Antiozonant and associated rubber composition and rubber article

Abstract

To provide antiozonants that do not form 6PPDQ when exposed to ozone, rubber compositions containing the antiozonants, and rubber articles including at least one component formed from the rubber compositions.SOLUTION: The present invention provides an antiozonant represented by formula (I), where X is selected from the group consisting of O, S, and N, and R is hydrogen, an alkyl moiety, a cycloalkyl moiety, or the like. A rubber composition comprises the antiozonant, a diene elastomer, a reinforcing filler, a sulfur-based curing agent, and an accelerator for a curing agent.SELECTED DRAWING: None

Description

Technical Field

[0001]

[0001] The present disclosure relates to ozone degradation inhibitors, rubber compositions containing ozone degradation inhibitors, articles containing rubber compositions, and methods for making and using the articles. Non-limiting examples of such articles include tires.

Background Art

[0002]

[0002] Ozone can attack the surface of rubber, resulting in surface cracks that can develop into deeper and / or larger cracks. Small cracks can negatively affect the physical appearance of rubber articles, and larger cracks can shorten the useful life of such articles.

[0003]

[0003] To reduce or eliminate the adverse effects of ozone attack, ozone degradation inhibitors have been developed and added to rubber compositions. One commonly used ozone degradation inhibitor is N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine or 6PPD, exemplified below.

[0004]

Chemical Formula

[0005]

[0004] It is known that 6PPD interacts with ozone to form N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone or 6PPDQ, exemplified below.

[0006]

Chemical Formula

[0007]

[0005] Due to roads and (rainwater runoff from heavy rain), 6PPDQ may contaminate waterways, and a study by Tian et al. (Zhenyu Tian et al., A ubiquitous tire rubber-derived chemical induced acute mortality in coho salmon. Science 371, 185 - 189 (2021). DOI: 10.1126 / science.abd6951.) suggests that this quinone is highly toxic to coho salmon.

[0008]

[0006] It is desirable to develop a new anti - ozone agent that does not form 6PPDQ upon exposure to ozone.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Non - Patent Documents

[0010]

Non - Patent Document 1

Non - Patent Document 2

Non - Patent Document 3

Summary of the Invention

Means for Solving the Problems

[0011]

[0007] The present disclosure relates to an ozone deterioration inhibitor that does not form 6PPDQ upon exposure to ozone, a rubber composition containing the ozone deterioration inhibitor, and a rubber article including at least one component formed from the rubber composition.

[0012]

[0008] Disclosed in some embodiments is a compound of formula (I):

Chemical Formula

[0013]

[0009] Disclosed in other embodiments is a rubber comprising an ozone deterioration inhibitor of formula (I), a diene elastomer, a reinforcing filler, a sulfur-based curing agent, and an accelerator for the curing agent.

[0014]

[0010] The ozone deterioration inhibitor may be included in the rubber composition in an amount of about 0.2 phr to about 8 phr per 100 phr of the diene elastomer, including about 0.5 phr to about 6 phr per 100 phr of the diene elastomer, and about 2 phr to about 4 phr per 100 phr of the diene elastomer.

[0015]

[0016]

[0011] In some embodiments, 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 copolymer, and isoprene copolymer.

[0017]

[0012] The diene elastomer may comprise at least one copolymer selected from the group consisting of butadiene-styrene copolymer (SBR), butadiene-isoprene copolymer (BIR), isoprene-styrene copolymer (SIR), and isoprene-butadiene-styrene copolymer (SBIR).

[0018]

[0013] In some embodiments, the reinforcing filler is present in the rubber composition in an amount of about 30 phr to about 150 phr per 100 phr of the diene elastomer.

[0019]

[0014] The reinforcing filler may comprise at least one filler material selected from the group consisting of carbon black, silica, graphene, and graphite.

[0020]

[0015] In some embodiments, the reinforcing filler comprises carbon black.

[0021]

[0016] The reinforcing filler may further comprise silica, optionally in combination with a silane coupling agent.

[0022]

[0017] In some embodiments, the rubber composition further comprises zinc oxide and / or a fatty acid.

