Tire belt with anti-oxidant

FIELD: chemistry.

SUBSTANCE: the invention relates to car tires, to tire belt in particular. The tire belt contains a rubber composition based, at least, on a isoprene elastomer, reinforcing material, suturing system and anti-oxidant. The anti-oxidant contains 4,4'- bis(alkylamino)triphenylamine, corresponding to the formula: where R¹ and R² can be identical or different, each of them represents a branched or an unbranched alkyl residue comprising from 1 to 12 carbon atoms, or a cycloalkyl group comprising from 5 to 8 carbon atoms.

EFFECT: increases fatigue resistance and prevents crack formation in the tire belt.

15 cl, 2 dwg, 2 tbl, 2 ex

The present invention relates to tire and crown amplifiers zones of these tyres, also known as "breakers".

In the particular case of the invention relates to a diene elastomer compositions, which are used to form all or part of the rubber matrix such amplifiers, and also relates to antioxidants, which are used to protect against aging such compositions.

It should be recalled in a few words, the tire having a radial frame amplification, contains, in a sense, the protector, two off not stretched side, two sides, attaching the bead to the tread and breaker located perifericheskie between the frame amplifier and protector, this Brecker, consisting of different layers (or "layers") of rubber, which may or may not be reinforced with reinforcing elements (or amplifiers), such as cords or monofilaments, metal or textile type.

Main breaker bus consists of at least two superimposed upon each other strata or layers, sometimes known as a "working" layers or cross-linked layers, amplifiers that are substantially parallel to one another within the layer, but together, in other words, are either symmetrically or no to the median peripheral plane at an angle in the range of from 10° to 45°, in which depending on the bus type, we are talking about. Each of these two stitched layers consists of a rubber matrix in the General case, based on isoprene, well-known, in particular, as calendered rubber, which covers the amplifiers. Stitched layers can be supplemented with other various auxiliary rubber layers or layers having widths that vary depending on the case and which may contain or may not contain amplifiers; should be mentioned as an example of a simple rubber pads, layers, known as "protective" layers, whose role is to protect the support of the breaker from external influence, perforations, or layers, known as layers "ring fittings, including amplifiers, oriented essentially along the peripheral direction (layers, known as layers "zero degrees")either radially outward or radially inward, compared with crosslinked layers.

This Brecker tires must conform to, in a sense, numerous, sometimes contradictory requirements, in particular:

(i) to be as hard as it greatly improves the rigidity of the crown area of the tire;

(ii) to have as low as possible hysteresis that, on the one hand, minimizes overheating of the internal zone of the crown during the rotation, and on the other hand, will reduce the resistance the of rotation of the tire, which is synonymous with fuel economy; and

(iii) ultimately have considerable strength, in particular on the phenomenon of separation or rupture of the ends of the stitched layers in the "shoulder" area of the tire problem, which is known under the term "gap".

Under the third condition is especially required that the rubber compositions entered in the configuration of the breakers tires, had a very high resistance to cracking and thermal oxidation, which, in particular, achieved through the use of antioxidants that offer effective protection against aging.

This requirement, in particular, is especially significant for tires of heavy vehicles, which are designed to be able to re-process one or more times when the protectors they contain, had reached a critical degree of wear after a long run.

Antioxidants, which are used for a long time as connections, protects against aging, in rubber compositions for tires, especially in the breakers of such tires, belong to the family of derivatives of p-phenylenediamine (PPD), such as, for example, N-isopropyl-N'-phenyl-p-phenylenediamine (I-PPD) or N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6-PPD), which are both excellent antioxidants and antiozonants (motri, for example, applications WO 2004/033548, WO 2005/063510, WO 2005/133666).

Currently, the authors of the patent application in the course of the research revealed that the use of another antioxidant, which to date has not been used in the tires, makes possible a further increase in long-term fatigue strength and resistance to cracking breakers tires.

Therefore, the first object of the present invention relates to the tread of the tire containing the rubber composition based on at least one isopropanol the elastomer, a reinforcing filler, a binding system and antioxidant, characterized in that the above-mentioned antioxidant includes 4,4'-bis(alkylamino)triphenylamine corresponding to the formula (I)

in which R¹and R²which are identical or different, each denotes unbranched or branched alkyl group having from 1 to 12 carbon atoms, or a cyclic group having from 5 to 8 carbon atoms.

Thus, the invention provides amplification of the crown area of the tire and also these tires, a new and particularly favorable full compromise of properties.

The invention also relates to any bus that contains Brecker corresponding to the present invention, in particular, is whether the tire is of radial type or not radial.

Bus us Otsego of the invention, in particular, intended for equipment of motor vehicles of the following types: passenger vehicles, SUVs (all-wheel drive cars, station wagons on the chassis of the car), two-wheeled vehicles (especially motorcycles), aircraft, for example, transport machines for industrial purposes, selected from cars to vans, "heavy vehicles - i.e. subway trains, buses, road transport (trucks, tractors, trailery), off-road vehicles such as agricultural or construction equipment, and other transport or lifting the vehicle.

