Rubber composition with anti-fatigue degradation properties and its applications

Abstract

The present invention provides a rubber composition that resists fatigue degradation and its applications, wherein the raw materials of the rubber composition comprise 100 parts by mass of a diene elastomer and 1 to 3 parts by mass of a compound of formula A, the compound of formula A as described in the specification. The compound of formula A can significantly improve the fatigue degradation characteristics of the rubber composition and extend the service life of rubber products.

Description

[Technical Field]

[0001] This invention belongs to the field of rubber materials and relates to a rubber composition that resists fatigue degradation and its applications. [Background technology]

[0002] Fatigue degradation refers to damage to rubber products due to periodic stress and deformation, or irreversible changes in their structure and properties. Tires, transmission belts, conveyor belts, rubber springs, and rubber dampers all undergo fatigue degradation. While rubber fatigue is caused by periodic mechanical forces, this phenomenon does not exist in isolation. Thermal oxidation degradation and ozone degradation occur simultaneously throughout the fatigue process, resulting from the combined action of multiple factors. Major external factors include ambient temperature, oxygen content, ozone concentration, and the amount and frequency of strain. Fatigue degradation accelerates damage to rubber products and shortens their service life. The fatigue resistance of rubber usually refers to the number of periodic stresses (deformations) that a test specimen withstands before damage occurs. The fatigue resistance of rubber is generally evaluated by bending crack tests and dynamic tensile fatigue tests. The former observes the occurrence and growth of cracks in the test specimen, while the latter records the number of fatigue cycles at which the test specimen fractures.

[0003] P-phenylenediamine-based degradation inhibitors such as 6PPD (N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine) and IPPD (N-isopropyl-N'-phenyl-p-phenylenediamine) are widely used in the formulation of automotive tire products due to their excellent anti-ozone degradation and anti-fatigue degradation properties.

[0004] However, when the external environment and conditions during the use of rubber products become extremely harsh, or when a longer service life is required, engineers often simply increase the amount of degradation inhibitor used to meet the required characteristics. On the other hand, p-phenylenediamine-based degradation inhibitors all have the serious problem of discoloration due to migration, and increasing the amount of degradation inhibitor used exacerbates issues such as tire appearance quality and environmental pollution, while also leading to increased costs for companies. [Overview of the Initiative]

[0005] In view of the challenges of existing technologies, the present invention provides a rubber composition containing a compound of formula A, a method for improving the fatigue degradation properties of the rubber composition, and the application of the compound of formula A in improving the fatigue degradation properties of the rubber composition. The compound of formula A can significantly improve the fatigue degradation properties (including resistance to bending crack degradation and resistance to dynamic tensile fatigue) of the rubber composition, thereby extending the service life of rubber products.

[0006] Specifically, one aspect of the present invention provides a rubber composition comprising 100 parts by mass of a diene elastomer and 1 to 3 parts by mass, for example, 1.5 to 2 parts by mass of a compound of formula A.

[0007] [ka] In formula A, R1, R2, and R3 are each independently selected from C1-C8 alkyl groups.

[0008] In one or more embodiments, the raw materials of the rubber composition include two or more compounds of formula A.

[0009] In one or more embodiments, in formula A, R1 and R2 are each independently selected from C1-C3 alkyl groups, preferably independently selected from a methyl group and an ethyl group.

[0010] In one or more embodiments, in formula A, R3 is selected from C3-C8 alkyl groups, preferably from C3-C6 alkyl groups, for example, from C4-C6 alkyl groups.

[0011] In one or more embodiments, the raw materials for the rubber composition include one or more compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV.

[0012]

Chem.

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

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

[0015] In one or more embodiments, in the raw materials of the rubber composition, the total usage amount of two compounds selected from the compounds of formula I, the compounds of formula II, the compounds of formula IV, the compounds of formula VI, the compounds of formula VIII, the compounds of formula X, the compounds of formula XII, and the compounds of formula XIV is 1 to 3 parts by mass, for example, 1.5 to 2 parts by mass.

[0016] In one or more embodiments, in the raw materials of the rubber composition, the mass ratio of two compounds selected from the compounds of formula I, the compounds of formula II, the compounds of formula IV, the compounds of formula VI, the compounds of formula VIII, the compounds of formula X, the compounds of formula XII, and the compounds of formula XIV is 1:2 to 2:1, for example, 1:1.5 to 1.5:1.

[0017] In one or more embodiments, the diene elastomer includes natural rubber and butadiene rubber with a mass ratio of 1:2 to 2:1.

[0018] In one or more embodiments, the raw materials of the rubber composition further include 30 to 70 parts by mass of a reinforcing filler, and the reinforcing filler is preferably carbon black.

[0019] In one or more embodiments, the raw materials of the rubber composition further include 0.5 to 3 parts by mass of sulfur.

[0020] In one or more embodiments, the raw materials of the rubber composition further include 1 to 10 parts by mass of an activator, and preferably, the activator is zinc oxide.

[0021] In one or more embodiments, the raw materials of the rubber composition further include 2 to 15 parts by mass of a softening agent.

[0022] In one or more embodiments, the raw materials of the rubber composition further include 0.2 to 2 parts by mass of an accelerator, and the accelerator is preferably N-tert-butyl-2-benzothiazolesulfenamide.

[0023] Another aspect of the present invention provides a rubber product, and the rubber product includes the rubber composition according to any one of the embodiments herein.

[0024] In one or more embodiments, the rubber product is a tire.

[0025] Another aspect of the present invention provides a method for improving the anti-fatigue deterioration characteristics of a rubber composition. The method includes 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, with the mass of the diene elastomer contained in the raw materials of the rubber composition being 100 parts by mass.

[0026]

Chemical formula

[0027] In one or more embodiments, in formula A, R1 and R2 are each independently selected from C1-C3 alkyl groups, preferably independently selected from a methyl group and an ethyl group.

[0028] In one or more embodiments, in formula A, R3 is selected from C3-C8 alkyl groups, preferably from C3-C6 alkyl groups, for example, from C4-C6 alkyl groups.

[0029] In one or more embodiments, the method includes adding two or more compounds of formula A to the raw materials of a rubber composition.

[0030] In one or more embodiments, the method includes adding one or more compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV to the raw materials of a rubber composition.

[0031] [ka] In one or more embodiments, the above method includes adding two or more compounds selected from the 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.

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

[0033] 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.

[0034] In one or more embodiments, the total amount used in the raw materials of the rubber composition is 1 to 3 parts by mass, for example, 1.5 to 2 parts by mass, of two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV.

