阅读说明：本技术 一种磁性纸基材料及其制备方法 (Magnetic paper base material and preparation method thereof ) 是由 胡健 王宜 龙金 王浩 沈俊奕 于 2020-05-09 设计创作，主要内容包括：本发明涉及一种磁性纸基材料及其制备方法。所述材料是由磁性沉析浆粕、高性能聚合物纤维和导电纤维组成,其中所述磁性沉析浆粕占所述磁性纸基材料的重量百分含量为100-10wt％,优选为100-50wt％；所述高性能聚合物纤维占所述磁性纸基材料的重量百分含量为0-90wt％,优选为0-50wt％；所述导电纤维占所述磁性纸基材料的重量百分含量为0-25wt％,优选为0-5wt％。本发明的材料可以有效解决磁性颗粒易脱落的问题,电磁性能稳定、吸收率高、质量轻、耐腐蚀且强度优异,其制备的蜂窝材料性能优异,是一种先进的磁性材料。(The invention relates to a magnetic paper base material and a preparation method thereof. The material consists of magnetic precipitation pulp, high-performance polymer fiber and conductive fiber, wherein the magnetic precipitation pulp accounts for 100-10 wt% of the magnetic paper base material, and preferably 100-50 wt%; the high-performance polymer fiber accounts for 0-90 wt%, preferably 0-50 wt% of the magnetic paper base material; the weight percentage of the conductive fiber in the magnetic paper base material is 0-25 wt%, preferably 0-5 wt%. The material can effectively solve the problem that magnetic particles are easy to fall off, has stable electromagnetic performance, high absorptivity, light weight, corrosion resistance and excellent strength, and the prepared honeycomb material has excellent performance and is an advanced magnetic material.)

1. a magnetic paper base material, which consists of magnetic precipitation pulp, high-performance polymer fiber and conductive fiber, wherein the magnetic precipitation pulp accounts for 100-10 wt%, preferably 100-50 wt% of the magnetic paper base material; the high-performance polymer fiber accounts for 0-90 wt%, preferably 0-50 wt% of the magnetic paper base material; the weight percentage of the conductive fiber in the magnetic paper base material is 0-25 wt%, preferably 0-5 wt%.

2. The magnetic paper base material according to claim 1, wherein the magnetic precipitation pulp is prepared by a precipitation process by mixing magnetic particles and a polymer solution;

preferably, the amount of the magnetic particles added is 1 to 2000 wt%, preferably 50 to 1000 wt%, more preferably 100 to 400 wt% of the weight of the polymer in the polymer solution.

3. The magnetic paper based material according to claim 2, wherein the polymer in the polymer solution is a low dielectric loss polymer selected from one or more of high performance polymers such as poly-p-Phenylene Benzobisoxazole (PBO), aramid and polyimide, preferably poly-p-Phenylene Benzobisoxazole (PBO);

preferably, the magnetic precipitation pulp has a freeness of 32 to 80 ° SR, preferably 40 to 80 ° SR.

4. A magnetic paper based material according to claim 2 or 3, wherein the magnetic particles are selected from one or more of carbonyl iron, ferrite, sendust, iron, cobalt, nickel and the like.

5. The magnetic paper based material according to any of claims 2 to 4, wherein the magnetic particles are sheet-like in shape with a size range of: a thickness of less than 20 μm, preferably less than 1 μm, and a length and width of 20-300 μm, preferably 150-200 μm; spherical, wherein the diameter ranges are: 5nm-200 μm, preferably 10nm-20 μm; or fibrous, wherein the diameter ranges are: 10nm-150 μm, length 150 μm-6mm, preferred diameter range is 10nm-30 μm, length 150 μm-3 mm.

6. The magnetic paper base material according to any of claims 1 to 5, characterized in that the high performance polymer fibers are selected from one or more of PBO fibers, aramid fibers and polyimide fibers.

7. The magnetic paper based material according to any one of claims 1 to 6, wherein the electrically conductive fibers are selected from one or more of carbon fibers and nickel-plated carbon fibers; preferably, the length of the conductive fibers is 0.5mm to 15mm, preferably 3mm to 9 mm.

