Tread composition for all season tires

Abstract

The present invention relates to a tread composition for an all season tire. A vulcanizable rubber composition suitable for tire treads that provides a balance of rolling resistance, wet traction, and grip on snow and ice, comprising 60-100 phr of a solution polymerized styrene butadiene rubber with a styrene content of 2-10 wt.%, a styrene content of 1-10 wt.%, and a styrene content of 1-10 wt.%. The present invention relates to a rubber composition comprising a rubber composition having a Tg of from-95 DEG C to-75 DEG C, 0-40 phr of a polybutadiene rubber, at least 100 phr of a silica filler, at least 6 parts by weight (phf) of a blocked mercaptoorganosilane coupling agent per hundred parts of silica filler, at least 40 phr of a hydrocarbon traction resin, at least 5 phr of a substituted or unsubstituted phenolic tackifying resin, and a cure package comprising a sulfur-based curing agent, zinc oxide, and a cure accelerator.

Description

Technical Field

[0001] Described herein are rubber compositions, methods of forming the rubber compositions, and components of pneumatic tires, such as tire treads, formed from the compositions. The rubber compositions are capable of improving wet performance and rolling resistance while maintaining or improving snow performance. Background Art

[0002] For all-season and winter tires, it is desirable to have good wet skid resistance, low rolling resistance, and good performance in the snow. Traditionally, it is difficult to maintain snow performance without sacrificing its wet skid resistance and rolling resistance properties. These properties depend to a large extent on the dynamic viscoelastic properties of the rubber composition used to make the tire.

[0003] In order to reduce rolling resistance, elastomers with high resilience are often used to make tire tread rubber compounds. On the other hand, in order to improve the wet skid resistance of the tire, elastomers that experience greater energy losses are used in the tire tread. In order to balance these two viscoelastic inconsistencies, a mixture of various types of synthetic and / or natural rubber is usually used in the tire tread.

[0004] For year-round use, a tire having a tread to promote traction on snowy and icy surfaces, as well as wet traction on wet roads is desirable.

[0005] Vulcanized rubber compositions for tire treads have been developed, including styrene-butadiene rubber (SSBR) of solution polymerization combined with polybutadiene rubber (PBD), silica and other additives in a selected ratio. For example, U.S. Publication No. 20200283602A1 describes a pneumatic tire tread, which includes a vulcanizable rubber composition containing a specific SSBR and high cis-PBD, silica and a resin selected from C5 / C9 resin and DCPD / C9 resin. U.S. Publication No. 20170145195A1 describes a pneumatic tire tread, which includes a vulcanizable rubber composition containing SSBR, PBD, one or more hydrocarbon resins and silica in a specific weight ratio. U.S. Publication No. 20100186869A1 describes a vulcanizable rubber composition, which includes SSBR, high cis-PBD and silica functionalized with an alkoxysilane group and at least one functional group selected from primary amines and mercaptans (thiol) .

[0006] Such rubber compositions generally tend to favor wet traction over snow performance, or vice versa.There remains a need for a rubber composition for a tire tread that provides improved wet performance while maintaining performance in the snow and providing low rolling resistance. Summary of the invention

[0007] According to one embodiment, the vulcanizable rubber composition includes 80 to 100 parts per hundred parts of rubber (phr) of a polydiene component, the polydiene component comprising 60 to 100 phr of solution polymerized styrene butadiene rubber, wherein the styrene content is 2 to 10% by weight and the Tg is -95°C to -75°C, and 0 to 40 phr of polybutadiene rubber. The rubber composition also includes at least 100 phr of silica filler; at least 6 parts by weight (phf) of a blocked mercapto organosilane coupling agent per hundred parts of silica filler; at least 40 phr of a hydrocarbon traction resin; at least 5 phr of a substituted or unsubstituted phenolic resin; and a cure package comprising: a sulfur-based curing agent, zinc oxide, and a cure accelerator.

[0008] In various aspects of this embodiment, alone or in combination:

[0009] The solution polymerized styrene butadiene rubber is present at 70 to 90 phr.

[0010] The polybutadiene rubber is present at 10 to 30 phr.

[0011] The weight ratio of the solution-polymerized styrene butadiene rubber to the polybutadiene rubber is 2.5:1 to 5:1.

[0012] The solution-polymerized styrene butadiene rubber has a styrene content of not more than 8% by weight.

[0013] Solution polymerized styrene butadiene rubber is functionalized with an aminosilane, such as an alkoxyaminosilane.

[0014] The silica filler is at least 140 phr.

[0015] The blocked mercapto organosilane coupling agent includes 3-octanoylthio-1-propyltriethoxysilane.

[0016] The blocked mercapto organosilane coupling agent is at least 10 phr and / or at most 18 phr, or at most 15 phr.

[0017] The total amount of coupling agents other than the blocked mercapto organosilane coupling agent does not exceed 2 phr.

[0018] The hydrocarbon pulling resin is at least 50 phr and / or at most 80 phr, or at most 70 phr.

[0019] Hydrocarbon pulling resins include hydrogenated dicyclopentadiene / C9 resins.

[0020] The substituted or unsubstituted phenolic resin is present in an amount of at least 8 phr and / or at most 12 phr.

[0021] Substituted or unsubstituted phenolic resins include alkylphenol formaldehyde resins.

[0022] The vulcanizable rubber composition also includes at least one of a liquid plasticizer and a wax.

[0023] The vulcanizable rubber composition includes no more than 5 phr or no more than 2 phr of carbon black.

[0024] The tire tread is formed from the rubber composition of any one of the above aspects. The tire may include a tread.

[0025] According to another embodiment, a method of forming a tire tread includes mixing together 80 to 100 parts per hundred parts of rubber (phr) of a polydiene component to form a vulcanizable rubber composition, the polydiene component including 60 to 100 phr of solution polymerized styrene butadiene rubber, wherein the styrene content is 2 to 10% by weight and the Tg is -95°C to -75°C, and 0 to 40 phr of polybutadiene rubber; at least 100 phr of silica; at least 6 parts by weight (phf) of a blocked mercapto organosilane coupling agent per hundred parts of silica; at least 40 phr of a hydrocarbon traction resin; at least 5 phr of a substituted or unsubstituted phenolic resin; and a cure package including a sulfur-based curing agent, zinc oxide, and a cure accelerator. The method also includes curing the vulcanizable rubber composition to form a tire tread.

[0026] According to another embodiment, the vulcanizable rubber composition comprises 70 to 85 phr of solution-polymerized styrene butadiene rubber, wherein the styrene content is 2 to 10 weight percent and the cis-1,4-butadiene content is less than 45; 15 to 30 phr of polybutadiene rubber; 140 to 170 phr of silica filler; 8 to 15 phr of blocked mercapto organosilane coupling agent; 50 to 70 phr of hydrocarbon traction resin; 8 to 12 phr of substituted or unsubstituted phenolic resin; and a cure package including a sulfur-based curing agent, zinc oxide and a cure accelerator.

[0027] The present invention discloses the following embodiments:

[0028] 1. A vulcanizable rubber composition comprising:

[0029] 80-100 parts per hundred parts of rubber (phr) of a polydiene component, the polydiene component comprising:

[0030] 60-100 phr of a solution polymerized styrene-butadiene rubber having a styrene content of 2-10 wt% and a Tg of -95°C to -75°C, and

[0031] 0-40phr of polybutadiene rubber;

[0032] At least 100 phr of silica filler;

[0033] at least 6 parts by weight (phf) of a blocked mercapto organosilane coupling agent per hundred parts of silica filler; and

[0034] at least 40 phr of a hydrocarbon traction resin;

[0035] At least 5 phr of a substituted or unsubstituted phenolic resin; and

[0036] Curing package.

[0037] 2. The vulcanizable rubber composition according to embodiment 1, wherein the solution polymerized styrene butadiene rubber is present at 70-90 phr, and / or wherein the polybutadiene rubber is present at 10-30 phr.

[0038] 3. The vulcanizable rubber composition according to embodiment 1, wherein the weight ratio of the solution-polymerized styrene butadiene rubber to the polybutadiene rubber is 2.5:1 to 5:1

[0039] 4. The vulcanizable rubber composition according to embodiment 1, wherein the solution-polymerized styrene butadiene rubber has a styrene content of not more than 8 wt%.

[0040] 5. The vulcanizable rubber composition of embodiment 1, wherein the solution polymerized styrene butadiene rubber is functionalized with an aminosilane.

[0041] 6. The vulcanizable rubber composition according to embodiment 5, wherein the aminosilane comprises an alkoxyaminosilane.

[0042] 7. The vulcanizable rubber composition according to embodiment 1, wherein the silica filler is at least 140 phr.

[0043] 8. The vulcanizable rubber composition according to embodiment 1, wherein the blocked mercapto organosilane coupling agent comprises 3-octanoylthio-1-propyltriethoxysilane.

[0044] 9. The vulcanizable rubber composition according to embodiment 1, wherein the blocked mercapto organosilane coupling agent is at least 10 phr.

[0045] 10. The vulcanizable rubber composition according to embodiment 1, wherein the coupling agent other than the blocked mercapto organosilane coupling agent does not exceed 2 phr in total.

[0046] 11. The vulcanizable rubber composition according to embodiment 1, wherein the hydrocarbon traction resin is at least 50 phr.

