Wave-absorbing material, preparation method thereof and mold

Abstract

The application discloses a wave-absorbing material, a preparation method thereof and a mold, and belongs to the technical field of wave-absorbing materials. A first raw material slurry for forming a first wave-absorbing structure is poured into a second mold by using a first mold and the second mold, so that the first raw material slurry is filled in a top plate of the second mold and a column arranged at intervals on the top plate; after defoaming, drying, vulcanization and demolding, a plurality of intermediate structures are obtained, wherein the first wave-absorbing structures are arranged at intervals and protrude on a substrate. The intermediate structures are arranged in the first mold, the circumferential edge of the substrate is attached to the inner wall of the first mold, the slurry of a second raw material with better wave-absorbing performance than the first raw material is poured into the first mold, and then the slurry of the second raw material is filled in the gaps of the first wave-absorbing structures; after defoaming, drying, vulcanization and demolding, a wave-absorbing material is obtained, wherein the second wave-absorbing structures are filled in the gaps of the first wave-absorbing structures. The wave-absorbing material prepared by the method has a large effective absorption bandwidth and low reflection loss.

Description

Technical Field

[0001] This application relates to the field of microwave absorbing technology, and more specifically, to a microwave absorbing material, its preparation method, and a mold. Background Technology

[0002] With the rapid development of the electronics industry, electronic products are widely used in both military and civilian fields. Electronic products often generate significant amounts of electromagnetic radiation, causing electromagnetic pollution in the environment and negatively impacting human health. Electromagnetic absorbing materials are one of the most effective methods for eliminating electromagnetic pollution.

[0003] Microwave absorbing materials can be mainly classified into magnetic loss materials, dielectric loss materials, and resistive loss materials according to their loss mechanisms. Among the many microwave absorbing materials, magnetic loss materials have advantages such as high permeability and magnetic loss, good impedance matching characteristics, and strong absorption performance, making them the most practically valuable absorbing materials. Carbonyl iron is a typical magnetic loss absorbing material, possessing advantages such as high magnetic loss and low reflection loss, and is one of the most commonly used magnetic absorbing agents.

[0004] However, current absorbing materials cannot simultaneously satisfy the requirements of having a large effective absorption bandwidth and low reflection loss in both high-frequency and low-frequency bands. Summary of the Invention

[0005] Based on the above-mentioned shortcomings, this application provides a microwave absorbing material, its preparation method, and a mold to partially or completely improve the problems of small effective absorption bandwidth and high reflection loss of microwave absorbing materials in related technologies.

[0006] This application is implemented as follows:

[0007] In a first aspect, an example of this application provides a microwave absorbing material. The microwave absorbing material includes a substrate and a plurality of first microwave absorbing structures spaced apart on the substrate; the plurality of first microwave absorbing structures are spaced apart to form gaps, and the gaps are filled with second microwave absorbing structures; both the first microwave absorbing structures and the substrate are formed of a first raw material, the second microwave absorbing structures are formed of a second raw material, and the microwave absorption performance of the second microwave absorbing material is superior to that of the first raw material.

[0008] In the above implementation process, multiple first absorbing structures are spaced apart on the substrate, and the material of the first absorbing structure is the same as that of the second absorbing structure. The gaps between the first absorbing structures are filled with second absorbing structures formed by a second raw material with better absorbing performance, which can increase the effective absorption bandwidth of the absorbing material and reduce the reflection loss of the absorbing material.

[0009] In conjunction with the first aspect, in one possible embodiment, the first raw material comprises a first microwave absorbing agent, and the second raw material comprises a second microwave absorbing agent;

[0010] The first and second microwave absorbing agents have the same microwave absorption performance, and the percentage content of the first microwave absorbing agent in the first raw material is less than the percentage content of the second microwave absorbing agent in the second raw material.

[0011] In the above implementation process, the microwave absorption performance of the first microwave absorbing agent used to prepare the first microwave absorbing structure can be the same as that of the second microwave absorbing agent used to prepare the second microwave absorbing structure, and the percentage content of the first microwave absorbing agent in the first raw material is less than the percentage content of the second microwave absorbing agent in the second raw material, so that the prepared microwave absorbing material has good microwave absorption performance.

[0012] In conjunction with the first aspect, in one possible embodiment, both the first and second microwave absorbers are independently selected from at least one of carbonyl iron powder, hydroxy iron powder, hydroxy nickel powder, hydroxy cobalt powder, or graphite powder.

[0013] In the above-mentioned process, the first and second absorbing agents can be independently selected from at least one of carbonyl iron powder, hydroxyl iron powder, hydroxyl nickel powder, hydroxyl cobalt powder or graphite powder, which can enable the absorbing material to have good absorbing performance.

