Impact-resistant structure wave-absorbing material and preparation method thereof

Abstract

The invention discloses an impact-resistant structure wave-absorbing material and a preparation method thereof, and belongs to the technical field of wave-absorbing materials. The impact-resistant structure wave-absorbing material comprises a rubber sheet and a light structure wave-absorbing layer which are stacked in sequence. And the raw materials of the rubber sheet comprise rubber and hollow glass beads filled in the rubber. By filling the hollow glass beads, the impedance matching property between the material and air is remarkably improved, so that electromagnetic waves enter the wave-absorbing layer to the greatest extent to generate loss, and the wave-absorbing property of the material is effectively improved; the rubber sheet has good flexibility and impact resistance, and has excellent impact resistance even under the condition that the thickness is 0.4-1.2 mm; due to the fact that the hollow glass beads are added, the surface density of the rubber sheet is only 0.3-0.8 kg / m, the rubber sheet is combined with the light structure wave-absorbing material, the overall weight is light, and the maneuverability of maneuvering equipment is improved. The impact-resistant structure wave-absorbing material not only has good electromagnetic wave absorption performance and impact resistance, but also is light in weight and high in environmental adaptability, and the preparation process is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of wave-absorbing materials, and in particular to an impact-resistant structure wave-absorbing material and a preparation method thereof. Background Art

[0002] Structural absorbing materials are multifunctional composite materials developed on the basis of advanced composite materials that can both bear and absorb waves. According to their structural forms, they can be divided into FRP laminate type, honeycomb sandwich type and foam sandwich type. Among them, honeycomb sandwich absorbing materials and foam sandwich absorbing materials are classified as lightweight structural absorbing materials because their density is significantly lower than that of FRP absorbing laminates. The lightweight structural absorbing material consists of a skin, a lightweight core material (honeycomb core material, foam core material) and a reflective layer. Due to its performance advantages such as light weight, high strength, strong absorption of wide-band electromagnetic waves, and excellent environmental adaptability, the lightweight structural absorbing material is widely used in radar stealth of mobile weapons and equipment.

[0003] At present, lightweight structural absorbing materials are vulnerable to impact during their application in ground mobile equipment, and impact conditions are common, which requires lightweight structural absorbing materials to have both radar absorbing and impact-resistant functions.

[0004] In order to make the lightweight structure absorbing material have excellent radar absorbing performance, its skin must be made of fiberglass with good wave transmission and the thickness should not exceed 1 mm. Because under the same internal absorption layer, too thick skin will lead to a significant increase in Ku and Ka band reflectivity and a decrease in the material's absorbing performance. Because the fiberglass skin is brittle, the brittle and thin skin is easy to break when hit, resulting in damage to the absorbing material and cannot meet the requirements of impact application conditions.

[0005] Existing technologies for solving the problem of multifunctional integration of wave absorption and impact resistance of lightweight structure wave absorbing materials include: (1) Spraying polyurea resin on the fiberglass skin to give the absorbing material impact resistance. For example, in the Chinese invention patent with application number 201710220234.0 and the Chinese invention patent with application number 202210366761.3, spraying polyurea coating on the honeycomb sandwich absorbing material skin plays an impact resistance role, but the impact resistance performance index and test standard that can be achieved are not clear, and spraying polyurea resin with high dielectric loss on the skin actually increases the thickness of the skin and increases the overall dielectric loss of the skin, thereby reducing the wave transmission of the skin, and significantly improving the reflectivity in the Ku and Ka bands. Although the embodiment does not test the reflectivity in the Ka band, it can be seen from the drawings in the specifications of the above two patents that the reflectivity increases significantly from 14 GHz, and the slope of the reflectivity curve at 18 GHz is larger.

[0006] (2) Using ultra-high molecular weight polyethylene fiber reinforced flexible resin instead of fiberglass as the skin to give the absorbing material impact resistance. For example, the Chinese invention patent with application number 202011491515.8 uses ultra-high molecular weight polyethylene fiber reinforced polyurea resin as the skin, and the prepared honeycomb sandwich absorbing material meets the requirements of Section 5.1 of GJB2093A-2012 "General Test Methods for Military Shelters" - Sandwich Panel Impact Resistance Test. Polyethylene fiber has low dielectric loss and good wave transmittance. The attached figure of the specification shows that the reflectivity of the absorbing material in the L, S, C, X, and Ku bands is low, and it has broadband absorbing performance. However, polyethylene has low polarity and poor bonding with high-polarity polyurea resin. When the skin is prepared by hand lay-up, the fiber surface is prone to lack of glue and the fiber is easy to delaminate, forming skin defects, resulting in poor environmental adaptability and failure to meet engineering application requirements.

