High-temperature-resistant electromagnetic shielding sealing material and preparation method thereof

Abstract

The application relates to the technical field of electromagnetic shielding sealing materials, and discloses a high-temperature-resistant electromagnetic shielding sealing material and a preparation method thereof. The high-temperature-resistant electromagnetic shielding sealing material comprises the following components in parts by mass: 100 parts of terpolymer ethylene-propylene rubber, 40-60 parts of carbon-based conductive fillers, 8-15 parts of acid anhydride, 3-7 parts of an activator, 2-4 parts of an antioxidant, 3-5 parts of a vulcanizing agent and 1-3 parts of an accelerator. The preparation method of the high-temperature-resistant electromagnetic shielding sealing material comprises the following steps: after the terpolymer ethylene-propylene rubber is plasticated, the remaining components are added for mixing and vulcanization forming to obtain the high-temperature-resistant electromagnetic shielding sealing material. Through the technical scheme, the problem that the carbon-based conductive fillers are not well dispersed in the rubber matrix in the prior art, resulting in low strength and poor high-temperature resistance of the electromagnetic shielding sealing material, is solved.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding sealing materials technology, specifically to a high-temperature resistant electromagnetic shielding sealing material and its preparation method. Background Technology

[0002] With the continuous development of the electronics industry, electromagnetic radiation has become the fourth major form of pollution after air pollution, water pollution, and noise pollution. The high-frequency electromagnetic waves emitted by electronic devices can not only cause the devices to malfunction, but also affect human health. Therefore, it is crucial to do a good job of electromagnetic shielding, and the selection of electromagnetic shielding materials is also extremely important.

[0003] Conductive rubber possesses excellent conductivity and sealing properties, and is widely used in electromagnetic shielding sealing materials. Conductive rubber is obtained by adding conductive fillers to a rubber base, then blending the fillers to ensure uniform distribution within the rubber matrix, followed by processing and molding.

[0004] Compared to other types of conductive rubber base materials, EPDM rubber has no double bonds in its molecular structure. When exposed to ozone, ultraviolet light, and humid heat, the main chain is not easily broken. Therefore, it has good aging resistance and a service life of up to 50 years. It is widely used as the rubber base material for high-temperature electromagnetic shielding sealing materials.

[0005] Conductive fillers include metallic conductive fillers and carbon-based conductive fillers. Metallic conductive fillers generate oxides at high temperatures, leading to a significant decrease in the material's conductivity. Therefore, carbon-based conductive fillers with good high-temperature resistance, such as carbon black and carbon nanotubes, are commonly used in the preparation of high-temperature resistant electromagnetic shielding sealing materials. However, carbon-based conductive fillers are poorly dispersed in rubber matrices, which limits the material's strength and high-temperature resistance. Summary of the Invention

[0006] This invention proposes a high-temperature resistant electromagnetic shielding sealing material and its preparation method, which solves the problem in related technologies where carbon-based conductive fillers are poorly dispersed in a rubber matrix, resulting in low strength and poor high-temperature resistance of the electromagnetic shielding sealing material.

[0007] The technical solution of the present invention is as follows:

[0008] A high-temperature resistant electromagnetic shielding sealing material comprises the following components in parts by weight: 100 parts of EPDM rubber, 40-60 parts of carbon-based conductive filler, 8-15 parts of acid anhydride, 3-7 parts of activator, 2-4 parts of antioxidant, 3-5 parts of vulcanizing agent, and 1-3 parts of accelerator.

[0009] As a further technical solution, the mass ratio of the carbon-based conductive filler to the acid anhydride is 25:5~6.

[0010] As a further technical solution, the acid anhydride includes one or more of phthalic anhydride, maleic anhydride, and 1,1-cyclohexyldiacetic anhydride.

[0011] As a further technical solution, it also includes 2 to 8 parts of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene.

[0012] As a further technical solution, the mass ratio of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene to acid anhydride is 2~3:6.

[0013] As a further technical solution, the carbon-based conductive filler includes one or two of carbon black and carbon nanotubes.

[0014] As a further technical solution, the activator includes one or more of stearic acid, zinc oxide, and calcium oxide.

[0015] As a further technical solution, the antioxidant includes one or more of antioxidant RD, antioxidant 4010NA and antioxidant MB.

[0016] As a further technical solution, the vulcanizing agent includes one or more of sulfur and peroxide;

[0017] The accelerator includes one or more of accelerators CZ, accelerators NS, and accelerators M.

[0018] The present invention also proposes a method for preparing a high-temperature resistant electromagnetic shielding sealing material, comprising the following steps: after plasticizing EPDM rubber, adding the remaining components for mixing, vulcanizing and molding to obtain the high-temperature resistant electromagnetic shielding sealing material.

