Electromagnetic shielding adhesive for medium and high frequency bands, preparation method therefor, and use method therefor

Abstract

The present invention belongs to the technical field of electromagnetic shielding adhesives, and specifically relates to an electromagnetic shielding adhesive for medium and high frequency bands, a preparation method therefor, and a use method therefor. The electromagnetic shielding adhesive for medium and high frequency bands is composed of the following components in parts by mass: 8-18 parts of polyvinyl alcohol, 6-12 parts of nano silver powder, 3-8 parts of submicron silver powder, 12-20 parts of graphene oxide, 0.5-1.2 parts of a coupling agent, and 22-30 parts of deionized water. The present invention provides an electromagnetic shielding adhesive for medium and high frequency bands, which not only has good electromagnetic shielding performance, but also is far lower in costs than existing conductive silver adhesives.

Description

A medium and high frequency electromagnetic shielding adhesive and its preparation method and use method Technical Field

[0001] The invention belongs to the technical field of electromagnetic shielding adhesives, and in particular relates to a medium- and high-frequency band electromagnetic shielding adhesive and a preparation method thereof. Background Art

[0002] The modern age is an era of electronic information, and various electrical devices continuously generate various electromagnetic radiations. This is especially true of the ubiquitous consumer electronics we all have, such as mobile phones, smartwatches, and drones. Radiation from these products is primarily concentrated in the 750MHz-30GHz frequency band. If left uncontrolled, these radiations can interfere with each other, leading to device malfunction or even more serious consequences. Consequently, many components are required to shield against these electromagnetic radiations, or even shield against the electromagnetic radiation they generate themselves.

[0003] In the prior art, electromagnetic radiation is generally addressed by adding a metal shield or applying an electromagnetic shielding coating to achieve electromagnetic shielding. These two methods generally have the following drawbacks:

[0004] 1. Shielding method with additional metal shielding cover: high cost, complex implementation, and large size.

[0005] 2. Shielding method using electromagnetic shielding coating: Conventional electromagnetic shielding coatings can only shield signals between 750MHz and 4GHz. To shield signals above 4GHz, conductive silver paste is often required as an electromagnetic shielding coating. Since over 90% of conductive silver paste is pure silver powder, it is generally expensive and difficult to promote and apply in ordinary consumer electronics. Even if conductive silver paste is used regardless of cost, the silver paste coating process often requires high-temperature curing at temperatures above 180°C, which is unbearable for many electronic products, thus severely limiting the scope of application of conductive silver paste.

[0006] In summary, developing a technology that can effectively solve the cost and solidification problems of electromagnetic shielding is of epoch-making significance for promoting the development of modern information.

[0007] Summary of the Invention

[0008] In order to address the deficiencies of the prior art, the present invention provides a medium- and high-frequency electromagnetic shielding adhesive, which uses nano silver powder and submicron silver powder of a specific form as the base material. With the assistance of polyvinyl alcohol and a coupling agent, an electrical path with silver as the core can be formed in the liquid phase. At the same time, graphene oxide that is soluble in water is used as a filler. On the one hand, since graphene oxide itself is an excellent conductor, it can reduce the resistance of the system and form a composite synergistic effect with the electrical path formed by silver, so that the system as a whole can have good electromagnetic shielding performance; and graphene itself has good electromagnetic absorption capacity, which can further improve the shielding ability of the shielding adhesive. On the other hand, since the price of graphene is much lower than that of silver, and the amount of silver used in this system is also much less than that in the conductive silver adhesive of the prior art, the cost of this shielding adhesive is much lower than that of the existing conductive silver adhesive.

[0009] Furthermore, the mid- and high-frequency electromagnetic shielding adhesive of this invention uses nano- and submicron silver powders as base materials in a water-based system, with graphene oxide as a filler. Therefore, compared to conventional conductive gels containing approximately 90% silver powder, the adhesive layer typically requires lower temperatures and shorter curing times during use. Furthermore, polyvinyl alcohol acts as both a dispersant and a solvent in this system, providing excellent coating properties.

[0010] The technical effects to be achieved by the present invention are achieved through the following technical solutions:

[0011] The medium and high frequency electromagnetic shielding adhesive of the present invention is composed of the following components and their mass fractions:

[0012] Furthermore, the medium and high frequency electromagnetic shielding adhesive is composed of the following components and their weight proportions:

[0013] Furthermore, the polyvinyl alcohol has a degree of polymerization of 3000-4500, a degree of alcoholysis of 85 mol%-90 mol%, and a viscosity of 4% aqueous solution of 6.0 mPa·S-8.0 mPa·S.