Another object of the present invention is the use of the breaker corresponding to the present invention, to obtain new tires or re-processing of waste tires.

Breakers corresponding to the invention are obtained in a way that is other object of the present invention, the above method includes the following stages:

- introduction to the isoprene elastomer, in a mixer:

- reinforcing filler and

- antioxidant

using a thermomechanical mixing a homogeneous mixture, in one or several stages, until then, until it reaches a maximum temperature of 110°C to 190°C;

- cooling the homogeneous mixture to a temperature below 100°C;

- then the introduction volcanic activity is serouse system;

- mixing the homogeneous mixture to a maximum temperature below 110°C;

- calendering or extruding the composition thus obtained in the form of a layer of rubber and

the introduction of this layer, after adding, if desired, textile or metal reinforcement, Brecker bus,

and characterized in that the above contains antioxidant 4,4'-bis(alkylamino)triphenylamine corresponding to the above formula (I).

The invention also relates to the use of compounds of the above formula (I) to protect against aging breaker bus.

The invention and its advantages will be more easily understood in the light of the description and illustrative embodiments that follow in the text of the patent application, and schematic drawings relating to these examples, which show radial cross-section tyres of heavy vehicles with radial frame fittings (figure 1) and also the reaction scheme for the synthesis of compounds of formula (I) suitable for the tread of the tire of the present invention (figure 2).

I. the measurements and tests

Rubber compositions are characterized before and after vulcanization, as shown below.

A) the Mooney plasticity:

Use the oscillating consistometer, such as described in French standard NF T 43-005 (1991). Plastic is the General Mooney is measured in accordance with the following principle: the composition in a wet state (i.e. before curing) is moulded in a cylindrical chamber when heated to 100°C. After preheating for one minute, the rotor rotates in the prototype at 2 rpm and operating torque for maintaining this movement is measured after rotating for 4 minutes. The Mooney plasticity (ML 1+4) is expressed in "Mooney units" (MU, 1 MU=0,83 N·m).

B) Rheology:

Measurements are performed at 150°C. the rheometer with the oscillation of the camera corresponding to the standard DIN 53529 - part 3 (June 1983). The change in rheological torque as a function of time describes the change in the stiffness of the composition, following the vulcanization reaction. The measurements are processed in accordance with standard DIN 53529 - part 3 (March 1983): t_iindicates the time of induction, in other words, the time required for the start of the vulcanization reaction; t_α(for example, t₉₉this refers to the time required to achieve a conversion of α%, in other words, α% (for example, 99%) difference between the minimum and maximum torques. Also measured is the constant of the first order rate conversion, denoted by K (expressed in min^-1), calculated from 30% to 80% conversion, which makes possible the determination of the kinetics of vulcanization.

(C) tensile Test

These tests allow the determination of the properties of elasticity in tension test and the gap. Unless otherwise stated, they who are made in accordance with French standard NF T 46-002, September 1988. Nominal secant modulus (or conditional stress in MPa) or the "true" secant modulus (related in this case, a valid cross-section of the test specimen) at 10% stretch (denoted respectively MA and E10), 100% stretch (respectively M and E100) and 300% extension (respectively M and e) is measured when the second extension (i.e. after the adaptive cycle). All these measurements stretching is performed at normal temperature (23±2°C) and the conditions of hygrometry (50±5% relative humidity) in accordance with French standard NF T 40-101 (December 1979). Also measured are the tensile strength (in MPa) and elongation at break (%) at 23°C.

D) "MFTRA" test:

Fatigue strength and resistance to cracking cuts (pre-initiation), expressed as the number of cycles or in relative units (u.r.), measured in the usual way on a test sample having a 1 mm incision, and subjected to repeated tensile tests low frequency to achieve a 20% stretch, using machine Monsanto ("MFTR" type), up until the test pattern will not be interrupted, in accordance with French standard NF T 46-021.

The above test is performed after rapid thermal oxidation 26-day aging, and tested on ASEC composition was placed in a vented oven, kept at a temperature of 80°C and ambient humidity of 40%.

II. DETAILED description of the INVENTION

Breakers tire of the present invention are distinguished mainly by the presence, in all or part of their rubber matrix, at least one elastomeric compositions based at least on each of the following components: (i) (at least one) of isoprene elastomer; (ii) (at least one) a reinforcing filler; (iii) a crosslinking system and (iv) (at least one) compound of formula (I) as an antioxidant.

Of course, it should be understood that the expression "composition based on" means a composition containing the actual product of the reaction and/or a mixture of different components used, and some of these basic components can, or intend, to interact with each other, at least partially, during the course of the steps in the manufacture of rubber compositions, breakers and buses, in particular when they are cured.

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

II-1. Diene elastomer

The term "diene" elastomer or rubber, both are treated as synonyms) implies, in General, the elastomer obtained, at least in part (i.e. a homopolymer or a copolymer) from diene mo is the Windows, in other words, from monomers carrying two (paired or unpaired) carbon-carbon double bonds.

