Coating composition

Abstract

The invention discloses a coating composition. Rubber compositions contain at least one elastomer comprising at least one conjugated diene elastomer, pre-silylated precipitated silica, high surface area (e.g., CTAB surface area of at least 200 m2 / g) silica, a tear strength agent, a sulfur-based curing agent, and an accelerator for the curing agent. The rubber composition can be used to form a tire.

Description

Technical Field

[0001] The present application relates to a ply of a tire formed by coating a plurality of cords with a rubber composition and curing the rubber composition; a method of forming a cord-reinforced rubber assembly; a cord-reinforced rubber assembly for a tire; and a rubber composition. Background Art

[0002] The present disclosure relates to rubber compositions and, in particular, to compositions suitable for use as coatings for cords / wires in the ply of a tire, such as a carcass ply, a tire belt ply, a tire overlay ply, or a ply strip.

[0003] To provide increased strength, tires typically contain reinforcing materials in the form of metal or fabric cords. Each cord may consist of one or more wires. The cords are typically encapsulated in a rubber material to form a ply. Each ply may incorporate a plurality of cords that generally extend parallel to one another. To provide good tire properties such as low rolling resistance, it is desirable to provide a tire that includes an internal component and a ply of a reinforcing rubber composite having low hysteresis (e.g., as determined by measurement using tangent δ (tanΔ)) while maintaining other desirable properties. For example, in the case where the ply is for a tire carcass, it is desirable to optimize elongation properties, high wire cord adhesion, and low hysteresis.

[0004] To modify tire properties, coating compositions containing natural rubber and reinforcing materials such as carbon black and particulate fillers have been developed for forming plies. Coupling agents may be incorporated into the cord-reinforced rubber composition to couple fillers such as silica to natural rubber, for example as described in U.S. Publication No. 20060169382A1. The rubber composition also includes a resinous reaction product of hexamethoxymethylmelamine and a methylene acceptor compound and also includes a cobalt salt. U.S. Publication No. 20090151838A1 describes the use of a resin that is a reaction product of hexamethoxymethylmelamine formed in situ in the rubber composition with a methylene acceptor (phenolic resin or resorcinol). While the addition of such resin systems can result in improved stiffness and / or adhesion properties, it also has some disadvantages, such as a more complex mixing process.

[0005] As described in U.S. Patent No. 11,441,019, the precipitated silica used in the coating composition can be pre-silanized. The ply-coated rubber composition also contains a cobalt salt and optionally a resin and / or an oil.

[0006] Carbon black is commonly used in coating compositions, for example, in place of silica. U.S. Patent No. 6,220,326 B1 describes a tire including a carcass ply comprising a cord-reinforced rubber composition formed without silica, including natural rubber, cis-1,4-polybutadiene rubber, and optionally up to 10 phr of another rubber; carbon black having specific properties; and natural rosin acid. U.S. Patent No. 10,072,154 describes carbon black products and their components for use in elastomeric compositions for tires, which include aggregates of carbon black having specific properties intermediate those of some existing grades. The products exhibit low rolling resistance and low heat build-up under service conditions when incorporated into rubber compositions for tires.

[0007] A problem with many existing coating formulations is that they cannot improve elongation and wire adhesion properties without sacrificing other properties such as hysteresis and stiffness, and vice versa. SUMMARY OF THE INVENTION

[0008] In some embodiments, a rubber composition is disclosed that contains: 100 phr of an elastomer, the elastomer including 60 - 100 phr of a conjugated diene elastomer; pre-silanized precipitated silica; high surface area silica; at least 0.1 phr of a tear strength agent; a sulfur-based curing agent; and an accelerator for the curing agent.

[0009] The rubber composition may contain 30 phr to 80 phr of pre-silanized precipitated silica; 1 phr to 20 phr of high surface area silica; and 0.1 phr to 3 phr of a tear strength agent.

[0010] In some embodiments, the rubber composition contains 40 phr to 70 phr of pre-silanized precipitated silica; 3 phr to 12 phr of high surface area silica; and 0.3 phr to 2 phr of a tear strength agent.

[0011] The rubber composition may contain 50 phr to 60 phr of pre-silanized precipitated silica; 4 phr to 9 phr of high surface area silica; and 0.5 phr to 1.1 phr of a tear strength agent.

[0012] In some embodiments, the pre-silanized precipitated silica has a CTAB surface area of 130 m 2 / g to 210 m 2 / g.

[0013] The rubber composition may be free of carbon black.

[0014] In some embodiments, the rubber composition contains 0 phr to 5 phr of carbon black.

[0015] The rubber composition may contain at least 0.1 phr of a silica coupling agent.

[0016] In some embodiments, the rubber composition contains at least 0.1 phr of a cobalt salt.

[0017] The tear strength agent may include 3-methyl-5-pyrazolone.

[0018] In some embodiments, the rubber composition includes at least 1 phr of zinc oxide.

[0019] The rubber composition may contain at least 0.5 phr of a fatty acid.

[0020] In some embodiments, the rubber composition contains at least 0.2 phr of an accelerator.

[0021] Also contemplated is a cord-reinforced rubber component for a tire, which includes a plurality of cords encapsulated by a rubber composition.

[0022] The cord-reinforced rubber component may include a tire ply.

[0023] In some embodiments, each cord includes at least one of a wire and a fabric material.

[0024] Also contemplated is a tire including a cord-reinforced rubber component.

[0025] In other embodiments, a method of forming a cord-reinforced rubber component is disclosed. The method includes forming a rubber composition, coating at least one cord with the rubber composition; and curing the rubber composition coating the at least one cord to form a cord-reinforced rubber component. The rubber composition may be formed by combining 100 phr of an elastomer with pre-silanized silica, high surface area silica, at least 0.1 phr of a tear strength agent, a sulfur-based curing agent, and an accelerator for the curing agent, wherein the elastomer comprises 60-100 phr of a conjugated diene elastomer.

[0026] The method may further include assembling an uncured component of a tire, the tire component including a tire tread and a cord-reinforced rubber component.

[0027] In a further embodiment, a tire ply formed by coating a plurality of cords with a rubber composition and curing the rubber composition is disclosed. The rubber composition comprises: 100 phr of an elastomer, the elastomer comprising 60-100 phr of cis-1,4-polyisoprene; 30 phr to 80 phr of pre-silanized precipitated silica; 1 phr to 20 phr of having at least 200 m 2Silica with a CTAB surface area of / g; 0.1 phr to 3 phr of a tear strength agent; 0.1 phr to 6 phr of a silica coupling agent; 0.1 phr to 5 phr of a cobalt salt; 0.1 phr to 10 phr of an anti-degradant; 0.5 phr to 10 phr of a fatty acid; 1 phr to 20 phr of zinc oxide; 0.1 phr to 10 phr of a sulfur-based curing agent; and 0.2 phr to 5 phr of a curing accelerator.

[0028] The present invention discloses the following embodiments:

[0029] 1. A rubber composition comprising:

[0030] 100 phr of an elastomer, said elastomer comprising 60 - 100 phr of a conjugated diene elastomer;

[0031] Pre-silanized precipitated silica;

[0032] High surface area silica;

[0033] At least 0.1 phr of a tear strength agent;

[0034] A sulfur-based curing agent; and

[0035] An accelerator for said curing agent.

[0036] 2. The rubber composition according to embodiment 1, wherein the rubber composition comprises 30 phr to 80 phr of pre-silanized precipitated silica; 1 phr to 20 phr of high surface area silica; and 0.1 phr to 3 phr of a tear strength agent.

