CN115895070A - Rubber composition and tire - Google Patents

Abstract

The invention discloses a rubber composition and a tire. A rubber composition and a tire comprising the rubber composition are disclosed. The rubber composition comprises 70 phr to 100 phr of at least one styrene-butadiene rubber, 0phr to 30 phr of at least one additional diene-based rubber, 40 phr to 200 phr of at least one filler, at least 5phr of aluminum hydroxide, and at least 10phr of at least one hydrocarbon resin selected from one or more of DCPD resin, CPD resin, and C5 resin.

Description

Rubber composition and tire

Technical Field

The present invention relates to a rubber composition, and to a tire. The rubber composition may be used in a tire, such as a tire tread.

Background

In developing summer tires, particularly low rolling resistance summer tires, it is a challenge to further improve the balance between grip and rolling resistance, including dry grip and/or wet grip. While the tire should be robust.

Although many improvements have been made in this area over the last decades, there is still significant room to improve the above balance of properties.

Disclosure of Invention

The present invention relates to a rubber composition according to claim 1 and a tire according to claim 14.

The dependent claims relate to preferred embodiments of the invention.

It is an object of the present invention to provide a rubber composition having an advantageous balance of improved grip and limited hysteresis.

It is another object of the present invention to provide a rubber composition having sufficient tensile strength, good grip properties and limited hysteresis.

It is a further object of the present invention to provide a rubber composition that provides good wet and dry grip, optionally with sufficient tensile strength, with limited hysteresis (or rolling resistance, respectively).

In a first preferred aspect of the invention, a rubber composition is disclosed comprising 70 phr to 100 phr of at least one styrene-butadiene rubber, 0phr to 30 phr of at least one (further) diene-based rubber, 40 phr to 200 phr of at least one filler, at least 5phr of aluminum hydroxide, and at least 10phr of at least one (hydrocarbon) resin selected from one or more of dicyclopentadiene (DCPD) resin, cyclopentadiene (CPD) resin, and C5 resin.

It has been found that the combination of aluminium hydroxide and the claimed type of resin results in a surprisingly improved balance of rolling resistance and wet grip. Furthermore, tread wear can be further improved. Such a combination may be of particular interest for low rolling resistance tires, for example for low rolling resistance passenger car tires.

In a preferred aspect of the invention, the rubber composition comprises from 5phr to 80 phr of aluminum hydroxide, preferably from 10phr to 40 phr of aluminum hydroxide.

In a preferred aspect of the invention, the rubber composition comprises from 15 phr to 80 phr of resin, preferably from 15 phr to 40 phr, or even more preferably from 15 phr to 35 phr of resin.

In a preferred aspect of the invention, the resin is an at least partially hydrogenated resin, preferably a fully hydrogenated resin.

In a preferred aspect of the invention, the resin is aromatic or C9 modified.

In a preferred aspect of the invention, the resin is a hydrogenated and C9 modified resin, preferably a hydrogenated and C9 modified DCPD or CPD resin.

In a preferred aspect of the present invention, the resin has a glass transition temperature of 35 ℃ to 65 ℃. Preferably the resin has a relatively high but still limited glass transition temperature.

The glass transition temperature of the resins herein is determined as the midpoint of the peak by Differential Scanning Calorimeter (DSC) at a temperature increase rate of 10 ℃ per minute according to ASTM D6604 or equivalent.

In a preferred aspect of the invention, the resin is selected from one or more of a C5 resin, a CPD resin, a DCPD resin, a C9 modified C5 resin, a C9 modified CPD resin and a C9 modified DCPD resin. Optionally, these resins may be partially or fully hydrogenated.

In a preferred aspect of the invention, the resin is selected from one or more of a C9 modified CPD and a C9 modified DCPD resin.

In a preferred aspect of the invention, the resin has an aromatic proton content of from 5% to 15%, preferably from 8% to 12%. This content can be determined, for example, by NMR, as known to those skilled in the art.

In a preferred aspect of the invention, the resin has a softening point of 88 ℃ to 110 ℃ as determined according to ASTM E28 or equivalent, which may sometimes be referred to as the ring and ball softening point.

In a preferred aspect of the invention, the resin has a weight average molecular weight Mw of from 500g/mol to 800g/mol as determined by Gel Permeation Chromatography (GPC) using polystyrene calibration standards according to ASTM 5296-11 or equivalent.

In a preferred aspect of the invention, the rubber composition has a glass transition temperature of-25 ℃ to-15 ℃, determined as described herein below.