[0023]

[0018] Further disclosed are rubber articles formed from the rubber composition.

[0024]

[0019] The rubber article may be a tire or a tire component.

[0025]

[0020] These and other non-limiting aspects and / or objectives of the present disclosure are described in more detail below.

[0026]

[0021] The following is a brief description of the drawings, which are presented for the purpose of illustrating exemplary embodiments disclosed herein and not for the purpose of limiting the same.

Brief Description of the Drawings

[0027]

Figure 1

[0022] A partial side view of a non-limiting example of a tire according to some embodiments of the present disclosure.

Figure 2

[0023] A flowchart showing a non-limiting example of an article forming process according to some embodiments of the present disclosure.

Modes for Carrying Out the Invention

[0028]

[0024] The present disclosure may be more readily understood by reference to the following detailed description of the desired embodiments included therein and the drawings. In the following specification and the appended claims, reference is made to a number of terms that are defined to have the following meanings.

[0029]

[0025] 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. Although methods and materials are described below, similar or equivalent methods and materials may 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 disclosed herein are illustrative only and not intended to be limiting.

[0030]

[0026] The singular forms "a", "an", and "the" include plural referents unless the context clearly indicates otherwise.

[0031]

[0027] As used in this specification and the claims, the term "comprising" may include embodiments "consisting of" and "consisting essentially of". The terms "comprise", "include", "having", "has", "can", "contain" and their variants as used herein are intended to be open-ended transitional phrases that require the presence of the recited components / steps and permit the presence of other components / steps. However, such recitations should be construed as also describing the composition, mixture or process as "consisting of" and "consisting essentially of" the recited components / steps, thereby allowing only the recited components / steps to be present, together with any impurities that may result therefrom, and excluding other components / steps.

[0032]

[0028] Unless indicated to the contrary, numerical values in this specification are to be understood as including numerical values that are the same when reduced to the same number of significant figures and numerical values that differ from the recited value only by less than the experimental error of conventional measurement techniques of the type used to determine a particular value.

[0033]

[0029] All ranges disclosed herein include the recited endpoints and are independently combinable (e.g., the range "2 to 10" includes the endpoints 2 and 10, as well as all intermediate values). The endpoints and any values disclosed herein are not limited to the exact ranges or values, and are sufficiently imprecise to include values approximating these ranges and / or values.

[0034] As used herein, approximate language may be applied to modify a quantitative expression that can vary without resulting in a change in the basic function to which it relates. Thus, in some cases, a value modified by terms such as "about" and "substantially" may not be limited to the specified exact value. Also, the modifier "about" should be considered to disclose a range defined by the absolute values of two endpoints. For example, the expression "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 number. For example, "about 10%" may indicate a range of 9% to 11%, and "about 1" may mean 0.9 to 1.1.

[0035]

[0031] Regarding the description of numerical ranges herein, each intervening number having the same degree of precision is explicitly contemplated. For example, for the range of 6 to 9, the numbers 7 and 8 in addition to 6 and 9 are contemplated, and for the range of 6.0 to 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 explicitly contemplated.

[0036]

[0032] As used herein, the term "phr" refers to parts of each material per 100 parts by weight of rubber or elastomer. The term "phf" refers to parts per 100 parts by weight of filler. Conventionally, the uncured rubber used in a rubber composition is 100 phr in total.

[0037]

[0033] The terms "rubber" and "elastomer" can be used interchangeably unless otherwise indicated. The terms "cure" and "vulcanize" can be used interchangeably unless otherwise indicated.

[0038]

[0034] The present disclosure relates to an anti-ozone agent that does not form 6PPDQ upon exposure to ozone. The anti-ozone agent has the general formula (I)

Chemical formula

[0039]

Table 1-1

Table 1-2

[0040]

[0035] In an ozone-containing environment, the ozone degradation inhibitor of formula (I) can form the intermediate of formula (II) and the product of formula (III) instead of forming 6PPDQ.

