WO2020114091A1

WO2020114091A1 - Electromagnetic wave absorbing material and method for preparing same

Info

Publication number: WO2020114091A1
Application number: PCT/CN2019/111278
Authority: WO
Inventors: 刘若鹏; 赵治亚; 王侃; 王佳佳; 刘志礼; 黄赤
Original assignee: 洛阳尖端技术研究院; 洛阳尖端装备技术有限公司
Priority date: 2018-12-06
Filing date: 2019-10-15
Publication date: 2020-06-11
Also published as: CN111286097A

Abstract

The present invention provides an electromagnetic wave absorbing material and a method for preparing the same. The electromagnetic wave absorbing material sequentially comprises, in an incident direction of electromagnetic waves, an electromagnetic wave matching layer, a low-frequency absorption layer, and a high-frequency absorption layer. The electromagnetic wave matching layer, the low-frequency absorption layer, and the high-frequency absorption layer are sequentially disposed in the incident direction of electromagnetic waves, such that the electromagnetic waves propagated in the air encounter the electromagnetic wave matching layer first. Since the electromagnetic wave matching layer has an impedance matching feature similar to that of the air, reflection of the electromagnetic waves can be effectively reduced, such that more electromagnetic waves can enter the interior of the electromagnetic wave absorbing material, low-frequency wave bands thereof can be gradually absorbed by the low-frequency absorption layer, and high-frequency wave bands thereof can then be absorbed by the high-frequency absorption layer. The invention thus achieves efficient absorption of broadband wave bands from low to high frequencies.

Description

Wave-absorbing material and preparation method thereof

Technical field

The invention relates to the field of electromagnetic wave absorbing materials, in particular, to a wave absorbing material and a preparation method thereof.

Background technique

Materials with good wave-absorbing properties must have two basic conditions: (1) The incident electromagnetic waves must enter the material as much as possible without being reflected on the front surface, that is, have the impedance matching characteristics of the material; (2) Enter the material The electromagnetic waves can be quickly absorbed and attenuated, that is, the material must also have the loss characteristics of electromagnetic waves.

For a single component absorber, the two requirements of impedance matching and loss characteristics often conflict with each other. At present, the absorbing materials are developing in the direction of "thin, wide, light and strong". Single-layer absorbing materials generally have the problem of narrow frequency bands, which cannot meet the requirements of stealth technology for light-weight and wide-band coatings. In addition, it is difficult to achieve the impedance matching of the absorbing material by relying only on a single dielectric loss or magnetic loss material.

technical problem

The use of a multi-layer structure design to make incident electromagnetic waves enter as much of the absorbing coating as possible and to be absorbed by losses has become a popular research direction for absorbing materials. At present, there are few reports on the design of multi-layer structure of absorbing materials, but there are defects such as complicated preparation process and poor absorbing properties (including absorption intensity and absorption bandwidth).

Technical solution

The main purpose of the present invention is to provide a wave-absorbing material and a preparation method thereof to improve the wave-absorbing performance of the wave-absorbing material in the prior art.

In order to achieve the above object, according to an aspect of the present invention, there is provided a wave absorbing material, the wave absorbing material includes, in order along the incident direction of electromagnetic waves: an electromagnetic wave matching layer, a low frequency absorption layer, and a high frequency absorption layer.

Further, the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer respectively contain different absorbers, and the absorber in the electromagnetic wave matching layer is selected from any one or more of TiO ₂ , SiO ₂ and SiC; preferably, The absorber in the low-frequency absorption layer is selected from carbonyl iron powder; preferably, the absorber in the high-frequency absorption layer is selected from oxides of one or more magnetic metals; more preferably, the magnetic metal is selected from Fe, Co, or Ni .

Further, the electromagnetic wave matching layer, the low-frequency absorption layer, and the high-frequency absorption layer also include a binder and an optional coupling agent, an optional vulcanizing agent, and an optional antioxidant.

Further, the electromagnetic wave matching layer, the low-frequency absorption layer, and the high-frequency absorption layer also include a binder, a coupling agent, a vulcanizing agent, and an antioxidant; preferably, in the electromagnetic wave matching layer, the binder, the absorption agent, and the coupling The weight ratio of the agent, vulcanizing agent and antioxidant is 100: (67-150): (3-5): (2-4): (1-2); preferably, in the low-frequency absorption layer, the binder, The weight ratio of absorber, coupling agent, vulcanizing agent and antioxidant is 100: (500-850): (3-5): (2-4): (1-2); preferably, the high-frequency absorption layer Among them, the weight ratio of binder, absorbent, coupling agent, vulcanizing agent and antioxidant is 100: (200-300): (3-5): (2-4): (1-2).

Further, the binders of the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer are each independently selected from one or more of neoprene rubber, urethane rubber and silicone rubber; preferably, the electromagnetic wave matching layer, the low-frequency absorption The coupling agent of the layer and the high-frequency absorption layer are each independently selected from one or two of titanate and vinyl tri-(2-methoxyethoxy) silane; preferably, the electromagnetic wave matching layer, low frequency The vulcanizing agent of the absorption layer and the high-frequency absorption layer are each independently selected from one or two of bis-pentapentyl sulfide and zinc oxide; preferably, the electromagnetic wave matching layer, the low-frequency absorption layer, and the antioxidant of the high-frequency absorption layer Each is independently selected from one or both of 4-methyl-6-tert-butylphenol and N-phenyl-N-cyclohexyl-p-phenylenediamine.

