Anti-ozonant and related rubber composition and rubber article

Abstract

The present disclosure relates to antiozonants and related rubber compositions and rubber articles. An antiozonant of formula (I): # imgabs0 # wherein X is selected from the group consisting of O, S and N; and wherein R is selected from the group consisting of hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety. The rubber composition contains an antiozonant and a diene elastomer; a reinforcing filler; a sulfur-based curing agent; and an accelerator for the curing agent.

Description

Technical Field

[0001] The present invention relates to a rubber composition, a rubber article formed from the rubber composition, and an anti-ozonant. Background Art

[0002] The present disclosure relates to anti-ozonants, rubber compositions containing anti-ozonants, articles comprising rubber compositions, and methods of making and using such articles. Non-limiting examples of such articles include tires.

[0003] Ozone can attack the rubber surface, thereby causing surface cracks, which can develop into deeper and / or larger cracks. Small cracks can have a negative impact on the physical appearance of rubber articles, while larger cracks can shorten the service life of such articles.

[0004] To reduce or eliminate the negative consequences of ozone attack, anti-ozonants have been developed and added to rubber compositions. A commonly used anti-ozonant is N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine or 6PPD, which is shown below.

[0005]

[0006] It is known that 6PPD interacts with ozone to form N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone or 6PPDQ, which is shown below.

[0007]

[0008] Partly due to road and rainwater runoff, 6PPDQ can contaminate waterways, and the study by Tian et al. (Zhenyu Tian et al., A ubiquitous tire rubber-derived chemical induces acute mortality in coho salmon. Science 371.185-189 (2021). DOI: 10.1126 / science.abd6951.) shows that this quinone is highly toxic to coho salmon.

[0009] It is desirable to develop new anti-ozonants that do not form 6PPDQ when exposed to ozone. Summary of the Invention

[0010] The present disclosure relates to anti-ozonants that do not form 6PPDQ when exposed to ozone, rubber compositions containing the anti-ozonant, and rubber articles comprising at least one component formed from the rubber composition.

[0011] In some embodiments, an anti-ozonant of formula (I) is disclosed:

[0012]

[0013] Wherein X is selected from O, S, and N; and wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety.

[0014] In some other embodiments, a rubber is disclosed that contains an anti-ozonant of formula (I); a diene elastomer; a reinforcing filler; a sulfur-based curing agent; and an accelerator for the curing agent.

[0015] The anti-ozonant can be included in the rubber composition in an amount of from about 0.2 phr to about 8 phr, including from about 0.5 phr to about 6 phr, and from about 2 phr to about 4 phr, per 100 phr of the diene elastomer.

[0016] In some embodiments, the diene elastomer includes at least one elastomeric material selected from polybutadiene rubber (BR), polyisoprene rubber (IR), natural rubber (NR), styrene-butadiene rubber (SBR), isobutene-isoprene rubber (HR), butadiene copolymers, and isoprene copolymers.

[0017] The diene elastomer can include at least one copolymer selected from butadiene-styrene copolymer (SBR), butadiene-isoprene copolymer (BIR), isoprene-styrene copolymer (SIR), and isoprene-butadiene-styrene copolymer (SBIR).

[0018] In some embodiments, the reinforcing filler is present in the rubber composition in an amount of from about 30 phr to about 150 phr per 100 phr of the diene elastomer.

[0019] The reinforcing filler can include at least one filler material selected from carbon black, silica, graphene, and graphite.

[0020] In some embodiments, the reinforcing filler includes carbon black.

[0021] The reinforcing filler can further include silica, optionally in combination with a silane coupling agent.

[0022] In some embodiments, the rubber composition further includes zinc oxide and / or fatty acid.

[0023] In some other embodiments, a rubber article formed from the rubber composition is disclosed.

[0024] The rubber article can be a tire or a tire component.

[0025] The present invention discloses the following embodiments:

[0026] 1. A rubber composition comprising:

[0027] A diene elastomer;

[0028] A reinforcing filler;

[0029] A sulfur-based curing agent;

[0030] An accelerator for the curing agent; and

[0031] An anti-ozonant of formula (I):

[0032]

[0033] wherein X is selected from O, S and N; and

[0034] wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety and a thiol moiety.

