Rubber composition containing antioxidant, and preparation method therefor and use thereof
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SHANDONG YANGGU HUATAI CHEM
- Filing Date
- 2025-07-30
- Publication Date
- 2026-06-18
Smart Images
Figure CN2025111524_18062026_PF_FP_ABST
Abstract
Description
A rubber composition containing an antioxidant, its preparation method and application Technical Field
[0001] This invention relates to a rubber composition containing an antioxidant and its preparation method, as well as the application of the rubber composition containing the antioxidant in tires, belonging to the field of tire manufacturing technology. Background Technology
[0002] As one of the three major synthetic polymer materials, rubber inevitably ages during storage, transportation, processing, and use, leading to safety issues in tires. To improve the aging resistance of rubber and other polymer materials and slow down or delay their aging rate, the primary method is to add antioxidants during tire compound processing. This reduces the rate of rubber aging, extends the reaction induction period, and thus improves the aging resistance of rubber materials.
[0003] Antioxidant 4020, chemically named N-(1-methylisopentyl)-N'-phenyl-p-phenylenediamine, also known as 6PPD, plays an irreplaceable role in the tire and rubber products industry. Its excellent anti-aging, anti-ozone, and fatigue resistance properties make it a key antioxidant. However, 6PPD has the following problems: (1) When a tire rubs against the road surface during driving, it releases particles containing 6PPD. These particles react with ozone and are converted into 6PPD-quinone, a chemical substance that is extremely toxic to aquatic organisms. On July 26, 2023, the California Department of Toxic Substances Control (DTSC) passed a strict regulation. The regulation stipulates that from October 1, 2023, all tire manufacturers operating in California must begin to evaluate and find safer materials to replace 6PPD. Finding safer alternatives has also become a focus of industry attention. (2) With increasingly fierce market competition in the global tire industry, the appearance of tires has become an industry concern. The addition of 6PPD will cause the tire sidewall, tread and other external parts to turn red and discolor, which is a pain point in the tire industry.
[0004] Therefore, finding a better alternative to antioxidant 4020, so that tire products not only have good ozone protection, but also do not produce toxic quinone substances during use, and can maintain a good appearance of the rubber compound, has been a long-standing pursuit in the industry. Summary of the Invention
[0005] To address the problems existing in the prior art, the present invention provides a rubber composition containing an antioxidant. The rubber composition contains a novel antioxidant, which not only enables the rubber composition to have excellent anti-aging properties, but also reduces harm to the environment and human body, making it more suitable for industrial applications and a good alternative to antioxidant 4020.
[0006] The specific technical solution of this invention is as follows:
[0007] A rubber composition containing an antioxidant, the rubber composition comprising rubber and an antioxidant used to improve the aging resistance of the rubber. The antioxidant may be one type or a combination of two or more types, and the antioxidant includes at least one compound with the structure shown in formulas (1)-(4):
[0008] In formulas (1), (2), (3), and (4), R1 and R2 are each independently selected from hydrogen, cyclohexyl, cyclooctyl, 2-cyclohexylethyl, 2-phenylethyl, benzyl, and long-chain or branched alkyl groups with 1-15 carbon atoms. The long-chain or branched alkyl groups with 1-15 carbon atoms can be methyl, ethyl, isopropyl, 1,3-dimethylbutyl, 1,4-dimethylpentyl, etc.
[0009] Furthermore, in addition to the compounds with the structures shown in formulas (1)-(4) above, the antioxidants may also include antioxidants with other structures, which can be selected from antioxidants commonly used in the existing rubber and tire industries.
[0010] Furthermore, based on a rubber weight of 100 parts, the total amount of antioxidants with the structures shown in formulas (1)-(4) is 0.1 to 5 parts by weight.
[0011] Furthermore, based on a rubber weight of 100 parts, the total amount of antioxidants in other structures is 1 to 10 parts by weight.
[0012] Furthermore, in addition to rubber and antioxidant, the rubber composition also includes at least one of vulcanizing agent, filler, and other additives.
[0013] Furthermore, based on 100 parts by weight of rubber, the vulcanizing agent is 0.01 to 20 parts by weight, the filler is 10 to 150 parts by weight, and other additives are 0.5 to 200 parts by weight.
[0014] Furthermore, the other additives include at least one of activators, processing aids, accelerators, and functional additives.
