Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • 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
• • 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
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/49—Phosphorus-containing compounds
  • C08K5/51—Phosphorus bound to oxygen
  • C08K5/52—Phosphorus bound to oxygen only
  • C08K5/521—Esters of phosphoric acids, e.g. of H3PO4
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/54—Silicon-containing compounds
  • C08K5/548—Silicon-containing compounds containing sulfur
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0016—Plasticisers

Definitions

• the invention relates to the tires having treads suitable for snow tires or winter tires, capable of rolling over ground surfaces covered with snow.
• the snow tires classified in a category of use "snow”, identified by an inscription the Alpine symbol ("3-peak-mountain with snowflake), marked on their sidewalls, mean tires whose tread patterns, tread compounds or structures are primarily designed to achieve, in snow conditions, a performance better than that of normal tires intended for normal on-road use with regard to their abilities to initiate, maintain or stop vehicle motion.
• Snowy ground referred to as white ground, has the feature of having a low friction coefficient and a constant objective of tire manufactures is improvement of a grip performance of winter tires on snow. .
• a first subjective matter of the invention is a snow tire having a tread comprising a rubber composition comprising at least, more than 50 and up to 100 phr of a first diene elastomer chosen from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes and the mixtures thereof, optionally, 0 to less than 50 phr of another diene elastomer, 40 to 200 phr of a reinforcing filler comprising an inorganic filler, a carbon black or the mixture thereof, wherein a content of the carbon black is less than 20 phr, more than 10 phr and less than 100 phr of a liquid phosphate plasticizer having a glass transition temperature less than - 80°C.
• a first diene elastomer chosen from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes and the mixtures thereof, optionally, 0 to less than 50 phr of another diene e
• aspects of the present invention can be as follows.
• a snow tire having a tread comprising a rubber composition comprising at least:
• first diene elastomer chosen from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes and the mixtures thereof,
• a reinforcing filler comprising an inorganic fil ler, a carbon black or the mixture thereof, wherein a content of the carbon black is less than 20 phr; and more than 10 phr and less than 100 phr of a liquid phosphate plasticizer having a glass transition temperature less than -80°C.
• liquid plasticizer(s) other than the liquid phosphate plasticizer are chosen from the group consisting of polyolefinic oils, naphthenic oils, paraffinic oils.
• plasticizing hydrocarbon resin(s) are chosen from the group consisting of cyclopentadiene homopolymer or copolymer resins, dicyclopentadiene homopolymer or copolymer resins, terpene homopolymer or copolymer resins, C5 fraction homopolymer or copolymer resins, C 9 fraction homopolymer or copolymer resins, alpha-methyl styrene homopolymer or copolymer resins, and the mixtures thereof.
• the tires of the invention are particularly intended to equip passenger motor vehicles, including 4x4 (four-wheel drive) vehicles and SUV (Sport Utility Vehicles) vehicles, and also industrial vehicles in particular chosen from vans and heavy duty vehicles (i.e., bus or heavy road transport vehicles (lorries, tractors, trailers).
• 4x4 four-wheel drive
• SUV Sport Utility Vehicles
• industrial vehicles in particular chosen from vans and heavy duty vehicles (i.e., bus or heavy road transport vehicles (lorries, tractors, trailers).
• treads and constituent rubber compositions of these treads of the tires according to the invention are characterized, after curing, as indicated below.
• a principle of the friction test is based on a block of a rubber composition that slides at a given speed (for example equal to 500 mm/s) over a snow track with an imposed load (for example: 2 to 3 bar).
• the forces generated in a direction of travel (Fx) of the block and in another direction perpendicular to the travel (Fz) are measured.
• the Fx/Fz ratio determines the friction coefficient of the test specimen on the snow.
• any interval of values denoted by the expression "between a and b" represents the range of values extending from greater than a to less than b (that is to say, limits a and b excluded) whereas any interval of values denoted by the expression “from a to b” means the range of values extending from a up to b (that is to say, including the strict limits a and b).
