CN112126089B - Carbon nano composite broadband wave-absorbing gradient structure material and preparation method thereof - Google Patents

Carbon nano composite broadband wave-absorbing gradient structure material and preparation method thereof Download PDF

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CN112126089B
CN112126089B CN202010905708.7A CN202010905708A CN112126089B CN 112126089 B CN112126089 B CN 112126089B CN 202010905708 A CN202010905708 A CN 202010905708A CN 112126089 B CN112126089 B CN 112126089B
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carbon nano
wave
preset
absorbing
mass ratio
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CN112126089A (en
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李克训
鞠军燕
周必成
张捷
王东红
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CETC 33 Research Institute
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    • C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
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Abstract

The invention discloses a carbon nano composite broadband wave-absorbing gradient structure material and a preparation method thereof, wherein a novel carbon nano material such as a carbon nano tube and graphene is used as a wave-absorbing agent, rigid polyurethane resin is used as a matrix, and the impedance gradual change design is adopted to obtain the novel carbon nano composite broadband wave-absorbing gradient structure material and the preparation method thereof.

Description

Carbon nano composite broadband wave-absorbing gradient structure material and preparation method thereof
Technical Field
The invention relates to the technical field of materials, in particular to a carbon nano composite broadband wave-absorbing gradient structure material and a preparation method thereof.
Background
In the information age, the rapid development of electronic information technology, electronic information equipment, systems and internal and external environments in which the electronic information equipment and systems are located, as well as the environment in which people live, the electromagnetic environment is increasingly complex. The electromagnetic radiation caused by the electromagnetic radiation is getting more and more serious, the electromagnetic radiation is filled in electronic information equipment, systems and spaces where people are located, and the normal work of the electronic information equipment and the systems is influenced by the complex electromagnetic environment effect, and potential harm is brought to the life health of people. Electromagnetic shielding materials have become one of the basic protective measures against such electromagnetic radiation hazards. With the increasing degree of informatization, electromagnetic protection materials play an increasingly important role in solving the problem of electromagnetic radiation facing complex electromagnetic environment effects. The traditional electromagnetic protection material realizes effective protection of complex electromagnetic radiation mainly by means of the electromagnetic shielding action principle of ideal conductors such as metal materials, the electrical loss of various conductive materials to electromagnetic waves and the magnetic loss characteristic of magnetic materials such as ferrite to the electromagnetic waves. Among them, one of the most influential materials, carbon materials (such as carbon black, graphite, etc.) and novel carbon nanomaterials (fullerene, graphene, carbon nanotube, etc.), as an electromagnetic wave absorber, shows an obvious electrical loss characteristic to electromagnetic waves due to their specific composition and structural characteristics, but their own magnetic loss characteristics are often poor.
Disclosure of Invention
The invention provides a carbon nano composite broadband wave-absorbing gradient structure material and a preparation method thereof, which aim to solve the problem of limited wave-absorbing property of the existing wave-absorbing material.
In a first aspect, the invention provides a preparation method of a carbon nano composite broadband wave-absorbing gradient structure material, which comprises the following steps: respectively stirring and mixing polyurethane, a foaming agent, a wave absorbing agent and a flame retardant according to a plurality of different preset mass proportions, casting and foaming to correspondingly obtain a plurality of bonding layers, wherein the wave absorbing agent is a carbon nano tube and graphene, and the mass fractions of the carbon nano tube in the different preset mass proportions are increased progressively according to a preset gradient; and bonding the plurality of bonding layers according to the increasing sequence of the mass fraction of the carbon nano tubes to obtain the carbon nano composite broadband wave-absorbing gradient structure material, and taking the bonding layer with the minimum mass fraction of the carbon nano tubes as an incident light receiving surface of the carbon nano composite broadband wave-absorbing gradient structure material.
