Flexible wave-absorbing patch as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of wave-absorbing materials, and particularly relates to a flexible wave-absorbing patch as well as a preparation method and application thereof. According to the flexible wave-absorbing patch disclosed by the invention, the raw material formula is designed and optimized, the modified epoxy resin is compounded with the acrylic resin and the alkyd resin to serve as an adhesive, and a stable and compact three-dimensional network structure is generated by ring-opening crosslinking of an epoxy group in the modified epoxy resin, so that the wave-absorbing patch has relatively good mechanical strength and environmental adaptability; ester groups in the acrylic resin and the alkyd resin are used for providing flexibility and weather resistance, so that the wave-absorbing patch has excellent flexibility and can be attached to various special-shaped curved surfaces or inclined surfaces according to actual requirements. Besides, the flexible wave-absorbing patch can change the proportion of the absorbent in the raw material formula according to actual requirements, so that the radar wave-absorbing performance is adjusted, and a feasible solution is provided for stealth performance test or in-situ rapid repair of stealth equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave absorbing materials, and particularly relates to a flexible microwave absorbing patch and a preparation method and application thereof. Background Art

[0002] A microwave absorbing material is a special functional material that can absorb or attenuate the energy of electromagnetic waves. Its core function is to convert the incident electromagnetic wave energy into heat energy or other forms of energy, thereby achieving the attenuation or elimination of electromagnetic waves. With the rapid development of modern technology, the application of electromagnetic waves in the fields of military, communication, electronic devices, etc. is becoming increasingly widespread, and the problem of electromagnetic pollution is also becoming increasingly prominent. Therefore, the research and development of microwave absorbing materials has become one of the important directions in the field of materials science.

[0003] However, although microwave absorbing materials show great application potential in many fields, the limitations of traditional microwave absorbing materials are also becoming increasingly prominent. Traditional microwave absorbing materials are usually prepared using an epoxy resin system. Although this material has high mechanical strength and heat resistance, its material is hard and brittle, lacking flexibility, and it is difficult to meet the requirements of complex shapes and sizes, that is, it cannot adapt to deformations such as bending and stretching, resulting in great limitations in its application scenarios. Therefore, there is an urgent need for a flexible microwave absorbing patch to solve the problems existing in traditional microwave absorbing materials.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a flexible microwave absorbing patch and a preparation method and application thereof.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides a flexible microwave absorbing patch, which comprises the following components by weight: 20 - 30 parts by weight of resin, 6 - 10 parts by weight of curing agent, 50 - 60 parts by weight of absorbent, 6 - 13 parts by weight of diluent, and 1 - 2 parts by weight of auxiliary agent.

[0008] Specifically, one side of the flexible microwave absorbing patch is adhered with a backing adhesive, and the backing adhesive is 3M backing adhesive.

[0009] Specifically, the resin includes at least two of modified epoxy resin, acrylic resin, and alkyd resin; the absorbent includes one of spherical carbonyl iron powder, flaky carbonyl iron powder, and iron silicon chromium; the curing agent is at least two of diethylenetriamine (DETA), PA650 polyamide, and HI100 isocyanate; the auxiliary agent includes at least three of dispersant, leveling agent, anti-settling agent, and adhesion promoter; the diluent includes at least three of ethanol, xylene, butyl acetate, and propylene glycol monomethyl ether acetate (PMA).

[0010] Specifically, the dispersant is MR110 (polyphosphate ester), the leveling agent is SN4006 (polyether modified silicone), the anti-settling agent is M5 fumed SiO2, and the adhesion promoter is KH550 (γ-aminopropyltriethoxysilane).

[0011] On the other hand, the present invention provides a method for preparing a flexible microwave absorbing patch, and the specific steps are as follows:

[0012] Step 1: Weigh the resin, absorbent, diluent and additives according to the required weights;

[0013] Step 2: At room temperature, sequentially mix and disperse the diluent, resin, absorbent and additives through a homogenizing disperser, with a stirring speed of 900 - 1200 r / min and a stirring time of 60 - 80 min, to obtain Coating A after mixing and dispersing;

[0014] Step 3: Select an aluminum plate or a titanium plate as the metal plate, and clean the surface of the metal plate with anhydrous ethanol to ensure that there are no residues such as dust and oil stains on the surface of the metal plate;

