Electromagnetic shielding adhesive composition and preparation method thereof

Abstract

The invention relates to the technical field of electromagnetic shielding materials, in particular to an electromagnetic shielding adhesive composition and a preparation method thereof.The electromagnetic shielding adhesive composition is prepared from, by weight, 100 parts of organic silicon resin, 100-400 parts of conductive filler, 0.1-10 parts of dispersing agent, 0-10 parts of anti-settling agent, 0.1-10 parts of plasticizer, 1-20 parts of vulcanizing agent and 0.1-2 parts of catalyst; the conductive filler comprises nickel-plated carbon nanotubes. The preparation method comprises the following steps: S10, preparing the component A: vacuumizing and mixing the organic silicon resin, the conductive filler, the dispersing agent and the vulcanizing agent in a planetary mixer at the rotating speed of 400-1500 rpm for 1-3 hours; s20, preparing a component B: vacuumizing and mixing an anti-settling agent, a plasticizer and a catalyst in a planetary mixer at the rotating speed of 400-1500 rpm for 1-3 hours; s30, uniformly mixing the component A and the component B through a static mixer; the electromagnetic shielding adhesive composition disclosed by the invention has the characteristics of stable conductivity, high shielding effectiveness, large adhesive strength, no oil leakage, long storage life and stable performance index.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic shielding materials, and particularly relates to an electromagnetic shielding adhesive composition and a preparation method thereof. BACKGROUND

[0002] Electromagnetic shielding is to isolate two space areas with metal to control the induction and radiation of electric field, magnetic field and electromagnetic wave from one area to another. A large number of high-power and high-frequency electronic instruments, communication equipment and computers in modern society will generate electromagnetic waves, which will not only affect the normal operation of other equipment, but also be interfered by external electromagnetic waves, including electromagnetic interference and radio frequency interference, also known as electronic fog. At present, the whole earth surface has been covered by such fog, just like a huge radiation blanket, which is extremely harmful to human society. It is one of the four major pollutions in the world together with water pollution, air pollution and noise pollution. Long-term exposure to low-frequency electromagnetic radiation can also damage the nervous system, hematopoietic system and immune cell function of organisms, and electromagnetic radiation also has an impact on genetics, fertility and teratogenesis. In addition, it will also interfere with the electronic of the car and affect the safe driving of the vehicle, the failure of the signal indicator light, the misopening of the windscreen wiper and the airbag, and the reduction of the ABS braking efficiency. Therefore, it is of great significance to prevent electromagnetic interference and ensure the reliability of intelligent electronic equipment in complex and harsh environments.

[0003] Conductive adhesive is a functional material with both anti-electromagnetic interference and bonding properties, mainly composed of matrix resin and conductive filler. According to the matrix resin, it can be divided into epoxy resin, acrylic and silicone type, etc. According to the conductive filler, it can be divided into silver, copper and carbon series, etc.

[0004] In the related art, the existing electromagnetic shielding adhesive often uses carbon nanotubes as conductive fillers, but there are the following problems: 1. Insufficient shielding effectiveness: the shielding effectiveness of traditional carbon nanotube fillers in the frequency band of 200MHz-10GHz is only 20-40dB, which cannot meet the demand of high-power equipment. 2. Poor dispersibility: carbon nanotubes have large specific surface area (high BET value) and are prone to agglomeration, so high-concentration slurry needs to be prepared by pre-dispersion, which is complex and high in cost. 3. Settlement risk: carbon nanotubes have low density and are prone to stratified settlement during long-term storage, which will damage the conductive network. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, one of the purposes of the present application is to provide an electromagnetic shielding adhesive composition. The adhesive composition solves the problems of existing electromagnetic shielding adhesives, such as difficult dispersion, poor conductivity, low shielding effectiveness, easy settlement of fillers and oil penetration, etc., through surface modification of carbon nanotubes, scientific proportioning of components and synergistic effect, realizes the characteristics of stable conductivity, high shielding effectiveness, large bonding force, no oil penetration, long storage period and stable performance index, and meets the strict requirements of different fields on electromagnetic shielding.

[0006] The second object of the present application is to provide a preparation method of the electromagnetic shielding adhesive composition.

[0007] The first aspect of the present application is to provide an electromagnetic shielding adhesive composition, comprising the following components by weight parts: silicone resin 100 parts, conductive filler 100-400 parts, dispersant 0.1-10 parts, anti-settling agent 0-10 parts, plasticizer 0.1-10 parts, vulcanizing agent 1-20 parts, catalyst 0.1-2 parts. The conductive filler comprises nickel-plated carbon nanotubes.