[0035] 2. The rubber composition according to embodiment 1, wherein the anti-ozonant is present in the rubber composition in an amount of from about 0.2 phr to about 8 phr per 100 phr of the diene elastomer.

[0036] 3. The rubber composition according to embodiment 1, wherein the anti-ozonant is present in the rubber composition in an amount of from about 0.5 phr to about 6 phr per 100 phr of the diene elastomer.

[0037] 4. The rubber composition according to embodiment 1, wherein the anti-ozonant is present in the rubber composition in an amount of from about 2 phr to about 4 phr per 100 phr of the diene elastomer.

[0038] 5. The rubber composition according to embodiment 1, wherein the diene elastomer comprises at least one elastomeric material selected from polybutadiene rubber (BR), polyisoprene rubber (IR), natural rubber (NR), styrene-butadiene rubber (SBR), isobutene-isoprene rubber (HR), butadiene copolymers and isoprene copolymers.

[0039] 6. The rubber composition according to embodiment 1, wherein the diene elastomer comprises at least one copolymer selected from butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR).

[0040] 7. The rubber composition according to embodiment 1, wherein the reinforcing filler is present in the rubber composition in an amount of from about 30 phr to about 150 phr per 100 phr of diene elastomer.

[0041] 8. The rubber composition according to embodiment 1, wherein the reinforcing filler comprises at least one filler material selected from carbon black, silica, graphene, and graphite.

[0042] 9. The rubber composition according to embodiment 1, wherein the reinforcing filler comprises carbon black.

[0043] 10. The rubber composition according to embodiment 9, wherein the reinforcing filler further comprises silica.

[0044] 11. The rubber composition according to embodiment 10, further comprising:

[0045] A silane coupling agent.

[0046] 12. The rubber composition according to embodiment 1, further comprising:

[0047] Zinc oxide.

[0048] 13. The rubber composition according to embodiment 1, further comprising:

[0049] Fatty acid.

[0050] 14. A rubber article formed from a rubber composition, the rubber composition comprising:

[0051] A diene elastomer;

[0052] A reinforcing filler;

[0053] A sulfur-based curing agent;

[0054] An accelerator for the curing agent; and

[0055] An anti-ozonant of formula (I):

[0056]

[0057] wherein X is selected from O, S, and N; and

[0058] wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety.

[0059] 15. The rubber article according to embodiment 14, wherein the reinforcing filler comprises carbon black and optionally silica.

[0060] 16. The rubber article according to embodiment 14, wherein the anti-ozonant is present in the rubber composition in an amount of from about 0.2 phr to about 15 phr per 100 phr of diene elastomer.

[0061] 17. The rubber article according to embodiment 14, wherein the anti-ozonant is present in the rubber composition in an amount of from about 0.5 phr to about 10 phr per 100 phr of diene elastomer.

[0062] 18. The rubber article according to embodiment 14, wherein the rubber article is a tire.

[0063] 19. The rubber article according to embodiment 14, wherein the rubber article is a tire assembly.

[0064] 20. An anti-ozonant of formula (I):

[0065]

[0066] wherein X is selected from O, S, and N; and

[0067] wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety.

[0068] These and other non-limiting aspects and / or objects of the present disclosure are described more particularly below. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The following is a brief description of the drawings provided to illustrate the exemplary embodiments disclosed herein and not to limit the same.

[0070] Figure 1 is a partial side view of a non-limiting example of a tire according to some embodiments of the present disclosure.

[0071] Figure 2 is a flow chart showing a non-limiting example of an article forming process according to some embodiments of the present disclosure. DETAILED EMBODIMENTS

[0072] The present disclosure can be more readily understood by reference to the following detailed description of the preferred embodiments and the drawings included herein. In the following specification and the subsequent claims, many terms will be used, and they should be defined to have the following meanings.

[0073] 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 incorporated by reference in their entirety. The materials, methods, and articles of manufacture disclosed herein are illustrative only and not intended to be limiting.

