Method for rapidly preparing super-uniform transparent electromagnetic shielding film on large scale

Abstract

The invention provides a method for rapidly preparing a super-uniform transparent electromagnetic shielding film on a large scale. The method comprises the following steps: step 1, flatly paving and fixing a substrate film on the inner wall of a rotary drum; 2, the rotating speed of the rotating drum is controlled to range from 1000 r / min to 10000 r / min; 3, the film coating liquid is subjected to superfine atomization and sprayed to the surface of the base film on the inner wall of the rotary drum; and 4, curing the film coating liquid to obtain the electromagnetic shielding film. The high-speed rotating drum is combined with the superfine spraying technology for film coating, the prepared electromagnetic shielding film is large in size, filler distribution is highly uniform, no coffee ring is formed, and the preparation process is simple, convenient, low in cost and suitable for large-scale batch production.

Description

Technical Field

[0001] This application relates to the field of electromagnetic shielding technology, and particularly to a method for rapidly and massively preparing a super-uniform transparent electromagnetic shielding film. Background Art

[0002] Functionalized films have a wide range of applications in multiple fields such as optoelectromagnetic devices, seawater desalination, catalysis, sensors, and electromagnetic shielding. Developing a method for rapidly and massively preparing super-uniform electromagnetic shielding films can effectively promote the development of industries such as medical devices, electronics, drones, aerospace, and new energy vehicles, and is also of great significance for industrial upgrading and transformation. Currently, the main film coating methods include spin coating by a spin coater, blade coating, Mayer rod coating, brush coating, vacuum filtration film formation, and dipping film formation. These methods have greatly expanded the applications in various film fields and promoted the application of functionalized films. However, there are still problems such as small film-forming area or uneven distribution, which greatly limit the application of the film in the field of electromagnetic shielding. Therefore, it is still necessary to develop a new method for preparing electromagnetic shielding films. Summary of the Invention

[0003] The purpose of this application is to provide a method for preparing an electromagnetic shielding film to improve the film-forming area and uniformity of the electromagnetic shielding film. The specific technical solutions are as follows:

[0004] The first aspect of this application provides a method for preparing an electromagnetic shielding film, including the steps of:

[0005] Step 1: Lay and fix the base film on the inner wall of the rotating cylinder;

[0006] Step 2: Control the rotation speed of the rotating cylinder to be 1000 r / min - 10000 r / min;

[0007] Step 3: Ultra-finely atomize the coating solution and spray it on the surface of the base film on the inner wall of the rotating cylinder;

[0008] Step 4: Cure the coating solution to obtain an electromagnetic shielding film.

[0009] In some embodiments of this application, the diameter of the rotating cylinder is 10 cm - 30 cm, and the depth of the rotating cylinder is 10 cm - 30 cm.

[0010] In some embodiments of this application, the concentration of the coating solution is 0.01 mg / mL - 10 mg / mL.

[0011] In some embodiments of this application, the sample injection speed of the atomizer used for atomization is 0.1 mL / min - 20 mL / min, and the atomization pressure is 0.1 MPa - 10 MPa.

[0012] In some embodiments of the present application, the distance between the nozzle and the surface of the base film during spraying is 50 mm - 200 mm, the horizontal moving distance of the nozzle relative to the base film is 0 cm - 30 cm, and the horizontal moving speed of the nozzle relative to the base film is 0 cm / min - 100 cm / min.

[0013] In some embodiments of the present application, the curing is carried out by drying and curing with an infrared drying lamp.

[0014] In some embodiments of the present application, the temperature of the infrared drying lamp is 50°C - 300°C.

[0015] In some embodiments of the present application, steps 3 and 4 are repeated successively.

[0016] In some embodiments of the present application, the base film is selected from a water-based base film or an organic-based base film.

[0017] In some embodiments of the present application, before laying and fixing the base film on the inner wall of the rotating cylinder, a pretreatment step is further included: washing the organic-based base film successively with water and ethanol, and then drying; or washing the water-based base film with water and then drying.