[0007] (3) Filling the toughened modified resin into the pores of the absorbing honeycomb core under the fiberglass skin to form an impact-resistant absorbing honeycomb core, giving the absorbing material impact resistance. For example, the Chinese invention patent with application number 202111212465.X provides an impact-resistant honeycomb sandwich absorbing material and a preparation method thereof. The absorbing material contains two layers of absorbing honeycomb cores. The absorbing honeycomb sandwich absorbing material is integrated with wave absorption and impact resistance by filling the pores of the surface layer of the absorbing honeycomb core with toughened resin. The invention requires that the toughened resin be filled into the pores of the surface layer of the absorbing honeycomb core with a thickness of 2 to 11 mm, resulting in a high overall density and heavy weight of the material, which is contrary to the lightweight requirements of absorbing materials used in mobile equipment. In addition, this method is not suitable for another large category of lightweight structural absorbing materials - foam sandwich absorbing materials, because foam does not have pores similar to honeycomb structures and cannot be filled with resin.

[0008] In order to meet market demand, it is urgent to develop an impact-resistant structural absorbing material that has strong electromagnetic wave absorption ability, light weight and excellent environmental adaptability. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides an impact-resistant structural absorbing material which has strong absorption of wide-band electromagnetic waves, is impact-resistant, light in weight, and has excellent environmental adaptability, and a preparation method thereof.

[0010] The impact-resistant structural wave-absorbing material comprises rubber sheets and a light-weight structural wave-absorbing layer which are stacked in sequence.

[0011] Preferably, the thickness of the rubber sheet is 0.4-1.2 mm.

[0012] Preferably, the raw materials of the rubber sheet include rubber and hollow glass microspheres filled therein.

[0013] For absorbing materials to effectively absorb electromagnetic waves, they must meet two basic conditions: first, when electromagnetic waves are incident on the surface of the material, they can penetrate into the interior of the material to the greatest extent possible to reduce direct reflection of the electromagnetic waves, which requires the material to have impedance matching characteristics; second, when electromagnetic waves enter the interior of the material, they can be attenuated, which requires the material to have electromagnetic wave attenuation characteristics.

[0014] As an impact-resistant layer, the rubber sheet is located on the upper layer of the impact-resistant structural absorbing material. It is the wave-facing surface of the electromagnetic wave, allowing the electromagnetic wave to enter the lightweight structural absorbing material below to the maximum extent, so as to reduce the reflection caused by the sudden change of impedance when the electromagnetic wave is transmitted from the air to the surface of the material; the impact-resistant layer is composed of a rubber matrix and hollow glass microspheres. The main component of the hollow glass microspheres is low-dielectric borosilicate (dielectric constant is only 1.2~1.7) and contains a large amount of air. After adding, it can significantly improve the impedance matching between the impact-resistant layer and the air, so that the electromagnetic wave can enter the absorbing material to the maximum extent and cause loss, thereby improving the broadband absorbing performance. Rubber has excellent flexibility, and a thickness of only 0.4~1.2 mm can give the material excellent impact resistance. Therefore, the impact-resistant layer plays the role of impact resistance and impedance matching at the same time.

[0015] In addition, the physical and chemical properties of rubber materials are stable, and the environment is highly inert. When placed on the surface of the material, the material has excellent environmental adaptability. Due to the addition of hollow glass microspheres, the surface density of the 0.4~1.2 mm impact-resistant layer is only 0.3~0.8 kg / m 2 After bonding and compounding with lightweight structural absorbing materials, the total weight is light, which meets the lightweight requirements and is beneficial to improving the mobility of mobile equipment.

[0016] Preferably, the mass of the hollow glass beads in the rubber sheet is 5% to 30% of the mass of the rubber.