[0037] 3. The rubber composition according to embodiment 1, wherein the rubber composition comprises 40 phr to 70 phr of pre-silanized precipitated silica; 3 phr to 12 phr of high surface area silica; and 0.3 phr to 2 phr of a tear strength agent.

[0038] 4. The rubber composition according to embodiment 1, wherein the rubber composition comprises 50 phr to 60 phr of pre-silanized precipitated silica; 4 phr to 9 phr of high surface area silica; and 0.5 phr to 1.1 phr of a tear strength agent.

[0039] 5. The rubber composition according to embodiment 1, wherein the pre-silanized precipitated silica has a CTAB surface area of 130 m 2 / g to 210 m 2 / g.

[0040] 6. The rubber composition according to embodiment 1, wherein the rubber composition does not contain carbon black.

[0041] 7. The rubber composition according to embodiment 1, comprising 0 phr to 5 phr of carbon black.

[0042] 8. The rubber composition according to embodiment 1, further comprising at least 0.1 phr of a silica coupling agent.

[0043] 9. The rubber composition according to embodiment 1, further comprising at least 0.1 phr of a cobalt salt.

[0044] 10. The rubber composition according to embodiment 1, wherein the tear strength agent comprises 3-methyl-5-pyrazolone.

[0045] 11. The rubber composition according to embodiment 1, further comprising at least 1 phr of zinc oxide.

[0046] 12. The rubber composition according to embodiment 1, further comprising at least 0.5 phr of a fatty acid.

[0047] 13. The rubber composition according to embodiment 1, further comprising at least 0.2 phr of an accelerator.

[0048] 14. A cord-reinforced rubber component for a tire, comprising a plurality of cords encapsulated by the rubber composition of embodiment 1.

[0049] 15. The cord-reinforced rubber component according to embodiment 14, wherein the cord-reinforced rubber component comprises a tire ply.

[0050] 16. The cord-reinforced rubber component according to embodiment 14, wherein each of the cords comprises at least one of a wire and a fabric material.

[0051] 17. A tire comprising the cord-reinforced rubber component of embodiment 14.

[0052] 18. A method of forming a cord-reinforced rubber component, comprising:

[0053] forming a rubber composition comprising combining 100 phr of an elastomer, the elastomer comprising 60 - 100 phr of a conjugated diene elastomer, pre-silanized silica, high surface area silica, at least 0.1 phr of a tear strength agent, a sulfur-based curing agent, and an accelerator for the curing agent;

[0054] coating at least one cord with the rubber composition; and

[0055] And curing the rubber composition coating the at least one cord to form a cord-reinforced rubber component.

[0056] 19. The method according to embodiment 18, further comprising assembling an uncured component of a tire, the component of the tire including a tire tread and a cord-reinforced rubber component.

[0057] 20. A ply of a tire formed by coating a plurality of cords with a rubber composition and curing the rubber composition, the rubber composition comprising:

[0058] 100 phr of an elastomer, the elastomer comprising 60-100 phr of cis-1,4-polyisoprene;

[0059] 30 phr to 80 phr of pre-silanized precipitated silica;

[0060] 1 phr to 20 phr of silica having a CTAB surface area of at least 200 m 2 / g;

[0061] 0.1 phr to 3 phr of a tear strength agent;

[0062] 0.1 phr to 6 phr of a silica coupling agent;

[0063] 0.1 phr to 5 phr of a cobalt salt;

[0064] 0.1 phr to 10 phr of an anti-degradant;

[0065] 0.5 phr to 10 phr of a fatty acid;

[0066] 1 phr to 20 phr of zinc oxide;

[0067] 0.1 phr to 10 phr of a sulfur-based curing agent; and

[0068] 0.2 phr to 5 phr of a curing accelerator.

[0069] These and other non-limiting aspects and / or objects of the present disclosure are described more particularly below. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The following is a brief description of the drawings, which are presented for purposes of illustrating the exemplary embodiments disclosed herein and not for purposes of limiting the invention.

[0071] Figure 1 is a schematic cross-sectional view of a tire according to some embodiments; and

[0072] Figure 2Schematic cross-sectional view of a ply (e.g., belt ply, carcass ply, or cover ply) including cords coated with a rubber composition according to another embodiment. Specific embodiments

[0073] The present disclosure can be more readily understood by reference to the following detailed description of the contemplated embodiments and the accompanying drawings. In the following specification and the subsequent claims, numerous terms will be mentioned, and they should be defined to have the following meanings.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure. All publications, patent applications, patents, and other references mentioned herein are hereby incorporated by reference in their entirety. The materials, methods, and articles of manufacture disclosed herein are merely exemplary and are not intended to be limiting.

[0075] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural objects.

[0076] As used in the specification and claims, the term "comprising" can include embodiments of "consisting of" and "consisting essentially of". As used herein, the terms "comprising", "including", "having", "containing", "may", "including", and variations thereof are intended as open transitional phrases that require the presence of the specified element / step and allow the presence of other elements / steps. However, such descriptions should also be construed as describing the composition, mixture, or method as "consisting of" and "consisting essentially of" the recited element / step, which only allows the presence of the specified element / step and any impurities that may result therefrom, and excludes other elements / steps.

[0077] Unless a contrary indication is made, numerical values in the specification should be understood to include the same numerical values and values differing from the specified value by less than the experimental error of the type of conventional measurement technique used to determine that particular value when reduced to the same number of significant digits.

[0078] All ranges disclosed herein include the recited endpoints and can be combined independently (e.g., the range "2 to 10" includes the endpoints 2 and 10 and all intermediate values). The endpoints and any values disclosed herein for ranges are not limited to the exact range or value; they are sufficiently imprecise to include values approaching those ranges and / or values.

[0079] As used herein, approximating language may be used to modify any quantity representation, which may vary without resulting in a change in the basic function it involves. Thus, values modified by one or more terms such as "about" and "substantially" may not be limited to the specified exact values in some cases. The modifier "about" should also be considered to disclose a range bounded by the absolute values of the two endpoints. For example, the phrase "about 2 to about 4" also discloses the range "2 to 4". The term "about" may refer to plus or minus 10% of the indicated value. For example, "about 10%" may refer to the range of 9% to 11%, and "about 1" may refer to 0.9 - 1.1.

[0080] For the enumeration of numerical ranges herein, all intermediate numbers with the same precision therebetween are explicitly considered. For example, for the range of 6 - 9, numbers 7 and 8 are considered in addition to 6 and 9, and for the range 6.0 - 7.0, numbers 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9 and 7.0 are explicitly considered.

[0081] In the specification, the term "phr" refers to the number of parts of the corresponding material per 100 parts by weight of rubber or elastomer. The term "phf" refers to the number of parts per 100 parts by weight of filler. By convention, the uncured rubber used in the rubber composition totals 100 phr.

[0082] Unless otherwise specified, the terms "rubber" and "elastomer" may be used interchangeably. Unless otherwise specified, the terms "cure" and "vulcanize" may be used interchangeably.

[0083] The term "high surface area silica" as used herein refers to silica having a CTAB surface area of at least 200 m 2 / g.

[0084] This disclosure relates to rubber compositions and particularly to compositions suitable for use as coatings for cords / wires used in the plies of tires, such as carcass plies, tire belt plies, tire cover plies or ply strips of tires.

[0085] Reference Figure 1 , the pneumatic tire 10 includes a tire tread 12 which defines the road contact surface of the tire. Two sidewalls 14, 16 extend from the tread to the respective bead regions 18, 20. Each bead region includes one bead or a plurality of beads 22, 24 which may be held in place by the respective bead filler apexes 26, 28, and the inner liner 30 defines the innermost surface of the tire.

