Electromagnetic metamaterial flexible film and preparation method thereof

Abstract

The invention discloses an electromagnetic metamaterial flexible film and a preparation method thereof. The electromagnetic metamaterial flexible film comprises an upper-layer film, a middle-layer film and a lower-layer film which are sequentially laminated, an upper-layer ITO wafer array and a lower-layer ITO wafer array are arranged on the opposite inner sides of the upper-layer film and the lower-layer film respectively, and a middle-layer ITO wafer array is arranged on one side of the middle-layer film; wherein the upper-layer film is an electromagnetic metamaterial film with low magnetic particle content; the middle layer film is a PET (Polyethylene Terephthalate) film; and the lower layer film is an electromagnetic metamaterial film with high magnetic particle content. The electromagnetic metamaterial flexible film has the advantages of being good in wave absorbing performance, good in flexibility and ductility and high in material utilization rate. In addition, the method is simple in process, low in cost and easy to implement industrially.

Description

Technical Field

[0001] The invention relates to an electromagnetic wave absorbing material, in particular to an electromagnetic metamaterial flexible film and a preparation method thereof. Background Art

[0002] Flexible materials refer to those materials that have excellent ductility and can be bent, folded, and twisted without damage. In recent years, with the increasing demand for miniaturization and lightweight electronic devices, flexible materials are increasingly used in electronic products, sensors, batteries, circuits, and other fields. Therefore, the research and development of high-performance flexible materials has become one of the important directions in the current field of materials science.

[0003] Electromagnetic metamaterials are artificial composite materials with special electromagnetic properties. Through specific structural design, they can achieve precise control and manipulation of electromagnetic waves. The characteristics of electromagnetic metamaterials mainly include negative refractive index, invisibility cloak, perfect absorption, etc. These characteristics make electromagnetic metamaterials have broad application prospects in radar absorption, communication equipment, electromagnetic protection and other fields.

[0004] Although electromagnetic metamaterials have been extensively studied and applied to a certain extent in the fields of wave absorption, their current applications are still in the exploratory stage, and the best application method has not been found. For example, the patent with the publication number CN111641044A discloses a flexible electromagnetic metamaterial and a preparation method thereof, wherein the flexible electromagnetic metamaterial comprises a flexible matrix composed of a magnetic composite material and a plurality of periodically arranged metamaterial periodic units embedded therein; the magnetic composite material is a composite material of a magnetic material and an adhesive; the geometric thickness of the flexible electromagnetic metamaterial is t1, and the value range of t1 is 0.5 to 2 mm; the metamaterial periodic unit is a circular sheet or a square sheet, and the diameter of the circular sheet or the side length of the square sheet is less than or equal to 5 cm; the metamaterial periodic unit is composed of a flexible conductive material. It can be seen that the patent discloses a flexible electromagnetic metamaterial with a metamaterial as a periodic unit and a flexible matrix as a carrier.

[0005] In addition, the current methods for preparing electromagnetic metamaterials mainly include photolithography, chemical vapor deposition and electron beam evaporation. However, these methods have some limitations, such as expensive equipment, long preparation time, low material utilization rate, etc. In addition, the electromagnetic metamaterials prepared by these methods often lack flexibility and ductility, which limits their application in flexible electronic devices and other fields.

[0006] Further research on the materials, structures and processes of electromagnetic metamaterial flexible membranes to enable them to have higher wave absorption performance, better flexibility and ductility, higher material utilization, simpler preparation processes and lower preparation costs is still a hot topic in this research direction. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides an electromagnetic metamaterial flexible film and a preparation method thereof. The electromagnetic metamaterial flexible film of the present invention has the characteristics of good wave absorption performance, good flexibility and ductility, and high material utilization rate; in addition, the process of the present invention is simple, low in cost, and easy to implement industrially.

[0008] One of the technical solutions of the present invention:

[0009] Provided is an electromagnetic metamaterial flexible film, comprising an upper film, a middle film and a lower film laminated in sequence; an upper ITO disc array and a lower ITO disc array are respectively arranged on the inner sides of the upper film and the lower film relative to each other, and a middle ITO disc array is arranged on one side of the middle film;

[0010] in:

[0011] The upper film is an electromagnetic metamaterial film with a low magnetic particle content;

[0012] The middle layer film is a PET film;

[0013] The lower film is an electromagnetic metamaterial film with a high content of magnetic particles.

