Polymer plastic wave-absorbing anti-interference low-infrared characteristic material and preparation method thereof

Abstract

The invention relates to a polymer plastic wave-absorbing anti-interference low-infrared characteristic material and a preparation method thereof, the material comprises a plurality of functional layers, and the functional layers comprise a surface layer, a wave-absorbing layer, a core layer and a bonding layer; the wave-absorbing layer and the bonding layer contain a wave-absorbing mixture composed of a magnetic medium type wave-absorbing material, a dielectric medium type wave-absorbing material and a resistance type wave-absorbing material, and the wave-absorbing layer forms a closed micropore structure through an extrusion foaming process; the core layer only contains a resistance-type wave-absorbing heat-conducting material, the density and the strength of the core layer are far greater than those of the wave-absorbing layer, and the core layer is used for supporting the overall strength of the material; the base material of the bonding layer is maleic anhydride grafted modified PE or PP resin, and the bonding layer contains 5%-15% of a wave-absorbing blend; the high-molecular plastic wave-absorbing anti-interference and low-infrared characteristic material disclosed by the invention not only has excellent wave-absorbing anti-interference and low-infrared characteristic performance, but also has the advantages of high strength, light weight, environmental protection, low carbon, high efficiency and low cost in production and use processes.

Description

Technical Field

[0001] The invention relates to the technical field of wave-absorbing, anti-interference and low-infrared characteristic composite materials, and in particular to a polymer plastic wave-absorbing, anti-interference and low-infrared characteristic material and a preparation method thereof. Background Art

[0002] With the continuous development of technology, there is an urgent need for a high-performance polymer plastic wave-absorbing, anti-interference and low-infrared characteristic material that has the properties of wave absorption and anti-interference, electromagnetic shielding, radar, infrared stealth, etc., and is environmentally friendly, efficient, and low-cost during production and use, and has a wide range of application scenarios. Not only does it need to have excellent wave absorption, anti-interference and low-infrared characteristic capabilities, it also needs to exhibit stable performance within a wide frequency band, while also having good mechanical strength, lightweight and environmental adaptability.

[0003] In addition to the co-extrusion method of plastic polymer substrates, traditional absorbing material preparation technologies mainly include: coating, lamination and compounding methods. Although these methods have met some of the needs to a certain extent, they still have problems such as low comprehensive performance, high cost, low production efficiency, few application scenarios, and environmental pollution during production and use. The existing multi-layer co-extrusion technology using the same plastic polymer substrate can produce multi-layer structural panels on the same production line, eliminating multiple processes and complex post-processing steps, and greatly improving production efficiency; it has the characteristics of strong interlayer adhesion and stable structure, but the same polymer material is difficult to simultaneously meet the multiple high-standard requirements of polymer plastic absorbing anti-interference and low-infrared characteristic materials, such as the surface layer needs to be flame retardant, beautiful, weather-resistant and durable; the absorbing layer needs to be able to fill the absorbing blend and extrude a closed-cell microporous structure; the core layer must have high strength, and the bonding layer must be compatible and have good adhesion with different polymer resins. It is difficult to meet the requirements using the same polymer substrate for each functional layer. The key is that due to the few interfaces and multiple interface effects in the structure, the absorbing performance is insufficient, which limits the performance and application scenarios of polymer plastic absorbing anti-interference and low-infrared characteristic materials.

[0004] The patent with publication number CN114055885B discloses a multi-layer co-extruded electromagnetic shielding fluoroplastic electrical insulation corrugated pipe and its preparation method, but it only includes a surface insulation layer and an inner electromagnetic shielding layer. Although it is made by the same polymer material multi-layer co-extrusion process, there is no similarity other than this. In the existing composite absorbing materials, multiple absorbing materials need to be added at the same time to improve the absorbing performance so as to achieve the multi-band absorbing effect of the material. However, adding too much absorbing material will lead to a decrease in the strength of the absorbing layer. In addition, in the prior art, a foaming agent is often added to the absorbing layer to form a closed-cell structure, which will greatly reduce the overall strength of the material. The patent with publication number CN101899221A discloses a foamed electromagnetic absorbing composite material and a preparation method thereof. Although dielectric and magnetic dielectric absorbing materials are used in the absorbing layer and foamed to form a closed-cell structure to better absorb electromagnetic waves, the overall strength of the material is low due to the high content of these absorbing materials. At the same time, the structure is single and lacks multiple interface effects, and the absorbing performance is limited. If used in outdoor equipment and buildings, it is very easy to be damaged in harsh environments. Therefore, there is often a certain contradiction between the absorbing performance and mechanical strength of the existing materials, especially in the balance between the multi-band absorbing effect and the material structure strength and the interlayer adhesion. The traditional design is difficult to meet the needs of complex applications.

