EPDM (Ethylene-Propylene-Diene Monomer) and silicone rubber blend and preparation method thereof

Abstract

The invention relates to the technical field of rubber production, in particular to an ethylene propylene diene monomer and silicone rubber blend rubber and a preparation method thereof. The blend rubber comprises the following raw materials in parts by weight: 10-90 parts of ethylene-propylene-diene monomer raw rubber, 2-5 parts of a modifier, 10-90 parts of methyl vinyl organic silicon raw rubber, 1-5 parts of an active agent, 0.5-2 parts of a coupling agent, 10-40 parts of a reinforcing agent and 1.5-5 parts of a vulcanizing agent. According to the invention, the ethylene-propylene-diene monomer raw rubber and the methyl vinyl organic silicon raw rubber are blended, and the compatibility of a blending system is improved by the aid of the modifier, the coupling agent and the like, so that the purpose of uniform blending is achieved, and the blended rubber material with excellent comprehensive performance is produced. The obtained blended rubber material not only has the characteristics of high strength and puncture resistance of the ethylene propylene diene monomer, but also has the characteristics of high and low temperature aging resistance of the silicone rubber, so that the application field of the blended rubber is widened.

Description

Technical Field

[0001] The invention relates to the technical field of rubber production, and in particular to an EPDM rubber and silicone rubber blend and a preparation method thereof. Background Art

[0002] Ethylene propylene diene monomer (EPDM) has excellent properties such as high strength, puncture resistance, water vapor resistance and ozone aging resistance, but its high temperature resistance is poor; while silicone rubber has good high temperature resistance, aging resistance and self-extinguishing properties, but its mechanical strength is low and the cost is high. In some special application fields, by using EPDM and silicone rubber together, it can not only reduce costs, but also improve the processing performance and high and low temperature resistance of the combined materials, so EPDM and silicone rubber blends will be considered to solve specific application problems, such as spark plug protection caps, high-voltage caps, and rubber parts that have high strength requirements at high temperatures.

[0003] In recent years, there have been many studies on the blending technology of EPDM and silicone rubber in China, but they are basically in the experimental research stage and have not been sold on a large scale in the market. The main reason is that most of the domestic blending technology is still simply to physically mix EPDM and silicone rubber to achieve the purpose of blending. This processing method is relatively simple, but the effect is not very ideal. This is mainly because the two rubber materials have poor compatibility and are difficult to mix. After blending, phase separation and uneven dispersion of the blending components will occur, which will lead to poor strength of the produced products or easy stratification. Summary of the invention

[0004] The purpose of the present invention is to provide an EPDM rubber and silicone rubber blend and a preparation method thereof in order to solve the above-mentioned deficiencies in the prior art.

[0005] The object of the present invention is achieved by the following technical scheme: an EPDM rubber and silicone rubber blend, the blend comprising the following raw materials in parts by weight: 10-90 parts of EPDM raw rubber, 2-5 parts of modifier, 10-90 parts of methyl vinyl silicone raw rubber, 1-6 parts of activator, 0.5-2 parts of coupling agent, 10-40 parts of reinforcing agent, and 1.5-5 parts of vulcanizing agent.

[0006] Furthermore, the Mooney viscosity (ML1+4, 125° C.) of the EPDM raw rubber is 20-60MU, the ethylene content is 60-80%, and the ethylidene-norbornene content is 4-6%.

[0007] Furthermore, the preparation method of the methyl vinyl silicone rubber comprises the following steps: adding octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into a reactor at 80-85°C and stirring thoroughly, introducing nitrogen and evacuating to below 100Pa, maintaining for 1-2h; then continuing to introduce nitrogen to restore to normal pressure and then heating to 110-115°C, adding a catalyst and decamethyltetrasiloxane to react for 3-3.5h, then heating to 160-165°C and evacuating to below 100Pa, continuing to react for 2-2.5h, and cooling naturally after completion to obtain the methyl vinyl silicone rubber.

[0008] Furthermore, the preparation method of the catalyst is: add octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate into a reactor at 80-85°C, pump nitrogen into the reactor and evacuate the reactor to below 100 Pa, and react for 3.5-4.5 hours to obtain the catalyst.