8. A method of manufacturing a magnetic paper based material according to any one of claims 1 to 7, the method comprising the steps of:

(1) preparing magnetic precipitation pulp from magnetic particles and a polymer solution through a precipitation process;

(2) and (2) adding the magnetic precipitation pulp, the high-performance polymer fiber and the conductive fiber prepared in the step (1) into a fluffer according to a ratio for fluffing, then using a sheet-making device or forming a single layer or multiple layers on a forming wire of the paper machine for dewatering, forming and squeezing, and finally drying to constant weight to prepare the magnetic paper base material.

9. The method of claim 8, wherein in step (2), the magnetic precipitation pulp, the high performance polymer fiber and the conductive fiber prepared in step (1) are added into a fluffer according to a certain proportion for fluffing, then are formed by a sheet machine or a forming wire of the paper machine in a plurality of layers, preferably 3-4 layers, for dewatering, forming and pressing, and finally are dried to constant weight to prepare the magnetic paper base material.

10. The production method according to claim 8 or 9, wherein, when the multilayer formation is performed in step (2), the magnetic precipitation pulp accounts for 0 to 10 wt%, preferably 0 to 3 wt%, of the magnetic paper-based material, the conductive fiber accounts for less than 3 wt%, and the balance is high-performance polymer fiber in the upper and lower surface layers; in the middle layer, the weight percentage of the magnetic precipitation pulp in the magnetic paper base material is 10-100 wt%, the weight percentage of the conductive fiber in the magnetic paper base material is 0-25 wt%, and the balance is high-performance polymer fiber.

Technical Field

The invention relates to a magnetic paper base material and a preparation method thereof.

Background

The magnetic paper base material is prepared by taking high-performance synthetic fibers as a framework, mixing the high-performance synthetic fibers according to a certain proportion, adding magnetic particle substances as a wave-absorbing medium, and preparing paper by a wet forming method, wherein two problems need to be considered during design: 1) the electromagnetic wave needs to pass through the surface of the material as completely as possible, so that the reflection is reduced; 2) when electromagnetic waves enter the material, the energy of the electromagnetic waves is lost as much as possible, so that the interference of the electromagnetic waves is reduced. The honeycomb structural member is processed into a honeycomb structural member, and can well meet the requirements of structure and function integration, so that the honeycomb structural member has wide application prospect in the fields of aviation and aerospace. At present, according to the forming process and the bearing capacity, the coating type and the structural type can be divided into two categories.

The coating type wave-absorbing material is prepared by taking a high molecular solution, emulsion or liquid high polymer as a matrix and dispersing particles with electromagnetic loss as a wave-absorbing agent and other additional components in the matrix, and has the defects of narrow absorption band, large weight, low bonding strength, poor weather resistance and the like. The structural wave-absorbing material has the dual functions of bearing and absorbing waves and comprises a laminated plate type, a honeycomb sandwich type, a foam sandwich type and a fiber woven structure at present. However, the conventional wave-absorbing sandwich material, such as a honeycomb sandwich material, is mainly prepared by taking a paper honeycomb as a substrate and impregnating a glue solution doped with a wave-absorbing agent, and the preparation method has a complex process, and if the wave-absorbing agent needs to be uniformly dispersed in the glue solution, the uniform impregnation is often difficult to realize when the glue solution contains the wave-absorbing agent, so that the gradient control of electromagnetic parameters is difficult to realize, the optimization of impedance matching characteristics is not facilitated, and the broadband wave-absorbing effect is not ideal. In addition, the wave-absorbing sandwich material prepared by the method is easy to have the phenomenon of absorbent peeling off after being used for a long time, pollutes the surrounding electromagnetic environment and influences the stability of the wave-absorbing performance of the wave-absorbing sandwich material.

