CN116813990A

CN116813990A - Rubber composition for winter tyres and winter tyre

Info

Publication number: CN116813990A
Application number: CN202310313139.0A
Authority: CN
Inventors: L·F·M·梅贾; C·C·雅各比; K·I·安尼凡塔基; E·康斯坦塔基; V·M-J·赫伯瓦尔
Original assignee: Goodyear Tire and Rubber Co
Current assignee: Goodyear Tire and Rubber Co
Priority date: 2022-03-28
Filing date: 2023-03-28
Publication date: 2023-09-29
Also published as: JP2023145415A

Abstract

The invention discloses a rubber composition for a winter tyre and a winter tyre. The present invention relates to a rubber composition comprising 35phr to 60phr of a first polybutadiene rubber having a glass transition temperature of-80 ℃ to-105 ℃,5phr to 30phr of a second polybutadiene rubber having a glass transition temperature of-20 ℃ to-40 ℃,10phr to 60phr of one or more polyisoprene selected from synthetic polyisoprene and natural rubber, 30phr to 200phr of at least one filler, and 40phr to 120phr of at least one plasticizer having a glass transition temperature of-40 ℃ to-110 ℃. Furthermore, the present invention relates to a tire comprising the rubber composition.

Description

Rubber composition for winter tyres and winter tyre

Technical Field

The present invention relates to rubber compositions, in particular sulfur-curable or cured rubber compositions, for example for tires. Furthermore, the present invention relates to a rubber component comprising such a rubber composition and a tire comprising said rubber composition and/or rubber component.

Background

The tire industry has developed tires that are particularly suited for use under different weather conditions. Winter tires have been developed to provide adequate performance for cold weather conditions including snow and ice. In some northern european regions, ice is often present on the road surface, and it is therefore desirable to have even better performance on ice than is typically required for typical winter tyres. Furthermore, there is an increasing need for winter tyres with further reduced rolling resistance. Therefore, there is a need to develop a tire with limited rolling resistance that is particularly suitable for running on ice.

Disclosure of Invention

It may be an object of the present invention to provide a winter tyre with improved performance on icy or icy roads.

Another object of the invention may be to provide a winter tyre with improved rolling resistance.

It may be a further object of the present invention to provide a winter tyre with improved ice performance (e.g. grip) and improved rolling resistance.

Furthermore, it may be an object to provide good snow, wet and/or dry handling properties at the same time.

Detailed description of the preferred embodiments

The invention is defined by the scope of the appended claim 1. Further embodiments are provided in the dependent claims and in the summary of the invention herein below.

Thus, in a first aspect, the present invention relates to a rubber composition comprising 35phr to 60phr of a first polybutadiene rubber having a glass transition temperature of-80 ℃ to-105 ℃,5phr to 30phr of a second polybutadiene rubber having a glass transition temperature of-20 ℃ to-40 ℃ and 10phr to 60phr of one or more polyisoprenes selected from synthetic polyisoprenes and natural rubbers. Furthermore, the rubber composition comprises 30phr to 200phr of at least one filler, and 40phr to 120phr of at least one plasticizer having a glass transition temperature of-40 ℃ to-110 ℃.

The rubber composition according to the invention combines three polymers, namely a low glass transition temperature polybutadiene rubber, a high glass transition temperature polybutadiene rubber and polyisoprene, preferably cis 1, 4-polyisoprene (e.g. glass transition temperature of-60 ℃ to-75 ℃), and a relatively high amount of plasticizer in the claimed Tg range. The compounds according to the invention provide good grip at very low temperatures and good hysteresis properties, which translate into limited rolling resistance of the tire.

In one embodiment, the first polybutadiene rubber has a vinyl content of less than 25%, preferably less than 20%, or even more preferably less than 15%.

In another embodiment, the first polybutadiene rubber has a vinyl content of at least 1%, optionally at least 5% or at least 10%. This low vinyl range has been found to be most preferred.

In another embodiment, the cis content of the first polybutadiene rubber is less than 60%, preferably less than 50% or even less than 40%. Preferably, the cis content is higher than 10%, and preferably higher than 20% or 30%. In other words, the first polybutadiene rubber is a low cis polybutadiene optionally prepared with an n-butyllithium initiator. In particular, the low cis content helps to avoid crystallization at low temperatures.