[0018] In some embodiments of the present application, the rotating cylinder is made of aluminum alloy or polytetrafluoroethylene.

[0019] Advantages of the present application:

[0020] The present application uses a high-speed rotating cylinder combined with an ultra-fine spraying technology to coat the film. The linear speed of the high-speed rotating cylinder is extremely fast, and a large area of the film can be coated in a very short time. The extremely high linear speed can also improve the uniformity of the film; the coated film liquid after ultra-fine atomization can evenly disperse the filler, and the size of the atomized liquid reaches the micron level. Combined with the high-speed rotating cylinder, the uniformity of the filler dispersion in the film can be further greatly improved, and the generation of the coffee ring can be completely avoided; the infrared drying lamp can quickly dry and cure the coated film liquid, and a large area of high-quality film can be obtained in a short time. The addition amount of the filler in the present application is extremely low, and a small amount of conductive filler can form a dense conductive network, resulting in excellent electromagnetic shielding performance and high light transmittance. The utilization rate of the coated film liquid in the present application is extremely high, theoretically reaching 100%, thus saving costs. The present application can prepare films of different types, structures and thicknesses according to actual needs by selecting rotating cylinders of different sizes, adjusting the rotating speed of the rotating cylinder, different types of base films, different atomization conditions, and different infrared drying and curing temperatures.

[0021] Of course, it is not necessary for any product or method implementing the present application to achieve all the above advantages simultaneously. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other embodiments can also be obtained based on these drawings.

[0023] Figure 1 Scanning electron microscope (SEM) image of a randomly selected area of the electromagnetic shielding film prepared in Example 1 of the present application;

[0024] Figure 2 SEM image of a randomly selected area of the electromagnetic shielding film prepared in Example 2 of the present application;

[0025] Figure 3 Electromagnetic shielding effectiveness diagram of the electromagnetic shielding film prepared in Example 1 of the present application in the X-band;

[0026] Figure 4 Electromagnetic shielding effectiveness diagram of the electromagnetic shielding film prepared in Example 2 of the present application in the X-band. Detailed implementation manners

[0027] The following will clearly and completely describe the technical solutions in the present application in combination with the embodiments and the accompanying drawings of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0028] The coating methods of existing electromagnetic shielding films mainly include spin coating by a spin coater, doctor blade coating, Mayer rod coating, brush coating, film formation by vacuum filtration, and immersion coating, etc. However, there are still many problems with the above methods. For example: the raw material utilization rate of spin coating is extremely low, and the film formation area is small; the coating speed of the Mayer rod is slow and the efficiency is low; brush coating, immersion coating, and doctor blade coating are prone to form coffee rings and filler aggregation, the filler distribution is uneven, and the requirements for the concentration of the coating solution are high. Due to various forces, such as electrostatic attraction, van der Waals forces, surface tension, etc., nano-scale fillers are prone to agglomeration, resulting in poor film formation effect, uneven coffee rings, etc. after film formation, which greatly deteriorates the performance of the electromagnetic shielding film. In addition, disadvantages such as difficult control of the film formation thickness and small film formation area also greatly limit the application of the film in the field of electromagnetic shielding.