[0035] In one or more embodiments, the mass ratio of two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV in the raw materials of the rubber composition is 1:2 to 2:1, for example, 1:1.5 to 1.5:1.

[0036] In one or more embodiments, the diene elastomer comprises natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:1.

[0037] In one or more embodiments, the raw materials of the rubber composition further include 30 to 70 parts by mass of a reinforcing filler, wherein the reinforcing filler is preferably carbon black.

[0038] In one or more embodiments, the raw materials of the rubber composition further contain 0.5 to 3 parts by mass of sulfur.

[0039] In one or more embodiments, the raw materials of the rubber composition further comprise 1 to 10 parts by mass of an activator, preferably zinc oxide.

[0040] In one or more embodiments, the raw materials of the rubber composition further include 2 to 15 parts by mass of a softening agent.

[0041] In one or more embodiments, the raw materials of the rubber composition further comprise 0.2 to 2 parts by mass of an accelerator, the accelerator being preferably N-tert-butyl-2-benzothiazole sulfenamide. [Modes for carrying out the invention]

[0042] To enable those skilled in the art to understand the features and effects of the present invention, terms used in the specification and claims are generally described and defined below. Unless otherwise specified, all technical and scientific terms used herein have their ordinary meanings as understood by those skilled in the art in relation to the present invention, and in case of any inconsistency, the definitions herein shall prevail.

[0043] The theories or mechanisms described and disclosed herein, whether correct or incorrect, do not limit the scope of the present invention in any way; that is, the present invention can be implemented without being limited by any particular theory or mechanism.

[0044] In this specification, “inclusion,” “contains,” “containing,” and similar terms encompass the meanings of “essentially consisting of” and “consisting of.” For example, when “A includes B and C” is disclosed herein, “A essentially consists of B and C” and “A consists of B and C” should be considered as being disclosed herein.

[0045] In this specification, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, content, and concentrations, are provided solely for the sake of brevity and convenience. Therefore, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible secondary ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0046] In this specification, unless otherwise specified, "percent" means mass percentage and "ratio" means mass ratio.

[0047] The embodiments or examples described herein should be understood not to limit the invention. Conversely, all substitutes, improvements and equivalents of the methods and materials described herein are included within the scope limited by the claims.

[0048] For the sake of brevity, this specification does not describe all possible combinations of the various technical features in each embodiment or example. Therefore, as long as these combinations of technical features are inconsistent, each technical feature in each embodiment or example can be combined arbitrarily, and all combinations should be considered to be within the scope of this specification.

[0049] In this specification, an alkyl group means a linear or branched monovalent saturated hydrocarbon group, typically containing 1 to 18 carbon atoms (C1-C18 alkyl groups), for example, 1 to 8 carbon atoms (C1-C8 alkyl groups). Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, 1-methylpropyl, isobutyl, 1-methylbutyl, and 1,3-dimethylbutyl groups.

[0050] In the present invention, the compound of formula A has the following structure.

[0051] [ka] In formula A, R1, R2, and R3 are each independently selected from C1-C8 alkyl groups.

[0052] In some embodiments, R1 is selected from C1-C4 alkyl groups, preferably from C1-C3 alkyl groups, such as a methyl group or an ethyl group. R1 may be located at the ortho, meta, or para position of the -NH- group.

[0053] In some embodiments, R2 is selected from C1-C4 alkyl groups, preferably from C1-C3 alkyl groups, such as methyl and ethyl groups. R2 may be located at the ortho or meta position of the -NH-R3 group.

[0054] In some embodiments, R3 is selected from C3-C8 alkyl groups, preferably from C3-C6 alkyl groups, such as isopropyl, 1-methylpropyl, 1-methylbutyl, and 1,3-dimethylbutyl groups, and more preferably from C4-C6 alkyl groups.

[0055] Examples of compounds of formula A include the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV listed below.

[0056] [ka] The present invention has discovered that, in rubber compositions, particularly tire rubber compositions, the use of one or more compounds of formula A can significantly improve the fatigue degradation properties of the rubber composition, and that this improvement effect is superior to that of the degradation inhibitor 6PPD. In this specification, improvement in fatigue degradation properties refers to improvement in the flexural crack resistance and / or dynamic tensile fatigue resistance properties of the rubber composition.

[0057] The present invention has further discovered that using two or more compounds of formula A exhibits a significant synergistic effect in improving the fatigue degradation characteristics of rubber compositions compared to using one compound of formula A alone. In some embodiments, the present invention uses two compounds of formula A in a rubber composition, for example, two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV, for example, using the compound of formula I and the compound of formula II, or the compound of formula IV and the compound of formula VI, or the compound of formula VIII and the compound of formula X, or the compound of formula XII and the compound of formula XIV.

[0058] In the present invention, the compound of formula A can be produced by a method comprising the following steps.

[0059] (1) Compound B and compound C are condensed in the presence of a first catalyst to obtain a condensate containing compound D and / or compound D'. Then, the condensate is reduced in the presence of H2 and a second catalyst to obtain compound E.

[0060] [ka] (2) The compound of formula E and the aldehyde compound or ketone compound represented by formula F are subjected to a reductive alkylation reaction in the presence of H2 and a third catalyst to obtain the compound of formula A.

[0061] [ka] In formulas A, B, C, D, and E, R1, R2, and R3 are as described in any one embodiment of this specification, and in formula F, R4 and R5 are each independently selected from H and C1-C7 alkyl groups, and those skilled in the art can determine appropriate R4 and R5 in formula F based on R3 contained in the compound of formula A.

[0062] The first catalyst used in step (1) may be one or more selected from alkali metal hydroxides, alkali metal alkoxides, quaternary ammonium bases, and combinations of alkali metal hydroxides and tetraalkylammonium halides. Alkali metal hydroxides applicable to the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. Alkali metal alkoxides applicable to the present invention include sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium tert-butoxide, potassium tert-butoxide, sodium tert-amilate, potassium tert-amilate, etc. Quaternary ammonium bases are R 1 This is a general term for compounds having the general formula 4NOH, where R represents four homologous or distinct aliphatic hydrocarbon groups or aromatic hydrocarbon groups. In the quaternary ammonium bases applied to this invention, R represents... 1 The group may be one or more selected from methyl, ethyl, propyl, and butyl groups. Examples of quaternary ammonium bases applicable to the present invention include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. The first catalyst may also be a combination of an alkali metal hydroxide and a tetraalkylammonium halide. The general formula for a tetraalkylammonium halide is R 2 4NX, and R in the formula 2 is one of four homologous or distinct aliphatic or aromatic hydrocarbon groups, such as a methyl group, an ethyl group, a propyl group, or a butyl group, and X is a halogen atom, such as fluorine, chlorine, bromine, or iodine. Examples of combinations of alkali metal hydroxides and tetraalkylammonium halides include sodium hydroxide and tetrabutylammonium bromide.

