A preparation process of tear-resistant and high-temperature resistant EPDM rubber

Abstract

The invention relates to the technical field of EPDM rubber, and discloses a preparation process of tear-resistant and high-temperature resistant EPDM rubber, wherein the EPDM rubber is mixed in an internal mixer, and then zinc oxide, hydroxyl flame retardant-modified aramid fiber, maleic anhydride-grafted EPDM rubber, and stearic acid are added to remove the glue, and then the rubber is mixed with an antioxidant, an accelerator, and sulfur in a double-roll open mill to form a triangular package, a thin pass, a lower sheet mixing, and vulcanization to obtain a modified tear-resistant and high-temperature resistant EPDM rubber; in the invention, hydroxyl, DOPO, and pyrimidine groups are introduced on the surface of the aramid fiber to form a nitrogen-phosphorus flame retardant, which significantly improves the limiting oxygen index of the EPDM rubber and has better flame retardant properties. At the same time, a maleic anhydride-grafted EPDM rubber compatibilizer is added to improve the compatibility of the aramid fiber with the EPDM rubber matrix, and enhance the mechanical properties and high-temperature resistance of the EPDM rubber.

Description

Technical Field

[0001] The invention relates to the technical field of EPDM rubber, in particular to a preparation process of tear-resistant and high-temperature resistant EPDM rubber. Background Art

[0002] EPDM rubber has good toughness, weather resistance, aging resistance and other high performance, and is widely used in wires and cables, household appliances, etc. However, EPDM rubber has poor mechanical strength, flame retardancy, high temperature resistance and other properties, which limits the application of EPDM rubber in high temperature resistant flame retardant materials, etc. Modifying EPDM rubber with high-performance fibers can effectively improve its comprehensive properties such as high temperature resistance and mechanics.

[0003] Aromatic polyamide fiber (aramid fiber) has strong high temperature resistance, high mechanical strength, high modulus, and certain flame retardant properties. It has broad application prospects in polymer materials such as epoxy resin and rubber. Surface modification of aramid fiber, such as cold plasma treatment, irradiation grafting, etc., can introduce functional groups or polymers on its surface to improve the compatibility between aramid fiber and material matrix, so that aramid fiber can have better reinforcement effect. Chinese patent CN111118905B discloses a surface modification method of aramid fiber, which can significantly improve the bonding strength between aramid fiber and rubber matrix by pre-treating the surface of aramid fiber and functionalizing graphene oxide. However, this patent does not improve the flame retardant properties of rubber materials. Summary of the invention

[0004] The invention solves the problems that the compatibility of aramid fiber with EPDM rubber is poor, and the compatibility, flame retardancy, tear strength and other properties of EPDM rubber are not good.

[0005] The technical scheme provided by the present invention is: a preparation process of tear-resistant and high-temperature resistant EPDM rubber: the EPDM rubber is internally kneaded in an internal mixer, and then zinc oxide, hydroxyl flame retardant modified aramid fiber, maleic anhydride grafted EPDM rubber, and stearic acid are added to perform rubber removal to obtain a masterbatch; then the masterbatch is triangularly packaged, thinned, and sheeted with an antioxidant, an accelerator, and sulfur in a double-roll open mill, and the mixture is cooled and finally placed in a flat vulcanizer for vulcanization to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0006] The preparation method of hydroxyl flame retardant modified aramid fiber is as follows: the aramid fiber is washed with ethanol and water in sequence, dried, and then placed in a plasma generator for air cold plasma treatment; finally, the aramid fiber is placed in an ethanol solution containing allyl hydroxy DOPO pyrimidine flame retardant, a grafting reaction is carried out in a nitrogen atmosphere, and after filtering, the aramid fiber is washed with xylene and acetone in sequence, and dried to obtain the hydroxyl flame retardant modified aramid fiber.

[0007] The structural formula of allyl hydroxy DOPO pyrimidine flame retardant is formula (I):

[0008]

[0009] The amount of EPDM rubber is 100 parts by weight, the amount of hydroxy flame retardant modified aramid fiber is 5-20 parts by weight, and the amount of maleic anhydride grafted EPDM rubber is 1.2-5 parts by weight.

[0010] The power of the plasma generator is 200-250W, the air pressure in the reaction chamber is 15-25Pa, and the processing time is 5-10min.

