N-o-tolyl-n'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine and a process for its preparation and use

Abstract

The application discloses N-o-tolyl-N'-(1-methyl-2-benzyl) ethyl p-phenylenediamine and a preparation method and application thereof. The product is prepared from p-chloronitrobenzene and 2-methylaniline through a nucleophilic substitution reaction to obtain N-o-tolyl p-nitroaniline, and then the N-o-tolyl p-nitroaniline and benzylacetone are subjected to a catalytic reduction reaction under high temperature and high pressure conditions to obtain the final product. The product has excellent ozone protection effect and anti-crack performance, and can obviously improve the red discoloration phenomenon of the tire side caused by the migration of the antioxidant.

Description

Technical Field

[0001] This invention relates to N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, its preparation method and application, belonging to the field of organic synthesis technology. Background Technology

[0002] Currently, the main ozone-resistant antioxidants used in rubber tire products are p-phenylenediamine antioxidants. P-phenylenediamine antioxidants are mainly divided into three types: one is diaryl antioxidants, such as antioxidant 3100; another is arylalkyl antioxidants, such as antioxidant 4020 and antioxidant 4010NA; and the third is dialkyl p-phenylenediamine, such as antioxidant 4030.

[0003] Compared to antioxidants such as 4030 and 4020, p-phenylenediamine, due to the introduction of benzyl and o-phenylenediamine, increases the solubility of the antioxidant in rubber products and slows its migration rate, providing a certain degree of long-term protection. However, due to the benzene ring conjugation effect, the electron cloud density of the amino group in the antioxidant decreases, reducing its ability to capture ozone. Therefore, the ozone protection effect of antioxidant 3100 is far inferior to that of antioxidants 4020 and 4030. In comparison, although antioxidants 4020 and 4030 have better ozone-capturing capabilities than antioxidant 3100, their low solubility and small molecular weight in rubber lead to rapid migration in rubber products, failing to provide long-term protection for rubber tires. Furthermore, excessive migration of antioxidants causes reddening and discoloration on the tire surface, affecting the appearance of the rubber tire products.

[0004] American company Kotria launched the triazine macromolecular antioxidant TAPDT and Ciba Specialty Chemicals launched the macromolecular antioxidant IRGAZONE 997. Although they can slow down the migration rate of antioxidants, effectively improve the appearance of rubber tire products, and enhance long-term protection, the production process of the two antioxidants is complicated and the production cost is high, so they cannot be promoted and applied in the tire market in the short term. Summary of the Invention

[0005] The purpose of this invention is to provide a p-phenylenediamine antioxidant—N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl p-phenylenediamine. This product contains benzyl and o-tolyl groups, which can effectively improve the solubility of p-phenylenediamine antioxidants in rubber products with carbon black filling systems, improve the migration, reddening, and staining phenomena of p-phenylenediamine antioxidants in rubber products, and provide excellent ozone protection for rubber products.

[0006] The chemical structural formula of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine provided by this invention is as follows:

[0007]

[0008] The present invention also provides a method for preparing the above-mentioned N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, which includes the following steps:

[0009] (1) Mix p-chloronitrobenzene, 2-methylaniline and organic solvent, heat to reflux to react, cool down after reaction, add acid-binding agent to remove the acid formed in the reaction, and then perform post-treatment on the reaction solution to obtain N-o-tolyl-p-nitroaniline;

[0010] (2) N-o-tolyl-p-nitroaniline, benzylacetone, and catalyst were mixed and hydrogen gas was introduced to carry out a hydrogenation reduction reaction. The reaction solution was then post-treated to obtain N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine; the reaction formula is as follows:

[0011]

[0012] Furthermore, in step (1), the molar ratio of p-chloronitrobenzene to 2-methylaniline is 1:1 to 1.5, for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5.

[0013] Furthermore, in step (1), the acid-binding agent is one or more of sodium carbonate, potassium carbonate, and sodium hydroxide. The molar ratio of the acid-binding agent to p-chloronitrobenzene is 1 to 1.1:1, for example, 1:1, 1.05:1, or 1.1:1.

