Method for manufacturing flexible electromagnetic shielding film having stretchable properties

Abstract

This invention discloses a flexible electromagnetic shielding film with stretchable properties and its preparation method. The electromagnetic shielding film includes a flexible organic transparent substrate, a metal alloy nanowire conductive layer, and an anti-reflection protective layer. A portion of the metal alloy nanowire is embedded in the upper and lower surfaces of the flexible organic transparent substrate, and the exposed surface of the metal alloy nanowire is covered with the anti-reflection protective layer. The preparation method includes the following steps: preparing a metal alloy solution for forming the metal alloy nanowire; preparing a metal alloy nanowire conductive film; embedding a portion of the metal alloy nanowire into the upper and lower surfaces of the flexible organic transparent substrate by hot pressing; and preparing Cu for forming the anti-reflection protective layer. x O solution; Coating the outer surface of the metal alloy nanowires exposed on the upper and lower surfaces of the flexible organic transparent substrate with Cu x O Anti-reflective protective layer. The electromagnetic shielding film of this invention has high transmittance, low haze, high electromagnetic shielding effectiveness, and high ductility, and is not easy to fall off, making it widely applicable to wearable devices.

Description

Preparation method of flexible electromagnetic shielding film with stretchable properties Technical Field

[0001] This invention belongs to the field of optical thin film preparation technology, specifically relating to a flexible electromagnetic shielding film with stretchable properties and its preparation method. Background Technology

[0002] With social development and improved living standards, people have placed higher demands on environmental quality and the shielding effectiveness of electromagnetic radiation. On the one hand, with the popularization of wearable devices and the development of 5G and even 6G technologies, shielding materials need to have a shielding effectiveness greater than 40dB. On the other hand, with technological advancements, people's demands for wearable devices are increasing; these devices need to be flexible and stretchable. However, traditional transparent conductive oxide (ITO) is inherently brittle and cannot meet the requirements of wearable devices for transparent conductive films. Therefore, it is necessary to develop a novel electromagnetic shielding film and its preparation method, enabling the electromagnetic shielding film to possess flexible and stretchable properties.

[0003] The invention patent with publication number CN110491549A discloses a stretchable flexible anti-reflection conductive film and its preparation method. The conductive film includes an organic transparent substrate with a micro-protrusion structure regularly distributed on the surface, a metal nanowire conductive layer covered on the organic transparent substrate with the micro-protrusion structure, and an oxide protective layer covered on the surface of the metal nanowire conductive layer. The organic transparent substrate is made of polydimethylsiloxane or polyurethane, the metal nanowires in the metal nanowire conductive layer are silver nanowires, copper nanowires or gold nanowires, and the oxide protective layer is made of niobium pentoxide, titanium dioxide, tungsten oxide, indium tin oxide, zinc oxide, gallium oxide, gallium zinc oxide or indium zinc oxide. The preparation method of this conductive film includes the following steps: On an anodic aluminum oxide template, regularly distributed inverted conical or frustum-shaped pit structures are prepared on its surface using electrochemical etching. Then, an organic sol-gel of an organic transparent substrate is spin-coated, followed by vacuum hot pressing and curing to obtain an organic transparent substrate with regularly arranged conical or frustum-shaped micro-convex structures on its surface. A metal nanowire solution is spin-coated onto the surface of the organic transparent substrate, and after drying, a metal nanowire conductive layer is obtained. An oxide protective layer is deposited on the metal nanowire conductive layer using magnetron sputtering. The metal wires used in this technical solution are pure metal nanowires, which are not embedded in a flexible transparent substrate. The surface of the pure metal nanowires also lacks an anti-glare structure. Therefore, the prepared electromagnetic shielding film does not have excellent environmental weather resistance, poor adhesion, lacks a structure layer to reduce haze, and does not possess the high electromagnetic shielding performance resulting from the resonance of double-sided conductive films.

[0004] Chinese patent application CN110767075A discloses a flexible anti-counterfeiting layer based on a metal micro / nano network, its preparation method, and its uses. The metal in the metal micro / nano network of this anti-counterfeiting layer is a single metal element and / or an alloy. The single metal element is any one of gold, silver, or copper, and the alloy is any one of gold-silver alloy, gold-copper alloy, copper-silver alloy, or gold-silver-copper alloy. The preparation method of this anti-counterfeiting layer includes the following steps: preparing a metal material; patterning the metal material to obtain a metal network with a specific pattern, i.e., a patterned metal network; and transferring the obtained patterned metal network onto the product requiring anti-counterfeiting to obtain the flexible anti-counterfeiting layer of the metal micro / nano network. The metal network in this technical solution has a regular grid shape and is prepared by etching. The resulting anti-counterfeiting layer has low environmental weather resistance, adhesion, and shielding effectiveness. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a flexible electromagnetic shielding film with stretchable properties, comprising a flexible organic transparent substrate, a metal alloy nanowire conductive layer, and an anti-reflection protective layer. The metal alloy nanowire conductive layer has an irregular network structure, which is formed by interlacing metal alloy nanowires. A portion of the metal alloy nanowires is embedded in the upper and lower surfaces of the flexible organic transparent substrate, while another portion of the metal alloy nanowires is exposed on the upper and lower surfaces of the flexible organic transparent substrate. The outer surface of the metal alloy nanowires exposed on the upper and lower surfaces of the flexible organic transparent substrate is covered by the anti-reflection protective layer.

