Composite flexible transparent electromagnetic shielding film and method for manufacturing the same

Abstract

The application discloses a kind of composite flexible transparent electromagnetic shielding film and preparation method thereof, the electromagnetic shielding film includes flexible transparent film substrate, first electromagnetic shielding function layer, first organic medium layer, second electromagnetic shielding function layer, second organic medium layer and third electromagnetic shielding function layer arranged in turn from bottom to top;The material of electromagnetic shielding function layer is hexakisamino nickel triphenyl, and the material of organic medium layer is polydimethylsiloxane.The preparation method includes the following steps: hexakisamino nickel triphenyl sol, polydimethylsiloxane, hexakisamino nickel triphenyl sol, polydimethylsiloxane and hexakisamino nickel triphenyl sol are successively scraped on flexible transparent film substrate, baking is needed after each time scraping, and finally composite flexible transparent electromagnetic shielding film is prepared.The electromagnetic shielding film prepared by the technical scheme of the application has high electromagnetic shielding efficiency, good ductility, excellent wave-absorbing performance, and is suitable for electromagnetic shielding of wearable devices.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical film, and particularly relates to a composite flexible transparent electromagnetic shielding film and a preparation method thereof. BACKGROUND

[0002] With the development of society and the improvement of living quality, people have put forward higher requirements for environmental quality and electromagnetic radiation shielding effectiveness, for example, with the popularization of wearable devices and the development of 5G or even 6G technology, the shielding effectiveness of shielding materials needs to be greater than 50 dB, and the shielding materials also need to have high ductility.

[0003] Generally, people prepare electromagnetic shielding glass by directly sputtering or coating a conductive film on a rigid substrate (such as glass), however, the electromagnetic shielding effectiveness of the electromagnetic shielding film prepared by this method does not meet the actual requirements, and the rigid substrate does not have ductility. Therefore, there is an urgent need to develop a new type of electromagnetic shielding film and a preparation method thereof to solve the problems of low shielding effectiveness and poor ductility of the electromagnetic shielding film prepared by the prior art.

[0004] The patent for invention with the application publication number CN111826617A discloses an electromagnetic wave shielding film and a preparation method thereof, the electromagnetic wave shielding film includes a carrier layer, an insulating layer, a metal shielding layer and a conductive adhesive layer which are sequentially stacked, the insulating paste includes PFA resin and at least one selected from polyimide, tetrafluoroethylene, polyphenylene sulfide, polyamide, ethylene-tetrafluoroethylene copolymer, polyetherimide and polyethylene naphthalate, the metal material includes silicon and at least one selected from gold, silver, nickel, chromium, copper, boron, beryllium, aluminum, tin and titanium, the conductive adhesive material includes resin and conductive material, the conductive material is selected from at least one of silver-coated copper, silver-coated nickel, graphene and nanowire. The technical solution improves the ductility and shielding effectiveness of the electromagnetic shielding film by depositing the metal material on the side surface of the insulating layer away from the carrier layer to obtain the metal shielding layer. Although this method can improve the ductility of the film, the improvement is limited, and the structure of the shielding film is complex, the preparation process is complicated and not universal.