[0086] The tire includes a belt structure that includes a set of belt plies 32 (four in the illustrated embodiment), a cover ply 34 that covers the belt plies, and a carcass ply 36 that is located inside the belt plies. The illustrated carcass ply 36 includes a pair of axially opposite ends 38, 40, each of which is associated with a corresponding one of the beads 22, 24. Each axially end 38, 40 of the carcass ply 36 can be turned up and around a corresponding bead to a position that anchors the respective axially end. The turned-up portions 38, 40 of the carcass ply can engage the axially outer surface of a corresponding bead flipper 42, 44 and the axially inner surface of a corresponding heel chipper 46, 48. The exemplary tread 10 has circumferential grooves (four in the illustrated embodiment), each of which defines a U-shaped opening in the tread 10. The tread 12, sidewalls, and carcass can be formed of one or more rubber-based compositions. The exemplary tire is suitable for mounting on a rim of a vehicle, such as a truck or a passenger vehicle, for example. As will be appreciated, the overall construction of the tire 10 can be different from Figure 1 the construction shown therein and can include fewer or more components.

[0087] As Figure 2 shown therein, one or more components of the tire, particularly the belt plies 32, the cover ply 34, and / or the carcass ply 36, can include a set of substantially parallel reinforcing members, such as cords 50, for example at least two cords, or at least three or at least four cords, or at most ten cords. The cords can be made of one or more metal wires, fabric materials (such as polyester, rayon, or similar suitable organic polymer materials), or combinations thereof. The cords are separated by and encapsulated in strips 52 formed of the rubber compositions described herein. The cords 50 are used to reinforce the rubber compositions in the strips 52.

[0088] Each ply can be formed in a wire calender, where a plurality of substantially parallel cords, such as metal wires, are coated on both sides with layers or sheets of the exemplary rubber compositions. During the curing process, the cords are embedded in the strips of the rubber composition 52, reinforcing the strips of the rubber composition. In some embodiments, prior to coating with the rubber composition, the cords 50 can be impregnated in an impregnating solution or emulsion to better adhere to the rubber composition.

[0089] Rubber composition

[0090] Exemplary rubber compositions suitable for forming plies include an elastomeric component that includes at least one conjugated diene; a reinforcing filler component that includes presilanized precipitated silica and high surface area silica; a cobalt salt; a tear strength agent; and a curing package that includes a sulfur-based curing agent.

[0091] The exemplary rubber composition provides low hysteresis for the carcass ply and / or other plies. As a result, a tire formed from such plies, such as a truck tire, has low rolling resistance.

[0092] Elastomeric component

[0093] The exemplary rubber composition comprises 100 phr of one or more elastomers, said elastomers comprising at least one conjugated diene elastomer. In some embodiments, at least 60 phr, or at least 80 phr, or at least 90 phr, or at least 95 phr, or up to 100 phr of the elastomer component is one or more conjugated diene elastomers. In some embodiments, the conjugated diene elastomers are selected from natural rubber, synthetic cis-1,4-polyisoprene, and mixtures thereof. In certain embodiments, the one or more elastomers consist essentially of or consist of natural rubber.

[0094] As used herein, the glass transition temperature (Tg) of an elastomer or elastomer composition refers to one or more glass transition temperatures of the corresponding elastomer or elastomer composition in its uncured state or, in the case of an elastomer composition, possibly in the cured state. The Tg values referred to herein are determined by differential scanning calorimetry (DSC) as the peak midpoint at a heating rate of 10 °C per minute in accordance with ASTM D3418-21, "Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry".

[0095] Natural rubber is mainly derived from isoprene (2-methyl-1,3-butadiene) and is thus mainly (e.g., at least 99 wt%) polyisoprene, especially cis-1,4-polyisoprene. The term "natural rubber" as used herein refers to naturally occurring rubber, such as can be harvested from sources such as Hevea rubber trees and non-Hevea sources (e.g., guayule shrubs and dandelions such as TKS). In other words, the term "natural rubber" should be construed to exclude synthetic polyisoprene. Natural rubber produced from plantation gels (cup lumps) from Hevea brasiliensis trees is a common form of natural rubber. For example, technically specified rubber or block rubber (TSR) is natural rubber obtainable from Indonesia, where it may be referred to as Standard Indonesian Rubber (SIR), Malaysia (SMR), and Thailand (STR). It can be obtained in many grades, including TSR 10 and TSR 20, where the TSR 10 grade has a higher purity.

[0096] In some embodiments, the rubber composition comprises at least 60 phr of natural rubber, or at least 80 phr, or at least 90 phr, or at least 92 phr, or at least 95 phr, or at least 98 phr, or up to 100 phr of natural rubber.

[0097] Natural rubber is desirable for the tear properties (high tear strength), low hysteresis (relatively high heat rebound properties), and good processability of cord-reinforced rubber composites. However, a small amount of synthetic polyisoprene contributes to green strength. Synthetic polyisoprene can be used, especially cis-1,4-polyisoprene having a cis content of at least 94 wt%. The cis-1,4-content of the synthetic polyisoprene can be at least 96 wt%. The Tg of the synthetic polyisoprene can be in the range of -60 °C to -70 °C.

[0098] In some embodiments, no synthetic polyisoprene is present in the rubber composition. In another embodiment, the rubber composition comprises at least 2 phr of synthetic polyisoprene, or at least 3 phr, or at least 4 phr, or at least 6 phr, or at least 10 phr, or up to 20 phr of synthetic polyisoprene.

[0099] Other elastomers that may be present in a total amount of up to 40 phr, or up to 20 phr, or up to 10 phr may be selected from butadiene and its homologues and derivatives, such as homopolymers of methylbutadiene, dimethylbutadiene and pentadiene, and copolymers formed from butadiene or its homologues or derivatives with other unsaturated monomers. Among them, the latter may be acetylene, such as vinylacetylene; olefins, such as isobutene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds, such as acrylic acid, acrylonitrile (which polymerizes with butadiene to form NBR), methacrylic acid and styrene, the latter compound polymerizing with butadiene to form SBR; and vinyl esters and various unsaturated aldehydes, ketones and ethers, such as acrolein, methyl isopropenyl ketone and vinyl ethyl ether. Specific examples of such synthetic rubbers include chloroprene rubber (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), butyl rubber, halogenated butyl rubbers such as chlorobutyl rubber and bromobutyl rubber, styrene / isoprene / butadiene rubber, copolymers of 1,3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, ethylene / propylene terpolymers, also known as ethylene / propylene / diene monomer (EPDM), and especially ethylene / propylene / dicyclopentadiene terpolymers. Additional examples of elastomers that can be used include alkoxy-silyl-terminated solution-polymerized polymers (SBR, PBR, IBR and SIBR), and silicon-coupled and tin-coupled star-branched polymers.

[0100] Reinforcing filler

[0101] In some embodiments, the rubber composition includes silica and optionally carbon black as reinforcing fillers. These two fillers may be the only reinforcing fillers present in the rubber composition, or one or more additional fillers may be present, such as up to 30 phr, or up to 20 phr, or up to 10 phr of other reinforcing fillers.

[0102] In some embodiments, carbon black is omitted. In other embodiments, a small amount of carbon black is included as a carrier for the coupling agent. In some embodiments, the weight ratio of silica to carbon black may be at least 5:1, at least 10:1, at least 12:1, at least 14:1, at least 15:1, at least 16:1, at least 17:1, at least 18:1, at least 19:1, or at least 20:1.