• the rubber composition of the tread of the snow tire according to the invention is based on at least more than 50 and up to 100 phr of a first diene elastomer chosen from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes and the mixtures thereof, a reinforcing filler, more than 10 phr and less than 100 phr a liquid phosphate plasticizer having a glass transition temperature less than -80°C.
• the expression "based on” should be understood in the present application to mean a composition comprising the mixture and/or the product of the reaction of the various constituents used, some of the constituents being able or intended to react together, .at least partly, during the various manufacturing phases of the composition, in particular during the vulcanization (curing).
• a "diene” elastomer (or “rubber”, the two terms being considered to be synonymous) should be understood, in a known manner, to mean an (one or more is understood) elastomer resulting at least in part (i.e., a homopolymer or a copolymer) from diene monomers (monomers bearing two carbon-carbon double bonds which may or may not be conjugated).
• diene elastomers can be classified in a known way into two categories: those "essentially unsaturated” and those "essentially saturated”.
• Butyl rubbers such as, for example copolymers of dienes and of a-olefins of EPDM type, come within the category of essentially saturated diene elastomers, having a content of units of diene origin which is low or very low, always less than 15% (mol %).
• essentially unsaturated diene elastomer is understood to mean a diene elastomer resulting at least in part from conjugated diene monomers, having a content of units of diene origin (conjugated dienes) which is greater than 15% (mol %).
• highly unsaturated diene elastomer is understood to mean in particular a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.
• An essential feature of the rubber composition of the tread of the snow tire of the invention is to use as a first diene elastomer base, more than 50 and up to 100 phr (it should be remembered that "phr" means parts by weight per 100 parts of elastomer) of a diene elastomer chosen from the group consisting of natural rubber (NR.), synthetic polyisoprenes (IR), polybutadienes (BR) and the mixtures thereof, and to use as another (or second) diene elastomer, optionally, 0 to less than 50 phr of the other diene elastomer.
• a diene elastomer base more than 50 and up to 100 phr (it should be remembered that "phr” means parts by weight per 100 parts of elastomer) of a diene elastomer chosen from the group consisting of natural rubber (NR.), synthetic polyisoprenes (IR), polybutadienes (BR) and the mixtures
• the following are preferably suitable: synthetic polyisoprenes in those of cis-1 ,4- type, in particular those having a content (mol%) of cis- l ,4-bonds of greater than 90%, preferably of greater than or equal to 98%, polybutadienes, in particular those having a content of 1,2-units of between 4% and 80% or those having a content of cis- 1 ,4 units of greater than 80%, preferably those having a content of cis-1 ,4 bonds which is greater than 90%.
• the first diene elastomer is natural rubber and/or a synthetic polyisoprene.
• the synthetic polyisoprene has a content (mol%) of cis- l ,4-bonds of greater than 90%, more preferably of greater than or equal to 98%.
• the second diene elastomer is polybutadiene, more particularly the polybutadiene having a content of cis- 1 ,4 bonds which is greater than 90%.
• the first diene elastomer is a polybutadiene, preferably the polybutadiene having a content of cis- 1 ,4 bonds which is greater than 90%. More preferably, the second diene elastomer is natural rubber or a synthetic polyisoprene, still more preferably the synthetic polyisoprene having a content (mol%) of cis- l ,4-bonds of greater than 90%, particularly of greater than or equal to 98%. [0022] According to a more preferred embodiment, the first diene elastomer is a synthetic polyisoprene. Preferably, the synthetic polyisoprene has a content (mol%) of cis- 1 ,4- bonds of greater than 90%, more preferably of greater than or equal to 98%.
• the other (second) diene elastomer other than the first dine elastomer is chosen from the group consisting of butadiene copolymers, isoprene copolymers (preferably other than butyl) and the mixtures thereof.
• Such copolymers are more preferably chosen from the group consisting of butadiene/styrene copolymers (SBR), isoprene/butadiene copolymers (BIR), isoprene/styrene copolymers (SIR), isoprene/butadiene/styrene copolymers (SBIR) and the mixtures thereof.