[0015] Furthermore, based on 100 parts by weight of rubber, the activator is 0-20 parts by weight, the processing aid is 0-30 parts by weight, the accelerator is 0-20 parts by weight, and the functional aid is 0-50 parts by weight.
[0016] The present invention also provides a method for preparing the above-mentioned rubber composition containing antioxidant, the method comprising the following steps:
[0017] (1) Mix the raw materials together and knead them to obtain the kneaded material;
[0018] (2) The mixed materials are vulcanized to obtain a rubber composition.
[0019] The present invention also provides the application of the above-mentioned rubber composition containing antioxidant in rubber products, wherein the rubber products are products in which the raw materials contain rubber, such as tires.
[0020] The present invention also provides a method for improving the aging resistance of rubber products. The method involves adding an antioxidant during the preparation of the rubber product. The antioxidant includes at least one compound with the structure shown in formulas (1)-(4) above. The antioxidant can be one or more compounds. In addition to the compounds with the structure shown in formulas (1)-(4) above, it may also contain antioxidants with other structures. The selection of antioxidants with other structures is consistent with the above description.
[0021] This invention introduces a novel antioxidant into a rubber composition. This novel antioxidant exhibits excellent anti-aging and mechanical aging resistance, as well as excellent resistance to ozone aging and cracking. It can completely or partially replace antioxidant 4020, providing a new solution for the tire and rubber products industry. Attached Figure Description
[0022] Figure 1 shows the carbon NMR spectrum of antioxidant ①.
[0023] Figure 2 shows the carbon NMR spectrum of antioxidant ②.
[0024] Figure 3 shows the carbon NMR spectrum of antioxidant ③.
[0025] Figure 4 shows the carbon NMR spectrum of antioxidant ④.
[0026] Figure 5 shows the carbon NMR spectrum of antioxidant ⑤.
[0027] Figure 6 shows the carbon NMR spectrum of antioxidant ⑥.
[0028] Figure 7 shows the carbon NMR spectrum of antioxidant ⑦.
[0029] Figure 8 shows the carbon NMR spectrum of antioxidant ⑧. Detailed Implementation
[0030] The following description illustrates exemplary embodiments of the present invention, including various details to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions, operations, and structures are omitted in the following description.
[0031] Unless otherwise defined, the technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. While similar or identical methods and materials may be applied in experimental or practical applications, the present invention describes materials and methods hereinafter. In case of conflict, the definitions included herein shall prevail.
[0032] The rubber composition of the present invention includes rubber and an antioxidant. The rubber may be at least one of natural rubber, styrene-butadiene rubber, cis-butadiene rubber, etc., but is not limited to these.
[0033] The antioxidant can be one type, or a combination of two or more types, and the antioxidant includes novel antioxidants, which include at least one of the compounds with the structures shown in formulas (1) to (4):
[0034] In formulas (1), (2), (3), and (4), R1 and R2 are each independently selected from hydrogen, cyclohexyl, cyclooctyl, 2-cyclohexylethyl, 2-phenylethyl, benzyl, and long-chain or branched alkyl groups with 1-15 carbon atoms. The long-chain or branched alkyl groups with 1-15 carbon atoms can be methyl, ethyl, isopropyl, 1,3-dimethylbutyl, 1,4-dimethylpentyl, etc.
[0035] Furthermore, the novel antioxidants described in formulas (1)-(4) can be selected from at least one of the compounds shown in ①-⑧ below:
[0036] Furthermore, the application fields of the novel antioxidant of this invention include the rubber or plastic products industry.
[0037] Furthermore, in addition to the compounds with the structures shown in formulas (1)-(4) above, the antioxidants may also include antioxidants with other structures. There are no special limitations on the types of antioxidants with other structures. Antioxidants well known to those skilled in the art can be used, such as antioxidants 6PPD (4020), IPPD (4010NA), 7PPD, 8PPD, antioxidants TMQ (RD), 77PD (4030), antioxidant AW, protective wax, etc.
[0038] Furthermore, based on 100 parts by weight of rubber, the total amount of the novel antioxidants with the structures shown in formulas (1)-(4) is 0.1 to 5 parts by weight, for example 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 parts, preferably 0.5 to 3 parts, and more preferably 1.5 to 3 parts.
[0039] Furthermore, based on 100 parts by weight of rubber, the total amount of antioxidants of other structures is 1 to 10 parts by weight, such as 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, preferably 1 to 6 parts.