U.S. Pat. No. 4,234,378 mentions the preparation of magnetic paper from barium ferrite powder or strontium ferrite powder by adding the ferrite powder to synthetic resin such as SBR/NBR polyvinyl acetate, polyacrylate, which contains water-soluble or emulsifiable organic polymer electrolyte such as polyamine polyethyleneimine. Although this method increases the uniformity of ferrite dispersion in the resin, it still cannot avoid the risk of high temperature and falling off.

Patent No. CN1125797A discloses a method for making magnetic paper, which comprises attaching magnetic material to the interior or surface of paper, adding appropriate amount of powdered ferrimagnetic material into paper pulp, making paper, and then performing magnetic treatment, or directly spraying a layer of magnetic material powder on the surface of paper, and then performing magnetic treatment to obtain magnetic paper.

Patent No. CN105401484A proposes that composite wave absorbing agent components such as nickel powder, silicon carbide, ferrite, glass fiber, etc. are added into plant fiber to prepare absorption type electromagnetic shielding paper. However, the strength and tolerance of the plant fiber are poor, so that the material cannot be used in a severe environment, and the use environment of the material is limited.

Patent No. CN107418512A discloses a method for preparing an ultrathin paper-based wave-absorbing material, which comprises using a multi-walled carbon nanotube as a carrier, acidifying with concentrated nitric acid to generate oxygen-containing groups on the surface of the carbon nanotube, uniformly embedding cobalt-nickel ferrite nanoparticles on the carbon nanotube under the action of electrostatic attraction between metal ions and the oxygen-containing groups to generate a cobalt-nickel ferrite carbon nanotube with good wave-absorbing effect, and finally manufacturing the cobalt-nickel ferrite carbon nanotube and recycled paper fibers to obtain the ultrathin paper-based wave-absorbing material. The method has complicated process and limited surface area of the carbon nano tube, and the performance of the carbon nano tube can be influenced by excessive acidification treatment, so that the strength of the whole material is low.

Chinese patent CN104404814A mentions that the paper with wave absorbing property is made by mixing fiber wave absorbing agent and wave transmitting fiber and making paper through paper making process, wherein the paper also contains granular or irregular-shaped wave absorbing agent, such as metal powder, carbon black, ceramic powder, ferrite powder, hollow microspheres, etc. Because the density difference between the wave absorbing agent and the wave-transmitting fiber is large, the wave absorbing agent and the wave-transmitting fiber are not uniformly dispersed in the dispersing process, and the magnetic particles have small sizes and large density, the retention rate is low because the magnetic particles easily penetrate through meshes in the papermaking process, and the exposed magnetic particles are oxidized and rusted due to contact with air, so that the wave absorbing performance of the material is influenced.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides a magnetic paper base material with designable electromagnetic performance and a preparation method thereof.

The invention is realized by the following technical scheme.

In one aspect, the invention provides a magnetic paper base material, which is composed of magnetic precipitation pulp, high-performance polymer fiber and conductive fiber, wherein the magnetic precipitation pulp accounts for 100-10 wt%, preferably 100-50 wt% of the magnetic paper base material; the high-performance polymer fiber accounts for 0-90 wt%, preferably 0-50 wt% of the magnetic paper base material; the weight percentage of the conductive fibers in the magnetic paper base material is 0-25 wt%, preferably 0-5 wt%;

preferably, the magnetic precipitation pulp is prepared by a precipitation process of magnetic particles and a polymer solution;

preferably, the amount of the magnetic particles added is 1 to 2000 wt%, preferably 50 to 1000 wt%, more preferably 100 to 400 wt% of the weight of the polymer in the polymer solution.

Preferably, the polymer in the polymer solution is a polymer with low dielectric loss, and is selected from one or more of high-performance polymers such as poly-p-Phenylene Benzobisoxazole (PBO), aramid fiber and polyimide, and is preferably poly-p-Phenylene Benzobisoxazole (PBO);

preferably, the magnetic precipitation pulp has a freeness of 32 to 80 ° SR, preferably 40 to 80 ° SR.