This General definition is given to understand that the term "isoprene elastomer" in the present patent application means of isoprene homopolymer or copolymer, in other words a diene elastomer selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IRs), the various isoprene copolymers and mixtures of these elastomers. Among isoprene copolymers should, in particular, to mention isobutene/isopropane (butyl rubber - IIR), isoprene/styrene (SIR), isoprene/butadiene (BIR) or isoprene/butadiene/styrene (SBIR) copolymers.

Preferably isoprene elastomer is natural rubber or synthetic CIS-1,4-polyisoprene. Among these synthetic polyisoprenes preferably used polyisoprenes having a content (molar %) of CIS-1,4 linkages more than 90%, more preferably more than 98%.

When mixing (i.e. mixing) with the above isoprene elastomer composition of the present invention may contain a diene elastomers, in addition to the isoprene elastomer, preferably in a minimal amount (less than 50 parts per hundred). Isoprene elastomer is more preferably represents from 75 to 100% by weight, from about the quantity of diene elastomers, that is from 75 to 100 weight parts per 100 parts of rubber.

As such diene elastomers, in addition to the isoprene elastomer, it is important to mention any diene unsaturated elastomer of the type selected in particular from the group consisting of polybutadienes (BRs), in the particular case, CIS-1,4 or 1,2-syndiotactic of polybutadienes and those that have a content of 1,2-units of between 4% and 80%, butadiene copolymers, especially styrene/butadiene (SBR) copolymers, and in particular, those which have a styrene content of between 5% to 50% by weight, or in the more particular case from 20% to 40% by weight, a content of 1,2-bonds of butadiene part of between 4% and 65%, a content of TRANS-1,4 linkages from 30% to 80%, styrene/butadiene/isoprene (SBIR) copolymers, and mixtures of these various elastomers (BR, SBR and SBIR).

As an example, when the breaker of the present invention is intended for bus passenger vehicle, if you use this mixture, the preferred is a mixture of SBR and BR, which are used as a mixture of natural rubber, it is preferable to limit less than 25% by weight (or less than 25 parts per hundred) of a mixture of SBR and BR.

Breaker of the present invention, in particular, is intended for heavy vehicles, either new tires or worn out (in case of re-processing). In this case, the isoprene elastomer preferably is used directly, in other words, without mixing with another diene elastomer or polymer. More preferably, this isoprene elastomer was only natural rubber.

II-2. Reinforcing filler

It is possible to use any type of reinforcing filler known for its ability to reinforce a rubber composition that can be used in the manufacture of tyres, for example an organic filler, such as carbon black or inorganic reinforcing filler, such as silica gel, which modifier should be associated.

As soot suit all kinds of black carbon, especially carbon black HAF, ISAF, SAF type traditionally used in tires (known as bus soot). Among the latter it should be noted reinforcing carbon black series 100, 200 or 300 (ASTM degree), such as, for example, carbon black N115, N134, N234, N326, N330, N339, N347, N375, or more, depending on the purpose applications, soot higher series (for example, N660, N683, N772). Carbon black may, for example, already be entered in the isoprene elastomer in the form of masterbatches (see, for example, applications WO 97/36724 or WO 99/16600).

It should be understood that the expression "inorganic reinforcing filler" in this patent application refers, by definition, any inorganic or mineral filler, whatever its colour and its origin (natural or synthetic), also known is hydrated as "white" filler, "clear" filler or even "nonblack filler", as an alternative soot can increase, without any ways besides the intermediate modifier, a rubber composition intended for the receipt of tyres, in other words capable of replacing, in the role of the amplifier conventional carbon black for tires, this filler is in General characterized by, in a sense, the presence of hydroxyl (-OH) groups at its surface.

Suitable inorganic reinforcing fillers are mainly mineral fillers siliceous type, in particular silica (SiO₂or aluminous type, in particular alumina (Al₂O₃). Used silicon dioxide may be any reinforcing silica known to the experts in this field, especially any silica in the form of sediment or smoke, having a surface area according to BET and CTAB specific surface area, both of which are below 450 m²/g, preferably from 30 to 400 m²/, as a fine (known as "HD") deposited silicon oxides, mention should be made, for example, oxides of silica Ultrasil 7000 and Ultrasil 7005 from Degussa, the oxides of silica Zeosil 1165MP, 1135 MP and 1115MP from Rhodia, the silica Hi-Sil EZ150G from PPG and silicon oxides having a specific surface area such as is prescribed in the patent application WO 03/16837.

When the compositions of the present invention are intended for treads of tires having a low rolling resistance, it is used inorganic reinforcing filler, in particular if it is silica, preferably has a BET surface area of from 45 to 400 m²/g, more preferably from 60 to 300 m²/year

Preferably, the total content of reinforcing filler (carbon black, inorganic reinforcing filler or a mixture of these two types of filler) was from 20 to 200 parts per hundred, more preferably from 30 to 150 parts per hundred, and the optimal value, in a sense, differs depending on each specific case requirements.

