A patterned wave-absorbing film material and preparation method thereof

Abstract

The present invention relates to a patterned absorbing film material and a method for preparing the same. The surface of the absorbing film material is provided with a plurality of protrusions arranged horizontally and vertically. The spacing between any two adjacent protrusions in a horizontal row is equal, and the spacing between any two adjacent protrusions in a vertical column is equal. The absorbing film material is prepared by placing a raw film material on the platform of a laser marking machine, adjusting the laser beam so that the beam intersects the raw film material horizontally and vertically to form a grid pattern, and then laser ablating the raw film material to obtain the desired product. Compared with existing technologies, the patterned absorbing film material of the present invention exhibits superior microwave shielding effectiveness. Furthermore, it avoids the use of a multi-layer composite structure, which does not increase the thickness and weight of the film material. The absorbing film material of the present invention is lightweight and thin.

Description

Technical Field

[0001] The present invention belongs to the technical field of wave-absorbing materials, and relates to a patterned wave-absorbing thin film material and a preparation method thereof. Background Art

[0002] Research on absorbing materials has been a hot topic in recent years, with widespread applications in areas such as military equipment stealth and civilian electromagnetic protection. With the advancement of modern communications technology and the widespread adoption of electronic products, the widespread presence of electromagnetic waves has also led to a series of environmental problems. Electromagnetic pollution has been identified as the fourth largest environmental pollution source, after water pollution, air pollution, and noise pollution. Absorbing materials that can absorb electromagnetic waves within specific frequency bands are crucial for effectively addressing this problem. Therefore, research on absorbing materials is of great significance in the civilian sector. In the military, absorbing materials that can efficiently absorb electromagnetic waves within specific frequency bands have long been indispensable for achieving weapon stealth.

[0003] While significant progress has been made in the preparation of microwave-absorbing materials in recent years, the development of lightweight, thin, chemically stable, broad-frequency-absorbing, and high-performance microwave-absorbing materials remains a key challenge. To date, the most common method for patterning thin-film materials is to layer a patterned absorbing material with other layers to form an absorbing layer. This technique significantly improves the material's absorption capacity, but also significantly increases the film's thickness and weight. Summary of the Invention

[0004] The purpose of the present invention is to provide a patterned absorbing film material and a preparation method thereof, so as to overcome the defects of the prior art patterned absorbing materials such as multi-layer structure, large thickness and weight or poor microwave absorption performance.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present invention provides a patterned absorbing film material, the surface of which is provided with a plurality of protrusions arranged horizontally and vertically, the intervals between any two adjacent protrusions in a horizontal row are equal, and the intervals between any two adjacent protrusions in a vertical column are equal.

[0007] Furthermore, the interval between any two adjacent protrusions in a horizontal row is equal to the interval between any two adjacent protrusions in a vertical column.

[0008] Furthermore, the protrusions have the same height.

[0009] Furthermore, the protrusions are arranged on the same surface of the absorbing film material.

[0010] Furthermore, the protrusion has a length of 200 μm and a width of 200 μm.

[0011] A second technical solution of the present invention provides a method for preparing the above-mentioned patterned absorbing film material, the method comprising:

[0012] Place the film raw material on the laser marking machine platform, adjust the laser line so that the laser line crosses the surface of the film raw material horizontally and vertically to obtain a grid pattern, and then perform laser ablation on the film raw material to obtain the target product.

[0013] Furthermore, the film raw material is a MXene film or a MXene film doped with silver nanowires.

[0014] Furthermore, the height of the protrusions obtained after laser ablation is less than half the thickness of the thin film raw material. The pattern etching method of the present invention is a cross-grid etching method. If the single laser etching depth exceeds (or is equal to) half the thickness of the thin film raw material, the laser will penetrate the thin film raw material at the cross-grid points.

[0015] Furthermore, the height of the protrusions obtained after laser ablation is 30% of the thickness of the film raw material.

[0016] Furthermore, the height of the protrusions obtained after laser ablation is 45% of the thickness of the film raw material.

[0017] Furthermore, the power of each laser line is equal.

[0018] During the preparation of the patterned absorbing film material of the present invention, the spacing between the laser lines should be much smaller than the wavelength size of the corresponding band (for example, the corresponding wavelength of the X-band is 2.5cm to 3.75cm, and the spacing between the laser lines can be around 300μm). The reason is that if the spacing between the laser lines (i.e., the side length of the protrusions) is comparable to the wavelength size of the corresponding band, it will become a metamaterial with a characteristic frequency response, which is different from the principle of the material of the present invention.