[0011] Wherein, the mass concentration of the allyl hydroxy DOPO pyrimidine flame retardant in the ethanol solution is (30-150) g / L.

[0012] The grafting reaction is carried out at 50-70° C. for 1-3 hours.

[0013] Among them, the preparation process of allyl hydroxy DOPO pyrimidine flame retardant is:

[0014] S1. Add 100 parts by weight of 5-pyrimidinamine (CAS registration number 591-55-9) and 120-135 parts by weight of 4-hydroxybenzaldehyde (CAS registration number 123-08-0) to ethanol, dropwise add 6-10 parts by weight of glacial acetic acid, react at 60-75° C. for 3-5 hours, concentrate the solution, wash with water, and recrystallize the product in ethyl acetate to obtain intermediate A. The reaction formula is as follows:

[0015]

[0016] S2. Add 100 parts by weight of intermediate A and 105-130 parts by weight of DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, CAS registration number 35948-25-5) to ethanol, and react at 75-80° C. for 3-5 hours. During the reaction, condense and reflux, concentrate the solution, wash the product with acetone, and recrystallize it in ethanol to obtain intermediate B. The reaction formula is as follows:

[0017]

[0018] S3, add 100 parts by weight of intermediate B, 32-40 parts by weight of propylene bromide, and 46-60 parts by weight of catalyst to acetonitrile, react at 60-75°C for 8-12 hours, concentrate the solution, wash the product with water, and recrystallize it in ethyl acetate to obtain allyl hydroxy DOPO pyrimidine flame retardant. The reaction formula is:

[0019]

[0020] Wherein, the catalyst is potassium carbonate or sodium carbonate.

[0021] The technical effect of the present invention is that the aramid fiber of the present invention is treated with air cold plasma and grafted with allyl hydroxyl DOPO pyrimidine flame retardant to achieve the grafting of polymer flame retardant containing hydroxyl, DOPO and pyrimidine groups on the surface of the aramid fiber.

[0022] The present invention adds hydroxy flame retardant modified aramid fiber and maleic anhydride grafted EPDM rubber to the EPDM rubber, and the aramid fiber itself has certain flame retardant properties. In addition, DOPO and pyrimidine groups are introduced on the fiber surface to form a nitrogen-phosphorus flame retardant. When burned, DOPO is pyrolyzed to produce phosphoric acid substances, which can promote the dehydration of the matrix into carbon. The nitrogen-containing pyrimidine group is pyrolyzed at high temperature to produce non-flammable gases such as nitrogen, thereby playing a good synergistic flame retardant role with the aramid fiber, significantly improving the limiting oxygen index of the EPDM rubber, and having better flame retardant properties.

[0023] The aramid fiber of the present invention has the characteristics of high strength, high modulus, and strong high temperature resistance. After being grafted with the allyl hydroxy DOPO pyrimidine flame retardant, a large number of hydroxyl groups are introduced on the fiber surface, which can react with the anhydride group of the maleic anhydride grafted EPDM rubber, so that the maleic anhydride grafted EPDM rubber can be used as a compatibilizer to improve the compatibility of the aramid fiber with the EPDM rubber matrix, and the dispersion in the rubber group is very good, so that the aramid fiber can significantly enhance the mechanical properties and high temperature resistance of the EPDM rubber, and show higher tensile properties and tear strength. After being heat treated at 120°C for 72 hours, the mechanical strength decreases at a low level, and the tensile properties and tear strength retention rate are high. DETAILED DESCRIPTION

[0024] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0025] The EPDM rubber of the present invention is of the brand TER 4436. The maleic anhydride grafted EPDM rubber is of the brand DY-306. The aramid fiber is aramid 1414 short fiber with an average length of 3 mm.

[0026] Example 1

[0027] (1) Add 2 g of 5-pyrimidinamine and 2.4 g of 4-hydroxybenzaldehyde to 60 mL of ethanol, add 0.12 g of glacial acetic acid dropwise, react at 75° C. for 3 h, concentrate the solution, wash with water, and recrystallize the product in ethyl acetate to obtain intermediate A.

[0028] (2) Add 5 g of intermediate A and 6.5 g of DOPO to 80 mL of ethanol and react at 75° C. for 3 h. During the reaction, condensation reflux is performed and the solution is concentrated. The product is washed with acetone and recrystallized in ethanol to obtain intermediate B.

