A heat-resistant rubber composition and a method for preparing synthetic rubber

Abstract

The invention discloses a method for preparing a heat-resistant rubber composition and a synthetic rubber, and belongs to the field of rubber technology. The raw materials of the heat-resistant rubber composition include: nitrile rubber, ethylene propylene diene monomer rubber, a reinforcing agent, an antioxidant, an activator, a vulcanizing agent, a vulcanization accelerator, a cross-linking agent, and a heat-resistant modification auxiliary agent, wherein the heat-resistant modification auxiliary agent is composed of nano ZrO2 doped with eight-functional styrene-POSS and nano HfO2 doped with eight-functional styrene-POSS; the synthetic rubber is prepared by the above-mentioned heat-resistant rubber composition. The synthetic rubber prepared by the present invention has excellent heat resistance and wear resistance, stable mechanical properties, and long service life.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber, and in particular relates to a preparation method of a heat-resistant rubber composition and a synthetic rubber. Background Art

[0002] Rubber products have the advantages of good insulation, sealing, waterproofness, oil resistance, resilience and plasticity. They can be used in different fields such as tires, rubber pads, sealing rings, conveyor belts, cables, etc. They are mainly made of natural and synthetic rubber as raw materials, and also include recycled rubber produced by recycling waste rubber. Ordinary rubber products are easy to soften at high temperatures, which may not only lose their original functions, but also cause damage to objects in contact with them. Therefore, in these high-temperature special application environments, higher requirements are placed on the performance of rubber products. They need to have good stability, high strength, high temperature resistance and heat resistance to ensure that they can maintain good performance even under extreme temperature conditions, thereby ensuring the safe operation of equipment and the safety of users. This type of rubber product requires not only excellent heat resistance, but also resistance to chemical corrosion and thermal oxidation corrosion, so as to provide reliable functions without affecting the convenience of operation.

[0003] Chinese patent CN109923154A discloses a rubber composition and a preparation method thereof, wherein the rubber composition comprises the following components: a rubber wet masterbatch with a rubber latex solution and a slurry containing carbon black as raw materials, rubber and carbon black, wherein the rubber latex solution is prepared by emulsion polymerization of at least one of isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), nitrile rubber (NBR), and chloroprene rubber (CR), and the rubber component is a blended rubber component of natural rubber and synthetic diene rubber; this patent uses carbon black with a specific DBP absorption amount and an iodine adsorption amount, and the amount of rubber combined with the rubber component is increased, so that the vulcanized rubber prepared from the rubber composition has good wear resistance and low heat generation, but the heat resistance and mechanical stability of the obtained vulcanized rubber are limited, and cannot meet some application scenarios with higher requirements. Chinese patent CN102604172A discloses a heat-resistant nitrile rubber composition, whose components include nitrile rubber, acrylate rubber, zinc oxide, magnesium oxide, stearic acid, white carbon black, spray carbon black, sulfur, quinone oxime, diisopropyl peroxide, magnesium methacrylate, antioxidant OD, antioxidant BPPD, and γ-aminopropyltriethoxysilane; this patent improves the heat resistance of nitrile rubber to a certain extent by adding acrylate rubber and a variety of additives to nitrile rubber, and the heat resistance effect is good, but the stability of the obtained heat-resistant rubber is poor, and the performance is prone to decline with the increase of use time, and the wear resistance and durability are also limited. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a heat-resistant rubber composition and a method for preparing a synthetic rubber. The heat-resistant rubber composition further improves the heat resistance and stability of the rubber by adding a specific heat-resistant modification additive to work together with other components, so that the rubber maintains excellent mechanical properties and wear resistance and extends its service life.

[0005] A heat-resistant rubber composition comprises the following raw materials:

[0006] Acrylonitrile rubber, EPDM rubber, reinforcing agent, antioxidant, activator, vulcanizing agent, vulcanization accelerator, co-crosslinking agent, heat-resistant modification auxiliary agent; the heat-resistant modification auxiliary agent is composed of nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS.

