Composite wave-absorbing film and preparation method thereof

Abstract

The application relates to the technical field of wave-absorbing materials, and particularly discloses a composite wave-absorbing film and a preparation method thereof. The composite wave-absorbing film comprises an iron-based wave-absorbing film layer, a first dielectric layer and a second dielectric layer; the iron-based wave-absorbing film layer contains the following components: 70-86 wt% of iron powder and the balance of epoxy resin; the first dielectric layer contains the following components: 32-46 wt% of zirconium oxide, 35-44 wt% of silicon dioxide and the balance of photocuring resin; and the second dielectric layer contains the following components: 16-22 wt% of aluminum fluoride, 48-66 wt% of aluminum oxide and the balance of photocuring resin. The composite wave-absorbing film has multi-frequency band absorption capacity and high wave-absorbing intensity.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, and in particular to a composite microwave absorbing film and its preparation method. Background Technology

[0002] Electromagnetic absorbing films are sheet-like absorbing materials that absorb electromagnetic waves into their interior and then convert them into other forms that dissipate. They have wide applications in stealth technology for military and civilian equipment, improving communication performance, microwave anechoic chambers, controlling electromagnetic pollution, and electromagnetic safety protection. Therefore, current requirements for absorbing films are that they must be thin, lightweight, wide, and strong.

[0003] However, existing electromagnetic absorbing films are often made by mixing ferrite or iron powder with epoxy resin, which results in a single absorption frequency band and low absorption efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a composite absorbing film and its preparation method. The obtained absorbing film has multi-frequency absorption capability and high absorption intensity.

[0005] To address the aforementioned problems, this invention proposes a composite absorbing membrane, comprising an iron-based absorbing membrane layer, a first dielectric layer, and a second dielectric layer.

[0006] The iron-based absorbing film contains the following components: 70-86 wt% iron powder, with the balance being epoxy resin;

[0007] The first dielectric layer contains the following components: 32-46 wt% zirconium oxide, 35-44 wt% silicon dioxide, and the balance being photocurable resin;

[0008] The second dielectric layer contains the following components: 16-22 wt% aluminum fluoride, 48-66 wt% aluminum oxide, and the balance being photocurable resin.

[0009] As an improvement to the above technical solution, the first dielectric layer contains the following components: 35-42 wt% zirconium oxide, 40-42 wt% silicon dioxide, and the balance being photocurable resin.

[0010] The second dielectric layer contains the following components: 20-22 wt% aluminum fluoride, 48-59 wt% aluminum oxide, and the balance being photocurable resin.

[0011] As an improvement to the above technical solution, the weight ratio of zirconium oxide, silicon dioxide, aluminum fluoride and aluminum oxide is (10-12):(9-11):(8-10):(19-24).

[0012] As an improvement to the above technical solution, the weight ratio of iron powder to zirconium oxide is (40-42):1.

[0013] As an improvement to the above technical solution, the iron-based absorbing film layer also contains glass microspheres, and the amount of glass microspheres added is 0.7 to 1.2 wt%.

[0014] As an improvement to the above technical solution, the thickness of the iron-based absorbing film layer is 0.5-1.4 mm, the thickness of the first dielectric layer and the second dielectric layer is 0.2-0.4 mm, and the planar dimensions of the iron-based absorbing film layer, the first dielectric layer and the second dielectric layer are the same.

[0015] Accordingly, the present invention also provides a method for preparing the composite absorbing film as described above, comprising the following steps:

[0016] (1) Mix iron powder and epoxy resin evenly to obtain slurry A, and use calendering equipment to calender slurry A to obtain iron-based microwave absorbing film layer;

[0017] (2) Zirconia, silica and photocurable resin are mixed evenly to obtain slurry B, and aluminum fluoride, alumina and photocurable resin are mixed evenly to obtain slurry C;

[0018] (3) Use slurry B and slurry C as slurries for a membrane-free direct-write 3D printing device, and print the first dielectric layer and the second dielectric layer on the iron-based microwave absorbing film layer using the membrane-free direct-write 3D printing device.

