Tire tread rubber composition and related methods

Abstract

To provide a tire tread rubber composition and related methods.SOLUTION: There are disclosed tire tread rubber compositions made of specified ingredients including an elastomer component including at least one styrene-butadiene rubber with a silica-reactive functional group and at least one non-functionalized styrene-butadiene rubber, a filler component including reinforcing silica filler and carbon black, hydrocarbon resin, liquid plasticizer (which includes a low molecular weight styrene-butadiene rubber), and a cure package. There are also disclosed a tire including a road-contacting tread comprising the tire tread rubber composition and methods for providing a tire with a road-contacting tread which tire has balanced wet performance, rolling resistance and cornering performance, the method comprising using the tire tread rubber composition in the road-contacting tread.SELECTED DRAWING: None

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This application is directed to tire tread rubber compositions and related methods. [Background technology]

[0002] A tire includes many components, including a tread that contacts the road surface. The specific ingredients used to prepare the rubber composition that comprises the tire tread can vary. Formulating tire tread rubber compositions is a complex science, as changes to the formulation that result in an improvement in one property (e.g., wet performance) can result in a deterioration of another property (e.g., dry traction). Summary of the Invention

[0003] Disclosed herein are rubber compositions for tire treads and related methods.

[0004] According to a first embodiment disclosed herein, a tire tread rubber composition is disclosed. The tire tread rubber composition of the first embodiment includes: (a) 100 parts of an elastomer component including: (i) 51 to 75 parts of at least one styrene-butadiene rubber having a silica-reactive functional group and a Tg of about −50 to about −35° C., preferably about −50 to about −40° C.; and (ii) 25 to 49 parts of at least one non-functionalized styrene-butadiene rubber having a Tg of about −30 to about −15° C., preferably about −25 to about −15° C.; and (b) at least one reinforcing silica filler in an amount of 60 to 90 phr, preferably about 200 to about 350 mcg. 2 / g BET surface area; (c) 10 phr or less of a carbon black filler; (d) 2 to 14 phr of at least one hydrocarbon resin having a Tg of about 40 to about 60°C; (e) 15 to 35 phr of a liquid plasticizer; and (f) a cure package, at least a portion of (e) being provided by a low molecular weight styrene-butadiene rubber.

[0005] According to a second embodiment disclosed herein, there is disclosed a tire including a road-contacting tread, wherein the road-contacting tread of the tire of the second embodiment comprises a tire tread rubber composition according to the first embodiment disclosed herein.

[0006] According to a third embodiment disclosed herein, there is provided a method for providing a tire having a road-contacting tread, wherein the tire has balanced wet performance, rolling resistance, and cornering performance, the method comprising utilizing a tire tread rubber composition according to the first embodiment in the road-contacting tread. The present disclosure includes the following embodiments. <1> 1. A tire tread rubber composition comprising: a. 100 parts of an elastomer component, i. 51 to 75 parts of at least one styrene-butadiene rubber having silica-reactive functional groups and a Tg of about -50 to about -35°C, preferably about -50 to about -40°C; ii. an elastomer component comprising 25 to 49 parts of at least one non-functionalized styrene-butadiene rubber, the non-functionalized styrene-butadiene rubber having a Tg of about -30 to about -15°C, preferably about -25 to about -15°C; b. At least one reinforcing silica filler in an amount of 60 to 90 phr, preferably from about 200 to about 350 m 2 a reinforcing silica filler having a BET surface area of ​​1000 nm / g; c. 10 phr or less of carbon black filler; d. 2 to 14 phr of at least one hydrocarbon resin, at about 40 to about 60°C a hydrocarbon resin having a Tg; e. 15 to 35 phr of liquid plasticizer, f. a curing package; and A tire tread rubber composition wherein at least a portion of (e) is provided by a low molecular weight styrene-butadiene rubber. <2> the low molecular weight styrene-butadiene rubber has a Tg of about -30 to about -10°C and a Mw of less than 200,000 grams / mole according to a polystyrene standard; <1> The tire tread rubber composition according to claim 1. <3> (a)(i) and (a)(ii) are present in a total amount of at least 90% by weight of the elastomer component, preferably 100% by weight of the elastomer component; <1> or <2> The tire tread rubber composition according to claim 1. <4> The at least one hydrocarbon resin comprises an aliphatic resin, preferably a C5 homopolymer or copolymer resin. <1> ~ <3> The tire tread rubber composition according to any one of claims 1 to 4. <5> The rubber composition has a compound Tg of about 10 to about -20°C, preferably about 0 to about -15°C. <1> ~ <4> The tire tread rubber composition according to any one of claims 1 to 4. <6> the styrene-butadiene rubber (a)(i) has a lower Mw than the styrene-butadiene rubber (a)(ii), <1> ~ <5> The tire tread rubber composition according to any one of claims 1 to 4. <7> the at least one styrene-butadiene rubber (a)(i) has a Mw of about 300,000 to about 500,000 grams / mole, and the at least one styrene-butadiene rubber (a)(ii) has a Mw of about 400,000 to about 700,000 grams / mole, both according to polystyrene standards; <6> The tire tread rubber composition according to claim 1. <8> (a)(i) comprises oil-extended styrene-butadiene rubber extended with 30 to 40 parts of a liquid plasticizer per 100 parts of styrene-butadiene rubber; <1> ~ <7> The tire tread rubber composition according to any one of claims 1 to 4. <9> The elastomer component has an average Tg of about -50 to about -20°C, preferably about -45 to about -25°C. <1> ~ <8> The tire tread rubber composition according to any one of claims 1 to 4. <10> (d) and (e) are present in a total amount of not more than 35 phr. <1> ~ <9> The tire tread rubber composition according to any one of claims 1 to 4. <11> (a)(ii) comprises the non-functionalized styrene-butadiene rubber (iii) extended with 30 to 40 parts of the low molecular weight styrene-butadiene rubber per 100 parts of the non-functionalized styrene-butadiene rubber (iii); <1> ~ <10> The tire tread rubber composition according to any one of claims 1 to 4. <12> (a)(i) is functionalized with at least one of a substituted or unsubstituted amino group, an amide residue, an isocyanate group, an imidazolyl group, an indolyl group, a substituted or unsubstituted imino group, a nitrile group, a pyridyl group, or a ketimine group, preferably an unsubstituted amino group, a substituted amino group, or a substituted imino group. <1> ~ <11> The tire tread rubber composition according to any one of claims 1 to 4. <13> The rubber composition has a tan δ value at 60°C of 0.15 to 0.25, preferably 0.16 to 0.2, and has the following properties: a. having a value of tan δ at 0°C that is at least 3.5 times the value of tan δ at 60°C, preferably 3.7 to 4.7 times the value of tan δ at 60°C; b. having a value of tan δ at 30°C that is at least 1.6 times the value of tan δ at 60°C, preferably 1.6 to 2 times the value of tan δ at 60°C; or c. having an E' value at 30°C that is at least 70 times the tan δ value at 60°C, preferably 75 to 90 times the tan δ value at 60°C, Satisfy at least one of the above <1> ~ <12> The tire tread rubber composition according to any one of claims 1 to 4. <14> (c) is satisfied, <13> The tire tread rubber composition according to claim 1. <15> Each of (a), (b), and (c) is satisfied. <13> The tire tread rubber composition according to claim 1. <16> The rubber composition comprises: (d) having an Eb at 23°C of at least 400%, more preferably at least 450%; (e) having an Eb at 100°C of at least 275%, preferably at least 300%, more preferably at least 325%, or (f) having a value of Tb at 100°C x Eb at 100°C of at least 3100, preferably at least 3500, more preferably at least 3700, or even at least 4000; <1> ~ <15> The tire tread rubber composition according to any one of claims 1 to 4. <17> Each of (d) to (f) is satisfied, <16> The tire tread rubber composition according to claim 1. <18> The aforementioned <1> ~ <17> 10. A tire comprising a tread for contacting a road surface, the tread comprising the tire tread rubber composition according to any one of claims 1 to 9. <19> 1. A method for providing a tire having a road-contacting tread, said tire having balanced wet performance, rolling resistance, and cornering performance, said method comprising: <1> ~ <17> Utilizing the tire tread rubber composition according to any one of claims 1 to 4 for the road-contacting tread. DETAILED DESCRIPTION OF THE INVENTION

[0007] Disclosed herein are rubber compositions for tire treads and related methods.

[0008] According to a first embodiment disclosed herein, a tire tread rubber composition is disclosed. The tire tread rubber composition of the first embodiment includes: (a) 100 parts of an elastomer component including: (i) 51 to 75 parts of at least one styrene-butadiene rubber having a silica-reactive functional group and a Tg of about −50 to about −35° C., preferably about −50 to about −40° C.; and (ii) 25 to 49 parts of at least one non-functionalized styrene-butadiene rubber having a Tg of about −30 to about −15° C., preferably about −25 to about −15° C.; and (b) at least one reinforcing silica filler in an amount of 60 to 90 phr, preferably about 200 to about 350 mcg. 2 / g BET surface area; (c) 10 phr or less of a carbon black filler; (d) 2 to 14 phr of at least one hydrocarbon resin having a Tg of about 40 to about 60°C; (e) 15 to 35 phr of a liquid plasticizer; and (f) a cure package, at least a portion of (e) being provided by a low molecular weight styrene-butadiene rubber.

[0009] According to a second embodiment disclosed herein, there is disclosed a tire including a road-contacting tread, wherein the road-contacting tread of the tire of the second embodiment comprises a tire tread rubber composition according to the first embodiment disclosed herein.

[0010] According to a third embodiment disclosed herein, there is provided a method for providing a tire having a road-contacting tread, wherein the tire has balanced wet performance, rolling resistance, and cornering performance, the method comprising utilizing a tire tread rubber composition according to the first embodiment in the road-contacting tread.

[0011] definition The terminology used herein is for the purpose of describing the embodiments only and should not be construed as limiting the invention as a whole.

[0012] As used herein, the term "BR" or "polybutadiene" refers to a homopolymer of 1,3-butadiene.

[0013] As used herein, the term "majority" refers to more than 50% (e.g., at least 50.1%, at least 50.5%, at least 51%, etc.).

[0014] As used herein, the term "minority" refers to less than 50% (e.g., 49.5% or less, 49% or less, etc.).

[0015] As used herein, the abbreviation Mn is used for number average molecular weight.

[0016] As used herein, the abbreviation Mp is used for peak molecular weight.

[0017] As used herein, the abbreviation Mw is used for weight average molecular weight.

[0018] Unless otherwise specified herein, the term "Mooney viscosity" refers to Mooney viscosity, ML 1+4 Those skilled in the art will appreciate that the Mooney viscosity of a rubber composition is measured prior to vulcanization or curing.

[0019] As used herein, the term "natural rubber" means naturally occurring rubber, such as that which can be harvested from sources such as Hevea rubber trees, and from non-Hevea sources (e.g., guayule and dandelion such as TKS). In other words, the term "natural rubber" should be interpreted to exclude synthetic polyisoprene.

[0020] As used herein, the term "phr" means parts per hundred of rubber. 100 parts of rubber are also referred to herein as 100 parts of elastomeric component.

[0021] As used herein, the term "polyisoprene" refers to synthetic polyisoprene. In other words, this term is used to refer to a polymer made from isoprene monomers and should not be interpreted as including naturally occurring rubber (e.g., Hevea rubber, guayule rubber, or dandelion rubber). However, the term "polyisoprene" should be interpreted as including polyisoprene made from natural sources of isoprene monomers.

[0022] As used herein, the term "SBR" means styrene-butadiene copolymer rubber.

[0023] As used herein, the term "tread" refers to both the portion of the tire that contacts the road under normal inflation and load, and any subtread.

[0024] Tire tread rubber composition As noted above, a first embodiment disclosed herein is directed to a tire tread rubber composition made from certain ingredients, a second embodiment is directed to a tire including a road-contacting tread comprising the tire tread rubber composition of the first embodiment, and a third embodiment disclosed herein is directed to a method of providing a tire having a road-contacting tread, the tire having balanced wet performance, rolling resistance, and cornering performance, the method comprising utilizing the tire tread rubber composition of the first embodiment in the road-contacting tread. The subject rubber compositions are generally used in preparing treads for tires by a process comprising forming a tread pattern by molding and curing one of the subject rubber compositions. Thus, the tire tread comprises a cured form of one of the tire tread rubber compositions. The tire tread rubber composition may exist in the form of a tread that has been formed but not yet incorporated into a tire, and / or may be present within a tread that forms part of a tire.

[0025] According to the first to third embodiments disclosed herein, the Tg of the overall rubber composition can vary. The Tg of the overall rubber composition can be referred to as the compound Tg or rubber composition Tg. In certain embodiments of the first to third embodiments, the rubber composition has a compound Tg of 10 to −20° C. (e.g., 10, 8, 6, 5, 4, 2, 0, −2, −4, −5, −6, −8, −10, −12, −14, −15, −16, −18, or −20° C.), preferably about 0 to about −15° C. or 0 to 15° C. (e.g., 0, −2, −4, −5, −6, −8, −10, −12, −14, or −15° C.). The compound Tg of a rubber composition can generally be measured according to the guidelines of ASTM D5992-96(2011) using a dynamic mechanical thermal spectrometer (such as the Gabo instrument described below, operating in tensile mode) and using a temperature sweep (-70 to 65°C) under specific test conditions (i.e., a frequency of 52 Hz, a static strain of 6%, a dynamic strain of 0.1%, and a specimen geometry of 4.75 mm wide x 29 mm long x 2 mm deep), with the specimen cured at 170°C for 15 minutes, and the Tg estimated from the resulting curve using an oscillatory method.

[0026] Elastomer components As discussed above, according to the first to third embodiments, the tire tread rubber composition comprises (includes) 100 parts of an elastomer component including: (i) 51 to 75 parts of at least one styrene-butadiene rubber having a silica-reactive functional group and a Tg of about -50 to about -35°C; and (ii) 25 to 49 parts of at least one non-functionalized styrene-butadiene rubber having a Tg of about -30 to about -15°C. In preferred embodiments of the first to third embodiments, at least 90% by weight (e.g., 90%, 91%, In some embodiments, at least 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more of the elastomer component consists of at least one SBR(i) and at least one SBR(ii), with the remaining portion (e.g., 10%, 9%, 8%, etc.) of the elastomer component consisting of one or more additional rubbers, preferably selected from conjugated diene-containing polymers, as discussed below. In certain such embodiments of the first through third embodiments, 100% by weight of the elastomer component is at least one SBR(i) and at least one SBR(ii). In other words, in such embodiments, the at least one SBR(i) and at least one SBR(ii) are the only types of rubber present in the elastomer component.

