An epdm-based crosslinked rubber material and a method for producing the same

Abstract

This invention relates to an EPDM-based crosslinked rubber material and its preparation method. The rubber material is obtained by vulcanizing raw rubber composed of EPDM rubber, maleic anhydride-grafted polyethylene, a peroxide vulcanizing agent, ethylene glycol dimethacrylate, p-benzoquinone dioxime, lead metal oxide, paraffin oil, a silane coupling agent, and an antioxidant. The EPDM-based crosslinked rubber material obtained by this invention has a double crosslinked structure. The formulation system endows EPDM rubber with excellent physical and mechanical properties, electrical insulation properties, and aging resistance, while also possessing good injection molding performance. This material solves the problems of high prices and long procurement cycles associated with imported finished products, providing an efficient and economical solution for the production of cable accessories.

Description

Technical Field

[0001] This invention belongs to the field of cable accessories technology, specifically relating to an EPDM rubber insulation material and its preparation method. Background Technology

[0002] EPDM rubber material, as a random copolymer, possesses numerous advantages, including high operational reliability, good heat resistance, excellent moisture resistance, slight decrease in electrical and mechanical properties after immersion in water, strong corona resistance, and good cable structural stability under emergency and short-circuit conditions. Due to its excellent electrical insulation properties and good chemical stability, EPDM has been widely used in many fields. However, EPDM insulation materials are affected by various aging factors such as electrical, thermal, and mechanical stress during long-term use, leading to a gradual decline in their insulation performance.

[0003] Existing patent CN112795107B discloses a high-insulation EPDM insulating material for power cables. This material uses EPDM with low flexibility and hardness as the main base material, and adjusts the hardness by adding polyolefin elastomers and polypropylene, thereby obtaining an insulating material with high insulation resistance, high strength, and excellent flexibility. However, this material has poor radiation resistance and cannot effectively avoid aging problems. Patent CN118994797A discloses a cold-resistant EPDM rubber material with EPDM rubber, chlorinated polyethylene, and EPDM rubber as the base materials. This material is suitable for sealing power batteries and improves physical and mechanical properties and flame retardancy. However, the material in this patent has insufficient electrical insulation properties and suffers from easy aging and poor thermal stability, thereby reducing the service life of the material and limiting its application range.

[0004] Therefore, a new rubber insulation material is needed to overcome the problems of traditional methods, improve service life and aging resistance, and expand its application range. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an EPDM rubber insulation material for cable accessories suitable for injection molding and its preparation method, thus overcoming the drawbacks of expensive imported finished products and long procurement cycles, providing an efficient and economical solution. This EPDM rubber possesses excellent physical and mechanical properties, electrical insulation properties, and aging resistance, while also exhibiting good injection molding performance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An EPDM-based crosslinked rubber material is obtained by vulcanization of raw rubber, wherein the raw rubber comprises the following components in parts by weight: 80-90 parts EPDM rubber, 10-15 parts of maleic anhydride-grafted polyethylene 1-2 parts of peroxide vulcanizing agent 2-8 parts of ethylene glycol dimethacrylate 2-3 parts of p-benzoquinone dioxime 15-20 parts of lead metal oxide, 3-8 parts paraffin oil 1-2 parts of silane coupling agent, 1-2 parts of anti-aging agent.

[0007] Preferably, the EPDM rubber has an ethylene content of 65% to 70%.

[0008] Preferably, the peroxide vulcanizing agent is one of DCP or BIBP.

[0009] Preferably, the lead metal oxide is one of Pb3O4 or PbO2.

[0010] Preferably, the silane coupling agent is γ-methacryloxypropyltrimethoxysilane (commercially available under the designation KH570).

[0011] Preferably, the antioxidant is one of MB or RD.

