A salt-fog-resistant electromagnetic shielding rubber material, a preparation method and application thereof

Abstract

The application discloses an easy-to-process salt-fog-resistant electromagnetic shielding rubber material and a preparation method and application thereof, and relates to the technical field of electromagnetic shielding materials.The application comprises the following components by weight: 100 parts of silicone rubber kneaded glue or fluorosilicone rubber kneaded glue, 1-5 parts of a structure control agent, 200-500 parts of conductive metal powder, 5-20 parts of a conductive reinforcing agent, 4-10 parts of an internal lubricant, 3-8 parts of a composite coupling agent, 1-4 parts of a vulcanizing agent and 1-2 parts of an auxiliary crosslinking agent.The internal lubricant such as oleic acid amide is used to modify the electromagnetic shielding rubber, so that the electromagnetic shielding rubber has the properties of easy processing and salt-fog resistance, and has great significance for improving the electromagnetic protection capacity and optimizing the production process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic shielding materials, in particular to an easy-to-process and salt-fog-resistant electromagnetic shielding rubber material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous increase of power of electronic equipment and equipment, a large amount of electromagnetic pollution is generated, which endangers human health and interferes with the normal operation of equipment. As a new type of electromagnetic shielding material, electromagnetic shielding rubber is widely used in sealing scenes in the field of electromagnetic protection due to its excellent electrical conductivity and flexibility.

[0003] Rubber itself is an insulator, and currently, the preparation of electromagnetic shielding rubber in the industry often needs to fill a large amount of conductive metal powder in the rubber. On the one hand, the mutual entanglement between the rubber macromolecular chains and the anchoring effect of the filler on the rubber limit the movement of the rubber macromolecular chains, resulting in reduced flowability of the composite material, difficulty in filling during molding, and the need for greater energy input during the processing process. Moreover, large internal stress is easily generated during extrusion of the rubber compound, leading to extrusion swelling effect and difficulty in size control.

[0004] On the other hand, a large amount of filler leads to a decrease in rubber crosslinking density and cohesion, and external water molecules easily penetrate into the rubber, causing corrosion of the conductive metal powder and a sharp decrease in electromagnetic shielding performance. Therefore, how to weaken the interaction between rubber macromolecular chains and improve the processing performance and salt-fog corrosion resistance of electromagnetic shielding rubber material has become two major problems that need to be solved in the industry. SUMMARY

[0005] In view of the deficiencies in the above background art, the present application provides an easy-to-process and salt-fog-resistant electromagnetic shielding rubber material and a preparation method and application thereof. The internal lubricant such as oleic acid amide, erucic acid amide, and stearic acid amide can weaken the interaction between the internal segments of the polymer, making the molecular chains easy to slide and improving the movement ability of the molecular chains, thereby improving the flowability. Moreover, due to its small molecular characteristics, it is easy to precipitate on the surface to form a waxy film, which isolates external moisture. Therefore, the use of internal lubricants such as oleic acid amide to modify electromagnetic shielding rubber makes it have both easy processing and salt-fog resistance, which is of great significance to improving its electromagnetic protection ability and optimizing the production process.

[0006] To achieve the above-mentioned purpose, the first object of the present application is to provide an easy-to-process and salt-fog-resistant electromagnetic shielding rubber material, which comprises the following components by weight:

[0007] 100 parts of silicone rubber kneaded glue or fluorosilicone rubber kneaded glue, 1-5 parts of structure control agent, 200-500 parts of conductive metal powder, 5-20 parts of conductive reinforcing agent, 4-10 parts of internal lubricant, 3-8 parts of composite coupling agent, 1-4 parts of vulcanizing agent, and 1-2 parts of crosslinking aid.

[0008] The inner lubricant is one or more of oleic acid amide, erucic acid amide, stearic acid amide, ethylene bis-stearamide, glycerol fatty acid ester.

[0009] Preferably, the structure control agent is one or more of methoxyl silicone oil, dimethyl diethoxyl silicone oil, hydroxyl silicone oil, fluorohydroxyl silicone oil.

[0010] Preferably, the conductive metal powder is one or more of silver-coated aluminum powder, silver-coated nickel powder, silver-coated glass microbeads, with a particle size of 10-60 μm and a spherical particle shape.