[0005] The application patent with the application publication number CN109130383A discloses a kind of double-layer electromagnetic shielding film and preparation method thereof, the electromagnetic shielding film includes carrier film, first insulating coating layer coated on carrier film, second insulating coating layer coated on first insulating coating layer, metal layer compounded on second insulating coating layer, electromagnetic wave shielding coating coated on metal layer, release protection film arranged on electromagnetic wave shielding coating;Carrier film is matte release film, the coating of first insulating coating layer is wear-resistant type acrylate coating or polyurethane coating, the coating of second insulating coating layer is high-filled, high-toughness acrylate coating or polyurethane coating or rubber coating, metal layer is calendered copper foil or calendered aluminum foil or calendered silver foil, the coating of electromagnetic wave shielding coating includes reflection layer matrix resin and metal filler, reflection layer matrix resin is acrylic type or polyurethane type or rubber type, metal filler is flaky silver-coated glass or flaky silver-coated copper powder or leaf-shaped silver-coated copper powder or dendritic silver-coated copper powder.The technical scheme adopts silver, copper, aluminum material calendered metal foil as metal layer and second insulating coating layer to be compounded to improve the ductility of film, this way can improve the ductility of film, but the degree of improvement is limited, and the structure of shielding film is complex, preparation process is complicated, each coating needs different formula, it is not universal. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a composite flexible transparent electromagnetic shielding film, which comprises a flexible transparent film substrate, an electromagnetic shielding functional layer, and an organic medium layer. The electromagnetic shielding functional layer comprises a first electromagnetic shielding functional layer, a second electromagnetic shielding functional layer, and a third electromagnetic shielding functional layer. The organic medium layer comprises a first organic medium layer and a second organic medium layer. The arrangement order of the flexible transparent film substrate, the electromagnetic shielding functional layer, and the organic medium layer from bottom to top is the flexible transparent film substrate, the first electromagnetic shielding functional layer, the first organic medium layer, the second electromagnetic shielding functional layer, the second organic medium layer, and the third electromagnetic shielding functional layer.

[0007] Preferably, the material of the flexible transparent film substrate is polyethylene terephthalate.

[0008] In any of the above-mentioned solutions, preferably, the materials of the first electromagnetic shielding functional layer, the second electromagnetic shielding functional layer, and the third electromagnetic shielding functional layer are all hexaazatriphenylhexanickel.

[0009] The electromagnetic shielding function layer mainly relies on hexaiminotriphenylene nickel to have good absorption effect on electromagnetic shielding. The hexaiminotriphenylene nickel is derived from the translation of Ni3(hexaiminotriphenylene)2, which is abbreviated as Ni3(HITP)2. The hexaiminotriphenylene nickel is a porous two-dimensional material. Electromagnetic waves form multiple reflections and interferences in the inside of the porous two-dimensional material, and then the absorption of electromagnetic waves is generated. By adopting three layers of two-dimensional hexaiminotriphenylene nickel, strong resonance interference of electromagnetic waves can be formed between the three layers of two-dimensional hexaiminotriphenylene nickel, and the absorption performance of the electromagnetic shielding structure to electromagnetic waves is further enhanced, so that the overall electromagnetic wave absorption performance of the electromagnetic shielding film is improved, and excellent electromagnetic shielding efficiency and ductility are exhibited.

[0010] In order to further improve the ductility of the electromagnetic shielding film, polydimethylsiloxane (PDMS) with excellent ductility is used as a medium layer between the conductive layers.

[0011] In any of the above schemes, preferably, the materials of the first organic medium layer and the second organic medium layer are both polydimethylsiloxane.

[0012] In any of the above schemes, preferably, the thickness of the flexible transparent film substrate is 50-125 μm.

[0013] In any of the above schemes, preferably, the thicknesses of the first electromagnetic shielding function layer, the second electromagnetic shielding function layer and the third electromagnetic shielding function layer are all 1-1.5 μm. More preferably, on the basis that the thicknesses of the first electromagnetic shielding function layer, the second electromagnetic shielding function layer and the third electromagnetic shielding function layer are 1-1.5 μm, the thickness ratio of the first electromagnetic shielding function layer to the second electromagnetic shielding function layer is 1:0.8-1.2.

[0014] In any of the above schemes, preferably, the thicknesses of the first organic medium layer and the second organic medium layer are both 1-1.5 mm. More preferably, on the basis that the thicknesses of the first organic medium layer and the second organic medium layer are 1-1.5 mm, the thickness ratio of the first organic medium layer to the second organic medium layer is 1:0.8-1.2.

[0015] The application also provides a preparation method of a composite flexible transparent electromagnetic shielding film, which is applied to the composite flexible transparent electromagnetic shielding film in any of the above schemes and comprises the following steps in sequence:

[0016] Step one: the flexible transparent film substrate is pretreated by oxygen ions, hexaiminotriphenylene nickel sol is coated on the upper surface of the flexible transparent film substrate by using a doctor blade, and then the first electromagnetic shielding function layer is formed by placing the flexible transparent film substrate in an oven for baking.