[0015] Step 4: First, weigh the curing agent according to the required weight, and manually mix it evenly with Coating A to obtain microwave absorbing coating B. Then, spray the microwave absorbing coating B on the surface of the metal plate by air spraying to obtain microwave absorbing coating layer B; during spraying, the air compressor pressure value is 0.60 - 0.80 MPa, the distance between the spray gun and the surface of the workpiece is 20 - 30 cm, and the angle between the spray gun and the surface of the workpiece is 45° - 90°;

[0016] Step 5: Cure the microwave absorbing coating layer B using an oven. When curing, the temperature of the oven is 50 - 70 °C, the heating time is 100 - 120 min, and after curing, it is cooled to room temperature with the oven;

[0017] Step 6: Use a craft knife to peel the cured microwave absorbing coating layer B from the surface of the metal plate. The thickness of the cured microwave absorbing coating layer B is 1.2 - 1.4 mm;

[0018] Step 7: Place the peeled microwave absorbing coating layer B with its back facing up on a clean workbench, evenly attach 3M adhesive on the back of the microwave absorbing coating layer B, and cut the adhesive according to the outer shape size of the microwave absorbing coating layer B to finally obtain the required flexible microwave absorbing patch.

[0019] On yet another aspect, the present invention provides a flexible microwave absorbing patch or the application of a flexible microwave absorbing patch prepared by the above preparation method. The flexible microwave absorbing patch provides electromagnetic protection for electronic devices by absorbing or weakening electromagnetic wave energy.

[0020] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0021] Through the design and optimization of the raw material formula, the flexible microwave absorbing patch of the present invention uses a modified epoxy resin compounded with an acrylic resin and an alkyd resin as an adhesive. By using the epoxy group in the modified epoxy resin to open the ring and crosslink to generate a stable and dense three-dimensional network structure, the microwave absorbing patch has good mechanical strength and environmental adaptability. The ester groups in the acrylic resin and the alkyd resin are used to provide flexibility and weather resistance, so that the microwave absorbing patch has excellent flexibility and can conform to various special-shaped curved surfaces or inclined surfaces according to actual needs. In addition, the flexible microwave absorbing patch of the present invention can change the proportion of the absorber in the raw material formula according to specific needs, so as to adjust the radar wave absorption performance, providing a practical solution for the performance testing of stealth devices and electromagnetic protection devices;

[0022] This preparation method uses the mature air spraying method to prepare the coating, with high efficiency and low preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings herein are incorporated into the specification and form a part of this specification, and are used together with the specification to explain the principles of the present invention.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 is a flowchart of the preparation method of the present invention;

[0026] Figure 2 is a diagram showing the flexibility of the flexible microwave absorbing patch prepared by the present invention;

[0027] Figure 3 is a radar reflectivity curve of the flexible microwave absorbing patch prepared in the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are only examples consistent with some aspects of the present invention detailed in the appended claims.

[0029] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0030] On the one hand, the present invention provides a flexible microwave absorbing patch, which comprises the following components by weight: 20-30 parts by weight of resin, 6-10 parts by weight of curing agent, 50-60 parts by weight of absorber, 6-13 parts by weight of diluent, and 1-2 parts by weight of additive.

[0031] Specifically, one side of the flexible microwave absorbing patch is coated with an adhesive, and the adhesive is 3M adhesive.

[0032] Specifically, the resin includes at least two of modified epoxy resin, acrylic resin, and alkyd resin; the absorber includes one of spherical carbonyl iron powder, flaky carbonyl iron powder, and iron silicon chromium; the curing agent is at least two of diethylenetriamine (DETA), PA650 polyamide, and HI100 isocyanate; the additive includes at least three of dispersant, leveling agent, anti-settling agent, and adhesion promoter; the diluent includes at least three of ethanol, xylene, butyl acetate, and propylene glycol methyl ether acetate (PMA).

[0033] Specifically, the dispersant is MR110 (polyphosphate ester), the leveling agent is SN4006 (polyether modified silicone), the anti-settling agent is M5 fumed SiO2, and the adhesion promoter is KH550 (γ-aminopropyltriethoxysilane).

[0034] On the other hand, the present invention provides a preparation method of a flexible microwave absorbing patch, and the specific steps are as follows:

[0035] Step 1: Weigh the required weight of diluent, resin, absorber, and additive with an electronic balance.

[0036] Step 2: At room temperature, sequentially mix and disperse the diluent, resin, absorber, and additive through a homogenizing disperser, with a stirring speed of 900-1200 r / min and a stirring time of 60-80 min, to obtain Coating A after mixing and dispersing.

[0037] Step 3: Select an aluminum plate or a titanium plate as the metal plate, and clean the surface of the metal plate with anhydrous ethanol to ensure that there are no residues such as dust and oil stains on the surface of the metal plate.

