Anti-aging agent composition with excellent ozone aging resistance, rubber composition and application thereof

Abstract

The invention provides an anti-aging agent composition containing two or more compounds as shown in a formula A, a rubber composition containing the anti-aging agent composition and application of the anti-aging agent composition and the rubber composition. The compound of formula A is as described herein. The anti-aging agent composition provided by the invention can significantly improve the static ozone aging resistance and dynamic ozone aging resistance of a tire rubber material, and other properties, such as thermo-oxidative aging resistance, of the tire rubber material can be kept consistent with those of the existing comprehensive anti-aging agent.

Description

Technical Field

[0001] The invention belongs to the field of rubber materials, and in particular relates to an antioxidant composition with excellent ozone aging resistance, a rubber composition and uses thereof. Background Art

[0002] With the development of society and the progress of the automobile industry, the requirements for automobile tires are getting higher and higher. Tires are a kind of rubber products. During the processing, storage and use of rubber materials, due to the influence of various factors such as light, oxygen, ozone, high temperature, chemical corrosion, etc., its structure changes and gradually loses its original excellent properties. This is the aging phenomenon of rubber. In particular, rubber containing double bonds and its products are easily affected by ozone and undergo ozone aging when used or stored in an air environment containing ozone. Ozone aging can be manifested as: cracks and cracks perpendicular to the stress direction appear on the surface of the material or product; the mechanical properties of the material such as tensile strength and elongation gradually decrease, and the performance of use decreases. For this reason, we need to add antioxidants to tires to improve the effects of various aging on their performance. Among the existing tire antioxidants, aniline, quinoline and triazine structures are the main ones.

[0003] When the tire is stationary or in motion, it is attacked by ozone in the air and cracks form. This may happen when the tire is parked in a warehouse. Such cracks will affect the appearance and performance of the tire, making it impossible to sell and use the tire. These tiny cracks on the tire of the car will expand into tire damage points during subsequent use, shortening the service life of the tire and even causing accidents during driving. Existing comprehensive antioxidants have a relatively balanced protection for various properties, but are not outstanding in ozone protection. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an antioxidant composition comprising two or more compounds of formula A, a rubber composition containing the antioxidant composition and uses thereof. The combined use of two or more compounds of formula A can significantly improve the static ozone aging resistance and dynamic ozone aging resistance of tire rubber materials, and other properties such as thermal oxygen aging resistance can also be consistent with existing comprehensive antioxidants. This helps to effectively deal with the ozone aging phenomenon of tires, thereby extending the service life of tires and improving the safety of tires during use.

[0005] Specifically, one aspect of the present invention provides an antioxidant composition, which comprises two or more compounds of formula A:

[0006]

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

[0008] In one or more embodiments, in Formula A, R1 is selected from C1-C2 alkyl, and R2 is selected from C3-C6 alkyl.

[0009] In one or more embodiments, the antioxidant composition comprises two or more 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 V, a compound of formula VII, and a compound of formula VIII:

[0010]

[0011]

[0012] In one or more embodiments, the antioxidant composition comprises a compound of formula I and a compound of formula II, or comprises a compound of formula IV and a compound of formula V, or comprises a compound of formula VII and a compound of formula VIII.

[0013] In one or more embodiments, in the antioxidant composition, the mass ratio of the compound of formula I to the compound of formula II, the mass ratio of the compound of formula IV to the compound of formula V, or the mass ratio of the compound of formula VII to the compound of formula VIII is 1:4 to 4:1.

[0014] Another 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 1-5 parts by mass of the antioxidant composition as described in any embodiment of the present invention.

[0015] In one or more embodiments, the raw material of the rubber composition includes 2-3 parts by mass of the antioxidant composition.

[0016] In one or more embodiments, the diene elastomer comprises natural rubber and butadiene rubber; preferably, the mass ratio of the natural rubber to the butadiene rubber is from 1:2 to 2:1.

[0017] In one or more embodiments, the raw materials of the rubber composition further include 30-70 parts by mass of a reinforcing filler; preferably, the reinforcing filler is carbon black.

[0018] 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.

[0019] In one or more embodiments, the raw materials of the rubber composition further include 2-15 parts by mass of a softener; preferably, the softener includes aromatic oil and stearic acid in a mass ratio of 1:1 to 5:1.

[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 0.2-2 parts by mass of an accelerator, and the accelerator is preferably N-tert-butyl-2-benzothiazolesulfenamide.

[0022] Another aspect of the present invention provides a rubber product, wherein the rubber product comprises the rubber composition described in any embodiment of the present invention; preferably, the rubber product is a tire.