[0009] In the above preparation method, the molar ratio of octamethylcyclotetrasiloxane to tetramethyltetravinylcyclotetrasiloxane is 99:0.1-1, the amount of the catalyst is 0.01-0.05% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane, and the decamethyltetrasiloxane is 0.05-0.08% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane.

[0010] In the present invention, the molecular weight of methyl vinyl silicone rubber is effectively regulated by controlling the ratio of a specific catalyst and decamethyltetrasiloxane through the above method, thereby obtaining methyl vinyl silicone rubber with high molecular weight and narrow distribution, and at the same time making it have good heat resistance.

[0011] Furthermore, the preparation method of the modifier is: fully dissolving the silicone resin or silicone oil containing active double bonds in tetrahydrofuran, then adding the perfluoroalcohol compound and continuing to stir for 20-30 minutes, then adding the initiator, heating to 60-65°C and reacting for 4-8 hours, after which the product is poured into twice the volume of anhydrous ethanol for flocculation, and finally the flocculent is redissolved in tetrahydrofuran, and the product is repeatedly placed in an oven for drying to obtain the modifier.

[0012] In the above modification method, the silicone resin containing active double bonds is vinyl silicone resin or allyl silicone resin, and the silicone oil containing active double bonds is vinyl silicone oil or allyl silicone oil. The perfluoroalcohol compound is any one of 1H, 1H, 2H, 2H-perfluoro-1-dodecanol, 1H, 1H, 2H, 2H-perfluoro-1-decanol, and 1H, 1H, 2H, 2H-perfluorodecanol, and the molar ratio of the perfluoroalcohol compound to the methyl vinyl silicone rubber is 1.18-1.2: 1. The initiator is any one of azobisisobutyronitrile, azobisisoheptanenitrile, diisopropylbenzene peroxide, and di-tert-butyl peroxide, and the amount of the initiator is 0.5-1phr of the mass of the methyl vinyl silicone rubber.

[0013] In the present invention, the modified silicone resin or modified silicone oil obtained by modifying the silicone resin or silicone oil is first subjected to a grafting reaction with the EPDM rubber, thereby effectively improving the compatibility of the system, and at the same time effectively improving the performance of the blended rubber in a low temperature environment, and also showing good water resistance and solvent resistance.

[0014] Furthermore, the active agent is at least one of zinc oxide, stearic acid, and zinc stearate.

[0015] Furthermore, the coupling agent is at least one of γ-aminopropyltriethoxysilane, vinyltriethoxysilane, and divinyldiethoxysilane.

[0016] Furthermore, the reinforcing agent is at least one of white carbon black and high structure carbon black.

[0017] Furthermore, the vulcanizing agent is at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, diisopropylbenzene peroxide, and trimethylolpropane trimethacrylate.

[0018] Furthermore, the blended rubber also includes 0-50 parts of a semi-reinforcing agent, and the semi-reinforcing agent is at least one of active calcium carbonate, kaolin, clay, alkaline silicate, titanium dioxide, and mica powder.

[0019] Furthermore, the blended rubber also includes 0-30 parts of a plasticizer, and the plasticizer is at least one of paraffin oil, cycloalkane oil, white oil, and liquid butadiene.

[0020] The present invention also provides a method for preparing the EPDM rubber and silicone rubber blend, comprising the following steps:

[0021] (1) adding EPDM raw rubber to an internal mixer and heating the mixture to 100-120° C. for internal mixing, then adding a modifier and a small amount of vulcanizing agent thereto, and internal mixing the mixture for 5-10 minutes at a temperature maintained at the temperature to obtain an EPDM raw rubber polymer;

[0022] (2) adding methyl vinyl silicone rubber, reinforcing agent and coupling agent to the EPDM raw rubber polymer obtained in step (1) in multiple portions, adding the materials multiple times to make the system fully mixed, kneading for 2-4 minutes each time, and then heating to 140-150° C. and discharging;

[0023] (3) The rubber material is transferred to an open mixing mill for discharging sheets and left to stand for 12-24 hours to cool the rubber material and fully release the internal stress, and then a vulcanizing agent is added to the open mixing mill. After mixing evenly, the rubber material is discharged from the mixing mill and left to stand for 12-24 hours to obtain the blended rubber.