[0041]

Chemical formula

[0042]

[0036] 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, the bead portion 120, and the sidewall portion 130 of the tire according to the present disclosure are not limited to the specific configurations shown in FIG. 1. For example, there may be a plurality of sidewall portions, ribs, patterns, colors, etc. The ozone degradation inhibitor of the present disclosure may be used in any or all of the tire parts. The pneumatic tire may be a racing tire, a passenger car tire, an aircraft tire, an agricultural, geotechnical, off-road, truck tire, etc. In one embodiment, the tire is a passenger car or truck tire. The tire may also be a radial tire or a bias tire.

[0043]

[0037] The ozone degradation inhibitor can also be used in other rubber products including, but not limited to, non-pneumatic tires, belts, hoses, shoes, air springs, engine mounts, etc.

[0044]

[0038] Figure 2 is a flowchart showing a non-limiting example of a process 240 for forming an article (e.g., a tire) according to some embodiments of the present disclosure. The process 240 includes preparation 250 of a rubber composition, non-productive mixing 260, productive mixing 270, and vulcanization 280. The ozone degradation inhibitor is generally introduced at the non-productive mixing stage 260. However, in addition to or as an alternative to introduction at the non-productive mixing stage 260, it is also possible to introduce the ozone degradation inhibitor at the productive mixing stage 270.

[0045] Rubber composition

[0039] An exemplary rubber composition includes an elastomeric component containing at least one conjugated diene; a reinforcing filler component, an ozone degradation inhibitor; and a curing package including a sulfur-based curing agent.

[0046] Elastomeric component The exemplary rubber composition includes 100 phr of elastomers including at least one conjugated diene elastomer.

[0047]

[0041] Non-limiting examples of diene elastomers include polybutadiene rubber (BR), polyisoprene rubber (IR), natural rubber (NR), styrene-butadiene rubber (SBR), isobutylene isoprene rubber (HR) butadiene copolymers, isoprene copolymers, and mixtures of these elastomers. Polyisoprene may include synthetic cis-1,4 polyisoprene characterized by having more than 90 mol.%, or more than 98 mol.% cis-1,4 bonds.

[0048]

[0042] Non-limiting examples of elastomer copolymer materials include butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), isoprene-styrene copolymers (SIR), and isoprene-butadiene-styrene copolymers (SBIR) and mixtures thereof.

[0049]

[0043] 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 a conjugated diene elastomer. In some embodiments, the conjugated diene elastomer is selected from natural rubber, synthetic cis-1,4-polyisoprene, and mixtures thereof. In certain embodiments, the elastomer consists of or consists essentially of natural rubber.

[0050]

[0044] The glass transition temperature (T g ) of the elastomer or elastomer composition referred to herein represents the glass transition temperature of each respective elastomer or elastomer composition in the uncured state, or in the case of an elastomer composition, in the cured state. The T gThe value is determined as the midpoint of the peak at a heating rate of 10 °C per minute by a differential scanning calorimeter (DSC) in accordance with ASTM D3418-21, "Standard Test Method for Measuring the Transition Temperatures and Enthalpies of Polymer Melting and Crystallization by Differential Scanning Calorimetry".

[0051]

[0045] Since natural rubber is mainly derived from isoprene (2-methyl-1,3-butadiene), it is mainly (for example, at least 99 wt%) polyisoprene, especially cis-1,4-polyisoprene. As used herein, the term "natural rubber" means a naturally occurring rubber that can be harvested from sources such as the Hevea rubber tree and non-Hevea rubber sources (such as 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 field-grade coagulum (cup lump) derived from the Hevea brasiliensis tree is a common form of natural rubber. For example, technically graded or block rubber (TSR) is natural rubber available from Indonesia and may be referred to as Standard Indonesian Rubber (SIR), Standard Malaysian Rubber (SMR), and Standard Thai Rubber (STR). TSR is available in a number of grades including TSR10 and TSR20, and the TSR10 grade is of higher purity.

[0052]

[0046] 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.