Preferably, the magnetic particles are selected from one or more of carbonyl iron, ferrite, iron-silicon-aluminum, iron, cobalt, nickel and the like.

Preferably, the magnetic particles may be in the shape of flakes, wherein the size range is: a thickness of less than 20 μm, preferably less than 1 μm; the length and width are 20-300 μm, preferably 150-200 μm; or spherical, wherein the diameter range is: 5nm-200 μm, preferably 10nm-20 μm; it may also be fibrous, wherein the diameter ranges are: 10nm to 150 μm, a length of 150 μm to 6mm, preferably in the range of 10nm to 30 μm in diameter, 150 μm to 3mm in length and various irregular shapes.

Preferably, the high performance polymer fibers are selected from one or more of PBO fibers, aramid fibers and polyimide fibers.

Preferably, the conductive fibers are selected from one or more of carbon fibers and nickel-plated carbon fibers; preferably, the length of the conductive fibers is 0.5mm to 15mm, preferably 3mm to 9 mm.

In another aspect, the present invention provides a method for preparing the magnetic paper-based material, including the steps of:

(1) preparing polymer precipitation pulp containing magnetic particles, namely the magnetic precipitation pulp, from the magnetic particles and the polymer solution through a precipitation process; the magnetic particles are added during the precipitation of the polymer solution, which is carried out by conventional preparation methods, as described in detail in, for example, Morgan patent No. 2,999,788.

(2) And (2) adding the magnetic precipitation pulp, the high-performance polymer fiber and the conductive fiber prepared in the step (1) into a fluffer according to a ratio for fluffing, then using a sheet-making device or forming a single layer or multiple layers on a forming wire of the paper machine, dehydrating, forming and squeezing, and finally drying to constant weight to prepare the magnetic paper base material.

Preferably, in the step (2), the magnetic precipitation pulp, the high-performance polymer fiber and the conductive fiber prepared in the step (1) are added into a fluffer according to the proportion for fluffing, then a plurality of layers, preferably 3-4 layers, are formed on a forming wire of the paper machine by using a sheet machine, and are dewatered, formed and pressed, and finally dried to constant weight, so that the magnetic paper base material is prepared.

Preferably, when the multilayer forming is performed in the step (2), in the upper and lower surface layers, the magnetic precipitation pulp accounts for 0-10 wt%, preferably 0-3 wt% of the magnetic paper base material, the conductive fiber accounts for less than 3 wt% of the magnetic paper base material, and the balance is high-performance polymer fiber; in the middle layer, the weight percentage of the magnetic precipitation pulp in the magnetic paper base material is 10-100 wt%; the weight percentage of the conductive fiber in the magnetic paper base material is 0-20 wt%, and the rest is high-performance polymer fiber.

The invention has the following advantages:

the invention adopts carbonyl iron, ferrite, iron-silicon-aluminum, iron, cobalt, nickel and other magnetic particles as wave absorbing agents, has the advantages of high magnetization intensity, thermal mechanical stability and the like, and the prepared material has the characteristics of high absorptivity, thin matching thickness and the like.

The polymer precipitation pulp adopted by the invention has excellent performances such as low density, high strength, high modulus, high heat resistance, good dielectric property, chemical stability and the like, the magnetic particles are added in the preparation process of the precipitation pulp, different electromagnetic parameters are designed by adjusting the addition amount of the magnetic particles, then the magnetic precipitation pulp is mixed with the high-performance polymer fiber, and the wet papermaking process is adopted for one-step forming, so that the process is simple. The magnetic particles are added in the process of preparing the precipitation pulp, so that the magnetic particles are firmly attached, the problems of difficult dispersion and low retention rate caused by large density difference in the papermaking process are solved, and the dispersion uniformity and the retention rate are improved. In addition, because the magnetic particles are firmly wrapped, the contact with the air can be effectively isolated, thereby preventing the magnetic particles from being oxidized and rusted and avoiding influencing the electromagnetic performance of the magnetic particles. The dielectric constants of the upper surface layer and the lower surface layer can be controlled by a multi-layer forming mode, so that the wave-transmitting function is achieved, the middle layer has a high dielectric constant, the wave-absorbing function is achieved, and the maximization of the electromagnetic wave absorption effect is achieved.