[0019] The present invention carves grid-like traces with the same horizontal and vertical intervals on one side of a thin film material through laser ablation. Adjacent traces surround the material not ablated by the laser to form bulges. The laser ablation traces have the same depth and the bulges have the same height.

[0020] The present invention provides a patterning process technology that can improve the absorption capacity of thin films for microwaves in a specific frequency band without increasing the thickness and quality of the film. The present invention increases the surface area of ​​the film by patterning the thin film material. Figure 1-2Many small interfaces are added at the laser ablation site (i.e., the four sides of the protrusion 2), and the incident wave 3 is directed toward the patterned thin film material 1 of the present invention to form a transmitted wave 4 and a reflected wave 5. Due to the presence of the protrusion 2, the reflection path of the microwave inside the patterned thin film material 1 is increased, forming more internal reflection waves 6 of the thin film, which increases the reflection loss of the electromagnetic wave inside the patterned thin film material 1. Therefore, the patterned thin film material of the present invention has a good microwave shielding effect. At the same time, no composite structure of multi-layer materials is used, and the thickness and weight of the thin film material will not be increased. The prepared absorbing material has the characteristics of light weight and thin thickness.

[0021] The reason for setting the protrusion heights and protrusion intervals to be equal in the present invention is to simplify the manufacturing process and ensure the uniformity of the absorbing material.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The absorbing film material of the present invention has better electromagnetic shielding effectiveness in the X-band than the film material without patterning. The total shielding effectiveness against microwaves in the 8-12 GHz frequency band can reach 38 dB, which is about 12% higher than that of the unprocessed MXene film material.

[0024] (2) The absorbing film material of the present invention does not use a composite structure of multiple layers of material, which does not increase the thickness and weight of the film material. The prepared absorbing material has the characteristics of being light and thin. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of microwaves passing through the patterned thin film material of the present invention;

[0026] Figure 2 Schematic diagram of the microwave shielding principle of the patterned thin film material of the present invention.

[0027] Description of the marks in the figure:

[0028] 1-Patterned thin film material, 2-Bump, 3-Incident wave, 4-Transmitted wave, 5-Reflected wave, 6-Reflected wave inside the thin film. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0030] In the following examples, unless otherwise specified, the raw materials or processing techniques used are conventional commercially available raw materials or conventional processing techniques in the art.

[0031] In the following examples, the MXene films used were homemade in the laboratory, and the preparation steps were as follows:

[0032] (1) Preparation of MXene powder: MXene powder was obtained by etching MAX material with HCl and LiF. The specific preparation method is referenced in the literature: M. Ghidiu, MR Lukatskaya, MQ Zhao, Y. Gogotsi, MW Barsoum, Conductive two-dimensional titanium carbide 'clay' with high volumetric capacitance, Nature, 516 (2014) 78-81;

[0033] (2) The MXene powder obtained in step (1) was prepared into a solution, and then the solution was filtered using a polypropylene membrane (pore size 0.25 μm, single-layer membrane) as filter paper for 2 h (the filtration pressure was fixed by the instrument, instrument model: Chemvak VF214), and the final filter cake was dried to obtain a MXene film with a thickness of 20 μm.

[0034] In the following examples, the MXene mixed with 50% by mass silver nanowire film used was homemade in the laboratory, and the preparation steps were as follows:

[0035] (1) Preparation of silver nanowires: Specific preparation method reference: X. Zhang, X. Yan, J. Chen, J. Zhao, Large-size graphene microsheets as a protective layer for transparent conductive silver nanowire film heaters, Carbon, 69 (2014) 437-443.

[0036] (2) Silver nanowires and MXene powders were uniformly mixed in a mass ratio of 1:1, and then prepared into a mixed liquid. The mixed liquid was filtered using a polypropylene membrane (pore size 0.25 μm, single-layer membrane) as filter paper for 2 h (the filtration pressure was fixed by the instrument, instrument model: Chemvak VF214). The final filter cake was dried to obtain a 20 μm thick MXene mixed with 50% silver nanowire thin film by mass.

[0037] Example 1:

[0038] A 5cm diameter circular MXene film was placed on the platform of a laser marking machine and pressed with a press. The laser lines were spaced 200μm apart, and a cross-fill pattern was formed to create a grid pattern (the spacing between any two adjacent transverse laser lines was 200μm, and the spacing between any two adjacent longitudinal laser lines was 200μm). Red light was used for observation to prevent the press from blocking the laser pattern. Laser ablation was initiated, with the height of the protrusions reaching 20% ​​of the film thickness. The total shielding effectiveness of this sample in the 8-12GHz frequency band was approximately 35dB.