[0053]

[0047] For the tear properties (high tear strength), low hysteresis (relatively high heat resilience properties), and good processability of the cord-reinforced rubber composite material, natural rubber is desirable. However, a small amount of synthetic polyisoprene aids in the green tack property. Synthetic polyisoprene, in particular, cis-1,4-polyisoprene having a cis content of at least 94 wt.% may be utilized. The cis-1,4 content of the synthetic polyisoprene may be at least 96 wt.%. The T g of the synthetic polyisoprene may be in the range of -60 °C to -70 °C.

[0054]

[0048] In some embodiments, the synthetic polyisoprene is not 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.

[0055]

[0049] 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 homopolymers of butadiene and its homologs and derivatives, such as methylbutadiene, dimethylbutadiene, and pentadiene, and copolymers formed from butadiene or its homologs or derivatives and other unsaturated monomers. The latter may be acetylene, such as vinylacetylene, olefins, such as isobutylene which copolymerizes with isoprene to form butyl rubber, vinyl compounds, such as acrylic acid, acrylonitrile (which copolymerizes with butadiene to form NBR), methacrylic acid, and styrene, the latter compounds which copolymerize 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 neoprene (polychloroprene), polybutadiene (including cis 1,4-polybutadiene), butyl rubber, halobutyl rubber, 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 / diene monomer (EPDM) ethylene / propylene terpolymers, particularly ethylene / propylene / dicyclopentadiene terpolymers. Further examples of elastomers that may be used include alkoxy-silyl end-functionalized solution polymerization polymers (SBR, PBR, IBR, and SIBR), and silicon coupling and tin coupling star-branched polymers.

[0056] Reinforcing filler

[0050] In some embodiments, the rubber composition includes carbon black.

[0057]

[0051] Typical 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. The iodine absorption of these carbon blacks ranges from 9 to 145 g / kg, and the DBP number is 34 cm 3 / 100 g to 150 cm 3 / 100 g.

[0058]

[0052] The carbon black contained in the rubber composition produced by the method disclosed herein may, in certain embodiments, be present in an amount, for example, of 30 phr to 150 phr, or 40 phr to 100 phr, or 40 phr to 80 phr. Suitable carbon blacks are known in the art and can be any carbon black suitable for a given purpose. For example, any carbon black with both a BET surface area and a CTAB specific surface area of less than 400 m 2 / g, or 20 to 200 m 2 / g may be suitable for certain 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. For example, suitable carbon blacks of the HAF, ISAF and SAF types have conventionally been used in tire treads.

[0059]

[0053] Silica may be useful as a reinforcing filler in addition to carbon black or as an alternative to carbon black. The silica may be any reinforcing silica known to those skilled in the art, for example, any silica with both a BET surface area and a CTAB specific surface area of less than 450 m 2 / g, or 20 to 400 m 2Precipitated or calcined silica having a BET surface area 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 of CTAB may be included.

[0060]

[0054] The silica may be used in combination with a silane coupling agent. Specific examples of the silane coupling agent include alkoxy organomercaptosilane, and bis(3-triethoxysilylpropyl) polysulfide containing an average of 1 to 5 connecting sulfur atoms (preferably 2 to 4) in the polysulfide crosslink. Bis(3-triethoxysilylpropyl) polysulfide having an average of about 2 to about 2.6 and an average of about 3.4 to about 3.8 connecting sulfur atoms in the polysulfide crosslink can be obtained from Evonik Industries as Si266 (trademark) and Si69 (trademark).

[0061]

[0055] The rubber composition may contain at least 0.1 phr, or at least 0.5 phr, or at least 1 phr, or up to 6 phr, or up to 3 phr, or up to 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 the coupling agent to the silica filler of at least 0.1:100, or at least 1:100, or at least 2:100, or up to 25:100, or up to 20:100, or up to 8:100. When the silica is pretreated with the coupling agent, less amount of the coupling agent may be used than when the silica is treated in situ with the coupling agent.