[0027] According to the first to third embodiments disclosed herein, the Tg of the elastomeric component can vary. In certain embodiments of the first to third embodiments, the elastomeric component has an average Tg of about −50 to about −20° C. or −50 to −20° C. (e.g., −50, −48, −46, −45, −44, −42, −40, −38, −36, −35, −34, −32, −30, −28, −26, −25, −24, −22, or −20° C.), preferably about −45 to about −25° C. or −45 to −25° C. (e.g., −45, −44, −42, −40, −38, −36, −35, −34, −32, −30, −28, −26, or −25° C.). The average Tg of an elastomeric component can be calculated using the Tg of each rubber present in 100 parts of the elastomeric component and considering their relative weight percentages. If one(or more) rubbers are oil-extended, only the amount of rubber (i.e., excluding any amount of oil) is used to calculate the average Tg of the elastomeric component. If one(or more) rubbers are oil-extended, the Tg of the un-oil-extended rubber is used to calculate the average Tg of the elastomeric component.

[0028] Functionalized styrene-butadiene rubber As discussed above, according to the first to third embodiments disclosed herein, the elastomer component of the tire tread rubber composition comprises (includes) 51 to 75 parts by weight (e.g., 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, or 75 parts) of at least one styrene-butadiene rubber having silica-reactive functional groups and a Tg of about −50 to about −35° C. or −50 to −35° C. (e.g., −50, −49, −48, −47, −46, −45, −44, −43, −42, −41, −40, −39, −38, −37, −36, or −35° C.). Because the at least one SBR (i) is present in an amount of at least 51 phr, it can be considered a majority (by weight) of the elastomeric components of the tire tread rubber composition according to the first through third embodiments. In certain preferred embodiments of the first through third embodiments disclosed herein, the at least one SBR having silica-reactive functional groups has a Tg of about −50 to about −40° C. or −50 to −40° C. (e.g., −50, −49, −48, −47, −46, −45, −44, −43, −42, −41, −40° C.). In certain of the first to third embodiments disclosed herein, only one SBR having a silica-reactive functional group and a Tg of about −50 to about −35° C. or −50 to −35° C. is used in the tire tread rubber composition, and in certain such embodiments, no other functionalized SBRs are present in the tire tread rubber composition (i.e., the only functionalized SBR in the tire tread rubber composition is SBR (i) having a silica-reactive functional group and a Tg of about −50 to about −35° C. or −50 to −35° C.). In other of the first to third embodiments disclosed herein, two SBRs having silica-reactive functional groups and a Tg of about −50 to about −35° C. or −50 to −35° C. are used in the tire tread rubber composition.In certain preferred embodiments of the first through third embodiments disclosed herein, the at least one SBR having silica-reactive functional groups and a Tg of about −50° C. to about −35° C., or −50 to −35° C., is present in an amount of 55 to 70 parts by weight (e.g., 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, or 75 parts by weight) or 55 to 65 parts by weight (e.g., 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, or 65 parts by weight) per 100 parts by weight of the elastomer component.

[0029] In certain embodiments of the first through third embodiments disclosed herein, at least one SBR(i) has a molecular weight of about 300,000 to about 550,000 grams / mole or 300,000 to 550,000 grams / mole (e.g., 300,000, 325,000, 350,000, 375,000, 400,000, 425,000, 450,000, 475,000, 500,000, 525,000, or 550,000 grams / mole), preferably about The Mw is from 300,000 to about 500,000 or from 300,000 to 500,000 grams / mol (e.g., 300,000, 325,000, 350,000, 375,000, 400,000, 425,000, 450,000, 475,000, or 500,000 grams / mol), more preferably from about 350,000 to about 450,000 or from 350,000 to 450,000 grams / mol (e.g., 350,000, 375,000, 400,000, 425,000, or 450,000 grams / mol). In certain embodiments of the first through third embodiments disclosed herein, at least one SBR(i) has a molecular weight of about 250,000 to about 450,000 grams / mole or 250,000 to 450,000 grams / mole (e.g., 250,000, 275,000, 300,000, 325,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1000,000, 1100,000, 1200,000, 1300,000, 1400,000, 1500,000, 1600,000, 1700,000, 1800,000, 1900,000, 2100,000, 2200,000, 2300,000, 2400,000, 2500,000, 2600,000, 275,000, 300,000, 325,000, 350,000, 3600,000, 375,000, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 600 The SBR(s) preferably have an Mn of from about 300,000 to about 400,000 grams / mol or from 300,000 to 400,000 grams / mol (e.g., 300,000, 325,000, 350,000, 375,000, or 400,000 grams / mol). Because at least one SBR(i) is a functionalized polymer, it is understood that the foregoing Mw and Mn values ​​refer to the combined Mw and combined Mn, rather than the base polymer values.

[0030] Generally, styrene-butadiene rubbers having silica-reactive functional groups can be considered functionalized polymers or functionalized SBR. Non-limiting examples of silica-reactive functional groups generally include nitrogen-containing functional groups, silicon-containing functional groups, oxygen- or sulfur-containing functional groups, and metal-containing functional groups, as described in more detail below.

[0031] When at least one styrene-butadiene rubber having silica-reactive functional groups is prepared, functionalization can be achieved by adding functional groups to one or both ends of the polymer, by adding functional groups to the backbone of the polymer (or a combination of the foregoing), by attaching two or more polymer chains to a coupling agent, or a combination thereof. Such an effect can be achieved by treating the living polymer with a coupling agent, a functionalizing agent, or a combination thereof, which serves to attach and / or functionalize the other chains. In certain embodiments of the first through third embodiments, the at least one styrene-butadiene rubber having silica-reactive functional groups contains one or more functional groups but is not attached (i.e., does not contain a coupling agent). Generally, coupling agents and / or functionalizing agents can be used in various molar ratios. Alternatively, in certain embodiments of the first through third embodiments, the functionalized SBR (i) can be silica-reactive solely as a result of the use of a coupling agent. While reference is made herein to the use of both coupling agents and functionalizing groups (and the compounds used therefor), those skilled in the art will understand that certain compounds may perform both functions. That is, a particular compound can both bond polymer chains and provide polymer chains with functional groups. Those skilled in the art will also understand that the ability to bond polymer chains may depend on the amount of coupling agent reacted with the polymer chain. For example, advantageous bonding can be achieved when the coupling agent is added in a 1:1 ratio of the lithium equivalent of the initiator to the leaving group (e.g., halogen atom) equivalent of the coupling agent. Non-limiting examples of coupling agents include metal halides, metalloid halides, alkoxysilanes, alkoxystannanes, and combinations thereof.

[0032] Non-limiting examples of nitrogen-containing functional groups that may be utilized as the silica-reactive functional group in at least one SBR (i) in certain embodiments of the first through third embodiments include, but are not limited to, substituted or unsubstituted amino groups, amide residues, isocyanate groups, imidazolyl groups, indolyl groups, imino groups, nitrile groups, pyridyl groups, and ketimines. In certain preferred embodiments of the first through third embodiments, at least one SBR (i) has a silica-reactive functional group comprising an unsubstituted amino group, a substituted amino group, or a substituted imino group. The substituted or unsubstituted amino group should be understood to include amino groups derived from primary alkylamines, secondary alkylamines, or cyclic amines, and substituted or unsubstituted imines. In certain embodiments of the first through third embodiments, at least one SBR (i) of the elastomeric component comprises a silica-reactive functional group selected from the aforementioned list of nitrogen-containing functional groups.

[0033] In certain embodiments of the first to third embodiments, at least one SBR (i) comprises a silica-reactive functional group from a compound containing nitrogen in the form of an imino group. Such imino-containing functional groups connect the active end of the polymer chain to the following formula (I): [ka] wherein R, R', R'', and R''' are each independently selected from the group consisting of alkyl, aryl, and aryl groups having 1 to 18 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms), and m and n are integers from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) and 1 to 3 (1, 2, or 3), respectively. Each of R, R', R'', and R''' is preferably hydrocarbyl and does not contain heteroatoms. In certain embodiments of the first to third embodiments, each R and R' is independently selected from alkyl groups having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6 carbon atoms), preferably 1 to 3 carbon atoms (e.g., 1, 2, or 3 carbon atoms). In certain embodiments of the first to third embodiments, m is an integer from 2 to 6 (e.g., 2, 3, 4, 5, or 6), preferably 2 or 3. In certain embodiments of the first to third embodiments, R''' is selected from groups having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6 carbon atoms), preferably 2 to 4 carbon atoms (e.g., 2, 3, or 4 carbon atoms). In certain embodiments of the first to third embodiments, R'' is selected from alkyl groups having 1 to 6 carbon atoms (e.g., 1, 2, 3, 4, 5, or 6 carbon atoms), preferably 1 to 3 carbon atoms (e.g., 1, 2, or 3 carbon atoms), most preferably 1 carbon atom (e.g., methyl). In certain embodiments of the first through third embodiments, n is 3, resulting in compounds having trihydrocarboxysilane moieties, such as trialkoxysilane moieties.Non-limiting examples of compounds having an imino group and satisfying formula (I) above that are suitable for providing silica-reactive functional groups for SBR include, but are not limited to, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, and N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine.

[0034] Non-limiting examples of silicon-containing functional groups that may be utilized in certain embodiments of the first through third embodiments as the silica-reactive functional group in at least one SBR (i) include, but are not limited to, organosilyl or siloxy groups; more precisely, such functional groups may be selected from alkoxysilyl groups, alkylhalosilyl groups, siloxy groups, alkylaminosilyl groups, and alkoxyhalosilyl groups. Optionally, the organosilyl or siloxy group may also contain one or more nitrogen atoms. Suitable silicon-containing functional groups for use in functionalizing diene-based elastomers also include those disclosed in U.S. Pat. No. 6,369,167, the entire disclosure of which is incorporated herein by reference. In certain embodiments of the first through third embodiments, at least one SBR (i) comprises at least one silica-reactive functional group selected from the foregoing list of silicon-containing functional groups.

[0035] In certain embodiments of the first to third embodiments, at least one SBR (i) comprises a silica-reactive functional group comprising a silicon-containing functional group having a siloxy group (e.g., a hydrocarbyloxysilane-containing compound), which optionally comprises a monovalent group having at least one functional group. Such silicon-containing functional group provides an active end of the polymer chain with a group represented by the following formula (II): [ka] [In the formula, A 1 represents a monovalent group having at least one functional group selected from epoxy, isocyanate, imine, cyano, carboxylic acid ester, carboxylic acid anhydride, cyclic tertiary amine, non-cyclic tertiary amine, pyridine, silazane, and sulfide; R c represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms), and R d represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms), a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms (e.g., 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms), or a reactive group; R e represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms) or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms (e.g., 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms), b is an integer of 0 to 2, and two or more R d OR e When exists, each R d and / or OR e may be the same or different, and the active proton may be added by reacting with a compound having a moiety not contained within the molecule) and / or its partial condensation product. As used herein, a partial condensation product refers to a product in which some (but not all) of the SiOR groups in the hydrocarbyloxysilane compound have been condensed to SiOSi bonds. In certain embodiments of the first to third embodiments, the following may be present: (a) R crepresents a divalent hydrocarbon group having 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms), 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6 carbon atoms), or 2 to 3 carbon atoms (e.g., 2 or 3 carbon atoms); (b) R e represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms), 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6 carbon atoms), or 1 to 2 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 8 carbon atoms; (c) R d represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms), 2 to 6 carbon atoms (e.g., 2, 3, 4, 5, or 6 carbon atoms), or 1 to 2 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 8 carbon atoms; and in certain such embodiments, each of (a), (b), and (c) is satisfied; and R c , R e and R d is selected from one of the aforementioned groups.

[0036] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1has at least one epoxy group. Non-limiting examples of such compounds include 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, (2-glycidoxyethyl)methyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl)methyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane. Among these, 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are particularly suitable.

[0037] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1 has at least one isocyanate group. Non-limiting specific examples of such compounds include 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropylmethyldiethoxysilane, and 3-isocyanatepropyltriisopropoxysilane, with 3-isocyanatepropyltrimethoxysilane being particularly preferred.

[0038] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1has at least one imine group. Non-limiting specific examples of such compounds include N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine, N-(cyclohexylidene)-3-(triethoxysilyl)-1-propanamine, and trimethoxysilyl compounds, methyldiethoxysilyl compounds, and ethyldimethoxysilyl compounds corresponding to the above triethoxysilyl compounds. Among these, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine and N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine are particularly suitable. Preferred examples of the imine (amidine) group-containing compound include 1-[3-trimethoxysilyl]propyl]-4,5-dihydroimidazole, 3-(1-hexamethyleneimino)propyl(triethoxy)silane, (1-hexamethyleneimino)methyl(trimethoxy)silane, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, N-(3-isopropoxysilylpropyl)-4,5-dihydroimidazole, and N-(3-methyldiethoxysilylpropyl)-4,5-dihydroimidazole. Of these, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole and N-(3-isopropoxysilylpropyl)-4,5-dihydroimidazole are preferred.

[0039] In certain embodiments of the first to third embodiments, the functional groups of the SBR originate from a compound represented by formula (II), wherein A 1has at least one carboxylic acid ester group. Non-limiting specific examples of such compounds include 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropyltriisopropoxysilane, and among these, 3-methacryloyloxypropyltriethoxysilane is preferred.

[0040] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1 has at least one carboxylic acid anhydride group. Non-limiting examples of such compounds include 3-trimethoxysilylpropyl succinic anhydride, 3-triethoxysilylpropyl succinic anhydride, 3-methyldiethoxysilylpropyl succinic anhydride, etc., and among these, 3-triethoxysilylpropyl succinic anhydride is preferred.

[0041] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1 has at least one cyano group. Non-limiting examples of such compounds include 2-cyanoethylpropyltriethoxysilane.

[0042] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1has at least one cyclic tertiary amine group. Specific, non-limiting examples of such compounds include 3-(1-hexamethyleneimino)propyltriethoxysilane, 3-(1-hexamethyleneimino)propyltrimethoxysilane, (1-hexamethyleneimino)methyltriethoxysilane, (1-hexamethyleneimino)methyltrimethoxysilane, 2-(1-hexamethyleneimino)ethyltriethoxysilane, 3-(1-hexamethyleneimino)ethyltrimethoxysilane, 3-(1-pyrrolidinyl) ... Examples of suitable silanes include 3-(1-hexamethyleneimino)propyltrimethoxysilane, 3-(1-pyrrolidinyl)propyltriethoxysilane, 3-(1-heptamethyleneimino)propyltriethoxysilane, 3-(1-dodecamethyleneimino)propyltriethoxysilane, 3-(1-hexamethyleneimino)propyldiethoxymethylsilane, 3-(1-hexamethyleneimino)propyldiethoxyethylsilane, and 3-[10-(triethoxysilyl)decyl]-4-oxazoline. Among these, 3-(1-hexamethyleneimino)propyltriethoxysilane and (1-hexamethyleneimino)methyltriethoxysilane are preferred.