[0012] This invention also provides a method for preparing the above-mentioned EPDM-based crosslinked rubber material, comprising the following steps: (1) Mix EPDM rubber, maleic anhydride grafted polyethylene, antioxidant, paraffin oil and silicone coupling agent until each component is uniformly dispersed to obtain mixture 1; (2) Mix the mixture 1, peroxide vulcanizing agent, ethylene glycol dimethacrylate, p-benzoquinone dioxime and lead metal oxide, and then pass through a thin stream until uniform, and let stand to obtain mixture 2; (3) Vulcanize the mixture 2 to obtain the EPDM-based crosslinked rubber material.

[0013] Preferably, the mixing described in step (1) is carried out in an internal mixer.

[0014] Preferably, the mixing temperature in step (1) is below 130°C.

[0015] Preferably, step (2) is carried out in an open mill, and the thin pass is performed 3 to 5 times.

[0016] Preferably, the parking time in step (2) is 24 hours.

[0017] Preferably, the vulcanization conditions in step (3) are 165~175°C for 15~25 minutes.

[0018] Preferably, step (3) also includes the step of letting the rubber material stand for 24 hours after vulcanization.

[0019] The beneficial effects of this invention are: The present invention provides an EPDM-based crosslinked rubber material and its preparation method, the innovation of which lies in: (1) In this invention, EPDM rubber is used as the base material and a dual crosslinking vulcanization technology system is adopted, including an organic peroxide vulcanization system and a p-benzoquinone dioxime / lead metal oxide vulcanization system. The organic peroxide vulcanization system can effectively improve the tensile strength and elongation at break of the rubber material. The p-benzoquinone dioxime / lead metal oxide vulcanization system has better aging resistance but lower elongation at break. The crosslinked rubber material obtained by the dual crosslinking vulcanization technology system of this invention has good tensile strength, elongation at break and aging resistance.

[0020] (2) The amount of lead metal oxide added in this invention far exceeds the amount required to produce a cross-linking reaction with p-benzoquinone dioxime. Excess lead metal oxide can also act as a filler in the system. At the same time, lead has a relatively high atomic number and density, which can give the rubber material good radiation resistance.

[0021] (3) The addition of silane coupling agent in this invention can be used as a surface modifier for inorganic fillers such as lead metal oxides, which can improve the compatibility between inorganic fillers and rubber matrix. At the same time, the addition of maleic anhydride grafted polyethylene has good compatibility with non-polar segments of polyethylene and non-polar segments of EPDM, and maleic anhydride groups have good compatibility with polar components such as peroxide vulcanizing agent, ethylene glycol dimethacrylate, and p-benzoquinone dioxime, ensuring the overall uniformity.

[0022] (4) In this invention, ethylene glycol dimethacrylate contains double bonds, and the silane coupling agent KH570 also contains double bonds. In the organic peroxide vulcanization system, the free radicals generated by the decomposition of peroxides can also crosslink a small number of double bond groups. The formation of new chemical bonds further promotes the compatibility of ethylene glycol dimethacrylate, lead metal oxides, etc. with the rubber matrix. At the same time, as a flexible long-chain small molecule, ethylene glycol dimethacrylate can be conveniently used to control the overall properties of rubber during the rubber crosslinking process. Detailed Implementation

[0023] To more clearly illustrate the features, advantages, and understanding of the present invention, the following embodiments are provided to further clarify the content of the present invention, which includes, but is not limited to, the following embodiments. Example 1

[0024] (1) Put 85 parts of EPDM rubber into a mixer for mixing. The temperature of the mixing chamber is controlled below 130℃. After mixing the EPDM rubber for 2 minutes, add 12 parts of maleic anhydride grafted polyethylene, 1.5 parts of antioxidant MB, 5 parts of paraffin oil, and 1.5 parts of silane coupling agent KH570. Continue mixing until each component is evenly dispersed. After mixing for a total of 12 minutes, discharge the rubber.