[0047] 12. The vulcanizable rubber composition of embodiment 1, wherein the hydrocarbon traction resin comprises a hydrogenated dicyclopentadiene / C9 resin.

[0048] 13. The vulcanizable rubber composition according to embodiment 1, wherein the substituted or unsubstituted phenolic resin is present in an amount of at least 8 phr.

[0049] 14. The vulcanizable rubber composition according to embodiment 1, wherein the substituted or unsubstituted phenolic resin comprises an alkylphenol formaldehyde resin.

[0050] 15. The vulcanizable rubber composition according to embodiment 1, further comprising at least one of a liquid plasticizer and a wax.

[0051] 16. The vulcanizable rubber composition according to embodiment 1, comprising no more than 5 phr of carbon black.

[0052] 17. A tire tread formed from the rubber composition of embodiment 1.

[0053] 18. A tire comprising the tread of embodiment 17.

[0054] 19. A method of forming a tire tread, comprising:

[0055] Mixing together 80-100 parts per hundred parts of rubber (phr) of a polydiene component comprising 60-100 phr of a solution polymerized styrene butadiene rubber having a styrene content of 2-10 wt. % and a Tg of -95°C to -75°C, and 0-40 phr of a polybutadiene rubber; at least 100 phr of silica; at least 6 parts by weight (phf) of a blocked mercapto organosilane coupling agent per hundred parts of silica; at least 40 phr of a hydrocarbon traction resin; at least 5 phr of a substituted or unsubstituted phenolic resin; and a cure package comprising a sulfur-based curing agent, zinc oxide, and a cure accelerator to form a vulcanizable rubber composition; and

[0056] The vulcanizable rubber composition is cured to form the tire tread.

[0057] 20. A vulcanizable rubber composition comprising:

[0058] 70-85 phr of a solution-polymerized styrene butadiene rubber having a styrene content of 2-10 wt. % and a cis-1,4-butadiene content of less than 45;

[0059] 15-30phr of polybutadiene rubber;

[0060] 140-170 phr of silica filler;

[0061] 8-15 phr of a blocked mercapto organosilane coupling agent;

[0062] 50-70 phr of hydrocarbon traction resin;

[0063] 8-12 phr of a substituted or unsubstituted phenolic resin; and

[0064] A cure package comprising a sulfur based curing agent, zinc oxide, and a cure accelerator. Specific implementation plan

[0065] A rubber composition is described that is suitable for forming an all-season tire or winter tire tread. The rubber composition includes an elastomeric component that includes a low Tg functionalized elastomer, a silica filler, a blocked mercapto organosilane coupling agent, a traction resin, and a substituted or unsubstituted phenolic tackifying resin. This combination has been found to improve the balance of wet performance, rolling resistance, and snow performance indicators in tire treads.

[0066] definition

[0067] As used herein, unless otherwise specified, the terms "rubber" and "elastomer" are used interchangeably. Unless otherwise specified, the terms "cure" and "vulcanize" are used interchangeably.

[0068] The term "tread" means the area of ​​the tire that comes in contact with the road when normally inflated and loaded, and any subtread.

[0069] The term "phr" means parts per hundred parts of rubber by weight. Typically, using this convention, a rubber composition includes 100 parts by weight of rubber / elastomer. The claimed composition may include other rubbers / elastomers than those explicitly mentioned in the claims, as long as the phr value of the claimed rubber / elastomer meets the claimed phr range and the amount of all rubbers / elastomers in the composition totals 100 parts of rubber. The term "phf" means parts per hundred parts by weight of silica in the rubber composition.

[0070] The molecular weight of elastomers, rubber compositions and resins, such as M n (number average molecular weight), M w (weight average molecular weight) and M z(Z-average molecular weight) is determined herein using gel permeation chromatography (GPC) according to ASTM D5296-19, "Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Polystyrene by High Performance Size-Exclusion Chromatography," using polystyrene calibration standards.

[0071] The glass transition temperature (Tg) of an elastomer or an elastomeric composition is the glass transition temperature or temperatures of the respective elastomer or elastomeric composition in its uncured state or, in the case of an elastomeric composition, possibly in the cured state.

[0072] The Tg value of the elastomer is measured as the peak midpoint by differential scanning calorimetry (DSC) at a heating rate of 10°C / min in accordance with ASTM D3418-21, "Standard Test Method for Transition On Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry".

[0073] The glass transition temperature Tg of the resin is measured as the peak midpoint by a differential scanning calorimeter (DSC) at a heating rate of 10°C / min in accordance with ASTM D6604-00 (2017), "Standard Practice for Glass Transition Temperatures of Hydrocarbon Resins by Differential Scanning Calorimetry".

[0074] The glass transition temperature Tg of the oil is measured as the peak midpoint by a differential scanning calorimeter (DSC) at a heating rate of 10°C / min in accordance with ASTM E1356-08 (2014), "Standard Test Method for Assignment of the Glass Transition Temperatures by Differential Scanning Calorimeter".

[0075] The softening point of a resin is measured according to ASTM E28-18, "Standard Test Methods for Softening Point of Resins Derived from Pine Chemicals and Hydrocarbons, by Ring-and-Ball Apparatus," which is sometimes referred to as the ring and ball softening point.

[0076] Mooney viscosity (ML 1+4) is measured in units of MU at 100°C according to ASTM D1646-19a, "Standard Test Methods for Rubber-Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)".

[0077] Unless otherwise stated, the cis, trans and vinyl contents (%) of a polymer refer to the molar proportions of the 1,4-cis, 1,4-trans and 1,2-vinylbutadiene units of the polymer. These percentages can be determined by solid state NMR.

[0078] Styrene content refers to the weight percent of bound styrene in a polymer (eg, styrene-butadiene polymer) and can be measured by FT-IR.

[0079] A. Vulcanizable rubber composition

[0080] In one embodiment, a vulcanizable rubber composition suitable for forming a tire tread comprises:

[0081] a) 80-100 parts by weight per hundred parts of rubber (phr) of a polydiene component comprising:

[0082] i) 60-100 phr of a solution polymerized styrene-butadiene rubber (SSBR) having a styrene content of 2-10 wt% and a Tg of -95°C to -75°C, and

[0083] ii) 0-40 phr of polybutadiene rubber (PBD);

[0084] b) 0-20 phr of one or more elastomers different from a) and b);

[0085] c) at least 100 phr of silica filler;

[0086] d) one or more coupling agents, including at least 6 parts by weight per hundred parts of silica (phf) of a blocked mercapto organosilane coupling agent;

[0087] e) a resin component comprising:

[0088] i) at least 40 phr of a hydrocarbon pulling resin, such as hydrogenated dicyclopentadiene (HDCPD) / C9 resin,

[0089] ii) at least 5 phr of a substituted or unsubstituted phenolic tackifying resin, such as a phenol formaldehyde resin;

[0090] f) 0-15 phr of a liquid plasticizer, for example a process oil, for example a vegetable oil;

[0091] g) 0-3 phr wax; and

[0092] h) a curing package comprising:

[0093] i) sulfur-based curing agents,

[0094] ii) zinc oxide, and

[0095] iii) Curing accelerator.

[0096] The cure package may further include iv) one or more organic activators, such as fatty acids, alkaline earth metal salts of fatty acids, and combinations thereof; and v) a cure retardant.

[0097] The rubber composition optionally includes additional rubber compounding materials such as antioxidants, antiozonants, antidegradants, and the like.

[0098] When used to form a tire tread for a pneumatic tire, the rubber composition provides a combination of improved wet traction, rolling resistance, and snow performance, as determined by various indices of these properties. Wet traction is the ability of a tire to stop on a wet road surface. Rolling resistance is the energy a vehicle needs to send to a tire to maintain movement at a consistent speed over a surface and thereby affects the fuel efficiency of the vehicle. Snow performance relates to the ability of a tire to stop on snowy and icy roads.

[0099] Exemplary components of the rubber composition are now described.

[0100] a) Polydiene elastomer

[0101] The rubber composition includes one or more polydiene elastomers, each of which is derived at least in part from butadiene. In one embodiment, the polydiene elastomer includes solution polymerized styrene / butadiene rubber (SSBR) and polybutadiene rubber (PBD). The weight ratio of SSBR to PBD may be at least 2.5:1, or at least 3:1, or at least 4:1, or at most 9:1, or at most 6:1, or at most 5:1.

[0102] In one embodiment, the polydiene component has a low cis content. This can be achieved by combining a solution polymerized styrene-butadiene rubber having a styrene content of 2-10 wt%, a cis content of no more than 50%, and a Tg of -95°C to -75°C with a polybutadiene rubber that may have a higher cis content than the solution polymerized styrene-butadiene rubber but is present in a smaller amount.

[0103] i) Solution polymerized styrene butadiene rubber (SSBR)

[0104] Solution polymerized styrene butadiene rubber (SSBR) (excluding any extender oil) may be present in the rubber composition at 60-100 phr, or at least 70 phr, or at least 72 phr, or up to 95 phr, or up to 90 phr, or up to 85 phr, or up to 80 phr, for example 75±2 phr.

[0105] Exemplary SSBRs may have a low styrene content. The styrene content of the SSBR may be at least 2 wt%, or at least 3 wt%, or at least 4 wt%, or up to 10 wt%, or up to 8 wt%, or up to 6 wt%, such as 5±1 wt%.

