Preparation method of slow-release DTPD anti-aging agent capable of reducing migration rate

Abstract

The invention relates to the technical field of rubber anti-aging agents, in particular to a preparation method of a slow-release DTPD anti-aging agent capable of reducing migration rate, which mainly comprises the following three steps: preparing a mesoporous double-sphere template, preparing an anti-aging coupling agent and grafting the mesoporous double-sphere template and the anti-aging coupling agent. The slow-release DTPD anti-aging agent prepared by the method can effectively improve the dispersion effect of a carrier type anti-aging agent in a rubber base, and the migration resistance and volatility resistance of the anti-aging agent are improved by designing the shape of the anti-aging agent carrier; moreover, the slow-release DTPD anti-aging agent can generate hydrogen-bond interaction with a rubber molecular chain, so that the interface bonding between rubber matrixes is improved, free radicals generated by the rubber molecular chain in the thermal oxidation process are captured, the autocatalytic reaction of the rubber molecular chain is inhibited, and the thermal oxidation resistance of the material is improved; due to low ionization potential and high reaction rate with ozone resistance, the ozone oxidation resistance of the material can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of rubber antioxidants, and in particular to a method for preparing an ageing-resistant DTPD rubber antioxidant for tires. Background Art

[0002] During long-term storage and use, the rubber components in tires will be affected by heat, oxygen, ozone resistance, variable valence metal ions, mechanical stress, light, high-energy rays, and erosion by other chemicals and molds, causing aging. In order to delay or inhibit this aging process, antioxidants need to be added. However, antioxidants will migrate in the rubber network as the environment changes during the use of the rubber, causing the antioxidants to lose their effectiveness prematurely and be unable to protect. In order to solve the above problems, common solutions include: preparing macromolecular antioxidants or reactive antioxidants to slow down their migration speed in the rubber network, thereby achieving the purpose of slowing down rubber aging.

[0003] However, the preparation of macromolecular antioxidants will have the risk of reducing the utilization efficiency of antioxidants, and the grafting rate of reactive antioxidants directly grafted into the rubber chain structure is low, and generally grafting reactions occur with rubber molecular chains containing double bond structures such as natural rubber, reducing dispersibility. Taking the above factors into consideration, in the face of the "blooming" phenomenon of small molecule additives in rubber, the use of filler grafted or loaded antioxidants added to rubber, that is, the method of fixing the antioxidant in a certain filler carrier and then adding it to the rubber has gradually gained attention.

[0004] For example, the article "Preparation of a new multifunctional biomass rubber antioxidant and its effect on the structure and properties of rubber composites" (DOI: 10.27151 / d.cnki.ghnlu.2021.001601) mentioned the method of using silica and halloysite nanotubes as carriers to load rubber antioxidants, and both carrier methods have achieved remarkable results. However, the above methods also have defects that cannot be ignored due to the nature of the carrier itself: SiO2 carriers are prone to a large number of hydrogen bonds, which can easily cause large-sized agglomerations and cannot be well dispersed in the rubber matrix; and halloysite nanotubes have a rod-like structure, and the structural overlap between each other will further weaken the interfacial bonding strength between the filler and the rubber matrix.

[0005] Therefore, the inventors tried to design a new carrier material that can not only meet the loading requirements of small molecule antioxidants, but also further improve the dispersion in the rubber matrix, and further avoid the problem of stress concentration points in the rubber matrix caused by the addition of the carrier antioxidant itself. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a method for preparing a slow-release DTPD antioxidant with reduced migration rate, as described below.

[0007] S1. Preparation of mesoporous double-sphere template:

[0008] S1-1. Preparation of dispersion:

[0009] Add styrene, sodium styrenesulfonate, 4,4-dihydroxybenzophenone, and azobisisobutyronitrile into 60 vol% methanol aqueous solution, and ultrasonically mix to obtain a dispersion.

[0010] S1-2. Preparation of double-sphere template:

[0011] Heat the dispersion from room temperature to 75 °C at a rate of 4 - 5 °C / min and keep it warm for 5 - 6 h; then filter the completely reacted dispersion to obtain a filter cake, and wash the filter cake with methanol 3 - 5 times to obtain a double-sphere template.