[0014] Furthermore, in step (1), the organic solvent is any one or more of isopropanol, 1,4-dioxane, and toluene.

[0015] Furthermore, in step (1), chloronitrobenzene and 2-methylaniline undergo a nucleophilic substitution reaction under reflux. Depending on the organic solvent, the reflux reaction temperature is between 85°C and 120°C, and the reaction time is generally 6 to 8 hours. Preferably, the reaction temperature is between 85°C and 110°C, and the reaction time is 7 to 8 hours.

[0016] Further, in step (1), after the reflux reaction of p-chloronitrobenzene and 2-methylaniline is complete, the temperature is lowered to 55-65°C and an acid-binding agent is added to remove the acid formed in the reaction. Preferably, the acid-binding agent is added dropwise over a period of 0.5-1 hour, and the reaction is maintained at this temperature for 0.5-1 hour after the addition is completed. Preferably, the acid-binding agent is added dropwise over a period of 0.5 hours, and the reaction is maintained at this temperature for 1 hour after the addition is completed.

[0017] Furthermore, in step (1), the reaction solution is generally post-treated by cooling it to allow crystallization, and the precipitated crystals are then washed and dried to obtain the intermediate. The crystallization temperature is 5–15°C, preferably 10°C.

[0018] Furthermore, in step (2), the molar ratio of N-o-tolyl-p-nitroaniline to benzylacetone is 1:1 to 1.3, for example, 1:1, 1:1.1, 1:1.2, 1:1.3.

[0019] Furthermore, in step (2), the catalyst is at least one of a nickel-based metal catalyst, a palladium-based metal catalyst, and a platinum-based metal catalyst. For example, the nickel-based metal catalyst can be nickel-aluminum alloy powder, the palladium-based metal catalyst can be Pd / C, and the platinum-based metal catalyst can be Pt / C. Preferably, the amount of catalyst used is 3-5% of the total mass of N-o-tolyl-p-nitroaniline and benzylacetone.

[0020] Furthermore, in step (2), the reaction is carried out in a low-carbon alcohol solvent, such as methanol or ethanol.

[0021] Furthermore, in step (2), after the reactor is heated to 70-100°C, hydrogen gas is introduced, and the hydrogen pressure is maintained at 2-3 MPa. The reaction ends when the pressure no longer changes. Preferably, after the reactor is heated to 70-85°C, hydrogen gas is introduced, and the hydrogen pressure is maintained at 2-2.5 MPa.

[0022] Furthermore, in step (2), the post-treatment of the reaction solution includes cooling to remove excess hydrogen, recovering the catalyst, removing impurities by vacuum distillation, and drying to obtain the final product.

[0023] The present invention, N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, can be used as a rubber antioxidant. It belongs to the novel o-tolyl antioxidant category and can give rubber products excellent ozone protection and reduce crack formation. It is more resistant to migration in rubber products and can effectively prevent the reddening and staining of rubber products caused by large-scale migration of antioxidants, thus giving rubber products excellent anti-discoloration properties.

[0024] The present invention has the following beneficial effects:

[0025] 1. The preparation process of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine of the present invention is simple, with high product yield and stable product quality.

[0026] 2. When the N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl p-phenylenediamine of this invention is applied to rubber tire products, its ozone protection effect is comparable to that of antioxidant 4020. At the same time, due to the presence of benzyl and o-tolyl groups, it has better migration resistance than traditional antioxidants 4020 and 3100, thereby effectively improving the redness, dirtiness and discoloration of the tire sidewall caused by the large-scale migration of traditional p-phenylenediamine antioxidants.

[0027] 3. The N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine of the present invention can also significantly improve the mechanical properties of rubber products, and can significantly improve the tear resistance of rubber products. Attached Figure Description

[0028] Figure 1 The image shows the results of a dynamic ozone aging test, with the left side showing a photograph of the actual object and the right side showing the observation results under a high magnification microscope (×100). Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0030] Unless otherwise specified, all raw materials used in the following examples are commercially available products. Unless otherwise specified, all material concentrations are mass percentages.