[0025] (2) Add the rubber obtained in step (1), 1.5 parts of peroxide vulcanizing agent DCP, 5 parts of ethylene glycol dimethacrylate, 2.5 parts of p-benzoquinone dioxime, and 18 parts of lead metal oxide Pb3O4 to the open mill. The power is 5.5kw, the roller diameter is 160mm, the roller speed ratio is 1 / 1.4, the front roller linear speed is 24m / min, and the rear roller linear speed is 33.6m / min. After passing through the mill 3 times until the mixture is uniform, the mill is sheeted and left to stand for 24h.

[0026] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine at a temperature of 170°C and a time of 20 min. After vulcanization, the sample was left to stand for 24 hours before use. Example 2

[0027] (1) Put 80 parts of EPDM rubber into a mixer for mixing. The temperature of the mixing chamber is controlled below 130℃. After mixing the EPDM rubber for 2 minutes, add 10 parts of maleic anhydride grafted polyethylene, 1 part of antioxidant RD, 3 parts of paraffin oil, and 1 part of silane coupling agent KH570. Continue mixing until all components are evenly dispersed. After mixing for a total of 10 minutes, discharge the rubber.

[0028] (2) Add the rubber obtained in step (1), 1 part of peroxide vulcanizing agent BIBP, 2 parts of ethylene glycol dimethacrylate, 2 parts of p-benzoquinone dioxime, 15 parts of lead metal oxide Pb3O4 to the open mill. The power is 5.5kw, the roller diameter is 160mm, the roller speed ratio is 1 / 1.4, the front roller linear speed is 24m / min, and the rear roller linear speed is 33.6m / min. After passing through the mill 4 times until the mixture is uniform, the mill is sheeted and left to stand for 24h.

[0029] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine. The vulcanization temperature was 165℃ and the vulcanization time was 25min. After vulcanization, the sample was left to stand for 24 hours before use. Example 3

[0030] (1) Put 90 parts of EPDM rubber into a mixer for mixing. The temperature of the mixing chamber is controlled below 130℃. After mixing the EPDM rubber for 2 minutes, add 15 parts of maleic anhydride grafted polyethylene, 2 parts of antioxidant MB, 8 parts of paraffin oil, and 2 parts of silane coupling agent KH570. Continue mixing until each component is evenly dispersed. After mixing for a total of 15 minutes, discharge the rubber.

[0031] (2) Add the rubber obtained in step (1), 2 parts of peroxide vulcanizing agent DCP, 8 parts of ethylene glycol dimethacrylate, 3 parts of p-benzoquinone dioxime, and 20 parts of lead metal oxide Pb3O4 to the open mill. The power is 5.5kw, the roller diameter is 160mm, the roller speed ratio is 1 / 1.4, the front roller linear speed is 24m / min, and the rear roller linear speed is 33.6m / min. After mixing for 5 times until uniform, the mixture is sheeted and left to stand for 24h.

[0032] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine. The vulcanization temperature was 175℃ and the vulcanization time was 15min. After vulcanization, the sample was left to stand for 24 hours before use. Example 4

[0033] (1) 82 parts of EPDM rubber were put into an internal mixer for mixing. The temperature of the mixing chamber was controlled below 130℃. After mixing the EPDM rubber for 2 minutes, 13 parts of maleic anhydride grafted polyethylene, 1.2 parts of antioxidant RD, 6 parts of paraffin oil, and 1.8 parts of silane coupling agent KH570 were added. The mixture was continued until all components were evenly dispersed. After mixing for a total of 13 minutes, the rubber was discharged.

[0034] (2) Add the rubber obtained in step (1), 1.8 parts of peroxide vulcanizing agent BIBP, 4 parts of ethylene glycol dimethacrylate, 2.2 parts of p-benzoquinone dioxime, and 16 parts of lead metal oxide Pb3O4 to the open mill. The power is 5.5kw, the roller diameter is 160mm, the roller speed ratio is 1 / 1.4, the front roller linear speed is 24m / min, and the rear roller linear speed is 33.6m / min. After passing through the mill 4 times until the mixture is uniform, the mill is sheeted and left to stand for 24h.

