Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons

Definitions

• the invention relates to rubber compositions for tire tread and more particularly to rubber compositions used in tire treads called "winter” that is to say tires particularly effective on wet floors or coated with snow or melting ice, that is to say for temperatures between -10 0 C and 0 0 C, preferably between -5 ° C and 0 0 C.
• Some solutions consist for example of incorporating into the constitutive rubber mixture of the tread, water-soluble powders. Such powders solubilize on contact with snow or melted ice, which allows on the one hand the creation on the surface of the tire tread of porosities likely to improve the "hooking" of the tire strip. bearing on the ground and on the other hand the creation of grooves acting as evacuation channels of the liquid film created between the tire and the ground.
• publication JP-3 159803 describes tire treads whose rubber composition comprises from 3 to 25 phr (pce meaning parts by weight per 100 parts of elastomers), of polysaccharide powder such as carboxymethylcellulose.
• EP 0 940 435 discloses a rubber composition for tread comprising from 1 to 25 phr of modified polyvinyl alcohol with a particle size of between 10 and 100 ⁇ m and a solubility at 0.degree. C Ig for 200 ml of water for a very short mixing time, that is to say of the order of one minute.
• JP200211203 describes a rubber composition for tread comprising 3 to 40 phr of starch powder whose particles have a size greater than or equal to 20 microns and a solubility of 1 g in 100 ml of water at 10 0 C reached after 3 minutes of mixing.
• the Applicant has surprisingly discovered that the introduction into the constitutive rubber composition of the tread of a particular polysaccharide powder not faded into the water in a very short time (of the order of one minute ) and at very low temperatures (of the order of 0 °) nevertheless allowed to improve the behavior of the tires in terms of resistance to sliding and adhesion on snow-covered or frozen ground without the slight drop in resistance to wear accompanying this amendment is unacceptable for the industrial use of such tires.
• tread tire the entire tread or part of the latter, especially when it is composed of several layers in contact with the ground.
• the invention thus relates to a tire tread having a rubber composition based on at least one diene elastomer, a reinforcing filler, a vulcanization system characterized in that the composition comprises a powder of xanthan gum in a proportion of 10 to 40 phr, and preferably 15 to 30 phr.
• the size of the particles of xanthan gum powder is between 10 and 500 microns, preferably between 50 and 300 microns.
• the xanthan gum powder is used in a blend with one or more other polysaccharide powders and in particular with a guar gum powder.
• the diene elastomer is predominantly, for more than 50 phr, an isoprene elastomer. - AT -
• the reinforcing filler mainly comprises carbon black.
• the reinforcing filler mainly comprises silica or comprises a blend of carbon black and silica.
• the invention also relates to a process for obtaining a rubber composition for a tread based on at least one diene elastomer, a reinforcing filler, a vulcanization system, which comprises a first kneading phase.
• thermomechanical composition of the constituents of the composition with the exception of the vulcanization system characterized in that the composition comprises a powder of xanthan gum in a proportion of 10 to 40 phr, preferably 10 to 30 phr, and that the Xanthan gum powder is incorporated during the first mixing phase.
• the first phase of the process is carried out in two steps: a first kneading step of all the constituents of the composition with the exception of xanthan gum powder and a second step in which the powder of xanthan gum is incorporated.
• the first step of the first mixing step is carried out at a temperature between 110 0 C and 190 0 C and, preferably, between 130 0 C and 180 0 C; the second step of the first kneading phase is carried out at a temperature of less than or equal to 130 ° C., after cooling after the first step, preferably at a temperature of less than or equal to 100 ° C.
• the second phase of the process is carried out at a temperature between 60 0 C and 100 0 C.
• the invention also relates to a tire comprising a tread whose rubber composition is based on at least one diene elastomer, a reinforcing filler, a vulcanization system characterized in that the composition comprises a powder of xanthan gum in a proportion of 10 to 40 phr, and particularly a winter tire comprising such a tread.
• the invention also relates to a tire intended to equip a vehicle called “heavyweight” (that is to say, subway, bus, road transport equipment (trucks, tractors, trailers), off-road vehicles. -route), aircraft, civil engineering, agrarian, or handling equipment, comprising a tread according to the invention.
• a vehicle that is to say, subway, bus, road transport equipment (trucks, tractors, trailers), off-road vehicles. -route), aircraft, civil engineering, agrarian, or handling equipment, comprising a tread according to the invention.
• the invention finally relates to a tire for equipping a passenger vehicle, comprising a tread according to the invention.
• polysaccharide gums all polysaccharides or their derivatives which are dispersed in water produce gels, highly viscous or solutions.
• Xanthan gum is part of the polysaccharide gums, it is food fibers "considered” as thickeners and gelling that are not soluble in water, indeed they form a gel on contact.
