substrate. For example, a simple steeping technique is used in a bath containing the metal or alloy in the liquid state, an electrolytic deposition technique, or even by spraying.

  In the most frequent case where the reinforcement used is a cable consisting of fine wires, the intermediate metal layer will preferably be deposited on the wires, and not on the final cable. In such a case, in particular to facilitate the drawing operations, the deposit will advantageously be made on a so-called "intermediate" diameter wire, for example of the order of a millimeter, at the outlet of the last heat treatment (patenting) preceding the wet final drawing step for obtaining the fine wire having the final target diameter.

  When the composites of the invention are used to reinforce carcass reinforcement or crown reinforcement of radial tires, the reinforcements used are preferably assemblies (strands or cables) of fine carbon steel or stainless steel wires having: tensile strength greater than 2000 MPa, more preferably greater than 2500 MPa, in particular greater than 3000 MPa; the person skilled in the art knows how to manufacture fine threads having such strength, by adjusting in particular the composition of the steel and the final work hardening rates of these threads; - For a good compromise between strength / flexural strength / feasibility, a diameter 4 between 0.12 and 0.40 mm, more preferably within a range of 45 from 0.15 to 0.26 mm when the composite is intended to reinforce a P10-1532 / MICH carcass reinforcement, in a range from 0.20 to 0.35 mm when the composite is intended to reinforce a crown reinforcement.

  When the composites of the invention are used to reinforce tire bead zones, the reinforcements may be in particular in the form of rods consisting of carbon steel or stainless steel son, unitary or assembled, these son having: a tensile strength greater than 1500 MPa, more preferably greater than 2000 MPa; - A diameter 1 (or a characteristic dimension, if it is a wire other than cylindrical) between 0.5 and 3 mm, more preferably between 0.8 and 2.2 mm.

  1-3. Phosphorus coupling agent It is recalled here that, by "metal-rubber coupling agent", is meant in known manner an agent capable of establishing a sufficient connection, of a chemical and / or physical nature, between the metal and the rubber. Such a coupling agent, therefore at least bifunctional, has for example as simplified general formula "YTX", in which: Y represents a functional group ("Y" function) which is capable of binding physically and / or chemically to the surface metal of the metal reinforcement considered; X represents a functional group ("X" function) capable of binding physically and / or chemically to the rubber composition, for example to the diene elastomer via a sulfur atom; T represents a divalent group making it possible to connect Y and X. As indicated above, the polyfunctional coupling agents intended for the composites of the invention have the essential characteristic of comprising, as function Y, a phosphorus functional group corresponding to the formula (I) which follows -P (Q) R ', (OR) 2-n in which - P represents (in accordance with the nomenclature) a phosphorus atom; Q represents an oxygen or sulfur atom; R 'represents a monovalent hydrocarbon group; - is equal to 0 or 1; the symbols R, which are identical or different if n is equal to 0, each represent a monovalent hydrocarbon group, hydrogen or an alkali metal chosen from Na and K. In formula (1) above, the following preferred characteristics are - R 'is selected from linear or branched C 1 -C 8 alkyls, C 6 -C 10 cycloalkyls, C 6 -C 8 aryls and (C 6 -C 8) aryl (C 1 -C 8) alkyls; R 10 is chosen from linear or branched C 1 -C 8 alkyls, C 6 -C 8 cycloalkyls, C 6 -C 18 aryls and (C 6 -C 8) aryl- ( C1-C6) alkyl, hydrogen or an alkali metal selected from Na and K. More preferably, R 'is selected from alkyl, linear or branched, C1-C8; R is chosen from alkyls, linear or branched, having from 1 to 6 carbon atoms and the phenyl radical, in particular from methyl, ethyl, propyl and isopropyl.

  On the other hand, preferably, at least one, more preferably, the following two characteristics are satisfied: n is zero; Q represents oxygen.

  As for the functional group X, it will be understood by those skilled in the art that a large number of functions are potentially usable, preferably chosen from the group consisting of the amine (for example amino, azide, ureido) and sulfur functional groups (for example mercapto, Polysulfide, episulfide, thiosulfinate, sulfenamide), oxygenated (for example epoxy, in particular glycidoxy), activated or non-activated alkenyls (for example vinyl, styryl, acryloxy, acrylamido, methacryloxy, methacrylamido, maleimido, citraconimido, acid or maleamic ester).

