Insulated ethylene propylene diene rubber composite material and method for manufacturing the same

Abstract

The application discloses an insulating EPDM composite material and a preparation method thereof, and belongs to the technical field of rubber preparation. First, boron nitride is dispersed in a dispersing agent, a coupling agent is added, and modified boron nitride is obtained by drying; the modified boron nitride is dispersed in polyisobutylene in a molten state, and polyisobutylene@boron nitride composite powder is obtained after freezing, crushing and sieving; EPDM, the polyisobutylene@boron nitride composite powder, a conductive agent and an antioxidant are mixed; finally, a vulcanizing agent is added to the S3 mixed system, and the insulating EPDM composite material is obtained after vulcanization is completed. The insulating EPDM composite material provided by the application has excellent electrical insulation performance and electrical resistance, can effectively prevent electrical tree aging, and prolongs the service life of the product.

Description

Technical Field

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

[0002] Ethylene propylene diene monomer (EPDM) rubber possesses excellent electrical insulation and corona resistance properties, with electrical properties superior to or approaching those of styrene-butadiene rubber, chlorosulfonated polyethylene, polyethylene, and cross-linked polyethylene. This is mainly due to the absence of polar substituents in its molecular structure, low cohesive energy, and the ability of its molecular chains to maintain flexibility over a wide range, resulting in low water absorption and thus good insulation properties.

[0003] However, the application of EPDM in insulation still has some shortcomings and areas for improvement. With the increasing demands on insulation material performance from modern electronic equipment and high-voltage electrical systems, EPDM's insulation performance may not meet requirements in complex environments such as high field strength and high humidity. Furthermore, EPDM has poor compatibility with other polar materials, which poses difficulties in preparing composite materials to improve insulation performance. For example, when combined with some polar fillers or fibers, problems such as uneven dispersion and poor interfacial bonding may occur, thus affecting the overall insulation effect of the composite material. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an insulating EPDM rubber composite material and its preparation method.

[0005] The first aspect of this invention is to provide a method for preparing an insulating EPDM rubber composite material, comprising the following steps:

[0006] S1: Boron nitride is dispersed in a dispersant, a coupling agent is added, and the mixture is dried to obtain modified boron nitride;

[0007] S2: Modified boron nitride is dispersed in molten polyisobutylene, pulverized under freezing conditions, and then sieved to obtain polyisobutylene@boron nitride composite powder;

[0008] S3: Mix EPDM rubber, polyisobutylene@boron nitride composite powder, conductive agent and antioxidant;

[0009] S4: Add a vulcanizing agent to the S3 mixture system. After vulcanization, an insulating EPDM rubber composite material is obtained.

[0010] It should be noted that boron nitride (BN) is a highly insulating filler that imparts ultra-high volume resistivity and breakdown strength to materials, while simultaneously blocking electrical dendration channels through its layered structure. Polyisobutylene (PIB) utilizes its molecular chain similarity to ethylene propylene diene monomer (EPDM) rubber to achieve interfacial compatibilization. The PIB@BN core-shell structure obtained by the above methods improves dispersibility and eliminates interfacial effects by physically isolating BN agglomerates through PIB coating. The enrichment effect of the PIB surface drives the uniform distribution of BN at the rubber interface, forming a dense physical barrier layer on the rubber surface that blocks internal charge injection and inhibits electrical tree initiation, thereby achieving long-lasting antistatic properties. Furthermore, the weak polarity and low surface energy of the PIB molecular chain facilitate the adsorption of environmental moisture or ions, forming directional migration channels for surface charges. This allows charges to migrate and dissipate rapidly through the interface, reducing static electricity accumulation and achieving interfacial dielectric relaxation-type antistatic properties.