Further, the thickness of the electromagnetic wave matching layer is 0.15 to 0.25 mm; preferably, the thickness of the low-frequency absorption layer is 0.65 to 0.75 mm; preferably, the thickness of the high-frequency absorption layer is 0.25 to 0.35 mm.

In order to achieve the above object, according to an aspect of the present invention, there is provided a method for preparing a wave absorbing material, the preparation method includes: providing three types of wave absorbing plates, the three types of wave absorbing plates are electromagnetic wave matching plates, low frequency absorbing plates and High frequency absorbing sheet; three kinds of wave absorbing sheets are stacked in this order in order of electromagnetic wave matching sheet, low frequency absorbing sheet and high frequency absorbing sheet to obtain a wave absorbing material.

Further, the step of providing three kinds of absorbers includes using an absorber selected from any one or more of TiO ₂ , SiO ₂ , and SiC as an electromagnetic wave matching sheet; preferably, the absorber is The absorbing sheet of carbonyl iron powder is used as a low-frequency absorbing sheet; preferably, the absorbing sheet using an oxide selected from oxides of one or more magnetic metals is used as a high-frequency absorbing sheet; more preferably, the magnetic metal is selected from Fe, Co or Ni.

Further, the step of providing three kinds of wave-absorbing plates further includes: a step of preparing each type of wave-absorbing plate separately by using a binder, a coupling agent, a vulcanizing agent, an antioxidant and an absorbent; preferably, preparing each The steps of a kind of absorber include: S1, pre-mixing the absorber, coupling agent and antioxidant to obtain a pre-mix; S2, mixing the pre-mix with the binder to obtain a mixed film; S3 , Adding vulcanizing agent to the mixed film for refining to obtain each kind of wave-absorbing plate.

Further, in the step of preparing the electromagnetic wave matching sheet, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (67-150): (3-5): (2-4 ): (1-2); preferably, in the step of preparing the low-frequency absorption sheet, the weight ratio of the binder, absorbent, coupling agent, vulcanizing agent and antioxidant is 100: (500-850): (3 -5): (2-4): (1-2); preferably, in the step of preparing the high-frequency absorption sheet, the weight ratio of the binder, absorbent, coupling agent, vulcanizing agent and antioxidant is 100 : (200-300): (3-5): (2-4): (1-2).

Further, in the steps of preparing the electromagnetic wave matching sheet, the low-frequency absorption sheet, and the high-frequency absorption sheet, the binders used are independently selected from one or more of neoprene rubber, polyurethane rubber, and silicone rubber; preferably Ground, the coupling agent used is independently selected from one or two of titanate and vinyl tri-(2-methoxyethoxy) silane; preferably, the vulcanizing agent used is independently Selected from one or both of bis-pentasulfide and zinc oxide; preferably, the antioxidants used are each independently selected from 4-methyl-6-tert-butylphenol and N-phenyl- One or two of N-cyclohexyl-p-phenylenediamine.

Further, the thickness of the electromagnetic wave matching sheet is 0.15 to 0.25 mm; preferably, the thickness of the low-frequency absorption sheet is 0.65 to 0.75 mm; preferably, the thickness of the high-frequency absorption sheet is 0.25 to 0.35 mm.

Further, after step S1 and before step S2, the step of preparing each type of absorber further includes the step of preliminary smelting the adhesive into a sheet-shaped adhesive. In step S2, the adhesive is adhered in the form of a sheet The form of the binder is mixed with the premix. Preferably, after step S2 and before step S3, the step of preparing each absorber further includes the step of cooling the mixed film; more preferably, Cool to 20~30℃.

Beneficial effect

By applying the technical solution of the present invention, by sequentially placing an electromagnetic wave matching layer, a low frequency absorbing layer and a high frequency absorbing layer along the incident direction of the electromagnetic wave, when the electromagnetic wave propagates in the air, it first encounters the electromagnetic wave matching layer, due to the impedance matching of the electromagnetic wave matching layer The characteristics are similar to air, which can effectively reduce the reflection of electromagnetic waves, so that the electromagnetic waves enter the interior of the absorbing material relatively more, and are gradually absorbed by the low-frequency absorption layer in the low-frequency band, and then absorbed by the high-frequency absorption layer in the high-frequency band, thereby achieving from low frequency to Efficient absorption of high-frequency broadband bands.

Embodiments of the invention

It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other if there is no conflict. The present invention will be described in detail below in conjunction with embodiments.

In order to further improve the wave absorbing performance of the multilayer wave absorbing material in the prior art, in a typical embodiment of the present application, a wave absorbing material is provided. The wave absorbing material includes, in order along the incident direction of electromagnetic waves: electromagnetic waves Matching layer, low-frequency absorption layer (band width is between 2~8 GHz) and high-frequency absorption layer (band width is between 12 ~ 18 GHz).

According to the defects existing in the existing multi-layer wave absorbing material, this application provides electromagnetic wave matching layer, low frequency absorption layer and high frequency absorption layer in order along the incident direction of the electromagnetic wave, so that when the electromagnetic wave propagates in the air, it first encounters the electromagnetic wave The matching layer, because the impedance matching characteristics of the electromagnetic wave matching layer are similar to air, can effectively reduce the reflection of the electromagnetic wave, so that the electromagnetic wave enters the interior of the absorbing material relatively more, and is gradually absorbed by the low frequency absorption layer.The low frequency band is then absorbed by the high frequency absorption layer Absorb the high-frequency band, so as to realize the high-efficiency absorption of the broadband band from low frequency to high frequency.