[0007] The invention further improves the heat resistance and mechanical stability of the rubber by adding a specific heat-resistant modification agent, thereby extending the service life. This is attributed to the synergistic effect of nano ZrO2 / HfO2 and the POSS structure. In the process of hydrolyzing and polycondensing the octafunctional styrene-POSS, the invention successfully dopes the nano metal oxide into the cage structure by adding a nano zirconium dioxide / hafnium dioxide dispersion, thereby forming a stable modification agent with better compatibility and dispersibility with the rubber matrix.

[0008] First, nano ZrO2 has a high melting point, excellent thermal stability and thermal shock resistance, and can withstand extreme temperature changes without cracking or breaking; nano HfO2 has a high melting point, excellent thermal stability and corrosion resistance, and can remain stable at extremely high temperatures; their combined use gives rubber excellent high-temperature stability, which can effectively inhibit the degradation and aging of rubber at high temperatures, but direct addition often leads to unsatisfactory results due to its poor compatibility with the rubber matrix and easy agglomeration. After the nano ZrO2 / HfO2 particles are incorporated into the POSS structure, the interface bonding between the inorganic nano particles and the organic rubber matrix is ​​improved. The good dispersibility of the nano particles ensures their uniform distribution with the rubber matrix, promotes more effective stress transfer and energy absorption, and enables the rubber to maintain excellent mechanical properties in high temperature environments. Secondly, the siloxane skeleton in the POSS cage-type structure molecule is also conducive to improving the thermal stability and mechanical strength, while the eight-functional styrene structure can enhance the compatibility with the rubber matrix and the cross-linking density. The double bonds it contains can react with the unsaturated bonds in the rubber to form a complex three-dimensional network structure. This cross-linking not only increases the cross-linking density of the rubber, but also improves the tensile strength and wear resistance. At the same time, the cross-linked network structure can maintain more stable performance at high temperatures, prevent excessive movement and softening of the rubber molecular segments, thereby improving the heat resistance and durability of the rubber; this nano ZrO2 / HfO2 doped styrene-POSS structure not only increases the glass transition temperature of the rubber, but also forms a dense protective layer to reduce the penetration of oxygen and moisture, thereby delaying the aging of the rubber. It can be seen that the heat-resistant modification additive significantly improves the heat resistance and durability of the rubber through the synergistic effects of the above aspects. This comprehensive improvement enables the rubber to maintain excellent physical properties at high temperatures and extend its service life.

[0009] Preferably, the heat-resistant modification aid is prepared by the following method:

[0010] Adding nano zirconium dioxide to an isopropanol aqueous solution and ultrasonically treating it to obtain a nano zirconium dioxide dispersion; adding styrene ethyl trimethoxy silane to tetrahydrofuran, stirring and heating, then adding the nano zirconium dioxide dispersion to react with a tetramethyl ammonium hydroxide aqueous solution, and then performing reduced pressure distillation and drying to obtain nano ZrO2 doped with eight-functional styrene-POSS;

[0011] Adding nano hafnium dioxide to an isopropanol aqueous solution and ultrasonically treating it to obtain a nano hafnium dioxide dispersion; adding styrene ethyl trimethoxy silane to tetrahydrofuran, stirring and heating, then adding the nano hafnium dioxide dispersion to react with a tetramethyl ammonium hydroxide aqueous solution, and then performing reduced pressure distillation and drying to obtain nano HfO2 doped octafunctional styrene-POSS; nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS are uniformly mixed to obtain the heat-resistant modification auxiliary agent.

[0012] Preferably, a heat-resistant rubber composition is composed of the following raw materials in parts by weight:

[0013] 70-80 parts by weight of nitrile rubber, 25-35 parts by weight of EPDM rubber, 15-25 parts by weight of reinforcing agent, 2-4 parts by weight of antioxidant, 4-6 parts by weight of activator, 1.5-3 parts by weight of vulcanizing agent, 1-2 parts by weight of vulcanization accelerator, 1-2 parts by weight of cross-linking agent, and 6-8 parts by weight of heat-resistant modification auxiliary agent.