[0019] The working principle and beneficial effects of this invention are as follows:

[0020] 1. This invention adds acid anhydride, which reacts with the hydroxyl groups on the surface of the carbon-based conductive filler to improve the inorganic nature of the carbon-based conductive filler surface, making the carbon-based conductive filler uniformly dispersed in the rubber matrix, thereby improving the strength, high temperature resistance and electromagnetic shielding effectiveness of the electromagnetic shielding sealing material.

[0021] 2. The present invention further adds 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, which further improves the strength and high temperature resistance of the electromagnetic shielding sealing material. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] In the following examples and comparative examples, the EPDM rubber was 4760P; the carbon black was Cabot conductive carbon black VULCANX C-72R; and the carbon nanotubes were multi-walled carbon nanotubes with a fineness of 1000 mesh, a diameter of 15-25 nm, a length of 5-15 μm, and a specific surface area of ​​150-210 m². 2 / g, purchased from Jiaxing Naco New Materials Co., Ltd.

[0024] Example 1

[0025] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 50 parts of carbon nanotubes, 8 parts of 1,1-cyclohexyl diacetic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 4 parts of sulfur and 2 parts of accelerator CZ were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0026] Example 2

[0027] After plasticizing 100 parts of EPDM rubber at 50℃ for 7 minutes, 40 parts of carbon nanotubes, 8 parts of 1,1-cyclohexyl diacetic anhydride, 1 part of stearic acid, 2 parts of zinc oxide, and 2 parts of antioxidant 4010NA were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 3 parts of dicumyl peroxide and 1 part of accelerator M were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0028] Example 3

[0029] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 60 parts of carbon black, 8 parts of 1,1-cyclohexyl diacetic anhydride, 4 parts of stearic acid, 3 parts of calcium oxide, and 4 parts of antioxidant MB were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 5 parts of benzoyl peroxide and 3 parts of accelerator NS were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0030] Example 4

[0031] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 50 parts of carbon nanotubes, 10 parts of 1,1-cyclohexyl diacetic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 4 parts of sulfur and 2 parts of accelerator CZ were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0032] Example 5

[0033] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 50 parts of carbon nanotubes, 12 parts of 1,1-cyclohexyl diacetic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 4 parts of sulfur and 2 parts of accelerator CZ were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0034] Example 6

[0035] After plasticizing 100 parts of EPDM rubber at 50℃ for 7 minutes, 50 parts of carbon nanotubes, 15 parts of 1,1-cyclohexyl diacetic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 4 parts of sulfur and 2 parts of accelerator CZ were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0036] Example 7

[0037] After plasticizing 100 parts of EPDM rubber at 50℃ for 7 minutes, 50 parts of carbon nanotubes, 12 parts of phthalic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 4 parts of sulfur and 2 parts of accelerator CZ were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0038] Example 8

[0039] After plasticizing 100 parts of EPDM rubber at 50℃ for 7 minutes, 50 parts of carbon nanotubes, 12 parts of maleic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃, 4 parts of sulfur and 2 parts of accelerator CZ were added, and the mixture was continued to be mixed for 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0040] Example 9

[0041] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 50 parts of carbon nanotubes, 12 parts of phthalic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃ and 2 parts of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, 4 parts of sulfur, and 2 parts of accelerator CZ were added and mixed for another 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0042] Example 10

[0043] After plasticizing 100 parts of EPDM rubber at 50℃ for 7 minutes, 50 parts of carbon nanotubes, 12 parts of phthalic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃ and 4 parts of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, 4 parts of sulfur, and 2 parts of accelerator CZ were added and mixed for another 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0044] Example 11

[0045] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 50 parts of carbon nanotubes, 12 parts of phthalic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃ and 6 parts of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, 4 parts of sulfur, and 2 parts of accelerator CZ were added and mixed for another 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0046] Example 12

[0047] 100 parts of EPDM rubber were plasticized at 50℃ for 7 minutes, then 50 parts of carbon nanotubes, 12 parts of phthalic anhydride, 3 parts of stearic acid, 2 parts of zinc oxide, and 3 parts of antioxidant RD were added and mixed at 135℃ for 4 minutes. The mixture was then cooled to 40℃ and 8 parts of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, 4 parts of sulfur, and 2 parts of accelerator CZ were added and mixed for another 5 minutes. The mixture was then vulcanized at 170℃ and 15MPa and cooled to obtain a high-temperature resistant electromagnetic shielding sealing material.

[0048] Comparative Example 1

[0049] The only difference from Example 1 is that 1,1-cyclohexyldiacetic anhydride is not added.