[0074] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0075] As used in the specification and claims, the term "comprising" can include embodiments of "consisting of" and "consisting essentially of". The terms "comprising", "including", "having", "containing", "may", "possessing", and variations thereof as used herein are open-ended 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 allows only the presence of the specified element / step and any impurities that may result therefrom, and excludes other elements / steps.

[0076] Unless a contrary indication is made, numerical values in the specification should be understood to include the same values when reduced to the same number of significant digits and values that differ from the specified value by less than the experimental error of the type of conventional measuring technique used to determine that particular value.

[0077] 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 a range are not limited to the exact range or value; they are sufficiently imprecise to include values approaching those ranges and / or values.

[0078] As used herein, approximating language may be used to modify any quantitative representation that can vary without resulting in a change in the basic function to which it is related. Thus, a value modified by one or more terms such as "about" and "substantially" may not be limited to the specified exact value in some instances. The modifier "about" should also be considered to disclose the range defined 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" can refer to plus or minus 10% of the indicated value. For example, "about 10%" can refer to the range from 9% to 11%, and "about 1" can refer to 0.9 - 1.1.

[0079] For the recitation of numerical ranges in this document, all intermediate numbers having the same precision therebetween are clearly contemplated. For example, for the range of 6 - 9, the numbers 7 and 8 are also contemplated in addition to 6 and 9, and for the range 6.0 - 7.0, the 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 clearly contemplated.

[0080] In the specification, the term “phr” refers to the number of parts of the respective 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.

[0081] Unless otherwise stated, the terms “rubber” and “elastomer” are used interchangeably. Unless otherwise stated, the terms “cure” and “vulcanize” are used interchangeably.

[0082] The present disclosure relates to antiozonants that do not form 6PPDQ when exposed to ozone. The antiozonants have the general formula (I)

[0083]

[0084] wherein X is selected from O, S, and N; and wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety. In some embodiments, X is O or S. In certain embodiments, X is O. In some embodiments, R is selected from an aryl moiety, an alkyl moiety, and a cycloalkyl moiety. In certain embodiments, R is an aryl moiety. Both substituted and unsubstituted moieties are encompassed. Additionally, R can be an alkyl, cycloalkyl, or aryl bearing one or more additional functional groups that are tolerant of cyclization reactions. Non-limiting examples of additional functional groups include ketones, esters, nitriles, and halogens (e.g., F, Cl, Br, I). For example, R can be a substituted alkyl moiety. In one particular embodiment, -X-R is -O-CH 2 -CH 2 -ketone. Table 1 (below) summarizes the various possible combinations of X and R.

[0085] Table 1

[0086]

[0087]

[0088] In an ozone-containing environment, the antiozonant of formula (I) can form an intermediate of formula (II) and a product of formula (III) instead of forming 6PPDQ.

[0089]

[0090] Figure 1 is a partial side view of a non - limiting example of a tire 100 according to some embodiments of the present disclosure. The tire 100 includes a tread portion 110, a bead portion 120, and a sidewall portion 130 located between the tread portion 110 and the bead portion 120. The tread portion 110, bead portion 120, and sidewall portion 130 of the tire according to the present disclosure are not limited to Figure 1 the specific configurations depicted. For example, there may be multiple sidewall portions, ribs, patterns, colors, etc. The anti - ozone agents of the present disclosure can be used in any or all tire parts. The pneumatic tire 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. In one embodiment, the tire is a passenger car or a truck tire. The tire can also be a radial tire or a bias tire.

[0091] The anti - ozone agents can also be used in other rubber products, including but not limited to non - pneumatic tires, belts, hoses, shoes, air springs, engine mounts, etc.

[0092] Figure 2 is a flow chart showing a non - limiting example of a process 240 for forming an article (such as a tire) according to some embodiments of the present disclosure. The method 240 includes providing a rubber composition 250, non - productive mixing 260, productive mixing 270, and vulcanization 280. The anti - ozone agent is typically introduced in the non - productive mixing stage 260. However, in addition to or instead of introducing in the non - productive mixing stage 260, the anti - ozone agent can also be introduced in the productive mixing stage 270.