[0006] Preferably, the flexible organic transparent substrate is made of polydimethylsiloxane or polyurethane; the thickness of the flexible organic transparent substrate is 1-2 mm.

[0007] Preferably, in any of the above embodiments, the material of the metal alloy nanowire is silver alloy nanowire or copper alloy nanowire; the shape of the metal alloy nanowire is cylindrical, with a diameter of 200-300 nm and a length of [missing information]. The portion of the metal alloy nanowire embedded in the upper and lower surfaces of the flexible organic transparent substrate is 50-68% of the diameter of the metal alloy nanowire. The metal alloy nanowire designed in this invention differs from ordinary silver or copper nanowires; it possesses excellent oxidation resistance and superior environmental weather resistance, making it suitable for outdoor use in wearable devices. This invention uses metal alloy nanowires as an electromagnetic shielding layer, forming a stable electromagnetic shielding layer by semi-embedding them on the surface of the transparent substrate. This method not only significantly improves the adhesion of the electromagnetic shielding layer but also enhances its ductility.

[0008] Preferably, in any of the above embodiments, the material of the anti-reflective protective layer is... Where x = 1-2; the thickness of the anti-reflection protective layer is 30-80 nm. The anti-reflection protective layer designed in this invention can further prevent the metal alloy nanowires from being oxidized, improve the environmental weather resistance of the metal alloy nanowires, and at the same time reduce the reflection of incident light, thereby reducing the haze of the electromagnetic shielding structure of the metal alloy nanowires and improving the clarity of the electromagnetic shielding structure.

[0009] This invention also provides a method for preparing a flexible electromagnetic shielding film with stretchable properties, applied to any of the above-mentioned flexible electromagnetic shielding films with stretchable properties, comprising the following steps in sequence:

[0010] Step 1: Prepare a metal alloy solution for forming metal alloy nanowires;

[0011] Step 2: Select glass as the substrate for the metal alloy nanowire conductive film and clean the glass; use a spin coater to spin coat the metal alloy solution onto the upper surface of the glass to form metal alloy nanowires; place the glass and the metal alloy nanowires on it into an oven for baking to cure the metal alloy nanowires. After curing, a metal alloy nanowire conductive film attached to the glass substrate is obtained.

[0012] Step 3: Place glass with attached metal alloy nanowire conductive films on the upper and lower surfaces of the flexible organic transparent substrate, respectively, so that the metal alloy nanowires are in contact with the upper and lower surfaces of the flexible organic transparent substrate. That is, the two metal alloy nanowire conductive films are located between the upper surface of the flexible organic transparent substrate and the glass and between the lower surface of the flexible organic transparent substrate and the glass, respectively.

[0013] Step 4: Vacuum pack the flexible organic transparent substrate and the metal alloy nanowire conductive film on its upper and lower surfaces, along with the glass as a whole, and place them in an autoclave for hot pressing, so that a portion of the metal alloy nanowires are embedded in the upper and lower surfaces of the flexible organic transparent substrate; after the hot pressing is completed, peel the glass off the metal alloy nanowire conductive film.

[0014] Step 5: Prepare the anti-reflection protective layer Solution;

[0015] Step Six: Place the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces into the substrate. The reaction takes place in solution, causing a layer to coat the outer surface of the metal alloy nanowires exposed on the upper and lower surfaces of a flexible organic transparent substrate. By adding an anti-reflective protective layer, a flexible electromagnetic shielding film with stretchable properties can be obtained.

[0016] Preferably, in step one, the method for preparing the silver alloy solution used to form the silver alloy nanowires is as follows: weigh out NaOH solution, ... Solution The solution is prepared by thoroughly mixing the three solutions to form a mixed solution, wherein the concentration of the NaOH solution is 20-25 mol / L. The concentration of the solution is 0.15-0.2 mol / L. The concentration of the solution is 0.05-0.1 mol / L, NaOH solution, Solution The volume ratio of the solutions is 250:5:1; the mixed solution is heated in a water bath at 90-95℃ for 10-20 minutes; ethanol is added to the mixed solution, and the ethanol and... With a solution volume ratio of 1:2.5, maintaining a heating temperature of 90-95℃ and continuing to hold at this temperature for 10-20 minutes, a solution suitable for forming silver alloy nanowires can be obtained. A solution, where x = 1-5.

