Preparation method of anti-aging agent DTPD

Abstract

The invention relates to the field of anti-aging agents DTPD, and particularly discloses a preparation method of the anti-aging agent DTPD. The preparation method of the anti-aging agent DTPD comprises the following steps: mixing aniline and o-toluidine, stirring, heating to 50-60 DEG C, adding hydroquinone and a catalyst, carrying out condensation reaction at 100-250 DEG C, removing evaporated water in the reaction process, and stopping the reaction until water cannot be evaporated; cooling to 100-140 DEG C, filtering while the mixture is hot, and distilling to remove impurities, so as to obtain the anti-aging agent DTPD; the catalyst is selected from one or more of benzene sulfonic acid, benzene disulfonic acid, p-toluenesulfonic acid, p-aminobenzene sulfonic acid, aniline trisulfonic acid and sulfonated halloysite. The preparation method disclosed by the invention has the advantages of high content of effective components in the product, simplicity and convenience in operation and safety.

Description

Technical Field

[0001] This application relates to the field of antioxidant DTPD, and more specifically, it relates to a method for preparing antioxidant DTPD. Background Technology

[0002] DTPD (N,N'-xylyl-p-phenylenediamine), a rubber antioxidant, is a p-phenylenediamine antioxidant. It is a highly efficient antioxidant used in the tire industry, with excellent ozone protection, good flexural and crack resistance, and can provide long-term protection. It has a wide range of applications.

[0003] The related technology discloses a method for preparing the rubber antioxidant DTPD, which includes using o-toluidine, aniline and hydroquinone as raw materials, carrying out a condensation reaction under high temperature conditions and the catalysis of ferric chloride, and then obtaining the finished antioxidant DTPD granules after washing, distillation, sedimentation and granulation.

[0004] However, the production process using ferric chloride as a catalyst has problems such as low reaction conversion rate, difficulty in removing impurities, and a large amount of waste, so it needs to be improved. Summary of the Invention

[0005] To improve the reaction conversion rate of the antioxidant DTPD production process, this application provides a method for preparing antioxidant DTPD.

[0006] This application provides a method for preparing the antioxidant DTPD, which adopts the following technical solution:

[0007] A method for preparing the antioxidant DTPD includes the following steps:

[0008] Aniline and o-toluidine are mixed and stirred and heated to 50-60℃. Hydroquinone and catalyst are added, and a condensation reaction is carried out at 100-250℃. During the reaction, evaporated water is removed and the reaction is terminated when no more water can be evaporated. The temperature is lowered to 100-140℃, filtered while hot, and impurities are removed by distillation to obtain the antioxidant DTPD.

[0009] The catalyst is selected from one or more of benzenesulfonic acid, benzenedisulfonic acid, p-toluenesulfonic acid, p-aminobenzenesulfonic acid, anilinetrisulfonic acid, and halloysite sulfonated.

[0010] By adopting the above technical solution, the type of catalyst for the condensation reaction is optimized. By selecting a specific catalyst, the content of effective components in the reaction product is increased, the occurrence of side reactions is reduced, and the possibility of generating a large amount of iron-containing wastewater and iron sludge by traditional preparation methods can be effectively avoided, thus reducing the three wastes. The hot filtration step can reduce the high-temperature water washing and separation process of the catalyst, which has a high safety factor and is simple to operate.

[0011] Preferably, the molar ratio of aniline, o-toluidine, and hydroquinone is (1-2.5):(1-1.5):1.

[0012] Preferably, the catalyst is p-toluenesulfonic acid and benzenedisulfonic acid in a mass ratio of 1:(0.3-0.5), and the mass of the catalyst is 3-8% of the hydroquinone.

[0013] By adopting the above technical solution and compounding p-toluenesulfonic acid and benzenedisulfonic acid in a specific mass ratio, the conversion rate of the antioxidant DTPD can be further improved, giving the antioxidant DTPD a higher content of effective ingredients, better catalytic effect, higher catalytic activity, and lower catalyst cost.

