Macromolecular antioxidant as well as preparation method and application thereof

Abstract

The invention discloses a macromolecular antioxidant as well as a preparation method and application thereof, and belongs to the technical field of rubber. According to the macromolecular antioxidant disclosed by the invention, through the arrangement of a strong-polarity secondary amino group and an active double-bond structure in a molecular structure, the migration degree of the macromolecular antioxidant when the macromolecular antioxidant is applied to a rubber material can be effectively reduced, meanwhile, high thermo-oxidative aging resistance can also be realized, and the components can also be compounded with an antioxidant or an anti-aging agent for a conventional rubber material for use, so that the macromolecular antioxidant has a good application prospect. The synergistic effect is generated, and the thermal stability of the rubber material is further improved.

Description

Technical Field

[0001] The invention relates to the field of rubber technology, and in particular to a macromolecular antioxidant and a preparation method and application thereof. Background Art

[0002] Rubber materials are widely used in fields such as automobiles, construction, and medical treatment due to their high elasticity and wear resistance. However, rubber materials are greatly affected by the external environment. In a hot and oxidative environment, rubber materials are very easy to age and their service life is significantly shortened. For this reason, antioxidants are often added during the preparation of existing rubber materials. However, existing rubber antioxidants are basically small molecule antioxidants, which are easy to migrate and volatilize in the rubber matrix. Not only are they inefficient in anti-oxidation, they may also cause environmental pollution. On the other hand, if an excessive amount of small molecule antioxidants is introduced, they may migrate to the surface of the rubber material and cause "frosting", which affects the appearance of the product.

[0003] To this end, people have tried to modify antioxidants by grafting and other methods, but they still have to take into account the high antioxidant properties and low migration and volatility of antioxidants for rubber materials. Summary of the invention

[0004] Based on the defects of the prior art, the purpose of the present invention is to provide a macromolecular antioxidant, which, through the arrangement of a strongly polar secondary amine group and an active double bond structure in the molecular structure, can not only effectively reduce the degree of migration when the rubber material is used, but also achieve high resistance to thermal oxidative aging. Moreover, this component can also be used in combination with conventional antioxidants or anti-aging agents for rubber materials to produce a synergistic effect, thereby further improving the thermal stability of the rubber material.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A macromolecular antioxidant, its molecular structure is as follows:

[0007]

[0008] Wherein, m≥1, and R is at least one of the following structures:

[0009]

[0010] Where n≥1.

[0011] Exemplarily, m and n can be any natural integer such as 1, 2, 3, 4, 5, etc., and the values ​​of m and n can be different.

[0012] The antioxidant of the present invention belongs to the type of macromolecular antioxidant based on the molecular structure composition. At the same time, the molecular structure of the antioxidant contains a highly polar secondary amine group and an active double bond structure. When applied to rubber materials, the active double bond structure in the antioxidant has the activity of auxiliary cross-linking, which can promote the cross-linking and bonding between the antioxidant and the rubber molecular network, thereby reducing the migration activity of the antioxidant in the rubber material. At the same time, the secondary amine group in the antioxidant can capture the free radicals generated by the rubber material in an aging-prone environment, thereby significantly improving the thermal oxidative aging resistance of the composite material. At the same time, due to the high compatibility of the functional group, when the antioxidant is applied to the rubber material, it can produce a synergistic effect with other antioxidants or anti-aging agents in the components, further improving the thermal oxidative aging resistance of the obtained product.

[0013] Another object of the present invention is to provide a method for preparing the macromolecular antioxidant, comprising the following steps:

[0014] Under an inert atmosphere, 2-mercaptobenzimidazole (MB) and the grafted product are ultrasonically mixed in a solvent, then stirred and heated to 60-70° C. under condensation reflux conditions, a catalyst is added and reacted for 20-25 hours, the temperature is lowered to 45-50° C., the solvent is removed, and the obtained solid is purified and dried to obtain the macromolecular antioxidant;

[0015] The grafted product is at least one of a bismaleimide derivative and an acrylate derivative.

