Fatigue- and aging-resistant rubber composition and use thereof

Abstract

The present invention provides a fatigue- and aging-resistant rubber composition and a use thereof. The rubber composition comprises the raw materials of 100 parts by mass of a diene elastomer and 1-3 parts by mass of a compound of formula A. The compound of formula A is as described in the description. The compound of formula A can significantly improve the fatigue and aging resistance of the rubber composition and prolong the service life of rubber products.

Description

Fatigue-resistant and aging-resistant rubber composition and its use Technical Field

[0001] The invention belongs to the field of rubber materials and relates to a fatigue-resistant and aging-resistant rubber composition and application thereof. Background Art

[0002] Fatigue aging occurs when rubber products are damaged or undergo irreversible changes in their structure and properties under cyclic stress and deformation. Tires, drive belts, conveyor belts, rubber springs, and rubber shock absorbers are all subject to fatigue aging. Rubber fatigue is caused by cyclic mechanical forces, but this phenomenon does not occur in isolation. The fatigue process is accompanied by thermal oxidative aging and ozone aging, resulting from the combined effects of multiple factors. Key external factors include ambient temperature, oxygen content, ozone concentration, and strain amplitude and frequency. Fatigue aging accelerates the damage of rubber products and shortens their service life. Fatigue aging resistance of rubber is typically measured by the number of cyclic stress (deformation) cycles a specimen undergoes before failure occurs. Rubber fatigue resistance is generally evaluated using flex crack tests and dynamic tensile fatigue tests. The former observes the initiation and growth of cracks in the specimen, while the latter records the number of fatigue cycles at fracture.

[0003] Paraphenylenediamine antioxidants, such as 6PPD (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) and IPPD (N-isopropyl-N′-phenyl-p-phenylenediamine), have good resistance to ozone aging and fatigue aging, and are therefore widely used in the formulation of automobile tire products.

[0004] However, when the external environment and conditions of rubber products become extremely demanding or when a longer service life is sought, technicians often simply increase the dosage of antioxidants to meet performance requirements. However, paraphenylenediamine antioxidants are prone to serious migration and discoloration issues. Increasing the dosage of antioxidants will inevitably further aggravate problems such as tire appearance quality and environmental pollution, while also increasing costs for manufacturers.

[0005] Summary of the Invention

[0006] To address the problems of the prior art, the present invention provides a rubber composition containing a compound of formula A, a method for improving the fatigue and aging resistance of the rubber composition, and the use of the compound of formula A in improving the fatigue and aging resistance of the rubber composition. The compound of formula A can significantly improve the fatigue and aging resistance of the rubber composition (including flex crack aging resistance and dynamic tensile fatigue resistance), thereby extending the service life of the rubber product.

[0007] Specifically, one aspect of the present invention provides a rubber composition, wherein the raw materials of the rubber composition include 100 parts by mass of a diene elastomer and 1-3 parts by mass, for example 1.5-2 parts by mass, of a compound of formula A:

[0008] In formula A, R1, R2 and R3 are each independently selected from a C1-C8 alkyl group.

[0009] In one or more embodiments, the raw materials of the rubber composition include two or more compounds of formula A.

[0010] In one or more embodiments, in formula A, R1 and R2 are each independently selected from C1-C3 alkyl, preferably each independently selected from methyl and ethyl.

[0011] In one or more embodiments, in formula A, R3 is selected from C3-C8 alkyl, preferably selected from C3-C6 alkyl, for example selected from C4-C6 alkyl.

[0012] In one or more embodiments, the raw materials of the rubber composition include one or more compounds selected from the group consisting of compounds of formula I, compounds of formula II, compounds of formula IV, compounds of formula VI, compounds of formula VIII, compounds of formula X, compounds of formula XII, and compounds of formula XIV:

[0013] In one or more embodiments, the raw materials of the rubber composition include two or more compounds selected from the group consisting of compounds of formula I, II, IV, VI, VIII, X, XII, and XIV.

[0014] In one or more embodiments, the raw materials of the rubber composition include two compounds selected from the group consisting of compounds of formula I, II, IV, VI, VIII, X, XII, and XIV.

[0015] In one or more embodiments, the raw materials of the rubber composition include a compound of formula I and a compound of formula II, or a compound of formula IV and a compound of formula VI, or a compound of formula VIII and a compound of formula X, or a compound of formula XII and a compound of formula XIV.

[0016] In one or more embodiments, in the raw materials of the rubber composition, the total amount of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII, and the compound of formula XIV is 1-3 parts by mass, for example, 1.5-2 parts by mass.

[0017] In one or more embodiments, in the raw materials of the rubber composition, the mass ratio of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII, and the compound of formula XIV is 1:2 to 2:1, for example, 1:1.5 to 1.5:1.

[0018] In one or more embodiments, the diene elastomer comprises natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:1.

[0019] In one or more embodiments, the raw materials of the rubber composition further include 30-70 parts by mass of a reinforcing filler; the reinforcing filler is preferably carbon black.

[0020] In one or more embodiments, the raw materials of the rubber composition further include 0.5-3 parts by mass of sulfur.

[0021] In one or more embodiments, the raw materials of the rubber composition further include 1-10 parts by mass of an active agent; preferably, the active agent is zinc oxide.

[0022] In one or more embodiments, the raw materials of the rubber composition further include 2-15 parts by mass of a softener.

[0023] In one or more embodiments, the raw materials of the rubber composition further include 0.2-2 parts by mass of an accelerator; the accelerator is preferably N-tert-butyl-2-benzothiazolesulfenamide.

[0024] Another aspect of the present invention provides a rubber product, comprising the rubber composition according to any embodiment of the present invention.

[0025] In one or more embodiments, the rubber article is a tire.

[0026] Another aspect of the present invention provides a method for improving the fatigue aging resistance of a rubber composition, the method comprising: adding 1 to 3 parts by mass, for example 1.5 to 2 parts by mass, of a compound of formula A to the raw materials of the rubber composition, based on 100 parts by mass of the diene elastomer contained in the raw materials of the rubber composition:

[0027] In formula A, R1, R2 and R3 are each independently selected from a C1-C8 alkyl group.

[0028] In one or more embodiments, in formula A, R1 and R2 are each independently selected from C1-C3 alkyl, preferably each independently selected from methyl and ethyl;

[0029] In one or more embodiments, in formula A, R3 is selected from C3-C8 alkyl, preferably selected from C3-C6 alkyl, for example selected from C4-C6 alkyl.

[0030] In one or more embodiments, the method includes adding two or more compounds of formula A to the raw materials of the rubber composition.

[0031] In one or more embodiments, the method comprises: adding one or more compounds selected from the group consisting of compounds of formula I, compounds of formula II, compounds of formula IV, compounds of formula VI, compounds of formula VIII, compounds of formula X, compounds of formula XII, and compounds of formula XIV to the raw materials of the rubber composition:

[0032] In one or more embodiments, the method includes adding two or more compounds selected from the group consisting of compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV to the raw materials of the rubber composition.

[0033] In one or more embodiments, the method includes adding two compounds selected from the group consisting of compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV to the raw materials of the rubber composition.