In order to bind the inorganic reinforcing filler to the diene elastomer, is used, in a sense, at least bifunctional modifier (or bonding agent)intended to provide sufficient binding, chemical and/or physical nature, the inorganic filler (surface of its particles) and the diene elastomer, in particular bifunctional organosilanes or polyorganosiloxanes.

Especially used polysulfide silanes that can be "symmetrical" or "asymmetrical"depending on their specific structure, such as described, e.g. the measures in patent applications WO 03/002648 and WO 03/002649.

In particular, suitable, and the following definition is not a limitation, are "symmetric" polysulfide silanes corresponding to the following General formula:

Z-A-S_n-A-Z, in which

n denotes an integer from 2 to 8 (preferably from 2 to 5);

- A stands for divalently radical hydrocarbon-based (preferably₁-C₁₈alkylene group or₆-C₁₂aromatic group, more private With₁-C₁₀specifically With₁-C₄alkylene, in particular propylene); and

Z corresponds to one of the formulas below:

in which:

- R^1'radicals which may be substituted or unsubstituted and are identical or different from each other, represent₁-C₁₈alkyl, C₅-C₁₈cycloalkyl or₆-C₁₈aryl group (preferably₁-C₆alkyl, tsiklogeksilnogo or phenolic groups, especially With₁-C₄alkyl groups, in a more particular case, methyl and/or ethyl); and

- R^2'radicals which may be substituted or unsubstituted and are identical or different from each other, represent₁-C₁₈CNS or₅-C₁₈cycloalkyl GRU is PU (preferably group, selected from C₁-C₈CNS or cycloalkene group, more preferably a group selected from C₁-C₄CNS groups, in the particular case, methoxy and ethoxypropan).

In the case of a mixture of polysulfide alkoxysilanes corresponding to the above formula, especially conventional commercially available mixtures, the average value of "n" is the share of preferably between 2 and 5, more preferably close to 4. But the invention can also preferably be carried out, for example, a disulfide-alkoxysilane (n=2).

As examples of polysulfide silanes should, in a more particular case, to mention polysulfides (especially disulfides, trisulfide or tetrasulfide) bis((C₁-C₄)alkoxy(C₁-C₄)alkylsilane(C₁-C₄)alkyl), such as, for example, polysulfides bis(3-triethoxysilylpropyl) or bis(3-triethoxysilylpropyl). Among these compounds are used, in particular, bis(3-triethoxysilylpropyl) tetrasulphide, abbreviated to TESPT, of formula [(C₂H₅O)₃Si(CH₂)₃S₂]₂or bis(triethoxysilylpropyl) disulphide, abbreviated to TESPD, of formula [(C₂H₅O)₃Si(CH₂)₃S]₂. It should also be mentioned as preferred examples, polysulfides (especially disulfides, trisulfide or tetrasulfide) bis(mono(the ₁-C₄)alkoxide(C₁-C₄)alkylsulfonyl), in the more particular case of bis(monomethoxypolyethylene)tetrasulfide, as described in patent application WO 02/083782.

As a modifier in addition to the polysulfide of alkoxysilane mention should be made of bifunctional POSs (polyorganosiloxanes) or even hydroxyzinesee polysulfides (R^2'=OH in the formula above in the text of the patent application), as described in patent applications WO 02/30939 and WO 02/31041.

In the rubber compositions of the present invention, the content of the modifier is preferably from 4 to 12 parts per hundred, more preferably from 3 to 8 parts per hundred.

Can be pre-made graft copolymerization modifier to the diene elastomer or inorganic reinforcing filler. However, it is preferable, especially with the aim of better processing of the compositions in the raw state, to use the modifier or grafted copolymerizing to inorganic reinforcing filler, either in the free state (that is, without carrying out the graft copolymerization).

Ultimately, the expert in this field will be clear that as equivalent to the inorganic reinforcing filler described in the present section, a reinforcing filler of another nature, especially organic PR is childbirth, can be used up until this reinforcing filler is covered with an inorganic layer such as silicon dioxide, or contains on its surface functional areas, especially hydroxyl radicals, requiring the use of a modifier, to establish communication between the filler and the elastomer.

II-3. Antioxidant

The main distinguishing feature of breakers tire of the present invention lies in the presence, as an antioxidant, 4,4'-bis(alkylamino)triphenylamine corresponding to the formula (I)

in which R¹and R²which are identical or different, each represents an unbranched or branched alkyl group having from 1 to 12 carbon atoms, or cycloalkyl group having 5 to 8 carbon atoms.

Preferably R¹and R²which are identical or different, each represents an unbranched or branched alkyl group having from 2 to 8 carbon atoms, preferably selected from the group consisting of ethyl, sawn (i.e. n-propyl, isopropyl), butilkoi (that is, n-butyl, W-butyl and tert-butyl), Pintilei, hexylene, heptylene and octiles groups, or cycloalkyl group having 5 to 8 carbon atoms, cyclopentamine, tsiklogeksilnogo, cycloheptyl or cycle anjilina group), more preferably tsiklogeksilnogo group.