[0023] The present invention also provides use of the antioxidant composition as described in any embodiment of the present invention in improving the ozone aging resistance of a rubber composition or a rubber product. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0025] 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.

[0026] 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 be disclosed herein.

[0027] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0028] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0029] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0030] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0031] The present invention finds that the combination of two or more compounds of formula A, especially the combination of compounds of formula I and formula II, the combination of compounds of formula IV and formula V, and the combination of compounds of formula VII and formula VIII in a rubber composition, especially a tire rubber composition, can significantly improve the ozone aging resistance of the rubber composition in static and dynamic processes, thereby extending the service life and improving the safety guarantee during use. Compared with the use of antioxidant 6PPD or one compound of formula A alone, the combination of two or more compounds of formula A, especially the combination of compounds of formula I and formula II, the combination of compounds of formula IV and formula V, and the combination of compounds of formula VII and formula VIII, shows an unexpected synergistic effect in improving the ozone aging resistance of the rubber composition.

[0032] In the present invention, the compound of formula A has the following structure:

[0033]

[0034] In formula A, R1 and R2 are each independently selected from a C1-C8 alkyl group.

[0035] As used herein, alkyl refers to a linear or branched monovalent saturated hydrocarbon group containing 1 to 8 carbon atoms (C1-C8 alkyl). Examples of alkyl include, but are not limited to, methyl, ethyl, propyl, isopropyl, 1-methylpropyl, isobutyl, 1-methylbutyl, and 1,3-dimethylbutyl.

[0036] In some embodiments, in Formula A, R1 is selected from C1-C4 alkyl, such as C1-C2 alkyl.

[0037] In some embodiments, in formula A, R2 is selected from C3-C6 alkyl, such as isopropyl, 1-methylpropyl, 1-methylbutyl, 1,3-dimethylbutyl, preferably selected from C4-C6 alkyl.

[0038] In some preferred embodiments, in formula A, R1 is selected from C1-C2 alkyl; R2 is selected from C3-C6 alkyl or C4-C6 alkyl, for example, selected from isopropyl, 1-methylpropyl, 1-methylbutyl, 1,3-dimethylbutyl.

[0039] In the present invention, the compound of formula A can be prepared by a method comprising the following steps:

[0040] (1) subjecting a compound of formula B to a condensation reaction with nitrobenzene in the presence of a first catalyst to obtain a condensate comprising a compound of formula C and / or a compound of formula C′, and then subjecting the condensate to a reduction reaction in the presence of H2 and a second catalyst to obtain a compound of formula D;

[0041]

[0042] (2) subjecting the compound of formula D to a reductive alkylation reaction with the compound of formula E in the presence of H2 and a third catalyst to obtain a compound of formula A;

[0043]

[0044] R1 and R2 in Formula A, Formula B, Formula C, and Formula D can be as described in any embodiment of the present invention, R3 and R4 in Formula E are each independently selected from H and C1-C7 alkyl, and those skilled in the art can determine the appropriate R4 and R5 in Formula F based on R3 contained in the compound of Formula A.

[0045] 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 the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. Suitable alkali metal alkoxides for 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, etc. Quaternary ammonium bases are a class of compounds with the general formula R 1 4NOH, 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, iodine. Examples of the combination of an alkali metal hydroxide and a tetraalkylammonium halide include sodium hydroxide and tetrabutylammonium bromide, etc.

[0046] 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, 1.5:1. In some embodiments, in step (1), the compound of formula B and the first catalyst are first salified, and then nitrobenzene is added dropwise to carry out a condensation reaction.

[0047] In step (1), the condensation product obtained by the condensation reaction of the compound of formula B and nitrobenzene under the action of the first catalyst may be one or both of the compound of formula C and the compound of formula C', and may also contain an azobenzene compound.

[0048] In step (1), the molar ratio of the compound of formula B to nitrobenzene can be 2:1 to 15:1, preferably 4:1 to 10:1, more preferably 5:1 to 8:1, such as 6:1 or 7:1.

[0049] In step (1), the condensation reaction can be carried out at 40 to 90° C., preferably 65 to 85° C., for example, the reaction temperature can be 60° C., 70° C., 75° C., 80° C. The condensation reaction needs to be carried out under vacuum conditions, with a pressure range of -0.09 to -0.1 MPa.