[0038] Step 4: First, weigh the required weight of the curing agent, and manually mix it evenly with Coating A to obtain microwave absorbing Coating B. Spray the microwave absorbing Coating B on the surface of the metal plate by air spraying to obtain Microwave Absorbing Coating B; during spraying, the air compressor pressure value is 0.60-0.80 MPa, the distance between the spray gun and the surface of the workpiece is 20-30 cm, and the angle between the spray gun and the surface of the workpiece is 45°-90°.

[0039] Step 5: Cure the absorbent coating B using an oven. When curing, the temperature of the oven is 50 - 70°C, and the heating time is 100 - 120 min. After curing, let it cool to room temperature with the oven.

[0040] Step 6: Use a craft knife to peel the cured absorbent coating B from the surface of the metal plate. The thickness of the cured absorbent coating B is 1.2 - 1.4 mm.

[0041] Step 7: Place the peeled absorbent coating B with its back facing up on a clean workbench. Evenly apply 3M adhesive on the back of the absorbent coating B, and cut the adhesive according to the outer shape size of the absorbent coating B to finally obtain the required flexible absorbent patch. See Figure 2 shown in Figure 2 (a) and Figure 2 (b) are flexible absorbent patches shown from different perspectives.

[0042] It should be noted that there is no sequence requirement for Steps 1, 2, and 3, and their sequence is determined by the actual generation situation.

[0043] To prove the effect of the preparation method of the present invention, the following examples are provided for verification:

[0044] Example 1

[0045] See Figure 1 shown in

[0046] Step 1: Weigh 30 parts by weight of resin, 10 parts by weight of curing agent, 50 parts by weight of absorbent, 8 parts by weight of diluent, and 2 parts by weight of additive using an electronic balance. Among them, the resin is a mixture of 10% modified epoxy resin and 90% acrylic resin; the absorbent is spherical carbonyl iron powder; the additive is a mixture of 45% dispersant MR110, 45% leveling agent SN4006, and 10% anti-settling agent M5 fumed silica; the diluent is a mixture of 30% ethanol, 30% butyl acetate, and 40% PMA.

[0047] Step 2: At room temperature, sequentially add the diluent, resin, absorbent, and additive into a homogenizing disperser for mixing and dispersion, and stir and disperse at a speed of 1200 r / min for 60 min to obtain Coating A.

[0048] Step 3: Clean the surface of the aluminum plate with absolute ethanol to ensure that there are no residues such as dust and oil stains on the surface of the aluminum plate.

[0049] Step 4: Weigh the curing agent as required. The curing agent is a mixture of 20% DETA and 80% HI100 isocyanate, and it is manually mixed evenly with Coating A to obtain Absorbing Coating B. At room temperature, the Absorbing Coating B is sprayed on the surface of the cleaned aluminum plate by air spraying method. The air compressor pressure value is 0.80 MPa, the distance between the spray gun and the workpiece surface is 30 cm, and the angle between the spray gun and the workpiece surface is 60°, to obtain Absorbing Coating Layer B;

[0050] Step 5: Cure Absorbing Coating Layer B using an oven. The temperature is set at 70 °C and the heating time is 100 min. After the oven cools down to room temperature, take out Absorbing Coating Layer B;

[0051] Step 6: Use a craft knife to completely peel the cured Absorbing Coating Layer B from the surface of the aluminum plate. The thickness of the Absorbing Coating B is 1.4 mm;

[0052] Step 7: Place the peeled Absorbing Coating B with its back facing up on a clean workbench, evenly attach 3M adhesive tape to the back of the Absorbing Coating B, and cut the 3M adhesive tape according to the outer shape size of the Absorbing Coating B to obtain the required flexible absorbing patch.

[0053] Example 2

[0054] See Figure 1 As shown, this example provides a method for preparing a flexible absorbing patch, and the specific steps are as follows:

[0055] Step 1: Weigh 20 parts by weight of resin, 6 parts by weight of curing agent, 60 parts by weight of absorbent, 13 parts by weight of diluent, and 1 part by weight of additive using an electronic balance; among them, the resin is a mixture of 10% modified epoxy resin, 80% acrylic resin, and 10% alkyd resin, the absorbent is flaky carbonyl iron powder, and the additive is a mixture of 55% dispersant MR110, 35% leveling agent SN4006, and 10% anti-settling agent M5 fumed silica; the diluent is a mixture of 40% ethanol, 20% butyl acetate, and 40% PMA;