[0024] The beneficial effects of the present invention are as follows: the present invention achieves the purpose of uniform blending by blending EPDM raw rubber and methyl vinyl silicone raw rubber, and improves the compatibility of the blending system by using modifiers, coupling agents and other additives, thereby producing a blended rubber material with excellent comprehensive performance. The blended rubber material thus obtained not only has the high strength and puncture resistance of EPDM rubber, but also has the high and low temperature aging resistance of silicone rubber, thereby broadening the application field of the blended rubber. Among them, the present invention first carries out a grafting reaction with EPDM rubber through the addition of a modifier, and then blends it with methyl vinyl silicone raw rubber under the action of processing aids such as coupling agents, activators, and reinforcing agents, which can significantly improve the compatibility of the blending system and avoid the problem of decreased mechanical properties of the blended material caused by uneven mixing. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0026] Example 1

[0027] The present embodiment provides a blend of EPDM rubber and silicone rubber, wherein the blend comprises the following raw materials in parts by weight: 70 parts of EPDM raw rubber, 3 parts of modifier, 30 parts of methyl vinyl silicone raw rubber, 5 parts of activator, 1.5 parts of coupling agent, 30 parts of reinforcing agent, and 2 parts of vulcanizer.

[0028] Furthermore, the Mooney viscosity of the EPDM raw rubber is 23MU, the ethylene content is 71wt%, and the ethylene-norbornene content is 5.7wt%.

[0029] Furthermore, the preparation method of the methyl vinyl silicone rubber comprises the following steps: adding octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into an 80°C reactor and stirring sufficiently, introducing nitrogen and evacuating to below 100 Pa, and maintaining for 1.5 hours; then continuing to introduce nitrogen to restore to normal pressure and then heating to 110°C, adding a catalyst and decamethyltetrasiloxane to react for 3 hours, then heating to 160°C and evacuating to below 100 Pa, continuing to react for 2.5 hours, and naturally cooling after completion to obtain the methyl vinyl silicone rubber.

[0030] Furthermore, the preparation method of the catalyst is: add octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate into a reactor at 80°C, pump nitrogen into the reactor and evacuate the reactor to below 100 Pa, and react for 4 hours to obtain the catalyst.

[0031] In the above preparation method, the molar ratio of octamethylcyclotetrasiloxane to tetramethyltetravinylcyclotetrasiloxane is 99:0.3, the amount of the catalyst is 0.03% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane, and the decamethyltetrasiloxane is 0.06% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane.

[0032] Furthermore, the preparation method of the modifier is: fully dissolving silicone oil containing active double bonds in tetrahydrofuran, then adding a perfluoroalcohol compound and continuing stirring for 30 minutes, then adding an initiator, heating to 60-65°C and reacting for 4-8 hours, after which the product is poured into twice the volume of anhydrous ethanol for flocculation, and finally the flocculent is redissolved in tetrahydrofuran, and the product is repeatedly placed in an oven for drying to obtain the modifier.

[0033] In the above modification method, the silicone oil containing active double bonds is vinyl silicone oil. The perfluoroalcohol compound is 1H,1H,2H,2H-perfluoro-1-dodecanol, and the molar ratio of the perfluoroalcohol compound to the methyl vinyl silicone rubber is 1.18:1. The initiator is azobisisobutyronitrile, and the amount of the initiator is 0.6phr of the mass of the methyl vinyl silicone rubber.

[0034] Furthermore, the active agent is compounded by zinc oxide and stearic acid in a mass ratio of 5:1.

[0035] Furthermore, the coupling agent is vinyltriethoxysilane.

[0036] Furthermore, the reinforcing agent is fumed silica, and the specific surface area of ​​the fumed silica is 200 m2 / g.

[0037] Furthermore, the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0038] Furthermore, the blended rubber also includes 25 parts of a semi-reinforcing agent, which is a compound of activated calcium carbonate treated with a silane coupling agent KH-550 and clay, and the mass ratio of the activated calcium carbonate to kaolin is 1:0.8.