[0012] Note: The advantage of preparing a double-sphere template through an organic polymer is that by adjusting the type, addition amount, and reaction environment of the organic polymer, it is easier to control the macroscopic morphology of the product and obtain the carrier shape compared with inorganic substances; and the double-sphere template not only has a large specific surface area, but also is less likely to migrate in the rubber matrix due to its "abnormal structure", and there is less overlap and agglomeration between carriers compared with carriers with "rod-shaped and tubular structures", so it has additional advantages.

[0013] S1-3. Carbonization treatment of double-sphere template:

[0014] Add the double-sphere template into water to prepare a mixed solution with a concentration of 1 - 2 mol / L, then heat it at 200 °C for 2 - 3 h, filter the completely reacted solution to obtain a filter cake, and wash the filter cake with deionized water and ethanol alternately until the filtrate is colorless to obtain a carbonized double-sphere template.

[0015] Note: High-temperature treatment carbonizes the organic polymer, fixes the macroscopic external structure of the carrier, and washes away excess impurities, serving as a pure template for subsequent reactions.

[0016] S1-4. In-situ generation of calcium carbonate microspheres on the carbonized double-sphere template:

[0017] Add calcium acetate into 50 vol% ethanol aqueous solution, mix evenly, then add the carbonized double-sphere template, and ultrasonically disperse it at 30 °C for 5 - 6 h to obtain a mixed solution.

[0018] Filter the mixed solution to obtain a filter cake, then wash the filter cake with deionized water 3 - 5 times, then dry it at 80 °C for 12 h, and finally heat it at a gradient temperature to obtain a mesoporous double-sphere template.

[0019] Description: A mesoporous double-sphere template is prepared by a soft template method, and then calcium carbonate microspheres with a hollow structure are in-situ generated on the asymmetric carbon microsphere template. In this way, not only the macroscopic shape of the template can be determined, but also the agglomeration phenomenon of the microspheres themselves can be avoided during the direct preparation of calcium carbonate microspheres.

[0020] S2. Prepare the antioxidant coupling agent: The antioxidant coupling agent is prepared by a one-step method using antioxidant PPDA and silane coupling agent KH-550 as raw materials.

[0021] S3. Graft the mesoporous double-sphere template with the antioxidant coupling agent: The mesoporous double-sphere template prepared in S1 is dispersed in a 95 vol% ethanol aqueous solution, and then the antioxidant coupling agent prepared in S2 is added and mixed evenly. After the reaction is complete, a slow-release DTPD antioxidant is obtained.

[0022] Furthermore, in the step of preparing the dispersion liquid in S1-1, the addition amounts of each component are as follows:

[0023] Denote n as the magnification coefficient and n ∈ R+, then the addition amount of styrene is 2.5n mL, the addition amount of sodium styrene sulfonate is [0.0453, 0.046]n g; the addition amount of 4,4-dihydroxybenzophenone is [0.002, 0.03]n g; the addition amount of azobisisobutyronitrile is [0.0453, 0.046]n g; the addition amount of 60 vol% methanol aqueous solution is [10, 12]n mL.

[0024] Furthermore, in the step of in-situ generating calcium carbonate microspheres on the carbonized double-sphere template in S1-4, the addition amounts of each component are as follows:

[0025] Denote n as the magnification coefficient and n ∈ R+, then the addition amount of calcium acetate is 0.1n mol, the addition amount of the carbonized double-sphere template is [300, 400]n mg; the addition amount in 50 vol% ethanol aqueous solution is [10, 12]n mL;

[0026] The gradient temperature used for heating when preparing the mesoporous double-sphere template is as follows:

[0027] First, heat from room temperature to 400 °C at a rate of 2 - 3 °C / min and hold for 8 - 10 min; then heat from 400 °C to 500 °C at a rate of 1 - 2 °C / min and hold for 2 - 2.5 h; finally, cool to room temperature with the furnace.

