A strong adhesion electromagnetic shielding sealing rubber material and a preparation method and application thereof

Abstract

The application discloses a kind of strong adhesion electromagnetic shielding sealing rubber material and preparation method and application thereof, it is related to electromagnetic shielding material technical field.The application comprises the following components by weight:107 silicone rubber 100 parts, conductive metal powder 200~600 parts, conductive reinforcing agent 2~10 parts, cerium oxide 2~10 parts, tackifier 20~50 parts, fumed silica 5~15 parts, curing agent 4~8 parts, silane coupling agent 3~6 parts;The tackifier is MQ silicone resin and / or polyisobutylene.The application based on the tackifier of polyisobutylene and MQ silicone resin, applied to adhesive and sealant can effectively improve its viscosity, can be bonded to different types of substrates, and effectively improve the shear resistance of adhesive, so that it is not easy to break or deform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic shielding materials, in particular to a strong adhesion electromagnetic shielding sealing rubber material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous upgrading of electronic equipment and military equipment, a large amount of electromagnetic radiation is generated, which has potential harm to the normal operation of electronic equipment and human health, and also puts forward higher demands on the electromagnetic protection capability of modern electronic information systems. As a new type of electromagnetic shielding material, electromagnetic shielding rubber is widely used in sealing scenes of wireless communication, electronic equipment and military equipment due to its excellent electrical conductivity, processing performance and flexibility, providing good sealing and electromagnetic protection.

[0003] At present, room temperature vulcanized silicone rubber is commonly used in industry to prepare electromagnetic shielding sealing materials for plugging or repairing of gap parts of electronic equipment or sites. When used for plugging or repairing, electromagnetic shielding sealing rubber needs to be in close contact with the base material to prevent electromagnetic waves from leaking from the gap. This requires electromagnetic shielding sealing rubber to have good mutual adhesion and self-adhesion. However, the surface energy of silicone rubber is low, and the adhesion is poor. When bonded with low surface energy interfaces such as polyethylene, polypropylene and glass, there are a series of problems such as difficult construction, poor adhesion, poor shear resistance, and adhesion force decreasing with time, which seriously affect the construction and result in a significant reduction in the actual electromagnetic shielding and protection effect.

[0004] Therefore, it is of great significance to improve the adhesion of sealing rubber by designing and optimizing the formula to balance excellent electromagnetic protection effect and adhesion performance, and to improve the electromagnetic protection reliability and use convenience of electromagnetic shielding sealing rubber. SUMMARY

[0005] In view of the deficiencies in the above background art, the present application provides a strong adhesion electromagnetic shielding sealing rubber material and a preparation method and application thereof. The present application uses polyisobutylene and MQ silicone resin as a viscous liquid tackifier, which has high adhesion and strong penetration, and is widely used in pressure sensitive adhesive, hot melt adhesive, mouse board and other fields. When applied to adhesive and sealant, it can effectively improve the adhesion, bond different types of substrates, and effectively improve the shear resistance of the adhesive, so that it is not easy to break or deform. This is very important in some occasions, for example, when pasting hard materials such as glass and metal, strong shear resistance is needed to maintain the adhesion effect.

[0006] To achieve the above purpose, the first object of the present application is to provide a strong adhesion electromagnetic shielding sealing rubber material, which comprises the following components by weight:

[0007] 107 silicone rubber 100 parts, conductive metal powder 200-600 parts, conductive reinforcing agent 2-10 parts, cerium oxide 2-10 parts, tackifier 20-50 parts, fumed silica 5-15 parts, curing agent 4-8 parts, silane coupling agent 3-6 parts;

[0008] The tackifier is MQ silicone resin and / or polyisobutylene.

[0009] Preferably, the viscosity of the 107 silicone rubber is 750-100000 mPa·s.

[0010] Preferably, the conductive metal powder is one or more of silver-coated copper powder, silver-coated aluminum powder, silver-coated nickel powder, and silver-coated glass microbeads.

[0011] Preferably, the conductive reinforcing agent is one or more of silver powder, conductive carbon black, carbon nanotubes, and graphene.