[0043] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1 has at least one acyclic tertiary amine group. Non-limiting specific examples of such compounds include 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyldiethoxymethylsilane, and 3-dibutylaminopropyltriethoxysilane, and among these, 3-dimethylaminopropyltriethoxysilane and 3-diethylaminopropyltriethoxysilane are suitable.

[0044] In certain embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound represented by formula (II), wherein A 1 has at least one pyridine group. Non-limiting examples of such compounds include 2-trimethoxysilylethylpyridine.

[0045] In certain preferred embodiments of the first to third embodiments, the silica-reactive functional group of at least one SBR (i) is derived from a compound of formula (II), wherein A 1 has at least one silazane group. Non-limiting examples of such compounds include N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane, and N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane. N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, or 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane is particularly preferred.

[0046] Silica-reactive functional groups according to formula (II) are used, where A 1In those embodiments of the first through third embodiments in which A contains one or more protected nitrogens (as discussed in detail above), the nitrogens can be deprotected or deblocked by hydrolysis or other procedures to convert the protected nitrogens to primary nitrogens. As a non-limiting example, a nitrogen bonded to two trimethylsilyl groups can be deprotected and converted to a primary amine nitrogen (such nitrogen still bonded to the remainder of the compound of formula (II)). Thus, at least one silica-reactive functional group of SBR(i) can be selected from the group consisting of A, ... 1 In certain embodiments of the first through third embodiments, where X results from the use of a compound according to Formula (II) containing one or more protected nitrogens, the functionalized polymer may be understood as containing functional groups resulting from the deprotected (or hydrolyzed) version of the compound.

[0047] Non-limiting examples of oxygen- or sulfur-containing functional groups that may be utilized as the silica-reactive functional group in at least one SBR (i) in certain embodiments of the first through third embodiments include, but are not limited to, hydroxyl, carboxyl, epoxy, glycidoxy, diglycidylamino, cyclic dithiane-derived functional groups, ester, aldehyde, alkoxy, ketone, thiocarboxyl, thioepoxy, thioglycidoxy, thiodiglycidylamino, thioester, thioaldehyde, thioalkoxy, and thioketone groups. In certain embodiments of the first through third embodiments, the alkoxy groups may be benzophenone-derived alcohol-derived alkoxy groups. In certain embodiments of the first through third embodiments, at least one SBR (i) comprises at least one silica-reactive functional group selected from the list of oxygen- or sulfur-containing functional groups described above.

[0048] According to the first to third embodiments, the at least one SBR (i) having silica-reactive functional groups can be prepared by either solution polymerization or emulsion polymerization. In certain preferred embodiments of the first to third embodiments, the only SBR having silica-reactive functional groups is prepared by solution polymerization. In other embodiments of the first to third embodiments, the only SBR having silica-reactive functional groups is prepared by emulsion polymerization. In certain embodiments of the first to third embodiments, when two or more SBRs having silica-reactive functional groups are used, the rubber is a combination of solution-polymerized SBR and emulsion-polymerized SBR (e.g., one solution SBR and one emulsion SBR). In certain embodiments of the first to third embodiments, the only SBR present in the elastomer component (including at least one SBR having silica-reactive functional groups) is solution SBR (i.e., no emulsion SBR).

[0049] Non-functionalized styrene-butadiene rubber As discussed above, according to the first to third embodiments disclosed herein, the elastomer component of the tire tread rubber composition comprises (includes) 25 to 49 parts (e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, or 49 parts) of at least one non-functionalized styrene-butadiene rubber having a Tg of about −30 to about −15° C. or −30 to −15° C. (e.g., −30, −29, −28, −27, −26, −25, −24, −23, −22, −21, −20, −19, −18, −17, −16, or −15° C.). In preferred embodiments of the first through third embodiments, the unfunctionalized SBR (ii) has a Tg of about −25 to about −15° C. or −25 to −15° C. (e.g., −25, −24, −23, −22, −21, −20, −19, −18, −17, −16, or −15° C.). In certain preferred embodiments of the first through third embodiments, the at least one SBR (ii) having a Tg as discussed above is present in an amount of 35 to 45 parts (e.g., 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45 parts).

[0050] In certain embodiments of the first through third embodiments, the elastomeric component comprises (only) one SBR(ii) that is unfunctionalized and has a Tg as discussed above. In other embodiments of the first through third embodiments, the elastomeric component comprises two SBR(ii) that are both unfunctionalized and independently have Tg as discussed above. In certain embodiments of the first through third embodiments disclosed herein, at least one SBR(ii) comprises an SBR extended with a low molecular weight SBR (as described below). In certain embodiments of the first through third embodiments, at least one SBR(ii) comprises an SBR that is not extended with any type of liquid plasticizer (e.g., oil). In certain embodiments of the first through third embodiments, at least one SBR(ii) comprises a combination of an SBR extended with a low molecular weight SBR and an SBR that is not extended with any type of liquid plasticizer or oil.

[0051] In certain embodiments of the first through third embodiments disclosed herein, at least one SBR (ii) has a molecular weight of about 400,000 to about 700,000 grams / mol or 400,000 to 700,000 grams / mol (e.g., 400,000, 425,000, 450,000, 475,000, 500,000, 525,000, 550,000, 575,000, 600,000, 625,000, 650,000, 675,000, or 700,000 grams / mol) according to polystyrene standards (and may be determined by GPC). ), preferably about 300,000 to about 500,000 or 300,000 to 500,000 grams / mol (e.g., 300,000, 325,000, 350,000, 375,000, 400,000, 425,000, 450,000, 475,000, or 500,000 grams / mol), more preferably about 350,000 to about 450,000 or 350,000 to 450,000 grams / mol (e.g., 350,000, 375,000, 400,000, 425,000, or 450,000 grams / mol). In certain embodiments of the first through third embodiments disclosed herein, at least one SBR(i) has a molecular weight of about 250,000 to about 450,000 grams / mole or 250,000 to 450,000 grams / mole (e.g., 250,000, 275,000, 300,000, 325,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1000,000, 1100,000, 1200,000, 1300,000, 1400,000, 1500,000, 1600,000, 1700,000, 1800,000, 1900,000, 2100,000, 2200,000, 2300,000, 2400,000, 2500,000, 2600,000, 275,000, 300,000, 325,000, 350,000, 3600,000, 375,000, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 600 350,000, 375,000, 400,000, 425,000, or 450,000 grams / mol), preferably about 300,000 to about 400,000 grams / mol or 300,000 to 400,000 grams / mol (e.g., 300,000, 325,000, 350,000, 375,000, or 400,000 grams / mol).When at least one SBR (ii) comprises an SBR extended with a low molecular weight (SBR), as discussed below, it may be preferable to use an SBR for (ii) having a Mw in the upper ranges disclosed above, e.g., 500,000 to 700,000 g / mole, preferably 550,000 to 700,000 g / mole, or 600,000 to 700,000 g / mole, understanding that the use of a lower Mw SBR for the low molecular weight SBR can lower the average Mw and / or Mn in the extended version of SBR (ii).

[0052] According to the first to third embodiments disclosed herein, the styrene content of the at least one SBR (ii) may vary. In certain preferred embodiments of the first to third embodiments, the at least one SBR (ii) has a styrene content of 30 to 50% (e.g., 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, or 50%), more preferably 35 to 45% (e.g., 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45%). According to the first to third embodiments disclosed herein, the vinyl bond content of the at least one SBR (ii) may vary. In certain preferred embodiments of the first to third embodiments, at least one SBR (ii) has a vinyl bond content of 15 to 35% (e.g., 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, or 35%), more preferably 20 to 30% (e.g., 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30%). The vinyl bond content referred to herein should be understood to refer to the total vinyl bond content in the SBR polymer chain, not the vinyl bond content in the butadiene portion of the SBR polymer chain, and H 1 -NMR and C 13The styrene content can be measured by NMR (e.g., using a 300 MHz Gemini 300 NMR spectrometer system (Varian)). The styrene content disclosed herein can be determined using similar methods and the same instruments. In certain embodiments of the first to third embodiments, at least one SBR (ii) has a vinyl bond content and a styrene content within one of the aforementioned ranges, optionally in combination with one or more of the Mw, Mn, and / or Mw / Mn ranges discussed above.

[0053] According to the first to third embodiments, the at least one SBR (i) having silica-reactive functional groups can be prepared by either solution polymerization or emulsion polymerization. In certain preferred embodiments of the first to third embodiments, the only SBR having silica-reactive functional groups is prepared by solution polymerization. In other embodiments of the first to third embodiments, the only SBR having silica-reactive functional groups is prepared by emulsion polymerization. In certain embodiments of the first to third embodiments, when two or more SBRs having silica-reactive functional groups are used, the rubber is a combination of solution-polymerized SBR and emulsion-polymerized SBR (e.g., one solution SBR and one emulsion SBR). In certain preferred embodiments of the first to third embodiments, the only SBR present in the elastomer component (comprising at least one SBR (i) having silica-reactive functional groups and at least one unfunctionalized SBR (ii)) is solution SBR (i.e., no emulsion SBR).

[0054] Low molecular weight styrene-butadiene rubber As discussed above, according to the first to third embodiments disclosed herein, the elastomer component of the tire tread rubber composition includes a low molecular weight styrene-butadiene rubber. The term "low molecular weight" SBR means that the SBR generally has a lower molecular weight (Mw) than SBRs (i) and (ii). Because low molecular weight SBRs are generally liquid at room temperature, they should be considered to constitute a liquid plasticizer rather than being included in the "elastomer component" discussed above. According to the first to third embodiments, the Tg of the low molecular weight SBR can vary, but in certain preferred embodiments, the Tg is about −30 to about −10° C. or −30 to −10° C. (e.g., −30, −28, −26, −25, −24, −22, −20, −18, −16, −15, −14, −12, or −10° C.), and even more preferably about −20 to about −10° C. or −20 to −10° C. (e.g., −20, −19, −18, −17, −16, −15, −14, −13, −12, −11, or −10° C.). According to the first through third embodiments, the Mw of the low molecular weight SBR can vary, but in certain preferred embodiments, the Mw is less than 200,000 grams / mole (e.g., 200,000, 190,000, 180,000, 170,000, 160,000, 150,000, 140,000, 130,000, 120,000, 110,000, 100,000, 90,000, 80,000, 70,000, 60,000, 50,000, 40,000 grams / mole or less), or between 200,000 and 40,000 grams / mole. In certain of the first through third embodiments, the Mw of the low molecular weight SBR is from 150,000 to 40,000 grams / mole (e.g., 150,000, 140,000, 130,000, 120,000, 110,000, 100,000, 90,000, 80,000, 70,000, 60,000, 50,000, or 40,000 grams / mole), or from 120,000 to 50,000 grams / mole (e.g., 120,000, 110,000, 100,000, 90,000, 80,000, 70,000, 60,000, or 50,000 grams / mole).In certain of the first through third embodiments, the Mw / Mn of the low molecular weight SBR is less than 1.2 (e.g., 1.2, 1.15, 1.1, 1.05, 1.0, 0.95, 0.90, 0.85, 0.80, etc.), preferably less than 1.1 (e.g., 1.1, 1.05, 1.0, 0.95, 0.90, 0.85, 0.80, etc.), and in certain such embodiments, the Mw / Mn can be less than 1.2 to 0.9 (e.g., 1.2, 1.15, 1.1, 1.05, 1.0, 0.95, or 0.90), or less than 1.1 to 0.9 (e.g., 1.1, 1.05, 1.0, 0.95, or 0.90).

[0055] According to the first to third embodiments, the low molecular weight SBR may be added to the tire tread rubber composition as a free liquid plasticizer, as an extension plasticizer for one of SBR(i) or (ii), or another rubber, or as a combination of both. In preferred embodiments of the first to third embodiments, the low molecular weight SBR is used to extend one of SBR(i) or (ii), more preferably SBR(ii). In certain embodiments of the first to third embodiments, the low molecular weight SBR is used to extend a portion of SBR(ii). In other words, in such embodiments, a portion of SBR(ii) is extended with the low molecular weight SBR, and the remaining portion of SBR(ii) is not extended with any low molecular weight SBR. In certain such embodiments, about 40 to about 70 weight percent or 40-70 weight percent (e.g., 40, 45, 50, 55, 60, 65, or 70 weight percent) of the SBR(ii) is extended with low molecular weight SBR, and preferably about 50 to about 65 weight percent or 50-65 weight percent (e.g., 50, 52, 54, 55, 56, 58, 60, 62, 64, or 65 weight percent) of the SBR(ii) is extended with low molecular weight SBR.

[0056] According to the first through third embodiments, the amount of low molecular weight SBR used to extend SBR(i) and / or SBR(ii), preferably SBR(ii), can vary. In certain embodiments of the first through third embodiments, the amount of low molecular weight SBR present in SBR(i) or SBR(ii), preferably SBR(ii), is from 10 to 50 parts low molecular weight SBR per 100 parts rubber (e.g., 10, 15, 20, 25, 30, 35, 40, 45, or 50 parts low molecular weight SBR per 100 parts rubber), preferably from 10 to 40 parts low molecular weight SBR (e.g., 10, 15, 20, 25, 30, 35, 40, 45, or 50 parts low molecular weight SBR per 100 parts rubber), or from 20 to 40 parts (e.g., 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, or 40 parts) low molecular weight SBR per 100 parts rubber.

[0057] According to the first to third embodiments, the low molecular weight SBR can be prepared by either solution polymerization or emulsion polymerization. In preferred embodiments of the first to third embodiments, the only low molecular weight SBR is prepared by solution polymerization. In other embodiments of the first to third embodiments, the only low molecular weight SBR is prepared by emulsion polymerization. In certain embodiments of the first to third embodiments, only one low molecular weight SBR is used, and in other embodiments, two or more (e.g., two or three) low molecular weight SBRs are used. Preferably, according to the first to third embodiments, only one low molecular weight SBR is used. In certain embodiments of the first to third embodiments, when two or more low molecular weight SBRs are used, the rubber is a combination of solution-polymerized SBR and emulsion-polymerized SBR (e.g., one solution SBR and one emulsion SBR). In certain preferred embodiments of the first to third embodiments, the only low molecular weight SBR present in the tire tread rubber composition is solution SBR (i.e., no emulsion SBR is present).