In the above-mentioned absorbing material, the electromagnetic wave matching layer, the low-frequency absorbing layer and the high-frequency absorbing layer respectively contain different absorbents, and any absorbent capable of realizing the functions of the above layers is suitable for this application. In a preferred embodiment of the present application, the absorber in the electromagnetic wave matching layer is selected from any one or more of TiO ₂ , SiO ₂ , and SiC; preferably, the absorber in the low-frequency absorption layer is selected from iron carbonyl Powder; preferably, the absorber in the high-frequency absorption layer is selected from oxides of one or more magnetic metals; more preferably, the magnetic metal is selected from Fe, Co, or Ni.

Compared with the prior art where most of the carbonyl iron powder is used as the absorber to form a multi-layer wave absorbing material, the above wave absorbing material of the present application optimizes the type of the wave absorbing agent of each layer by combining the process of electromagnetic waves entering the wave absorbing material It improves the balance between permeability and dielectric constant, and also solves the problem of the contradiction between impedance matching characteristics and attenuation characteristics, thereby improving the electromagnetic wave absorption performance of the absorbing material.

Among them, TiO ₂ , SiO ₂ , SiC, especially nano-titanium dioxide, the dielectric constant is relatively close to the magnetic permeability, using it to prepare an electromagnetic wave matching layer, reducing the reflection at the interface, so that the electromagnetic wave can enter the absorption wave as much as possible Inside the material, compared with the existing wave absorbing material, the reflectivity of the surface is greatly reduced, the impedance matching of the material is optimized, and the wave absorbing performance is improved. In the low-frequency absorption layer, carbonyl iron powder is used as the absorber, which fully utilizes the excellent microwave loss performance of the carbonyl iron powder, and its microwave loss performance is greatly improved compared with the titanium dioxide absorbing material. Since the microwave loss performance of carbonyl iron powder is mainly reflected in the low-frequency region, the introduction of high-frequency absorbers such as ferric oxide, nickel oxide, or cobalt oxide further improves the high-frequency absorption characteristics of the material. A variety of loss mechanisms work together to make the material absorb Wave performance has been greatly improved.

In the above-mentioned absorbing material, the electromagnetic wave matching layer, the low-frequency absorbing layer and the high-frequency absorbing layer may include other raw materials used for molding in addition to the absorber. For example, the binder is not only used to bond and form the absorbent, but also has heat resistance and weather resistance, so that the absorbent material can still maintain good performance in complex environments.

In order to further make the binder and the absorbent have a good binding effect, a coupling agent and/or a coupling agent can be included to improve the interface between the absorbent and the binder, and the antioxidant can delay Or inhibit the oxidation process of the binder, thereby preventing the aging of the binder and extending its service life. Similarly, in order to further improve the overall performance of the absorbing material, it is preferable to further contain a vulcanizing agent, which reduces the plasticity of the binder and increases the elasticity and strength.

When the above components are included at the same time, it is conducive to the synergy between the various components, which can not only greatly improve the impedance matching characteristics of the absorbing material, but also provide a variety of absorbing loss mechanisms. A variety of mechanisms work together to make the absorbing material absorb waves The intensity and effective absorption bandwidth are also greatly improved.

In a preferred embodiment of the present application, the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer all include a binder, an absorbent, a coupling agent, a vulcanizing agent and an antioxidant, according to the functions of the above components , The dosage of each component can be optimized and configured to achieve the matching and optimization of the performance of each layer.

In a preferred embodiment of the present application, in the electromagnetic wave matching layer, the weight ratio of the binder, absorber, coupling agent, vulcanizing agent and antioxidant is 100: (67-150): (3-5) : (2-4): (1-2);

In a preferred embodiment of the present application, in the low-frequency absorption layer, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (500-850): (3-5) : (2-4): (1-2);

In a preferred embodiment of the present application, in the high-frequency absorption layer, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (200-300): (3-5 ): (2-4): (1-2).

In the above preferred embodiments, by optimizing the dosage ratio of each component, the same synergy between the components is achieved, which not only realizes the optimization of the functions of each layer, but also makes the three absorbing layers match each other, thereby solving the impedance matching performance The problem of contradiction with the attenuation characteristic improves the balance between the magnetic permeability and the dielectric constant, and improves the electromagnetic wave absorption performance of the wave absorbing material.

Among the above wave-absorbing materials, the specific types of binders, coupling agents, vulcanizing agents and antioxidants of the electromagnetic wave matching layer, low-frequency absorption layer and high-frequency absorption layer are not particularly limited, and any corresponding materials that can achieve the above functions Applies to this application. In the present application, it is preferred that the binders in the three wave-absorbing layers are independently selected from one or more of neoprene rubber, polyurethane rubber, and silicone rubber; preferably, the electromagnetic wave matching layer, the low-frequency absorption layer and The coupling agent of the high-frequency absorption layer is independently selected from one or more of titanate and vinyl tri-(2-methoxyethoxy) silane; preferably, the electromagnetic wave matching layer and the low-frequency absorption layer And the vulcanizing agent of the high-frequency absorbing layer are each independently selected from one or more of bis-pentasulfurizing agent and zinc oxide; preferably, the antioxidants of the electromagnetic wave matching layer, the low-frequency absorbing layer, and the high-frequency absorbing layer are each independently One or more selected from 4-methyl-6-tert-butylphenol and N-phenyl-N-cyclohexyl-p-phenylenediamine.

