CA2971124C - A snow tire having a tread comprising a rubber composition - Google Patents

A snow tire having a tread comprising a rubber composition Download PDF

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CA2971124C
CA2971124C CA2971124A CA2971124A CA2971124C CA 2971124 C CA2971124 C CA 2971124C CA 2971124 A CA2971124 A CA 2971124A CA 2971124 A CA2971124 A CA 2971124A CA 2971124 C CA2971124 C CA 2971124C
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liquid
tire according
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CA2971124A1 (en
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Aya HARANO
Yuji Kanno
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Compagnie Generale des Etablissements Michelin SCA
Michelin Recherche et Technique SA France
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Compagnie Generale des Etablissements Michelin SCA
Michelin Recherche et Technique SA France
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/34Silicon-containing compounds
    • C08K3/36Silica
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60CVEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B60C1/0016Compositions of the tread
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/49Phosphorus-containing compounds
    • C08K5/51Phosphorus bound to oxygen
    • C08K5/52Phosphorus bound to oxygen only
    • C08K5/521Esters of phosphoric acids, e.g. of H3PO4
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/54Silicon-containing compounds
    • C08K5/548Silicon-containing compounds containing sulfur
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L7/00Compositions of natural rubber
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/02Elements
    • C08K3/04Carbon
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/0008Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/0016Plasticisers

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Tires In General (AREA)

Abstract

A snow tire with an improved grip on snow ground includes a tread formed of a rubber composition. The rubber composition comprises 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.

Description

DESCRIPTION
Title of Invention A SNOW TIRE HAVING A TREAD COMPRISING A RUBBER
COMPOSITION
1. FIELD OF THE INVENTION
[00011 The invention relates to the tires having treads suitable for snow tires or winter tires, capable of rolling over ground surfaces covered with snow.
2. BACKGROUND
[00021 As is known, 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.
[00031 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.
3. BRIEF DESCRIPTION OF THE INVENTION
[0004] On the continuing their research, the inventors have discovered a novel and specific rubber composition for a snow tire tread, which makes it possible to achieve the above objective to improve a grip of a snow tire on snow.
[0005] Thus, according to a first general aspect of the disclosure, there is provided a snow tire having a tread comprising a rubber composition comprising at least: from 80 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 20 phr of a second diene elastomer which is different from the first 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;
and more than 10 phr and less than 100 phr of a liquid phosphate plasticizer having a glass transition temperature measured according to standard ASTM D3418 of less than -80 C, and the liquid phosphate plasticizer being liquid at 20 C under atmospheric pressure.
For instance, a 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.
[0006] Moreover, aspects of the present invention can be as follows.

Date Recue/Date Received 2022-02-08 [1]. 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 a second diene elastomer which is different from the first 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; and 2a Date Recue/Date Received 2022-02-08 - more than 10 phr and less than 100 phr of a liquid phosphate plasticizer having a glass transition temperature less than -80 C.
[2] The tire according to [1], wherein the first diene elastomer has a glass transition temperature less than -50 C.
[31 The tire according to [1] or [2], wherein the content of the first diene elastomer is within a range from 60 to 100 phr.
[4] The tire according to any one of [1] to [3], wherein the first diene elastomer is natural rubber and/or a synthetic polyisoprene.
[51 The tire according to any one of [1] to [3], wherein the first diene elastomer is a synthetic polyisoprene.
[6] The tire according to [4] or [5], wherein the synthetic polyisoprene has a content of cis-1,4 bonds of greater than 90%.
[71 The tire according to any one of [1] to [3], wherein the first diene elastomer is a polybutadiene.
[8] The tire according to any one of [1] to [7], wherein the second diene elastomer is chosen from the group consisting of butadiene copolymers, isoprene copolymers and the mixtures thereof.
[91 The tire according to any one of [1] to [8], wherein the content of the reinforcing filler is within a range from 50 to 150 phr.
[10] The tire according to any one (A[1] to [9], wherein the inorganic filler is silica.
[11] The tire according to any one of [1] to [10], wherein the content of liquid phosphate plasticizer is more than 20 phr and less than 80phr.
[12] The tire according to any one of [1] to [11], wherein the liquid phosphate plasticizer has a glass transition temperature less than -90 C.