[0005] Based on the above technical problems, it is of great significance to develop a polymer plastic material with wave absorption, anti-interference and low infrared characteristics, good electromagnetic shielding performance, light weight and durability, which can meet multi-functional requirements, produce environmentally friendly, efficient and low-cost materials and their preparation methods. Summary of the invention

[0006] The purpose of the present invention is to provide a polymer plastic absorbing anti-interference and low-infrared characteristic material and a preparation method thereof. The polymer plastic absorbing anti-interference and low-infrared characteristic material is characterized by: 1: at least one layer of wave-transmitting, flame-retardant and weather-resistant surface layer; 2: at least one layer of absorbing layer with a closed-cell microporous structure made of a highly filled absorbing blend; 3: at least one layer of absorbing core layer providing structural strength; 4: at least one layer of bonding layer containing 5% to 10% of the absorbing blend, which plays a bonding role between the functional layers and has reflective and absorbing effects.

[0007] The production process uses multiple extruders equipped with melt pumps to form high-molecular plastic wave-absorbing, anti-interference and low-infrared characteristic materials with excellent wave-absorbing performance and high structural strength through a multi-channel co-extrusion mold.

[0008] The purpose of the present invention is achieved by the following technical scheme. In the first aspect, the present invention provides a polymer plastic wave absorbing anti-interference and low infrared characteristic material, wherein the polymer plastic wave absorbing anti-interference and low infrared characteristic material comprises at least 4 functional layers, wherein the functional layers have different formulas and properties, and the functional layers of the same formula are extruded by the same extruder, wherein the functional layers comprise, from the surface layer to the inner layer, the following in order: At least one surface layer, the surface layer has flame retardant, weather-resistant, durable and beautifying properties; At least one wave absorbing layer, wherein the wave absorbing layer contains 15% to 30% of a wave absorbing blend, and the wave absorbing layer comprises a closed-cell microporous structure; At least one core layer, the core layer contains 5% to 10% of a resistive absorbing material that absorbs waves and conducts heat, which is generally a reinforcing absorbing material such as conductive carbon black and carbon nanotubes. The density and strength of the core layer are much greater than those of the absorbing layer; the core layer accounts for 30% to 60% of the thickness of the polymer plastic absorbing, anti-interference and low infrared characteristic material; At least one bonding layer is made of maleic anhydride grafted modified PE and PP resin and contains 5% to 15% of a wave absorbing blend; the bonding layer is located between the surface layer, the wave absorbing layer and the core layer.

[0009] Preferably, the substrates of the surface layer, the absorbing layer and the core layer are respectively one of AES, ASA, LDPE, HDPE, PP and ABS. The substrates of at least two functional layers in the multilayer structure of polymer plastic absorbing anti-interference and low infrared characteristic material are different.

[0010] Preferably, the base material of the surface layer is HDPE, which contains 5% flame retardant and 3% anti-UV agent, masterbatch and other additives; the base material of the wave-absorbing layer is LDPE, which contains 30% wave-absorbing blend.

[0011] Preferably, the core layer is HDPE, which is doped with 5% carbon nanotubes or 5% conductive carbon black.

[0012] Preferably, the substrate of the bonding layer is PE-g-MAH, which contains 10% of the absorbing blend.

[0013] Preferably, the base material of the surface layer is AES, the base material of the absorbing layer is LDPE, and the base material of the core layer is ABS; the surface layer contains 2% flame retardant and weathering agent masterbatch; the absorbing layer contains 30% absorbing blend, and the core layer contains 5% conductive carbon black or 5% carbon nanotubes.