Among the above text of the patent application of the compounds of formula (I) is more preferable to use the connection for which R¹and R²groups are branched, formula (II) below

in which R³, R⁴, R⁵and R⁶which are identical or different, each represents an alkyl group whose number of carbon atoms is consistent with the preferred definitions given above in the text of the patent application for R¹and R².

Compounds corresponding to the above characteristic formulas (I) and (II), known as antiozonant or antioxidants for rubber; some of them, as well as their synthesis, for example, have been described in the patent US 3277174. No patent application compositions isoprene elastomer for a tire, especially in the breakers of the above tyres, have not yet been provided.

As preferable examples of the branched R¹and R²radicals, in particular, mention should be made of isopropyl (a), 1,3-dimethylbutyl (b) and 1,4-dimethylpentyl (C) radicals of the formulas below

Thus, in accordance with one particular preferred embodiment of the present invention, the breaker tire of this invention use the em as an antioxidant one of the following connections:

- 4,4'-bis(isopropylamino)triphenylamine corresponding to the specific formula

- 4,4'-bis(1,3-dimethylbutylamino)triphenylamine corresponding to the formula

- 4,4'-bis(1,4-dimethylpentylamine)triphenylamine corresponding to the formula

In forming part isoprene rubber composition of the tread of the tire corresponding to the invention, the content of the antioxidant of formula (I), (II) or (III) is preferably 1 and 10 parts per hundred. Below a certain minimum fatigue resistance may be insufficient, whereas above the recommended maximum, there is a risk of degradation of mechanical properties due to adverse plasticiser actions.

Given all these reasons, more preferably, the content of the antioxidant ranged from 2 to 8 parts per hundred, in the particular case of 2 to 6 parts per hundred.

II-4. Various additives

The rubber matrix of the breakers of the present invention may also contain one or more conventional additives used in rubber compositions intended for the receipt of breakers tires, such as, for example, oil filling rubber, plasticizers, stabilizers against aging, in addition to those mentioned above, such as protivoionov the th agent, other chemical antiozonant or antioxidants, means of improving fatigue strength, acceptors and donors of methylene bismaleimide or other reinforcing resin vulcanizing system based either on sulfur or on sulfur donors and/or peroxide, vulcanization accelerators, activators or inhibitors vulcanization system to activate the adhesion of rubber to metal, such as, for example, metal complexes or salts (for example, containing cobalt, boron, phosphorus, or even salts of lanthanides, such as described in the aforementioned patent application WO 2005/133666).

Isoprene matrix may also contain, in addition to the potential modifiers for inorganic reinforcing fillers, agents for covering these inorganic fillers, or, more generally, substances to improve the processing properties, is able, in a sense, to improve the dispersion of the filler in the rubber matrix and to reduce the viscosity of the compositions, thereby improving their technological characteristics.

II-5. Breakers and bus corresponding to the present invention

Previously described isoprene compositions are used to form all or part of the rubber matrix tread tires, particularly tires for heavy vehicles or passenger transport.

They may, for example, be used as the rubber strap is ü with a high content of rubber for calendering a layer or stratum of the breaker cord fabric, whether it is cross-linked layer, a protective layer or layer for a ring armature (at zero degrees), or they are intended for the formation of simple pads, ribbons or strips of rubber compound with a high rubber content, free from the amplifiers placed radially above or below the various above-mentioned layers of the breaker, or even placed between these layers, for example, for formation of the substrate protector, or even placed on the lateral ends of the layers of the breaker in the "shoulder" areas of the tyre, for example, for the formation of the unmodified rubber mixtures with a high content of rubber.

As an example, the accompanying figure 1 schematically represents a radial section of a tire of a heavy vehicle 1 having radial frame fittings that can meet or fail to meet this invention in General form. This tire 1 comprises a corona zone 2, two sidewalls 3, two boards 4, the radial frame reinforcement 7, ranging from one Board to another. Corona zone 2, is placed on top of the protector (not presented on this very schematic drawing, for simplification) is amplified, in a sense, with the help of the breaker 6, comprising at least two cross-linked layers in the crown area covered with at least one of the crown protective layer, and these layers usilivaut the steel cord, made of carbon steel. Frame the amplifier 7 is wound around the two bead wires 5 in each Board 4, and the side 8 of the amplifier 7, for example, is directed to the outside of the tire 1, which is depicted here, a raised rim 9. Frame the amplifier 7 is performed, at least one layer or layer reinforced steel cord, known as the radial cords, in other words, these cords are almost parallel one to another and from one Board to another so that they form an angle ranging from 80° to 90° with the median circumferential plane (plane perpendicular to the axis of rotation of the tire, which is located between the two flanges 4 and passes through the middle of the breaker 6).

The bus corresponding to the invention, of the above example has the main feature consists in its crown area 2, the belt 6, corresponding to the invention, the isoprene composition, based on the compound of formula (I), component rubber compound with a high rubber content for calendering layers of the breaker 6 (two stitched layers and the protective layer in this example).

In the case of tires containing, for example, one or more "zero degree" of layers, it is preferable that the rubber mixture with a high content of rubber for the cord calendering fabric, VI is e Li layer, having a defined width close to the width of the stitched layers, or even in the form of a single wire in a rubber shell, was also based on the isoprene composition containing the compound of formula (I).