[0063] 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 is first salted with the first catalyst, and then the compound of formula C is added dropwise to carry out the condensation reaction.

[0064] In step (1), the condensate formed by the condensation reaction of the compound of formula B and the compound of formula C in the presence of the first catalyst may be one or both of the compound of formula D and the compound of formula D', and may include an azobenzene compound.

[0065] 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, and more preferably 5:1 to 8.1, for example 6:1 or 7:1.

[0066] The condensation reaction in step (1) can be carried out at 40 to 90°C, preferably 65 to 85°C, for example the reaction temperature may be 60°C, 70°C, 75°C, or 80°C. The condensation reaction is carried out under vacuum conditions, with a pressure range of -0.09 to -0.1 MPa.

[0067] The second catalyst used in step (1) may be a porous metal catalyst or a supported metal catalyst. A porous metal catalyst is also called a sponge metal catalyst. Examples of porous metal catalysts applicable to the present invention include Raney nickel (also called skeleton nickel), Raney cobalt, and Raney copper. A supported metal catalyst includes a metal that serves as the catalytic active center and a support that holds the metal. Examples of metals used in the supported metal catalyst applicable to the present invention include nickel, cobalt, copper, platinum, palladium, ruthenium, and rhodium, and examples of supports include carbon, alumina, silica gel, and molecular sieves, with activated carbon being an example of the carbon used as a support. The molar ratio of the metal to the condensate in the second catalyst may be 0.0001:1 to 0.2:1.

[0068] In step (1), the condensate produced in the condensation reaction is subjected to a hydrogenation reduction reaction in the presence of a second catalyst to produce the compound of formula E. The reduction reaction in step (1) can be carried out at 40 to 120°C, preferably 60 to 90°C, for example the reaction temperature may be 70°C, 75°C, or 80°C. The hydrogen pressure in the reduction reaction may be 0.5 to 5 MPa, for example 1 MPa, 1.5 MPa, 2 MPa, or 2.5 MPa.

[0069] In step (1), the compound of formula B itself can be used as the solvent, or solvents such as toluene and xylene can be used. After the reaction in step (1) is complete, the reaction mixture is filtered, washed with water, and phase separated. The organic phase is then removed by vacuum distillation to obtain the compound of formula E.

[0070] The third catalyst used in step (2) may be the supported metal catalyst described above, for example, Pt / C. The molar ratio of the metal to the compound of formula III in the third catalyst may be 0.0001:1 to 0.2:1.

[0071] In step (2), the carbonyl carbon atom in the compound of formula F after the reaction is bonded to the amino nitrogen atom in the compound of formula E. Therefore, an appropriate compound of formula F can be selected and reacted depending on 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, or 10:1. The reaction temperature in 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.

[0072] In step (2), the compound of formula F, which is the reaction raw material, may be used as the solvent. After the reaction in step (2) is complete, the reaction solution is filtered and distilled under reduced pressure to remove light components and obtain the compound of formula A.

[0073] In the present invention, liquid chromatography (LC) or gas chromatography (GC) can be used to determine whether the reaction in each step has reached its endpoint, and to determine an appropriate reaction time.

[0074] The raw materials for rubber compositions generally include diene elastomers, reinforcing fillers, degradation inhibitors, and crosslinking agents. In this specification, rubber compositions include unvulcanized rubber and vulcanized rubber. Unvulcanized rubber can be converted into vulcanized rubber by vulcanization (curing).

[0075] The raw materials for the rubber composition of the present invention include a diene elastomer and one or more compounds of formula A as a degradation inhibitor. Here, if the amount of diene elastomer used is 100 parts by mass, the total amount of compounds of formula A used may be 1 to 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. In this specification, unless otherwise specified, the mass of the diene elastomer in the raw materials of the rubber composition is set at 100 parts by mass as the basis for calculating the parts by mass of the other components in the raw materials of the rubber composition.

[0076] In this specification, a diene elastomer refers to an elastomer whose monomer is a diene (e.g., butadiene, isoprene). The diene elastomers applicable to the present invention may be various diene elastomers well known in the art, and include, but are not limited to, one or more selected from natural rubber (NR), butadiene rubber (BR), isoprene rubber, styrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile 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 consists of natural rubber and butadiene rubber. The mass ratio of natural rubber to 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, or 1:1.

[0077] The raw materials for the rubber composition of the present invention include one or more compounds of formula A, for example, two or more compounds of formula A. In some embodiments, the rubber composition of the present invention does not contain any other degradation inhibitors other than compounds of formula A. In some embodiments, the raw materials for the rubber composition of the present invention include one or more compounds selected from compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV, for example, two or more compounds. In the raw materials for the rubber composition of the present invention, the amount of compound of formula A used may be 1 to 3 parts by mass, for example, within 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 compound of formula A used within the above range is advantageous in ensuring an improvement effect on anti-fatigue degradation characteristics with a low amount of use.

[0078] In preferred embodiments, the raw materials for the rubber composition of the present invention contain two or more types of compounds of formula A. Using two or more compounds of formula A in combination in the rubber composition can yield a synergistic effect that clearly improves the anti-fatigue degradation characteristics. In some embodiments, the raw materials for the rubber composition of the present invention contain two types of compounds of formula A. In some embodiments, the raw materials for the rubber composition of the present invention include two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV. In some embodiments, the raw materials for the rubber composition of the present invention include the compound of formula I and the compound of formula II. In some embodiments, the raw materials for the rubber composition of the present invention include the compound of formula IV and the compound of formula VI. In some embodiments, the raw materials for the rubber composition of the present invention include the compound of formula VIII and the compound of formula X. In some embodiments, the raw materials for the rubber composition of the present invention include the compound of formula XII and the compound of formula XIV. In the present invention, the mass ratio of the two compounds of formula A is preferably 1:2 to 2:1, and may be within the range of, for example, 1:1.5, 1:1.2, 1:1, 1.2:1, 1.5:1, or any two of the aforementioned values. Controlling the mass ratio of the two compounds of formula A within the aforementioned range is advantageous for obtaining a synergistic effect that improves the anti-fatigue degradation characteristics. In a preferred embodiment, the raw materials for the rubber composition of the present invention include a compound of formula I and a compound of formula II, the total mass of the compounds of formula I and formula II may be 1 to 3 parts by mass, for example 1.5 to 2 parts by mass, and the mass ratio of the compound of formula I to the compound of formula II may be 1:2 to 2:1, for example 1:1.5 to 1.5:1.