[0056] Step 2: At room temperature, sequentially add the diluent, resin, absorbent, and additive to a homogenizing disperser for mixing and dispersion, and stir and disperse at a speed of 900 r / min for 80 min to obtain Coating A;

[0057] Step 3: Clean the surface of the aluminum plate with anhydrous ethanol to ensure that there are no residues such as dust and oil stains on the surface of the aluminum plate;

[0058] Step 4: Weigh the curing agent according to the required weight. The curing agent is a mixture of 20% DETA, 20% PA650 polyamide, and 60% HI100 isocyanate, and manually mix it evenly with Coating A to obtain Absorbing Coating B. At room temperature, spray the Absorbing Coating B on the surface of the cleaned aluminum plate by air spraying method. The air compressor pressure value is 0.60 MPa, the distance between the spray gun and the workpiece surface is 20 cm, and the angle between the spray gun and the workpiece surface is 70°, to obtain Absorbing Coating Layer B;

[0059] Step 5: Cure the Absorbing Coating B in an oven. Set the temperature to 50 °C and the heating time to 120 min. After the oven cools down to room temperature, take out the Absorbing Coating B;

[0060] Step 6: Use a utility knife to completely peel the cured Absorbing Coating B from the surface of the aluminum plate. The thickness of the Absorbing Coating B is 1.2 mm;

[0061] Step 7: Place the peeled Absorbing Coating B with its back facing up on a clean workbench, evenly apply 3M adhesive tape on the back of the Absorbing Coating B, and cut the 3M adhesive tape according to the outer shape size of the Absorbing Coating B to obtain the required flexible absorbing patch.

[0062] Example 3

[0063] See Figure 1 As shown, this example provides a preparation method of a flexible absorbing patch, and the specific steps are as follows:

[0064] Step 1: Weigh 25 parts by weight of resin, 8 parts by weight of curing agent, 55 parts by weight of absorbent, 10.5 parts by weight of diluent, and 1.5 parts by weight of additive using an electronic balance; among them, the resin is a mixture of 10% modified epoxy resin, 45% acrylic resin, and 45% alkyd resin, the absorbent is iron silicon chromium, and the additive is a mixture of 40% dispersant MR110, 40% leveling agent SN4006, 10% anti-settling agent M5 fumed silica, and 10% adhesion promoter KH550; the diluent is a mixture of 40% ethanol, 30% xylene, and 30% PMA;

[0065] Step 2: At room temperature, sequentially add the diluent, resin, absorbent, and additive into a homogenizing disperser for mixing and dispersing, and stir and disperse at a rotation speed of 1000 r / min for 70 min to obtain Coating A;

[0066] Step 3: Clean the surface of the titanium plate with anhydrous ethanol to ensure that there are no residues such as dust and oil stains on the surface of the titanium plate;

[0067] Step 4: Weigh the curing agent according to the required weight. The curing agent is a mixture of 10% DETA, 20% PA650 polyamide curing agent, and 70% HI100 isocyanate curing agent. Manually mix it evenly with the coating A to obtain the absorbing coating B. At room temperature, spray the absorbing coating B on the surface of the cleaned titanium plate by air spraying method. The air compressor pressure value is 0.70 MPa, the distance between the spray gun and the workpiece surface is 25 cm, and the angle between the spray gun and the workpiece surface is 80° to obtain the absorbing coating B;

[0068] Step 5: Cure the absorbing coating B in an oven. Set the temperature to 60 °C and the heating time to 110 min. Take out the absorbing coating B after the oven cools down to room temperature;

[0069] Step 6: Use a utility knife to completely peel the cured absorbing coating B from the surface of the titanium plate. The thickness of the absorbing coating B is 1.3 mm;

[0070] Step 7: Place the peeled absorbing coating B with its back facing up on a clean workbench. Evenly apply 3M adhesive tape on the back of the absorbing coating B and cut the 3M adhesive tape according to the outer shape size of the absorbing coating B to obtain the required flexible absorbing patch.