[0050] 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 metals as catalytic active centers and carriers for supporting metals. The metals suitable for the supported metal catalysts of the present invention can be nickel, cobalt, copper, platinum, palladium, ruthenium, rhodium, etc., and the carrier can be carbon, alumina, silica gel, molecular sieves, etc., and the carbon as a 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.

[0051] In step (1), the condensate generated by the condensation reaction is subjected to a hydrogenation reduction reaction under the action of a second catalyst to produce a compound of formula D. 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 in the reduction reaction can be 0.5 to 5 MPa, for example, 1 MPa, 1.5 MPa, 2 MPa, or 2.5 MPa.

[0052] 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 separated into phases, and the organic phase is subjected to reduced pressure distillation to remove light components to obtain the compound of formula D.

[0053] The third catalyst used in step (2) may 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 D may be 0.0001:1 to 0.2:1.

[0054] In step (2), after the reaction, the carbonyl carbon atom in the compound of formula E is connected to the amino nitrogen atom in the compound of formula D. Therefore, a suitable compound of formula E 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 E to the compound of formula D 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, 120°C. The hydrogen pressure in step (2) can be 0.5 to 5MPa, for example, 1MPa, 1.5MPa, 2MPa, 2.5MPa.

[0055] In step (2), the compound of formula E, 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 reduced pressure distillation to obtain the compound of formula A.

[0056] 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.

[0057] The antioxidant composition of the present invention comprises two or more compounds of formula A, or is composed of two or more compounds of formula A.

[0058] In some embodiments, the antioxidant composition of the present invention comprises two or more compounds selected from the group consisting of compounds of formula I, compounds of formula II, compounds of formula IV, compounds of formula V, compounds of formula VII, and compounds of formula VIII:

[0059]

[0060]

[0061] In some embodiments, the antioxidant composition of the present invention comprises two compounds of formula A, or consists of two compounds of formula A; the mass ratio of the two compounds of formula A can be 1:4 to 4:1, for example 1:3, 1:2, 1:1.5, 1:1, 1.5:1, 2:1, 3:1.

[0062] In some preferred embodiments, the antioxidant composition comprises a compound of formula I and a compound of formula II, or is composed of a compound of formula I and a compound of formula II. In the antioxidant composition of the present invention, the mass ratio of the compound of formula I to the compound of formula II is preferably 1:4 to 4:1, for example, 1:3, 1:2, 1:1.5, 1:1, 1.5:1, 2:1, 3:1. Controlling the mass ratio of the compound of formula I to the compound of formula II within the aforementioned range is conducive to exerting the synergistic effect of the two in improving the ozone aging resistance of the rubber composition.

[0063] In other preferred embodiments, the antioxidant composition comprises a compound of formula IV and a compound of formula V, or is composed of a compound of formula IV and a compound of formula V. In the antioxidant composition of the present invention, the mass ratio of the compound of formula IV to the compound of formula V is preferably 1:4 to 4:1, for example, 1:3, 1:2, 1:1.5, 1:1, 1.5:1, 2:1, 3:1. Controlling the mass ratio of the compound of formula IV to the compound of formula V within the aforementioned range is conducive to exerting the synergistic effect of the two in improving the ozone aging resistance of the rubber composition.

[0064] In other preferred embodiments, the antioxidant composition comprises a compound of formula VII and a compound of formula VIII, or is composed of a compound of formula VII and a compound of formula VIII. In the antioxidant composition of the present invention, the mass ratio of the compound of formula VII to the compound of formula VIII is preferably 1:4 to 4:1, for example, 1:3, 1:2, 1:1.5, 1:1, 1.5:1, 2:1, 3:1. Controlling the mass ratio of the compound of formula VII to the compound of formula VIII within the aforementioned range is conducive to exerting the synergistic effect of the two in improving the ozone aging resistance of the rubber composition.

[0065] The raw materials of the rubber composition generally include a diene elastomer, a reinforcing filler, an antioxidant and a crosslinking agent. Herein, the rubber composition includes unvulcanized rubber and vulcanized rubber. The unvulcanized rubber can be vulcanized (cured) to obtain vulcanized rubber.

[0066] The raw materials of the rubber composition of the present invention include diene elastomer and antioxidant composition of the present invention, wherein, based on the amount of diene elastomer as 100 parts by mass, the amount of antioxidant composition of the present invention can be 1-5 parts by mass, preferably 1-4 parts by mass, such as 1.5 parts by mass, 2 parts by mass, 2.5 parts by mass, 3 parts by mass, 3.5 parts by mass. Controlling the amount of antioxidant composition of the present invention within the aforementioned range is conducive to ensuring the effect of improving the ozone aging resistance at a lower dosage. Herein, if not otherwise specified, the mass of the diene elastomer in the raw material of the rubber composition is 100 parts by mass as a benchmark to calculate the mass parts of other components in the raw material of the rubber composition.