[0017] More preferably, the hollow glass microspheres have a particle size of 20-135 μm and a wall thickness of 1-5 μm.

[0018] Preferably, the rubber sheet is mainly prepared by the following steps: mixing rubber, hollow glass microbeads, a curing agent and an auxiliary agent, and then successively subjecting the mixture to plasticizing, mixing, calendering and vulcanization.

[0019] Preferably, the light structure absorbing layer comprises a fiberglass skin, a light structure absorbing material and a fiberglass skin stacked in sequence.

[0020] Further preferably, the lightweight structure absorbing material includes one of aramid honeycomb absorbing material, polymethacrylimide foam absorbing material and polyurethane foam absorbing material.

[0021] Preferably, the thickness of the lightweight structure absorbing layer is 5-60 mm.

[0022] Preferably, the thickness of the fiberglass skin is 0.2-1 mm.

[0023] The method for preparing the impact-resistant structural absorbing material comprises the following steps: grinding a surface of a rubber sheet and a light-weight structural absorbing layer to roughness, and then bonding the rough surface of the rubber sheet and the rough surface of the light-weight structural absorbing layer with an adhesive to obtain the impact-resistant structural absorbing material.

[0024] Compared with the prior art, the beneficial effects of the present invention are: 1. The impact-resistant structural absorbing material provided by the present invention significantly improves the impedance matching between the material and the air by adding hollow glass microspheres into the rubber sheet, so that electromagnetic waves can enter the interior of the material more effectively; through the combined design of the rubber sheet and the lightweight structural absorbing layer, the electromagnetic waves can be effectively attenuated after entering the material, thereby improving the absorbing performance.

[0025] 2. The impact-resistant structural absorbing material provided by the present invention can provide excellent impact resistance even at a relatively thin thickness of 0.4-1.2 mm, because the rubber sheet has good flexibility and impact resistance; due to the addition of hollow glass microbeads, the surface density of the rubber sheet is relatively low, only 0.3-0.8 kg / m², and after being combined with the lightweight structural absorbing material, the overall weight is relatively light, which is beneficial to improving the mobility of mobile equipment; and the rubber material has stable physical and chemical properties and high environmental inertness, so that the material has good environmental adaptability.

[0026] 3. The impact-resistant structural absorbing material provided by the present invention not only has good electromagnetic wave absorption performance and impact resistance, but also has light weight, strong environmental adaptability and simple preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of an embodiment of the impact-resistant structural absorbing material proposed by the present invention; wherein: 1, rubber sheet; 2, lightweight structural absorbing layer. DETAILED DESCRIPTION

[0028] It should be noted that, in the embodiments, those without specifying specific conditions are carried out according to normal conditions or conditions recommended by the manufacturer. Those without specifying the manufacturer of reagents or instruments used are conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, and "A and / or B" is taken as an example, including schemes A, B, or A and B that meet the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of the technical schemes is contradictory or cannot be achieved, it should be considered that the combination of such technical schemes does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work, all belong to the scope of protection of the present invention.

[0029] In view of the deficiencies of the prior art described in the background art, the present invention provides an impact-resistant honeycomb sandwich absorbing material and a preparation method thereof. The present invention is described in detail below in conjunction with the accompanying drawings.

[0030] The technical scheme of the present invention is further described below through examples. The raw materials used in the examples can be purchased commercially or prepared by conventional methods. The rubber, curing agent, additive, hollow glass microsphere and adhesive used in the following examples of the present invention are all commercially mature products; the aramid honeycomb absorbing material, polymethacrylimide foam absorbing material and polyurethane foam absorbing material are BD-Fg series aramid honeycomb absorbing material, BD-Fd series polymethacrylimide foam absorbing material and BD-Fb series polyurethane foam absorbing material of Wuhan Magnetics and Electrics Co., Ltd. of Aerospace Science and Industry Corporation respectively.