[0035] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine at a temperature of 172°C and a time of 18 min. After vulcanization, the sample was left to stand for 24 hours before use.

[0036] Comparative Example 1

[0037] (1) Put 85 parts of EPDM rubber into a mixer for mixing. The temperature of the mixing chamber is controlled below 130℃. After mixing the EPDM rubber for 2 minutes, add 12 parts of maleic anhydride grafted polyethylene, 1.5 parts of antioxidant MB, 5 parts of paraffin oil, and 1.5 parts of silane coupling agent KH570. Continue mixing until each component is evenly dispersed. After mixing for a total of 12 minutes, discharge the rubber.

[0038] (2) Add the rubber obtained in step (1), 1.5 parts of peroxide vulcanizing agent DCP, and 5 parts of ethylene glycol dimethacrylate to the open mill. No p-benzoquinone dioxime and lead metal oxide were added. The power is 5.5kw, the roller diameter is 160mm, the roller speed ratio is 1 / 1.4, the front roller linear speed is 24m / min, and the rear roller linear speed is 33.6m / min. After passing through the mill 3 times until the mixture is uniform, the mill is sheeted and left to stand for 24h.

[0039] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine. The vulcanization temperature was 170℃ and the vulcanization time was 20min. After vulcanization, the sample was left to stand for 24 hours before use.

[0040] Comparative Example 2

[0041] (1) Put 85 parts of EPDM rubber into a mixer for mixing. The temperature of the mixing chamber is controlled below 130℃. After mixing the EPDM rubber for 2 minutes, add 12 parts of maleic anhydride grafted polyethylene, 1.5 parts of antioxidant MB, 5 parts of paraffin oil, and 1.5 parts of silane coupling agent KH570. Continue mixing until each component is evenly dispersed. After mixing for a total of 12 minutes, discharge the rubber.

[0042] (2) Add the rubber obtained in step (1) to the open mill, without adding peroxide vulcanizing agent, add 2.5 parts of p-benzoquinone dioxime and 18 parts of lead metal oxide, power 5.5kw, roller diameter 160mm, roller speed ratio 1 / 1.4, front roller linear speed 24m / min, rear roller linear speed 33.6m / min, pass through the mill 3 times until the mixture is uniform, then sheet it and let it stand for 24h.

[0043] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine. The vulcanization temperature was 170℃ and the vulcanization time was 20min. After vulcanization, the sample was left to stand for 24 hours before use.

[0044] Comparative Example 3

[0045] (1) Put 85 parts of EPDM rubber into a mixer for mixing. The temperature of the mixing chamber is controlled below 130℃. After mixing the EPDM rubber for 2 minutes, add 12 parts of maleic anhydride grafted polyethylene, 1.5 parts of antioxidant MB, and 5 parts of paraffin oil. Continue mixing until all components are evenly dispersed. After mixing for a total of 12 minutes, discharge the rubber.

[0046] (2) Add the rubber obtained in step (1), 1.5 parts of peroxide vulcanizing agent DCP, 5 parts of ethylene glycol dimethacrylate, 2.5 parts of p-benzoquinone dioxime, and 18 parts of lead metal oxide Pb3O4 to the open mill. The power is 5.5kw, the roller diameter is 160mm, the roller speed ratio is 1 / 1.4, the front roller linear speed is 24m / min, and the rear roller linear speed is 33.6m / min. After passing through the mill 3 times until the mixture is uniform, the mill is sheeted and left to stand for 24h.

[0047] (3) The vulcanization of the sample was carried out on a vacuum track vulcanizing machine at a temperature of 170°C and a time of 20 min. After vulcanization, the sample was left to stand for 24 hours before use.

[0048] Test case

[0049] The rubber materials obtained in Examples 1-4 and Comparative Examples 1-3 were tested for Shore A hardness, tensile strength, elongation, and radiation resistance. The test results are shown in Table 1. Radiation resistance was tested according to GB / T14522-2008 standard at 150℃ for 72 hours to determine the retention rate of tensile strength of the samples.