[0014] Preferably, the catalyst is sulfonated halloysite, specifically halloysite grafted with p-aminobenzenesulfonic acid; and the mass of the catalyst is 5-12% of the hydroquinone.

[0015] By adopting the above technical solution, the sulfonated halloysite solid catalyst is easy to recycle after use, which helps to reduce the generation of organic waste and is more green and safe; it also helps to improve the conversion rate of the antioxidant DTPD and make the content of the effective components of antioxidant DTPD more optimal.

[0016] Preferably, the method for preparing the sulfonated halloysite includes the following steps:

[0017] Step 1: After acid washing and drying, halloysite is treated under an ammonia plasma atmosphere to obtain aminated halloysite;

[0018] Step 2: Immerse aminated halloysite in an organic solvent, add polyisocyanate dropwise at 40-70℃ with stirring, and continue stirring for 1-4 hours. Then add p-aminobenzenesulfonic acid dropwise and continue stirring for 2-6 hours. Filter, wash, and dry to obtain sulfonated halloysite.

[0019] By employing the above technical solution, p-aminobenzenesulfonic acid is bonded and grafted onto the halloysite surface using polyisocyanate as a bridging agent. This ensures grafting strength and good stability, reducing the possibility of p-aminobenzenesulfonic acid loss after repeated use and improving catalyst lifespan. Halloysite has a rich porous structure and a natural nanotube structure, and its surface is rich in hydroxyl groups. After plasma surface treatment, it can carry abundant active amino groups, effectively loading p-aminobenzenesulfonic acid and ensuring a high grafting rate. By controlling the reaction temperature, side reactions can be reduced, ensuring the quality and purity of the catalyst product.

[0020] Preferably, the mass ratio of the aminated halloysite, polyisocyanate, and p-aminobenzenesulfonic acid is 1:(0.1-0.5):(0.3-0.8).

[0021] Preferably, the polyisocyanate is selected from toluene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate.

[0022] Preferably, step 2 further includes adding 5-10% sodium acetate catalyst by mass of aminated halloysite to the reaction system.

[0023] By adopting the above technical solution, the sodium acetate catalyst can improve the reaction activity, increase the formation efficiency of sulfonated halloysite, and help to further reduce the occurrence of side reactions.

[0024] Preferably, the pickling step specifically includes: immersing halloysite in a 10% hydrochloric acid solution, stirring and soaking for 1-3 hours, filtering out and washing with water until neutral.

[0025] By adopting the above technical solution, it is beneficial to improve the surface activity of halloysite and the grafting rate of p-aminobenzenesulfonic acid.

[0026] Preferably, the distillation temperature for the distillation and impurity removal step is 210-240℃, and the distillation time is 2-3 hours.

[0027] By adopting the above technical solution, unreacted reactants and intermediate products are removed through a distillation step, ensuring the purity of the antioxidant DTPD.

[0028] In summary, this application has the following beneficial effects:

[0029] 1. Because this application optimizes the type of catalyst for the condensation reaction, the content of effective components in the reaction product is increased by selecting a specific catalyst, the occurrence of side reactions is reduced, and the possibility of generating a large amount of iron-containing wastewater and iron sludge by traditional preparation methods can be effectively avoided, thus reducing the three wastes; the hot filtration step can reduce the high-temperature water washing and separation process of the catalyst, which has a high safety factor and is simple to operate.

[0030] 2. In this application, it is preferred to use p-toluenesulfonic acid and benzenedisulfonic acid in a specific mass ratio to further improve the conversion rate of the antioxidant DTPD, so that the antioxidant DTPD has a high content of effective ingredients, good catalytic effect, high catalytic activity, and low catalyst cost.

[0031] 3. In this application, sulfonated halloysite is preferred for the production of antioxidant DTPD, which further improves the conversion rate of antioxidant DTPD, makes the content of effective components of antioxidant DTPD better, and makes sulfonated halloysite easy to recycle after use, which helps to reduce the generation of organic waste and is more green and safe. Detailed Implementation

[0032] To further aid in understanding the technical solution of this invention, several specific implementation examples are provided below to describe the technical solution of this invention in more detail. All of these described embodiments are only some embodiments of this invention, and not all of them.