[0017] Step two: after solidification, use a scraper to scrape polydimethylsiloxane on the upper surface of the first electromagnetic shielding functional layer, then put it into the oven for baking, forming the first organic medium layer;

[0018] Step three: after solidification, use a scraper to scrape hexamino nickel sol on the upper surface of the first organic medium layer, then put it into the oven for baking, forming the second electromagnetic shielding functional layer;

[0019] Step four: after solidification, use a scraper to scrape polydimethylsiloxane on the upper surface of the second electromagnetic shielding functional layer, then put it into the oven for baking, forming the second organic medium layer;

[0020] Step five: after solidification, use a scraper to scrape hexamino nickel sol on the upper surface of the second organic medium layer, then put it into the oven for baking, forming the third electromagnetic shielding functional layer, at this time, the composite flexible transparent electromagnetic shielding film can be prepared.

[0021] In steps one, three and five, the baking temperature is 90-110℃, and the baking time is 2-2.5h.

[0022] In steps two and four, the baking temperature is 80-100℃, and the baking time is 1-2h.

[0023] In the preparation process of the composite flexible transparent electromagnetic shielding film, multiple baking is required, and each baking is to put the film to be baked into the oven, then the oven is heated, and after baking, the oven is cooled.

[0024] Preferably, the synthesis method of the hexamino nickel sol comprises the following steps in the order:

[0025] Step A: preparing a nickel chloride solution with dimethylformamide as the solvent and nickel chloride hexahydrate as the solute;

[0026] Step B: preparing a hexamino nickel salt solution with dimethylformamide as the solvent and hexamino nickel salt hexahydrate as the solute;

[0027] Step C: injecting the nickel chloride solution and the hexamino nickel salt solution into a sealed stirrer for stirring and mixing;

[0028] Step D: after mixing evenly, injecting the mixed solution into a beaker, then putting it into the oven for baking to volatilize the solvent, and the hexamino nickel sol can be prepared.

[0029] In step A, the solvent used is dimethylformamide analytical pure, and the solute used is nickel chloride hexahydrate analytical pure. The concentration of the prepared nickel chloride solution is 30-35mmol / L.

[0030] In step B, the solvent used is analytical grade dimethylformamide, and the concentration of the prepared hexaaminotriphenylhexahydrochloride solution is 18-21 mmol / L.

[0031] In step C, the stirring speed is 500-600 r / min, and the stirring time is 2-3 h.

[0032] In step D, the baking temperature is 90-100℃ and the baking time is 1-1.5h.

[0033] The composite flexible transparent electromagnetic shielding film and its preparation method of this invention are simple in structure and convenient to operate. The prepared electromagnetic shielding film has high electromagnetic shielding effectiveness, good elongation performance, and excellent wave absorption performance, making it suitable for electromagnetic shielding of wearable devices. The electromagnetic shielding film has an electromagnetic shielding effectiveness greater than 60dB in the 8-20GHz range, an electromagnetic wave absorption effectiveness greater than 50dB, a visible light (380-780 nm) transmittance greater than 60%, and an elongation greater than 5%. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a preferred embodiment of the composite flexible transparent electromagnetic shielding film according to the present invention.

[0035] The diagram shows the following labels: 1- Flexible transparent film substrate, 2- First electromagnetic shielding functional layer, 3- First organic dielectric layer, 4- Second electromagnetic shielding functional layer, 5- Second organic dielectric layer, 6- Third electromagnetic shielding functional layer. Detailed Implementation

[0036] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0037] Example 1:

[0038] like Figure 1 As shown, according to a preferred embodiment of the composite flexible transparent electromagnetic shielding film of the present invention, it includes a flexible transparent film substrate 1, an electromagnetic shielding functional layer, and an organic dielectric layer; the electromagnetic shielding functional layer includes a first electromagnetic shielding functional layer 2, a second electromagnetic shielding functional layer 4, and a third electromagnetic shielding functional layer 6, and the organic dielectric layer includes a first organic dielectric layer 3 and a second organic dielectric layer 5; the flexible transparent film substrate, the electromagnetic shielding functional layer, and the organic dielectric layer are arranged in the following order from bottom to top: flexible transparent film substrate 1, first electromagnetic shielding functional layer 2, first organic dielectric layer 3, second electromagnetic shielding functional layer 4, second organic dielectric layer 5, and third electromagnetic shielding functional layer 6.