[0067] Herein, diene elastomer refers to an elastomer whose monomers include dienes (such as butadiene, isoprene). Suitable diene elastomers for 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), cis-1,4-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, diene elastomer includes natural rubber and cis-1,4-butadiene rubber, or is composed of natural rubber and cis-1,4-butadiene rubber. The mass ratio of natural rubber and cis-1,4-butadiene rubber is preferably 1:2 to 2:1, such as 1:1.5 to 1.5:1, 4.5:5.5 to 5.5:4.5, 1:1.

[0068] The antioxidant contained in the rubber composition of the present invention includes the antioxidant composition of the present invention. In some embodiments, the rubber composition of the present invention does not contain other antioxidants except the antioxidant composition of the present invention. In the raw materials of the rubber composition of the present invention, the amount of the antioxidant composition of the present invention can be 1-5 mass parts, preferably 1-4 mass parts, such as 1.5 mass parts, 2 mass parts, 2.5 mass parts, 3 mass parts, 3.5 mass parts, more preferably 2-3 mass parts.

[0069] The raw material of the rubber composition of the present invention may include reinforcing filler. In the raw material of the rubber composition of the present invention, the amount of reinforcing filler can be 30-70 mass parts, such as 40 mass parts, 45 mass parts, 50 mass parts, 55 mass parts, 60 mass parts. Reinforcing filler suitable for the present invention can be a conventional reinforcing filler for rubber composition, including but not limited to one or more selected from carbon black, white carbon black, titanium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay and talcum. In some preferred embodiments, reinforcing filler comprises carbon black, or reinforcing filler is carbon black.

[0070] The raw materials of the rubber composition of the present invention include a crosslinking agent, such as sulfur. In the raw materials of the rubber composition of the present invention, the amount of sulfur used can be 0.5-3 parts by mass, such as 1 part by mass, 1.5 parts by mass, 2 parts by mass, and 2.5 parts by mass.

[0071] 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, activators and accelerators.

[0072] Softener can be used to improve the processing properties of rubber composition. Softener can include petroleum softener, such as naphthenic oil, aromatic oil, process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, vaseline, etc., and can also include fatty oil softener, such as stearic acid, castor oil, linseed oil, rapeseed oil, coconut oil, wax (such as beeswax, carnauba wax and lanolin), tall oil, linoleic acid, palmitic acid, lauric acid, etc. In the raw material of rubber composition of the present invention, the amount of softener can be 2-15 mass parts, such as 3 mass parts, 5 mass parts, 7 mass parts, 8 mass parts, 9 mass parts, 10 mass parts, 11 mass parts, 13 mass parts. In some preferred embodiments, softener includes aromatic oil and stearic acid, or is composed of aromatic oil and stearic acid. The mass ratio of aromatic oil and stearic acid can be 1:1 to 5:1, such as 2:1, 2.5:1, 3:1, 3.5:1, 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, 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, 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, 2.5 parts by mass, 3 parts by mass, and 4 parts by mass.

[0073] The protective wax can migrate from the inside of the rubber to the surface to form a wax film, which plays a role in 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 parts by mass, such as 1.5 parts by mass, 2 parts by mass, 3 parts by mass, and 4 parts by mass.

[0074] The activating agent can accelerate the vulcanization speed, improve the thermal conductivity, wear resistance, tear resistance and the like of rubber. In the raw material of the rubber composition of the present invention, the amount of the activating agent can be 1-10 mass parts, such as 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, the activating agent includes ZnO, or the activating agent is ZnO. In some preferred embodiments, in the raw material of the rubber composition of the present invention, the amount of ZnO is 3-8 mass parts, such as 4 mass parts, 5 mass parts, 6 mass parts, 7 mass parts.

[0075] The accelerator is usually a vulcanization accelerator, which can be selected from sulfonamide vulcanization accelerators, thiazole vulcanization accelerators, thiuram vulcanization accelerators, thiourea vulcanization accelerators, guanidine vulcanization accelerators, dithiocarbamate vulcanization accelerators, aldehyde amine vulcanization accelerators, aldehyde ammonia vulcanization accelerators, imidazoline vulcanization accelerators and xanthogenic acid vulcanization accelerators. In the raw materials of the rubber composition of the present invention, the amount of the 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, the accelerator is accelerator NS (N- tert-butyl -2-benzothiazole sulfonamide).