In accordance with one preferred embodiment of the present invention, a rubber composition based on the isoprene elastomer, a reinforcing filler and an antioxidant of the formula (I), has, in volcanoserver.com state (i.e. after vulcanization), the moment resistance of the cross section during extension (E10), which is more than 5 MPa, more preferably from 7 to 20 MPa. Higher ranges of moments shows that the best compromise of fatigue resistance.

II-6. Obtain rubber compositions

Rubber compositions are produced in suitable mixing devices, the use of two sequential stages of obtaining well-known to specialists in this field: the first stage of thermomechanical working or kneading (sometimes referred to this stage as "unproductive") at high temperature, up to the maximum temperature (denoted as T_maxbetween 110°C. and 190°C., preferably between 130°C and 180°C, with a subsequent second phase of mechanical working (sometimes referred to as "productive" phase) at lower temperature, typically below 110°C, in EMA which introduces a crosslinking or vulcanizing system, which completes the stage.

The method of receiving breakers tire of the present invention, characterized in that at least a reinforcing filler and a compound of formula (I) are introduced with stirring isoprene elastomer during a first non-productive stage, in other words, at least, these different main components are introduced into the mixing apparatus and thermo-mechanical mixed in one or more stages until then, until it reaches the maximum temperature of between 110°C. and 190°C., preferably between 130°C. and 180°C.

As an example, the first (non-productive) phase is performed in a single thermomechanical stage during which the following components are introduced into a suitable mixer, such as a traditional closed mixer: first, all basic components (isoprene elastomer, a reinforcing filler and a compound of formula (I)), then, secondly, for example, after stirring for one to two minutes, additional processing AIDS, and other various additives, in addition to crosslinking or vulcanizing system. The total mixing time in this non-productive stage is preferably from 2 to 10 minutes.

After cooling the mixture, thus obtained, are then introduced vulcanizing system at low tempera is ur, in the General case, in an external mixer, such as a roller mill; then the whole mixture is completely mixed (productive phase) for several minutes, for example from 5 to 15 minutes.

Thus obtained final composition is then calandered, for example, in the form of sheets (thickness of 2 to 3 mm) or of thin films of rubber in order to measure the physical or mechanical properties, especially for laboratory research, or extruded to form the profile of the wheel tread, which can be used directly, after cutting or mounting to the preset sizes and after adding the desired textile or metal reinforcement, such as a layer of the breaker.

Thus, the method corresponding to the present invention, receipt of the tread of the tire corresponding to the present invention, comprising a rubber composition based on at least one isoprene elastomer, a reinforcing filler, a crosslinking system and an antioxidant, includes the following stages:

- introduction to the isoprene elastomer, in a mixer:

- reinforcing filler and

- antioxidant

when thermomechanical mixing the mixture, in one or several stages until then, until it reaches the maximum temperature of between 110°C. and 190°C;

- cooling source CME and to a temperature below 100°C.;

- then the introduction of a crosslinking system;

- mixing the source system to the maximum temperature below 110°C;

- calendering or extruding the thus obtained composition in the form of a layer of rubber and

the introduction of this layer, after the possible addition of textile or metal amps, the breaker bus,

and characterized in that the above contains antioxidant 4,4'-bis(alkylamino)triphenylamine corresponding to the above formula (I).

Vulcanization or curing is performed, in a sense, at a temperature preferably between 130°C and 200°C and under pressure, for a sufficient time which may vary, for example, from 5 to 90 min, depending in the particular case, the temperature of vulcanization, used vulcanizing system, the kinetics of vulcanization and the tire size question.

Directly cross-linking system is preferably based on sulphur and on a primary vulcanization accelerator, in particular the accelerator sulfenamide type. Added to this vulcanizing system, introduced during the first non-productive phase and/or during the productive stage, are various known secondary accelerators or vulcanization activators, such as zinc oxide, stearic acid, guanidine derivatives (in the particular case of the WPPT is iguanidae), the vulcanization retarders, etc.

Sulfur is used in amounts of preferably from 1 to 10 parts per hundred, more preferably from 2 to 8 parts per hundred, especially when the invention is used for tires of heavy vehicles. The primary vulcanization accelerator is used in an amount preferably from 0.5 to 5 parts per hundred, more preferably from 0.5 to 2 parts per hundred.

May be used as primary or secondary accelerator, any compound capable of acting as an accelerator for vulcanization of diene elastomers in the presence of sulfur, especially accelerators, thiazole type and their derivatives, accelerators turnovoo or zinc dithiocarbamate type. These accelerators are more preferably selected from the group consisting of 2-mercaptobenzothiazole (abbreviated MBTS), N-cyclohexyl-2-benzothiazolesulfenamide (abbreviated CBS), N,N-DICYCLOHEXYL-2-benzothiazolesulfenamide (abbreviated DCBS), N-tert-butyl-2-benzothiazolesulfenamide (abbreviated TBBS), N-tert-butyl-2-benzothiazolesulfenamide (abbreviated TBSI), dibenzyldithiocarbamate zinc (abbreviated ZBEC), and mixtures of these compounds. Preferably use the primary accelerator sulfenamide type.