[0058] Other (additional) rubber In certain of the first through third embodiments, the elastomeric component of the tire tread rubber composition includes at least one additional rubber. In certain such embodiments, only one additional rubber is present, and in other embodiments, two (or more) additional rubbers are present. In those embodiments of the first through third embodiments, when at least one additional rubber is present, the rubber is preferably selected from conjugated diene monomer-containing polymers and copolymers. In certain preferred embodiments of the first through third embodiments, SBRs (i) and (ii) are present in a total amount of at least 90% by weight (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more) of the elastomeric component, preferably at least 95% by weight (e.g., 95%, 96%, 97%, 98%, 99% or more) of the elastomeric component, or 100% by weight of the elastomeric component. It is understood that when SBRs (i) and (ii) are present in one of the aforementioned amounts (e.g., at least 90 wt%), the additional rubber is present in a corresponding total amount (e.g., 90 parts SBR(i)+(ii) and 10 parts additional rubber) to make up 100 parts of the total elastomeric component. In those embodiments of the first through third embodiments in which at least one additional rubber is present, the at least one additional rubber comprises at least one of additional SBR (i.e., other than SBR(i) and SBR(ii) and low molecular weight SBR), natural rubber, polyisoprene, or polybutadiene (preferably a polybutadiene having a cis-bond content of at least 90%, more preferably at least 92%), preferably natural rubber, or a polybutadiene having a cis-bond content of at least 90% (preferably at least 92%). In certain embodiments, the additional rubber is selected from the group consisting of styrene-isoprene rubber, butadiene-isoprene-rubber, styrene-isoprene-butadiene rubber, butyl rubber (both halogenated and non-halogenated), ethylene-propylene rubber (EPR), ethylene-butylene rubber (EBR), ethylene-propylene-diene rubber (EPDM), and combinations thereof.

[0059] Filler components As discussed above, according to first through third embodiments, the tire tread rubber composition comprises at least one reinforcing silica filler and 10 phr or less of a carbon black filler. Collectively, these fillers may be considered to constitute the "filler component" of the tire tread rubber composition. According to first through third embodiments, the filler component comprises at least one reinforcing silica filler in an amount of 60 to 90 phr (e.g., 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 78, 80, 82, 84, 85, 86, 88, or 90 phr), and 10 phr or less of carbon black (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0 phr). As discussed further below, the at least one reinforcing silica filler is preferably present in an amount of from about 200 to about 350 m 2 / g BET surface area. In certain preferred embodiments of the first through third embodiments, the filler component consists of at least one reinforcing silica filler in an amount of 60-90 phr and 10 phr or less of carbon black (only). In other embodiments of the first through third embodiments, the filler component includes at least one reinforcing silica filler in an amount of 60-90 phr and 10 phr or less of carbon black (preferably reinforcing carbon black), as discussed above, but may also include other additional fillers. Such additional fillers may be present in amounts up to 200 m 2 Silica filler with a BET surface area of ​​less than 360 m 2The filler may be selected from silica fillers having a BET surface area greater than 1 / g, non-reinforcing carbon black, or other fillers suitable for use in tire tread rubber compositions. In those embodiments of the first through third embodiments in which one or more additional fillers are present in the filler component, the amount of such filler is preferably 20% by weight or less (e.g., 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or less) of the total filler component, more preferably 10% by weight or less (e.g., 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or less) of the total filler component, and even more preferably 5% by weight or less (e.g., 5%, 4%, 3%, 2%, 1% or less) of the total filler component.

[0060] Reinforcing Silica Filler As described above, according to the first to third embodiments disclosed herein, the tire tread rubber composition contains at least one reinforcing silica filler in an amount of 60 to 90 phr (e.g., 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 78, 80, 82, 84, 85, 86, 88, or 90 phr). The at least one silica filler used in (b) is preferably about 200 to about 350 m 2 / g, 200-350m 2 / g (e.g., 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, or 350 m 2 / g), more preferably about 250 to about 320 m 2 / g or 250-320m 2 / g (e.g., 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, or 350 m 2 / g). In embodiments of the first through third embodiments disclosed herein, the only silica filler present in the tire tread rubber composition has a BET surface area within one of the aforementioned ranges. In certain preferred embodiments of the first through third embodiments, the amount of the at least one silica filler (b) is 65 to 85 phr (e.g., 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, or 75 phr), preferably 70 to 80 phr (e.g., 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, or 80 phr).

[0061] According to the first through third embodiments disclosed herein, one or more reinforcing silica fillers may be used in (b). In preferred embodiments of the first through third embodiments, one silica filler, preferably having a BET surface area as discussed herein, is used in (b). In other embodiments of the first through third embodiments, two (or more) silica fillers, preferably having a BET surface area as discussed herein, are used in (b).

[0062] According to the first through third embodiments, the specific type of silica for the at least one reinforcing silica filler can vary. Non-limiting examples of reinforcing silica fillers suitable for use in certain embodiments of the first through third embodiments include, but are not limited to, precipitated amorphous silica, wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), fumed silica, calcium silicate, and the like. Other reinforcing silica fillers suitable for use in certain embodiments of the first through third embodiments include, but are not limited to, aluminum silicate, magnesium silicate (Mg2SiO4, MgSiO3, etc.), magnesium calcium silicate (CaMgSiO4), calcium silicate (Ca2SiO4, etc.), aluminum silicate (Al2SiO5, Al4.3SiO4.5H2O, etc.), aluminum calcium silicate (Al2O3.CaO2SiO2, etc.), and the like. Of the reinforcing silica fillers listed, precipitated amorphous wet-process, hydrous silica fillers are preferred. Such reinforcing silica fillers are produced by a chemical reaction in water, from which they are precipitated as ultrafine spherical particles with primary particles that are strongly bound into aggregates, which in turn are less strongly bound into agglomerates. Surface area, as determined by the BET method, is the preferred measure for characterizing the reinforcing properties of various reinforcing silica fillers. In certain embodiments of the first to third embodiments disclosed herein, the rubber composition comprises a reinforcing silica filler having a pH of about 5.5 to about 8, 5.5 to 8 (e.g., 5.5, 5.7, 5.9, 6.1, 6.3, 6.5, 6.7, 6.9, 7.1, 7.3, 7.5, 7.7, 7.9, or 8), about 6 to about 8, 6 to 8 (e.g., 6, 6.2, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.6, 7.8, or 8), about 6 to about 7.5, 6 to 7.5, about 6.5 to about 8, 6.5 to 8, about 6.5 to about 7.5, 6.5 to 7.5, about 5.5 to about 6.8, or 5.5 to 6.8.Some commercially available reinforcing silica fillers that can be used in certain embodiments of the first through third embodiments include Hi-Sil® EZ 120G, Hi-Sil® EZ 120G-D, Hi-Sil® 134G, Hi-Sil® EZ 160G, Hi-Sil® EZ 160G-D, Hi-Sil® 190, Hi-Sil® 190G-D, Hi-Sil® EZ 200G, and Hi-Sil® EZ 190G-D, manufactured by PPG Industries (Pittsburgh, Pa.). 200G-D, Hi-Sil® 210, Hi-Sil® 233, Hi-Sil® 243LD, Hi-Sil® 255CG-D, Hi-Sil® 315-D, Hi-Sil® 315G-D, Hi-Sil® HDP 320G, and the like. Similarly, many useful commercial grades of different reinforcing silica fillers are also available from Evonik Corporation (e.g., Ultrasil® 320 GR, Ultrasil® 5000 GR, Ultrasil® 5500 GR, Ultrasil® 7000 GR, Ultrasil® VN2 GR, Ultrasil® VN2, Ultrasil® VN3, Ultrasil® VN3 GR, Ultrasil® 7000 GR, Ultrasil® 7005, Ultrasil® 7500 GR, Ultrasil® 7800 GR, Ultrasil® 9500 GR, Ultrasil® 9000 GR, Ultrasil® 9100 GR, Ultrasil® 9200 GR, Ultrasil® 9300 GR, Ultrasil® 9400 GR, Ultrasil® 9500 GR, Ultrasil® 9600 GR, Ultrasil® 9700 GR, Ultrasil® 9800 GR, Ultrasil® 9900 GR, Ultrasil® 1000 GR, Ultrasil® 10100 GR, Ultrasil® 10200 GR, Ultrasil® 10300 GR, Ultrasil® 10400 GR, Ultrasil® 10500 GR, Ultrasil® 10600 GR, Ultrasil® 10700 GR, Ultrasil® 10800 GR, Ultrasil® 10900 GR, Ultrasil® 1100 GR, Ultrasil® 11600 GR, Ultrasil® 11700 GR, Ultrasil® 11800 GR, Ultrasil® 119 ... GR) and Solvay (e.g., Zeosil® 1115MP, Zeosil® 1085GR, Zeosil® 1165MP, Zeosil® 1200MP, Zeosil® Premium, Zeosil® 195HR, Zeosil® 195GR, Zeosil® 185GR, Zeosil® 175GR, and Zeosil® 165 GR).

[0063] Silica Coupling Agent In certain embodiments of the first through third embodiments disclosed herein, one or more silica coupling agents may also (optionally) be utilized. In preferred embodiments of the first through third embodiments, at least one silica coupling agent is utilized. Silica coupling agents are useful for preventing or reducing agglomeration of silica filler particles in rubber compositions. Agglomeration of silica filler particles is believed to increase the viscosity of a rubber composition; therefore, preventing this agglomeration reduces the viscosity, improving the processability and blending of the rubber composition.

[0064] Generally, any conventional silica coupling agent type can be used, such as those having moieties capable of reacting with silanes and components or polymers, particularly vulcanizable polymers. The silica coupling agent acts as a connecting bridge between the silica and the polymer. Suitable silica coupling agents for use in certain embodiments of the first through third embodiments disclosed herein include those containing groups such as alkylalkoxy, mercapto, blocked mercapto, sulfide-containing (e.g., monosulfide-based alkoxy-containing, disulfide-based alkoxy-containing, tetrasulfide-based alkoxy-containing), amino, vinyl, epoxy, and combinations thereof. In preferred embodiments of the first through third embodiments, the tire tread rubber composition includes a mercapto-type silica coupling agent, most preferably as the only type of silica coupling agent. In certain embodiments of the first through third embodiments, the silica coupling agent can be added to the rubber composition in the form of pretreated silica. The pretreated silica is surface-treated with a silane before being added to the rubber composition. The use of pretreated silica allows for the addition of two components in one (i.e., silica and silica coupling agent), which generally tends to make rubber compounding easier.

[0065] Alkylalkoxysilanes have the general formula R 10 p Si(OR 11 )4-p and each R 11 are independently monovalent organic groups, p is an integer of 1 to 3, and at least one R 10 is an alkyl group. Preferably, p is 1. Generally, each R 10 are C1 to C independently. 20 Aliphatic, C5-C 20 Cycloaliphatic or C6-C 20 Each R 11 independently comprises a C1-C6 aliphatic. In certain exemplary embodiments, each R 10 independently C6 to C 15 In further embodiments, each R 10 independently C8~C 14 Mercaptosilanes include aliphatic mercaptosilanes of the general formula HS-R 13 -Si(R 14 )(R 15 )2, and R 13 is a divalent organic group, and R 14 is a halogen atom or an alkoxy group, and each R 15 are independently a halogen, an alkoxy group, or a monovalent organic group. The halogen is chlorine, bromine, fluorine, or iodine. The alkoxy group preferably has 1 to 3 carbon atoms. Blocked mercaptosilanes have the general formula BSR 16 -Si-X3, where the silyl group is available to react with silica in a silica-silane reaction, and the blocking group B replaces the mercapto hydrogen atom to block the reaction of the sulfur atom with the polymer. In the above general formula, B is a blocking group that can be in the form of an unsaturated heteroatom or a carbon directly attached to the sulfur through a single bond. R 16 is a C1 to C6 straight or branched chain alkylidene, and each X is independently selected from the group consisting of C1 to C4 alkyl or C1 to C4 alkoxy.

[0066] Non-limiting examples of alkylalkoxysilanes suitable for use in certain embodiments of the first through third embodiments include, but are not limited to, octyltriethoxysilane, octyltrimethoxysilane, trimethylethoxysilane, cyclohexyltriethoxysilane, isobutyltriethoxy-silane, ethyltrimethoxysilane, cyclohexyl-tributoxysilane, dimethyldiethoxysilane, methyltriethoxysilane, propyltriethoxysilane, hexyltriethoxysilane, heptyltriethoxysilane, nonyltriethoxysilane, Included are decyltriethoxysilane, dodecyltriethoxysilane, tetradecyltriethoxysilane, octadecyltriethoxysilane, methyloctyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, heptyltrimethoxysilane, nonyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, octadecyltrimethoxysilane, methyloctyldimethoxysilane, and mixtures thereof.

[0067] Non-limiting examples of bis(trialkoxysilylorgano) polysulfides suitable for use in certain embodiments of the first through third embodiments include bis(trialkoxysilylorgano) disulfides and bis(trialkoxysilylorgano) tetrasulfides. Specific non-limiting examples of bis(trialkoxysilylorgano) disulfides include, but are not limited to, 3,3'-bis(triethoxysilylpropyl) disulfide, 3,3'-bis(trimethoxysilylpropyl) disulfide, 3,3'-bis(tributoxysilylpropyl) disulfide, 3,3'-bis(tri-t-butoxysilylpropyl) disulfide, 3,3'-bis(trihexoxysilylpropyl) disulfide, 2,2'-bis(dimethyl ... 3,3'-bis(dimethoxysilylethyl) disulfide, 3,3'-bis(diphenylcyclohexoxysilylpropyl) disulfide, 3,3'-bis(ethyl-di-sec-butoxysilylpropyl) disulfide, 3,3'-bis(propyldiethoxysilylpropyl) disulfide, 12,12'-bis(triisopropoxysilylpropyl) disulfide, 3,3'-bis(dimethoxyphenylsilyl-2-methylpropyl) disulfide, and mixtures thereof. Non-limiting examples of bis(trialkoxysilylorgano)tetrasulfide silica coupling agents suitable for use in certain embodiments of the first through third embodiments include, but are not limited to, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropyl-benzothiazoletetrasulfide, 3-triethoxysilylpropylbenzothiazoletetrasulfide, and mixtures thereof. Bis(3-triethoxysilylpropyl)tetrasulfide is commercially available as Si69® from Evonik Degussa Corporation.

[0068] Non-limiting examples of mercaptosilanes suitable for use in certain embodiments of the first through third embodiments disclosed herein include, but are not limited to, 1-mercaptomethyltriethoxysilane, 2-mercaptoethyltriethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 2-mercaptoethyltripropoxysilane, 18-mercaptooctadecyldiethoxychlorosilane, and mixtures thereof.