[0079] The raw materials for the rubber composition of the present invention may include a reinforcing filler. In the raw materials for the rubber composition of the present invention, the amount of reinforcing filler used may be 30 to 70 parts by mass, for example, 40 parts by mass, 45 parts by mass, 50 parts by mass, 55 parts by mass, or 60 parts by mass. The reinforcing filler applied to the present invention may be a reinforcing filler commonly used in rubber compositions, and may include, but is not limited to, one or more selected from carbon black, white carbon black, titanium dioxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay, and talc. In some preferred embodiments, the reinforcing filler includes carbon black, or the reinforcing filler is carbon black.

[0080] The raw materials for the rubber composition of the present invention include a crosslinking agent, such as sulfur. In the raw materials for the rubber composition of the present invention, the amount of sulfur used may be 0.5 to 3 parts by mass, for example, 1 part by mass, 1.5 parts by mass, 2 parts by mass, or 2.5 parts by mass. The sulfur may also be sulfurous acid.

[0081] The raw materials of the rubber composition of the present invention may further include other components commonly used in rubber compositions, and may include, but are not limited to, one or more selected from softeners, protective waxes, surfactants, and accelerators.

[0082] A softening agent can be used to improve the processability of the rubber composition. The softening agent may include petroleum-based softening agents, such as naphthenic oils, aromatic oils, processing oils, lubricating oils, paraffin, liquid paraffin, petroleum asphalt, and petrolatum. It may also include fatty oil-based softening agents, such as stearic acid, castor oil, linseed oil, rapeseed oil, coconut oil, waxes (e.g., beeswax, carnauba wax, and lanolin), tall oil, linoleic acid, palmitic acid, and lauric acid. In the raw materials of the rubber composition of the present invention, the amount of softening agent used may be 2 to 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 softening agent includes arene oil and stearic acid, or consists of arene oil and stearic acid. The mass ratio of aromatic oil to stearic acid may be 1:1 to 5:1, for example, 2:1, 3:1, 3.5:1, or 4:1. In some preferred embodiments, the amount of aromatic oil used in the raw materials of the rubber composition of the present invention is 1 to 10 parts by mass, for example, 5 parts by mass, 6 parts by mass, 7 parts by mass, 8 parts by mass, or 9 parts by mass, and the amount of stearic acid used is 1 to 5 parts by mass, for example, 1.5 parts by mass, 2 parts by mass, or 3 parts by mass.

[0083] The protective wax migrates from the inside of the rubber to the surface, forming a wax film that isolates the rubber surface from the external environment. The protective wax is added optionally. When the raw materials of the rubber composition of the present invention include protective wax, the amount of protective wax used may be 1 to 5 parts by mass, for example, 1.5 parts by mass, 2 parts by mass, 3 parts by mass, or 4 parts by mass.

[0084] The activator plays a role in accelerating the vulcanization rate and improving the thermal conductivity, abrasion resistance, and tear strength of the rubber. In the raw materials of the rubber composition of the present invention, the amount of activator used may be 1 to 10 parts by mass, for example, 2 parts by mass, 3 parts by mass, 4 parts by mass, 5 parts by mass, 6 parts by mass, 7 parts by mass, 8 parts by mass, or 9 parts by mass. In some preferred embodiments, the activator contains ZnO, or the activator is ZnO. In some preferred embodiments, in the raw materials of the rubber composition of the present invention, the amount of ZnO used is 3 to 8 parts by mass, for example, 4 parts by mass, 5 parts by mass, 6 parts by mass, or 7 parts by mass.

[0085] The accelerator is usually a vulcanization accelerator and may be one or more selected from sulfonamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiram-based vulcanization accelerators, thiourea-based vulcanization accelerators, guanidine-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehydeamine-based vulcanization accelerators, imidazoline-based vulcanization accelerators, and xanthate-based vulcanization accelerators. In the raw materials of the rubber composition of the present invention, the amount of accelerator used may be 0.2 to 2 parts by mass, for example, 0.5 parts by mass, 0.6 parts by mass, 0.8 parts by mass, 1 part by mass, or 1.5 parts by mass. In some preferred embodiments, the accelerator is accelerator NS (N-tert-butyl-2-benzothiazole sulfenamide).

[0086] Furthermore, 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) may be used in the rubber composition as needed. The amount of plasticizer used may be the amount normally used in the art.

[0087] In some preferred embodiments, the raw materials for the rubber composition of the present invention include, or consist of, 100 parts by mass of diene elastomer, 0.5 to 3 parts by mass of sulfur, 1 to 3 parts by mass of a compound of formula A, 30 to 70 parts by mass of carbon black, 1 to 10 parts by mass of ZnO, 1 to 5 parts by mass of stearic acid, 1 to 10 parts by mass of aromatic oil, and 0.2 to 2 parts by mass of an accelerator, where the diene elastomer preferably includes natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:1, and the accelerator is preferably accelerator NS.

[0088] The unvulcanized rubber of the present invention can be manufactured using conventional rubber mixing methods. For example, it can be manufactured using a two-stage mixing method. In the first stage, the raw materials of the rubber composition, excluding the crosslinking agent and accelerator, are mixed in a thermomechanical machine (e.g., an internal mixer), and the entire mixture is kneaded to a maximum temperature of 110°C to 190°C to obtain first-stage rubber. In the second stage, the mixture is kneaded in a thermomechanical machine (e.g., an open mill), the first-stage rubber is cooled, and then the first-stage rubber, crosslinking agent, and accelerator are kneaded together to a maximum temperature of 110°C or lower to obtain second-stage rubber, i.e., unvulcanized rubber.

[0089] Vulcanized rubber can be obtained by vulcanizing (solidifying) unvulcanized rubber. The vulcanization temperature is typically 130°C to 200°C, for example, 140°C to 160°C or 145±5°C. The vulcanization time depends on the vulcanization temperature, vulcanization system, and vulcanization kinetics, but is typically 15 to 60 minutes, for example, 20 to 40 minutes or 30±5 minutes.