[0103] Silica generally includes at least two different components, including presilanized precipitated silica and high surface area silica (e.g., having at least 200 m 2(CTAB surface area per g). In some embodiments, the weight ratio of the presilylated precipitated silica to the ultra-high surface area silica can be at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, or at least 9:1.

[0104] Pre-silanized precipitated silica

[0105] The presilylated precipitated silica can be pretreated and / or pre-hydrophobized.

[0106] In some embodiments, the presilylated and precipitated silica has a CTAB adsorption surface area of 130 m 2 / g to 210 m 2 / g, optionally 130 m 2 / g to 150 m 2 / g and / or 190 m 2 / g to 210 m 2 / g, or even 195 m 2 / g to 200 m 2 / g or 195 m 2 / g to 205 m 2 / g of CTAB adsorption surface area. The CTAB (cetyltrimethylammonium bromide) method (ASTM D6845) for determining the surface area of silica is known to those skilled in the art.

[0107] In some embodiments, the presilylated precipitated silica is a precipitated silica pre-reacted with a silica coupling agent, and the silica coupling agent includes bis(3-triethoxysilylpropyl) polysulfide or alkoxy organomercapto silane containing an average of 1 to 5 linked sulfur atoms (preferably 2 to 4) in its polysulfide bridge.

[0108] Mercapto silane and its SH group can improve the compatibility with rubber materials or rubber matrices and / or support the curing process.

[0109] The amount of mercapto groups on the silica surface can be 0.1 to 1 wt%, or 0.4 to 1 wt% or 0.4 to 0.6 wt%.

[0110] In addition to the mercapto groups coupled to the silica, the silica can contain a compatibilizer, which is usually a (hydrocarbon) carbon chain material having multiple carbon atoms (e.g., at least 4 carbon atoms) along its chain. Such compatibilizers can promote the mixing of the composition. In one example, the carbon surface loading / functionalization weight percentage is 2 to 10, or 3 to 8.

[0111] In another embodiment, the presilylated precipitated silica is a precipitated silica pre-reacted with a silica coupling agent containing alkoxy organomercapto silane.

[0112] In another embodiment, the presilylated precipitated silica is pre-hydrophobized, for example, with a hydrocarbon chain material having a plurality of carbon atoms (e.g., at least 4 carbon atoms) along its chain.

[0113] The precipitated silica reinforcing agent can be characterized, for example, by having a BET surface area measured using nitrogen of, for example, from about 40 to about 600, and more typically from about 50 to about 300 square meters per gram. The BET method for measuring surface area can be described, for example, in Journal of the American Chemical Society, Volume 60 and ASTM D3037.

[0114] Such precipitated silica can also be characterized, for example, by having a dibutyl phthalate (DBP) absorption value of, for example, from about 100 cc / 100 g to about 400 cc / 100 g and more typically from about 150 cc / 100 g to about 300 cc / 100 g.

[0115] The pre-hydrophobized precipitated silica is hydrophobized by treatment with at least one silane before its addition to the rubber composition. Suitable silanes include, but are not limited to, alkyl silanes, alkoxy silanes, organoalkoxysilyl polysulfides, and organomercaptoalkoxy silanes.

[0116] In an alternative embodiment, the pre-hydrophobized precipitated silica can be pretreated with a silica coupling agent comprising, for example, an alkoxy organomercaptoalkoxy silane or a combination of an alkoxy silane and an organomercaptoalkoxy silane before blending the pretreated silica with the rubber, rather than allowing the precipitated silica to react in situ with the silica coupling agent in the rubber. See, for example, U.S. Patent No. 7,214,731, the teachings of which are incorporated herein for the purpose of describing pre-hydrophobized precipitated silica and techniques for making such pre-hydrophobized precipitated silica.

[0117] The pre-hydrophobized precipitated silica can optionally be treated with a silica dispersion aid. Such silica dispersion aids can include glycols, such as fatty acids, diethylene glycol, polyethylene glycol, hydrogenated or non-hydrogenated C 5 or C 6 fatty acid esters of sugars and polyoxyethylene derivatives of hydrogenated or non-hydrogenated C 5 or C 6 fatty acid esters of sugars. Exemplary fatty acids include stearic acid, palmitic acid, and oleic acid. Exemplary hydrogenated and non-hydrogenated C 5 and C 6Fatty acid esters of sugars (such as sorbose, mannose, and arabinose) include, but are not limited to, sorbitan oleates such as sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, and sorbitan sesquioleate, and sorbitan esters of lauric fatty acids, sorbitan esters of palmitic fatty acids, and sorbitan esters of stearic fatty acids. Exemplary hydrogenated and non-hydrogenated C 5 and C 6 Polyoxyethylene derivatives of fatty acid esters of sugars include, but are not limited to, polysorbates and polyoxyethylene sorbitan esters, which are similar to the above-described hydrogenated and non-hydrogenated fatty acid esters of sugars, except that an ethylene oxide group is added to each hydroxyl group.

[0118] If used, the optional silica dispersion aid is present in an amount of from about 0.1 wt% to about 25 wt% based on the weight of the silica, where from about 0.5 wt% to about 20 wt% is suitable, and from about 1 wt% to about 15 wt% based on the weight of the silica is also suitable. Various pretreated precipitated silicas are described in U.S. Patent Nos. 4,704,414, 6,123,762, and 6,573,324. The teachings of U.S. Patent Nos. 4,704,414, 6,123,762, and 6,573,324 are incorporated herein by reference.

[0119] In any case, the pre-hydrophobized precipitated silica is pre-hydrophobized by treating the silica in its aqueous colloidal form with both an organomercaptosilane and an alkylsilane, where the weight ratio of the organomercaptosilane to the alkylsilane is from 10 / 90 to 90 / 10; where the alkylsilane has the general formula (I):

[0120] X n -Si-R 4-n (I),

[0121] where R is an alkyl group having 1 to 18 carbon atoms, preferably 1 to 8 carbon atoms, such as methyl, ethyl, isopropyl, n-butyl, and octadecyl, n is a number from 1 to 3 and X is a group selected from a halogen, i.e., chlorine or bromine, preferably a chlorine group, and an alkoxy group, preferably an alkoxy group of the form (R 1 O)-, where R 1 is an alkyl group having 1 to 3 carbon atoms, such as methyl, ethyl, and isopropyl, preferably methyl and ethyl, and where the organomercaptosilane has the general formula (II):

[0122] (X) n (R 2 O) 3-n -Si-R 3 -SH (II),

[0123] Wherein X is a group selected from the following: halogen, such as chlorine or bromine, preferably a chlorine group, and an alkyl group having 1 to 16 carbon atoms, preferably selected from methyl, ethyl, n-propyl and n-butyl; wherein R 2 is an alkyl group having 1 to 16 carbon atoms, preferably 1 to 4 carbon atoms, preferably selected from methyl and ethyl, and R 3 is an alkylene group having 1 to 16 carbon atoms, preferably 1 to 4 carbon atoms, preferably propylene; wherein n represents an integer from 0 to 3, and wherein n preferably represents 0.

[0124] The hydrophobized precipitated silica aggregates can be recovered, for example, from the treated colloidal silica, for example as a treated silica hydrosol - by adding an acid (such as sulfuric acid or hydrochloric acid) to the treated colloidal silica, followed by washing with water and drying to recover the hydrophobized silica as hydrophobized silica gel or as hydrophobized precipitated silica. Although the present invention is not intended to cover the specific preparation techniques of the pre-hydrophobized precipitated silica itself (preparation of silica hydrosol, recovery of silica gel and precipitated silica, etc.), for educational purposes in this regard, for a more detailed discussion, reference can be made to the above-mentioned Condensed Chemical Dictionary and U.S. Patent Nos. 5,094,829 and 5,708,069, 5,789,514 and 5,750,610.