[0093] rubber composition

[0094] Exemplary rubber compositions include an elastomeric component that includes at least one conjugated diene; a reinforcing filler component; an anti - ozone agent; and a curing package that includes a sulfur - based curing agent.

[0095] elastomeric component

[0096] Exemplary rubber compositions contain 100 phr of one or more elastomers, the elastomers including at least one conjugated diene elastomer.

[0097] Non - limiting examples of diene elastomers include polybutadiene rubber (BR), polyisoprene rubber (IR), natural rubber (NR), styrene - butadiene rubber (SBR), isobutene - isoprene rubber (HR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers. Polyisoprene includes synthetic cis - 1,4 - polyisoprene, which can be characterized as having greater than 90 mole % or greater than 98 mole % of cis - 1,4 bonds.

[0098] Non-limiting examples of elastomeric copolymer materials include butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), isoprene-styrene copolymers (SIR), and isoprene-butadiene-styrene copolymers (SBIR) and mixtures thereof.

[0099] 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 elastomeric 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, one or more elastomers consist of or consist essentially of natural rubber.

[0100] As used herein, the glass transition temperature (Tg) of an elastomer or elastomeric composition refers to one or more glass transition temperatures of the corresponding elastomer or elastomeric composition in its uncured state or, in the case of an elastomeric composition, possibly in its 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".

[0101] 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 rubber that occurs naturally and can be harvested, for example, 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 the Hevea brasiliensis tree 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.

[0102] 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.

[0103] Natural rubber is desirable for the tear properties (high tear strength), low hysteresis (relatively high heat resilience 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.

[0104] 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.

[0105] Other elastomers, which 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 in particular ethylene / propylene / dicyclopentadiene terpolymers. Additional examples of elastomers that can be used include alkoxy-methylsilyl-terminated solution-polymerized polymers (SBR, PBR, IBR and SIBR), and silicon-coupled and tin-coupled star-branched polymers.

[0106] reinforcing filler

[0107] In some embodiments, the rubber composition includes carbon black.

[0108] Representative examples of carbon black 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.

[0109] In certain embodiments, the amount of carbon black included in the rubber compositions produced by the methods disclosed herein can be, for example, from 30 phr to 150 phr, or from 40 phr to 100 phr, or from 40 phr to 80 phr. Suitable carbon blacks are any carbon blacks known in the art and suitable for a given purpose. For example, any carbon black having a BET surface area or a specific CTAB surface area of less than 400 m 2 / g, or from 20 to 200 m 2 / g can be suitable for specific embodiments based on the desired properties of the cured rubber composition. The CTAB specific surface area is the external surface area determined according to the standard AFNOR-NFT-45007 of November 1987. Suitable carbon blacks of the HAF, ISAF, and SAF types are, for example, conventionally used in tire treads.

[0110] In addition to or in place of carbon black, silica can be used as a reinforcing filler. The silica can be any reinforcing silica known to those of ordinary skill in the art, including, for example, any precipitated or pyrogenic silica having a BET surface area and a CTAB specific surface area of less than 450 m 2 / g, or from 20 to 400 m 2 / g can be suitable for specific embodiments based on the desired properties of the cured rubber composition. Specific embodiments of the rubber compositions disclosed herein can include silica having a CTAB of from 80 to 200 m 2 / g, from 100 to 190 m 2 / g, from 120 to 190 m 2 / g, or from 140 to 180 m 2 / g.

[0111] The silica can be used in combination with a silane coupling agent. Specific examples of silane coupling agents include alkoxy organosulfanyl silanes and bis(3-triethoxysilylpropyl) polysulfides having an average of 1 to 5 linked sulfur atoms (preferably 2 to 4) in their polysulfide bridges. Bis(3-triethoxysilylpropyl) polysulfides having an average of approximately 2 to approximately 2.6 and approximately 3.4 to approximately 3.8 linked sulfur atoms, respectively, in their polysulfide bridges are available as Si266 TM and Si69 TM from Evonik Industries.

[0112] 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 a 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 may be used than when the silica is treated in situ with the coupling agent.