[0031] Example 1

[0032] The preparation method of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine includes the following three steps:

[0033] Step 1:

[0034] 200 ml of toluene, 47.27 g of p-nitrochlorobenzene, and 35.36 g of 2-methylaniline were added to a 500 ml three-necked flask equipped with a reflux condenser and a mechanical stirrer. The temperature was gradually increased during stirring, and after the temperature reached 110 °C, the solvent stabilized and refluxed. The reaction was maintained at this temperature for 6 hours, after which heating was stopped, and the material temperature was lowered to 60 °C. After the material temperature stabilized, 24 g of 50% sodium hydroxide aqueous solution was added dropwise over 0.5 hours. After the addition was completed, the reaction was maintained at this temperature for another 1 hour. After the reaction was completed, the material temperature was lowered to 10 °C and maintained at this temperature for 0.5 hours. The stirring and temperature control devices were then stopped, and the mixture was allowed to stand for 15 minutes before being filtered to obtain crude N-o-tolyl-p-nitroaniline. The crude product was soaked in 100 ml of deionized water for 15 minutes, filtered, washed twice, and then dried in an oven at 80 °C to obtain 67.21 g of N-o-tolyl-p-nitroaniline, with a yield of 98.15% and a liquid phase purity of 99.12%.

[0035] Step 2:

[0036] 67.21g of N-o-tolyl-p-nitroaniline and 48.01g of benzylacetone were added to a 500ml high-pressure hydrogenation reactor. Then, 200ml of methanol was added to the reactor. Finally, 3.46g of activated Pd / C catalyst (dry basis, palladium content in the catalyst was 5%) was flushed into the reactor using 50ml of methanol. The reactor was then assembled. The pressure was evacuated to -0.09MPa using a vacuum pump, and nitrogen gas was introduced to 0.5MPa. After holding for 10 seconds, the pressure was purged. This process was repeated three times. The temperature was then raised to 70℃. After the temperature of the material in the reactor stabilized, hydrogen gas was introduced to 2.5MPa to start the hydrogenation reduction reaction. After the hydrogen pressure in the reactor dropped to 2MPa, hydrogen gas was introduced again to 2.5MPa. After 8 hours of reaction, the hydrogen pressure in the reactor stabilized and did not decrease after 0.5 hours, indicating that the hydrogenation reduction reaction was complete. The temperature of the material was lowered to 25℃, the remaining hydrogen gas in the reactor was purged, and the material was discharged from the high-pressure reactor.

[0037] Step 3:

[0038] The Pd / C catalyst was recovered by vacuum filtration using a G6 sand core funnel. After washing and sealing, methanol and a small amount of low-boiling substances were removed by vacuum distillation to obtain 93.31 g of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, with a yield of 95.88% and a purity of 96.73%.

[0039] Example 2

[0040] The preparation method of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine includes the following three steps:

[0041] Step 1:

[0042] 200 ml of isopropanol, 47.27 g of p-nitrochlorobenzene, and 38.57 g of 2-methylaniline were added to a 500 ml three-necked flask equipped with a reflux condenser and a mechanical stirrer. The temperature was gradually increased during stirring until the solvent reached a stable reflux at 90 °C. The reaction was maintained at this temperature for 8 hours, after which heating was stopped. The material temperature was then lowered to 60 °C and allowed to stabilize. Finally, 84.62 g of a 50% potassium carbonate aqueous solution was added dropwise over a period of 0. After 5 hours of dropwise addition, the reaction was continued at the same temperature for 1 hour. After the reaction was completed, the material temperature was lowered to 10°C and kept at that temperature for 0.5 hours. Then, the stirring and temperature control device were stopped. After standing for 15 minutes, the crude N-o-tolyl-p-nitroaniline was obtained by vacuum filtration. The crude product was soaked in 100 ml of deionized water for 15 minutes and then filtered. After washing twice, the product was dried in an oven at 80°C to obtain 67.56 g of N-o-tolyl-p-nitroaniline, with a yield of 98.65% and a liquid phase purity of 99.23%.