[0029] (3) Add 5 g of intermediate B, 2 g of propylene bromide, and 2.3 g of catalyst potassium carbonate to 60 mL of acetonitrile, react at 75° C. for 8 h, concentrate the solution, wash the product with water, and recrystallize it in ethyl acetate to obtain an allyl hydroxy DOPO pyrimidine flame retardant.

[0030] (4) The aramid fiber was washed with ethanol and water in turn, dried, and then placed in a plasma generator. The power of the plasma generator was controlled to be 200 W, the air pressure in the reaction chamber was 15 Pa, and the air cold plasma treatment was performed for 10 minutes. Finally, the aramid fiber was placed in an ethanol solution of allyl hydroxy DOPO pyrimidine flame retardant with a mass concentration of 30 g / L, and the grafting reaction was carried out at 50°C in a nitrogen atmosphere for 2 hours. After filtering, the fiber was washed with xylene and acetone in turn, and dried to obtain hydroxyl flame retardant modified aramid fiber.

[0031] (5) 1000 g of EPDM rubber was mixed in an internal mixer for 3 min at a roller temperature of 125°C, and then 12 g of zinc oxide, 50 g of hydroxyl flame retardant modified aramid fiber, 12 g of maleic anhydride grafted EPDM rubber, and 15 g of stearic acid were added to perform rubber removal to obtain a masterbatch; the masterbatch was then mixed with 15 g of antioxidant 2-mercaptobenzopyrimidine, 10 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 20 g of sulfur in a double-roll open mill, triangularly packaged 5 times, thinned 8 times, and mixed for 10 min. The mixture was cooled and finally placed in a flat vulcanizer for vulcanization at 170°C and a pressure of 10 MPa to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0032] Example 2

[0033] (1) Add 2 g of 5-pyrimidinamine and 2.7 g of 4-hydroxybenzaldehyde to 80 mL of ethanol, add 0.2 g of glacial acetic acid dropwise, react at 60° C. for 5 h, concentrate the solution, wash with water, and recrystallize the product in ethyl acetate to obtain intermediate A.

[0034] (2) Add 5 g of intermediate A and 5.25 g of DOPO to 70 mL of ethanol, and react at 80° C. for 5 h. During the reaction, condensation reflux is performed, and the solution is concentrated. The product is washed with acetone and recrystallized in ethanol to obtain intermediate B.

[0035] (3) Add 5 g of intermediate B, 1.6 g of propylene bromide, and 3 g of catalyst sodium carbonate to 50 mL of acetonitrile, react at 60° C. for 12 h, concentrate the solution, wash the product with water, and recrystallize it in ethyl acetate to obtain an allyl hydroxy DOPO pyrimidine flame retardant.

[0036] (4) The aramid fiber was washed with ethanol and water in turn, dried, and then placed in a plasma generator. The power of the plasma generator was controlled to be 200 W, the air pressure in the reaction chamber was 25 Pa, and the air cold plasma treatment was performed for 10 minutes. Finally, the aramid fiber was placed in an ethanol solution of allyl hydroxy DOPO pyrimidine flame retardant with a mass concentration of 70 g / L, and the grafting reaction was carried out at 50°C in a nitrogen atmosphere for 3 hours. After filtering, the fiber was washed with xylene and acetone in turn, and dried to obtain hydroxyl flame retardant modified aramid fiber.

[0037] (5) Mix 1000 g of EPDM rubber in an internal mixer for 3 min at a roller temperature of 125°C, then add 8 g of zinc oxide, 100 g of hydroxyl flame retardant modified aramid fiber, 25 g of maleic anhydride grafted EPDM rubber, and 15 g of stearic acid to obtain a masterbatch; then mix the masterbatch with 10 g of antioxidant 2-mercaptobenzopyrimidine, 12 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 26 g of sulfur in a double-roll open mill, roll into triangles 5 times, pass through 8 times, and mix for 10 min. The mixture is cooled and finally placed in a flat vulcanizer for vulcanization at 170°C and 10 MPa to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0038] Example 3

[0039] (1) The aramid fiber was washed with ethanol and water in turn, dried, and then placed in a plasma generator, the power of the plasma generator was controlled to be 250 W, the air pressure in the reaction chamber was 15 Pa, and air cold plasma treatment was performed for 5 minutes; finally, the aramid fiber was placed in an ethanol solution of allyl hydroxy DOPO pyrimidine flame retardant (prepared according to the process of Example 1) with a mass concentration of 110 g / L, and a grafting reaction was carried out at 60° C. in a nitrogen atmosphere for 3 hours. After filtering, the fiber was washed with xylene and acetone in turn, and dried to obtain hydroxyl flame retardant modified aramid fiber.