[0034] In one or more embodiments, the method includes adding a compound of formula I and a compound of formula II, or a compound of formula IV and a compound of formula VI, or a compound of formula VIII and a compound of formula X, or a compound of formula XII and a compound of formula XIV to the raw materials of the rubber composition.

[0035] In one or more embodiments, in the raw materials of the rubber composition, the total amount of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII, and the compound of formula XIV is 1-3 parts by mass, for example, 1.5-2 parts by mass.

[0036] In one or more embodiments, in the raw materials of the rubber composition, the mass ratio of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII, and the compound of formula XIV is 1:2 to 2:1, for example, 1:1.5 to 1.5:1.

[0037] In one or more embodiments, the diene elastomer comprises natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:1.

[0038] In one or more embodiments, the raw materials of the rubber composition further include 30-70 parts by mass of a reinforcing filler; the reinforcing filler is preferably carbon black.

[0039] In one or more embodiments, the raw materials of the rubber composition further include 0.5-3 parts by mass of sulfur.

[0040] In one or more embodiments, the raw materials of the rubber composition further include 1-10 parts by mass of an active agent; preferably, the active agent is zinc oxide.

[0041] In one or more embodiments, the raw materials of the rubber composition further include 2-15 parts by mass of a softener.

[0042] In one or more embodiments, the raw materials of the rubber composition further include 0.2-2 parts by mass of an accelerator; the accelerator is preferably N-tert-butyl-2-benzothiazolesulfenamide. DETAILED DESCRIPTION

[0043] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0044] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0045] Herein, “comprising,” “including,” “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of,” for example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to have been disclosed herein.

[0046] Throughout this document, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values ​​within those ranges (including integers and fractions).

[0047] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0048] Herein, when describing embodiments or examples, it should be understood that they are not intended to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications and equivalents of the methods and materials described herein are encompassed within the scope defined by the claims.

[0049] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0050] As used herein, an alkyl group refers to a linear or branched monovalent saturated hydrocarbon group, typically containing 1 to 18 carbon atoms (C1-C18 alkyl), for example, 1 to 8 carbon atoms (C1-C8 alkyl). Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, 1-methylpropyl, isobutyl, 1-methylbutyl, and 1,3-dimethylbutyl.

[0051] In the present invention, the compound of formula A has the following structure:

[0052] In formula A, R1, R2 and R3 are each independently selected from a C1-C8 alkyl group.

[0053] In some embodiments, R1 is selected from C1-C4 alkyl, preferably C1-C3 alkyl, for example methyl, ethyl. R1 can be located in the ortho, meta or para position relative to the -NH- group.

[0054] In some embodiments, R2 is selected from C1-C4 alkyl, preferably C1-C3 alkyl, for example methyl, ethyl. R2 can be located in the ortho or meta position of the -NH-R3 group.

[0055] In some embodiments, R3 is selected from C3-C8 alkyl, preferably C3-C6 alkyl, for example, isopropyl, 1-methylpropyl, 1-methylbutyl, 1,3-dimethylbutyl, more preferably C4-C6 alkyl.

[0056] Examples of compounds of formula A include the following compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV:

[0057] The present invention has discovered that the use of one or more compounds of Formula A in rubber compositions, particularly tire rubber compositions, can significantly improve the fatigue and aging resistance of the rubber compositions, with the improvement being superior to that achieved by the antioxidant 6PPD. Herein, the improved fatigue and aging resistance refers to improved flex crack resistance and / or dynamic tensile fatigue resistance of the rubber compositions.

[0058] The present invention also discovered that the use of two or more compounds of Formula A exhibits a significant synergistic effect in improving the fatigue aging resistance of a rubber composition compared to the use of one compound of Formula A alone. In some embodiments, the present invention uses two compounds of Formula A in the rubber composition, for example, two compounds selected from the group consisting of Formula I, Formula II, Formula IV, Formula VI, Formula VIII, Formula X, Formula XII, and Formula XIV, for example, using a compound of Formula I and a compound of Formula II, or a compound of Formula IV and a compound of Formula VI, or a compound of Formula VIII and a compound of Formula X, or a compound of Formula XII and a compound of Formula XIV in the rubber composition.

[0059] In the present invention, the compound of formula A can be prepared by a method comprising the following steps:

[0060] (1) subjecting a compound of formula B and a compound of formula C to a condensation reaction under the action of a first catalyst to obtain a condensate containing a compound of formula D and / or a compound of formula D′, and then subjecting the condensate to a reduction reaction under the action of H2 and a second catalyst to obtain a compound of formula E;

[0061] (2) subjecting the compound of formula E to a reductive alkylation reaction with an aldehyde compound or a ketone compound represented by formula F in the presence of H2 and a third catalyst to obtain a compound of formula A;

[0062] R1, R2, and R3 in Formula A, Formula B, Formula C, Formula D, and Formula E are as described in any embodiment herein, and R4 and R5 in Formula F are each independently selected from H and C1-C7 alkyl. Those skilled in the art can determine suitable R4 and R5 in Formula F based on R3 contained in the compound of Formula A.

[0063] The first catalyst used in step (1) can be one or more selected from alkali metal hydroxides, alkali metal alkoxides, quaternary ammonium bases, and combinations of alkali metal hydroxides and tetraalkylammonium halides. Suitable alkali metal hydroxides for use in the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like. Suitable alkali metal alkoxides for use in the present invention include sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium tert-butoxide, potassium tert-butoxide, sodium tert-amyl alcoholate, potassium tert-amyl alcoholate, and the like. Quaternary ammonium bases are a class of compounds with the general formula R 14NOH compound, wherein R is four identical or different aliphatic or aromatic groups. 1 It can be selected from one or more of methyl, ethyl, propyl, butyl, etc. Examples of quaternary ammonium bases suitable for the present invention include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc. The first catalyst can also be a combination of an alkali metal hydroxide and a tetraalkylammonium halide. The general formula of the tetraalkylammonium halide is R 2 4NX, where R 2 are four identical or different aliphatic or aromatic hydrocarbon groups, such as methyl, ethyl, propyl, butyl, etc., and X is a halogen atom, such as fluorine, chlorine, bromine, or iodine. Examples of the combination of an alkali metal hydroxide and a tetraalkylammonium halide include sodium hydroxide and tetrabutylammonium bromide.

[0064] The molar ratio of the first catalyst to the compound of formula B can be 0.1:1 to 2:1, preferably 0.9:1 to 1.1:1, for example 1.05:1, 1.1:1, or 1.5:1. In some embodiments, in step (1), the compound of formula B and the first catalyst are first salted, and then the compound of formula C is added dropwise to carry out a condensation reaction.

[0065] In step (1), the condensation product obtained by the condensation reaction of the compound of formula B and the compound of formula C under the action of the first catalyst may be one or both of the compound of formula D and the compound of formula D', and may also contain an azobenzene compound.

[0066] In step (1), the molar ratio of the compound of formula B to the compound of formula C can be 2:1 to 15:1, preferably 4:1 to 10:1, more preferably 5:1 to 8:1, for example 6:1, 7:1.

[0067] In step (1), the condensation reaction can be carried out at 40-90° C., preferably 65-85° C., for example, the reaction temperature can be 60° C., 70° C., 75° C., or 80° C. The condensation reaction needs to be carried out under vacuum conditions, with a pressure range of -0.09 to -0.1 MPa.