[0043] Step 2:

[0044] 67.56g of N-o-tolyl-p-nitroaniline and 52.64g of benzylacetone were added to a 500ml high-pressure hydrogenation reactor. Then, 200ml of methanol was added to the reactor. Finally, 4.81g of activated Pd / C catalyst (dry basis, palladium content in the catalyst was 5%) was flushed into the reactor using 50ml of methanol. The reactor was then assembled. The pressure was evacuated to -0.09MPa using a vacuum pump, and nitrogen gas was introduced to 0.5MPa. After holding for 10 seconds, the pressure was purged. This process was repeated three times. The temperature was then raised to 80℃. After the temperature of the material in the reactor stabilized, hydrogen gas was introduced to 2.5MPa to start the hydrogenation reduction reaction. After the hydrogen pressure in the reactor dropped to 2MPa, hydrogen gas was introduced again to 2.5MPa. After 8 hours of reaction, the hydrogen pressure in the reactor stabilized and no longer dropped after 0.5 hours, indicating that the hydrogenation reduction reaction was complete. The temperature of the material was lowered to 25℃, the remaining hydrogen gas in the reactor was purged, and the material was discharged from the high-pressure reactor.

[0045] Step 3:

[0046] The Pd / C catalyst was recovered by vacuum filtration using a G6 sand core funnel. After washing and sealing, methanol and a small amount of low-boiling substances were removed by vacuum distillation to obtain 94.81 g of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, with a yield of 96.93% and a purity of 95.97%.

[0047] Example 3

[0048] The preparation method of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine includes the following three steps:

[0049] Step 1:

[0050] Add 200 ml of dioxane, 47.27 g of p-nitrochlorobenzene, and 36.96 g of [unspecified ingredient] to a 500 ml three-necked flask equipped with a reflux condenser and a mechanical stirrer. 2-Methylaniline was gradually heated during stirring. Once the temperature reached 105℃, the solvent stabilized and refluxed. The reaction was maintained at this temperature for 6 hours, after which heating was stopped. The material temperature was then lowered to 60℃. After the material temperature stabilized, 24g of a 50% sodium hydroxide aqueous solution was added dropwise over 0.5 hours. After the addition was complete, the reaction was maintained at this temperature for another 1 hour. After the reaction was complete, the material temperature was lowered to 10℃ and maintained at this temperature for 0.5 hours. Stirring and temperature control were then stopped. After standing for 15 minutes, the crude N-o-tolyl-p-nitroaniline was obtained by vacuum filtration. The crude product was then soaked in 100ml of deionized water for 15 minutes, filtered, washed twice, and dried in an oven at 80℃ to obtain 66.96g of N-o-tolyl-p-nitroaniline, with a yield of 97.78% and a liquid phase purity of 99.43%.

[0051] Step 2:

[0052] 66.96g of N-o-tolyl-p-nitroaniline and 52.64g of benzylacetone were added to a 500ml high-pressure hydrogenation reactor. Then, 200ml of methanol was added to the reactor. Finally, 4.81g of activated Pt / C catalyst (dry basis, palladium content in the catalyst is 5%) was flushed into the reactor using 50ml of methanol. The reactor was then assembled. The pressure was evacuated to -0.09MPa using a vacuum pump, and nitrogen gas was introduced to 0.5MPa. After holding for 10 seconds, the pressure was purged. This process was repeated three times. The temperature was then raised to 90℃. After the temperature of the material in the reactor stabilized, hydrogen gas was introduced to 2.5MPa to start the hydrogenation reduction reaction. After the hydrogen pressure in the reactor dropped to 2MPa, hydrogen gas was introduced again to 2.5MPa. After 8 hours of reaction, the hydrogen pressure in the reactor stabilized and did not decrease after 0.5 hours, indicating that the hydrogenation reduction reaction was complete. The temperature of the material was lowered to 25℃, the remaining hydrogen gas in the reactor was purged, and the material was discharged from the high-pressure reactor.