[0014] Furthermore, the functional layer also includes an adhesive layer, and the adhesive layer contains 10% of the wave-absorbing blend.

[0015] Furthermore, the interlayer structure of the polymer plastic absorbing, anti-interference and low-infrared characteristic material can be an asymmetric structure or a symmetric structure. The asymmetric structure form is: ANBNC (A, B, C represent the surface layer, the absorbing layer, the core layer, respectively, and N represents the bonding layer); the symmetric structure form can be: ANBNCNBNA.

[0016] Furthermore, the base material of the surface layer and the core layer is HDPE, the wave absorbing layer is LDPE, and the bonding layer N between the surface layer, the wave absorbing layer and the core layer is PE-g-MAH containing "wave absorbing blend".

[0017] In a second aspect, the present invention provides a method for preparing a polymer plastic wave absorbing, anti-interference and low infrared characteristic material, which comprises the following steps: S1. Select and weigh the base resin and additives of each functional layer respectively, and blend the base resin and the functional material through a twin-screw extruder to form granules; the functional layer includes a surface layer, an absorbing layer, a core layer, and a bonding layer. Except for the surface layer, each functional layer contains absorbing materials. During the blending and granulation process, the core layer only contains dielectric absorbing materials; the absorbing layer and the bonding layer contain different proportions of absorbing blends. S2. The absorbing layer includes a closed-cell microporous structure formed during the co-extrusion process.

[0018] S3, each functional layer extruder is equipped with a melt pump to stably and evenly extrude the blended and granulated product in step S1 to form each functional layer; S4, co-extruding each functional layer into an integrated high-strength multi-layer structure through a multi-channel die; S5, cooling and cutting the multilayer structure of step S4 to obtain the polymer plastic wave absorbing, anti-interference and low infrared characteristic material.

[0019] Preferably, in step S1, the substrates of the surface layer, the absorbing layer and the core layer are the same, but the functional substances contained are different, and the independent bonding layer N layer is made of pe-g-mah containing absorbing substances. Preferably, in step S1, the substrates of the functional layers are different, such as the surface layer substrate is AES, the absorbing layer substrate is LDPE, the core layer is ABS, and the bonding layer N layer is PE-G-MAH; the bonding layer N layer substrate is one of maleic anhydride grafted PE and PP resin, and 5% to 15% of the absorbing blend is added during the blending and granulation process. Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects: First, the present invention introduces an independent bonding layer into the multi-layer co-extruded material and adds an absorbing blend therein, which can not only effectively bond different polymer materials, but also significantly improve the multiple absorbing, reflecting and thermal conductive properties of the material due to the interface effect of the material; the existing multi-layer co-extruded material has the same base material for each functional layer, a single structure and material, and low absorbing performance and material strength.

[0020] Second, the present invention uses maleic anhydride grafted resin as the bonding layer between the functional layers, which has good applicability to various materials, high interlayer bonding strength, and stable overall material structure; since the substrates of the functional layers are different and the compatibility between different substrates is poor, an independent bonding layer is introduced between the functional layers to enhance the bonding force of each layer, thereby making the functional layer more flexible, simple and stable in formulation and structural design; the bonding layer contains maleic anhydride grafted resin and an absorbing blend, which not only improves the interlayer bonding strength, but also further improves the overall absorbing and thermal conductivity of the material through the absorption and reflection interface effect generated by the absorbing blend.

[0021] Third, the absorbing layer of the present invention achieves excellent absorbing performance in the high, medium and low frequency ranges through the optimized compound combination of magnetic medium type absorbing materials, dielectric type absorbing materials and resistive absorbing materials (absorbing blends); it meets the needs of broadband absorbing, and at the same time, due to the thermal conductivity of the resistive absorbing material, the heat converted by the electromagnetic waves absorbed by the material itself can be effectively dissipated, reducing the infrared characteristics and material deformation of the high molecular plastic absorbing anti-interference and low infrared characteristic materials.

[0022] Fourthly, the present invention improves the multiple absorption capacity of electromagnetic waves by introducing a foaming agent into the absorbing layer to form a closed-cell microporous structure. The structure forms multiple paths inside the material, prolongs the propagation path of the electromagnetic waves, and causes multi-layer reflection, diffusion, and attenuation of the electromagnetic waves, thereby greatly improving the anti-interference performance of polymer plastic absorbing materials and the absorbing performance of low-infrared characteristic materials.