[0039] The material of the flexible transparent film substrate is polyethylene terephthalate; the materials of the first electromagnetic shielding functional layer, the second electromagnetic shielding functional layer and the third electromagnetic shielding functional layer are all hexaiminotriphenylene nickel; and the materials of the first organic medium layer and the second organic medium layer are both polydimethylsiloxane.

[0040] The electromagnetic shielding functional layer mainly relies on the good absorption of hexaiminotriphenylene nickel to electromagnetic shielding. Hexaiminotriphenylene nickel is derived from the translation of Ni3(hexaiminotriphenylene)2, which is abbreviated as Ni3(HITP)2. Hexaiminotriphenylene nickel is a porous two-dimensional material. Electromagnetic waves form multiple reflections and interferences in the interior of the porous two-dimensional material, thereby generating absorption of electromagnetic waves. By adopting three layers of two-dimensional hexaiminotriphenylene nickel, strong resonance interference of electromagnetic waves can be formed between the three layers of two-dimensional hexaiminotriphenylene nickel, further enhancing the absorption performance of the electromagnetic shielding structure to electromagnetic waves, thereby improving the overall electromagnetic wave absorption performance of the electromagnetic shielding film and exhibiting excellent electromagnetic shielding efficiency and ductility. In order to further improve the ductility of the electromagnetic shielding film, polydimethylsiloxane (PDMS) with excellent ductility is used as a medium layer between the conductive layers.

[0041] The thickness of the flexible transparent film substrate is 50 μm.

[0042] The thickness ratio of the first electromagnetic shielding functional layer to the second electromagnetic shielding functional layer is 1:0.8, that is, the thickness of the first electromagnetic shielding functional layer is 1.25 μm, and the thickness of the second electromagnetic shielding functional layer is 1 μm; the thickness of the third electromagnetic shielding functional layer is 1 μm.

[0043] The thickness ratio of the first organic medium layer to the second organic medium layer is 1:0.8, that is, the thickness of the first organic medium layer is 1.25 mm, and the thickness of the second organic medium layer is 1 mm.

[0044] The embodiment also provides a preparation method of the composite flexible transparent electromagnetic shielding film, which is applied to the composite flexible transparent electromagnetic shielding film and includes the following steps in sequence:

[0045] Step one: the flexible transparent film substrate is pretreated by oxygen ions, hexaiminotriphenylene nickel sol is scraped on the upper surface of the flexible transparent film substrate by using a scraper, and then the first electromagnetic shielding functional layer is formed by baking in an oven;

[0046] Step two: after solidification is completed, polydimethylsiloxane is scraped on the upper surface of the first electromagnetic shielding functional layer by using a scraper, and then the first organic medium layer is formed by baking in an oven;

[0047] Step three: after the solidification is completed, the hexamino triphenyl nickel sol is scraped on the upper surface of the first organic medium layer using a scraper, and then is placed in an oven for baking to form a second electromagnetic shielding functional layer;

[0048] Step four: after the solidification is completed, the polydimethylsiloxane is scraped on the upper surface of the second electromagnetic shielding functional layer using a scraper, and then is placed in an oven for baking to form a second organic medium layer;

[0049] Step five: after the solidification is completed, the hexamino triphenyl nickel sol is scraped on the upper surface of the second organic medium layer using a scraper, and then is placed in an oven for baking to form a third electromagnetic shielding functional layer, and at this time, the composite flexible transparent electromagnetic shielding film can be prepared.