• Such copolymers are still more preferably butadiene/styrene copolymers (SBR), in particular bearing at least one (i.e., one or more) SiOR function, R being hydrogen or hydrocarbon radical, as described in an application WO 2012/069565.
• SBR butadiene/styrene copolymers
• butadiene/isoprene copolymers in particular those having an isoprene content of between 5% and 90% by weight and a glass transition temperature ("Tg"- measured according to ASTM D 3418-82) of -40°C to -80°C
• Tg glass transition temperature
• isoprene/styrene copolymers in particular those having a styrene content of between 5% and 50% by weight and a Tg of between -25°C and -50°C are suitable in particular.
• butadiene/styrene/isoprene copolymers those having a styrene content of between 5% and 50% by weight and more particularly of 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 of between 20% and 40%, a content of 1 ,2-units of the butadiene part of between 4% and 85%, a content of trans- 1 ,4-un its of the butadiene part of between 6% and 80%, a content of 1 ,2 plus 3,4-units of the isoprene part of between 5% and 70% and a content of trans- 1 ,4-units of the isoprene part of between 10% and 50%, and more generally any butadiene/styrene/isoprene copolymer having a Tg of between -20°C and -70°C, are examples of the isoprene
• the first diene elastomer has a Tg less than -50°C (notably between - 100°C and -50°C), more preferably less than -55°C (notably between -90°C and - 55°C), still more preferably equal to or less than -60°C (notably from -80°C to - 60°C).
• the content of the first diene elastomer is preferably within a range from 60 to 100 phr (0 to 40 phr of the other elastomer optionally), more preferably from 80 to 100 phr (0 to 20 phr of the other elastomer optimally), still more preferably 100 phr.
• Use may be made of any type of reinforcing filler known for its capabilities of reinforcing a rubber composition which can be used for the manufacture of tires, for example an organic filler, such as carbon black, or a reinforcing inorganic filler, such as silica, with which a coupling agent is combined in a known way.
• an organic filler such as carbon black
• a reinforcing inorganic filler such as silica
• Such a reinforcing filler typically consists of nano particles, the mean size (by weight) of which is less than 500 nm, generally between 20 and 200 nm, in particular and preferably between 20 and 150 nm.
• J Al l carbon blacks in particular blacks of the HAF, ISAF or SAF type, conventionally used in treads for tires ("tire-grade" blacks) are suitable as carbon blacks. Mention will more particularly be made, among the latter, of the reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as, for example, the N l 15, N 134, N234, N326, N330, N339, N347 or N375 blacks.
• the carbon blacks might, for example, be already incorporated in the isoprene elastomer in the form of a masterbatch (see, for example, Applications WO 97/36724 or W0 99/ 1 6600).
• organ ic fillers other than carbon blacks Mention may be made, as examples of organ ic fillers other than carbon blacks, of the functionalized polyvinyl organic fillers as described in Applications WO 2006/ 069792, WO 2006/069793, WO2008/003434 and WO2008/003435.
• the term "reinforcing inorganic filler” should be understood here as meaning any inorganic or mineral filler, whatever its color and its origin (natural or synthetic), also known as “white filler” or sometimes “clear fil ler” in contrast to carbon black, capable of reinforcing by itself, without means other than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words capable of replacing, in its reinforcing role, a conventional tire-grade carbon black; such a filler is generally characterized, in a known way, by the presence of hydroxy! (-OH) groups at its surface.
• -OH hydroxy!
• Mineral fillers of the sil iceous type in particular si lica (Si0 2 ), or of the aluminous type, in particular alumina (A I 2O3), are suitable in particular as reinforcing inorganic fillers.
• the silica used can be any reinforcing silica known to a person skilled in the art, in particular any precipitated or pyrogenic silica exhibiting a BET surface and a CTAB specific surface both of less than 450 m 2 / g, preferably from 30 to 400 m 3 /g. in particular between 60 and 300 m 2 / g.
• Mention wil l be made, as highly dispersible ("HD precipitated silicas"), for example, of the Ultrasil 7000 and Ultrasil 7005 silicas from Evonik, the Zeosi l 1 165 MP, 1 135 MP and 1 1 15 MP silicas from Rhodia, the Hi-Sil EZ 1 50G silica from PPG, the Zeopol 8715, 8745 and 8755 silicas from Huber.