[0028] Furthermore, the specific steps for preparing the antioxidant coupling agent in S2 are as follows:

[0029] S2-1. Mix antioxidant PPDA and silane coupling agent KH-550 evenly, and then stir and heat in an oil bath environment at 140 °C for 2 - 3 h;

[0030] S2-2. After heating is completed, when the reaction system cools down to 60-70 °C, add an aqueous ethanol solution of 95 vol%, and ultrasonically oscillate for 20-30 min to obtain the alcoholysis anti-aging coupling agent;

[0031] Let n be the magnification coefficient and n ∈ R+, then the addition amount of anti-aging agent PPDA is [19,20]n g, the addition amount of silane coupling agent KH-550 is [21,22]n mL, and the addition amount of the 95 vol% aqueous ethanol solution is [20,25]n mL.

[0032] Note: In an environment such as heat oxygen and ozone, the rubber molecular chain ages and loses protons. First, it oxidizes to form an alkyl radical R·, then changes to a peroxide free radical ROO·. ROO· undergoes a hydrogen abstraction reduction reaction to form ROOH and a new alkyl radical R·, which then reacts to form a chain cycle of rubber aging. The anti-aging agent PPDA (N,N'-ditolyl-p-phenylenediamine) can participate in the hydrogen abstraction reduction reaction of ROO· due to the obvious donating effect of the hydrogen atom in the -OH group, and the dehydrogenated anti-aging agent molecule can also capture the peroxide free radical ROO·. In this way, it can hinder the chain growth reaction to delay or terminate the aging phenomenon.

[0033] The amino group (-NH2) in the silane coupling agent KH-550 can form hydrogen bonds or covalent bonds with the aniline group of the anti-aging agent DTPD, and the ethoxy group (-Si-O-) condenses with the hydroxyl group on the surface of calcium carbonate. Therefore, it is a preferred coupling agent.

[0034] Further, the specific steps for grafting the mesoporous double-sphere template with the anti-aging coupling agent in S3 are as follows:

[0035] S3-1. Ultrasonically oscillate the mesoporous double-sphere template prepared in S1 in an aqueous ethanol solution of 95 vol% for 20-30 min. After sufficient dispersion, add the anti-aging coupling agent prepared in S2 and mix evenly to obtain a mixed solution;

[0036] Let n be the magnification coefficient and n ∈ R+, then the addition amount of the mesoporous double-sphere template is [200,210]n mg, the addition amount of the 95 vol% aqueous ethanol solution is [100,150]n mL, and the addition amount of the anti-aging coupling agent is [300,310]n mg.

[0037] S3-2. Stir and heat the mixed solution prepared in S3-1 at 80 °C for 4-4.5 h, filter to obtain a filter cake, wash the filter cake with ethanol 5-7 times, and finally dry the washed filter cake to obtain the slow-release DTPD anti-aging agent.

[0038] Description: A DTPD antioxidant with a slow-release effect was prepared by chemical grafting. Since the DTPD antioxidant is confined in the mesoporous double-sphere template, it will gradually diffuse during the service life of the rubber, providing long-term anti-thermal oxidation performance and anti-ozone oxidation performance. (After aging for 7 days under the condition of 100 °C thermal oxygen aging, compared with the small-molecule antioxidant with the same content, the rubber has excellent anti-"blooming" performance and less antioxidant content on the migrated surface). Moreover, in the present invention, by adjusting the reaction conditions, the grafting rate of the carrier antioxidant can reach 20-25%. Data show that the antioxidant prepared in the present invention has effectively improved performance compared with similar products.

[0039] As another aspect of the present invention, a slow-release DTPD antioxidant with a reduced migration rate prepared in the present invention can be applied to the preparation of the sidewall part of a tire, which can significantly reduce the "blooming" phenomenon of additives caused by heat and ozone in the sidewall part of an automobile tire, and can improve the tensile strength and elongation at break retention rate of this part.

[0040] Description: The sidewall part of a tire has higher requirements for bending deformation resistance and ozone oxidation resistance compared with the tread, belt layer or inner liner. The pure DTPD antioxidant has outstanding antioxidant performance, but it is insufficient in anti-thermal oxidation performance compared with 6PPD or TMQ antioxidants. Therefore, when designing the antioxidant carrier, its advantages should be guaranteed while its disadvantages should be compensated to improve the overall performance.

