Low odor rubber composition with excellent resistance to thermal oxidation aging and fatigue

Abstract

A low-odor rubber composition with excellent thermal oxidative aging resistance and tensile fatigue resistance is formulated, comprising 100 parts by weight of a diene elastomer, 30 to 70 parts by weight of a reinforcing filler, 0.1 to 8 parts by weight of an antioxidant composition, and 0.5 to 3 parts by weight of a crosslinking agent, the antioxidant composition containing a 6PPD antioxidant having a purity of about 98% by mass or higher and S-TMQ. The rubber composition does not require the addition of an odor suppressant / absorbent or deodorizer, and by using a combination of a 6PPD antioxidant having a purity of about 98% by mass or higher and S-TMQ instead of the conventional combination of a 6PPD antioxidant and a TMQ antioxidant, the rubber composition effectively reduces VOC emissions, reduces odor grade, and improves thermal oxidative aging resistance and tensile fatigue resistance.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 202011090561.7, filed in China on October 13, 2020. The Chinese priority application is incorporated herein by reference.

[0002] The present invention relates to a rubber composition, and more particularly to the formulation of a low odor rubber composition having excellent resistance to thermal oxidative aging and fatigue resistance. [Background technology]

[0003] Although tires are not part of the interior of a car, spare tires are often stored in the trunks of passenger cars, emitting unpleasant odors and even affecting the health and safety of passengers.

[0004] As awareness of environmental protection, health, and safety grows year by year, people are becoming more sensitive to and concerned about odors inside their cars.More and more major automobile engine manufacturers are requiring spare tires to be inspected and controlled for volatile organic compounds (VOCs), and tire odors need to be reduced.

[0005] Various additives and materials, such as vulcanizing agents, accelerators, and antioxidants, are added to rubber compositions during processing. Complex chemical reactions occur during vulcanization, resulting in the generation of volatile organic compounds and unpleasant, odorous low-molecular-weight gases. While most of these substances are released after vulcanization, small amounts of gas remain in the rubber product and are gradually released over time. Antioxidants, particularly p-phenylenediamine antioxidants such as N-(1,3-dimethylbutyl)-N'-phenyl p-phenylenediamine (6PPD), are widely used in various parts of tires due to their excellent anti-aging properties. The volatile substances remaining in the antioxidants, 4-methyl-2-pentanone (MIBK) and aniline, are irritating even in small amounts and are therefore considered to be one of the main causes of tire odor. Summary of the Invention [Problem to be solved by the invention]

[0006] Currently, methods for improving tire odor mainly include the following: (1) Adding aromatic additives or physical adsorbents to tire compounds can improve odors, but these methods only mask or adsorb the odor and do not fundamentally reduce VOC emissions. (2) Deodorizing additives, i.e., physical deodorizers such as polyethylene glycol, are added to tire formulations to promote the release of small molecule gases generated during rubber processing (mixing and vulcanization) and reduce subsequent release during storage. This method is disadvantageous because it increases plant VOC emissions and increases health risks to operators.

[0007] On the other hand, excellent thermal oxidative aging resistance and tensile fatigue resistance are important properties pursued in the field of rubber compositions. Therefore, there remains a need in the art for a low odor rubber composition that has reduced VOC emissions and good thermal oxidative aging resistance and tensile fatigue resistance. [Means for solving the problem]

[0008] To address these challenges, the present invention provides a low-odor rubber composition formulation that exhibits excellent thermal oxidative aging resistance and tensile fatigue resistance without the addition of odor inhibitors, adsorbents, or deodorizers. By adjusting the combination of antioxidants in the formulation—that is, by combining a specific 6PPD antioxidant with a specific quinoline antioxidant (S-TMQ), also a polymer of 1,2-dihydro-2,2,4-trimethylquinoline (CAS No. 26780-96-1) (hereinafter referred to as TMQ or TMQ antioxidant), instead of the conventional combination of 6PPD antioxidant with TMQ, i.e., a quinoline antioxidant (S-TMQ or S-TMQ antioxidant), instead of the conventional combination of 6PPD antioxidant with TMQ, i.e., a quinoline antioxidant (S-TMQ), also a polymer of 1,2-dihydro-2,2,4-trimethylquinoline (CAS No. 26780-96-1)—the present invention effectively reduces VOC emissions and odor grades while improving thermal oxidative aging resistance and tensile fatigue resistance.

[0009] Specifically, the present invention provides a rubber composition formulation including 100 parts by weight of a diene elastomer, 30 to 70 parts by weight of a reinforcing filler, 0.1 to 8 parts by weight of an antidegradant composition, and 0.5 to 3 parts by weight of a crosslinking agent, wherein the antidegradant composition includes a 6PPD antidegradant having a purity of about 98% by weight or more and an S-TMQ antidegradant, and the S-TMQ antidegradant is a TMQ antidegradant having a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 80% by weight or more.

[0010] The rubber composition formulation of the present invention comprises a mixture of ingredients, generally referred to as raw materials. Based on the rubber composition formulation of the present invention, those skilled in the art can obtain both vulcanized and unvulcanized rubber, which can then be further processed into rubber products.

[0011] In one or more embodiments of the present invention, the purity of the 6PPD anti-degradant is 98.5% by mass or more.

[0012] In one or more embodiments of the present invention, the number of types of organic volatile substances in the 6PPD antidegradant is 5 or less.