[0019] As an improvement to the above technical solution, in step (1), the slurry A is preheated at 60-100°C for 5-8 minutes before calendering; the calendering equipment includes calendering rolls, and the working temperature of the calendering rolls is 50-65°C.

[0020] As an improvement to the above technical solution, in step (3), the working input gas pressure of the film-free direct writing 3D printing device is 480-580 kPa, and the working gas output is 10-100 psi.

[0021] As an improvement to the above technical solution, in step (3), slurry B and slurry C are used as slurries for the film-free direct writing 3D printing equipment, and the film-free direct writing 3D printing equipment prints the first dielectric layer and the second dielectric layer on the same side of the iron-based microwave absorbing film layer.

[0022] The implementation of this invention has the following beneficial effects:

[0023] In the preparation method of the composite absorbing film of the present invention, a first dielectric layer and a second dielectric layer are printed on both sides of the iron-based absorbing film layer by a film-free direct-write 3D printing device, or the first dielectric layer and the second dielectric layer are randomly printed on one side of the iron-based absorbing film layer, so that it has a three-layer composite structure. Specifically, the first dielectric layer contains zirconium oxide and silicon dioxide, and the second dielectric layer contains aluminum fluoride and aluminum oxide. Under the action of the composite structure of three different matrix components, the composite absorbing film of the present invention has multi-band wave absorption capability and strong wave absorption capability. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0025] This invention discloses a composite absorbing film, comprising an iron-based absorbing film layer, a first dielectric layer, and a second dielectric layer;

[0026] The iron-based absorbing film contains the following components: 70-86 wt% iron powder, with the balance being epoxy resin;

[0027] The first dielectric layer contains the following components: 32-46 wt% zirconium oxide, 35-44 wt% silicon dioxide, and the balance being photocurable resin;

[0028] The second dielectric layer contains the following components: 16-22 wt% aluminum fluoride, 48-66 wt% aluminum oxide, and the balance being photocurable resin.

[0029] The first dielectric layer of the present invention contains zirconium oxide and silicon dioxide, and the second dielectric layer contains aluminum fluoride and aluminum oxide. The first dielectric layer and the second dielectric layer are respectively disposed on both sides of the iron-based absorbing film layer, or the first dielectric layer and the second dielectric layer are randomly disposed on the same side. Since the composite absorbing film of the present invention is a multi-layer structure composed of three different matrix components, it has multi-band absorbing function and high absorbing intensity.

[0030] Preferably, the first dielectric layer contains the following components: 35-42 wt% zirconium oxide, 40-42 wt% silicon dioxide, and the balance being photocurable resin; the mass percentage of zirconium oxide is, for example, 35 wt%, 37 wt%, 39 wt%, or 42 wt%, but is not limited thereto; the mass percentage of silicon dioxide is, for example, 40 wt%, 41 wt%, or 42 wt%, but is not limited thereto.

[0031] The second dielectric layer contains the following components: 20-22 wt% aluminum fluoride, 48-59 wt% aluminum oxide, and the balance being photocurable resin; the mass percentage of aluminum fluoride is 20 wt%, 21 wt%, or 22 wt%, but is not limited thereto; the mass percentage of aluminum oxide is 48 wt%, 49 wt%, 50 wt%, or 52 wt%, but is not limited thereto.

[0032] Preferably, the weight ratio of zirconium oxide, silicon dioxide, aluminum fluoride, and aluminum oxide is (10-12):(9-11):(8-10):(19-21). When zirconium oxide, silicon dioxide, aluminum fluoride, and aluminum oxide are in a specific weight ratio, the width of the absorption frequency band of the composite absorbing film can be further improved. The wider the absorption frequency band of the composite absorbing film, the stronger its applicability.

[0033] Preferably, the weight ratio of iron powder to zirconium oxide is (40-42):1. Limiting the ratio of iron powder to zirconium oxide increases the absorption intensity of the composite absorbing membrane. Examples include 40:1, 41:1, and 42:1, but are not limited to these.