[0069] Non-limiting examples of blocked mercaptosilanes suitable for use in certain embodiments of the first through third embodiments disclosed herein include, but are not limited to, those described in U.S. Pat. Nos. 6,127,468, 6,204,339, 6,528,673, 6,635,700, 6,649,684, and 6,683,135, the disclosures of which are incorporated herein by reference. Representative examples of blocked mercaptosilanes include 2-triethoxysilyl-1-ethylthioacetate, 2-trimethoxysilyl-1-ethylthioacetate, 2-(methyldimethoxysilyl)-1-ethylthioacetate, 3-trimethoxysilyl-1-propylthioacetate, triethoxysilylmethyl-thioacetate, trimethoxysilylmethylthioacetate, triisopropoxysilylmethylthioacetate, methyldiethoxysilylmethylthioacetate, methyldimethoxysilylmethylthioacetate, methyldiisopropoxysilylmethylthioacetate, dimethylethoxysilylmethylthioacetate, dimethylmethoxysilylmethylthioacetate, dimethylisopropoxysilylmethylthioacetate, 2-triisopropoxysilyl-1-ethylthioacetate, 2-(methyldiethoxysilyl)-1-ethylthioacetate, 2-( 2-(dimethylethoxysilyl-1-ethylthioacetate, 2-(dimethylmethoxysilyl)-1-ethylthioacetate, 2-(dimethylisopropoxysilyl)-1-ethylthioacetate, 3-triethoxysilyl-1-propylthioacetate, 3-triisopropoxysilyl-1-propylthioacetate, 3-methyldiethoxysilyl-1-propyl-thioacetate thioacetate, 3-methyldimethoxysilyl-1-propylthioacetate, 3-methyldiisopropoxysilyl-1-propylthioacetate, 1-(2-triethoxysilyl-1-ethyl)-4-thioacetylcyclohexane, 1-(2-triethoxysilyl-1-ethyl)-3-thioacetylcyclohexane, 2-triethoxysilyl-5-thioacetylnorbornene, 2-triethoxysilyl-4-thioacetylnorbornene,2-(2-triethoxysilyl-1-ethyl)-5-thioacetylnorbornene, 2-(2-triethoxy-silyl-1-ethyl)-4-thioacetylnorbornene, 1-(1-oxo-2-thia-5-triethoxysilylphenyl)benzoic acid, 6-triethoxysilyl-1-hexylthioacetate, 1-triethoxysilyl-5-hexylthioacetate, 8-triethoxysilyl-1-octylthioacetate, 1-triethoxysilyl-7-octylthioacetate, 6-triethoxysilyl-1-hexylthioacetate, 1- Triethoxysilyl-5-octylthioacetate, 8-trimethoxysilyl-1-octylthioacetate, 1-trimethoxysilyl-7-octylthioacetate, 10-triethoxysilyl-1-decylthioacetate, 1-triethoxysilyl-9-decylthioacetate, 1-triethoxysilyl-2-butylthioacetate, 1-triethoxysilyl-3-butylthioacetate, 1-triethoxysilyl-3-methyl-2-butylthioacetate, 1-triethoxysilyl-3-methyl-3-butylthioacetate, 3- Trimethoxysilyl-1-propylthiooctanoate, 3-triethoxysilyl-1-propyl-1-propylthiopalmitate, 3-triethoxysilyl-1-propylthiooctanoate, 3-triethoxysilyl-1-propylthiobenzoate, 3-triethoxysilyl-1-propylthio-2-ethylhexanoate, 3-methyldiacetoxysilyl-1-propylthioacetate, 3-triacetoxysilyl-1-propylthioacetate, 2-methyldiacetoxysilyl-1-ethylthioacetate, 2-triacetoxysilyl silyl-1-ethylthioacetate, 1-methyldiacetoxysilyl-1-ethylthioacetate, 1-triacetoxysilyl-1-ethyl-thioacetate, tris-(3-triethoxysilyl-1-propyl)trithiophosphate, bis-(3-triethoxysilyl-1-propyl)methyldithiophosphonate, bis-(3-triethoxysilyl-1-propyl)ethyldithiophosphonate, 3-triethoxysilyl-1-propyldimethylthiophosphinate, 3-triethoxysilyl-1-propyldiethylthiophosphinate,Tris-(3-triethoxysilyl-1-propyl)tetrathiophosphate, bis-(3-triethoxysilyl-1-propyl)methyl trithiophosphonate, bis-(3-triethoxysilyl-1-propyl)ethyl trithiophosphonate, 3-triethoxysilyl-1-propyldimethyldithiophosphinate, 3-triethoxysilyl-1-propyldiethyldithiophosphinate, tris-(3-methyldimethoxysilyl-1-propyl)trithiophosphate, bis-(3-methyldimethoxysilyl-1-propyl)-methyldithiophosphonate, bis-(3-methyldimethoxysilyl-1-propyl)-ethyldithiophosphonate, 3-methyldimethoxysilyl-1-propyldimethylthiophosphinate, 3-methyldimethoxysilyl-1-propyldiethylthiophosphinate, 3-triethoxysilyl-1-propylmethylthios Examples of blocked mercaptosilanes include, but are not limited to, 3-triethoxysilyl-1-propyl methanethiosulfonate, 3-triethoxysilyl-1-propyl ethanethiosulfonate, 3-triethoxysilyl-1-propyl benzenethiosulfonate, 3-triethoxysilyl-1-propyl toluenethiosulfonate, 3-triethoxysilyl-1-propyl naphthalenethiosulfonate, 3-triethoxysilyl-1-propyl xylenethiosulfonate, triethoxysilylmethyl methylthiosulfate, triethoxysilylmethyl methanethiosulfonate, triethoxysilylmethyl ethanethiosulfonate, triethoxysilylmethyl benzenethiosulfonate, triethoxysilylmethyl toluenethiosulfonate, triethoxysilylmethyl naphthalenethiosulfonate, triethoxysilylmethyl xylenethiosulfonate, etc. Mixtures of various blocked mercaptosilanes can be used. A further example of a blocked mercaptosilane suitable for use in certain exemplary embodiments is NXT™ silane (3-octanoylthio-1-propyltriethoxysilane), available from Momentive Performance Materials Inc. (Albany, NY).

[0070] Non-limiting examples of pretreated silicas (i.e., silicas pre-surface treated with silanes) suitable for use in certain embodiments of the first through third embodiments disclosed herein include, but are not limited to, mercaptosilane-pretreated Ciptane® 255 LD and Ciptane® LP (PPG Industries) silicas, and Coupsil® 8113 (Degussa), which is the product of the reaction between organosilane bis(triethoxysilylpropyl) polysulfide (Si69) and Ultrasil® VN3 silica. Coupsil 6508, Agilon 400™ silica (PPG Industries), Agilon 454® silica (PPG Industries), and 458® silica (PPG Industries). In embodiments in which the silica comprises pretreated silica, the pretreated silica is used in the amounts previously disclosed for silica fillers (i.e., 81 to 120 phr or about 90 to about 120 phr, etc.).

[0071] When a silica coupling agent is utilized in the first through third embodiments, the amount used can vary. In certain embodiments of the first through third embodiments, the rubber composition does not contain any silica coupling agent. In other preferred embodiments of the first through third embodiments, the silica coupling agent is present in an amount sufficient to provide a ratio of total silica coupling agent to silica filler of about 0.1:100 to about 1:5 (i.e., about 0.1 to about 20 parts by weight per 100 parts of silica), for example, 0.1:100 to 1:5, about 1:100 to about 1:10, 1:100 to 1:10, about 1:100 to about 1:20, 1:100 to 1:20, about 1:100 to about 1:25, and 1:100 to 1:25, and about 1:100 to about 0:100, and 1:100 to 0:100. In a preferred embodiment of the first to third embodiments, the ratio of the total amount of silica coupling agent to the silica filler falls within a ratio of 1:10 to 1:20 (ie, 10 to 5 parts by weight per 100 parts of silica).In certain embodiments according to the first to third embodiments, the rubber composition comprises about 0.1 to about 15 phr of a silica coupling agent, for example, 0.1 to 15 phr (e.g., 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 phr), about 0.1 to about 12 phr, 0.1 to 12 phr, about 0.1 to about 10 phr, 0.1 to 10 phr, about 0.1 to about 7 phr, 0.1 to 7 phr, about 0.1 to about 5 phr, 0.1 to 5 phr, about 0.1 to about 3 phr, 0.1 to 3 phr, about 1 to about 15 phr, 1 to 15 phr (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 phr), about 1 to about 12 phr, 1 to 12 phr (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 phr), about 1 to about 10 phr, 1 to 10 phr (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10 phr), about 1 to about 7 phr, 1 to 7 phr, about 1 to about 5 phr, 1 to 5 phr, about 1 to about 3 phr, 1 to 3 phr , about 3 to about 15 phr, 3 to 15 phr, about 3 to about 12 phr, 3 to 12 phr, about 3 to about 10 phr, 3 to 10 phr, about 3 to about 7 phr, 3 to 7 phr, about 3 to about 5 phr, 3 to 5 phr, about 5 to about 15 phr, 5 to 15 phr, about 5 to about 12 phr, 5 to 12 phr, about 5 to about 10 phr, 5 to 10 phr, about 5 to about 7 phr, or 5 to 7 phr. In preferred embodiments of the first to third embodiments, the rubber composition comprises 8 to 12 phr of silica coupling agent, or one of the aforementioned ranges subtended therein.

[0072] carbon black filler As discussed above, according to the first through third embodiments, the tire tread rubber composition includes a limited amount of carbon black filler, more specifically, 10 phr or less (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0 phr) of carbon black filler. In certain embodiments of the first through third embodiments, the tire tread rubber composition includes 5 phr or less (e.g., 5, 4, 3, 2, 1, or 0 phr) of carbon black filler. In preferred embodiments of the first through third embodiments, the carbon black filler is present in an amount of 1 to 10 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 phr) or 1 to 5 phr (e.g., 1, 2, 3, 4, or 5 phr), or an amount within one of the aforementioned ranges.

[0073] In certain embodiments of the first through third embodiments, the aforementioned limited amount of carbon black filler should be understood to refer to reinforcing carbon black filler (i.e., 10 phr or less, 5 phr or less, or 1 to 10 or 1 to 5 phr of reinforcing carbon black filler is used). In other embodiments of the first through third embodiments, the aforementioned limited amount of carbon black filler should be understood to refer to non-reinforcing carbon black filler (i.e., 10 phr or less, 5 phr or less, or 1 to 10 or 1 to 5 phr of non-reinforcing carbon black filler). In still other embodiments of the first through third embodiments, the aforementioned limited amount of carbon black filler should be understood to refer to the total amount of all carbon black fillers (i.e., both reinforcing and non-reinforcing carbon black fillers). In preferred embodiments of the first through third embodiments, the only carbon black filler utilized is reinforcing carbon black filler.

[0074] According to the first to third and second embodiments, the particular type of carbon black utilized can vary. Generally, suitable carbon blacks for use as reinforcing fillers in the rubber compositions of certain embodiments of the first to third embodiments have a carbon black content of at least about 20 m 2 / g (at least 20m 2 / g), and more preferably at least about 35m 2 / g ~ Maximum approx. 200m 2 / g or higher (35m 2 / g~Maximum 200m 2 The term "carbon black" includes any of the commonly available commercially produced carbon blacks, including those having a surface area of ​​1 / g or greater. Surface area values ​​used herein for carbon blacks are determined by ASTM D-1765 using the cetyltrimethyl-ammonium bromide (CTAB) technique. Useful carbon blacks include furnace blacks, channel blacks, and lamp blacks. More specifically, examples of useful carbon blacks include super abrasion furnace (SAF) black, high abrasion furnace (HAF) black, fast extrusion furnace (FEF) black, fine furnace (FF) black, intermediate super abrasion furnace (ISAF) black, semi-reinforcing furnace (SRF) black, medium processability channel black, difficult processability channel black, and conductive channel black. Other carbon blacks that may be utilized include acetylene black. In certain embodiments of the first through third embodiments, the tire tread rubber composition comprises a mixture of two or more of the aforementioned blacks. Preferably, according to the first through third embodiments, the carbon black filler, if present, consists of only one type (or grade) of reinforcing carbon black. Typical carbon blacks suitable for use in certain embodiments of the first through third embodiments are N-110, N-220, N-339, N-330, N-351, N-550, and N-660, as designated by ASTM D-1765-82a. The carbon black used can be in pelletized form or in non-pelletized flocculent form. Preferably, non-pelletized carbon black is preferred for more homogeneous mixing.

[0075] Other reinforcing fillers In certain of the first through third embodiments, the tire tread rubber composition includes a reinforcing filler other than carbon black or silica (i.e., additional reinforcing fillers). One or more additional reinforcing fillers may be utilized, but their total amount is preferably limited to 10 phr or less (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0 phr), or 5 phr or less (e.g., 5, 4, 3, 2, 1, or 0 phr). In certain preferred embodiments of the first through third embodiments, the tire tread rubber composition does not contain additional reinforcing fillers (i.e., 0 phr); in other words, in such embodiments, reinforcing fillers other than silica and, optionally, carbon black, are absent.

[0076] In embodiments of the first through third embodiments in which an additional reinforcing filler is utilized, the additional reinforcing filler can vary. Non-limiting examples of additional reinforcing fillers suitable for use in the tire tread rubber compositions of certain embodiments of the first through third embodiments include, but are not limited to, alumina, aluminum hydroxide, clay (reinforcing grades), magnesium hydroxide, boron nitride, aluminum nitride, titanium dioxide, reinforcing zinc oxide, and combinations thereof.

[0077] Non-reinforcing fillers In certain embodiments of the first through third embodiments, the tire tread rubber composition for the tread further comprises at least one non-reinforcing filler that is a non-carbon black, non-reinforcing filler. In other preferred embodiments of the first through third embodiments, the tire tread rubber composition contains no non-carbon black, non-reinforcing fillers (i.e., 0 phr). In still other embodiments of the first through third embodiments, the tire tread rubber composition contains no non-reinforcing fillers (in such embodiments, the carbon black filler of the filler component is a reinforcing carbon black filler). In embodiments of the first through third embodiments in which at least one non-carbon black, non-reinforcing filler is utilized, the at least one non-reinforcing filler may be selected from clay (non-reinforcing grades), graphite, magnesium dioxide, aluminum oxide, starch, boron nitride (non-reinforcing grades), silicon nitride, aluminum nitride (non-reinforcing grades), calcium silicate, silicon carbide, ground rubber, and combinations thereof. The term "non-reinforcing filler" refers to a filler having a content of at least about 20 m 2 / g or less (20m 2 In certain embodiments, the ion exchange rate is about 10 m / g, including less than about 10 m / g. 2 / g or less (10m 2 The term "non-reinforcing filler" is used to mean a particulate material having a nitrogen adsorption specific surface area (N2SA) of less than 1 / g (including less than 1 / g). The N2SA surface area of ​​a particulate material can be determined according to various standard methods, including ASTM D6556. In certain embodiments, the term "non-reinforcing filler" alternatively or additionally refers to a particulate material having a particle size greater than about 1000 nm (including greater than 1000 nm). In those embodiments of the first through third embodiments in which non-carbon black non-reinforcing filler is present in the tire tread rubber composition, the total amount of non-carbon black non-reinforcing filler can vary, but is preferably 20 phr or less (e.g., 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 phr), and in certain embodiments, 1 to 10 phr, 10 phr or less, 5 phr or less (e.g., 5, 4, 3, 2, or 1 phr), 1 to 5 phr, or 1 phr or less.