Does not require evidence that the invention relates to a breakers and buses, as described previously in the "raw" form (that is here to vulcanization), and in the "cured" or volcanoserver.com state (that is, after crosslinking or vulcanization).

III. Illustrative embodiments of the present invention

III-1. Synthesis of 4,4'-bis(1,3-dimethylbutylamino)triphenylamine

The compound of formula (III) obtained according to the synthesis scheme shown in figure 2, which was inspired, in a particular case, a known method of synthesis described in the above document US 3277174 (Example 7).

In more detail the synthesis was performed in three stages (A, B and C), as follows.

A) Obtaining 4,4'-dinitrodiphenylamine:

Added a 2-liter three-neck flask equipped with a thermometer, a stirrer and a trap Dean-stark, filled with benzene, 121 g (1 mol) of formanilide, 314 g (2.5 mol) of nitrochlorobenzene, 220 g (1.6 mol) K₂CO₃in 115 ml of DMF and 5 ml of benzene. Wednesday was heated at 165-174°C for 21 hours with constant extraction of the formed water. The reaction was cooled and stopped with 1 liter of water. The precipitate was filtered, suspended dilute hydrochloric acid, then filtered, and again suspended in hot ethanol. Thus obtained suspension was filtered to obtain 242 g (72% yield) of 4,4'-dinitrodiphenylamine.

C) Obtaining 4,4'-diaminodiphenylamine:

In order to obtain 4,4'-diaminodiphenylamine, then did the no is the connection from the previous stage by hydrogenation in isopropanol at 100°C, under the pressure of the H₂about 20 bar and in the presence of palladium catalyst (on an angle).

C) Synthesis of 4,4'-bis(1,3-dimethylbutylamino)triphenylamine:

The next step following compounds were placed in a reactor: 85 g (that is, 0.3 mol) of 4,4'-diaminodiphenylamine from the previous stage, 400 ml (that is, 3 mol) of 4-methylpentan-2-he (or MIBK) in the presence of 2 g of Pd (5 wt.% on the corner), under the pressure of the H₂25 bar, for 1 hour 45 minutes at 100-130°C., then 2 hours 30 minutes at 130-135°C. the Catalyst was separated by filtration, and excess MIBK was removed by distillation. The residue (yield of approximately 92%) was purified by chromatography on aluminium oxide. The product has to recrystallize in ethanol. Thus, the compound of formula (III) obtained with a total yield of approximately 66%.

III-2. Obtain rubber compositions

The following tests were performed in the following way: put into a closed mixer filled to 70%, in which the initial chamber temperature was approximately 60°C., isoprene elastomer, a reinforcing filler (carbon black), then after stirring for one to two minutes various other ingredients, including the compound of formula (III), but except for the vulcanizing system. The following thermo-mechanical working stage (non-productive phase) is performed in one or two stage (full mixing time is, for example, the arr is SyteLine 7 minutes) as long until it was achieved the maximum dropping temperature of about 165-170°C. the Mixture thus obtained was isolated, cooled, and then vulcanizing system (sulfur and primary sulfenamide accelerator) was added in an external mixer (homofinisher) at 30°C, under stirring all the content (productive phase), for example, within 3-10 minutes.

The composition thus obtained, and then either have extrudible in the form of sheets (thickness of 2 to 3 mm)in order to measure their physical or mechanical properties, or Kalandarishvili to obtain a metal cord fabric forming the layer of the breaker ("working" layer) tyres of heavy vehicles.

III-3. Laboratory tests to determine characteristics

The purpose of this test was to demonstrate improved fatigue resistance isoprene rubber composition for the tread of the tire when it contains antioxidant corresponding to the formula (I), compared to the control rubber composition using traditional antioxidant (6-PPD).

This has prepared two compositions based on natural rubber:

- composition, denoted by C-1 (control); and

- composition, denoted With a-2 (the present invention).

These two compositions having the formulations that were identical except for the nature and con is entrale by weight of an antioxidant, intended for education calendered rubber operational layers of the breaker for tires of heavy vehicles.

Tables 1 and 2 show the composition of the two compositions (table 1 - contents of a variety of products, expressed in parts per hundred (%, unit concentration of the additive/modifier to the plastic)), and their properties before and after curing (60 minutes at 140°C). Vulcanizing system consisted of sulfur and sulfenamide. In these compositions C-1 and C-2 used two antioxidant, essentially, isomolar number, which implies that whatever the composition nor tested, used the same number of moles of active functional groups (secondary amines); this explains the difference in the weight content of the product (expressed in parts per hundred).

It should be recalled here that the connection 6-PPD, antioxidant comparison, in rubber compositions for tires, especially in the breakers last, has deployed the formula

For comparison, you can try the below formula (III) 4,4'-bis(1,3-dimethylbutylamino)triphenylamine used in the composition C-2:

You can immediately notice that the second molecule has a much greater steric obstruction and, therefore, less ability to diffusion, which, for specialists in this area, is initially n is desirable for effective protection against fatigue.