[0013] In one or more embodiments of the present invention, the total content of organic volatile substances in the 6PPD antidegradant does not exceed 10% of the total content of organic volatile substances in the 6PPD antidegradant having a purity of 97% by mass.

[0014] In one or more embodiments of the present invention, the content of 4-methyl-2-pentanone in the 6PPD antidegradant does not exceed 12% of the content of 4-methyl-2-pentanone in a 6PPD antidegradant having a purity of 97% by mass.

[0015] In one or more embodiments of the present invention, the content of aniline in the 6PPD antidegradant does not exceed 6.2% of the content of aniline in a 6PPD antidegradant having a purity of 97% by mass.

[0016] In one or more embodiments of the present invention, the total content of dimers, trimers, and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline in the S-TMQ degradation inhibitor is 80.2% by mass or more.

[0017] In one or more embodiments of the present invention, the number of types of organic volatile substances in the S-TMQ antidegradant is eight or less.

[0018] In one or more embodiments of the present invention, the total content of organic volatile substances in the S-TMQ does not exceed 41.7% of the total content of organic volatile substances in a TMQ degradation inhibitor in which the total content of dimers, trimers, and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline is 51% by weight.

[0019] In one or more embodiments of the present invention, the acetone content in the S-TMQ does not exceed 20.5% of the acetone content in a TMQ degradation inhibitor containing 51% by mass of the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer.

[0020] In one or more embodiments of the present invention, the aniline content in the S-TMQ does not exceed 27.3% of the aniline content in a TMQ degradation inhibitor in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer is 51% by mass.

[0021] In one or more embodiments of the present invention, the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the S-TMQ does not exceed 64.8% of the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the TMQ degradation inhibitor, in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer is 51% by mass.

[0022] In one or more embodiments of the present invention, the mass ratio of the 6PPD antidegradant to the S-TMQ antidegradant in the antidegradant composition of the rubber composition of the present invention is 1:0.2 to 1:1, preferably 1:0.36 to 1:0.6.

[0023] In one or more embodiments of the present invention, the formulation comprises 2 to 5 parts by weight, preferably 3.4 to 4 parts by weight, of the antidegradant composition relative to 100 parts by weight of the diene elastomer.

[0024] In one or more embodiments of the present invention, the antioxidant composition comprises a 6PPD antioxidant having a purity of about 98% by mass or greater, and the S-TMQ.

[0025] In one or more embodiments of the present invention, the diene elastomer includes one or more selected from natural rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, isoprene / butadiene copolymer, isoprene / styrene copolymer, and isoprene / butadiene / styrene copolymer. Preferably, the diene elastomer includes natural rubber and butadiene rubber, and the mass ratio of the natural rubber to the butadiene rubber is preferably 4:6 to 6:4.

[0026] In one or more embodiments of the present invention, the reinforcing filler comprises one or more selected from carbon black, titanium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay, and talc. Preferably, the reinforcing filler is carbon black.

[0027] In one or more embodiments of the invention, the cross-linking agent is sulfur.

[0028] In one or more embodiments of the invention, the formulation further comprises one or more selected from an emollient, an activator, and an accelerator.

[0029] In one or more embodiments of the present invention, the rubber composition formulation includes 100 parts by weight of a diene elastomer, 40 to 60 parts by weight of carbon black, 1 to 2 parts by weight of sulfur, 2 to 3 parts by weight of a 6PPD antidegradant having a purity of about 98% by weight or higher, 0.5 to 2 parts by weight of S-TMQ, 2 to 8 parts by weight of zinc oxide, 1 to 3 parts by weight of stearic acid, 1 to 10 parts by weight of naphthenic oil, and 0.5 to 1.5 parts by weight of an accelerator, wherein the diene elastomer includes natural rubber and butadiene rubber in a mass ratio of 4:6 to 6:4.

[0030] The present invention also provides a rubber composition prepared from the compounding of a rubber composition according to an embodiment described herein, which may be vulcanized or unvulcanized.

[0031] The present invention also provides a rubber product comprising a rubber composition prepared from the compounding of a rubber composition according to an embodiment described herein. Preferably, the rubber product is a tire.

[0032] The present invention also provides a method for using a 6PPD antidegradant having a purity of about 98% by mass or greater and S-TMQ in improving odor of a rubber composition or rubber product, thermal oxidative aging resistance of a rubber composition or rubber product, tensile fatigue resistance of a rubber composition or rubber product, or a combination thereof, wherein the S-TMQ is a TMQ antidegradant having a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 80% by mass or greater. Preferably, the rubber product is a tire. Preferably, the 6PPD antidegradant having a purity of about 98% by mass or greater is as described in an embodiment of the present specification. Preferably, the S-TMQ is as described in an embodiment of the present specification.

[0033] The present invention also provides a method for improving odor, thermal oxidative aging resistance, tensile fatigue resistance, or a combination thereof, of a rubber composition or a rubber product, the method comprising: using an antioxidant composition containing 6PPD antioxidant having a purity of about 98% by mass or more and S-TMQ in compounding a rubber composition; and preparing a rubber composition or a rubber product from the compounding. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention will be further described in conjunction with the following examples, which do not limit the protection scope of the present invention, and the technical features disclosed therein can be modified or combined without departing from the scope of the present invention.

[0035] In the present invention, unless otherwise specified, percentage of content or total content means mass percentage of content or total content, percentage means mass percentage, and ratio means mass ratio.