[0029] The ultra-fine atomization technology uses compressed air to atomize a liquid into ultra-fine droplets with a size in the micron range, which can excellently disperse nano materials. There is an existing high-efficiency ultrasonic rotary coating device. The substrate to be coated is placed on the substrate plate. The vacuum air source is turned on, the liquid supply device is connected, the protective ring is installed, and the rotation speed of the substrate plate and the swing speed of the ultrasonic head are set on the control panel interface. The droplets after ultrasonic atomization are sprayed on the surface of the substrate to achieve coating; the film obtained by this method has uniform dispersion of fillers and high coating quality; however, there are problems such as small film-forming area, complex equipment device, and large waste of coating liquid. There is an existing coating technology combining spin coating and oscillation. A spin coating agent is applied and coated on the base, and then oscillated. After the spin coating agent is cured, the spin coating agent is applied again for rotary coating and oscillation, and finally a spin coating film with uniform thickness is obtained. This method improves the uniformity of the film layer, but it is necessary to add a buffer and oscillation device and an oscillation control device, and the structure is relatively complex, and the coating area is also small. The inventor unexpectedly found in the research that by using a high-speed rotating drum combined with the ultra-fine spray technology for coating, the prepared electromagnetic shielding film has a large size, highly uniform filler distribution, no formation of any coffee rings, and the preparation process is simple and the cost is low, which is suitable for large-scale mass production.

[0030] The present application provides a method for preparing an electromagnetic shielding film, comprising the steps of:

[0031] Step 1: Lay and fix the base film on the inner wall of the drum;

[0032] Step 2: Control the rotation speed of the drum to be 1000 r / min - 10000 r / min;

[0033] Step 3: Ultra-finely atomize the coating liquid and spray it on the surface of the base film on the inner wall of the drum;

[0034] Step 4: Cure the coating liquid to obtain an electromagnetic shielding film.

[0035] In the present application, the rotation speed of the drum can be 1000 r / min, 2000 r / min, 3000 r / min, 4000 r / min, 5000 r / min, 6000 r / min, 7000 r / min, 8000 r / min, 9000 r / min, 10000 r / min or any range composed of any two of these values. When the rotation speed of the drum is lower than 1000 r / min, the coating speed decreases, and the uniformity and electromagnetic shielding performance of the obtained electromagnetic shielding film significantly decrease; when the rotation speed of the drum is higher than 10000 r / min, the requirement for the dynamic balance of the equipment is relatively high, and the coating cost increases significantly. The present application controls the rotation speed of the drum within the above-mentioned range of 1000 r / min - 10000 r / min, which is beneficial to coating a large area in a very short time and effectively improving the uniformity of the electromagnetic shielding film.

[0036] There is no particular limitation on the size of the base film in this application, as long as the inventive purpose of this application can be achieved. For example, it can be 10 cm × 33.5 cm or 12 cm × 83.2 cm.

[0037] There is no particular limitation on the equipment used to control the rotation speed of the rotating cylinder in this application, as long as the inventive purpose of this application can be achieved. For example, a motor and a motor control panel can be used to stably control the rotation speed of the rotating cylinder at 1000 r / min - 10000 r / min.

[0038] There is no particular limitation on the type of coating solution in this application, as long as the inventive purpose of this application can be achieved. For example, a coating solution can be prepared by dispersing silver nanowires in ethanol or water.

[0039] The ultra-fine atomization described in this application means that the size of the atomized liquid is in the micron range. There is no particular limitation on the equipment used for ultra-fine atomization and spraying in this application, as long as the inventive purpose of this application can be achieved. For example, an electronic atomizing spray can be used to achieve ultra-fine atomization and spraying.

[0040] The areal density of the electromagnetic shielding film described in this application can be adjusted according to actual needs. For example, the areal density is 500 mg / mL - 1000 mg / mL.

[0041] This application uses a high-speed rotating cylinder combined with an ultra-fine spraying technology for coating. The linear speed of the high-speed rotating cylinder is extremely fast, and a large area can be coated in a very short time. The extremely high linear speed can also improve the uniformity of the film. The coating solution after ultra-fine atomization can evenly disperse the filler, and the size of the atomized liquid reaches the micron range. Combined with the high-speed rotating cylinder, the uniformity of the filler dispersion in the film can be further greatly improved, and the generation of coffee rings can be completely avoided.

[0042] In some embodiments of this application, the diameter of the rotating cylinder is 10 cm - 30 cm, and the depth of the rotating cylinder is 10 cm - 30 cm. In this application, the diameter of the rotating cylinder can be 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, or any range composed of any two of these values; the depth of the rotating cylinder can be 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, or any range composed of any two of these values. Controlling the diameter and depth of the rotating cylinder within the above range in this application is beneficial to maintaining good dynamic balance during the rotation coating process of the equipment and ensuring the uniformity of the filler in the film.