In another embodiment, the first polybutadiene rubber has a weight average molecular weight Mw of 250k g/mol to 450k g/mol. Mw is determined herein using Gel Permeation Chromatography (GPC) according to ASTM 5296-11 using polystyrene calibration standards or equivalents.

In another embodiment, the first polybutadiene rubber has a glass transition temperature of at most-80 ℃, preferably at most-85 ℃, and/or at least-99 ℃, preferably at least-95 ℃.

In another embodiment, the weight average molecular weight Mw of the second polybutadiene rubber is within the following range: 500k g/mol to 900k g/mol, preferably to 800k g/mol or to 700k g/mol.

In another embodiment, the second polybutadiene rubber has a vinyl content greater than 50%, preferably greater than 60% or greater than 70%. In other words, the second polybutadiene rubber is a high vinyl polybutadiene rubber. These features support, for example, miscibility with polyisoprene.

In another embodiment, the glass transition temperature of the second polybutadiene rubber is at least-20℃and/or at least-35 ℃.

In another embodiment, the glass transition temperature of the second polybutadiene rubber is at most-20℃and/or at least-35 ℃.

In another embodiment, the glass transition temperature of the second polybutadiene rubber is at least up to-20℃and/or at least-35 ℃.

In another embodiment, the rubber composition is free of styrene-containing rubber, such as styrene butadiene rubber, or comprises less than 5phr, preferably less than 1phr, of such rubber.

In another embodiment, the rubber composition comprises more first polybutadiene rubber (all by weight) than polyisoprene. Preferably, the rubber composition comprises at least 5% (by weight) more than polyisoprene or alternatively at least 2phr more of the first polybutadiene. Preferably, the rubber composition comprises up to 20% (by weight) or alternatively up to 15phr more of the first polybutadiene than polyisoprene.

In another embodiment, the rubber composition comprises more polyisoprene than the second polybutadiene, all by weight. Preferably, the rubber composition comprises at least 5% (by weight) more than the second polybutadiene or alternatively at least 2phr more polyisoprene. Preferably, the rubber composition comprises up to 500% or 5 times more (all by weight) than the second polybutadiene, or alternatively up to 40phr more polyisoprene. Preferably, the rubber composition comprises up to 500% or 5 times (all by weight) the second polybutadiene, or alternatively up to 40phr more polyisoprene than the second polybutadiene.

In yet another embodiment, the rubber composition comprises one or more of the following: 10 to 20phr of a second polybutadiene rubber, 40 to 60phr of a first polybutadiene rubber, 30 to 50phr of the polyisoprene.

In yet another embodiment, the polyisoprene is cis 1, 4-polyisoprene, preferably synthetic cis 1, 4-polyisoprene or natural rubber.

In another embodiment, the filler comprises predominantly silica.

In yet another embodiment, the rubber composition comprises 80phr to 150phr of silica, preferably 80phr to 140phr of silica, or even more preferably 95phr to 140phr of silica or 105 to 135phr of silica.

In another embodiment, the silica has a BET surface area of 90m ² /g to 140m ² /g, preferably 100m ² /g to 135m ² /g。

In yet another embodiment, the plasticizer is a liquid plasticizer, such as an oil or liquid diene-based polymer. By liquid plasticizer is meant herein that the plasticizer is liquid at 23 ℃.

In yet another embodiment, the plasticizer comprises at least one oil having a glass transition temperature below-35 ℃.

In yet another embodiment, the rubber composition comprises 55phr to 95phr of at least one liquid plasticizer having a glass transition temperature of-40 ℃ to-100 ℃. Preferably, the liquid plasticizer comprises or consists of one or more oils.

In yet another embodiment, the first oil has a glass transition temperature of-40 ℃ to-85 ℃ and the second oil has a glass transition temperature of-90 ℃ to-100 ℃. Preferably, the first oil is a mineral oil and/or the second oil is a triglyceride oil or a vegetable oil.

In yet another embodiment, the rubber composition comprises from 8phf (parts per hundred filler, all by weight) to 15phf of at least one silane.

In yet another embodiment, the first polybutadiene rubber is functionalized to couple to silica.

In yet another embodiment, the first polybutadiene rubber is functionalized with at least one of amino, siloxy, and silane groups. Preferably, the first polybutadiene rubber comprises at least one functional group selected from one or more of the following: aminosiloxy, and aminosiloxy groups.

In yet another embodiment, the first polybutadiene rubber is end-chain functionalized with these groups.