  According to a particularly preferred embodiment of the invention, a polysulfide coupling agent of formula (II) below is used: (RO) 2 (Q) P - (Z) y - S x - (Z) y - P (Q) (OR) 2 in which: the symbols Q, identical or different, represent an oxygen or sulfur atom; the symbols Z, which are identical or different, are divalent linking groups comprising from 1 to 18 carbon atoms; each y is equal to 0 or 1 (both of which may be different from each other); x is an integer or fractional number, preferably in a range of 2 to 8, more preferably in a range from 2 to 5.

  Preferably, Q is oxygen and each y is 1, that is, there is a Z spacer between the polysulfide group S x and each phosphorus functional group. The Z chains may comprise or be interrupted by a heteroatom such as, for example, S, O or N. Z is preferably a C 1 -C 6 alkylene group, more preferably a C 1 -C 4 alkylene group.

  Compounds of formula (II) above are known as well as their methods of synthesis; they have been described, for example, in GB-A-1 189 304 as lubricating additives.

  They can be prepared according to methods known to those skilled in the art, for example those for which Q = oxygen, by reaction of a hydrocarbon dihalide with a trialkyl phosphite to intermediately form the corresponding halogenated dialkylphosphonate. Sulfurization of the latter with an alkali metal polysulfide followed by oxidation leads to the compound (II) of the polysulfide type.

  As preferred examples of polysulfides corresponding to formula (II) supra, mention will in particular be made of polysulfides of particular formulas (III) to (V) hereinafter (EtO) 2 P (CH 2) 4 -Sx - (CH 2) 4 P (OEt) 2 (III) (HO) 2 P- (CH 2) 4 S x (CH 2) 4 P (OH) 2 (IV) (NaO) 2 P- (CH 2) 4 -Sx (CH 2) ) 4 P (ONa) 2 (V) for which, therefore: - Q = O (oxygen); y =; Z (CH 2) 4 (butylene); - R = Et (ethyl), H or Na - x is in a range from 2 to 8, preferably from 2 to 5. In formula (II) above (and more particularly in formulas (III) at (V) above), in the case where the synthesis route of the compound in question can give rise to only one kind of polysulphurized group, the number x is then an integer, preferably within a range from 2 to 8, more preferably from 2 to 5; this is the case for example disulfide compounds (x = 2) or tetrasulfides (x = 4).

  However, those skilled in the art will readily understand that this number may be a fractional average number when the synthesis route gives rise to a mixture of polysulfide groups each having a different number of sulfur atoms; in such a case, the synthesized polysulfide group is in fact constituted by a distribution of polysulfides, ranging for example from disulfide S2 to heavier polysulphides, centered on a mean value (in mole) of "x" (fractional number) between 2 and 8, more preferably between 2 and 5.

  I-4. Treatment of the metal reinforcement with the phosphorus coupling agent The phosphorus coupling agent is preferably deposited directly on the surface of the metal reinforcement used. This deposition can be carried out by any known method, batchwise or continuous PIO-1532 / MICH-12, for example by application with a brush, by dipping, by spraying, the coupling agent being used pure or diluted in a solvent such as toluene.

  If the selected coupling agent is used in solution, for example in toluene, the concentration of the coupling agent in the solution is preferably between 0.001% and 15%, more preferably between 0.001% and 5%. .

  Prior to contact with the coupling agent, the surface of the metal reinforcement may be previously cleaned and / or activated in various ways known in the art, for example by washing with hot water, treatment with an acidic aqueous solution or basic, with optional rinsing and drying steps, or by plasma treatment.

  As an indication, the layer of coupling agent thus deposited is preferably less than 50 mg, more preferably less than 5 mg of phosphorus coupling agent per 100 g of reinforcement, which is equivalent to a thickness generally of 10 and 100 nm (nanometers), depending on the type of process used for the deposition.

  After the application of the coupling agent, the surface of the reinforcement may be dried, for example in ambient air, or preferably heat-treated, by heating in an oven or in a tunnel, the heating being for example obtained by conduction in contact with hot gas, or electrically, in particular by Joule effect or by induction. This heat treatment allows the departure of the solvent or solvents, as well as the reaction, partial or total depending on the intensity of the treatment, the phosphorus coupling agent with the metal surface. I-5. Composite of the invention The metal reinforcement thus prepared can be brought into direct contact with the rubber composition, in order to manufacture the composite of the invention. This composite can be in various forms, for example in the form of a web, band, strip or block of rubber in which is incorporated the metal reinforcement using various known means of those skilled in the art, such as, for example, molding, calendering or coiling means. Of course, the invention relates to composites in the green (i.e., before firing or crosslinking) as in the fired state (i.e., after crosslinking). In this composite, the final adhesion between the metal and the rubber composition, via the adhesive interphase, is obtained at the end of the firing of the finished article, for example the tire, comprising the composite. Preferably, this cooking is operated under pressure.