[0023] Fifth, the innermost core layer of the present invention acts as a supporting skeleton in the material, and generally adopts a polymer material with relatively large mechanical strength, such as ABS, HDPE, PP, etc., and adds 5% to 10% resistive absorbing materials such as conductive carbon black, carbon nanotubes, and polycrystalline iron fibers to further strengthen the core layer and at the same time channel the heat accumulated inside the material; the core layer is a solid structural layer, and its higher density and strength provide higher mechanical properties, such as tensile strength, compressive strength and rigidity; when subjected to external force, the core layer can effectively disperse stress, reduce structural deformation, and improve overall reliability and durability; the core layer with higher density can form a stronger frame in the composite material, reduce the compression or deformation of the absorbing layer due to its lower density, thereby ensuring the stability of the material in long-term use; the absorbing layer has a lower density and can provide good absorbing performance, while the core layer has a higher density and can play a stable supporting role. The design of the density difference between the two realizes functional division of labor, which helps to achieve a balance between absorbing performance and mechanical properties.

[0024] Sixth, the present invention adds an absorbing blend to the absorbing layer, and only adds a resistive absorbing material with a reinforcing effect to the core layer, in order to ensure the supporting strength of the core layer; and the resistive absorbing material such as conductive carbon black or carbon nanotubes added to the core layer only accounts for 5% to 10%. Since an appropriate amount of carbon black and carbon nanotubes have an excellent reinforcing effect on polymer materials, the core layer is further reinforced; the strength of the overall material is greatly improved while ensuring certain absorbing and thermal conductive properties.

[0025] Seventh, the present invention can very conveniently connect such materials together through hot-melt welding of the core layer to form various required shapes; traditional radar-absorbing stealth materials are often unable to independently build larger equipment; the thickness of the core layer of the present invention can account for 60% of the material thickness, with high strength, simple and easy hot-melt welding, and guaranteed quality. Therefore, polymer plastic radar-absorbing, anti-interference and low-infrared characteristic materials can be widely used in the construction of small, high-strength, low-cost stealth boats, vehicles, platforms, and various required equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a symmetrical distribution diagram of the first embodiment of the polymer plastic wave absorbing, anti-interference and low infrared characteristic material of the present invention; Figure 2 This is an asymmetric distribution diagram of the first embodiment of the polymer plastic wave absorbing, anti-interference and low infrared characteristic material of the present invention.

[0028] 1. Surface layer; 2. Absorbing layer; 3. Core layer; 4. Adhesive layer. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] The following describes the implementation methods of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The present invention can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention; it should be understood that the "surface layer", "absorbing layer" and "core layer" should be arranged in order from the surface to the inside, and the bonding layer is between the different sides of the surface layer, the absorbing layer and the core layer.

[0031] Existing polymer absorbing materials generally have the problems of narrow polymer substrate selection, single material, great limitations in functional layer material and structural design, and inability to balance absorbing performance and overall strength. Adding more absorbing materials or simply using microporous structures will lead to a decrease in strength, and the adhesion between multilayer structures will also be weakened, and the various indicators of polymer plastic absorbing anti-interference and low infrared characteristic materials cannot be guaranteed. Under this premise, how to develop a polymer plastic absorbing anti-interference and low infrared characteristic material with good electromagnetic shielding performance and high structural strength, which can meet multi-functional requirements and produce efficient and environmentally friendly high molecular plastic absorbing anti-interference and low infrared characteristic materials has become an urgent problem to be solved in the industry.