[0125] Representative alkylsilanes of formula (I) are, for example, trichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane, methoxymethylsilane, trimethoxypropylsilane, trimethoxyoctylsilane, trimethoxyhexadecylsilane, dimethoxydipropylsilane, triethoxymethylsilane, triethoxypropylsilane, triethoxyoctylsilane and diethoxydimethylsilane.

[0126] Representative organosulfhydrylsilanes of formula (II) are, for example, triethoxysulfhydrylpropylsilane, trimethoxysulfhydrylpropylsilane, methyldimethoxysulfhydrylpropylsilane, methyldiethoxysulfhydrylpropylsilane, dimethylmethoxysulfhydrylpropylsilane, triethoxysulfhydrylethylsilane and tripropoxysulfhydrylpropylsilane.

[0127] Some non-limiting examples of the pretreated silica (i.e., silica pre-surface treated with silane) include, but are not limited to, silica pretreated with sulfhydrylsilane 255LD and LP (PPG Industries) silica, and 8113 (Degussa), which is a reaction product between the organosilane bis(triethoxysilylpropyl) polysulfide (Si69) and VN3 silica, and 6508, from PPG Industries 400 silica, from PPG Industries 454 silica, and from PPG Industries 458 silica. Some representative examples of preferred presilanized precipitated silica include those from PPG Industries 400, 454 and 458.

[0128] A variety of commercially available precipitated silica that can be used in combination with presilanized precipitated silica can be used, such as silica with grades 210, 243, etc. from PPG Industries under the trademark Hi-Sil; silica from Solvay with grades such as Zeosil 1165MP and Zeosil 165GR; and silica from Evonik with grades such as VN2 and VN3.

[0129] In one embodiment, the rubber composition does not include the addition of a silica coupling agent to the rubber composition (and thus does not include a silica coupling agent).

[0130] As shown, in one embodiment, the rubber composition may contain a combination of an additional silica coupling agent added to the rubber composition, particularly bis(3-triethoxysilylpropyl) polysulfide containing on average from about 2 to about 4 linked sulfur atoms in its polysulfide bridges, and an additional precipitated silica (non-presilanized precipitated silica) added to the rubber composition, wherein the ratio of presilanized precipitated silica to the precipitated silica is desirably at least 8 / 1, or at least 10 / 1.

[0131] The surface area of silica can be measured in various ways. One method is 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 the nitrogen surface area. Another method is according to ASTM D6845-20, "Standard Test Method for Silica, Precipitated, Hydrated-CTAB (Cetyltrimethylammonium Bromide) Surface Area", which is referred to herein as the CTAB surface area. CTAB molecules are relatively large; thus it does not adsorb in micropores or on rough surfaces. Accordingly, the CTAB surface area only reflects the silica surface available for interaction with rubber molecules.

[0132] The carcass ply typically uses medium nitrogen surface area silica, such as about 160 m 2 / g.

[0133] High surface area silica

[0134] An exemplary high surface area silica is available as Zeosil TM Premium SW from Solvay. This silica has a CTAB surface area of about 250 m 2 / g. High surface area silica has a CTAB surface area of at least 200 m 2 / g, or at least 220 m 2 / g, or at least 240 m 2 / g, or at least 250 m 2 / g. In some embodiments, the high surface area silica has a CTAB surface area of at most 350 m 2 / g or at most 300 m 2 / g.

[0135] Coupling agent

[0136] The use of a silica coupling agent in combination with precipitated silica can promote low hysteresis and good tear strength in rubber compositions. Suitable coupling agents generally include a first portion that reacts with hydroxyl groups (such as silanol groups) present on the surface of precipitated silica and a second portion that is capable of reacting with a diene-based elastomer (such as natural rubber and / or synthetic polyisoprene rubber). These two portions are connected by a linking group (such as a hydrocarbon group or a sulfur bridge) such that the precipitated silica is chemically bonded to the elastomer. Examples of silica coupling agents include those containing groups such as alkyl, alkoxy, mercapto, capped mercapto, sulfide-containing groups (such as alkoxy-containing groups based on monosulfide, alkoxy-containing groups based on disulfide, alkoxy-containing groups based on tetrasulfide), amino, vinyl, epoxy, and combinations thereof.

[0137] Specific examples of silane coupling agents include alkoxy organomercapto silanes and bis(3-triethoxysilylpropyl) polysulfides containing on average 1 to 5 (preferably 2 to 4) linked sulfur atoms in their polysulfide bridges. Bis(3-triethoxysilylpropyl) polysulfides having on average approximately 2 to approximately 2.6 and approximately 3.4 to approximately 3.8 linked sulfur atoms in their polysulfide bridges are available as Si266 TM and Si69 TM obtained from Evonik Industries.

[0138] The rubber composition may include at least 0.1 phr, or at least 0.5 phr or at least 1 phr, or at most 6 phr, or at most 3 phr, or at most 2 phr of the silica coupling agent. The silica coupling agent may be present in an amount sufficient to provide a weight ratio of the total amount of coupling agent to silica filler of at least 0.1:100, or at least 1:100, or at least 2:100, or at most 25:100, or at most 20:100, or at most 8:100. When the silica is pretreated with the coupling agent, a smaller amount of the coupling agent can be used than when the silica is treated in situ with the coupling agent.

[0139] Examples of silica dispersion aids include diols such as fatty acids, diethylene glycol, alkylene diols such as polyethylene glycol and polypropylene glycol, hydrogenated or non-hydrogenated C 5 or C 6 fatty acid esters of sugars, polyoxyethylene derivatives of hydrogenated or non-hydrogenated C 5 or C 6 fatty acid esters of sugars, and mixtures thereof. Exemplary fatty acids include stearic acid, palmitic acid, and oleic acid. Exemplary hydrogenated and non-hydrogenated C 5 or C 6Fatty acid esters of sugars (such as sorbose, mannose, and arabinose) include sorbitan oleates such as sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, and sorbitan sesquioleate, as well as sorbitan esters of lauric fatty acids, sorbitan esters of palmitic fatty acids, and sorbitan esters of stearic fatty acids. Exemplary hydrogenated and non-hydrogenated C 5 or C 6 Polyoxyethylene derivatives of fatty acid esters of sugars include polysorbates and polyoxyethylene sorbitan esters, which are similar to fatty acid esters of hydrogenated and non-hydrogenated sugars except that an ethylene oxide group is placed on each hydroxyl group.

[0140] Exemplary polyalkylene oxides can have a weight-average molecular weight Mw of at least 500, such as at least 2,000, or at least 4,000, or at most 15,000, or at most 12,000, or at most 10,000, or at most 8,500. In cases where a polyalkylene oxide (such as polyethylene glycol) is used in a rubber composition, it can be included in an amount of at least 0.1 phr, such as at least 0.2 phr, or at least 0.3 phr, or at most 5 phr, or at most 3 phr, or at most 2 phr, or at most 1 phr, or at most 0.6 phr.

[0141] Examples of commercially available polyethylene glycols include Carbowax TM PEG 3350 and Carbowax TM PEG 8000, where the numbers indicate the approximate weight-average molecular weight. Other polyalkylene oxide polymers can be used, such as those described in U.S. Patent Nos. 6,322,811 and 4,082,703.

[0142] If used, based on the weight of the silica, the silica dispersion aid can be present in a total amount of at least 0.1 wt%, or at least 0.5 wt%, or at least 1 wt%, or at most 25 wt%, or at most 20 wt% or at most 15 wt%.