[0076] In addition, when necessary, the rubber composition may also contain 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), etc. The amount of the plasticizer may be a conventional amount in the art.

[0077] 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, 1-5 parts by mass of the antioxidant composition of the present invention, 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.

[0078] 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 (e.g., internal mixer) mixing, mixing the rubber composition raw materials except the crosslinking agent and the accelerator, kneading the entire mixture until the maximum temperature reaches between 110°C and 190°C to obtain a first stage of rubber; a second stage of thermomechanical (e.g., open mixer) mixing, after the first stage of rubber is cooled to below 100°C, mixing the first stage of rubber with the crosslinking agent and the accelerator until the maximum temperature is below 110°C to obtain a second stage of rubber, i.e., the unvulcanized rubber.

[0079] Vulcanized rubber can be obtained by vulcanizing (curing) the unvulcanized rubber. The vulcanization temperature is usually 130-200°C, such as 140-160°C, 145±5°C; the vulcanization time depends on the vulcanization temperature, the vulcanization system and the vulcanization kinetics, and is usually 15-60 minutes, such as 20-40 minutes, 30±5 minutes. Before vulcanization, the unvulcanized rubber can be rolled to a certain thickness, such as about 2 mm.

[0080] The rubber composition of the present invention is used in rubber products, especially tires. Compared with the use of antioxidant 6PPD or a formula A compound alone, the use of the antioxidant composition of the present invention, especially the combination of formula I compound and formula II compound, the combination of formula IV compound and formula V compound, and the combination of formula VII compound and formula VIII compound can significantly improve the ozone aging resistance of rubber products. Therefore, the present invention also provides a rubber product, the rubber product contains the rubber composition described herein. The rubber product can be a tire, a rubber shoe, a sealing strip, a sound insulation board, a shock pad, etc. The rubber product is preferably a tire, such as a sidewall rubber, a tread rubber, etc.

[0081] The present invention also provides the antioxidant composition of the present invention, such as the combination of the compound of formula I and the compound of formula II, the combination of the compound of formula IV and the compound of formula V, and the combination of the compound of formula VII and the compound of formula VIII in improving the ozone aging resistance of the rubber composition or rubber products, and the method for improving the ozone aging resistance of the rubber composition or rubber products. Preferably, the use or method of the present invention comprises: based on the mass of the diene elastomer contained in the rubber composition being 100 parts by mass, adding 1-5 parts by mass of the antioxidant composition of the present invention to the raw materials of the rubber composition. In the use or method of the present invention, the raw material composition of the rubber composition is preferably as described in any embodiment herein.

[0082] The present invention will be described below in the form 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 raw material compounds in the examples can all be purchased through commercial routes.

[0083] 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, stearic acid (SA), aromatic oil, sulfur (S) and accelerator NS are all common raw materials for the rubber industry.

[0084] Preparation Example 1: Synthesis of Compounds of Formula I

[0085] (1) Synthesis of compound of formula III

[0086] In a 1000mL four-necked flask, 400.2g (3.25mol) of o-methyl ether aniline and 200.2g (0.55mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added, stirred and heated to 40-50°C, and dehydrated by vacuum distillation to form salts of TMAOH and o-methyl ether aniline. During this process, the reaction solution gradually changed from yellow to reddish brown; the temperature was gradually raised to 75°C. When the fraction was about 100g, 61.55g (0.50mol) of nitrobenzene was added dropwise at 75°C under reduced pressure (-0.097MPa) for about 3h. After the addition was completed, the temperature was kept for 1h. LC monitoring was performed until the reaction of nitrobenzene was complete to obtain a condensation solution.

[0087] The condensation liquid was transferred to a 1000mL stainless steel reactor, 100g of deionized water and 60g of catalyst skeleton nickel were added, hydrogen was replaced three times, the temperature was raised to 65°C, the pressure was raised to 1.5MPa for reaction, and LC was monitored until the nitro and nitroso compounds were completely reduced. The reaction liquid was filtered, washed with water, and phase-separated; the aqueous phase was concentrated and then used again, and the organic phase was distilled under reduced pressure to obtain 84.6g of the compound of formula III (yield of about 79.5%), and the content detected by GC was >99.2%.

[0088]

[0089] Molecular formula: C 13 H 14 N2O

[0090] LC-MS (m / z): 214.26 (MH + ).