[0039] Furthermore, the blended rubber also includes 15 parts of a plasticizer, and the plasticizer is compounded from white oil and liquid butadiene in a mass ratio of 1:1.5.

[0040] The present invention also provides a method for preparing the EPDM rubber and silicone rubber blend, comprising the following steps:

[0041] (1) adding EPDM raw rubber to an internal mixer and heating the mixture to 110° C. for internal mixing, then adding a modifier and a vulcanizing agent in an amount of 1 / 10 of the formula, and internal mixing the mixture for 8 minutes at a temperature of 100° C. to obtain an EPDM raw rubber polymer;

[0042] (2) adding methyl vinyl silicone rubber, reinforcing agent and coupling agent to the EPDM raw rubber polymer obtained in step (1) in multiple portions, adding the materials multiple times to make the system fully mixed, kneading for 3 minutes each time, and then heating to 140° C. and discharging;

[0043] (3) The rubber material is transferred to an open mixer for discharging sheets and left to stand for 12 hours to cool the rubber material and fully release the internal stress. Then, a vulcanizing agent is added to the open mixer, and after mixing evenly, the rubber material is discharged and left to stand for 12 hours to obtain the blended rubber.

[0044] Example 2

[0045] The present embodiment provides a blend of EPDM rubber and silicone rubber, wherein the blend comprises the following raw materials in parts by weight: 80 parts of EPDM raw rubber, 5 parts of a modifier, 50 parts of methyl vinyl silicone raw rubber, 1-3 parts of an activator, 1.5 parts of a coupling agent, 35 parts of a reinforcing agent, and 3 parts of a vulcanizing agent.

[0046] Furthermore, the Mooney viscosity of the EPDM raw rubber is 23MU, the ethylene content is 71wt%, and the ethylene-norbornene content is 5.7wt%.

[0047] Furthermore, the preparation method of the methyl vinyl silicone rubber comprises the following steps: adding octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into an 82°C reactor and stirring sufficiently, introducing nitrogen and evacuating to below 100 Pa, and maintaining for 2 hours; then continuing to introduce nitrogen to restore to normal pressure and then heating to 112°C, adding a catalyst and decamethyltetrasiloxane to react for 3.5 hours, then heating to 162°C and evacuating to below 100 Pa, continuing to react for 2.5 hours, and naturally cooling after completion to obtain the methyl vinyl silicone rubber.

[0048] Furthermore, the preparation method of the catalyst is: add octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate into a reactor at 82° C., pump nitrogen into the reactor and evacuate the reactor to below 100 Pa, and react for 4 hours to obtain the catalyst.

[0049] In the above preparation method, the molar ratio of octamethylcyclotetrasiloxane to tetramethyltetravinylcyclotetrasiloxane is 99:0.5, the amount of the catalyst is 0.03% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane, and the decamethyltetrasiloxane is 0.07% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane.

[0050] Furthermore, the preparation method of the modifier is as follows: fully dissolving the silicone resin containing active double bonds in tetrahydrofuran, then adding the perfluoroalcohol compound and continuing stirring for 25 minutes, then adding the initiator, heating to 62°C and reacting for 6 hours, after which the product is poured into twice the volume of anhydrous ethanol for flocculation, and finally the flocculent is redissolved in tetrahydrofuran, and the product is repeatedly placed in an oven for drying to obtain the modifier.

[0051] In the above modification method, the silicone resin containing active double bonds is vinyl silicone resin, the perfluoroalcohol compound is 1H, 1H, 2H, 2H-perfluorodeoxythiol, and the molar ratio of the perfluoroalcohol compound to the methyl vinyl silicone rubber is 1.19: 1. The initiator is azobisisoheptanenitrile, and the amount of the initiator is 0.8 phr of the mass of the methyl vinyl silicone rubber.

[0052] Furthermore, the active agent is compounded by zinc oxide and stearic acid in a mass ratio of 5:1.

[0053] Furthermore, the coupling agent is divinyldiethoxysilane.