The material prepared by the invention can effectively solve the problem that magnetic particles are easy to fall off, has stable electromagnetic performance, high absorptivity, light weight, corrosion resistance and excellent strength, and the prepared honeycomb material has excellent performance and is an advanced magnetic material.

The invention utilizes a wet forming method to prepare a structural function integrated material integrating wave absorbing and bearing functions, relies on good wave absorbing and wave transmitting performance, excellent strength and heat resistance of raw materials, and realizes the designability of electromagnetic parameters by controlling the addition amount of magnetic particles and combining the magnetic particles with a wet forming technology. The prepared magnetic material effectively solves the problems of low retention rate of magnetic particles, poor dispersibility, easy oxidation and easy shedding, has stable electromagnetic performance, and meets the development requirements of 'thin, light, wide and strong' of a new generation of wave-absorbing material.

Drawings

FIG. 1 is an SEM image of carbonyl iron particles;

FIG. 2 is an SEM image of a precipitation pulp with carbonyl iron particles;

FIG. 3 is an SEM photograph of a precipitate pulp at an intermediate layer iron carbonyl content of 50 wt% in example 3, wherein A is an SEM photograph magnified 500 times; b is an SEM image magnified by 7000 times; c is SEM picture magnified 2000 times;

FIG. 4 is an SEM photograph of a precipitated pulp in example 4 in which the content of carbonyl iron in the intermediate layer was 400 wt%.

Detailed Description

The present invention will be further described with reference to the following examples. These examples are intended to help illustrate the content of the invention and not to limit the scope of the invention.

In the following examples, the electromagnetic properties were tested according to standard SJ 20152-1995 standard microwave high loss solid material complex dielectric constant and complex permeability test methods. The amounts of magnetic particles mentioned in the examples below are all percentages of magnetic particles by weight of polymer in the polymer solution.

Example 1

In the preparation process of the PBO precipitation pulp, 250 wt% of carbonyl iron particles are added, wherein the carbonyl iron particles are flaky particles with the average length and width of 1 mu m and the thickness of 50nm, the SEM picture of the carbonyl iron particles is shown in figure 1, the PBO precipitation pulp containing carbonyl iron is prepared, and the SEM picture of the obtained precipitation pulp with the carbonyl iron particles is shown in figure 2.

Basis weight 150g/m according to paper design²Making paper, mixing 90 wt% PBO precipitation pulp containing carbonyl iron particles and 10 wt% PBO fiber, defibering, dewatering, forming, squeezing, and drying to constant weight to obtain the final product with a quantitative of 147g/m²A magnetic paper base material having a thickness of 160 μm.

The retention rate of the test paper is 98%, the 3GHz dielectric constant tested by the paper is 6.30, and the dielectric loss is between 0.10; the magnetic permeability is 1.11, and the magnetic loss is 0.50. Preparing honeycombs with 2.75mm cells by using the paper, wherein the tested dielectric constant of 3GHz is 1.42, and the dielectric loss is 0.02; the magnetic permeability is 1.03, and the magnetic loss is 0.10. The shrinkage of the paper in hot dimension at 300 ℃ is 0.

Comparative example 1

Basis weight 150g/m according to paper design²The paper is made, 65 wt% carbonyl iron particles, 25 wt% PBO precipitation pulp and 10 wt% PBO fiber are directly mixed and defibered, the carbonyl iron particles are sheet-shaped particles with the average length and width of 1 μm and the thickness of 50nm, the SEM picture of the carbonyl iron particles is shown in figure 1, dehydration, forming and pressing are carried out, and finally drying is carried out to constant weight, and the retention rate of the paper is 41%. A quantitative yield of 61g/m was obtained²A magnetic paper base material having a thickness of 132 μm.

The 3GHz dielectric constant of the paper test is 2.10, and the dielectric loss is between 0.01; the magnetic permeability is 1.00, and the magnetic loss is 0.001.