[0036] The present invention uses a combination of a 6PPD antioxidant with a purity of about 98% by mass or more and S-TMQ in a rubber composition instead of a combination of a low-purity 6PPD antioxidant and a TMQ antioxidant, thereby significantly improving the rubber odor without adding odor inhibitors, adsorbents, or deodorizers. Furthermore, the present invention not only significantly improves the rubber odor by using a combination of a 6PPD antioxidant with a purity of about 98% by mass or more and S-TMQ in a rubber composition, but also improves the thermal oxidative aging resistance and tensile fatigue resistance of the rubber composition with a smaller amount of antioxidant, while maintaining the original tensile strength, original elongation at break, static ozone aging resistance, and dynamic ozone aging resistance.

[0037] In the present invention, S-TMQ refers to a TMQ (polymer of 1,2-dihydro-2,2,4-trimethylquinoline) antioxidant with a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 80% or more. 6PPD antioxidant has the meaning well known in the art and refers to an antioxidant whose main component is 6PPD. TMQ antioxidant has the meaning well known in the art and refers to an antioxidant whose main component is TMQ.

[0038] In some embodiments of the present invention, the 6PPD inhibitor used in the present invention has a purity of about 98% by mass or greater and has one or more of the following characteristics: the purity is 98.5% by mass or greater; the number of types of organic volatile substances in the 6PPD inhibitor is 5 or less; the total content of organic volatile substances in the 6PPD inhibitor does not exceed 10% of the total content of organic volatile substances in a 6PPD inhibitor with a purity of 97% by mass; the content of 4-methyl-2-pentanone in the 6PPD inhibitor with a purity of 97% by mass does not exceed 12% of the content of 4-methyl-2-pentanone in the 6PPD inhibitor with a purity of 97% by mass; and the content of aniline in the 6PPD inhibitor with a purity of 97% by mass does not exceed 6.2% of the content of aniline in the 6PPD inhibitor with a purity of 97% by mass.

[0039] In some embodiments of the present invention, the S-TMQ used in the present invention has one or more of the following characteristics: the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimers, trimers, and tetramers in the S-TMQ is 80.2% by mass or more; the number of types of organic volatile substances in the S-TMQ is 8 or less; the total content of organic volatile substances in the S-TMQ does not exceed 41.7% of the total content of organic volatile substances in a TMQ deterioration inhibitor in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimers, trimers, and tetramers is 51% by mass; and the content of acetone in the S-TMQ is 51% by mass. The content of acetone in the MQ antidegradant does not exceed 20.5%; the content of aniline in the S-TMQ does not exceed 27.3% of the content of aniline in a TMQ antidegradant having a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 51% by mass; and the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the S-TMQ does not exceed 64.8% of the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in a TMQ antidegradant having a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 51% by mass.

[0040] The rubber composition generally contains a diene elastomer, a reinforcing filler, an anti-aging agent, and a crosslinking agent. Here, the rubber composition includes unvulcanized rubber and vulcanized rubber. Vulcanized rubber can be prepared from unvulcanized rubber after vulcanization (curing).

[0041] The rubber composition of the present invention comprises a diene elastomer, a reinforcing filler, an antioxidant composition, and a crosslinker, wherein the reinforcing filler is present in an amount of 30 to 70 parts by weight, the antioxidant composition is present in an amount of 0.1 to 8 parts by weight, and the crosslinker is present in an amount of 0.5 to 3 parts by weight, per 100 parts by weight of the diene elastomer, and the antioxidant composition contains a 6PPD antioxidant having a purity of about 98% by mass or greater and S-TMQ. Unless otherwise specified, the weight parts are based on 100 parts by weight of the diene elastomer in the rubber composition.

[0042] Here, the term "diene elastomer" refers to an elastomer whose monomer contains a diene (such as butadiene or isoprene). The diene elastomers applicable to the present invention are 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-butadiene rubber (NBR), isoprene / butadiene copolymer, isoprene / styrene copolymer, and isoprene / butadiene / styrene copolymer. In some embodiments, in the formulation of the rubber composition of the present invention, the diene elastomer comprises or consists of natural rubber and butadiene rubber, and the mass ratio of the natural rubber to the butadiene rubber may be in the range of 1:9 to 9:1, 2:8 to 8:2, 3:7 to 7:3, 4:6 to 6:4, 4.5:5.5 to 5.5:4.5, or 1:1. Examples of natural rubber include the first standard rubber of Chinese national standard GB / T 8081-2008 (commonly referred to as SCR5). Examples of butadiene rubber include butadiene rubber conforming to Chinese national standard GB / T 8659-2018 (commonly referred to as BR9000). Both national standards are incorporated herein by reference.