• highly dispersible for example, of the Ultrasil 7000 and Ultrasil 7005 silicas from Evonik, the Zeosi l 1 165 MP, 1 135 MP and 1 1 15 MP silicas from Rhodia, the Hi-Sil EZ 1 50G silica from PPG, the Zeopol 8715, 8745 and 8755 silicas from Huber.
• the rubber composition of the tread of the snow tire according to the invention comprises 40 to 200 phr of a reinforcing filler comprising an inorganic filler, a carbon black or the mixture thereof, wherein a content of the carbon black is less than 20 phr.
• the content of total reinforcing filler is within a range from 50 to 1 50 phr, in particular from 60 to 140 phr.
• the reinforcing filler comprises predominantly an inorganic fi ller, in particular silica; in such a case, the inorganic fi ller, in particular silica, is present at a content preferably of greater than or equal to 40 phr, in combination or not with carbon black in a minor amount; the carbon black, when it is present, is used at a content of less than 20 phr, preferably less than 10 phr (for example between 0.5 and 20 phr, in particular between 2 and 10 phr).
• the coloring properties (black pigmenting agent) and UV-stabilizing properties of the carbon blacks are benefited from, without, moreover, adversely affecting the typical performances provided by the reinforcing inorganic fil ler.
• an at least bifunctional coupling agent (or bonding agent) intended to provide a satisfactory connection, of chemical and/or physical nature, between the inorganic filler (surface of its particles) and the diene elastomer.
• Use is made, in particular, of bifunctional organosilanes or polyorganosiloxanes.
• silane polysulphides referred to as “symmetrical” or “asymmetrical” depending on their specific structure, as described, for example, in Applications WO 03/002648 (or US 2005/01665 1 ) and WO 03/002649 (or US 2005/016650).
• x is an integer from 2 to 8 (preferably from 2 to 5);
• A is a divalent hydrocarbon radical (preferably, C pC ig alkylene groups or C6-C 12 arylene groups, more particularly C 1 -C t0 , in particular C 1-C4, alkylenes, especially propylene);
• the R 1 radicals which are unsubstituted or substituted and identical to or different from one another, represent a C i-C ( 8 alkyl. C 5 -C
• the R 2 radicals which are iinsubstituted or substituted and identical to or different from one another, represent a C C i8 alkoxyl or C 5 -C
• silane polysulphides of bis((C
• the content of coupling agent is preferably between 2 and 20 phr, more preferably between 3 and 15 phr.
• a reinforcing filler of another nature might be used as filler equivalent to the reinforcing inorganic filler described in the present section, provided that this reinforcing filler is covered With an inorganic layer, such as silica, or else comprises, at its surface, functional sites, in particular hydroxyls, requiring the use of a coupling agent in order to form the connection between the filler and the elastomer.
• an inorganic layer such as silica
• the rubber composition of the tread of the snow tire according to the invention has the other essential characteristic of comprising more than 10 phr and less than 100 phr a liquid phosphate plasticizer.
• the liquid phosphate plasticizer is l iquid at 20°C (under atmospheric pressure) by definition.
• the role of the liquid phosphate plasticizer is to soften the matrix by diluting the elastomer and the reinforcing filler.
• the content of the liquid phosphate plasticizer is preferably more than 20 phr and less than 80 phr, more preferably from 30 to 60 phr.
• the liquid phosphate plasticizer has a Tg (glass transition temperature, measured according to standard ASTM D3418) less than - 80°C (notably between -80°C and - 130°C), preferably less than -90°C (notably between -90°C and - 120°C), more preferably less than -100°C (notably between - 100°C and - 1 10°C).
• liquid phosphate plasticizers for example, of those that contain between 12 and 30 carbon atoms, for example trialkyi phosphate having between 12 and 30 carbon atoms.
• the number of carbon atoms of trialkyi phosphate should be taken to mean the total number of carbon atoms of three alkyl groups.