[0017] The method for preparing the copper alloy solution used to form copper alloy nanowires is as follows: weigh out NaOH solution, ... Solution The solution is prepared by thoroughly mixing the three solutions to form a mixed solution, wherein the concentration of the NaOH solution is 20-25 mol / L. The concentration of the solution is 0.1-0.15 mol / L. The concentration of the solution is 0.05-0.1 mol / L, NaOH solution, Solution The volume ratio of the solutions is 50:2.5:1; the mixed solution is heated in a water bath at 90-95℃ for 10-20 minutes; ethanol is added to the mixed solution, and the ethanol and... With a solution volume ratio of 1:5, maintaining a heating temperature of 90-95℃ and continuing to hold at this temperature for 10-20 minutes, a solution suitable for forming copper alloy nanowires can be obtained. A solution, where x = 5-10.

[0018] In any of the above schemes, it is preferred that, in step two, the spin coating speed is 1000-1500 r / min, the spin coating time is 5-8 min, the baking temperature is 100-110℃, and the baking time is 30-40 min.

[0019] In any of the above schemes, it is preferred that, in step four, the hot pressing temperature is 120-140℃, the hot pressing pressure is 5-7 bar, and the hot pressing time is 1-1.5 h.

[0020] In any of the above schemes, it is preferred that, in step five, the anti-reflective protective layer is formed. The solution is prepared by weighing out the following amounts: The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.1-0.15 mol / L. The volume ratio of the solution to deionized water is 2:1; add 30-35 mg of sodium dodecyl sulfate to the mixed solution, and after complete dissolution, a protective layer for forming anti-reflective coating can be obtained. Solution.

[0021] In any of the above embodiments, it is preferred that, in step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed as a whole. The reaction takes place in solution and lasts for 1-1.5 hours.

[0022] This invention relates to a flexible electromagnetic shielding film with stretchable properties and its preparation method. The film utilizes metal alloy nanowires as a conductive layer. Its core functional layer relies primarily on the conductivity of the metal alloy nanowires to reflect incident electromagnetic waves, thus achieving electromagnetic shielding. After spin-coating, the metal alloy nanowires overlap on a transparent substrate to form a network structure, which is then embedded into the transparent substrate surface through hot pressing, thereby endowing the electromagnetic shielding film with stretchable properties. The electromagnetic shielding film prepared by this invention exhibits an electromagnetic shielding effectiveness of no less than 50 dB, a transmittance of no less than 87%, a haze of no more than 0.5%, and an elongation of at least 380% within the 2-18 GHz range. Attached Figure Description

[0023] Figure 1 is a cross-sectional view of a preferred embodiment of a flexible electromagnetic shielding film with stretchable properties according to the present invention;

[0024] Figure 2 is a schematic diagram showing the location of the metal alloy nanowires in the embodiment shown in Figure 1;

[0025] Figure 3 shows the surface morphology of the flexible electromagnetic shielding film with stretchable properties prepared according to the embodiment shown in Figure 1.

[0026] The diagram shows: 1- Flexible organic transparent substrate, 2- Conductive layer of metal alloy nanowires, 3- Anti-reflective protective layer, 4- Metal alloy nanowires. Detailed Implementation

[0027] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0028] Example 1:

[0029] As shown in Figures 1-2, a preferred embodiment of the flexible electromagnetic shielding film with stretchable properties according to the present invention includes a flexible organic transparent substrate 1, a metal alloy nanowire conductive layer 2, and an anti-reflection protective layer 3. The metal alloy nanowire conductive layer 2 has an irregular network structure, which is formed by interlacing metal alloy nanowires 4. A portion of the metal alloy nanowires 4 is embedded in the upper and lower surfaces of the flexible organic transparent substrate 1, and another portion of the metal alloy nanowires 4 is exposed on the upper and lower surfaces of the flexible organic transparent substrate 1. The outer surface of the metal alloy nanowires 4 exposed on the upper and lower surfaces of the flexible organic transparent substrate 1 is covered by the anti-reflection protective layer 3.

[0030] The flexible organic transparent substrate is made of polydimethylsiloxane and has a thickness of 1 mm.

[0031] The metal alloy nanowires are made of copper alloy nanowires, and the copper alloy nanowires are cylindrical in shape with a diameter of 200 nm and a length of [missing information]. The portion of the copper alloy nanowire embedded in the upper and lower surfaces of the flexible organic transparent substrate is 50% of the diameter of the copper alloy nanowire. The copper alloy nanowire designed in this embodiment differs from ordinary copper metal nanowires; it possesses excellent oxidation resistance and superior environmental weather resistance. This embodiment uses copper alloy nanowires as an electromagnetic shielding layer, forming a stable electromagnetic shielding layer by semi-embedding them on the surface of the transparent substrate. This method not only significantly improves the adhesion of the electromagnetic shielding layer but also enhances its ductility.

[0032] The anti-reflection protective layer is made of CuO and has a thickness of 30 nm. The anti-reflection protective layer designed in this embodiment can further prevent the copper alloy nanowires from being oxidized, improve the environmental weather resistance of the copper alloy nanowires, and reduce the reflection of incident light, thereby reducing the haze of the copper alloy nanowire electromagnetic shielding structure and improving the clarity of the electromagnetic shielding structure.