[0011] In some embodiments, the dispersant is selected from at least one of anhydrous ethanol and isopropanol; the coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and vinyltriethoxysilane; the conductive agent is selected from carbon black and multi-walled carbon nanotubes; and the vulcanizing agent is selected from at least one of dicumyl peroxide and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0012] In some embodiments, the antioxidant is obtained by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0013] In some embodiments, boron nitride and a dispersant are mixed at a mass ratio of 1:8-12, and the boron nitride has a plate-like structure.

[0014] In some embodiments, in S1, the drying temperature is 120-130°C and the drying time is 3-4 hours.

[0015] In some embodiments, in S2, the freezing conditions are rapid cooling in liquid nitrogen at -20 to -30°C for 10-15 minutes; and the sieve mesh is 400-450 mesh.

[0016] It should be noted that since PIB is in a viscous state at room temperature, room temperature pulverization will cause stringing, and the coating layer will string together and stick, which will lead to uncontrolled particle size and the formation of agglomerated lumps. At the same time, the shear force of room temperature mechanical pulverization will destroy the integrity of the BN sheet structure. Liquid nitrogen cryogenic pulverization ensures that the BN sheets peel off along the PIB seam through brittle fracture, maintaining the sheet structure.

[0017] In some implementations, in step S3, the mixing temperature is 120-150°C and the mixing time is 8-10 min.

[0018] In some embodiments, in S4, the vulcanization time is 10-20 min and the vulcanization temperature is 50-70°C.

[0019] A second aspect of the present invention is to provide an insulating EPDM rubber composite material.

[0020] In some embodiments, by weight, 100 parts of EPDM rubber, 20-30 parts of boron nitride, 8-12 parts of polyisobutylene, 3-4 parts of conductive agent, 2-4 parts of coupling agent, 1-2 parts of antioxidant, and 2-3 parts of vulcanizing agent.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention creatively combines modified boron nitride with polyisobutylene to form a polyisobutylene@boron nitride composite powder. Utilizing the good compatibility of polyisobutylene with EPDM rubber and the low surface energy of polyisobutylene, the polyisobutylene@boron nitride is uniformly dispersed on the rubber surface, forming a dense boron nitride physical barrier layer. This allows the insulating properties of boron nitride to block charge injection and suppress electrical treeing, achieving an insulating effect. Furthermore, polyisobutylene can form surface charge migration channels, enabling rapid charge migration and dissipation, thereby reducing static electricity accumulation.

[0023] The insulating EPDM rubber composite material provided by this invention has excellent electrical insulation and anti-electric properties, can effectively prevent electrical treeing aging, extend the service life of products, and can be widely used in cable insulation layers and other fields. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments.

[0025] Example 1

[0026] An insulating EPDM rubber composite material, by weight, comprises 100 parts EPDM rubber, 25 parts boron nitride, 10 parts polyisobutylene, 4 parts conductive agent, 3 parts coupling agent, 2 parts antioxidant, and 3 parts vulcanizing agent.

[0027] The above-mentioned insulating EPDM rubber composite material is prepared by the following steps:

[0028] S1: Flake boron nitride (source: Shandong Jingyi New Material Co., Ltd.) was dispersed in anhydrous ethanol, γ-glycidoxypropyltrimethoxysilane was added, and the mixture was dried at 125°C for 3.5 h to obtain modified boron nitride; wherein, boron nitride and dispersant were mixed at a mass ratio of 1:10.

[0029] S2: Modified boron nitride was dispersed in molten polyisobutylene, rapidly cooled in liquid nitrogen at -25℃ for 12 min, pulverized, and sieved through a 450-mesh sieve to obtain polyisobutylene@boron nitride composite powder.

[0030] S3: Ethylene propylene diene monomer (EPDM) rubber, polyisobutylene@boron nitride composite powder, carbon black, and antioxidants are mixed at 120-150℃ for 8-10 min; wherein, antioxidants 1010 and antioxidants 168 are compounded in a mass ratio of 1:1.

[0031] S4: Add dicumyl peroxide to the S3 mixture system, and vulcanize at 60°C for 15 min to obtain an insulating EPDM rubber composite material.