[0068] The second catalyst used in step (1) can be a porous metal catalyst or a supported metal catalyst. Porous metal catalysts are also called sponge metal catalysts. Porous metal catalysts suitable for the present invention include Raney nickel (also known as skeleton nickel), Raney cobalt, Raney copper, etc. Supported metal catalysts include a metal as a catalytic active center and a carrier for supporting the metal. The metal in the supported metal catalyst suitable for the present invention can be nickel, cobalt, copper, platinum, palladium, ruthenium, rhodium, etc., and the carrier can be carbon, alumina, silica gel, molecular sieve, etc., and the carbon used as the carrier can be activated carbon. The ratio of the amount of metal in the second catalyst to the amount of the condensate can be 0.0001:1 to 0.2:1.

[0069] In step (1), the condensate generated by the condensation reaction is subjected to a hydrogenation reduction reaction in the presence of a second catalyst to produce a compound of formula E. In step (1), the reduction reaction can be carried out at 40 to 120° C., preferably 60 to 90° C., for example, the reaction temperature can be 70° C., 75° C., or 80° C. The hydrogen pressure during the reduction reaction can be 0.5 to 5 MPa, for example, 1 MPa, 1.5 MPa, 2 MPa, or 2.5 MPa.

[0070] In step (1), the compound of formula B itself can be used as a solvent, or solvents such as toluene and xylene can be used. After the reaction in step (1) is completed, the reaction solution is filtered, washed with water, and phase separated. The organic phase is then distilled under reduced pressure to remove light components to obtain the compound of formula E.

[0071] The third catalyst used in step (2) can be the aforementioned supported metal catalyst, such as Pt / C. The molar ratio of the metal in the third catalyst to the compound of formula III can be 0.0001:1 to 0.2:1.

[0072] In step (2), after the reaction, the carbonyl carbon atom in the compound of formula F is connected to the amino nitrogen atom in the compound of formula E. Therefore, a suitable compound of formula F can be selected for reaction according to the R3 group contained in the compound of formula A to be prepared. The molar ratio of the compound of formula F to the compound of formula E can be 1:1 to 15:1, for example, 2:1, 3:1, 5:1, 8:1, 10:1. The reaction temperature of step (2) can be 40 to 150°C, for example, 50°C, 80°C, 100°C, or 120°C. The hydrogen pressure in step (2) can be 0.5 to 5 MPa, for example, 1 MPa, 1.5 MPa, 2 MPa, or 2.5 MPa.

[0073] In step (2), the compound of formula F, which is a reaction raw material, can be used as a solvent. After the reaction in step (2) is completed, the reaction solution is filtered and the light components are removed by vacuum distillation to obtain the compound of formula A.

[0074] In the present invention, liquid chromatography (LC) or gas chromatography (GC) can be used to determine whether each step of the reaction has reached the endpoint, thereby determining the appropriate reaction time.

[0075] The raw materials of the rubber composition generally include a diene elastomer, a reinforcing filler, an antioxidant, and a cross-linking agent. Herein, the rubber composition includes unvulcanized rubber and vulcanized rubber. The unvulcanized rubber can be vulcanized (cured) to produce vulcanized rubber.

[0076] The raw materials of the rubber composition of the present invention include a diene elastomer and one or more compounds of formula A as antioxidants. The total amount of compounds of formula A can be 1-3 parts by mass, for example, 1.3 parts by mass, 1.5 parts by mass, 1.8 parts by mass, 2 parts by mass, 2.2 parts by mass, or 2.5 parts by mass, based on 100 parts by mass of the diene elastomer. Unless otherwise specified herein, the weight percentages of other components in the rubber composition raw materials are calculated based on 100 parts by mass of the diene elastomer.

[0077] Herein, diene elastomer refers to an elastomer whose monomers include dienes (such as butadiene, isoprene). Suitable diene elastomers for use in the present invention can be various diene elastomers known in the art, including but not limited to one or more selected from natural rubber (NR), butadiene rubber (BR), isoprene rubber, styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), isoprene / butadiene copolymer, isoprene / styrene copolymer and isoprene / butadiene / styrene copolymer. In some preferred embodiments, the diene elastomer includes natural rubber and butadiene rubber, or is composed of natural rubber and butadiene rubber. The mass ratio of natural rubber and butadiene rubber is preferably 1: 2 to 2: 1, for example 1: 1.5 to 1.5: 1, 4.5: 5.5 to 5.5: 4.5, 1: 1.

[0078] The raw material of the rubber composition of the present invention includes one or more formula A compounds, such as two or more formula A compounds. In some embodiments, the rubber composition of the present invention does not contain other antioxidants except the formula A compound. In some embodiments, the raw material of the rubber composition of the present invention includes one or more compounds selected from formula I compound, formula II compound, formula IV compound, formula VI compound, formula VIII compound, formula X compound, formula XII compound and formula XIV compound, such as two or more compounds. In the raw material of the rubber composition of the present invention, the amount of the formula A compound can be 1-3 parts by mass, for example, can be in the range of 1.3 parts by mass, 1.5 parts by mass, 1.8 parts by mass, 2 parts by mass, 2.2 parts by mass, 2.5 parts by mass or any two of the above values. Controlling the amount of the formula A compound within the aforementioned range is conducive to ensuring the effect of improving fatigue aging resistance under lower dosage.

[0079] In a preferred embodiment, in the raw materials of the rubber composition of the present invention, the number of species of the compound of formula A is two or more. The combined use of two or more compounds of formula A in the rubber composition can achieve a synergistic effect of significantly improving fatigue aging resistance. In some embodiments, in the raw materials of the rubber composition of the present invention, the number of species of the compound of formula A is two. In some embodiments, the raw materials of the rubber composition of the present invention include two compounds selected from the group consisting of compounds of formula I, compounds of formula II, compounds of formula IV, compounds of formula VI, compounds of formula VIII, compounds of formula X, compounds of formula XII, and compounds of formula XIV. In some embodiments, the raw materials of the rubber composition of the present invention include compounds of formula I and compounds of formula II. In some embodiments, the raw materials of the rubber composition of the present invention include compounds of formula IV and compounds of formula VI. In some embodiments, the raw materials of the rubber composition of the present invention include compounds of formula VIII and compounds of formula X. In some embodiments, the raw materials of the rubber composition of the present invention include compounds of formula XII and compounds of formula XIV. In the present invention, the mass ratio of the two compounds of formula A is preferably 1:2 to 2:1, for example, it can be 1:1.5, 1:1.2, 1:1, 1.2:1, 1.5:1 or within the range of any two of the foregoing values. Controlling the mass ratio of the two compounds of formula A within the foregoing range is conducive to obtaining a synergistic effect of improving fatigue aging resistance. In a preferred embodiment, the raw materials of the rubber composition of the present invention include a compound of formula I and a compound of formula II, the total mass of the compound of formula I and the compound of formula II can be 1-3 parts by mass, for example, 1.5-2 parts by mass, and the mass ratio of the compound of formula I to the compound of formula II can be 1:2 to 2:1, for example, 1:1.5 to 1.5:1.