[0040] (2) 1000 g of EPDM rubber was mixed in an internal mixer for 3 min at a roller temperature of 125°C, and then 10 g of zinc oxide, 150 g of hydroxyl flame retardant modified aramid fiber, 38 g of maleic anhydride grafted EPDM rubber, and 12 g of stearic acid were added to perform rubber removal to obtain a masterbatch; the masterbatch was then mixed with 12 g of antioxidant 2-mercaptobenzopyrimidine, 15 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 26 g of sulfur in a double-roll open mill, triangularly packaged 5 times, thinned 8 times, and mixed for 10 min, cooled, and finally placed in a flat vulcanizer at 170°C and 10 MPa pressure for vulcanization to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0041] Example 4

[0042] (1) The aramid fiber was washed with ethanol and water in turn, dried, and then placed in a plasma generator, the power of the plasma generator was controlled to be 250 W, the air pressure in the reaction chamber was 25 Pa, and air cold plasma treatment was performed for 8 minutes; finally, the aramid fiber was placed in an ethanol solution of allyl hydroxy DOPO pyrimidine flame retardant (prepared according to the process of Example 1) with a mass concentration of 150 g / L, and a grafting reaction was carried out at 70° C. in a nitrogen atmosphere for 1 hour. After filtering, the fiber was washed with xylene and acetone in turn, and dried to obtain hydroxyl flame retardant modified aramid fiber.

[0043] (2) 1000 g of EPDM rubber was mixed in an internal mixer for 3 min at a roller temperature of 125°C, and then 8 g of zinc oxide, 200 g of hydroxyl flame retardant modified aramid fiber, 50 g of maleic anhydride grafted EPDM rubber, and 18 g of stearic acid were added to perform rubber removal to obtain a masterbatch; the masterbatch was then mixed with 15 g of antioxidant 2-mercaptobenzopyrimidine, 12 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 20 g of sulfur in a double-roll open mill, triangularly packaged 5 times, thinned 8 times, and mixed for 10 min, cooled, and finally placed in a flat vulcanizer at 170°C and 10 MPa pressure for vulcanization to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that no hydroxy flame retardant is added to modify the aramid fiber.

[0046] (1) 1000 g of EPDM rubber was mixed in an internal mixer for 3 min at a roller temperature of 125° C., and then 12 g of zinc oxide, 12 g of maleic anhydride grafted EPDM rubber, and 15 g of stearic acid were added to perform rubber removal to obtain a masterbatch; the masterbatch was then mixed with 15 g of antioxidant 2-mercaptobenzopyrimidine, 10 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 20 g of sulfur in a double-roll open mill, and triangularly packaged 5 times, thinned 8 times, and mixed for 10 min. The mixture was cooled and finally placed in a flat vulcanizer at 170° C. and 10 MPa to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 1 is that unmodified aramid fiber is added.

[0049] (1) 1000 g of EPDM rubber was mixed in an internal mixer for 3 min at a roller temperature of 125° C., and then 12 g of zinc oxide, 50 g of aramid fiber, 12 g of maleic anhydride grafted EPDM rubber, and 15 g of stearic acid were added to perform rubber removal to obtain a masterbatch; the masterbatch was then mixed with 15 g of antioxidant 2-mercaptobenzopyrimidine, 10 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 20 g of sulfur in a double-roll open mill, and triangularly packaged for 5 times, thinned for 8 times, and mixed for 10 min. The mixture was cooled and finally placed in a flat vulcanizer for vulcanization at 170° C. and 10 MPa to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0050] Comparative Example 3

[0051] The difference between this comparative example and Example 1 is that maleic anhydride grafted EPDM rubber is not added.