The types of the above components are conducive to the synergy between the various components, which can not only greatly improve the impedance matching characteristics of the absorbing material, but also provide a variety of absorbing loss mechanisms. A variety of mechanisms work together to make the absorbing strength and the absorbing material The effective absorption bandwidth is greatly increased.

The thickness of each absorbing layer in the above absorbing material can be adjusted reasonably according to actual needs. In a preferred embodiment of the present application, the thickness of the electromagnetic wave matching layer is 0.15~0.25mm; preferably, the thickness of the low frequency absorption layer is 0.65~0.75mm; preferably, the thickness of the high frequency absorption layer is 0.25~0.35mm . By reasonably optimizing the thickness of each wave absorbing layer, the layers cooperate with each other, thereby improving the wave absorbing strength and the absorption band width of the wave absorbing material.

In another typical embodiment of the present application, there is also provided a method for preparing a wave absorbing material, the preparation method includes: providing three types of wave absorbing plates, the three types of wave absorbing plates are electromagnetic wave matching plates and low frequency absorbing plates respectively And a high-frequency absorption sheet; three types of wave-absorbing sheets are sequentially stacked in the order of electromagnetic wave matching sheet, low-frequency absorption sheet and high-frequency absorption sheet to obtain a wave-absorbing material.

The above preparation method of the present application, by sequentially placing an electromagnetic wave matching layer, a low-frequency absorption layer and a high-frequency absorption layer along the incident direction of the electromagnetic wave, makes the electromagnetic wave firstly encounter the electromagnetic wave matching layer when propagating in the air, due to the impedance matching characteristics of the electromagnetic wave matching layer Similar to air, it can effectively reduce the reflection of electromagnetic waves, so that electromagnetic waves enter the interior of the absorption material relatively more, and is gradually absorbed by the low-frequency absorption layer, and then absorbed by the high-frequency absorption layer. Efficient absorption of wide frequency band.

In a preferred embodiment of the present application, the step of providing three kinds of absorbers includes using one or more absorbers selected from TiO ₂ , SiO ₂ and SiC as electromagnetic wave matching sheets ; More preferably, an absorber using an carbonyl iron powder as a low-frequency absorber; more preferably, an absorber selected from an oxide of one or more magnetic metals as a high-frequency absorber; Further preferably, the magnetic metal is selected from Fe, Co or Ni.

In the above preparation method, by using an electromagnetic wave matching sheet whose absorber is TiO ₂ , SiO ₂ or SiC, especially nano-titania, its dielectric constant is relatively close to the magnetic permeability, which can reduce the reflection at the interface and enable the electromagnetic wave to It may enter the inside of the absorbing material more. Compared with the existing absorbing material, the reflectivity of the surface is greatly reduced, the impedance matching of the material is optimized, and the absorbing performance is improved. The absorbing sheet using carbonyl iron powder as an absorber is used as a low-frequency absorbing sheet, making full use of the excellent microwave loss performance of carbonyl iron powder, and its microwave loss performance is greatly improved compared with the titanium dioxide absorbing material. Since the microwave loss performance of carbonyl iron powder is mainly reflected in the low frequency region, the introduction of iron oxide, nickel oxide, or cobalt oxide as high-frequency absorption sheet further improves the high-frequency absorption characteristics of the material, and a variety of loss mechanisms cooperate. The wave absorbing performance of the prepared wave absorbing material is greatly improved.

The above steps of providing three kinds of wave-absorbing plates only need to provide three kinds of wave-absorbing plates using different absorbers, and the specific preparation method is not particularly limited. In order to meet the processing requirements and actual use requirements, coupling agents, vulcanizing agents and antioxidants can be added to further improve the wave-absorbing performance of the three types of wave-absorbing plates provided above.

In a preferred embodiment of the present application, the step of providing three kinds of wave-absorbing plates further includes: separately preparing each type of wave-absorbing plate using a binder, a coupling agent, a vulcanizing agent, an antioxidant and an absorber Step; more preferably, the step of preparing each type of absorber includes: S1, premixing the absorber, coupling agent and antioxidant to obtain a premix; S2, the premix and the binder Mixing to obtain a mixed film; S3, adding a vulcanizing agent to the mixing film for refining, to obtain each type of absorber.

In the above preparation method, the binder is beneficial to improve the oil resistance and physical mechanical properties of the wave absorbing material, and endows the wave absorbing material with heat resistance and weather resistance, so that the wave absorbing material still maintains good working performance in a complex environment. The coupling agent is used to improve the interface between the wave absorber and the binder, thereby greatly improving the physical properties, dielectric properties, magnetic loss performance, etc. of the wave absorbing material, while improving the wear resistance and aging resistance of the material. And can reduce the amount of rubber, thereby reducing costs. The vulcanizing agent can reduce the plasticity of the binder and increase the elasticity and strength. Antioxidants can delay or inhibit the oxidation of rubber and other binders, thereby preventing aging and extending their service life.