[0034] Furthermore, the iron-based absorbing film layer also contains glass microspheres, with the amount of glass microspheres added being 0.7–1.2 wt%. Glass microspheres have high electromagnetic wave transmittance and do not affect the wave absorption performance of the absorbing powder within them. In addition, the hollow structure of the glass microspheres reduces the density of the absorbing matrix, making it less likely for the iron powder to settle in the slurry, allowing for uniform mixing and distribution, and ensuring the uniformity and stability of the wave absorption performance in all parts of the coating. Examples include 0.7 wt%, 0.9 wt%, and 1.0 wt%, but the addition is not limited to these.

[0035] Furthermore, the thickness of the iron-based absorbing film layer is 0.5–1.4 mm, the thickness of the first dielectric layer and the second dielectric layer is 0.2–0.4 mm, and the planar dimensions of the iron-based absorbing film layer, the first dielectric layer and the second dielectric layer are the same.

[0036] This invention also discloses a method for preparing a composite absorbing film, comprising the following steps:

[0037] (1) Mix iron powder and epoxy resin evenly to obtain slurry A, and use calendering equipment to calender slurry A to obtain iron-based microwave absorbing film layer;

[0038] Specifically, the steps include:

[0039] (1.1) Mix iron powder and epoxy resin evenly to obtain slurry A;

[0040] (1.2) Preheat slurry A at 60-100℃ for 5-8 minutes;

[0041] (1.3) The slurry A is calendered using a calendering equipment to obtain an iron-based microwave absorbing film layer; wherein the working temperature of the calendering roll of the calender is 50-65℃.

[0042] (2) Zirconia, silica and photocurable resin are mixed evenly to obtain slurry B, and aluminum fluoride, alumina and photocurable resin are mixed evenly to obtain slurry C;

[0043] (3) Using slurry B and slurry C as slurries in a film-free direct-write 3D printing device, the first dielectric layer and the second dielectric layer are printed on both sides of the iron-based microwave absorbing film layer, respectively, or the first dielectric layer and the second dielectric layer are randomly printed on one side of the iron-based microwave absorbing film layer. The working input gas pressure of the film-free direct-write 3D printing device is 480–580 kPa, and the working gas output is 10–100 psi.

[0044] Preferably, slurry B and slurry C are used as slurries in the film-free direct-write 3D printing equipment, which prints a first dielectric layer and a second dielectric layer on the same side of the iron-based absorbing film. Printing the first and second dielectric layers on the same side of the iron-based absorbing film can improve the preparation efficiency of the composite absorbing film.

[0045] The present invention is further illustrated below with specific embodiments:

[0046] Example 1

[0047] formula:

[0048] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 110g silica, 96g UV-curable resin; Slurry C: 60g aluminum fluoride, 162g alumina, 111g UV-curable resin.

[0049] Preparation steps:

[0050] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0051] (2) Use the paste B and paste C obtained by mixing them evenly according to the formula as the paste of the film-free direct writing 3D printing equipment. Then, print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on both sides of the iron-based microwave absorbing film layer respectively. The working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0052] Example 2

[0053] formula:

[0054] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 110g silica, 96g UV-curable resin; Slurry C: 60g aluminum fluoride, 162g alumina, 111g UV-curable resin.

[0055] Preparation steps:

[0056] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0057] (2) Use slurry B and slurry C, which are mixed evenly according to the formula, as slurries for the film-free direct writing 3D printing equipment. Print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on the same side of the iron-based microwave absorbing film layer in sequence; wherein, the working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0058] Example 3

[0059] formula:

[0060] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 110g silica, 96g UV-curable resin; Slurry C: 60g aluminum fluoride, 162g alumina, 111g UV-curable resin.