[0014] Furthermore, the nano silver powder has a spherical structure with a diameter D50 of 30nm-50nm and a diameter D100 of 80nm-100nm.

[0015] Furthermore, the submicron silver powder is a flake structure with a width-to-thickness ratio of (8-20):1.

[0016] Furthermore, the submicron silver powder has a diameter D50 of 150nm-300nm and a diameter D100 of 600um-900um.

[0017] Furthermore, the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 um to 3 um.

[0018] Furthermore, the coupling agent is a silane coupling agent, including one or more of KH550, KH560, KH570, KH792, DL602, and DL171.

[0019] The method for preparing the medium and high frequency electromagnetic shielding adhesive of the present invention comprises the following steps:

[0020] S01, add deionized water and heat to 70℃;

[0021] S02, add polyvinyl alcohol, maintain the temperature and stir until completely dissolved;

[0022] S03, add coupling agent, maintain temperature and stir to mix evenly;

[0023] S04, sequentially add nano silver powder and submicron silver powder, keep warm and stir until evenly dispersed;

[0024] S05, adding graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0025] S06. Cool to room temperature and store in a sealed container to obtain the medium and high frequency electromagnetic shielding adhesive.

[0026] The method for using the medium and high frequency electromagnetic shielding adhesive of the present invention comprises the following steps:

[0027] S10. Apply 10um-80um of high thixotropic insulating glue on the surface of the shielded object and bake at a temperature of 80℃-150℃ for no more than 25 minutes;

[0028] S20, coating the medium and high frequency band electromagnetic shielding adhesive with a thickness of 30 μm to 180 μm on the surface of the formed high thixotropic insulating adhesive layer, and baking at a temperature of 80° C. to 150° C. for no more than 25 minutes;

[0029] S30, apply diluted high thixotropic insulating glue 0-30um on the surface of the material to be shielded, and bake at a temperature of 80℃-150℃ for no more than 25 minutes;

[0030] In steps S10 and S30, the thixotropic index of the highly thixotropic insulating adhesive is greater than 7, and the insulation retention time after immersion in artificial sweat is greater than 12 hours at a coating thickness of 100 μm;

[0031] In step S30, the highly thixotropic insulating adhesive is diluted 2-10 times with at least one of C1-C4 monohydric alcohols.

[0032] In summary, the present invention has at least the following benefits:

[0033] 1. The medium and high frequency electromagnetic shielding adhesive of the present invention uses nano silver powder and submicron silver powder of a specific form as the basic material. With the assistance of polyvinyl alcohol and a coupling agent, an electrical path with silver as the core can be formed in the liquid phase. At the same time, graphene oxide that is soluble in water is used as a filler. On the one hand, since graphene oxide itself is an excellent conductor, it can reduce the resistance of the system and form a composite synergistic effect with the electrical path formed by silver, so that the system as a whole can have good electromagnetic shielding performance; and graphene itself has good electromagnetic absorption capacity, which can further improve the shielding ability of the shielding adhesive. On the other hand, since the price of graphene is much lower than that of silver, and the amount of silver used in this system is also much less than that in the conductive silver adhesive of the prior art, the cost of this shielding adhesive is much lower than that of the existing conductive silver adhesive.

[0034] 2. The mid- and high-frequency electromagnetic shielding adhesive of this invention uses nano- and submicron silver powders as base materials in a water-based system, with graphene oxide as a filler. Therefore, compared to conventional conductive gels containing approximately 90% silver powder, it typically requires lower temperatures and shorter curing times. Furthermore, polyvinyl alcohol acts as both a dispersant and a solvent in this system, providing excellent coating properties.

[0035] 3. The method for preparing the medium and high frequency electromagnetic shielding adhesive of the present invention can realize the preparation of the medium and high frequency electromagnetic shielding adhesive by using simple temperature control and stirring methods, without the need for complicated operations, and the preparation method is simple and efficient.