[0052] (1) 1000 g of EPDM rubber was mixed in an internal mixer for 3 min at a roller temperature of 125° C., and then 12 g of zinc oxide, 50 g of hydroxy flame retardant modified aramid fiber, and 15 g of stearic acid were added to perform rubber removal to obtain a masterbatch; the masterbatch was then mixed with 15 g of antioxidant 2-mercaptobenzopyrimidine, 10 g of accelerator N-cyclohexyl-2-benzothiazolesulfonamide, and 20 g of sulfur in a double-roll open mill, and triangularly packaged 5 times, thinned 8 times, and mixed for 10 min. The mixture was cooled and finally placed in a flat vulcanizer for vulcanization at 170° C. and 10 MPa to obtain a modified tear-resistant and high-temperature resistant EPDM rubber.

[0053] The tensile properties were tested according to GB / T 528-2009. The tensile speed was 500 mm / min and the test temperature was 25°C.

[0054] The tearing properties were tested according to GB T 529-2008 method. The tensile speed was 500 mm / min and the test temperature was 25°C.

[0055] The modified tear-resistant and high-temperature resistant EPDM rubber was placed in an oven and heat treated at 120°C for 72 hours. After being taken out and cooled to room temperature, the tensile and tear properties were tested.

[0056] The oxygen index is tested according to GBT 10707-2008 method.

[0057] Table 1 EPDM rubber tensile properties test

[0058]

[0059]

[0060] Table 2 EPDM rubber tearing performance test

[0061]

[0062] Table 3 Flame retardant properties test of EPDM rubber

[0063]

[0064]

[0065] As shown in Table 1, the EPDM rubber of Comparative Example 1 does not have hydroxyl flame retardant modified aramid fiber. The tensile strength is 16.6MPa, the elongation at break is 382.8%, the tear strength is 48.2kN / m, and after heat treatment at 120°C for 72h, the tensile property retention rate and the tear strength retention rate are low, the decline is low, and the high temperature resistance is poor. In addition, the limiting oxygen index is only 22.5%, and the flame retardancy is poor.

[0066] In Examples 1-4, hydroxyl flame retardant-modified aramid fiber is added. The aramid fiber itself has certain flame retardant properties. After air cold plasma treatment and allyl hydroxy DOPO pyrimidine flame retardant grafting modification, DOPO and pyrimidine groups are introduced on the fiber surface to form a nitrogen-phosphorus flame retardant. When burned, DOPO pyrolyzes to produce phosphoric acid substances, which can promote the dehydration of the matrix to carbonize. The nitrogen-containing pyrimidine groups pyrolyze at high temperature to produce non-flammable gases such as nitrogen, thereby having a good synergistic flame retardant effect with the aramid fiber, significantly improving the limiting oxygen index of EPDM rubber, and having better flame retardant properties.

[0067] Aramid fiber has the characteristics of high strength, high modulus and strong high temperature resistance. After being grafted with allyl hydroxyl DOPO pyrimidine flame retardant, a large number of hydroxyl groups are introduced on the fiber surface, which can react with the anhydride group of maleic anhydride grafted EPDM rubber, so that the maleic anhydride grafted EPDM rubber can be used as a compatibilizer to improve the compatibility of aramid fiber with the EPDM rubber matrix. It has good dispersion in the rubber group, so that aramid fiber can significantly enhance the mechanical properties and high temperature resistance of EPDM rubber, showing higher tensile properties and tear strength. After heat treatment at 120°C for 72 hours, the mechanical strength decreases at a low level, and the tensile properties and tear strength retention rate are high.

[0068] In Comparative Example 2, unmodified aramid fiber is added, which has poor compatibility with EPDM rubber and poor dispersion in the rubber group, which has an adverse effect on the mechanical properties of EPDM rubber. In addition, the aramid fiber is not grafted with allyl hydroxyl DOPO pyrimidine flame retardant and does not contain DOPO and pyrimidine nitrogen-phosphorus flame retardant groups, and cannot effectively improve the limiting oxygen index and flame retardant properties of EPDM rubber.

[0069] In Comparative Example 3, aramid fiber modified with hydroxyl flame retardant was added, and the oxygen limiting index of EPDM rubber was significantly improved, and the flame retardant performance was very good. However, due to the lack of maleic anhydride grafted EPDM rubber compatibilizer, the compatibility with EPDM rubber was poor, and the tensile properties and tear strength of the rubber were not significantly improved. However, the tensile properties and tear strength of Comparative Example 3 were higher than those of Comparative Examples 1 and 2. It may be that the allyl hydroxy DOPO pyrimidine flame retardant contains allyl groups. After the aramid fiber is grafted with the flame retardant, the molecular chain of the polypropylene derivative is introduced on the fiber surface, which can improve the compatibility of the aramid fiber with EPDM rubber to a certain extent, so the tensile properties and tear strength are improved to a certain extent.