[0014] In conjunction with the first aspect, in one possible embodiment, both the first raw material and the second raw material include methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber, sericite powder, vulcanizing agent, and polyester polyol.

[0015] Optionally, the first and second raw materials may also include silane coupling agents and retarders.

[0016] In the above-mentioned process, the first raw material forming the first absorbing structure and the second raw material forming the second absorbing structure are methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber, sericite powder, vulcanizing agent and polyester polyol, as well as silane coupling agent and retarder, which enable the absorbing material to have good absorbing performance.

[0017] In conjunction with the first aspect, in one possible embodiment, the first raw material, by percentage, comprises: 50-60% carbonyl iron powder, 10-20% methyl vinyl silicone oil, 10-15% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 15-20% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol;

[0018] The second raw material, by percentage, includes: 70-80% carbonyl iron powder, 5-10% methyl vinyl silicone oil, 5-10% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 5-10% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol.

[0019] In the above-mentioned implementation process, a first absorbing structure and substrate are prepared using a first raw material comprising 50-60% carbonyl iron powder, 10-20% methyl vinyl silicone oil, 10-15% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 15-20% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol. A second absorbing structure, filled in the gaps of the first absorbing structure, is prepared using a second raw material comprising 70-80% carbonyl iron powder, 5-10% methyl vinyl silicone oil, 5-10% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 5-10% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol. This enables the absorbing material to have the characteristics of a large effective absorption bandwidth and low reflection loss.

[0020] In conjunction with the first aspect, in one possible embodiment, the shape of the plurality of first absorbing structures is selected from at least one of cylindrical, triangular prism, quadrangular prism, pentagonal prism or hexagonal prism.

[0021] In conjunction with the first aspect, in one possible embodiment, the second absorbing structure is a continuum.

[0022] Optionally, the thickness of the substrate is 0.2-0.5mm, the thickness of the first absorbing structure is 0.5-0.8mm, and the width of the first absorbing structure is 10-20mm.

[0023] Optionally, multiple arrays of first absorbing structures are disposed on the substrate.

[0024] In the above implementation process, the shape of the first absorbing structure can be cylindrical, triangular prism, square prism, pentagonal prism or hexagonal prism, and the second absorbing structure is a continuous body filling the gap of the first absorbing structure. The absorbing performance of the second material is better than that of the first material, which can increase the effective absorption bandwidth of the absorbing material and reduce the reflection loss of the absorbing material.

[0025] In a second aspect, this application provides a method for preparing the microwave absorbing material provided in the first aspect, comprising: obtaining an intermediate structure of the first microwave absorbing structure spaced apart on a substrate; placing the intermediate structure in a first mold such that the edge of the substrate is attached to the inner wall of the first mold away from the demolding opening; filling the first mold with a slurry of a second raw material forming a second microwave absorbing structure; degassing, drying, and vulcanizing the slurry of the second raw material to form a second microwave absorbing structure filling the gaps in the first microwave absorbing structure, thereby obtaining the microwave absorbing material.

[0026] In the above-described process, when preparing the microwave absorbing material provided in the first aspect, the intermediate structure of the first microwave absorbing structure, which is spaced apart on the substrate, is placed in the first mold, and the edge of the substrate is made to fit against the inner wall of the first mold away from the demolding opening. Then, a slurry of the second raw material that forms the second microwave absorbing structure is filled into the first mold. The slurry of the second raw material can fill the gaps of the first microwave absorbing structure and does not flow to the circumferential edge of the substrate. After the filled slurry of the second raw material is degassed, dried, and vulcanized, a second microwave absorbing structure that fills the gaps of the first microwave absorbing structure can be obtained, thus obtaining the microwave absorbing material provided in the first aspect. Through the above method, an integrally formed second microwave absorbing structure can be obtained.

[0027] In conjunction with the second aspect, in one possible embodiment, the method for preparing the intermediate structure includes:

[0028] The slurry of the first raw material is filled into the second mold, and the slurry of the second raw material is degassed, dried, vulcanized, and then demolded. The second mold has a top plate and multiple spaced columns that protrude from the top plate. The cavities inside the columns are connected to the cavities inside the top plate.

[0029] In the above-described process, since the first mold includes a top plate and multiple spaced-apart columns protruding from the top plate, with the cavities inside the columns communicating with the cavities inside the top plate, the slurry of the first raw material is filled into the second mold. This slurry fills the columns and the top plate. After degassing, drying, and vulcanizing the slurry, a secondary structure with multiple first absorbing structures spaced apart on the substrate is obtained after demolding. Through this preparation method, a secondary structure integrally formed with the substrate and the first absorbing structures can be obtained, facilitating the subsequent filling of the gaps in the first absorbing structures with the slurry of the second raw material to obtain the absorbing material provided in the first aspect.