[0011] Preferably, the conductive reinforcing agent is silver powder with a particle size of 1-20 μm.

[0012] Preferably, the composite coupling agent is a mixture of silane coupling agent and titanate coupling agent.

[0013] The mass ratio of the silane coupling agent to the titanate coupling agent is 1:1-2.

[0014] The silane coupling agent is one or more of KH-550, KH-560, and KH-792.

[0015] The titanate coupling agent is one or more of NDZ-105, NDZ-102, and NDZ-201.

[0016] Preferably, the curing agent is one of bisdibenzyl, bisdibenzyl, DCP, and platinum sulfuration agent.

[0017] The co-crosslinking agent is one of triallyl isocyanurate, triallyl cyanurate, and N,N'-p-phenyl bismaleimide.

[0018] The second object of the application is to provide a method for preparing an electromagnetic shielding rubber material that is easy to process and resistant to salt spray, comprising the following steps:

[0019] The speed of the internal mixer is set to 40-60 rpm / min.

[0020] The rubber, structure control agent, conductive metal powder, conductive reinforcing agent, composite coupling agent, and inner lubricant are sequentially added to the internal mixer and mixed for 10-20 min, with the temperature of the mixing chamber controlled to be ≤100℃; the rubber compound is removed, allowed to stand, and cooled to room temperature, then reinserted into the internal mixer and mixed with the curing agent and co-crosslinking agent for 5-10 min, with the temperature of the mixing chamber controlled to be ≤60℃; the rubber compound is allowed to stand at room temperature for 2-4 h after mixing is completed.

[0021] The rubber compound is subjected to one-stage mold vulcanization to obtain a vulcanized rubber compound; the vulcanized rubber compound is then subjected to two-stage hot air vulcanization to obtain the electromagnetic shielding rubber material.

[0022] Preferably, in the first stage of the molding vulcanization forming process, the vulcanization temperature is 160-180 DEG C, the vulcanization time is 10-40 min, and the vulcanization pressure is 10-20 MPa.

[0023] Preferably, in the second stage of the hot air vulcanization process, the vulcanization temperature is 180-200 DEG C, and the vulcanization time is 1-4 h.

[0024] The third object of the present application is to provide an application of the rubber material in electromagnetic shielding.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The present application provides an easy-to-process, salt-fog-resistant electromagnetic shielding rubber material, a preparation method and an application thereof. The present application is based on the fact that internal lubricants such as oleic acid amide, erucic acid amide and stearic acid amide can penetrate into the intermolecular chains of rubber, weaken the interaction force between the internal chain segments of the polymer, make the intermolecular chains easy to slide, and improve the movement ability of the molecular chains, thereby improving the fluidity. The titanate coupling agent has similar groups to the internal lubricants, which forms a channel for the internal lubricants to precipitate to the surface of the rubber, and due to the small molecular characteristics of the internal lubricants, the internal lubricants are easy to precipitate on the surface of the rubber to form a wax-like film, which isolates the external moisture. Therefore, the use of internal lubricants such as oleic acid amide to modify the electromagnetic shielding rubber makes it have the properties of easy processing and salt-fog resistance, which is of great significance to improve the electromagnetic protection ability and optimize the production process.

[0027] The rubber material provided by the present application reduces the Mooney viscosity of the rubber compound, improves the fluidity of the rubber compound, weakens the intermolecular internal stress of the rubber macromolecule, and can weaken the extrusion swelling effect of the rubber compound during extrusion, thereby optimizing the forming process. The wax-like film precipitated on the surface of the rubber can realize super-hydrophobicity of the rubber, resist the intrusion of moisture into the rubber matrix, and improve the salt-fog corrosion resistance of the electromagnetic shielding rubber. DETAILED DESCRIPTION

[0028] In order for those skilled in the art to better understand the technical solutions of the present application and implement them, the present application will be further described below in conjunction with specific embodiments, but the embodiments are not limiting to the present application.

[0029] The first aspect of the present application provides an easy-to-process, salt-fog-resistant electromagnetic shielding rubber material, which comprises the following components by weight:

[0030] 100 parts of silicone rubber kneaded glue or fluorosilicone rubber kneaded glue, 1-5 parts of a structured control agent, 200-500 parts of conductive metal powder, 5-20 parts of a conductive reinforcing agent, 4-10 parts of an internal lubricant, 3-8 parts of a composite coupling agent, 1-4 parts of a vulcanizing agent, and 1-2 parts of a co-crosslinking agent;

[0031] The inner lubricant is one or more of oleic acid amide, erucic acid amide, stearic acid amide, ethylene bis-stearic acid amide, glycerol fatty acid ester.