[0014] Preferably, the reinforcing agent is one of N375 carbon black, N330 carbon black, N220 carbon black, N550 carbon black, and N660 carbon black, or a mixture of two or more thereof.

[0015] Preferably, the reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 1-3:3.

[0016] Preferably, the antioxidant is one of antioxidant RD, antioxidant 6PPD, antioxidant MB, or a mixture of two or more thereof.

[0017] Preferably, the antioxidant is antioxidant RD.

[0018] Preferably, the activator is a mixture of stearic acid and zinc oxide.

[0019] Preferably, the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:3-5.

[0020] Preferably, the vulcanizing agent is sulfur.

[0021] Preferably, the vulcanization accelerator is one or a mixture of two or more of N-cyclohexyl-2-benzothiazolesulfenamide, dibenzothiazole disulfide, and zinc diethyldithiocarbamate.

[0022] Preferably, the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazolesulfenamide and zinc diethyldithiocarbamate in a weight ratio of 1-3:1.

[0023] Preferably, the auxiliary cross-linking agent is at least one of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, and triallyl isocyanurate.

[0024] Preferably, the auxiliary cross-linking agent is trimethylolpropane trimethacrylate.

[0025] Preferably, the heat-resistant modification aid is prepared by the following method:

[0026] 0.3-0.6 parts by weight of nano zirconium dioxide is added to 25-40 parts by weight of 40-50wt% isopropanol aqueous solution, and ultrasonicated for 15-30 minutes at 150-200W and 30-40kHz to obtain a nano zirconium dioxide dispersion; 15-30 parts by weight of styrene ethyl trimethoxy silane is added to 200-300 parts by weight of tetrahydrofuran, and heated to 45-55°C at 50-100r / min stirring, and then 7-15 parts by weight of the nano zirconium dioxide dispersion and 3-6 parts by weight of 15-20wt% tetramethylammonium hydroxide aqueous solution are added, and the reaction is carried out at 45-55°C for 40-45h, and after the reaction, the organic solvent is removed by reduced pressure distillation, and the reaction is dried to obtain nano ZrO2 doped with octafunctional styrene-POSS;

[0027] 0.3-0.6 parts by weight of nano hafnium dioxide is added to 25-40 parts by weight of 40-50wt% isopropanol aqueous solution, and ultrasonicated for 15-30 minutes at 150-200W and 30-40kHz to obtain a nano hafnium dioxide dispersion; 15-30 parts by weight of styrene ethyl trimethoxy silane is added to 200-300 parts by weight of tetrahydrofuran, heated to 45-55°C under stirring at 50-100r / min, and then 7-1 5 parts by weight of nano hafnium dioxide dispersion and 3-6 parts by weight of 15-20wt% tetramethylammonium hydroxide aqueous solution are reacted at 45-55° C. for 40-45 hours, and then the organic solvent is removed by reduced pressure distillation and dried to obtain nano HfO2 doped octafunctional styrene-POSS; nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS are uniformly mixed in a weight ratio of 1:0.5-2 to obtain the heat-resistant modification auxiliary agent.

[0028] The invention also provides a method for preparing the synthetic rubber.

[0029] Preferably, a method for preparing synthetic rubber comprises the following steps:

[0030] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification auxiliary agent into an internal mixer, mix at 95-110°C for 8-12 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 45-60°C. After mixing, leave it for 20-30 hours, and then place it in a flat vulcanizer for vulcanization at 145-160°C for 15-30 minutes to obtain the synthetic rubber.