[0014] Preferably, in the aforementioned electromagnetic metamaterial flexible film, the thickness of the upper film, the middle film, the lower film, the upper ITO disc array, the lower ITO disc array and the middle ITO disc array is 0.01-0.03mm; the diameter of the discs in the upper ITO disc array, the lower ITO disc array and the middle ITO disc array is 3-4mm, and the spacing between adjacent discs is 0.2-0.5mm.

[0015] Preferably, in the aforementioned electromagnetic metamaterial flexible film, the upper ITO disc array and the lower ITO disc array are rectangular arrays corresponding one to the other.

[0016] Preferably, in the aforementioned electromagnetic metamaterial flexible film, the middle layer ITO disc array is a staggered array composed of small groups arranged in a rhombus as repeating units, wherein the long diagonal of the rhombus: the short diagonal = 2:1, the spacing between the discs in the same rhombus is 0.2-0.5mm, and the vertical spacing between adjacent rhombuses is 0.2-0.5mm.

[0017] Preferably, in the aforementioned electromagnetic metamaterial flexible film, the magnetic particles are one of ferrite particles, carbonyl iron powder or rare earth permanent magnetic materials.

[0018] Preferably, in the aforementioned electromagnetic metamaterial flexible film, the content of magnetic particles in the upper film is 20-40wt%.

[0019] Preferably, in the aforementioned electromagnetic metamaterial flexible film, the content of magnetic particles in the lower film is 40-60wt%.

[0020] One of the technical solutions of the present invention:

[0021] A method for preparing an electromagnetic metamaterial flexible film is provided, comprising the following steps:

[0022] S1. The polymer solution and the magnetic particles are mixed uniformly in proportion to obtain a mixed solution;

[0023] S2. The mixed solution is sequentially coated and heat treated to form an upper film having a low magnetic particle content and a lower film having a high magnetic particle content;

[0024] S3. Take the middle film of PET material, and make an upper ITO wafer array, a middle ITO wafer array and a lower ITO wafer array on the surface of the upper film, the middle film and the lower film respectively;

[0025] S4. Coat the surfaces of the upper film, middle film and lower film of the ITO array prepared in S3 with an adhesive, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

[0026] Preferably, in the aforementioned method for preparing the electromagnetic metamaterial flexible film, the high molecular polymer is one of polyaniline or polypyrrole; and the adhesive is one of polyurethane flexible glue, silicone flexible glue, acrylate flexible glue or hot melt flexible glue.

[0027] Preferably, in the aforementioned method for preparing the electromagnetic metamaterial flexible film, the temperature of the heat treatment in S2 is 100-200° C., and the treatment time is 10-60 min.

[0028] Beneficial effects of the present invention:

[0029] 1. The electromagnetic metamaterial flexible film of the present invention is composed of three layers of films, namely, an upper, middle and lower layer, wherein the upper layer and the lower layer are an electromagnetic metamaterial film with a low magnetic particle content and an electromagnetic metamaterial film with a high magnetic particle content, respectively. At the same time, ITO wafer arrays are respectively arranged on the three layers of films, so that the electromagnetic metamaterial flexible film of the present invention has higher wave absorbing performance.

[0030] 2. The upper and lower films of the electromagnetic metamaterial flexible film of the present invention are prepared by mixing polymer materials and magnetic particles, and have the advantages of good flexibility, high ductility and high material utilization rate. At the same time, the preparation process of the electromagnetic metamaterial flexible film of the present invention is simple, low-cost, and easy to implement industrially.