[0033] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments; and the reaction devices, monomer compounds, etc. involved in the following embodiments are all commercially available.

[0034] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0035] The following examples further illustrate the present invention, but the invention is not limited thereto. Unless otherwise specified in the examples, all percentages (%) are mass percentages.

[0036] Preparation Example

[0037] Preparation Example 1

[0038] This preparation example provides a sulfonated halloysite, prepared by the following method:

[0039] Halloysite was immersed in a 10% hydrochloric acid solution and stirred for 1 hour. After filtration, it was washed with water until the washing solution was neutral. It was then dried at 120°C and treated with ammonia plasma for 2 minutes to obtain aminated halloysite.

[0040] Take 20g of aminated halloysite and immerse it in 100ml of N,N-dimethylformamide. Under stirring conditions at 50℃, add 2g of toluene diisocyanate dropwise and stir continuously for 1h. Then add 6g of p-aminobenzenesulfonic acid dropwise and stir continuously for another 3h. Filter the mixture, wash it three times with anhydrous ethanol and deionized water respectively, and then dry it at 140℃ to obtain sulfonated halloysite.

[0041] Preparation Example 2

[0042] The only difference between this preparation example and Preparation Example 1 is that the method for preparing sulfonated halloysite is as follows:

[0043] Halloysite was immersed in a 10% hydrochloric acid solution and stirred for 1 hour. After filtration, it was washed with water until the washing solution was neutral. It was then dried at 120°C and treated with ammonia plasma for 2 minutes to obtain aminated halloysite.

[0044] Take 20g of aminated halloysite and immerse it in 120ml of N,N-dimethylformamide. Under stirring conditions at 50℃, add 8g of toluene diisocyanate dropwise and stir continuously for 3h. Then add 12g of p-aminobenzenesulfonic acid dropwise and stir continuously for another 5h. Filter the mixture, wash it three times with anhydrous ethanol and deionized water respectively, and then dry it at 140℃ to obtain sulfonated halloysite.

[0045] Preparation Example 3

[0046] The only difference between this preparation example and Preparation Example 1 is that the method for preparing sulfonated halloysite is as follows:

[0047] Halloysite was immersed in a 10% hydrochloric acid solution and stirred for 1 hour. After filtration, it was washed with water until the washing solution was neutral. It was then dried at 120°C and treated with ammonia plasma for 2 minutes to obtain aminated halloysite.

[0048] Take 20g of aminated halloysite and immerse it in 150ml of N,N-dimethylformamide. Under stirring conditions at 50℃, add 10g of toluene diisocyanate dropwise and stir continuously for 4h. Then add 16g of p-aminobenzenesulfonic acid dropwise and stir continuously for another 6h. Filter the mixture, wash it three times with anhydrous ethanol and deionized water respectively, and then dry it at 140℃ to obtain sulfonated halloysite.

[0049] Preparation Example 4

[0050] The only difference between this preparation example and Preparation Example 1 is that the method for preparing sulfonated halloysite is as follows:

[0051] Halloysite was immersed in a 10% hydrochloric acid solution, stirred and soaked for 1 hour, filtered, washed with water until the washing solution was neutral, and dried at 120°C to obtain activated halloysite.

[0052] Take 20g of activated halloysite and immerse it in 100ml of N,N-dimethylformamide. Under stirring conditions at 50℃, add 2g of toluene diisocyanate dropwise and stir continuously for 1h. Then add 6g of p-aminobenzenesulfonic acid dropwise and stir continuously for another 3h. Filter the mixture and wash it three times with anhydrous ethanol and deionized water respectively. Then dry it at 140℃ to obtain sulfonated halloysite.