[13] The tire according to any one of [1] to [12], wherein the liquid phosphate plasticizer is a trialkyl phosphate having between 12 and 30 carbon atoms.
[14] The tire according to any one of [1] to [13], wherein the liquid phosphate plasticizer is tris(2-ethylhexyl) phosphate.
[15] The tire according to any one of [1] to [14], wherein the rubber composition is devoid or comprises less than 30 phr of liquid plasticizer(s) other than the liquid phosphate plasticizer.
[16] The tire according to [15], wherein the liquid plasticizer(s) other than the liquid phosphate plasticizer are chosen from the group consisting of 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, Safety Residual Aromatic Extracts (SRAE) oils, mineral oils, vegetable oils, ether plasticizers, ester plasticizers other than phosphate plasticizers, sulphonate plasticizers and the mixtures thereof.
[17] The tire according to any one of [1] to [16], wherein the rubber composition is devoid or comprises less than 60 phr of plasticizing hydrocarbon resin(s).
[18] The tire according to [14 wherein the 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, C9 fraction homopolymer or copolymer resins, alpha-methyl styrene homopolymer or copolymer resins, and the mixtures thereof.

[00071 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).
100081 The invention and its advantages will be easily understood in the light of the description and implementation examples which follow.
4. MEASUREMENTS AND TESTS USED
[00091 The treads and constituent rubber compositions of these treads of the tires according to the invention are characterized, after curing, as indicated below.
4-1. Tensile tests [00101 These tensile tests make it possible to determine the elasticity stresses and the properties at break. Unless otherwise indicated, they are carried out in accordance with French Standard NF T 46-002 of September 1988. The nominal secant moduli (or apparent stresses, in IV[Pa) are measured in second elongation (i.e., after a cycle of accommodation to the degree of extension expected for the measurement itself) at 10% elongation (denoted M10), 100% elongation (denoted M100) and 300%
elongation (denoted M300). All these tensile measurements are carried out under the standard conditions of temperature (23 2 C) and hygrometry (50 5% relative humidity), according to French Standard NF T 40-101 (December 1979).
4-2. Shore A hardness [00111 The Shore A hardness of the compositions after curing is assessed in accordance with Standard ASTM D 2240-86.

4-3. Friction test with rubber block on snow [00121 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. This test, the principle of which is well known to a person skilled in the art (see, for example, patent applications EP 1 052 270 and EP 1 505 112) makes it possible to evaluate, under representative conditions, the grip on ice/snow which would be obtained after a running test on a vehicle fitted with tires whose tread is composed of the same rubber compositions.
5. DETAILED DESCRIPTION OF THE INVENTION
[00131 In the present description, unless expressly indicated otherwise, all the percentages (%) shown are % by weight. Moreover, any interval of values denoted by the expression "between a and 6" 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).
[00141 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.

[0015] 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).
5-1. Diene elastomer [0016] 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).
[00171 These 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 %). In contrast, 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 %). In the category of "essentially unsaturated" diene elastomers, "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%.
[0018] 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 SO and up to 100 phr (it
7
8 should be remembered that "phi" 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.
[00191 The following are preferably suitable: synthetic polyisoprenes in those of cis-1,4-type, in particular those having a content (mol%) of cis-1,4-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%.
[00201 According to a preferred embodiment, the first diene elastomer is natural rubber and/or 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%. Particularly, the second diene elastomer is polybutadiene, more particularly the polybutadiene having a content of cis-1,4 bonds which is greater than 90%.
[00211 According to another preferred embodiment, 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-1,4-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%.
[0023] According to one embodiment, 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.
[0024] In the case of 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, or 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.
[0025] In the case of 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 oft ,2-units of the butadiene part of between 4% and 85%, a content of trans-1,4-units of the butadiene part of
9 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 suitable in particular.
[0026] Synthetic elastomers other than diene elastomers, indeed even polymers other than elastomers, for example thermoplastic polymers, might be combined, in a minor amount, with the diene elastomers of the compositions of the invention.
[0027] Preferably, 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).
[0028] Preferably, 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.
5-2. Reinforcing Filler [0029] 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.
100301 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.