[0033] This embodiment also provides a method for preparing a flexible electromagnetic shielding film with stretchable properties, applied to the aforementioned flexible electromagnetic shielding film with stretchable properties, comprising the following steps in sequence:

[0034] Step 1: Prepare a metal alloy solution for forming metal alloy nanowires;

[0035] Step 2: Select glass as the substrate for the metal alloy nanowire conductive film and clean the glass; use a spin coater to spin coat the metal alloy solution onto the upper surface of the glass to form metal alloy nanowires; place the glass and the metal alloy nanowires on it into an oven for baking to cure the metal alloy nanowires. After curing, a metal alloy nanowire conductive film attached to the glass substrate is obtained.

[0036] Step 3: Place glass with attached metal alloy nanowire conductive films on the upper and lower surfaces of the flexible organic transparent substrate, respectively, so that the metal alloy nanowires are in contact with the upper and lower surfaces of the flexible organic transparent substrate. That is, the two metal alloy nanowire conductive films are located between the upper surface of the flexible organic transparent substrate and the glass and between the lower surface of the flexible organic transparent substrate and the glass, respectively.

[0037] Step 4: Vacuum pack the flexible organic transparent substrate and the metal alloy nanowire conductive film on its upper and lower surfaces, along with the glass as a whole, and place them in an autoclave for hot pressing, so that a portion of the metal alloy nanowires are embedded in the upper and lower surfaces of the flexible organic transparent substrate; after the hot pressing is completed, peel the glass off the metal alloy nanowire conductive film.

[0038] Step 5: Prepare the anti-reflection protective layer Solution;

[0039] Step Six: Place the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces into the substrate. The reaction takes place in solution, causing a layer to coat the outer surface of the metal alloy nanowires exposed on the upper and lower surfaces of a flexible organic transparent substrate. By adding an anti-reflective protective layer, a flexible electromagnetic shielding film with stretchable properties can be obtained.

[0040] In step one, the metal alloy nanowires are copper alloy nanowires. The method for preparing the copper alloy solution used to form the copper alloy nanowires is as follows: weigh out NaOH solution, ... Solution The solution is prepared by thoroughly mixing the three solutions to form a mixed solution, wherein the concentration of the NaOH solution is 20 mol / L. The concentration of the solution is 0.1 mol / L. The concentration of the solution is 0.1 mol / L, NaOH solution, Solution The volume ratio of the solutions is 50:2.5:1, that is, NaOH solution, Solution The solutions were prepared with volumes of 1000 ml, 50 ml, and 20 ml, respectively. The mixed solution was heated in a water bath at 90°C for 10 minutes. Ethanol was then added to the mixed solution. The volume ratio of the solution is 1:5, i.e., the volume of ethanol is 10 ml. Maintaining the heating temperature at 90℃ and continuing this temperature for 10 minutes yields a solution suitable for forming copper alloy nanowires. Solution. The chemical reagents used in this example were purchased from a chemical reagent website.

[0041] In step two, the spin coating speed is 1000 r / min and the spin coating time is 5 min; the baking temperature is 100℃ and the baking time is 30 min.

[0042] In step four, the hot pressing temperature is 120℃, the hot pressing pressure is 5 bar, and the hot pressing time is 1 hour.

[0043] In step five, the CuO solution used to form the antireflective protective layer is prepared as follows: weigh out the following amounts respectively. The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.1 mol / L. The volume ratio of the solution to deionized water is 2:1, that is... The volumes of the solution and deionized water are 10 ml and 5 ml, respectively. Sodium dodecyl sulfate is added to the mixed solution at a dosage of 30 mg. After complete dissolution, a CuO solution for forming an anti-reflective protective layer is obtained.

[0044] In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed into a CuO solution for reaction, and the reaction time is 1 hour.

[0045] This embodiment describes a flexible electromagnetic shielding film with stretchable properties and its preparation method. The film uses copper alloy nanowires as the conductive layer. Its core functional layer relies primarily on the conductivity of the copper alloy nanowires to reflect incident electromagnetic waves and generate electromagnetic shielding. After spin-coating, the copper alloy nanowires overlap to form a network structure on the surface of a transparent substrate, and then are embedded into the transparent substrate surface through hot pressing, thus giving the electromagnetic shielding film stretchable properties. The surface morphology of the flexible electromagnetic shielding film with stretchable properties prepared in this embodiment is shown in Figure 3. Within the 2-18 GHz range, this electromagnetic shielding film exhibits an electromagnetic shielding effectiveness of 56 dB, a transmittance of 89%, a haze of 0.3%, and an elongation of 390%.

[0046] Example 2:

[0047] According to another preferred embodiment of the flexible electromagnetic shielding film with stretchable properties and its preparation method of the present invention, the structure, preparation process, equipment used, chemical reagent suppliers, technical principles, and beneficial effects of the electromagnetic shielding film are basically the same as those of Embodiment 1, except that:

[0048] For a flexible electromagnetic shielding film with stretchable properties: the flexible organic transparent substrate is made of polyurethane with a thickness of 1.5 mm; the metal alloy nanowires are made of copper alloy nanowires with a diameter of 250 nm and a length of... The copper alloy nanowires embedded on both the upper and lower surfaces of the flexible organic transparent substrate are 55% of the diameter of the copper alloy nanowires; the anti-reflective protective layer is made of... Its thickness is 50nm.