[0016] Preferably, the molecular structure of the bismaleimide derivative is as follows:

[0017]

[0018] The R is at least one of the following structures:

[0019]

[0020] Where n≥1.

[0021] Preferably, the molecular structure of the acrylate derivative is any one of the following:

[0022]

[0023] When preparing the macromolecular antioxidant of the present invention, the mercapto group of 2-mercaptobenzimidazole and the double bond in the grafted derivative undergo a thiol-ene click reaction to form a macromolecular compound. The chemical reaction degree of the two raw materials is high, the operation is simple, and industrial-scale production can be achieved.

[0024] Preferably, the molar ratio of the thiol group in the 2-mercaptobenzimidazole to the double bond group in the graft is (1.4-1.6):1.

[0025] Preferably, the solvent is at least one of tetrahydrofuran, acetone, methanol and ethanol.

[0026] Preferably, the catalyst is at least one of azobisisobutyronitrile (AIBN), dibenzoyl peroxide (BPO), persulfate, hydrogen peroxide-ferrous salt mixture, N,N-dimethylaminopyridine (DMAP), triethylamine (TEA), and 4-pyrrolidinopyridine (PPY).

[0027] More preferably, when the grafted material is a bismaleimide derivative, the catalyst is triethylamine; and when the grafted material is an acrylate derivative, the catalyst is azobisisobutyronitrile.

[0028] The use of the above preferred catalyst types to catalyze the grafted product can result in a higher degree of reaction and less unreacted raw material impurities.

[0029] Preferably, the mass ratio of the catalyst to the grafted material is (0.1-0.15):1.

[0030] Preferably, the purification is carried out by washing with a polar solvent, and the polar solvent is at least one of toluene, methanol, ethanol, ether, acetone and ethyl acetate.

[0031] Another object of the present invention is to provide use of the macromolecular antioxidant in the preparation of rubber materials.

[0032] Another object of the present invention is to provide an EPDM rubber composite material, comprising the following raw materials in parts by weight:

[0033] 100 parts of EPDM rubber, 0.1-5 parts of macromolecular antioxidant, 5-10 parts of zinc oxide, 1-2 parts of stearic acid, 0-7 parts of antioxidant, 200-600 parts of thermal conductive filler, 20-40 parts of reinforcing filler, 10-50 parts of softener, 0.5-2 parts of coupling agent, 2-5 parts of vulcanizer and 0.5-2 parts of vulcanizing agent.

[0034] When the macromolecular antioxidant of the present invention is used in the processing of composite materials of EPDM rubber system, based on its efficient rubber cross-linking and antioxidant properties, the heat-oxidative aging performance of milk of the product can be greatly improved, and other added antioxidant and anti-aging components in the product can be coordinated. After the obtained product is subjected to heat-oxidative treatment at 180°C for 168 hours, the mechanical property change rate can be maintained within 40%. At the same time, under the formula, the thermal conductivity of the product is not less than 0.8 W·m -1 ·K -1 The tensile strength is not less than 8.6MPa, the elongation at break is not less than 209%, and the performance is very excellent.

[0035] Preferably, the antioxidant is at least one of 2-mercaptobenzimidazole (MB), 2-mercaptobenzimidazole zinc salt (MBZ), 2-mercaptomethylbenzimidazole zinc salt (MMBZ), 2,2,4-trimethyl-1,2-dihydroquinoline polymer (RD), 4,4-di(phenylisopropyl)diphenylamine (445), and N,N-di-n-butyldithiocarbamate nickel (NBC).

[0036] The macromolecular antioxidant of the present invention can not only be compounded and synergistically formulated with the raw material MB required for preparation, but also, based on its special anti-oxidation and anti-precipitation mechanism, it can also be compounded and used with various other anti-aging and antioxidant additives on the market with similar molecular structures or similar performance effects. It has been verified by the inventor that in the EPDM rubber composite material of the present invention, the components of the antioxidant system formed therein have a synergistic effect.

[0037] Preferably, the thermally conductive filler is at least one of aluminum oxide, boron nitride and aluminum nitride.

[0038] Preferably, the reinforcing filler is at least one of calcined clay, kaolin and white carbon black.

