阅读说明：本技术 一种轻质柔性阻燃宽频的聚乙烯基吸波材料及其制备方法 (Light flexible flame-retardant broadband polyvinyl wave-absorbing material and preparation method thereof ) 是由 穆武第 毛宁 张朝阳 刘磊 孟晓明 周建伟 闫佳 于 2020-12-29 设计创作，主要内容包括：本发明公开一种轻质柔性阻燃宽频的聚乙烯基吸波材料及其制备方法,该聚乙烯基吸波材料包括基体、吸收剂和助剂,以低密度聚乙烯和线性低密度聚乙烯的共混物为基体,以超导炭黑和短切碳纤维为吸收剂；所述聚乙烯基吸波材料中各组分均匀分散；该制备方法包括制备导电胚料、制备可发泡导电胚料、可发泡导电胚料再次混合并压片、静置、交联反应和热平衡。本发明提供的聚乙烯基吸波材料力学性能优异、化学性能稳定,不吸水、不易水解；本发明提供的制备方法工艺简单,适用于大批量生产,且该制备方法制备获得的聚乙烯基吸波材料力学性能优异、化学性能稳定,不吸水、使用寿命长。(The invention discloses a light flexible flame-retardant broadband polyvinyl wave-absorbing material and a preparation method thereof, wherein the polyvinyl wave-absorbing material comprises a matrix, an absorbent and an auxiliary agent, a blend of low-density polyethylene and linear low-density polyethylene is used as the matrix, and superconducting carbon black and short carbon fibers are used as the absorbent; the components in the polyvinyl wave absorbing material are uniformly dispersed; the preparation method comprises the steps of preparing a conductive blank, preparing a foamable conductive blank, mixing and tabletting the foamable conductive blank again, standing, carrying out a crosslinking reaction and carrying out heat balance. The polyvinyl wave-absorbing material provided by the invention has excellent mechanical property, stable chemical property, no water absorption and difficult hydrolysis; the preparation method provided by the invention is simple in process and suitable for mass production, and the polyvinyl wave-absorbing material prepared by the preparation method is excellent in mechanical property, stable in chemical property, free of water absorption and long in service life.)

1. The light flexible flame-retardant broadband polyvinyl wave-absorbing material is characterized by comprising a base body, an absorbent and an auxiliary agent, wherein a blend of low-density polyethylene and linear low-density polyethylene is used as the base body, and superconducting carbon black and short carbon fibers are used as the absorbent; the polyvinyl wave-absorbing material is uniformly dispersed in all components.

2. The polyvinyl wave absorbing material of claim 1, wherein the matrix comprises 65 to 80 parts by mass of low density polyethylene and 35 to 20 parts by mass of linear low density polyethylene;

the mass parts of the components in the absorbent are 15-20 parts of superconducting carbon black and 2-10 parts of short carbon fiber.

3. The polyvinyl wave absorbing material of claim 1, wherein the additives include plasticizers, cross-linking agents, foaming synergists, lubricants, and flame retardants; ethylene-vinyl acetate is used as a plasticizer, dicumyl peroxide is used as a cross-linking agent, azodicarbonamide is used as a foaming agent, zinc stearate is used as a foaming synergist, stearic acid is used as a lubricant, and melamine cyanurate is used as a flame retardant.

4. The polyvinyl wave absorbing material according to claim 3, wherein the polyvinyl wave absorbing material comprises 90-110 parts by mass of a base body, 17-30 parts by mass of an absorbent, 5-10 parts by mass of a plasticizer, 0.5-1.5 parts by mass of a cross-linking agent, 4-6 parts by mass of a foaming agent, 1-3 parts by mass of a foaming synergist, 1-3 parts by mass of a lubricant and 10-20 parts by mass of a flame retardant.

5. The polyvinyl wave absorbing material of any one of claims 1 to 4, wherein the apparent specific volume of the superconducting carbon black is not less than 4.5cm³The iodine absorption value is more than or equal to 650g/kg, the resistivity is less than or equal to 1 omega m, and the pH value is 7-8.

6. The polyvinyl wave absorbing material of any one of claims 1 to 4, wherein the chopped carbon fibers have a length of 3mm and a type of T700.

7. The polyvinyl wave absorbing material of any one of claims 1 to 4, wherein the low density polyethylene has a melt index of 10 to 20g/min, and the linear low density polyethylene has a melt index of 8 to 16 g/min.