[0090] The rubber composition of the present invention is used in rubber products, particularly tires. Compared to using the degradation inhibitor 6PPD alone, using a compound of formula A, particularly two or more compounds of formula A (e.g., a compound of formula I and a compound of formula II), can clearly improve the fatigue degradation characteristics of the rubber product. Accordingly, the present invention further provides rubber products, which include the rubber composition according to this specification. Examples of rubber products include tires, rubber shoes, sealing materials, soundproofing panels, and vibration-damping pads. Preferably, the rubber product is a tire, such as sidewall rubber or tread rubber.

[0091] The present invention further provides applications of the compound of formula A in improving the fatigue degradation properties of rubber compositions, and methods for improving the fatigue degradation properties of rubber compositions. Preferably, the applications or methods of the present invention include adding 1 to 3 parts by mass of the compound of formula A to the raw materials of a rubber composition, with the mass of the diene elastomer contained in the rubber composition being 100 parts by mass. In the applications or methods of the present invention, the amount and ratio of the compound of formula A used, preferred compounds of formula A, and raw material components of the rubber composition are preferably as described in any one embodiment of this specification.

[0092] The present invention will be explained below with specific examples. These examples are for illustrative purposes only and are not intended to intentionally limit the scope of the present invention. Unless otherwise noted, the methods, reagents, and materials used in the examples are those well known in the art. All raw material compounds used in the examples are commercially available.

[0093] The sources of the raw materials used in the examples are as follows: Natural rubber (SCR5), Xishuangbanna Zhonghua Rubber Co., Ltd. Butadiene rubber (BR9000), Shandong Yuhuang Chemical Co., Ltd. Degradation inhibitor 6PPD, Sheng'ao Chemical Technology Co., Ltd. Carbon black N550, zinc oxide, aromatic oil, stearic acid, sulfur, and accelerator NS are all common raw materials in the rubber industry.

[0094] Manufacturing Example 1: Synthesis of the compound of formula I (1) Synthesis of the compound of formula III 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. The mixture was heated to 40-50°C while stirring, and dehydration was carried out by vacuum distillation to form a salt between TMAOH and m-toluidine. During this process, the color of the reaction solution gradually changed from yellow to dark red. The temperature was gradually raised to 72°C, and when the fraction reached approximately 50% of the amount of 25% tetramethylammonium hydroxide used as a catalyst, 30 g (0.22 mol) of m-nitrotoluene was added dropwise for about 3 hours while distilling under reduced pressure (-0.098 MPa) at 72°C. After the addition was complete, the mixture was kept warm for 1 hour, and the completion of the reaction of m-nitrotoluene was confirmed by LC to obtain the condensate.

[0095] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 50 g of deionized water and 40 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 75°C and 1.5 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. The reaction solution was filtered, washed with water, and phase separated. The organic phase was then removed by vacuum distillation (-0.1 MPa, 160°C) to obtain 37.1 g of the compound of formula III (yield approximately 80%), and GC measurement showed a content of >99.5%.

[0096] [ka] LC-MS (m / z): 212.22 (MH) + ). 1 H NMR (400 MHz, DMSO-d6) δ 6.95-6.88 (m, 2H), 6.79 (d, J= 8.3 Hz, 1H), 6.48 (d, J = 2.6 Hz, 1H), 6.43-6.30 (m, 4H), 4.80 (s, 2H), 2.14 (s, 3H), 2.02 (s, 3H).

[0097] (2) Synthesis of the compound of formula I 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 charged into a reaction kettle. After replacing with hydrogen gas three times, the temperature was raised to 100 °C and the pressure was increased to 1.5 MPa to carry out the reaction. After confirming by GC measurement that the content of compound X-6 was <0.1%, the reaction was stopped. The temperature was lowered, the catalyst was removed by filtration, and the light components were removed by vacuum distillation at -0.1 MPa and 180 °C to obtain 49.2 g of the compound of formula I (yield about 95%). The content was >98.5% by GC measurement. Appearance: Reddish-brown solid.

[0098]

Chem.

[0099] Production Example 2: Synthesis of the compound of formula II (1) Synthesis of the compound of formula III The synthesis of the compound of formula III is the same as that in Production Example 1.

[0100] (2) Synthesis of the compound of formula II 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 charged into a reaction kettle. After replacing with hydrogen gas three times, the temperature was raised to 80 °C and the pressure was increased to 1.5 MPa to carry out the reaction. When it was confirmed by GC measurement that the content of the compound of formula III was <0.1%, the reaction was stopped. The temperature was lowered, the catalyst was removed by filtration, and the light components were removed by vacuum distillation at -0.1 MPa and 150 °C to obtain 36.7 g of the compound of formula II (yield about 98%). The content was >98.5% by GC measurement. Appearance: Reddish-brown solid.

[0101]

Chem.

[0102] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 50 g of deionized water and 40 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 75°C and 1.5 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. Next, the mixture was filtered, washed with water, and phase separated. The organic phase was then subjected to vacuum distillation (-0.1 MPa, 170°C) to remove light components, yielding 42.8 g of compound V (yield approximately 80%). GC measurement showed a content of >98%, and the compound was a pale yellow solid at room temperature.

[0103] [ka] LC-MS (m / z): 212.28 (MH) + ). 1 H NMR (400 MHz, CDCl3) δ 7.09 (d, J = 7.3 Hz, 1H), 6.99 (t, J = 7.7 Hz, 1H), 6.91 (d, J = 8.2 Hz, 1H), 6.69 (t, J = 7.3 Hz, 1H), 6.55 (s, 1H), 6.49 (dd, J = 14.3, 5.2 Hz, 2H), 4.91 (s, 1H), 3.48 (br s, 2H), 2.23 (s, 3H), 2.11 (s, 3H).

[0104] (2) Synthesis of the compound of formula IV 42.5 g (0.2 mol) of compound V, 129 g (1.5 mol) of 2-pentanone, and 0.5 g of Pt / buta catalyst were placed in a reaction vessel. After purging with hydrogen gas three times, the temperature was raised and pressurized to 90°C and 1.5 MPa to carry out the reaction. GC measurement confirmed that the content of compound V was <0.1%, after which the reaction was stopped. The mixture was cooled, the catalyst was removed by filtration, and light components were removed by vacuum distillation at -0.1 MPa and 180°C to obtain 53.6 g of compound IV (yield approximately 95%), and GC measurement confirmed a content of >98.7%. Properties: Reddish-brown solid.

[0105] [ka] LC-MS (m / z): 282.40 (MH) + ).