[0043] The rubber composition of the present invention generally contains 0.1 to 8 parts by weight, preferably 2 to 5 parts by weight, more preferably 3 to 4.5 parts by weight, and even more preferably 3.4 to 4 parts by weight of an antidegradant composition. The rubber composition of the present invention is characterized in that the antidegradant composition contains a 6PPD antidegradant having a purity of about 98% by mass or higher and S-TMQ. In one or more embodiments of the present invention, the antidegradant composition consists of a 6PPD antidegradant having a purity of about 98% by mass or higher and the S-TMQ. In the antidegradant composition, the mass ratio of the 6PPD antidegradant having a purity of about 98% by mass or higher to S-TMQ is generally 1:0.2 to 1:1, preferably 1:0.3 to 1:0.8, and more preferably 1:0.36 to 1:0.6. According to the present invention, by controlling the mass ratio of the 6PPD antioxidant to S-TMQ within the above range, it is possible to significantly improve the odor of rubber, improve the thermal oxidative aging resistance and tensile fatigue resistance of the rubber composition, and maintain the original tensile strength, original elongation at break, static ozone aging resistance, and dynamic ozone aging resistance. Generally, in the rubber composition of the present invention, the 6PPD antioxidant having a purity of about 98% by mass or higher is used in an amount of 0.1 to 4 parts by weight, preferably 1 to 4 parts by weight, more preferably 2 to 3 parts by weight, e.g., 2.2 to 2.8 parts by weight, 2.5±0.2 parts by weight, or 2.5±0.1 parts by weight. Generally, in the rubber composition of the present invention, S-TMQ is used in an amount of 0.1 to 4 parts by weight, preferably 0.5 to 3 parts by weight, more preferably 0.5 to 2 parts by weight, e.g., 0.6 to 1.8 parts by weight, 0.8 to 1.6 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.2 parts by weight, or 1.5 parts by weight. According to the present invention, when a rubber composition formulation contains a 6PPD antioxidant having a purity of about 98% by mass or higher and S-TMQ in the above-mentioned amounts, the rubber composition prepared therefrom exhibits significantly improved odor, improved resistance to thermal oxidative aging and tensile fatigue of the rubber, and good inherent tensile strength, inherent elongation at break, static ozone aging resistance, and dynamic ozone aging resistance.

[0044] The reinforcing filler used in the present invention may be any filler conventionally used in rubber compositions, including, but not limited to, one or more selected from carbon black, titanium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay, and talc. In some embodiments of the rubber composition of the present invention, the reinforcing filler is carbon black. Generally, the rubber composition formulation includes 30 to 70 parts by weight, preferably 40 to 60 parts by weight, and more preferably 45 to 55 parts by weight of the reinforcing filler. In some embodiments, the rubber composition formulation includes 30 to 70 parts by weight, preferably 40 to 60 parts by weight, and more preferably 45 to 55 parts by weight, of carbon black, for example, 50±2 parts by weight.

[0045] The crosslinking agent may be sulfur. Generally, the rubber composition formulation includes 0.5 to 3 parts by weight, preferably 1 to 3 parts by weight, and more preferably 1 to 2 parts by weight of the crosslinking agent. In some embodiments, the rubber composition formulation of the present invention includes 0.5 to 3 parts by weight, preferably 1 to 3 parts by weight, and more preferably 1 to 2 parts by weight, of carbon black, e.g., 1.5±0.2 parts by weight or 1.5±0.1 parts by weight.

[0046] The rubber composition formulation of the present invention may also contain other ingredients conventionally used in rubber compositions, including, but not limited to, one or more auxiliary agents and accelerators, which may be in amounts conventional in the art.

[0047] The auxiliary agent may include a softener used to improve processability and other properties. The softener may include petroleum softeners (hydraulic oils) such as naphthenic oil, aromatic oil, processing oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and petrolatum, and / or fatty oil softeners such as stearic acid, castor oil, linseed oil, rapeseed oil, coconut oil, waxes (e.g., beeswax, carnauba wax, lanolin), tall oil, linoleic acid, palmitic acid, and lauric acid. The auxiliary agent may include an activator such as zinc oxide, which can accelerate the vulcanization rate and improve the thermal conductivity, abrasion resistance, and tear resistance of the rubber. Generally, the auxiliary agent is used in an amount of 2 to 20 parts by weight per 100 parts by weight of diene elastomer. In some embodiments, the rubber composition of the present invention is formulated with a hydraulic oil such as naphthenic oil. The rubber composition compound of the present invention may contain 0 to 20 parts by weight, preferably 1 to 10 parts by weight, more preferably 2 to 8 parts by weight, for example, 5±2 parts by weight or 5±1 parts by weight, of a hydraulic oil such as naphthenic oil. In some embodiments, the rubber composition compound of the present invention may contain a fatty oil softener such as stearic acid. The rubber composition compound of the present invention may contain 0 to 5 parts by weight, preferably 0.5 to 4 parts by weight, more preferably 1 to 3 parts by weight, for example, 2±0.5 parts by weight or 2±0.2 parts by weight, of a fatty oil softener such as stearic acid. In some embodiments, the rubber composition compound of the present invention may contain an activator such as zinc oxide. The rubber composition compound of the present invention may contain 0 to 10 parts by weight, preferably 2 to 8 parts by weight, more preferably 3 to 7 parts by weight, for example, 5±1 parts by weight, of an activator such as zinc oxide. In some embodiments, the rubber composition compound of the present invention may contain a hydraulic oil, a fatty oil softener, and an activator. The amounts of the hydraulic oil, fatty oil softener, and activator are as described above.

[0048] The accelerator is generally a vulcanization accelerator and can be selected from one or more of sulfonamides, thiazoles, thiurams, thioureas, guanidines, dithiocarbamates, aldimines, aldehyde ammonia, imidazolines, and xanthic acid accelerators. For example, the accelerator can be N-cyclohexylbenzothiazole-2-sulfenamide (CBS). In some embodiments, the rubber composition formulation of the present invention includes an accelerator such as CBS. The rubber composition formulation of the present invention can include an accelerator such as CBS in an amount of 0 to 1.5 parts by weight, preferably 0.5 to 1.5 parts by weight, more preferably 0.5 to 1.2 parts by weight, e.g., 0.8±0.2 parts by weight or 0.8±0.1 parts by weight.