• the three alkyl groups of trialkyi phosphate may be the same or different each other.
• alkyl used herein refers to a straight or branched alkyl group, which may contain a hetero atom such as an oxygen atom in its chain, or which may be substituted with a halogen atom such as fluorine, chlorine, bromine or iodine.
• the trialkyi phosphate may have one or two phenyl groups of instead of alkyl groups.
• the liquid phosphate plasticizer is preferably trialkyi phosphate having between 12 and 30 carbon atoms.
• trialkyi phosphate of an oil selected from the group consisting of trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate (especially, tris(2-ethylhexyl) phosphate), tris(2-butoxyethyl) phosphate, tris(2-chloroethyl) phosphate, 2-ethylhexyl diphenyl phosphate, and the mixtures thereof.
• an oil selected from the group consisting of trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate (especially, tris(2-ethylhexyl) phosphate), tris(2-butoxyethyl) phosphate, tris(2-chloroethyl) phosphate, 2-ethylhexyl diphenyl phosphate, and the mixtures thereof.
• the liquid phosphate plasticizer is tris(2- ethylhexyl) phosphate.
• the rubber composition of the tread of the snow tire according to the invention is devoid or comprises less than 30 phr, preferably less than 20 phr, more preferably less than 10 phr, of any l iquid plasticizer(s) other than the liquid phosphate plasticizer.
• any extending oil whether of aromatic or non-aromatic nature, any liquid plasticizing agent known for its plasticizing properties with regard to diene elastomers, can be used as the liquid plasticizer other than the liquid phosphate plasticizer.
• these plasticizers or these oils which are more or less viscous, are liquids (that is to say, as a reminder, substances that have the ability to eventual ly take on the shape of their container), as opposed, in particular, to plasticizing hydrocarbon resins which are by nature solid at ambient temperature.
• the liquid plasticizer(s) (other than the liquid phosphate plasticizer) chosen from the group consisting of naphthenic oils (low or high viscosity, in particular hydrogenated or otherwise), polyolefinic oils, naphthenic oils, paraffinic oils, Distillate Aromatic Extracts (DAE) oils, Medium Extracted Solvates (MES) oils, Treated Distillate Aromatic Extracts (TDAE) oils, Residual Aromatic Extracts (RAE) oils, Treated Residual Aromatic Extracts (TRAE) oils.
• naphthenic oils low or high viscosity, in particular hydrogenated or otherwise
• polyolefinic oils naphthenic oils
• paraffinic oils Distillate Aromatic Extracts (DAE) oils
• MES Medium Extracted Solvates
• TDAE Treated Distillate Aromatic Extracts
• RAE Residual Aromatic Extracts
• TCE Treated Residual Aromatic Extracts
• SRAE Safety Residual Aromatic Extracts
• mineral oils vegetable oils
• vegetable oils ether plasticizers, ester plasticizers other than phosphate plasticizers, sulphonate plasticizers and the mixtures thereof are particularly suitable.
• the liquid plasticizer(s) are vegetable oils as described, for example, in an application WO 2012/069565.
• the rubber composition of the tread of the snow tire according to the invention is devoid or comprises less than 60 phr (that is from 0 to less than 60phr), preferably less than 50 phr (that is from 0 to 50 phr), more preferably less than 40 phr (that is from 0 to 40 phr) of any plasticizing hydrocarbon resin(s).
• Hydrocarbon resin(s) are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but which may comprise other types of atoms, which can be used in particular as plasticizer or tackifiers in polymeric matrices. They are by nature miscible (i.e., compatible) in the contents used with the polymer compositions for which they are intended, so as to act as true diluents. They have been described for example in the work entitled "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617- 9), Chapter 5 of which is devoted to their applications, especially in rubber tyres (5.5.
• Rubber Tires and Mechanical Goods may be aliphatic, cycloaliphatic, aromatic, hydrogenated aromatic, of the aliphatic/aromatic type, i.e., based on aliphatic and/ or aromatic monomers. They may be natural or synthetic resins, whether or not based on petroleum (if such is the case, they are also known as petroleum resins). Their Tg is preferably above 0°C, in particular above 20°C (usually between 30°C and 95°C).