[0053] Preparation Example 5

[0054] The only difference between this preparation example and Preparation Example 1 is that the method for preparing sulfonated halloysite is as follows:

[0055] Halloysite was washed with acetone, dried at 120°C, and then treated with ammonia plasma for 2 minutes to obtain aminated halloysite.

[0056] Take 20g of aminated halloysite and immerse it in 100ml of N,N-dimethylformamide. Under stirring conditions at 50℃, add 2g of toluene diisocyanate dropwise and stir continuously for 1h. Then add 6g of p-aminobenzenesulfonic acid dropwise and stir continuously for another 3h. Filter the mixture, wash it three times with anhydrous ethanol and deionized water respectively, and then dry it at 140℃ to obtain sulfonated halloysite.

[0057] Example

[0058] Example 1

[0059] This embodiment discloses a method for preparing the antioxidant DTPD, including the following steps:

[0060] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0061] The temperature is raised to 70℃, and 110g of hydroquinone and 5g of benzenesulfonic acid are added to the reactor. The temperature is then raised to 230℃ to carry out a condensation reaction. The water and excess amine generated by the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0062] After about 4 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 229g of the antioxidant DTPD product.

[0063] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 93.5%, and the melting point was 91.5℃.

[0064] Example 2

[0065] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0066] Add 130g of aniline and 130g of o-toluidine to the reactor and stir to mix well;

[0067] The temperature is raised to 70℃, and 110g of hydroquinone and 5g of p-toluenesulfonic acid are added to the reactor. The temperature is then raised to 230℃ to carry out a condensation reaction. The water and excess amine generated by the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0068] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 233g of the antioxidant DTPD product.

[0069] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 92.9%, and the melting point was 92.5℃.

[0070] Example 3

[0071] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0072] Add 220g of aniline and 160g of o-toluidine to the reactor and stir to mix well;

[0073] The temperature is raised to 70℃, and 110g of hydroquinone and 3g of benzene disulfonic acid are added to the reactor. The temperature is then raised to 240℃ to carry out a condensation reaction. The water and excess amine generated by the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0074] After about 4 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 213g of the antioxidant DTPD product.

[0075] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 88.9%, and the melting point was 90.2℃.

[0076] Example 4

[0077] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0078] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0079] The temperature is raised to 70℃, and 110g hydroquinone, 3.8g p-toluenesulfonic acid and 1.2g benzenedisulfonic acid are added to the reactor. The temperature is then raised to 230℃ to carry out a condensation reaction. The water and excess amine generated in the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0080] After about 5 hours of reaction, when no more water is produced, the reaction reaches its endpoint. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 220g of the antioxidant DTPD product.

[0081] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 96.2%, and the melting point was 91.7℃.

[0082] Example 5

[0083] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0084] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0085] The temperature is raised to 70℃, and 110g hydroquinone, 3.4g p-toluenesulfonic acid and 1.6g benzenedisulfonic acid are added to the reactor. The temperature is then raised to 230℃ to carry out a condensation reaction. The water and excess amine generated in the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0086] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 217g of the antioxidant DTPD product.

[0087] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 95.8%, and the melting point was 92.2℃.

[0088] Example 6

[0089] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0090] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0091] The temperature is raised to 70℃, and 110g hydroquinone, 3g p-toluenesulfonic acid and 2g benzenedisulfonic acid are added to the reactor. The temperature is then raised to 230℃ to carry out a condensation reaction. The water and excess amine generated by the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0092] After about 4 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 210g of the antioxidant DTPD product.

[0093] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 92.5%, and the melting point was 92.1℃.

[0094] Example 7

[0095] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0096] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0097] The temperature is raised to 70℃, and 110g hydroquinone, 4.2g p-toluenesulfonic acid and 0.8g benzenedisulfonic acid are added to the reactor. The temperature is then raised to 230℃ to carry out a condensation reaction. The water and excess amine generated in the reaction enter the phase separator in an azeotropic manner. The amine is refluxed back to the reactor, and the water is continuously discharged.

[0098] After about 5 hours of reaction, when no more water is produced, the reaction reaches its endpoint. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 235g of the antioxidant DTPD product.