In the above-mentioned preferred embodiment, by pre-mixing the coupling agent and the antioxidant with the absorbent, it is advantageous for the coupling agent and the antioxidant to play a corresponding role at the beginning of contact with the binder, thereby optimizing each The performance of the ingredients improves the absorption effect of the absorbent. The final addition of the vulcanizing agent is to further improve the performance of the binder and improve the physical and mechanical properties of the bonded wave-absorbing plate under the premise that the first four components are mixed evenly, which is more suitable for stability in complex environments. Give full play to its absorbing performance, and then improve the absorbing performance of absorbing materials.

In a preferred embodiment of the present application, in the step of preparing the electromagnetic wave matching sheet, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (67-150): (3 -5): (2-4): (1-2); more preferably, in the step of preparing the low-frequency absorption sheet, the weight ratio of the binder, absorbent, coupling agent, vulcanizing agent and antioxidant is 100 : (500-850): (3-5): (2-4): (1-2); more preferably, in the step of preparing the high-frequency absorption sheet, the binder, absorbent, coupling agent, vulcanization The weight ratio of the agent and the antioxidant is 100: (200-300): (3-5): (2-4): (1-2).

In the above preferred embodiment, by optimizing the dosage ratio of each component, the same synergy between the components is achieved, which not only realizes the optimization of the functions of each layer, but also makes the three absorbing layers match each other, thereby solving the impedance matching performance and The problem of contradictory attenuation characteristics improves the balance between magnetic permeability and dielectric constant, and improves the electromagnetic wave absorption performance of the absorbing material.

In the above preparation method, the specific types of binders, coupling agents, vulcanizing agents and antioxidants for preparing the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer are not particularly limited, and any corresponding materials that can achieve the above functions are Applies to this application. In a preferred embodiment of the present application, in the steps of preparing the electromagnetic wave matching sheet, the low-frequency absorption sheet and the high-frequency absorption sheet, the binders used are independently selected from neoprene rubber, polyurethane rubber, and silicone rubber One or more; more preferably, the coupling agent used is independently selected from one or more of titanate and vinyl tri-(2-methoxyethoxy) silane; more preferably Preferably, the vulcanizing agent used is independently selected from one or more of bis-pentapentyl sulfide and zinc oxide; more preferably, the antioxidant used is independently selected from 4-methyl-6- One or more of tert-butylphenol and N-phenyl-N-cyclohexyl-p-phenylenediamine.

The use of the types of the above-mentioned components is conducive to the synergy between the various components and provides a variety of absorption loss mechanisms. The combination of various mechanisms makes the absorption intensity and effective absorption bandwidth of the absorption material greatly improved.

The thickness of each wave absorbing sheet in the above wave absorbing material can be adjusted reasonably according to actual needs. In a preferred embodiment of the present application, the thickness of the electromagnetic wave matching sheet is 0.15~0.25mm; more preferably, the thickness of the low frequency absorption sheet is 0.65~0.75mm; more preferably, the thickness of the high frequency absorption sheet is 0.25~ 0.35mm. By rationally optimizing the thickness of each wave-absorbing sheet, the wave-absorbing layers are cooperatively coordinated, thereby improving the wave-absorbing intensity and width of the absorption band of the wave-absorbing material.

It should be noted that, in actual use, there is a certain limit to the thickness of the absorbing material, and the thickness of each absorbing layer also has an effect on the absorbing performance of the absorbing material, so it is preferable to strictly control the thickness within the above ranges , Especially electromagnetic wave matching sheet and high frequency absorbing sheet. Because of its relatively thin thickness, it is relatively difficult to control when operating on an ordinary open mill, so extra care is required during operation.

In a preferred embodiment of the present application, before step S2, the step of preparing each type of wave absorbing sheet further includes the step of preliminary smelting the adhesive into a sheet-shaped adhesive, and the adhesive in step S2 Kneading with the premix in the form of a sheet-shaped binder; more preferably, after step S2 and before step S3, the step of preparing each type of absorber further includes the step of cooling the mixed film ; More preferably, cooled to 20 ~ 30 ℃.

The binder is first densely kneaded into a sheet shape, which is more conducive to contact and play a role in the components in the premix containing the absorbent. After the mixed film is obtained, it is cooled and then added with a vulcanizing agent for refining. The purpose of cooling is to eliminate the stress in the rubber processing process, so that the coupling agent and other additives are completely mixed evenly. Cooling to the above temperature will help to eliminate stress and the diffusion of additives.

The beneficial effects of the present application will be further described in conjunction with specific embodiments below.

Example 1

Step 1. By weight, according to nanometer titanium dioxide powder (particle size is 150 nm or so): Neoprene: coupling agent (vinyl tri-(2-methoxyethoxy) silane): vulcanizing agent (double two five vulcanizing agent): antioxidant (4-methyl-6- Tert-butylphenol)=67:100:4:3:1 for weighing, put the weighed neoprene raw rubber on the open mixer into the feeding port above the two rollers to break the glue into pieces, and then gradually add the weighing The titanium dioxide powder that is pre-mixed with coupling agent and antioxidant is gradually added to the feeding port, the roller distance is adjusted, and the mixing is continued; the mixed film is taken out and placed in a clean tray to cool for more than 20min; adjusting the roller distance will cool well Put the above rubber material into the feeding port, let it wrap the roller, and gradually add double two five vulcanizing agent to continuously refining; after the surface is smooth and no bubbles, the film is adjusted, and the roller pitch is adjusted to make the film thickness 0.20mm.