[0049] Furthermore, a plasticizer may be used in the rubber composition of the present invention, if necessary, such as dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diheptyl phthalate (DHP), dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), butyl benzyl phthalate (BBP), dilauryl phthalate (DWP), dicyclohexyl phthalate (DHP), etc. The plasticizer may be used in a conventional amount known in the art.

[0050] In some preferred embodiments, the rubber composition formulation of the present invention comprises 100 parts by weight of a diene elastomer; 40 to 60 parts by weight, preferably 45 to 55 parts by weight of a reinforcing filler; 1 to 3 parts by weight, preferably 1 to 2 parts by weight of sulfur; 2 to 5 parts by weight, preferably 3 to 4.5 parts by weight, more preferably 3.4 to 4 parts by weight of an antidegradant composition; 2 to 8 parts by weight, preferably 3 to 7 parts by weight of an activator; 0.5 to 4 parts by weight, preferably 1 to 3 parts by weight of a fatty oil softener; 1 to 10 parts by weight, preferably 2 to 8 parts by weight of a hydraulic oil; and 0.5 to 1.5 parts by weight, preferably 0.5 to 1.2 parts by weight of an accelerator, wherein the diene elastomer preferably comprises natural rubber and butadiene rubber in a mass ratio of 4:6 to 6:4, preferably 4.5:5.5 to 5.5:4.5; the reinforcing filler is preferably carbon black; and The antidegradant composition comprises a 6PPD antidegradant having a purity of about 98% by mass or higher and S-TMQ, or consists of a 6PPD antidegradant having a purity of about 98% by mass or higher and S-TMQ; preferably, the mass ratio of the 6PPD antidegradant having a purity of about 98% by mass or higher to S-TMQ is 1:0.2 to 1:1, preferably 1:0.3 to 1:0.8, more preferably 1:0.36 to 1:0.6; preferably, the rubber composition formulation comprises 1 to 4 parts by weight, preferably 2 to 3 parts by weight, of a 6PPD antidegradant having a purity of about 98% by mass or higher and 0.5 to 3 parts by weight, preferably 0.5 to 2 parts by weight of S-TMQ; the activator is preferably zinc oxide; the fatty oil softener is preferably stearic acid; the hydraulic oil is preferably naphthenic oil; and the accelerator is preferably a CBS accelerator.

[0051] The unvulcanized rubber of the present invention can be produced by conventional rubber mixing methods, such as a two-stage mixing method. In the first stage, an internal mixer is used to mix a diene elastomer, a reinforcing filler, an auxiliary agent, an antidegradant, and a rubber, and the rubber discharge temperature is set to 110°C or higher. In the second stage, an open mill is used to mix the rubber obtained in the first stage with a crosslinking agent and an accelerator. Generally, the diene elastomer is first charged into a thermomechanical mixer (such as an internal mixer). After mixing for a while, the reinforcing filler, auxiliary agent, and antidegradant composition are added to the diene elastomer, and the mixture is kneaded until the mixture is homogeneous. The reinforcing filler, auxiliary agent, and antidegradant composition can be added in batches. The temperature during mixing is controlled to 110°C to 190°C, preferably 150°C to 160°C. The mixture is then cooled to 100°C or below. A crosslinking agent and an accelerator are added to this mixture, and secondary kneading is carried out while controlling the temperature at 110°C or less, for example, 70±5°C, to obtain unvulcanized rubber.

[0052] The unvulcanized rubber of the present invention can be vulcanized by a conventional vulcanization method to obtain a vulcanized rubber. The vulcanization temperature is generally 130°C to 200°C, for example, 140°C to 150°C or 145±2°C. The vulcanization time depends on the vulcanization temperature, vulcanization system, and vulcanization kinetics, and is generally 15 to 60 minutes, for example, 20 to 30 minutes or 25±2 minutes. The kneaded unvulcanized rubber before vulcanization can be subjected to conventional tableting.

[0053] In some embodiments, the rubber composition of the present invention is prepared by the following method. (1) homogeneously mixing a diene elastomer, a reinforcing filler, an auxiliary agent, and an anti-degradant in a thermomechanical mixer (e.g., an internal mixer) at a rubber discharge temperature of preferably 110°C or higher, e.g., 140°C or higher; (2) The rubber obtained in step (1), vulcanizing agent, and accelerator are uniformly mixed in a thermomechanical mixer (e.g., an open mill) at a tablet discharge temperature of preferably 110°C or less, for example, 70±5°C, to obtain unvulcanized rubber.

[0054] In some preferred embodiments, the method for preparing the rubber composition of the present invention further includes (3) optionally pressing the unvulcanized rubber and then vulcanizing the unvulcanized rubber to obtain a vulcanized rubber. Preferably, the vulcanization temperature is 130°C to 200°C, for example, 140°C to 150°C. Preferably, the vulcanization time is 15 to 60 minutes, for example, 20 to 30 minutes.

[0055] Compared with rubber compositions containing a combination of a 6PPD antioxidant and a TMQ antioxidant with lower purities, the use of the rubber composition of the present invention in rubber products, particularly rubber tires, not only significantly improves the odor of the rubber product, but also improves the thermal oxidative aging resistance and tensile fatigue resistance of the rubber product with a smaller amount of antioxidant, while maintaining the original tensile strength, original elongation at break, static ozone aging resistance, and dynamic ozone aging resistance.