[0099] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 90.6%, and the melting point was 91.2℃.

[0100] Example 8

[0101] The only difference between this embodiment and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0102] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0103] The temperature was raised to 70°C, and 110g of hydroquinone and 8g of sulfonated halloysite prepared in Example 1 were added to the reactor. The temperature was then raised to 230°C to carry out a condensation reaction. The water and excess amine generated in the reaction azeotropically entered the phase separator, the amine was refluxed back to the reactor, and the water was continuously discharged.

[0104] After about 5 hours of reaction, when no more water is produced, the reaction reaches its endpoint. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 230g of the antioxidant DTPD product.

[0105] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 96.7%, and the melting point was 92.5℃.

[0106] Example 9

[0107] The only difference between this embodiment and Embodiment 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0108] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0109] The temperature was raised to 70°C, and 110g of hydroquinone and 8g of sulfonated halloysite prepared in Example 2 were added to the reactor. The temperature was then raised to 230°C to carry out a condensation reaction. The water and excess amine generated in the reaction azeotropically entered the phase separator, the amine was refluxed back to the reactor, and the water was continuously discharged.

[0110] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and then distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 226g of the antioxidant DTPD product.

[0111] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 98.4%, and the melting point was 93.6℃.

[0112] Example 10

[0113] The only difference between this embodiment and Embodiment 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0114] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0115] The temperature was raised to 70°C, and 110g of hydroquinone and 8g of sulfonated halloysite prepared in Example 3 were added to the reactor. The temperature was then raised to 230°C to carry out a condensation reaction. The water and excess amine generated in the reaction azeotropically entered the phase separator, the amine was refluxed back to the reactor, and the water was continuously discharged.

[0116] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 231g of the antioxidant DTPD product.

[0117] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 97.5%, and the melting point was 93.1℃.

[0118] Example 11

[0119] The only difference between this embodiment and Embodiment 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0120] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0121] The temperature was raised to 70°C, and 110g of hydroquinone and 8g of sulfonated halloysite prepared in Example 4 were added to the reactor. The temperature was then raised to 230°C to carry out a condensation reaction. The water and excess amine generated in the reaction azeotropically entered the phase separator, the amine was refluxed back to the reactor, and the water was continuously discharged.

[0122] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and then distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 226g of the antioxidant DTPD product.

[0123] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 97.1%, and the melting point was 92.4℃.

[0124] Example 12

[0125] The only difference between this embodiment and Embodiment 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0126] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0127] The temperature was raised to 70°C, and 110g of hydroquinone and 8g of sulfonated halloysite prepared in Example 5 were added to the reactor. The temperature was then raised to 230°C to carry out a condensation reaction. The water and excess amine generated in the reaction azeotropically entered the phase separator, the amine was refluxed back to the reactor, and the water was continuously discharged.

[0128] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 223g of the antioxidant DTPD product.

[0129] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 94.3% and the melting point was 92.1℃.

[0130] Example 13

[0131] The only difference between this embodiment and Embodiment 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0132] Add 102g of aniline and 118g of o-toluidine to the reactor and stir to mix well;

[0133] The temperature was raised to 70°C, and 110g of hydroquinone and 8g of sulfonated halloysite prepared in Example 6 were added to the reactor. The temperature was then raised to 230°C to carry out a condensation reaction. The water and excess amine generated in the reaction azeotropically entered the phase separator, the amine was refluxed to the reactor, and the water was continuously discharged.

[0134] After about 5 hours of reaction, the reaction reaches its endpoint when no more water is produced. The reaction solution is cooled to 120°C, filtered while hot to remove the catalyst, and distilled at 230°C for 2 hours to remove aniline, o-toluidine and intermediate products, yielding 229g of the antioxidant DTPD product.

[0135] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 95.0%, and the melting point was 91.0℃.