[0043] In some embodiments of the present application, the concentration of the coating solution is 0.01 mg / mL - 10 mg / mL. In the present application, the concentration of the coating solution can be 0.01 mg / mL, 0.1 mg / mL, 1 mg / mL, 5 mg / mL, 10 mg / mL, or a range composed of any two values therebetween. By controlling the concentration of the coating solution within the above range in the present application, it is beneficial to the good dispersion of the filler in the dispersion liquid, avoids the aggregation of the filler at too high a concentration, and is beneficial to improving the uniformity of the coated filler.

[0044] The addition amount of silver nanowires in the coating solution of the present application is extremely low. A small amount of silver nanowires can form a dense conductive network, and the obtained electromagnetic shielding film has excellent electromagnetic shielding performance and high light transmittance. The utilization rate of the coating solution of the present application is extremely high, theoretically up to 100%, which can save costs.

[0045] In some embodiments of the present application, the sample injection speed of the atomizer used for atomization is 0.1 mL / min - 20 mL / min, and the atomization pressure is 0.1 MPa - 10 MPa. In the present application, the sample injection speed can be 0.1 mL / min, 0.5 mL / min, 1 mL / min, 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, or a range composed of any two values therebetween. The atomization pressure can be 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, or a range composed of any two values therebetween. By controlling the sample injection speed and the atomization pressure within the above range in the present application, it is beneficial to coat a large area in a very short time, improve the uniformity of the film, and avoid the generation of coffee rings.

[0046] In some embodiments of the present application, the distance between the nozzle and the surface of the substrate film during spraying is 50 mm - 200 mm, the horizontal moving distance of the nozzle relative to the substrate film is 0 cm - 30 cm, and the horizontal moving speed of the nozzle relative to the substrate film is 0 cm / min - 100 cm / min. In the present application, the distance between the nozzle and the surface of the substrate film can be 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm or any range composed of any two values therebetween; the horizontal moving distance of the nozzle relative to the substrate film can be 0.5 cm, 1 cm, 5 cm, 10 cm, 15 cm, 20 cm, 25 cm, 30 cm or any range composed of any two values therebetween; the horizontal moving speed of the nozzle relative to the substrate film is 0.5 cm / min, 1 cm / min, 5 cm / min, 10 cm / min, 15 cm / min, 20 cm / min, 25 cm / min, 30 cm / min, 40 cm / min, 50 cm / min, 60 cm / min, 70 cm / min, 80 cm / min, 90 cm / min, 100 cm / min or any range composed of any two values therebetween. Controlling the distance between the nozzle and the surface of the substrate film during spraying in the present application is beneficial to the atomization and dispersion of the spray and reduces aggregation; when the horizontal moving distance of the nozzle relative to the substrate film and the horizontal moving speed of the nozzle relative to the substrate film are within the above ranges, it is beneficial to the uniform distribution of the film in the horizontal moving direction and improves the raw material utilization rate at the same time.

[0047] In some embodiments of the present application, the curing is carried out by drying and curing with an infrared drying lamp. The infrared drying lamp used in the present application can quickly dry and cure the coating liquid, and a large-area high-quality film can be obtained in a short time.

[0048] In some embodiments of the present application, the temperature of the infrared drying lamp is 50°C - 300°C. In the present application, the temperature of the infrared drying lamp can be 50°C, 70°C, 90°C, 100°C, 120°C, 150°C, 180°C, 200°C, 230°C, 250°C, 280°C, 300°C or any range composed of any two values therebetween. Controlling the temperature of the infrared drying lamp within the above range is beneficial to the rapid volatilization of the solvent of the coating liquid, and a large-area high-quality film can be obtained in a short time.