In one embodiment, the rubber composition may comprise at least one additional diene-based rubber. Representative synthetic polymers may be homo-and copolymers of butadiene and its homologs and derivatives, such as methyl butadiene, dimethyl butadiene and pentadiene, as well as copolymers, such as those formed from butadiene or its homologs or derivatives with other unsaturated monomers. Among the latter may be acetylene, such as vinyl acetylene; olefins, such as isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds such as acrylic acid, acrylonitrile (which polymerize with butadiene to form NBR), methacrylic acid and styrene, the latter compound polymerizing with butadiene to form SBR, and vinyl esters and various unsaturated aldehydes, ketones and ethers such as acrolein, methyl isopropenyl ketone and vinyl ethyl ether. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1, 4-polybutadiene), polyisoprene (including cis-1, 4-polyisoprene), butyl rubber, halobutyl rubber such as chlorobutyl rubber or bromobutyl rubber, styrene/isoprene/butadiene rubber, copolymers of 1, 3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, and ethylene/propylene terpolymers, also known as Ethylene Propylene Diene Monomer (EPDM), and in particular ethylene/propylene/dicyclopentadiene terpolymers. Additional examples of rubbers that may be used include alkoxy-silyl end-functionalized solution polymerized polymers (SBR, PBR, IBR and SIBR), silicon-coupled and tin-coupled star-branched polymers. Preferred rubbers or elastomers may generally be natural rubber, synthetic polyisoprene, polybutadiene, and SBR, including SSBR.

In another embodiment, emulsion polymerization derived styrene/butadiene (ESBR) having a styrene content of 20% to 28% bound styrene may be used, or for some applications, ESBR having a medium to relatively high bound styrene content, i.e., 30% to 45% bound styrene content. In many cases, ESBR will have a bound styrene content of 26% to 31%. ESBR prepared by emulsion polymerization may represent copolymerization of styrene and 1, 3-butadiene in the form of an aqueous emulsion. These are well known to those skilled in the art. The bound styrene content may vary, for example, from 5% to 50%. In one aspect, the ESBR may also contain acrylonitrile to form a terpolymer rubber, such as ESBAR, in an amount of, for example, 2 to 30 weight percent bound acrylonitrile in the terpolymer. Styrene/butadiene/acrylonitrile copolymer rubbers prepared by emulsion polymerization containing 2 to 40 wt.% bound acrylonitrile in the copolymer may also be considered diene-based rubbers.

In another embodiment, solution polymerization prepared SBR (SSBR) may be used. Such SSBR may, for example, have a bound styrene content of 5-50%, preferably 9-36%, and most preferably 26-31%. SSBR may conveniently be prepared, for example, by anionic polymerization in an inert organic solvent. More specifically, SSBR can be synthesized by copolymerizing styrene and 1, 3-butadiene monomers in a hydrocarbon solvent using an organolithium compound as an initiator. In yet another embodiment, the polystyrene-soluble butadiene rubber is a tin-coupled polymer. In another embodiment, the SSBR is functionalized to improve compatibility with silica. Additionally, or alternatively, SSBR is sulfur/thiol-functionalized. This helps to improve the stiffness of the compound and/or its hysteresis behavior. Thus, for example, the SSBR may be a sulfur/thiol-functionalized (thio-functionalized) tin-coupled solution-polymerized copolymer of butadiene and styrene.

However, it is preferred that the rubber composition does not contain any SBR, IBR and SIBR, or comprises at least less than 5phr of such rubber.

In one embodiment, synthetic or natural polyisoprene rubber (natural rubber) may be used. Synthetic cis-1, 4-polyisoprene and natural rubber are known per se to those skilled in the rubber art. In particular, the cis 1, 4-microstructure content may be at least 90%, and typically at least 95%, or even higher.

In one embodiment, cis-1, 4-polybutadiene rubber (BR or PBD) is used. Suitable polybutadiene rubbers may be prepared, for example, by organic solution polymerization of 1, 3-butadiene. BR can conveniently be characterized, for example, by having a cis-1, 4-microstructure content of at least 90% (high cis content) and a glass transition temperature (Tg) of from-95℃to-110 ℃. Suitable polybutadiene rubbers are commercially available, e.g. from The Goodyear Tire&Rubber Company1207、/>1208、/>1223 or->1280. These high cis-1, 4-polybutadiene rubbers can be synthesized, for example, using a nickel catalyst system comprising a mixture of (1) an organonickel compound, (2) an organoaluminum compound, and (3) a fluorine-containing compound, as described in U.S. patent 5,698,643 and U.S. patent 5,451,646, which are incorporated herein by reference.