[0008] In the first aspect of the present application, as a preferred embodiment, the electromagnetic shielding adhesive composition comprises the following components by weight parts: silicone resin 100 parts, conductive filler 100-400 parts, dispersant 1-5 parts, anti-settling agent 1-3 parts, plasticizer 1-5 parts, vulcanizing agent 1-10 parts, catalyst 0.1-2 parts.

[0009] In the first aspect of the present application, as a preferred embodiment, the nickel content of the nickel-plated layer of the nickel-plated carbon nanotubes is ≥90%, and the nickel-plated carbon nanotubes are prepared by a chemical nickel plating process, which comprises the following steps in sequence: Oscillation step: ultrasonic oscillation of the carbon nanotubes in deionized water for 30 min; Sensitization step: sensitization of the carbon nanotubes in an acidic solution containing Sn 2+ for 20-40 min; Activation step: activation of the carbon nanotubes in an acidic solution containing Pd 2+ for 20-40 min; Nickel plating step: nickel plating of the carbon nanotubes in a chemical plating solution with pH=8-9 and temperature 48-52℃, and the reaction is ended when 900-1000 mL of the chemical plating solution is consumed per 1 g of the carbon nanotubes.

[0010] In the first aspect of the present application, as a preferred embodiment, the chemical plating solution comprises: NiSO4: 20-40 g / L; reducing agent: 20-40 g / L; complexing agent: 50-80 g / L; surfactant: 1.3-1.7 g / L; and the balance is water.

[0011] The surfactant is one of sodium dodecyl sulfonate, sodium dodecyl sulfate and sodium dioctyl succinate sulfonate; The complexing agent is one of sodium citrate, disodium EDTA and triethanolamine; The reducing agent is NaH2PO2.

[0012] In the first aspect of the present application, as a preferred embodiment, the organic silicone resin is one or a mixture of two or more of silicone resin with viscosity of 100-500000, 107 glue and silicone oil.

[0013] In the first aspect of the present application, as a preferred embodiment, the dispersant is one or a mixture of two or more of PVP, hydroxymethyl cellulose, polyethylene glycol, Si69, BYK110 and BYK2155.

[0014] In the first aspect of the present application, as a preferred embodiment, the anti-settling agent includes one or a mixture of two or more of polyethylene wax paste, talc, organic bentonite, diatomite, BYK302 and BYK163.

[0015] In the first aspect of the present application, as a preferred embodiment, the plasticizer is one or a mixture of two or more of paraffin oil, white oil, dimethyl silicone oil, DOP and epoxy soybean oil.

[0016] In the first aspect of the present application, as a preferred embodiment, the vulcanizing agent is one or a mixture of two or more of 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane, 2,4-dichlorobenzoyl peroxide, hydrogen-containing silicone oil, tetraethyl orthosilicate and vinyl tributyl ketoxime silane.

[0017] In the first aspect of the present application, as a preferred embodiment, the catalyst is one or a mixture of two or more of dibutyltin dilaurate and platinum gold catalyst.

[0018] The second aspect of the present application provides a preparation method of an electromagnetic shielding adhesive composition, comprising the following steps: S10, preparing component A: mixing the organic silicone resin, conductive filler, dispersant, vulcanizing agent in a planetary mixer at a speed of 400-1500 rpm for 1-3 hours under vacuum; the vacuum degree of the vacuum mixing is ≤0.1 MPa, and the mixing temperature is ≤30℃; S20, preparing component B: mixing the anti-settling agent, plasticizer, catalyst in a planetary mixer at a speed of 400-1500 rpm for 1-3 hours under vacuum; the vacuum degree of the vacuum mixing is ≤0.1 MPa, and the mixing temperature is ≤30℃; S30, uniformly mixing component A and component B through a static mixer.

[0019] Compared with the prior art, the present application has the following advantages: 1、The nickel-plated carbon nanotube of the present application constructs a dense conductive network, and the shielding effectiveness can reach more than 90dB, which is significantly improved compared with the traditional carbon nanotube adhesive (20-40dB). The surface nickel plating reduces the BET value of the carbon nanotube, and uniform dispersion is achieved in cooperation with the dispersing agent, so as to avoid the failure of the conductive network. The anti-settling agent inhibits the settling of the filler, the plasticizer has good compatibility with the matrix, and there is no problem of delamination and oil seepage during long-term storage. The organic silicone resin and the nickel-plated carbon nanotube synergistically act to firmly bond metal, plastic and other substrates, and are resistant to high and low temperatures and external force impact. In this way, the present application solves the problems of dispersion difficulty, poor conductivity, low shielding effectiveness, easy settling of fillers and easy oil seepage of existing electromagnetic shielding adhesives, and realizes the characteristics of stable conductivity, high shielding effectiveness, large bonding force, no oil seepage, long storage period and stable performance index, so as to meet the strict requirements of different fields on electromagnetic shielding.