[0031] All carbon blacks, in particular blacks of the High Abrasion Furnace (HAF), Intermediate Super Abrasion Furnace (ISAF) or Super Abrasion Furnace (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 N115, N134, N234, N326, N330, N339, N347 or N375 ASTM-designated 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 WO

16600).
[0032] Mention may be made, as examples of organic fillers other than carbon blacks, of the functionalized polyvinyl organic fillers as described in Applications WO 2006/

069792, WO 2006/069793, W02008/003434 and W02008/003435.
[0033] 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 filler" 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 hydroxyl (-OH) groups at its surface.
[0034] Mineral fillers of the siliceous type, in particular silica (SiO2), or of the aluminous type, in particular alumina (A1203), 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 m2/ g, preferably from 30 to 400 m2/g,
11 Date Recue/Date Received 2022-02-08 in particular between 60 and 300 m2/ g. Mention will be made, as highly dispersible ("HD precipitated silicas"), for example, of the UltrasilTM 7000 and UltrasilTM 7005 silicas from Evonik, the ZeosilTM 1165 MP, 1135 MP and 1115 MP silicas from Rhodia, the HiSi1TM EZ150G silica from PPG, the ZeopolTM 8715, 8745 and 8755 silicas from Huber. Mention may be made, as examples of reinforcing aluminas, of the "Baikalox Al2STM or "Baikalox CR125TM aluminas from Baikowski, the "APA-10ORDX"Tm alumina from Condea, the "Aluminoxid C" TM alumina from Degussa or the "AKP-G015"Tm alumina from Sumitomo Chemicals.
[0035] As another essential feature, 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.
[0036] Preferably, the content of total reinforcing filler (carbon black and/or reinforcing inorganic filler) is within a range from 50 to 150 phr, in particular from 60 to 140 phr.
[0037] According to a specific embodiment, the reinforcing filler comprises predominantly an inorganic filler, in particular silica; in such a case, the inorganic filler, 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). In the ranges indicated, 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 filler.
12 Date Recue/Date Received 2022-02-08 [0038] In order to couple the reinforcing inorganic filler to the diene elastomer, use is made, in a well-known way, of 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.
[00391 Use is made in particular of silane polysulphides, referred to as "symmetrical" or "asymmetrical" depending on their specific structure, as described, for example, in Applications WO 03/002648 (or US 2005/016651) and WO 03/002649 (or US
2005/016650). "Symmetrical" silane polysulphides corresponding to the following general formula (I):
[00401 (I) ,Z - A ¨ Sx - A - Z , in which:
[00411 x is an integer from 2 to 8 (preferably from 2 to 5);
[00421 A is a divalent hydrocarbon radical (preferably, C1-C18 alkylene groups or C6-C12 arylene groups, more particularly Ci-C10, in particular C1-C4, alkylenes, especially propylene);
100431 Z corresponds to one of the formulae below:
R1 Ri R2 ¨Si¨R1 = ¨Si¨R2 =
¨Si¨R2 , [0044] in which:
[0045] the RI radicals, which are unsubstituted or substituted and identical to or different /0 from one another, represent a C1-C18 alkyl, C5-C18 cycloalkyl or C6-C18 aryl group (Preferably, CI-C6 alkyl, cyclohexyl or phenyl groups, in particular C1-C4 alkyl groups, more particularly methyl and/or ethyl),
13 [0046] the R2 radicals, which are unsubstituted or substituted and identical to or different from one another, represent a CI-C18 alkoxyl or C5-C18 cycloalkoxyl group (preferably a group chosen from Ci-C8 alkoxyls and C5-C8 cycloalkoxyls, more preferably still a group chosen from C alkoxyls, in particular methoxyl and ethoxyl). are suitable in particular, without the above definition being limiting.
Mention will more particularly be made, as examples of silane polysulphides, of bis((C1-C4)alkoxyl(CI-C4)alkylsilyl(CI-C4)alkyl)polysulph ides (in particular disulphides, trisulphides or tetrasulphides), such as, for example, bis(3-trimethoxysilylpropyl) or bis(3-triethoxysilylpropyl) polysulphides. Use is in particular made, among these compounds, of bis(3-triethoxysilylpropyl) ,tetrasulphide, abbreviated to TESPT, of formula [(C2H50)3Si(CH2)3S2]:2, or bis(triethoxysilylpropyl)disulphide, abbreviated to TESPD, of formula [(C2HSO)3Si(CH2)3S12. Mention will also be made, as preferred examples, of bis(mono(Ci-C4)alkoxyldi(Ci-C4)alkylsilylpropyl) polysulphides (in particular disulphides, trisulphides or tetrasulphides), more particularly bis(monoethoxydimethylsilylpropyl) tetrasulphide, as described in Patent Application WO 02/083782 (or US 7 217 751).