[0032] The structural control agent is one or more of methoxy silicone oil, dimethyl diethoxy silicone oil, hydroxyl silicone oil, fluorohydroxy silicone oil.

[0033] The conductive metal powder is one or more of silver-coated aluminum powder, silver-coated nickel powder, silver-coated glass microbeads, with a particle size of 10-60 μm and a spherical particle shape.

[0034] The conductive reinforcing agent is silver powder with a particle size of 1-20 μm.

[0035] The composite coupling agent is a mixture of silane coupling agent and titanate coupling agent.

[0036] The mass ratio of the silane coupling agent to the titanate coupling agent is 1:1-2.

[0037] The silane coupling agent is one or more of KH-550, KH-560 and KH-792.

[0038] The titanate coupling agent is one or more of NDZ-105, NDZ-102 and NDZ-201.

[0039] The curing agent is one of bis-dinitrate, bis-dipentyl, DCP and platinum sulfide agent.

[0040] The co-crosslinking agent is one of triallyl isocyanurate, triallyl cyanurate and N,N'-p-phenyl bismaleimide.

[0041] The second aspect of the application provides a preparation method of an easy-to-process and salt-fog-resistant electromagnetic shielding rubber material, comprising the following steps:

[0042] The speed of the internal mixer is set to 40-60 rpm / min.

[0043] The rubber, the structural control agent, the conductive metal powder, the conductive reinforcing agent, the composite coupling agent and the inner lubricant are sequentially added to the internal mixer and mixed for 10-20 min, with the temperature of the mixing chamber controlled to be ≤100℃; the rubber compound is taken out and cooled to room temperature, and then put into the internal mixer and mixed with the curing agent and the co-crosslinking agent for 5-10 min, with the temperature of the mixing chamber controlled to be ≤60℃; after the mixing, the rubber compound is left to stand at room temperature for 2-4 h to obtain the rubber compound.

[0044] The rubber compound is subjected to one-stage mold pressing vulcanization to obtain a vulcanized rubber compound; and then the vulcanized rubber compound is subjected to two-stage hot air vulcanization to obtain the electromagnetic shielding rubber material.

[0045] In the first-stage mold vulcanization forming process, the vulcanization temperature is 160-180 DEG C, the vulcanization time is 10-40 min, and the vulcanization pressure is 10-20 MPa.

[0046] In the second-stage hot air vulcanization process, the vulcanization temperature is 180-200 DEG C, and the vulcanization time is 1-4 h.

[0047] In an embodiment, a method for preparing a processable and salt spray resistant electromagnetic shielding rubber material comprises the following steps:

[0048] S1, the required materials are weighed according to the formula.

[0049] S2, the speed of the internal mixer is set to 40-60 rpm / min.

[0050] S3, the rubber, structure control agent, conductive metal powder, conductive reinforcing agent, composite coupling agent and internal lubricant are sequentially added to the internal mixer, and mixed for 10-20 min, and the temperature of the mixing chamber is controlled to be not more than 100 DEG C.

[0051] S4, the rubber material is taken out and cooled to room temperature.

[0052] S5, the rubber material is re-input into the internal mixer, and the vulcanizing agent and the crosslinking aid are added, and mixed for 5-10 min, and the temperature of the mixing chamber is controlled to be not more than 60 DEG C.

[0053] S6, the rubber material is stored at room temperature for 4 h.

[0054] S7, the rubber material is subjected to first-stage high-temperature mold vulcanization forming, the vulcanization temperature is 160-180 DEG C, the vulcanization time is 10-40 min, and the vulcanization pressure is 10-20 MPa.

[0055] S8, the first-stage vulcanized rubber material is subjected to second-stage hot air vulcanization, the vulcanization temperature is 180-200 DEG C, and the vulcanization time is 1-4 h, and the electromagnetic shielding rubber material is prepared.

[0056] The third aspect of the application provides a rubber material for use in electromagnetic shielding.