[0080] The raw material of rubber combination of the present invention can include reinforcing filler.In the raw material of rubber combination of the present invention, the consumption of reinforcing filler can be 30-70 mass parts, for example 40 mass parts, 45 mass parts, 50 mass parts, 55 mass parts, 60 mass parts.Be applicable to reinforcing filler of the present invention can be the conventional reinforcing filler for rubber combination, includes but not limited to be selected from one or more in carbon black, white carbon black, titanium oxide, calcium carbonate, magnesium carbonate, aluminium hydroxide, magnesium hydroxide, clay and talcum.In some preferred embodiments, reinforcing filler comprises carbon black, or reinforcing filler is carbon black.

[0081] The raw materials of the rubber composition of the present invention include a crosslinking agent, such as sulfur. The amount of sulfur in the raw materials of the rubber composition of the present invention can be 0.5-3 parts by mass, such as 1 part by mass, 1.5 parts by mass, 2 parts by mass, or 2.5 parts by mass. The sulfuric acid can be sublimed sulfur.

[0082] The raw materials of the rubber composition of the present invention may further include other ingredients commonly used in rubber compositions, including but not limited to one or more selected from the group consisting of softeners, protective waxes, active agents, and accelerators.

[0083] Softeners can be used to improve the processing properties of the rubber composition. Softeners can include petroleum softeners such as naphthenic oil, aromatic oil, process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, vaseline, etc., and can also include fatty oil softeners such as stearic acid, castor oil, linseed oil, rapeseed oil, coconut oil, waxes (such as beeswax, carnauba wax and lanolin), tall oil, linoleic acid, palmitic acid, lauric acid, etc. In the raw materials of the rubber composition of the present invention, the amount of softener can be 2-15 parts by mass, for example, 3 parts by mass, 5 parts by mass, 7 parts by mass, 8 parts by mass, 9 parts by mass, 10 parts by mass, 11 parts by mass, or 13 parts by mass. In some preferred embodiments, the softener includes aromatic oil and stearic acid, or consists of aromatic oil and stearic acid. The mass ratio of aromatic oil to stearic acid can be 1:1 to 5:1, for example, 2:1, 3:1, 3.5:1, or 4:1. In some preferred embodiments, in the raw materials of the rubber composition of the present invention, the amount of aromatic oil used is 1-10 parts by mass, for example, 5 parts by mass, 6 parts by mass, 7 parts by mass, 8 parts by mass, and 9 parts by mass; the amount of stearic acid used is 1-5 parts by mass, for example, 1.5 parts by mass, 2 parts by mass, and 3 parts by mass.

[0084] The protective wax can migrate from the interior of the rubber to the surface to form a wax film, thereby isolating the rubber surface from the external environment. The protective wax is optionally added. When the raw materials of the rubber composition of the present invention include the protective wax, the amount of the protective wax can be 1-5 mass parts, for example, 1.5 mass parts, 2 mass parts, 3 mass parts, or 4 mass parts.

[0085] Activating agent can play the effect such as accelerating vulcanization speed, improving rubber thermal conductivity, wear resistance, tear resistance.In the raw material of the rubber composition of the present invention, the consumption of activating agent can be 1-10 mass parts, for example, 2 mass parts, 3 mass parts, 4 mass parts, 5 mass parts, 6 mass parts, 7 mass parts, 8 mass parts, 9 mass parts.In some preferred embodiments, activating agent includes ZnO, or activating agent is ZnO.In some preferred embodiments, in the raw material of the rubber composition of the present invention, the consumption of ZnO is 3-8 mass parts, for example, 4 mass parts, 5 mass parts, 6 mass parts, 7 mass parts.

[0086] Accelerator is generally a vulcanization accelerator, and can be selected from one or more of sulfonamide vulcanization accelerator, thiazole vulcanization accelerator, thiuram vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization accelerator, dithiocarbamate vulcanization accelerator, aldehyde amine vulcanization accelerator, aldehyde ammonia vulcanization accelerator, imidazoline vulcanization accelerator and xanthate vulcanization accelerator. In the raw material of the rubber composition of the present invention, the consumption of accelerator can be 0.2-2 mass parts, such as 0.5 mass parts, 0.6 mass parts, 0.8 mass parts, 1 mass parts, 1.5 mass parts. In some preferred embodiments, accelerator is accelerator NS (N- tert-butyl -2- benzothiazole sulfenamide).

[0087] In addition, when necessary, the rubber composition may further include plasticizers such as DMP (dimethyl phthalate), DEP (diethyl phthalate), DBP (dibutyl phthalate), DHP (diheptyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DIDP (diisodecyl phthalate), BBP (butyl benzyl phthalate), DWP (dilauryl phthalate), and DCHP (dicyclohexyl phthalate). The amount of the plasticizer used may be a conventional amount in the art.

[0088] In some preferred embodiments, the raw materials of the rubber composition of the present invention include: 100 parts by mass of a diene elastomer, 0.5-3 parts by mass of sulfur, 1-3 parts by mass of a compound of formula A, 30-70 parts by mass of carbon black, 1-10 parts by mass of ZnO, 1-5 parts by mass of stearic acid, 1-10 parts by mass of aromatic oil and 0.2-2 parts by mass of an accelerator, or are composed of the above components; wherein the diene elastomer preferably includes natural rubber and butadiene rubber in a mass ratio of 1:2-2:1, and the accelerator is preferably accelerator NS.

[0089] The unvulcanized rubber of the present invention can be prepared by conventional rubber mixing methods, for example, by a two-stage mixing method: a first stage of thermomechanical mixing (e.g., an internal mixer) in which the rubber composition raw materials except the crosslinking agent and the accelerator are mixed, and the entire mixture is kneaded until a maximum temperature between 110° C. and 190° C. is obtained to obtain a first stage of rubber; and a second stage of thermomechanical mixing (e.g., an open mixer) in which, after the first stage of rubber has cooled, the first stage of rubber is mixed with the crosslinking agent and the accelerator until a maximum temperature below 110° C. is obtained to obtain a second stage of rubber, i.e., an unvulcanized rubber.

[0090] Vulcanized rubber can be obtained by vulcanizing (curing) the unvulcanized rubber. The vulcanization temperature is generally 130°C-200°C, for example, 140-160°C, 145±5°C. The vulcanization time depends on the vulcanization temperature, the vulcanization system, and the vulcanization kinetics, and is generally 15-60 minutes, for example, 20-40 minutes, 30±5 minutes.

[0091] The rubber composition of the present invention is used in rubber products, especially tires. Compared with the use of antioxidant 6PPD alone, the use of formula A compounds, particularly two or more formula A compounds (such as formula I compounds and formula II compounds) can significantly improve the fatigue aging resistance of rubber products. Therefore, the present invention also provides a rubber product, the rubber product containing the rubber composition as described herein. The rubber product can be a tire, rubber shoes, sealing strips, sound insulation boards, anti-vibration pads, etc. The rubber product is preferably a tire, such as sidewall rubber, tread rubber, etc.

[0092] The present invention also provides the use of a compound of formula A in improving the fatigue aging resistance of a rubber composition, and a method for improving the fatigue aging resistance of a rubber composition. Preferably, the use or method of the present invention comprises: adding 1-3 parts by mass of the compound of formula A to the raw materials of the rubber composition based on 100 parts by mass of the diene elastomer contained in the rubber composition. In the use or method of the present invention, the amount and ratio of the compound of formula A, the preferred compound of formula A, and the raw material composition of the rubber composition are preferably as described in any embodiment herein.