[0041] Compared with the existing rubber antioxidants, the beneficial effects of the present invention are as follows:

[0042] (1) The slow-release DTPD antioxidant prepared in the present invention can effectively improve the dispersion effect of the carrier antioxidant in the rubber matrix, and by designing the morphology of the antioxidant carrier, improve the migration resistance and volatility resistance of the antioxidant, and avoid the precipitation of the antioxidant on the surface of the rubber product, that is, significantly reduce the occurrence of the blooming phenomenon.

[0043] (2) The slow-release DTPD antioxidant prepared in the present invention can form hydrogen bond interactions with the rubber molecular chains, improve the interfacial bonding between the rubber matrices, capture the free radicals generated by the rubber molecular chains during the thermal oxidation process, inhibit its autocatalytic reaction, and improve the anti-thermal oxidation performance of the material.

[0044] (3) The slow-release DTPD antioxidant prepared in the present invention has a lower ionization potential and a higher reaction rate with ozone resistance compared with the rubber. Therefore, it can enhance the internal structural stability of the rubber and improve the anti-ozone oxidation performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the flow chart of the present invention.

[0046] Figure 2It is the mechanical strength diagram of the rubber after incorporating the slow-release DTPD antioxidant in the experimental examples of the present invention;

[0047] Figure 3 It is the migration resistance performance diagram of the rubber after incorporating the slow-release DTPD antioxidant in the experimental examples of the present invention. Specific implementation mode

[0048] To further elaborate on the methods adopted and the effects achieved by the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with experiments.

[0049] Example 1: The content recorded in this example is a preparation method of a slow-release DTPD antioxidant for reducing the migration rate under a certain set of parameters.

[0050] S1. Prepare a mesoporous double-sphere template:

[0051] S1-1. Prepare a dispersion:

[0052] Add 2.5 mL of styrene, 0.0453 g of sodium styrene sulfonate, 0.002 g of 4,4-dihydroxybenzophenone, and 0.0453 g of azobisisobutyronitrile to 10 mL of a 60 vol% methanol aqueous solution, and ultrasonically mix to obtain a dispersion;

[0053] S1-2. Prepare a double-sphere template:

[0054] Heat the dispersion from room temperature to 75 °C at a rate of 4 °C / min and keep it warm for 5 h; then filter the completely reacted dispersion to obtain a filter cake, and wash the filter cake 3 times with methanol to obtain a double-sphere template;

[0055] S1-3. Carbonize the double-sphere template:

[0056] Add the double-sphere template to water to prepare a mixed solution with a concentration of 1 mol / L, and then heat it at 200 °C for 23 h. After the reaction is complete, filter it to obtain a filter cake, and wash the filter cake alternately with deionized water and ethanol until the filtrate is colorless to obtain a carbonized double-sphere template;

[0057] S1-4. In-situ generate calcium carbonate microspheres on the carbonized double-sphere template:

[0058] Add 0.1 mol of calcium acetate to 10 mL of a 50 vol% ethanol aqueous solution, mix evenly, and then add 300 mg of the carbonized double-sphere template, and ultrasonically disperse it at 30 °C for 6 h to obtain a mixed solution;

[0059] Filter the mixed solution to obtain a filter cake, then wash the filter cake 3 times with deionized water, then dry it at 80 °C for 12 h, and finally heat it at a gradient temperature to obtain a mesoporous double-sphere template;

[0060] The gradient temperature parameters are as follows: First, heat from room temperature to 400 °C at a rate of 2 °C / min and hold for 8 min; then heat from 400 °C to 500 °C at a rate of 1 °C / min and hold for 2 h; finally, cool to room temperature in the furnace.