[0040] Furthermore, in addition to rubber and antioxidant, the rubber composition also includes at least one of vulcanizing agent, filler, and other additives.
[0041] Furthermore, based on 100 parts by weight of rubber, the vulcanizing agent is 0.01 to 20 parts by weight, for example, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, or 20 parts, preferably 1 to 15 parts.
[0042] Furthermore, the vulcanizing agent promotes the cross-linking reaction of the rubber, causing the linear molecules to form a three-dimensional network structure, resulting in rubber that is both elastic and strong. There are no special requirements for the vulcanizing agent; it can be at least one of those commonly used in the rubber and tire industries, such as sulfur, insoluble sulfur, or peroxides.
[0043] Furthermore, based on 100 parts by weight of rubber, the filler is 10 to 150 parts by weight, for example 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 150 parts, preferably 30 to 120 parts.
[0044] Furthermore, the filler is at least one selected from carbon black, mineral filler, silica, calcium carbonate, and clay. This invention does not impose any special limitations on the specific ratio of the filler; any mixture in any proportion can be used. In this invention, there are no special requirements regarding the source of the filler; commercially available products familiar to those skilled in the art can be used, specifically, carbon black N134, N220, N234, N330, N326, N375, N550, N660, N770, or precipitated silica or other silica types.
[0045] Furthermore, based on a rubber weight of 100 parts, other additives are 0.5 to 200 parts by weight, for example, 0.5 parts, 1 part, 5 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts, and 200 parts.
[0046] In a specific embodiment of the present invention, the rubber composition comprises the following components in parts by weight: 100 parts of rubber, 0.01 to 20 parts of vulcanizing agent, 0.1 to 5 parts of novel antioxidant, 1 to 10 parts of antioxidant with other structures, 10 to 150 parts of filler, and 0.5 to 200 parts of other additives.
[0047] Furthermore, the other additives include at least one of activators, processing aids, accelerators, and functional additives.
[0048] Furthermore, based on 100 parts by weight of rubber, the activator is 0 to 20 parts by weight, for example, 0 parts, 0.01 parts, 0.05 parts, 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, preferably 3 to 10 parts. The activator promotes the vulcanization, activation, and reinforcement of rubber, prevents aging, strengthens the vulcanization process, and improves the tear resistance and abrasion resistance of rubber products. This invention does not impose any specific limitations on the type of activator; any activator well-known to those skilled in the art can be used, such as ZnO.
[0049] Furthermore, based on a rubber weight of 100 parts, the processing aid is 0 to 30 parts by weight, for example, 0 parts, 0.01 parts, 0.05 parts, 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, etc. 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, 21 parts, 21.5 parts, 22 parts, 22.5 parts, 23 parts, 23.5 parts, 24 parts, 24.5 parts, 25 parts, 25.5 parts, 26 parts, 26.5 parts, 27 parts, 27.5 parts, 28 parts, 28.5 parts, 29 parts, 29.5 parts, 30 parts. Processing aids specifically refer to additives that help with the processing of rubber compounds. Examples include additives used to improve mixing operations and the processing properties of compounded rubber in calendering, extrusion, and injection molding. Examples include lubricants, dispersants, homogenizers, release agents, and physical plasticizers. The present invention does not have any special limitation on the type of processing aids. Processing aids that are well known to those skilled in the art can be used, such as plasticizer A, homogenizer H40MSF, dispersant H60EF, etc.
[0050] Furthermore, based on a rubber weight of 100 parts, the accelerator is 0 to 20 parts by weight, for example, 0 parts, 0.01 parts, 0.05 parts, 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, preferably 1 to 6 parts. Accelerators are substances that promote vulcanization, shortening the vulcanization time or lowering the vulcanization temperature of rubber, reducing the amount of vulcanizing agent used, and improving the physical and mechanical properties of rubber. This invention does not specifically limit the type of accelerator; accelerators well-known to those skilled in the art can be used. Specific examples include NS, DM, CBS, DCBS, TMTD, and TBBS (NS).
[0051] Furthermore, based on a rubber weight of 100 parts, the functional additives range from 0 to 50 parts by weight, for example, 0 parts, 0.5 parts, 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, and 50 parts. Functional additives refer to additives other than antioxidants, vulcanizing agents, activators, processing aids, and accelerators, which can enhance the rubber composition with certain special functions and may also possess some of the functions of other types of additives. This invention does not specifically limit the types of functional additives; those skilled in the art and those commonly used in rubber formulations can use them, such as tread functional resins and silane coupling agents.