[0020] 2、The preparation method of the present application uniformly mixes the components through the strong stirring of the planetary mixer and the vacuum operation, so as to ensure the consistency and stability of the adhesive quality. The conductive filler is effectively dispersed, and the preliminary construction of the conductive network is promoted, which lays a foundation for obtaining good conductivity and electromagnetic shielding performance in the future. At the same time, the adverse effects of factors such as air bubble introduction and excessive temperature on the performance of the adhesive are avoided. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall process of the preparation method of the present application; Figure 2 It is a scanning electron microscope (SEM) image of the nickel-plated carbon nanotube of the present application, with a magnification of 10000 times; Figure 3 It is another scanning electron microscope (SEM) image of the nickel-plated carbon nanotube of the present application, with a magnification of 100000 times. DETAILED DESCRIPTION

[0022] In the following, the application will be further described in conjunction with the drawings and specific embodiments. It should be noted that the embodiments described below or the technical features between them can be combined in any way to form new embodiments, provided that there is no conflict. Unless otherwise specified, the materials and equipment used in the embodiments can be purchased from the market. The examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation on the present application.

[0023] In the description of the application, it is to be understood by the orientations or positional relationships indicated by the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In the description of the application, the meaning of "a plurality of" is two or more, unless otherwise specifically specified and limited.

[0024] In the description of the application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "communicated", "connected" should be understood in a broad sense, for example, it can be connected, or connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0025] The terms "first", "second", and the like in the specification and claims of the application and the above drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0026] The first aspect of the embodiment is to provide an electromagnetic shielding adhesive composition, comprising the following components by weight parts: 100 parts of silicone resin, 100-400 parts of conductive filler, 0.1-10 parts of dispersing agent, 0-10 parts of anti-settling agent, 0.1-10 parts of plasticizer, 1-20 parts of vulcanizing agent, 0.1-2 parts of catalyst; The conductive filler comprises nickel-plated carbon nanotubes.

[0027] On the basis of the above scheme, the nickel-plated carbon nanotubes are used to replace the carbon nanotube powder, and the nickel-plated carbon nanotubes have excellent conductivity, and the dense conductive network constructed in the adhesive can efficiently absorb and reflect electromagnetic waves. When the electromagnetic waves are incident, the electrons oscillate in the network to produce strong skin effect and reflection loss, and a large amount of electromagnetic wave energy is converted into heat energy, so that the shielding efficiency of the adhesive can reach more than 90 dB, compared with the traditional carbon nanotube conductive adhesive (20-40 dB), the electromagnetic shielding demand of high-end electronic equipment can be better met. Meanwhile, the excellent conductivity also significantly improves the overall conductive performance of the composite material. The nickel-plated carbon nanotubes are prepared by surface nickel plating modification, which reduces the BET, effectively solves the problem of difficult dispersion of the carbon nanotube nanomaterial in the preparation of conductive slurry, and makes the nickel-plated carbon nanotubes uniformly dispersed in the adhesive system to form a stable conductive network. In addition, the addition of the anti-settling agent inhibits the problem that the nickel-plated carbon nanotubes are prone to sedimentation in the long-term storage process due to the large density after the plasticizer improves the flowability of the adhesive, and ensures the stability of the adhesive system in the storage and use process. The silicone resin serves as an adhesive matrix, provides basic adhesion due to its unique molecular structure and performance, the plasticizer improves the flexibility and wettability of the base material, so that the base material can better adhere to the surface of the base material, and the crosslinked structure formed by the vulcanizing agent and the catalyst enhances the cohesive force of the adhesive and improves the overall strength. Meanwhile, the nickel-plated carbon nanotubes not only do not have a negative impact on the bonding performance, but also have a certain reinforcing effect, and cooperates with other components to make the adhesive firmly bond various substrates such as metals, plastics and composites, and still maintains good bonding effect under external force, temperature change and the like, thereby protecting the integrity of the electromagnetic shielding structure. The content of the plasticizer is strictly controlled in the present application, so that the molecules are reasonably distributed between the molecular chains of the silicone resin, the flexibility and plasticity of the adhesive are improved, and the imbalance of the internal structure of the adhesive caused by excessive free molecules is avoided, thereby effectively avoiding the oil seepage problem and ensuring the appearance quality and use performance of the adhesive in the actual production and use process. The anti-settling agent of the present application maintains the stability of the system and prevents the nickel-plated carbon nanotubes from settling; the dispersant ensures uniform dispersion of the filler; the vulcanizing agent and the catalyst fully react to form a stable crosslinked network, and the good compatibility between the components avoids separation, deterioration and the like. Meanwhile, the preparation process of the nickel-plated carbon nanotubes ensures the stability of its own performance, and these factors jointly make the adhesive still maintain stable performance after long-term storage, so that frequent detection and adjustment are not needed, the management cost and quality risk in the production, transportation and storage process are reduced, and the market competitiveness of the product is improved.