  The composites according to the invention are preferably intended for tires, in particular for radial tires to form all or part of the crown reinforcement, of the carcass reinforcement or the reinforcement of the bead zone of such tires. By way of example, the appended FIGURE schematically represents a radial section of a heavy-weight tire 1 with a radial carcass reinforcement which may or may not conform to the invention, in this representation. General. This tire 1 comprises an apex 2, two flanks 3, two beads 4, a carcass reinforcement 7 extending from one bead to the other. The top 2, surmounted by a tread (not shown in this schematic figure, for simplification), is in a manner known per se reinforced by a crown reinforcement 6 constituted for example by at least two superimposed crossed vertex plies (plies so-called "working" top), optionally covered with at least one protective crown ply, all these plies being able to be reinforced by metal ropes. The carcass reinforcement 7 is wound around the two rods 5 in each bead 4, the upturn 8 of this armature 7 being for example disposed towards the outside of the tire 1 which is shown here mounted on its rim 9. The armature of carcass 7 consists of at least one sheet reinforced by so-called "radial" metal cables, that is to say that these cables are arranged substantially parallel to each other and extend from a bead to 15 l other so as to form an angle between 800 and 900 with the median circumferential plane (plane perpendicular to the axis of rotation of the tire which is located halfway between the two beads 4 and passes through the middle of the frame of summit 6).

  The tire according to the invention has the essential feature of comprising in its structure at least one composite (metal / rubber) according to the invention, this composite being, for example, a part of the bead zone 4 comprising the bead wire. 5, a crossed crown ply or a protective ply of the crown reinforcement 6, a ply forming all or part of the carcass reinforcement 7.

  As indicated above, the composite of the invention is advantageously usable for constituting a carcass reinforcement ply 7 of a tire for an industrial vehicle such as heavy vehicle. Preferably, in such a case, its rubber composition has, in the vulcanized state (ie, after firing), a secant modulus in extension at 10% elongation (denoted "El 0") which is less than 9 MPa. more preferably between 4 and 9 MPa. However, the composite of the invention may have an equally advantageous use in the crown reinforcement of all types of tires, for example for passenger vehicles, vans or heavy vehicles. Preferably, in such a case, its rubber composition has in the vulcanized state a modulus E10 which is greater than 9 MPa, more preferably between 9 and 20 MPa.

  II. EXAMPLES OF CARRYING OUT THE INVENTION 11-1. Dynamometric measurements For metal reinforcements (wire or cable), fracture force measurements denoted Fm (maximum load in N), tensile strengths Rm (in MPa) and elongation at break 45 At (total elongation in%) are made in tension according to ISO 6892 of 1984. For rubber compositions, the module P10-1532 / MICH measurements are made in tension, unless otherwise specified according to ASTM standard. D 412 of 1998 (specimen "C"): one measures in second elongation (that is to say after a cycle of accommodation) the true secants modules that is to say brought back to the real section of the test tube at 10% elongation, denoted ElO and expressed in MPa (normal temperature and humidity conditions according to ASTM D 1349 of 1999).

  11-2. Nature and properties of the reinforcements used For the production of examples of composites in accordance with the invention, it is possible to use, as metal reinforcements, cables consisting of thin carbon steel wires, coated or uncoated, suitable for reinforcing the carcass reinforcements of heavy-duty tires or touring tire crown reinforcement, ie large-diameter elementary wires that can be used for reinforcing low tire areas, particularly in the form of rods.

  The fine carbon steel wires are prepared starting from, for example, machine wires (diameter 5 to 6 mm) that are first cold-worked by rolling and / or drawing to an intermediate diameter of about 1 mm. or starting directly from commercial intermediate threads whose diameter is close to 1 mm. The steel used is a known carbon steel, for example of the USA AISI 1069 type whose carbon content is about 0.7%, comprising 0.5% manganese and about 0.2% silicon, the rest consisting of iron and the usual unavoidable impurities associated with the steelmaking process. The intermediate diameter son then undergo a degreasing treatment and / or pickling, before further processing. After optional depositing of a metal coating on these intermediate wires (for example, brass, zinc or aluminum alloy), a "final" work hardening is carried out on each wire (ie, carried out after the last heat treatment of patenting), by cold drawing in a wet medium with a drawing lubricant which is, for example, in the form of an aqueous emulsion.