[0052] The present invention also provides a method for preparing the above-mentioned rubber composition, comprising the following steps:
[0053] (1) Mix the raw materials together and knead them to obtain the kneaded material;
[0054] (2) The mixed materials are vulcanized to obtain a rubber composition.
[0055] Furthermore, in step (1), rubber, vulcanizing agent, antioxidant, filler, and other additives are mixed together for compounding. There are no special requirements for the mixing order between them. The mixing order commonly used in the industry can be followed. For example, filler, antioxidant, and processing aids can be mixed with rubber first to obtain pre-mixed material, and then vulcanizing agent and accelerator can be added for compounding to obtain compounded material.
[0056] Furthermore, in step (1), the mixing temperature is 60–160°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or 160°C. The mixing time is 1–20 min, for example, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min, preferably 3–10 min.
[0057] In one embodiment of the present invention, the mixing method is as follows: first, fillers, antioxidants, and processing aids are mixed with rubber and then mixed to obtain a premixed material; after the temperature of the premixed material is below 110°C, a vulcanizing agent and an accelerator are added. In the present invention, the temperature at which the vulcanizing agent and the accelerator are added is preferably 70–100°C.
[0058] Furthermore, in step (2), after obtaining the compound material, the present invention vulcanizes the compound material to obtain a rubber composition. The vulcanization temperature is 120-200℃, for example 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, preferably 140-180℃. The vulcanization time is 5–90 minutes, for example, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min, 43 min, 44 min, 45 min, 46 min, 47 min, 48 min, 4… 9 min, 50 min, 51 min, 52 min, 53 min, 54 min, 55 min, 56 min, 57 min, 58 min, 59 min, 60 min, 61 min, 62 min, 63 min, 64 min, 65 min, 66 min, 67 min, 68 min, 69 min, 70 min, 71 min, 72 min, 73 min, 74 min, 75 min, 76 min, 77 min, 78 min, 79 min, 80 min, 81 min, 82 min, 83 min, 84 min, 85 min, 86 min, 87 min, 88 min, 89 min, 90 min, preferably 10 to 60 min, more preferably 10 to 30 min.
[0059] Furthermore, the present invention does not impose any special limitations on the mixing and vulcanization equipment; any equipment familiar to those skilled in the art can be used. Specifically, the mixing process uses an internal mixer or an open mill, and the vulcanization process uses a vulcanizing machine.
[0060] The present invention also provides the application of the above-described rubber composition in rubber products, wherein the rubber products are products containing rubber in any raw materials, such as tires.
[0061] The present invention also provides a method for improving the aging resistance of rubber products. The method is as follows: an antioxidant is added during the preparation of the rubber product. The antioxidant includes the above-mentioned novel antioxidants. The antioxidant can be at least one of the above-mentioned novel antioxidants, or it can be a combination of the above-mentioned novel antioxidants and antioxidants with other structures.
[0062] The following detailed description of the rubber composition and advantages provided by the present invention, in conjunction with specific examples, should not be construed as limiting the scope of protection of the present invention.
[0063] The antioxidants used in the following embodiments have the following structural formulas:
[0064] The preparation method of antioxidant ① is as follows: 29.9 g (0.15 mol) of 2,4-diaminodiphenylamine, 1.4 g of platinum, and 130.7 g (2.25 mol) of acetone are weighed and added to a 1 L high-pressure reactor. The air in the reactor is first replaced with nitrogen three times, and then replaced with hydrogen three times. When the temperature is raised to 80℃, hydrogen is introduced to 3.5 MPa. When the pressure in the reactor drops to 1 MPa, hydrogen is introduced again to 3.5 MPa. When the pressure in the reactor is maintained at 1 MPa and no longer changes, the reaction is considered complete. Then, the temperature is lowered and the pressure is released to release the reaction liquid. The catalyst is filtered out (this process can be repeated 2-3 times). The excess acetone and by-product isopropanol are removed by rotary evaporation of the filtrate to obtain antioxidant ①. The NMR spectrum of antioxidant ① is shown in Figure 1.