[0062]

[0056] Examples of silica dispersing aids include glycols such as alkylene glycols like fatty acids, diethylene glycol, polyethylene glycol, and polypropylene glycol, fatty acid esters of hydrogenated or non-hydrogenated C5 or C6 sugars, polyoxyethylene derivatives of fatty acid esters of hydrogenated or non-hydrogenated C5 or C6 sugars, and mixtures thereof. Exemplary fatty acids include stearic acid, palmitic acid, and oleic acid. Exemplary fatty acid esters of hydrogenated and non-hydrogenated C5 and C6 sugars (e.g., sorbose, mannose, and arabinose) include sorbitan oleates such as sorbitan monooleate, dioleate, trioleate, and sesquioleate, as well as sorbitan esters of lauric acid, palmitic acid, and stearic acid fatty acids. Exemplary polyoxyethylene derivatives of fatty acid esters of hydrogenated and non-hydrogenated C5 and C6 sugars include polysorbates and polyoxyethylene sorbitan esters, which are similar to fatty acid esters of hydrogenated and non-hydrogenated sugars except that ethylene oxide groups are arranged at each of the hydroxyl groups.

[0063]

[0057] 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 up to 15,000, or up to 12,000, or up to 10,000, or up to 8,500. When a polyalkylene oxide, such as polyethylene glycol, is utilized 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 up to 5 phr, or up to 3 phr, or up to 2 phr, or up to 1 phr, or up to 0.6 phr.

[0064]

[0058] Examples of commercially available polyethylene glycols include Carbowax™ PEG 3350 and Carbowax™ PEG 8000 from Dow Chemical, where the numbers indicate the approximate weight average molecular weight. Other polyalkylene oxide polymers as described in, for example, U.S. Patent Nos. 6,322,811 and 4,082,703 may also be used.

[0065]

[0059] When used, the silica dispersing 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 up to 25 wt.%, or up to 20 wt.%, or up to 15 wt.%, based on the weight of the silica.

[0066]

[0060] Other fillers, 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, may also be included as reinforcing fillers for the elastomeric system.

[0067] Other compounding ingredients

[0061] The rubber composition may include additional components such as antioxidants, processing aids, mastication accelerators, sulfur-based curing agents, activators, curing accelerators, and curing retarders.

[0068]

[0062] Representative antioxidants include monophenols, bisphenols, thiobisphenols, polyphenols, hydroquinone derivatives, phosphites, phosphate blends, thioesters, naphthylamines, diphenylamine, and other diarylamine derivatives, paraphenylenediamine, quinoline, and blend amines. Exemplary antioxidants include 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) and others, such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 - 346.

[0069]

[0063] Exemplary processing aids include liquid plasticizers, waxes, resins, and combinations thereof. Liquid plasticizers such as process oils have a T below 0 °C, generally well below, for example, less than -30 °C, or less than -40 °C, or less than -50 °C, for example, a T between 0 °C and -100 °C. Relatively low concentrations of process oil assist in the mixing of the components of the rubber composition and / or facilitate the processing of the rubber composition. Representative process oils that can be used in the rubber composition include aliphatic oils, aromatic oils, naphthenic oils, triglyceride oils, low polycyclic aromatic (PCA) oils such as mildly extracted solvent naphthenes (MES), treated distilled aromatic extracts (TDAE), special residual aromatic extracts (SRAE), and heavy naphthenic oils, 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 containing about 87 wt.% ricinoleic acid, 7 wt.% oleic acid, 3 wt.% linoleic acid, 2 wt.% palmitic acid, and 1 wt.% stearic acid. Examples of naphthenic process oils include Hyprene (trademark) 100 from Ergon Refining and Tufflo 100 (trademark) from Barton Solvent. The process oil may be used in the rubber composition at about 0 to about 30 phr, for example, 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 may be used as a carrier for one or more other components such as elemental sulfur. g For example, a T between 0 °C and -100 °C g and have.

[0070]

[0064] Exemplary resins that may be used in the rubber composition are generally solid or viscous at room temperature and include tackifying resins such as non-reactive phenol formaldehyde, as well as rigid resins such as reactive phenol formaldehyde resins and resorcinol or resorcinol and hexamethylenetetramine, hexakis(methoxymethyl)melamine (HMMM) resins, benzoxazine resins, and hydrocarbon resins. Examples of hydrocarbon resins include aromatic, aliphatic, and cycloaliphatic resins.