  The cables used are for example layered cables of known construction [3 + 9], fretted, formed of 12 wires of diameter equal to about 0.225 mm (Fm = 131 daN, Rm = 2685 MPa, At = 2.75%) . These cables comprise a core of 3 wires wound together in a helix (direction S) in a pitch of 6.3 mm, this core being in contact with an outer layer of 9 wires themselves wound together in a helix (direction S) around 12.5 mm pitch, the whole being shrunk by a 0.15 mm shrinkwire at a pitch of 3.5 mm (Z direction). Other cables used are, for example, stranded cables of known construction [3 × 2], not fretted, formed of 6 wires of diameter equal to about 0.225 mm (Fm = 66 daN, Rm = 2700 MPa, At = 2.7% ); these cables comprise three strands wound together in a helix (direction S) in a pitch of 12.5 mm, each strand consisting of two wires themselves wound together in a helix (direction Z) in the same pitch of 12.5 mm.

  In these cables, each carbon steel wire may be either "clear" steel (that is to say uncoated), or coated with an aluminum-zinc alloy interlayer (about 5% by weight aluminum), or a flash of zinc. The thickness of the coating Al-Zn alloy, 45 deposited "dipped" before final wet drawing, is of the order of one micrometer after wire drawing (about 1.6 g of aluminum alloy per 100 g of wire ). The thickness of the zinc flash, electrolytically deposited before final wet drawing, is of the order of 0.002 μm after drawing (ie about 4 mg of zinc per 100 g of wire).

  II-3. Phosphorus Coupling Agent The coupling agent used is a bis (butyldiethylphosphonate) polysulfide having the above-mentioned formula (III) (EtO) 2 P - (CH 2) 4 -Sx (CH 2) 4 P (OEt) 2 This coupling agent was obtained in two steps: an Arbusov reaction to obtain bromobutyldiethylphosphonate, followed by a sulfurization reaction, as indicated in the reaction scheme below (Et = ethyl) P (OEt) 3 Br (CH 2) 4 Br. (EtO) 2 P - (CH 2) 4 - Br Na 2 S x (Na 2 S · 9H 2 O + S 8) H 2 O + NaCl Toluene

TBAB

  EtO 2 P - (CH 2) 4 - S x (CH 2) 4 - P (OEt) 2 A) Synthesis of 4-bromobutyldiethylphosphonate: In a 100 mL tricol equipped with a magnetized bar and a ascending refrigerant, 26.98 g (0.125 mol) of 1,4-dibromobutane was introduced. The mixture is brought to 90 ° C. before starting the addition of triethyl phosphite (8.31 g, 0.05 mol). Temperature and stirring are maintained for 24 hours (monitoring by gas chromatography makes it possible to control the progress of the reaction). The mixture is distilled under vacuum in a bulb oven (1.7 mm Hg, 65 ° C.). 10.61 g of product are thus collected. B) Synthesis of bis (butyldiethylphosphonate) polysulfide: In a second step, the target polysulfide is formed by the action of sodium polysulfide generated in situ with 4-bromobutyldiethylphosphonate, using a known technique of phase transfer catalysis ( see for example US 5,468,893).

  In a three-neck topped with a condenser is introduced 0.51 g (15.7 mmol) of sulfur and 1.27 g (5.3 mmol) of Na2S (taken under Argon) to which are added 8 ml of saturated water in NaCl and P10-1532 / ml - 3 ml of toluene. The solution is heated to 80 ° C. The yellow reaction medium first turns red, then a solution containing 90 mg of TBAB (tetrabutylammonium bromide), 2.80 g of 4-bromobutyldiethylphosphonate (10 mmol) and 3 ml of toluene is added dropwise. The initially red aqueous phase is discolored in favor of the colorless toluene phase, which becomes yellow. The toluene phase is isolated and the aqueous phase is extracted with toluene. The organic phases are joined and concentrated.

  2.44 g of product of formula (III) above is thus obtained, as attested by NMR analysis (yield 92%). This product actually consists of a polysulfide distribution, ranging essentially from disulfide (x = 2) to hexasulfide (x = 6), centered on an average value of x which is close to 4.

  It will be understood that modified synthesis conditions would make it possible to obtain other polysulfide distributions, with average values of x variables but preferably of between 2 and 8, more preferably of between 2 and 5.