[0065] The preparation method of antioxidant ② is as follows: Weigh 29.9 g (0.15 mol) of 2,4-diaminodiphenylamine, 1.4 g of copper-zinc alloy, and 186.4 g (1.9 mol) of cyclohexanone and add them to a 1 L high-pressure reactor. First, replace the air in the reactor with nitrogen three times, and then replace it with hydrogen three times. When the temperature is raised to 180℃, hydrogen is introduced to 4 MPa. When the pressure in the reactor drops to 1 MPa, hydrogen is introduced again to 4 MPa. When the pressure in the reactor is maintained at 1 MPa and no longer changes, the reaction is considered complete. Then, the temperature is lowered and the pressure is released to release the reaction liquid. Filter to remove the catalyst (this process can be repeated 2-3 times). Rotary evaporation of the filtrate removes excess cyclohexanone and by-product cyclohexanol, yielding antioxidant ②. The NMR spectrum of antioxidant ② is shown in Figure 2.
[0066] The preparation method of antioxidant ③ is as follows:
[0067] Step 1: Synthesis of intermediate formamide
[0068] 27.95 g (0.3 mol) of aniline and 280 g of toluene were weighed and added to a 1000 mL reaction apparatus equipped with a water separator. 34.53 g (0.75 mol) of formic acid was weighed and placed in a constant pressure dropping apparatus. When the temperature was raised to 80 °C, the formic acid was added dropwise. During the dropwise addition, the temperature was maintained at 90–100 °C. After the dropwise addition was completed within 1 hour, the reaction was continued under reflux for 1 hour. Then, the toluene and excess formic acid were distilled off under reduced pressure. The remaining material was poured into cold water and stirred. A white solid precipitated. The solid was filtered and washed with cold water until neutral. The filter cake was dried under vacuum at 30–40 °C to obtain 35.98 g of formamide aniline.
[0069] The second step is the synthesis of the intermediate 2-anilino-5-nitropyridine.
[0070] Weigh 30.30 g (0.25 mol) of formaniline, 31.75 g (0.2 mol) of 2-chloro-5-nitropyridine, 31.0 g (0.224 mol) of potassium carbonate and 300 mL of p-xylene and add them to a 1000 mL reaction apparatus equipped with a water separator. Heat to reflux (170-190 °C) and react for 5 hours. When the water level in the water separator stops rising, the reaction is complete. Add a small amount of liquid alkali to decompose the residual formaniline and remove the residual toluene from the reaction apparatus under vacuum. Transfer the material in the reaction apparatus to a heat-insulated separator while it is still hot, wash with hot water until neutral, and then pour it into a pan for vacuum drying to obtain 42.1 g of 2-aniline-5-nitropyridine.
[0071] The third step is the synthesis of antioxidant products.
[0072] 32.28 g (0.15 mol) of 2-anilino-5-nitropyridine, 22.54 g (0.225 mol) of 4-methyl-2-pentanone, 1.3 g of palladium on carbon, and 280 mL of methanol were weighed and added to a 1 L high-pressure reactor. The reactor was first purged with nitrogen three times, then with hydrogen three times. When the temperature reached 75 °C, hydrogen was added to the reactor to a pressure of 3.5 MPa. As the reaction proceeded, the pressure inside the reactor continuously decreased. When the pressure dropped to 0.2 MPa, hydrogen was added back to the reactor to bring it back to 3.5 MPa. This process was repeated until the pressure inside the reactor reached 3.5 MPa and stopped decreasing, indicating the reaction was complete. The reactor temperature was then lowered to room temperature, and the reaction liquid was safely released. The palladium on carbon catalyst was filtered out. After removing methanol, unreacted raw materials, and byproducts from the filtrate, 37.3 g of antioxidant ③ was obtained. The NMR spectrum of antioxidant ③ is shown in Figure 3.
[0073] The preparation method of antioxidant ④ is as follows: it is prepared according to the method of antioxidant ③, except that in step three, 22.54 g (0.225 mol) of 4-methyl-2-pentanone is replaced with 0.225 mol of cyclohexanone. The NMR spectrum of antioxidant ④ is shown in Figure 4.
[0074] The preparation method of antioxidant ⑤ is as follows: it is prepared according to the method of antioxidant ③, except that 2,4-diaminodiphenylamine is replaced with an equal mass of 4,4-diaminodiphenylamine. The NMR spectrum of antioxidant ⑤ is shown in Figure 5.