[0047] Mention will in particular be made, as coupling agent other than alkoxysilane polysulphide, of bifunctional POSs (polyorganosiloxanes) or of hydroxysi lane /0 polysulphides (R2 = OH in the above formula (I)), such as described in Patent Applications WO 02/30939 (or US 6 774 255) and WO 02/31041 (or US
2004/051210), or of silanes or POSs carrying azodicarbonyl functional groups, such as described, for example, in Patent Applications WO 2006/125532, WO
2006/125533 and WO 2006/125534.
14 [0048] In the rubber composition of the tread of the snow tire according to the invention, the content of coupling agent is preferably between 2 and 20 phr, more preferably between 3 and 15 phr.
[0049] A person skilled in the art will understand that a reinforcing filler of another nature, in particular organic 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.
5-3. Liquid phosphate plasticizer [0050] 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 liquid 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.
[0051] Regarding the content of the liquid phosphate plasticizer, below the indicated minimum, the targeted technical effect is insufficient. Wherein the indicated maximum, there is an issue of cost of the liquid phosphate plasticizer and a risk of worsening processability. For these reasons, the content of the liquid phosphate 70 plasticizer is preferably more than 20 phr and less than 80 phr, more preferably from 30 to 60 phr.
[0052] Another essential feature of the rubber composition of the tread of the snow tire according to the invention is that 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 -110 C).
[0053] Mention may be made, as the liquid phosphate plasticizers for example, of those that contain between 12 and 30 carbon atoms, for example trialkyl phosphate having between 12 and 30 carbon atoms. The number of carbon atoms of trialkyl phosphate should be taken to mean the total number of carbon atoms of three alkyl groups. The three alkyl groups of trialkyl phosphate may be the same or different each other. The term "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 trialkyl phosphate may have one or two phenyl groups of instead of alkyl groups.
[0054] According to a preferred embodiment, the liquid phosphate plasticizer is preferably trialkyl phosphate having betwecn 12 and 30 carbon atoms.
[0055] Mention may be made, as examples of the trialkyl 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.
[0056] According to a more preferred embodiment, the liquid phosphate plasticizer is tris(2-ethylhexyD phosphate. The liquid plasticizer is commercially available; for example, product name: DisflmollTM TOF (Tg= -105 C) provided by Lanxess co., ltd.
[0057] According to one embodiment, the rubber composition of the tread of the snow tire according to the invention is devoid or comprises less than 30 phr, preferably less Date Recue/Date Received 2022-02-08 than 20 phr, more preferably less than 10 phr, of any liquid plasticizer(s) other than the liquid phosphate plasticizer.
[00581 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. At ambient temperature (20 C) under atmospheric pressure, 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 eventually take on the shape of their container), as opposed, in particular, to plasticizing hydrocarbon resins which are by nature solid at ambient temperature.
[0059] 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, Safety Residual Aromatic Extracts (SRAE) oils, mineral oils, vegetable oils, ether plasticizers, ester plasticizers other than phosphate plasticizers, sulphonate plasticizers and the mixtures thereof are particularly suitable. Preferably, the liquid plasticizer(s) (other than the liquid phosphate plasticizer) are vegetable oils as described, for example, in an application WO 2012/069565.
100601 According to another embodiment, 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).
[0061] 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"). They 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).
[0062] In a known manner, 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.