[0113] Examples of silica dispersing 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, hydrogenated or non-hydrogenated C 5 or C 6 polyoxyethylene derivatives of 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 6 fatty acid esters of sugars (e.g., sorbose, mannose, and arabinose) include sorbitan oleates such as sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, and sorbitan sesquioleate, and sorbitan esters of lauric fatty acid, sorbitan esters of palmitic fatty acid, and sorbitan esters of stearic fatty acid. 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 the hydrogenated and non-hydrogenated fatty acid esters of sugars except that ethylene oxide groups are placed on each hydroxyl group.

[0114] Exemplary polyalkylene oxides may 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 (e.g., polyethylene glycol) is used in the rubber composition, it may 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.

[0115] Examples of commercially available polyethylene glycols include Carbowax TM PEG 3350 and Carbowax TMPEG 8000, where the number indicates the approximate weight-average molecular weight. Other polyalkylene oxide polymers may be used, such as those described in U.S. Patent Nos. 6,322,811 and 4,082,703.

[0116] If used, based on the weight of the silica, the silica dispersion aid may 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%.

[0117] Other fillers may also be included as reinforcing fillers in the elastomeric system, such as graphene, graphite, zeolite, calcium carbonate, alumina, aluminum hydroxide, clay (reinforcing grade), magnesium hydroxide, boron nitride, aluminum nitride, titanium dioxide, reinforcing zinc oxide, and combinations thereof.

[0118] other compounding ingredients

[0119] The rubber composition may include additional components such as anti-degradants, processing aids, peptizers, sulfur-based curing agents, activators, cure accelerators, and cure retarders.

[0120] Representative anti-degradants include monophenols, bisphenols, thiobisphenols, 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), etc., such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 - 346.

[0121] Exemplary processing aids include liquid plasticizers, waxes, resins, and combinations thereof. Liquid plasticizers, such as processing oils, have a T below 0 °C, typically well below 0 °C, such as below -30 °C, or below -40 °C, or below -50 °C. g such as a T from 0 °C to -100 °C gProcessing oils with relatively low concentrations assist in mixing the components of the rubber composition and / or facilitate the processing of the rubber composition. Representative processing oils that can be used 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 TM 100 from Ergon Refining, Inc., 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).

[0122] Exemplary resins that can be used 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.

[0123] In some embodiments, the rubber composition includes 1 to 10 phr of resin. In another embodiment, the rubber composition does not contain or is substantially free of resin. This is beneficial because resins can pose a potential threat to the environment, health, and safety during mixing and / or tire manufacturing processes. Therefore, it is attractive to identify compositions that have good adhesion and / or stiffness properties while avoiding resins. 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.

[0124] Suitable waxes, particularly microcrystalline waxes, may be of the type described in The Vanderbilt Rubber Handbook (1978), pages 346 and 347. The wax may be absent from the rubber composition or present in the composition in an amount of at least 1 phr or at most 5 phr.

[0125] Exemplary peptizers include pentachlorophenol dibenzoyl aminodiphenyl disulfide. The peptizer may be absent from the rubber composition or present in the composition in an amount of at least 0.1 phr, or at most 1 phr, or at most 0.4 phr.

[0126] 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 may vary depending on the type of rubber and the specific type of curing agent, but may 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 at most 8 phr, or at most 6 phr.

[0127] Exemplary activators for sulfur curing agents include fatty acids and zinc oxide. Zinc oxide may help improve the adhesion between the wire and the rubber-coated stock during sulfur curing. The rubber composition may include from 1 phr to 20 phr of zinc oxide, such as at least 5 phr, or at least 7 phr, or at most 15 phr, or at most 12 phr, or at most 10 phr of zinc oxide. Exemplary fatty acids include stearic acid and mixtures of stearic acid with other fatty acids. The rubber composition may 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 at most 10 phr, or at most 5 phr, or at most 2 phr of fatty acid.

[0128] Accelerators may 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 may be at least 0.2 phr, or at least 0.5 phr, or at least 1 phr, or at most 5 phr, or at most 3 phr.