[0032] Based on this, the embodiment of this specification proposes a polymer plastic absorbing anti-interference and low infrared characteristic material solution: the solution adopts a polymer material co-extrusion process, and co-extrudes different substrates through a specially designed multi-channel composite mold to form an absorbing material with a multifunctional layer structure of a surface layer, an absorbing layer, a core layer, and a bonding layer. The absorbing material can be in the form of a plate or a profile, and its surface layer has the characteristics of weather resistance, durability, flame retardancy, and multi-color beauty; the absorbing layer contains 15% to 30% of an absorbing blend, including a closed-cell microporous structure, which can efficiently absorb and reflect electromagnetic waves; the core layer contains 5% to 10% of a resistive absorbing material, which absorbs and conducts heat while further improving the overall strength of the material, and the bonding layer plays a connecting role between other functional layers. The bonding layer substrate is a resin with good compatibility with a variety of polymer materials, generally using maleic anhydride grafted modified PEPP, and contains 5% to 10% of an absorbing blend. The bonding of each functional layer also has an interface effect, further improving the multiple absorbing reflection and thermal conductivity of the material. Example

[0033] The present embodiment provides a polymer plastic absorbing anti-interference and low-infrared characteristic material, which includes a surface layer 1, an absorbing layer 2, a core layer 3, and an adhesive layer 4. Each functional layer is compounded into a high-performance absorbing plate and profile by a co-extrusion process. The surface layer 1 has the properties of weather resistance, durability, flame retardancy and good appearance; the absorbing layer 2 contains 15% to 30% of an absorbing blend, and the absorbing layer 2 includes a closed-cell microporous structure, so that the incident electromagnetic wave is reflected, diffused, and attenuated multiple times, greatly improving the absorbing performance; the core layer 3 contains 5% to 10% of conductive carbon black, carbon fiber, and carbon nanotube absorbing materials, which further enhances the material's absorbing and thermal conductivity. At the same time, due to the excellent reinforcing properties of conductive carbon black, carbon fiber, and carbon nanotube absorbing materials for plastics, the strength index of the core layer 3 is improved, and the base material density and strength of the core layer 3 are much greater than the base material density and strength of the absorbing layer 2; the bonding layer 4 is a maleic anhydride grafted resin containing 5% to 15% of the absorbing blend as the bonding layer 4 and is located between the other functional layers; the maleic anhydride grafted resin is preferably PE-g-MAH and PP-g-MAH; the base material of the functional layer is two or more of AES, ASA, LDPE, HDPE, PP and ABS; each functional layer can be a multilayer, and preferably, the absorbing layer 2 and the core layer 3 can be combined into one.

[0034] In a preferred embodiment, antioxidants and anti-UV agents are added to the surface layer 1 to improve corrosion resistance and anti-aging properties; preferably, the surface layer 1 achieves a multi-color appearance by adding pigments (such as masterbatches); further, flame retardants (such as aluminum hydroxide, antimony trioxide) are added to the surface layer 1 to improve fire resistance.

[0035] It should be noted that the magnetic dielectric absorbing material described in this application may be ferrite (Ni-Zn, Mn-Zn ferrite), soft magnetic metal (such as iron silicon alloy) or magnetic nanoparticles (such as Fe3O4, CoFe2O4), which mainly absorbs electromagnetic waves through magnetic loss and is suitable for medium and low frequency ranges (1GHz to 18GHz); the dielectric absorbing material may be high dielectric constant ceramics (such as BaTiO3, SrTiO3), silicon nitride and iron nitride, etc., which mainly absorb electromagnetic waves through polarization loss and are suitable for high-frequency absorption; the resistive absorbing material mainly absorbs electromagnetic waves by interaction with the electric field. Commonly used absorbing materials include carbon black, carbon fiber and carbon nanoparticles. Tubes, silicon carbide, conductive graphite, metal short fibers, etc. The absorbing layer 2 contains a specially designed absorbing blend, which can effectively improve the wide-band absorbing ability of the material. For example, blending nano-magnetic particles with nano-conductive media (such as Fe3O4 and graphene), or compounding magnetic materials with polymer matrices (such as Ni-Zn ferrite and polymer), can all improve the absorbing performance; since each sub-functional layer structure contains absorbing and heat-conducting materials such as doped ferrite, conductive carbon black, carbon nanotubes, hydroxyl iron powder, etc., the high-frequency electromagnetic waves acting on the surface of the material can be absorbed and converted into heat energy, which is quickly dissipated and exported by the heat-conducting material, greatly reducing the infrared radiation signal intensity of the material.