[0075] The preparation method of antioxidant ⑥ is as follows: it is prepared according to the method of antioxidant ④, except that 2,4-diaminodiphenylamine is replaced with an equal mass of 4,4-diaminodiphenylamine. The NMR spectrum of antioxidant ⑥ is shown in Figure 6.
[0076] The preparation method of antioxidant ⑦ is as follows: 18.33 g (0.15 mol) of 2,4-diaminotoluene, 150.1 g (1.5 mol) of 4-methyl-2-pentanone, 1.3 g of palladium on carbon, and 280 mL of methanol are weighed and added to a 1 L high-pressure reactor. The air inside the reactor is first replaced with nitrogen three times, and then replaced with hydrogen in the order of hydrogen-nitrogen three times. When the temperature is raised to 75 °C, hydrogen is added to the high-pressure reactor to 3.5 MPa. As the reaction proceeds, the pressure inside the reactor continuously decreases. When the pressure drops to 0.2 MPa, hydrogen is added to the high-pressure reactor to 3.5 MPa again. This process is repeated until the pressure inside the reactor reaches 3.5 MPa and no longer decreases, indicating that the reaction is complete. The temperature of the reactor is then lowered to room temperature, and the reaction liquid is safely released. The palladium on carbon catalyst is filtered out, and the filtrate is treated to remove methanol, unreacted raw materials, and byproducts to obtain antioxidant ⑦. The NMR spectrum of antioxidant ⑦ is shown in Figure 7.
[0077] The preparation method of antioxidant ⑧ is as follows: it is prepared according to the method of antioxidant ⑦, except that 150.1 g (1.5 mol) of 4-methyl-2-pentanone is replaced with 147.2 g (1.5 mol) of cyclohexanone. The NMR spectrum of antioxidant ⑧ is shown in Figure 8.
[0078] Comparative Example 1
[0079] A rubber composition comprising the following components in parts by weight: 45 parts natural rubber, 55 parts butadiene rubber, 45 parts carbon black N330, 4.5 parts ZnO-80, 2 parts stearic acid, 1 part antioxidant RD, 1.8 parts protective wax, 1.5 parts sulfur, and 1 part accelerator NS.
[0080] The preparation method includes the following steps:
[0081] (1) Natural rubber, butadiene rubber, carbon black N330, antioxidant RD, protective wax, ZnO-80 and stearic acid are put into a mixer and mixed at 100-145℃ for 6 minutes to obtain a masterbatch. After the temperature is below 100℃, sulfur and accelerator NS are added and mixed for 5 minutes to obtain a compound.
[0082] (2) After the above-mentioned compounded rubber material is left to stand for more than 6 hours, the vulcanization tester, Mooney viscosity, Mooney scorch time and other tests are performed.
[0083] (3) The above-mentioned compounded rubber is vulcanized in a vulcanizing machine at 150-180°C. The vulcanization conditions are vulcanizing instrument test temperature × t90, and then a rubber composition is obtained.
[0084] In the above preparation process, the vulcanization characteristics of the compound were tested using the testing standard GB / T 16584-1996, the Mooney viscosity of the compound was tested using the testing standard GB / T 1232.1-2016, and the scorch time was determined using the standard GB / T 1233-2008.
[0085] The vulcanized rubber composition was tested according to GB / T 528-2009 for tensile stress-strain properties, tensile strength, and elongation at break; GB / T 3512-2014 for thermo-oxidative aging tests; GB / T 7762-2014 for ozone cracking static tensile tests; GB / T 13642-2015 for ozone cracking dynamic tensile tests; and GB / T 11206-2009 for crack grade evaluation.
[0086] Comparative Example 2
[0087] A rubber composition comprising the following components in parts by weight: 45 parts natural rubber, 55 parts butadiene rubber, 45 parts carbon black N330, 4.5 parts ZnO-80, 2 parts stearic acid, 1 part antioxidant RD, 2 parts antioxidant 4020 (6PPD), 1.8 parts protective wax, 1.5 parts sulfur, and 1 part accelerator NS.
[0088] The rubber composition was prepared using the same preparation method as Comparative Example 1, except that 2 more parts of antioxidant 4020 (6PPD) were added compared to Comparative Example 1.