[0039] Preferably, the softener is at least one of white oil, paraffin oil and fatty oil.

[0040] Preferably, the coupling agent is a silane coupling agent, more preferably at least one of γ-methacryloxypropyltrimethoxysilane, vinyltriethoxysilane, bis(triethoxysilylpropyl)disulfide, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, and octyltriethoxysilane.

[0041] Preferably, the vulcanizing agent is at least one of dicumyl peroxide (DCP), di-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0042] Preferably, the vulcanizing agent is at least one of triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), N,N′-m-phenylene bismaleimide (HVA-2), trimethylolpropane triacrylate (TMPTA), trialkyl methyl propane trimethacrylate (TMPTMA), and rubber crosslinking agent VP-4.

[0043] Another object of the present invention is to provide a method for preparing the EPDM rubber composite material, comprising the following steps:

[0044] (1) EPDM rubber, zinc oxide, stearic acid, antioxidant and macromolecular antioxidant are mixed in an internal mixer and kneaded at 70-80° C. for 3-5 minutes, and then thermal conductive filler and reinforcing filler are added alternately in batches. After the mixture is uniformly kneaded, a softener is added and kneaded for 8-10 minutes, and the rubber is discharged to obtain a rubber mixture I;

[0045] (2) placing the rubber mix I in an open mixer for mixing, and after mixing until the rubber mix wraps around the roller, sequentially adding a coupling agent, a vulcanizing agent, and a co-vulcanizing agent and continuing to mix until the rubber mix is ​​uniform, placing the sheet, and allowing the sheet to stand to obtain a rubber mix II;

[0046] (3) placing the rubber mix II into a mold for hot pressing to obtain the EPDM rubber composite material.

[0047] The preparation operation steps of the EPDM rubber composite material of the present invention are simple, the requirements on equipment are low, and industrial-scale production can be realized.

[0048] Preferably, the rotation speed of the internal mixer during mixing in step (1) is 60 to 80 rpm.

[0049] Preferably, the mixing mill in step (2) is a double-roll mill with a roller distance of 1.8 to 2.2 mm and a roller temperature of 30 to 50°C.

[0050] Preferably, the temperature during hot pressing in step (3) is 160-180° C., the pressure is 10-15 MPa, and the time is 15-20 min.

[0051] Another object of the present invention is to provide an application of the EPDM rubber composite material in the preparation of high-temperature resistant components. Preferably, the high-temperature resistant components include automotive sealing strips, automotive brake hoses, and charging cable outer tubes.

[0052] The EPDM rubber composite material of the present invention has ideal appearance performance and mechanical performance, and excellent heat-oxidative aging resistance, and is therefore very suitable for the preparation of the above-mentioned high-temperature resistant devices that often need to be used in a high-heat oxygen environment.

[0053] The beneficial effect of the present invention is that the present invention provides a macromolecular antioxidant, which can effectively reduce the degree of migration when the rubber material is used, and can also achieve high resistance to thermal oxidative aging through the arrangement of a strong polar secondary amine group and an active double bond structure in the molecular structure. Moreover, the component can also be compounded with conventional antioxidants or anti-aging agents for rubber materials to produce a synergistic effect, thereby further improving the thermal stability of the rubber material. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1The infrared spectrum of the macromolecular antioxidant (labeled as reactive macromolecular antioxidant in the figure) prepared in Example 1 of the present invention and its preparation raw materials;

[0055] Figure 2 This is the NMR spectrum of the macromolecular antioxidant prepared in Example 1 of the present invention and its preparation raw materials. DETAILED DESCRIPTION

[0056] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention, unless otherwise specified, are all commonly used common reagents and instruments.