[0106] Exemplary SSBRs may have a medium vinyl microstructure. The vinyl content of the SSBR may be at least 8%, or at least 10%, or at most 14%, or at most 12%, such as 11±2%; the cis-1,4-butadiene content of the SSBR may be less than 60%, or less than 50%, or less than 45%, or less than 40%, or at least 20%, or at least 30%, such as 40±5%; and the balance may be trans-1,4, to constitute 100% of the butadiene content of the polymer.

[0107] The Tg of the SSBR may be from -95°C to -75°C, such as at least -90°C, or up to -80°C, for example -85±3°C.

[0108] The Mooney viscosity (ML1+4 at 100°C) of SSBR may be 80-100, such as 90±5.

[0109] The SSBR may have an Mw of at least 550, or at least 600, or at most 700, or at most 650. The SSBR may have an Mn of at least 300, or at most 375, or at most 350.

[0110] SSBR can be functionalized with various functional groups, or SSBR can be non-functionalized. SSBR can be obtained by copolymerization of styrene and butadiene with aminosilane and / or other functional groups, which produces one or more functional groups bonded to the polymer chain. Other functional groups that can be used include thiol groups, hydroxyl groups, ethoxy groups, epoxy groups, amino groups, carboxyl groups, phthalocyanine groups, silane-sulfide groups and mixtures thereof. In one embodiment, SSBR can be partially hydrogenated to reduce the number of double bonds in the butadiene-derived units of the polymer.

[0111] Suitable SSBR can be formed by polymerization of styrene and 1,3-butadiene monomers and monomers for polymer functionalization. SSBR can be prepared, for example, by anionic polymerization in an inert organic solvent. For example, SSBR can be synthesized by copolymerizing styrene and 1,3-butadiene monomers in a hydrocarbon solvent using organic alkali metals and / or organic alkaline earth metals as initiators, such as organic lithium compounds. Alternatively, SSBR can be tin coupled. One or more functional groups can be bonded to any one of the main chain and side chains of the polymerization initiation end, the polymerization termination end, styrene-butadiene rubber, as long as they are bonded to the styrene-butadiene rubber chain. Other methods for preparing SSBR are described in, for example, U.S. Patent Nos. 7,137,423 B2, 7,342,070 B2, 8,312,905 B2 and U.S. Publication Nos. 20080287601 A1 and 20140135437 A1.

[0112] In one embodiment, the SSBR is functionalized with aminosilane groups, such as aminosiloxane groups, which may be sulfur-free. In one embodiment, the aminosiloxane compound used for functionalization has Formula 1:

[0113]

[0114] Among them A 1 and A 2 are each independently a substituted or unsubstituted divalent hydrocarbon group of 1 to 20 carbon atoms, such as an alkylene group, a cycloalkylene group, an alkenyl group or an arylene group, for example an alkylene group of 1 to 6 carbon atoms, such as a methylene group, an ethylene group or a propylene group,

[0115] R 1 To R 4 each independently H or a substituted or unsubstituted monovalent hydrocarbon group of 1 to 20 carbon atoms, such as a substituted or unsubstituted alkyl group of 1 to 10 carbon atoms, or 1 to 6 carbon atoms, a cycloalkyl group of 3 to 10 carbon atoms, an aryl group of 6 to 12 carbon atoms, an alkylaryl group of 7 to 12 carbon atoms, an arylalkyl group of 7 to 12 carbon atoms, wherein one or more substituents, when present, may be an alkyl group and / or a halogenated (e.g. chloro) group, and

[0116] L 1 To L 4 Each is independently H or a substituted or unsubstituted monovalent hydrocarbon group of 1 to 20 carbon atoms, such as an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or an alkylaryl group, for example an alkyl group of 1 to 6 carbon atoms.

[0117] In one embodiment, in the aminosilane compound of Formula 1, A 1 and A 2 Each independently is an alkylene group having 1 to 3 carbon atoms, R 1 To R 4 are each independently an alkyl group having 1 to 6 carbon atoms, and L 1 To L 4 Each is independently an alkyl group having 1 to 6 carbon atoms.

[0118] Such aminosilanes are described, for example, in U.S. Pat. No. 10,533,062 B2.

[0119] Other aminosilanes that can be used for functionalization can have the general formula 2:

[0120]

[0121] Where R 5 and R 6 Each is a C1-C20, or C1-C6, or C1-C3 hydrocarbon group, or a C1-C20, or C1-C6, or C1-C3 heteroatom-containing hydrocarbon group, R 7 is a C1-C10 or C1-C6 hydrocarbon group, R 8 and R 9 Each is a C1-C20, or C1-C6, or C1-C3 hydrocarbon group, and n is an integer from 1 to 3.

[0122] Such aminosilanes are described, for example, in U.S. Pat. No. 9,951,150 B2.

[0123] Other aminosilanes that can be used for functionalization can have the general formula 3:

[0124]

[0125] Where R 10 and R 15 Each is a C1-C20 or C1-C6 hydrocarbon group, or a C1-C20 or C1-C6 hydrocarbon group containing heteroatoms, R 12 is a C1-C10 or C1-C6 hydrocarbon group, R 13 and R 14 Each is a C1-C20, or C1-C6 hydrocarbon group, when m is 1, R 11is a C1-C10 hydrocarbon group, and when m is 2, R 11 does not exist, n is an integer from 1 to 3, and m is an integer of 1 or 2.

[0126] For example, OR 13 It can be ethoxy, R 10 , R 14 and R 15 It can be CH 3 , m can be 2 and R 11 does not exist, and n can be 2.

[0127] Such aminosilanes are described, for example, in U.S. Pat. No. 9,822,192 B2.

[0128] Other examples of aminosilane compounds that can be used for functionalization include mono-, di-, tri-, and tetra-(alkylamino)alkenylmethylsilanes, -(alkenylamino)alkenylmethylsilanes, -(alkylamino)halomethylsilanes, -(alkenylamino)halomethylsilanes, -(arylamino)alkenylmethylsilanes, -(arylamino)halomethylsilanes, and combinations thereof.

[0129] The content of the aminosilane bonded to the polymer chain of the SSBR may be 0.5-200 mmol / kg of the styrene-butadiene rubber, or 1 to 100 mmol / kg, or 2 to 50 mmol / kg of the styrene-butadiene rubber.

[0130] For ease of processing, SSBR can be extended with extender oil.

[0131] Suitable low styrene, styrene-butadiene rubbers multifunctionalized with aminosilane groups are commercially available, such as M0511 from LG Chemicals. TM .

[0132] ii) High cis polybutadiene rubber (PBD)

[0133] The rubber composition includes 0-40phr of polybutadiene rubber (PBD). PBD can be present in the rubber composition with at least 5phr, or at least 10phr, or at least 15phr, or at least 20phr, or at most 35phr, or at most 30phr, or 22±5phr. The polybutadiene rubber can be a synthetic polybutadiene, which is a homopolymerization product of a single monomer butadiene. In one embodiment, cis-1,4-polybutadiene rubber, i.e., cis-1,4-butadiene-dominated polybutadiene rubber is used.

[0134] Suitable polybutadiene rubbers can be prepared, for example, by organic solution polymerization of 1,3-butadiene. The PBD can be conveniently characterized, for example, by having a cis-1,4 butadiene content of at least 90% by weight ("high cis" content), or at least 95% by weight, or at least 96% by weight cis-1,4 butadiene content. Polybutadiene rubbers with lower cis contents are also contemplated.

[0135] The glass transition temperature (Tg) of the PBD measured according to ASTM D3418 may be -112 to -95°C, or -110 to -100°C, such as -106±3°C. The PBD may have a Mooney viscosity measured according to ASTM D1646 of 45-65 M.U., such as 55±5.

[0136] Suitable polybutadiene rubbers are commercially available, such as BUTYRENE from The Goodyear Tire & Rubber Company. 1223, 1207, 1208 and 1280. These high cis 1,4-polybutadiene rubbers can be synthesized using nickel or neodymium catalyst systems, such as those comprising a mixture of (1) an organic nickel compound, (2) an organic aluminum compound, and (3) a fluorine-containing compound, such as those described in U.S. Pat. Nos. 5,698,643 and 5,451,646. For example, 1223 is a solution polymerized high cis 1,4-polybutadiene stabilized with a non-staining antioxidant. This polymer is made using a stereoregular neodymium catalyst which controls the molecular weight distribution and provides a highly linear polymer weight distribution and provides a highly linear polymer. 1223 has a Mooney viscosity of 55 (ML1+4 at 100°C), a Tg of -106°C, an onset Tg of -110°C, a cis-1,4 butadiene content of 96-97 wt%, a maximum of 0.5 wt% volatiles, and a specific gravity of 0.91.

[0137] In one embodiment, the PBD may be hydrogenated and / or functionalized. If employed, the functionalization may be selected from one or more of hydroxyl groups, ethoxy groups, epoxy groups, siloxane groups, amine groups, amine siloxane groups, carboxyl groups, phthalocyanine groups, and silane-sulfide groups at the polymer chain ends or at pendant positions within the polymer, as described above for SSBR.

[0138] b) Other elastomers

[0139] The rubber composition may include 0 to 20 phr, or up to 10 phr, or up to 5 phr, or up to 2 phr, or up to 1 phr of one or more elastomers different from those described above for a).