• these hydrocarbon resins may also be termed thermoplastic resins in the sense that they soften when heated and may thus be molded. They may also be defined by a softening point or temperature.
• the softening point of a hydrocarbon resin is generally about 50°C to 60°C higher than its Tg value. The softening point is measured according to standard ISO 4625 (ring-and-ball method).
• the macrostructure (Mw, Mn and Ip) is determined by size exclusion chromatography (SEC) as indicated below.
• SEC analysis for example, consists in separating the macromolecules in solution according to their size through columns filled with a porous gel; the molecules are separated according to their hydrodynamic volume, the bulkiest being eluted first.
• the sample to be analyzed is simply dissolved beforehand in an appropriate solvent, tetrahydrofuran, at a concentration of 1 g/liter.
• the solution is then filtered through a filter with a porosity of 0.45 ⁇ , before injection into the apparatus.
• the apparatus used is, for example, a "Waters Alliance" chromatographic line according to the following conditions:
• elution solvent is tetrahydrofuran
• flow rate 1 ml/min
• injected volume 100 ⁇ ⁇ ;
• a Moore calibration is carried out with a series of commercial polystyrene standards having a low Ip (less than 1.2), with known molar masses, covering the range of masses to be analyzed.
• the weight-average molar mass (Mw), the number-average molar mass (Mn) and the polydispersity index (Ip:Mw/Mn) are deduced from the data recorded (curve of distribution by mass of the molar masses).
• All the values for molar masses shown in the present application are thus relative to calibration curves produced with polystyrene standards.
• the plasticizing hydrocarbon resin exhibits at least any one, more preferably all, of the following characteristics:
• a Tg of above 25°C in particular between 30°C and 100°C, more preferably above 30°C (in particular between 30°C and 95°C);
• Mn a number-average molar mass between 400 and 2000 g/mol, preferably between 500 and 1500 g/mol;
• hydrocarbon resin(s) examples include those chosen from the group consisting of cyclopentadiene (abbreviated to CPD) homopolymer or copolymer resins, dicyclopentadiene (abbreviated to DCPD) homopolymer or copolymer resins, terpene homopolymer or copolymer resins, C 5 fraction homopolymer or copolymer resins, C fraction homopolymer or copolymer resins, alpha-methyl styrene homopolymer or copolymer resins and the mixtures thereof.
• CPD cyclopentadiene
• DCPD dicyclopentadiene
• terpene homopolymer or copolymer resins terpene homopolymer or copolymer resins
• C 5 fraction homopolymer or copolymer resins C fraction homopolymer or copolymer resins
• alpha-methyl styrene homopolymer or copolymer resins alpha-methyl
• Use is more preferably made, among the above copolymer resins, of those chosen from the group consisting of (D)CPD/vinylaromatic copolymer resins, (D)CPD/terpene copolymer resins, (D)CPD/C 5 fraction copolymer resins, (D)CPD/Cg fraction copolymer resins, terpene/vinylaromatic copolymer resins, terpene/phenol copolymer resins, C 5 fraction/vinyl-aromatic copolymer resins, C 9 fraction/vinylaromatic copolymer resins, and the mixtures thereof.
• pene' combines here, in a known way, the a-pinene, ⁇ -pinene and limonene monomers; use is preferably made of a limonene monomer, which compound exists, in a known way, in the form of three possible isomers: L-limonene ( laevorotatory enantiomer), D-l imonene (dextrorotatory enantiomer) or else dipentene, the racemate of the dextrorotatory and laevorotatory enantiomers.
• the vinylaromatic compound is styrene or a vinylaromatic monomer resulting from a C 9 fraction (or more generally from a Cg to C IO fraction).
• the vinylaromatic compound is the minor monomer, expressed as molar fraction, in the copolymer under consideration.