[0030] In a third aspect, an example of this application provides a mold for preparing the microwave absorbing material provided in the first aspect. The mold includes a first mold and a second mold. The first mold has a first chamber and a first demolding opening communicating with the first chamber. The second mold includes a top plate and a plurality of spaced-apart pillars protruding from the top plate. The chambers inside the pillars communicate with the second chamber inside the top plate. The side of the top plate away from the pillars has a second demolding opening communicating with the second chamber. The pillars are used to form a first microwave absorbing structure, and the top plate is used to form a substrate. The circumferential dimension of the first chamber away from the first demolding opening is the same as the circumferential dimension of the second chamber, so that the substrate demolded from the second chamber fits into the inner wall of the first chamber to fill the gaps in the first microwave absorbing structure and form a second microwave absorbing structure.

[0031] In the above implementation process, the second mold includes a top plate and a plurality of spaced-apart columns protruding from the top plate. The cavity inside the column is connected to the second cavity inside the top plate. The side of the top plate away from the column has a second demolding port connected to the second cavity. Therefore, after the slurry of the first raw material is poured into the second mold, the slurry of the first raw material will fill each column and the top plate. After the slurry in the second mold is processed and demolded from the second demolding port, a middle structure with a plurality of first wave-absorbing structures spaced apart on the substrate can be obtained. Since the circumferential dimension of the first chamber away from the first demolding port is the same as that of the second chamber, the circumferential dimension of the substrate after demolding is the same as that of the first chamber away from the first demolding port. Therefore, when the intermediate structure is placed in the first mold, the edge of the substrate will fit against the inner wall of the first chamber. After the slurry of the second microwave absorbing structure is poured into the first chamber, the slurry will fill the gap of the first microwave absorbing structure and will not flow to the circumferential edge of the substrate. This makes it easier to obtain the microwave absorbing material provided in the first aspect after the slurry in the first mold is processed and demolded.

[0032] By utilizing the combination of the first mold and the second mold, the material composition distribution within the substrate, the first absorbing structure, and the second absorbing structure can be made more uniform, and the contact between the substrate and the first absorbing structure, as well as between the first absorbing structure and the second absorbing structure, can be made closer, thereby increasing the effective absorption bandwidth of the absorbing material and reducing reflection loss. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0034] Figure 1 A schematic diagram of the structure of the microwave absorbing material provided as an example in this application;

[0035] Figure 2 A schematic diagram of the intermediate structure provided as an example in this application;

[0036] Figure 3 A schematic diagram of the mold provided as an example in this application;

[0037] Figure 4 A schematic diagram illustrating the connection between the intermediate structure and the first mold, provided as an example in this application;

[0038] Figure 5 Test curves for S1-S4 and S9-S10 provided for the test examples of this application;

[0039] Figure 6 The test curves for S5-S8 provided for the test examples of this application.

[0040] Icons: 100 - Absorbing material; 101 - Substrate; 102 - First absorbing structure; 103 - Second absorbing structure; 104 - Intermediate structure; L1 - Gap; 200 - Mold; 201 - First mold; 2011 - First demolding port; 202 - Second mold; 2021 - Top plate; 2022 - Column; 2023 - Second demolding port. Detailed Implementation

[0041] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0042] This application provides an absorbing material, its preparation method, and a mold to increase the effective absorption bandwidth of the absorbing material, reduce its reflection loss, and improve the preparation efficiency and quality of the absorbing material.

[0043] Please combine Figure 1 and Figure 2 The absorbing material 100 includes a substrate 101 and a plurality of first absorbing structures 102 spaced apart on the substrate 101; the plurality of first absorbing structures 102 are spaced apart to form gaps L1, and the gaps L1 are filled with second absorbing structures 103.

[0044] The first absorbing structure 102 and the substrate 101 are both formed from a first material, and the second absorbing structure 103 is formed from a second material, wherein the absorbing performance of the second material is better than that of the first material.

[0045] Understandably, the main focus of absorption performance is on minimizing reflection loss and effective absorption bandwidth.

[0046] The microwave absorbing material 100 will be described in further detail below in conjunction with its preparation method.

[0047] This application provides an example of a method for preparing a microwave absorbing material 100, comprising:

[0048] S1. Obtain the intermediate structure 104 of the first absorbing structure 102 spaced apart on the substrate 101. The raw material for forming the first absorbing structure 102 is the same as the raw material for forming the substrate 101.

[0049] The structural diagram of intermediate structure 104 is as follows: Figure 2 As shown.