[0036] This embodiment also provides a method for preparing a polymer plastic wave absorbing, anti-interference and low infrared characteristic material, which comprises the following steps: S1. Select the substrate and additives of each functional layer, and blend the substrate and the functional material through at least one twin-screw extruder to granulate; the functional layer includes a surface layer 1, an absorbing layer 2, a core layer 3, and a bonding layer 4; the functional material includes absorbing materials with various properties; during the blending and granulation process, the absorbing layer 2 contains a compounded absorbing blend, the core layer 3 contains one of conductive carbon black, carbon fiber, and carbon nanotubes, and the bonding layer 4 contains a compounded absorbing blend.

[0037] S2, the absorbing layer 2 comprises a closed-cell microporous structure, which is formed by an extrusion foaming process; S3. Functional layers with the same formulation are extruded by the same single-screw extruder equipped with a melt pump. The products blended and granulated in step S1 are extruded evenly and stably to form each functional layer. Each bonding layer 4 is also extruded separately by an extruder equipped with a melt pump.

[0038] S4, co-extruding each functional layer into a multi-layer composite structure through a specially designed multi-channel die; S5, cooling and cutting the multilayer structure of step S4 to obtain a polymer plastic wave absorbing, anti-interference and low infrared characteristic material.

[0039] It should be noted that not all polymer materials can serve as the substrate in step S1 of this method. The substrate is selected from polymer materials with high cost performance, good compatibility with absorbing materials, and similar melt index and melt temperature. Preferably, polymer materials such as AES, ASA, LDPE, HDPE, PP and ABS are selected. Among them, the surface layer 1 is preferably made of weather-resistant, durable and flame-retardant polymer materials such as AES and ASA, the absorbing layer 2 is preferably LDPE with good filling performance, and the core layer 3 is preferably ABS or PP, HDPE with high strength. The optimized design is performed according to the rheological properties, viscosity matching and flow rate control of different materials. With the support of the melt pump and the bonding layer 4, the uniform distribution of multi-layer structure, multiple materials and polymer resins of different densities is ensured to avoid uneven thickness and interface stratification problems. Example

[0040] In this embodiment, compared with the first embodiment, the base material of the surface layer 1 is HDPE, the base material of the absorbing layer 2 is LDPE, and the base material of the core layer 3 is ABS; the surface layer 1 contains flame retardants and weather-resistant masterbatches; the absorbing layer 2 contains a specially designed absorbing blend; the core layer 3 contains 5% conductive carbon black or 5% carbon nanotubes; preferably, the absorbing blend formula of the absorbing layer 2 can flexibly adjust the proportion of each absorbing material as needed to meet the requirements of performance indicators, and the absorbing layer 2 has a closed-cell microporous structure, which increases the specific surface area and multiple absorbing and reflecting capabilities, and further improves the absorbing efficiency.

[0041] In a preferred embodiment, the functional layer also includes an adhesive layer 4, the substrate of the adhesive layer 4 is a maleic anhydride grafted resin, and the adhesive layer 4 contains 5% to 15% of an absorbing blend; the adhesive layer 4 not only has a bonding effect, but also has an interface effect, and has the effects of absorbing, reflecting and conducting heat; the surface layer 1, the absorbing layer 2 and the core layer 3 are connected by the adhesive layer 4; the adhesive layer 4 is extruded by a special extruder with a melt pump, and the thickness is 0.3mm-3mm; since the substrates of each functional layer are different, the functional layers of the same formula are extruded by the same extruder, and the raw materials of each functional layer must be blended and granulated by a twin-screw extruder before the co-extrusion process; in this scheme, the adhesive layer 4 as a functional layer improves the interlayer bonding strength, and the absorption and reflection interface effect generated by the absorbing substance contained in it further improves the material's absorption, reflection and thermal conductivity.