  II-4. Treatment of the cables For the treatment of the cables by this coupling agent, the procedure is as follows: the reinforcement is first treated by passing through a bath of hot water at 60 ° C., the residence time being about 10 s; in the case of Zn-flashed clear steel, this step is preceded by 10 s pickling in an acid bath at 60 ° C. (Condat's "Allmet" degreaser product, diluted to 10% in water ). Then, the reinforcement is sent to the bath of phosphorus coupling agent at 20 ° C. containing, depending on the case, 0.01 or 0.05 mol of phosphorus coupling agent diluted in toluene (residence time: 5 or 15 hours). min, depending on the case). After application of the coupling agent, the surface of the reinforcement is dried by passing through a heating oven at a temperature of 100 ° C. for 60 seconds. An ultra-thin phosphor coupling agent film estimated at less than 5 mg of coupling agent per 100 g of reinforcement is thus targeted.

  11-5. Composites and tires of the invention For the manufacture of the composites and tires of the invention, the previously described cables of construction [3x2] are incorporated by calendering with a rubberized fabric formed of a known composition based on natural rubber and black of carbon as a reinforcing filler, conventionally used for the manufacture of crown reinforcement plies for radial tires (ElO modulus equal to about 18 MPa, after firing).

  This composition essentially comprises, in addition to the elastomer and the reinforcing filler, an antioxidant, stearic acid, a reinforcing resin (phenolic resin plus methylene donor), cobalt naphthenate as adhesion promoter, and finally a vulcanization system (sulfur, accelerator, ZnO). In the rubber fabric, the cables are arranged parallel in a known manner, according to a determined cable density, for example about 70 cables per dm of web, which, given the diameter of the cables, equals a width of the bridges. of rubber, between two adjacent cables, about 0.65 mm.

  Those of construction [3 + 9] are used to reinforce another fabric formed of a similar rubber matrix, based on natural rubber and carbon black, used conventionally for the manufacture of polyester webs. carcass reinforcement of radial tires of heavy-weight type (ElO module equal to about 6 MPa, after cooking). In this other fabric, the cables are arranged in parallel according to a cable density of about 60 cables per dm of web (width of the rubber bridges of about 0.5 mm).

  The tires, manufactured in known manner, are as schematized in the appended figure, already commented. Their radial carcass reinforcement 7 consists of a single radial ply formed of the previously described rubberized fabric according to the invention, comprising the metal cables [3 + 9] arranged at an angle of about 900 with the median circumferential plane. As for the crown reinforcement 6, it consists of (i) two crossed superimposed working plies, reinforced with metal cables inclined by 22 degrees, these two working plies being covered by (ii) a protective top ply reinforced with conventional elastic metal cables tilted 22 degrees. Each of the two working plies is formed from the previously described rubberized fabric or composite according to the invention, reinforced by the [3 × 2] cables.

PIO-1532 / MICH - 18

Claims (31)