[0050] Performance testing:

[0051] (1) Tensile strength: Refer to the method in GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", cut into dumbbell-shaped specimens of type 1A and test the tensile strength at a moving speed of 100 mm / min. The tensile strength before heat aging is recorded. The results are recorded in Table 1.

[0052] (2) High temperature resistance: Refer to the method in GB / T 17782-1999 "Test method for heat aging of vulcanized rubber under pressure air" to carry out a heat aging test at 120℃ for 96h, test the tensile strength after heat aging, and calculate the tensile strength change rate according to the following formula. The results are recorded in Table 1.

[0053] Tensile strength change rate (%) = (Tensile strength after heat aging - Tensile strength before heat aging) ÷ Tensile strength before heat aging × 100

[0054] (3) Electromagnetic shielding effectiveness: The electromagnetic shielding effectiveness was measured using a vector network analyzer (PAN-LN5230L) and calculated using the following formula. The results are recorded in Table 2.

[0055] Electromagnetic shielding effectiveness = SER + SEA, where SER is the reflection effectiveness and SEA is the absorption effectiveness;

[0056] Table 1. Tensile strength and tensile strength variation rate of high-temperature electromagnetic shielding sealing materials

[0057]

[0058] As can be seen from Table 1, the tensile strength of the high-temperature electromagnetic shielding sealing material provided by the present invention is above 17.1 MPa, exhibiting high tensile strength and good high-temperature resistance.

[0059] Compared with Comparative Example 1, the high-temperature resistant electromagnetic shielding sealing materials obtained in Examples 1-12 have better tensile strength and high-temperature resistance than those in Comparative Example 1. This indicates that the addition of acid anhydride can make the carbon-based conductive filler uniformly dispersed in the rubber matrix, thereby improving the tensile strength and high-temperature resistance of the electromagnetic shielding sealing material.

[0060] Compared with Examples 1-8, Examples 9-12 contain 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, while Examples 1-8 do not contain 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene. The tensile strength and high-temperature resistance of the high-temperature electromagnetic shielding sealing materials obtained in Examples 1-8 are lower than those in Comparative Examples 9-12, indicating that adding 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene can further improve the tensile strength and high-temperature resistance of the electromagnetic shielding sealing materials.

[0061] Table 2 Electromagnetic shielding effectiveness of high-temperature resistant electromagnetic shielding sealing materials

[0062]

[0063] As can be seen from Table 2, the electromagnetic shielding effectiveness of the high-temperature electromagnetic shielding sealing materials obtained in Examples 1-8 is higher than that of Comparative Example 1, indicating that the addition of acid anhydride can make the carbon-based conductive filler uniformly dispersed in the rubber matrix, thereby improving the electromagnetic shielding effectiveness of the electromagnetic shielding sealing material.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant electromagnetic shielding sealing material, characterized in that, The composition comprises the following components in parts by weight: 100 parts of EPDM rubber, 40-60 parts of carbon-based conductive filler, 8-15 parts of acid anhydride, 3-7 parts of activator, 2-4 parts of antioxidant, 3-5 parts of vulcanizing agent, 1-3 parts of accelerator, and 2-8 parts of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene; wherein the acid anhydride comprises one or both of phthalic anhydride and 1,1-cyclohexyldiacetic anhydride.

2. The high-temperature resistant electromagnetic shielding sealing material according to claim 1, characterized in that, The mass ratio of the carbon-based conductive filler to the acid anhydride is 25:5~6.

3. The high-temperature resistant electromagnetic shielding sealing material according to claim 1, characterized in that, The mass ratio of 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene to acid anhydride is 2~3:

6.

4. The high-temperature resistant electromagnetic shielding sealing material according to claim 1, characterized in that, The carbon-based conductive filler includes one or two of carbon black and carbon nanotubes.

5. The high-temperature resistant electromagnetic shielding sealing material according to claim 1, characterized in that, The activator includes one or more of stearic acid, zinc oxide, and calcium oxide.

6. The high-temperature resistant electromagnetic shielding sealing material according to claim 1, characterized in that, The antioxidant includes one or more of antioxidant RD, antioxidant 4010NA and antioxidant MB.

7. The high-temperature resistant electromagnetic shielding sealing material according to claim 1, characterized in that, The vulcanizing agent includes one or more of sulfur and peroxide; The accelerator includes one or more of accelerators CZ, accelerators NS, and accelerators M.

8. A method for preparing a high-temperature resistant electromagnetic shielding sealing material according to any one of claims 1 to 7, characterized in that, Includes the following steps: After plasticizing EPDM rubber, the remaining components are added and mixed, then vulcanized to obtain a high-temperature resistant electromagnetic shielding sealing material.

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