[0049] Methods for preparing flexible electromagnetic shielding films with stretchable properties:

[0050] In step one, the metal alloy nanowires are copper alloy nanowires. The method for preparing the copper alloy solution used to form the copper alloy nanowires is as follows: weigh out NaOH solution, ... Solution The three solutions are thoroughly mixed to form a mixed solution, wherein the concentration of the NaOH solution is 25 mol / L. The concentration of the solution is 0.15 mol / L. The concentration of the solution is 0.05 mol / L, NaOH solution, Solution The volume ratio of the solutions is 50:2.5:1, that is, NaOH solution, Solution The solutions were prepared with volumes of 1000 ml, 50 ml, and 20 ml, respectively. The mixed solution was heated in a water bath at 95°C for 20 minutes. Ethanol was then added to the mixed solution. The volume ratio of the solution is 1:5, i.e., the volume of ethanol is 10 ml. Maintaining the heating temperature at 95℃ and continuing this temperature for 20 minutes yields a solution suitable for forming copper alloy nanowires. Solution.

[0051] In step two, the spin coating speed is 1200 r / min and the spin coating time is 6 min; the baking temperature is 105℃ and the baking time is 35 min.

[0052] In step four, the hot pressing temperature is 130℃, the hot pressing pressure is 6 bar, and the hot pressing time is 1.2 hours.

[0053] In step five, the anti-reflective protective layer is formed. The solution is prepared by weighing out the following amounts: The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.12 mol / L. The volume ratio of the solution to deionized water is 2:1, that is... The volumes of the solution and deionized water are 10 ml and 5 ml, respectively; add 32 mg of sodium dodecyl sulfate to the mixed solution, and after complete dissolution, a protective layer for forming anti-reflective coating is obtained. Solution.

[0054] In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed as a whole. The reaction takes place in solution and the reaction time is 1.2 h.

[0055] The electromagnetic shielding film prepared in this embodiment has an electromagnetic shielding effectiveness of 53dB, a transmittance of 87%, a haze of 0.2%, and an elongation of 410% in the 2-18GHz range.

[0056] Example 3:

[0057] According to another preferred embodiment of the flexible electromagnetic shielding film with stretchable properties and its preparation method of the present invention, the structure, preparation process, equipment used, chemical reagent suppliers, technical principles, and beneficial effects of the electromagnetic shielding film are basically the same as those of Embodiment 1, except that:

[0058] For a flexible electromagnetic shielding film with stretchable properties: the flexible organic transparent substrate is made of polyurethane with a thickness of 1.8 mm; the metal alloy nanowires are made of copper alloy nanowires with a diameter of 230 nm and a length of [missing information]. The portion of the copper alloy nanowire embedded on the upper and lower surfaces of the flexible organic transparent substrate is 62% of the diameter of the copper alloy nanowire; the material of the anti-reflective protective layer is... Its thickness is 60nm.

[0059] Methods for preparing flexible electromagnetic shielding films with stretchable properties:

[0060] In step one, the metal alloy nanowires are copper alloy nanowires. The method for preparing the copper alloy solution used to form the copper alloy nanowires is as follows: weigh out NaOH solution, ... Solution The three solutions are thoroughly mixed to form a mixed solution, wherein the concentration of the NaOH solution is 25 mol / L. The concentration of the solution is 0.12 mol / L. The concentration of the solution is 0.08 mol / L, NaOH solution, Solution The volume ratio of the solutions is 50:2.5:1, that is, NaOH solution, Solution The solutions were prepared with volumes of 1000 ml, 50 ml, and 20 ml, respectively. The mixed solution was heated in a water bath at 95°C for 20 minutes. Ethanol was then added to the mixed solution. The volume ratio of the solution is 1:5, i.e., the volume of ethanol is 10 ml. Maintaining the heating temperature at 95℃ and continuing this temperature for 20 minutes yields a solution suitable for forming copper alloy nanowires. Solution.

[0061] In step two, the spin coating speed is 1400 r / min and the spin coating time is 7 min; the baking temperature is 105℃ and the baking time is 35 min.

[0062] In step four, the hot pressing temperature is 135℃, the hot pressing pressure is 6 bar, and the hot pressing time is 1.4 hours.

[0063] In step five, the anti-reflective protective layer is formed. The solution is prepared by weighing out the following amounts: The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.12 mol / L. The volume ratio of the solution to deionized water is 2:1, that is... The volumes of the solution and deionized water are 10 ml and 5 ml, respectively; add 32 mg of sodium dodecyl sulfate to the mixed solution, and after complete dissolution, a protective layer for forming anti-reflective coating is obtained. Solution.

[0064] In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed as a whole. The reaction takes place in solution and the reaction time is 1.2 h.

[0065] The electromagnetic shielding film prepared in this embodiment has an electromagnetic shielding effectiveness of 57dB, a transmittance of 92%, a haze of 0.1%, and an elongation of 432% in the 2-18GHz range.