[0140] Such one or more other vulcanizable elastomers may be selected from natural rubber, synthetic polyisoprene, halogenated butyl rubber (e.g., bromobutyl rubber and chlorobutyl rubber), nitrile rubber, liquid rubber, polynorbornene copolymer, isoprene-isobutylene copolymer, ethylene-propylene-diene rubber, chloroprene rubber, acrylate rubber, fluororubber, silicone rubber, polysulfide rubber, epichlorohydrin rubber, styrene-isoprene-butadiene terpolymer, hydrated acrylonitrile butadiene rubber, isoprene-butadiene copolymer, butyl rubber, hydrogenated styrene-butadiene rubber, butadiene acrylonitrile rubber, terpolymers formed from ethylene monomers, propylene monomers and / or ethylene propylene diene monomers (EPDM ), isoprene-based block copolymers, butadiene-based block copolymers, styrenic block copolymers, styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene / butylene-styrene block copolymers (SEBS), styrene-[ethylene-(ethylene / propylene)]-styrene block copolymers (SEEPS), styrene-isoprene-styrene block copolymers (SIS), random styrenic copolymers, hydrogenated styrenic block copolymers, polyisobutylene, ethylene vinyl acetate (EVA) polymers, polyolefins, amorphous polyolefins, semi-crystalline polyolefins, alpha-polyolefins, reactor-ready polyolefins (reactor-ready polyolefins), acrylates, metallocene-catalyzed polyolefin polymers and elastomers, reactor-made thermoplastic polyolefin elastomers, olefin block copolymers, copolyester block copolymers, polyurethane block copolymers, polyamide block copolymers, thermoplastic polyolefins, thermoplastic vulcanizates, ethylene vinyl acetate copolymers, ethylene n-butyl acrylate copolymers, ethylene methyl acrylate copolymers, chloroprene rubber, acrylics, polyurethanes, polyacrylates and methacrylates, ethylene acrylic acid copolymers, polyetheretherketones, polyamides, atactic polypropylene, ethylene-propylene polymers, propylene-hexene polymers, ethylene-butene polymers, ethylene-octene polymers, propylene-butene polymers, propylene-octene polymers, metallocene-catalyzed polypropylene polymers, metallocene-catalyzed polyethylene polymers, ethylene-propylene-butene terpolymers, propylene, ethylene, C 4 -C 10Copolymers made from α-olefin monomers, polypropylene polymers, maleated polyolefins, polyester copolymers, copolyester polymers, ethylene acrylic acid copolymers and / or polyvinyl acetate, and / or wherein the polymers are modified and / or functionalized with one or more selected from hydroxyl groups, ethoxy groups, epoxy groups, siloxane groups, amine groups, amine siloxane groups, carboxyl groups, phthalocyanine groups and silane-sulfide groups, optionally at the polymer chain ends or in the side chain positions within the polymer.

[0141] In one embodiment, the rubber composition includes no more than 10 phr, or no more than 5 phr, or no more than 2 phr of polyisoprene elastomer (natural rubber and synthetic polyisoprene).

[0142] In one embodiment, PBD and SSBR are the only elastomers in the rubber composition, or together may comprise at least 95 phr or at least 98 phr of the elastomer.

[0143] c) Silica and other particulate fillers

[0144] The rubber composition comprises at least 100 phr, or at least 120 phr, or at least 130 phr, or at least 140 phr, or at least 150 phr, or up to 200 phr, or up to 180 phr, or up to 170 phr of silica filler, such as 150±10 or 155±10 phr.

[0145] Expressed in terms of the total amount of particulate filler, the silica may be present in the rubber composition in an amount of at least 90 phf, or at least 95 phf, or at most 100 phf, or at most 98 phf.

[0146] The term "silica" is used herein to refer to silicon dioxide SiO 2 (It may contain small amounts of impurities, typically less than 1% by weight, from the process of forming the silica.) The silica may be precipitated silica formed by digesting amorphous silica with sodium hydroxide to form sodium silicate and precipitating the silica from the sodium silicate by reaction with an acidifying agent such as sulfuric acid or carbon dioxide. The resulting precipitate is washed and filtered. Other methods of preparing particulate silica are described, for example, in U.S. Pat. Nos. 5,587,416 A, 5,708,069 A, 5,789,514 A, 5,800,608 A, 5,882,617 A and 9,359,215 B2 and U.S. Publication Nos. 20020081247 A1 and 20050032965 A1.

[0147] The surface area of ​​silicon dioxide can be measured by nitrogen adsorption according to ASTM D1993-18, "Standard Test Method for Precipitated Silica-Surface Area by Multipoint BET Nitrogen Adsorption", which is referred to herein as nitrogen surface area. The nitrogen surface area of ​​silicon dioxide can be at least 100 m 2 / g, or at least 110m 2 / g, or at least 120m 2 / g, or up to 400m 2 / g, or up to 300m 2 / g, or up to 240m 2 / g.

[0148] The surface area of ​​silica can also be measured by CTAB surface area according to ASTM D6845-20, "Standard Test Method for Silica, Precipitated, Hydrated-CTAB (Cetyltrimethylammonium Bromide) Surface Area". This test method covers the measurement of the specific surface area of ​​precipitated silica, excluding the area contained in the micropores that are too small to accommodate hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, commonly known as CTAB) molecules. The CTAB surface area tends to be slightly lower than the nitrogen surface area. Silica can have a surface area of ​​at least 90 m 2 / g, or at least 100m 2 / g, or up to 350m 2 / g, or up to 300m 2 / g, or up to 230m 2 / g CTAB specific surface area.

[0149] Exemplary precipitated silicas that may be used include Hi-Sil® from PPG Industries. TM 315G-D, Hi-Sil TM 532.Hi-Sil TM 532 EP and Hi-Sil TM EZ 160G; Hubersil from JMHuber TM4155; Zeosil from Solvay 115GR, 125GR, 165GR, 175GR, 185GR, 195GR, 1085GR, 1165MP, 1115MP, HRS 1200MP, Premium MP, Premium 200MP, Premium SW and 195HR TM ; Ultrasil from Evonik with the designations VN2, VN3, VN3GR, 5000GR, 7000GR, 9000GR TM ; Zeopol 8755LS and 8745 from Evonik TM ; Newsil 115GR and 2000MP from Wuxi Quechen Silicon Chemical Co. Ltd TM ; and Tokusil from Maruo Calcium Co., Ltd TM 315.

[0150] Other particulate fillers may also be used in the rubber composition, such as one or more of carbon black, alumina, aluminum hydroxide, clay (reinforcement grade), magnesium hydroxide, boron nitride, aluminum nitride, titanium dioxide, and combinations thereof. Such other particulate fillers may be present in a total amount of 1 to 30 phr, or up to 20 phr, or up to 10 phr, or up to 5 phr when used.

[0151] Carbon black, when used, may be present at up to 10 phr, or up to 5 phr, or at least 0.5 phr, and may have a surface area of ​​at least 8, or at least 20, or at least 100, or at least 120, or at most 132 m2 as measured according to ASTM D6556-21, "Standard Test Method for Carbon Black - Total and External Surface Area by Nitrogen Adsorption". 2 / kg specific surface area. The specific (external) surface area based on the statistical thickness method (STSA) is defined as the specific surface area accessible to the rubber. In one embodiment, no carbon black is present except for carbon black used in small amounts (e.g. less than 5 phr) as a carrier for one or more coupling agents.

[0152] Exemplary carbon blacks useful herein include those having ASTM designations N110, N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990, and N991 as specified in ASTM D1765-21, "Standard Classification System for Carbon Blacks Used in Rubber Products." These carbon blacks have an iodine absorption of 9 to 145 g / kg as determined according to ASTM D 1510-21 and an iodine absorption of 34 to 150 cm 3 / 100g of DBP absorption value determined according to ASTM D2414. For example, N234 grade has an iodine absorption of about 120g / kg, an iodine absorption of about 119m / kg, and an iodine absorption of about 120g / kg. 2 / kg CATB specific surface area and about 125m 2 / kg of DBP absorption of granular carbon black. N121 grade is about 121g / kg of iodine absorption, about 121m 2 / kg of CATB specific surface area, about 132m 2 / kg DBP absorption and less than 0.5% by weight of ash content of granular carbon black. N220 grade is 116-126g / kg iodine absorption, 106-116m 2 / kg CATB specific surface area, 109-119m 2 / kg of DBP absorption and less than 0.5% by weight of ash content of granular carbon black.

[0153] d) Organic silane coupling agent

[0154] The rubber composition includes one or more organosilane coupling agents, including a capped mercapto organosilane coupling agent and optionally one or more other sulfur-containing organosilane coupling agents. The organosilane coupling agent helps disperse the silica and bond the silica to the elastomer.

[0155] In one embodiment, the weight ratio of blocked mercapto organosilane coupling agent to all organosilane coupling agents is at least 0.7:1, or at least 0.8:1, or at least 0.9:1, or at most 1:1, or at most 0.95:1.

[0156] The blocked mercapto organosilane coupling agent is present in an amount of at least 6 parts by weight (phf), or at least 7phf, or at least 8phf, or at most 12phf, or at most 10phf per hundred parts of silica. When silica is present at 150 to 160phr, the blocked mercapto organosilane coupling agent may be present at 9 to 18phr, or for example 10 to 15phr.