[0129] Exemplary accelerators for sulfur-based curing agents include amines, guanidines, thioureas, thiols, thiazoles, dithiocarbamates, 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, may 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 may be used in an amount less than that of the primary accelerator. The primary accelerator may be a sulfenamide, while the secondary accelerator may be a guanidine, a dithiocarbamate, or a thiuram compound such as diphenylguanidine.

[0130] As is to be understood, the rubber composition may include other components in addition to those exemplified herein.

[0131] form a rubber composition

[0132] 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 components) 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 preceding non-productive mixing stages.

[0133] In some embodiments, in 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 up to 165 °C. The temperature of the mixture rises 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 2 to 30 minutes to incorporate the curing agent into the mixture without significantly curing the mixture.

[0134] The vulcanization of pneumatic tires 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 will be apparent to those skilled in the art.

[0135] The rubber composition generally has sufficient viscosity and uncured tack to enable it to be incorporated into the uncured tire without significantly deviating from conventional tire manufacturing techniques. In some embodiments, a strip of the rubber composition is formed.

[0136] tire construction

[0137] To form a cord-reinforced rubber assembly, such as a ply, multiple cords, which are typically arranged in parallel, are coated with the rubber composition before curing 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.

[0138] One or more plies formed from the above rubber composition can be constructed into an uncured tubeless pneumatic rubber tire before vulcanization. A tire comprising the vulcanized rubber composition is also disclosed.

[0139] In some embodiments, the tire includes one or more of a ply, such as a belt ply, a body ply, an overlay 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 calendering 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.

[0140] Tires containing plies formed from the exemplary rubber composition can be racing tires, passenger car tires, aircraft tires, agricultural tires, bulldozer tires, off-road tires, truck tires, etc. The tire can be a radial tire or a bias tire. In some embodiments, the tire is an inflated radial (medium-duty) truck tire.

[0141] WO 2022 / 146441 A1, published on July 7, 2022, and granted to Compagnie Generale Des Establissements Michelin, discloses certain aspects related to rubber compositions and is incorporated herein by reference in its entirety.

[0142] It should be 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: Diene Elastomer: Reinforced fillers; Sulfur-based curing agents; an accelerator for the curing agent; and Antiozonants of formula (I): wherein X is selected from O, S and N; and wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety. 2 . The rubber composition according to claim 1 , wherein the antiozonant is present in the rubber composition in an amount of about 0.2 phr to about 8 phr per 100 phr of diene elastomer.

3. The rubber composition of claim 1, wherein the antiozonant is present in the rubber composition in an amount of about 0.5 phr to about 6 phr per 100 phr of diene elastomer.

4. The rubber composition of claim 1, wherein the antiozonant is present in the rubber composition in an amount of about 2 phr to about 4 phr per 100 phr of diene elastomer.

5. The rubber composition according to claim 1, wherein the diene elastomer comprises at least one elastomeric material selected from the group consisting of polybutadiene rubber (BR), polyisoprene rubber (IR), natural rubber (NR), styrene-butadiene rubber (SBR), isobutylene isoprene rubber (HR), butadiene copolymers and isoprene copolymers.

6. The rubber composition according to claim 1, wherein the diene elastomer comprises at least one copolymer chosen from butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR).

7. The rubber composition according to claim 1, wherein the reinforcing filler is present in the rubber composition in an amount of about 30 phr to about 150 phr per 100 phr of diene elastomer.

8. The rubber composition according to claim 1, wherein the reinforcing filler comprises at least one filler material selected from the group consisting of carbon black, silica, graphene, and graphite.

9. A rubber article formed from a rubber composition, the rubber composition comprising: Diene elastomers; Reinforced fillers; Sulfur-based curing agents; an accelerator for the curing agent; and Antiozonants of formula (I): wherein X is selected from O, S and N; and wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety.

10. Antiozonants of formula (I): wherein X is selected from O, S and N; and wherein R is selected from hydrogen, an alkyl moiety, a cycloalkyl moiety, an aryl moiety, an amine moiety, an amide moiety, an alcohol moiety, an aldehyde moiety, a ketone moiety, a carboxylic acid moiety, an ether moiety, an ester moiety, and a thiol moiety.

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