[0028] In a first aspect of the invention, as a preferred embodiment, the electromagnetic shielding adhesive composition comprises the following components by weight: 100 parts of silicone resin, 100-400 parts of conductive filler, 1-5 parts of dispersant, 1-3 parts of anti-settling agent, 1-5 parts of plasticizer, 1-10 parts of vulcanizing agent, and 0.1-2 parts of catalyst.

[0029] In a first aspect of the present invention, as a preferred embodiment, the nickel content of the nickel plating layer of the nickel-plated carbon nanotube is ≥90%.

[0030] In a first aspect of the present invention, as a preferred embodiment, the nickel-plated carbon nanotubes are prepared by a chemical nickel plating process, comprising the following steps: Shaking step: Place the carbon nanotubes in deionized water and ultrasonically shake for 20-40 minutes to make the carbon nanotubes evenly dispersed in the water; Sensitization step: placing carbon nanotubes in a Sn-containing environment 2+ Sensitize in an acidic solution for 20-40 minutes to eliminate amorphous impurities and catalysts, allowing carbon nanotubes to carry oxygen-containing functional groups; Activation step: Carbon nanotubes are placed in a Pd-containing environment. 2+ Activate CNTs in an acidic solution for 20-40 minutes to complete the activation process; Nickel plating step: Carbon nanotubes are plated with nickel in a chemical plating solution with pH=8-9 and temperature 48-52℃. The nickel plating reaction ends when 900-1000 mL of chemical plating solution is consumed per 1g of carbon nanotubes. Elemental nickel has catalytic activity for the nickel plating reaction and possesses self-catalytic properties, so the nickel plating reaction can continue, resulting in uniform nickel particle coating of CNTs.

[0031] In a first aspect of the present invention, as a preferred embodiment, the chemical plating solution comprises: NiSO4: 20-40 g / L; reducing agent: 20-40 g / L; complexing agent: 50-80 g / L; surfactant: 1.3-1.7 g / L; and the balance being water.

[0032] The surfactant is one of sodium dodecyl sulfonate, sodium dodecyl sulfate, and sodium dioctyl succinate sulfonate; The complexing agent is one of sodium citrate, disodium EDTA, and triethanolamine; The reducing agent is NaH2PO2.

[0033] In a first aspect of the present invention, as a preferred embodiment, the silicone resin is one or a mixture of two or more of silicone resin, 107 glue and silicone oil with a viscosity of 100-500000.

[0034] As a matrix material for adhesives, it provides basic bonding properties. The silicon-oxygen bonds in its molecular structure endow the adhesive with good flexibility, resistance to high and low temperatures, and chemical stability. In the entire adhesive system, silicone resin encapsulates and fixes other components, allowing each component to work synergistically to form a stable adhesive system, laying the foundation for achieving good adhesion and overall performance.

[0035] In a first aspect of the invention, as a preferred embodiment, the dispersant is one or a mixture of two or more of PVP, hydroxymethyl cellulose, polyethylene glycol, Si69, BYK110 and BYK2155.

[0036] These dispersant molecules possess a unique structure: one end adsorbs onto the surface of the conductive filler (nickel-plated carbon nanotube powder), while the other end exhibits good compatibility with the silicone resin matrix. Through this adsorption, the dispersant forms a protective film on the surface of the conductive filler particles, reducing the surface energy between particles and preventing aggregation. Simultaneously, the dispersant ensures uniform distribution of the conductive filler particles within the silicone resin matrix, promoting the effective construction of the conductive network. This effectively improves the dispersibility of the conductive filler in the silicone resin matrix, allowing for a more uniform distribution and optimizing the formation of the conductive network. This contributes to further improving the conductivity and electromagnetic shielding performance of the adhesive, and with increasing nickel-plated carbon nanotube powder content, the volume resistivity and shielding effectiveness are further improved.

[0037] In a first aspect of the invention, as a preferred embodiment, the anti-settling agent comprises one or a mixture of two or more of polyethylene wax paste, talc powder, organobentonite, diatomaceous earth, BYK302 and BYK163.