[0057] Example 1

[0058] An embodiment of the macromolecular antioxidant and its preparation method and application of the present invention, the preparation method of the macromolecular antioxidant comprises the following steps:

[0059] Under nitrogen atmosphere, 53.26mmol MB and 17.75mmol grafted product were ultrasonically mixed in 150mL tetrahydrofuran, and then transferred to a three-necked flask equipped with a reflux condenser and a magnetic stirrer, stirred and heated to 65°C under condensation reflux conditions, and 0.636g of catalyst TEA was added, and the resulting mixed solution changed from light yellow to reddish brown. After reacting for 24h, the temperature was lowered to 45°C, and the resulting mixed solution was rotary evaporated to remove the solvent. The resulting solid was washed and purified with methanol and toluene three times, respectively, and dried at 70°C for 24h to obtain a reddish brown macromolecular antioxidant.

[0060] The grafted product is a bismaleimide derivative, and the molecular structure of the bismaleimide derivative is as follows:

[0061]

[0062] The structure of R is as follows:

[0063]

[0064] That is, the grafted substance is N,N'-(4,4'-methylenediphenyl)bismaleimide.

[0065] The macromolecular antioxidant is applied to prepare EPDM rubber composite materials, and the weight proportions of the raw materials are shown in Table 1.

[0066] Among them, EPDM rubber is produced by Jilin Petrochemical with the brand name J4045;

[0067] The thermally conductive filler is alumina with a commercially available particle size range of 30 to 50 μm;

[0068] The reinforcing filler is commercially available precipitated silica with a particle size range of 70 to 100 nm;

[0069] The softener was commercially available paraffin oil;

[0070] The coupling agent is commercially available silane coupling agent KH570;

[0071] The vulcanizing agent is DCP;

[0072] The vulcanizing agent is TAIC.

[0073] The preparation method of the EPDM rubber composite material is:

[0074] (1) EPDM rubber, zinc oxide, stearic acid, antioxidant and macromolecular antioxidant are mixed in an internal mixer and kneaded at 70-80° C. and 60-80 rpm for 3-5 min, then thermal conductive filler and reinforcing filler are added alternately in batches, softener is added after mixing evenly, and kneaded for 8-10 min, and rubber is discharged to obtain rubber mix I;

[0075] (2) The rubber mix I is placed in a two-roll open mill with a roller spacing of 2 mm and a roller temperature of 30-50° C. and mixed for 2-3 minutes. After mixing until the rollers are wrapped, a coupling agent, a vulcanizing agent and a co-vulcanizing agent are added in sequence and mixed until uniform. The left and right cutters are used 5 times each, and the triangular package is made 10 times and thinned 5 times before being unrolled and left to stand for 12 hours to obtain the rubber mix II;

[0076] (3) placing the rubber mix II into a mold, and then hot pressing it on a flat vulcanizer at 170° C. and 10 MPa for 15 min to obtain the EPDM rubber composite material.

[0077] Example 2

[0078] An embodiment of the macromolecular antioxidant and its preparation method and application of the present invention is different from Embodiment 1 only in that the preparation method of the macromolecular antioxidant comprises the following steps:

[0079] Under nitrogen atmosphere, 53.26mmol MB and 17.75mmol grafted product were ultrasonically mixed in 150mL tetrahydrofuran, and then transferred to a three-necked flask equipped with a reflux condenser and a magnetic stirrer, stirred and heated to 65°C under condensation reflux conditions, and 0.476g of catalyst TEA was added, and the resulting mixed solution changed from light yellow to reddish brown. After reacting for 24 hours, the temperature was lowered to 45°C, and the resulting mixed solution was rotary evaporated to remove the solvent. The resulting solid was washed and purified three times with methanol and toluene, respectively, and dried at 70°C for 24 hours to obtain a reddish brown macromolecular antioxidant.

[0080] The grafted product is a bismaleimide derivative, and the molecular structure of the bismaleimide derivative is as follows:

[0081]

[0082] The structure of R is as follows:

[0083]

[0084] Example 3

[0085] An embodiment of the macromolecular antioxidant and its preparation method and application of the present invention is different from Embodiment 1 only in that the preparation method of the macromolecular antioxidant comprises the following steps:

[0086] Under nitrogen atmosphere, 53.26mmol MB and 11.84mmol grafted product were ultrasonically mixed in 150mL tetrahydrofuran, and then transferred to a three-necked flask equipped with a reflux condenser and a magnetic stirrer, stirred and heated to 65°C under condensation reflux conditions, and 0.391g catalyst TEA was added, and the resulting mixed solution changed from light yellow to reddish brown. After reacting for 24h, the temperature was lowered to 45°C, and the resulting mixed solution was rotary evaporated to remove the solvent. The resulting solid was washed and purified with methanol and toluene three times, respectively, and dried at 70°C for 24h to obtain a reddish brown macromolecular antioxidant.