The glass transition temperature or Tg of an elastomer means the glass transition temperature of the corresponding elastomer in its uncured state. The glass transition temperature of the elastomer composition means the glass transition temperature of the elastomer composition in its cured state. Tg is measured as the midpoint of the peak at a rate of temperature increase of 20℃per minute by a Differential Scanning Calorimeter (DSC) according to ASTM D3418 or equivalent.

The term "phr" as used herein and in accordance with conventional practice refers to "parts by weight of each material per 100 parts by weight of rubber or elastomer". Typically, using this convention, the rubber composition comprises 100 parts by weight of rubber/elastomer. The claimed compositions may contain other rubbers/elastomers than those explicitly mentioned in the claims, provided that the phr values of the claimed rubbers/elastomers are consistent with the claimed phr ranges and that the amounts of all rubbers/elastomers in the composition result in a total of 100 parts rubber. In one example, the composition may further comprise from 1phr to 10phr, optionally from 1phr to 5phr, of one or more additional diene-based rubbers, such as SBR, SSBR, ESBR. In another example, the composition may comprise less than 5phr, preferably less than 3phr, of additional diene-based rubber, or may also be substantially free of such additional diene-based rubber. The terms "size" and "composition" and "formulation" are used interchangeably herein unless otherwise indicated. The terms "rubber" and "elastomer" are also used interchangeably herein.

In another embodiment, the rubber composition comprises from 1phr to 80phr, or from 5phr to 80phr, of the resin, preferably having a glass transition temperature Tg of greater than 20 ℃. The Tg of the resin is measured as the midpoint of the peak by a Differential Scanning Calorimeter (DSC) at a rate of temperature increase of 10 ℃/min according to ASTM D6604 or equivalent. Preferably, the resin has a softening point above 70 ℃ as determined by ASTM E28, which may sometimes be referred to as the ring and ball softening point. In one embodiment, the rubber composition comprises from 10phr to 60phr, or from 20phr to 60phr, or from 30phr to 60phr, of the resin.

In another embodiment, the resin is selected from the group consisting of coumarone-indene resins, petroleum resins (petroleum hydrocarbon resin), terpene polymers/resins, styrene/alpha-methylstyrene resins, terpene phenol resins (terpene phenol resin), rosin-derived resins, and copolymers and/or mixtures thereof.

The coumarone-indene resin preferably contains coumarone and indene as monomer components constituting a resin skeleton (main chain). The monomer components other than coumarone and indene that can be incorporated into the backbone are, for example, methyl coumarone, styrene, alpha methyl styrene, methyl indene, vinyl toluene, dicyclopentadiene, cyclopentadiene, and dienes such as isoprene and piperylene. The coumarone-indene resin preferably has a melting point (as measured by the ball and socket method) of 10 ℃ to 160 ℃. Even more preferably, the melting point is 30 to 100 ℃.

Suitable petroleum resins include both aromatic and non-aromatic types. Several types of petroleum resins are available. Some resins have low unsaturation and high aromatic content, while some are highly unsaturated, while some are completely free of aromatic structures. The difference in resins is mainly due to the olefins in the feed from which the resin is derived. Conventional derivatives in these resins include any C5 species (olefins and dienes containing an average of five carbon atoms) such as cyclopentadiene, dicyclopentadiene, dienes such as isoprene and piperylene, and any C9 species (olefins and dienes containing an average of 9 carbon atoms) such as vinyl toluene, alpha-methyl styrene and indene. Such resins are prepared from any mixture of the above-mentioned C5 and C9 species and are referred to as C5/C9 copolymer resins. Petroleum resins are generally available at softening points of 10 ℃ to 120 ℃. Preferably, the softening point is 30 to 100 ℃.

In one embodiment, the C5 resin is an aliphatic resin prepared from one or more of the following monomers: 1, 3-pentadiene (e.g., cis or trans), 2-methyl-2-butene, cyclopentene, cyclopentadiene and dicyclopentadiene.

In another embodiment, the C9 resin is a resin prepared from one or more aromatic monomers, preferably selected from indene, methylindene, vinyl toluene, styrene, and methyl styrene (e.g., alpha-methyl styrene).