[0039] Example 2:

[0040] A 5cm diameter circular MXene film was placed on the platform of a laser marking machine and pressed with a press. The laser lines were spaced 200μm apart, and a cross-fill pattern was created (the spacing between any two adjacent transverse laser lines was 200μm, and the spacing between any two adjacent longitudinal laser lines was 200μm). Red light was used for observation to prevent the press from blocking the laser pattern. Laser ablation was then initiated, with the protrusion height reaching 30% of the film thickness. The total shielding effectiveness of this sample in the 8-12GHz frequency band was approximately 36dB.

[0041] Example 3:

[0042] A 5cm diameter circular MXene film was placed on the platform of a laser marking machine and pressed with a press. The laser lines were spaced 200μm apart and a cross-fill pattern was formed to create a grid pattern (the spacing between any two adjacent transverse laser lines was 200μm, and the spacing between any two adjacent longitudinal laser lines was 200μm). Red light was turned on to prevent the press from blocking the laser pattern. Laser ablation was then initiated to a pattern depth of 45% of the film thickness. The total shielding effectiveness of this sample in the 8-12GHz frequency band was approximately 38dB.

[0043] Example 4:

[0044] A 5cm diameter circular film of MXene mixed with 50% silver nanowires by mass was placed on the platform of a laser marking machine and pressed with a press. The laser lines were spaced 200μm apart and a cross-fill pattern was formed to create a grid pattern (the spacing between any two adjacent transverse laser lines was 200μm, and the spacing between any two adjacent longitudinal laser lines was 200μm). Red light was used for observation to prevent the press from obstructing the laser pattern. Laser ablation was initiated, with the height of the protrusions reaching 10% of the film thickness. The total shielding effectiveness of this sample in the 8-12GHz frequency band was approximately 37dB.

[0045] Example 5:

[0046] A 5cm diameter circular film of MXene mixed with 50% silver nanowires by mass was placed on the platform of a laser marking machine and pressed with a press. The laser lines were spaced 200μm apart and a cross-fill pattern was created to create a grid pattern with 200μm spacing. Red light was used for observation to prevent the press from obstructing the laser pattern. Laser ablation was then initiated, with the height of the protrusions reaching 30% of the film thickness. The total shielding effectiveness of this sample in the 8-12GHz frequency band was approximately 38dB.

[0047] Comparative Example 1:

[0048] Compared to Example 1, most aspects are the same except that no laser ablation is performed, i.e., an unprocessed MXene film material is obtained. The total shielding effectiveness of this sample in the 8-12 GHz frequency band is approximately 34 dB.

[0049] Comparative Example 2:

[0050] Compared with Example 1, most of the steps are the same except that the height of the protrusions is adjusted to 60% of the film thickness. The film is burned through at the laser intersection points.

[0051] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A patterned absorbing film material, characterized in that: The surface of the absorbing film material is provided with a plurality of protrusions arranged in a horizontal and vertical manner, wherein the intervals between any two adjacent protrusions in a horizontal row are equal, and the intervals between any two adjacent protrusions in a vertical column are equal; The protrusions have equal heights; The protrusions are arranged on the same surface of the absorbing film material; The distance between any two adjacent protrusions in a horizontal row is equal to the distance between any two adjacent protrusions in a vertical column; The height of the protrusion is 30% or 45% of the thickness of the absorbing film material; The absorbing film material is a MXene film or a MXene film doped with silver nanowires; The wave-absorbing film material is prepared by the following method: Laser ablation is used to carve grid-like marks with equal horizontal and vertical intervals on one side of the thin film material, and adjacent marks surround the material not ablated by the laser to form the protrusions; The incident wave is directed toward the absorbing film material, forming a transmitted wave and a reflected wave. Due to the presence of the protrusions, the reflection path of the microwave inside the absorbing film material is increased, forming more reflected waves inside the film, thereby increasing the reflection loss of the electromagnetic wave inside the absorbing film material.

2. The method for preparing a patterned absorbing film material according to claim 1, wherein: The method includes: Place the film raw material on the laser marking machine platform, adjust the laser line so that the laser line crosses the surface of the film raw material horizontally and vertically to obtain a grid pattern, and then perform laser ablation on the film raw material to obtain the target product.

3. The method for preparing a patterned absorbing film material according to claim 2, wherein: The power of each laser line is equal.

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