Optionally, the adhesive layer is 5 layers;
the polyurethane, the foaming agent, the wave absorbing agent and the flame retardant are respectively stirred and mixed according to a plurality of different preset mass proportions, and are cast and foamed to correspondingly obtain a plurality of sticking layers, and the method comprises the following steps:
firstly, stirring and mixing polyurethane, a foaming agent, a wave absorbing agent and a flame retardant in a first preset mass ratio, casting and foaming to obtain a first adhesive layer, wherein the wave absorbing agent is a carbon nano tube and graphene;
step two, preparing a second sticking layer, a third sticking layer, a fourth sticking layer and a fifth sticking layer according to a second preset mass proportion, a third preset mass proportion, a fourth preset mass proportion and a fifth preset mass proportion respectively in the mode of the step one; the mass proportions of the carbon nanotubes in the first preset mass proportion, the second preset mass proportion, the third preset mass proportion, the fourth preset mass proportion and the fifth preset mass proportion are increased progressively according to a preset gradient;
bonding the plurality of bonding layers according to the increasing order of the mass fraction of the carbon nano tube to obtain the carbon nano composite broadband wave-absorbing gradient structure material, which comprises the following steps:
and the first pasting layer, the second pasting layer, the third pasting layer, the fourth pasting layer and the fifth pasting layer are sequentially pasted to obtain the carbon nano composite broadband wave-absorbing gradient structure material, and one side of the first pasting layer of the carbon nano composite broadband wave-absorbing gradient structure material is used as an incident light receiving surface.
Optionally, the mass ratios of the carbon nanotubes in the first preset mass ratio, the second preset mass ratio, the third preset mass ratio, the fourth preset mass ratio and the fifth preset mass ratio are respectively: 1 to 2 parts, 2 to 4 parts, 4 to 6 parts, 6 to 8 parts and 8 to 10 parts.
Optionally, the polyurethane further comprises: polyol and isocyanate, wherein the mass ratio of the polyol to the isocyanate is 100:130 to 150.
Optionally, the polyol is a polyether polyol having a molecular weight of 300 to 1000 and a functionality of 3 to 8.
Optionally, the casting foaming specifically includes: the casting foaming is carried out in a preset mould, and the temperature of the preset mould is 50-80 ℃.
Optionally, the mass ratio of the polyurethane, the foaming agent, the wave absorbing agent and the flame retardant is as follows: 100:30 to 50: 1-2, 2-4, 4-6, 6-8 and 8-10: 10 to 100.
Optionally, the stirring and mixing is performed by adopting a dispersing sand mill to stir at the rotating speed of 1000-1500 r/min, or performing ball milling and dispersing through a planetary ball mill, wherein the revolution is 100-200 r/min, and the stirring time is 60-120 min.
Optionally, the mass ratio of the wave absorbing agent to the carbon nanotubes is 1:1.
In a second aspect, the invention provides a carbon nano composite broadband wave-absorbing gradient structure material, which is prepared by any one of the methods.
The invention has the following beneficial effects:
the invention uses novel carbon nano materials such as carbon nano tubes, graphene and the like as wave absorbing agents, uses hard polyurethane resin as a matrix, and obtains a novel carbon nano composite broadband wave absorbing gradient structure material and a preparation method thereof through impedance gradual change design.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a schematic flow chart of a method for preparing a carbon nano composite broadband wave-absorbing gradient structural material according to a first embodiment of the present invention;
fig. 2 is a schematic flow chart of a method for preparing another carbon nano composite broadband wave-absorbing gradient structural material according to a first embodiment of the present invention;
fig. 3 is a schematic diagram of the wave-absorbing performance of a typical carbon nano composite broadband wave-absorbing gradient structure material according to the first embodiment of the present invention.
Detailed Description
Aiming at the problem that the existing wave absorbing material has limited wave absorption, the embodiment of the invention carries out the optimized design of a rigid polyurethane foaming formula by using novel carbon nano materials such as carbon nano tubes and graphene and rigid polyurethane foam materials, prepares rigid polyurethane foam layers with different wave absorbing agent contents by synchronously adding wave absorbing agents, flame retardants and the like and accurately regulating and controlling the using amount of the wave absorbing agents, and realizes the preparation of a wave absorbing gradient structure material by a laminating process. The present invention will be described in further detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The first embodiment of the invention provides a preparation method of a carbon nano composite broadband wave-absorbing gradient structure material, and referring to fig. 1, the method comprises the following steps:
s101, stirring and mixing polyurethane, a foaming agent, a wave absorbing agent and a flame retardant according to a plurality of different preset mass proportions respectively, casting and foaming to obtain a plurality of adhesive layers correspondingly, wherein the wave absorbing agent is a carbon nano tube and graphene, and the mass fractions of the carbon nano tube in the different preset mass proportions are increased progressively according to a preset gradient;
in practice, those skilled in the art can adjust the ratio of each component in the polyurethane to obtain a flexible or rigid polyurethane according to the need.