[0031] Beneficial effects of the present invention:

[0032] The invention provides a heat-resistant rubber composition and a method for preparing a synthetic rubber. By adding a heat-resistant modification auxiliary agent composed of nano ZrO2 doped with eight-functional styrene-POSS and nano HfO2 doped with eight-functional styrene-POSS and acting together with other components, the heat resistance and stability of the rubber are further improved, the rubber maintains excellent mechanical properties and wear resistance, and the service life is extended. The invention also discloses a method for preparing a synthetic rubber using the heat-resistant rubber composition, which has a simple process and is easy to operate. DETAILED DESCRIPTION

[0033] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Some of the raw materials used in the following examples are described as follows:

[0035] Nitrile rubber, NBR, model: 3305E, acrylonitrile content: 33.7wt%, manufacturer: Lanzhou Petrochemical.

[0036] Ethylene propylene diene monomer rubber, EPDM, model: 3092PM, ethylene content: 67wt%, manufacturer: Shanghai Sinopec Mitsui.

[0037] Nano zirconium dioxide, average particle size: 200nm.

[0038] Nano hafnium dioxide, average particle size: 50nm.

[0039] Styreneethyltrimethoxysilane, CAS: 134000-44-5.

[0040] Octaphenyl-POSS, CAS: 5256-79-1.

[0041] Example 1

[0042] A heat-resistant rubber composition, comprising the following raw materials in parts by weight:

[0043] 75 parts by weight of nitrile rubber, 30 parts by weight of EPDM rubber, 20 parts by weight of reinforcing agent, 3 parts by weight of antioxidant, 5 parts by weight of activator, 2 parts by weight of vulcanizing agent, 1.5 parts by weight of vulcanization accelerator, 1.5 parts by weight of cross-linking agent, and 7 parts by weight of heat-resistant modification auxiliary agent. The reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 2:3; the antioxidant is antioxidant RD; the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:4; the vulcanizing agent is sulfur; the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazole sulfenamide and zinc diethyl dithiocarbamate in a weight ratio of 2:1; the cross-linking agent is trimethylolpropane trimethacrylate.

[0044] The heat-resistant modification auxiliary agent is prepared by the following method:

[0045] 0.45 parts by weight of nano zirconium dioxide was added to 30 parts by weight of 45wt% isopropanol aqueous solution, and ultrasonicated for 20 minutes at 180W and 35kHz to obtain a nano zirconium dioxide dispersion; 20 parts by weight of styrene ethyl trimethoxy silane was added to 250 parts by weight of tetrahydrofuran, and heated to 50°C under stirring at 80r / min, and then 10 parts by weight of the nano zirconium dioxide dispersion and 4.5 parts by weight of 18wt% tetramethylammonium hydroxide aqueous solution were added, and the reaction was carried out at 50°C for 42h. After the reaction, the organic solvent was removed by reduced pressure distillation, and the reaction was dried to obtain nano ZrO2 doped with octafunctional styrene-POSS;

[0046] 0.45 parts by weight of nano hafnium dioxide is added to 30 parts by weight of 45wt% isopropanol aqueous solution, and ultrasonicated for 20 minutes at 180W and 35kHz to obtain a nano hafnium dioxide dispersion; 20 parts by weight of styrene ethyl trimethoxy silane is added to 250 parts by weight of tetrahydrofuran, and the temperature is raised to 50°C under a stirring condition of 80r / min, and then 10 parts by weight of the nano hafnium dioxide dispersion and 4.5 parts by weight of 18wt% tetramethylammonium hydroxide aqueous solution are added, and the reaction is carried out at 50°C for 42 hours. After the reaction, the organic solvent is removed by reduced pressure distillation, and the reaction is dried to obtain nano HfO2 doped octafunctional styrene-POSS; nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS are uniformly mixed in a weight ratio of 1:1 to obtain the heat-resistant modification auxiliary agent.

[0047] A method for preparing synthetic rubber comprises the following steps:

[0048] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification auxiliary agent into an internal mixer, mix at 100°C for 10 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 50°C. After mixing, leave it for 24 hours, and then place it in a flat vulcanizer for vulcanization at 150°C for 20 minutes to obtain the synthetic rubber.