[0049] In some embodiments of the present application, step 3 and step 4 are repeated in sequence. In the present application, the number of times of repeating step 3 and step 4 in sequence can be adjusted according to the performance requirements of the required electromagnetic shielding film.

[0050] In some embodiments of the present application, the substrate film is selected from an aqueous substrate film or an organic substrate film.

[0051] The present application does not particularly limit the specific types of aqueous or organic base membranes, which can be selected according to actual needs and obtained through commercial channels. For example, PET (polyethylene terephthalate) base membranes can be selected as the organic base membranes.

[0052] In some embodiments of the present application, before laying and fixing the base membrane on the inner wall of the rotating cylinder, a pretreatment step is further included: sequentially washing the organic base membrane with water and ethanol, and then drying it; or washing the aqueous base membrane with water and then drying it. The drying described in the present application can be natural drying.

[0053] In some embodiments of the present application, the rotating cylinder is made of aluminum alloy or polytetrafluoroethylene.

[0054] The method for rapidly and massively preparing a super-uniform electromagnetic shielding film provided by the present application has the advantages of simple process, high repeatability, high reliability, low cost, large film size, highly uniform filler distribution, and small filler dosage. Moreover, the prepared electromagnetic shielding film has no coffee ring formation and excellent shielding performance, overcoming the problems widely existing in the existing coating technologies, such as extremely low raw material utilization rate, small film-forming area, uneven filler distribution, and low coating efficiency. In addition, the present application can prepare films of different types, structures, and thicknesses according to actual needs by selecting rotating cylinders of different sizes, adjusting the rotating speed of the rotating cylinder, different types of base membranes, different atomization conditions, and different infrared drying and curing temperatures.

[0055] Examples

[0056] Hereinafter, examples and comparative examples are given to more specifically illustrate the embodiments of the present application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0057] The PET base film used in the following examples and comparative examples was purchased from Dongguan Jubang Plastic Materials Co., Ltd., with the product model Xiwei-120; the silver nanowires were synthesized by the polyol method, including the steps of dissolving 2.67 g of polyvinylpyrrolidone with a number average molecular weight of 58,000 and 0.01 g of potassium bromide in 80 mL of ethylene glycol solution, heating at 170 °C until the temperature was stable, adding 5 mL of an ethylene glycol dispersion containing 0.05 g of silver chloride, and reacting for 5 minutes. Then, 80 mL of an ethylene glycol solution containing 0.88 g of silver nitrate was added dropwise at a rate of 4 mL / minute, and the reaction was continued at 170 °C for 60 minutes. After the reaction ended, heating was removed, and the silver nanowires were separated and purified by differential centrifugation. The reaction stock solution was diluted with water by a factor of two, centrifuged at 1000 r / min for 5 minutes, centrifuged twice, and the supernatant was collected. The supernatant was centrifuged at 5000 r / min for 10 minutes, the precipitate was collected and redispersed in deionized water, and centrifuged five times. Finally, the precipitate was dispersed in ethanol for standby.

[0058] Testing methods and equipment:

[0059] (1) Electromagnetic shielding effectiveness test

[0060] The electromagnetic shielding effectiveness was tested by the waveguide method. The magnetic shielding film was cut into a size of 23 mm × 10 mm, and its electromagnetic parameters and electromagnetic shielding effectiveness were measured by a vector network analyzer. The electromagnetic shielding effectiveness mainly depends on the reflection (R) coefficient, absorption (A) coefficient, and transmission (T) coefficient of electromagnetic waves. The sum of the three is equal to 1, that is

[0061] R + T + A = 1;

[0062] The reflection coefficient and transmission coefficient were calculated through the scattering coefficients (S 11 , S 12 , S 21 , S 22 ) of the sample. The scattering coefficients were obtained by testing with a vector network analyzer, that is

[0063] R = │S 11 │2 = │S 22 │2;

[0064] T = │S 21 │2 = │S 12 │2;

[0065] The total electromagnetic shielding effectiveness (S ET ) is equal to the sum of reflection (S ER ), absorption (S EA ), and multiple in-plane reflections (S EMR ), that is

[0066] S ET = SER +S EA +S EMR ;

[0067] For highly conductive materials, the contribution of multiple in-plane reflections to the total electromagnetic shielding effectiveness is very small and can be ignored. Therefore, the electromagnetic shielding effectiveness of the material consists of reflection and absorption.