[0093] The present invention will be described below by way of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents, and materials used in the examples are, unless otherwise stated, conventional methods, reagents, and materials in the art. The starting compounds in the examples can all be purchased from commercial sources.

[0094] The raw materials used in the examples are: natural rubber (SCR5), Xishuangbanna Sinochem Rubber Co., Ltd.; butadiene rubber (BR9000), Shandong Yuhuang Chemical Co., Ltd.; antioxidant 6PPD, Shengao Chemical Technology Co., Ltd.; carbon black N550, zinc oxide, aromatic oil, stearic acid, sublimed sulfur and accelerator NS are all common raw materials in the rubber industry.

[0095] Preparation Example 1: Synthesis of Compounds of Formula I

[0096] (1) Synthesis of compound of formula III

[0097] In a 500 mL four-necked flask, 132.4 g (1.23 mol) of m-toluidine and 87.6 g (0.24 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added, stirred, heated to 40-50° C., and dehydrated by vacuum distillation to form a salt between TMAOH and m-toluidine. During this process, the reaction solution gradually changed from yellow to deep red. The temperature was gradually raised to 72° C. When the fraction was approximately 50% of the 25% tetramethylammonium hydroxide charge of the catalyst, 30 g (0.22 mol) of m-nitrotoluene was added dropwise under vacuum distillation (−0.098 MPa) at 72° C. for about 3 h. After the addition was complete, the mixture was kept warm for 1 h. LC monitoring was performed to obtain a condensation solution.

[0098] The condensation solution was transferred to a 500 mL stainless steel reactor, and 50 g of deionized water and 40 g of skeletal nickel catalyst were added. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 75°C and the pressure was increased to 1.5 MPa. LC monitoring was performed until the nitro and nitroso compounds were completely reduced. The reaction solution was filtered, washed with water, and phase separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 160°C) to remove light components, yielding 37.1 g of compound III (yield approximately 80%). The GC assay showed a content of >99.5%.

[0099] LC-MS (m / z): 212.22 (MH + ).

[0100] 1 H NMR (400MHz, DMSO-d6) δ 6.95-6.88 (m, 2H), 6.79 (d, J=8.3Hz, 1H), 6.48 (d, J=2.6Hz, 1H), 6.43-6.30 (m, 4H), 4.80 (s, 2H), 2.14 (s, 3H), 2.02 (s, 3H).

[0101] (2) Synthesis of compound of formula I

[0102] 37.1 g of the compound of formula III, 60 g (0.60 mol) of 4-methyl-2-pentanone, and 0.5 g of Pt / C catalyst were placed in a reactor. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 100°C and the pressure was increased to 1.5 MPa. The reaction was stopped when the content of the compound of formula III was <0.1%. The temperature was lowered, the catalyst was removed by filtration, and light components were removed by distillation at -0.1 MPa and 180°C to obtain 49.2 g of the compound of formula I (yield approximately 95%). The content was >98.5% as determined by GC. Properties: Reddish-brown solid.

[0103] LC-MS (m / z): 296.44 (MH + ).

[0104] Preparation Example 2: Synthesis of Compound of Formula II

[0105] (1) Synthesis of compound of formula III

[0106] The synthesis of the compound of formula III is the same as that in Preparation Example 1.

[0107] (2) Synthesis of compound of formula II

[0108] 30 g (0.14 mol) of the compound of formula III, 100 g (1.38 mol) of 2-butanone, and 0.6 g of Pt / C catalyst were placed in a reactor. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 80°C and the pressure was increased to 1.5 MPa. The reaction was stopped when the content of the compound of formula III was <0.1%. The temperature was lowered, the catalyst was removed by filtration, and light components were removed by distillation at -0.1 MPa and 150°C to obtain 36.7 g of the compound of formula II (yield approximately 98%). The content was >98.5% as determined by GC. Properties: Reddish-brown solid.

[0109] LC-MS (m / z): 268.40 (MH + ).

[0110] 1 H NMR (400MHz, DMSO-d6) δ 6.96-6.87 (m, 2H), 6.83 (d, J = 8.4Hz, 1H), 6.45 (d, J = 2.6Hz, 1H), 6.42-6.29 (m, 4H), 4.98 (d, J = 8.6Hz, 1H), 2.14 (s , 3H), 2.04 (s, 3H), 1.81-1.66 (m, J=6.7Hz, 1H), 1.45 (dt, J=13.9, 7.1Hz, 1H), 1.21 (dt, J=13.5, 6.8Hz, 1H), 0.89 (dd, J=16.2, 6.6Hz, 6H).

[0111] Preparation Example 3: Synthesis of Compound IV

[0112] (1) Synthesis of compound of formula V

[0113] In a 500 mL four-necked flask, 160.5 g (1.5 mol) of 2-methylaniline and 91 g (0.25 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added dropwise. The mixture was stirred and heated to 40-50° C., and dehydrated by vacuum distillation to form a salt between TMAOH and 2-methylaniline. During this process, the reaction solution gradually changed from yellow to deep red. The temperature was gradually increased to 72° C. When the fraction was approximately 50% of the 25% tetramethylammonium hydroxide solution of the catalyst, 34.3 g (0.25 mol) of 3-methylnitrobenzene was added dropwise at 72° C. under reduced pressure (−0.098 MPa) for approximately 3 hours. After the addition was complete, the mixture was incubated for 1 hour. LC monitoring was performed to obtain a condensation solution.

[0114] The condensation solution was transferred to a 500 mL stainless steel reactor, and 50 g of deionized water and 40 g of skeletal nickel catalyst were added. The reaction was replaced with hydrogen three times, and the temperature was raised to 75°C and the pressure was increased to 1.5 MPa. LC monitoring was performed until the nitro and nitroso compounds were completely reduced. The reaction was then filtered, washed with water, and the phases were separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 170°C) to remove light components, yielding 42.8 g of the compound of formula V (yield: approximately 80%). GC analysis showed a content of >98%, resulting in a light yellow solid at room temperature.

[0115] LC-MS (m / z): 212.28 (MH + ).

[0116] 1 H NMR (400MHz, CDCl3) δ7.09 (d, J=7.3Hz, 1H), 6.99 (t, J=7.7Hz, 1H), 6.91 (d, J=8.2Hz, 1H) , 6.69 (t, J=7.3Hz, 1H), 6.55 (s, 1H), 6.49 (dd, J=14.3, 5.2Hz, 2H), 4.91 (s, 1H), 3.48 (br s, 2H), 2.23 (s, 3H), 2.11 (s, 3H).

[0117] (2) Synthesis of compound of formula IV

[0118] 42.5 g (0.2 mol) of the compound of formula V, 129 g (1.5 mol) of 2-pentanone, and 0.5 g of Pt / C catalyst were placed in a reactor. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 90°C and the pressure was increased to 1.5 MPa. The reaction was stopped when the content of the compound of formula V was <0.1%. The temperature was lowered, the catalyst was removed by filtration, and light components were removed by distillation at -0.1 MPa and 180°C to obtain 53.6 g of the compound of formula IV (yield approximately 95%). The content was >98.7% as determined by GC. Properties: Reddish-brown solid.