• resins selected from the group consisting of (D)CPD homopolymer resins, (D)CPD/ styrene copolymer resins, polylimonene resins, limonene/ styrene copolymer resins, limonene/D(CPD) copolymer resins, C 5 fraction/styrene copolymer resins, C 5 fraction /C 9 fraction copolymer resins and blends of these resins.
• the designation "resin” is reserved in the present application, by definition, for a compound which is solid at ambient temperature (20°C under atmosphere pressure), in contrast to a l iquid plasticizing compound, such as an oil.
• the rubber compositions of the treads of the tires in according to the invention also comprise all or a portion of the usual additives generally used in the elastomer compositions intended for the manufacture of treads for tires, in particular for snow tires or winter tires, such as, for example, protection agents, such as antiozone waxes, chemical antiozonants, antioxidants, reinforcing resins, methylene acceptors (for example phenol ic novolak resin) or methylene donors (for example HMT or H3M), a crosslinking system based either on sulphur or on donors of sulphur and/or per oxide and/or bismaleimides, vulcanization accelerators, or vulcanization activators.
• protection agents such as antiozone waxes, chemical antiozonants, antioxidants, reinforcing resins, methylene acceptors (for example phenol ic novolak resin) or methylene donors (for example HMT or H3M)
• methylene acceptors for example phenol ic novolak
• compositions can also comprise coupling activators when a coupling agent is used, agents for covering the inorganic filler or more generally processing aids capable, in a known way, by virtue of an improvement in the dispersion of the filler in the rubber matrix and of a lowering of the viscosity of the compositions, of improving their property of processing in the raw state; these agents are, for example, hydrolysable silanes, such as alkylalkoxysilanes, polyols, polyethers, amines, or hydroxylated or hydrolysable polyorganosiloxanes. -5.
• the rubber compositions of the treads of the snow tires according to the invention may be manufactured in appropriate mixers using two successive preparation phases well known to a person skilled in the art: a first phase of thermomechanical working or kneading (referred to a as “non-productive” phase) at high temperature, up to a maximum temperature of between 1 10°C and 190°C, preferably between 130°C and 180°C, followed by a second phase of mechanical working (referred to as “productive” phase) at a lower temperature, typically of less than 1 10°C, for example between 40°C and 100° C, finishing phase during which the crosslinking or vulcanization system is incorporated.
• a first phase of thermomechanical working or kneading referred to a as "non-productive" phase
• productive phase a second phase of mechanical working
• a process which can be used for the manufacture of such compositions comprises, for example and preferably, the following steps:
• the first (non-productive) phase is carried out in a single thermomechanical stage during which all the necessary constituents are introduced into an appropriate mixer, such as a standard internal mixer, followed, in a second step, for example after kneading for 1 to 2 minutes, by the other additives, optional additional filler-covering agents or processing aids, with the exception of the crosslinking system.
• the total kneading time, in this non-productive phase is preferably between 1 and 15 min.
• the crosslinking system is then incorporated at low temperature (for example, between 40°C and 100°C), generally in an external mixer, such as an open mill;
• the combined mixture is then mixed (the second (productive) phase) for a few minutes, for example between 2 and 15 min.
• the crosslinking system proper is preferably based on sulphur and on a primary vulcanization accelerator, in particular on an accelerator of sulphenamide type.
• a primary vulcanization accelerator in particular on an accelerator of sulphenamide type.
• various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (in particular diphenylguanidine), and the like, incorporated during the first nonproductive phase and/or during the productive phase.
• the content of sulphur is preferably between 0.5 and 3.0 phr, and that of the primary accelerator is preferably between 0.5 and 5.0 phr.
• Use may be made, as accelerator (primary or secondary) of any compound capable of acting as accelerator of the vulcanization of diene elastomers in the presence of sulphur, in particular accelerators of the thiazoles type and their derivatives, accelerators of thiurams types, or zinc dithiocar bamates.