[0066] Example 4:

[0067] According to another preferred embodiment of the flexible electromagnetic shielding film with stretchable properties and its preparation method of the present invention, the structure, preparation process, equipment used, chemical reagent suppliers, technical principles, and beneficial effects of the electromagnetic shielding film are basically the same as those of Embodiment 1, except that:

[0068] For a flexible electromagnetic shielding film with stretchable properties: the flexible organic transparent substrate is made of polyurethane with a thickness of 2 mm; the metal alloy nanowires are made of silver alloy nanowires with a diameter of 300 nm and a length of [missing information]. The portion of the silver alloy nanowire embedded on the upper and lower surfaces of the flexible organic transparent substrate is 68% of the diameter of the silver alloy nanowire; the material of the anti-reflective protective layer is... Its thickness is 80nm.

[0069] Methods for preparing flexible electromagnetic shielding films with stretchable properties:

[0070] In step one, the metal alloy nanowires are silver alloy nanowires. The method for preparing the silver alloy solution used to form the silver alloy nanowires is as follows: weigh out NaOH solution, ... Solution The solution is prepared by thoroughly mixing the three solutions to form a mixed solution, wherein the concentration of the NaOH solution is 20 mol / L. The concentration of the solution is 0.15 mol / L. The concentration of the solution is 0.05 mol / L, NaOH solution, Solution The volume ratio of the solutions is 250:5:1, that is, NaOH solution, Solution The volumes of the solutions were 1000 ml, 20 ml, and 4 ml, respectively; the mixed solution was heated in a water bath at 90°C for 10 min; ethanol was added to the mixed solution, and the ethanol and... The volume ratio of the solution is 1:2.5, i.e., the volume of ethanol is 8 ml. Maintaining the heating temperature at 90℃ and continuing this temperature for 10 minutes yields the solution used to form silver alloy nanowires. Solution.

[0071] In step two, the spin coating speed is 1500 r / min and the spin coating time is 8 min; the baking temperature is 110℃ and the baking time is 40 min.

[0072] In step four, the hot pressing temperature is 140℃, the hot pressing pressure is 7 bar, and the hot pressing time is 1.5 hours.

[0073] In step five, the anti-reflective protective layer is formed. The solution is prepared by weighing out the following amounts: The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.15 mol / L. The volume ratio of the solution to deionized water is 2:1, that is... The volumes of the solution and deionized water are 10 ml and 5 ml, respectively; add 35 mg of sodium dodecyl sulfate to the mixed solution, and after complete dissolution, a protective layer for forming anti-reflective coating is obtained. Solution.

[0074] In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed as a whole. The reaction takes place in solution and the reaction time is 1.5 hours.

[0075] The electromagnetic shielding film prepared in this embodiment has an electromagnetic shielding effectiveness of 58dB, a transmittance of 91%, a haze of 0.2%, and an elongation of 420% in the 2-18GHz range.

[0076] Example 5:

[0077] According to another preferred embodiment of the flexible electromagnetic shielding film with stretchable properties and its preparation method of the present invention, the structure, preparation process, equipment used, chemical reagent suppliers, technical principles, and beneficial effects of the electromagnetic shielding film are basically the same as those of Embodiment 1, except that:

[0078] For a flexible electromagnetic shielding film with stretchable properties: the flexible organic transparent substrate is made of polydimethylsiloxane with a thickness of 1.2 mm; the metal alloy nanowires are made of silver alloy nanowires with a diameter of 280 nm and a length of... The portion of the silver alloy nanowire embedded on the upper and lower surfaces of the flexible organic transparent substrate is 60% of the diameter of the silver alloy nanowire; the anti-reflective protective layer is made of CuO and has a thickness of 60 nm.

[0079] Methods for preparing flexible electromagnetic shielding films with stretchable properties:

[0080] In step one, the metal alloy nanowires are silver alloy nanowires. The method for preparing the silver alloy solution used to form the silver alloy nanowires is as follows: weigh out NaOH solution, ... Solution The three solutions are thoroughly mixed to form a mixed solution, wherein the concentration of the NaOH solution is 25 mol / L. The concentration of the solution is 0.2 mol / L. The concentration of the solution is 0.05 mol / L, NaOH solution, Solution The volume ratio of the solutions is 250:5:1, that is, NaOH solution, Solution The volumes of the solutions were 1000 ml, 20 ml, and 4 ml, respectively; the mixed solution was heated in a water bath at 95°C for 20 min; ethanol was added to the mixed solution, and the ethanol and... The volume ratio of the solution is 1:2.5, i.e., the volume of ethanol is 8 ml. Maintaining the heating temperature at 95℃ for 20 minutes yields the solution suitable for forming silver alloy nanowires. Solution.

[0081] In step two, the spin coating speed is 1300 r / min and the spin coating time is 7 min; the baking temperature is 110℃ and the baking time is 35 min.

[0082] In step four, the hot pressing temperature is 130℃, the hot pressing pressure is 6 bar, and the hot pressing time is 1.5 hours.