[0049] Example 2

[0050] A heat-resistant rubber composition, comprising the following raw materials in parts by weight:

[0051] 70 parts by weight of nitrile rubber, 25 parts by weight of EPDM rubber, 15 parts by weight of reinforcing agent, 2 parts by weight of antioxidant, 4 parts by weight of activator, 1.5 parts by weight of vulcanizing agent, 1 part by weight of vulcanization accelerator, 1 part by weight of cross-linking agent, and 6 parts by weight of heat-resistant modification auxiliary agent. The reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 1:3; the antioxidant is antioxidant RD; the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:3; the vulcanizing agent is sulfur; the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazolesulfenamide and zinc diethyldithiocarbamate in a weight ratio of 1:1; the cross-linking agent is trimethylolpropane trimethacrylate.

[0052] The heat-resistant modification aid is the same as that in Example 1.

[0053] A method for preparing synthetic rubber comprises the following steps:

[0054] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification agent into an internal mixer, mix at 95°C for 12 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 45°C. After mixing, leave it for 20 hours, and then place it in a flat vulcanizer for vulcanization at 145°C for 30 minutes to obtain the synthetic rubber.

[0055] Example 3

[0056] A heat-resistant rubber composition, comprising the following raw materials in parts by weight:

[0057] 80 parts by weight of nitrile rubber, 35 parts by weight of EPDM rubber, 25 parts by weight of reinforcing agent, 4 parts by weight of antioxidant, 6 parts by weight of activator, 3 parts by weight of vulcanizing agent, 2 parts by weight of vulcanization accelerator, 2 parts by weight of cross-linking agent, and 8 parts by weight of heat-resistant modification auxiliary agent. The reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 3:3; the antioxidant is antioxidant RD; the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:5; the vulcanizing agent is sulfur; the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazolesulfenamide and zinc diethyldithiocarbamate in a weight ratio of 3:1; the cross-linking agent is trimethylolpropane trimethacrylate.

[0058] The heat-resistant modification aid is the same as that in Example 1.

[0059] A method for preparing synthetic rubber comprises the following steps:

[0060] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification auxiliary agent into an internal mixer, mix at 110°C for 8 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 60°C. After mixing, leave for 30 hours, and then place in a flat vulcanizer for vulcanization at 160°C for 15 minutes to obtain the synthetic rubber.

[0061] Example 4

[0062] A heat-resistant rubber composition, comprising the following raw materials in parts by weight:

[0063] 75 parts by weight of nitrile rubber, 30 parts by weight of EPDM rubber, 20 parts by weight of reinforcing agent, 3 parts by weight of antioxidant, 5 parts by weight of activator, 2 parts by weight of vulcanizing agent, 1.5 parts by weight of vulcanization accelerator, 1.5 parts by weight of cross-linking agent, and 7 parts by weight of heat-resistant modification auxiliary agent. The reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 2:3; the antioxidant is antioxidant RD; the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:4; the vulcanizing agent is sulfur; the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazole sulfenamide and zinc diethyl dithiocarbamate in a weight ratio of 2:1; the cross-linking agent is trimethylolpropane trimethacrylate.

[0064] The heat-resistant modification auxiliary agent is prepared by the following method:

[0065] 0.45 parts by weight of nano zirconium dioxide is added to 30 parts by weight of a 45wt% isopropanol aqueous solution, and ultrasonicated for 20 minutes at 180W and 35kHz to obtain a nano zirconium dioxide dispersion; 20 parts by weight of styreneethyltrimethoxysilane is added to 250 parts by weight of tetrahydrofuran, and the temperature is raised to 50°C under a stirring condition of 80r / min, and then 10 parts by weight of the nano zirconium dioxide dispersion and 4.5 parts by weight of an 18wt% tetramethylammonium hydroxide aqueous solution are added, and the reaction is carried out at 50°C for 42 hours. After the reaction is completed, the organic solvent is removed by reduced pressure distillation, and the reaction is dried to obtain the heat-resistant modification auxiliary agent.