The paper is used for preparing 2.75mm honeycombs, and the tested dielectric constant of 3GHz is 1.5, and the dielectric loss is 0.008; magnetic permeability of 1.00 and magnetic loss of 0.001. The shrinkage of the paper in hot dimension at 300 ℃ is 0.

Example 2

And adding 200 wt% of iron-silicon-aluminum magnetic particles in the process of precipitation of the aramid pulp, wherein the thickness of the magnetic particles is 1 micrometer, and the length and the width of the magnetic particles are 150 micrometers. Then 60 wt% of aramid precipitation pulp containing iron-silicon-aluminum magnetic particles, 35 wt% of aramid fiber and 5 wt% of carbon fiber are mixed and defibered, and then dehydration, forming and squeezing are carried out, and finally drying is carried out to constant weight, so that the remaining paper is obtainedThe ratio was 98%. A quantitative content of 120g/m was obtained²A magnetic paper base material having a thickness of 80 μm.

The 3GHz dielectric constant of the paper test is 150, and the dielectric loss is 1.0; the magnetic permeability is 1.12, and the magnetic loss is 0.59. The paper is used for preparing 2.75mm honeycombs, and the tested dielectric constant of 3GHz is 7.90, and the dielectric loss is 0.09; magnetic permeability of 1.05 and magnetic loss of 0.08.

Example 3

Magnetic paper-based materials are prepared using a multi-layer forming process, wherein the multiple layers consist essentially of an upper surface layer, a lower surface layer and an intermediate layer. Mixing 50 wt% of PBO precipitation pulp and 50 wt% of PBO fiber to prepare slurry A1; mixing 88 wt% of PBO magnetic precipitation pulp (the magnetic particle carbonyl iron accounts for 50 wt% of the polymer, the SEM picture of the precipitation pulp containing the magnetic particle carbonyl iron is shown in figure 3) with 10 wt% of PBO fiber and 2 wt% of carbon fiber to prepare a slurry A2; mixing 50 wt% of PBO precipitation pulp and 50 wt% of PBO fiber to prepare slurry A3; dewatering A1, A2 and A3 respectively, stacking in the order of A1-A2-A3, squeezing, and drying to obtain 150g/m²The multilayer composite paper base material of (1).

The retention rate of the paper is 98%, the 3GHz dielectric constant 102 tested by the paper is high, and the dielectric loss is 0.9; magnetic permeability is 1.08, and magnetic loss is 0.38. The shrinkage of the paper in hot dimension at 300 ℃ is 0.

The paper is used for preparing 2.75mm honeycombs, and the tested dielectric constant of 3GHz is 5.91, and the dielectric loss is 0.67; magnetic permeability of 1.04 and magnetic loss of 0.11. The average reflectivity of the honeycomb at 2-18GHz is less than-10 dB, and the average reflectivity of the honeycomb at 4-18GHz is less than-15 dB.

Comparative example 2

Magnetic paper-based materials are prepared using a multi-layer forming process, wherein the multiple layers consist essentially of an upper surface layer, a lower surface layer and an intermediate layer. Mixing 30 wt% of PBO precipitation pulp, 50 wt% of PBO fiber and 20 wt% of carbon fiber to prepare slurry A1; mixing 88 wt% of PBO precipitation pulp (magnetic particle carbonyl iron accounts for 50 wt% of the weight of the polymer) with 10 wt% of PBO fiber and 2 wt% of carbon fiber to prepare slurry A2; precipitating 30 wt% of PBO pulp and 50 wt% of PBO pulpMixing PBO fiber and 20 wt% of carbon fiber to prepare slurry A3; mixing A1, A2 and A3, dewatering, squeezing, drying, and making into powder with a weight of 150g/m²The paper base material of (1).

The retention rate of the paper is 98%, the 3GHz dielectric constant 132 tested by the paper is high, and the dielectric loss is 0.32; the magnetic permeability is 1.02, and the magnetic loss is 0.32.