[0063] To recapitulate, 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 um, before injection into the apparatus. The apparatus used is, for example, a "Waters Alliance"
chromatographic line according to the following conditions:
[0064] elution solvent is tetrahydrofuran, [0065] temperature: 35 C;
100661 concentration: 1 g/litre;
[0067] flow rate: 1 ml/min;
[0068] injected volume: 100 ul;
[0069] Moore calibration with polystyrene standards;
[0070] set of 3 "Waters" columns in series ("Styragel HR4E", "Styragel IARI"
and "Styragel FIR 0.5").
[0071] detection by differential refractometer (for example "WATERS 2410") which may be equipped with operating software (for example "Waters Millenium").
[0072] A Moore calibration is carried out with a series of commercial polystyrene standards having a low 1p (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 (1p:Mw/lVIn) are deduced from the data recorded (curve of distribution by mass of the molar masses).

[0073] All the values for molar masses shown in the present application are thus relative to calibration curves produced with polystyrene standards.
[0074] Preferably, the plasticizing hydrocarbon resin exhibits at least any one, more preferably all, of the following characteristics:
[0075] 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);
[0076] a softening point above 50 C (in particular between 50 C and 150 C);
[0077] a number-average molar mass (Mn) between 400 and 2000 g/mol, preferably between 500 and 1500 g/mol;
[0078] a polydispersity index (1p) of less than 3, preferably of less than 2 (reminder:
1p:Mw/Mn with Mw the weight average molar mass).
[0079] As examples of such hydrocarbon resin(s), mention may be made of 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. C5 fraction homopolymer or copolymer resins, C9 fraction homopolymer or copolymer resins, alpha-methyl styrene homopolymer or copolymer resins and the mixtures thereof.

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/C5 fraction copolymer resins, (D)CPD/C9 fraction copolymer resins, terpene/vinylaromatic copolymer resins, terpene/phenol copolymer resins, C5 fraction/vinyl-aromatic copolymer resins, fraction/vinylaromatic copolymer resins, and the mixtures thereof.

[0080] The term "terpene" combines here, in a known way, the a-pinene, I3-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-limonene (dextrorotatory enantiomer) or else dipentene, the racemate of the dextrorotatory and laevorotatory enantiomers. Styrene, a-methylstyrene, ortho-, meta- or para-methylstyrene, vinyltoluene, para-(tert-butyl) styrene, methoxy styrenes, chlorostyrenes, hydroxy styrenes vinylmesitylene, divinylbenzene, vinylnaphthalene, or any vinylaromatic monomer resulting from a C9 fraction (or more generally from a C8 to Cio fraction) are suitable, for example, as vinylaromatic monomer. Preferably, the vinylaromatic compound is styrene or a vinylaromatic monomer resulting from a C9 fraction (or more generally from a C8 to C10 fraction). Preferably, the vinylaromatic compound is the minor monomer, expressed as molar fraction, in the copolymer under consideration.
[0081] More particularly, mention may be made of 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, fraction/styrene copolymer resins, C5 fraction /C9 fraction copolymer resins and blends of these resins.
[0082] All the above resins are well known to those skilled in the art and are commercially available, for example sold by DRT under the name "Dercolyte"TM as regards polylimonene resins, sold by Neville Chemical Company under the name "Super Nevtac"TM, by Kolon under the name HikorezTM or by Exxon Mobil under the name EscorezTM as regards C5 fraction /styrene resins or C5 fraction/C9 fraction resins, or Date Recue/Date Received 2022-02-08 else by Struktol under the name "40 MSTM or "40 NS" ' (blends of aromatic and/or aliphatic resins).
[0083] In a manner known to a person skilled in the art, 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 liquid plasticizing compound, such as an oil.
5-4. Various Additives [0084] 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 phenolic 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.
[0085] These 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.