[0038] These anti-settling agents can form a spatial network structure in the adhesive system or increase the viscosity of the system, thus hindering the sedimentation of conductive fillers (nickel-plated carbon nanotube powder). For example, thixotropic anti-settling agents such as organobentonite, after being removed by applied shear force, gradually restore their network structure at an appropriate rate through hydrogen bonding, providing support and barrier for the nickel-plated carbon nanotube powder and preventing it from settling due to gravity. Fumed silica and other materials have special structures that can form a three-dimensional network structure in the system, preventing the material from settling. This suppresses the sedimentation problem of nickel-plated carbon nanotube powder during adhesive storage, ensuring the performance stability of the adhesive during long-term storage and extending the shelf life.

[0039] In a first aspect of the invention, as a preferred embodiment, the plasticizer is one or a mixture of two or more of paraffin oil, white oil, dimethyl silicone oil, DOP, and epoxidized soybean oil. Plasticizers improve the flowability of adhesives, but excessive plasticizers reduce the viscosity of the system. Due to their high density, nickel-plated carbon nanotubes are prone to sedimentation during long-term storage; therefore, anti-settling agents are added to suppress the sedimentation problem of nickel-plated carbon nanotube powder.

[0040] In a first aspect of the invention, as a preferred embodiment, the vulcanizing agent is one or a mixture of two or more of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,4-dichlorobenzoyl peroxide, hydrogen-containing silicone oil, tetraethyl orthosilicate, and vinyltributylone oxime silane.

[0041] Under certain conditions, vulcanizing agents can chemically react with silicone resin molecules, forming cross-linked structures between the molecular chains. Taking hydrogen-containing silicone oil as an example, the Si-H bonds in its molecules can undergo addition reactions with active groups such as vinyl groups in silicone resin molecules under the action of a catalyst, thereby forming chemical bonds between molecular chains and constructing a three-dimensional network structure. Through the cross-linking reaction, the strength, hardness, and abrasion resistance of the cured adhesive are improved, enhancing the cohesive strength of the adhesive and enabling it to better withstand external forces, ensuring the reliability and durability of the adhesive during use.

[0042] In a first aspect of the present invention, as a preferred embodiment, the catalyst is one or a mixture of two or more of dibutyltin dilaurate and platinum catalyst.

[0043] Catalysts can lower the activation energy of the reaction between vulcanizing agents and silicone resins, accelerating the reaction rate and allowing the vulcanization reaction to proceed under milder conditions. For example, platinum catalysts in the crosslinking reaction of hydrogen-containing silicone oil and silicone resins can promote the addition reaction between Si-H bonds and vinyl groups, significantly shortening the reaction time and improving production efficiency. Ensuring that the vulcanization reaction proceeds quickly and completely allows the adhesive to cure in a shorter time and reach the expected performance indicators, improving production efficiency while guaranteeing the stability of adhesive product quality.

[0044] Please refer to Figure 1 A second aspect of the present invention provides a method for preparing an electromagnetic shielding adhesive composition, comprising the following steps: S10. Preparation of component A: The organosilicon resin, conductive filler, dispersant, and vulcanizing agent are mixed in a planetary mixer at a speed of 400-1500 rpm under vacuum for 1-3 hours; the vacuum degree of the vacuum mixing is ≤0.1MPa, and the mixing temperature is ≤30℃. S20. Preparation of component B: The anti-settling agent, plasticizer, and catalyst are mixed in a planetary mixer at a speed of 400-1500 rpm under vacuum for 1-3 hours; the vacuum degree of the vacuum mixing is ≤0.1MPa, and the mixing temperature is ≤30℃. S30. Mix component A and component B evenly using a static mixer.

[0045] Based on the above scheme, the planetary mixer provides efficient mixing, ensuring thorough mixing of all components. The vacuum environment eliminates air from the system, preventing the introduction of air bubbles during mixing and thus avoiding negative impacts on adhesive performance. Simultaneously, the vacuum environment facilitates better dispersant action and promotes the dispersion of conductive fillers, as dispersant molecules are more easily adsorbed onto the surface of the conductive fillers and distributed uniformly in the absence of air interference. The powerful mixing and vacuum operation of the planetary mixer ensure uniform mixing of all components, guaranteeing the consistency and stability of the adhesive quality. It effectively disperses the conductive fillers, promoting the initial construction of the conductive network and laying the foundation for achieving good conductivity and electromagnetic shielding performance. Furthermore, it avoids the adverse effects of air bubble introduction and excessively high temperatures on adhesive performance.