In a preferred aspect of the present invention, the at least one styrene-butadiene rubber is a solution-polymerized styrene-butadiene rubber; and/or the diene-based rubber is polyisoprene, preferably one or more of synthetic polyisoprene and natural rubber.

In a preferred aspect of the present invention, the rubber composition comprises i) a first styrene-butadiene rubber (preferably solution polymerized) having a glass transition temperature of-51 ℃ to-86 ℃, and ii) a second styrene-butadiene rubber (preferably solution polymerized) having a glass transition temperature of-10 ℃ to-45 ℃. Preferably, at least one (or both) of the first and second styrene-butadiene rubbers is functionalized to couple to a filler (e.g. to carbon black or silica), in particular to silica.

In a preferred aspect of the present invention, the rubber composition comprises 40 phr to 60 phr of the first styrene-butadiene rubber and 30 phr to 50phr of the second styrene-butadiene rubber.

In a preferred aspect of the invention, the first and second styrene-butadiene rubbers comprise at least one functional group configured for coupling to silica.

In a preferred aspect of the invention, at least one of the first and second styrene-butadiene rubbers comprises at least one functional group configured for coupling to silica, and wherein the functional group is selected from the group consisting of siloxy, alkoxy, amino, alkylsiloxy, stannylamino, aminosiloxane groups, and one or more of aminosilane groups and mercapto groups.

In a preferred aspect of the invention, one of the first and second styrene-butadiene rubbers is functionalized with an aminosilane group and the other of the first and second styrene-butadiene rubbers is functionalized with an aminosiloxane group.

In a preferred aspect of the present invention, one of the first and second styrene-butadiene rubbers is functionalized with at least one mercapto group, and the other of the first and second styrene-butadiene rubbers is functionalized with at least one of an aminosilane group or an aminosiloxane group. Preferably, the styrene butadiene rubber with the lower Tg is functionalized with mercapto groups.

In a preferred aspect of the present invention, the glass transition temperature of the first styrene-butadiene rubber is-20 ℃ to-35 ℃, and the glass transition temperature of the second styrene-butadiene rubber is-55 ℃ to-69 ℃.

In a preferred aspect of the present invention, the filler comprises predominantly silica.

In a preferred aspect of the invention, the filler comprises less than 10phr of carbon black, preferably less than 5phr of carbon black, and at least 40 phr of silica.

In a preferred aspect of the invention, the rubber composition comprises up to 85 phr of silica. For low rolling resistance applications or even ultra-low rolling resistance applications, limited amounts of silica or filler are particularly desirable.

In a preferred aspect of the present invention, the aluminum hydroxide has the following characteristicsOne or more of: (i) A D50 particle size of 0.2 to 5 μm, and (ii) a BET surface area of 1m ² G to 20m ² /g。

The particle size of the aluminium hydroxide is based on ISO 22412 or equivalent using a Zetasizer from Malvern ^TM Nano S, determined using dynamic light scattering.

The BET surface area of the aluminum hydroxide particles is determined according to ISO 9277 or equivalent.

In a preferred aspect of the invention, the silica has a BET surface area of 150m ² G to 220m ² (ii) in terms of/g. In particular, high surface area silica is preferred herein.

In a preferred aspect of the invention, the rubber composition comprises one or more of the following: (i) 0phr to less than 5phr of other resins other than the hydrocarbon resin; and (ii) 0phr to less than 5phr of an oil. Thus, in this preferred embodiment, the amount of other plasticizers and/or resins or oils is limited. Preferably, the oil content is less than 1phr or 0phr.

In a preferred aspect of the invention, the rubber may be functionalized (preferably end-functionalized) with groups comprising at least one mercapto group and at least one alkoxy group.

In a preferred aspect of the invention, the rubber composition comprises from 1phr to 4 phr of a vegetable oil having a glass transition temperature of from-75 ℃ to-100 ℃, preferably from-75 ℃ to-90 ℃.

The glass transition temperature of the oil was determined as the midpoint of the peak by Differential Scanning Calorimeter (DSC) at a temperature increase rate of 10 ℃ per minute according to ASTM E1356 or equivalent.

In a preferred aspect of the invention, the rubber composition comprises predominantly silica as filler, wherein the composition further comprises a mercaptosilane, preferably a blocked mercaptosilane, such as 3- (octanoylthio) -1-propyltriethoxysilane, in an amount of from 1phr to 20phr, preferably from 2 phr to 10phr.

In a preferred aspect of the invention, the rubber composition further comprises an α, ω -bis (N, N' -dihydrocarbylthiocarbamoyldithio) alkane, preferably from 0.5phr to 5phr, or even more preferably from 1phr to 4 phr.

