A migration-resistant macromolecular rubber antioxidant, and a preparation method and application thereof

Abstract

This invention discloses a migration-resistant macromolecular rubber antioxidant, its preparation method, and its application. The migration-resistant macromolecular rubber antioxidant of this invention is obtained by reacting a benzimidazole compound, an epoxy-containing compound, and p-aminodiphenylamine in a specific solvent and catalyst, wherein the epoxy-containing compound is cashew phenol glycidyl ether. This invention improves the migration resistance and thermo-oxidative aging resistance of the antioxidant by grafting a macromolecular organic compound onto a p-aminodiphenylamine compound; moreover, the preparation conditions are mild and the process is simple.

Description

Technical Field

[0001] This invention relates to the field of rubber antioxidant technology, specifically to a migration-resistant p-aminodiphenylamine macromolecular rubber antioxidant, its preparation method, and its application. Background Technology

[0002] Rubber products are widely used in daily life, but they are prone to aging during storage and use. The aging process of rubber is irreversible. After aging, rubber will cause great damage to the internal structure, appearance, performance and value of the rubber material. Therefore, it is necessary to add rubber antioxidants to slow down the aging process and extend the service life of rubber products.

[0003] Traditional p-aminodiphenylamine antioxidants, such as 6PPD, have become the most widely produced class of general-purpose antioxidants due to their excellent overall protective properties. However, their small molecular weight leads to problems such as poor extraction resistance, easy migration, and color contamination. The migration of antioxidants not only reduces anti-aging efficiency and affects the performance of rubber materials, but also harms the environment. According to relevant literature, 6PPD antioxidants entering the environment with tire wear particles can be converted into the highly toxic substance 6PPD-quinone under the action of ozone, causing the death of aquatic organisms and terrestrial microorganisms and impacting the ecological environment.

[0004] Patent CN 115260585 discloses a GMA-modified p-aminodiphenylamine rubber antioxidant and its preparation method. The rubber antioxidant is prepared by reacting p-aminodiphenylamine with the epoxy groups of GMA. The specific preparation method includes heating and stirring p-aminodiphenylamine and GMA to react, obtaining a fluid product, and then granulating it to obtain the final antioxidant product. The rubber antioxidant prepared by this method has better stability and lower migration rate compared to traditional antioxidants. However, this method has a long reaction time and requires high temperature. Furthermore, at room temperature, the epoxy ring-opening product of GMA and p-aminodiphenylamine is a viscous liquid, requiring subsequent granulation for easy processing, which undoubtedly increases the complexity of the process and production costs. Currently, most p-aminodiphenylamine antioxidants are modified with GMA, but their preparation methods are mostly cumbersome, and their performance cannot meet practical needs. Summary of the Invention

[0005] To address the problems mentioned above in the background art, the purpose of this invention is to improve the migration resistance and enhance the anti-aging efficiency of p-aminodiphenylamine antioxidants. By grafting macromolecular organic compounds onto p-aminodiphenylamine compounds, a migration-resistant macromolecular rubber antioxidant based on p-aminodiphenylamine compounds is prepared, thereby improving the migration resistance and thermo-oxidative aging resistance of the antioxidant.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A migration-resistant macromolecular rubber antioxidant, the structure of which is shown in formula (Ⅰ):

[0008]

[0009] In formula (Ⅰ), R is H or CH3.

[0010] Furthermore, the rubber antioxidant of the present invention is obtained by reacting a benzimidazole compound, an epoxy group-containing compound, and p-aminodiphenylamine, wherein the epoxy group-containing compound is cashew phenol glycidyl ether (CGE) as shown in formula (II).

[0011]

[0012] Furthermore, the benzimidazole compound described in this invention is 2-mercaptobenzimidazole or 2-mercaptomethylbenzimidazole.

[0013] Furthermore, the molar ratio of p-aminodiphenylamine, benzimidazole compounds and epoxy group-containing compounds in this invention is 1:0.8-1.2:0.5-3, more preferably 1:0.9-1.1:1-2.