[0078] Hydrocarbon Resin As noted above, according to the first to third embodiments, the tire tread rubber composition comprises 2 to 14 phr (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 phr) of at least one hydrocarbon resin having a Tg of about 40 to about 60° C. or 40 to 60° C. (e.g., 40, 42, 44, 45, 46, 48, 50, 52, 54, 56, 58, or 60° C.). The Tg of the hydrocarbon resin can be measured by DSC according to the procedure discussed above for measuring the Tg of elastomers. In certain preferred embodiments of the first to third embodiments, the tire tread rubber composition comprises 2 to 10 phr (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or 10 phr) of at least one hydrocarbon resin having a Tg of about 40 to about 60°C, or 40 to 60°C (e.g., 40, 42, 44, 45, 46, 48, 50, 52, 54, 55, 56, 58, or 60°C). In certain preferred embodiments of the first to third embodiments, the at least one hydrocarbon resin (d) has a Tg of about 45 to about 55°C, or 45 to 55°C (e.g., 45, 46, 48, 50, 52, 54, or 55°C). In certain preferred embodiments of the first to third embodiments, the at least one hydrocarbon resin (d) comprises an aliphatic hydrocarbon resin having a Tg of about 40 to about 60° C., 40 to 60° C., about 45 to about 60° C., 45 to 60° C., about 45 to about 55° C., or 45 to 55° C. In addition to controlling the amount of hydrocarbon resin (c) used in the tire tread rubber composition, as further discussed below according to the first to third embodiments, it is also preferred to control the total amount of hydrocarbon resin (c) and oil (d) within the amounts discussed elsewhere herein.

[0079] In certain embodiments of the first through third embodiments, the hydrocarbon resin of (d) optionally comprises an aliphatic resin in combination with one or more additional resins selected from cycloaliphatic resins, aromatic resins, and terpene resins; in those embodiments of the first through third embodiments in which one or more additional resins are present, the total amount of such additional resins is preferably 5 phr or less, less than 5 phr, less than 4 phr, less than 3 phr, less than 2 phr, or less than 1 phr (and in each case 10 wt. % or less, preferably 5 wt. % or less, of the total amount of hydrocarbon resin of (d)). In other embodiments of the first through third embodiments, the hydrocarbon resin of (d) consists (only) of an aliphatic resin. When an aliphatic resin is used, one or more aliphatic resins may be utilized. In certain embodiments of the first through third embodiments, the hydrocarbon resin (d) does not comprise any terpene resin (i.e., 0 phr of terpene resin is present in the tire tread rubber composition). As used herein, the term "aliphatic resin" should be understood to include both aliphatic homopolymer resins and aliphatic copolymer resins. Aliphatic copolymer resins refer to hydrocarbon resins containing one or more aliphatic monomers in combination with one or more other (non-aliphatic) monomers, where the greatest amount of any type of monomer is aliphatic. Aliphatic copolymer resins may include hydrocarbon resins having 25% by weight of cycloaliphatic monomers and 30% by weight of aromatic monomers, plus 45% by weight of aliphatic monomers, and hydrocarbon resins having 30% by weight of cycloaliphatic monomers and 15% by weight of aromatic monomers, plus 55% by weight of aliphatic monomers. In certain embodiments of the first through third embodiments, the hydrocarbon resin (d) comprises one or more aliphatic copolymer resins in which a majority (e.g., 51%, 55%, 60%, 65%, etc.) of the total monomers by weight are aliphatic. Non-limiting examples of aliphatic resins suitable for use as the hydrocarbon resin in certain embodiments of the first through third embodiments include C5 homopolymer or copolymer resins, C5 / C9 copolymer resins, C5 / vinyl aromatic copolymer resins (e.g., C5 / styrene copolymer resins), C5 / cycloaliphatic copolymer resins, C5 / C9 / cycloaliphatic copolymer resins, and combinations thereof.Non-limiting examples of cycloaliphatic monomers include, but are not limited to, cyclopentadiene ("CPD") and dicyclopentadiene ("DCPD"). Exemplary aliphatic resins are commercially available under various trade names from various companies, including Chemfax, Dow Chemical Company, Eastman Chemical Company, Idemitsu, Neville Chemical Company, Nippon, Polysat Inc., Resinall Corp., and Zeon.

[0080] In certain embodiments of the first through third embodiments, the hydrocarbon resin of (d) comprises a C5 fraction homopolymer resin, a C5 fraction copolymer resin (e.g., C5 in combination with one or more of the above monomers, such as C9 fraction, DCPD, CPD, and combinations thereof), or combinations thereof. In other embodiments of the first through third embodiments, the hydrocarbon resin of (c) consists (only) of a C5 fraction homopolymer resin, a C5 fraction copolymer resin (e.g., C5 in combination with one or more of the above monomers, such as C9 fraction, DCPD, CPD, and combinations thereof), or combinations thereof.

[0081] Liquid Plasticizer As discussed above, according to the first through third embodiments disclosed herein, the tire tread rubber composition comprises, as (e), 15 to 35 phr (e.g., 15, 16, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 34, or 35 phr) of a liquid plasticizer, at least a portion of which is provided by a low molecular weight styrene-butadiene rubber (as discussed above). In certain embodiments of the first through third embodiments, the amount of liquid plasticizer (e) is 15-30 phr (e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 phr) or 15-25 phr (e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 phr), with at least a portion of the liquid plasticizer being provided by low molecular weight SBR (as discussed above). The term liquid plasticizer should be understood to refer to plasticizers that are liquid at 25°C, including, but not limited to, oil and ester-based plasticizers. In certain embodiments of the first to third embodiments, at least a portion of the liquid plasticizer (e) is provided by the oil used to extend SBR(i) and / or SBR(ii), preferably SBR(ii). In certain embodiments of the first to third embodiments, the entire amount of liquid plasticizer (e) is provided by a combination of low molecular weight SBR and the oil used to extend SBR(i) and / or SBR(ii), preferably SBR(ii). In certain embodiments of the first to third embodiments, liquid plasticizer (e) is provided by a combination of low molecular weight SBR (as discussed above), the oil used to extend SBR(i) and / or SBR(ii), preferably SBR(ii), and free liquid plasticizer. The phrase free liquid plasticizer means a liquid plasticizer that is added separately to the mixing equipment used to prepare the rubber composition along with the other components of the rubber composition (e.g., SBR(i) and SBR(ii) and filler components), rather than being added via premixing or extension of the SBR or one of the other polymers used in the elastomer component.In certain embodiments of the first through third embodiments, about 10% to about 60% by weight or 10% to 60% by weight (e.g., 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, or 60%), preferably about 25% to about 50% by weight or 25% to 50% by weight (e.g., 25%, 30%, 35%, 40%, 45%, or 50%), of the liquid plasticizer (e) is provided by low molecular weight SBR (as discussed above). In certain embodiments of the first to third embodiments, about 10% to about 50% by weight or 10% to 50% by weight (e.g., 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%), preferably about 15% to about 30% by weight (e.g., 15%, 20%, 25%, or 30%), of the liquid plasticizer (e) is provided by SBR(i) and / or SBR(ii), preferably the oil used to extend SBR(ii). In certain embodiments of the first to third embodiments, about 10% to about 50% by weight or 10% to 50% by weight (e.g., 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%), preferably about 15% to about 30% by weight (e.g., 15%, 20%, 25%, or 30%) of the liquid plasticizer (e) is provided by free liquid plasticizer.

[0082] In those embodiments of the first through third embodiments in which oil-extended rubber or SBR is used, the amount of oil used to prepare the oil-extended rubber can vary, and in certain such embodiments, the amount of extended oil present in the oil-extended rubber (polymer) is 10 to 50 parts oil per 100 parts rubber (e.g., 10, 15, 20, 25, 30, 35, 40, 45, or 50 parts oil per 100 parts rubber), preferably 10 to 40 parts oil per 100 parts rubber or 20 to 40 parts oil per 100 parts rubber.

[0083] As used herein, oil refers to both petroleum-based oils (e.g., aromatic oils, naphthenic oils, and low PCA oils) and vegetable oils (such as those that can be harvested from vegetables, nuts, and seeds). Vegetable oils generally contain triglycerides, and this term should be understood to include synthetic triglycerides and those that are actually sourced from plants.

[0084] According to the first to third embodiments, when one or more oils are present in the rubber composition as at least a portion of the liquid plasticizer (e), various types of processing and extending oils that can be utilized include, but are not limited to, aromatic oils, naphthenic oils, and low PCA oils (petroleum-derived or vegetable-derived). Suitable low PCA oils include those having a polycyclic aromatic content of less than 3% by weight as measured by the IP346 method. The IP346 method procedure can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, 62nd Edition, published by the Institute of Petroleum (UK). Exemplary petroleum-derived low PCA oils include mild extraction solvate (MES), treated distillate aromatic extract (TDAE), TRAE, and heavy naphthenics. Exemplary MES oils are commercially available as CATENEX SNR (manufactured by SHELL), PROREX 15 and FLEXON 683 (manufactured by EXXONMOBIL), VIVATEC 200 (manufactured by BP), PLAXOLENE MS (manufactured by TOTAL FINA ELF), TUDALEN 4160 / 4225 (manufactured by DAHLEKE), MES-H (manufactured by REPSOL), MES (manufactured by Z8), and OLIO MES S201 (manufactured by AGIP). Exemplary TDAE oils are available as TYREX 20 (manufactured by EXXONMOBIL), VIVATEC 500, VIVATEC 180, and ENERTHENE 1849 (manufactured by BP), and EXTENSOIL 1996 (manufactured by REPSOL). Exemplary heavy naphthenic oils are available as SHELLFLEX 794, ERGON BLACK OIL, ERGON H2000, CROSS C2000, CROSS C2400, and SAN JOAQUIN 2000 L. Exemplary low PCA oils also include various plant-derived oils, such as those that can be obtained from vegetables, nuts, and seeds.Non-limiting examples include soybean oil, sunflower oil (including high oleic sunflower oil), safflower oil, corn oil, linseed oil, cottonseed oil, rapeseed oil, cashew oil, sesame oil, camellia oil, jojoba oil, hemp oil, macadamia nut oil, coconut oil, and palm oil. The aforementioned processed oils can also be used as extender oils, i.e., for the preparation of oil-extended polymers or copolymers, or as processed or free oils.

[0085] In those embodiments of the first through third embodiments in which one or more oils are present in the rubber composition as at least a portion of the liquid plasticizer (e), the Tg of the oil used can vary. In certain embodiments of the first through third embodiments, any oil utilized may have a Tg of about −40 to about −100° C., −40 to −100° C. (e.g., −40, −45, −50, −55, −60, −65, −70, −75, −80, −85, −90, −95, or −100° C.), about −40 to about −90° C., −40 to −90° C. (e.g., −40, −45, −50, −55, −60, − The polymer has a Tg of about -45 to about -85°C, about -45 to about -85°C (e.g., -45, -50, -55, -60, -65, -70, -75, -80, or -85°C), about -50 to about -80°C, or about -50 to -80°C (e.g., -50, -55, -60, -65, -70, -75, or -80°C).

[0086] Preferably, according to the first to third embodiments, the tire tread rubber composition contains less than 5 phr (e.g., 4.5, 4, 3, 2, 1, or 0 phr) of MES or TDAE oil, and preferably contains no MES or TDAE oil (i.e., 0 phr). In certain embodiments of the first to third embodiments, the rubber composition contains no petroleum oil (i.e., 0 phr); instead, any oil utilized is a vegetable oil. In certain embodiments of the first to third embodiments, the tire tread rubber composition contains soybean oil, either as free oil and / or extender oil, preferably as free oil, in one of the amounts described above; in certain such embodiments, the only oil included is soybean oil, either as free oil and / or extender oil, preferably as free oil. In certain embodiments of the first to third embodiments, the tire tread rubber composition contains no sunflower oil (i.e., 0 phr). In other embodiments of the first to third embodiments, the only oil included is sunflower oil, either as free oil and / or extender oil, preferably as free oil.

[0087] In certain embodiments of the first to third embodiments, the tire tread rubber composition includes one or more ester plasticizers for at least a portion of the liquid plasticizer (e). Ester plasticizers are generally liquid at room temperature. In other embodiments of the first to third embodiments, the liquid plasticizer (e) does not contain an ester plasticizer (i.e., 0 phr of ester plasticizer is present). Suitable ester-based plasticizers are known to those skilled in the art and include, but are not limited to, phosphate esters, phthalate esters, adipate esters, and oleate esters (i.e., derived from oleic acid). Considering that esters are chemical compounds derived from acids in which at least one —OH is replaced with an —O-alkyl group, various alkyl groups can be used in ester plasticizers suitable for use in tire tread rubber compositions, generally ranging from C1 to C6. 20 (For example, C1, C2, C3, C4, C5, C6, C7, C8, C9, C 10 , C 11 , C 12 , C 13 , C 14 , C15 C 16 C 17 C 18 C 19 C 20 ), also C6~C 12and linear or branched alkyl groups. Certain of the foregoing esters are based on acids having two or more -OH groups and therefore may accommodate one or more O-alkyl groups (e.g., trialkyl phosphates, dialkyl phthalates, dialkyl adipates). Non-limiting examples of suitable ester plasticizers include trioctyl phosphate, dioctyl phthalate, dioctyl adipate, nonyl oleate, octyl oleate, and combinations thereof. The use of ester plasticizers such as one or more of the foregoing can be beneficial to the snow or ice performance of tires made from tire tread rubber compositions containing such ester plasticizers, due at least in part to the relatively low Tg of the ester plasticizers. In certain of the first through third embodiments, the tread rubber composition comprises one or more ester plasticizers having a Tg of −40° C. to −70° C. (e.g., −40, −45, −50, −55, −60, −65, or −70° C.), or −50° C. to −65° C. (e.g., −50, −51, −52, −53, −54, −55, −56, −57, −58, −59, −60, −61, −62, −63, −64, or −65° C.). In those embodiments of the first through third embodiments in which one or more ester plasticizers are utilized, the amounts utilized can vary. In certain embodiments of the first through third embodiments, the one or more ester plasticizers are present in an amount of 1 to 25 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 phr), 1 to 20 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 phr), 1-15 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 phr), 1-10 phr (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 phr), 2-6 phr (e.g., 2, 3, 4, 5, or 6 phr), or 2-5 phr (e.g., 2, 3, 4, or 5 phr).In certain embodiments of the first through third embodiments, the one or more ester plasticizers are used in combination with oil (in one of the amounts previously mentioned), where the oil is present in an amount of 1 to less than 10 phr, or 1 to 5 phr. In other embodiments of the first through third embodiments, the one or more ester plasticizers are used without any oil being present in the tire tread rubber composition (i.e., 0 phr of oil).