[0106] Manufacturing Example 4: Synthesis of the compound of formula VI (1) Synthesis of compound VII In a 500 mL four-necked flask, 160.5 g (1.5 mol) of 4-methylaniline and 100.1 g (0.275 mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added. The mixture was heated to 40-50°C while stirring, and dehydration was carried out by vacuum distillation to form a salt between TMAOH and 4-methylaniline. During this process, the color of the reaction solution gradually changed from yellow to dark red. The temperature was gradually raised to 72°C, and when the fraction reached 50% of the amount of 25% tetramethylammonium hydroxide solution used as a catalyst, 34.3 g (0.25 mol) of 3-nitrotoluene was added dropwise for approximately 3 hours while distilling under reduced pressure (-0.098 MPa) at 72°C. After the addition was complete, the mixture was kept warm for 1 hour, and the completion of the reaction of 3-nitrotoluene was confirmed by LC to obtain the condensate.

[0107] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 50 g of deionized water and 40 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 75°C and 1.5 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. Next, the mixture was filtered, washed with water, and phase separated. The organic phase was then subjected to vacuum distillation (-0.1 MPa, 170°C) to remove light components, yielding 46.1 g of the compound of formula VII (yield approximately 86%). GC measurement showed a content of >98%, and it was a pale yellow solid at room temperature.

[0108] [ka] 1 H NMR (400 MHz, CDCl3) δ 7.01 (t, J = 6.6 Hz, 3H), 6.67-6.63 (m, 2H), 6.62 (d, J = 2.5 Hz, 1H), 6.55 (dd, J = 8.3, 2.6 Hz, 1H), 5.02 (s, 1H), 3.38 (s, 2H), 2.29 (s, 3H), 2.19 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 144.36, 142.87, 133.94, 132.41, 129.72, 127.73, 125.32, 117.69, 114.90, 113.67, 20.47, 17.99.

[0109] (2) Synthesis of compound VI 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 reaction vessel. After three purgings with hydrogen gas, the temperature was raised and the pressure increased to 70°C and 1.5 MPa to carry out the reaction. GC measurement confirmed that the content of the compound of formula VII was <0.1%, after which the reaction was stopped. The mixture was cooled, the catalyst was removed by filtration, and light components were removed by vacuum distillation at -0.1 MPa and 180°C to obtain 48.8 g of the compound of formula VI (yield approximately 96%), and GC measurement confirmed a content of >98.9%. Properties: Reddish-brown solid.

[0110] [ka] LC-MS (m / z): 254.30 (MH) + ).

[0111] Manufacturing Example 5: Synthesis of the compound of formula VIII (1) Synthesis of the compound of formula IX 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. The mixture was heated to 40-50°C while stirring, and dehydration was carried out by vacuum distillation to form a salt between TMAOH and p-toluidine. During this process, the color of the reaction solution gradually changed from yellow to dark red. The temperature was gradually raised to 72°C, and when the fraction reached approximately 50% of the amount of 25% tetramethylammonium hydroxide used as a catalyst, 30.2 g (0.22 mol) of m-nitrotoluene was added dropwise for about 3 hours while distilling under reduced pressure (-0.098 MPa) at 72°C. After the addition was complete, the mixture was kept warm for 1 hour, and the completion of the reaction of m-nitrotoluene was confirmed by LC to obtain the condensate.

[0112] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 50 g of deionized water and 40 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 75°C and 1.5 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. The reaction solution was filtered, washed with water, and phase separated. The organic phase was then removed by vacuum distillation (-0.1 MPa, 160°C) to obtain 40.3 g of the compound of formula IX (yield approximately 81%), and GC measurement showed a content of >97.2%.

[0113] [ka] LC-MS (m / z): 226.20 (MH) + ).

[0114] (2) Synthesis of the compound of formula VIII 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 reaction vessel. After three purgings with hydrogen gas, the temperature and pressure were increased to 100°C and 1.5 MPa to carry out the reaction. GC measurement confirmed that the content of the compound of formula IX was <0.1%, after which the reaction was stopped. The mixture was cooled, the catalyst was removed by filtration, and light components were removed by vacuum distillation at -0.1 MPa and 180°C to obtain 51 g of the compound of formula VIII (yield approximately 96.5%), and GC measurement confirmed a content of >99.1%. Properties: Red liquid.

[0115] [ka] LC-MS (m / z): 310.46 (MH) + ).

[0116] Manufacturing Example 6: Synthesis of Compound X (1) Synthesis of the compound of formula XI 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. The mixture was heated to 40-50°C while stirring, and dehydration was carried out by vacuum distillation to form a salt between TMAOH and p-toluidine. During this process, the color of the reaction solution gradually changed from yellow to dark red. The temperature was gradually raised to 72°C, and when the fraction reached approximately 50% of the amount of 25% tetramethylammonium hydroxide used as a catalyst, 33.2 g (0.22 mol) of m-nitroethylbenzene was added dropwise for about 3 hours while distilling under reduced pressure (-0.098 MPa) at 72°C. After the addition was complete, the mixture was kept warm for 1 hour, and the completion of the reaction of m-nitrotoluene was confirmed by LC to obtain the condensate.

[0117] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 50 g of deionized water and 40 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 75°C and 1.5 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. The reaction solution was filtered, washed with water, and phase separated. The organic phase was then removed by vacuum distillation (-0.1 MPa, 160°C) to obtain 42 g of the compound of formula XI (yield approximately 84.5%), and GC measurement showed a content of >97%.

[0118] [ka] LC-MS (m / z): 226.20 (MH) + ).

[0119] (2) Synthesis of the compound of formula X 40.7 g (0.18) 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 reaction vessel. After three purgings with hydrogen gas, the temperature was raised and pressurized to 80°C and 1.5 MPa to carry out the reaction. GC measurement confirmed that the content of the compound of formula XI was <0.1%, after which the reaction was stopped. The mixture was cooled, the catalyst was removed by filtration, and light components were removed by vacuum distillation at -0.1 MPa and 180°C to obtain 49.8 g of the compound of formula X (yield approximately 98%), and GC measurement confirmed a content of >98.2%. Properties: Red solid.

[0120] [ka] LC-MS (m / z): 282.21 (MH) + ).