In a preferred aspect of the invention, the α, ω -bis (N, N '-dihydrocarbylthiocarbamoyl disulfide) alkane is selected from the group consisting of 1,2-bis (N, N' -dibenzylthiocarbamoyldisulfide) ethane; 1,3-bis (N, N' -dibenzylthiocarbamoyldithio) propane; 1,4-bis (N, N' -dibenzylthiocarbamoyldithio) butane; 1,5-bis (N, N' -dibenzylthiocarbamoyldithio) pentane; 1,6-bis (N, N' -dibenzylthiocarbamoyldithio) hexane; 1,7-bis (N, N' -dibenzylthiocarbamoyldithio) heptane; 1,8-bis (N, N' -dibenzylthiocarbamoyldithio) octane; 1,9-bis (N, N' -dibenzylthiocarbamoyldithio) nonane; and 1,10-bis (N, N' -dibenzylthiocarbamoyldithio) decane. Preferably, the α, ω -bis (N, N '-dihydrocarbylthiocarbamoyl disulfide) alkane is 1,6-bis (N, N' -dibenzylthiocarbamoyldisulfide) hexane.

In a preferred aspect of the invention, the rubber composition comprises from 0.5phr to 15 phr, preferably from 0.5phr to 10phr, or more preferably from 1phr to 9 phr, or even more preferably from 1phr to 5phr of the rosin-based resin. In particular, it has been found that even surprisingly small amounts of rosin-based resins can significantly support improved wet grip and/or wet control performance. The use of such small amounts of rosin is also advantageous from a cost point of view.

In a preferred aspect of the present invention, the rosin-based resin (or rosin acid-based resin) is based on one or more of gum rosin and dimerized gum rosin.

In a preferred aspect of the present invention, the rosin-based resin has a softening point of 70 ℃ to 160 ℃.

The softening point of the resin is determined herein according to ASTM E28 or equivalent, which may sometimes be referred to as the ring and ball softening point.

In a preferred aspect of the present invention, the rosin-based resin has an acid value of 130 to 180.

In a preferred aspect of the invention, the rosin-based resin is a gum rosin, optionally having a softening point of 65 ℃ to 90 ℃, preferably 70 ℃ to 85 ℃, and preferably having an acid number of 140 to 180.

In a preferred aspect of the invention, the rosin-based resin is dimerized gum rosin, optionally having a softening point of 130 ℃ to 160 ℃, preferably 140 ℃ to 150 ℃, and preferably having an acid number of 130 to 160, and even more preferably having an acid number of 140 to 150.

In a preferred aspect of the present invention, the rosin-based resin mainly contains abietic acid. In the case where it is dimerized, it mainly contains dimerized abietic acid.

In a preferred aspect of the present invention, the rosin-based resin is based primarily on abietic acid.

Optionally, the term rosin-based resin may be replaced with rosin or rosin resin.

In a preferred aspect of the invention, the rubber composition comprises from 20phr to 80 phr of the resin (or hydrocarbon resin).

In a preferred aspect of the present invention, the rubber composition may comprise at least one and/or one additional diene-based rubber. Representative synthetic polymers may be the homopolymerization products of butadiene and its homologues and derivatives, such as methylbutadiene, dimethylbutadiene and pentadiene, as well as copolymers such as those formed from butadiene or its homologues 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, as well as 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, 1,3-butadiene or isoprene copolymers with monomers such as styrene, acrylonitrile and methyl methacrylate, and ethylene/propylene terpolymers, also known as Ethylene Propylene Diene Monomer (EPDM), and particularly 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 a preferred aspect of the invention, the composition comprises less than 5phr of natural rubber and/or polyisoprene, or is substantially free/free of natural rubber and/or polyisoprene.

Combinations of two or more rubbers are preferred, such as cis 1,4-polyisoprene rubber (natural or synthetic, but preferably natural), 3,4-polyisoprene rubber, styrene/isoprene/butadiene rubber, emulsion and solution polymerization derived styrene/butadiene rubber, cis 1,4-polybutadiene rubber and emulsion polymerization prepared butadiene/acrylonitrile copolymers.

In a preferred aspect of the invention, an emulsion polymerization-derived styrene-butadiene rubber (ESBR) having a bound styrene content of 20% to 28% may be used, or for some applications, an ESBR having a medium to relatively high bound styrene content, i.e., a bound styrene content of 30% to 45%, may be used. In some cases, the ESBR will have a bound styrene content of 26 to 31%. ESBR prepared by emulsion polymerization can mean styrene and 1,3-butadiene copolymerized 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 which contain from 2 to 40% by weight of bound acrylonitrile in the copolymer are also contemplated as diene-based rubbers.