The 2.75mm honeycomb is prepared by using the paper, the average reflectivity of the 2-18GHz of the honeycomb is less than-5 dB, and the average reflectivity of the 4-18GHz of the honeycomb is less than-8 dB.

Example 4

Magnetic paper-based materials are prepared using a multi-layer forming process, wherein the multiple layers consist essentially of an upper surface layer, a lower surface layer and an intermediate layer. Wherein the three layers are all designed with different electromagnetic properties. Mixing 49 wt% of aramid precipitation pulp, 50 wt% of PBO fiber and 1 wt% of carbon fiber to prepare slurry A1; mixing 88 wt% of aramid fibrid precipitate pulp (magnetic particle carbonyl iron accounts for 400 wt% of the weight of the polymer, the SEM picture of the precipitate pulp containing the magnetic particle carbonyl iron is shown in figure 4) with 10 wt% of PBO fiber and 2 wt% of carbon fiber to prepare pulp A2; mixing 49.5 wt% of aramid fiber precipitation, 50 wt% of PBO fiber and 0.5 wt% of carbon fiber to prepare slurry A3; a1, A2 and A3 are subjected to primary dewatering forming on a three-layer paper machine, and then are pressed and dried to prepare the paper with the basis weight of 150g/m²The multilayer composite paper base material of (1).

The retention rate of the paper is 98%, the 3GHz dielectric constant tested by the paper is 128, and the dielectric loss is 0.9; the magnetic permeability is 1.10, and the magnetic loss is 0.49.

Preparing 1.83mm honeycombs from the paper, wherein the tested dielectric constant of 3GHz is 6.98, and the dielectric loss is 0.78; magnetic permeability of 1.06 and magnetic loss of 0.12. The average reflectivity of the honeycomb at 0.3-1GHz is less than-6 dB, the average reflectivity of the honeycomb at 1-2GHz is less than-8 dB, the average reflectivity of the honeycomb at 2-18GHz is less than-10 dB, and the average reflectivity of the honeycomb at 4-18GHz is less than-18 dB.

Comparative example 3

49 wt% of aramid fiber magnetic precipitation pulp (magnetic particle carbonyl iron accounts for 400 wt% of the polymer, and SEM picture of precipitation pulp containing magnetic particle carbonyl iron is shown in the specificationShown in fig. 4) was mixed with 50 wt% PBO fibers and 1 wt% carbon fibers to prepare a slurry a 1; mixing 88 wt% of aramid precipitation pulp (magnetic particle carbonyl iron accounts for 400 wt% of the polymer), 10 wt% of PBO fiber and 2 wt% of carbon fiber to prepare slurry A2; mixing 49.5 wt% of aramid precipitation pulp, 50 wt% of PBO fiber and 0.5 wt% of carbon fiber to prepare slurry A3; mixing A1, A2 and A3, dewatering, squeezing, and drying to obtain 150g/m²A paper based material.

The retention rate of the paper is 98%, the 3GHz dielectric constant 140 tested by the paper is 140, and the dielectric loss is 0.68; the magnetic permeability is 1.11, and the magnetic loss is 0.60.

When the paper is used for preparing 1.83mm honeycombs, the average reflectivity of 0.3-1GHz is less than-2 dB, the average reflectivity of 1-2GHz is less than-3 dB, the average reflectivity of 2-18GHz is less than-8 dB, and the average reflectivity of 4-18GHz is less than-10 dB.

Example 5

Adding carbonyl iron particles with the weight percentage content of 500 wt% in the preparation process of PBO precipitation pulp, then defibering, dehydrating, forming, squeezing and finally drying the PBO precipitation pulp with the weight percentage content of 100 wt% to constant weight to obtain the product with the quantitative content of 60g/m²A magnetic paper base material having a thickness of 80 μm. The retention of the magnetic particles is tested to be 97%, and the dielectric constant of the material is tested to be: 12.30, dielectric loss: 0.25; magnetic permeability: 1.21, magnetic loss: 0.26.