• compositions according to the invention are based on the following constituents: at least one diene elastomer, a reinforcing filler and a crosslinking system.
• composition based on is meant a composition comprising the mixture and / or the reaction product in situ of the various basic constituents used, some of these constituents being able to react and / or being intended to react. between them, at least partially, during the various phases of manufacture of the composition, or during subsequent cooking.
• elastomer or "diene” rubber is meant in known manner an elastomer derived at least in part (i.e. a homopolymer or a copolymer) of monomers dienes (monomers carrying two carbon-carbon double bonds, conjugated or not).
• iene 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. % (mole%).
• diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins EPDM type (ethylene-propylene-diene terpolymer) do not fall within the previous definition and can be particularly described as "essentially saturated" diene elastomers (low or very low diene origin, always less than 15%).
• 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%.
• conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) alkyl-1,3-butadienes, such as 2,3dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1,3 butadiene, an aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene.
• vinyl aromatic compounds are suitable for example styrene, ortho-, meta-, para-methylstyrene, the commercial mixture "vinyl-toluene", para-tertiarybutylstyrene, 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.
• the elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used.
• the elastomers can be for example block, statistical, sequence, microsequential, and be prepared in dispersion or in solution; they can be coupled and / or star or functionalized with a coupling agent and / or starring or functionalization.
• Polybutadienes and, in particular, those having a content of -1.2 units of between 4% and 80% or those having a cis-1,4 content of greater than 80%, polyisoprenes or copolymers, are preferably suitable.
• butadiene-styrene and in particular those having a styrene content of between 5% and 50% by weight and more particularly between 20% and 40%, a 1,2-butadiene content of the butadiene part between 4% and 65%, a content of trans-1,4 bonds of between 20% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight and a glass transition temperature (Tg) of -40 ° C. to -80 ° C., the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg of between -25 ° C. and -50 ° C.
• Tg glass transition temperature
• butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly between 10% and 40%, an isoprene content of between 15% and 60% by weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight and more particularly between 20% and 40%, a content of -1,2 units of the part butadiene content of between 4% and 85%, a trans-1,4 content of the butadiene part of between 6% and 80%, a content of -1,2 units plus -3,4 of the isoprenic part of between 5% and 80%; % and 70% and a trans-1,4 content of the isoprene portion of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg of between -20 ° C. and -70 ° C. .
• the diene elastomer of the composition according to the invention is chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (BR), polyisoprenes (IR) or natural rubber (NR).
• BR polybutadienes
• IR polyisoprenes
• NR natural rubber
• butadiene-styrene copolymers SBR
• butadiene-isoprene copolymers BIR
• isoprene-styrene copolymers SIR
• butadiene-acrylonitrile copolymers NBR
• isoprene-styrene copolymers SIR
• butadiene-styrene-isoprene copolymers SBIR
• butadiene-styrene-acrylonitrile copolymers SBR
• SBIR butadiene-styrene-acrylonitrile copolymers
• the diene elastomer is predominantly (for more than 50 phr) an isoprene elastomer. This is particularly the case when the compositions of the invention are intended to constitute, in the tires, the rubber dies of certain treads (for example for industrial vehicles).
• isoprene elastomer in known manner a homopolymer or a copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR ), the various isoprene copolymers and the mixtures of these elastomers.
• NR natural rubber
• IR synthetic polyisoprenes
• isoprene copolymers examples include isobutene-isoprene copolymers (butyl rubber-HR), isoprene-styrene copolymers (SIR), isoprene-butadiene copolymers (BIR) or isoprene-butadiene-styrene copolymers. (SBIR).
• This isoprene elastomer is preferably natural rubber or synthetic cis-1,4 polyisoprene; of these synthetic polyisoprenes, polyisoprenes having a content (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%, are preferably used.
• diene polymers can be used alone or in combination with other elastomers conventionally used in tires such as essentially saturated diene elastomers such as:
• a reinforcing filler it may in particular use carbon black or silica or other reinforcing fillers alone or in a cut with each other.
• carbon blacks are suitable for all carbon blacks, especially blacks of the type HAF, ISAF, SAF, conventionally used in tires and particularly in the treads of tires.
• blacks of the type HAF, ISAF, SAF conventionally used in tires and particularly in the treads of tires.
• a highly dispersible precipitated silica is preferably used, in particular when the invention is used for the manufacture of tires having a low rolling resistance; as non-limiting examples of such preferential highly dispersible silicas, mention may be made of the Ultrasil 7000 and Ultrasil 7005 silicas from Degussa, the Zeosil 1165MP, 1135MP and II 15MP silicas from Rhodia, the Hi-SiI silica EZ150G from PPG.