[0061] S2. Prepare the anti-aging coupling agent:

[0062] S2-1. Mix 19 g of antioxidant PPDA and 21 mL of silane coupling agent KH-550 evenly, and then stir and heat in an oil bath at 140 °C for 2 h;

[0063] S2-2. After heating, when the reaction system cools to 60 °C, add 20 mL of 95 vol% ethanol aqueous solution and ultrasonically vibrate for 20 min to obtain the alcoholyzed anti-aging coupling agent.

[0064] S3. Graft the mesoporous double-sphere template with the anti-aging coupling agent:

[0065] S3-1. Ultrasonically vibrate 200 mg of the mesoporous double-sphere template prepared in S1 in 100 mL of 95 vol% ethanol aqueous solution for 20 min. After sufficient dispersion, add 300 mg of the anti-aging coupling agent prepared in S2 and mix evenly to obtain a mixed solution;

[0066] S3-2. Stir and heat the mixed solution prepared in S3-1 at 80 °C for 4 h, filter to obtain a filter cake, wash the filter cake 5 times with ethanol, and finally dry the washed filter cake to obtain the slow-release DTPD antioxidant.

[0067] Example 2: The content recorded in this example is the preparation method of a slow-release DTPD antioxidant with a reduced migration rate under another parameter.

[0068] S1. Prepare the mesoporous double-sphere template:

[0069] S1-1. Prepare the dispersion:

[0070] Add 2.5 mL of styrene, 0.0455 ng of sodium styrene sulfonate, 0.015 g of 4,4-dihydroxybenzophenone, and 0.0455 g of azobisisobutyronitrile to 11 mL of 60 vol% methanol aqueous solution, and ultrasonically mix to obtain the dispersion;

[0071] S1-2. Prepare the double-sphere template:

[0072] Heat the dispersion from room temperature to 75 °C at a rate of 4.5 °C / min and hold for 5.5 h; then filter the completely reacted dispersion to obtain a filter cake, and wash the filter cake 4 times with methanol to obtain the double-sphere template;

[0073] S1-3. Carbonization treatment of the double-sphere template:

[0074] Add the double-sphere template to water to prepare a mixed solution with a concentration of 1.5 mol / L, and then heat it at 200 °C for 2.5 h. After the reaction is complete, filter the mixture to obtain a filter cake, and wash the filter cake alternately with deionized water and ethanol until the filtrate is colorless to obtain the carbonized double-sphere template.

[0075] S1-4: In-situ generation of calcium carbonate microspheres on the carbonized double-sphere template:

[0076] Add 0.1 mol of calcium acetate to 11n mL of 50 vol% ethanol aqueous solution, mix well, and then add 350 mg of the carbonized double-sphere template, and ultrasonically disperse it at 30 °C for 5.5 h to obtain a mixed solution.

[0077] Filter the mixed solution to obtain a filter cake, then wash the filter cake 4 times with deionized water, then dry it at 80 °C for 12 h, and finally heat it at a gradient temperature to obtain the mesoporous double-sphere template.

[0078] The gradient temperature parameters are as follows: First, heat from room temperature to 400 °C at a rate of 2.5 °C / min and hold for 9 min; then heat from 400 °C to 500 °C at a rate of 1.5 °C / min and hold for 2.3 h; finally, cool to room temperature with the furnace.

[0079] S2: Preparation of the antioxidant coupling agent:

[0080] S2-1: Mix 19.5 g of antioxidant PPDA with 21.5 mL of silane coupling agent KH-550 evenly, and then stir and heat in an oil bath environment at 140 °C for 2 - 3 h.

[0081] S2-2: After the heating is completed, when the reaction system cools down to 65 °C, add 23 mL of 95 vol% ethanol aqueous solution and ultrasonically vibrate for 25 min to obtain the alcoholyzed antioxidant coupling agent.

[0082] S3: Grafting of the mesoporous double-sphere template and the antioxidant coupling agent:

[0083] S3-1: Ultrasonically vibrate 205 mg of the mesoporous double-sphere template prepared in S1 in 120 mL of 95 vol% ethanol aqueous solution for 25 min. After sufficient dispersion, add 305 mg of the antioxidant coupling agent prepared in S2 and mix evenly to obtain a mixed solution.