• accelerators are more preferably chosen from the group consisting of 2-mercaptobenzothiazyl disulphide (abbreviated to "MBTS”), N-cycIohexyl-2-benzothiazole sulphenamide (abbreviated to “CBS”), N,N-dicyclohexyl-2 benzothiazolesulphenamide (“DCBS”), N-ter't-butyl-2-ben zothiazolesulphenamide (“TBBS”), N-tert-butyl-2 benzothiazolesulphenimide (“TBSI”), zinc dibenzyldithiocarbamate (“ZBEC”). Tetrabenzylthiuram disulfide (“TBZTD”) and the mixtures thereof.
• MBTS 2-mercaptobenzothiazyl disulphide
• CBS N-cycIohexyl-2-benzothiazole sulphenamide
• DCBS N,N-dicyclohexyl-2 benzothiazoles
• the final composition thus obtained is subsequently calendered, for example in the form of a sheet or of a plaque, in particular for laboratory characterization, or else extruded in the form of a rubber profiled element which can be used directly as snow tire tread or winter tire tread.
• the vulcanization (or curing) is carried out in a known way at a temperature generally of between 1 10°C and 190°C for a sufficient time which can vary, for example, between 5 and 90 min depending in particular on the curing temperature, the vulcanization system adopted and the vulcanization kinetics of the composition under consideration.
• the rubber compositions of the treads of the snow tires according to the invention can constitute all or a portion only of the tread in accordance with the invention, in the case of a tread of composite type formed from several rubber compositions of different formulations.
• the invention relates to the rubber compositions and to the treads described above, both in the raw state (i.e., before curing) and in the cured state (i.e., after crosslinking or vulcanization).
• the invention also applies to the cases where the rubber compositions described above form only one part of treads of composite or hybrid type, especially those consisting of two radially superposed layers of different formulations (referred to as "cap-base” construction), that are both patterned and intended to come into contact with the road when the tire is rolling, during the service life of the latter.
• the base part of the formulation described above could then constitute the radially outer layer of the tread intended to come into contact with the ground from the moment when a new tire starts rolling, or on the other hand its radially inner layer intended to come into. contact with the ground at a later stage.
• the reinforcing filler for example a reinforcing inorganic filler, such as silica, and its associated coupling agent
• the liquid phosphate plasticizer for example a reinforcing inorganic filler, such as silica, and its associated coupling agent
• the liquid phosphate plasticizer for example a reinforcing inorganic filler, such as silica, and its associated coupling agent
• the diene elastomer(s) and the various other ingredients with the exception of the vulcanization system
• compositions thus obtained were subsequently calendered, either in the form of sheets (thickness of 2 to 3 mm) or of fine sheets of rubber, for the measurement of their-physical or mechanical properties, or in the form of profiled elements which could be used directly, after cutting and/or assembling to the desired dimensions, for example as tire semi-finished products, in particular as tire treads.
• compositions based on a diene elastomer (IR) are compared, the three compositions are reinforced with a blend of silica and carbon black with 40phr of a tris(2-ethylhexyl)phosphate (as a liquid phosphate plasticizer) or of another liquid plasticizer (MES oils or TDAE oils instead of the liquid phosphate plasticizer) conventionally used for snow tires or winter tires:
• composition C- 1 composition with MES oils (a first reference);
• Composition C-2 composition with TDAE oils (a comparative example);
• composition C-3 composition according to the present invention with the liquid phosphate plasticizer
• composition C-3 according to the invention has equivalent values of shore A hardness and of moduli in the extension compared to that of the first reference of C- 1 (and also the comparative example C-2). This is a general indicator of a good road performance maintained on the snow tire of the invention.
• compositions C-4, C-5 and C-6 formulations of which are expressed in Table 4 were also subjected to the above friction test.
• the results are expressed in Table 5.
• the composition C-5, based on natural rubber, according to the invention has a certain increase (5%)
• the composition C-6, based on a synthetic polyisoprene, according to the invention has a further remarkable increase ( 13%) in the friction coefficient on the snow, relative to the composition C-4 (the second reference).
• the results of the tests commented above show that the specific rubber composition of the tread of the snow tire according to the present invention gives the snow tires and their treads a better and improved grip on snowy ground.

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• 2015
  • 2015-12-15 EP EP15870107.8A patent/EP3234001A4/en not_active Ceased
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