[0066] A method for preparing synthetic rubber comprises the following steps:

[0067] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification auxiliary agent into an internal mixer, mix at 100°C for 10 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 50°C. After mixing, leave it for 24 hours, and then place it in a flat vulcanizer for vulcanization at 150°C for 20 minutes to obtain the synthetic rubber.

[0068] Example 5

[0069] A heat-resistant rubber composition, comprising the following raw materials in parts by weight:

[0070] 75 parts by weight of nitrile rubber, 30 parts by weight of EPDM rubber, 20 parts by weight of reinforcing agent, 3 parts by weight of antioxidant, 5 parts by weight of activator, 2 parts by weight of vulcanizing agent, 1.5 parts by weight of vulcanization accelerator, 1.5 parts by weight of cross-linking agent, and 7 parts by weight of heat-resistant modification auxiliary agent. The reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 2:3; the antioxidant is antioxidant RD; the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:4; the vulcanizing agent is sulfur; the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazole sulfenamide and zinc diethyl dithiocarbamate in a weight ratio of 2:1; the cross-linking agent is trimethylolpropane trimethacrylate.

[0071] The heat-resistant modification auxiliary agent is prepared by the following method:

[0072] 0.45 parts by weight of nano hafnium dioxide is added to 30 parts by weight of a 45wt% isopropanol aqueous solution, and ultrasonicated for 20 minutes at 180W and 35kHz to obtain a nano hafnium dioxide dispersion; 20 parts by weight of styrene ethyl trimethoxy silane is added to 250 parts by weight of tetrahydrofuran, and the temperature is raised to 50°C under a stirring condition of 80r / min, and then 10 parts by weight of the nano hafnium dioxide dispersion and 4.5 parts by weight of an 18wt% tetramethylammonium hydroxide aqueous solution are added, and the reaction is carried out at 50°C for 42 hours. After the reaction is completed, the organic solvent is removed by reduced pressure distillation, and the mixture is dried to obtain the heat-resistant modification auxiliary agent.

[0073] A method for preparing synthetic rubber comprises the following steps:

[0074] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification auxiliary agent into an internal mixer, mix at 100°C for 10 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 50°C. After mixing, leave it for 24 hours, and then place it in a flat vulcanizer for vulcanization at 150°C for 20 minutes to obtain the synthetic rubber.

[0075] Example 6

[0076] A heat-resistant rubber composition, comprising the following raw materials in parts by weight:

[0077] 75 parts by weight of nitrile rubber, 30 parts by weight of EPDM rubber, 20 parts by weight of reinforcing agent, 3 parts by weight of antioxidant, 5 parts by weight of activator, 2 parts by weight of vulcanizing agent, 1.5 parts by weight of vulcanization accelerator, 1.5 parts by weight of cross-linking agent, and 7 parts by weight of heat-resistant modification auxiliary agent. The reinforcing agent is a mixture of N375 carbon black and N550 carbon black in a weight ratio of 2:3; the antioxidant is antioxidant RD; the activator is a mixture of stearic acid and zinc oxide in a weight ratio of 1:4; the vulcanizing agent is sulfur; the vulcanization accelerator is a mixture of N-cyclohexyl-2-benzothiazole sulfenamide and zinc diethyl dithiocarbamate in a weight ratio of 2:1; the cross-linking agent is trimethylolpropane trimethacrylate.

[0078] The heat-resistant modification auxiliary agent is composed of octaphenyl-POSS, nano zirconium dioxide and nano hafnium dioxide in a weight ratio of 5:0.3:0.3.