[0087] The grafted product is an acrylate derivative, and the molecular structure of the acrylate derivative is as follows:

[0088]

[0089] Example 4

[0090] An embodiment of the macromolecular antioxidant and its preparation method and application of the present invention is different from Embodiment 1 only in that the preparation method of the macromolecular antioxidant comprises the following steps:

[0091] Under nitrogen atmosphere, 53.26mmol MB and 17.75mmol grafted product were ultrasonically mixed in 150mL tetrahydrofuran, and then transferred to a three-necked flask equipped with a reflux condenser and a magnetic stirrer, stirred and heated to 65°C under condensation reflux conditions, and 0.437g catalyst TEA was added, and the resulting mixed solution changed from light yellow to reddish brown. After reacting for 24 hours, the temperature was lowered to 45°C, and the resulting mixed solution was rotary evaporated to remove the solvent. The resulting solid was washed and purified three times with methanol and toluene, respectively, and dried at 70°C for 24 hours to obtain a reddish brown macromolecular antioxidant.

[0092] The grafted product is an acrylate derivative, and the molecular structure of the acrylate derivative is as follows:

[0093]

[0094] Embodiments 5 to 8

[0095] An embodiment of the macromolecular antioxidant and its preparation method and application of the present invention is different from Example 1 only in that the raw materials and weight portions of the EPDM rubber composite material are different.

[0096] A macromolecular antioxidant and a preparation method and application thereof, which are different from Example 1 only in that the raw material selection and weight proportion of the EPDM rubber composite material are different.

[0097] As shown in Table 1;

[0098] The antioxidant 1 is commercially available MB;

[0099] Antioxidant 2 was commercially available MMBZ;

[0100] Antiaging agent 3 is a homemade product, and the preparation method is as follows:

[0101] Under nitrogen atmosphere, 53.26 mmol MB and 17.75 mmol grafted product were ultrasonically mixed in 150 mL tetrahydrofuran, and then transferred to a three-necked flask equipped with a reflux condenser and a magnetic stirrer. After stirring at room temperature for 24 h under condensation reflux conditions, the resulting mixture was rotary evaporated to remove the solvent. The resulting solid was washed and purified three times with methanol and toluene, respectively, and dried at 70°C for 24 h to obtain a reddish-brown macromolecular antioxidant.

[0102] The grafted product is a bismaleimide derivative, and the molecular structure of the bismaleimide derivative is as follows:

[0103]

[0104] The structure of R is as follows:

[0105]

[0106] That is, the grafted substance is N,N'-(4,4'-methylenediphenyl)bismaleimide;

[0107] Antioxidant 4 is commercially available antioxidant 412S.

[0108] Table 1

[0109]

[0110]

[0111] Table 2

[0112]

[0113] Effect Example 1

[0114] In order to verify the performance of the EPDM rubber composite material of the present invention, the vulcanized products obtained in each embodiment and comparative example were subjected to the following tests after standing for 18 hours:

[0115] (1) Hardness test: Test the Shore A hardness of the product according to GB / T 531.1-2008;

[0116] (2) Tensile strength and elongation at break test: tested according to GB / T 528-2009, tensile speed 250 mm / min;

[0117] (3) Thermal conductivity test: Tested according to GB / T 11205-2009;

[0118] (4) Thermal oxidative aging performance test: According to GB / T 3512-2001, each product was placed in an oven with air circulation at 135°C, 156°C and 180°C for 168 h, and the tensile strength and elongation at break of the product before and after standing were tested according to step (2). The change rates of the tensile strength and elongation at break were calculated. If the product became brittle after standing, the change rate was not counted.