[0036] 4. The method of using the medium and high frequency electromagnetic shielding adhesive in the present invention is combined with a high thixotropic insulating adhesive. The adhesive layer can be cured under a temperature of 150°C and within a curing time of 25 minutes. The curing temperature is low, the curing time is short, and the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a graph showing the shielding efficiency changes of the high-frequency electromagnetic shielding adhesive in the embodiment of the present invention and the commercially available conductive silver adhesive in the comparative example at different frequency bands. DETAILED DESCRIPTION

[0038] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be described more fully below with reference to specific embodiments. The present invention provides preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0039] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0040] As used herein, any reference to "one embodiment" or "an embodiment" means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" in multiple places in the specification are not necessarily all referring to the same embodiment.

[0041] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present disclosure shall have the meanings commonly understood by those of ordinary skill in the art. In addition, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0042] In a first aspect, the present invention provides a medium- and high-frequency electromagnetic shielding adhesive comprising the following components and their weight percentages: 8-18 parts polyvinyl alcohol, 6-12 parts nano-silver powder, 3-8 parts submicron silver powder, 12-20 parts graphene oxide, 0.5-1.2 parts coupling agent, and 22-30 parts deionized water. Preferably, the medium- and high-frequency electromagnetic shielding adhesive comprises the following components and their weight percentages: 12 parts polyvinyl alcohol, 10 parts nano-silver powder, 7 parts submicron silver powder, 14 parts graphene oxide, 0.9 parts coupling agent, and 22-30 parts deionized water.

[0043] Furthermore, the polyvinyl alcohol has a degree of polymerization of 3000-4500, a degree of alcoholysis of 85mol%-90mol%, and a 4% aqueous solution viscosity of 6.0mPa·s-8.0mPa·s. The nanosilver powder has a spherical structure with a diameter D50 of 30nm-50nm and a D100 of 80nm-100nm. The submicron silver powder has a flake structure with an aspect ratio of (8-20):1, a diameter D50 of 150nm-300nm, and a D100 of 600um-900um. The graphene oxide has a thickness of 0.55nm-1.2nm and a diameter of 0.5um-3um. The coupling agent is a silane coupling agent, including one or more of KH550, KH560, KH570, KH792, DL602, and DL171.

[0044] In a second aspect, the present invention provides a method for preparing a medium- and high-frequency electromagnetic shielding adhesive, comprising the following steps:

[0045] S01, add deionized water and heat to 70℃;

[0046] S02, add polyvinyl alcohol, maintain the temperature and stir until completely dissolved;

[0047] S03, add coupling agent, maintain temperature and stir to mix evenly;

[0048] S04, sequentially add nano silver powder and submicron silver powder, keep warm and stir until evenly dispersed;

[0049] S05, adding graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0050] S06. Cool to room temperature and store in a sealed container to obtain the medium and high frequency electromagnetic shielding adhesive.

[0051] In a third aspect, the present invention provides a method for using a medium- and high-frequency electromagnetic shielding adhesive, comprising the following steps:

[0052] S10. Apply 10um-80um of high thixotropic insulating glue on the surface of the shielded object and bake at a temperature of 80℃-150℃ for no more than 25 minutes;

[0053] S20, coating the medium and high frequency band electromagnetic shielding adhesive with a thickness of 30 μm to 180 μm on the surface of the formed high thixotropic insulating adhesive layer, and baking at a temperature of 80° C. to 150° C. for no more than 25 minutes;

[0054] S30, apply diluted high thixotropic insulating glue 0-30um on the surface of the material to be shielded, and bake at a temperature of 80℃-150℃ for no more than 25 minutes;

[0055] Preferably, in steps S10 and S30, the thixotropic index of the highly thixotropic insulating adhesive is greater than 7, and the insulation retention time after immersion in artificial sweat is greater than 12 hours at a coating thickness of 100 μm;

[0056] In step S30, the highly thixotropic insulating adhesive is diluted 2-10 times with at least one of C1-C4 monohydric alcohols.

[0057] In the following specific examples, the sources of the main raw materials and main equipment used are as follows:

[0058] Polyvinyl alcohol: Kuraray, Japan;

[0059] Nano silver powder: Ferro, USA;

[0060] Submicron silver powder: Ferro, USA;

[0061] Graphene oxide: Guangdong Innovation Materials (Shenzhen) Co., Ltd.

[0062] Coupling agent: Guangzhou Zhongjie New Materials Co., Ltd.