[0053] Step 3:

[0054] The Pd / C catalyst was recovered by vacuum filtration using a G6 sand core funnel. After washing and sealing, methanol and a small amount of low-boiling substances were removed by vacuum distillation to obtain 93.02 g of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, with a yield of 95.96% and a purity of 96.37%.

[0055] Comparative Example 1

[0056] By replacing the 2-methylaniline raw material in Example 1 with p-toluidine, N-p-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine was obtained.

[0057] Comparative Example 2

[0058] The preparation method of N-p-nitrophenyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine includes the following three steps:

[0059] Step 1:

[0060] 108.14g of p-phenylenediamine was added to a 500ml high-pressure hydrogenation reactor. Then, 200ml of methanol was added to the reactor. Finally, 3.24g of activated Pd / C catalyst (dry basis, palladium content 5%) was flushed into the reactor using 50ml of methanol. The reactor was then assembled, and a vacuum pump was used to evacuate to -0.09MPa. Nitrogen gas was then introduced to 0.5MPa, held for 10 seconds, and then vented. This process was repeated three times. The temperature was then raised to 70℃, and the reaction proceeded as expected. After the temperature stabilizes, hydrogen gas is introduced to 2.5 MPa. 44.46 g of benzylacetone is then added dropwise to the reactor at a uniform rate using a horizontal flow pump over a period of 3 hours. When the hydrogen pressure in the reactor drops to 2 MPa, hydrogen gas is introduced again to 2.5 MPa. After the addition is complete, the reactor is kept at the same temperature and pressure for 2 hours. The hydrogen pressure in the reactor stabilizes and does not decrease after 0.5 hours, indicating that the hydrogenation reduction reaction is complete. The material temperature is then lowered to 25°C, the remaining hydrogen gas in the reactor is vented, and the material is discharged from the high-pressure reactor.

[0061] Step 2:

[0062] After removing the methanol solvent by distillation, and then removing the excess p-phenylenediamine by fractional distillation, 71.44 g of N-(1-methyl-2-benzyl)ethyl p-phenylenediamine was obtained, with a yield of 98.60% and a liquid phase purity of 99.35%.

[0063] Step 3:

[0064] In a 500 mL three-necked flask equipped with a reflux condenser and mechanical stirrer, 200 mL of toluene, 106.76 g of p-nitrochlorobenzene, and 70 g of N-(1-methyl-2-benzyl)ethyl-p-phenylenediamine were added. The temperature was gradually increased during stirring, and once it reached 110 °C, the solvent stabilized and refluxed. The reaction was maintained at this temperature for 6 hours, after which heating was stopped. The material temperature was then lowered to 60 °C, and once it stabilized, 34.63 g of a 50% sodium hydroxide aqueous solution was added dropwise over a period of 0 minutes. After the addition of 0.5h, the reaction was continued at the temperature for 1h. After the reaction was completed, the material temperature was lowered to 10℃, and the temperature was maintained for 0.5h. Then, the stirring and temperature control device were stopped. After standing for 15min, the crude product was obtained by vacuum filtration. The crude product was soaked in 100ml of deionized water for 15min and then vacuum filtered. After washing twice, it was dried in an oven at 80℃ to obtain 157.32g of N-p-nitrophenyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, with a yield of 97.44% and a liquid phase purity of 99.43%.

[0065] Application Trial

[0066] 1. Test Methods

[0067] 1.1 Experimental formulation

[0068] Rubber formulation (parts by weight): NR: 70 parts, BR: 30 parts, zinc oxide: 4 parts, stearic acid: 3 parts, protective wax: 1.5 parts, antioxidant: 3 parts, carbon black: 50 parts, sulfur and accelerator: 2.0 parts each. The antioxidants are N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine prepared in Example 1 of this invention, N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine prepared in Comparative Example 1, N-p-nitrophenyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine prepared in Comparative Example 2, antioxidant 4020, and antioxidant 3100.