Step 2. By weight, from carbonyl iron powder (particle size is about 2 μm): neoprene: coupling agent (vinyl tri-(2-methoxyethoxy) silane): vulcanizing agent (double two Five vulcanizing agent): antioxidant (4-methyl-6-tert-butylphenol) = 850:100:4:3:1 for weighing, and put the weighed neoprene raw rubber on the open mixer Go to the feeding port above the two rollers to break the glue into pieces, and then gradually add the carbonyl iron powder that has been weighed and pre-mixed with the coupling agent and antioxidant. Then gradually add the feeding port, adjust the roller distance, and continuously mix; take out the mixed film, Put it in a clean tray and cool for more than 20min; adjust the roller distance and put the cooled rubber material into the feeding port, let it wrap the roller, and gradually add double two five vulcanizing agent to continuously refining; after the surface is smooth and no bubbles, the film is released , Adjust the roller pitch to make the film thickness 0.70mm.

Step 3. By weight, it is composed of nanometer ferric oxide powder (particle size is 100 nm or so): Neoprene: coupling agent (vinyl tri-(2-methoxyethoxy) silane): vulcanizing agent (double two five vulcanizing agent): antioxidant (4-methyl-6- Tert-butylphenol)=300:100:4:3:1 for weighing, put the weighed neoprene raw rubber on the open mixer into the feeding port above the two rollers to break the glue into pieces, and then gradually add the weighing Good and pre-mix the coupling agent and anti-oxidant nano-iron tetroxide powder gradually add to the feeding port, adjust the roll distance, continuous mixing; take out the mixed film, put it in a clean tray and cool for more than 20min; adjust the roll distance Put the above-mentioned cooled rubber compound into the feeding port, let it wrap the roller, and gradually add double two five vulcanizing agent to continuously refining; after the surface is smooth and no bubbles, the film is released, and the roller pitch is adjusted to make the film thickness 0.30mm.

Step 4. Laminate the mixed sheets in the order of titanium dioxide powder, carbonyl iron powder, and iron trioxide powder, and vulcanize with a flat vulcanizer to prepare a patch; the molding temperature is 150℃ and the pressure It is 10MPa and the curing time is 25min. A sheet-shaped absorbing material with a specification of 350mmX350mm was produced.

Example 2

In step 1, the weight ratio of titanium dioxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant is adjusted to 100:100:4:3:1, and the roller pitch is adjusted so that the film thickness is 0.15mm. Example 1 is repeated for the rest.

Example 3

In step 2, the weight ratio of carbonyl iron powder: neoprene: coupling agent: vulcanizing agent: antioxidant is adjusted to 500:100:4:3:1, and the roller pitch is adjusted to make the film thickness 0.65mm. Example 1 is repeated for the rest.

Example 4

In step 2, the weight ratio of carbonyl iron powder: neoprene: coupling agent: vulcanizing agent: antioxidant is adjusted to 700:100:4:3:1, and the roller pitch is adjusted so that the film thickness is 0.75mm. Example 1 is repeated for the rest.

Example 5

In step 3, the weight ratio of ferroferric oxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant is adjusted to 250:100:4:3:1, and the roller pitch is adjusted so that the film thickness is 0.25mm Example 1 is repeated for the rest.

Example 6

In step 1, the weight ratio of titanium dioxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant is adjusted to 100:150:5:4:2, and the roller pitch is adjusted so that the film thickness is 0.25mm. Example 1 is repeated for the rest.

Example 7

Adjust the weight ratio of titanium dioxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant in step 1 to 100:90:3:2:1, and repeat Example 1 for the rest.

Example 8

The weight ratio of carbonyl iron powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant in step 2 was adjusted to 750:100:5:4:2, and Example 1 was repeated for the rest.

Example 9

The weight ratio of carbonyl iron powder: neoprene: coupling agent: vulcanizing agent: antioxidant in step 2 was adjusted to 550:100:3:2:1, and Example 1 was repeated for the rest.

Example 10

In step 3, the weight ratio of ferroferric oxide powder: neoprene: coupling agent: vulcanizing agent: antioxidant is adjusted to 200:100:5:4:2, and the roller pitch is adjusted so that the film thickness is 0.35mm Example 1 is repeated for the rest.

Example 11

In step 3, the weight ratio of ferroferric oxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant is adjusted to 250:100:3:2:2, and Example 1 is repeated for the rest.

Example 12

Replace the nano-titania powder in step 1 with SiO ₂ powder (the particle size is unchanged), and repeat Example 1 for the rest.

Example 13

Replace the nano-titania powder in step 1 with SiC powder (the particle size is unchanged), and repeat Example 1 for the rest.

Example 14

Replace the nano-titania powder in step 1 with nano-titania powder + SiC powder (the mass ratio of the two is 1::1), and repeat Example 1 for the rest.

Example 15

In step 3, the ferroferric oxide powder was replaced with cobalt tetroxide, but the particle size was unchanged, and the rest was repeated in Example 1.

Example 16

In step 3, the ferroferric oxide powder was replaced with nickel oxide powder but the particle size was unchanged, and the rest was repeated in Example 1.