[0031] Example 1 A shock-resistant structural wave-absorbing material, comprising sequentially stacked layers with a thickness of 0.5 mm and a surface density of 0.4 kg / m 2 The invention relates to a rubber sheet and a lightweight structural absorbing layer with a thickness of 10 mm; the main raw materials of the rubber sheet are 3309 silicone rubber and K20 hollow glass beads with a particle size of 20 μm and a wall thickness of 1 μm; the mass of the K20 hollow glass beads is 30% of the mass of the 3309 silicone rubber; the lightweight structural absorbing layer comprises a fiberglass skin, a BD-Fg006 aramid honeycomb absorbing material and a fiberglass skin stacked in sequence, and the thickness of the fiberglass skin is 0.5 mm.

[0032] The rubber sheet is mainly prepared by the following steps: 500 g of 3309 silicone rubber, 7.5 g of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (curing agent), 35 g of vinyl silicone oil (auxiliary agent) and 150 g of K20 hollow glass microspheres are added to an open mill in batches for mixing, and the mixing is repeated 10 times to mix the components evenly to obtain a mixed material; the mixed material is added to a calender for calendering, and the calendering thickness is 0.5 mm to obtain a calendered material; the calendered material is added to a vulcanizer for vulcanization to obtain a material with a thickness of 0.5 mm and a surface density of 0.4 kg / m 2 of rubber sheet.

[0033] The method for preparing the impact-resistant structural absorbing material comprises the following preparation steps: grinding one surface of the rubber sheet and the lightweight structural absorbing layer prepared above to roughness, and then using EP01 epoxy adhesive to bond the rough surface of the rubber sheet and the rough surface of the lightweight structural absorbing layer to obtain the impact-resistant structural absorbing material.

[0034] The standard size samples were prepared by the above method, and the reflectivity test was carried out according to GJB2038A-2011 "Test Method for Reflectivity of Radar Absorbing Materials", and the impact resistance test was carried out according to GJB2093A-2012 "General Test Method for Military Shelters" and judged against the requirements of the standard, see Table 1 for details.

[0035] Table 1 Test data of Example 1

[0036] Example 2 A shock-resistant structural wave-absorbing material, comprising sequentially stacked layers with a thickness of 1.2 mm and a surface density of 0.8 kg / m 2 The invention relates to a rubber sheet and a lightweight structural absorbing layer with a thickness of 24 mm; the main raw materials of the rubber sheet are 602 polyurethane rubber and K50 hollow glass microspheres with a particle size of 50 μm and a wall thickness of 3 μm; the mass of the K50 hollow glass microspheres is 20% of the mass of the 602 polyurethane rubber; the lightweight structural absorbing layer comprises a fiberglass skin, a BD-Fb003 type polyurethane foam absorbing material and a fiberglass skin stacked in sequence, and the thickness of the fiberglass skin is 0.2 mm.

[0037] The rubber sheet is mainly prepared by the following steps: 500 g of 602 polyurethane rubber, 40 g of diisopropyl peroxide (curing agent), 20 g of N-isopropyl-N'-phenyl-p-phenylenediamine (auxiliary agent), 10 g of triallyl isocyanurate (auxiliary agent) and 100 g of K50 hollow glass microspheres are added to an open mill in batches for mixing, and the mixing is repeated 10 times to mix the components evenly to obtain a mixed material; the mixed material is added to a calender for calendering, and the calendering thickness is 1.2 mm to obtain a calendered material; the calendered material is added to a vulcanizer for vulcanization to obtain a material with a thickness of 1.2 mm and a surface density of 0.8 kg / m 2 of rubber sheet.

[0038] The method for preparing the impact-resistant structural absorbing material comprises the following preparation steps: grinding one surface of the rubber sheet and the lightweight structural absorbing layer prepared above to roughness, and then using EP01 epoxy adhesive to bond the rough surface of the rubber sheet and the rough surface of the lightweight structural absorbing layer to obtain the impact-resistant structural absorbing material.

[0039] The standard size samples were prepared by the above method, and the reflectivity test was carried out according to GJB2038A-2011 "Test Method for Reflectivity of Radar Absorbing Materials", and the impact resistance test was carried out according to GJB2093A-2012 "General Test Method for Military Shelters" and judged against the requirements of the standard, see Table 2 for details.