[0143] Carbon black

[0144] Common carbon blacks can also be added, for example, as additional filler components or to impart black color to the tire components. However, in some embodiments, the rubber composition contains less than 5 phr of carbon black or less than 3 phr of carbon black, or even no carbon black. Representative examples of carbon blacks include N110, N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990, and N991. These carbon blacks have an iodine absorption of 9 to 145 g / kg and a DBP value of 34 cm 3 / 100 g to 150 cm 3 / 100 g.

[0145] Other reinforcing fillers

[0146] In addition to silica and carbon black, additional reinforcing fillers can be used, for example, in a total amount of up to 30 phr, or up to 20 phr, or up to 10 phr, or up to 1 phr, or may be absent. Examples of such additional reinforcing fillers include calcium carbonate, alumina, aluminum hydroxide, clay (reinforcing grade), magnesium hydroxide, boron nitride, aluminum nitride, titanium dioxide, reinforcing zinc oxide, and combinations thereof.

[0147] Tear strength agent

[0148] The tear strength agent helps to provide an improvement in the tear strength of the rubber composition. The rubber composition may contain at least 0.1 phr, or at least 0.5 phr, or up to 3 phr, or up to 2 phr, or up to 1.2 phr, or up to 1 phr of the tear strength agent.

[0149] Examples of tear strength agents include nitrogen-containing organic compounds such as those of formulas (1) to (8), and mixtures thereof:

[0150]

[0151] In the formula, R represents an acylhydrazide group, an N'-alkylidene hydrazide group, an N-allylcarbamoyl group, a 3-carboxyacryloyl group, a hydrazinocarboxylamino group, a thiocarboxyl group, a thiol group, or a hydrogen atom. R 4 is a sulfur atom or an oxygen atom. R 5is a thiol group or a hydroxyl group. R 6 is an alkylene group having 1 to 4 carbon atoms. R 7 is an alkyl group, an aralkyl group or a heterocyclic group. R 8 is a hydrogen atom or an amino group. R 9 is a heteroatom. R 10 is a heterocyclic group.

[0152] In some embodiments, the tear strength agent includes a heterocycle containing more than one nitrogen atom. For example, the tear strength agent may include 3-methyl-5-pyrazolone (Formula (8), which may be obtained as Acroad TM EN-01 from Otsuka Chemical Co., Ltd).

[0153] Cobalt salt

[0154] In some embodiments, the rubber composition includes a cobalt salt. The rubber composition may include at least 0.1 phr, or at least 0.2 phr, or at least 0.3 phr, or at most 5 phr, or at most 2 phr, or at most 1 phr, or at most 0.6 phr of the cobalt salt.

[0155] In the ply coating, the cobalt salt can improve the adhesion of the rubber coating to the ply material, especially if such material is a metal, such as brass-coated metal, like steel. The cobalt salt tends to promote high low-strain stiffness values (as demonstrated by G' at 10% strain at 100 °C).

[0156] In some embodiments, the cobalt salt is an organic salt of cobalt. Examples of organic cobalt salts include cobalt salts of fatty acids and cobalt salts of aliphatic or alicyclic carboxylic acids having 6 to 30 carbon atoms. Examples of such cobalt salts include cobalt naphthenate, cobalt octoate, cobalt linoleate, cobalt stearate, cobalt oleate, cobalt acetate, cobalt neodecanoate, cobalt salts of tall oil fatty acids, cobalt resinate, cobalt pyruvate, in-situ salts prepared from cobalt hydroxide and organic acids such as naphthenic acid, stearic acid, oleic acid, acetic acid, linoleic acid, cobalt-boron complex salts, cobalt-aluminum complex salts, and mixtures thereof. Examples of complex salts containing aluminum and / or boron linked to divalent cobalt through an oxygen atom and containing at least one acyloxy group attached to cobalt include those of the general formula X-Co-[O-T(Y)] m -[O-Co] n -Y, where X is an acyloxy group, T is selected from boron and aluminum, Y is an alkoxy group or an acyloxy group, m is at least 1, and n is 0 or 1. Methods for preparing this type of complex cobalt salt are described, for example, in U.S. Patent No. 3,296,242A.

[0157] The cobalt boron complex organic salts that can be used are available as ManobondTM C is obtained from Borchers Americas, Inc. and is available as ComendT M Cobalt boro-neodecanoate obtained from Shepherd Chemical.

[0158] In another embodiment, the cobalt salt is an inorganic salt such as cobalt chloride.

[0159] In another embodiment, the rubber composition may be substantially free of cobalt, i.e., it includes less than 0.1 phr, or less than 0.05 phr, or 0 phr of cobalt salt.

[0160] Other compounding ingredients

[0161] The rubber composition may include additional components such as anti-degradants, processing aids, peptizers, sulfur-based curing agents, activators, cure accelerators, and cure retarders.

[0162] The rubber composition may include at least 0.1 phr, or at least 1 phr, or at least 2 phr, or up to 10 phr, or up to 8 phr, or up to 5 phr of anti-degradants such as anti-ozonants and / or antioxidants. These compounds help protect the tire from oxidation and ozonation. Representative anti-degradants include monophenols, bisphenols, thio-bisphenols, polyphenols, hydroquinone derivatives, phosphites, phosphate blends, thioesters, naphthylamines, bisphenol amines, and other diarylamine derivatives, p-phenylenediamines, quinolines, and blended amines. Exemplary antioxidants include 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), diphenyl-p-phenylenediamine (PPD), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), etc., such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 - 346.

[0163] Exemplary processing aids include liquid plasticizers, waxes, resins, and combinations thereof. Liquid plasticizers, such as processing oils, have a Tg below 0 °C, typically well below 0 °C, such as below -30 °C, or below -40 °C, or below -50 °C, e.g., a Tg of from 0 °C to -100 °C. Relatively low concentrations of processing oils assist in mixing the components of the rubber composition and / or facilitate the processing of the rubber composition. Representative processing oils useful in rubber compositions include aliphatic oils, aromatic oils, naphthenic oils, triglyceride oils, low polycyclic aromatic (PCA) oils such as mild extraction solvates (MES), treated distillate aromatic extracts (TDAE), special residual aromatic extract (SRAE), and heavy naphthenes, and mixtures thereof. Triglyceride oils that can be used include vegetable oils such as castor oil, soybean oil, canola oil, corn oil, cottonseed oil, olive oil, palm oil, safflower oil, sunflower oil, coconut oil, and peanut oil. Castor oil is a triglyceride oil that contains approximately 87 wt% ricinoleic acid, 7 wt% oleic acid, 3 wt% linoleic acid, 2 wt% palmitic acid, and 1 wt% stearic acid. Exemplary naphthenic processing oils include Hyprene from Ergon Refining, Inc. TM 100, and Tufflo 100 from Barton Solvent Company TM . One or more processing oils can be used in the rubber composition at about 0 to about 30 phr, such as at least 0.5 phr, or at least 1 phr, or at most 10 phr, or at most 7 phr, or at most 5 phr, or at most 3 phr. In some embodiments, the oil can be used as a carrier for one or more other components (such as for elemental sulfur).

[0164] Exemplary resins useful in rubber compositions are typically solids or viscous at room temperature and include tackifying resins such as non-reactive phenolic resins, and rigid resins such as reactive phenolic resins and resorcinol or resorcinol with hexamethylenetetramine, hexakis(methoxymethyl)melamine (HMMM) resins, benzoxazine resins, and hydrocarbon resins. Exemplary hydrocarbon resins include aromatic, aliphatic, and cycloaliphatic resins.