[0069] 1.2 Test Equipment and Methods

[0070] The instruments and equipment used in the experiment included: a 50-ton flat vulcanizing machine, an XLL-2500N rubber tensile testing machine, a C2000E rubber rotorless vulcanizing apparatus, a GK270 internal mixer, an XM-140 / 20 internal mixer, and an XK-160 open mill.

[0071] 1.3 Sample Preparation

[0072] The rubber compound is mixed using a two-stage mixing process.

[0073] The first mixing process is carried out in a 1.5L internal mixer: mixing parameters: initial temperature 80℃, rotation speed 50r·min-1; feeding sequence: NR and BR are added to the internal mixer for 20s, pressed and mixed for 60s, lifted for 10s, protective wax, carbon black, zinc oxide, stearic acid are added, pressed and mixed for 45s, lifted for 10s, mixed for 40s, cleaned for 10s, pressed and mixed for 30s, cleaned for 10s, pressed and mixed for 30s, lifted for 10s, then pressed for 20s to discharge the glue (discharge temperature: 135℃±5℃).

[0074] The two-stage mixing process is carried out on an open mill. After adjusting the open mill to a suitable roll gap, the first-stage mixing masterbatch wraps around the roll for 1 minute, and then cuts twice on each of the left and right 3 / 4 sections. Then, sulfur, accelerator and antioxidant are added. After the mixing masterbatch has finished consuming the material, it is cut twice on each of the left and right 3 / 4 sections. Then, the mixed rubber is cut off. After adjusting the open mill roll gap to the minimum, the mixed rubber is cut off after alternating thin-pass triangular wrapping and rolling 3 times each. It is then left to stand for testing.

[0075] According to the different antioxidants used, each rubber sample is numbered as follows: 1#: Product of this invention; 2#: N-p-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine; 3#: N-p-nitrophenyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine; 4#: Antioxidant 4020; 5#: Antioxidant 3100.

[0076] 1.4 Performance Testing

[0077] All performance tests were conducted in accordance with national standards.

[0078] 2. Test Results

[0079] 2.1 Comparison of test performance

[0080] The physical properties and aging properties of the rubber compound are shown in Tables 1 and 2 below, and the dynamic flexural properties are shown in Table 3 below.

[0081] Table 1. Physical properties before thermo-oxidative aging

[0082]

[0083] A comparison of the vulcanization characteristics and mechanical properties data with those of sample #1 shows that:

[0084] The addition of N-p-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine to sample #2 slightly reduced the degree of crosslinking and the maximum torque value (MH), and the mechanical properties of the vulcanized rubber before aging were slightly lower than those of sample #1.

[0085] When N-p-nitrophenyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine was added to sample #3, the MH of the compound decreased significantly, reflecting a significant decrease in the degree of cross-linking and vulcanization of the vulcanizate. The scorch time T10 was significantly shorter than that of samples #1 and #2, reflecting a deterioration in the processing performance of the compound. The mechanical properties of the vulcanizate before aging were significantly lower than those of sample #1.

[0086] After adding antioxidants 4020 and 3100 to samples #4 and #5 respectively, the vulcanization characteristics of the compound and the mechanical properties of the vulcanized rubber before aging were slightly lower than those of sample #1.

[0087] Table 2 Results of mechanical property changes after thermo-oxidative aging (100℃, 24h)

[0088]

[0089] A comparison with the mechanical properties data of sample #1 after aging shows that:

[0090] The mechanical properties and mechanical property retention rate of rubber samples #2 and #3 declined significantly after aging, indicating that the N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine of this invention can also significantly improve the heat and oxygen aging resistance of rubber products.

[0091] The mechanical strength retention rate of samples #4 and #5 was higher after aging, but the retention rate of elongation at break was slightly lower than that of sample #1.