[0014] Furthermore, the present invention also provides a method for preparing the above-mentioned anti-migration macromolecular rubber antioxidant, comprising the following steps:

[0015] (1) After adding solvent to a three-necked flask with a protective atmosphere, add benzimidazole compounds, p-aminodiphenylamine (RT-Pys), cashew phenol glycidyl ether (CGE) and catalyst in proportion. Stir until fully dissolved, and then heat to 135℃~180℃ to react for 2h~15h.

[0016] (2) After cooling the mixture obtained after the reaction in step (1) to room temperature, wash and vacuum dry to obtain the migration-resistant macromolecular rubber antioxidant of the present invention.

[0017] Furthermore, the protective atmosphere described in step (1) of the present invention is nitrogen and / or an inert gas.

[0018] Furthermore, the solvent mentioned in step (1) of the present invention is either acetone or ethyl acetate.

[0019] Furthermore, the catalyst of the present invention is salicylic acid, and its addition amount is 0.5% to 2.5% of the total mass of the reactants.

[0020] Furthermore, the washing method in step (2) of the present invention is as follows: repeatedly washing with sodium bicarbonate aqueous solution to remove salicylic acid, and then washing with deionized water multiple times to remove sodium bicarbonate.

[0021] Furthermore, the present invention also provides a method for applying the above-mentioned anti-migration macromolecular rubber antioxidant, which is applied to natural rubber and / or synthetic rubber, wherein the amount of antioxidant added is 1% to 3% of the raw rubber mass.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The preparation conditions of the macromolecular rubber antioxidant of the present invention are mild and the process is simple.

[0024] (2) Compared with existing rubber antioxidants, the macromolecular rubber antioxidant prepared by the present invention has better migration resistance, as well as higher anti-aging efficiency and anti-thermal-oxidative aging performance.

[0025] (3) The macromolecular rubber antioxidant of the present invention contains a benzimidazole group. The imidazole ring contained in the benzimidazole group has antiparasitic and antibacterial effects. Tires using this antioxidant can effectively improve their antibacterial and antifungal capabilities, while also making their anti-aging and migration resistance properties more excellent. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0027] The raw materials used in the examples and comparative examples are all commercially available or can be prepared in-house using methods disclosed in the prior art.

[0028] The number of components used in each embodiment and comparative example is by mass.

[0029] Example 1

[0030] A method for preparing a migration-resistant macromolecular rubber antioxidant includes:

[0031] A reactor under nitrogen protection was placed in an oil bath, and acetone was added as solvent. p-Aminodiphenylamine, 2-mercaptobenzimidazole, and CGE were added sequentially to the reactor in a molar ratio of 1:1:1.5. Salicylic acid, at 1.3% of the total reactant mass, was added as a catalyst. A magnetic stir bar was placed in the reactor, and stirring was started. After the product was fully dissolved, the temperature was raised to 150°C and the reaction was carried out for 8 hours. After cooling to room temperature, the product was repeatedly washed with sodium bicarbonate aqueous solution to remove salicylic acid, and then repeatedly washed with deionized water to remove sodium bicarbonate. Finally, the product was dried in a vacuum drying oven to obtain macromolecular rubber antioxidant 1.

[0032] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of macromolecular rubber antioxidant 1, and mix them evenly on a two-roll mill to obtain the compound.

[0033] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0034] Example 2

[0035] A method for preparing a migration-resistant macromolecular rubber antioxidant includes:

[0036] A reactor under nitrogen protection was placed in an oil bath. Ethyl acetate was added as solvent, and p-aminodiphenylamine, 2-mercaptomethylbenzimidazole, and CGE were added sequentially to the reactor in a molar ratio of 1:1:1.5. Salicylic acid, at 1.3% of the total reactant mass, was added as a catalyst. A magnetic stir bar was placed in the reactor and the stirring was started. After the product was fully dissolved, the temperature was raised to 150°C and the reaction was carried out for 8 hours. After the product was cooled to room temperature, it was repeatedly washed with sodium bicarbonate aqueous solution to remove salicylic acid, and then repeatedly washed with deionized water to remove sodium bicarbonate. Ethyl acetate was evaporated to remove the product, and then the product was dried in a vacuum drying oven to obtain macromolecular rubber antioxidant 2.