[0050] In steps one, three and five, the baking temperature is 90℃, and the baking time is 2.5h.

[0051] In steps two and four, the baking temperature is 80℃, and the baking time is 2h.

[0052] In the preparation process of the composite flexible transparent electromagnetic shielding film, multiple baking is required, and each time the film to be baked is placed in an oven, then the oven is heated, and after the baking is completed, the oven is cooled.

[0053] The synthesis method of the hexamino triphenyl nickel sol comprises the following steps in order:

[0054] Step A: a nickel chloride solution is prepared by taking dimethylformamide as a solvent and nickel chloride hexahydrate as a solute;

[0055] Step B: a hexamino triphenyl hexa hydrochloride solution is prepared by taking dimethylformamide as a solvent and hexamino triphenyl hexa hydrochloride as a solute;

[0056] Step C: the nickel chloride solution and the hexamino triphenyl hexa hydrochloride solution are injected into a sealed stirrer for stirring and mixing;

[0057] Step D: after the mixing is completed, the mixed solution is injected into a beaker, and then is placed in an oven for baking to volatilize the solvent, and thus the hexamino triphenyl nickel sol can be prepared.

[0058] In step A, the solvent used is dimethylformamide analytical pure, the solute used is nickel chloride hexahydrate analytical pure, and the concentration of the prepared nickel chloride solution is 30mmol / L.

[0059] In step B, the solvent used is dimethylformamide analytical pure, and the concentration of the prepared hexamino triphenyl hexa hydrochloride solution is 18mmol / L.

[0060] In step C, the stirring speed is 500r / min, and the stirring time is 3h.

[0061] In Step D, the baking temperature is 90℃, and the baking time is 1.5h.

[0062] The composite flexible transparent electromagnetic shielding film and the preparation method thereof have simple structure, convenient operation, and the prepared electromagnetic shielding film has high electromagnetic shielding efficiency, good ductility, and excellent wave absorption performance, and is suitable for electromagnetic shielding of wearable devices.

[0063] The electromagnetic shielding film prepared in the embodiment has an electromagnetic shielding efficiency of 62dB at 8-20GHz, an electromagnetic wave absorption efficiency of 54dB, a visible light (380-780nm) transmittance of 74%, and an elongation of the electromagnetic shielding film of 5.3%.

[0064] Example Two:

[0065] According to another preferred embodiment of the composite flexible transparent electromagnetic shielding film, the film structure, the materials used in each layer, the preparation method, the design principle, and the beneficial effects are basically the same as those of Example One, except that:

[0066] The thickness of the flexible transparent film substrate is 125μm.

[0067] The thickness ratio of the first electromagnetic shielding functional layer to the second electromagnetic shielding functional layer is 1:1, that is, the thickness of the first electromagnetic shielding functional layer is 1.2μm, and the thickness of the second electromagnetic shielding functional layer is 1.2μm; the thickness of the third electromagnetic shielding functional layer is 1.2μm.

[0068] The thickness ratio of the first organic medium layer to the second organic medium layer is 1:1, that is, the thickness of the first organic medium layer is 1.5mm, and the thickness of the second organic medium layer is 1.5mm.

[0069] In the embodiment, the preparation method of the composite flexible transparent electromagnetic shielding film includes the following main parameters:

[0070] In Step One, Step Three, and Step Five, the baking temperature is 110℃, and the baking time is 2h.

[0071] In Step Two and Step Four, the baking temperature is 100℃, and the baking time is 1h.

[0072] In the embodiment, the synthesis method of the hexaazatriphenyl nickel sol includes the following main parameters:

[0073] In Step A, the solvent used is dimethylformamide of analytical purity, and the solute used is nickel chloride hexahydrate of analytical purity, and the concentration of the prepared nickel chloride solution is 35mmol / L.

[0074] In Step B, the solvent used is dimethylformamide analytical pure, and the concentration of the prepared hexamino triphenyl hexachloride solution is 21 mmol / L.