8. The polyvinyl wave absorbing material of any one of claims 1 to 4, wherein the content of vinyl acetate in the ethylene-vinyl acetate is 20 to 26%.

9. The preparation method of the light flexible flame-retardant broadband polyvinyl wave-absorbing material according to any one of claims 1 to 8, which is characterized by comprising the following steps:

s1: weighing the following raw materials in parts by mass:

65-80 parts of low-density polyethylene, 35-20 parts of linear low-density polyethylene, 15-20 parts of superconducting carbon black, 2-10 parts of chopped carbon fiber, 5-10 parts of ethylene-vinyl acetate, 0.5-1.5 parts of dicumyl peroxide, 4-6 parts of azodicarbonamide, 1-3 parts of zinc stearate, 1-3 parts of stearic acid and 10-20 parts of melamine cyanurate salt;

s2: mixing low-density polyethylene, linear low-density polyethylene, superconducting carbon black, chopped carbon fiber and ethylene-vinyl acetate, and carrying out melt blending at 110 ℃ for 60-120 min to obtain a conductive blank;

s3: adding dicumyl peroxide, azodicarbonamide, zinc stearate, stearic acid and melamine cyanurate into the conductive blank, and carrying out melt blending for 5-10 min at 110 ℃ to obtain a foamable conductive blank;

s4: pressing the foamable conductive blank at 105 ℃ to form a foamable sheet material;

s5: standing the foamable sheet material for 8-12 h in a room temperature environment;

s6: reacting the settled foamable sheet material for 20-30 min under the conditions of heating and pressurizing to obtain a sheet material;

s7: and thermally balancing the sheet at 70 ℃ for 4h to obtain the polyvinyl flame-retardant light flexible broadband wave-absorbing material.

10. The method according to claim 9, wherein the heating temperature is 170 to 180 ℃ and the pressurizing pressure is 10 to 20MPa in step S6.

Technical Field

The invention relates to the technical field of polymer melt foaming preparation, in particular to a light flexible flame-retardant broadband polyethylene-based wave-absorbing material and a preparation method thereof.

Background

With the development of the electronic industry and the wide use of electronic equipment, the pollution of electromagnetic waves is increasingly serious, the requirements on wave-absorbing materials and shielding materials are increasingly vigorous, and meanwhile, due to the hidden requirements on military equipment such as fighters, warships and the like in military affairs, the requirements on materials capable of absorbing radar waves and reducing reflectivity are increasingly urgent, so that the requirements on the wave-absorbing materials in practical application are increasingly urgent in both military and civil markets.

Among the wave-absorbing materials, the foam wave-absorbing material is one of the more concerned, and the foam wave-absorbing material not only has good absorption effect on electromagnetic waves, but also has the advantages of low density, high strength, sound absorption, heat insulation and shock absorption. The composite material is applied to civil facilities, can effectively improve the influence of electromagnetic waves on equipment, lightens the bearing of a building main body, and simultaneously has the functions of heat insulation and noise reduction; the radar stealth agent is applied to military equipment such as airplanes, missiles, ships and warships, can effectively reduce the weight of the equipment, provides a radar stealth effect, improves the working environment of operators, and has a good application prospect.

The common light foam wave-absorbing material in the market at present takes polyurethane foam as a main base material, the polyurethane foam is divided into hard foam and soft foam according to a foam structure, the hard polyurethane foam is closed-cell foam, the mechanical property is general, the hard polyurethane foam is brittle and easy to slag, the hard polyurethane foam is easy to damage in the processes of carrying and processing, and the soft polyurethane foam is open-cell foam, so that the water absorption rate is high, the weight gain is obvious, and the soft polyurethane foam is not resistant to hydrolysis. Therefore, the polyurethane foams with two foam structures have certain defects in the application of the wave-absorbing material.

Disclosure of Invention

The invention provides a light flexible flame-retardant broadband polyethylene-based wave-absorbing material and a preparation method thereof, which are used for overcoming the defects of insufficient mechanical property, high water absorption rate, hydrolysis resistance and the like of the light wave-absorbing material in the prior art.

In order to achieve the purpose, the invention provides a light flexible flame-retardant broadband polyvinyl wave-absorbing material which comprises a base body, an absorbent and an auxiliary agent, wherein a blend of low-density polyethylene and linear low-density polyethylene is used as the base body, and superconducting carbon black and short carbon fibers are used as the absorbent; the polyvinyl wave-absorbing material is uniformly dispersed in all components.