[0063] Example 1:

[0064] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 10 parts polyvinyl alcohol, 12 parts nanosilver powder, 7 parts submicron silver powder, 14 parts graphene oxide, 0.9 parts coupling agent, and 26 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 3000, a degree of alcoholysis of 85 mol%, and a viscosity of 6.0 mPa·s in a 4% aqueous solution; the nanosilver powder is spherical with a diameter D50 of 30 nm and a D100 of 80 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 150 nm, and a D100 of 600 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent is DL171.

[0065] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0066] S01, add 26 parts of deionized water to a glass reactor and heat to 70°C;

[0067] S02, add 10 parts of polyvinyl alcohol to the glass reactor, maintain the temperature and stir until completely dissolved;

[0068] S03, add 0.9 parts of coupling agent DL171 to the glass reactor, maintain the temperature and stir to mix evenly;

[0069] S04, sequentially add 12 parts of nano silver powder and 7 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0070] S05, adding 14 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0071] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding adhesive 1.

[0072] Example 2:

[0073] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 8 parts polyvinyl alcohol, 10 parts nanosilver powder, 4 parts submicron silver powder, 12 parts graphene oxide, 0.7 parts coupling agent, and 30 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 3500, a degree of alcoholysis of 90 mol%, and a 4% aqueous solution viscosity of 7.0 mPa·s; the nanosilver powder is spherical with a diameter D50 of 40 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 200 nm and a D100 of 700 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent is DL171.

[0074] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0075] S01, add 30 parts of deionized water to a glass reactor and heat to 70°C;

[0076] S02, add 8 parts of polyvinyl alcohol to the glass reactor, maintain the temperature and stir until completely dissolved;

[0077] S03, add 0.7 parts of coupling agent DL171 to the glass reactor, maintain the temperature and stir to mix evenly;

[0078] S04, sequentially add 10 parts of nano silver powder and 4 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0079] S05, adding 12 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0080] S06. Cool to room temperature, seal and store to obtain the medium and high frequency band electromagnetic shielding glue 2.

[0081] Example 3:

[0082] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components by mass: 18 parts polyvinyl alcohol, 6 parts nanosilver powder, 8 parts submicron silver powder, 19 parts graphene oxide, 1.1 parts coupling agent, and 22 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4000, a degree of alcoholysis of 90 mol%, and a viscosity of 8.0 mPa·s in a 4% aqueous solution; the nanosilver powder is spherical with a diameter D50 of 50 nm and a D100 of 100 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 250 nm and a D100 of 800 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent is DL171.

[0083] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0084] S01, add 22 parts of deionized water to a glass reactor and heat to 70°C;

[0085] S02, add 18 parts of polyvinyl alcohol to a glass reactor, maintain the temperature and stir until completely dissolved;

[0086] S03, add 1.1 parts of coupling agent DL171 to the glass reactor, maintain the temperature and stir to mix evenly;

[0087] S04, sequentially add 6 parts of nano silver powder and 8 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0088] S05, adding 19 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0089] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding glue 3.

[0090] Example 4:

[0091] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 12 parts polyvinyl alcohol, 10 parts nanosilver powder, 7 parts submicron silver powder, 14 parts graphene oxide, 0.9 parts coupling agent, and 26 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4000, a degree of alcoholysis of 90 mol%, and a viscosity of 7.0 mPa·s in a 4% aqueous solution; the nanosilver powder is spherical with a diameter D50 of 40 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 200 nm and a D100 of 750 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent is DL171.

[0092] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0093] S01, add 26 parts of deionized water to a glass reactor and heat to 70°C;

[0094] S02, add 12 parts of polyvinyl alcohol to a glass reactor, maintain the temperature and stir until completely dissolved;

[0095] S03, add 0.9 parts of coupling agent DL171 to the glass reactor, maintain the temperature and stir to mix evenly;

[0096] S04, sequentially add 10 parts of nano silver powder and 7 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0097] S05, adding 14 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0098] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding glue 4.

[0099] Example 5:

[0100] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 12 parts polyvinyl alcohol, 9 parts nanosilver powder, 3 parts submicron silver powder, 14 parts graphene oxide, 0.5 parts coupling agent, and 28 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4500, a degree of alcoholysis of 90 mol%, and a 4% aqueous solution viscosity of 7.0 mPa·s; the nanosilver powder is spherical with a diameter D50 of 40 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 300 nm and a D100 of 900 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent is DL171.