[0075] In Step C, the stirring speed is 600 r / min, and the stirring time is 2 h.

[0076] In Step D, the baking temperature is 100 ℃, and the baking time is 1 h.

[0077] The electromagnetic shielding film prepared in this embodiment has an electromagnetic shielding effectiveness of 68 dB, an electromagnetic wave absorption effectiveness of 57 dB, a visible light (380-780 nm) transmittance of 70%, and an elongation of 5.5%.

[0078] Example Three

[0079] According to another preferred embodiment of the composite flexible transparent electromagnetic shielding film, the film structure, the materials used in each layer, the preparation method, the design principle, the beneficial effects and the like are basically the same as those of Example One, except that:

[0080] The thickness of the flexible transparent film substrate is 90 μm.

[0081] The thickness ratio of the first electromagnetic shielding functional layer to the second electromagnetic shielding functional layer is 1:1.2, that is, the thickness of the first electromagnetic shielding functional layer is 1.25 μm, and the thickness of the second electromagnetic shielding functional layer is 1.5 μm; the thickness of the third electromagnetic shielding functional layer is 1.5 μm.

[0082] The thickness ratio of the first organic medium layer to the second organic medium layer is 1:1.2, that is, the thickness of the first organic medium layer is 1 mm, and the thickness of the second organic medium layer is 1.2 mm.

[0083] In this embodiment, the preparation method of the composite flexible transparent electromagnetic shielding film includes the following main parameters:

[0084] In Step One, Step Three and Step Five, the baking temperature is 100 ℃, and the baking time is 2.2 h.

[0085] In Step Two and Step Four, the baking temperature is 90 ℃, and the baking time is 1.5 h.

[0086] In this embodiment, the synthesis method of the hexaamino triphenyl nickel sol includes the following main parameters:

[0087] In Step A, the solvent used is dimethylformamide analytical pure, and the solute used is nickel chloride hexahydrate analytical pure. The concentration of the prepared nickel chloride solution is 32 mmol / L.

[0088] In step B, the solvent used is dimethylformamide of analytical purity, and the concentration of the prepared hexamine triphenyl hexachloride hydrochloride solution is 20 mmol / L.

[0089] In step C, the stirring speed is 550 r / min, and the stirring time is 2.5 h.

[0090] In step D, the baking temperature is 95℃, and the baking time is 1.2 h.

[0091] The electromagnetic shielding film prepared in the example has an electromagnetic shielding effectiveness of 73 dB at 8-20 GHz, an electromagnetic wave absorption effectiveness of 61 dB, a visible light (380-780 nm) transmittance of 65%, and an elongation of the electromagnetic shielding film of 6.0%.

[0092] Special note: The technical solution of the present application involves many parameters, and the synergistic effect between each parameter needs to be considered in order to obtain the beneficial effects and significant progress of the present application. Moreover, the value range of each parameter in the technical solution is obtained through a large number of experiments. For each parameter and the mutual combination of each parameter, the inventors have recorded a large amount of experimental data. Due to the limited space, the specific experimental data is not disclosed here.