• Zeopol silicas 8715, 8745 and 8755 from the Huber Company treated precipitated silicas such as, for example, the "aluminum doped" silicas described in the above-mentioned application EP-A-0735088.
• the vulcanization system itself is preferably based on sulfur and a primary vulcanization accelerator, in particular a sulfenamide type accelerator.
• a primary vulcanization accelerator in particular a sulfenamide type accelerator.
• various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (in particular diphenylguanidine), etc.
• Sulfur is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr, for example between 0.5 and 3.0 phr, when the invention is applied to a strip. of tire rolling.
• the primary vulcanization accelerator is used at a preferential rate of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr, in particular when the invention is applied to a tire tread. It goes without saying that the invention relates to the previously described rubber compositions both in the so-called “raw” state (ie, before firing) and in the so-called “cooked” or vulcanized state (ie, after crosslinking). or vulcanization).
• compositions according to the invention can be used alone or in cutting (i.e., mixed) with any other rubber composition used for the manufacture of tires.
• the rubber compositions in accordance with the invention may also comprise all or part of the usual additives normally used in elastomer compositions intended for the manufacture of tires, for example plasticizers or extension oils, which these are of aromatic or non-aromatic nature, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M) as described for example in the application WO 02/10269 (or US2003-0212185).
• the rubber compositions are characterized after baking as indicated below.
• the dynamic properties G * and tan ( ⁇ ) max are measured on a viscoanalyzer (Metravib V A4000), according to the ASTM D 5992 - 96 standard.
• the response of a sample of vulcanized composition (cylindrical test specimen 2 mm in diameter) is recorded. thickness and 78.5 mm2 section), subjected to sinusoidal stress in alternating simple shear, at a frequency of 10 Hz, under normal temperature conditions according to ASTM D 1349 - 99.
• a strain amplitude sweep is carried out peak to peak of 0.1 to 50% (forward cycle), then 50% to 1% (return cycle).
• the results exploited are the complex dynamic shear modulus (G *) and the loss factor, tan ( ⁇ ). For the return cycle, the maximum value of tan ( ⁇ ) observed (tan ( ⁇ ) max) is indicated.
• compositions are manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermo-mechanical mixing (sometimes called “non-productive” phase) to high temperature, up to a maximum temperature (denoted Tmax) of between 110 ° C. and 190 ° C., preferably between 130 ° C.
• a second phase of mechanical work (sometimes referred to as a "productive" phase ") at a lower temperature, typically less than 110 0 C, for example between 60 0 C and 100 0 C, finishing phase during which is incorporated the crosslinking system or vulcanization; such phases have been described for example in the aforementioned EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.
• the first phase (non-productive) is conducted in two thermomechanical steps.
• the first step all the necessary basic constituents, any coating agents or application agents are introduced into a suitable mixer such as a conventional internal mixer. and other miscellaneous additives, with the exception of the vulcanization system.
• This first step is carried out at a temperature of between 110 ° C. and 190 ° C. and, preferably, between 130 ° C. and 180 ° C.
• the second thermomechanical working step is carried out in this internal mixer, after intermediate cooling (cooling temperature).
• the total mixing time, in this non-productive phase, is preferably between 2 and 10 minutes at a temperature of less than or equal to 130 ° C. in order to avoid any degradation of the polymer.
• the low temperature vulcanization system is then incorporated, generally in an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 minutes.
• the final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or extruded, to form for example a rubber profile used for the manufacture semi-finished products such as treads.
• the vulcanization (or cooking) is conducted in a known manner at a temperature generally between 130 0 C and 200 0 C, under pressure, for a sufficient time which may vary for example between 5 and 90 minutes depending in particular on the cooking temperature, the vulcanization system adopted, the kinetics of vulcanization of the composition in question or the size of the tire.
• This example is intended to show the superiority of a tread according to the invention with respect to a control tread in an ice-start situation of a tire, with a temperature of between -5 ° C. and 0 ° C.
• control tread is made from a control composition Al and the tread according to the invention from a composition A2 according to the invention, that is to say comprising a Xanthan gum powder in proportions and for a particle size corresponding to the invention
• compositions A1 and A2 have the same basic formula A.
• This basic formulation A is as follows:
• compositions A1 and A2 are shown in Table 1 which follows.
• Xanthan gum RHODOPOL 23, RHODIA (particle size: 106 ⁇ m)
