Preparation method of composite electromagnetic shielding film

Abstract

The invention discloses a preparation method of a composite electromagnetic shielding film. The preparation method comprises the following steps: (1) carrying out corona treatment on a substrate film to form a hole structure on the surface of the substrate film; (2) sequentially adding water-based acrylic resin, graphene slurry, a defoaming agent and a flatting agent into a vacuum stirrer, and uniformly stirring to obtain first slurry; (3) the mixed slurry obtained in the step (2) is placed in a ball mill, nano metal powder is added in batches, and second slurry is obtained after ball milling; (4) the surface of the basement membrane treated in the step (1) is coated with second slurry in a blade coating mode, a coating layer is formed, and the thickness of the coating layer ranges from 0.1 mm to 0.3 mm; and (5) drying the film coated in the step (4) in a drying oven.

Description

Technical Field

[0001] This invention relates to a method for preparing an electromagnetic shielding film. Background Technology

[0002] With the rapid development of information technology and the electronics industry, the integration of electronic devices is constantly increasing, and the electromagnetic environment is becoming increasingly complex, leading to widespread concern about electromagnetic interference (EMI). Miniaturized and integrated electronic devices (such as those used in wireless communication, satellite navigation, and aerospace) have very high requirements for the electromagnetic environment. However, electromagnetic interference, signal attenuation, and electromagnetic pollution increase the risks that may be encountered during equipment operation, which is a problem that cannot be ignored for equipment that needs to maintain high reliability. Therefore, electromagnetic interference (EMI) shielding technology to maintain the functionality and reliability of electronic devices has become extremely important.

[0003] Electromagnetic waves not only affect the normal operation of electronic devices but may also have adverse effects on human health. To address this issue, electromagnetic shielding materials have emerged. Traditional electromagnetic shielding materials mainly include metallic materials, conductive polymer materials, and conductive ceramic materials. However, these materials have many shortcomings, such as high density, easy oxidation, narrow absorption bandwidth, and poor flexibility. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings of existing electromagnetic shielding films, the present invention provides a method for preparing a composite electromagnetic shielding film that can improve conductivity and electromagnetic shielding performance.

[0005] The technical solution of this invention to solve its technical problem is: a method for preparing a composite electromagnetic shielding film, comprising the following steps: (1) The base film is subjected to corona treatment to form a porous structure on the surface of the base film, thereby increasing the surface roughness of the base film and enhancing the adhesion of subsequent graphene coating. The base film can be a common film in the prior art, such as polyamide film, polyethersulfone film, polyacrylonitrile film, polymethyl methacrylate film, etc.

[0006] (2) A water-based acrylic resin, graphene slurry, defoamer, and leveling agent in a mass ratio of 1:0.4-0.7:0.002-0.004:0.02-0.04 are added sequentially to a vacuum mixer and stirred until homogeneous to obtain the first slurry. The defoamer is used to defoam, and the leveling agent is used to promote leveling. Therefore, the defoamer and leveling agent can be common defoamers and leveling agents in the existing technology, and there are no special requirements. The graphene slurry is composed of graphene, water and dispersant in a mass ratio of 1:2-4:0.05-0.07. The dispersant is used to promote dispersion, so the dispersant can be a common dispersant in the existing technology and there are no special requirements.

[0007] (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano metal powder in batches, with an interval of 10-20 minutes between each batch, and control the ball milling time to 1-2 hours to obtain a second slurry, in which the mass percentage of nano metal powder is 40-50 wt%.

[0008] (4) Apply the second slurry to the surface of the substrate film treated in step (1) to form a coating layer with a thickness of 0.1-0.3 mm.

[0009] (5) Dry the film coated in step (4) in an oven.

[0010] Preferably, the corona treatment time of the basement membrane in step (1) is 15-20 min.

[0011] Preferably, the nano metal powder in step (3) is nano copper powder, or nano silver powder, or a mixture of nano copper powder and nano silver powder.

[0012] The beneficial effects of this invention are as follows: by uniformly dispersing metal nanopowder in graphene to form a highly conductive network structure, the conductivity and electromagnetic shielding performance of the material are significantly improved, solving the problem of low conductivity of traditional electromagnetic shielding materials. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to specific embodiments.

[0014] Example 1: A method for preparing a composite electromagnetic shielding film, comprising the following steps: (1) The polyamide substrate film is subjected to corona treatment to form a porous structure on the surface of the substrate film, thereby increasing the surface roughness of the substrate film and enhancing the adhesion of subsequent graphene coating. The corona treatment time of the polyamide substrate film is 15 min.

[0015] (2) Add water-based acrylic resin, graphene slurry, defoamer, and leveling agent in a mass ratio of 1:0.5:0.003:0.03 to a vacuum mixer and stir until homogeneous to obtain the first slurry. The defoamer is for defoaming, and the leveling agent is for promoting leveling. Therefore, the defoamer and leveling agent can be common defoamers and leveling agents in the existing technology, and there are no special requirements. For example, the defoamer can be silicone defoamer, glycerol polyether, stearic acid, octadecyl alcohol, etc., and the leveling agent can be polydimethylsiloxane, polyether polyester modified silicone, acrylic leveling agent, etc.