[0031] 3. The ITO disc arrays in the electromagnetic metamaterial flexible film of the present invention respectively adopt a rectangular array and a staggered array composed of small groups arranged in a diamond shape as repeating units. This arrangement has better wave absorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Attached Figure 1 It is a schematic diagram of the structure of the electromagnetic metamaterial flexible film of the present invention;

[0033] Attached Figure 2 A plan view of a middle layer film of the electromagnetic metamaterial flexible film of the present invention;

[0034] Attached Figure 3 The radar wave reflectivity comparison diagram of the electromagnetic metamaterial flexible film of the present invention before and after the ITO disc is set. The upper line is the electromagnetic metamaterial flexible film without the ITO disc, and the lower line is the electromagnetic metamaterial flexible film prepared in Example 3 of the present invention. It can be seen that the present invention has a better radar wave reflectivity by adding a metamaterial harmonic array characteristic formed by the arrangement and combination of special ITO films.

[0035] Attached Figure 4 This is a comparison chart of radar wave reflectivity of the electromagnetic metamaterial flexible film of Example 2 of the present invention and a commercially available electromagnetic absorbing film; the upper curve is the commercially available electromagnetic absorbing film, and the lower curve is the film of the present invention.

[0036] Attached Figure 5 This is a comparison chart of radar wave reflectivity of the electromagnetic metamaterial flexible film of Example 3 of the present invention and a commercially available electromagnetic absorbing film; the upper curve is the commercially available electromagnetic absorbing film, and the lower curve is the film of the present invention.

[0037] Attached Figure 6 This is a comparison chart of radar wave reflectivity of the electromagnetic metamaterial flexible film of Example 4 of the present invention and a commercially available electromagnetic absorbing film; the upper curve is the commercially available electromagnetic absorbing film, and the lower curve is the film of the present invention.

[0038] Attached Figure 7 This is a comparison chart of radar wave reflectivity of the electromagnetic metamaterial flexible film of Example 5 of the present invention and a commercially available electromagnetic absorbing film; the upper curve is the commercially available electromagnetic absorbing film, and the lower curve is the film of the present invention.

[0039] Attached Figure 8 This is a comparison chart of radar wave reflectivity of the electromagnetic metamaterial flexible film of Example 6 of the present invention and a commercially available electromagnetic absorbing film; the upper curve is the commercially available electromagnetic absorbing film, and the lower curve is the film of the present invention.

[0040] Explanation of the reference numerals: 1 - upper film, 2 - middle film, 3 - lower film, 4 - upper ITO disc array, 5 - lower ITO disc array, 6 - middle ITO disc array. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0042] Embodiments of the present invention

[0043] Example 1

[0044] An electromagnetic metamaterial flexible film, such as the attached Figure 1-2 As shown, it comprises an upper film 1, a middle film 2 and a lower film 3 which are laminated in sequence; an upper ITO disc array 4 and a lower ITO disc array 5 are respectively arranged on the inner sides of the upper film 1 and the lower film 3, and a middle ITO disc array 6 is arranged on one side of the middle film 2;

[0045] in:

[0046] The upper film 1 is an electromagnetic metamaterial film with a low magnetic particle content;

[0047] The middle layer film 2 is a PET film;

[0048] The lower film 3 is an electromagnetic metamaterial film with a high content of magnetic particles.

[0049] Further implementation examples include Figure 1-2 As shown, the thickness of the upper film 1, the middle film 2, the lower film 3, the upper ITO disc array 4, the lower ITO disc array 5 and the middle ITO disc array 6 is 0.01-0.03mm, and 0.02mm in this embodiment; the diameter of the discs in the upper ITO disc array 4, the lower ITO disc array 5 and the middle ITO disc array 6 is 3-4mm, and 3.2mm in this embodiment, and the spacing between adjacent discs is 0.2-0.5mm, and 0.4mm in this embodiment.

[0050] Further implementation examples include Figure 1-2 As shown, the upper ITO disc array 4 and the lower ITO disc array 5 are rectangular arrays corresponding to each other.

[0051] Further implementation examples include Figure 1-2 As shown, the middle layer ITO disc array 6 is a staggered array composed of small groups arranged in a rhombus as repeating units, wherein the long diagonal of the rhombus: the short diagonal = 2:1, the spacing between the discs in the same rhombus is 0.2-0.5mm, and is 0.3mm in this embodiment, and the vertical spacing between adjacent rhombuses is 0.2-0.5mm, and is 0.3mm in this embodiment.

[0052] Further implementation examples include Figure 1-2 As shown, the magnetic particles are one of ferrite particles, carbonyl iron powder or rare earth permanent magnet materials.