[0088] In certain embodiments of the first through third embodiments, the tire tread rubber composition comprises a total amount of plasticizer from 20 to 49 phr (e.g., 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, or 49 phr), the plasticizer including all of the hydrocarbon resins and liquid plasticizers, all as discussed above. In certain embodiments of the first to third embodiments, the rubber composition comprises a total amount of plasticizer of 49 phr or less (e.g., 49, 45, 40, 35, 30, 25, or 20 phr), 20 to 40 phr (e.g., 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, or 40 phr), preferably 35 phr or less (e.g., 35, 34, 32, 30, 28, 26, 25, 24, 22, or 20 phr), or 25 to 35 phr (e.g., 25, 26, 28, 30, 32, 34, or 35 phr). In certain embodiments of the first through third embodiments, the total amount of plasticizer comprises hydrocarbon resin in a weight ratio of 2 / 1 to 1 / 5 relative to the liquid plasticizer, preferably 1 / 1 or less relative to the liquid plasticizer, for example, 1 / 1 to 1 / 4 (e.g., 1 / 1, 1 / 1.5, 1 / 2, 1 / 2.5, 1 / 3, 1 / 3.5, or 1 / 4). As a non-limiting example, if the hydrocarbon resin is used in an amount of 8 phr and the total amount of liquid plasticizer is 16 phr, the weight ratio of hydrocarbon resin to liquid plasticizer is 1 / 2.

[0089] Hardening Package As discussed above, according to the first to third embodiments disclosed herein, the tire tread rubber composition includes (comprises) a curing package. The components of the curing package may vary depending on the first to third embodiments, but generally, the curing package includes at least one of a vulcanizing agent, a vulcanization accelerator, a vulcanization activator (e.g., zinc oxide, stearic acid, etc.), a vulcanization inhibitor, and a scorch inhibitor. In certain embodiments among the first to third embodiments, the curing package includes at least one vulcanizing agent, at least one vulcanization accelerator, at least one vulcanization activator, and, optionally, a vulcanization inhibitor and / or a scorch inhibitor. The vulcanization accelerator and vulcanization activator act as catalysts for the vulcanization agent. Various vulcanization inhibitors and scorch inhibitors are known in the art and can be selected by one of ordinary skill in the art based on the desired vulcanization properties.

[0090] Examples of types of vulcanizing agents suitable for use in certain embodiments of the first through third embodiments include, but are not limited to, sulfur- or peroxide-based curing components. Accordingly, in certain such embodiments, the cure package includes a sulfur-based or peroxide-based curing agent. In preferred embodiments of the first through third embodiments, the vulcanizing agent is a sulfur-based curing agent, and in certain such embodiments, the vulcanizing agent consists (only) of a sulfur-based curing agent. Examples of particularly suitable sulfur-vulcanizing agents include "rubbermaker's" soluble sulfur, sulfur-donor curing agents such as amine disulfide, polymeric polysulfide, or sulfur olefin adducts, and insoluble polymeric sulfur. Preferably, the sulfur-vulcanizing agent is soluble sulfur or a mixture of soluble and insoluble sulfur polymers. For a general disclosure of suitable curing agents and other components (e.g., vulcanization inhibitors and scorch inhibitors) used in curing, reference may be made to Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed., Wiley Interscience, NY 1982, Vol. 20, pp. 365-468, especially Vulcanization Agents and Auxiliary Materials, pp. 390-402, or to A.Y. Coran, Vulcanization (Encyclopedia of Polymer Science and Engineering, Second Edition (1989 John Wiley & Sons, Inc.)), both of which are incorporated herein by reference. Vulcanizing agents may be used alone or in combination. Generally, in certain embodiments of the first to third embodiments, the vulcanizing agent may be used in an amount ranging from 0.1 to 10 phr (e.g., 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 phr), such as 1 to 7.5 phr, for example, 1 to 5 phr, preferably 1 to 3.5 phr (e.g., 1, 1.5, 2, 2.5, 3, or 3.5 phr).

[0091] Vulcanization accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanizate. Examples of vulcanization accelerators suitable for use in certain embodiments of the first to third embodiments disclosed herein include, but are not limited to, thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, 2,2'-dithiobis(benzothiazole) (MBTS), N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), and the like, guanidine vulcanization accelerators such as diphenyl guanidine (DPG), thiuram vulcanization accelerators, carbamate vulcanization accelerators, and the like. Generally, the amount of vulcanization accelerator used ranges from 0.1 to 10 phr (e.g., 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 phr), preferably from 1 to 6 phr (e.g., 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6 phr). Preferably, the optional vulcanization accelerator used in the rubber compositions of the first to third embodiments does not include any thiuram such as thiuram monosulfide and thiuram polysulfide (examples of which include TMTM (tetramethylthiuram monosulfide), TMTD (tetramethylthiuram disulfide), DPTT (dipentamethylenethiuram tetrasulfide), TETD (tetraethylthiuram disulfide), TiBTD (tetraisobutylthiuram disulfide), and TBzTD (tetrabenzylthiuram disulfide)). In other words, the rubber compositions of the first to third embodiments preferably do not contain a thiuram accelerator (i.e., 0 phr).

[0092] Vulcanization activators are additives used to aid vulcanization. Generally, vulcanization activators include both inorganic and organic components. Zinc oxide is the most widely used inorganic vulcanization activator. A variety of organic vulcanization activators are commonly used, including stearic acid, palmitic acid, lauric acid, and zinc salts of each of the foregoing. Generally, in certain embodiments of the first through third embodiments, the amount of vulcanization activator used ranges from 0.1 to 6 phr (e.g., 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6 phr), preferably 0.5 to 4 phr (e.g., 0.5, 1, 1.5, 2, 2.5, 3, 3.5, or 4 phr). In certain of the first through third embodiments, both zinc oxide and stearic acid are used as vulcanization activators, and the total amount utilized falls within one of the aforementioned ranges; in certain such embodiments, the only vulcanization activators used are zinc oxide and stearic acid.

[0093] Vulcanization inhibitors are used to control the vulcanization process, typically slowing or preventing vulcanization until a desired time and / or temperature is reached. Common vulcanization inhibitors include, but are not limited to, PVI (cyclohexylthiophthalmide) manufactured by Santogard. Generally, in certain embodiments of the first through third embodiments, the amount of vulcanization inhibitor is 0.01 to 1 phr (e.g., 0.01, 0.015, 0.02, 0.025, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 phr), preferably 0.01 to 0.3 phr (e.g., 0.01, 0.015, 0.02, 0.025, or 0.3 phr).

[0094] Other ingredients Various other components that may be optionally added to the tire tread rubber compositions of the first through third embodiments as disclosed herein include waxes (which in some cases are antioxidants), processing aids, reinforcing resins, peptizers, and antioxidants / antidegradants. The antioxidant components may be classified as antiozonants or antioxidants, such as those selected from N,N'-disubstituted-p-phenylenediamines, e.g., N-1,3-dimethylbutyl-N'phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N-phenyl-N-isopropyl-p-phenylenediamine (IPPD), and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (HPPD). Other examples of antidegradants include acetone diphenylamine condensation products, 2,4-trimethyl-1,2-dihydroquinoline, octylated diphenylamine, 2,6-di-t-butyl-4-methylphenol, and certain waxes. In certain other embodiments of the first through third embodiments, the tire tread rubber composition may be free of, or essentially free of, antidegradants such as antioxidants or antiozonants.

[0095] Preparation of Rubber Composition The specific steps involved in preparing the tire tread rubber compositions of the first through third embodiments disclosed herein are generally those of a conventionally practiced process that includes mixing the ingredients in at least one non-productive masterbatch stage and a final productive mix stage. In certain embodiments of the first through third embodiments, the tire tread rubber composition is prepared by mixing the ingredients of the rubber composition (as disclosed above) by methods known in the art, such as by kneading the ingredients together in a Banbury mixer or mill rolls. Such processes generally include at least one non-productive masterbatch mix stage and a final productive mix stage. The term non-productive masterbatch stage is known to those skilled in the art and is generally understood to be a mix stage or stages in which no vulcanizing agents or vulcanization accelerators are added. The term final productive mix stage is also known to those skilled in the art and is generally understood to be a mix stage in which vulcanizing agents and vulcanization accelerators are added to the rubber composition. In certain of the first through third embodiments, the tire tread rubber composition is prepared by a process that includes two or more non-productive masterbatch mixing stages.

[0096] In certain preferred embodiments of the first through third embodiments, the tire tread rubber composition is prepared by a process in which the masterbatch mixing stage includes at least one of tandem mixing or intermeshing mixing. Tandem mixing can be understood to include the use of a mixer having two mixing chambers, each having a set of mixing rotors; typically, the two mixing chambers are stacked together, with the upper mixer being the primary mixer, and the lower mixer receiving the batch from the upper or primary mixer. In certain embodiments, the primary mixer utilizes intermeshing rotors, while in other embodiments, the primary mixer utilizes tangential rotors. Preferably, the lower mixer utilizes intermeshing rotors. Intermeshing mixing can be understood to include the use of a mixer with intermeshing rotors. Intermeshing rotors refer to a set of rotors in which the larger diameter of one rotor in the set interacts with the smaller diameter of the opposing rotor in the set so that the rotors intermesh with each other. Intermeshing rotors must be driven at a uniform speed due to the interaction between the rotors. In contrast to intermeshing rotors, tangential rotors refer to a set of rotors in which each rotor rotates independently of the other within a cavity that may be referred to as a lateral surface. Generally, mixers with tangential rotors include a ram, whereas a ram is not required in mixers with intermeshing rotors.

[0097] Generally, the rubber (or polymer) and at least one reinforcing filler (and optional silane coupling agent, liquid plasticizer, and resin) are added in a non-productive or masterbatch mix stage(s). Generally, at least the vulcanizing agent and vulcanization accelerator components of the cure package are added in a final or productive mix stage.

[0098] In certain embodiments of the first through third embodiments, the tire tread rubber composition is prepared using a process in which at least one non-productive masterbatch mix stage is carried out at a temperature of about 130° C. to about 200° C. or 130-200° C. (e.g., 130, 140, 150, 160, 170, 180, 190, or 200° C.), preferably about 130 to about 180° C. or 130-180° C. (130, 140, 150, 160, 170, or 180° C.). In certain embodiments of the first through third embodiments, the tire tread rubber composition is prepared using a final productive mix stage carried out at a temperature below the vulcanization temperature to avoid undesirable pre-cure of the tire tread rubber composition. Thus, the temperature of the production or final mix stage generally should not exceed about 120°C, and is typically about 40°C to about 120°C or 40-120°C (e.g., 40, 50, 60, 70, 80, 90, 100, 110, or 120°C), or about 60°C to about 110°C, particularly about 75°C to about 100°C or 75-100°C (e.g., 75, 80, 85, 90, 95, or 100°C). In certain embodiments of the first through third embodiments, the tire tread rubber composition is prepared according to a process including at least one non-production mix stage and at least one production mix stage. The use of silica fillers may optionally require a separate regrind stage to separately add some or all of such filler. This stage is often conducted at temperatures similar to those employed in the masterbatch stage, but often slightly lower, i.e., to a drop temperature of about 90°C to about 150°C.

[0099] Properties of rubber compositions for tire treads As noted above, according to a third embodiment disclosed herein, there is provided a method for providing a tire having a road-contacting tread, the tire having balanced wet performance, rolling resistance, and cornering performance, the method comprising utilizing a tire tread rubber composition according to the first embodiment. Generally, according to the first through third embodiments disclosed herein, the tire tread rubber composition (when used as the road-contacting tread of the tire) can be understood to produce a tire having balanced wet performance, rolling resistance, and cornering performance. Additional improved or desirable properties include elongation at break (Eb), tensile at break (Tb), and Tb x Eb.

[0100] Measurement of E' (dynamic storage modulus) at different temperatures can provide an indication of various properties of a rubber composition when used as a tire tread (e.g., E' at -20°C correlates with snow traction, with a relatively low E' indicating better snow traction, and E' at 30°C correlates with stiffness or cornering, with a relatively high E' indicating improved stiffness or cornering). When the rubber composition is incorporated into a tire tread, steering stability, including cornering on dry roads, is generally affected by E' at high temperatures (e.g., 30°C), with higher values ​​being preferred, and snow traction is affected by E' at low temperatures (e.g., -20°C and -40°C), with lower values ​​being preferred. The measurements and performance referred to herein can be measured on slabs of laboratory-prepared cured rubber compositions (the rubber compositions are as discussed herein for the first to third embodiments) or can be measured on samples cut from tire treads (e.g., those containing cured versions of the rubber compositions as discussed herein for the first to third embodiments).

[0101] Measurement of tan δ at various temperatures can be used to quantify the expected wet performance, dry performance, and rolling resistance of a rubber composition when incorporated into a tire tread. Tan δ values ​​can generally be measured according to the guidelines of ASTM D5992-96 (2011) using a dynamic mechanical thermal spectrometer (Eplexor® 500N, Gabo Qualimeter Testanlagen GmbH, Ahiden, Germany) under the following conditions: measurement mode: tensile test mode, measurement frequency: 52 Hz, temperature sweep measurement, applied strain of 0.2% from -50 to -5°C and strain of 1% from -5 to 65°C, starting temperature slightly below -50°C and ending temperature slightly above -5°C, data collected approximately every 1°C to provide measurements at temperatures of -30°C, 0°C, 30°C, and 60°C, sample geometry: width 4.75 mm x length 29 mm x thickness 2.0 mm. Measurements are made on cured rubber samples (cured at 170° C. for 15 minutes). When incorporated into a tire tread, the tan δ of a rubber composition at 0° C. indicates its wet traction, when incorporated into a tire tread, its tan δ at 30° C. indicates its dry traction, and when incorporated into a tire tread, its tan δ at 60° C. indicates its rolling resistance.