• composition A1 is manufactured with an introduction of all the constituents on an internal mixer, with the exception of the vulcanizing agents (sulfur and accelerator) introduced on an external mixer at low temperature (the constituent cylinders of the mixer being about 30.degree. 0 C).
• composition A2 is manufactured according to the process of the invention, with the introduction, during the first step of the non-productive phase, of the constituents on an internal mixer with the exception of xanthan gum, said xanthan gum being introduced in the second step on the internal mixer with a temperature not exceeding 130 0 C so as not to degrade the polysaccharide powder.
• the vulcanization system is then introduced, during the second "productive" phase, onto an external mixer.
• treads corresponding to the compositions A1 and A2 are then manufactured in accordance with the method described above in the description.
• the measurements are performed for the empty vehicle and for the laden vehicle, that is to say, with a nominal load.
• the purpose of this example is to compare the properties of stiffness, stress and elongation properties, and so on. of several rubber compositions according to the invention with those of a tread composition conforming to the state of the aforementioned technique that is to say comprising a water-soluble powder such as carboxymethylcellulose or polyvinyl alcohol, PV A.
• compositions were prepared according to the procedure described in Example 1 for A2, A2 being identical to the composition of the same name of Example 1.
• compositions noted A2, E (PVA) and F (CARBO) have the basic formulation A specified in Example 1, they are distinguished from each other by their content of xanthan gum or powder hydrolso lubie as follows: - A2 contains 20 phr of xanthan gum, RHODOPOL 23, RHODIA (particle size: 106 ⁇ m)
• PVA 20 phr of PVA sold under the name Mowiol 4-88 by the company Alrich, PVA 86.7-88.7 mol% hydrolysis, degree of polymerization 630, viscosity at 4% in H20 at 20 ° C 3-5mPa. s, (particle size: 500 ⁇ m)
• CARBO 20 phr of carboxymethylcellulose, sodium salt, originating from FLUKA (N ° 21903), characterized by a solution viscosity of 700-1500 mPa.s ( at 1% in H 2 O at 25 ° C) and a degree of substitution of 0.7- 0.85 (particle size: 89 ⁇ m).
• Table 3 gives the properties measured after cooking at 150 0 C for 25 minutes.
• compositions A2 according to the invention have a much better compromise of mechanical reinforcement without a significant penalty for the hysteresis of the material, that the mixtures comprising polyvinyl alcohol, E (PVA), or carboxymethylcellulose, F (CARBO).
• EXAMPLE 3 The purpose of this example is, in the same way as in Example 1, to compare the different rubber properties of a diene control tread composition which does not include polysaccharide or water-soluble powder with compositions for tread according to the invention, that is to say comprising a powder of xanthan gum.
• the two base formulation compositions B have a blend of natural rubber and synthetic rubber different from that of Example 1.
• This basic formulation B is the following:
• compositions B1 and B2 are given in Table 4 which follows:
• the first mixing stage of the process (so-called non-productive phase) is carried out in a mixing tank.
• the main ingredients (elastomer, silica, oil and chemical additives) are introduced.
• a finishing phase of the process (so-called productive phase) performed on a cylinder tool, the vulcanization system is introduced. Table 5 gives the properties measured after cooking at 150 0 C for 40 minutes.
• composition B2 according to the invention comprising a xanthan gum
• This example is intended to show the superiority of a tread according to the invention with respect to a control tread in an ice-up situation of a tire with a temperature of between -5 ° C. and 0 ° C. 0 C for treads manufactured according to the method detailed in the description with rubber compositions Bl, control, and B2, according to the invention, identical to those of Example 3 above.
• These compositions B1 and B2 were used for the manufacture of tire treads 205 / 55R16 brand "MICHELIN X Ice", mounted on a vehicle "TOYOTA PRONAR" with a braking system with anti Wheel Lock (ABS) and Start Control (TCS).
• Ice driving tests were conducted, during which different types of icy slopes and temperature conditions were tested.
• IPFreinage (Braking distance of the indicator / tire braking distance test) * 100.
• Start-up test The results obtained after the start-up test (active anti-skid system) correspond to the time required to accelerate from 5 to 20 km / h at full engine speed under the control of the TCE system.
• the ice acceleration tests are performed on a covered track.
• IPStart (Light start time / Test tire acceleration time) * 100. The results obtained are shown in Table 6 which follows.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Tires In General (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38328279

Family Applications (1)

Country Status (5)

Cited By (3)

Families Citing this family (26)

Family Cites Families (31)

• 2006
  • 2006-12-27 FR FR0611509A patent/FR2910904B1/fr not_active Expired - Fee Related
• 2007
  • 2007-12-06 US US12/521,482 patent/US8372901B2/en not_active Expired - Fee Related
  • 2007-12-06 JP JP2009543424A patent/JP5450091B2/ja active Active
  • 2007-12-06 WO PCT/EP2007/063397 patent/WO2008080751A1/fr active Application Filing
  • 2007-12-06 EP EP07847884A patent/EP2104710A1/fr not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events