[0157] Exemplary blocked mercaptosilanes include alkoxysilylalkylthio and alkylalkoxysilylalkylthio-acetates, -phosphonates, -phosphinates, -sulfates, -sulfonates, -alkanoates, -palmitates and -benzoates, and mixtures thereof. Examples of such blocked mercaptosilanes include 3-octanoylthio-1-propyltriethoxysilane (also known as 3-triethoxysilyl-1-propyl thiooctanoate), 2-triethoxysilyl-1-ethylthioacetate, 2-trimethoxysilyl-1-ethylthioacetate, 2-(methyldimethoxysilyl)-1-ethylthioacetate, 3-trimethoxysilyl-1-propylthioacetate, triethoxysilylmethylthioacetate, trimethoxysilylmethylthioacetate. Thioacetate, triisopropoxysilylmethylthioacetate, methyldiethoxysilylmethylthioacetate, methyldimethoxysilylmethylthioacetate, methyldiisopropoxysilylmethylthioacetate, dimethylethoxysilylmethylthioacetate, dimethylmethoxysilylmethylthioacetate, 1-(2-triethoxysilyl-1-ethyl)-4-thioacetylcyclohexane, 8-trimethoxysilyl-1-octylthioacetate and mixtures thereof.

[0158] In one embodiment, the blocked mercaptosilane has the general formula 4:

[0159] (R 16 O) d R 17 (3-d) -Si-ZSC(=O)-R 18

[0160] Formula 4,

[0161] in:

[0162] R 16 A hydrogen atom, a straight chain or a branched chain C 1 -C 18 Alkyl, C 3 -C 8 Cycloalkyl and C 6-C 10 Aryl;

[0163] R 17 Selected from linear or branched C 1 -C 18 Alkyl, C 3 -C 8 Cycloalkyl and C 6 -C 10 Aryl;

[0164] R 18 A hydrogen atom, a straight chain or a branched chain C 1 -C 18 Alkyl, C 3 -C 8 Cycloalkyl, C 6 -C 10 Aryl and straight-chain or branched C 2 -C 8 Alkoxyalkyl;

[0165] Z is for C 1 -C 18 divalent bonding groups; and

[0166] d is an integer equal to 1, 2 or 3.

[0167] Such blocked mercapto organosilane coupling agents are disclosed, for example, in U.S. Publication No. 20200325312 A1. Other blocked mercapto organosilane coupling agents are disclosed, for example, in U.S. Pat. No. 6,608,125 B2 and U.S. Publication No. 2006 / 0041063 A1.

[0168] An example of a suitable capped mercaptosilane is 3-octanoylthio-1-propyltriethoxysilane, which can be used as NXT TM The silanes were obtained from Momentive Performance Materials Inc., Albany, NY. Such coupling agents also provide improved wet performance to tires.

[0169] Examples of polysulfide-containing organosilane coupling agents that may be present in a smaller amount include those containing groups such as alkyl, alkoxy, amino, vinyl, epoxy, and combinations thereof (e.g., disulfide alkoxy-containing organosilane coupling agents, tetrasulfide alkoxy-containing organosilane coupling agents).

[0170] Exemplary polysulfide organosilane coupling agents containing alkoxy groups include bis(trialkoxysilylorganyl)polysulfides, such as bis(trialkoxysilylorganyl)disulfide and bis(trialkoxysilylorganyl)tetrasulfide. Exemplary bis-(3-triethoxysilylpropyl)polysulfides may have an average of 2 to 2.6 or 3.5 to 4 linked sulfur atoms in the polysulfide bridge. An exemplary bis-(3-triethoxysilylpropyl)disulfide has an average of 2.15 linked sulfur atoms in the polysulfide bridge and is Si266 TM Obtained from Evonik Industries. Bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) supported on carbon black can be used as Obtained from Evonik.

[0171] Such one or more bis(trialkoxysilylorganyl)polysulfides may be present in the rubber composition in an amount of at least 0.5 phf, or at most 3 phf, or at least 0.3 phr, or at most 4 phr.

[0172] In one embodiment, such one or more bis(trialkoxysilylorganyl)polysulfides are used only in the productive mixing step, ie, during or after the addition of the sulfur curing agent.

[0173] In one embodiment, one or more organosilane coupling agents are added to the rubber composition in the form of pretreated silica. The pretreated silica can be silica that has been surface-pretreated with an organosilane before being added to the rubber composition. The use of pretreated silica can allow two ingredients (i.e., silica and silica coupling agent) to be added as one ingredient, which generally tends to make rubber compounding easier and can also reduce the amount of required organosilane coupling agent. In another embodiment, one or more organosilane coupling agents are added to the rubber composition alone.

[0174] e) Resin component

[0175] The resin component of the rubber composition includes at least 40 phr of a hydrocarbon traction resin, at least 5 phr of a tackifying resin and optional rosin. The tackifying resin may include a substituted or unsubstituted phenolic resin, such as a phenol formaldehyde resin. Other resins may also be present in the resin component. In one embodiment, one or more of the resins are at least partially hydrogenated.

[0176] Unlike oils, which are liquid at room temperature (20-25° C.), resins are generally solid or highly viscous at room temperature. For example, the resin may have a Tg of at least 30° C., or at least 40° C., or at least 50° C., or at most 70° C., or at most 60° C., as determined using DSC according to ASTM D6604.

[0177] The weight ratio of traction resin to tackifying resin may be at least 3:1, or at least 4:1, or at least 5:1, or at most 20:1, or at most 10:1, or at most 8:1, or at most 7:1.

[0178] i) Hydrocarbon traction resins

[0179] Exemplary rubber compositions include at least 40 phr, or at least 50 phr, or at least 55 phr, or up to 80 phr, or up to 75 phr, or up to 70 phr of a hydrocarbon traction resin, such as 63 ± 5 phr. Exemplary traction resins help improve / maintain the wet traction of the tire, which can be estimated, for example, by percent rebound or tan delta value at about 0°C.

[0180] The hydrocarbon traction resin may have a softening point of at least 70°C, or at least 80°C, or at most 120°C, or at most 110°C, as determined according to ASTM E28. The Tg is generally lower than its softening point, and the lower the Tg, the lower the softening point. The hydrocarbon traction resin may have a Tg of at least 45°C, or at least 50°C, or at most 65°C, or at most 60°C, as determined using DSC according to ASTM D6604.

[0181] Petroleum-based resins suitable as traction resins include aromatic and non-aromatic resins. Examples of aromatic resins include aromatic homopolymer resins and aromatic copolymer resins. Aromatic copolymer resins refer to hydrocarbon resins comprising a combination of one or more aromatic monomers and one or more other (non-aromatic) monomers, wherein a majority of all monomers by weight are typically aromatic. The aromatic resin may have a Mw of at least 500 g / mole, or at least 650 g / mole, and / or at most 2000 g / mole, or at most 1000 g / mole.

[0182] The hydrocarbon traction resin may be selected from C5 resins, including polydicyclopentadiene (DCPD) and its hydrogenated equivalents, such as HC5 resins and hydrogenated DCPD resins (HDCPD); C9 resins, and their hydrogenated equivalents, such as HC9 resins; and copolymers and mixtures thereof, such as C5 / C9 resins, including DCPD / C9 resins, HDCPD / C9 resins, and mixtures thereof. In the abbreviations, H indicates that the resin is at least partially hydrogenated, and C5 and C9 indicate the number of carbon atoms in the monomers forming the resin prior to any dimerization or functionalization. Other hydrocarbon traction resins that may be used include terpene-phenol resins, terpene resins, terpene-styrene resins, styrene / α-methylstyrene resins, and coumarone-indene resins.

[0183] C5 resins are derived from aliphatic monomers having an average of 5 carbon atoms, such as one or more of cyclopentene, 1,3-pentadiene (e.g., cis or trans), 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene (a dimer of cyclopentadiene), and dienes such as isoprene and piperylene. C9 resins are derived from aromatic olefins having an average of 9 carbon atoms and may include one or more of vinyl toluene, methyl styrene such as α-methyl styrene, β-methyl styrene, m-methyl styrene, p-methyl styrene, indene, methyl indene, styrene, p-(tert-butyl) styrene, methoxy styrene, chlorostyrene, hydroxy styrene, vinyl mesitylene, divinyl benzene, vinyl naphthalene, xylene, alkyl substituted derivatives thereof, and mixtures thereof.

[0184] The resin may be formed from a mixture of the above C5 and C9 monomers (C5 / C9 copolymer resin). In one embodiment, the C5 fraction for the C5 / C9 resin is primarily dicyclopentadiene (DCPD), and the C9 fraction is primarily composed of styrenics such as styrene, α-methylstyrene, and β-methylstyrene.

[0185] In one embodiment, the hydrocarbon pulling resin is functionalized and / or partially hydrogenated.

[0186] A C5 / C9 resin, such as a DCPD / C9 or HDCPD / C9 resin, may have at least 5 mol%, or at least 8 mol%, or at most 25 mol%, or at most 20 mol%, or at most 15 mol% of 1 The aromatic hydrogen content as determined by H NMR, with the balance being aliphatic hydrogen content. The C5 / C9 resin may have an aromatic monomer content of at least 5 wt%, or at least 8 wt%, or up to 12 wt%, or 10±2 wt%.