In order to achieve the above object, the present invention further provides a preparation method of the above polyvinyl wave absorbing material, including:

s1: weighing the following raw materials in parts by mass:

65-80 parts of low-density polyethylene, 35-20 parts of linear low-density polyethylene, 15-20 parts of superconducting carbon black, 2-10 parts of chopped carbon fiber, 5-10 parts of ethylene-vinyl acetate, 0.5-1.5 parts of dicumyl peroxide, 4-6 parts of azodicarbonamide, 1-3 parts of zinc stearate, 1-3 parts of stearic acid and 10-20 parts of melamine cyanurate salt;

s2: mixing low-density polyethylene, linear low-density polyethylene, superconducting carbon black, chopped carbon fiber and ethylene-vinyl acetate, and carrying out melt blending at 110 ℃ for 60-120 min to obtain a conductive blank;

s3: adding dicumyl peroxide, azodicarbonamide, zinc stearate, stearic acid and melamine cyanurate into the conductive blank, and carrying out melt blending for 5-10 min at 110 ℃ to obtain a foamable conductive blank;

s4: pressing the foamable conductive blank at 105 ℃ to form a foamable sheet material;

s5: standing the foamable sheet material for 8-12 h in a room temperature environment;

s6: reacting the settled foamable sheet material for 20-30 min under the conditions of heating and pressurizing to obtain a sheet material;

s7: and thermally balancing the sheet at 70 ℃ for 4h to obtain the polyvinyl flame-retardant light flexible broadband wave-absorbing material.

Compared with the prior art, the invention has the beneficial effects that:

1. the polyvinyl wave-absorbing material provided by the invention has more outstanding wave-absorbing performance and more excellent mechanical property by adding the resistance type absorbent, particularly the short carbon fiber absorbent, and meanwhile, the polyvinyl wave-absorbing material provided by the invention has isotropic wave-absorbing performance because the absorbent is uniformly dispersed in the matrix material.

2. Compared with the common wave-absorbing material of other base materials at present, the polyvinyl wave-absorbing material provided by the invention has the advantages of high foaming ratio, small density, stable mechanical property, chemical corrosion resistance, aging resistance, stable chemical property, friction resistance, extremely low water absorption rate, simple and convenient processing and the like, so that the polyvinyl wave-absorbing material provided by the invention has all the advantages of polyethylene; meanwhile, due to the mixed use of a plurality of absorbents, the polyvinyl wave absorbing material has strong absorption capacity for electromagnetic waves with frequencies of 2-18 GHz and 27-40 GHz, and has strong broadband absorption performance for radar waves.

3. The preparation method of the polyvinyl wave-absorbing material provided by the invention is simple in process and suitable for mass production, and the polyvinyl wave-absorbing material prepared by the preparation method is excellent in mechanical property, stable in chemical property, free of water absorption and long in service life.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a photo of a light flexible flame-retardant broadband polyvinyl wave-absorbing material prepared in embodiment 1 of the present invention;

FIG. 2 is an SEM image of a lightweight flexible flame-retardant broadband polyvinyl wave-absorbing material prepared in embodiment 1 of the invention;

FIG. 3 is a graph showing the absorption efficiency of the light flexible flame-retardant broadband polyvinyl wave-absorbing material prepared in embodiment 1 of the invention for electromagnetic waves with a frequency of 2-18 GHz;

FIG. 4 is a graph showing the absorption efficiency of the lightweight flexible flame-retardant broadband polyvinyl wave-absorbing material prepared in embodiment 1 of the invention for electromagnetic waves with frequency of 27-40 GHz.

The implementation, functional features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without any creative effort based on the embodiments of the present invention belong to the protection scope of the present invention.

In addition, the technical solutions in the embodiments of the present invention can be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent, and is not within the protection scope of the present invention.

The drugs/reagents used are all commercially available without specific mention.

The invention provides a light flexible flame-retardant broadband polyvinyl wave-absorbing material, which comprises a base body, an absorbent and an auxiliary agent, wherein a blend of low-density polyethylene and linear low-density polyethylene is used as the base body, and superconducting carbon black and short carbon fibers are used as the absorbent; the polyvinyl wave-absorbing material is uniformly dispersed in all components.

The polyvinyl wave-absorbing material provided by the invention has more outstanding wave-absorbing performance and more excellent mechanical property by adding the resistance type absorbent, particularly the short carbon fiber absorbent, and meanwhile, the polyvinyl wave-absorbing material provided by the invention has isotropic wave-absorbing performance because the absorbent is uniformly dispersed in the matrix material.