[0119] LC-MS (m / z): 282.40 (MH + ).

[0120] Preparation Example 4: Synthesis of Compound VI

[0121] (1) Synthesis of Compound VII

[0122] In a 500mL four-necked flask, 160.5g (1.5mol) of 4-methylaniline and 100.1g (0.275mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added, and the mixture was stirred and heated to 40-50°C. The mixture was dehydrated by distillation under reduced pressure to form a salt between TMAOH and 4-methylaniline. During this process, the reaction solution gradually changed from yellow to dark red. The temperature was gradually increased to 72°C. When the fraction was approximately 50% of the amount of the 25% tetramethylammonium hydroxide solution of the catalyst, 34.3g (0.25mol) of 3-methylnitrobenzene was added dropwise under reduced pressure (-0.098MPa) at 72°C. The addition time was about 3h. After the addition was complete, the mixture was kept warm for 1h. The reaction was monitored by LC to obtain a condensation solution.

[0123] The condensation solution was transferred to a 500 mL stainless steel reactor, and 50 g of deionized water and 40 g of skeletal nickel catalyst were added. The reaction was replaced with hydrogen three times, and the temperature was raised to 75°C and the pressure was increased to 1.5 MPa. LC monitoring was performed until the nitro and nitroso compounds were completely reduced. The reaction was then filtered, washed with water, and the phases were separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 170°C) to remove light components to obtain 46.1 g of compound of formula VII (yield: approximately 86%). The GC assay showed a content of >98%, and the product was a light yellow solid at room temperature.

[0124] 1 H NMR (400MHz, CDCl3) δ7.01 (t, J=6.6Hz, 3H), 6.67-6.63 (m, 2H), 6.62 (d, J=2.5Hz, 1H ), 6.55 (dd, J=8.3, 2.6Hz, 1H), 5.02 (s, 1H), 3.38 (s, 2H), 2.29 (s, 3H), 2.19 (s, 3H).

[0125] 13 C NMR (101MHz, CDCl3) δ144.36, 142.87, 133.94, 132.41, 129.72, 127.73, 125.32, 117.69, 114.90, 113.67, 20.47, 17.99.

[0126] (2) Synthesis of Compound VI

[0127] 42.5 g (0.2 mol) of the compound of formula VII, 162.4 g (2.8 mol) of acetone, and 0.5 g of Pt / C catalyst were placed in a reactor. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 70°C and the pressure was increased to 1.5 MPa. The reaction was stopped when the content of the compound of formula VII was <0.1% by GC. The temperature was lowered, the catalyst was removed by filtration, and light components were removed by distillation at -0.1 MPa and 180°C to obtain 48.8 g of the compound of formula VI (yield: approximately 96%). The content was >98.9% as determined by GC. Properties: Reddish-brown solid.

[0128] LC-MS (m / z): 254.30 (MH + ).

[0129] Preparation Example 5: Synthesis of Compound VIII

[0130] (1) Synthesis of compound of formula IX

[0131] In a 500 mL four-necked flask, 149 g (1.23 mol) of m-ethylaniline and 87.4 g (0.24 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added, stirred, heated to 40-50° C., and dehydrated by vacuum distillation to form a salt between TMAOH and p-toluidine. During this process, the reaction solution gradually changed from yellow to deep red. The temperature was gradually raised to 72° C. When the fraction was approximately 50% of the 25% tetramethylammonium hydroxide charge of the catalyst, 30.2 g (0.22 mol) of m-nitrotoluene was added dropwise under vacuum distillation (−0.098 MPa) at 72° C. for about 3 h. After the addition was complete, the mixture was kept warm for 1 h. LC monitoring was performed to obtain a condensation solution.

[0132] The condensation solution was transferred to a 500 mL stainless steel reactor, and 50 g of deionized water and 40 g of skeletal nickel catalyst were added. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 75°C and the pressure was increased to 1.5 MPa. LC monitoring was performed until the nitro and nitroso groups were completely reduced. The reaction solution was filtered, washed with water, and phase separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 160°C) to remove light components, yielding 40.3 g of compound of formula IX (yield approximately 81%). The GC assay showed a content of >97.2%.

[0133] LC-MS (m / z): 226.20 (MH + ).

[0134] (2) Synthesis of compound of formula VIII

[0135] 38.5 g (0.17 mol) of the compound of formula IX, 100 g (1.0 mol) of 4-methyl-2-pentanone, and 0.5 g of Pt / C catalyst were placed in a reactor. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 100°C and the pressure was increased to 1.5 MPa. The reaction was stopped when the content of the compound of formula IX was <0.1%. The temperature was lowered, the catalyst was removed by filtration, and light components were removed by distillation at -0.1 MPa and 180°C to obtain 51 g of the compound of formula VIII (yield: approximately 96.5%). The content was >99.1% as determined by GC. Properties: Red liquid.

[0136] LC-MS (m / z): 310.46 (MH + ).

[0137] Preparation Example 6: Synthesis of Compound X

[0138] (1) Synthesis of Compound XI

[0139] In a 500 mL four-necked flask, 131.8 g (1.23 mol) of p-toluidine and 87.4 g (0.24 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added, stirred, heated to 40-50° C., and dehydrated by vacuum distillation to form a salt between TMAOH and p-toluidine. During this process, the reaction solution gradually changed from yellow to deep red. The temperature was gradually raised to 72° C. When the fraction was approximately 50% of the 25% tetramethylammonium hydroxide charge of the catalyst, 33.2 g (0.22 mol) of m-nitroethylbenzene was added dropwise at 72° C. under reduced pressure (−0.098 MPa) for about 3 hours. After the addition was complete, the mixture was incubated for 1 hour. LC monitoring was performed to obtain a condensation solution.

[0140] The condensation solution was transferred to a 500 mL stainless steel reactor, and 50 g of deionized water and 40 g of skeletal nickel catalyst were added. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 75°C and the pressure was increased to 1.5 MPa. LC monitoring was performed until the nitro and nitroso groups were completely reduced. The reaction solution was filtered, washed with water, and phase separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 160°C) to remove light components, yielding 42 g of compound of formula XI (yield, approximately 84.5%). The GC assay showed a content of >97%.

[0141] LC-MS (m / z): 226.20 (MH + ).

[0142] (2) Synthesis of compound of formula X

[0143] 40.7 g (0.1 g) of the compound of formula XI, 108 g (1.50 mol) of 2-butanone, and 0.5 g of Pt / C catalyst were placed in a reactor. The atmosphere was replaced with hydrogen three times, and the temperature was raised to 80°C and the pressure was increased to 1.5 MPa. The reaction was stopped when the content of the compound of formula XI was <0.1%. The temperature was lowered, the catalyst was removed by filtration, and light components were removed by distillation at -0.1 MPa and 180°C to obtain 49.8 g of the compound of formula X (yield: approximately 98%). The content was >98.2% as determined by GC. Properties: Red solid.

[0144] LC-MS (m / z): 282.21 (MH + ).