In yet another embodiment, the C9 modified resin is a resin (e.g., C5 resin) that has been modified or functionalized with one or more aromatic monomers, preferably selected from indene, methylindene, vinyl toluene, styrene, and methyl styrene (e.g., alpha-methyl styrene).

The terpene resin preferably comprises a polymer of at least one of limonene, alpha pinene, beta pinene and delta-3-carene. Such resins may be obtained at a melting point of 10 ℃ to 135 ℃.

Terpene-phenol resins can be obtained by copolymerizing phenol monomers with terpenes such as limonene, pinene and delta-3-carene.

Representative of resins derived from rosin and its derivatives are, for example, gum rosin, wood rosin, and tall oil rosin. Gum rosin, wood rosin, and tall oil rosin have similar compositions, although the amount of rosin components may vary. Such resins may be dimerized, polymerized or disproportionated. Such resins may be in the form of esters of rosin acids and polyols such as pentaerythritol or glycols.

Styrene/alpha-methylstyrene resins are herein considered to be (preferably relatively short-chain) copolymers of styrene and alpha-methylstyrene having a styrene/alpha-methylstyrene molar ratio of from about 0.05 to about 1.50. In one aspect, such resins may suitably be prepared, for example, by cationic copolymerization of styrene and alpha-methylstyrene in a hydrocarbon solvent. Thus, the contemplated styrene/alpha-methylstyrene resins may be characterized, for example, by their chemical structure, i.e., their styrene and alpha-methylstyrene content, as well as by their glass transition temperature, molecular weight, and molecular weight distribution.

In one embodiment, the resin may be partially or fully hydrogenated.

In a preferred embodiment, the rubber composition is resin-free or comprises less than 5phr of resin or less than 3phr of resin, in particular hydrocarbon resin.

In embodiments, the rubber composition comprises an oil, in particular a processing oil. The processing oil may be included in the rubber composition as extender oil commonly used to fill elastomers. Processing oils may also be included in the rubber composition by adding the oil directly during the rubber compounding process. The process oil used may include both extender oil present in the elastomer and process oil added during compounding. Suitable process oils may include a variety of oils known in the art, including aromatic, paraffinic, naphthenic, vegetable, and low PCA oils, such as MES, TDAE, SRAE and heavy naphthenic oils. Suitable low PCA oils may include those having a polycyclic aromatic content of less than 3 percent by weight as determined by the IP346 method. Procedures for the IP346 method can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000parts,2003, 62 nd edition, the Institute of Petroleum, published, united Kingdom. Some representative examples of vegetable oils that may be used include soybean oil, sunflower oil, canola oil, corn oil, coconut oil, cottonseed oil, olive oil, palm oil, peanut oil, and safflower oil. Soybean oil and corn oil are typically preferred vegetable oils.

The glass transition temperature Tg of a liquid plasticizer, such as an oil, is measured by a Differential Scanning Calorimeter (DSC) as the midpoint of the peak at a temperature increase rate of 10 ℃/min according to ASTM E1356 or equivalent.

In one embodiment, the rubber composition comprises silica. Common siliceous pigments that may be used in the rubber compounds include, for example, conventional fumed and precipitated siliceous pigments (silica). In one embodiment, precipitated silica is used. Conventional siliceous pigments may be precipitated silicas such as, for example, those obtained by the acidification of a soluble silicate such as sodium silicate. The silica can be characterized, for example, by having a BET surface area as measured using nitrogen. In one embodiment, the BET surface area may be 40 to 600 square meters per gram. In another embodiment, the BET surface area may be from 50 to 300 square meters per gram. BET surface area is determined according to ASTM D6556 or equivalent and is described in the Journal ofthe American Chemical Society, vol.60, page 304 (1930). Conventional silica may also have a thickness of 100cm ³ 100g to 400cm ³ 100g, or 150cm ³ 100g to 300cm ³ 100g of dibutyl phthalate (DBP) absorption, as determined according to ASTM D2414 or equivalent. Conventional silica may be expected to have an average final particleThe degree, for example, is 0.01 to 0.05 microns, as determined by electron microscopy, although the silica particles may be even smaller or possibly larger in size. Various commercially available silicas may be used, such as, for example only, and without limitation, silicas commercially available from PPG Industries under the Hi-Sil trademark with designations 210, 315G, EZ G, and the like; silica available from Solvay has, for example, the designations Z1165MP and Premium200MP, and silica available from Evonik AG has, for example, the designations VN2 and Ultrasil 6000GR, 9100GR.