[0054] Furthermore, the reinforcing agent is high-structure carbon black.

[0055] Furthermore, the vulcanizing agent is dicumyl peroxide.

[0056] Furthermore, the blended rubber also includes 20 parts of a semi-reinforcing agent, which is a compound of activated calcium carbonate treated with a silane coupling agent KH-550 and kaolin, and the mass ratio of the activated calcium carbonate to the kaolin is 1:0.6.

[0057] Furthermore, the blended rubber also includes 12 parts of a plasticizer, and the plasticizer is compounded from paraffin oil and liquid butadiene in a mass ratio of 1:1.5.

[0058] The present invention also provides a method for preparing the EPDM rubber and silicone rubber blend, comprising the following steps:

[0059] (1) adding EPDM raw rubber to an internal mixer and heating the mixture to 110° C. for internal mixing, then adding a modifier and a vulcanizing agent in an amount of 1 / 10 of the formula, and internal mixing the mixture for 10 minutes at a temperature maintained at the temperature to obtain an EPDM raw rubber polymer;

[0060] (2) adding methyl vinyl silicone rubber, reinforcing agent, coupling agent, semi-reinforcing agent and plasticizer to the EPDM raw rubber polymer obtained in step (1) in multiple portions, adding the materials multiple times to make the system fully mixed, kneading for 4 minutes each time, and then heating to 145° C. and discharging;

[0061] (3) The rubber material is transferred to an open mixer for discharging sheets and left to stand for 20 hours to cool the rubber material to fully release the internal stress, and then a vulcanizing agent is added to the open mixer. After mixing evenly, the rubber material is discharged and left to stand for 20 hours to obtain the blended rubber.

[0062] Example 3

[0063] The present embodiment provides a blend of EPDM rubber and silicone rubber, wherein the blend comprises the following raw materials in parts by weight: 50 parts of EPDM raw rubber, 3 parts of modifier, 40 parts of methyl vinyl silicone raw rubber, 3 parts of activator, 1.2 parts of coupling agent, 15 parts of reinforcing agent, and 1.8 parts of vulcanizing agent.

[0064] Furthermore, the Mooney viscosity of the EPDM raw rubber is 24MU, the ethylene content is 69wt%, and the ethylene-norbornene content is 4.2wt%.

[0065] Furthermore, the preparation method of the methyl vinyl silicone rubber comprises the following steps: adding octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into an 85°C reactor and stirring thoroughly, introducing nitrogen and evacuating to below 100 Pa, and maintaining for 1.5 hours; then continuing to introduce nitrogen to restore to normal pressure and then heating to 115°C, adding a catalyst and decamethyltetrasiloxane to react for 3 hours, then heating to 165°C and evacuating to below 100 Pa, continuing to react for 2.5 hours, and naturally cooling after completion to obtain the methyl vinyl silicone rubber.

[0066] Furthermore, the preparation method of the catalyst is: add octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate into a reactor at 85°C, pump nitrogen into the reactor and evacuate the reactor to below 100 Pa, and react for 4.5 hours to obtain the catalyst.

[0067] In the above preparation method, the molar ratio of octamethylcyclotetrasiloxane to tetramethyltetravinylcyclotetrasiloxane is 99:0.8, the amount of the catalyst is 0.04% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane, and the decamethyltetrasiloxane is 0.08% of the total amount of octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane.

[0068] Furthermore, the preparation method of the modifier is: fully dissolving the silicone resin containing active double bonds in tetrahydrofuran, then adding the perfluoroalcohol compound and continuing to stir for 25 minutes, then adding the initiator, raising the temperature to 65°C and reacting for 8 hours, after which the product is poured into twice the volume of anhydrous ethanol for flocculation, and finally the flocculent is redissolved in tetrahydrofuran, and the product is repeatedly placed in an oven for drying to obtain the modifier.

[0069] In the above modification method, the silicone resin containing active double bonds is allyl silicone resin, the perfluoroalcohol compound is 1H,1H,2H,2H-perfluoro-1-decyl alcohol, and the molar ratio of the perfluoroalcohol compound to the methyl vinyl silicone rubber is 1.2: 1. The initiator is dicumyl peroxide, and the amount of the initiator is 0.8 phr of the mass of the methyl vinyl silicone rubber.