S102, bonding the plurality of bonding layers according to the increasing sequence of the mass fraction of the carbon nano tubes to obtain the carbon nano composite broadband wave-absorbing gradient structure material, and taking the bonding layer with the least mass fraction of the carbon nano tubes as an incident light receiving surface of the carbon nano composite broadband wave-absorbing gradient structure material.
In other words, the embodiment of the invention takes novel carbon nano materials such as carbon nano tubes, graphene and the like as a wave absorbing agent, takes rigid polyurethane resin as a base body, and obtains the novel carbon nano composite broadband wave absorbing gradient structure material and the preparation method thereof through impedance gradual change design.
The method according to the invention will be explained and illustrated in detail below with the adhesive layer as 5 layers:
stirring polyurethane, foamer, wave absorber and fire retardant respectively according to a plurality of different preset mass proportions and mixing, casting foaming correspondingly obtains a plurality of layers of pasting, includes:
firstly, stirring and mixing polyurethane, a foaming agent, a wave absorbing agent and a flame retardant in a first preset mass ratio, casting and foaming to obtain a first adhesive layer, wherein the wave absorbing agent is a carbon nano tube and graphene;
step two, preparing a second sticking layer, a third sticking layer, a fourth sticking layer and a fifth sticking layer according to a second preset mass proportion, a third preset mass proportion, a fourth preset mass proportion and a fifth preset mass proportion respectively according to the mode of the step one; the mass proportions of the carbon nanotubes in the first preset mass proportion, the second preset mass proportion, the third preset mass proportion, the fourth preset mass proportion and the fifth preset mass proportion are increased progressively according to a preset gradient;
bonding the plurality of bonding layers according to the increasing order of the mass fraction of the carbon nano tube to obtain the carbon nano composite broadband wave-absorbing gradient structure material, which comprises the following steps:
and the first pasting layer, the second pasting layer, the third pasting layer, the fourth pasting layer and the fifth pasting layer are sequentially pasted to obtain the carbon nano composite broadband wave-absorbing gradient structure material, and one side of the first pasting layer of the carbon nano composite broadband wave-absorbing gradient structure material is used as an incident light receiving surface.
In specific implementation, the mass ratio of the polyurethane, the foaming agent, the wave absorbing agent and the flame retardant in the embodiment of the invention is as follows: 100:30 to 50: 1-2, 2-4, 4-6, 6-8 and 8-10: 10 to 100.
And the mass ratio of the wave absorbing agent to the carbon nano tube is 1:1.
And in specific implementation, in the embodiment of the present invention, the mass ratios of the carbon nanotubes in the first preset mass ratio, the second preset mass ratio, the third preset mass ratio, the fourth preset mass ratio, and the fifth preset mass ratio are respectively: 1 to 2 parts, 2 to 4 parts, 4 to 6 parts, 6 to 8 parts and 8 to 10 parts.
Also, the polyurethane according to the embodiment of the present invention further includes: polyol and isocyanate, wherein the mass ratio of the polyol to the isocyanate is 100:130 to 150.
Wherein the polyol is polyether polyol with the molecular weight of 300-1000 and the functionality of 3-8.
In specific implementation, the casting foaming in the embodiment of the invention is performed in a preset mold, and the temperature of the preset mold is 50-80 ℃. The stirring and mixing are performed by adopting a dispersing sand mill to stir at the rotating speed of 1000-1500 r/min, or ball milling and dispersing are performed by a planetary ball mill, the revolution is 100-200 r/min, and the stirring time is 60-120 min.
The preparation process flow of the carbon nano composite broadband wave-absorbing gradient structure material is shown in figure 2.
The invention takes carbon nano materials such as carbon nano tubes, graphene and the like as wave absorbing agents, takes hard polyurethane as a matrix, the matrix materials are mainly stirred at a high speed through a metering ratio, injected into mould cavities with different specifications for casting and foaming, respectively prepares hard polyurethane foam layers with different wave absorbing agent contents, and then is laminated and molded, and the concrete steps are as follows:
(1) Weighing polyurethane raw materials and a foaming agent (in mass ratio): 100 portions of polyol, wherein the polyol is polyether polyol with the molecular weight of 300-1000 and the functionality of 3-8, polyoxypropylene polyol (initiator is triethanolamine, pentaerythritol, sorbitol, mannitol, sucrose and the like); 130-150 parts of isocyanate, toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and polymer (PAPI) thereof are optional; 30-50 parts of foaming agent, which is fluorocarbon, dichloromethane, dichloroethane, isopentane or carbon dioxide (formed by reaction of isocyanate and water), and the like; deionized water: 0-5 parts; catalyst: 1-5 parts of amine and tin, such as triethylene diamine, dimethyl cyclohexylamine, stannous octoate (T-9), dibutyltin dilaurate (T-12) and the like, a foam stabilizer: 0.5-1.5 parts of water-soluble polyether, silicone oil and silicone; the above 5 parts were weighed and numbered (1), (2), (3), (4) and (5), respectively.