[0119] (5) Thermal elongation performance test: According to GB / T 42279-2022, the maximum elongation of the product under load and the permanent elongation after cooling are tested. The test conditions are 250°C, 15min, 20N / cm 2 ;

[0120] (6) Appearance performance test: After standing in an oven at 180° C. in step (4), observe the surface of the product to see if “frosting” occurs.

[0121] The test results are shown in Tables 3 and 4.

[0122] Table 3

[0123]

[0124] Table 4

[0125]

[0126] It can be clearly seen from the results that the EPDM rubber composite material prepared by using the macromolecular antioxidant of the present invention has ideal performance. Before the thermal oxidation aging treatment, the tensile strength can reach 8.5MPa, the elongation at break can reach 209% and above, the hardness can reach above 80A, and the thermal conductivity can reach 0.85Wm -1 K -1And above; in terms of thermal extension performance, the maximum elongation of the product under load reaches 5-10%, and the permanent elongation after cooling can be maintained at 0-2.5%; after thermal oxidative aging treatment, at the highest temperature of 180°C, the change rate of the product's tensile strength and elongation at break can still be maintained within 40%, which fully demonstrates that the product has good thermal oxidative aging resistance. At the same time, after thermal oxidative aging treatment, no obvious antioxidant precipitation appears on the product surface.

[0127] In contrast, the product of Comparative Example 1 does not introduce any antioxidant or anti-aging additives at all. The product becomes brittle after thermal oxidative aging treatment at a relatively low temperature, and has poor thermal oxidative aging resistance. The products of Comparative Examples 2 and 3 only introduce general antioxidants MB or MMBZ. It can be seen that although these two ingredients can improve the thermal oxidative aging resistance of the product to a certain extent, the degree of improvement is low, and the product still becomes brittle at 180°C.

[0128] At the same time, according to Example 1 and Examples 5 and 6, it can be seen that when the macromolecular antioxidant is compounded with the existing antioxidants MB and MMBZ, the heat-oxidative aging resistance of the product is further improved. When the treatment condition is the highest temperature of 180°C, the change rate of the tensile strength and elongation at break of the product can still be maintained within 30%. In the products of Comparative Examples 6 to 8, although the total amount of antioxidant and anti-aging components has not changed compared with Examples 5 and 6 (both are 10 parts), whether MB or MMBZ is used alone, or the two are used in combination similar to Examples 5 and 6, the change rate of the product after heat-oxidative aging treatment is high, and the change rate after treatment at 180°C reaches more than 40%, which fully illustrates that the macromolecular antioxidant of the present invention has a synergistic effect with MB and MMBZ in the EPDM rubber composite material, and the existing common antioxidant components, even if the dosage is increased or introduced in a multi-phase compounding manner, do not significantly improve the heat-oxidative aging resistance of the product, and the compounding of conventional antioxidants does not show obvious synergistic effects.

[0129] The macromolecular antioxidant of the present invention can achieve high antioxidant properties and low migration, but this effect is only achieved after MB and the grafted product undergo thiol-ene click chemistry reaction. The macromolecular antioxidant obtained in Example 1 and the corresponding raw materials were subjected to infrared testing (Bruker TENSOR 27 Fourier transform infrared spectrometer testing, wave number range 4000~400cm -1 , resolution 4cm -1 ; Scanning stacking times is 32 times) and NMR test (DMSO -6 Solvent, room temperature, BRUKER AVANCE400 spectrometer test), the results are as follows Figure 1 and Figure 2As shown, the test results clearly show that the two raw materials are combined through obvious chemical reactions and obtain corresponding functional group structures. If the two substances are simply mixed without adding a catalyst for reaction, as shown in Comparative Example 4, the effect of the product when further applied to EPDM rubber composite materials is very similar to that of MB and MMBZ, indicating that the two raw materials do not actually have sufficient antioxidant properties if they are simply mixed.