[0084] S3-2: Stir and heat the mixed solution prepared in S3-1 at 80 °C for 4 - 4.5 h, filter the mixture to obtain a filter cake, wash the filter cake 6 times with ethanol, and finally dry the washed filter cake to obtain the slow-release DTPD antioxidant.

[0085] Example 3: The content recorded in this example is the preparation method of the slow-release DTPD antioxidant with a reduced migration rate under another parameter.

[0086] S1. Preparation of mesoporous double-sphere template:

[0087] S1-1. Preparation of dispersion:

[0088] Add 2.5 mL of styrene, 0.046 g of sodium styrene sulfonate, 0.03 g of 4,4-dihydroxybenzophenone, and 0.046 g of azobisisobutyronitrile into 12 mL of 60 vol% methanol aqueous solution, and ultrasonically mix to obtain a dispersion;

[0089] S1-2. Preparation of double-sphere template:

[0090] Heat the dispersion from room temperature to 75 °C at a rate of 5 °C / min and keep it warm for 6 h; then filter the completely reacted dispersion to obtain a filter cake, and wash the filter cake with methanol 5 times to obtain a double-sphere template;

[0091] S1-3. Carbonization treatment of double-sphere template:

[0092] Add the double-sphere template into water to prepare a mixed solution with a concentration of 2 mol / L, then heat it at 200 °C for 3 h. After the reaction is complete, filter it to obtain a filter cake, and wash the filter cake alternately with deionized water and ethanol until the filtrate is colorless to obtain a carbonized double-sphere template;

[0093] S1-4. In-situ generation of calcium carbonate microspheres on the carbonized double-sphere template:

[0094] Add 0.1 mol of calcium acetate into 12 mL of 50 vol% ethanol aqueous solution, mix evenly, then add 400 mg of the carbonized double-sphere template, and ultrasonically disperse it at 30 °C for 6 h to obtain a mixed solution;

[0095] Filter the mixed solution to obtain a filter cake, then wash the filter cake with deionized water 5 times, then dry it at 80 °C for 12 h, and finally heat it at a gradient temperature to obtain a mesoporous double-sphere template;

[0096] The gradient temperature parameters are as follows: first, heat from room temperature to 400 °C at a rate of 3 °C / min and keep it warm for 10 min; then heat from 400 °C to 500 °C at a rate of 2 °C / min and keep it warm for 2.5 h; finally, cool it to room temperature with the furnace.

[0097] S2. Preparation of antioxidant coupling agent:

[0098] S2-1. Mix 20 g of antioxidant PPDA and 22 mL of silane coupling agent KH-550 evenly, and then stir and heat it in an oil bath environment at 140 °C for 3 h;

[0099] After heating is completed, when the reaction system cools down to 70 °C, add 25 mL of 95 vol% ethanol aqueous solution and ultrasonically vibrate for 30 min to obtain an alcoholyzed antioxidant coupling agent.

[0100] S3, grafting of mesoporous double-sphere template and antioxidant coupling agent:

[0101] S3-1. Ultrasonically vibrate 210 mg of the mesoporous double-sphere template prepared in S1 in 150 mL of 95 vol% ethanol aqueous solution for 30 min. After sufficient dispersion, add 310 mg of the antioxidant coupling agent prepared in S2 and mix evenly to obtain a mixed solution.

[0102] S3-2. Stir and heat the mixed solution prepared in S3-1 at 80 °C for 4.5 h. Filter to obtain a filter cake, wash the filter cake 7 times with ethanol, and finally dry the washed filter cake to obtain the slow-release DTPD antioxidant.

[0103] Experimental example: The description basis of this experimental example is the recording scheme in Example 1, aiming to clarify the actual application effect of the present invention.

[0104] Experimental design: To clarify the specific performance of the slow-release DTPD antioxidant with reduced migration rate prepared by the present invention, a composite rubber after mixing styrene-butadiene rubber (SBR) and the slow-release DTPD antioxidant is prepared in this experimental example to elaborate on the performance of the composite rubber:

[0105] Plasticate SBR 3 times on an open mill, then sequentially add the slow-release DTPD antioxidant and other additives. After mixing evenly, pass through the mill to make sheets. After the prepared mixed rubber is placed at room temperature for 12 h, hot press and vulcanize according to the optimum vulcanization time (T C90 ) measured at 160 °C to prepare the composite rubber.