[0101] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0102] S01, add 28 parts of deionized water to a glass reactor and heat to 70°C;

[0103] S02, add 12 parts of polyvinyl alcohol to a glass reactor, maintain the temperature and stir until completely dissolved;

[0104] S03, add 0.5 parts of coupling agent DL171 to the glass reactor, maintain the temperature and stir to mix evenly;

[0105] S04, sequentially add 9 parts of nano silver powder and 3 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0106] S05, adding 14 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0107] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding adhesive 5.

[0108] Example 6:

[0109] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 15 parts polyvinyl alcohol, 10 parts nanosilver powder, 5.5 parts submicron silver powder, 20 parts graphene oxide, 1.2 parts coupling agent, and 25 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4500, a degree of alcoholysis of 90 mol%, and a 4% aqueous solution viscosity of 7.0 mPa·s; the nanosilver powder is spherical with a diameter D50 of 40 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 300 nm and a D100 of 900 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent is KH550.

[0110] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0111] S01, add 25 parts of deionized water to a glass reactor and heat to 70°C;

[0112] S02, add 15 parts of polyvinyl alcohol to the glass reactor, maintain the temperature and stir until completely dissolved;

[0113] S03, add 1.2 parts of coupling agent KH550 to the glass reactor, maintain the temperature and stir to mix evenly;

[0114] S04, sequentially add 10 parts of nano silver powder and 5.5 parts of submicron silver powder, and stir while keeping warm until uniformly dispersed;

[0115] S05, adding 20 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0116] S06. Cool to room temperature, seal and store to obtain medium and high frequency electromagnetic shielding glue 6.

[0117] Example 7:

[0118] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 12 parts polyvinyl alcohol, 10 parts nanosilver powder, 7 parts submicron silver powder, 14 parts graphene oxide, 0.9 parts coupling agent, and 28 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4500, a degree of alcoholysis of 85 mol%, and a viscosity of 7.0 mPa·s in a 4% aqueous solution; the nanosilver powder is spherical with a diameter D50 of 30 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 200 nm and a D100 of 750 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent comprises 0.5 parts of coupling agent KH560 and 0.4 parts of coupling agent DL602.

[0119] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0120] S01, add 28 parts of deionized water to a glass reactor and heat to 70°C;

[0121] S02, add 12 parts of polyvinyl alcohol to a glass reactor, maintain the temperature and stir until completely dissolved;

[0122] S03, add 0.5 parts of coupling agent KH560 and 0.4 parts of coupling agent DL602 to the glass reactor, maintain the temperature and stir to mix evenly;

[0123] S04, sequentially add 10 parts of nano silver powder and 7 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0124] S05, adding 14 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0125] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding adhesive 7.

[0126] Example 8:

[0127] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 12 parts polyvinyl alcohol, 10 parts nanosilver powder, 7 parts submicron silver powder, 14 parts graphene oxide, 0.9 parts coupling agent, and 24 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4500, a degree of alcoholysis of 85 mol%, and a 4% aqueous solution viscosity of 7.0 mPa·s; the nanosilver powder is spherical with a diameter D50 of 30 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 200 nm, and a D100 of 750 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent comprises 0.3 parts of coupling agent KH560, 0.3 parts of coupling agent KH570, and 0.3 parts of coupling agent DL602.

[0128] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0129] S01, add 24 parts of deionized water to a glass reactor and heat to 70°C;

[0130] S02, add 12 parts of polyvinyl alcohol to a glass reactor, maintain the temperature and stir until completely dissolved;

[0131] S03, add 0.3 parts of coupling agent KH560, 0.3 parts of coupling agent KH570 and 0.3 parts of coupling agent DL602 to the glass reactor, maintain the temperature and stir to mix evenly;

[0132] S04, sequentially add 10 parts of nano silver powder and 7 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0133] S05, adding 14 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0134] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding glue 8.