In a preferred aspect of the invention, solution polymerization prepared SBR (SSBR) is 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 another embodiment, the solution styrene butadiene rubber is a tin coupled polymer. In another embodiment, the SSBR is functionalized to improve compatibility with silica. Additionally, or alternatively, the SSBR is mercapto-functionalized. This helps to improve the stiffness of the compound and/or its hysteresis behavior. Thus, for example, the SSBR may be a mercapto-functionalized, tin-coupled, solution polymerized copolymer of butadiene and styrene.

In a preferred aspect of the invention, synthetic or natural polyisoprene rubber is used. The synthesis of cis 1,4-polyisoprene and natural rubber is known per se to those skilled in the rubber art. The cis 1,4-microtissue content is preferably at least 90%, and typically at least 95% or even higher.

In a preferred aspect of the invention, 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 is 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-95 ℃ to-110 ℃. Suitable polybutadiene Rubber is commercially available as, for example, budene ® 1207, budene ® 1208, budene ® 1223 or Budene @ 1280 articles from The Goodyear Tire & Rubber Company. These high cis-1,4-polybutadiene rubbers may 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.

When referred to herein, the glass transition temperature or Tg of an elastomer or elastomer/rubber composition means one or more glass transition temperatures of the respective elastomer or elastomer composition in its uncured state or possibly in the cured state in the case of an elastomer composition.

Tg is determined according to ASTM D3418 by the midpoint or inflection point of the relevant phase of interest to the glass transition, as measured using a Differential Scanning Calorimeter (DSC) at a temperature change rate of 10 ℃/minute.

The term "phr", as used herein and in accordance with conventional practice, refers to "parts by weight of a respective material per 100 parts by weight of rubber or elastomer. Generally, using this convention, a rubber composition comprises 100 parts by weight rubber/elastomer. The claimed compositions may contain other rubbers/elastomers than those explicitly mentioned in the claims, provided that the phr value of the claimed rubber/elastomer is in accordance with the claimed phr range, and that the amount of all rubbers/elastomers in the composition yields a total of 100 parts rubber. In one example, the composition can further comprise 1phr to 10phr, optionally 1phr to 5phr, of one or more additional diene-based rubbers, such as SBR, SSBR, ESBR, PBD/BR, NR, and/or synthetic polyisoprene. In another example, the composition may comprise less than 5phr, preferably less than 3 phr, of additional diene-based rubber, or may also be substantially free of such additional diene-based rubber. Unless otherwise indicated, the terms "size" and "composition" and "formulation" are used interchangeably herein.

In a preferred aspect of the invention, the rubber composition may further comprise one or more additional oils, in particular (additional) processing oils. Processing oils may be included in the rubber composition as extending oils typically used to extend elastomers. Processing oil may also be included in the rubber composition by adding the oil directly during rubber compounding. The process oil used may include both extender oil present in the elastomer and process oil (process oil) added during compounding. Suitable process oils may include various oils known in the art, including aromatic oils, paraffinic oils, naphthenic oils, vegetable oils, and low PCA oils, such as MES, TDAE, SRAE, and heavy naphthenic oils. Suitable low PCA oils may include those having a polycyclic aromatic (PCA) content of less than 3 weight percent 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 2000 Parts, 2003, 62 nd edition, published by the Institute of Petroleum, united Kingdom. Some representative examples of vegetable oils (non-aminated and non-epoxidized) that may be used include soybean oil, sunflower oil, canola oil (rapeseed oil), corn oil, coconut oil, cottonseed oil, olive oil, palm oil, peanut oil, and safflower oil.

In a preferred aspect of the present invention, the rubber composition comprises silica. Common siliceous pigments that can be used in the rubber compound include, for example, conventional pyrogenic 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 acidifying soluble silicates such as sodium silicate. Such conventional silicas may be characterized, for example, as having a BET surface area as measured using nitrogen. In one embodiment, the BET surface area may be from 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 herein according to ASTM D5604-96 or equivalent. Conventional silica may also be characterized as having a dibutyl phthalate (DBP) absorption value as determined by ASTM D2414 or equivalent, suitably determined according to ASTM D2414, or equivalent, having a slope from 100 cm/100 g to 400cm, or from 150cm, or 100g to 300cm, respectively. Various commercially available silicas may be used, for example, silica commercially available from PPG Industries under the Hi-Sil trademark under the designation 210, 315G, EZ G; silicas available from Solvay, having, for example, the names ZeoSil 1165 MP and ZeoSil Premium 200 MP; and silicas available from Evonik AG, having, for example, the names VN2 and Ultrasil 6000 GR, 9100GR.