[0187] Exemplary C5 / C9 resins may have a glass transition temperature Tg of greater than 40° C., or at least 50° C., or up to 70° C., such as 55±5° C., as measured using DSC according to ASTM D6604. The C5 / C9 resin may have a softening point of at least 80° C., or at least 90° C., or up to 120° C., or up to 110° C. as measured by ASTM E28 (ring and ball softening point). The C5 / C9 resin may have a melt viscosity at 160° C. of 300 to 800 centipoise (cPs), or 350 to 650 cPs, or 375 to 615 cPs, or 475 to 600 cPs, as measured by a Brookfield viscometer with a “J” type spindle according to ASTM D6267.

[0188] The C5 / C9 resin may have a weight average molecular weight (Mw) of at least 500 g / mole, or at least 600 g / mole, or at least 700 g / mole, or up to 1000 g / mole, or up to 900 g / mole, or up to 800 g / mole as determined by gel permeation chromatography (GPC). The C5 / C9 resin may have a number average molecular weight (Mn) of at least 350 g / mole, or at least 400 g / mole, or at least 450 g / mole, or up to 600 g / mole as determined by gel permeation chromatography (GPC). In one embodiment, the C5 / C9 resin has a polydispersity index ("PDI", PDI = Mw / Mn) of 4 or less, e.g., 1.3:1 to 3.1.

[0189] In one embodiment, the traction resin is or includes hydrogenated dicyclopentadiene (HDCPD) / C9 resin.

[0190] In one embodiment, the C5 / C9 resin is substantially free of (eg, contains no more than 5 wt % or no more than 2 wt %) isoprene.

[0191] In one embodiment, the C5 / C9 resin is substantially free of (eg, contains no more than 5 wt. % or no more than 2 wt. %) pentene.

[0192] The C5 / C9 resin may include less than 15% indene components, or less than 10% by weight, or less than 5% by weight, or less than 2% by weight of indene components. The indene components include indene and indene derivatives.

[0193] A suitable HDCPD / C9 resin can be used as OPPERA TM PR 383 is available from Exxonmobil. This resin has an aromatic hydrogen content of about 10 mol %, an aliphatic hydrogen content of about 89 mol %; a softening point (ring and ball) of about 103°C; a Tg of 55°C; an Mn of 480 g / mol; and an Mw of 770 g / mol. Another suitable C5 / C9 copolymer resin is available as OPPERA TM PR373 is available from ExxonMobil and has a Tg of 47°C. Other exemplary OPPERA TM Hydrocarbon resins including OPPERA TM PR 100A、OPPERA TM PR 100N、OPPERA TM PR 120, OPPERA TM PR140 and OPPERA TM PR395.

[0194] Additional hydrocarbon-based tackifying resins are described in U.S. Publication No. 20210032442 A1. U.S. Patent No. 11,214,667 B2 describes modified hydrocarbon thermoplastic resins for rubber compositions.

[0195] ii) Tackifying resin

[0196] The tackifying resin may be present in the rubber composition in an amount of at least 5 phr, or at least 7 phr, or at most 15 phr, or at most 12 phr, such as 10 ± 2 phr.

[0197] Exemplary tackifying resins include substituted and unsubstituted phenolic resins, such as phenolic resins, alkylphenolic resins, and mixtures thereof. These are condensation resins obtained by reacting phenol or a substituted phenol (such as an alkylphenol) with an aldehyde (such as formaldehyde, acetaldehyde, or furfural) in the presence of an acid or base catalyst. Examples of alkylphenols for alkylphenolic resins include cresol, xylenol, tert-butylphenol, octylphenol, and nonylphenol.

[0198] Exemplary substituted and unsubstituted phenolic resins, such as alkylphenolic resins, may have a softening point (Ring and Ball method) of at least 80 °C, or at most 160 °C, or at most 120 °C.

[0199] One or more substituted or unsubstituted phenolic resins (such as alkylphenolic resins) may be present in the rubber composition in an amount of at least 5 phr, or at least 7 phr, or at most 15 phr, or at most 12 phr (such as 10 ± 2 phr).

[0200] A suitable alkylphenol formaldehyde resin has a softening point (Ring and Ball method) of about 90 °C and is available from SI Group as SP-1068 TM obtained.

[0201] Other tackifying resins include alkylphenol-alkyne condensation resins obtained by the reaction of an alkylphenol with an alkyne such as acetylene; and modified alkylphenolic resins obtained by modifying the aforementioned resins with compounds such as cashew nut oil, tall oil, linseed oil, various animal or vegetable oils, unsaturated fatty acids, rosin, alkylbenzene resins, aniline, or melamine.

[0202] iii) Other resins

[0203] Other resins suitable for use in rubber compositions (generally referred to herein as "rosins") are derived from naturally occurring rosins and derivatives thereof, including, for example, gum rosin, wood rosin, and tall oil rosin. Gum rosin, wood rosin, and tall oil rosin have similar compositions, although the amounts of the components of the rosin may vary. Such resins may be dimerized, polymerized, or disproportionated. Such resins may be in the form of esters of rosin acid and a polyol such as pentaerythritol or (ethylene) glycol. In one embodiment, the tackifying resin is or includes a modified gum rosin.

[0204] Rosin (ie, a resin derived from naturally occurring rosin and / or its derivatives) may be present in the rubber composition in an amount of 0 to 5 phr, or at least 1 phr, or up to 3 phr, or up to 2 phr. In one embodiment, no rosin is used.

[0205] In addition to the exemplary traction resins and tackifying resins, other exemplary resins useful in the rubber composition include non-reactive phenol formaldehyde resins, resorcinol resins, hexamethylenetetramine resins, and benzoxazine resins, which, when present, may be used in a total amount of 1 to 5 phr, or up to 3 phr.

[0206] f) Liquid plasticizer

[0207] Exemplary rubber compositions may include one or more liquid plasticizers. These are processing aids that are liquid at room temperature (i.e., liquid at 25°C and above), and are therefore distinguished from hydrocarbon resins that are generally solid at room temperature. Liquid plasticizers may have a Tg below 0°C, typically well below 0°C, such as below -30°C, or below -40°C, or below -50°C, such as a Tg of 0°C to -100°C.

[0208] Suitable liquid plasticizers include oils (e.g., petroleum oils and oils of plant origin) and other non-oil liquid plasticizers, such as ether plasticizers, ester plasticizers, phosphate / salt plasticizers and sulfonate / salt plasticizers. Liquid plasticizers can be added during compounding, or added later as extender oils (which are used to extend rubber). Petroleum-based oils can include aromatic oils, naphthenic oils, low polycyclic aromatic hydrocarbons (PCA) oils such as MES, TDAE and SRAE and mixtures thereof. Vegetable oils can include oils harvested from vegetables, nuts, seeds, and mixtures thereof, such as triglycerides. Some representative examples of vegetable oils that can be used include soybean oil, sunflower oil, rapeseed oil (canola (rapeseed) oil), corn oil, coconut oil, cottonseed oil, olive oil, palm oil, peanut oil and safflower oil. In one embodiment, vegetable oils include sunflower oil or consist of sunflower oil.

[0209] The liquid plasticizer may be used in the rubber composition at 0 to 10 phr, or at least 0.5 phr, or at least 1 phr, or at least 2 phr, or at least 4 phr, or at most 8 phr, or at most 7 phr, such as 6±2 phr.

[0210] g) Wax

[0211] The rubber composition may include one or more waxes, for example selected from paraffin waxes, microcrystalline waxes and mixtures thereof, which may be of the type described in The Vanderbilt Rubber Handbook (1978), pages 346 and 347. Such waxes may act as antiozonants.

[0212] When used, waxes may be used at 1-5 phr, or up to 3 phr.

[0213] Other processing aids may also be used in the rubber composition. For example, compounds of fatty acids and amino acid derivatives may be used as Obtained from Schill & Seilacher, as HT 257. Such compounds can be used in rubber compositions at 1 to 5 phr and are beneficial in reducing silica agglomeration at high silica loadings.

[0214] h) Curing package

[0215] The curing package comprises i) a sulfur-based curing (vulcanizing) agent, ii) zinc oxide, iii) a curing accelerator, and optionally, one or more of an organic curing activator and a curing inhibitor. The curing package can be used in the rubber composition at 0.5 to 20 phr, or at least 5 phr, or at most 12 phr.

[0216] i) Sulfur-based curing agents

[0217] Examples of suitable sulfur-based curing agents include elemental sulfur (free sulfur), insoluble polymeric sulfur, soluble sulfur, and sulfur donating vulcanizing agents such as amine disulfides, polymeric polysulfides or sulfur olefin adducts, and mixtures thereof.

[0218] Sulfur-based curing agents may be used in amounts of 0.1 to 10 phr, such as at least 0.4 phr, or at least 1 phr, or at most 5 phr, or at most 2 phr (expressed as the amount of sulfur).

[0219] ii) Cure accelerators, cure activators, free radical initiators, and inhibitors

[0220] Cure accelerators and activators act as catalysts for the vulcanizing agent.

[0221] Curing activator is an additive for supporting vulcanization. Curing activator includes inorganic and organic curing activators. Zinc oxide is the most widely used inorganic curing activator, and it can be present with 1phr to 10phr, for example at least 1.5phr, or at least 2phr, or at most 7phr, or at most 5phr, or at most 4phr.