[0070] The above description of the present disclosure is provided to enable any person of ordinary skill in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to those of ordinary skill in the art, and the general principles corresponding to the present disclosure may be applied to other variations without departing from the scope of protection of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is consistent with the widest range of principles and novel features disclosed herein.

Claims

1. A process for preparing tear-resistant and high-temperature resistant EPDM rubber, characterized in that: The preparation process comprises: mixing EPDM rubber in an internal mixer, then adding zinc oxide, hydroxy flame retardant modified aramid fiber, maleic anhydride grafted EPDM rubber, and stearic acid, and performing rubber removal to obtain a masterbatch; then mixing the masterbatch with an antioxidant, an accelerator, and sulfur in a double-roll open mill to form a triangle bag, thin pass, and sheet, and cooling, and finally placing the masterbatch in a flat vulcanizer for vulcanization to obtain a modified tear-resistant and high-temperature resistant EPDM rubber; The preparation method of the hydroxyl flame retardant modified aramid fiber is: The aramid fiber is washed with ethanol and water in turn, dried, and then placed in a plasma generator for air cold plasma treatment; finally, the aramid fiber is placed in an ethanol solution containing an allyl hydroxy DOPO pyrimidine flame retardant, a grafting reaction is carried out in a nitrogen atmosphere, and after filtering, it is washed with xylene and acetone in turn, and dried to obtain a hydroxy flame retardant modified aramid fiber; The structural formula of the allyl hydroxy DOPO pyrimidine flame retardant is formula (I): Formula (I); The usage of the EPDM rubber is 100 parts by weight, the usage of the hydroxy flame retardant modified aramid fiber is 5-20 parts by weight, and the usage of the maleic anhydride grafted EPDM rubber is 1.2-5 parts by weight.

2. The preparation process of tear-resistant and high-temperature resistant EPDM rubber according to claim 1, characterized in that: The power of the plasma generator is 200-250W, the air pressure in the reaction chamber is 15-25Pa, and the treatment time is 5-10min.

3. The preparation process of tear-resistant and high-temperature resistant EPDM rubber according to claim 1, characterized in that: The mass concentration of the allyl hydroxy DOPO pyrimidine flame retardant in the ethanol solution is (30-150) g / L.

4. The process for preparing tear-resistant and high-temperature resistant EPDM rubber according to claim 1, characterized in that: The grafting reaction is carried out at 50-70° C. for 1-3 hours.

5. The process for preparing tear-resistant and high-temperature resistant EPDM rubber according to claim 1, characterized in that: The preparation process of the allyl hydroxy DOPO pyrimidine flame retardant is as follows: S1, adding 100 parts by weight of 5-pyrimidineamine and 120-135 parts by weight of 4-hydroxybenzaldehyde to ethanol, dropping 6-10 parts by weight of glacial acetic acid, reacting at 60-75° C. for 3-5 hours, concentrating the solution, washing the product with water, and recrystallizing it in ethyl acetate to obtain intermediate A; S2, adding 100 parts by weight of intermediate A and 105-130 parts by weight of DOPO to ethanol, reacting at 75-80° C. for 3-5 hours, concentrating the solution, washing the product with acetone, and recrystallizing it in ethanol to obtain intermediate B; S3. Add intermediate B, propylene bromide and a catalyst to acetonitrile. After the reaction, concentrate the solution. After washing with water, recrystallize the product in ethyl acetate to obtain an allyl hydroxy DOPO pyrimidine flame retardant.

6. The process for preparing tear-resistant and high-temperature resistant EPDM rubber according to claim 5, characterized in that: In the above S3, the usage of intermediate B is 100 parts by weight, propylene bromide is 32-40 parts by weight, and the catalyst is 46-60 parts by weight.

7. The process for preparing tear-resistant and high-temperature resistant EPDM rubber according to claim 6, characterized in that: The catalyst is potassium carbonate or sodium carbonate.

8. The process for preparing tear-resistant and high-temperature resistant EPDM rubber according to claim 5, characterized in that: In S3, the reaction is carried out at 60-75° C. for 8-12 h.

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