[0050] This application does not limit how the intermediate structure 104 is prepared. In one possible embodiment, this application provides a mold 200, which includes a second mold 202 for preparing the intermediate structure 104.

[0051] Please see Figure 3 The second mold 202 includes a top plate 2021 and a plurality of spaced-apart pillars 2022 protruding from the top plate 2021. The cavities inside the pillars 2022 communicate with a second cavity inside the top plate 2021. The side of the top plate 2021 away from the pillars 2022 has a second demolding opening 2023 communicating with the second cavity. The pillars 2022 are used to form the first wave-absorbing structure 102, and the top plate 2021 is used to form the substrate 101.

[0052] When preparing the intermediate structure using the second mold 202, the slurry of the first raw material forming the first microwave absorbing structure 102 and the substrate 101 is injected into the second mold 202, so that the slurry of the first raw material fills the cavity of the column 2022 and the top plate 2021. Then, the slurry of the first raw material in the second mold 202 is degassed, dried and vulcanized. Then, the material in the cavity is taken out from the second demolding port 2023 to obtain the intermediate structure 104.

[0053] Using the second mold 202, the first formed intermediate structure 104 can be obtained.

[0054] This application does not limit the type of the first raw material. In one possible embodiment, the first raw material includes a first microwave absorbing agent.

[0055] For example, the first microwave absorbing agent is selected from at least one of carbonyl iron powder, hydroxy iron powder, hydroxy nickel powder, hydroxy cobalt powder, or graphite powder.

[0056] Furthermore, the first raw material may also include methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber, sericite powder, vulcanizing agent, polyester polyol, silane coupling agent and retarder.

[0057] For example, the vulcanizing agent can be selected from hydrogen-containing silicone oil.

[0058] For example, the delay agent may be selected from organosilicon inhibitors or alkynyl alcohol inhibitors.

[0059] Furthermore, the preparation method of the slurry of the first raw material may include: mixing the weighed first microwave absorbing agent, methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber and sericite powder from the first raw material, and then mixing them on a two-roll mill at a temperature of 30-50°C for 10 minutes. Then, a vulcanizing agent is added and mixed for 10 minutes, followed by the addition of a retarder and mixing for 10 minutes, and finally, polyester polyol is added and mixed for 10 minutes.

[0060] This application does not limit the shape of the substrate 101, and relevant personnel can make corresponding adjustments as needed.

[0061] For example, the substrate 101 can be a polygonal plate such as a triangle, quadrilateral or pentagon, or a streamlined plate such as a circle or ellipse.

[0062] This application does not limit the specific thickness of the substrate 101. In one possible embodiment, the thickness of the substrate 101 can be 0.2-0.5 mm.

[0063] For example, the thickness of the substrate 101 can be one of 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm or any combination thereof.

[0064] This application does not limit the specific shape of the first absorbing structure 102. In one possible embodiment, the shape of the plurality of first absorbing structures 102 is selected from at least one of cylindrical, triangular prism, quadrangular prism, pentagonal prism or hexagonal prism.

[0065] For example, the shapes of the plurality of first absorbing structures 102 are all selected from cylindrical shapes.

[0066] For example, a portion of the first absorbing structure 102 is selected from a cylindrical shape, and a portion of the first absorbing structure 102 is selected from a quadrangular prism shape.

[0067] Furthermore, the thickness of the first absorbing structure 102 can be 0.5-0.8 mm.

[0068] For example, the thickness of the first absorbing structure 102 can be one of 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm or any combination thereof.

[0069] Furthermore, the width of the first absorbing structure 102 can be 10-20mm.

[0070] For example, the width of the first absorbing structure 102 can be one of 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm or 20mm or any range between two of them.

[0071] Furthermore, the spacing between the multiple first absorbing structures 102 can be the same.

[0072] For example, the first absorbing structure 102 array is disposed on the substrate 101.

[0073] Alternatively, multiple first absorbing structures 102 are arranged at random intervals on the substrate 101.

[0074] The top plate 2021 is used to form the substrate 101. In one possible embodiment, when it is necessary to prepare a substrate 101 with a thickness of 0.2 mm, the thickness of the second chamber inside the top plate 2021 can be set to 0.2 mm.

[0075] The column 2022 is used to form the first microwave absorbing structure 102. In one possible embodiment, when it is necessary to prepare a cylindrical first microwave absorbing structure 102 with a thickness of 0.8 mm and a diameter of 10 mm, the cavity inside the column 2022 has a diameter of 10 mm and a thickness of 0.8 mm.