[0040] Table 2 Test data of Example 2

[0041] Example 3 A shock-resistant structural wave-absorbing material, comprising sequentially stacked layers with a thickness of 0.4 mm and a surface density of 0.3 kg / m 2 The invention relates to a rubber sheet and a lightweight structural absorbing layer with a thickness of 30 mm; the main raw materials of the rubber sheet are 1103 nitrile rubber and K135 hollow glass beads with a particle size of 50 μm and a wall thickness of 3 μm; the mass of the K135 hollow glass beads is 5% of the mass of the 1103 nitrile rubber; the lightweight structural absorbing layer comprises a fiberglass skin, a BD-Fd005 polymethacrylimide foam absorbing material and a fiberglass skin which are stacked in sequence, and the thickness of the fiberglass skin is 1 mm.

[0042] The rubber sheet is mainly prepared by the following steps: 500 g of 1103 nitrile rubber, 40 g of diisopropyl peroxide (curing agent), 20 g of N-isopropyl-N'-phenyl-p-phenylenediamine (auxiliary agent), 10 g of triallyl isocyanurate (auxiliary agent) and 25 g of K135 hollow glass microspheres are added to an open mill in batches for mixing, and the mixing is repeated 10 times to mix the components evenly to obtain a mixed material; the mixed material is added to a calender for calendering, and the calendering thickness is 0.4 mm to obtain a calendered material; the calendered material is added to a vulcanizer for vulcanization to obtain a material with a thickness of 0.4 mm and a surface density of 0.3 kg / m 2 of rubber sheet.

[0043] The method for preparing the impact-resistant structural absorbing material comprises the following preparation steps: grinding one surface of the rubber sheet and the lightweight structural absorbing layer prepared above to roughness, and then using EP01 epoxy adhesive to bond the rough surface of the rubber sheet and the rough surface of the lightweight structural absorbing layer to obtain the impact-resistant structural absorbing material.

[0044] The standard size samples were prepared by the above method, and the reflectivity test was carried out according to GJB2038A-2011 "Test Method for Reflectivity of Radar Absorbing Materials", and the impact resistance test was carried out according to GJB2093A-2012 "General Test Method for Military Shelters" and judged against the requirements of the standard, see Table 3 for details.

[0045] Table 3 Test data of Example 3

[0046] It should be understood that the above embodiments are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims

1. An impact-resistant structural absorbing material, characterized in that: It comprises a rubber sheet and a light structure wave absorbing layer which are stacked in sequence; the raw materials of the rubber sheet include rubber and hollow glass micro beads filled in the rubber.

2. The impact-resistant structural absorbing material according to claim 1, characterized in that: The thickness of the rubber sheet is 0.4-1.2 mm.

3. The impact-resistant structural absorbing material according to claim 1, characterized in that: The mass of the hollow glass microbeads in the rubber sheet is 5% to 30% of the mass of the rubber.

4. The impact-resistant structural absorbing material according to claim 1 or 3, characterized in that: The hollow glass microspheres have a particle size of 20-135 μm and a wall thickness of 1-5 μm.

5. The impact-resistant structural absorbing material according to claim 1, characterized in that: The rubber sheet is mainly prepared by the following steps: mixing rubber, hollow glass microbeads, curing agent and auxiliary agent, and then successively plasticizing, mixing, calendering and vulcanizing to obtain the rubber sheet.

6. The impact-resistant structural absorbing material according to claim 1, characterized in that: The light structure wave absorbing layer comprises a glass fiber reinforced plastic skin, a light structure wave absorbing material and a glass fiber reinforced plastic skin which are stacked in sequence.

7. The impact-resistant structural absorbing material according to claim 6, characterized in that: The light structure absorbing material comprises one of aramid honeycomb absorbing material, polymethacrylimide foam absorbing material and polyurethane foam absorbing material.

8. The impact-resistant structural absorbing material according to claim 1, characterized in that: The thickness of the lightweight structure absorbing layer is 5-60 mm.

9. The impact-resistant structural absorbing material according to claim 1, characterized in that: The thickness of the fiberglass skin is 0.2-1 mm.

10. The impact-resistant structural absorbing material according to claim 1, characterized in that: The method for preparing the impact-resistant structural absorbing material comprises the following steps: grinding a surface of a rubber sheet and a light-weight structural absorbing layer to roughness, and then bonding the rough surface of the rubber sheet and the rough surface of the light-weight structural absorbing layer with an adhesive to obtain the impact-resistant structural absorbing material.

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