[0135] Example 9:

[0136] This embodiment provides a medium- and high-frequency electromagnetic shielding adhesive, comprising the following components and their weight fractions: 12 parts polyvinyl alcohol, 10 parts nanosilver powder, 7 parts submicron silver powder, 14 parts graphene oxide, 0.9 parts coupling agent, and 25 parts deionized water. Furthermore, the polyvinyl alcohol has a degree of polymerization of 4500, a degree of alcoholysis of 85 mol%, and a 4% aqueous solution viscosity of 7.0 mPa·s; the nanosilver powder is spherical with a diameter D50 of 30 nm and a D100 of 90 nm; the submicron silver powder is flake-shaped with a width-to-thickness ratio of (8-20):1, a diameter D50 of 200 nm and a D100 of 750 μm; the graphene oxide has a thickness of 0.55 nm to 1.2 nm and a diameter of 0.5 μm to 3 μm; and the coupling agent comprises 0.5 parts of coupling agent DL171 and 0.4 parts of coupling agent KH792.

[0137] This embodiment also provides a method for preparing the above-mentioned medium and high frequency electromagnetic shielding adhesive, comprising the following steps:

[0138] S01, add 24 parts of deionized water to a glass reactor and heat to 70°C;

[0139] S02, add 12 parts of polyvinyl alcohol to a glass reactor, maintain the temperature and stir until completely dissolved;

[0140] S03, add 0.5 parts of coupling agent DL171 and 0.4 parts of coupling agent KH792 to the glass reactor, maintain the temperature and stir to mix evenly;

[0141] S04, sequentially add 10 parts of nano silver powder and 7 parts of submicron silver powder, and stir while keeping warm until evenly dispersed;

[0142] S05, adding 14 parts of graphene oxide, maintaining at 70°C, and stirring for 2 hours;

[0143] S06. Cool to room temperature, seal and store to obtain the medium and high frequency electromagnetic shielding adhesive 9.

[0144] Comparative Example 1:

[0145] This comparative example provides a commercially available conductive silver paste product 1.

[0146] Comparative Example 2:

[0147] This comparative example provides a commercially available conductive silver paste product 2.

[0148] Cost comparison

[0149] The preparation costs of the high-frequency electromagnetic shielding adhesives in Examples 1-9 and the commercially available conductive silver adhesive products in Comparative Examples 1-2 are shown in Table 1;

[0150] Table 1 Statistics of preparation costs of electromagnetic shielding adhesives and commercially available conductive silver adhesives in various medium and high frequency bands

[0151] As can be seen from Table 1, the cost of the medium and high frequency electromagnetic shielding glue of the present invention is basically around 2,000, while the commercially available conductive silver glue products are all around 6,000. Compared with the commercially available conductive silver glue products, the cost of the medium and high frequency electromagnetic shielding glue of the present invention is reduced by about 2 / 3.

[0152] Electromagnetic shielding performance

[0153] The medium and high frequency electromagnetic shielding glue 1-9 and the commercially available conductive silver glue product 1-2 were coated on a dedicated test board according to the following usage method to obtain test samples. The specific usage method is as follows:

[0154] S10. Apply high thixotropic insulating adhesive to a thickness of 40 μm on a special test board and bake at 120°C for 20 minutes.

[0155] S20, coating the surface of the formed high thixotropic insulating adhesive layer with respective medium and high frequency band electromagnetic shielding adhesive and commercially available conductive silver adhesive products, with a coating thickness of 100 μm, baking the medium and high frequency band electromagnetic shielding adhesive layer at a temperature of 120° C. for 20 minutes, and baking the conductive silver adhesive layer at a temperature of 180° C. for 30 minutes;

[0156] S30, apply diluted high thixotropic insulating glue on the surface of the special test board with a coating thickness of 20 μm and bake at 120°C for 15 minutes;

[0157] In steps S10 and S30, the highly thixotropic insulating adhesive can be a commercially available insulating adhesive or a homemade insulating adhesive, as long as the thixotropic index meets the requirements of >7 and the insulation retention time after immersion in artificial sweat is >12 hours at a coating thickness of 100 μm; and in step S30, the highly thixotropic insulating adhesive is diluted 5 times with C1 monohydric alcohol.

[0158] Each special test board emits electromagnetic waves of different frequencies at a power of 15W to test the shielding efficiency SE of each test sample. The test results are shown in Figure 1. It can be seen from Figure 1 that the shielding efficiency of the medium and high frequency electromagnetic shielding glue of the present invention is comparable to that of the commercially available conductive silver glue, among which the electromagnetic shielding effect for the frequency band above 750MHz is particularly significant. It can be seen that the medium and high frequency electromagnetic shielding glue of the present invention not only has good electromagnetic shielding performance, but also costs much less than the existing conductive silver glue.