[0076] In one possible implementation, the column 2022 can be prismatic, with both ends of the prism connected to the sidewalls of the top plate 2021. That is, the width of the prism is the same as the width of the top plate 2021. By using the cooperation of the second mold 202 and the first mold 201, a second wave-absorbing structure 103 with a discontinuous structure can be prepared.

[0077] Furthermore, in order to facilitate the fabrication of the second absorbing structure 103 that fills the gap L1 of the first absorbing structure 102, the mold 200 provided in this application example also includes a first mold 201.

[0078] Please continue reading. Figure 3 The first mold 201 has a first chamber and a first demolding port 2011 communicating with the first chamber.

[0079] The circumferential dimension of the first chamber away from the first demolding opening 2011 is the same as the circumferential dimension of the second chamber in the top plate 2021 of the second mold 202 used for molding the substrate 101.

[0080] The method for preparing the microwave absorbing material 100 provided in this application also includes:

[0081] S2. The intermediate structure 104 is placed inside the first mold 201, so that the edge of the substrate 101 is attached to the inner wall of the first mold 201 away from the first demolding port 2011. A slurry of the second raw material to form the second microwave absorbing structure 103 is filled into the first mold 201. The slurry of the second raw material is degassed, dried, and vulcanized to form the second microwave absorbing structure 103 filling the gap L1 of the first microwave absorbing structure 102, thereby obtaining the microwave absorbing material 100.

[0082] The shape of the first mold 201 can be similar to that of the top plate 2021 so that the substrate 101 demolded from the top plate 2021 can be placed into the first mold 201 and fit against the inner wall of the first mold 201.

[0083] Please refer to the schematic diagram showing the intermediate structure 104 placed inside the first mold 201, with the circumferential outer wall of the substrate 101 fitting against the inner wall of the first mold 201. Figure 4 .

[0084] Furthermore, the second raw material forming the second microwave absorbing structure 103 includes a second microwave absorbing agent.

[0085] For example, the second absorber is selected from at least one of carbonyl iron powder, hydroxy iron powder, hydroxy nickel powder, hydroxy cobalt powder, or graphite powder.

[0086] Furthermore, the second raw material may also include methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber, sericite powder, vulcanizing agent, polyester polyol, silane coupling agent and retarder.

[0087] For example, the vulcanizing agent can be selected from hydrogen-containing silicone oil.

[0088] For example, the delay agent may be selected from organosilicon inhibitors or alkynyl alcohol inhibitors.

[0089] Furthermore, the preparation method of the slurry of the second raw material may include: mixing the weighed first microwave absorbing agent, methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber and sericite powder from the first raw material, and then mixing them on a two-roll mill at a temperature of 30-50°C for 10 minutes. Then, a vulcanizing agent is added and mixed for 10 minutes, followed by the addition of a retarder and mixing for 10 minutes, and finally, polyester polyol is added and mixed for 10 minutes.

[0090] This application does not limit the specific content of each component in the first and second raw materials. Those who are interested can make adjustments as needed, provided that the absorption performance of the second raw material is better than that of the first raw material.

[0091] In one possible embodiment, both the first and second microwave absorbers are selected from carbonyl iron powder with the same microwave absorption performance from the same manufacturer. In order to make the microwave absorption performance of the second raw material better than that of the first raw material, in one possible embodiment, the percentage content of the first microwave absorber in the first raw material is less than the percentage content of the second microwave absorber in the second raw material.

[0092] Although the first and second absorbing agents have the same absorbing performance, the second raw material has better absorbing performance than the first raw material because the content of the first absorbing agent in the first raw material is less than the content of the second absorbing agent in the second raw material.

[0093] For example, the first raw material may contain 50-60% carbonyl iron powder by percentage; the second raw material may contain 70-80% carbonyl iron powder by percentage.

[0094] For example, by percentage, the first raw material may include 50-60% carbonyl iron powder, 10-20% methyl vinyl silicone oil, 10-15% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 15-20% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol; by percentage, the second raw material includes: 70-80% carbonyl iron powder, 5-10% methyl vinyl silicone oil, 5-10% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 5-10% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol.

[0095] Alternatively, the first and second microwave absorbing agents may be selected from two materials with different microwave absorbing properties, and the percentage content of the first microwave absorbing agent in the first raw material and the percentage content of the second microwave absorbing agent in the second raw material may be the same.

[0096] The microwave absorbing material 100 of this application will be further described in detail below with reference to the embodiments.

[0097] Example 1

[0098] Example 1 provides a microwave absorbing material, utilizing... Figure 3 The mold 200 shown is prepared. The first chamber inside the first mold 201 has dimensions of 350mm x 350mm x 1mm; in the second mold 202, the second chamber inside the top plate 2021 has dimensions of 350mm x 350mm x 0.2mm, and the cylindrical column 2022 has a diameter of 20mm and a thickness of 0.8mm.