[0222] Organic curing activators include stearic acid, palmitic acid, lauric acid, zinc salts of each of the foregoing, and thiourea compounds, such as thiourea, and dialkylthioureas such as dialkylthioureas and diarylthioureas, and mixtures thereof. Specific thiourea compounds include N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea (DEU), N,N'-dimethylthiourea, N,N'-dibutylthiourea, ethylenethiourea, N,N'-diisopropylthiourea, N,N'-dicyclohexylthiourea, 1,3-di(o-tolyl)thiourea, 1,3-di(p-tolyl)thiourea, 1,1-diphenyl-2-thiourea, 2,5-dithiodiurea, guanylthiourea, 1-(1-naphthyl)-2-thiourea, 1-phenyl-2-thiourea, p-tolylthiourea, and o-tolylthiourea.

[0223] The total amount of one or more organic curing activators (such as a mixture of fatty acids) may be from 0.1 to 6 phr, such as at least 0.5 phr, or at least 1 phr, or at most 4 phr, or at most 3 phr.

[0224] Curing accelerator is used to control the time and / or temperature required for vulcanization, and improves the property of vulcanized rubber. In one embodiment, a single accelerator system, i.e. a primary accelerator, can be used. The primary accelerator can be used with an amount of 0.5 to 5phr. In another embodiment, a combination of two or more accelerators can be used. In order to activate and improve the property of vulcanized rubber, an auxiliary accelerator is used with less amount usually. The combination of such accelerators known in history produces the synergistic effect of the final properties of the rubber of sulfur-curing, and is usually better than those produced by using any accelerator alone to a certain extent. In addition, a delayed action accelerator can be used, which is less affected by the normal processing temperature, but produces satisfactory curing under common vulcanization temperature.

[0225] Representative examples of accelerators include amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. In one embodiment, the primary accelerator is a sulfenamide, such as N-cyclohexylbenzothiazole-2-sulfenamide (CBS) or N-tert-butyl-2-benzothiazole-sulfenamide (TBBS). If a secondary accelerator is used, it can be a guanidine such as N,N'-diphenylguanidine (DPG), a dithiocarbamate or a thiuram compound, although a secondary sulfonamide accelerator can be used.

[0226] Examples of the thiazole curing accelerator include 2-mercaptobenzothiazole, 2,2'-dithiobis(benzothiazole) (MBTS).

[0227] Cure accelerators with fast cure onset times, typically less than 3 minutes, are referred to as super accelerators. Exemplary super accelerators that can be used alone or in combination with other accelerators include 1,6-bis(N,N′-dibenzylthiocarbamoyldisulfide)hexane (BDBZTH), tetrabenzylthiuram disulfide (TBzTD), tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetraisobutylthiuram disulfide (TiBTD), dipentamethylenethiuram tetrasulfide (DPTT), zinc dibutyldithiocarbamate (ZDBC), zinc dibenzyldithiocarbamate (ZBED), zinc dibenzyldithiocarbamate (ZBEC), and mixtures thereof.

[0228] The total amount of one or more cure accelerators may be from 0.1 to 10 phr, or at least 0.5 phr, or at least 2 phr, or at least 4 phr, or up to 8 phr.

[0229] The free radical initiator that can be used for some embodiments is sometimes referred to as a redox initiator, and includes a combination of chelated iron salts, sodium formaldehyde sulfoxylate and an organic hydroperoxide. Representative organic hydroperoxides include cumene hydroperoxide, p-menthene hydroperoxide and tert-butyl hydroperoxide. The free radical initiator can be used in combination with a sulfur-based vulcanizing agent, or as a substitute for a sulfur-based vulcanizing agent. When used, the amount of the free radical initiator can be 0.1 to 4phr, or 0.5 to 2phr. In other embodiments, there is no free radical initiator in the rubber composition.

[0230] Cure inhibitors are used to control the vulcanization process and usually delay or inhibit vulcanization until the required time and / or temperature is reached. Exemplary cure inhibitors include cyclohexylthiophthalimide. If used, the amount of the cure inhibitor can be 0.1 to 3 phr, or 0.5 to 2 phr. In one embodiment, no cure inhibitor is used.

[0231] The rubber composition may further include other components such as a colorant, an antioxidant, an antidegradant, an antiozonant, and a peptizing agent.

[0232] Exemplary amounts of antioxidants, antidegradants, antiozonants (except waxes acting as antiozonants) are 0.1 to 5 phr, such as at least 0.3 phr, or up to 2 phr. Representative antioxidants include aryl p-phenylenediamines, such as diphenyl p-phenylenediamine and alkylaryl p-phenylenediamines, such as N-(1,3-dimethylbutyl)-N'-phenyl p-phenylenediamine, etc., such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 to 346.

[0233] B Preparation of rubber composition

[0234] In another embodiment, a method of preparing a vulcanizable rubber composition includes combining the above-described components, such as in two or more mixing steps, to form the vulcanizable rubber composition.

[0235] In another embodiment, a method of forming a tread for a pneumatic tire includes combining the above-described components to form a vulcanizable rubber composition, and curing the vulcanizable rubber composition to form the tread.

[0236] The rubber composition can be prepared by mixing the vulcanizable elastomer, silica and other rubber compounding ingredients, excluding the curing agent, to an elevated temperature in at least one continuous mixing stage (commonly referred to as one or more "non-productive" mixing stages) using at least one mechanical mixer under high shear rubber mixing conditions, followed by a final "productive" mixing stage, wherein a sulfur-based curing package (such as a sulfur-based curing agent and one or more curing accelerators) is added to the mixture and mixed at a lower mixing temperature to avoid unnecessary pre-curing of the rubber mixture during the productive mixing stage. The ingredients can be mixed in one or more non-productive mixing stages to a temperature of 130° C. to 200° C., such as about 160° C., which is maintained for 1-2 minutes. Once the curing package (or at least the curing agent) is added, the subsequent productive mixing step can be carried out at a temperature below the vulcanization (curing) temperature and / or for a short time to avoid unwanted pre-curing of the rubber composition, such as not more than 120° C., such as at least 40° C., or at least 60° C., such as at a temperature of 110-115° C. for 1-2 minutes. Mixing can be carried out, for example, by kneading the ingredients together in a Banbury mixer or on a milled roll. Between each mixing stage, the rubber composition can be cooled to a temperature below 40° C. For example, the rubber composition can be dumped from the mixer after each mixing step, sheeted out from an open mill or sheeted through a roller die and cooled to below 40° C. after each mixing step.

[0237] When the curing package is fully mixed, the rubber composition can be molded or otherwise formed into the shape of the green component of the tire, such as the tire tread. The temperature of the green component can be raised to achieve curing. The curing of the pneumatic tire or its parts can be carried out at a temperature of 120°C to 200°C, for example, at least 140°C or at most 180°C or about 150°C for at least 10 minutes. Any conventional vulcanization method can be used, such as heating in a press or mold, or heating with superheated steam or hot air. Such tires can be constructed, shaped, molded and cured by various known methods, and it is obvious to those skilled in the art.

[0238] The use of high loadings of silica filler may optionally require a separate re-mill stage to separately add a portion or all of such filler. This stage is typically conducted at temperatures similar to, although usually slightly lower than, those employed in other productive mixing stages, e.g., from 90°C to 150°C.

[0239] In another embodiment, a tire is provided having a tread formed at least in part from an exemplary rubber composition. Other components of the tire, such as the tire sidewall, may additionally or alternatively be formed at least in part from a rubber composition as described herein. The tire may be a pneumatic tire for a road vehicle (such as a bus or truck) or an automobile, or a tire for an off-road vehicle, an aircraft, or the like.

[0240] The rubber composition is not limited to use in tires, but can be applied to rubber gloves, surgical instruments, etc.

[0241] Exemplary Rubber Compositions

[0242] Table 1 shows exemplary rubber compositions according to aspects of the exemplary embodiments.

[0243] Table 1: Exemplary Rubber Compositions

[0244]

[0245] In a tire, use of the exemplary rubber composition, such as in a tire tread, can produce a tire having improved or desirable tread properties. These improved or desirable properties can include improved wet performance without a significant loss of snow performance.

[0246] Without intending to limit the scope of the exemplary embodiments, the following examples illustrate the preparation of exemplary rubber compositions and their properties.

[0247] Example

[0248] Rubber compositions AG were formulated using the ingredients listed in Table 2. All compositions used a mixture of low Tg, low styrene SSBR and PBD as the elastomer, with Examples E to G using a slightly lower ratio of SSBR to PBD than Examples A to D.

[0249] Example A is a control for Example B. Example B is a negative example, in which only one element of the combination of the present invention, the formaldehyde-phenol tackifying resin, is shown, and thus shows poor RR&Snow index.

[0250] Example C is the same as Control A, but uses slightly more processing aid. Example C also serves as a reference for Example F. Example D is a modified C with increased silica and silane, and serves as a reference for Examples E and F.

[0251] Example E is a negative example, showing only one element (blocked mercaptosilane) of the inventive combination (tackifying resin + blocked mercaptosilane), and it only leads to an improvement in the RR index. Example F shows the inventive combination (tackifying resin + blocked mercaptosilane), which leads to an improvement in the wet and RR indexes while maintaining the snow index. Example G shows the inventive combination, and compared to the reference example D, it produces an improved wet and RR index while maintaining the snow index.