Example 17

The adhesive of each step was replaced with polyurethane rubber (Mooney viscosity 50), the coupling agent was replaced with titanate, and the rest was repeated in Example 1.

Example 18

On the basis of Example 13, the vulcanizing agent and antioxidant in each step were further replaced with zinc oxide and N-phenyl-N-cyclohexyl-p-phenylenediamine.

Example 19

The weight ratio of titanium dioxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant in step 1 was adjusted to 65:100:4:3:1, and Example 1 was repeated for the rest.

Example 20

The weight ratio of carbonyl iron powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant in step 2 was adjusted to 900:100:4:3:1, and Example 1 was repeated for the rest.

Example 21

In step 3, the weight ratio of nanometer ferrous tetroxide powder: neoprene rubber: coupling agent: vulcanizing agent: antioxidant is adjusted to 320:100:4:3:1, and Example 1 is repeated for the rest.

Example 22

The antioxidant in step 3 is removed, and the weight ratio of nanometer ferrous oxide powder: neoprene rubber: coupling agent: vulcanizing agent is adjusted to 300:100:4:3, and Example 1 is repeated for the rest.

Example 23

The vulcanizing agent in step 2 is removed, and the weight ratio of carbonyl iron powder: neoprene rubber: coupling agent: antioxidant is adjusted to 850:100:4:1, and Example 1 is repeated for the rest.

Example 24

The coupling agent in step 3 is removed, and the weight ratio of nanometer ferrous oxide powder: neoprene rubber: vulcanizing agent: antioxidant is adjusted to 300:100:3:1, and Example 1 is repeated for the rest.

Comparative Example 1

Using the method disclosed in CN108092006A to prepare a 5-layer structure radar absorber, from top to bottom are : first layer: spherical iron carbonyl film; second layer and third layer: sheet iron carbonyl film; fourth layer and The fifth layer is sheet iron silicon aluminum film. The thickness of the first layer is 0.10 mm; the thickness of the second and third layers is 0.18 mm, the thickness of the fourth layer is 0.06 mm, and the thickness of the fifth layer is 0.05 mm.

test:

The wave absorption performance is measured by the bow reflection method, and the test frequency is 2-18 GHz. Before the test starts, the vector network analyzer should be turned on and warmed up for 30 minutes. Each patch must measure 3 frequency segments, which are 2-6GHz, 4-8GHz and 8-18GHz respectively. The test is completed by combining the reflectivity of 3 sections. After testing, the comparison of the absorbing properties of the materials prepared in the above Examples 1-24 and Comparative Example 1 is shown in Table 1.

From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: by sequentially placing an electromagnetic wave matching layer, a low-frequency absorption layer, and a high-frequency absorption layer along the incident direction of the electromagnetic wave, the electromagnetic wave propagates in the air First, the electromagnetic wave matching layer is encountered. Because the impedance matching characteristics of the electromagnetic wave matching layer are similar to air, it can effectively reduce the reflection of the electromagnetic wave, so that the electromagnetic wave enters the interior of the absorbing material relatively more, and is gradually absorbed by the low frequency absorption layer. The high-frequency band is absorbed by the high-frequency absorption layer, thereby achieving efficient absorption from low to high frequencies. This application utilizes a multilayer structure, which not only solves the contradiction between impedance matching characteristics and attenuation characteristics, but also introduces a variety of loss mechanisms to improve the balance between magnetic permeability and dielectric constant, thereby improving the electromagnetic wave absorption performance of the wave absorbing material.

In some preferred embodiments, an electromagnetic wave matching layer is prepared by using an absorber whose dielectric constant is close to the magnetic permeability, such as nano-titanium dioxide, so that the electromagnetic wave can enter the inside of the material as much as possible, compared with the ordinary wave-absorbing material , Can greatly reduce the reflectivity of the surface, optimize the impedance matching of the material, and improve the absorbing performance. In some preferred embodiments, the excellent microwave loss performance of carbonyl iron powder is also utilized to absorb low-frequency electromagnetic waves. In some preferred embodiments, a high-frequency absorption layer is prepared by further introducing an absorbent such as triiron tetroxide that further improves high-frequency absorption characteristics. In addition, a dielectric loss mechanism is introduced, and a variety of loss mechanisms cooperate to make The wave absorbing performance of the material of this application has been greatly improved.

Industrial applicability

The above is only the preferred embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

A wave absorbing material, characterized in that the wave absorbing material includes, in order, an electromagnetic wave incident direction: an electromagnetic wave matching layer, a low frequency absorbing layer, and a high frequency absorbing layer.
The wave absorbing material according to claim 1, wherein the electromagnetic wave matching layer, the low frequency absorbing layer, and the high frequency absorbing layer respectively contain different absorbers, and the absorption in the electromagnetic wave matching layer The agent is selected from any one or more of TiO 2 , SiO 2 and SiC;

Preferably, the absorbent in the low-frequency absorption layer is selected from carbonyl iron powder;

Preferably, the absorber in the high-frequency absorption layer is selected from oxides of one or more magnetic metals; more preferably, the magnetic metal is selected from Fe, Co, or Ni.
The wave-absorbing material according to claim 2, wherein the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer all further include a binder and an optional coupling agent, optional Vulcanizing agent and optional antioxidant.
The wave-absorbing material according to claim 3, wherein the electromagnetic wave matching layer, the low-frequency absorption layer, and the high-frequency absorption layer all further include the binder, the coupling agent, and the Vulcanizing agent and the antioxidant;