[0092] Table 3 Comparison of Dynamic Flexibility Performance

[0093] code name initial / mm 50,000 times / mm 100,000 times / mm 1# 2.00 3.75 7.21 2# 2.00 6.21 14.72 3# 2.00 8.54 16.19 4# 2.00 4.14 10.12 5# 2.00 3.92 8.91

[0094] A comparison with the dynamic flexural performance data of sample #1 shows that:

[0095] The dynamic flexural properties of rubber samples #2, #3, #4, and #5 decreased significantly, with the most significant decrease observed in sample #3. This indicates that the N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine of this invention can also significantly improve the tear resistance of rubber products.

[0096] 2.2 Ozone Dynamic Test of Antioxidant

[0097] Dynamic ozone test conditions: ozone concentration of 50 pphm, test temperature of 40℃, static stretching of 20% for 48 hours followed by dynamic stretching of 10%, dynamic stretching frequency of 0.5 Hz.

[0098] The results of the ozone aging dynamic test are as follows: Figure 1 As shown in the figure, under the same experimental conditions, samples 2#, 3#, 4#, and 5# exhibit a reddish and dirty appearance compared to sample 1#, indicating that the N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine of this invention has superior migration resistance and discoloration resistance compared to the other four antioxidants.

[0099] 3. Conclusion

[0100] Compared with p-tolyl and p-nitrophenyl antioxidants, the o-tolyl antioxidant designed in this invention produces rubber compounds with significant advantages in heat and oxygen aging resistance, tear resistance, dynamic ozone aging resistance, and migration resistance.

Claims

1. An N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, characterized in that... It has the following structural formula: 。 2. A method for preparing N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine, characterized in that... Includes the following steps: (1) Mix p-chloronitrobenzene, 2-methylaniline and organic solvent, heat to reflux to react, cool down after reaction, add acid-binding agent to remove the acid formed in the reaction, and then perform post-treatment on the reaction solution to obtain N-o-tolyl-p-nitroaniline; (2) N-o-tolyl-p-nitroaniline, benzylacetone and catalyst are mixed and hydrogen is introduced to carry out hydrogenation reduction reaction. The reaction solution is then post-treated to obtain N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine. In step (2), the catalyst is at least one of nickel-based metal catalysts, palladium-based metal catalysts, and platinum-based metal catalysts; In step (2), after heating to 70~100℃, hydrogen gas is introduced and the hydrogen pressure is maintained at 2~3MPa. The reaction ends when the pressure no longer changes.

3. The preparation method according to claim 2, characterized in that: In step (1), the organic solvent is at least one of isopropanol, 1,4-dioxane, and toluene; the acid-binding agent is at least one of sodium carbonate, potassium carbonate, and sodium hydroxide.

4. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of p-chloronitrobenzene to 2-methylaniline is 1:1 to 1.5; the molar ratio of the acid binder to p-chloronitrobenzene is 1 to 1.1:

1.

5. The preparation method according to claim 2, characterized in that: In step (1), chloronitrobenzene and 2-methylaniline are first reacted under reflux for 6-8 hours, and then the temperature is lowered to 55-65℃, and an acid-binding agent is added.

6. The preparation method according to claim 2, 3 or 5, characterized in that: The acid-binding agent is added dropwise over a period of 0.5 to 1 hour.

7. The preparation method according to claim 2, characterized in that: In step (2), the molar ratio of N-o-tolyl-p-nitroaniline to benzylacetone is 1:1~1.

3.

8. The preparation method according to claim 2, characterized in that: In step (2), the amount of catalyst used is 3 to 5% of the total mass of N-o-tolyl-p-nitroaniline and benzylacetone.

9. The application of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine according to claim 1 in improving the anti-discoloration properties of rubber products. 。 10. The application of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine according to claim 1 in improving the anti-aging properties of rubber products.

11. The application of N-o-tolyl-N'-(1-methyl-2-benzyl)ethyl-p-phenylenediamine according to claim 1 in improving the crack resistance of rubber products.

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