[0061] Preparation steps:

[0062] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0063] (2) Use the paste B and paste C obtained by mixing them evenly according to the formula as the paste of the film-free direct writing 3D printing equipment, and print the second dielectric layer and the first dielectric layer with a thickness of 0.2 mm on the same side of the iron-based microwave absorbing film layer in sequence; wherein, the working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0064] Example 4

[0065] formula:

[0066] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 97g silica, 70g UV-curable resin; Slurry C: 60g aluminum fluoride, 162g alumina, 78g UV-curable resin.

[0067] Preparation steps:

[0068] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0069] (2) Use slurry B and slurry C, which are mixed evenly according to the formula, as slurries for the film-free direct writing 3D printing equipment. Print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on the same side of the iron-based microwave absorbing film layer in sequence; wherein, the working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0070] Example 5

[0071] formula:

[0072] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 97g silica, 48g UV-curable resin; Slurry C: 71g aluminum fluoride, 211g alumina, 41g UV-curable resin.

[0073] Preparation steps:

[0074] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0075] (2) Use slurry B and slurry C, which are mixed evenly according to the formula, as slurries for the film-free direct writing 3D printing equipment. Print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on the same side of the iron-based microwave absorbing film layer in sequence; wherein, the working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0076] Example 6

[0077] formula:

[0078] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 97g silica, 48g UV-curable resin; Slurry C: 71g aluminum fluoride, 211g alumina, 73g UV-curable resin.

[0079] Preparation steps:

[0080] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0081] (2) Use the paste B and paste C obtained by mixing them evenly according to the formula as the paste of the film-free direct writing 3D printing equipment. Then, print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on both sides of the iron-based microwave absorbing film layer respectively. The working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0082] Example 7

[0083] formula:

[0084] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 71g zirconium oxide, 78g silica, 38g UV-curable resin; Slurry C: 71g aluminum fluoride, 163g alumina, 89g UV-curable resin.

[0085] Preparation steps:

[0086] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0087] (2) Use slurry B and slurry C, which are mixed evenly according to the formula, as slurries for the film-free direct writing 3D printing equipment. Then, print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on the same side of the iron-based microwave absorbing film layer in sequence. The working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0088] Example 8

[0089] formula:

[0090] Slurry A: 2900g iron powder, 928g epoxy resin, 39g glass microspheres; Slurry B: 97g zirconium oxide, 110g silica, 96g UV-curable resin; Slurry C: 60g aluminum fluoride, 162g alumina, 111g UV-curable resin.

[0091] Preparation steps:

[0092] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0093] (2) Use slurry B and slurry C, which are mixed evenly according to the formula, as slurries for the film-free direct writing 3D printing equipment. Print the first dielectric layer and the second dielectric layer with a thickness of 0.2 mm on the same side of the iron-based microwave absorbing film layer in sequence; wherein, the working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0094] Comparative Example 1

[0095] formula:

[0096] Slurry A: 2900g iron powder, 967g epoxy resin;

[0097] Preparation steps:

[0098] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with a calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0099] Comparative Example 2

[0100] formula:

[0101] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry B: 97g zirconium oxide, 110g silica, 96g UV-curable resin;

[0102] Preparation steps:

[0103] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0104] (2) The paste B obtained by mixing the formula evenly is used as the paste of the film-free direct writing 3D printing equipment. The first dielectric layer with a thickness of 0.2 mm is printed sequentially on one side of the iron-based microwave absorbing film layer. The working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0105] Comparative Example 3

[0106] formula:

[0107] Slurry A: 2900g iron powder, 967g epoxy resin; Slurry C: 60g aluminum fluoride, 162g alumina, 111g UV-cured resin;

[0108] Preparation steps:

[0109] (1) The slurry A obtained by mixing the formula evenly is preheated at 65°C for 5 minutes, and then calendered by calendering equipment with calendering roller temperature of 60°C to obtain an iron-based microwave absorbing film layer with a thickness of 0.6 mm.

[0110] (2) The slurry C obtained by mixing the formula evenly is used as the slurry of the film-free direct writing 3D printing equipment. Then, a second dielectric layer with a thickness of 0.2 mm is printed on one side of the iron-based microwave absorbing film layer. The working input gas pressure of the film-free direct writing 3D printing equipment is set to 500 kPa and the working gas output is set to 30 psi.