In yet another embodiment, the rubber composition may comprise pre-silanized and/or precipitated silica.

In another embodiment, the pre-silanized, or in other words pre-hydrophobated, precipitated silica used is hydrophobated by treatment with at least one silane before it is added to the rubber composition. Suitable silanes include, but are not limited to, alkylsilanes, alkoxysilanes, organoalkoxysilyl polysulfides, and organomercaptoalkoxysilanes.

In an alternative embodiment, instead of reacting the precipitated silica with the silica coupling agent in situ within the rubber, the pre-hydrophobized precipitated silica may be pre-treated with a silica coupling agent comprising, for example, an alkoxy organomercaptoalkoxysilane or a combination of an alkoxysilane and organomercaptoalkoxysilane prior to blending the pre-treated silica with the rubber. See, for example, U.S. patent 7,214,731, the teachings of which are incorporated herein for the purpose of describing pre-hydrophobized precipitated silica and techniques for preparing such pre-hydrophobized precipitated silica.

In another embodiment, the pre-silanized precipitated silica is a precipitated silica pre-reacted with a silica coupling agent comprising bis (3-triethoxysilylpropyl) polysulfide or an alkoxyorganomercaptosilane having an average of 1 to 5 linking sulfur atoms (preferably 2 to 4) in its polysulfide bridge.

In one embodiment, the rubber composition comprises carbon black. Representative examples of such carbon blacks include N110,Grades N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990 and N991. These blacks have an iodine absorption of 9g/kg to 145g/kg and 34cm ³ /100g-150cm ³ DBP value of/100 g. Iodine absorption values were determined according to ASTM D1510 or equivalent. Preferably, the amount of carbon black used herein is from 0.1phr to 10phr, or from 0.1phr to 6phr.

In one embodiment, the rubber composition may contain a sulfur-containing organosilicon compound or silane. Examples of suitable sulfur-containing organosilicon compounds have the formula:

Z-Alk-Sn-Alk-Z l

wherein Z is selected from

Wherein R1 is alkyl of 1 to 4 carbon atoms, cyclohexyl or phenyl; r2 is an alkoxy group of 1 to 8 carbon atoms or a cycloalkoxy group of 5 to 8 carbon atoms; alk is a divalent hydrocarbon of 1 to 18 carbon atoms, and n is an integer of 2 to 8. In one embodiment, the sulfur-containing organosilicon compound is a 3,3' -bis (trimethoxy or triethoxysilylpropyl) polysulfide. In one embodiment, the sulfur-containing organosilicon compound is 3,3 '-bis (triethoxysilylpropyl) disulfide and/or 3,3' -bis (triethoxysilylpropyl) tetrasulfide. Thus, for formula I, Z may be

Wherein R2 is an alkoxy group of 2 to 4 carbon atoms or 2 carbon atoms; alk is a divalent hydrocarbon of 2 to 4 carbon atoms, alternatively 3 carbon atoms, and n is an integer of 2 to 5 or an integer of 2 or 4. In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. patent application 6,608, 125. At the position ofIn one embodiment, the sulfur-containing organosilicon compound comprises 3- (octanoylthio) -1-propyltriethoxysilane, CH ₃ (CH ₂ ) ₆ C(＝O)-S-CH ₂ CH ₂ CH ₂ Si(OCH ₂ CH ₃ ) ₃ As NXT ^TM Commercially available from Momentive Performance Materials. In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. patent application publication No. 2003/013055. In one embodiment, the sulfur-containing organosilicon compound is Si-363 from Degussa. The amount of sulfur containing organosilicon compound in the rubber composition may vary depending on the level of other additives used. In general, the amount of compound may be from 0.5phr to 20phr. Other preferred amounts are described herein above.