Date Recue/Date Received 2022-02-08 5-5. Manufacture of the Rubber Compositions and of the Treads [0086] 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 110 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 110 C, for example between 40 C and 100 C. finishing phase during which the crosslinking or vulcanization system is incorporated.
[0087] A process which can be used for the manufacture of such compositions comprises.
for example and preferably, the following steps:
[0088] incorporating in the diene elastomer(s), in a mixer, the reinforcing filler, the liquid phosphate plasticizer, during a first stage ("non productive" stage) everything being kneaded thermomechanically (for example in one or more steps) until a maximum temperature of between 110 C and 190 C is reached;
[0089] cooling the combined mixture to a temperature of less than 100 C;
[0090] subsequently incorporating, during a second stage (referred to as a "productive"
stage), a crosslinking system;
[0091] kneading everything up to a maximum temperature of less than 110 C;
[0092] extruding or calendering the rubber composition thus obtained, in particular in the form of a tire tread.
[0093] By way of example, 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.
[0094] After cooling the mixture thus obtained, 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.
[0095] The crosslinking system proper is preferably based on sulphur and on a primary vulcanization accelerator, in particular on an accelerator of sulphenamide type.
Added to this vulcanization system are 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 non-productive 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.
[0096] 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. These accelerators are more preferably chosen from the group consisting of 2-mercaptobenzothiazyl disulphide (abbreviated to "MBTS"). N-cyclohexy1-2-benzothiazole sulphenamide (abbreviated to "CBS"), N,N-dicyclohexy1-2 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.
[0097] 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.
[0098] The vulcanization (or curing) is carried out in a known way at a temperature generally of between 110 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.
[0099] 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.
[0100] 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).
[0101] 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.
[0102] The invention is further illustrated by the following non-limiting examples.
6. EXAMPLES OF THE IMPLEMENTATION OF THE INVENTION
[0103] Results shown in Tables 2, 3 and 5 are obtained by methods of measurements and tests mentioned in "4. MEASUREMENTS AND TESTS USED" unless otherwise instructed.
6-1. Preparation of the Rubber Compositions and of the Treads [0104] The, tests which follow were carried out in the following way: the reinforcing filler (for example a reinforcing inorganic filler, such as silica, and its associated coupling agent), the liquid phosphate plasticizer, the diene elastomer(s) and the various other ingredients, with the exception of the vulcanization system, were successively introduced into an internal mixer having an initial vessel temperature of approximately 60 C; the mixer was thus approximately 70% full (% by volume).
Thermomechanical working (non-productive phase) was then carried out in one stage, which lasts in total approximately 3 to 4 minutes, until a maximum "dropping'.
temperature of 165 C was reached. The mixture thus obtained was recovered and cooled and then sulphur and an accelerator of sulphenamide type were incorporated on an external mixer (homofinisher) at 30 C, everything being mixed (productive phase) for an appropriate time (for example between 5 and 12 min).
[0105] The 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.
6-2. Rubber tests (Tensile tests and Shore A hardness) [0106] In -these tests, three compositions (identified as C-1. C-2 and C-3) 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;
[0107] The formulations of the three compositions (Table 1 - contents of the various products expressed in phr), their properties after curing (20 min at 150 C) are given in Tables 1 and 2; the vulcanization system is composed of sulphur and sulphenamide.
[0108] It is known by a person skilled in the art that after curing, shore A
hardness and moduli in the extension are important for the mechanical behavior of the tread and thus for the road performance of the tire. One can note here that the 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.
6-3. Friction test with rubber block on snow [0109] These three compositions were subjected to the friction test, as a laboratory test, consisting in measuring their friction coefficients on snow. The snow temperature was set at -10 C, and the friction test (snow test) was conducted on a hard pack snow track with a CTI penetrometer reading of about 90 in according to Standard ASTM
F1805.
101101 The results are expressed in Table 3. A value above that of the first reference (composition C-1), arbitrarily set at 100, indicates an improved result, that is to say an aptitude for shorter braking distance. It is observed in this Table 3 that the composition C-3 according to the invention has a remarkable increase (10% or even 18%, respectively) in the friction coefficient on the snow, relative to the composition C-1 (the first reference) and the composition C-2 (the comparative example).
[0111] Moreover, other three compositions (identified as 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. A value above that of a second reference (composition C-4), arbitrarily set at 100, indicates an improved result, that is to say to an aptitude for shorter braking distance. It is observed in this Table 5 that the composition C-5, based on natural rubber, according to the invention has a certain increase (5%), and 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).