[0106] Among them, other additives include: zinc oxide: 5 phr; stearic acid: 2 phr; N-cyclohexyl-2-benzothiazole sulfenamide: 2 phr; sulfur: 2 phr.

[0107] Table 1 Composition ratio of the composite rubber

[0108]

[0109] To compare the influence brought by the slow-release DTPD antioxidant, a blank group and each control group are designed based on the data in Table 1 to compare the actual performance of the present invention under different experimental conditions. The specific data are shown in Figure 2 and Figure 3 .

[0110] And from Figure 2It can be seen from the data that the tensile strength and tensile fracture strength of the composite rubber in Control Groups 1-5 are higher than those of the blank group, and the strength reaches the peak at the ratio in Control Group 4. Among them, the increase in tensile strength in Control Group 4 is 64.7%, and the increase in tensile fracture strength is 28.1%. Therefore, in actual use, this set of data should be used as the main reference standard. It should be noted that the tensile strength and tensile fracture strength of the composite rubber in Control Group 5 decreased slightly. This is because too high a content of the slow-release DTPD antioxidant will cause the slow-release DTPD antioxidant particles to be unevenly distributed on the rubber molecular chain, thereby reducing the interfacial bonding force between the filler and the rubber. Therefore, in actual application, the dosage of the slow-release DTPD antioxidant should be set according to actual needs to achieve better bonding strength.

[0111] From Figure 3 Figure shows the extraction resistance performance graph of sulfur elements in the composite rubber, which is used to reflect the influence of the slow-release DTPD antioxidant on the volatile resistance performance of the composite rubber. The residual amounts of sulfur elements (from the additives in the experimental design of this example) in the blank group and Control Groups 1-5 were measured by acetone extraction. The sulfur content in the composite rubber was measured at 0h, 12h, 24h, and 36h respectively. It can be seen that: in all groups, the sulfur content in the composite rubber gradually decreased with the increase of the extraction time. Among them, the blank group and Control Group 1 had the largest decrease, while Control Group 5 had the smallest decrease. This indicates that with the increase of the slow-release DTPD antioxidant, the migration rate of small molecule additives in the rubber matrix decreased, that is, the "blooming" phenomenon of rubber products was reduced, meeting the design expectations.

Claims

1. A preparation method of a slow-release DTPD antioxidant for reducing migration rate, characterized in that, It includes the following steps: S1. Prepare a mesoporous double-sphere template: S1-1. Prepare a dispersion: Add styrene, sodium styrene sulfonate, 4,4-dihydroxybenzophenone, and azobisisobutyronitrile into a 60 vol% methanol aqueous solution, and ultrasonically mix to obtain a dispersion; S1-2. Prepare a double-sphere template: Heat the dispersion from room temperature to 75 °C at a rate of 4 - 5 °C / min, and keep it warm for 5 - 6 h; then filter the completely reacted dispersion to obtain a filter cake, and wash the filter cake with methanol 3 - 5 times to obtain a double-sphere template; S1-3. Carbonize the double-sphere template: Add the double-sphere template into water to prepare a mixed solution with a concentration of 1 - 2 mol / L, then heat it at 200 °C for 2 - 3 h, after the reaction is complete, filter it to obtain a filter cake, and wash the filter cake with deionized water and ethanol alternately until the filtrate is colorless to obtain a carbonized double-sphere template; S1-4. In-situ generate calcium carbonate microspheres: Add calcium acetate into a 50 vol% ethanol aqueous solution, mix evenly, then add the carbonized double-sphere template, and ultrasonically disperse it at 30 °C for 5 - 6 h to obtain a mixed solution; Filter the mixed solution to obtain a filter cake, then wash the filter cake with deionized water 3 - 5 times, then dry it at 80 °C for 12 h, and finally heat it at a gradient temperature to obtain a mesoporous double-sphere template; S2. Prepare an antioxidant coupling agent: Prepare an antioxidant coupling agent by a one-step method using antioxidant PPDA and silane coupling agent KH-550 as raw materials; S3. Graft the mesoporous double-sphere template with the antioxidant coupling agent: Disperse the mesoporous double-sphere template prepared in S1 in a 95 vol% ethanol aqueous solution, then add the antioxidant coupling agent prepared in S2 and mix evenly, and obtain a slow-release DTPD antioxidant after the reaction is complete.