Compared with the common wave-absorbing material of other base materials at present, the polyvinyl wave-absorbing material provided by the invention has the advantages of high foaming ratio, small density, stable mechanical property, chemical corrosion resistance, aging resistance, stable chemical property, friction resistance, extremely low water absorption rate, simple and convenient processing and the like, so that the polyvinyl wave-absorbing material provided by the invention has all the advantages of polyethylene; meanwhile, due to the mixed use of a plurality of absorbents, the polyvinyl wave absorbing material has strong absorption capacity for electromagnetic waves with frequencies of 2-18 GHz and 27-40 GHz, and has strong broadband absorption performance for radar waves.

Preferably, the mass parts of the components in the matrix are 65-80 parts of low density polyethylene and 35-20 parts of linear low density polyethylene;

the mass parts of the components in the absorbent are 15-20 parts of superconducting carbon black and 2-10 parts of short carbon fiber. The polyvinyl wave absorbing material has better electromagnetic wave absorbing capacity and wider wave absorbing frequency by mixing a plurality of absorbents.

Preferably, the auxiliary agents include plasticizers, crosslinking agents, foaming synergists, lubricants and flame retardants; ethylene-vinyl acetate is used as a plasticizer, dicumyl peroxide is used as a cross-linking agent, azodicarbonamide is used as a foaming agent, zinc stearate is used as a foaming synergist, stearic acid is used as a lubricant, and melamine cyanurate is used as a flame retardant. By selecting the plasticizer, the cross-linking agent, the foaming synergist, the lubricant and the flame retardant, the polyvinyl wave-absorbing material has an ideal cellular structure, relatively soft texture and low density.

Preferably, the polyvinyl wave-absorbing material comprises, by mass, 100 parts of a base body, 17-30 parts of an absorbent, 5-10 parts of a plasticizer, 0.5-1.5 parts of a cross-linking agent, 4-6 parts of a foaming agent, 1-3 parts of a foaming synergist, 1-3 parts of a lubricant and 10-20 parts of a flame retardant.

Preferably, the apparent specific volume of the superconducting carbon black is more than or equal to 4.5cm³The iodine absorption value is more than or equal to 650g/kg, the resistivity is less than or equal to 1 omega m, and the pH value is 7-8.

Preferably, the chopped carbon fibers have a length of 3mm and a type T700. The carbon fiber with the length has good dispersibility in the resin matrix and is easy to be lapped into a space conductive network.

Preferably, the low density polyethylene has a melt index of 10 to 20g/min, and the linear low density polyethylene has a melt index of 8 to 16 g/min.

Preferably, the content of vinyl acetate in the ethylene-vinyl acetate is 20-26%.

The invention also provides a preparation method of the light flexible flame-retardant broadband polyethylene-based wave-absorbing material, which comprises the following steps:

s1: weighing the following raw materials in parts by mass:

65-80 parts of Low Density Polyethylene (LDPE), 35-20 parts of Linear Low Density Polyethylene (LLDPE), 15-20 parts of superconducting carbon black (HG-1P) and short carbon fiber (C)_f) 2-10 parts of ethylene-vinyl acetate (EVA), 0.5-1.5 parts of dicumyl peroxide (DCP), 4-6 parts of Azodicarbonamide (AC), 1-3 parts of zinc stearate (Zn-St), 1-3 parts of stearic acid (St) and 10-20 parts of melamine cyanurate (MAC);

chopped carbon fiber (C)_f) In addition to as absorptionThe agent can also be used as a reinforcing material to reinforce the mechanical property of the finally prepared polyvinyl wave-absorbing material.

S2: mixing low-density polyethylene, linear low-density polyethylene, superconducting carbon black, chopped carbon fiber and ethylene-vinyl acetate, and carrying out melt blending at 110 ℃ for 60-120 min to obtain a conductive blank;

step S2 is mainly to uniformly disperse the absorbent in the matrix material, and to add a plasticizer to increase the flexibility of the final product.

S3: adding dicumyl peroxide, azodicarbonamide, zinc stearate, stearic acid and melamine cyanurate into the conductive blank, and carrying out melt blending for 5-10 min at 110 ℃ to obtain a foamable conductive blank;

the step S3 is mainly to uniformly disperse the assistant in the conductive blank, and the time for melt blending after adding the assistant cannot be too long, because too long time will cause temperature rise, thereby causing decomposition of the assistant. Also, the melt blending is divided into two steps S2 and S3, which can ensure uniform mixing and prevent the decomposition of the auxiliary agent by heat.