[0016] The graphene slurry consists of graphene, water, and a dispersant in a mass ratio of 1:3:0.06. The dispersant is used to promote dispersion, and therefore, any commonly used dispersant in existing technologies can be used without special requirements. For example, the 7170W dispersant from Guangzhou Sloco New Materials Co., Ltd. can be used, as it has a better effect on dispersing graphene. Of course, other dispersants, such as sodium polyacrylate, can also be used.

[0017] (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano copper powder in batches, with an interval of 15 min between each batch, and control the ball milling time to 100 min to obtain a second slurry. The mass percentage of nano metal powder in the second slurry is 45 wt%.

[0018] (4) Apply the second slurry to the surface of the base film treated in step (1) to form a coating layer with a thickness of 0.2 mm.

[0019] (5) Dry the film coated in step (4) in an oven.

[0020] Example 2: A method for preparing a composite electromagnetic shielding film, comprising the following steps: (1) The polyethersulfone substrate film is subjected to corona treatment to form a porous structure on the surface of the substrate film, thereby increasing the surface roughness of the substrate film and enhancing the adhesion of subsequent graphene coating. The corona treatment time of the polyethersulfone substrate film is 18 min.

[0021] (2) Add water-based acrylic resin, graphene slurry, defoamer, and leveling agent in a mass ratio of 1:0.4:0.004:0.04 to a vacuum mixer and stir evenly to obtain the first slurry. The defoamer is for defoaming, and the leveling agent is for promoting leveling. Therefore, the defoamer and leveling agent can be common defoamers and leveling agents in the existing technology, and there are no special requirements. For example, the defoamer can be silicone defoamer, glycerol polyether, stearic acid, octadecyl alcohol, etc., and the leveling agent can be polydimethylsiloxane, polyether polyester modified silicone, acrylic leveling agent, etc.

[0022] The graphene slurry consists of graphene, water, and a dispersant in a mass ratio of 1:4:0.05. The dispersant is used to promote dispersion, and therefore, any commonly used dispersant in existing technologies can be used without special requirements. For example, the 7170W dispersant from Guangzhou Sloco New Materials Co., Ltd. can be used, as it has a better effect on dispersing graphene. Of course, other dispersants, such as sodium polyacrylate, can also be used.

[0023] (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano silver powder in batches, with an interval of 20 minutes between each batch, and control the ball milling time to 90 minutes to obtain a second slurry. The mass percentage of nano metal powder in the second slurry is 40 wt%.

[0024] (4) Apply the second slurry to the surface of the substrate film treated in step (1) to form a coating layer with a thickness of 0.15 mm.

[0025] (5) Dry the film coated in step (4) in an oven.

[0026] Example 3: A method for preparing a composite electromagnetic shielding film, comprising the following steps: (1) The polyacrylonitrile substrate film is subjected to corona treatment to form a porous structure on the surface of the substrate film, thereby increasing the surface roughness of the substrate film and enhancing the adhesion of subsequent graphene coating. The corona treatment time of the polyacrylonitrile substrate film is 20 min.

[0027] (2) Add water-based acrylic resin, graphene slurry, defoamer, and leveling agent in a mass ratio of 1:0.7:0.002:0.035 to a vacuum mixer and stir until homogeneous to obtain the first slurry. The defoamer is for defoaming, and the leveling agent is for promoting leveling. Therefore, the defoamer and leveling agent can be common defoamers and leveling agents in the existing technology, and there are no special requirements. For example, the defoamer can be silicone defoamer, glycerol polyether, stearic acid, octadecyl alcohol, etc., and the leveling agent can be polydimethylsiloxane, polyether polyester modified silicone, acrylic leveling agent, etc.

[0028] The graphene slurry consists of graphene, water, and a dispersant in a mass ratio of 1:2:0.055. The dispersant is used to promote dispersion, and therefore, any commonly used dispersant in existing technologies can be used without special requirements. For example, the 7170W dispersant from Guangzhou Sloco New Materials Co., Ltd. can be used, as it has a better effect on dispersing graphene. Of course, other dispersants, such as sodium polyacrylate, can also be used.

[0029] (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano silver powder in batches, with an interval of 10 min between each batch, and control the ball milling time to 120 min to obtain a second slurry. The mass percentage of nano metal powder in the second slurry is 48 wt%.

[0030] (4) Apply the second slurry to the surface of the substrate film treated in step (1) to form a coating layer with a thickness of 0.1 mm.

[0031] (5) Dry the film coated in step (4) in an oven.

[0032] Example 4: A method for preparing a composite electromagnetic shielding film, comprising the following steps: (1) The polymethyl methacrylate (PMMA) base film was subjected to corona treatment to form a porous structure on the surface of the base film, thereby increasing the surface roughness of the base film and enhancing the adhesion of the subsequent graphene coating. The corona treatment time of the PMMA base film was 16 min.