[0071]

[0065] In some embodiments, the rubber composition comprises 1 to 10 phr of resin. In another embodiment, the rubber composition does not contain or substantially does not contain resin. This is an advantage because resin can pose a potential threat to the environment, health, and safety during mixing and / or tire manufacturing. Thus, it is interesting to identify compositions that have good adhesion and / or rigidity properties while avoiding resin. In particular, the amount of resin in the composition may be less than 1 phr, or less than 0.5 phr, or less than 0.2 phr, or 0 phr.

[0072]

[0066] Suitable waxes, particularly microcrystalline waxes, may be of the types described on pages 346 and 347 of The Vanderbilt Rubber Handbook (1978). The wax may be present in the rubber composition or not present, or may be used in an amount of at least 1 phr or up to 5 phr.

[0073]

[0067] An exemplary mastication accelerator is pentachlorophenol dibenzamide diphenyl disulfide. The mastication accelerator may be present in the rubber composition or not present, or may be used in an amount of at least 0.1 phr, or up to 1 phr, or up to 0.4 phr.

[0074]

[0068] Exemplary sulfur-based curing agents include elemental sulfur (free sulfur) and sulfur-donating curing agents 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 may be in the range of 0.1 phr to 10 phr, for example 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.

[0075]

[0069] Exemplary activators for sulfur curing agents include fatty acids and zinc oxide. Zinc oxide can help improve the adhesion between the metal wire and the coated rubber compound during sulfur curing. The rubber composition may contain 1 phr to 20 phr of zinc oxide, for example 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 and other fatty acids. The rubber composition may contain fatty acids starting from 0.5 phr, for example 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 acids.

[0076]

[0070] Accelerators may be used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanizate. 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 in the rubber composition.

[0077]

[0071] Exemplary accelerators for sulfur-based curing agents include amines, guanidines, thioureas, thiols, thiazoles, thiurams, sulfenamides, dithiocarbamates, and xanthates. 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 vulcanization 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 is activated at a lower temperature than the secondary accelerator but loses its activity more rapidly. The secondary accelerator may be used in a smaller amount than the primary accelerator. The primary accelerator may be a sulfenamide, and the secondary accelerator may be a guanidine, dithiocarbamate, or thiuram compound, such as diphenylguanidine.

[0078]

[0072] As will be appreciated, the rubber composition may contain components other than those exemplified herein.

[0079] Formation of the Rubber Composition

[0073] The various components of the rubber layer may be mixed together using a convenient rubber mixing apparatus such as an internal rubber mixer. Generally, elastomers, such as butyl rubber and natural rubber, are blended in at least one non-productive mixing stage in the absence of the curing agent, and then blended in a final or productive mixing stage where the curing agent (and optionally one or more additional components) is added. In the productive mixing stage, the mixing is typically carried out at a temperature lower than the mixing temperature used in the preceding non-productive mixing stage, or at the temperature reached.

[0080]

[0074] In some embodiments, in the first non - productive stage (or stages), 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 dropped from the mixer and cooled before being returned to the mixer. In the second productive stage, the mixture is returned to the mixer with the curing agent over a period of 2 - 30 minutes to incorporate the curing agent into the mixture without significantly curing the mixture.

[0081]

[0075] The vulcanization of a pneumatic tire incorporating the rubber composition may be carried out at a temperature of 100 °C - 200 °C, for example 110 °C - 180 °C. Any of the usual vulcanization processes may be used, such as heating in a press or mold, heating by superheated steam or hot air. Such tires may be constructed, shaped, molded and cured by various methods known and readily understood by those skilled in the art.

[0082]

[0076] The rubber composition typically has a viscosity and unvulcanized tack sufficient to be incorporated into an unvulcanized tire without departing significantly from conventional tire - building techniques. In some embodiments, strips of the rubber composition are formed.