When checking the results from Table 2 first, it is noteworthy that two of the investigated compositions are, to aging, identical rubber properties as the properties prior to vulcanization (Mooney viscosity and rheological properties), and after vulcanization (mechanical tensile properties). This is already an indication that the antioxidant compositions of the invention to aging compositions, works also as a comparative antioxidant control composition.

Only after accelerated aging by heating, in the MFTRA dimensions (main 100 left for the control composition C-1), which is very much improved fatigue strength (increase of almost 50%), unexpectedly observed in the composition corresponding to the invention, the improvement that can be attributed only to the use of compounds of formula (III).

This result allows the specialists in this field can expect a high fatigue strength breakers and tire of the present invention, in particular with regard to the problem of separation of the ends of the crown layers (“stratification”), mentioned earlier.

(1) Natural rubber;

(2) Carbon black N330 (ASTM grade);

(3) N-1,3-dimethylbutyl-N-phenyl-para-phenylenediamine (SANTOFLEX 6-PPD from Flexsys);

(4) 4,4'-bis(1,3-dimethylbutylamino)triphenylamine;

(5) zinc Oxide (industrial grade - Umicore);

(6) Stearin (PRISTERENE 4931 - Uniqema) and

(7) N-DICYCLOHEXYL-2-benzothiazolesulfenamide (SANTOCURE DCBS from Flexsys).

1. Brecker tire containing the rubber composition based on at least one isoprene elastomer, a reinforcing filler, a crosslinking system and an antioxidant, wherein the above-mentioned antioxidant contains 4,4'-bis(1,3-alkylamino)-triphenylamine corresponding to the formula (I):
,
in which R¹and R²which are identical or different, each denotes unbranched or branched alkyl group having from 1 to 12 carbon atoms, or cycloalkyl group having 5 to 8 carbon atoms.

2. Brecker tire according to claim 1, in which R¹and R²which are identical or different, each represents an alkyl group having from 2 to 8 carbon atoms, or tsiklogeksilnogo group

3. Brecker tire according to claim 2, in which R¹and R²radicals, which are identical or different, each represents an alkyl group selected from the group consisting of isopropyl, 1,3-dimethylbutyl and 1,4-dimethylpentyl.

4. Brecker tire according to claim 3, in which the antioxidant is 4,4'-bis(isopropylamino)triphenylamine corresponding to the formula (III-a):

5. Brecker tire according to claim 3, in which the antioxidant is 4,4'-bis(1,3-dimethylbutylamino)triphenylamine corresponding to the formula (III-b):

6. Brecker tire according to claim 3, in which the antioxidant is 4,4'-bis(1,4-dimethylpentylamine)triphenylamine corresponding to the formula (III-C):

7. Breaker bus to claim 1, in which the content of the antioxidant is from 1 to 10 parts per hundred.

8. Brecker tire according to claim 7, in which the content of the antioxidant is from 2 to 8 parts per hundred.

9. Brecker tire according to any one of claims 1 to 8, in which the isoprene elastomer is selected from the group consisting of natural rubber, synthetic CIS-1,4-polyisoprene and mixtures of these elastomers.

10. Brecker tire according to claim 9, in which the isoprene elastomer is natural rubber.

11. Applying, to protect against aging breaker tire, antioxidant, containing 4,4'-bis(alkylamino)triphenylamine corresponding forms of the Le (I):
,
in which R¹and R²which are identical or different, each represents a linear or branched alkyl group having from 1 to 12 carbon atoms or cycloalkyl group having 5 to 8 carbon atoms.

12. The application of the tread of the tire corresponding to claims 1 to 10, in the manufacture or repair of tires.

13. Bus, including Brecker, corresponding to claims 1 to 10.

14. Bus corresponding to item 13, which, in fact, is a bus heavy vehicles.

15. The method of obtaining the tread of the tire containing the rubber composition based on at least one isoprene elastomer, a reinforcing filler, a crosslinking system and an antioxidant comprising the following stages:
- introduction to the isoprene elastomer, in a mixer:
- reinforcing filler; and
- antioxidant,
using a thermomechanical mixing a homogeneous mixture, in one or several stages, until you reach the maximum temperature from 110 to 190°C;
- cooling the homogeneous mixture to a temperature below 100°C;
then the introduction of a vulcanizing system;
- mixing the homogeneous mixture to a maximum temperature below 110°C;
- calendering or extruding the composition thus obtained, in the form of a layer of rubber; and
the introduction of this layer after adding what about the desire of textile or metal reinforcement in Brecker tires,
the above method is characterized by the fact that the above contains antioxidant 4,4'-bis(alkylamino)triphenylamine corresponding to the above formula (I):
,
in which R¹and R²which are identical or different, each represents an unbranched or branched alkyl group having from 1 to 12 carbon atoms, or cycloalkyl group having 5 to 8 carbon atoms.