[0091] (2) Synthesis of Compounds of Formula I

[0092] 50g (0.23mol) of compound III, 100g (1.0mol) of 4-methyl-2-pentanone and 1.0g of Pt / C were put into a 500mL autoclave, heated to 90°C for reaction, and then the pressure was raised to 1.2MPa for reaction after hydrogen replacement. The content of compound III was detected by GC to be <0.1%, and the temperature was lowered to stop the reaction. Filter and distill under reduced pressure to remove light components such as water and 4-methyl-2-pentanone to obtain 65.1g of compound I (yield of about 95%), and the content detected by GC was >98.2%. Properties: purple-brown liquid.

[0093]

[0094] Molecular formula: C 19 H 26 N2O

[0095] LC-MS (m / z): 298.42 (MH+ ).

[0096] Preparation Example 2: Synthesis of Formula II

[0097] (1) Synthesis of compound of formula III

[0098] The synthesis of the compound of formula III is the same as step (1) of Preparation Example 1.

[0099] (2) Synthesis of Compound II

[0100] 81.5g (0.38mol) of compound III, 117g (1.62mol) of 2-butanone and 1.0g of Pt / C were put into a 500mL autoclave, heated to 70°C for reaction, and then the pressure was raised to 1.2MPa for reaction after hydrogen substitution. The content of compound III was <0.1% detected by GC, and the temperature was lowered to stop the reaction. Filter and distill under reduced pressure to remove light components such as water and 2-butanone to obtain 99.5g of compound II (yield of about 97%), and the content detected by GC was >97.2%. Properties: purple liquid.

[0101]

[0102] Molecular formula: C 17 H 22 N2O

[0103] LC-MS (m / z): 270.37 (MH + ).

[0104] Preparation Example 3: Synthesis of Formula IV

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

[0106] The synthesis of the compound of formula III is the same as step (1) of Preparation Example 1.

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

[0108] 92g (0.43mol) of compound III, 106g (1.83mol) of acetone and 1.0g of Pt / C were put into a 500mL autoclave, heated to 75°C for reaction, and then the pressure was raised to 1.2MPa for reaction after hydrogen substitution. The content of compound III was <0.1% detected by GC, and the temperature was lowered to stop the reaction. Light components such as water and acetone were removed by filtration and reduced pressure distillation to obtain 106.1g of compound IV (yield of about 96%), and the content detected by GC was >97.6%. Properties: purple liquid.

[0109]

[0110] Molecular formula: C 16 H 20N2O

[0111] LC-MS (m / z): 256.35 (MH + ).

[0112] Preparation Example 4: Synthesis of Compound V

[0113] (1) Synthesis of compound of formula III

[0114] The synthesis of the compound of formula III is the same as step (1) of Preparation Example 1.

[0115] (2) Synthesis of Compound V

[0116] 62g (0.29mol) of compound III, 107g (1.24mol) of 2-pentanone and 1.0g of Pt / C were put into a 500mL autoclave, heated to 80°C for reaction, and then the pressure was raised to 1.2MPa for reaction after hydrogen substitution. The content of compound III was detected by GC to be <0.1%, and the temperature was lowered to stop the reaction. Filter and distill under reduced pressure to remove light components such as water and 2-pentanone to obtain 79.2g of compound V (yield of about 96%), and the content detected by GC was >98.2%. Properties: purple liquid.

[0117]

[0118] Molecular formula: C 18 H 24 N2O

[0119] LC-MS (m / z): 284.40 (MH + ).

[0120] Preparation Example 5: Synthesis of Compound VII

[0121] (1) Synthesis of Compound VI

[0122] In a 500mL four-necked flask, 220g (1.6mol) of o-ethyl ether aniline and 80g (0.22mol) of a 25% aqueous solution of tetramethylammonium hydroxide (TMAOH) were added, stirred and heated to 50°C, and dehydrated by vacuum distillation to form salts of TMAOH and o-ethyl ether aniline. During this process, the reaction liquid gradually changed from yellow to reddish brown; the temperature was gradually raised to 75°C. When the fraction was about 100g, 24.6g (0.2mol) of nitrobenzene was added dropwise at 78°C under reduced pressure (-0.097MPa) for about 3h. After the addition was completed, the temperature was kept for 1h. LC monitoring was performed until the reaction of nitrobenzene was complete to obtain a condensation liquid.