S4: pressing the foamable conductive blank at 105 ℃ to form a foamable sheet material;

melt blending was again performed to ensure uniform dispersion of the components.

S5: standing the foamable sheet material for 8-12 h in a room temperature environment;

the resting is to allow the interior of the foamable sheet to reach an equilibrium state, so that the properties of the finally prepared product are stable.

S6: reacting the settled foamable sheet material for 20-30 min under the conditions of heating and pressurizing to obtain a sheet material;

heating and pressurizing to cause the inside of the foamable sheet to generate a crosslinking reaction.

S7: and (3) thermally balancing the sheet at 70 ℃ for 4h to obtain the polyvinyl flame-retardant light flexible broadband wave-absorbing material.

The heat balance is to allow the sheet to have an excess rather than directly from the heated, pressurized condition to room temperature. The internal structure of the sheet gradually tends to be stable in the heat balance process, and finally the polyvinyl wave-absorbing material with excellent performance is obtained.

Preferably, in step S6, the heating temperature is 170 to 180 ℃, and the pressurizing pressure is 10 to 20 MPa. The proper temperature and pressure can make the cross-linking reaction inside the foamable sheet material more complete without destroying the original excellent performance of the base material.

Example 1

The embodiment provides a preparation method of a light flexible flame-retardant broadband polyethylene-based wave-absorbing material, which comprises the following steps:

s1: weighing the following raw materials in parts by mass:

70 parts of low-density polyethylene, 30 parts of linear low-density polyethylene, 18 parts of superconducting carbon black, 5 parts of chopped carbon fiber, 8 parts of ethylene-vinyl acetate, 1 part of dicumyl peroxide, 5 parts of azodicarbonamide, 1.5 parts of zinc stearate, 2 parts of stearic acid and 20 parts of melamine cyanurate salt;

s2: mixing low-density polyethylene, linear low-density polyethylene, superconducting carbon black, chopped carbon fiber and ethylene-vinyl acetate, and then melting and blending in an internal mixer at the temperature of 110 ℃ for 100min to obtain a conductive blank;

s3: adding dicumyl peroxide, azodicarbonamide, zinc stearate, stearic acid and melamine cyanurate into the conductive blank, and continuously melting and blending for 7min at 110 ℃ on an internal mixer to obtain a foamable conductive blank;

s4: placing the foamable conductive blank into an open mill, and pressing at 105 ℃ to prepare a foamable sheet material;

s5: standing the foamable sheet material for 10 hours in a room temperature environment;

s6: placing the foamed sheet after standing into a foaming mold coated with a release agent and heated, and heating and pressurizing the mold for 15min by using a flat vulcanizing machine under the conditions of heating and pressurizing to obtain a sheet;

s7: and (3) thermally balancing the sheet at 70 ℃ for 4h to obtain the polyvinyl flame-retardant light flexible broadband wave-absorbing material.

Fig. 1 is a photo of a light flexible flame-retardant broadband polyethylene-based wave-absorbing material prepared in this embodiment, and it can be seen from the photo that the wave-absorbing material prepared in this embodiment has uniform cells, no large cells, and no cracks.

Fig. 2 is an SEM image of the lightweight flexible flame-retardant broadband polyethylene-based wave-absorbing material prepared in this embodiment, and it can be seen from the image that the wave-absorbing material prepared in this embodiment has uniform cell size, complete cell wall, and no through hole.

Fig. 3 and 4 are absorption efficiency curve diagrams of the lightweight flexible flame-retardant broadband polyethylene-based wave-absorbing material prepared in the embodiment, and it can be seen from the diagrams that the average reflectivity is less than-12 Db in the 2-18 GHz band and the 27-40 GHz band, the average reflectivity is less than-16 Db in the 2-18 GHz band, and the average reflectivity is less than-20 Db in the 27-40 GHz band, and the wave-absorbing material has a good electromagnetic wave absorption effect in a wider frequency band.