[0053] Further implementation examples include Figure 1-2 As shown, the content of magnetic particles in the upper film 1 is 20-40wt%. The content of magnetic particles can be adjusted according to the use requirements during specific production.

[0054] Further implementation examples include Figure 1-2 As shown, the content of magnetic particles in the lower film 3 is 40-60wt%. The content of magnetic particles can be adjusted according to the use requirements during specific production.

[0055] Example 2

[0056] A method for preparing an electromagnetic metamaterial flexible film, comprising the following steps:

[0057] S1. The polyaniline solution and the ferrite particles were mixed evenly in a mass ratio of 70:30 and 50:50 to obtain two mixed solutions;

[0058] S2. The two mixed solutions were first coated and then heat treated at 100°C for 60 min to form an upper film 1 having a magnetic particle content of 30 wt% and a lower film 3 having a magnetic particle content of 50 wt%;

[0059] S3. Take the middle film 2 of PET material, and make the upper ITO wafer array 4, the middle ITO wafer array 6 and the lower ITO wafer array 5 on the surface of the upper film 1, the middle film 2 and the lower film 3 respectively;

[0060] S4. Coat the surfaces of the upper film 1, the middle film 2 and the lower film 3 of the ITO array prepared in S3 with polyurethane flexible glue, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

[0061] Example 3

[0062] A method for preparing an electromagnetic metamaterial flexible film, comprising the following steps:

[0063] S1. The polyaniline solution and the carbonyl iron powder were mixed uniformly in a mass ratio of 60:40 and 40:60 respectively to obtain two mixed solutions;

[0064] S2. The two mixed solutions were first coated and then heat treated at 150°C for 35 min to form an upper film 1 having a magnetic particle content of 40 wt% and a lower film 3 having a magnetic particle content of 60 wt%;

[0065] S3. Take the middle film 2 of PET material, and make the upper ITO wafer array 4, the middle ITO wafer array 6 and the lower ITO wafer array 5 on the surface of the upper film 1, the middle film 2 and the lower film 3 respectively;

[0066] S4. Coat the surfaces of the upper film 1, the middle film 2 and the lower film 3 of the ITO array prepared in S3 with silicone flexible glue, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

[0067] Example 4

[0068] A method for preparing an electromagnetic metamaterial flexible film, comprising the following steps:

[0069] S1. The polyaniline solution and the rare earth permanent magnet material are mixed evenly according to the mass ratio of polyaniline to the rare earth permanent magnet material of 65:35 and 45:55 to obtain two mixed solutions;

[0070] S2. The two mixed solutions were first coated and then heat treated at 120°C for 45 min to form an upper film 1 having a magnetic particle content of 35 wt% and a lower film 3 having a magnetic particle content of 55 wt%;

[0071] S3. Take the middle film 2 of PET material, and make the upper ITO wafer array 4, the middle ITO wafer array 6 and the lower ITO wafer array 5 on the surface of the upper film 1, the middle film 2 and the lower film 3 respectively;

[0072] S4. Coat the surfaces of the upper film 1, the middle film 2 and the lower film 3 of the ITO array prepared in S3 with acrylic flexible glue, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

[0073] Example 5

[0074] A method for preparing an electromagnetic metamaterial flexible film, comprising the following steps:

[0075] S1. The polypyrrole solution and the carbonyl iron powder were mixed uniformly in a mass ratio of 75:25 and 55:45 to obtain two mixed solutions;

[0076] S2. The two mixed solutions were first coated and then heat treated at 180°C for 20 min to form an upper film 1 having a magnetic particle content of 25 wt% and a lower film 3 having a magnetic particle content of 45 wt%;

[0077] S3. Take the middle film 2 of PET material, and make the upper ITO wafer array 4, the middle ITO wafer array 6 and the lower ITO wafer array 5 on the surface of the upper film 1, the middle film 2 and the lower film 3 respectively;

[0078] S4. Coat the surfaces of the upper film 1, the middle film 2 and the lower film 3 of the ITO array prepared in S3 with hot-melt flexible glue, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

[0079] Example 6

[0080] A method for preparing an electromagnetic metamaterial flexible film, comprising the following steps:

[0081] S1. The polypyrrole solution and the ferrite particles were mixed evenly at a mass ratio of 80:20 and 60:40 to obtain two mixed solutions;

[0082] S2. The two mixed solutions were first coated and then heat treated at 200°C for 10 min to form an upper film 1 having a magnetic particle content of 20wt% and a lower film 3 having a magnetic particle content of 40wt%;

[0083] S3. Take the middle film 2 of PET material, and make the upper ITO wafer array 4, the middle ITO wafer array 6 and the lower ITO wafer array 5 on the surface of the upper film 1, the middle film 2 and the lower film 3 respectively;

[0084] S4. Coat the surfaces of the upper film 1, the middle film 2 and the lower film 3 of the ITO array prepared in S3 with polyurethane flexible glue, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

[0085] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An electromagnetic metamaterial flexible film, characterized in that: It comprises an upper film (1), a middle film (2) and a lower film (3) which are laminated in sequence; an upper ITO disc array (4) and a lower ITO disc array (5) are respectively arranged on the inner sides of the upper film (1) and the lower film (3) facing each other, and a middle ITO disc array (6) is arranged on one side of the middle film (2); in: The upper film (1) is an electromagnetic metamaterial film with a low magnetic particle content; The middle layer film (2) is a PET film; The lower film (3) is an electromagnetic metamaterial film with a high magnetic particle content.

2. The electromagnetic metamaterial flexible film according to claim 1, characterized in that: The thickness of the upper film (1), the middle film (2), the lower film (3), the upper ITO disc array (4), the lower ITO disc array (5) and the middle ITO disc array (6) is 0.01-0.03 mm; the diameter of the discs in the upper ITO disc array (4), the lower ITO disc array (5) and the middle ITO disc array (6) is 3-4 mm, and the spacing between adjacent discs is 0.2-0.5 mm.

3. The electromagnetic metamaterial flexible film according to claim 1, characterized in that: The upper ITO disc array (4) and the lower ITO disc array (5) are rectangular arrays that correspond one to another.

4. The electromagnetic metamaterial flexible film according to claim 1, characterized in that: The middle layer ITO disc array (6) is a staggered array composed of small groups arranged in a rhombus as repeating units, wherein the ratio of the long diagonal line to the short diagonal line of the rhombus is 2:1, the spacing between discs in the same rhombus is 0.2-0.5 mm, and the vertical spacing between adjacent rhombuses is 0.2-0.5 mm.

5. The electromagnetic metamaterial flexible film according to claim 1, characterized in that: The magnetic particles are one of ferrite particles, carbonyl iron powder or rare earth permanent magnetic materials.

6. The electromagnetic metamaterial flexible film according to claim 1, characterized in that: The content of magnetic particles in the upper film (1) is 20-40 wt%.

7. The electromagnetic metamaterial flexible film according to claim 1, characterized in that: The content of magnetic particles in the lower film (3) is 40-60 wt%.

8. A method for preparing an electromagnetic metamaterial flexible film according to any one of claims 1 to 7, characterized in that: The steps include: S1. The polymer solution and the magnetic particles are mixed uniformly in proportion to obtain a mixed solution; S2. The mixed solution is sequentially coated and heat-treated to form an upper film (1) with a low magnetic particle content and a lower film (3) with a high magnetic particle content; S3. Take the middle film (2) of PET material, and make an upper ITO wafer array (4), a middle ITO wafer array (6) and a lower ITO wafer array (5) on the surface of the upper film (1), the middle film (2) and the lower film (3); S4. Coat the surfaces of the upper film (1), the middle film (2) and the lower film (3) of the ITO array prepared in S3 with an adhesive, and then stack them in sequence to obtain an electromagnetic metamaterial flexible film.

9. The method for preparing the electromagnetic metamaterial flexible film according to claim 8, characterized in that: The high molecular polymer is one of polyaniline and polypyrrole; the adhesive is one of polyurethane flexible glue, silicone flexible glue, acrylate flexible glue or hot melt flexible glue.

10. The method for preparing the electromagnetic metamaterial flexible film according to claim 8, characterized in that: The heat treatment temperature in S2 is 100-200° C., and the treatment time is 10-60 min.

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