[0032] Example 2

[0033] It is basically the same as Example 1, except that: by weight, EPDM rubber is 100 parts, boron nitride is 20 parts, polyisobutylene is 8 parts, conductive agent is 3 parts, coupling agent is 2 parts, antioxidant is 1 part, and vulcanizing agent is 2 parts.

[0034] Example 3

[0035] It is basically the same as Example 1, except that: by weight, EPDM rubber is 100 parts, boron nitride is 30 parts, polyisobutylene is 12 parts, conductive agent is 4 parts, coupling agent is 4 parts, antioxidant is 2 parts, and vulcanizing agent is 3 parts.

[0036] Example 4

[0037] It is basically the same as Example 1, except that:

[0038] The insulating EPDM rubber composite material of Example 4 was prepared by the following steps:

[0039] S1: Disperse flake boron nitride in isopropanol, add γ-aminopropyltriethoxysilane, and dry at 120°C for 3 h to obtain modified boron nitride; wherein, boron nitride and dispersant are mixed at a mass ratio of 1:8;

[0040] S2: Modified boron nitride was dispersed in molten polyisobutylene, rapidly cooled in liquid nitrogen at -20℃ for 10 min, pulverized, and sieved through a 400-mesh sieve to obtain polyisobutylene@boron nitride composite powder.

[0041] S3: Ethylene propylene diene monomer (EPDM) rubber, polyisobutylene@boron nitride composite powder, multi-walled carbon nanotubes, and antioxidants are mixed at 120°C for 8 min; wherein antioxidants 1010 and antioxidants 168 are compounded in a mass ratio of 1:1.

[0042] S4: Add 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane to the S3 mixture system, and vulcanize at 50°C for 10 min to obtain an insulating EPDM rubber composite material.

[0043] Example 5

[0044] It is basically the same as Example 1, except that:

[0045] The insulating EPDM rubber composite material provided in Example 5 is prepared by the following steps:

[0046] S1: Disperse flake boron nitride in anhydrous ethanol, add vinyltriethoxysilane, and dry at 130°C for 4 hours to obtain modified boron nitride; wherein, boron nitride and dispersant are mixed at a mass ratio of 1:12;

[0047] S2: Modified boron nitride was dispersed in molten polyisobutylene, rapidly cooled in liquid nitrogen at -30℃ for 15 min, pulverized, and sieved through a 450-mesh sieve to obtain polyisobutylene@boron nitride composite powder.

[0048] S3: Ethylene propylene diene monomer (EPDM) rubber, polyisobutylene@boron nitride composite powder, carbon black, and antioxidants are mixed at 150°C for 10 min; wherein antioxidants 1010 and antioxidants 168 are compounded in a mass ratio of 1:1.

[0049] S4: Add dicumyl peroxide to the S3 mixture system, and vulcanize at 70°C for 20 min to obtain an insulating EPDM rubber composite material.

[0050] Example 6

[0051] It is basically the same as Example 1, except that the sheet-like boron nitride is replaced with the same amount of spherical boron nitride.

[0052] Comparative Example 1

[0053] The method is basically the same as in Example 1, except that S1 and S2 are omitted in the preparation method, and the polyisobutylene@boron nitride composite powder in S3 is replaced with flake boron nitride and polyisobutylene, that is, BN and PIB are physically blended, rather than PIB@BN core-shell structure.

[0054] Comparative Example 2

[0055] It is basically the same as Example 1, except that polyisobutylene is replaced with the same amount of polymethyl methacrylate.

[0056] Comparative Example 3

[0057] The process is basically the same as in Example 1, except that the operation in S2, "rapidly cooling in liquid nitrogen at -25°C for 12 min", is changed to "cooling and pulverizing at room temperature (25°C)".

[0058] To verify that the insulating EPDM rubber composite material provided by this invention has excellent insulation properties and good mechanical properties, the rubber composite materials prepared in Examples 1-5 and Comparative Examples 1-3 were tested below. The performance test results are shown in Table 1.