[0046] When components A and B pass through the static mixer, the two components are continuously divided, combined, and then divided again by the mixing elements inside, achieving thorough mixing. This mixing method requires no additional power drive, relying solely on the pressure of the fluid itself. It ensures effective mixing while avoiding damage to the adhesive system caused by excessive shear forces from mechanical stirring. The static mixer also ensures that the vulcanizing agent and catalyst are evenly distributed throughout the adhesive system, guaranteeing uniform curing during the subsequent curing process. This further ensures the homogeneity of the adhesive components, allowing the vulcanizing agent and catalyst to fully function throughout the system, promoting uniform curing and resulting in electromagnetic shielding adhesive products with consistent performance. This mixing method is simple, efficient, and does not cause any additional adverse effects on the adhesive system, contributing to improved production efficiency and product quality.

[0047] Controlling the mixing temperature to ≤30℃ is to prevent some components from undergoing chemical reactions or changes in performance due to excessively high temperatures during the mixing process. For example, it can prevent premature reactions of the vulcanizing agent and thermal degradation of the silicone resin. Controlling the vacuum degree to ≤0.1MPa ensures the effectiveness of the vacuum environment and meets the requirements of the mixing process.

[0048] The following are some embodiments listed in this application, which further illustrate this application.

[0049] Example 1

[0050] This embodiment provides an electromagnetic shielding adhesive composition comprising the following components by weight: 100 parts of silicone resin, 400 parts of conductive filler, 1 part of dispersant, 1 part of anti-settling agent, 3 parts of plasticizer, 3 parts of vulcanizing agent, and 0.5 parts of catalyst. The conductive filler includes nickel-plated carbon nanotubes, and the nickel content of the nickel plating layer of the nickel-plated carbon nanotubes is 90%.

[0051] The organosilicon resin is silicone oil, the dispersant is PVP, the anti-settling agent includes polyethylene wax paste, the plasticizer is paraffin oil, the vulcanizing agent is hydrogen-containing silicone oil, and the catalyst is a platinum catalyst.

[0052] The nickel-plated carbon nanotubes are prepared by a chemical nickel plating process, which includes the following steps: Shaking procedure: Place the carbon nanotubes in deionized water and ultrasonically shake for 30 minutes; Sensitization step: placing carbon nanotubes in a Sn-containing environment 2+ Sensitize in an acidic solution for 30 minutes; Activation step: Carbon nanotubes are placed in a Pd-containing environment. 2+ Activate in an acidic solution for 30 minutes; Nickel plating step: Carbon nanotubes are plated with nickel in a chemical plating solution with pH=8.5 and temperature of 50℃. The nickel plating reaction ends when 1000mL of chemical plating solution is consumed for every 1g of carbon nanotubes, and nickel-plated carbon nanotubes are obtained.

[0053] The electroless plating solution comprises: NiSO4: 30 g / L; reducing agent: 30 g / L; complexing agent: 65 g / L; surfactant: 1.5 g / L; and the balance is water. The surfactant is sodium dodecyl sulfonate; the complexing agent is sodium citrate; and the reducing agent is NaH2PO2.

[0054] A method for preparing an electromagnetic shielding adhesive composition includes the following steps: S10. Preparation of component A: Organosilicon resin, conductive filler, dispersant, and vulcanizing agent are mixed in a planetary mixer at 1000 rpm under vacuum for 2 hours; the vacuum degree of the vacuum mixing is ≤0.1MPa, and the mixing temperature is ≤30℃. S20. Preparation of component B: The anti-settling agent, plasticizer, and catalyst are mixed in a planetary mixer at 1000 rpm under vacuum for 2 hours; the vacuum degree of the vacuum mixing is ≤0.1MPa and the mixing temperature is ≤30℃. S30. Mix component A and component B evenly using a static mixer.

[0055] Reference Figure 2 Nickel is coated on the surface of carbon nanotubes in the form of nanoparticles; Reference Figure 3The nickel-plated carbon nanotubes exhibit a three-dimensional interwoven structure.

[0056] The performance of the electromagnetic shielding adhesive composition of Example 1 is shown in Table 1.

[0057] Table 1

[0058] Based on Example 1 above, the effect of different weight parts of conductive filler (nickel-plated carbon nanotubes) on the properties of the adhesive composition was further investigated. In this process, different weight parts of nickel-plated carbon nanotubes were used, but other conditions remained consistent with Example 1. The specific performance of the adhesive composition is shown in Table 2.

[0059] Table 2

[0060] As can be seen from Table 2, with the increase of the nickel-plated carbon nanotube powder content, the volume resistivity and shielding effectiveness are improved, the overlap shear strength is reduced, the oil permeability is also improved, and no delamination phenomenon is observed after 6 months of storage.

[0061] Based on Example 1 above, the effect of conductive fillers (nickel-plated carbon nanotubes) with different nickel contents on the properties of the adhesive composition was further investigated. In this process, nickel-plated carbon nanotubes with different nickel contents were used, but other conditions remained consistent with Example 1. The specific performance of the adhesive composition is shown in Table 3.