[0123] The condensation liquid was transferred to a 500 mL stainless steel reactor, 30 g of deionized water and 20 g of catalyst skeleton nickel were added, hydrogen was replaced three times, the temperature was raised to 69 ° C, the pressure was raised to 1.6 MPa for reaction, and LC was monitored until the nitro and nitroso compounds were completely reduced. The reaction liquid was filtered, washed with water, and phase-separated; the aqueous phase was concentrated and then used again, and the organic phase was distilled under reduced pressure to obtain 34.1 g of the intermediate compound of formula VI (yield of about 75%), and the content detected by GC was >98.5%.

[0124]

[0125] Molecular formula: C 14 H 16 N2O

[0126] LC-MS (m / z): 228.26 (M-H+).

[0127] (2) Synthesis of the compound of formula VII

[0128] 30g (0.13mol) of compound VI, 43.2g (0.6mol) of 2-butanone and 0.6g of Pt / C were put into a 500mL autoclave, heated to 70°C for reaction, and then the pressure was raised to 1.2MPa for reaction after hydrogen substitution. The content of compound VI was <0.1% detected by GC, and the temperature was lowered to stop the reaction. Filter and remove light components such as water and 2-butanone by reduced pressure distillation to obtain 35.4g of compound VII (yield of about 96%), and the content detected by GC was >97.5%. Properties: reddish brown liquid.

[0129]

[0130] Molecular formula: C 18 H 24 N2O

[0131] LC-MS (m / z): 284.40 (MH + ).

[0132] Preparation Example 6: Synthesis of Compound VIII

[0133] (1) Synthesis of Compound VI

[0134] The synthesis of the compound of formula VI is the same as step (1) of Preparation Example 5.

[0135] (2) Synthesis of compound of formula VIII

[0136] 30g (0.13mol) of compound VI, 78g (0.8mol) of 4-methyl-2-pentanone and 0.8g of Pt / C were put into a 500mL autoclave, heated to 90°C for reaction, and then the pressure was raised to 1.8MPa for reaction after hydrogen substitution. The content of compound VI was <0.1% by GC, and the temperature was lowered to stop the reaction. Filter and distill under reduced pressure to remove light components such as water and 4-methyl-2-pentanone to obtain 39.8g of compound VIII (yield of about 98%), and the content was >98.0% by GC. Properties: reddish brown liquid.

[0137]

[0138] Molecular formula: C 20 H 28 N2O

[0139] LC-MS (m / z): 312.46 (MH + ).

[0140] Example 1

[0141] According to the formula shown in Table 1-2, the rubber composition 1-14 was prepared by the following process:

[0142] (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, compound of formula II, compound of formula I, compound of formula IV, compound of formula V, compound of formula VII and / or compound of formula VIII), kneading until the temperature of the rubber material rises to 130° C. and the rubber is discharged to obtain a rubber section;

[0143] (2) After the first-stage rubber is cooled to 50°C, the first-stage rubber is refined on an open mixing mill, accelerator NS and sulfur are added, and the rubber is kneaded until the temperature of the rubber reaches 70°C to obtain a sheet, thereby obtaining a second-stage rubber;

[0144] (3) The second-stage rubber was rolled into a sheet with a thickness of 2 mm, and the second-stage rubber was vulcanized (145° C.×30 min) to obtain a vulcanized rubber.

[0145] Table 1: Rubber composition formula (unit: mass parts)

[0146] Rubber composition number 1 2 3 4 5 6 7 8 SCR5 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 BR9000 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 Carbon Black N550 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 ZnO 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 S 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Aromatic oil 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Antioxidant 6PPD 2.5 0 0 0 0 0 0 0 Compound of formula II 0 2.5 0 0.5 1.0 1.25 1.5 2.0 Compounds of formula I 0 0 2.5 2.0 1.5 1.25 1.0 0.5 Accelerator NS 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 S 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 total 166.8 166.8 166.8 166.8 166.8 166.8 166.8 166.8

[0147] Table 2: Rubber composition formula (unit: mass parts)

[0148]

[0149]

[0150] Test Example 1: Vulcanization Characteristics Test and Thermal Oxidation Aging Test

[0151] The vulcanization characteristics t10 and t90 were measured according to GB / T 16584-1996 "Rotorless vulcanizer for rubber". The thermal oxygen aging test of the rubber compound was carried out according to GB / T3512-2014 "Hot air accelerated aging and heat resistance test of vulcanized rubber or thermoplastic rubber", and the test conditions were: 100℃×48 hours. The test standard for elongation at break and tensile strength before and after aging is: GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber. The results are shown in Table 3-4.