[0099] Preparation methods include:

[0100] (1) Preparation of the slurry for the first raw material: Carbonyl iron powder (340 parts), methyl vinyl silicone oil (101.7 parts), dimethyl silicone oil (69.6 parts), methyl vinyl silicone rubber (8.8 parts), silane coupling agent (0.4 parts), sericite powder (115 parts), and other raw materials were weighed and mixed, and stirred into a relatively uniform state. The mixed raw materials were kneaded on a two-roll mill at 30°C for 10 minutes, then the vulcanizing agent hydrogen-containing silicone oil (4.36 parts) was added and kneaded for 10 minutes, then the retardant agent (0.13 parts) was added and kneaded for 10 minutes, and finally the polyester polyol (2.5 parts) was added and kneaded for 10 minutes. The first raw material in Example 1 is denoted as raw material A, and the specific components and contents are shown in Table 1.

[0101] (2) Preparation of the slurry for the second raw material: Carbonyl iron powder (450.4 parts), methyl vinyl silicone oil (49.5 parts), dimethyl silicone oil (34.6 parts), methyl vinyl silicone rubber (6.2 parts), silane coupling agent (0.3 parts), sericite powder (38 parts), and other raw materials were weighed and mixed, and stirred until a relatively uniform state was achieved. The mixed raw materials were then kneaded on a two-roll mill at 30°C for 10 minutes. Then, a vulcanizing agent (hydrogen-containing silicone oil, 2.66 parts) was added and kneaded for another 10 minutes. Next, a delaying agent (0.12 parts) was added and kneaded for another 10 minutes. Finally, polyester polyol (1.8 parts) was added and kneaded for another 10 minutes. The second raw material in Example 1 is designated as raw material B, and its specific components and contents are shown in Table 1.

[0102] (3) Preparation of intermediate structure 104: Pour the slurry of the first raw material in step (1) into the second mold 202, so that the slurry of the first raw material is evenly distributed in the column 2022 and the top plate 2021. Then degas in a vacuum degassing machine for 30 minutes, and then place the second mold 202 in an oven and bake at 140°C for 10 minutes for vulcanization. Demold from the second demolding port 2023 to obtain intermediate structure 104.

[0103] (4) Preparation of the second absorbing structure 103: The intermediate structure 104 obtained in step (3) is placed in the first mold 201, so that the circumferential edge of the substrate 101 is attached to the inner wall of the first mold 201. The slurry of the second raw material in step (2) is poured into the first mold 201, so that the slurry of the second raw material is evenly distributed in the gap L1 of the first absorbing structure 102. Then, the material is degassed in a vacuum degassing machine for 30 minutes. After that, the first mold 201 is placed in an oven and baked at 140°C for 10 minutes for vulcanization. The material is then demolded from the first demolding port 2011 to obtain the second absorbing structure 103 filling the gap L1 of the first absorbing structure 102, and the absorbing material 100 is obtained. The absorbing material 100 provided in Example 1 is denoted as S3.

[0104] Example 2

[0105] Example 2 provides a microwave absorbing material 100, which differs from Example 1 in that:

[0106] In step (1), the slurry of the first raw material includes: first carbonyl iron powder (113.30 parts), methyl vinyl silicone oil crosslinking agent (33.90 parts), dimethyl silicone oil (23.20 parts), methyl vinyl silicone rubber (2.93 parts), silane coupling agent (0.13 parts), sericite powder (38.33 parts), vulcanizing agent hydrogen-containing silicone oil (1.45 parts), retarder (0.04 parts), and polyester polyol (0.83 parts). In Example 2, the first raw material is denoted as raw material C, and the components and contents are shown in Table 1.

[0107] In step (2), the slurry of the second raw material includes: second carbonyl iron powder (300.27 parts), methyl vinyl silicone oil crosslinking agent (33 parts), dimethyl silicone oil (13.07 parts), methyl vinyl silicone rubber (4.13 parts), silane coupling agent (0.2 parts), sericite powder (25.33 parts), vulcanizing agent hydrogen-containing silicone oil (1.77 parts), retarder (0.08 parts), and polyester polyol (1.2 parts). In Example 2, the second raw material is designated as raw material D; please refer to Table 1 for its components and content.

[0108] Please refer to Table 1 for the composition and content of the second raw material in Example 2. The microwave absorbing material 100 provided in Example 2 is designated as S7.

[0109] Comparative Example 1

[0110] Comparative Example 1 provides a microwave absorbing material, which differs from Example 1 in that:

[0111] In step (3), intermediate structure 104 is prepared using raw material B obtained in step (2).