[0042] In a preferred embodiment, Figure 1The polymer plastic absorbing anti-interference and low-infrared characteristic material shown is symmetrically distributed as ANBNCNBNA, A is the surface layer 1, B is the absorbing layer 2, C is the core layer 3, and N is the bonding layer 4; the polymer plastic absorbing anti-interference and low-infrared characteristic material can also be in other symmetrical distribution structures, such as: ANBNA, there is no core layer 3 (C layer), the absorbing layer 2 (B layer) also has the function of the core layer 3 (C layer), the same letters represent the same material and are extruded by the same extruder; it should be understood that the polymer plastic absorbing anti-interference and low-infrared characteristic material is also symmetrically distributed only for preference, and cannot be understood as a limitation on the protection scope of the independent claims of the present application, the polymer plastic absorbing anti-interference and low-infrared characteristic material can also be asymmetrically distributed, such as: ANB, there is no core layer 3 (C layer), the absorbing layer 2 (B layer) also has the function of the core layer 3 (C layer); the symmetrical structures of ANBNC and ANBNCNBNA have the characteristics of many flow channels and more complex molds, but have good omnidirectional absorbing and shielding performance; and as Figure 2 As shown, the asymmetric structure of ANBNC is directional, but the mold has fewer runners and is simple to manufacture.

[0043] In the symmetrically distributed polymer plastic absorbing anti-interference and low-infrared characteristic material of this scheme, since the core layer 3 is at the most central position and the thickness of the core layer 3 is 30% to 60% of the total thickness of the material, the core layer 3 can be welded together by various methods of hot melt welding. Since the structural strength of the core layer 3 is relatively high, the welding quality can be guaranteed. Therefore, this material can be used to build high-strength, low-cost unmanned stealth boats, vehicles, platforms, various absorbing stealth, and electromagnetic shielding equipment.

[0044] This embodiment also provides a method for preparing a polymer plastic absorbing, anti-interference and low-infrared characteristic material. Compared with the first embodiment, in step S1, the substrates of each functional layer are different, and the functional layer also includes a bonding layer 4. The substrate of the bonding layer 4 is a maleic anhydride grafted resin, and 5% to 15% of the absorbing blend is added during the blending and granulation process; in step S4, 4 single-screw extruders with melt pumps are used to extrude the functional layers that have been mixed and granulated through a specially designed multi-channel mold to form a multi-layer structure plate or profile.

[0045] In a preferred embodiment, each functional layer is extruded by four single-screw extruders with melt pumps. The surface layer 1 (A layer) is made of HDPE material containing additives such as weather-resistant flame-retardant masterbatch, with a thickness of 1 mm to 2 mm; the absorbing layer 2 (B layer) includes a closed-cell microporous structure, contains 15% to 30% of the absorbing blend, and the base resin is LDPE, with a thickness of 1 mm to 3 mm; the core layer 3 (C layer) is HDPE containing 5% conductive carbon black or carbon nanotubes, with a thickness of 8 mm to 15 mm; the bonding layer 4 (N layer) is a 5% conductive carbon black or carbon nanotube containing HDPE, with a thickness of 8 mm to 15 mm. ~15% PE-g-MAH of absorbing material, the thickness of the bonding layer 4 is 0.1mm~0.3mm; the HDPE composite absorbing thick plate extruded by this method is weather-resistant and durable, and this plate can be used to build small stealth manned and unmanned boats, vehicles, and various equipment requiring electromagnetic shielding through hot-melt welding; the hull and equipment built with the polymer plastic absorbing anti-interference and low-infrared characteristic materials of this embodiment are light in weight, high in strength, and have excellent multi-band radar and infrared stealth performance, and have strong corrosion resistance and durability, meeting the needs of a variety of complex use environments. The embodiments of this specification are designed and produced through a co-extrusion process with a multi-layer structure of polymer plastic absorbing, anti-interference and low-infrared characteristic materials with a closed-cell microporous layer, combining the advantages of various absorbing materials, optimizing the interface adhesion and multiple interface effects, and greatly improving the material's absorbing, stealth, and electromagnetic shielding performance; the material has the characteristics of light weight, high strength, energy saving and environmental protection, and low cost, and can be widely used in absorbing, stealth, electromagnetic shielding, military equipment, communications, electronics and other fields, providing a new solution for the development of polymer materials in the fields of absorbing, stealth, and electromagnetic shielding.