[0033] (2) Add water-based acrylic resin, graphene slurry, defoamer, and leveling agent in a mass ratio of 1:0.6:0.003:0.02 to a vacuum mixer and stir evenly to obtain the first slurry. The defoamer is for defoaming, and the leveling agent is for promoting leveling. Therefore, the defoamer and leveling agent can be common defoamers and leveling agents in the existing technology, and there are no special requirements. For example, the defoamer can be silicone defoamer, glycerol polyether, stearic acid, octadecyl alcohol, etc., and the leveling agent can be polydimethylsiloxane, polyether polyester modified silicone, acrylic leveling agent, etc.

[0034] The graphene slurry consists of graphene, water, and a dispersant in a mass ratio of 1:2.5:0.07. The dispersant is used to promote dispersion, and therefore, any commonly used dispersant in existing technologies can be used without special requirements. For example, the 7170W dispersant from Guangzhou Sloco New Materials Co., Ltd. can be used, as it has a better effect on dispersing graphene. Of course, other dispersants, such as sodium polyacrylate, can also be used.

[0035] (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano copper powder in batches, with an interval of 13 minutes between each batch, and control the ball milling time to 60 minutes to obtain a second slurry. The mass percentage of nano metal powder in the second slurry is 50 wt%.

[0036] (4) Apply the second slurry to the surface of the substrate film treated in step (1) to form a coating layer with a thickness of 0.3 mm.

[0037] (5) Dry the film coated in step (4) in an oven.

[0038] Example 5: A method for preparing a composite electromagnetic shielding film, comprising the following steps: (1) The polyethersulfone (PES) film substrate is subjected to corona treatment to form a porous structure on the surface of the substrate, thereby increasing the surface roughness of the substrate and enhancing the adhesion of subsequent graphene coating. The corona treatment time of the PES film substrate is 17 min.

[0039] (2) Add water-based acrylic resin, graphene slurry, defoamer, and leveling agent in a mass ratio of 1:0.5:0.004:0.025 to a vacuum mixer and stir evenly to obtain the first slurry. The defoamer is for defoaming, and the leveling agent is for promoting leveling. Therefore, the defoamer and leveling agent can be common defoamers and leveling agents in the existing technology, and there are no special requirements. For example, the defoamer can be silicone defoamer, glycerol polyether, stearic acid, octadecyl alcohol, etc., and the leveling agent can be polydimethylsiloxane, polyether polyester modified silicone, acrylic leveling agent, etc.

[0040] The graphene slurry consists of graphene, water, and a dispersant in a mass ratio of 1:3.5:0.065. The dispersant is used to promote dispersion, and therefore, any commonly used dispersant in existing technologies can be used without special requirements. For example, the 7170W dispersant from Guangzhou Sloco New Materials Co., Ltd. can be used, as it has a better effect on dispersing graphene. Of course, other dispersants, such as sodium polyacrylate, can also be used.

[0041] (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano copper powder and nano silver powder in batches, with an interval of 18 minutes between each batch, and control the ball milling time to 70 minutes to obtain a second slurry. The mass percentage of nano metal powder in the second slurry is 42 wt%. The ratio between nano copper powder and nano silver powder in the nano metal powder is not specified and can be any ratio.

[0042] (4) Apply the second slurry to the surface of the substrate film treated in step (1) to form a coating layer with a thickness of 0.25 mm.

[0043] (5) Dry the film coated in step (4) in an oven.

Claims

1. A method for preparing a composite electromagnetic shielding film, characterized in that... Includes the following steps: (1) The base film is subjected to corona treatment to form a porous structure on the surface of the base film, thereby increasing the surface roughness of the base film and enhancing the adhesion of subsequent graphene coating. (2) Add water-based acrylic resin, graphene slurry, defoamer and leveling agent in a mass ratio of 1:0.4-0.7:0.002-0.004:0.02-0.04 to a vacuum mixer and stir evenly to obtain the first slurry; The graphene slurry is composed of graphene, water, and dispersant in a mass ratio of 1:2-4:0.05-0.

07. (3) Place the mixed slurry obtained in step (2) into a ball mill, add nano-metal powder in batches, with an interval of 10-20 minutes between each batch, and control the ball milling time to be 1-2 hours to obtain a second slurry, in which the mass percentage content of nano-metal powder is 40-50 wt%; (4) Apply the second slurry to the surface of the substrate film treated in step (1) to form a coating layer with a thickness of 0.1-0.3 mm; (5) Dry the film coated in step (4) in an oven.

2. The method for preparing the composite electromagnetic shielding film as described in claim 1, characterized in that: The corona treatment time for the basement membrane in step (1) is 15-20 min.

3. The method for preparing the composite electromagnetic shielding film as described in claim 1, characterized in that: In step (3), the nano metal powder is nano copper powder, or nano silver powder, or a mixture of nano copper powder and nano silver powder.