[0037] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of antioxidant 2, and mix them evenly on a two-roll mill to obtain the compound.

[0038] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0039] Example 3

[0040] A method for preparing a migration-resistant macromolecular rubber antioxidant includes:

[0041] The reactor, protected by nitrogen, was placed in an oil bath. Acetone was added as solvent, and p-aminodiphenylamine, 2-mercaptomethylbenzimidazole, and CGE were added sequentially to the reactor in a molar ratio of 1:0.9:1. Salicylic acid, at 1% of the total reactant mass, was added as a catalyst. A magnetic stir bar was placed in the reactor, and stirring was started. After the product was fully dissolved, the temperature was raised to 135°C and the reaction was carried out for 4 hours. After the product was cooled to room temperature, it was repeatedly washed with sodium bicarbonate aqueous solution to remove salicylic acid. Sodium bicarbonate was removed by washing with deionized water multiple times. Finally, the product was dried in a vacuum drying oven to obtain macromolecular rubber antioxidant 3.

[0042] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of antioxidant 3, and mix them evenly on a two-roll mill to obtain the compound.

[0043] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0044] Example 4

[0045] A method for preparing a migration-resistant macromolecular rubber antioxidant includes:

[0046] The reactor, protected by nitrogen, was placed in an oil bath. Acetone was added as solvent, and p-aminodiphenylamine, 2-mercaptobenzimidazole, and CGE were added sequentially to the reactor in a molar ratio of 1:1.1:2. Salicylic acid, at 2% of the total reactant mass, was added as a catalyst. A magnetic stir bar was placed in the reactor, and stirring was started. After the product was fully dissolved, the temperature was raised to 165°C and the reaction was carried out for 12 hours. After the product was cooled to room temperature, it was repeatedly washed with sodium bicarbonate aqueous solution to remove salicylic acid, and then washed with deionized water several times to remove sodium bicarbonate. Finally, it was dried in a vacuum drying oven to obtain the product, macromolecular rubber antioxidant 4.

[0047] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of antioxidant 4, and mix them evenly on a two-roll mill to obtain the compound.

[0048] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0049] Comparative Example 1 (using antioxidant 6PPD)

[0050] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of antioxidant 6PPD, and mix them evenly on a two-roll mill to obtain the compound.

[0051] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0052] Comparative Example 2 (using antioxidant 4010NA)

[0053] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of antioxidant 4010NA, and mix them evenly on a two-roll mill to obtain the compound.

[0054] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0055] Comparative Example 3 (using the antioxidant 2-mercaptobenzimidazole)

[0056] Take 100 parts of styrene-butadiene rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 45 parts of carbon black N330, 2 parts of accelerator, 2 parts of sulfur and 2 parts of antioxidant 2-mercaptobenzimidazole, and mix them evenly on a two-roll mill to obtain the compound.

[0057] The obtained compound was vulcanized and cut into pieces to obtain dumbbell-shaped vulcanized rubber samples. Then, heat and oxygen aging resistance tests and migration resistance tests were conducted. The test results are shown in Table 1 and Table 2.

[0058] Performance Testing (I) Heat and Oxygen Aging Resistance Test.

[0059] The vulcanized rubber samples from the examples and comparative examples were suspended in an aging oven at 100°C for 5 days of thermo-oxidative aging, and the mechanical properties of the vulcanized rubber before and after aging were tested. The tensile strength retention rate after aging was used to characterize its anti-aging efficiency. Tensile strength retention rate = (parameter after aging / parameter before aging) × 100%. The test results are shown in Table 1.

[0060] Table 1. Heat and oxygen aging resistance tests of the examples and comparative examples.