[0062] Table 3

[0063] As can be seen from Table 3, when the nickel content of carbon nanotubes is fixed at 400g, the conductivity improves, the volume resistivity and shielding effectiveness are improved, and the oil permeability deteriorates as the nickel content increases. When the nickel content exceeds 92%, stratification occurs after 6 months of storage.

[0064] Based on Example 1 above, the effect of different weight parts of dispersant on the properties of the adhesive composition was further investigated. In this process, different weight parts of dispersant were used, but other conditions remained consistent with Example 1. The specific properties of the adhesive composition are shown in Table 4.

[0065] Table 4

[0066] As shown in Table 4, with the increase of dispersant content, the filler dispersibility improves, and the overlap shear strength first increases and then decreases because excessive dispersant will migrate to the surface; similarly, the oil permeability of the system first decreases and then increases; the system resistance first decreases and then increases because with the increase of dispersant, the powder is dispersed evenly, the conductive network is well constructed, and the conductivity is good, but with the addition of excessive dispersant, the conductivity deteriorates; adding an appropriate amount of dispersant has a certain dust-prevention effect.

[0067] Based on Example 1 above, the effect of different weight parts of anti-settling agent on the performance of the adhesive composition was further investigated. In this process, different weight parts of anti-settling agent were used, but other conditions remained consistent with Example 1. The specific performance of the adhesive composition is shown in Table 5.

[0068] Table 5

[0069] As shown in Table 5, with the increase of anti-settling agent content, the lap shear strength first increases and then decreases, the oil permeability first decreases and then increases, and the conductivity and shielding effectiveness also first improve and then deteriorate. Without anti-settling agent, there is stratification. With the increase of anti-settling agent content, there is a significant inhibition of sedimentation. There is no stratification after 6 months of storage. However, when the amount of anti-settling agent added exceeds 8 parts, stratification will occur again due to excessive anti-settling agent.

[0070] Based on Example 1 above, the effect of different weight parts of plasticizer on the properties of the adhesive composition was further investigated. In this process, different weight parts of plasticizer were used, but other conditions remained consistent with Example 1. The specific properties of the adhesive composition are shown in Table 6.

[0071] Table 6

[0072] As can be seen from Table 6, with the increase of plasticizer content, the lap shear strength gradually decreases, the oil permeability gradually increases, and the conductivity and shielding effectiveness gradually deteriorate. When the plasticizer content is low, there is no stratification phenomenon, but as the plasticizer content increases, significant stratification occurs when it exceeds 8 parts.

[0073] Based on Example 1 above, the effect of different weight parts of vulcanizing agent on the properties of the adhesive composition was further investigated. In this process, different weight parts of vulcanizing agent were used, but other conditions remained consistent with Example 1. The specific properties of the adhesive composition are shown in Table 7.

[0074] Table 7

[0075] As can be seen from Table 7, when the vulcanizing agent content is low, the system is not solidified and does not form, and there is obvious oil seepage; when the amount of vulcanizing agent added exceeds 1 part, the system begins to solidify, with slight oil seepage. At this time, the oil seepage value increases with the increase of vulcanizing agent content; as the vulcanizing agent content increases, the conductivity and shielding effectiveness of the conductive network gradually improve, but when the vulcanizing agent is excessive, the conductivity and shielding effectiveness gradually deteriorate, and delamination begins to occur.

[0076] Based on Example 1 above, the effect of different parts by weight of catalyst on the properties of the adhesive composition was further investigated. In this process, different parts by weight of catalyst were used, but other conditions remained consistent with Example 1. The specific properties of the adhesive composition are shown in Table 8.

[0077] Table 8

[0078] As can be seen from Table 8, with the increase of catalyst content, the lap shear strength increases, the oil penetration value gradually decreases, and the conductivity and shielding effectiveness are improved. However, excessive catalyst will cause stratification.

[0079] Example 2: The only difference between this embodiment and Example 1 is that the silicone resin is silicone oil, the dispersant is hydroxymethyl cellulose, the anti-settling agent includes talc, the plasticizer is white oil, the vulcanizing agent is tetraethyl orthosilicate, and the catalyst is dibutyltin dilaurate. Everything else is the same as in Example 1.

[0080] The performance of the electromagnetic shielding adhesive composition of Example 2 is shown in Table 9.

[0081] Table 9

[0082] Comparative Example 1: The difference between this comparative example and Example 1 is that conventional carbon nanotubes are used instead of nickel-plated carbon nanotubes. Everything else is the same as in Example 1.

[0083] The performance of the electromagnetic shielding adhesive composition of Comparative Example 1 is shown in Table 10.