In a preferred aspect of the invention, the rubber composition may comprise pre-silanized and precipitated silica, which may for example have a particle size of 130m ² G to 210m ² G, optionally 130m ² G to 150m ² (iv)/g and/or 190m ² G to 210m ² In terms of/g, or even 195m ² (ii) g to 205m ² CTAB adsorption surface area per g. ForThe CTAB (cetyl trimethylammonium bromide) method for determining the surface area of silica (ASTM D6845) is known to those skilled in the art.

In a preferred aspect of the invention, a surface-modified precipitated silica treated with at least one silane or silazane is employed prior to addition to the rubber composition. Suitable surface modifying agents include, but are not limited to, alkylsilanes, alkoxysilyl polysulfides, organomercaptoalkoxysilanes, and hexamethyldisilazane.

The optional silica dispersing aids that may be used may be present in an amount of from 0.1 to 25 wt% based on the weight of silica, with amounts of from 0.5 to 20 wt% being suitable and amounts of from 1 to 15 wt% being also suitable, based on the weight of silica.

Various pretreated precipitated silicas are described in U.S. patent 4,704,414, U.S. patent 6,123,762, and U.S. patent 6,573,324.

Some examples of pretreated silica (i.e., silica that has been pre-surfaced with silane) suitable for use in the practice of the present invention include Ciptane 255 LD and Ciptane LP (PPG Industries) silica that has been pretreated with mercaptosilane, and the reaction products Copyl 8113 (Degussa) and Copyl 6508 between organosilane bis (triethoxysilylpropyl) polysulfide (Si 69) and Ultrasil VN3 silica, agilon 400 silica from PPG Industries, agilon 454 silica from PPG Industries, and Agilon 458 silica from PPG Industries. Some representative examples of preferred pre-silanized precipitated silicas include Agilon 400, agilon 454 and Agilon 458 from PPG Industries.

Representative silica coupling agents (silica coupling agents) having a moiety reactive with the pre-silanized precipitated silica and hydroxyl groups on the precipitated silica and another moiety that interacts with the elastomer may include, for example: (A) a bis (3-trialkoxysilylalkyl) polysulfide having an average of 2 to 4, alternatively 2 to 2.6, alternatively 3.2 to 3.8 sulfur atoms in its connecting bridge, or (B) an alkoxyorganomercaptosilane, or (C) a combination thereof. A representative example of such bis (3-trialkoxysilylalkyl) polysulfide is bis (3-triethoxysilylpropyl) polysulfide. As noted, for pre-silanized precipitated silica, the silica coupling agent may desirably be an alkoxyorganomercaptosilane. For precipitated silicas that are not pre-silanized, the silica coupling agent may be or comprise a bis (3-triethoxysilylpropyl) polysulfide.

In a preferred aspect of the invention, the rubber composition does not include the addition of a silica coupling agent to the rubber composition (and thus does not include a silica coupling agent).

As shown, in a preferred embodiment, the rubber composition may contain an additional silica coupling agent added to the rubber composition, particularly a bis (3-triethoxysilylpropyl) polysulfide having an average of 2 to 4 connecting sulfur atoms in its polysulfide bridges, in combination with an additional precipitated silica (non-pre-silanized precipitated silica) added to the rubber composition, wherein the ratio of pre-silanized precipitated silica to the precipitated silica is desirably at least 8/1, or at least 10/1.

In a preferred aspect of the present invention, the rubber composition may contain carbon black. Representative examples of such carbon blacks include N110, 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 grades. These carbon blacks have iodine absorptions of 9-145 g/kg and 34 cm ³ /100g-150 cm ³ DBP value of/100 g. Iodine absorbance values may be suitably determined according to ASTM D1510 or an equivalent. Conventional carbon blacks may be used as conventional fillers in amounts of from 10phr to 150 phr. However, in a preferred embodiment, the composition comprises up to 10phr of carbon black, preferably up to 5phr of carbon black, as preferred embodiments relate to high silica compounds and their property improvements.