[0112] In step (4), the second absorbing structure 103 is prepared using the raw material A obtained in step (1). That is, in the absorbing material provided by Comparative Example 1, the absorbing performance of the first absorbing structure 102 is greater than that of the second absorbing structure 103. The absorbing material provided by Comparative Example 1 is denoted as S9.

[0113] Comparative Example 2

[0114] The difference between Comparative Example 2 and Example 1 is that the intermediate structure 104 is not prepared. The raw material A obtained in step (1) is poured into the second mold 202. The intermediate structure 104 is not placed inside the second mold 202, and a flat plate-shaped microwave absorbing material with a size of 350mm x 350mm x 1mm is prepared. The microwave absorbing material provided in Comparative Example 2 is denoted as S1.

[0115] Comparative Example 3

[0116] The difference between Comparative Example 3 and Example 1 is that the intermediate structure 104 is not prepared. The raw material B obtained in step (2) is poured into the second mold 202. The intermediate structure 104 is not placed inside the second mold 202, and a flat plate-shaped microwave absorbing material with a size of 350mm x 350mm x 1mm is prepared. The microwave absorbing material provided in Comparative Example 3 is denoted as S2.

[0117] Comparative Example 4

[0118] The difference between Comparative Example 4 and Example 1 is that the intermediate structure 104 is not prepared. The raw material B obtained in step (2) and the raw material A obtained in step (1) are mixed evenly and poured into the second mold 202. The intermediate structure 104 is not placed inside the second mold 202, and a flat plate-shaped microwave absorbing material with a size of 350mm x 350mm x 1mm is obtained. The microwave absorbing material provided in Comparative Example 4 is denoted as S4.

[0119] Comparative Example 5

[0120] The difference between Comparative Example 5 and Example 2 is that the intermediate structure 104 is not prepared. The raw material C obtained in step (1) is poured into the second mold 202. The intermediate structure 104 is not placed inside the second mold 202, and a flat microwave absorbing material with a size of 350mm x 350mm x 1mm is obtained. The microwave absorbing material provided in Comparative Example 5 is denoted as S5.

[0121] Comparative Example 6

[0122] The difference between Comparative Example 6 and Example 2 is that the intermediate structure 104 is not prepared. The raw material D obtained in step (2) is poured into the second mold 202. The intermediate structure 104 is not placed inside the second mold 202, and a flat microwave absorbing material with a size of 350mm x 350mm x 1mm is prepared. The microwave absorbing material provided by Comparative Example 6 is denoted as S6.

[0123] Comparative Example 7

[0124] The difference between Comparative Example 7 and Example 2 is that the intermediate structure 104 is not prepared. The raw material D obtained in step (2) and the raw material C obtained in step (1) are mixed evenly and poured into the second mold 202. The intermediate structure 104 is not placed inside the second mold 202, and a flat plate-shaped microwave absorbing material with a size of 350mm x 350mm x 1mm is obtained. The microwave absorbing material provided in Comparative Example 7 is denoted as S8.

[0125] Table 1

[0126] microwave absorber 340 450.4 113.30 300.27 Methyl vinyl silicone oil 101.7 49.5 33.90 33 Dimethyl silicone oil 69.6 34.6 23.20 13.07 Methyl vinyl silicone rubber 8.8 6.2 2.93 1.13 Silane coupling agents 0.4 0.3 0.13 0.2 sericite powder 115 38 38.33 25.33 Vulcanizing agent containing hydrogen silicone oil 4.36 2.66 1.45 1.77 Delay agent 0.13 0.12 0.04 0.08 Polyester polyols 2.5 1.8 0.83 1.2 Percentage of microwave absorber 52.89％ 77.18％ 52.92％ 79.22％

[0127] Test case

[0128] The reflection loss of the absorbing materials provided in Examples 1-2 and Comparative Examples 1-7 was tested using the bow-shaped method. The test curves for S1-S4 and S9 are shown below. Figure 5 As shown, the test curves for S5-S8 are as follows: Figure 6 As shown in Table 2, the absorption performance statistics of S1-S9 are presented.

[0129] Table 2

[0130]

[0131]

[0132] Results analysis:

[0133] Combining Examples 1-2 and Comparative Examples 1-7, it can be seen that the absorbing material provided in this application, consisting of a substrate prepared from a first raw material, a plurality of first absorbing structures 102 spaced apart on the substrate 101, and a second absorbing structure 103 formed from a second raw material with a absorbing performance greater than that of the first raw material and filling the gap L1 of the first absorbing structure 102, can have a large effective absorption bandwidth while having low reflection loss.