It will be readily appreciated by those skilled in the art that the rubber compositions may be compounded by methods generally known in the rubber compounding art, such as mixing the various sulfur-vulcanizable constituent rubbers with various commonly used additive materials such as, for example, sulfur donors, curing aids, e.g., activators and scorch retarders, and processing additives, such as oils, resins and plasticizers including tackifying resins, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants, and antiozonants and peptizing agents. The additives mentioned above are selected and generally used in conventional amounts, as known to the person skilled in the art, depending on the intended use of the sulfur-vulcanizable and sulfur-vulcanized material (rubber). Some representative examples of sulfur donors include elemental sulfur (free sulfur), amine disulfide (amine disulfide), polymeric polysulfides, and sulfur olefin adducts. In one embodiment, the sulfur-vulcanizing agent is elemental sulfur. The sulfur-vulcanizing agent may be used, for example, in an amount of 0.5phr to 8phr, alternatively 1.5phr to 6phr. Typical amounts of tackifier resins, if used, comprise, for example, 0.5phr to 10phr, typically 1phr to 5phr. Typical amounts of processing aids, if used, include, for example, 1phr to 50phr (which may include, inter alia, oil). Typical amounts of antioxidants, if used, may comprise, for example, from 1phr to 5phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as those disclosed, for example, in pages 344-346 of The Vanderbilt Rubber Handbook (1978). Typical amounts of antiozonants, if used, may comprise, for example, 1phr to 5phr. Typical amounts of fatty acids, if used, may include stearic acid, and may include, for example, 0.5phr to 3phr. Typical amounts of wax, if used, may include, for example, 1phr to 5phr. Microcrystalline waxes are commonly used. Typical amounts of peptizers, if used, may comprise, for example, 0.1phr to 1phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzoyl aminodiphenyl disulfide.

Accelerators may be preferred, but are not necessary to control the time and/or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system, the primary accelerator, may be used. The primary accelerator(s) may be used in a total amount of 0.5phr to 4phr, alternatively 0.8phr to 1.5 phr. In another embodiment, a combination of primary and secondary accelerators may be used, with the secondary accelerator being used in a smaller amount, for example 0.05phr to 3phr, to activate and improve the properties of the vulcanizate. The combination of these accelerators may be expected to produce a synergistic effect on the final properties and are somewhat better than those produced by either accelerator alone. In addition, a slow acting accelerator may be used which is not affected by normal processing temperatures but produces satisfactory cure at ordinary vulcanization temperatures. Vulcanizing scorch retarders may also be used. Suitable types of accelerators useful in the present invention are, for example, amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. In one embodiment, the primary accelerator is a sulfenamide. If a secondary accelerator is used, the secondary accelerator may be, for example, a guanidine, dithiocarbamate or thiuram compound. Suitable guanidines include diphenylguanidine (dipheyyguanidine) and the like. Suitable thiurams include tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrabenzylthiuram disulfide.

The mixing of the rubber composition may be accomplished by methods known to those skilled in the art of rubber mixing. For example, the ingredients may generally be mixed in at least two stages, i.e., at least one non-productive stage followed by a productive mixing stage. The final curative, including the sulfur-vulcanizing agent, may generally be mixed in a final stage, commonly referred to as a "productive" mixing stage, where the mixing is typically conducted at a temperature or final temperature that is lower than the mixing temperature or temperatures of the preceding non-productive mixing stage or stages. The terms "non-productive" and "productive" mix stages are well known to those skilled in the rubber mixing arts. In one embodiment, the rubber composition may be subjected to a thermomechanical mixing step. The thermomechanical mixing step typically comprises mechanical processing in a mixer or extruder for a period of time, for example, a period of time suitable to produce a rubber temperature of 140 ℃ to 190 ℃. The appropriate duration of the thermo-mechanical processing varies with operating conditions and the volume and nature of the component. For example, the thermo-mechanical processing may be 1 to 20 minutes.

The rubber composition may be incorporated into various rubber components of a tire (or in other words, tire components). For example, the rubber component may be a tread (including preferably tread cap and/or tread base), sidewall, apex, chafer, sidewall insert, cord coating (wirecoat), or innerliner.

The vulcanization of the pneumatic tire of the present invention may be carried out, for example, at a conventional temperature of 100 to 200 ℃. In one embodiment, the vulcanization is carried out at a temperature of 110 ℃ to 180 ℃. Any conventional vulcanization method may be used, such as heating in a press or mold, heating with superheated steam or hot air. Such tires can be manufactured, shaped, molded, and cured by various methods that are known and will be apparent to those skilled in the art.

In a second aspect of the invention, the invention relates to a tyre comprising the rubber composition according to the first aspect of the invention and optionally one or more of its embodiments.

The tire of the present invention may be, for example, a pneumatic or non-pneumatic tire, a racing tire, a passenger tire, an aircraft tire, an agricultural tire, a bulldozer tire, an off-the-road (OTR) tire, a truck tire, or a motorcycle tire. The tire may also be a radial or bias tire.

In one embodiment, the tire is a winter tire.