[0159] It will be apparent to one skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other cases, features well known to those skilled in the art have not been described in detail to avoid unnecessarily complicating the description. It is intended that all alternatives, substitutions, modifications, and equivalents apparent to those skilled in the art are included within the scope of this disclosure. All compounds / compositions disclosed herein, as well as methods for their preparation, applications, and uses, can be prepared and implemented without undue experimentation in light of this disclosure.

[0160] Although the compounds / compositions and methods of the present disclosure have been described with respect to specific embodiments, it will be apparent to those skilled in the art that changes may be made in the formulations, compounds or compositions and / or methods, and in the steps or order of steps of the methods described herein without departing from the spirit and scope of the inventive concepts of the present disclosure.

[0161] Although the present invention has been described with reference to the above specific embodiments, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the above. Therefore, all such substitutions, modifications, and variations are intended to be encompassed within the spirit and scope of the appended claims.

Claims

1. A medium and high frequency electromagnetic shielding adhesive, characterized in that, It consists of the following components and the weight parts of the components:

2. The medium and high frequency electromagnetic shielding adhesive according to claim 1, wherein Composed of the following components and their weight parts:

3. The medium and high frequency electromagnetic shielding adhesive according to claim 1, wherein The degree of polymerization of the polyvinyl alcohol is 3,000 - 4,500, the degree of alcoholysis is 85 mol% - 90 mol%, and the viscosity of a 4% aqueous solution is 6.0 mPa·S - 8.0 mPa·S.

4. The medium and high frequency electromagnetic shielding adhesive according to claim 1, characterized in that, The nano silver powder is in a spherical structure, with a D50 diameter of 30 nm - 50 nm and a D100 diameter of 80 nm - 100 nm.

5. The medium and high frequency electromagnetic shielding adhesive according to claim 1, wherein The submicron silver powder is in a flake structure, with an aspect ratio of (8 - 20):

1.

6. The medium and high frequency electromagnetic shielding adhesive according to claim 1, wherein The diameter D50 of the submicron silver powder is 150 nm - 300 nm, and the D100 is 600 um - 900 um.

7. The medium and high frequency electromagnetic shielding adhesive according to claim 1, characterized in that, The thickness of the graphene oxide is 0.55 nm - 1.2 nm, and the diameter is 0.5 um - 3 um.

8. The medium and high frequency electromagnetic shielding adhesive according to claim 1, characterized in that, The coupling agent is a silane coupling agent, including one or more of KH550, KH560, KH570, KH792, DL602, and DL171.

9. The preparation method of a medium and high frequency electromagnetic shielding adhesive according to any one of claims 1-8, characterized in that, It includes the following steps: S01: Add deionized water and heat to 70 °C. S02: Add polyvinyl alcohol, maintain the temperature and stir until completely dissolved. S03: Add the coupling agent, maintain the temperature and stir to mix evenly. S04: Sequentially add nano silver powder and submicron silver powder, keep warm and stir until evenly dispersed. S05: Add graphene oxide, maintain at 70 °C and stir for 2 hours. S06: Cool to room temperature and store in a sealed manner to obtain the medium and high frequency electromagnetic shielding adhesive.

10. The method of using a medium and high frequency electromagnetic shielding adhesive according to any one of claims 1-8, characterized in that, It includes the following steps: S10: Coat a high thixotropic insulating adhesive with a thickness of 10 um - 80 um on the surface of the object to be shielded, and bake at a temperature of 80 °C - 150 °C for no more than 25 min. S20: Coat the medium and high frequency electromagnetic shielding adhesive with a thickness of 30 um - 180 um on the surface of the formed high thixotropic insulating adhesive layer, and bake at a temperature of 80 °C - 150 °C for no more than 25 min. S30: Coat a diluted high thixotropic insulating adhesive with a thickness of 0 - 30 um on the surface of the object to be shielded material, and bake at a temperature of 80 °C - 150 °C for no more than 25 min. In steps S10 and S30, the thixotropic index of the high thixotropic insulating adhesive > 7, and the insulation retention time after being soaked in artificial sweat at a coating thickness of 100 μm > 12H. In step S30, the high thixotropic insulating adhesive is diluted 2 - 10 times with at least one of C1 - C4 monohydric alcohols.

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