[0083] In step five, the CuO solution used to form the antireflective protective layer is prepared as follows: weigh out the following amounts respectively. The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.13 mol / L. The volume ratio of the solution to deionized water is 2:1, that is... The volumes of the solution and deionized water are 10 ml and 5 ml, respectively. Sodium dodecyl sulfate is added to the mixed solution at a dosage of 33 mg. After complete dissolution, a CuO solution for forming an anti-reflective protective layer is obtained.

[0084] In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed into a CuO solution for reaction, and the reaction time is 1.5 h.

[0085] The electromagnetic shielding film prepared in this embodiment has an electromagnetic shielding effectiveness of 59dB, a transmittance of 89%, a haze of 0.2%, and an elongation of 430% in the 2-18GHz range.

[0086] Example 6:

[0087] According to another preferred embodiment of the flexible electromagnetic shielding film with stretchable properties and its preparation method of the present invention, the structure, preparation process, equipment used, chemical reagent suppliers, technical principles, and beneficial effects of the electromagnetic shielding film are basically the same as those of Embodiment 1, except that:

[0088] For a flexible electromagnetic shielding film with stretchable properties: the flexible organic transparent substrate is made of polydimethylsiloxane with a thickness of 1.7 mm; the metal alloy nanowires are made of silver alloy nanowires with a diameter of 290 nm and a length of... The portion of the silver alloy nanowire embedded on the upper and lower surfaces of the flexible organic transparent substrate is 62% of the diameter of the silver alloy nanowire; the anti-reflective protective layer is made of CuO and has a thickness of 70 nm.

[0089] Methods for preparing flexible electromagnetic shielding films with stretchable properties:

[0090] In step one, the metal alloy nanowires are silver alloy nanowires. The method for preparing the silver alloy solution used to form the silver alloy nanowires is as follows: weigh out NaOH solution, ... Solution The three solutions are thoroughly mixed to form a mixed solution, wherein the concentration of the NaOH solution is 25 mol / L. The concentration of the solution is 0.18 mol / L. The concentration of the solution is 0.07 mol / L, NaOH solution, Solution The volume ratio of the solutions is 250:5:1, that is, NaOH solution, Solution The volumes of the solutions were 1000 ml, 20 ml, and 4 ml, respectively; the mixed solution was heated in a water bath at 95°C for 20 min; ethanol was added to the mixed solution, and the ethanol and... The volume ratio of the solution is 1:2.5, i.e., the volume of ethanol is 8 ml. Maintaining the heating temperature at 95℃ for 20 minutes yields the solution suitable for forming silver alloy nanowires. Solution.

[0091] In step two, the spin coating speed is 1100 r / min and the spin coating time is 8 min; the baking temperature is 110℃ and the baking time is 40 min.

[0092] In step four, the hot pressing temperature is 138℃, the hot pressing pressure is 6 bar, and the hot pressing time is 1.5 hours.

[0093] In step five, the CuO solution used to form the antireflective protective layer is prepared as follows: weigh out the following amounts respectively. The solution and deionized water are thoroughly mixed to form a mixed solution, in which... The concentration of the solution is 0.13 mol / L. The volume ratio of the solution to deionized water is 2:1, that is... The volumes of the solution and deionized water are 10 ml and 5 ml, respectively. Sodium dodecyl sulfate is added to the mixed solution at a dosage of 33 mg. After complete dissolution, a CuO solution for forming an anti-reflective protective layer is obtained.

[0094] In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed into a CuO solution for reaction, and the reaction time is 1.5 h.

[0095] The electromagnetic shielding film prepared in this embodiment has an electromagnetic shielding effectiveness of 61dB, a transmittance of 90%, a haze of 0.1%, and an elongation of 439% in the 2-18GHz range.

[0096] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0097] Those skilled in the art will readily understand that the flexible electromagnetic shielding film with stretchable properties and its preparation method of the present invention include any combination of the inventive content and specific embodiments described in the above specification and the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible electromagnetic shielding film with stretchable properties, characterized in that, The preparation method includes the following steps in sequence: Step 1: Prepare a metal alloy solution for forming metal alloy nanowires; Step 2: Select glass as the substrate for the conductive film of metal alloy nanowires and clean the glass; use a spin coater to spin coat the metal alloy solution onto the upper surface of the glass to form metal alloy nanowires; place the glass and the metal alloy nanowires on it into an oven for baking to cure the metal alloy nanowires. After curing, a conductive film of metal alloy nanowires attached to the glass substrate is obtained; Step 3: Place the glass with the attached conductive film of metal alloy nanowires on the upper and lower surfaces of a flexible organic transparent substrate, respectively. The process involves: 1) Making contact between the metal alloy nanowires and the upper and lower surfaces of the flexible organic transparent substrate, i.e., placing two conductive films of metal alloy nanowires between the upper surface of the flexible organic transparent substrate and the glass, and between the lower surface of the flexible organic transparent substrate and the glass, respectively; 2) Vacuum packaging the flexible organic transparent substrate, its upper and lower surfaces, and the glass as a whole, and placing it in an autoclave for hot pressing, so that a portion of the metal alloy nanowires is embedded in the upper and lower surfaces of the flexible organic transparent substrate; 3) After the hot pressing is completed, peeling the glass off the conductive films of the metal alloy nanowires; 4) Preparing Cu for forming the anti-reflection protective layer. x O solution; Step 6: Place the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces into Cu x The reaction is carried out in O solution, so that the outer surface of the metal alloy nanowires exposed on the upper and lower surfaces of the flexible organic transparent substrate is coated with a layer of Cu. x An anti-reflection protective layer is used to obtain a flexible electromagnetic shielding film with stretchable properties. The flexible electromagnetic shielding film includes a flexible organic transparent substrate, a metal alloy nanowire conductive layer, and an anti-reflection protective layer. The metal alloy nanowire conductive layer has an irregular network structure, which is formed by interwoven metal alloy nanowires. A portion of the metal alloy nanowires is embedded in the upper and lower surfaces of the flexible organic transparent substrate, and another portion of the metal alloy nanowires is exposed on the upper and lower surfaces of the flexible organic transparent substrate. The outer surface of the metal alloy nanowires exposed on the upper and lower surfaces of the flexible organic transparent substrate is covered by the anti-reflection protective layer.

2. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 1, characterized in that, In step one, the preparation method of the silver alloy solution used to form silver alloy nanowires is as follows: Weigh out NaOH solution, AgNO3 solution, and Pd(NO3)2 solution respectively, and mix them thoroughly to form a mixed solution. The concentration of NaOH solution is 20-25 mol / L, the concentration of AgNO3 solution is 0.15-0.2 mol / L, and the concentration of Pd(NO3)2 solution is 0.05-0.1 mol / L. The volume ratio of NaOH solution, AgNO3 solution, and Pd(NO3)2 solution is 250:5:

1. Heat the mixed solution in a water bath at 90-95℃ for 10-20 minutes. Add ethanol to the mixed solution, with a volume ratio of ethanol to AgNO3 solution of 1:2.

5. Maintain the heating temperature at 90-95℃ and continue heating for another 10-20 minutes to obtain the AgNO3 solution used to form silver alloy nanowires. 100-x Pd x A solution, where x = 1-5; the preparation method of the copper alloy solution for forming copper alloy nanowires is as follows: Weigh out NaOH solution, Cu(NO3)2 solution, and Pd(NO3)2 solution respectively, and mix them thoroughly to form a mixed solution. The concentration of NaOH solution is 20-25 mol / L, the concentration of Cu(NO3)2 solution is 0.1-0.15 mol / L, and the concentration of Pd(NO3)2 solution is 0.05-0.1 mol / L. The volume ratio of NaOH solution, Cu(NO3)2 solution, and Pd(NO3)2 solution is 50:2.5:

1. Heat the mixed solution in a water bath at 90-95℃ for 10-20 minutes. Add ethanol to the mixed solution, with a volume ratio of ethanol to Cu(NO3)2 solution of 1:

5. Maintain the heating temperature at 90-95℃ and continue heating for 10-20 minutes to obtain the Cu alloy solution used for forming copper alloy nanowires. 100-x Pd x A solution, where x = 5-10.

3. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 2, characterized in that, In step two, the spin coating speed is 1000-1500 r / min and the spin coating time is 5-8 min; the baking temperature is 100-110℃ and the baking time is 30-40 min.

4. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 3, characterized in that, In step four, the hot pressing temperature is 120-140℃, the hot pressing pressure is 5-7 bar, and the hot pressing time is 1-1.5 h.

5. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 4, characterized in that, In step five, Cu is used to form the antireflective protective layer. x The preparation method of O solution is as follows: Weigh out CuCl2 solution and deionized water separately, and mix them thoroughly to form a mixed solution. The concentration of CuCl2 solution is 0.1-0.15 mol / L, and the volume ratio of CuCl2 solution to deionized water is 2:

1. Add sodium dodecyl sulfate to the mixed solution at a dosage of 30-35 mg. After complete dissolution, CuCl2 solution used to form an anti-reflection protective layer is obtained. x O solution.

6. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 5, characterized in that, In step six, the flexible organic transparent substrate and the metal alloy nanowires on its upper and lower surfaces are placed as a whole into Cu. x The reaction takes place in O solution for 1-1.5 hours.

7. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 1, characterized in that, The flexible organic transparent substrate is made of polydimethylsiloxane or polyurethane; the thickness of the flexible organic transparent substrate is 1-2 mm.

8. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 7, characterized in that, The metal alloy nanowires are made of silver alloy nanowires or copper alloy nanowires; the metal alloy nanowires are cylindrical in shape, with a diameter of 200-300 nm and a length of 10-50 μm; the portions of the metal alloy nanowires embedded on the upper and lower surfaces of the flexible organic transparent substrate are 50-68% of the diameter of the metal alloy nanowires.

9. The method for preparing a flexible electromagnetic shielding film with stretchable properties according to claim 8, characterized in that, The anti-reflective protective layer is made of Cu. x O, where x=1-2; the thickness of the antireflective protective layer is 30-80nm.

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