In another embodiment, the tire is a winter tire and/or a tire having a trimodal mountain snowflake symbol (3peak mountain snowflake symbol,3PMSF symbol) on its sidewall.

In yet another embodiment, the rubber composition is contained in the tread of a tire.

In yet another embodiment, the rubber composition is provided in the radially outermost layer of the tread (contacting the road surface when driving).

Examples

Table 1 below shows inventive examples according to embodiments of the present invention and comparative examples not according to the present invention.

TABLE 1

¹ Polybutadiene rubber having Tg of-108 ℃ and a cis content of 96%, obtained as Buden by Goodyear ^TM 1223 form

² Polybutadiene rubber functionalized to couple with silica and having a Tg of-90.5 ℃ and a vinyl content of 14.5% and a cis content of 34.5%, obtained as KBR 820 from Kumho

³ Polybutadiene rubber having Tg of-28 ℃ and a vinyl content of 77% in Europrene ^TM Forms of BR HV80 are from Versalis

⁴ Natural rubber

⁵ Low surface area silica having BET surface area of 125m ² /g

⁶ Mineral oil having Tg of-70deg.C

⁷ Sunflower oil having a Tg of-97deg.C

⁸ Bis-triethoxysilylpropyl disulfide in SI266 ^TM Form(s) from Evonik

⁹ Types of phenylenediamines

¹⁰ DPG and CBS types

The compositions of table 1 were tested as tire tread compounds, with the results shown in table 2 below.

TABLE 2

^a Average acceleration, braking and handling on ice under the same conditions, normalized to comparative example (higher better)

^b Average acceleration, braking and handling on snow under the same conditions normalized to comparative example (higher better)

^c Braking on dry road under the same conditions, normalized to comparative example (higher better)

^d Tire rolling resistance test under the same conditions normalized to comparative example (higher better)

^e Braking on wet road under the same conditions (lower than 10 ℃) was normalized to comparative example (higher better)

As shown in table 2 above, when inventive examples were used as tread rubber compositions in the same passenger car winter tires instead of comparative examples, the performance of the tires on ice was significantly improved (i.e., 8% improvement).

The rubber composition according to the inventive examples was modified without modifying the performance on snow and wet road surfaces and only slightly affecting dry braking.

Rolling resistance is improved.

Thus, the rubber composition of the inventive examples provides both improved ice performance and rolling resistance. The snow performance, wet braking performance and/or dry braking performance remained almost unchanged from the comparative examples. The corresponding winter tyre is therefore particularly suitable for effective use in areas which are often facing icy roads.

Claims

1. A rubber composition characterized in that:

35phr to 60phr of a first polybutadiene rubber having a glass transition temperature of-80 ℃ to-105 ℃;

5phr to 30phr of a second polybutadiene rubber having a glass transition temperature of-20 ℃ to-40 ℃;

10phr to 60phr of a polyisoprene selected from one or more of synthetic polyisoprene and natural rubber;

30phr to 200phr of at least one filler; and

40phr to 120phr of at least one plasticizer having a glass transition temperature of-40 ℃ to-110 ℃.

2. The rubber composition according to claim 1, characterized in that the first polybutadiene rubber has a vinyl content of less than 25% or in that the second polybutadiene rubber has a vinyl content of at least 50%.

3. The rubber composition according to claim 1, characterized in that the rubber composition comprises one or more of the following:

40phr to 60phr of a first polybutadiene rubber,

from 10phr to 20phr of a second polybutadiene rubber, and

30phr to 50phr of polyisoprene.

4. Rubber composition according to claim 1, characterized in that it comprises 80phr to 150phr of silica.

5. The rubber composition according to claim 1, characterized in that 55phr to 95phr of the liquid plasticizer has a glass transition temperature of-40 ℃ to-100 ℃.

6. The rubber composition according to claim 1, characterized in that the plasticizer comprises one or more of the following: i) A first oil having a glass transition temperature of-40 ℃ to-85 ℃, and ii) a second oil having a glass transition temperature of-90 ℃ to-100 ℃.

7. The rubber composition according to claim 1, characterized in that it comprises at least one silane of 8phf to 15 phf.

8. A tire characterized by the rubber composition according to claim 1.

9. Tyre according to claim 8, characterized in that it is a winter tyre.

10. The tire of claim 8, wherein the rubber composition is contained in a tread of the tire or in a radially outermost layer of the tread of the tire.