Preferably, in the electromagnetic wave matching layer, the weight ratio of the binder, the absorber, the coupling agent, the vulcanizing agent and the antioxidant is 100: (67-150): ( 3-5): (2-4): (1-2);

Preferably, in the low-frequency absorption layer, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (500-850): ( 3-5): (2-4): (1-2);

Preferably, in the high-frequency absorption layer, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (200-300): (3-5): (2-4): (1-2).
The wave-absorbing material according to claim 3, wherein the binders of the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer are each independently selected from neoprene rubber and polyurethane rubber And one or more of silicone rubber;

Preferably, the coupling agents of the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer are each independently selected from titanate and vinyl tri-(2-methoxyethoxy) One or two of silane;

Preferably, the vulcanizing agent of the electromagnetic wave matching layer, the low-frequency absorbing layer and the high-frequency absorbing layer are each independently selected from one or two of bis-pentapentyl sulfide and zinc oxide;

Preferably, the antioxidants of the electromagnetic wave matching layer, the low-frequency absorption layer and the high-frequency absorption layer are each independently selected from 4-methyl-6-tert-butylphenol and N-phenyl-N -One or two of cyclohexyl p-phenylenediamine.
The wave absorbing material according to claim 2 or 3, wherein the thickness of the electromagnetic wave matching layer is 0.15~0.25mm;

Preferably, the thickness of the low-frequency absorption layer is 0.65 to 0.75 mm;

Preferably, the thickness of the high-frequency absorption layer is 0.25 to 0.35 mm.
A preparation method of a wave absorbing material, characterized in that the preparation method includes:

Provide three kinds of absorbing sheet, the three kinds of absorbing sheet are electromagnetic wave matching sheet, low frequency absorbing sheet and high frequency absorbing sheet respectively;

The three types of wave absorbing sheets are stacked in this order in order of the electromagnetic wave matching sheet, the low frequency absorbing sheet and the high frequency absorbing sheet to obtain the wave absorbing material.
The preparation method according to claim 7, characterized in that the step of providing three kinds of absorbers includes using one or more absorbers selected from TiO 2 , SiO 2 , and SiC as the absorber The electromagnetic wave matching sheet;

Preferably, a wave absorbing sheet whose absorber is carbonyl iron powder is used as the low frequency absorbing sheet;

Preferably, an absorber selected from oxides of one or more magnetic metals is used as the high-frequency absorber; more preferably, the magnetic metal is selected from Fe, Co, or Ni.
The preparation method according to claim 8, characterized in that the step of providing three kinds of absorber plates further comprises: using a binder, a coupling agent, a vulcanizing agent, and an antioxidant and the absorber to prepare each The steps of a kind of absorber;

Preferably, the step of preparing each of the wave absorbing plates includes:

S1, premix the absorbent, the coupling agent and the antioxidant to obtain a premix;

S2, mixing the premix with the binder to obtain a mixed film;

S3, adding the vulcanizing agent to the mixed film for refining to obtain each of the wave absorbing plates.
The preparation method according to claim 9, wherein in the step of preparing the electromagnetic wave matching sheet, the binder, the absorber, the coupling agent, the vulcanizing agent and the antioxidant The weight ratio of the agent is 100: (67-150): (3-5): (2-4): (1-2);

Preferably, in the step of preparing the low-frequency absorption sheet, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (500-850 ): (3-5): (2-4): (1-2);

Preferably, in the step of preparing the high-frequency absorption sheet, the weight ratio of the binder, the absorbent, the coupling agent, the vulcanizing agent and the antioxidant is 100: (200- 300): (3-5): (2-4): (1-2).
The manufacturing method according to claim 9 or 10, characterized in that in the steps of preparing the electromagnetic wave matching sheet, the low-frequency absorption sheet, and the high-frequency absorption sheet,

The binder used is independently selected from one or more of neoprene, urethane rubber, and silicone rubber; preferably, the coupling agent used is independently selected from titanate And one or both of vinyl tris-(2-methoxyethoxy) silane;

Preferably, each of the vulcanizing agents used is independently selected from one or two of bis-pentapentyl sulfide and zinc oxide;

Preferably, the antioxidants used are each independently selected from one or both of 4-methyl-6-tert-butylphenol and N-phenyl-N-cyclohexyl-p-phenylenediamine.
The preparation method according to any one of claims 7 to 10, wherein the thickness of the electromagnetic wave matching sheet is 0.15 to 0.25 mm;

Preferably, the thickness of the low-frequency absorption sheet is 0.65 to 0.75 mm;

Preferably, the thickness of the high-frequency absorption sheet is 0.25 to 0.35 mm.
The preparation method according to claim 9, wherein after the step S1 and before the step S2, the step of preparing each of the wave absorbing plates further comprises: preliminary smelting the binder A step of forming a sheet-shaped adhesive, in step S2, the adhesive is kneaded with the premix in the form of a sheet-shaped adhesive,

Preferably, after the step S2 and before the step S3, the step of preparing each of the wave absorbing plates further includes: a step of cooling the mixed film; more preferably, cooling to 20~ 30℃.