[0056] Accordingly, the present invention also provides a rubber product comprising the rubber composition described herein. The rubber product may be a tire, rubber overshoe, sealing strip, acoustic panel, crash pad, or the like. In some embodiments, the rubber product is a tire, such as a tire tread, belt ply, or sidewall. As a tire belt ply, the rubber product may further comprise, in addition to the rubber composition of the present invention, a reinforcing agent conventionally used in the art. The present invention further provides the use of a 6PPD antidegradant having a purity of about 98% by mass or greater and S-TMQ in improving the odor of a rubber composition or rubber product, and / or improving the thermal oxidative aging resistance and / or tensile fatigue resistance of a rubber composition or rubber product. In the use of the present invention, the preferred 6PPD antidegradant having a purity of about 98% by mass or greater, the preferred S-TMQ, and the dosage ratio of both are as described in the embodiments. [Example]

[0057] The present invention will be described below based on specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. Unless otherwise specified, the methods, reagents, and materials used in the examples are conventional methods, reagents, and materials in the art. The raw materials used in the examples are commercially available.

[0058] The sources of raw materials and ingredients used in the preparation and testing examples are as follows: NR: Xishuangban Nazhonghua Rubber Co., Ltd., SCR5; BR9000: Nanjing Yangtze Petrochemical Rubber Co., Ltd., synthetic rubber BR9000; N550: Cabot Corporation, Carbon Black N550; Zinc oxide: Shanghai Taitan Technology Co., Ltd., general reagent, zinc oxide (AR); Stearic acid: Shanghai Taitan Technology Co., Ltd., general reagents, stearic acid (AR); Naphthenic oil: Maoming Runhua Petrochemical Co., Ltd., naphthenic oil KN4010; 6PPD deterioration inhibitor 1: Seioku Chemical Technology Co., Ltd., purity 97.0%; TMQ anti-degradation agent: Seio Chemical Technology Co., Ltd.; 6PPD anti-degradation agent 2: Seioku Chemical Technology Co., Ltd., purity 98.5%; S-TMQ: Kemai Chemical Co., Ltd.; CBS: Shandong Yanggu Huatai Chemical Co., Ltd.; S: Sinopharm Chemical Reagent Company, sublimable sulfur (AR).

[0059] Preparation Examples 1 to 4: Preparation of vulcanized rubber films The rubber compositions of Examples 1-4 and the Comparative Example were prepared by a laboratory mixing process and a two-stage mixing method from the formulations shown in Table 1 using the following specific steps: 1. First stage mixing using an internal mixer: natural rubber (NR), synthetic rubber BR9000, carbon black N550, zinc oxide, stearic acid (SA), naphthenic oil, and antidegradants (6PPD antidegradant 1 and TMQ antidegradant, or 6PPD antidegradant 2 and S-TMQ) were placed in an internal mixer, and the mixture was mixed uniformly, with the rubber discharge temperature set to 140°C; 2. The second stage of mixing by open mill: the rubber, sulfur (S) and accelerator CBS obtained in the first stage were added to the open mill, the mixture was mixed uniformly, and the film discharge temperature was set to 70°C; 3. Vulcanization: The rubber obtained by the two-stage mixing was rolled into a film of 2 mm thickness and vulcanized at 145°C for 25 minutes to obtain a vulcanized rubber film. Each vulcanized film was cut into rubber particles of approximately 2 mm*2 mm*2 mm size for subsequent odor evaluation and VOC analysis.

[0060] [Table 1]

[0061] Test Example 1: Odor Evaluation The odor grades of the vulcanized rubber films of Examples 1 to 4 and the Comparative Example were evaluated in accordance with the published odor detection standard VW50180. The specific method was as follows: The odor grade of vulcanized rubber films is evaluated at normal and elevated temperatures according to the odor grade criteria in Table 2. a.Put 20g of sample into a 1L odor bottle, leave it at room temperature for 24 hours, and evaluate the odor; b. Place 20 g of sample in a 1 L odor bottle, leave at 80°C for 2 hours, then cool to room temperature and evaluate the odor.

[0062] Each evaluation was conducted by five people using a subjective evaluation method. As shown in Table 2, odor intensity was divided into six grades, from Grade 1 to Grade 6, ranging from imperceptible to unbearable. The average of the five evaluation results was taken to distinguish and compare the odor intensity of the samples. The results are shown in Table 3.

[0063] [Table 2]

[0064] Test Example 2: VOC analysis of rubber film Volatile substances in the vulcanized rubber films of Examples 1 to 4 and the Comparative Example were qualitatively analyzed by headspace gas chromatography-mass spectrometry (HS-GCMS). Samples were injected under the same high-temperature conditions (80°C x 2 hours) as in the odor evaluation in Test Example 1. The obtained spectra were compared with standard spectra from the NIST library to identify volatile substances, and the content of each substance was calculated using the area normalization method. The test conditions were as follows: HS: 80°C, 120 minutes; GC-MS capillary column: HP-5MS (30 m x 0.25 mm x 0.25 μm); process: hold at 60°C for 2 minutes, increase to 280°C at a rate of 10°C / min, hold for 2 minutes, increase to 300°C at a rate of 10°C / min, and maintain for 2 minutes. The VOC analysis results for the vulcanized rubber films are shown in Table 3.