[0112] In conclusion, 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.

Table 1 Rubber Composition No.: Comparative Example of the Ref.1 example invention 1R(1) 100 100 100 Silica (2) 70 70 70 Coupling agent (3) 5.6 5.6 5.6 Carbon black (4) 5 5 5 Non aromatic oil 1 (5) 40 Non aromatic oil 2 (6) 40 Liquid phosphate plasticizer (7) 40 ZnO 3 3 3 Stearic acid 1 1 1 Antiozone wax 1.5 1.5 1.5 Antioxidant (8) 2 2 2 DPG (9) 1.7 1.7 1.7 Sulphur 2 2 2 Accelerator (10) 1.5 1.5 1.5 (1) Polyisoprene rubber "1R2200" from ZEON (98% of cis-1,4, Tg: -62 C);
(2) Silica "Zeosill 165MP" from Rhodia, " (CTAB, BET: about 160 m2/g);
(3) Coupling agent TESPT ("S 169" from Evonik);
(4) Grade ASTM N234 (Cabot);
(5) MES oil ("Catenex SNR" from Shell) (6) TDAE oil ("V ivaTec 500" from H&R) (7) Tris(2-ethylhexyl)phosphate, "Disflamoll TOE", from LANXESS
Company (Tg= -105 C) (8) N-(1,3-dimethylbuty1)-N-phenyl-para-phenylenediamine ("Santoflex 6-PPD" from Flexsys);
(9) Diphenylguanidine ("Perkacit DPG" from Flexsys);
(10) N-dicyclohexy1-2-benzothiazolesulphenamide ("Santocure CBS" from Flexsys).

Table 2 Rubber Composition No.: Comparative Example of the Ref.1 example invention Shore A 56 57 56 MA 10 3.1 3.3 3.0 MA100 1.4 1.4 1.4 MA300 1.3 1.3 1.2 Table 3 Rubber Composition No.: Comparative Example of the Ref.1 example invention Snow index 100 93 110 Table 4 Rubber Composition No.: Ref.2 Examples of the invention IR(1) 100 NR(11) 60 100 BR (12) 40 Silica (2) 80 80 80 Coupling agent (3) 6.4 6.4 6.4 Carbon black (4) 5 5 5 Non aromatic oil 1 (5) 50 Liquid phosphate plasticizer (7) 60 60 Hydrocarbon resin (13) 10 ZnO 3 3 3 Stearic acid 1 1 1 Antiozone wax 1.5 1.5 1.5 Antioxidant (8) 2 2 2 DPG (9) 1.7 1.7 1.7 Sulphur 2 2 2 Accelerator (10) 1.5 1.5 1.5 (11) Natural rubber (peptised);
(12) BR with 0.3% of 1,2; 2.7%-1,4 of trans; 97% of cis-1,4 (Tg = -104 C);
(13) Hydrocarbon resin C5/C9 type ("Escorez ECR-373" from Exxon);
Table 5 Rubber Composition No.: Ref.2 Example of the invention Snow index 100 105 113