[0130] In addition, the low mobility of the macromolecular antioxidant of the present invention is also unmatched by the existing conventional small molecule antioxidants. As shown in Comparative Example 5, after the macromolecular antioxidant of the present invention is replaced by antioxidant 412S, not only the thermal oxidation aging resistance of the product is weakened, but also "frosting" phenomenon appears on the surface of the product after thermal oxidation aging treatment. However, the product of the present invention does not have this situation after use, and has excellent comprehensive performance.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the present invention.

Claims

1. A macromolecular antioxidant, characterized in that: Its molecular structure is as follows: Wherein m≥1, and R is at least one of the following structures: Where n≥1.

2. The method for preparing the macromolecular antioxidant according to claim 1, characterized in that: The following steps are involved: Under an inert atmosphere, 2-mercaptobenzimidazole and the grafted product are ultrasonically mixed in a solvent, then stirred and heated to 60-70° C. under condensation reflux conditions, a catalyst is added and reacted for 20-25 hours, the temperature is lowered to 45-50° C., the solvent is removed, and the obtained solid is purified and dried to obtain the macromolecular antioxidant; The grafted product is at least one of a bismaleimide derivative and an acrylate derivative.

3. The method for preparing the macromolecular antioxidant according to claim 2, characterized in that: The molecular structure of the bismaleimide derivative is as follows: The R is at least one of the following structures: Where n≥1.

4. The method for preparing the macromolecular antioxidant according to claim 2, characterized in that: The molecular structure of the acrylate derivative is any one of the following:

5. The method for preparing the macromolecular antioxidant according to claim 2, characterized in that: The molar ratio of the thiol group in the 2-mercaptobenzimidazole to the double bond group of the graft is (1.4-1.6):

1.

6. The method for preparing the macromolecular antioxidant according to claim 2, characterized in that: Include at least one of the following (a) to (c): (a) the solvent is at least one of tetrahydrofuran, acetone, methanol and ethanol; (b) the catalyst is at least one of azobisisobutyronitrile, dibenzoyl peroxide, persulfate, hydrogen peroxide-ferrous salt mixture, N,N-dimethylaminopyridine, triethylamine, and 4-pyrrolidinopyridine; (c) The mass ratio of the catalyst to the grafted material is (0.1-0.15):

1.

7. Use of the macromolecular antioxidant as claimed in claim 1 in the preparation of rubber materials.

8. An EPDM rubber composite material, characterized in that: The preparation comprises the following raw materials in parts by weight: 100 parts of EPDM rubber, 0.1-5 parts of the macromolecular antioxidant according to claim 1, 5-10 parts of zinc oxide, 1-2 parts of stearic acid, 0-7 parts of antioxidant, 200-600 parts of thermal conductive filler, 20-40 parts of reinforcing filler, 10-50 parts of softener, 0.5-2 parts of coupling agent, 2-5 parts of vulcanizing agent and 0.5-2 parts of vulcanizing agent; preferably, the antioxidant is at least one of 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, 2-mercaptomethylbenzimidazole zinc salt, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 4,4-di(phenylisopropyl)diphenylamine and N,N-di-n-butyldithiocarbamate nickel.

9. The method for preparing the EPDM rubber composite material according to claim 8, characterized in that: The following steps are involved: (1) EPDM rubber, zinc oxide, stearic acid, antioxidant and macromolecular antioxidant are mixed in an internal mixer and kneaded at 70-80° C. for 3-5 minutes, and then thermal conductive filler and reinforcing filler are added alternately in batches. After the mixture is uniformly kneaded, a softener is added and kneaded for 8-10 minutes, and the rubber is discharged to obtain a rubber mixture I; (2) placing the rubber mix I in an open mixer for mixing, and after mixing until the rubber mix wraps around the roller, sequentially adding a coupling agent, a vulcanizing agent, and a co-vulcanizing agent and continuing to mix until the rubber mix is ​​uniform, placing the sheet, and allowing the sheet to stand to obtain a rubber mix II; (3) placing the rubber mix II into a mold for hot pressing to obtain the EPDM rubber composite material.

10. Use of the EPDM rubber composite material as claimed in claim 8 in the preparation of high temperature resistant components; preferably, the high temperature resistant components include automotive sealing strips, automotive brake hoses, and charging cable outer tubes.

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