[0111] The absorbing films obtained in Examples 1-8 and Comparative Examples 1-3 were tested, specifically:

[0112] The absorption frequency band and absorption intensity were measured using a magnetic measurement system (MPMS).

[0113] The specific test results are as follows:

[0114] Example 1 3 2-4 / 4-10 / 10-18 7 / 14 / 10 Example 2 3 2-4 / 4-10 / 10-18 7 / 14 / 11 Example 3 3 2-4 / 4-10 / 10-18 7 / 13 / 11 Example 4 3 2-4 / 4-10 / 10-18 9 / 15 / 14 Example 5 3 2-4 / 4-10 / 10-18 8 / 13 / 10 Example 6 3 1-5 / 5-11 / 11-18 9 / 15 / 13 Example 7 3 1-5 / 5-11 / 11-18 10 / 19 / 16 Example 8 3 2-4 / 4-10 / 10-18 8 / 13 / 11 Comparative Example 1 1 2-18 5 Comparative Example 2 2 2-5 / 5-18 6 / 13 Comparative Example 3 2 2-5 / 5-18 5 / 11

[0115] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A composite absorbing film, characterized in that, It includes an iron-based absorbing film layer, a first dielectric layer, and a second dielectric layer; The iron-based absorbing film contains the following components: 70-86 wt% iron powder, with the balance being epoxy resin; The first dielectric layer contains the following components: 35-42 wt% zirconium oxide, 40-42 wt% silicon dioxide, and the balance being photocurable resin; The second dielectric layer contains the following components: 20-22 wt% aluminum fluoride, 48-59 wt% aluminum oxide, and the balance being photocurable resin; The weight ratio of zirconium oxide, silicon dioxide, aluminum fluoride and aluminum oxide is (10~12):(9~11):(8~10):(19~24).

2. The composite absorbing film as described in claim 1, characterized in that, The weight ratio of the iron powder to zirconium oxide is (40~42):

1.

3. The composite absorbing film as described in claim 1, characterized in that, The iron-based absorbing film layer also contains glass microspheres, and the amount of glass microspheres added is 0.7~1.2wt%.

4. The composite absorbing film as described in claim 1, characterized in that, The thickness of the iron-based absorbing film layer is 0.5~1.4mm, the thickness of the first dielectric layer and the second dielectric layer is 0.2~0.4mm, and the planar dimensions of the iron-based absorbing film layer, the first dielectric layer and the second dielectric layer are the same.

5. A method for preparing the composite absorbing film as described in claim 1, characterized in that, Includes the following steps: (1) Mix iron powder and epoxy resin evenly to obtain slurry A, and use calendering equipment to calender slurry A to obtain iron-based microwave absorbing film layer; (2) Zirconia, silica and photocurable resin are mixed evenly to obtain slurry B, and aluminum fluoride, alumina and photocurable resin are mixed evenly to obtain slurry C; (3) Use slurry B and slurry C as slurries for a film-free direct writing 3D printing device, and print the first dielectric layer and the second dielectric layer on the iron-based microwave absorbing film layer using the film-free direct writing 3D printing device.

6. The preparation method according to claim 5, characterized in that, In step (1), the slurry A is preheated at 60~100℃ for 5~8 minutes before calendering; the calendering equipment includes calendering rolls, and the working temperature of the calendering rolls is 50~65℃.

7. The preparation method according to claim 5, characterized in that, In step (3), the working input gas pressure of the membrane-free direct writing 3D printing equipment is 480~580Kpa, and the working gas output is 10~100psi.

8. The preparation method according to claim 5, characterized in that, In step (3), slurry B and slurry C are used as slurries for the film-free direct writing 3D printing equipment, and the film-free direct writing 3D printing equipment prints a first dielectric layer and a second dielectric layer on the same side of the iron-based microwave absorbing film layer.