[0065] [Table 3]

[0066] The odor grade evaluation results in Table 3 show that the odor of the rubber mixed with the combination of 6PPD antidegradant 2 / S-TMQ (Examples 1-4) was lower than that of the rubber mixed with the combination of 6PPD antidegradant 1 / TMQ (Comparative Example) at both room temperature and high temperature. The odor grade of the rubber of the Examples at room temperature did not exceed Grade 3.1, indicating only a slight odor. At high temperatures, the odor grade of the rubber of the Examples did not exceed Grade 3.3, meaning there was no unpleasant odor, while the corresponding rubber of the Comparative Example emitted an unpleasant odor, reaching an odor grade of Grade 4.

[0067] Test Example 3: Physical and mechanical properties and aging resistance The physical and mechanical properties and aging properties such as thermal oxidation resistance, ozone resistance, and tensile fatigue resistance of the vulcanized rubber films of Examples 1 to 4 and the Comparative Example were tested according to the following rubber test standards, and the test results are shown in Table 4. Tensile strength and elongation at break: GB / T 528-2009 Rubber, vulcanized or thermoplastic - Determination of tensile stress and strain properties; GB / T 3512-2001 Rubber, vulcanized or thermoplastic - Accelerated aging and heat resistance test - Air oven method; Static ozone aging resistance: GB / T 7762-2014 Rubber, vulcanized or thermoplastic - Resistance to ozone cracking - Static strain test - Method A; Dynamic ozone aging resistance: GB / T 13642-2015 Rubber, vulcanized or thermoplastic - Resistance to ozone cracking - Dynamic strain test - Method A; Tensile fatigue resistance: GB / T 1688-2008 Rubber, vulcanized - Determination of tensile fatigue.

[0068] [Table 4]

[0069] The results in Table 4 show that the physical properties of the rubbers of Examples 1 to 4 did not change significantly compared to the comparative examples, but the thermal oxidative aging resistance and tensile fatigue resistance were slightly improved. This indicates that the combination of an antioxidant, 6PPD with a purity of about 98% by mass or more, and S-TMQ can improve the odor grade of tire rubber and improve the thermal oxidative aging resistance and tensile fatigue resistance of the rubber, while maintaining the physical properties of the rubber.

[0070] Test Example 4 According to the method of Test Example 1, the odors of 6PPD antidegradants 1 and 2 were evaluated. According to the method of Test Example 2, the volatile substances in 6PPD antidegradant 1 and 6PPD antidegradant 2 were qualitatively analyzed. Table 5 shows the main physical and chemical properties, odor evaluation results, and VOC analysis results of 6PPD Antidegradant 1 and 6PPD Antidegradant 2.

[0071] [Table 5]

[0072] The results in Table 5 show that at room temperature, 6PPD Antidegradant 2 had a lower odor intensity than 6PPD Antidegradant 1, with the odor grade reduced by more than two grades, indicating that 6PPD Antidegradant 2 had only a slight odor. The results at high temperatures show that 6PPD Antidegradant 2 had a lower odor intensity than 6PPD Antidegradant 1, with the odor grade reduced by more than one grade. VOC analysis showed that 6PPD Antidegradant 2 contained less than half the types of organic volatile substances found in 6PPD Antidegradant 1, and that the total VOCs of 6PPD Antidegradant 2 were approximately 90% lower by mass than those of 6PPD Antidegradant 1, with the content of MIBK and aniline, which have pungent odors, also reduced by approximately 90% by mass. This is the direct reason for the improved odor.

[0073] Test Example 5 According to the method of Test Example 1, the odors of S-TMQ and the TMQ deterioration inhibitor were evaluated. According to the method of Test Example 2, the volatile substances in S-TMQ and the TMQ deterioration inhibitor were qualitatively analyzed. Table 6 shows the main physical and chemical properties, odor evaluation results, and VOC analysis results of S-TMQ and TMQ antidegradants.

[0074] [Table 6]

[0075] The results in Table 6 show that at room temperature, S-TMQ had a lower odor intensity than TMQ antidegradants, approximately 0.5 odor grades lower, and no obvious odor was present. At elevated temperatures, the results also showed that S-TMQ had a lower odor intensity than TMQ antidegradants, approximately 0.5 odor grades lower. VOC analysis results showed that the types of organic volatile substances in the S-TMQ sample were approximately 40% lower than those in the TMQ antidegradants, the total VOCs in the S-TMQ sample were approximately 60% lower by mass than those in the TMQ antidegradants, and the contents of both aniline and acetone, which have pungent odors, were reduced by more than 70% by mass. Furthermore, the contents of dimers, trimers, and tetramers in S-TMQ were more than 30% higher by mass than those in the TMQ antidegradants.

Claims

1. The rubber composition contains 100 parts by weight of a diene elastomer, 30 to 70 parts by weight of a reinforcing filler, 0.1 to 8 parts by weight of an antidegradant composition, and 0.5 to 3 parts by weight of a crosslinking agent, wherein the antidegradant composition contains a 6PPD antidegradant having a purity of 98% by mass or more and S-TMQ, and the S-TMQ is a TMQ antidegradant having a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 80% by mass or more.

2. 2. The rubber composition according to claim 1, wherein the purity of the 6PPD antidegradant is 98.5% by mass or more.

3. 2. The rubber composition according to claim 1, wherein the number of types of organic volatile substances in the 6PPD antidegradant is 5 or less.

4. the total content of organic volatile substances in the 6PPD anti-degradant does not exceed 10% of the total content of organic volatile substances in the 6PPD anti-degradant having a purity of 97% by mass; The content of 4-methyl-2-pentanone in the 6PPD antidegradant does not exceed 12% of the content of 4-methyl-2-pentanone in a 6PPD antidegradant having a purity of 97% by mass; and The content of aniline in the 6PPD antidegradant does not exceed 6.2% of the content of aniline in a 6PPD antidegradant having a purity of 97% by mass; The rubber composition of claim 1 .