[0012] Preferably, the particle size of the silver powder is 1-20 μm, and the particle size of the cerium oxide is 10-50 μm.

[0013] Preferably, the curing agent is one or more of methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, dibutyltin dilaurate, and dibutyltin diacetate.

[0014] Preferably, the silane coupling agent is one or more of KH-550, KH-560, KH-570, and KH-792.

[0015] A second object of the present application is to provide a method for preparing the strong-adhesion electromagnetic shielding sealing rubber material, comprising the following steps:

[0016] The 107 silicone rubber, conductive metal powder, conductive reinforcing agent, cerium oxide, tackifier, and fumed silica are added to a kneader, and mixed at 110-130 °C under vacuum for 1-2 h to remove internal moisture as a first-stage rubber; after waiting for the first-stage rubber to cool to ≤50 °C, the first-stage rubber is added to a double-planetary mixer, mixed, and a curing agent is added and mixed under vacuum for 30-60 min, and then removed and packaged.

[0017] A third object of the present application is to provide a rubber material for use in electromagnetic shielding.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] The application provides a strong adhesion electromagnetic shielding sealing rubber material and a preparation method and application thereof. By adding conductive metal powder as a primary conductive filler and a conductive reinforcing agent as a secondary conductive filler, a multi-dimensional conductive network system is constructed to realize synergistic effect of conductivity; cerium oxide is used as an antioxidant to reduce the decline of the binding force of the filler caused by rubber aging and prolong the service life; the adhesion agent has good compatibility with the silicone rubber, weakens the intermolecular force of the silicone rubber, improves the flexibility of the silicone rubber and provides excellent adhesion, and the end groups of the silane coupling agent contain amino groups and epoxy groups to improve the wettability with the bonding base material, and the synergistic effect of the two provides the silicone rubber with strong adhesion; fumed silica is used to reinforce the silicone rubber to improve the strength and shear resistance of the silicone rubber. The strong adhesion electromagnetic shielding sealing rubber material prepared by the application has high shielding performance and high adhesion. The preparation method provided by the application is convenient for construction, has wide applicability, can be used for bonding low surface energy substrates such as polyethylene, polypropylene and glass and other high surface energy substrates, and can be adhered to a vertical interface without falling off. The strong adhesion electromagnetic shielding sealing rubber material prepared by the preparation method has shear resistance and long-term adhesion, which ensures the durability and reliability of electromagnetic shielding protection. DETAILED DESCRIPTION

[0020] In order for those skilled in the art to better understand the technical solutions of the application and implement them, the application is further described below in combination with specific examples, but the examples are not used as limitations to the application.

[0021] The polyisobutylene and the MQ silicone resin provided by the application are both viscous liquid tackifiers, have high tackiness and strong penetration, and are widely used in the fields of pressure-sensitive adhesives, hot melt adhesives and mouse boards. When applied to adhesives and sealants, the adhesives and sealants can effectively improve the tackiness, bond different types of substrates, and effectively improve the shear resistance of the adhesives, so that the adhesives are not easy to break or deform, which is very important in some occasions, for example, when hard materials such as glass and metal are pasted, strong shear resistance is required to maintain the bonding effect.

[0022] The application provides a strong adhesion electromagnetic shielding sealing rubber material, which comprises the following components by weight:

[0023] 107 silicone rubber 100 parts, conductive metal powder 200-600 parts, conductive reinforcing agent 2-10 parts, cerium oxide 2-10 parts, adhesion agent 20-50 parts, fumed silica 5-15 parts, curing agent 4-8 parts, and silane coupling agent 3-6 parts.

[0024] The adhesion agent is an MQ silicone resin and / or polyisobutylene.

[0025] The viscosity of the 107 silicone rubber is 750-100000 mPa·s.

[0026] The conductive metal powder is one or more of silver-coated copper powder, silver-coated aluminum powder, silver-coated nickel powder, and silver-coated glass microbeads.

[0027] The conductive reinforcing agent is one or more of silver powder, conductive carbon black, carbon nanotubes, and graphene.

[0028] The particle size of the silver powder is 1-20 μm, and the particle size of the cerium oxide is 10-50 μm.