[0134] As can be seen from Example 1 and Comparative Example 1, the absorbing material 100, which consists of a substrate 101 prepared from a first raw material, a plurality of first absorbing structures 102 spaced apart on the substrate 101, and a second absorbing structure 103 formed from a second raw material with better absorbing performance than the first raw material and filled in the gap L1 of the first absorbing structure 102, has the effect of increasing the effective absorption bandwidth of the absorbing material 100 and reducing the reflection loss of the absorbing material 100.

[0135] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A microwave absorbing material, characterized in that, The absorbing material includes a substrate and a plurality of first absorbing structures spaced apart on the substrate; the plurality of first absorbing structures are spaced apart to form gaps, and the gaps are filled with second absorbing structures; the first absorbing structures and the substrate are both formed from a first raw material, the second absorbing structures are formed from a second raw material, and the absorbing performance of the second raw material is better than that of the first raw material, the absorbing performance including the lowest reflection loss and the effective absorption bandwidth.

2. The microwave absorbing material according to claim 1, characterized in that, The first raw material contains a first microwave absorbing agent, and the second raw material contains a second microwave absorbing agent; The first absorbing agent and the second absorbing agent have the same absorbing performance, and the percentage content of the first absorbing agent in the first raw material is less than the percentage content of the second absorbing agent in the second raw material.

3. The microwave absorbing material according to claim 2, characterized in that, Both the first and second microwave absorbing agents are independently selected from at least one of carbonyl iron powder, hydroxy iron powder, hydroxy nickel powder, hydroxy cobalt powder, or graphite powder.

4. The microwave absorbing material according to claim 3, characterized in that, Both the first raw material and the second raw material include methyl vinyl silicone oil, dimethyl silicone oil, methyl vinyl silicone rubber, sericite powder, vulcanizing agent and polyester polyol; And / or, the first raw material and the second raw material further include a silane coupling agent and a retarder.

5. The microwave absorbing material according to claim 4, characterized in that, The first raw material, by percentage, includes: 50-60% carbonyl iron powder, 10-20% methyl vinyl silicone oil, 10-15% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 15-20% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol. The second raw material, by percentage, includes: 70-80% carbonyl iron powder, 5-10% methyl vinyl silicone oil, 5-10% dimethyl silicone oil, 1-5% methyl vinyl silicone rubber, 5-10% sericite powder, 0.5-1% vulcanizing agent, and 0.1-0.5% polyester polyol.

6. The microwave absorbing material according to claim 1, characterized in that, The shape of the plurality of the first absorbing structures is selected from at least one of cylindrical, triangular prism, quadrangular prism, pentagonal prism or hexagonal prism.

7. The microwave absorbing material according to claim 6, characterized in that, The second absorbing structure is a continuum.

8. The microwave absorbing material according to claim 7, characterized in that, The substrate has a thickness of 0.2-0.5 mm, the first absorbing structure has a thickness of 0.5-0.8 mm, and the first absorbing structure has a width of 10-20 mm.

9. The microwave absorbing material according to claim 7, characterized in that, Multiple arrays of the first absorbing structures are disposed on the substrate.

10. A method for preparing a microwave absorbing material according to any one of claims 1-9, characterized in that, include: An intermediate structure is obtained by spaced-apart from the first absorbing structure on the substrate. The intermediate structure is placed in a first mold, such that the edge of the substrate is attached to the inner wall of the first mold away from the demolding opening. A slurry of the second raw material for forming the second absorbing structure is filled into the first mold. The slurry of the second raw material is degassed, dried, and vulcanized to form the second absorbing structure that fills the gaps between the first absorbing structures, thereby obtaining the absorbing material.

11. The preparation method according to claim 10, characterized in that, The method for preparing the intermediate structure includes: The slurry of the first raw material of the intermediate structure is filled into the second mold, and the slurry of the first raw material is degassed, dried, vulcanized, and then demolded; the second mold has a top plate and a plurality of spaced columns that protrude from the top plate, and the cavities inside the columns are connected to the cavities inside the top plate.

12. A mold for preparing the microwave absorbing material according to any one of claims 1-9, characterized in that, The mold includes a first mold and a second mold, wherein the first mold has a first chamber and a first demolding port communicating with the first chamber; The second mold includes a top plate and a plurality of spaced-apart columns protruding from the top plate. The cavities inside the columns communicate with a second cavity inside the top plate. The top plate has a second demolding opening on the side away from the columns, which communicates with the second cavity. The columns are used to form the first wave-absorbing structure, and the top plate is used to form the substrate. The circumferential dimension of the first chamber away from the first demolding opening is the same as the circumferential dimension of the second chamber, so that the substrate demolded from the second chamber fits the inner wall of the first chamber, thereby filling the gap of the first absorbing structure to form the second absorbing structure.

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