2. The preparation method of a slow-release DTPD antioxidant for reducing the migration rate as described in claim 1, characterized in that, In the step of preparing the dispersion in S1-1, the addition amounts of each component are: Let n be a magnification factor and n ∈ R+, then the addition amount of styrene is 2.5n mL, the addition amount of sodium styrene sulfonate is [0.0453, 0.046]n g; the addition amount of 4,4-dihydroxybenzophenone is [0.002, 0.03]n g; the addition amount of azobisisobutyronitrile is [0.0453, 0.046]n g; the addition amount of 60 vol% methanol aqueous solution is [10, 12]n mL.

3. The preparation method of a slow-release DTPD antioxidant for reducing the migration rate according to claim 1, characterized in that, In the step of in-situ generating calcium carbonate microspheres on the carbonized double-sphere template in S1-4, the addition amounts of each component are: Let n be a magnification factor and n ∈ R+, then the addition amount of calcium acetate is 0.1n mol, the addition amount of the carbonized double-sphere template is [300, 400]n mg; the addition amount in 50 vol% ethanol aqueous solution is [10, 12]n mL; The gradient temperature used for heating when preparing the mesoporous double-sphere template is: First, heat from room temperature to 400 °C at a rate of 2 - 3 °C / min, and keep it warm for 8 - 10 min; then heat from 400 °C to 500 °C at a rate of 1 - 2 °C / min, and keep it warm for 2 - 2.5 h; finally, cool it to room temperature with the furnace.

4. The preparation method of a slow-release DTPD antioxidant for reducing the migration rate as described in claim 1, characterized in that, The specific steps for preparing the antioxidant coupling agent in S2 are: S2-1, mix the antioxidant PPDA and the silane coupling agent KH-550 evenly, and then stir and heat in a 140℃ oil bath for 2-3h; S2-2, after the heating is completed, when the temperature of the reaction system drops to 60-70°C, add 95 vol% ethanol aqueous solution, and ultrasonically vibrate for 20-30 minutes to obtain an anti-aging coupling agent after alcoholysis; Let n be the rate coefficient and n∈R+, then the amount of the antioxidant PPDA added is [19,20] ng, the amount of the silane coupling agent KH-550 added is [21,22] n mL, and the amount of the 95 vol% ethanol aqueous solution added is [20,25] n mL.

5. The preparation method of a slow-release DTPD antioxidant for reducing the migration rate as described in claim 1, characterized in that, The specific steps of grafting the S3 mesoporous double-ball template with the anti-aging coupling agent are: S3-1, ultrasonically vibrate the mesoporous double-sphere template prepared in S1 in a 95 vol% ethanol aqueous solution for 20 to 30 minutes, fully disperse it, add the anti-aging coupling agent prepared in S2 and mix well to obtain a mixed solution; Let n be the rate coefficient and n∈R+, then the amount of the mesoporous double-sphere template added is [200,210]n mg, the amount of 95 vol% ethanol aqueous solution added is [100,150]n mL, and the amount of the anti-aging coupling agent added is [300,310]n mg. S3-2. The mixed solution prepared in S3-1 is heated with stirring at 80° C. for 4 to 4.5 hours, and a filter cake is obtained by suction filtration. The filter cake is washed with ethanol for 5 to 7 times, and finally the washed filter cake is dried to obtain a sustained-release DTPD antioxidant.

6. The preparation method of a slow-release DTPD antioxidant for reducing the migration rate as claimed in claim 1, characterized in that, The slow-release DTPD antioxidant is applied to prepare the tire sidewall.

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