[0083] Tire Construction

[0077] To form a cord - reinforced rubber component such as a ply, a plurality of cords, generally arranged in parallel, are coated with the rubber composition before the rubber composition is cured. The coated cords may be passed through a calender that applies pressure and optionally heat to provide a ply having a relatively smooth upper and lower surface defined by the rubber composition.

[0084]

[0078] One or more plies formed from the rubber composition described above may be constructed into an uncured tubeless pneumatic rubber tire before vulcanization. Also disclosed is a tire comprising a vulcanized rubber composition.

[0085]

[0079] In some embodiments, the tire includes one or more of plies, such as belt plies, carcass plies, overlay plies (covering one or more belt plies), and ply strips (which may be spirally wound in the circumferential direction of the tire). The ply includes, for example, an exemplary rubber composition in the form of a rubber coating added to a fabric or wire material. The ply may be formed by a calendering device (e.g., a wire calender or a fabric calender). The coating includes or consists of a rubber composition according to one or more of the embodiments described herein.

[0086]

[0080] A tire including a ply formed from an exemplary rubber composition may be a racing tire, a passenger tire, an aircraft tire, an agricultural tire, a geotextile tire, an off-road tire, a truck tire, etc. The tire may be a radial or bias type tire. In some embodiments, the tire is an air radial (medium) truck tire.

[0087]

[0081] WO2022 / 146441A1 to Compagnie Generale Des Establissements Michelin, published on July 7, 2022, discloses certain aspects related to rubber compositions, which are hereby incorporated by reference in their entirety.

[0088]

[0082] It is understood that the above-disclosed, as well as variations of other features and functions or their alternatives, can be combined in many other different systems or applications. Various presently unforeseen or unexpected alternatives, modifications, variations or improvements may later be made by those skilled in the art, but these are also intended to be encompassed by the following claims.

Description of the Signs

[0089] 100 Tire 110 Tread portion 120 Bead portion 130 Sidewall part 240 Process 250 Preparation of rubber composition 260 Non-productive mixing 270 Productive mixing 280 Vulcanization

Claims

1. Diene elastomers, Reinforcing fillers, Sulfur-based hardeners, Accelerators for hardeners, and Formula (I): 【Chemistry 1】 wherein X is selected from the group consisting of O, S, and N; 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. A rubber composition comprising the antiozonant.

2. 10. The rubber composition of claim 1, wherein the antiozonant is present in the rubber composition in an amount from about 0.2 phr to about 8 phr per 100 phr of diene elastomer.

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

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

5. 2. The rubber composition of 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 copolymer, and isoprene copolymer.

6. 2. The rubber composition of claim 1, wherein the diene elastomer comprises at least one copolymer selected from the group consisting of butadiene-styrene copolymer (SBR), butadiene-isoprene copolymer (BIR), isoprene-styrene copolymer (SIR), and isoprene-butadiene-styrene copolymer (SBIR).

7. 10. The rubber composition of claim 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.

8. 10. The rubber composition of 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. The rubber composition of claim 1 , wherein the reinforcing filler comprises carbon black.

10. The rubber composition of claim 9, wherein the reinforcing filler further comprises silica.

11. The rubber composition of claim 10 further comprising a silane coupling agent.

12. The rubber composition of claim 1 further comprising zinc oxide.

13. The rubber composition of claim 1 further comprising a fatty acid.

14. Diene elastomers, Reinforcing fillers, Sulfur-based hardeners, Accelerators for hardeners, and Formula (I): 【Chemistry 2】 wherein X is selected from the group consisting of O, S, and N; 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. A rubber article formed from a rubber composition comprising the antiozonant of claim 1.

15. 15. The rubber article of claim 14, wherein the reinforcing filler comprises carbon black and optionally silica.

16. The rubber article of claim 14, wherein the antiozonant 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.

17. The rubber article of claim 14, wherein the antiozonant 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.

18. 15. The rubber article of claim 14 which is a tire.

19. 15. The rubber article of claim 14 which is a tire component.

20. Formula (I): 【Chemistry 3】 wherein X is selected from the group consisting of O, S, and N; 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. Antiozonant.

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