[0093] It is not difficult for those skilled in the art to understand that the composite flexible transparent electromagnetic shielding film and the preparation method thereof of the present application include any combination of the parts shown in the summary of the application and the specific embodiment part of the present application and the drawings. Due to the limited space and in order to make the specification concise, each scheme formed by these combinations is not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A composite flexible transparent electromagnetic shielding film, comprising a flexible transparent thin film substrate, an electromagnetic shielding functional layer, and an organic dielectric layer, characterized in that: The electromagnetic shielding functional layer includes a first electromagnetic shielding functional layer, a second electromagnetic shielding functional layer, and a third electromagnetic shielding functional layer; the organic dielectric layer includes a first organic dielectric layer and a second organic dielectric layer; the flexible transparent film substrate, the electromagnetic shielding functional layer, and the organic dielectric layer are arranged in the following order from bottom to top: the flexible transparent film substrate, the first electromagnetic shielding functional layer, the first organic dielectric layer, the second electromagnetic shielding functional layer, the second organic dielectric layer, and the third electromagnetic shielding functional layer; The first electromagnetic shielding functional layer, the second electromagnetic shielding functional layer, and the third electromagnetic shielding functional layer are all made of hexamethylenetriphenyl nickel; the synthesis method of hexamethylenetriphenyl nickel sol includes the following steps in sequence: Step A: Prepare a nickel chloride solution using dimethylformamide as solvent and nickel chloride hexahydrate as solute; Step B: Prepare a solution of hexaaminotriphenylhexahydrochloride using dimethylformamide as solvent and hexaaminotriphenylhexahydrochloride as solute; Step C: Pour the nickel chloride solution and hexaaminotriphenylhexahydrochloride solution into a sealed stirrer and mix them. Step D: After the mixture is evenly mixed, pour the mixture into a beaker and then put it in an oven to bake, so that the solvent evaporates, and the hexamethylenetriphenyl nickel sol can be obtained. In step A, the solvent used is dimethylformamide (analytical grade), and the solute is nickel chloride hexahydrate (analytical grade). The concentration of the prepared nickel chloride solution is 30-35 mmol / L. In step B, the solvent used is dimethylformamide (analytical grade), and the concentration of the prepared hexaaminotriphenylhexahydrochloride solution is 18-21 mmol / L. In step C, the stirring speed is 500-600 r / min, and the stirring time is 2-3 h. In step D, the baking temperature is 90-100℃, and the baking time is 1-1.5 h. The thicknesses of the first electromagnetic shielding functional layer, the second electromagnetic shielding functional layer, and the third electromagnetic shielding functional layer are controlled within the range of 1-1.5 μm, and the thickness ratio of the first electromagnetic shielding functional layer to the second electromagnetic shielding functional layer is 1:0.8-1.

2. Both the first organic dielectric layer and the second organic dielectric layer are made of polydimethylsiloxane; the thickness of the first organic dielectric layer and the second organic dielectric layer is controlled within the range of 1-1.5 mm, and the thickness ratio of the first organic dielectric layer to the second organic dielectric layer is 1:0.8-1.2; The method for preparing the composite flexible transparent electromagnetic shielding film includes the following steps in sequence: Step 1: Pre-treat the flexible transparent film substrate with oxygen ions, apply hexamethylenetriphenyl nickel sol to the upper surface of the flexible transparent film substrate with a scraper, and then bake it in an oven to form the first electromagnetic shielding functional layer. Step 2: After curing, use a scraper to coat polydimethylsiloxane on the upper surface of the first electromagnetic shielding functional layer, and then place it in an oven for baking to form the first organic dielectric layer; Step 3: After curing, use a scraper to apply hexamethylenetriphenyl nickel sol to the upper surface of the first organic dielectric layer, and then place it in an oven to bake, forming the second electromagnetic shielding functional layer; Step 4: After curing, use a scraper to coat the upper surface of the second electromagnetic shielding functional layer with polydimethylsiloxane, and then place it in an oven to bake, forming the second organic dielectric layer. Step 5: After curing, use a scraper to coat the upper surface of the second organic dielectric layer with hexamethylene triphenyl nickel sol, and then put it in an oven to bake to form the third electromagnetic shielding functional layer, thus obtaining the composite flexible transparent electromagnetic shielding film. In steps one, three, and five, the baking temperature is 90-110℃ and the baking time is 2-2.5h. In steps two and four, the baking temperature is 80-100℃ and the baking time is 1-2h. In the preparation process of the composite flexible transparent electromagnetic shielding film, multiple baking processes are required. Each baking process involves placing the film to be baked into an oven, heating it up with the oven, and then cooling it with the oven after baking.

2. The composite flexible transparent electromagnetic shielding film according to claim 1, characterized in that: The flexible transparent film substrate is made of polyethylene terephthalate.

3. The composite flexible transparent electromagnetic shielding film according to claim 2, characterized in that: The thickness of the flexible transparent film substrate is 50-125 μm.

Images