[0084] Table 10

[0085] As can be seen from Tables 10 and 1, nickel plating on carbon nanotubes improves the dispersion of carbon nanotubes, increases the lap shear strength and oil permeability, and improves conductivity and shielding effectiveness due to the increased nickel content.

[0086] Although only certain components and embodiments of this application have been illustrated and described, many modifications and alterations will be apparent to those skilled in the art without actually departing from the scope and spirit of the claims, such as variations in the size, dimensions, structure, shape and proportion of the various elements, installation arrangement, material use, color, orientation, etc.

[0087] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. An electromagnetic shielding adhesive composition characterized by, A silicone resin 100 parts by weight, an electrically conductive filler 100-400 parts by weight, a dispersing agent 0.1-10 parts by weight, an anti-settling agent 0-10 parts by weight, a plasticizer 0.1-10 parts by weight, a vulcanizing agent 1-20 parts by weight, and a catalyst 0.1-2 parts by weight. The electrically conductive filler comprises nickel-plated carbon nanotubes.

2. The electromagnetic shielding adhesive composition of claim 1, wherein, A silicone resin 100 parts by weight, an electrically conductive filler 100-400 parts by weight, a dispersing agent 1-5 parts by weight, an anti-settling agent 1-3 parts by weight, a plasticizer 1-5 parts by weight, a vulcanizing agent 1-10 parts by weight, and a catalyst 0.1-2 parts by weight.

3. The electromagnetic shielding adhesive composition of claim 1, wherein, The nickel content of the nickel-plated layer of the nickel-plated carbon nanotube is greater than or equal to 90%, and the nickel-plated carbon nanotube is prepared by a chemical nickel plating process and sequentially comprises the following steps: An oscillation step: placing the carbon nanotube in deionized water and ultrasonically oscillating for 30 minutes; Sensitization step: Carbon nanotubes were sensitized in an acidic solution containing Sn 2+ for 20-40 minutes; Activation step: Carbon nanotubes are activated in an acidic solution containing Pd 2+ for 20-40 minutes; A nickel plating step: plating nickel on the carbon nanotube in a chemical plating solution with a pH of 8-9 and a temperature of 48-52°C, and the nickel plating ends when 900-1000 mL of the chemical plating solution is consumed per 1 g of the carbon nanotube.

4. The electromagnetic shielding adhesive composition of claim 3, wherein The chemical plating solution comprises: NiSO4: 20-40 g / L; a reducing agent: 20-40 g / L; a complexing agent: 50-80 g / L; a surfactant: 1.3-1.7 g / L; and the balance is water.

5. The electromagnetic shielding adhesive composition of claim 1, wherein, The silicone resin is one or a mixture of two or more of a silicone resin with a viscosity of 100-500000, a 107 glue, and a silicone oil.

6. The electromagnetic shielding adhesive composition of claim 1, wherein The dispersing agent is one or a mixture of two or more of PVP, hydroxymethyl cellulose, polyethylene glycol, Si69, BYK110, and BYK2155.

7. The electromagnetic shielding adhesive composition of claim 1, wherein The anti-settling agent comprises one or a mixture of two or more of polyethylene wax paste, talc, organic bentonite, diatomite, BYK302, and BYK163.

8. The electromagnetic shielding adhesive composition of claim 1, wherein, The plasticizer is one or a mixture of two or more of paraffin oil, white oil, dimethyl silicone oil, DOP, and epoxy soybean oil.

9. The electromagnetic shielding adhesive composition of claim 1, wherein, The vulcanizing agent is one or a mixture of two or more of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,4-dichlorobenzoyl peroxide, hydrogen-containing silicone oil, tetraethyl orthosilicate, and vinyl tributyl ketoxime silane; and the catalyst is one or a mixture of two or more of dibutyltin dilaurate and platinum gold catalyst.

10. A process for producing the electromagnetic shielding adhesive composition according to any one of claims 1 to 9, characterized by, The method comprises the following steps: S10, preparing component A: mixing the silicone resin, the electrically conductive filler, the dispersing agent, and the vulcanizing agent in a planetary mixer at a rotation speed of 400-1500 rpm for 1-3 hours under vacuum; the vacuum degree of the vacuum mixing is less than or equal to 0.1 MPa, and the mixing temperature is less than or equal to 30°C; S20, preparing component B: mixing the anti-settling agent, the plasticizer, and the catalyst in a planetary mixer at a rotation speed of 400-1500 rpm for 1-3 hours under vacuum; the vacuum degree of the vacuum mixing is less than or equal to 0.1 MPa, and the mixing temperature is less than or equal to 30°C; S30, uniformly mixing component A and component B through a static mixer.

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