In a preferred aspect of the invention, other fillers may be used in the rubber composition, including particulate fillers, including Ultra High Molecular Weight Polyethylene (UHMWPE), crosslinked particulate polymer gels, including those disclosed in U.S. Pat. No. 6,242,534, U.S. Pat. No. 6,207,757, U.S. Pat. No. 6,133,364, U.S. Pat. No. 6,372,857, U.S. Pat. No. 5,395,891, or U.S. Pat. No. 6,127,488, and plasticized starch composite fillers, including but not limited to those disclosed in U.S. Pat. No. 5,672,639. Syndiotactic polybutadiene may also be used. These other fillers may be used in amounts of 1phr to 30 phr.

In a preferred aspect of the present invention, the rubber composition may contain conventional sulfur-containing organosilicon compounds or silanes. Examples of suitable sulfur containing organosilicon compounds have the formula:

I

wherein Z is selected from

/>

Wherein R is ¹ Is alkyl, cyclohexyl or phenyl of 1 to 4 carbon atoms; r ² Is alkoxy of 1 to 8 carbon atoms or cycloalkoxy 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 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 R is ² 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 or 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. Pat. No. 6,608,125. In 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. 2003/0130535. In one embodiment, the sulfur containing organosilicon compound is Si-363 from Degussa. The amount of sulfur containing organosilicon compound in the rubber composition can vary depending on the level of other additives used. In general, the amount of compound may be from 0.5phr to 20phr. In one embodiment, the amount will be from 1phr to 10phr.

In a preferred aspect of the invention, the rubber composition comprises less than 0.1phr of cobalt salt or 0phr of cobalt salt.

It will be readily understood by those skilled in the art that the rubber composition can be compounded by methods generally known in the rubber compounding art, such as mixing the various sulfur-vulcanizable constituent rubbers with various common additive materials such as, for example, sulfur donors, curing aids such as activators and scorch retarders, and processing additives such as oils, resins including tackifying resins and plasticizers, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants, antiozonants, and peptizing agents. As known to those skilled in the art, depending on the intended use of the sulfur-vulcanizable and sulfur-vulcanized material (rubbers), the additives mentioned above are selected and commonly used in conventional amounts. Some representative examples of sulfur donors include elemental sulfur (free sulfur), amine disulfides (amine disulfides), 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 8 phr, alternatively 1.5 phr to 6 phr. Typical amounts of tackifier resins, if used, include, for example, 0.5phr to 10phr, usually 1phr to 5phr. Typical amounts of processing aids, if used, include, for example, 1phr to 50phr (which may include, in particular, oils). Typical amounts of antioxidants, if used, may, for example, comprise from 1phr to 5phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as, for example, those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344-346. Typical amounts of antiozonants, if used, can, for example, comprise from 1phr to 5phr. Typical amounts of fatty acids, which may include stearic acid if used, may include, for example, 0.5phr to 3 phr. Typical amounts of wax, if used, may generally be employed at levels of from 1phr to 5phr. Microcrystalline waxes are typically used. Typical amounts of peptizers, if used, are generally from 0.1phr to 1 phr. Typical peptizers may be, for example, pentachlorophenol and/or dibenzamidodiphenyl disulfide.

Accelerators may be preferred, but are not necessary for controlling the time and/or temperature required for vulcanization and for improving the properties of the vulcanizate. In one embodiment, a single accelerator system, i.e., a primary accelerator, may be used. The one or more primary accelerators may be used in a total amount of 0.5phr to 4 phr, alternatively 0.8 phr to 1.5 phr. In another embodiment, a combination of primary and secondary accelerators may be used, with the secondary accelerators being used in smaller amounts, e.g., 0.05phr to 3 phr, to activate and improve the properties of the vulcanized rubber. Combinations of these accelerators might be expected to produce a synergistic effect on the final properties and to some extent better than those produced by the use of either accelerator alone. In addition, slow acting accelerators may be used which are not affected by normal processing temperatures but produce satisfactory cure at ordinary vulcanization temperatures. Vulcanization retarders may also be used. Suitable types of accelerators that can be used 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, it may be, for example, a guanidine, dithiocarbamate or thiuram compound. Suitable guanidines include diphenylguanidine (dipheynylguanidine), and the like. Suitable thiurams include tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetraphenylthiuram 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 curatives, including the sulfur-vulcanizing agents, may typically be mixed in a final stage, which is often referred to as a "productive" mixing stage, where 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. 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 thermomechanical working varies with operating conditions and variations in the volume and nature of the components. For example, the thermomechanical working may be from 1 to 20 minutes.

In a preferred aspect of the present invention, there is provided a rubber product comprising a rubber composition according to the present invention, selected from the group consisting of a tire, a power transmission belt, a hose, a track, an air sleeve and a conveyor belt.