Example 2

The embodiment provides a preparation method of a light flexible flame-retardant broadband polyethylene-based wave-absorbing material, which comprises the following steps:

s1: weighing the following raw materials in parts by mass:

65 parts of low-density polyethylene, 35 parts of linear low-density polyethylene, 18 parts of superconducting carbon black, 5 parts of chopped carbon fiber, 6 parts of ethylene-vinyl acetate, 1 part of dicumyl peroxide, 5 parts of azodicarbonamide, 1.5 parts of zinc stearate, 2 parts of stearic acid and 20 parts of melamine cyanurate salt;

s2: mixing low-density polyethylene, linear low-density polyethylene, superconducting carbon black, chopped carbon fiber and ethylene-vinyl acetate, and then melting and blending in an internal mixer at the temperature of 110 ℃ for 100min to obtain a conductive blank;

s3: adding dicumyl peroxide, azodicarbonamide, zinc stearate, stearic acid and melamine cyanurate into the conductive blank, and continuously melting and blending the mixture for 8min at 110 ℃ on an internal mixer to obtain a foamable conductive blank;

s4: placing the foamable conductive blank into an open mill, and pressing at 105 ℃ to prepare a foamable sheet material;

s5: standing the foamable sheet material for 10 hours in a room temperature environment;

s6: placing the foamed sheet after standing into a foaming mold coated with a release agent and heated, and heating and pressurizing the mold for 15min by using a flat vulcanizing machine under the conditions of heating and pressurizing to obtain a sheet;

s7: and (3) thermally balancing the sheet at 70 ℃ for 4h to obtain the polyvinyl flame-retardant light flexible broadband wave-absorbing material.

Embodiment 3

The embodiment provides a preparation method of a light flexible flame-retardant broadband polyethylene-based wave-absorbing material, which comprises the following steps:

s1: weighing the following raw materials in parts by mass:

70 parts of low-density polyethylene, 30 parts of linear low-density polyethylene, 18 parts of superconducting carbon black, 2 parts of chopped carbon fiber, 8 parts of ethylene-vinyl acetate, 1 part of dicumyl peroxide, 4 parts of azodicarbonamide, 3 parts of zinc stearate, 3 parts of stearic acid and 10 parts of melamine cyanurate salt;

s2: mixing low-density polyethylene, linear low-density polyethylene, superconducting carbon black, chopped carbon fiber and ethylene-vinyl acetate, and then melting and blending in an internal mixer at the temperature of 110 ℃ for 70min to obtain a conductive blank;

s3: adding dicumyl peroxide, azodicarbonamide, zinc stearate, stearic acid and melamine cyanurate into the conductive blank, and continuously melting and blending the mixture for 10min at 110 ℃ on an internal mixer to obtain a foamable conductive blank;

s4: placing the foamable conductive blank into an open mill, and pressing at 105 ℃ to prepare a foamable sheet material;

s5: standing the foamable sheet material for 12 hours in a room temperature environment;

s6: placing the foamed sheet after standing into a foaming mold coated with a release agent and heated, and heating and pressurizing the mold for 18min by using a flat vulcanizing machine under the conditions of heating and pressurizing to obtain a sheet;

s7: and (3) thermally balancing the sheet at 70 ℃ for 4h to obtain the polyvinyl flame-retardant light flexible broadband wave-absorbing material.

The wave-absorbing materials prepared in the embodiment 1-4 are compared with performance parameters, and the results are shown in table 1, and it can be seen from table 1 that the polyvinyl flame-retardant lightweight flexible broadband wave-absorbing material prepared by the invention has excellent electromagnetic wave absorption capacity. From the comparison between the embodiment examples 1 and 2, it can be known that the dispersion of the absorbent in the matrix material is affected by the mixture ratio of the different matrix materials, and from table 1, the dispersion of the absorbent in the embodiment example 1 is better than that in the embodiment example 2; compared with the embodiment 1 and the embodiment 3, the absorption capacity of the electromagnetic wave is obviously influenced by the amount of the absorbent, and the more the absorbent is added under the same dispersion condition, the better the wave absorbing performance of the wave absorbing material is; compared with the implementation cases 1, 3 and 4, the carbon fiber has a larger influence on the absorption capacity of electromagnetic waves compared with the superconducting carbon black, and the carbon fiber with a certain length is more favorable for building a space conductive network and improving the electromagnetic wave absorption rate compared with the superconducting carbon black under the same dispersion condition.

Table 1 table for comparing performance parameters of the wave-absorbing materials prepared in embodiments 1-3 and comparative example 1

	Example 1	Example 2	Embodiment 3	Example 4
					2～4Ghz	-12.75	-9.50	-4.05	-6.55
4～8Ghz	-16.50	-13.60	-7.50	-8.00
					8～12Ghz	-18.05	-16.75	-9.05	-8.50
12～18Ghz	-17.70	-15.05	-10.00	-11.05
					27～40Ghz	-20.75	-18.00	-8.00	-9.20

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.