[0165] In some embodiments, the rubber composition comprises 1 to 10 phr of resin. In another embodiment, the rubber composition is free or substantially free of resin. This is beneficial because the resin can pose a potential threat to the environment, health, and safety during mixing and / or tire manufacturing processes. Thus, it is desirable to identify compositions that have good adhesion and / or stiffness properties while avoiding the resin. In particular, the amount of resin in the composition can be less than 1 phr, or less than 0.5 phr, or less than 0.2 phr, or 0 phr.

[0166] Suitable waxes, particularly microcrystalline waxes, can be of the type described in The Vanderbilt Rubber Handbook (1978), pages 346 and 347. The wax can be absent from the rubber composition or present in the composition and used in an amount of at least 1 phr or up to 5 phr.

[0167] Exemplary peptizers include pentachlorophenol dibenzoyl aminodiphenyl disulfide. The peptizer can be absent from the rubber composition or present in the composition and used in an amount of at least 0.1 phr, or up to 1 phr, or up to 0.4 phr.

[0168] Exemplary sulfur-based curing agents include elemental sulfur (free sulfur) and sulfur donors, such as amine disulfides, polymeric polysulfides, and sulfur olefin adducts. The amount of the sulfur-based curing agent can vary depending on the type of rubber and the specific type of curing agent, but can be from 0.1 phr to 10 phr, such as at least 0.5 phr, or at least 1 phr, or at least 2 phr, or up to 8 phr, or up to 6 phr.

[0169] Exemplary activators for the sulfur curing agent include fatty acids and zinc oxide. Zinc oxide can help improve the adhesion between the wire and the coated rubber stock during sulfur curing. The rubber composition can include 1 phr to 20 phr of zinc oxide, such as at least 5 phr, or at least 7 phr, or up to 15 phr, or up to 12 phr, or up to 10 phr of zinc oxide. Exemplary fatty acids include stearic acid and mixtures of stearic acid with other fatty acids. The rubber composition can include 0.5 phr of fatty acid, such as at least 0.7 phr, or at least 1 phr, or at least 1.2 phr, or up to 10 phr, or up to 5 phr, or up to 2 phr of fatty acid.

[0170] Accelerators can be used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanized rubber. In the rubber composition, the accelerator can be at least 0.2 phr, or at least 0.5 phr, or at least 1 phr, or up to 5 phr, or up to 3 phr.

[0171] Exemplary accelerators for sulfur-based curing agents include amines, guanidines, thioureas, thiols, thiazoles, thiurams, sulfenamides, dithiocarbamates, and xanthates / salts. Examples of thiazole curing accelerators include 2-mercaptobenzothiazole, 2,2'-dithiobis(benzothiazole) (MBTS), N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), and N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), guanidine curing accelerators such as diphenylguanidine (DPG), and mixtures thereof. In some embodiments, a single accelerator system, i.e., a primary accelerator, can be used. In other embodiments, the primary accelerator is used in combination with a secondary accelerator, where the primary accelerator becomes active at a lower temperature than the secondary accelerator but loses its activity more quickly. The secondary accelerator can be used in an amount less than that of the primary accelerator. The primary accelerator can be a sulfenamide, while the secondary accelerator can be a guanidine, dithiocarbamate, or thiuram compound such as diphenylguanidine.

[0172] As is to be understood, the rubber composition can include other ingredients in addition to those exemplified herein.

[0173] Table 1 shows exemplary rubber compositions, expressed in phr. All ingredients are expressed based on the active substance (i.e., excluding diluents, carriers).

[0174] Table 1: Exemplary rubber composition

[0175]

[0176]

[0177] Forming a rubber composition

[0178] The various components of the rubber layer can be mixed together using a convenient rubber mixing device, such as a Banbury mixer. Generally, elastomers, such as butyl rubber and natural rubber, are blended in the absence of a curing agent in at least one non-productive mixing stage, followed by a final or productive mixing stage in which the curing agent (and possibly one or more additional ingredients) is added. In the productive mixing stage, the mixing is typically carried out at a temperature lower than the temperature or limit temperature used in one or more of the previous non-productive mixing stages.

[0179] In some embodiments, during the first non-productive stage(s), the components other than the sulfur-based curing agent are stirred in a mixer set at a suitable temperature, such as at least 100 °C, or at least 110 °C, or at most 165 °C. The temperature of the mixture increases as it is stirred. When the temperature reaches about 150 °C - 165 °C, the mixture is poured out of the mixer and allowed to cool, and then returned to the mixer. In the second productive stage, the mixture is returned to the mixer with the curing agent for 1 to 5 minutes to incorporate the curing agent into the mixture, but without significantly curing the mixture.

[0180] The vulcanization of a pneumatic tire incorporating the rubber composition can be carried out at a temperature of 100 °C to 200 °C, such as 110 °C to 180 °C. Any conventional vulcanization method can be used, such as heating in a press or mold, heating with superheated steam or hot air. Such tires can be constructed, shaped, molded, and cured by various known methods and are obvious to those skilled in the art.

[0181] The rubber composition generally has sufficient viscosity and uncured tack to enable it to be incorporated into an uncured tire without significantly deviating from conventional tire manufacturing techniques. In some embodiments, a strip of the rubber composition is formed.

[0182] Tire construction

[0183] To form a cord-reinforced rubber component, such as a ply, before curing the rubber composition, multiple cords that are typically arranged in parallel are coated with the rubber composition. The coated cords can pass through a calender that applies pressure and optionally heat to provide a ply having relatively smooth upper and lower surfaces defined by the rubber composition.

[0184] One or more plies formed from the above-described rubber composition can be constructed into an uncured tubeless pneumatic rubber tire before vulcanization. A tire comprising a vulcanized rubber composition is also disclosed.

[0185] In some embodiments, the tire includes one or more of a ply, such as a belt ply, a carcass ply, a cover ply (covering one or more belt plies), and a ply strip (which can be helically wound in the circumferential direction of the tire). The ply contains an exemplary rubber composition, such as in the form of a rubber coating attached to a fabric or wire material. The ply can be formed in a calender device, such as a wire calender or a fabric calender. The coating contains or consists of a rubber composition according to one or more embodiments described herein.

[0186] A tire containing a ply formed of an exemplary rubber composition can be a racing tire, a passenger car tire, an aircraft tire, an agricultural tire, a bulldozer tire, an off-road tire, a truck tire, etc. The tire can be a radial tire or a bias tire. In some embodiments, the tire is a pneumatic radial (medium-duty) truck tire.

[0187] Without intending to limit the scope of the exemplary embodiments, the following examples illustrate the rubber compositions and their properties.

[0188] Examples

[0189] The rubber composition was prepared in a Banbury mixer using three separate addition stages, with two non-productive mixing stages totaling approximately 4 minutes to a temperature of approximately 140 °C. After the second non-productive stage was a productive mixing stage at a temperature of approximately 2 minutes to approximately 105 °C, where sulfur and a curing agent were added.

[0190] Table 1 shows the amounts of the components of the example rubber compositions, expressed in phr.

[0191] Example A used 55 phr of pre-silanized precipitated silica. Example B corresponded to Example A but further incorporated 6.4 phr of high surface area silica. Example C corresponded to Example B but further included 0.6 phr of a tear strength agent. Example D corresponded to Example C but replaced 0.6 phr of the tear strength reagent with 1.0 phr of a tear strength reagent.

[0192] The amounts of natural rubber, silica coupling agent, and various additives were the same for each example.