In a preferred aspect of the invention, the rubber product comprising the rubber composition according to the invention is a tire comprising one or more rubber components selected from the group consisting of tread, shear band (shearband), rubber spoke, base tread (undercut), sidewall, apex, flipper, chipper, chafer, carcass, belt, overlay, wherein one or more of the rubber components comprises the rubber composition. In a preferred embodiment, the tire has a tread comprising a rubber composition. In one preferred embodiment, the tire has a tread that employs one or more tread cap (cap) layers, wherein the rubber composition according to the invention is in one or more of the two radially outermost tread cap layers, preferably in the radially outermost tread cap layer.

In another embodiment, the rubber composition is in a tread cap layer radially inward of the radially outermost tread cap layer. The rubber composition according to the invention is then optionally not in the radially outermost tread cap layer. In such embodiments, the radially outermost tread cap layer does not comprise a rubber composition according to the present invention. In contrast, the rubber composition of the tread cap layer radially below the radially outermost tread cap layer has a rubber composition according to the invention (or one or more of its embodiments). This arrangement or configuration may help to maintain the level of grip, particularly wet grip, at a similar level when the first tread cap layer is worn and the radial rib or block height of the tread has been reduced. The loss of tread height can be at least partially compensated by the improved grip of the rubber composition according to the invention.

The vulcanization of the pneumatic tire of the present invention can 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 from 110 ℃ to 180 ℃. Any conventional vulcanization process may be used, such as heating in a press or mold, heating with superheated steam or hot air. However, it is generally preferred that the tire of the present invention be cured at a temperature of from 132 ℃ to 166 ℃. More typically the tire of the present invention is cured at a temperature of 143 ℃ to 154 ℃. Such tires can be manufactured, shaped, molded and cured by various methods that are known and obvious to those skilled in the art.

Drawings

The structure, operation, and advantages of the present invention will become more apparent upon consideration of the following description taken in conjunction with the accompanying drawings, in which fig. 1 is a schematic cross section of a tire including a rubber component having a rubber composition according to an embodiment of the present invention.

Detailed Description

Fig. 1 is a schematic cross section of a tire 1 according to an embodiment of the present invention. The tire 1 has a plurality of tire components such as a tread 10, an inner liner 13, a belt comprising four belt plies 11, a carcass ply 9, two sidewalls 2 and two bead regions 3, a bead filler apex 5 and beads 4. The exemplary tire 1 is suitable for mounting on a rim of a vehicle, such as a truck or a car, for example. As shown in fig. 1, the belt ply 11 may be covered by an overlay ply 12, and/or may include one or more breaker layers. The carcass ply 9 comprises a pair of axially opposite end portions 6 associated respectively with each of the beads 4. Each axial end portion 6 of the carcass ply 9 may be turned up and around each bead 4 to a position to anchor each axial end portion 6. The turnup portion 6 of the carcass ply 9 may engage the axially outer surfaces of the two flippers 8 and the axially inner surfaces of the two chippers 7 (which are also considered tire assemblies). As shown in FIG. 1, an exemplary tread 10 may have circumferential grooves 20, each groove 20 substantially defining a U-shaped opening in the tread 10. The main portion of the tread 10 may be formed from one or more tread compounds. Furthermore, the groove 20, in particular the bottom and/or the sidewalls of the groove 20, may be reinforced by a rubber compound having a higher hardness and/or stiffness than the remaining tread compound. Such reinforcements may be referred to herein as groove reinforcements.

While the embodiment of fig. 1 presents a plurality of tire components including, for example, apex 5, chipper 7, flipper 8, and overlay 12, these and other components are not mandatory to the present invention. The turnup end of the carcass ply 9 is also not essential to the invention, or may pass over and terminate axially inward of the bead 4 on the opposite side of the bead region 3 rather than axially outward of the bead 4. The tire may also have, for example, a different number of grooves 20, for example, less than 4 grooves.

In one embodiment, the tread 10 of the tire 1 or another tire comprises a rubber composition according to an embodiment of the present invention as identified in table 1 below. The rubber composition according to the preferred embodiment of the present invention is used for a tread or tread layer contacting a road.