[0252] The rubber composition is prepared as follows: in the first non-productive step (NP1), all ingredients except sulfur, zinc oxide, accelerator, antidegradant / antioxidant and tetrasulfide coupling agent are combined in a laboratory-scale mixer and mixed until the temperature reaches about 160°C for 1-2 minutes. The mixture is poured out from the mixer and allowed to cool. A further non-productive mixing step (NP2) is carried out to ensure the full mixing of the ingredients. Subsequently, in the productive mixing step (PR), the remaining ingredients are added and mixing is continued until the temperature reaches about 115°C, and then the vulcanizable composition is cured at about 170°C and formed into strips suitable for testing.

[0253] Table 2: Composition of rubber composition (in phr)

[0254]

[0255] 1 Solution polymerized, Li-catalyzed styrene butadiene rubber; 5 wt% styrene; aminosilicone multifunctional; 11 wt% vinyl in polymer; 3.8 wt% oil-extended (reported separately); Mooney viscosity of 90 (ML1+4 at 100°C); Tg of -85°C; as M0511 TM Available from LG Chemicals.

[0256] 2Solution polymerized high cis-1,4 polybutadiene stabilized with a non-staining antioxidant; made using a stereoregular neodymium catalyst that controls molecular weight distribution and provides a highly linear polymer weight distribution and provides a highly linear polymer; Mooney viscosity of 55 (ML1+4 at 100°C); Tg of -106°C; onset Tg of -110°C; cis-1,4 butadiene content, 96-97 wt%; volatiles, up to 0.5 wt%; specific gravity 0.91; as 1223 obtained from The Goodyear Tire and Rubber Company.

[0257] 3 With about 125m 2 / g BET nitrogen surface area; about 115m 2 / g of CTAB surface area of ​​precipitated silica; as Hi-Sil TM 315G-D was obtained from PPG.

[0258] 4 3-Octanoylthio-1-propyltriethoxysilane, as NXT TM Silanes were obtained from Momentive Performance Materials.

[0259] 5 Bis-(3-triethoxysilylpropyl) disulfide with an average of 2.15 connected sulfur atoms in the polysulfide bridge as Si266 TM Obtained from Evonik Industries.

[0260] 6 Hydrogenated dicyclopentadiene (HDCPD) / C9 resin; 10 wt% aromatic; 89 wt% aliphatic; softening point (ring and ball method), about 103°C; Tg, 55°C; Mn 480 g / mol; Mw 770 g / mol; as Oppera TM PR 383 was obtained from ExxonMobil.

[0261] 7 Alkylphenol formaldehyde tackifying resin, having a softening point (ring and ball method) of about 90°C; available from SI Group as SP-1068 TM get..

[0262] 8 WW grade gum rosin (rosin); softening point of about 85°C (ring and ball method); available from AV Pound & Co. Ltd.

[0263] 9 Vegetable oil.

[0264] The rubber composition was molded into samples of appropriate size and subjected to various tests. Table 3 shows the test results for predicting snow performance, rolling resistance, and wet performance.

[0265] Table 3: Performance prediction test

[0266]

[0267] A The rebound at 0° C. was determined using a Zwick rebound tester on samples that had been cured for 10 minutes at 170° C. Lower results were considered an indicator of better wet traction performance.

[0268] B The rebound at 100° C. was determined using a Zwick rebound tester on samples which had been cured for 10 minutes at 170° C. A higher result was considered an indication of better (lower) rolling resistance.

[0269] C Storage modulus G' at -30 °C using a frequency of 7.8 Hz and a strain of 1.5% for samples cured at 170 °C for 10 min with Metravib TM It is measured by the Dynamic Mechanical Analyzer provided by XT-M Instruments and is an indicator of performance in the snow (lower is better).

[0270] The results show that the combination of a blocked mercapto organosilane coupling agent with a hydrocarbon traction resin and 10 phr of an alkylphenol formaldehyde tackifying resin in Examples F and G, in a highly silica-filled winter / all season tread formulation containing a low Tg functionalized SSBR polymer, results in improved wet traction performance (represented by rebound at 0°C) and lower rolling resistance (represented by rebound at 100°C) at maintained snow performance (represented by G' at -30°C) compared to similar compositions. For example, Example F can be compared to Example C, which uses a disulfide organosilane coupling agent and no alkylphenol formaldehyde tackifying resin, or Example G can be compared to Example D.

[0271] Other comparisons can be made. For example, it can be seen that, when compared to Example A, replacing the rosin tackifying resin and part of the hydrocarbon traction resin with 9 phr of alkylphenol formaldehyde tackifying resin at a silica level of 150 phr (Example B) results in a deterioration in rolling resistance and snow indicators. Compared to Example C, the combination of a blocked mercapto organosilane coupling agent with an alkylphenol formaldehyde tackifying resin and 150 phr silica (Example F) produces improved wet and rolling resistance indicators at a maintained snow indicator level. Compared to Example D, using a blocked mercapto organosilane coupling agent to replace a disulfide organosilane coupling agent (Example E) at 165 phr silica produces improved rolling resistance indicators at a maintained wet and snow indicator level. Compared to Example D, the combination of a blocked mercapto organosilane coupling agent with an alkylphenol formaldehyde tackifying resin (Example G) at 165 phr silica also produces improved wet and rolling resistance indicators at a maintained snow indicator.

[0272] Each document mentioned above is incorporated herein by reference. Unless otherwise specified in the context, singular forms, such as "one / kind" and "one / kind" are intended to cover plural forms. Except in the embodiments or otherwise indicated, all numerical values ​​of the amount of material, reaction conditions, molecular weight, carbon number, etc. specified in this specification should be understood to be modified by the word "about". Unless otherwise specified, each chemical or composition mentioned herein should be interpreted as a commercial grade material, which may contain isomers, by-products, derivatives and other such materials generally understood to be present in the commercial grade. However, unless otherwise specified, the amount of each chemical component stated does not include any solvent or diluent oil that may be conventionally present in commercial materials. It is to be understood that the upper and lower limits, ranges and ratio limits listed herein can be independently combined. Similarly, the scope and amount of each element of the present invention can be used together with the scope or amount of any other element.

[0273] It will be appreciated that variations of the features and functions disclosed above and other or their alternatives may be combined into many other different systems or applications. Those skilled in the art may subsequently make various currently unforeseeable or unexpected alternatives, modifications, changes or improvements, which are also intended to be covered by the following claims.

Claims

1. A vulcanizable rubber composition comprising: 80-100 parts per hundred parts of rubber (phr) of a polydiene component, the polydiene component comprising: 60-100 phr of a solution polymerized styrene-butadiene rubber having a styrene content of 2-10 wt% and a Tg of -95°C to -75°C, and 0-40phr polybutadiene rubber; At least 100 phr of silica filler; at least 6 parts by weight (phf) of a blocked mercapto organosilane coupling agent per hundred parts of silica filler; and at least 40 phr of a hydrocarbon traction resin; At least 5 phr of a substituted or unsubstituted phenolic resin; and Curing package.

2. The vulcanizable rubber composition according to claim 1, wherein the solution polymerized styrene butadiene rubber is present at 70-90 phr, and / or wherein the polybutadiene rubber is present at 10-30 phr.

3. The vulcanizable rubber composition according to claim 1, wherein the weight ratio of the solution-polymerized styrene butadiene rubber to the polybutadiene rubber is 2.5:1 to 5:

1.

4. The vulcanizable rubber composition of claim 1, wherein the solution polymerized styrene butadiene rubber has a styrene content of not more than 8 weight percent.

5. The vulcanizable rubber composition of claim 1 wherein the solution polymerized styrene butadiene rubber is functionalized with an aminosilane.

6. The vulcanizable rubber composition according to claim 5, wherein the aminosilane comprises an alkoxyaminosilane.

7. A tire tread formed from the rubber composition of claim 1.

8. A tire comprising the tread of claim 7.

9. A method of forming a tire tread, comprising: mixing together 80-100 parts per hundred parts of rubber (phr) of a polydiene component comprising 60-100 phr of a solution polymerized styrene butadiene rubber having a styrene content of 2-10 wt. % and a Tg of -95°C to -75°C, and 0-40 phr of a polybutadiene rubber; at least 100 phr of silica; at least 6 parts by weight (phf) of a blocked mercapto organosilane coupling agent per hundred parts of silica; at least 40 phr of a hydrocarbon traction resin; at least 5 phr of a substituted or unsubstituted phenolic resin; and a cure package comprising a sulfur-based curing agent, zinc oxide, and a cure accelerator to form a vulcanizable rubber composition; and The vulcanizable rubber composition is cured to form the tire tread.

10. A vulcanizable rubber composition comprising: 70-85 phr of a solution-polymerized styrene butadiene rubber having a styrene content of 2-10 wt. % and a cis-1,4-butadiene content of less than 45; 15-30phr of polybutadiene rubber; 140-170 phr of silica filler; 8-15 phr of a blocked mercapto organosilane coupling agent; 50-70 phr of hydrocarbon traction resin; 8-12 phr of a substituted or unsubstituted phenolic resin; and A cure package comprising a sulfur based curing agent, zinc oxide, and a cure accelerator.

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