[0059] Tensile properties were tested according to GB / T1040.2-2022, with a tensile rate of 500 mm / min.

[0060] Tear strength was tested according to GB / T529-2008, with a tensile rate of 500 mm / min.

[0061] Shore hardness was tested according to GB / T531.1-2008.

[0062] Volume resistivity was tested according to GB / T 40719-2021.

[0063] Dielectric strength was tested according to GB / T 1695-2005.

[0064] Table 1

[0065]

[0066] As can be seen from the performance test data in Table 1, the rubber materials in Examples 1-5 all possess high electrical insulation and excellent physical properties. In Example 6, the sheet-like boron nitride was replaced with spherical boron nitride. The gaps between the spherical particles lacked planar shielding and could not block the charge injection channels, resulting in a decrease in insulation performance. Combined with the comparative examples, it can be seen that the rubber resistivity and dielectric strength decreased due to the blending method used in the comparative examples, indicating that the PIB@BN core-shell structure can greatly improve the resistivity of the rubber material. In Comparative Example 2, due to the extremely poor compatibility between polymethyl methacrylate and EPDM, BN severely agglomerated, and the electrical resistance also decreased significantly. In Comparative Example 3, cooling and crushing at room temperature to obtain polyisobutylene@boron nitride composite powder destroyed the integrity of the BN sheet structure, leading to a decrease in the insulation performance of the rubber material.

[0067] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing an insulating EPDM rubber composite material, characterized in that, Includes the following steps: S1: Boron nitride is dispersed in a dispersant, a coupling agent is added, and the mixture is dried to obtain modified boron nitride; wherein the boron nitride has a plate-like structure; S2: The modified boron nitride is dispersed in molten polyisobutylene, pulverized under freezing conditions, and then sieved to obtain polyisobutylene@boron nitride composite powder; S3: Mix EPDM rubber, the polyisobutylene@boron nitride composite powder, conductive agent and antioxidant; S4: Add a vulcanizing agent to the S3 mixture system. After vulcanization, the insulating EPDM rubber composite material is obtained. Of which, by weight, the EPDM rubber is 100 parts, the boron nitride is 20-30 parts, the polyisobutylene is 8-12 parts, the conductive agent is 3-4 parts, the coupling agent is 2-4 parts, the antioxidant is 1-2 parts, and the vulcanizing agent is 2-3 parts.

2. The method for preparing the insulating EPDM rubber composite material according to claim 1, characterized in that, The dispersant is selected from at least one of anhydrous ethanol and isopropanol; the coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and vinyltriethoxysilane; the conductive agent is selected from carbon black and multi-walled carbon nanotubes; and the vulcanizing agent is selected from at least one of dicumyl peroxide and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

3. The method for preparing the insulating EPDM rubber composite material according to claim 1, characterized in that, The antioxidant is obtained by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:

1.

4. The method for preparing the insulating EPDM rubber composite material according to claim 2, characterized in that, The boron nitride and the dispersant are mixed at a mass ratio of 1:8-12.

5. The method for preparing the insulating EPDM rubber composite material according to claim 1, characterized in that, In step S1, the drying temperature is 120-130℃ and the drying time is 3-4 h.

6. The method for preparing the insulating EPDM rubber composite material according to claim 1, characterized in that, In S2, the freezing conditions are rapid cooling in liquid nitrogen at -20 to -30°C for 10-15 minutes; the sieve mesh is 400-450 mesh.

7. The method for preparing the insulating EPDM rubber composite material according to claim 1, characterized in that, In step S3, the mixing temperature is 120-150℃ and the mixing time is 8-10 min.

8. The method for preparing the insulating EPDM rubber composite material according to claim 1, characterized in that, In S4, the vulcanization time is 10-20 min and the vulcanization temperature is 50-70℃.

9. An insulating EPDM rubber composite material, characterized in that... It is prepared by the preparation method according to any one of claims 1-8.

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