[0079] A method for preparing synthetic rubber comprises the following steps:

[0080] Add nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification auxiliary agent into an internal mixer, mix at 100°C for 10 minutes, then add activator, vulcanizer, vulcanization accelerator and cross-linking agent into an open mixer for mixing at 50°C. After mixing, leave it for 24 hours, and then place it in a flat vulcanizer for vulcanization at 150°C for 20 minutes to obtain the synthetic rubber.

[0081] Test Example 1

[0082] The synthetic rubber prepared in the above embodiment was subjected to a low temperature brittleness test with reference to the standard GB / T 15256-2014. The synthetic rubber prepared in the above embodiment was used as a rubber damping block for fatigue test; a cyclic durability test was conducted in a damping disc, and the parameters of a cyclic test were: preload 1200N, load to 1600N, frequency 3Hz, test 1min, unload and stop for 15S; the durability cycle was more than 6000 times, and whether cracks / wear occurred was observed. The results are shown in Table 1.

[0083] Table 1 Test results of low temperature brittleness and durability of rubber

[0084]

[0085] Test Example 2

[0086] The synthetic rubber prepared in the above embodiment was subjected to a thermal oxygen aging test, specifically: the synthetic rubber was aged at 120°C for 168 hours under air conditions. The mechanical properties of the synthetic rubber before and after the aging test were tested in accordance with the standard GB / T 528-2009. Wherein, the rate of change = (value before aging test - value after aging test) / value before aging test × 100%, and the results are shown in Table 2.

[0087] Table 2 Test results of heat resistance stability of rubber

[0088]

[0089] By the comparison of above-mentioned embodiment 1-6, it is known that the synthetic rubber (heat-resistant rubber composition) prepared by embodiment 1-3 has excellent heat resistance and durability, and mechanical property is stable, this is because the present invention has added specific heat-resistant modification auxiliary agent in the raw material formula of heat-resistant rubber composition and plays a role together with other components, thereby significantly improving the heat resistance and stability of rubber. Compared with embodiment 1-3, in embodiment 4-6, do not use by nano ZrO doped eight-functional styrene-POSS and nano HfO doped eight-functional styrene-POSS composition heat-resistant modification auxiliary agent, from Table 2 it can be seen that it causes the heat resistance (mechanical stability) of rubber to have different amplitude reduction, this shows that embodiment 4-6 is owing to not adopting the essential technical solution of the present invention, causes it to be obviously deteriorated in corresponding performance test, further demonstrates the importance of the essential technical solution defined by the present invention to its technical effect.

[0090] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A heat-resistant rubber composition, characterized in that: Including the following ingredients: Acrylonitrile rubber, EPDM rubber, reinforcing agent, antioxidant, activator, vulcanizing agent, vulcanization accelerator, co-crosslinking agent, heat-resistant modification auxiliary agent; the heat-resistant modification auxiliary agent is composed of nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS; The heat-resistant modification auxiliary agent is prepared by the following method: Adding nano zirconium dioxide to an isopropanol aqueous solution and ultrasonically treating it to obtain a nano zirconium dioxide dispersion; adding styrene ethyl trimethoxy silane to tetrahydrofuran, stirring and heating, then adding the nano zirconium dioxide dispersion to react with a tetramethyl ammonium hydroxide aqueous solution, and then performing reduced pressure distillation and drying to obtain nano ZrO2 doped with eight-functional styrene-POSS; Adding nano hafnium dioxide to an isopropanol aqueous solution and ultrasonically treating it to obtain a nano hafnium dioxide dispersion; adding styrene ethyl trimethoxy silane to tetrahydrofuran, stirring and heating, then adding the nano hafnium dioxide dispersion to react with a tetramethyl ammonium hydroxide aqueous solution, and then performing reduced pressure distillation and drying to obtain nano HfO2 doped octafunctional styrene-POSS; nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS are uniformly mixed to obtain the heat-resistant modification auxiliary agent.

2. The heat-resistant rubber composition according to claim 1, characterized in that: The reinforcing agent is one of N375 carbon black, N330 carbon black, N220 carbon black, N550 carbon black, and N660 carbon black, or a mixture of two or more thereof.