[0121] Manufacturing Example 7: Synthesis of Compound XII (1) Synthesis of the compound of formula XIII 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 to a 1000 mL four-necked flask. The mixture was heated to 60°C while stirring, and dehydration was carried out by vacuum distillation to form a salt between TMAOH and o-toluidine. During this process, the color of the reaction solution gradually changed from yellow to reddish-brown. The temperature was gradually raised to 80°C, and when the fraction reached approximately half the amount of 25% tetramethylammonium hydroxide used as a catalyst, 68.5 g (0.50 mol) of o-nitrotoluene was added dropwise for about 3 hours while distillation was carried out at 80°C under reduced pressure (-0.097 MPa). After the addition was complete, the mixture was kept warm for 1 hour, and the completion of the reaction of o-nitrotoluene was confirmed by LC to obtain the condensate.

[0122] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 65 g of deionized water and 38 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 78 °C and 2.0 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. The reaction solution was filtered, washed with water, and phase separated. The organic phase was removed by vacuum distillation (-0.1 MPa, 180 °C) to obtain 31.8 g of the compound of formula XIII (yield approximately 30%), and GC measurement showed a content of >92.5%.

[0123] [ka] LC-MS (m / z): 212.20 (M-H+).

[0124] (2) Synthesis of the compound of formula XII 30 g (0.14 mol) of the compound of formula XIII, 120.6 g (1.4 mol) of 2-pentanone, and 0.8 g of Pt / C were placed in a reaction vessel, heated to 90 °C, purged with hydrogen gas, and then pressurized to 1.5 MPa to carry out the reaction. GC measurement confirmed that the content of the compound of formula XIII was <0.1%, after which the temperature was lowered and the reaction was stopped. Light components were removed by filtration and vacuum distillation (-0.1 MPa, 160 °C) to obtain 38 g of the compound of formula XII (yield approximately 96%), and GC measurement confirmed a content of >96.2%. Properties: Black solid.

[0125] [ka] LC-MS (m / z): 282.43 (MH) + ).

[0126] Manufacturing Example 8: Synthesis of Compound XIV (1) Synthesis of the compound of formula XV 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 to a 1000 mL four-necked flask. The mixture was heated to 60°C while stirring, and dehydration was carried out by vacuum distillation to form a salt between TMAOH and o-toluidine. During this process, the color of the reaction solution gradually changed from yellow to reddish-brown. The temperature was gradually raised to 80°C, and when the fraction reached approximately half the amount of 25% tetramethylammonium hydroxide used as a catalyst, 68.5 g (0.50 mol) of o-nitrotoluene was added dropwise for about 3 hours while distillation was carried out at 80°C under reduced pressure (-0.097 MPa). After the addition was complete, the mixture was kept warm for 1 hour, and the completion of the reaction of o-nitrotoluene was confirmed by LC to obtain the condensate.

[0127] The above condensation solution was transferred to a 500 mL stainless steel reaction vessel, 65 g of deionized water and 38 g of skeletonized nickel as a catalyst were added, and after three substitutions with hydrogen gas, the temperature was raised and pressurized to 78 °C and 2.0 MPa to carry out the reaction. LC confirmed that the reduction of nitro and nitroso compounds was completely finished. The reaction solution was filtered, washed with water, and phase separated. The organic phase was removed by vacuum distillation (-0.1 MPa, 180 °C) to obtain 34 g of the compound of formula XV (yield approximately 32%), and GC measurement showed a content of >93.4%.

[0128] [ka] LC-MS (m / z): 212.30 (MH) + ).

[0129] (2) Synthesis of the compound of formula XIV 30 g (0.14 mol) of compound XV, 104.5 g (1.8 mol) of acetone, and 0.8 g of Pt / C catalyst were placed in a reaction vessel. The temperature was raised to 70°C, the vessel was purged with hydrogen gas, and the reaction was carried out under pressure of 1.5 MPa. GC measurement confirmed that the content of compound XV was <0.1%, after which the temperature was lowered and the reaction was stopped. Light components were removed by filtration and vacuum distillation (-0.1 MPa, 160°C) to obtain 34.7 g of compound XIV (yield approximately 97.5%), and GC measurement confirmed a content of >95.8%. Properties: Deep red solid.

[0130] [ka] LC-MS (m / z): 240.35 (MH) + ).

[0131] Examples 1-17 and Comparative Example 1 The rubber compositions of Examples 1 to 17 and Comparative Example 1 were manufactured according to the formulations shown in Tables 1, 2, and 3, by the following process. (1) Natural rubber and butadiene rubber were added to an internal mixer, then carbon black, zinc oxide, stearic acid, aromatic oil and one or two of the following (degradation inhibitors 6PPD, compound I, compound II, compound IV, compound VI, compound VIII, compound X, compound XII, and compound XIV) were added, and the mixture was kneaded until the rubber mixture temperature reached 130°C, and the rubber was discharged to obtain a single-stage rubber. (2) After the first stage rubber was cooled, it was kneaded in an open mill, accelerator NS and sulfur were added, and the kneading continued until the rubber compound temperature reached 70°C, and then discharged to obtain the second stage rubber. (3) The two-stage rubber was vulcanized (145°C x 30 min) to obtain vulcanized rubber.

[0132] [Table 1]

[0133] [Table 2]

[0134] [Table 3] Test Example 1: Bending Crack Resistance Test According to standard GB / T 13934-2006, Measurement of flexural cracking and crack growth (DeMattia type) for vulcanized rubber or thermoplastic rubber, flexural cracking characteristic tests were performed on vulcanized rubber. The number of flexes corresponding to the early onset of cracks (level 1, level 2) and damage to the test specimen (level 6) were recorded, and the results are shown in Tables 4, 5, and 6.

[0135] [Table 4]

[0136] [Table 5]

[0137] [Table 6] Note: The percentage values ​​in Tables 4, 5, and 6 refer to the increase in the number of bends of the corresponding example compared to the number of bends of Comparative Example 1.

[0138] As can be seen from Tables 4-6, the rubber compositions of Examples 1-17 (containing the compound of formula A) showed clear superiority over the rubber composition of Comparative Example 1 (containing the degradation inhibitor 6PPD) in both early crack prevention and suppression of late crack growth rate, with an average improvement of 30% or more. Furthermore, the flexural crack resistance of Example 6 was clearly superior to that of Examples 1 and 3. The flexural crack resistance of Examples 5, 7, and 8 was clearly superior to that of Examples 2 and 4. The flexural crack resistance of Example 9 was clearly superior to that of Examples 12 and 13. The flexural crack resistance of Example 10 was clearly superior to that of Examples 14 and 15. The flexural crack resistance of Example 11 was clearly superior to that of Examples 16 and 17. This indicates that the combined use of two compounds of formula A (for example, the combined use of compounds of formula I and formula II, the combined use of compounds of formula IV and formula VI, the combined use of compounds of formula VIII and formula X, and the combined use of compounds of formula XII and formula XIV) shows a clear synergistic effect in improving flexural crack resistance. Among these, the combined use of compounds of formula I and formula II shows the best improvement in flexural crack resistance.