[0145] Preparation Example 7: Synthesis of Compound of Formula XII

[0146] (1) Synthesis of Compound XIII

[0147] In a 1000 mL four-necked flask, 347.9 g (3.25 mol) of o-toluidine and 200 g (0.55 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added. The mixture was stirred and heated to 60° C., and dehydrated by vacuum distillation to form a salt between TMAOH and o-toluidine. During this process, the reaction solution gradually changed from yellow to reddish brown. The temperature was gradually raised to 80° C. When the fraction was approximately half of the amount of 25% tetramethylammonium hydroxide catalyst charged, 68.5 g (0.50 mol) of o-nitrobenzene was added dropwise at 80° C. under reduced pressure (−0.097 MPa) for about 3 h. After the addition was complete, the mixture was kept warm for 1 h. The reaction was monitored by LC until the o-nitrobenzene reacted completely to obtain a condensation solution.

[0148] The condensation solution was transferred to a 500 mL stainless steel reactor, and 65 g of deionized water and 38 g of skeletal nickel catalyst were added. The atmosphere was replaced with hydrogen three times, and the temperature and pressure were raised to 78°C and 2.0 MPa. LC monitoring was performed until the nitro and nitroso compounds were completely reduced. The reaction solution was filtered, washed with water, and phase separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 180°C) to remove light components, yielding 31.8 g of compound XIII (approximately 30% yield). GC analysis indicated a content of >92.5%.

[0149] LC-MS (m / z): 212.20 (M-H+)

[0150] (2) Synthesis of compound of formula XII

[0151] 30 g (0.14 mol) of compound XIII, 120.6 g (1.4 mol) of 2-pentanone, and 0.8 g of Pt / C were placed in a reactor. The temperature was raised to 90°C, the atmosphere was replaced with hydrogen, and the pressure was increased to 1.5 MPa for reaction. When the content of compound XIII was <0.1% as determined by GC, the temperature was lowered and the reaction was stopped. Filtration and vacuum distillation (-0.1 MPa, 160°C) were performed to remove light components to yield 38 g of compound XII (yield approximately 96%). The content was >96.2% as determined by GC. Properties: Black solid.

[0152] LC-MS (m / z): 282.43 (MH + ).

[0153] Preparation Example 8: Synthesis of Compound of Formula XIV

[0154] (1) Synthesis of compound of formula XV

[0155] In a 1000 mL four-necked flask, 347.9 g (3.25 mol) of p-toluidine and 200 g (0.55 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added. The mixture was stirred and heated to 60° C., and dehydrated by vacuum distillation to form a salt between TMAOH and o-toluidine. During this process, the reaction solution gradually changed from yellow to reddish brown. The temperature was gradually raised to 80° C. When the fraction was approximately half of the amount of 25% tetramethylammonium hydroxide catalyst charged, 68.5 g (0.50 mol) of o-nitrobenzene was added dropwise at 80° C. under reduced pressure (-0.097 MPa) for about 3 h. After the addition was complete, the mixture was kept warm for 1 h. The reaction was monitored by LC until the o-nitrobenzene reacted completely to obtain a condensation solution.

[0156] The condensation solution was transferred to a 500 mL stainless steel reactor, and 65 g of deionized water and 38 g of skeletal nickel catalyst were added. The atmosphere was replaced with hydrogen three times, and the temperature and pressure were raised to 78°C and 2.0 MPa. LC monitoring was performed until the nitro and nitroso compounds were completely reduced. The reaction solution was filtered, washed with water, and phase separated. The organic phase was distilled under reduced pressure (-0.1 MPa, 180°C) to remove light components, yielding 34 g of compound XV (approximately 32% yield). GC analysis indicated a content of >93.4%.

[0157] LC-MS (m / z): 212.30 (MH + ).

[0158] (2) Synthesis of compound of formula XIV

[0159] 30 g (0.14 mol) of the compound of formula XV, 104.5 g (1.8 mol) of acetone, and 0.8 g of Pt / C were placed in a reactor. The temperature was raised to 70°C, the atmosphere was replaced with hydrogen, and the pressure was increased to 1.5 MPa for reaction. When the content of the compound of formula XV was <0.1% as determined by GC, the temperature was lowered and the reaction was terminated. The mixture was filtered and light components were removed by vacuum distillation (-0.1 MPa, 160°C) to obtain 34.7 g of the compound of formula XIV (yield, approximately 97.5%). The content was >95.8% as determined by GC. Properties: Dark red solid.

[0160] LC-MS (m / z): 240.35 (MH + ).

[0161] Examples 1-17 and Comparative Example 1

[0162] According to the formulations shown in Table 1, Table 2, and Table 3, the rubber compositions of Examples 1-17 and Comparative Example 1 were prepared using the following process:

[0163] (1) adding natural rubber and butadiene rubber into an internal mixer, and then adding carbon black, zinc oxide, stearic acid, aromatic oil and antioxidant (antioxidant 6PPD, one or two of the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII and formula XIV), and kneading until the temperature of the rubber material rises to 130° C. and the rubber is discharged to obtain a rubber section;

[0164] (2) After the first stage rubber is cooled, it is milled on an open mill, accelerator NS and sulfur are added, and the mixture is kneaded until the temperature of the rubber reaches 70°C and a sheet is produced to obtain the second stage rubber;

[0165] (3) The second-stage rubber is vulcanized (145°C×30 min) to obtain a vulcanized rubber.

[0166] Table 1: Rubber composition formula of Comparative Example 1 and Examples 1-5 (Unit: parts by mass)

[0167] Table 2: Rubber composition formulations of Examples 6-11 (unit: parts by mass)

[0168] Table 3: Rubber composition formulations of Examples 12-17 (unit: parts by mass)

[0169] Test Example 1: Flexure-cracking resistance test

[0170] The vulcanized rubber was subjected to flex-cracking performance testing in accordance with the standard GB / T 13934-2006, Rubber or Thermoplastic Rubber - Determination of Flexural Crack and Crack Growth (Demessia Type). The flexion times corresponding to the early appearance of cracks (Grade 1 and Grade 2) and specimen failure (Grade 6) were recorded, respectively. The results are shown in Tables 4, 5, and 6.

[0171] Table 4: Flex-crack resistance test results of the rubber compositions of Comparative Example 1 and Examples 1-5

[0172] Table 5: Flex-crack resistance test results of the rubber compositions of Examples 6-11

[0173] Table 6: Flex-crack resistance test results of the rubber compositions of Examples 12-17

[0174] Note: The percentage values ​​in Table 4, Table 5 and Table 6 refer to the growth rate of the flexion times of the corresponding embodiments relative to the flexion times of Comparative Example 1.

[0175] As shown in Tables 4-6, the rubber compositions of Examples 1-17 (containing the compound of Formula A) exhibit significant advantages over the rubber composition of Comparative Example 1 (containing the antioxidant 6PPD) in both early crack resistance and later crack growth rate reduction, with performance improvements exceeding 30% on average. Furthermore, Example 6 exhibited significantly better flex-crack resistance than Example 1 and Example 3; Examples 5, 7, and 8 exhibited significantly better flex-crack resistance than Example 2 and Example 4; Example 9 exhibited significantly better flex-crack resistance than Example 12 and Example 13; Example 10 exhibited significantly better flex-crack resistance than Example 14 and Example 15; and Example 11 exhibited significantly better flex-crack resistance than Example 16 and Example 17. This demonstrates that the combined use of two compounds of Formula A (e.g., the combination of a compound of Formula I and a compound of Formula II, the combination of a compound of Formula IV and a compound of Formula VI, the combination of a compound of Formula VIII and a compound of Formula X, and the combination of a compound of Formula XII and a compound of Formula XIV) exhibits a significant synergistic effect in improving flex-crack resistance. Among them, the effect of improving the flex crack resistance is most excellent when the compound of formula I and the compound of formula II are used in combination.