TABLE 1

¹ As Sprintan from Trinseo ^TM SLR 3402 having a Tg of-62 ℃ and mercapto-alkoxysilane functionality

² HPR 355H as derived from JSR, having a Tg of about-27 ℃ and an aminosilane functionality

³ Natural rubber

⁴ Dercolyte from DRT ^TM A115, having a Tg of about 70 ℃

⁵ As Oppera from Exxon Mobil ^TM 383 having a Tg of about 54 ℃

⁶ Al(OH) ₃ Having a BET surface area of 15 m, d50 of 0.4 μm, d90 of 0.8 μm and d10 of 0.3 μm, and a material density of 2.4g/cm

⁷ As Zeosil from Solvay ^TM Premium 200 MP with BET surface area of 215 m/g

⁸ Bis-triethoxysilylpropyl disulfide

⁹ Bis (triethoxysilylpropyl) tetrasulfide

¹⁰ Based on dihydroquinolines and phenylenediamines

¹¹ As Vulcure ^TM 1,6-bis (N, N-dibenzylthiocarbamoyldithio) hexane from Lanxess contains about 10% oil and carbon black

¹² TBBS and DPG types

Table 2 shows the tire properties obtained based on the comparative examples and inventive examples listed above in table 1. As is apparent from the results below, the wet grip and tread wear of the inventive examples are surprisingly significantly improved by changing the resin type. Furthermore, the wet grip remains flat, so that the overall balance of these properties has been improved according to example 1 of the present invention.

TABLE 2

^a Laboratory tests show thatRatio, normalized to a comparative example, based on Dynamic Mechanical Analysis (DMA) of tan delta shear response at 30 ℃

^b Laboratory tests, the results being in percentages, normalized to the comparative examples, based on the determination of transmissible friction forces on a linear friction tester

^c Laboratory tests, results in percentages, normalized to comparative examples, based on abrasion measured according to ASTM D5963

Claims (15)

1. A rubber composition comprising:

70 From phr to 100 phr of at least one styrene-butadiene rubber,

from 0phr to 30 phr of at least one additional diene-based rubber,

40 From phr to 200 phr of at least one filler,

at least 5phr of aluminum hydroxide, and

at least 10phr of at least one hydrocarbon resin selected from one or more of DCPD resin, CPD resin and C5 resin.

2. The rubber composition of claim 1, wherein the rubber composition comprises from 5phr to 80 phr of the aluminum hydroxide; and/or wherein the rubber composition comprises from 15 phr to 80 phr of the hydrocarbon resin.

3. The rubber composition according to claim 1 or 2, wherein the hydrocarbon resin is a hydrogenated hydrocarbon resin and/or wherein the hydrocarbon resin is aromatic modified.

4. The rubber composition according to at least one of the preceding claims, wherein the resin has a glass transition temperature of from 35 ℃ to 65 ℃.

5. The rubber composition of at least one of the preceding claims, wherein the at least one styrene-butadiene rubber is a solution-polymerized styrene-butadiene rubber, and wherein the at least one diene-based rubber is a synthetic polyisoprene, a natural rubber, or both.

6. The rubber composition of claim 5, wherein the at least one styrene-butadiene rubber comprises (i) a first styrene-butadiene rubber having a glass transition temperature of from-51 ℃ to-86 ℃, and (ii) a second styrene-butadiene rubber having a glass transition temperature of from-10 ℃ to-45 ℃; and optionally wherein at least one of the first and second styrene-butadiene rubbers is functionalized to couple to silica.

7. The rubber composition according to at least one of the preceding claims, wherein the filler comprises predominantly silica; and/or wherein the filler comprises less than 10phr of carbon black and at least 40 phr of silica.

8. The rubber composition according to at least one of the preceding claims, wherein the rubber composition comprises at most 85 phr of silica.

9. The rubber composition according to at least one of the preceding claims, wherein the aluminum hydroxide has one or both of the following characteristics: (i) D50 particle size of 0.2 to 5 μm, (ii) BET surface area of 1m ² G to 20m ² /g。

10. The rubber composition according to at least one of the preceding claims, wherein the silica has 150m ² G to 220m ² BET surface area in g.

11. The rubber composition according to at least one of the preceding claims, comprising one or both of the following: (i) 0phr to less than 5phr of other resins other than the hydrocarbon resin; and (ii) 0phr to less than 5phr of an oil.

12. The rubber composition according to at least one of the preceding claims, wherein the resin has an aromaticity of 8% to 12%; and/or wherein the resin has a softening point of 88 ℃ to 110 ℃.

13. The rubber composition of at least one of the preceding claims, wherein one of the first and second styrene-butadiene rubbers is functionalized with at least one mercapto group; and wherein the other of the first and second styrene-butadiene rubbers is functionalized with at least one of an aminosilane group or an aminosiloxane group.

14. A tire comprising a rubber composition according to at least one of the preceding claims.

15. The tire of claim 14, having a tread employing a radially outermost tread cap layer, wherein the radially outermost tread cap layer comprises the rubber composition.

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