[0139] Test Example 2: Anti-dynamic tensile fatigue property test In accordance with the standard GBT1688-2008, the measurement standard for tensile fatigue of vulcanized rubber, a dynamic tensile fatigue characteristic test was performed on vulcanized rubber. The test specimen was reciprocated under test conditions of 50% elongation and a frequency of 5 Hz, and the number of cycles until the test specimen fractured was recorded. The results are shown in Tables 7 and 8.

[0140] [Table 7]

[0141] [Table 8] Note: The percentage values ​​in Tables 7 and 8 represent the increase in the number of tensile cycles at fatigue failure in the corresponding example compared to the number of tensile cycles at fatigue failure in Comparative Example 1.

[0142] As can be seen from Tables 7 and 8, the dynamic tensile fatigue properties of the rubber compositions of Examples 1 to 17 (containing the compound of formula A) were clearly superior to those of the rubber composition of Comparative Example 1 (containing the degradation inhibitor 6PPD), with an average improvement of 30% or more. Furthermore, the dynamic tensile fatigue properties of Example 6 were superior to those of Examples 1 and 3. The dynamic tensile fatigue properties of Examples 5, 7, and 8 were superior to those of Examples 2 and 4. The dynamic tensile fatigue properties of Example 9 were superior to those of Examples 12 and 13. The dynamic tensile fatigue properties of Example 10 were superior to those of Examples 14 and 15. The dynamic tensile fatigue properties of Example 11 were superior to those of Examples 16 and 17. This indicates that the combined use of two compounds of formula A (for example, the combined use of the compound of formula I and the compound of formula II, the combined use of the compound of formula IV and the compound of formula VI, the combined use of the compound of formula VIII and the compound of formula X, and the combined use of the compound of formula XII and the compound of formula XIV) shows a synergistic effect in improving the dynamic tensile fatigue properties. Among these, the combination of compound I and compound II exhibits the best improvement in anti-dynamic tensile fatigue properties.

Claims

1. A rubber composition comprising 100 parts by mass of a diene elastomer and 1 to 3 parts by mass of two or more compounds of formula A, 【Chemistry 1】 In equation A, R 1 , R 2 and R 3 A rubber composition characterized in that each of the elements is independently selected from C1 to C8 alkyl groups.

2. The rubber composition according to claim 1, In equation A, R 1 and R 2 Each is independently selected from C1-C3 alkyl groups, preferably independently selected from methyl and ethyl groups, and / or In equation A, R 3 A rubber composition characterized in that the C3-C8 alkyl group is selected from C3-C6 alkyl groups, preferably from C3-C6 alkyl groups, for example, from C4-C6 alkyl groups.

3. A rubber composition according to claim 1, wherein the raw materials of the rubber composition include two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV, 【Chemistry 2】 Preferably, the rubber composition is characterized in that 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, In the raw materials of the rubber composition, the total amount used of two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV is 1 to 3 parts by mass, for example, 1.5 to 2 parts by mass, and / or A rubber composition characterized in that, in the raw materials of the rubber composition, the mass ratio of two compounds selected from 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, wherein the rubber composition has the following characteristics, namely, The diene elastomer contains natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:

1. The raw materials of the rubber composition further include 30 to 70 parts by mass of a reinforcing filler, wherein the reinforcing filler is preferably carbon black. The raw materials for the rubber composition further contain 0.5 to 3 parts by mass of sulfur. The raw materials of the rubber composition further contain 1 to 10 parts by mass of an activator, preferably the activator being zinc oxide. The raw materials of the rubber composition further contain 2 to 15 parts by mass of a softening agent. The rubber composition is characterized in that the raw materials of the rubber composition further contain 0.2 to 2 parts by mass of an accelerator, wherein the accelerator is preferably selected from N-tert-butyl-2-benzothiazole sulfenamide, and the rubber composition is further characterized in that the accelerator is one or more selected from N-tert-butyl-2-benzothiazole sulfenamide.

6. A rubber product comprising a rubber composition according to any one of claims 1 to 4, and preferably a tire.

7. A method for improving the fatigue degradation resistance of a rubber composition, the method comprising adding 1 to 3 parts by mass of two or more compounds of formula A to the raw materials of the rubber composition, with the mass of the diene elastomer contained in the raw materials of the rubber composition being 100 parts by mass. 【Transformation 3】 In formula A, R 1 , R 2 and R 3 are each independently selected from C1-C8 alkyl groups, Preferably, in formula A, R 1 and R 2 Each is independently selected from C1-C3 alkyl groups, preferably independently selected from a methyl group and an ethyl group. Preferably, in formula A, R 3 A method characterized in that the alkyl group is selected from C3 to C8 alkyl groups, preferably from C3 to C6 alkyl groups, for example, from C4 to C6 alkyl groups.

8. A method according to claim 7, the method comprising adding two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV to the raw materials of a rubber composition, 【Chemistry 4】 Preferably, the method is characterized by 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, In the raw materials of the rubber composition, the total amount used of two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV is 1 to 3 parts by mass, for example, 1.5 to 2 parts by mass, and / or A method characterized in that, in the raw materials for the rubber composition, the mass ratio of two compounds selected from the compounds of formula I, formula II, formula IV, formula VI, formula VIII, formula X, formula XII, and formula XIV is 1:2 to 2:1, for example, 1:1.5 to 1.5:

1.

10. The method according to claim 7, wherein the method has the following features, namely, The diene elastomer contains natural rubber and butadiene rubber in a mass ratio of 1:2 to 2:

1. The raw materials of the rubber composition further include 30 to 70 parts by mass of a reinforcing filler, wherein the reinforcing filler is preferably carbon black. The raw materials for the rubber composition further contain 0.5 to 3 parts by mass of sulfur. The raw materials of the rubber composition further contain 1 to 10 parts by mass of an activator, preferably the activator being zinc oxide. The raw materials of the rubber composition further contain 2 to 15 parts by mass of a softening agent. The method is characterized in that the raw materials of the rubber composition further contain 0.2 to 2 parts by mass of an accelerator, wherein the accelerator is preferably selected from N-tert-butyl-2-benzothiazole sulfenamide.

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