[0176] Test Example 2: Dynamic tensile fatigue resistance test

[0177] The vulcanized rubber was subjected to a dynamic tensile fatigue test in accordance with the standard GBT1688-2008 for the determination of tensile fatigue of vulcanized rubber. The number of cycles of reciprocating motion of the sample under the test conditions of 50% tensile deformation and 5 Hz frequency until the sample broke was recorded. The results are shown in Tables 7 and 8.

[0178] Table 7: Dynamic tensile fatigue resistance test results of the rubber compositions of Comparative Example 1 and Examples 1-8

[0179] Table 8: Dynamic tensile fatigue resistance test results of the rubber compositions of Examples 9-17

[0180] Note: The percentage values ​​in Table 7 and Table 8 refer to the growth rate of the number of stretching times at fatigue fracture of the corresponding embodiments relative to the number of stretching times at fatigue fracture of Comparative Example 1.

[0181] As can be seen from Tables 7 and 8, the dynamic tensile fatigue resistance of the rubber compositions of Examples 1-17 (containing the compound of Formula A) is significantly superior to that of the rubber composition of Comparative Example 1 (containing the antioxidant 6PPD), with the performance improvement exceeding 30% on average. In addition, the dynamic tensile fatigue resistance of Example 6 is better than that of Example 1 and Example 3; the dynamic tensile fatigue resistance of Examples 5, 7, and 8 is better than that of Example 2 and Example 4; the dynamic tensile fatigue resistance of Example 9 is better than that of Example 12 and Example 13; the dynamic tensile fatigue resistance of Example 10 is better than that of Example 14 and Example 15; and the dynamic tensile fatigue resistance of Example 11 is better than that of Example 16 and Example 17. This shows that the combination of two compounds of Formula A (for example, the combination of a compound of Formula I and a compound of Formula II, the combination of a compound of Formula IV and a compound of Formula VI, the combination of a compound of Formula VIII and a compound of Formula X, and the combination of a compound of Formula XII and a compound of Formula XIV) exhibits a synergistic effect in improving the dynamic tensile fatigue resistance. Among them, the combination of the compound of Formula I and the compound of Formula II has the most excellent effect in improving the dynamic tensile fatigue resistance.

Claims

1. A rubber composition, characterized in that: The raw materials of the rubber composition include 100 parts by mass of a diene elastomer and 1 to 3 parts by mass of two or more compounds of formula A: In formula A, R1, R2 and R3 are each independently selected from C1-C8 alkyl groups.

2. The rubber composition according to claim 1, characterized in that In formula A, R1 and R2 are each independently selected from C1-C3 alkyl, preferably each independently selected from methyl and ethyl; and / or In formula A, R3 is selected from C3-C8 alkyl, preferably selected from C3-C6 alkyl, for example selected from C4-C6 alkyl.

3. The rubber composition according to claim 1, characterized in that The raw materials of the rubber composition include two compounds selected from the group consisting of a compound of formula I, a compound of formula II, a compound of formula IV, a compound of formula VI, a compound of formula VIII, a compound of formula X, a compound of formula XII and a compound of formula XIV: Preferably, the raw materials of the rubber composition include a compound of formula I and a compound of formula II, or a compound of formula IV and a compound of formula VI, or a compound of formula VIII and a compound of formula X, or a compound of formula XII and a compound of formula XIV.

4. The rubber composition according to claim 3, characterized in that In the raw materials of the rubber composition, the total amount of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII and the compound of formula XIV is 1-3 parts by mass, for example, 1.5-2 parts by mass; and / or Among the raw materials of the rubber composition, the mass ratio of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII and the compound of formula XIV is 1:2 to 2:1, for example, 1:1.5 to 1.5:

1.

5. The rubber composition according to claim 1, characterized in that The rubber composition has one or more of the following characteristics: The diene elastomer comprises natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:1; The raw materials of the rubber composition also include 30-70 parts by mass of a reinforcing filler; the reinforcing filler is preferably carbon black; The raw materials of the rubber composition also include 0.5-3 parts by mass of sulfur; The raw materials of the rubber composition further include 1-10 parts by mass of an active agent; preferably, the active agent is zinc oxide; The raw materials of the rubber composition also include 2-15 parts by mass of a softener; The raw materials of the rubber composition also include 0.2-2 parts by mass of an accelerator; the accelerator is preferably It is N-tert-butyl-2-benzothiazole sulfenamide.

6. A rubber product, characterized in that: The rubber product comprises the rubber composition according to any one of claims 1 to 4; preferably, the rubber product is a tire.

7. A method for improving the fatigue aging resistance of a rubber composition, characterized in that: The method comprises: based on 100 parts by mass of the diene elastomer contained in the raw materials of the rubber composition, adding 1 to 3 parts by mass of two or more compounds of formula A to the raw materials of the rubber composition: In formula A, R1, R2 and R3 are each independently selected from C1-C8 alkyl; Preferably, in formula A, R1 and R2 are each independently selected from C1-C3 alkyl, preferably each independently selected from methyl and ethyl; Preferably, in formula A, R3 is selected from C3-C8 alkyl, preferably selected from C3-C6 alkyl, for example selected from C4-C6 alkyl.

8. The method according to claim 7, characterized in that The method comprises: adding two compounds selected from the group consisting of a compound of formula I, a compound of formula II, a compound of formula IV, a compound of formula VI, a compound of formula VIII, a compound of formula X, a compound of formula XII and a compound of formula XIV to the raw materials of the rubber composition: Preferably, the method comprises: adding a compound of formula I and a compound of formula II, or a compound of formula IV and a compound of formula VI, or a compound of formula VIII and a compound of formula X, or a compound of formula XII and a compound of formula XIV to the raw materials of the rubber composition.

9. The method according to claim 8, characterized in that In the raw materials of the rubber composition, the total amount of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII and the compound of formula XIV is 1-3 parts by mass, for example, 1.5-2 parts by mass; and / or Among the raw materials of the rubber composition, the mass ratio of two compounds selected from the group consisting of the compound of formula I, the compound of formula II, the compound of formula IV, the compound of formula VI, the compound of formula VIII, the compound of formula X, the compound of formula XII and the compound of formula XIV is 1:2 to 2:1, for example, 1:1.5 to 1.5:

1.

10. The method according to claim 7, characterized in that The method has one or more of the following features: The diene elastomer comprises natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:1; The raw materials of the rubber composition also include 30-70 parts by mass of a reinforcing filler; the reinforcing filler is preferably carbon black; The raw materials of the rubber composition also include 0.5-3 parts by mass of sulfur; The raw materials of the rubber composition further include 1-10 parts by mass of an active agent; preferably, the active agent is zinc oxide; The raw materials of the rubber composition also include 2-15 parts by mass of a softener; The raw materials of the rubber composition also include 0.2-2 parts by mass of an accelerator; the accelerator is preferably It is N-tert-butyl-2-benzothiazole sulfenamide.

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