[0068] SER = 10 log(1 - 1 / R) = 10 log(1 / (1 - |S11| 2 ));

[0069] SEA = 10 log((1 - R) / T) = 10 log((1 - |S11| 2 ) / |S21| 2 ).

[0070] (2) Transmittance test

[0071] The transmittance of the electromagnetic shielding film in the visible light band of 300 - 800 nm was measured using an ultraviolet / visible spectrometer (Shimadzu UV3600).

[0072] Example 1

[0073] Step 1: Pretreatment of the substrate film and fixation of the substrate film

[0074] A rotating cylinder with a diameter of 10 cm and a depth of 10 cm (made of aluminum alloy) was selected. The 10 cm × 33.5 cm PET substrate film was first washed with water and then with ethanol, and dried naturally; after the substrate film was dried, it was fixed to the inner wall of the rotating cylinder.

[0075] Step 2: Start the motor to make the rotating speed of the rotating cylinder reach the set value until it is stable

[0076] Operate the motor control panel to adjust the motor speed to 3000 r / min and wait for the speed to stabilize.

[0077] Step 3: Atomize and spray the coating liquid on the surface of the substrate film in the cylinder

[0078] The silver nanowires were dispersed in ethanol to prepare a coating liquid with a concentration of 0.1 mg / mL. The coating liquid was evenly sprayed on the surface of the substrate film on the inner wall of the rotating cylinder using an atomizing sprayer; the distance between the spray nozzle and the substrate film was 50 mm, the horizontal moving distance of the spray nozzle relative to the substrate film was 2 - 8 cm, the moving speed was 50 cm / min, the sample injection speed of the atomizing sprayer was 2 mL / min, and the atomizing pressure was 1 MPa.

[0079] Step 4: Dry and cure the coating liquid to form a film

[0080] Turn on the infrared drying lamp, set the temperature to 80 °C, continue to rotate, and dry the coating liquid on the inner wall of the rotating cylinder to cure it into a film.

[0081] Repeat steps 3 and 4 until the areal density of the obtained electromagnetic shielding film is 500 mg / m 2 .

[0082] Example 2

[0083] Except that "dispersing silver nanowires in ethanol" is adjusted to "dispersing silver nanowires in water", and "repeat steps 3 and 4 until the areal density of the obtained electromagnetic shielding film is 500 mg / m 2 " is adjusted to "repeat steps 3 and 4 until the areal density of the obtained electromagnetic shielding film is 1000 mg / m 2 ", and the corresponding parameters are adjusted according to Table 1, the rest is the same as Example 1.

[0084] Examples 3 - 19

[0085] Except that the corresponding parameters are adjusted according to Table 1, the rest is the same as Example 1.

[0086] Comparative Examples 1 - 2

[0087] Except that the corresponding parameters are adjusted according to Table 1, the rest is the same as Example 1.

[0088] The preparation parameters and result parameters of each example and comparative example are shown in Table 1.

[0089] Table 1

[0090]

[0091]

[0092] Data such as the areal density, scanning electron microscope image (SEM) display results, and electromagnetic shielding effectiveness of the electromagnetic shielding films prepared in the above examples and comparative examples are shown in Table 2 below. Among them, SEM images of randomly selected areas of the electromagnetic shielding films prepared in Example 1 and Example 2 are respectively as Figure 1 and Figure 2 shown, and the electromagnetic shielding effectiveness diagrams of the electromagnetic shielding films prepared in Example 1 and Example 2 in the X - band are respectively as Figure 3 and Figure 4 shown, where EMI SE refers to the electromagnetic shielding efficiency.