  1. Composite (metal / rubber) comprising a matrix of diene elastomer reinforced by a metal reinforcement adhered to the elastomer matrix via an adhesive interphase, said adhesive interphase being based on at least one adhesive agent coupling comprising on the one hand at least one function "X" graftable on the diene elastomer, and on the other hand at least one function "Y" graftable on the metal body, 10 characterized in that said function Y corresponds to the formula (I): -P (Q) R '(OR) 2-n in which: - P represents phosphorus; Q represents oxygen or sulfur; R 'represents a monovalent hydrocarbon group; - is uneven in Seoul; the symbols R, which are identical or different if n is equal to 0, each represent a monovalent hydrocarbon group, hydrogen or an alkali metal chosen from Na and K. 2. The composite according to claim 1, wherein the following characteristics are satisfied: R 'is chosen from linear or branched C1-C8 alkyls, CsC10 cycloalkyls, C6-C18 aryls and (C6-C18) aryl (1-6C) alkyls; - R is chosen from linear or branched alkyls, CQ-Cs, CsC10 cycloalkyls, C6-C18 aryls, (C6-C18) aryl- (C1-Cs) alkyls, hydrogen or a metal; Alkali selected from Na and K. 3. Composite according to claims 1 or 2, n being equal to zero and Q representing oxygen.   4. Composite according to any one of claims 1 to 3, the diene elastomer being selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers and blends. of these elastomers.   5. Composite according to any one of claims 1 to 4, the surface metal of the metal body being selected from Fe, Cu, Zn, Al, Ni, Co, Cr, Mn, Sn, the oxides, hydroxides and alloys thereof. elements.   6. Composite according to claim 5, the surface metal being selected from Fe, Cu, Zn, Al, Sn, the oxides, hydroxides and alloys of these elements.   P 10-1532 / MICH - 19 7. Composite according to any one of claims 1 to 6, the coupling agent being a polysulfide of formula (II): (RO) 2 (Q) P - (Z) y -S- (Z) y-P (Q) (OR) 2 in which - the symbols Q, identical or different, represent oxygen or sulfur, preferably oxygen; the symbols Z, which are identical or different, are divalent linking groups comprising from 1 to 18 carbon atoms; each y is 0 or 1, preferably 1.   x is an integer or fractional number, preferably in a range from 2 to 8.   8. A composite as claimed in any one of claims 1 to 7 wherein R is selected from linear or branched alkyls having from 1 to 6 carbon atoms and the phenyl radical.   9. Composite according to claims 7 or 8, Z being a C1-C8 alkylene group, preferably C1-C4 alkylene.   10. Composite according to any one of claims 5 to 9, the diene elastomer being selected from the group consisting of natural rubber, synthetic polyisoprenes, isoprene copolymers and mixtures of these elastomers.   11. The composite of claim 10 wherein the diene elastomer is natural rubber.   12. Composite according to any one of claims 7 to 11, the metal of the metal body being steel, preferably a carbon steel or a stainless steel.   13. Composite according to claim 12, the steel being a stainless steel.   14. Composite according to claim 12, the steel being a carbon steel.   15. The composite according to claim 14, the carbon steel having a carbon content of between 0.35% and 1.20%, preferably between 0.5% and 1.1%.   16. Composite according to claims 12 or 13, the steel being covered with an intermediate layer of aluminum, zinc, or an alloy thereof.   17. Composite according to any one of claims 1 to 16, the metal body being selected from son, yarn assemblies and films.   18. Use of a composite according to any one of claims 1 to 17 for the manufacture or reinforcement of a motor vehicle ground connection system or a semi-finished rubber product intended for such a system. .   P1O-1532 / MICH - 20 19. Use according to claim 18, the ground connection system consisting of a tire.   20. Use according to claim 19 for the reinforcement of a crown reinforcement, carcass or the bead zone of a tire.   21. Use according to claim 20, for the reinforcement of a tire carcass reinforcement for a heavy vehicle.   lo A ground connection system or semi-finished rubber product incorporating a composite according to any one of claims 1 to 17.   23. Ground connection system according to claim 22, consisting of a tire.   24. The tire according to claim 23, the composite being present in the armature of the bead zone of the tire.   25. A tire according to claim 23, the composite being present in the carcass reinforcement of the tire.   Tire according to claim 25, the rubber composition of the composite having, in the vulcanized state, a secant modulus in extension, at 10% elongation, which is less than 9 MPa, preferably between 4 and 9 MPa. .   27. The tire according to claim 23, the composite being present in the crown reinforcement of the tire.   28. A tire according to claim 27, wherein the rubber composition of the composite has, in the vulcanized state, a secant modulus in extension, at 10% elongation, which is greater than 9 MPa, preferably 9 to 20 MPa.   29. Metal reinforcement covered with an adhesive layer capable of adhering to a rubber matrix based on diene elastomer, said adhesive layer being based on at least one coupling agent comprising on the one hand at least one function " X "35 graftable on the diene elastomer and secondly at least one function" Y "graftable on the metal body, characterized in that said function Y corresponds to the formula (1) - P (Q) R'n ( OR) 2n wherein - P represents phosphorus; Q represents oxygen or sulfur, preferably oxygen; R 'represents a monovalent hydrocarbon group; N is 0 or 1; P1O-1532 / MICH - 21 the symbols R, identical or different if n is equal to 0, each represent a monovalent hydrocarbon group, hydrogen or an alkali metal selected from Na and K. 30. Reinforcement according to claim 29, the coupling agent being a polysulfide of formula (II): (RO) 2 (Q) P - (Z) y -Sx (Z) y -P (Q) (OR) 2 in which: the symbols Q, identical or different, represent oxygen or sulfur, preferably oxygen; the symbols Z, which are identical or different, are divalent linking groups comprising from 1 to 18 carbon atoms; each y is equal to 0 or 1, preferably equal to 1.   x is an integer or fractional number, preferably in a range from 2 to 8.   31. Metal reinforcement according to claim 29 or 30, characterized in that it is selected from son, wire assemblies and films. 20 P10-1532 / MICH