[0193] Table 2 - Rubber composition (phr)

[0194]

[0195] 400G, CTAB surface area of 140 m 2 / g.

[0196] 2 From Solvay Premium SW, CTAB surface area of 250 m 2 / g.

[0197] 3 3-Methyl-5-pyrazolone, as EN-01 obtained from Otsuka Chemical Co., Ltd.

[0198] 4Bis(3-triethoxysilylpropyl) polysulfide, as SI Obtained from Evonik Industries.

[0199] A mixture of 5-dihydroquinoline and one or more antioxidants based on phenylenediamine.

[0200] 6 Rubber processing oil, including naphthenic oil.

[0201] 7 Mainly stearic acid (at least 90% stearic acid), as a mixture of stearic acid, palmitic acid and oleic acid.

[0202] 8 Cobalt neodecanoate salt, 20.5% by weight of cobalt.

[0203] 9 Sulfenamide.

[0204] 10 Elemental sulfur. Examples A, B and E use Crystex from Flexus TM HDOT20, which is incorporated into a carrier oil (specified separately in Table 2), while Examples C and D use Crystex TM OT33AS, which is incorporated into a carrier oil and silica (specified separately in Table 2).

[0205] The rubber composition is formed into test samples and cured at a temperature of approximately 150 °C for approximately 32 minutes. The following tests are carried out on the cured strips:

[0206] According to ASTM D5289-19a, "Standard Test Method for Rubber Property-Vulcanization Using Rotorless Cure Meters", a Rubber Processing Analyzer (RPA) RPA2000 from Alpha Technologies is used to obtain the value of the storage modulus G' at a temperature of 100 °C at 10% strain (MPa). The tangent δ value (the ratio of G" to G') is also obtained.

[0207] Tear strength data is obtained through a peel strength adhesion test to determine the interfacial adhesion between two samples of the rubber composition. The interfacial adhesion is determined according to DIN 53539, 1979 edition, September 1979, using an Instron instrument by pulling one rubber composition away from another at right angles to the un-torn specimen, where the two ends of the rubber composition are pulled apart at an angle of 180°.

[0208] Steel cord adhesion data was determined according to ASTM D2229-10(2014), "Standard Test Method for Adhesion Between Steel Tire Cords and Rubber". For this test, a block of the rubber composition was formed in a four-chamber steel cord adhesion mold with a steel core. This test method involves determining the force required to pull the steel cord out of the vulcanized rubber block.

[0209] The steel cord adhesion coverage was determined by visual observation (the higher, the better).

[0210] The elongation at break (%) was determined using an Automated Testing System instrument from Instron Corporation according to ASTM D412-06ae2, "Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers - Tension".

[0211] The resilience was measured on a ZwickRoell TM 5109 resilience tester according to DIN 53512, April 2000, "Determination the rebound resilience of rubber using the Schob pendulum" at a given temperature (100 °C).

[0212] The cut growth was measured at 95 °C using a pierced groove flex test according to ASTM D813.

[0213] The physical properties of the rubber composition are shown in Table 3.

[0214] Table 3: Properties of the rubber composition (normalized to Example A = 100)

[0215] Testing Example A Example B Example C Example D G’ (10% strain) MPa 100 120 187 173 Tan δ at 10% strain 100 122 140 138 Rebound (100 °C), % 100 95 98 98 Tear strength, N / mm 100 167 400 367 Elongation at break, % 100 115 121 123 Steel cord adhesion after 10 days water aging N 100 146 205 209 Steel cord adhesion coverage, % 100 133 189 322 Fatigue notch growth, min / mm 100 125 225 242

[0216] Using only pre-silanized precipitated silica (Example A) results in low hysteresis, but with a significant reduction in stiffness, tear, and wire adhesion. Adding 6.4 phr of high surface area silica (Example B) improves elongation while increasing stiffness, slightly improves tear, but does not improve wire adhesion. Adding 0.6 phr of tear strength agent (Example C) or 1.0 phr of tear strength agent (Example D) further improves stiffness, tear, and wire adhesion without affecting hysteresis. Additionally, when the additives are used together, the fatigue crack growth property is improved. Incorporating these components together can balance the durability metrics while using a low hysteresis filler.

[0217] The various documents mentioned above are incorporated herein by reference. Except in the examples or where otherwise expressly indicated, all numerical quantities of materials, reaction conditions, molecular weights, carbon atom numbers, etc. specified in this specification should be understood to be modified by the word "about". Unless otherwise stated, 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 commonly understood to be present in commercial grades. However, unless otherwise stated, the amounts of each chemical component stated do not include any solvents or diluent oils that may conventionally be present in commercial materials. It is to be understood that the upper and lower limits, ranges, and ratio limits listed herein can be combined independently. Similarly, the ranges and amounts of each element can be used with the ranges or amounts of any other element.

[0218] It is recognized that variations or alternatives of the features and functions disclosed above and others can be combined into many other different systems or applications. Those skilled in the art may subsequently make various substitutions, modifications, variations, or improvements that are currently unforeseen or unexpected, and these are also intended to be covered by the following claims.

Claims

1. A rubber composition comprising: 100 phr of an elastomer, the elastomer comprising 60-100 phr of a conjugated diene elastomer; Pre-silanized precipitated silica; high surface area silica; At least 0.1 phr of a tear strength agent; Sulfur-based curing agents; and An accelerator for the curing agent.

2. The rubber composition of claim 1, wherein the rubber composition comprises 30 to 80 phr of pre-silanized precipitated silica; 1 to 20 phr of high surface area silica; and 0.1 to 3 phr of a tear strength agent.

3. The rubber composition of claim 1, wherein the rubber composition comprises 40 to 70 phr of pre-silanized precipitated silica; 3 to 12 phr of high surface area silica; and 0.3 to 2 phr of a tear strength agent.

4. The rubber composition of claim 1, wherein the rubber composition comprises 50 to 60 phr of pre-silanized precipitated silica; 4 to 9 phr of high surface area silica; and 0.5 to 1.1 phr of a tear strength agent.

5. The rubber composition according to claim 1, wherein the pre-silanized precipitated silica has a 2 / g to 210m 2 / g of CTAB surface area. The rubber composition according to claim 1 , wherein the rubber composition does not contain carbon black.

7. The rubber composition according to claim 1, comprising 0 to 5 phr of carbon black.

8. A cord-reinforced rubber component for a tire, comprising a plurality of cords encapsulated by the rubber composition of claim 1.

9. A method of forming a cord reinforced rubber assembly comprising: forming a rubber composition comprising combining 100 phr of an elastomer comprising 60-100 phr of a conjugated diene elastomer, pre-silanized silica, high surface area silica, at least 0.1 phr of a tear strength agent, a sulfur-based curative, and an accelerator for the curative; coating at least one cord with the rubber composition; and and curing the rubber composition coating the at least one cord to form a cord-reinforced rubber assembly.

10. A tire ply formed by coating a plurality of cords with a rubber composition and curing the rubber composition, the rubber composition comprising: 100 phr of an elastomer, the elastomer comprising 60-100 phr of cis-1,4-polyisoprene; 30 to 80 phr of pre-silylated precipitated silica; 1phr to 20phr with at least 200m 2 / g of CTAB surface area of ​​silica; 0.1 to 3 phr of a tear strength agent; 0.1 to 6 phr of a silica coupling agent; 0.1 to 5 phr of a cobalt salt; 0.1 to 10 phr of an antidegradant; 0.5 to 10 phr of fatty acids; 1 to 20 phr of zinc oxide; 0.1 to 10 phr of a sulfur-based curing agent; and 0.2phr to 5phr of curing accelerator.

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