[0152] Table 3: Vulcanization characteristics and physical properties before and after thermal oxidative aging

[0153]

[0154]

[0155] Table 4: Vulcanization characteristics and physical properties before and after thermal oxidative aging

[0156]

[0157] Test Example 2: Ozone Aging Test

[0158] The ozone resistance of rubber was tested in an ozone aging test chamber using ISO 1431-1:2004 "Ozone cracking resistance of vulcanized or thermoplastic rubber". The test conditions were: ozone volume concentration 50×10 -8 , temperature (40±2)℃, humidity (50±5)%; pre-stretch 20% for static test, run at fixed intervals, and observe the cracking of the sample; pre-stretch 10% for dynamic test, dynamic stretch 10%, frequency 0.5Hz, run at fixed intervals, and observe the cracking of the sample. The results of static ozone aging test are shown in Table 5-6. The results of dynamic ozone aging test are shown in Table 7-8. The description of ozone crack level in Table 5-8 is shown in Table 9.

[0159] Table 5: Results of static ozone aging test on crack grade of rubber compounds

[0160]

[0161] Table 6: Results of static ozone aging test on crack grade of rubber compounds

[0162]

[0163] Table 7: Dynamic ozone aging test results of rubber crack grade

[0164]

[0165] Table 8: Dynamic ozone aging test results of rubber crack grade

[0166]

[0167] Table 9: Ozone aging test crack level description

[0168]

[0169]

[0170] From Tables 3-8, it can be seen that, compared with rubber compositions 1-3 containing only 6PPD, compounds of formula I or compounds of formula II, rubber compositions 4-8 containing compounds of formula I and compounds of formula II have comparable basic physical properties and greatly improved static and dynamic ozone aging resistance; compared with rubber compositions 11-12 containing only compounds of formula IV or compounds of formula V, rubber composition 9 containing compounds of formula IV and compounds of formula V has comparable basic physical properties and greatly improved static and dynamic ozone aging resistance; compared with rubber compositions 13-14 containing only compounds of formula VII or compounds of formula VIII, rubber composition 10 containing compounds of formula VII and compounds of formula VIII has comparable basic physical properties and improved static and dynamic ozone aging resistance. This indicates that the combination of compounds of formula I and compounds of formula II, the combination of compounds of formula IV and compounds of formula V, and the combination of compounds of formula VII and compounds of formula VIII have achieved unexpected synergistic effects in improving the static and dynamic ozone aging resistance of rubber compositions.

Claims

1. An antioxidant composition, characterized in that The antioxidant composition comprises two or more compounds of formula A: In formula A, R1 and R2 are each independently selected from a C1-C8 alkyl group.

2. The antioxidant composition according to claim 1, characterized in that In formula A, R1 is selected from C1-C2 alkyl, and R2 is selected from C3-C6 alkyl.

3. The antioxidant composition according to claim 1, characterized in that The antioxidant composition comprises two or more 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 V, a compound of formula VII and a compound of formula VIII:

4. The antioxidant composition according to claim 3, characterized in that The antioxidant composition comprises a compound of formula I and a compound of formula II, or comprises a compound of formula IV and a compound of formula V, or comprises a compound of formula VII and a compound of formula VIII; Preferably, in the antioxidant composition, the mass ratio of the compound of formula I to the compound of formula II, the mass ratio of the compound of formula IV to the compound of formula V, or the mass ratio of the compound of formula VII to the compound of formula VIII is 1:4 to 4:

1.

5. 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 5 parts by mass of the antioxidant composition according to any one of claims 1 to 4.

6. The rubber composition according to claim 5, characterized in that The raw materials of the rubber composition include 2-3 parts by mass of the antioxidant composition.

7. The rubber composition according to claim 5, characterized in that The diene elastomer comprises natural rubber and butadiene rubber; preferably, the mass ratio of the natural rubber to the butadiene rubber is from 1:2 to 2:

1.

8. The rubber composition according to claim 5, characterized in that The rubber composition has one or more of the following characteristics: The raw materials of the rubber composition further include 30-70 parts by mass of a reinforcing filler; preferably, the reinforcing filler is carbon black; 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 further include 2-15 parts by mass of a softener; preferably, the softener includes aromatic oil and stearic acid in a mass ratio of 1:1 to 5:1; 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 0.2-2 parts by mass of an accelerator, and the accelerator is preferably N-tert-butyl-2-benzothiazole sulfenamide.

9. A rubber product, characterized in that: The rubber product comprises the rubber composition according to any one of claims 5 to 8; preferably, the rubber product is a tire.

10. Use of the antioxidant composition according to any one of claims 1 to 4 in improving the ozone aging resistance of a rubber composition or a rubber product.

Images