[0093] Table 2

[0094]

[0095]

[0096] From Figure 1 andFigure 2 It can be seen that for the electromagnetic shielding films prepared in Example 1 and Example 2, at a low magnification, the density of silver nanowires is large and the distribution is very uniform, without any coffee rings and uneven distribution areas.

[0097] It can be seen from Figure 3 It can be seen that the shielding effectiveness of the electromagnetic shielding film prepared in Example 1 is mainly reflection-based, and the total shielding effectiveness reaches 37.62 dB, which can block more than 99.98% of the incident electromagnetic wave energy. At the same time, the light transmittance at 550 nm reaches 91.17%.

[0098] It can be seen from Figure 4 It can be seen that the shielding effectiveness of the electromagnetic shielding film prepared in Example 2 is mainly reflection-based, and the total shielding effectiveness reaches 51.64 dB, which can block more than 99.999% of the incident electromagnetic wave energy. At the same time, the light transmittance at 550 nm reaches 83.47%.

[0099] As can be seen from Table 2, the electromagnetic shielding films prepared in Examples 1-16 of the present application are all very evenly distributed, without any coffee rings, have good total shielding effectiveness, a high percentage of blocked incident electromagnetic wave energy, and a high light transmittance at 550 nm. It can be seen from Examples 17-19 that when the sample injection speed of the atomizer is not within the range of 0.1 mL / min - 20 mL / min, or the atomization pressure is not within the range of 0.1 MPa - 10 MPa, or the temperature of the infrared drying lamp is not within the range of 50°C - 300°C, the prepared electromagnetic shielding film is not evenly distributed; as can be seen from Comparative Examples 1-2, when the rotation speed of the rotating cylinder is not within the range of the present application, the prepared electromagnetic shielding film is unevenly distributed and the total shielding effectiveness is poor.

[0100] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing an electromagnetic shielding film, comprising the steps of: Step 1: lay the basement membrane flat and fix it on the inner wall of the drum; Step 2: Control the rotating speed of the drum to 1000r / min-10000r / min; Step 3: Ultrafinely atomizing the coating liquid and spraying it on the surface of the base film on the inner wall of the drum; Step 4: solidify the coating liquid to obtain an electromagnetic shielding film.

2. The preparation method according to claim 1, wherein The diameter of the rotating drum is 10 cm-30 cm, and the depth of the rotating drum is 10 cm-30 cm.

3. The preparation method according to claim 1, wherein The concentration of the coating solution is 0.01 mg / mL-10 mg / mL.

4. The preparation method according to claim 1, wherein The injection speed of the nebulizer used for the atomization is 0.1mL / min-20mL / min, and the atomization pressure is 0.1MPa-10MPa.

5. The preparation method according to claim 1, wherein During the spraying, the distance between the nozzle and the surface of the base film is 50mm-200mm, the horizontal movement distance of the nozzle relative to the base film is 0cm-30cm, and the horizontal movement speed of the nozzle relative to the base film is 0cm / min-100cm / min.

6. The preparation method according to claim 1, wherein The curing is performed by using an infrared drying lamp.

7. The preparation method according to claim 6, wherein: The temperature of the infrared drying lamp is 50°C-300°C.

8. The preparation method according to claim 1, wherein Repeat step 3 and step 4 in sequence.

9. The preparation method according to claim 1, wherein The basement membrane is selected from a water-based basement membrane or an organic basement membrane; Preferably, before the basement membrane is laid flat and fixed on the inner wall of the drum, a pretreatment step is also included: washing the organic basement membrane with water and ethanol in sequence, and then drying; or washing the aqueous basement membrane with water and then drying.

10. The preparation method according to any one of claims 1 to 9, wherein The material of the rotating drum is aluminum alloy or polytetrafluoroethylene.

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