[0089] Comparative Example 3
[0090] A rubber composition comprising the following components in parts by weight: 45 parts natural rubber, 55 parts butadiene rubber, 45 parts carbon black N330, 4.5 parts ZnO-80, 2 parts stearic acid, 2 parts antioxidant 4020, 1.8 parts protective wax, 1.5 parts sulfur, and 1 part accelerator NS.
[0091] The rubber composition was prepared using the same preparation method as Comparative Example 2, except that the antioxidant RD in Comparative Example 2 was removed and only 2 parts of 4020 were used.
[0092] Examples 1-8
[0093] A rubber composition comprising the following components in parts by weight: 45 parts natural rubber, 55 parts butadiene rubber, 45 parts carbon black N330, 4.5 parts ZnO-80, 2 parts stearic acid, 1 part antioxidant RD, 2 parts antioxidants ① to ⑧, 1.8 parts protective wax, 1.5 parts sulfur, and 1 part accelerator NS.
[0094] Rubber compositions were prepared using the same preparation method as Comparative Example 2, except that the antioxidant 4020 (6PPD) in Comparative Example 2 was replaced with an equal mass of novel antioxidants ① to ⑧, namely, antioxidant 4020 in Example 1 was replaced with novel antioxidant ①, antioxidant 4020 in Example 2 was replaced with novel antioxidant ②, antioxidant 4020 in Example 3 was replaced with novel antioxidant ③, antioxidant 4020 in Example 4 was replaced with novel antioxidant ④, antioxidant 4020 in Example 5 was replaced with novel antioxidant ⑤, antioxidant 4020 in Example 6 was replaced with novel antioxidant ⑥, antioxidant 4020 in Example 7 was replaced with novel antioxidant ⑦, and antioxidant 4020 in Example 8 was replaced with novel antioxidant ⑧. The raw material ratios and performance tests are shown in Tables 1 to 4.
[0095] Example 9
[0096] A rubber composition comprising the following components in parts by weight: 45 parts natural rubber, 55 parts butadiene rubber, 45 parts carbon black N330, 4.5 parts ZnO-80, 2 parts stearic acid, 1 part antioxidant RD, 0.6 parts antioxidant ④, 1 part antioxidant 4020, 1.8 parts protective wax, 1.5 parts sulfur, and 1 part accelerator NS.
[0097] Rubber compositions were prepared using the same preparation method as Comparative Example 2, except that 2 parts of antioxidant 4020 (6PPD) in Comparative Example 2 were replaced with 1 part of 4020 and 0.6 parts of antioxidant ④. The application effect of the new antioxidant partially replacing 4020 was investigated. The raw material ratio and performance test results are shown in Tables 1 to 4.
[0098] Example 10
[0099] A rubber composition comprising the following components in parts by weight: 45 parts natural rubber, 55 parts butadiene rubber, 45 parts carbon black N330, 4.5 parts ZnO-80, 2 parts stearic acid, 2 parts antioxidant ④, 1.8 parts protective wax, 1.5 parts sulfur, and 1 part accelerator NS.
[0100] The rubber composition was prepared using the same preparation method as Comparative Example 2, except that antioxidant 4020 in Comparative Example 3 was replaced with 2 parts of antioxidant ④.
[0101] The raw material ratios and performance test results of the above embodiments and comparative examples are shown in Tables 1 to 4.
[0102] Table 1 Raw Material Proportions
[0103] Table 2 Raw material ratio
[0104] Table 3 Performance Test Data
[0105] Table 4 Performance Test Data
[0106] As can be seen from the comparison of Examples 1-10 with Comparative Examples 2-3 in Tables 3 and 4, the replacement of antioxidants has little effect on Mooney viscosity, but a significant effect on scorch time. The vulcanization speed of Examples 1-10 is slightly faster than that of Comparative Examples 2 and 3, with Examples 5 and 6 having the fastest vulcanization speed. From the perspective of initial mechanics, the initial tensile strength of the rubber compounds in Examples 1-10 is basically equivalent to that of Comparative Examples 2 and 3, but the tensile strength of several new antioxidants remains excellent. In Example 9, replacing 1 part of 4020 with 0.6 parts of new antioxidant ④ achieves heat and oxygen aging resistance comparable to that of Comparative Example 2. The tensile product of several new antioxidants remains excellent, and their aging resistance is basically equivalent to that of Comparative Example 2.