[0102] In certain embodiments of the first to third embodiments, the rubber composition has a value of tan δ at 60°C of 0.15 to 0.25 (e.g., 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, or 0.25), preferably 0.16 to 0.2 (e.g., 0.16, 0.17, 0.18, 0.19, or 0.2). A tan δ at 60°C within one of the aforementioned ranges may be understood as indicative of a tire (or, more specifically, a tire tread) having low overall rolling resistance. In certain embodiments of the first to third embodiments, the value of tan δ at 60°C is: (a) a value of tan δ at 0°C that is at least 3.5 times (e.g., 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or more), preferably at least 3.7 times, or 3.7 to 4.7 times (e.g., 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7) the value of tan δ at 60°C; or (b) a value of tan δ at 0°C that is at least 1.6 times (e.g., 1.6, 1.7, 1.8, 1.9, 2, 2.1 or more), preferably ... is combined with at least one of: (a) a value of tan δ at 30°C that is 1.6 to 2 times the value of tan δ at 60°C; or (c) an E' value at 30°C that is at least 70 times (e.g., 70, 72, 74, 75, 76, 78, 80, 82, 84, 85, 86, 88, 90 times or more) the value of tan δ at 60°C, preferably at least 75 times, or 75 to 90 times (e.g., 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, or 90 times) the value of tan δ at 60°C; in certain such embodiments, a value of tan δ at 60°C is combined with each of (a), (b), and (c). In certain embodiments of the first to third embodiments, one of the aforementioned values ​​of tan δ at 60°C (e.g., 0.15 to 0.25 or 0.16 to 0.2) is combined with (a) a value of δ at 0°C that is 3.7 to 4.7 times the value of tan δ at 60°C.In certain embodiments of the first to third embodiments, one of the aforementioned values ​​of tan δ at 60°C (e.g., 0.15 to 0.25 or 0.16 to 0.2) is combined with (b) a value of tan δ at 30°C that is 1.6 to 2 times the value of tan δ at 60°C. In certain embodiments of the first to third embodiments, one of the aforementioned values ​​of tan δ at 60°C (e.g., 0.15 to 0.25 or 0.16 to 0.2) is combined with (c) a value of E' at 30°C that is 75 to 90 times the 60°C value. In certain embodiments of the first to third embodiments, one of the aforementioned values ​​of tan δ at 60°C (e.g., 0.15 to 0.25 or 0.16 to 0.2) is combined with one of the aforementioned values ​​of tan δ at -30°C, one of the aforementioned values ​​of tan δ at 0°C, and one of the aforementioned values ​​of E' at 30°C.

[0103] In certain embodiments of the first to third embodiments, the rubber composition has a room temperature Eb of at least 400% (e.g., 400%, 405%, 410%, 415%, 420%, 425%, 430%, 435%, 440%, 445%, 450%, 455%, 460%, 465%, 470%, 475%, 480%, 485%, 490%, 495%, 500% or more), or in a range of 400-550% or 400-500%, preferably at least 450%, or in a range of 450-550% or 450-500%, or a subrange within one of the aforementioned ranges. The aforementioned room temperature Eb values ​​can be determined according to the procedure described below and refer to measurements taken at 23°C.

[0104] In certain embodiments of the first to third embodiments, the rubber composition has a modulus of elasticity of at least 275% (e.g., 275%, 280%, 285%, 290%, 295%, 300%, 305%, 310%, 315%, 320%, 325%, 330%, 335%, 340%, 345%, 350%, 355%, 360%, 365%, 370%, 375% or more), or in a range of 275 to 400% or 275 to 375%, preferably at least 300% (e.g., 300%, 305%, 310%, 315%, 320%, 325%, 330%, 335%, 340%, 345%, 350%, 355%, 360%, 365%, 370%, 375% or more). The high temperature Eb may be in the range of 300-400% or 300-375%, more preferably at least 325% (e.g., 325%, 330%, 335%, 340%, 345%, 350%, 355%, 360%, 365%, 370%, 375% or more), or 325-400% or 325-375%, or a subrange within one of the aforementioned ranges. The aforementioned high temperature Eb values ​​may be determined according to the procedure described below and refer to measurements taken at 100°C.

[0105] In certain embodiments of the first to third embodiments, the rubber composition has a viscosity of at least 3100 (e.g., 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300 or more), preferably 3100, 3150, 3200, 3250, 3300, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300 or more). has a high temperature Eb x Tb (with both Eb and Tb measured at 100°C) of at least 3500 (e.g., 3500, 3550, 3600, 3650, 3700, 3750, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300 or more), more preferably at least 3700, or even at least 4000. In certain such embodiments, the high temperature Tb x Eb is 3100 to 4300, preferably 3500 to 4300 or 3700 to 4000, or a subrange within one of the foregoing ranges. The high temperature Tb x Eb is calculated by multiplying the high temperature Tb by the high temperature Eb value, which may be determined according to the procedure described below and refers to a measurement taken at 100°C.

[0106] In certain of the first to third embodiments, the rubber composition satisfies at least one of the following: (d) an Eb at 23°C of at least 400%, preferably at least 450%, and more preferably at least 475%, (e) an Eb at 100°C of at least 275%, preferably at least 300%, and more preferably at least 325%, or (f) a Tb at 100°C x Eb at 100°C value of at least 3100, preferably at least 3500, more preferably at least 3700, or even at least 4000. In certain of the foregoing embodiments, each of (d)-(f) is preferably satisfied for each according to each of the "preferably" values, and more preferably for each according to each of the "more preferably" values.

[0107] Room temperature Eb represents the elongation at break measurement (in terms of % elongation) and provides an indication of the tear resistance of a rubber composition. The abbreviation Tb refers to tensile at break; this measurement (given in MPa) provides an indication of the strength of a rubber composition by determining the maximum stress it can withstand before breaking. Eb and Tb can be measured using dumbbell-shaped specimens with a width cross-sectional dimension of 4 mm and a center thickness of 1.9 mm, following the standard procedure described in ASTM D-412, but not by way of limitation. During the measurement, the specimen can be strained at a constant rate (20% per second), and the resulting force can be recorded as a function of extension (strain). Room temperature measurements refer to measurements taken at 23°C, and hot measurements refer to measurements taken at 100°C. [Example]

[0108] The following examples illustrate particular and exemplary embodiments and / or embodiment features of the present disclosure. The examples are provided for illustrative purposes only and should not be construed as limiting the present disclosure. Many variations on these specific examples are possible without departing from the spirit and scope of the embodiments of the present disclosure. It should be specifically understood that different components (including different rubbers, different fillers, different liquid plasticizers, different resins, and different cure package components for the elastomer component) in different amounts compared to those specified in the tables can be utilized in rubber compositions according to the present disclosure (i.e., as fully disclosed in the preceding paragraphs).

[0109] Tire tread rubber compositions may be prepared using the ingredients set forth in Table 1. The amount listed for SBR represents the amount of rubber (excluding any liquid plasticizer used to extend the rubber). Example 1 may be considered a tire tread rubber composition according to the present disclosure, while Examples C1-C6 may be considered comparative tire tread rubber compositions. Each of the rubber compositions may be mixed utilizing a tandem mixing procedure (generally as described above) having a non-productive stage (carried out within a (maximum) temperature range of about 130 to about 180°C) and a productive mix stage (carried out within a (maximum) temperature range not exceeding about 120°C). [Table 1]

[0110] Table 2 provides predicted properties for each of the rubber compositions from Table 1. In particular, tan δ values ​​can be measured according to the Gabo procedure described in the section above, and E' values ​​can be measured according to the procedure described above. Room temperature Eb represents the elongation at break measurement (in terms of % elongation) and provides an indication of the tear resistance of the rubber composition. The abbreviation Tb refers to tensile at break; this measurement (made in MPa) provides an indication of the strength of the rubber composition by measuring the maximum stress it can withstand before breaking. Eb and Tb can be measured using dumbbell-shaped specimens with a width cross-sectional dimension of 4 mm and a center thickness of 1.9 mm, following the standard procedure described in ASTM D-412, but not by any limiting guidelines. During the measurement, the specimen can be strained at a constant rate (20% per second), and the resulting force can be recorded as a function of extension (strain). Room temperature measurements refer to measurements taken at 23°C, and hot measurements refer to measurements taken at 100°C. The results are reported below in Table 2, with data from an example of the invention (i.e., Example 1) used to index the comparative example values. As a non-limiting example, if Example 1's value for tan δ at 60° C. was 0.18 and Example C1's value for tan δ at 60° C. was 0.27, the indexed values ​​would be reported as 100 and 150, respectively, with 150 calculated from (0.27 / 0.18)*100. [Table 2]

[0111] As can be seen from the data provided in Table 2, varying the components in the comparative rubber compositions results in predicted properties that differ from those of the rubber compositions of the present invention. More specifically, for the rubber composition of Comparative Example C1, using less than half the weight of SBR(i) (and correspondingly more SBR(ii)) results in a rubber composition with worsened rolling resistance and a ratio of E' @ 30°C / tan δ @ 60°C of less than 70. For the rubber composition of Comparative Example C2, a ratio of 250 to 320 m 2By using less reinforcing silica filler having a BET surface area in the range of / g, a rubber composition having a ratio of E' / tanδ at 30°C to tanδ at 60°C less than 70, an Eb at 100°C less than 300%, and a Tb×Eb less than 3100 can be obtained. Regarding the rubber composition of Comparative Example C3, by using more hydrocarbon resin (i.e., 19 phr instead of 9 phr), a rubber composition having a ratio of E' / tanδ at 30°C to tanδ at 60°C less than 75, a ratio of tanδ at 30°C to tanδ at 60°C less than 1.6, deteriorated rolling resistance, and a Tb×Eb less than 3500 can be obtained. Regarding the rubber composition of Comparative Example C4, by using less than a majority weight of SBR(i) and replacing SBR2 with SBR4 (SBR4 has a slightly higher Tg than SBR2), a rubber composition having a ratio of tanδ at 0°C to tanδ at 60°C exceeding 4.7, deteriorated dry performance, and a Tb×Eb less than 3100 can be obtained. Regarding the rubber composition of Comparative Example C5, by removing SBR(i) (i.e., SBR1) and replacing it with non-functionalized SBR4, a rubber composition having a ratio of tanδ at 0°C to tanδ at 60°C exceeding 4.7, a ratio of E' / tanδ at 30°C to tanδ at 60°C less than 70, and a Tb×Eb less than 3100 can be obtained. Regarding the rubber composition of Comparative Example C6, by using a silica filler having a lower BET surface area, a rubber composition having a ratio of tanδ at 0°C to tanδ at 60°C exceeding 4.7, a ratio of E' / tanδ at 30°C to tanδ at 60°C less than 75, an Eb at 100°C of only 300%, and a Tb*Eb less than 3100 can be obtained.

[0112] In general, those skilled in the art will understand that the terms used in this specification, and particularly in the appended claims, are generally intended to be "open" terms. For example, the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," and the term "including" should be interpreted as "including but not limited to." Furthermore, those skilled in the art will understand that where a specific number is intended in a prefaced claim recitation, such intention shall be expressly recited in the claim; otherwise, no such intention exists. For example, as an aid to understanding, the following appended claims may include the use of the preface terms "at least one" and "one or more" to preface the claim recitation. However, the use of such phrases should not be construed as meaning that the preface of a claim recitation with the indefinite article "a" or "an" limits any particular claim containing the claim recitation so prefaced to inventions containing only one such recitation, even if the same claim also includes the preface phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" or "an" should typically be interpreted to mean "at least one" or "one or more"). The same is true for the use of definite articles used to preface claim recitations. Additionally, even when a particular number is explicitly recited in a prefaced claim recitation, those skilled in the art understand that such a recitation should typically be interpreted to mean at least the recited number (e.g., the explicit recitation "two recitations" without any other modifier typically means at least two recitations, or more than two recitations). Furthermore, when a conventional expression similar to "at least one of A, B, and C, etc." is used, such a configuration is generally intended in the sense that one of ordinary skill in the art would understand the conventional expression (e.g., "a system having at least one of A, B, and C" may include, but is not limited to, a system having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.).Furthermore, those skilled in the art will understand that virtually any disjunctive word or phrase presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibility of including one of those terms, either of those terms, or both of those terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." All references, including but not limited to patents, patent applications, and non-patent literature, are incorporated herein by reference in their entirety. While various aspects and embodiments of the compositions and methods have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes only and are not intended to limit the true scope and spirit of the appended claims.

Claims

1. (a) 100 parts of an elastomer component, (i) 51 to 65 parts of at least one styrene-butadiene rubber having silica-reactive functional groups and a Tg of −50 to −35° C.; (ii) 35 to 49 parts of at least one non-functionalized styrene-butadiene rubber, the non-functionalized styrene-butadiene rubber having a Tg of −30 to −15° C.; an elastomeric component comprising: (a)(i) and (a)(ii) present in a combined amount of at least 90% by weight of said elastomeric component; (b) at least one reinforcing silica filler in an amount of 60 to 90 phr, ２ a reinforcing silica filler having a BET surface area of ​​1 / g; (c) 10 phr or less of a carbon black filler; (d) 2 to 10 phr of at least one aliphatic hydrocarbon resin, the aliphatic hydrocarbon resin having a Tg of 40 to 60°C; (e) 15 to 30 phr of a liquid plasticizer; (f) a curing package; A tire tread rubber composition made from ingredients comprising: at least a portion of (e) is provided by a low molecular weight styrene-butadiene rubber having a Tg of −30 to −10° C. and a Mw of less than 200,000 grams / mole according to polystyrene standards, and (d) and (e) are present in a combined amount of 35 phr or less; Tire tread rubber composition.

2. 10. The tire tread rubber composition of claim 1, wherein said at least one styrene-butadiene rubber (a)(i) has a Mw of 300,000 to 500,000 grams / mole and said at least one styrene-butadiene rubber (a)(ii) has a Mw of 400,000 to 700,000 grams / mole, both according to polystyrene standards.

3. The rubber composition has a tan δ value at 60°C of 0.16 to 0.2, and (a) having a tan δ value at 0°C that is 3.5 to 4.7 times the tan δ value at 60°C; (b) having a tan δ value at 30°C that is 1.6 to 2 times the tan δ value at 60°C; or (c) having a dynamic storage modulus (E') at 30°C that is 70 to 90 times the tan δ value at 60°C; The tire tread rubber composition according to claim 1 or claim 2, which satisfies at least one of the above.

4. The rubber composition comprises: (d) having an elongation at break (Eb) at 23°C of at least 400%; (e) having an elongation at break (Eb) at 100°C of at least 275%, or (f) the tensile at break (Tb) at 100°C multiplied by the elongation at break (Eb) at 100°C is at least 3100; The tire tread rubber composition according to any one of claims 1 to 3, which satisfies at least one of the above.

5. A tire comprising a road-contacting tread comprising the tire tread rubber composition according to any one of claims 1 to 4.

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