[0070] Furthermore, the active agent is compounded by zinc oxide and stearic acid in a mass ratio of 5:1.

[0071] Furthermore, the coupling agent is γ-aminopropyltriethoxysilane.

[0072] Furthermore, the reinforcing agent is fumed silica.

[0073] Furthermore, the vulcanizing agent is trimethylolpropane trimethacrylate.

[0074] Furthermore, the blended rubber also includes 35 parts of a semi-reinforcing agent, which is a compound of active calcium carbonate treated with a silane coupling agent KH-550 and mica powder, and the mass ratio of the active calcium carbonate to the mica powder is 1:1.

[0075] Furthermore, the blended rubber also includes 20 parts of a plasticizer, and the plasticizer is compounded from cyclohexane oil and liquid butadiene in a mass ratio of 1:1.5.

[0076] The present invention also provides a method for preparing the EPDM rubber and silicone rubber blend, comprising the following steps:

[0077] (1) adding EPDM raw rubber to an internal mixer and heating the mixture to 120° C. for internal mixing, then adding a modifier and a vulcanizing agent in an amount of 1 / 10 of the formula, and internal mixing the mixture for 10 minutes at a temperature maintained at the temperature to obtain an EPDM raw rubber polymer;

[0078] (2) adding methyl vinyl silicone rubber, reinforcing agent, coupling agent, semi-reinforcing agent and plasticizer to the EPDM raw rubber polymer obtained in step (1) in multiple portions, adding the materials multiple times to make the system fully mixed, kneading for 4 minutes each time, and then heating to 150° C. and discharging;

[0079] (3) The rubber material is transferred to an open mixer for sheeting and left to stand for 24 hours to cool and fully release the internal stress. Then, a vulcanizing agent is added to the open mixer, and after mixing evenly, the rubber material is sheeted and left to stand for 24 hours to obtain the blended rubber.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 1 is that the EPDM rubber and silicone rubber blend provided in this comparative example comprises the following raw materials in parts by weight: 70 parts of EPDM raw rubber, 30 parts of methyl vinyl silicone raw rubber, 5 parts of activator, 1.5 parts of coupling agent, 30 parts of reinforcing agent and 2 parts of vulcanizing agent.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Example 2 is that the modifier in Example 2 is replaced by vinyl silicone resin in this comparative example.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 2 is that this comparative example uses commercially available methyl vinyl silicone rubber (Daoruo 110 silica gel, molecular weight 600,000, vinyl content 0.23%) to replace the methyl vinyl raw rubber in Example 2.

[0086] In the present invention, the hardness, tensile strength, tear strength and elongation of the blended rubber test pieces (180°C×20min×10MPa) prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-3 were tested, wherein the hardness was tested in accordance with the GB / T 531-2008 standard, the tensile strength was tested in accordance with the GB / T 528-2009 standard, the tear strength was tested in accordance with the GB / T 529-2008 standard, and the elongation at break was tested in accordance with the GB / T 528-2009 standard. The test results are shown in the following table:

[0087] project Hardness / HA Tensile strength / MPa Tear strength / kN / m Elongation at break / % Example 1 70 15.8 41 580 Example 2 72 18.3 45 571 Example 3 69 14 38 544 Comparative Example 1 73 8.8 26 360 Comparative Example 2 70 11.4 29 402 Comparative Example 3 72 13.3 33 424

[0088] From the above test comparison, it can be seen that the blended rubbers prepared in Examples 1-3 of the present invention have excellent comprehensive mechanical properties, with hardness maintained between 68-72HA, tensile strength greater than 14MPa, tear strength greater than 38kN / m, and elongation greater than 544%. This shows that the present invention can significantly improve the compatibility of the blending system by first grafting the EPDM raw rubber with the addition of a modifier, and then blending it with the methyl vinyl silicone raw rubber under the action of processing aids such as a coupling agent, an activator, and a reinforcing agent, thereby avoiding the problem of decreased mechanical properties of the blended material caused by uneven mixing.