[0107] As can be seen from Tables 3 and 4 regarding the dynamic ozone aging cracking levels, the rubber compounds in Examples 1-10 exhibited good early ozone protection, comparable to Comparative Examples 2 and 3. With prolonged ozone aging time, Example 2 showed significantly better ozone aging resistance and slower crack development. After 96 hours of dynamic ozone aging, the cracking levels of the rubber compounds in these examples were comparable to those in Comparative Examples 2 and 3, with no significant differences observed in dynamic ozone aging. Example 9 demonstrates that using 0.6 parts of the novel antioxidant plus 1 part of 4020 to replace 2 parts of 4020 achieves comparable ozone aging resistance. In summary, the novel antioxidants of this invention possess excellent mechanical aging resistance and superior ozone aging cracking resistance. Furthermore, the novel antioxidants also offer the effect of reducing the amount of 4020 used, making them a viable alternative to 6PPD.
[0108] The above description is only a preferred embodiment of the present invention. All novel antioxidant structures provided by the present invention should be included. It should be noted that for those skilled in the art, several improvements and fine-tunings can be made without departing from the principle of the present invention, and these improvements and fine-tunings should also be considered within the scope of protection of the present invention.
Claims
1. A rubber composition containing an antioxidant, comprising rubber and an antioxidant, said antioxidant comprising at least one of compounds with structures shown in formulas (1)-(4): In formulas (1), (2), (3), and (4), R1 and R2 are each independently selected from hydrogen, cyclohexyl, cyclooctyl, 2-cyclohexylethyl, 2-phenylethyl, benzyl, or long-chain or branched alkyl groups having 1-15 carbon atoms.
2. The rubber composition according to claim 1, comprising at least one of the following conditions: Condition 1: The long-chain or branched alkyl group having 1-15 carbon atoms includes methyl, ethyl, isopropyl, 1,3-dimethylbutyl or 1,4-dimethylpentyl; Condition 2: Based on 100 parts by weight of rubber, the antioxidant with the structure shown in formula (1)-(4) is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight; Condition 3: The rubber includes at least one of natural rubber, styrene-butadiene rubber, and cis-butadiene rubber.
3. The rubber composition according to claim 1 or 2, wherein the antioxidant further comprises antioxidants with other structures, wherein the antioxidants with other structures are 1 to 10 parts by weight, based on 100 parts by weight of rubber.
4. The rubber composition according to any one of claims 1-3 further comprises at least one of a vulcanizing agent, a filler, and other additives.
5. The rubber composition according to claim 4, comprising at least one of the following conditions: Condition 1: Based on 100 parts by weight of rubber, the vulcanizing agent is 0.01 to 20 parts by weight, the filler is 10 to 150 parts by weight, and other additives are 0.5 to 200 parts by weight. Condition 2: The filler includes at least one of carbon black, mineral filler, silica, calcium carbonate, and clay. Condition 3: The vulcanizing agent includes at least one of sulfur, insoluble sulfur, and peroxide; Condition 4: The other additives include at least one of activators, processing aids, accelerators, and functional additives.
6. The rubber composition according to claim 5, wherein the activator is 0-20 parts by weight, the processing aid is 0-30 parts by weight, the accelerator is 0-20 parts by weight, and the functional aid is 0-50 parts by weight, based on 100 parts by weight of rubber.
7. A method for preparing a rubber composition containing an antioxidant according to any one of claims 1-6, comprising the following steps: (1) Mix the raw materials together and knead them to obtain the kneaded material; (2) The mixed materials are vulcanized to obtain a rubber composition.
8. The preparation method according to claim 7, comprising at least one of the following conditions: a. In step (1), the mixing temperature is 60-160℃ and the mixing time is 1-20 min; b. In step (2), the vulcanization temperature is 120-200℃ and the vulcanization time is 5-90min.
9. The use of the rubber composition containing an antioxidant as described in claim 1 or 2 in a rubber article, preferably, the rubber article being a tire.
10. A method for improving the aging resistance of rubber products, comprising adding an antioxidant during the preparation of the rubber products, said antioxidant comprising at least one of compounds with structures shown in formulas (1)-(4): In formulas (1), (2), (3), and (4), R1 and R2 are each independently selected from hydrogen, cyclohexyl, cyclooctyl, 2-cyclohexylethyl, 2-phenylethyl, benzyl, and long-chain or branched alkyl groups with 1-15 carbon atoms.