[0071] See Figure 3 As shown, the abscissa is the frequency and the ordinate is the reflection loss; the absorbent used in Example 1 is 50% by weight of spherical carbonyl iron powder, and the coating thickness is 1.4 mm. The specific surface area of spherical carbonyl iron powder is relatively small, resulting in its eddy current loss ability being inferior to that of iron-silicon-chromium and flake carbonyl iron powder in the high-frequency band (above the X band). However, in the low-frequency band (S / C band), the electromagnetic wave wavelength is longer, and the spherical morphology of carbonyl iron powder is more conducive to uniform distribution inside the coating, forming a continuous magnetic path. Therefore, the impedance matching is higher, the reflection loss is smaller, and the overall absorption curve is flat; the absorbent used in Example 2 is 60% flake carbonyl iron powder, and the coating thickness is 1.2 mm. Flake carbonyl iron powder has significant anisotropy due to its morphological characteristics. Its flat structure increases the in-plane component of the magnetic moment, improving the storage and loss performance of electromagnetic waves. At the same time, the flake stacking forms an interlayer capacitance, triggering dielectric loss and realizing the magnetic-dielectric synergistic loss mechanism. Therefore, it has excellent high-frequency electromagnetic performance. The absorbent used in Example 3 is 55% iron-silicon-chromium, and the coating thickness is 1.3 mm. Iron-silicon-chromium is a multi-element alloy. The doping of silicon reduces the conductivity of the material, slowing down the attenuation of eddy current loss with the increase of frequency. The synergistic effect of chromium and iron can improve the magnetocrystalline anisotropy and enhance the hysteresis loss, thus bringing outstanding high-frequency wave absorption performance.

[0072] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0073] It should be understood that the present invention is not limited to the above-described content and can be variously modified and changed without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A flexible microwave absorbing patch, characterized in that By weight, it includes the following components: 20 - 30 parts by weight of resin, 6 - 10 parts by weight of curing agent, 50 - 60 parts by weight of absorbent, 6 - 13 parts by weight of diluent, and 1 - 2 parts by weight of additives.

2. The flexible absorbing patch according to claim 1, wherein The resin includes at least two of modified epoxy resin, acrylic resin, and alkyd resin; the absorbent includes one of spherical carbonyl iron powder, flaky carbonyl iron powder, and iron silicon chromium; the curing agent includes at least two of diethylenetriamine, polyamide, and isocyanate; the additives include at least three of dispersant, leveling agent, anti-settling agent, and adhesion promoter; the diluent includes at least three of ethanol, xylene, butyl acetate, and propylene glycol methyl ether acetate.

3. The flexible absorbing patch according to claim 2, wherein The dispersant is MR110, the leveling agent is SN4006, the anti-settling agent is fumed SiO2, and the adhesion promoter is KH550.

4. The preparation method of the flexible microwave absorbing patch according to any one of claims 1 to 3, characterized in that, The specific steps are as follows: Step 1: Weigh the diluent, resin, absorbent, and additives according to the required weights. Step 2: Mix and disperse the diluent, resin, absorbent, and additives to obtain Coating A. Step 3: Select a metal plate and perform surface pretreatment. Step 4: First, weigh the curing agent according to the required weight and add it to Coating A and mix evenly before spraying to obtain the microwave-absorbing coating B, and then spray the microwave-absorbing coating B on the surface of the metal plate to obtain the microwave-absorbing coating B. Step 5: Cure the microwave-absorbing coating B and then cool it. Step 6: Peel the cured microwave-absorbing coating B from the surface of the metal plate. Step 7: Stick an adhesive on the back of the peeled microwave-absorbing coating B to finally obtain the required flexible microwave-absorbing patch.

5. The preparation method according to claim 4, wherein, In Step 2, at room temperature, a homogenizing disperser is used for mixing and dispersing, the stirring speed is 900 - 1200 r / min, and the stirring time is 60 - 80 min.

6. The preparation method according to claim 4, characterized in that, In Step 3, the metal plate includes one of aluminum plate or titanium plate.

7. The preparation method according to claim 4, wherein In Step 4, the air spraying method is used to spray the microwave-absorbing coating B. During spraying, the air compressor pressure value is 0.60 - 0.80 MPa, the distance between the spray gun and the workpiece surface is 20 - 30 cm, and the angle between the spray gun and the workpiece surface is 45° - 90°.

8. The preparation method according to claim 4, characterized in that, In Step 5, an oven is used for curing. During curing, the temperature of the oven is 50 - 70 °C, the heating time is 100 - 120 min, and after curing, it is cooled to room temperature with the oven.

9. The preparation method according to claim 4, wherein In Step 6, the thickness of the cured microwave-absorbing coating B is 1.2 - 1.4 mm.

10. Application of the flexible microwave absorbing patch according to any one of claims 1 to 3, or the flexible microwave absorbing patch prepared by the preparation method according to any one of claims 4 to 9, characterized in that The flexible microwave-absorbing patch provides electromagnetic protection for electronic devices by absorbing or weakening electromagnetic wave energy.

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