3. The heat-resistant rubber composition according to claim 1, characterized in that: The antioxidant is one of antioxidant RD, antioxidant 6PPD, and antioxidant MB, or a mixture of two or more thereof.

4. The heat-resistant rubber composition according to claim 1, characterized in that: The activator is a mixture of stearic acid and zinc oxide.

5. The heat-resistant rubber composition according to claim 1, characterized in that: The vulcanizing agent is sulfur; the vulcanization accelerator is one or a mixture of two or more of N-cyclohexyl-2-benzothiazolesulfenamide, dibenzothiazole disulfide, and zinc diethyldithiocarbamate.

6. The heat-resistant rubber composition according to claim 1, characterized in that: The auxiliary cross-linking agent is at least one of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, and triallyl isocyanurate.

7. The heat-resistant rubber composition according to claim 1, characterized in that: It is composed of the following raw materials in parts by weight: 70-80 parts by weight of nitrile rubber, 25-35 parts by weight of EPDM rubber, 15-25 parts by weight of reinforcing agent, 2-4 parts by weight of antioxidant, 4-6 parts by weight of activator, 1.5-3 parts by weight of vulcanizing agent, 1-2 parts by weight of vulcanization accelerator, 1-2 parts by weight of cross-linking agent, and 6-8 parts by weight of heat-resistant modification auxiliary agent.

8. The heat-resistant rubber composition according to claim 7, characterized in that: The heat-resistant modification auxiliary agent is prepared by the following method: 0.3-0.6 parts by weight of nano zirconium dioxide is added to 25-40 parts by weight of isopropanol aqueous solution, and ultrasonic treatment is performed for 15-30 minutes to obtain a nano zirconium dioxide dispersion; 15-30 parts by weight of styrene ethyl trimethoxy silane is added to 200-300 parts by weight of tetrahydrofuran, the temperature is raised to 45-55° C. under stirring conditions, and then 7-15 parts by weight of the nano zirconium dioxide dispersion and 3-6 parts by weight of tetramethyl ammonium hydroxide aqueous solution are added, and the reaction is carried out at 45-55° C. for 40-45 hours, and after the reaction, the reaction is carried out by reduced pressure distillation and drying to obtain nano ZrO2 doped with octafunctional styrene-POSS; 0.3-0.6 parts by weight of nano hafnium dioxide is added to 25-40 parts by weight of isopropanol aqueous solution, and ultrasonic treatment is performed for 15-30 minutes to obtain a nano hafnium dioxide dispersion; 15-30 parts by weight of styrene ethyl trimethoxy silane is added to 200-300 parts by weight of tetrahydrofuran, the temperature is raised to 45-55° C. under stirring conditions, and then 7-15 parts by weight of the nano hafnium dioxide dispersion and 3-6 parts by weight of tetramethyl ammonium hydroxide aqueous solution are added, and the mixture is reacted at 45-55° C. for 40-45 hours, and then vacuum distilled and dried to obtain nano HfO2 doped octafunctional styrene-POSS; nano ZrO2 doped octafunctional styrene-POSS and nano HfO2 doped octafunctional styrene-POSS are uniformly mixed in a weight ratio of 1:0.5-2 to obtain the heat-resistant modification auxiliary agent.

9. A method for preparing synthetic rubber, characterized in that: The synthetic rubber is prepared by using the heat-resistant rubber composition according to any one of claims 1 to 8, and the preparation method thereof comprises the following steps: The nitrile rubber, EPDM rubber, reinforcing agent, antioxidant and heat-resistant modification agent are added to an internal mixer for internal mixing, and then added with an activator, a vulcanizing agent, a vulcanization accelerator and a cross-linking agent to an open mixer for open mixing. After the mixing is completed, the mixture is left to stand and then placed in a vulcanizer for vulcanization to obtain the synthetic rubber.

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