[0029] The curing agent is one or more of methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, dibutyltin dilaurate, and dibutyltin diacetate.

[0030] The silane coupling agent is one or more of KH-550, KH-560, KH-570, and KH-792.

[0031] The second aspect of the present application provides a preparation method of a strong-adhesion electromagnetic shielding sealing rubber material, comprising the following steps:

[0032] The 107 silicone rubber, conductive metal powder, conductive reinforcing agent, cerium oxide, tackifier, and fumed white carbon black are added into a kneader, and mixed by vacuum stirring at 110-130°C for 1-2 h to remove internal moisture as a first-stage glue. After the first-stage glue is cooled to ≤50°C, it is added into a double-planetary stirrer, stirred, and vacuum stirred for 30-60 min by adding a curing agent, and then taken out for packaging.

[0033] In an embodiment, a preparation method of a strong-adhesion electromagnetic shielding sealing rubber material, comprising the following steps:

[0034] The 107 silicone rubber, conductive metal powder, conductive reinforcing agent, cerium oxide, tackifier, and fumed white carbon black are added into a kneader, and mixed by vacuum stirring at 120°C for 1-2 h to remove internal moisture as a first-stage glue. After the first-stage glue is cooled to ≤50°C, it is added into a double-planetary stirrer, stirred, and vacuum stirred for 30-60 min by adding a curing agent, and then taken out for packaging.

[0035] The third aspect of the present application provides an application of a rubber material in electromagnetic shielding.

[0036] It should be noted that, in the present application, the experimental methods used are conventional methods unless otherwise specified; and the reagents and materials used are commercially available unless otherwise specified.

[0037] The following embodiment provides a preparation method of a strong-adhesion electromagnetic shielding sealing rubber material, which is as follows:

[0038] The materials were weighed according to the formulation in Table 1, and then added into a kneader. The kneader was sealed and started to run. The temperature of the kneader was set to 120°C. The kneader was vacuumized and stirred for 2 hours. Then the heating was turned off and the material was cooled to below 50°C. The vacuum pump was kept running during the whole process. The material was transferred into a double planetary mixer. The curing agent and silane coupling agent were added into the mixer. The mixer was sealed and vacuumized. The material was stirred for 30 minutes. Then the material was taken out and packed. The adhesive of Examples 1-4 was obtained.

[0039] Table 1 Formulation of electromagnetic shielding sealing rubber material (weight ratio)

[0040] Item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 107 silicone rubber, viscosity 750 mPa.s. 80 70 0 0 0 0 107 silicone rubber, viscosity 30000 mPa.s. 0 0 100 100 100 100 107 silicone rubber, viscosity 100000 mPa.s. 20 30 0 0 0 0 Silver-coated aluminum powder, particle size 20 μm 300 0 450 0 0 0 Silver-coated glass beads, particle size 40 μm 0 350 0 0 350 0 Silver-coated copper powder, particle size 40 μm 0 0 0 400 0 400 Silver powder 10 0 5 0 0 0 Carbon nanotube 0 5 0 3 5 3 Cerium oxide 3 4 5 4 4 4 MQ silicone resin 30 30 0 0 0 0 Polyisobutylene 0 0 40 40 0 0 Curing agent 4 4 6 6 4 6 Silane coupling agent KH-550 2 2 3 3 2 3 Silane coupling agent KH-792 1 1 2 2 1 2

[0041] The adhesives of Examples 1-4 were tested for performance.

[0042] The adhesion to polypropylene was tested according to GB / T7124-2008 "Determination of Tensile Shear Strength of Adhesives (Rigid Materials to Rigid Materials)".

[0043] The surface dry time of the adhesive was tested according to GB / T13477.5-2002.

[0044] The shear displacement capacity was tested according to GB / T 22083-2008 "Classification and Requirement of Building Adhesives".

[0045] The electromagnetic shielding performance of the adhesive was tested according to MIL-G-83528.