[0089] In order to further evaluate the high temperature aging resistance of the blended rubber, the blended rubber test piece prepared in Example 2 was placed in an oven at 150°C for 72 hours, and then the tensile strength and elongation at break were tested on the aged test piece. The results showed that the tensile strength of the aged test piece was 18 MPa, and the elongation at break was 556%.

[0090] In order to further evaluate the low-temperature aging resistance of the blended rubber, the blended rubber test piece prepared in Example 2 was placed in a -30°C refrigerator and aged for 72 hours. The tensile strength and elongation at break were then tested on the aged test piece. The results showed that the tensile strength of the aged test piece was 17.2 MPa, and the elongation at break was 543%.

[0091] The above specific embodiments are further explanations of the technical solutions and beneficial effects of the present invention, and are not limitations of the implementation methods. For those skilled in the art, any obvious replacements that do not depart from the concept of the present invention are within the protection scope of the present invention.

Claims

1. An EPDM rubber and silicone rubber blend, characterized in that: The blended rubber comprises the following raw materials in parts by weight: 10-90 parts of EPDM raw rubber, 2-5 parts of modifier, 10-90 parts of methyl vinyl silicone raw rubber, 1-5 parts of activator, 0.5-2 parts of coupling agent, 10-40 parts of reinforcing agent and 1.5-5 parts of vulcanizing agent.

2. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The Mooney viscosity of the EPDM raw rubber is 20-60MU, the ethylene content is 60-80%, and the ethylidene-norbornene content is 4-6%.

3. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The preparation method of the methyl vinyl silicone rubber comprises the following steps: adding octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into a reactor at 80-85° C. and stirring thoroughly, introducing nitrogen and evacuating to below 100 Pa, and maintaining for 1-2 hours; then continuing to introduce nitrogen to restore to normal pressure, heating to 110-115° C., adding a catalyst and decamethyltetrasiloxane to react for 3-3.5 hours, then heating to 160-165° C. and evacuating to below 100 Pa, continuing to react for 2-2.5 hours, and cooling naturally after completion to obtain the methyl vinyl silicone rubber.

4. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The active agent is at least one of zinc oxide, stearic acid and zinc stearate.

5. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The coupling agent is at least one of γ-aminopropyltriethoxysilane, vinyltriethoxysilane and divinyldiethoxysilane.

6. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The reinforcing agent is at least one of white carbon black and high structure carbon black.

7. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The vulcanizing agent is at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, diisopropylbenzene peroxide, and trimethylolpropane trimethacrylate.

8. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The blended rubber also includes 0-50 parts of a semi-reinforcing agent, and the semi-reinforcing agent is at least one of active calcium carbonate, kaolin, clay, alkaline silicate, titanium dioxide, and mica powder.

9. The EPDM rubber and silicone rubber blend according to claim 1, characterized in that: The blended rubber further includes 0-30 parts of a plasticizer, and the plasticizer is at least one of paraffin oil, cycloalkane oil, white oil, and liquid butadiene.

10. The method for preparing the blend of EPDM rubber and silicone rubber according to any one of claims 1 to 9, characterized in that: The steps include: (1) adding EPDM raw rubber to an internal mixer and heating the mixture to 100-120° C. for internal mixing, then adding a modifier and a small amount of vulcanizing agent thereto, and internal mixing the mixture for 5-10 minutes at a temperature maintained at the temperature to obtain an EPDM raw rubber polymer; (2) adding methyl vinyl silicone rubber, reinforcing agent and coupling agent to the EPDM raw rubber polymer obtained in step (1) in multiple portions, adding the materials multiple times to make the system fully mixed, kneading for 2-4 minutes each time, and then heating to 140-150° C. and discharging; (3) The rubber material is transferred to an open mixing mill for discharging sheets and left to stand for 12-24 hours to cool the rubber material and fully release the internal stress, and then a vulcanizing agent is added to the open mixing mill. After mixing evenly, the rubber material is discharged from the mixing mill and left to stand for 12-24 hours to obtain the blended rubber.