[0057] It should be noted that, in the present application, the experimental methods are conventional methods unless otherwise specified, and the reagents and materials can be purchased on the market unless otherwise specified.

[0058] The following embodiment provides a processable and salt spray resistant electromagnetic shielding rubber material, and the preparation method is as follows:

[0059] The ingredients were weighed according to the formulation in Table 1, and then sequentially added into the internal mixer in the order of rubber, structured control agent, conductive metal powder, conductive reinforcing agent, composite coupling agent and internal lubricant, with the rotation speed of the internal mixer being 50 rpm / min, the temperature of the mixing chamber being controlled at 80 ℃, and the mixing time being 15 min. After the mixing, the rubber compound was taken out and allowed to stand for 30 min to room temperature, and then re-fed into the internal mixer and mixed with vulcanizing agent and crosslinking aid for 10 min, with the temperature of the mixing chamber being controlled at 60 ℃. After the rubber compound was allowed to stand for 4 h, it was vulcanized and formed according to the vulcanization conditions to obtain the example.

[0060] The addition amount of each component in each example and comparative example is shown in Table 1 below.

[0061] Table 1 Formulation of electromagnetic shielding rubber material (weight ratio)

[0062] Item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Silicone rubber kneaded glue 100 100 0 0 100 0 Fluorosilicone rubber kneaded glue 0 0 100 100 0 100 Hydroxyl silicone oil 3 0 0 0 0 0 Fluorohydroxyl silicone oil 0 0 2 3 0 3 Methoxyl silicone oil 0 3 0 0 3 0 Silver-coated aluminum powder 300 0 300 0 0 0 Silver-coated glass beads 0 250 0 250 250 250 Silver powder 10 10 15 15 10 15 Oleic acid amide 4 0 4 0 0 0 Eruic acid amide 0 6 0 6 0 0 Silane coupling agent KH-550 2 0 2 0 0 0 Silane coupling agent KH-792 0 2 0 2 2 2 Titanate coupling agent NDZ-105 2 0 2 4 0 4 Titanate coupling agent NDZ-201 0 3 0 0 3 0 Curing agent DCP 2 0 2 0 0 0 Curing agent bisdipentyl 0 2 0 2 2 2 Co-crosslinking agent TAIC 2 0 2 0 0 0 Co-crosslinking agent PDM 0 1 0 1 1 1 One-stage vulcanization temperature, ℃ 170 160 170 170 160 170 One-stage vulcanization time, min 10 30 10 20 30 20 One-stage vulcanization pressure, MPa 10 15 15 15 15 15 Two-stage vulcanization temperature, ℃ 190 190 200 200 190 200 Two-stage vulcanization time, h 2 2 1 2 2 2

[0063] The performance of Examples 1-4 and Comparative Examples 1-2 was tested.

[0064] The Mooney viscosity was tested according to GB / T 1232.1-2000.

[0065] After the sample was allowed to stand for 24 h, the water contact angle was measured using a contact angle measuring instrument with a model number of SL1000.

[0066] The resistivity was tested using a four-probe resistance tester.

[0067] The electromagnetic shielding performance of the rubber compound was tested according to MIL-G-83528.

[0068] Table 2 Performance of examples and comparative examples

[0069] Item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Mooney viscosity, [100℃ (1+4)] 68 56 70 60 62 67 Hydrophobicity of rubber surface Super-hydrophobic Super-hydrophobic Super-hydrophobic Super-hydrophobic Hydrophobic Hydrophobic Shielding effectiveness, 10 MHz 72 65 74 70 67 72 Shielding effectiveness, 10 GHz 94 78 98 82 78 81 Shielding effectiveness, 18 GHz 115 88 115 105 90 95 Resistivity, Ω·cm 0.0040 0.0075 0.0042 0.0070 0.0052 0.0048 Resistivity after acid salt spray for 400 h, Ω·cm 0.0062 0.0081 0.0065 0.0075 15.25 10.12