[0046] Table 2 Performance of Examples and Comparative Examples

[0047] Item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Tack-free time, min 26 min 28 min 32 min 30 min 25 min 28 min Adhesion strength, MPa, polypropylene 0.68 0.67 0.75 0.72 0.26 0.23 Displacement ability ±50 √ √ √ √ × × +100 / -50 √ √ √ √ × × Volume resistivity, mΩ-cm 3.6 2.2 1.6 2.5 1.7 1.2 Shielding effectiveness, 10 MHz 65 68 74 72 69 75 Shielding effectiveness, 10 GHz 85 88 112 108 90 112 Shielding effectiveness, 18 GHz 95 98 115 112 106 114

[0048] From Table 2, it can be seen that the tack-free time and conductive properties of Examples 1-4 are not much different from those of Comparative Examples 1-2, but because the tackifier has a modulus similar to that of the silicone rubber and is compatible with the silicone rubber, it can be uniformly dispersed in the silicone rubber, penetrate between the molecular chains of the silicone rubber, weaken the interaction force between the molecular chains of the silicone rubber, improve the flexibility of the silicone rubber, and entangle with the molecular chains of the silicone rubber. The fumed silica is dispersed in the matrix to form segregation, most of which reinforces the silicone rubber matrix to improve the strength of the silicone rubber, and a small amount of which exists in the tackifier to retain the flexibility of the tackifier, so that the shear resistance and bonding properties of the silicone rubber are obviously improved, and the silicone rubber can be used for bonding in low-surface-energy interface electromagnetic shielding occasions such as polyethylene, polypropylene, and glass, and has strong shear resistance, which can solve the problems such as difficult construction, poor adhesion, no shear resistance, and decreasing adhesion with time of the current electromagnetic shielding sealing rubber. Comparative Examples 1-2 do not add a tackifier to toughen and tackify the silicone rubber, resulting in low rubber bonding strength; and the fumed silica excessively reinforces the silicone rubber, which on the one hand is prone to stress concentration in the silicone rubber, and on the other hand causes interface damage between the silicone rubber and the bonding substrate, resulting in bonding failure.

[0049] The above description is only the best mode of the present application, but the protection scope of the present application is not limited thereto, and all those skilled in the art can make various corresponding changes and modifications to the present application without departing from the principles of the present application, and all such changes and modifications shall fall within the protection scope of the claims of the present application.

Claims

1. A strong adhesion electromagnetic shielding sealing rubber material, characterized by, The following components are included by weight: 107 silicone rubber 100 parts, conductive metal powder 200-600 parts, conductive reinforcing agent 2-10 parts, cerium oxide 2-10 parts, tackifier 20-50 parts, fumed silica 5-15 parts, curing agent 4-8 parts, silane coupling agent 3-6 parts; The tackifier is MQ silicone resin and / or polyisobutylene; The conductive metal powder is one or more of silver-coated copper powder, silver-coated aluminum powder, silver-coated nickel powder, and silver-coated glass beads; The conductive reinforcing agent is one or more of silver powder, conductive carbon black, carbon nanotubes, and graphene; The particle size of the silver powder is 1-20 μm, and the particle size of the cerium oxide is 10-50 μm; The curing agent is one or more of methyltrimethoxysilane, methyltriethoxysilane, and tetramethoxysilane; The silane coupling agent is one or more of KH-550, KH-560, KH-570, and KH-792.

2. The strong adhesion electromagnetic shielding sealing rubber material according to claim 1, characterized by, The viscosity of the 107 silicone rubber is 750-100000 mPa·s.

3. A process for the preparation of the strongly adhering electromagnetic shielding sealing rubber material according to claim 1 or 2, characterized in that, The following steps are included: The 107 silicone rubber, conductive metal powder, conductive reinforcing agent, cerium oxide, tackifier, and fumed silica are added to a kneader, and vacuum stirring is performed at 110-130°C for 1-2 h to remove internal moisture as a one-stage gum; After the one-stage gum is cooled to ≤50°C, it is added to a double-planetary stirrer, and stirring is performed while adding the curing agent and silane coupling agent, and vacuum stirring is performed for 30-60 min, after which the product is removed and packaged.

4. Use of the rubber material of claim 1 or 2 in electromagnetic shielding.