[0046] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments. The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A polymer plastic wave absorbing, anti-interference and low infrared characteristic material, characterized in that: The invention comprises a plurality of functional layers, wherein the functional layers include: At least one layer; At least one absorbing layer, the absorbing layer contains an absorbing blend, the absorbing blend includes magnetic medium type, dielectric type and resistive type absorbing materials, a foaming agent is added to the raw materials of the absorbing layer before molding, and a closed-cell microporous structure is formed during the extrusion molding stage; At least one core layer, wherein the core layer contains 5% to 10% of a resistive absorbing material, wherein the resistive absorbing material is one or more of conductive carbon black, carbon nanotubes, and polycrystalline iron fibers, and the core layer accounts for 30% to 60% of the thickness of the polymer plastic absorbing, anti-interference and low infrared characteristic material; At least one bonding layer, the base material of the bonding layer is maleic anhydride grafted modified PE or PP resin, and contains 5% to 15% of absorbing blend; the bonding layer is located between two different layers among the surface layer, absorbing layer and core layer.

2. The polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 1, characterized in that: The base materials of the surface layer, the absorbing layer and the core layer are two or more of AES, ASA, ABS, LDPE, HDPE and PP, and at least two of the base materials of the surface layer, the absorbing layer, the core layer and the bonding layer are different from each other.

3. The polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 2, characterized in that: The base material of the surface layer is AES, the base material of the wave-absorbing layer is LDPE, and the base material of the core layer is ABS; flame retardant, weathering agent and masterbatch are added to the surface layer; and the wave-absorbing layer contains 15% to 30% of the wave-absorbing blend.

4. The polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 1, characterized in that: The core layer contains conductive carbon black or carbon nanotubes or polycrystalline iron fibers in a total amount not exceeding 10%; the bonding layer contains 5% to 15% of a wave absorbing blend.

5. The polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 4, characterized in that: The functional layer includes at least one core layer and at least two surface layers, an absorbing layer, and an adhesive layer; the surface layer, the absorbing layer, and the adhesive layer are symmetrically distributed with the core layer as the core, and the functional layers are compounded together through a multi-layer co-extrusion die.

6. The polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 1, characterized in that: The substrates of the surface layer, the absorbing layer and the core layer are all HDPE, and the absorbing layer and the core layer contain 2% of PE-g-MAH or PP-g-MAH compatibilizer in addition to the absorbing material.

7. The polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 6, characterized in that: The base material of the surface layer is HDPE, which contains 2% PE-g-MAH, 5% to 15% flame retardant, 1% antioxidant and 3% masterbatch; the base material of the wave absorbing layer is HDPE, which contains 20% wave absorbing blend.

8. A method for preparing a polymer plastic wave absorbing, anti-interference and low infrared characteristic material, characterized in that: The following steps are involved: S1. Weigh the base resin and additives of each functional layer, and blend and granulate the base resin of each functional layer with the functional material through a twin-screw extruder; the functional layer includes a surface layer, an absorbing layer, a core layer, and a bonding layer, and the functional material includes an absorbing blend and various processing aids; during the blending and granulation process, the absorbing layer and the bonding layer contain different proportions of the absorbing blend, and the core layer contains only no more than 10% of a resistive absorbing material; S2, adding a foaming agent to the raw material of the absorbing layer to form a closed-cell microporous structure during the extrusion molding process; S3, the functional layers with the same formula are made of the same extruder, and each extruder is equipped with a melt pump to extrude the blended and granulated product in step S1 through a multi-layer co-extrusion die to form a high-molecular plastic wave-absorbing, anti-interference and low-infrared characteristic material with each functional layer firmly bonded; S4, co-extruding each functional layer into a multi-layer structure of a polymer plastic wave absorbing, anti-interference and low infrared characteristic material through a multi-channel die, in the shape of a plate and a profile; S5, cooling and cutting the multilayer structure of step S4 to obtain a high molecular plastic wave absorbing, anti-interference and low infrared characteristic material of required specifications.

9. The method for preparing the polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 8, characterized in that: In the step S1, the base materials of the functional layers except the bonding layer are the same, and during the blending and granulation process, the surface layer, the absorbing layer and the core layer contain 2% of PE-g-MAH or PP-g-MAH compatibilizer.

10. The method for preparing the polymer plastic wave absorbing, anti-interference and low infrared characteristic material according to claim 9, characterized in that: In the step S1, the substrates of the functional layers are different, and the functional layers further include a bonding layer, the substrate of the bonding layer is maleic anhydride grafted resin, and the bonding layer contains 5% to 15% of the absorbing blend.

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