5. The rubber composition according to claim 1, characterized in that the total content of dimers, trimers and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline in the S-TMQ is 80.2 mass % or more.

6. 2. The rubber composition according to claim 1, wherein the number of types of organic volatile substances in the S-TMQ is 8 or less.

7. the total content of organic volatile substances in the S-TMQ does not exceed 41.7% of the total content of organic volatile substances in a TMQ deterioration inhibitor in which the total content of dimers, trimers, and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline is 51% by mass; the content of acetone in the S-TMQ does not exceed 20.5% of the content of acetone in a TMQ deterioration inhibitor in which the total content of dimers, trimers, and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline is 51% by mass; The aniline content in the S-TMQ does not exceed 27.3% of the aniline content in a TMQ deterioration inhibitor in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer is 51% by mass; and the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the S-TMQ does not exceed 64.8% of the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the TMQ deterioration inhibitor, in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer is 51% by mass; The rubber composition of claim 1 .

8. 2. The rubber composition according to claim 1, wherein the mass ratio of the 6PPD antioxidant to the S-TMQ in the antioxidant composition is 1:0.2 to 1:

1.

9. 2. The rubber composition formulation of claim 1, wherein the formulation comprises 2 to 5 parts by weight of the antidegradant composition per 100 parts by weight of the diene elastomer.

10. 2. The rubber composition according to claim 1, wherein the antidegradant composition comprises the 6PPD antidegradant having a purity of 98% by mass or more and the S-TMQ.

11. 10. The rubber composition formulation of claim 1, wherein the diene elastomer comprises one or more selected from natural rubber, butadiene rubber, isoprene rubber, styrene butadiene rubber, chloroprene rubber, nitrile rubber, isoprene / butadiene copolymer, isoprene / styrene copolymer, and isoprene / butadiene / styrene copolymer.

12. The rubber composition formulation according to claim 11, wherein the diene elastomer comprises natural rubber and butadiene rubber, and the mass ratio of the natural rubber to the butadiene rubber is 4:6 to 6:

4.

13. 10. The rubber composition formulation of claim 1, wherein the reinforcing filler comprises one or more selected from carbon black, titanium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay, and talc.

14. 2. The rubber composition of claim 1, wherein the crosslinking agent is sulfur.

15. 10. The rubber composition compound of claim 1, wherein the compound further comprises one or more selected from softeners, activators, and accelerators.

16. 100 parts by weight of a diene elastomer, 40 to 60 parts by weight of carbon black, 1 to 2 parts by weight of sulfur, 2 to 3 parts by weight of the 6PPD deterioration inhibitor having a purity of 98% by mass or more; 0.5 to 2 parts by weight of the S-TMQ; 2 to 8 parts by weight of zinc oxide, 1 to 3 parts by weight of stearic acid, 1 to 10 parts by weight of naphthenic oil, and 0.5 to 1.5 parts by weight of an accelerator; The diene elastomer contains natural rubber and butadiene rubber in a mass ratio of 4:6 to 6:

4. The rubber composition of claim 1 .

17. The purity of the 6PPD antidegradant is 98.5% by mass; The number of kinds of organic volatile substances in the 6PPD deterioration inhibitor is 5; the total content of the organic volatile substances in the 6PPD deterioration inhibitor is 10% of the total content of the organic volatile substances in the 6PPD deterioration inhibitor having a purity of 97% by mass; The content of 4-methyl-2-pentanone in the 6PPD deterioration inhibitor is 12% of the content of 4-methyl-2-pentanone in a 6PPD deterioration inhibitor having a purity of 97% by mass; The content of aniline in the 6PPD deterioration inhibitor is 6.2% of the content of aniline in a 6PPD deterioration inhibitor having a purity of 97% by mass, The total content of dimers, trimers, and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline in the S-TMQ was 80.2% by mass; The number of types of organic volatile substances in the S-TMQ is 8; The total content of organic volatile substances in the S-TMQ was 41.7% of the total content of organic volatile substances in the TMQ deterioration inhibitor in which the total content of dimers, trimers, and tetramers of 1,2-dihydro-2,2,4-trimethylquinoline was 51% by mass; The acetone content in the S-TMQ was 20.5% of the acetone content in the TMQ deterioration inhibitor in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer was 51% by mass; The aniline content in the S-TMQ was 27.3% of the aniline content in the TMQ deterioration inhibitor in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer was 51% by mass; The content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the S-TMQ is 64.8% of the content of 1,2-dihydro-2,2,4-trimethylquinoline monomer in the TMQ deterioration inhibitor, in which the total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer is 51% by mass. The rubber composition of claim 1 .

18. A rubber composition prepared from the formulation of claim 1.

19. A rubber article comprising a rubber composition prepared from the formulation of claim 1.

20. a rubber composition containing 6PPD and S-TMQ, and a rubber product prepared from the rubber composition; the 6PPD deterioration inhibitor has a purity of 98% by mass or more, and the S-TMQ is a TMQ deterioration inhibitor having a total content of 1,2-dihydro-2,2,4-trimethylquinoline dimer, trimer, and tetramer of 80% by mass or more; A method for improving odor, thermal oxidative aging resistance, tensile fatigue resistance, or a combination thereof, of a rubber composition or rubber product.

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