[0050] Table 1 Sample performance test results sample Shore A hardness Tensile strength (MPa) Elongation (%) Radiation resistance (%) Example 1 78 12.5 380 85 Example 2 75 11.2 410 82 Example 3 80 13.8 350 88 Example 4 77 12.0 390 84 Comparative Example 1 65 8.3 320 62 Comparative Example 2 76 9.5 250 83 Comparative Example 3 77 10.2 300 70 As can be seen from the data in Table 1, the samples in Examples 1-4 exhibited higher tensile strength, elongation, and radiation resistance, and their Shore A hardness was also within a reasonable range suitable for cable accessories. The dual crosslinking vulcanization system composed of organic peroxide and p-benzoquinone dioxime / lead metal oxide effectively crosslinked the EPDM rubber with its components, contributing to improved tensile strength, elongation, and radiation resistance. The excess lead metal oxide, while participating in the crosslinking reaction, also acts as a filler for reinforcement. Furthermore, the high atomic number and density of lead significantly enhance the material's radiation stability, which is the key reason why the radiation resistance of the examples is superior to that of the samples with a single vulcanization system. The increased elongation demonstrates that the dual crosslinking system used in this invention compensates for the low elongation at break of the single p-benzoquinone dioxime vulcanization system. The synergistic effect of the organic peroxide vulcanization system and the p-benzoquinone dioxime / lead metal oxide vulcanization system balances the material's strength and toughness. The processing technology of Examples 1-4 and Comparative Examples 1-3 is completely the same, and the components can be uniformly dispersed during the mixing process. This shows that the formulation system of the present invention improves the performance without affecting its processing performance, and solves the problems of expensive imported finished products and long procurement cycle.

[0051] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. An EPDM-based crosslinked rubber material, characterized in that, It is obtained by vulcanizing raw rubber. The raw rubber comprises the following components in parts by weight: 80-90 parts EPDM rubber, 10-15 parts of maleic anhydride-grafted polyethylene 1-2 parts of peroxide vulcanizing agent 2-8 parts of ethylene glycol dimethacrylate 2-3 parts of p-benzoquinone dioxime 15-20 parts of lead metal oxide, 3-8 parts paraffin oil 1-2 parts of silane coupling agent 1-2 parts of anti-aging agent.

2. The EPDM-based crosslinked rubber material according to claim 1, characterized in that, The peroxide vulcanizing agent is either DCP or BIBP.

3. The EPDM-based crosslinked rubber material according to claim 1, characterized in that, The lead metal oxide is either Pb3O4 or PbO2.

4. The EPDM-based crosslinked rubber material according to claim 1, characterized in that, The silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane.

5. The EPDM-based crosslinked rubber material according to claim 1, characterized in that, The antioxidant mentioned is either MB or RD.

6. A method for preparing the EPDM-based crosslinked rubber material according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Mix EPDM rubber, maleic anhydride grafted polyethylene, antioxidant, paraffin oil and silicone coupling agent until each component is uniformly dispersed to obtain mixture 1; (2) Mix the mixture 1, peroxide vulcanizing agent, ethylene glycol dimethacrylate, p-benzoquinone dioxime and lead metal oxide, and then pass through a thin stream until uniform, and let stand to obtain mixture 2; (3) Vulcanize the mixture 2 to obtain the EPDM-based crosslinked rubber material.

7. The preparation method according to claim 6, characterized in that, The mixing temperature described in step (1) is below 130°C.

8. The preparation method according to claim 6, characterized in that, Step (2) is carried out in an open mill, and the thin pass is performed 3 to 5 times.

9. The preparation method according to claim 6, characterized in that, The parking time mentioned in step (2) is 24 hours.

10. The preparation method according to claim 6, characterized in that, The vulcanization conditions described in step (3) are 165~175℃ and 15~25 minutes.