[0070] As can be seen from Table 2, compared with Comparative Examples 1-2, Examples 1-4 have the following advantages: (1) due to the addition of the internal lubricant, the interaction between the rubber macromolecular chains is weakened, the rubber flowability is increased, and the Mooney viscosity of the rubber compound is obviously decreased; (2) due to the synergistic effect of the internal lubricant and the titanate coupling agent, the internal lubricant is quickly precipitated from the inside of the rubber to the surface of the rubber, a layer of waxy film is formed on the surface of the rubber after the rubber compound is allowed to stand for 24 h, and the hydrophobicity of the rubber is improved; (3) due to the addition of the internal lubricant, the interaction between the molecular chains is reduced, the friction between the rubber and the filler during the mixing process is reduced to a certain extent, the peeling of the silver shell of the silver-coated aluminum powder or silver-coated glass beads and other core-shell materials is reduced, and after 400 h of acid salt spray, the volume resistivity of the sample of the example changes little, while the volume resistivity of the sample of the comparative example increases obviously, and the presence of the internal lubricant improves the ability of the rubber to resist salt spray corrosion.

[0071] The above merely describes the best mode of the present application, but the protection scope of the present application is not limited to this, and all the skilled in the art can make various corresponding changes and modifications to the present application, and as long as the changes and modifications do not deviate from the principles of the present application, they shall belong to the protection scope of the claims of the present application.

Claims

1. A processable, salt-fog resistant, electromagnetic shielding rubber material, characterized in that, The following components are included by weight: 100 parts of silicone rubber kneading glue or fluorosilicone rubber kneading glue, 1-5 parts of structure control agent, 200-500 parts of conductive metal powder, 5-20 parts of conductive reinforcing agent, 4-10 parts of internal lubricant, 3-8 parts of composite coupling agent, 1-4 parts of vulcanizing agent, and 1-2 parts of crosslinking aid; The internal lubricant is one or more of oleic acid amide, erucic acid amide, stearic acid amide, ethylene bis-stearyl amide, and glycerol fatty acid ester; The structure control agent is one or more of methoxy silicone oil, dimethyl diethoxysilicone oil, hydroxyl silicone oil, and fluorohydroxyl silicone oil; The conductive metal powder is one or more of silver-coated aluminum powder, silver-coated nickel powder, and silver-coated glass microbeads, with a particle size of 10-60 μm and a spherical particle shape; The conductive reinforcing agent is silver powder with a particle size of 1-20 μm; The composite coupling agent is a mixture of silane coupling agent and titanate coupling agent; The mass ratio of the silane coupling agent to the titanate coupling agent is 1:1-2; The silane coupling agent is one or more of KH-550, KH-560, and KH-792; and the titanate coupling agent is one or more of NDZ-105, NDZ-102, and NDZ-201; The vulcanizing agent is one of bis-dibutyltin dilaurate, bis-dibutyltin dataurate, DCP, and platinum gold vulcanizing agent; The crosslinking aid is one of triallyl isocyanurate, triallyl cyanurate, and N,N'-p-phenyl bismaleimide.

2. A process for the preparation of the easily processable, salt mist resistant electromagnetic shielding rubber material as claimed in claim 1, characterized in that, The following steps are included: The speed of the internal mixer is set to 40-60 rpm / min; The rubber, structure control agent, conductive metal powder, conductive reinforcing agent, composite coupling agent, and internal lubricant are sequentially added to the internal mixer and mixed for 10-20 min, with the temperature of the mixing chamber controlled to be ≤100℃; the rubber compound is removed, cooled to room temperature, and then added to the internal mixer, and the vulcanizing agent and crosslinking aid are added and mixed for another 5-10 min, with the temperature of the mixing chamber controlled to be ≤60℃; after mixing, the rubber compound is left to stand at room temperature for 2-4 h to obtain the rubber compound; The rubber compound is subjected to one-stage mold vulcanization to obtain the vulcanized rubber compound; and the vulcanized rubber compound is then subjected to two-stage hot air vulcanization to obtain the electromagnetic shielding rubber material.

3. The process for preparing a processable, salt-fog resistant, electromagnetic shielding rubber material according to claim 2, characterized in that During the one-stage mold vulcanization, the vulcanization temperature is 160-180℃, the vulcanization time is 10-40 min, and the vulcanization pressure is 10-20 MPa.

4. The process for preparing a processable, salt-fog resistant, electromagnetic shielding rubber material according to claim 2, characterized in that During the two-stage hot air vulcanization, the vulcanization temperature is 180-200℃, and the vulcanization time is 1-4 h.

5. The rubber material of claim 1 is used in electromagnetic shielding.