[0136] Comparative Example

[0137] The only difference between this comparative example and Example 1 is that the preparation method of the antioxidant DTPD includes the following steps:

[0138] Add 100g of aniline and 200g of o-toluidine to the reactor and stir to mix well;

[0139] After heating to 70℃, 110g hydroquinone, 5.5g anhydrous ferric chloride and 10g toluene were added to the reactor. The temperature was then raised to 250℃ to carry out the condensation reaction. The water generated in the reaction was continuously removed by the solvent toluene. The reaction reached its endpoint when no more water was generated.

[0140] The reaction solution was cooled to 110℃, and 50g of 10% trisodium phosphate was added to neutralize the reaction solution. The water layer in the reaction solution was separated and removed. The solution was washed three times with deionized water at 90℃ until it was neutral. After removing water, aniline, o-toluidine and intermediate products by distillation at 220℃, 198g of antioxidant DTPD product was obtained.

[0141] Gas chromatography and capillary melting point analysis were performed on the finished antioxidant DTPD product, and the effective component content of the finished antioxidant DTPD product prepared in this embodiment was 84%, and the melting point was 90.3℃.

[0142] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing the antioxidant DTPD, characterized in that, Includes the following steps: Aniline and o-toluidine are mixed and stirred and heated to 50-60℃. Hydroquinone and catalyst are added, and a condensation reaction is carried out at 100-250℃. During the reaction, evaporated water is removed and the reaction is terminated when no more water can be evaporated. The temperature is lowered to 100-140℃, filtered while hot, and impurities are removed by distillation to obtain the antioxidant DTPD. The catalyst is selected from one or more of benzenesulfonic acid, benzenedisulfonic acid, p-toluenesulfonic acid, p-aminobenzenesulfonic acid, anilinetrisulfonic acid, and halloysite sulfonated.

2. The method for preparing the antioxidant DTPD according to claim 1, characterized in that, The molar ratio of aniline, o-toluidine, and hydroquinone is (1-2.5):(1-1.5):

1.

3. The method for preparing the antioxidant DTPD according to claim 2, characterized in that, The catalyst is p-toluenesulfonic acid and benzenedisulfonic acid in a mass ratio of 1:(0.3-0.5), and the mass of the catalyst is 4-10% of the hydroquinone.

4. The method for preparing the antioxidant DTPD according to claim 2, characterized in that, The catalyst is sulfonated halloysite, specifically halloysite grafted with p-aminobenzenesulfonic acid; and the mass of the catalyst is 5-12% of the hydroquinone.

5. The method for preparing the antioxidant DTPD according to claim 4, characterized in that, The method for preparing the sulfonated halloysite includes the following steps: Step 1: After acid washing and drying, halloysite is treated under an ammonia plasma atmosphere to obtain aminated halloysite; Step 2: Immerse aminated halloysite in an organic solvent, add polyisocyanate dropwise at 40-70℃ with stirring, and continue stirring for 1-4 hours. Then add p-aminobenzenesulfonic acid dropwise and continue stirring for 2-6 hours. Filter, wash, and dry to obtain sulfonated halloysite.

6. The method for preparing the antioxidant DTPD according to claim 5, characterized in that, The mass ratio of the aminated halloysite, polyisocyanate, and p-aminobenzenesulfonic acid is 1:(0.1-0.5):(0.3-0.8).

7. The method for preparing the antioxidant DTPD according to claim 5, characterized in that, The polyisocyanate is selected from toluene diisocyanate, diphenylmethane diisocyanate, and isophorone diisocyanate.

8. The method for preparing the antioxidant DTPD according to claim 5, characterized in that, Step 2 further includes adding 5-10% sodium acetate catalyst by mass of aminated halloysite to the reaction system.

9. The method for preparing the antioxidant DTPD according to claim 5, characterized in that, The pickling step specifically includes: immersing halloysite in a 10% hydrochloric acid solution, stirring and soaking for 1-3 hours, filtering out and washing with water until neutral.

10. The method for preparing the antioxidant DTPD according to claim 1, characterized in that, The distillation temperature for the impurity removal step is 210-240℃, and the distillation time is 2-3 hours.