[0061]

[0062] As shown in Table 1, compared with commercial antioxidants 6PPD, 4010NA and 2-mercaptobenzimidazole, the rubber products with antioxidants prepared in this invention have higher tensile strength after 5 days of thermo-oxidative aging at 100°C, indicating that the macromolecular rubber antioxidant prepared in this invention has better thermo-oxidative aging resistance.

[0063] (ii) Migration resistance test.

[0064] Equal amounts of vulcanized rubber from the examples and comparative examples were placed in the same volume of acetonitrile solvent. After immersion at room temperature for 3 days, the UV absorbance of the acetonitrile solvent was measured, and the concentration of antioxidant was calculated to characterize the migration resistance of the antioxidant. The test results are shown in Table 2.

[0065] Table 2 shows the migration resistance tests of the examples and comparative examples.

[0066]

[0067] As shown in Table 2, compared with commercial antioxidants 6PPD, 4010NA and 2-mercaptobenzimidazole, the concentration of antioxidant in the solution after extraction with acetonitrile solvent was lower in rubber products containing the antioxidant prepared in this invention. This indicates that less antioxidant migrated from the rubber products, which shows that the macromolecular rubber antioxidant prepared in this invention has better migration resistance and less antioxidant migrated into the acetonitrile solution.

[0068] In summary, the macromolecular rubber antioxidant prepared in this invention has better resistance to heat and oxygen aging and migration resistance compared with commercial antioxidants 6PPD, 4010NA and 2-mercaptobenzimidazole.

[0069] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A migration-resistant macromolecular rubber antioxidant, characterized in that, Its structure is shown in equation (Ⅰ): In formula (Ⅰ), R is H or CH3.

2. The anti-migration macromolecular rubber antioxidant according to claim 1, characterized in that, The rubber antioxidant is obtained by reacting benzimidazole compounds, epoxy group-containing compounds, and p-aminodiphenylamine, wherein the epoxy group-containing compound is cashew phenol glycidyl ether as shown in formula (II). The benzimidazole compound is 2-mercaptobenzimidazole or 2-mercaptomethylbenzimidazole.

3. The anti-migration macromolecular rubber antioxidant according to claim 2, characterized in that, The molar ratio of p-aminodiphenylamine, benzimidazole compounds, and epoxy group-containing compounds is 1:0.8-1.2:0.5-3.

4. The anti-migration macromolecular rubber antioxidant according to claim 2, characterized in that, The molar ratio of p-aminodiphenylamine, benzimidazole compounds, and epoxy group-containing compounds is 1:0.9-1.1:1-2.

5. A method for preparing the anti-migration macromolecular rubber antioxidant according to any one of claims 2 to 4, characterized in that, Includes the following steps: (1) After adding solvent to a three-necked flask with a protective atmosphere, add benzimidazole compounds, p-aminodiphenylamine, cashew phenol glycidyl ether and catalyst in proportion, stir until fully dissolved, and then heat to 135℃~180℃ to react for 2h~15h. (2) After cooling the mixture obtained after the reaction in step (1) to room temperature, wash and vacuum dry to obtain the migration-resistant macromolecular rubber antioxidant.

6. The preparation method according to claim 5, characterized in that, The protective atmosphere described in step (1) is nitrogen and / or an inert gas.

7. The preparation method according to claim 5, characterized in that, The solvent mentioned in step (1) is either acetone or ethyl acetate.

8. The preparation method according to claim 5, characterized in that, The catalyst is salicylic acid, and its addition amount is 0.5% to 2.5% of the total mass of the reactants.

9. The preparation method according to claim 5, characterized in that, The washing method in step (2) is as follows: repeatedly wash with sodium bicarbonate aqueous solution to remove salicylic acid, and then wash with deionized water multiple times to remove sodium bicarbonate.

10. A method for applying the anti-migration macromolecular rubber antioxidant according to any one of claims 1 to 4, characterized in that, The migration-resistant macromolecular rubber antioxidant is applied to natural rubber and / or synthetic rubber, and the amount of rubber antioxidant added is 1% to 3% of the raw rubber mass.

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