Claims (15)

1. A snow tire having a tread comprising a rubber composition comprising at least:
- from 80 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 20 phr of a second diene elastomer which is different from the first 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; and - more than 10 phr and less than 100 phr of a liquid phosphate plasticizer having a glass transition temperature measured according to standard ASTM D3418 of less than -80 C, and the liquid phosphate plasticizer being liquid at 20 C under atmospheric pressure.
2. The tire according to Claim 1, wherein the first diene elastomer has a glass transition temperature measured according to ASTM D3418-82 of less than -50 C.
3. The tire according to Claim 1 or 2, wherein the first diene elastomer is a synthetic polyisoprene.

Date Recue/Date Received 2022-02-08
4. The tire according to any one of Claims 1 to 3, wherein the synthetic polyisoprene has a content of cis-1,4 bonds of greater than 90 %.
5. The tire according to any one of Claims 1 to 4, wherein the rubber composition comprises 0 to 20 phr of the second diene elastomer which is different from the first diene elastomer, the second diene elastomer being chosen from the group consisting of butadiene copolymers, isoprene copolymers and the mixtures thereof.
6. The tire according to any one of Claims 1 to 4, wherein the content of the reinforcing filler is within a range from 50 to 150 phr.
7. The tire according to any one of Claims 1 to 6, wherein the inorganic filler is silica.
8. The tire according to any one of Claims 1 to 7, wherein the content of liquid phosphate plasticizer being liquid at 20 C under atmospheric pressure is more than 20 phr and less than 8 Ophr.
9. The tire according to any one of Claims 1 to 8, wherein the liquid phosphate plasticizer being liquid at 20 C under atmospheric pressure has a glass transition temperature measured according to standard ASTM D3418 of less than -90 C.
10. The tire according to any one of Claims 1 to 9, wherein the liquid phosphate plasticizer being liquid at 20 C under atmospheric pressure is a trialkyl phosphate having between 12 and carbon atoms.

Date Recue/Date Received 2022-02-08
11. The tire according to Claim 10, wherein the liquid phosphate plasticizer being liquid at 20 C under atmospheric pressure is a tris(2-ethylhexyl) phosphate.
12. The tire according to any one of Claims 1 to 11, wherein the rubber composition is devoid or comprises less than 30 phr of liquid plasticizer(s) other than the liquid phosphate plasticizer.
13. The tire according to Claim 12, wherein the liquid plasticizer(s) other than the liquid phosphate plasticizer are chosen from the group consisting of 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, Safety Residual Aromatic Extracts (SRAE) oils, mineral oils, vegetable oils, ether plasticizers, ester plasticizers other than phosphate plasticizers, sulphonate plasticizers and the mixtures thereof.
14. The tire according to any one of Claims 1 to 13, wherein the rubber composition is devoid or comprises less than 60 phr of plasticizing hydrocarbon resin(s).
15. The tire according to Claim 14, wherein the 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, C9 fraction homopolymer or copolymer resins, alpha-methyl styrene homopolymer or copolymer resins, and the mixtures thereof.
Date Recue/Date Received 2022-02-08
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US9873780B1 (en) * 2016-10-10 2018-01-23 The Goodyear Tire & Rubber Company Tire with tread for combination of low temperature performance and wet traction
EP3532310B1 (en) * 2016-10-31 2020-10-14 Compagnie Générale des Etablissements Michelin A tire comprising a tread
CN109952208A (en) * 2016-10-31 2019-06-28 米其林集团总公司 Tire including tyre surface
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EP3234001A1 (en) 2017-10-25
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WO2016098908A1 (en) 2016-06-23
JP6698261B2 (en) 2020-05-27
EP3234001A4 (en) 2018-05-30
CN107001714A (en) 2017-08-01

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