In the present invention, the polyol and isocyanate, if added with the blowing agent and other auxiliary agents, will form a flexible or rigid polyurethane (foam), and in the specific implementation, those skilled in the art can adjust the component ratio as required to obtain flexible or rigid polyurethane.
(2) Weighing a flame retardant: 10-100 parts of aluminum hydroxide, hydrated alumina, magnesium hydroxide, melamine and antimony trioxide, wherein the aluminum hydroxide and the hydrated alumina are mainly used; 5 parts were weighed and numbered (1), (2), (3), (4) and (5), respectively.
(3) Weighing a wave absorbing agent: respectively weighing 1-2 parts, 2-4 parts, 4-6 parts, 6-8 parts and 8-10 parts, numbering (1), (2), (3), (4) and (5), wherein the wave absorbing agent is a carbon nano tube, graphene and a compound system thereof.
(4) Mixing materials: placing 5 parts of polyol in the step (1) into a container, wherein the polyol is numbered as (1), (2), (3), (4) and (5), and respectively adding a foaming agent, deionized water, a foam stabilizer, a flame retardant and a wave absorbing agent, wherein the numbers correspond to each other; and respectively mixing the catalyst and the isocyanate for later use.
(5) Stirring and mixing: respectively stirring the polyol mixed system mixed with the auxiliary agent in the step (4) at a high speed of 500-1500 r/min by a dispersing sand mill, or performing ball milling dispersion by a planetary ball mill, revolving at 100-300 r/min, and stirring for 30-120 min; and (3) adding the isocyanate mixed with the catalyst in the step (4) into a polyol mixing system, stirring and mixing the isocyanate and the polyol mixing system through a dispersing sand mill for 5 to 30 seconds.
(6) Casting and foaming: the systems (1), (2), (3), (4) and (5) stirred and mixed in the step (5) are respectively injected into preheated moulds with corresponding specification and size, the specification of length multiplied by 300mm multiplied by 5mm is taken as an example, and the mould temperature is 50-80 ℃.
(7) Curing and sampling: standing for 10-120 min, and taking out after the polyurethane foaming system is fully reacted and solidified and cooled to room temperature.
(8) Attaching: taking out the boards (1), (2), (3), (4) and (5) and finishing gluing and bonding from top to bottom in sequence.
Finally, the carbon nano composite broadband wave-absorbing gradient structure material is obtained.
As can be seen from FIG. 3, the carbon nano composite broadband wave-absorbing gradient structure material of the embodiment of the invention has better wave-absorbing performance.
The method of the embodiment of the invention has the following beneficial effects:
firstly, compared with the metal wave absorber material prepared by the traditional method, the carbon nano tube and the graphene have the advantages of obvious nano effect, light weight and high performance as a novel carbon wave absorber. The novel nano carbon material, namely the carbon nano tube and the graphene are compounded, and the advantages of the lamellar of the graphene and the fibrous advantages of the carbon nano tube are combined to give full play to the advantages of the structure and the composition performance of the wave absorbing agent.
Compared with the traditional method for preparing the broadband wave-absorbing foam material by soaking carbon black in the soft polyurethane foam, the method has the advantages that the wave-absorbing material is formed by means of in-situ foaming of the hard polyurethane matrix, the interface bonding force between the wave-absorbing agent and the resin matrix is improved, and the wave-absorbing material also has certain mechanical support performance.
Moreover, the broadband gradient structure wave-absorbing material adopts an impedance gradual change structure design, and through a multilayer optimization design, such as the impedance gradual change of a five-layer structure in a typical case of the broadband gradient structure wave-absorbing material, the broadband gradient structure wave-absorbing material is beneficial to further reducing the thickness of the wave-absorbing material, and is another advantage of the broadband gradient structure wave-absorbing material.
In addition, the thickness of each layer of hard polyurethane in the invention can be adjusted, the number of layers of the total broadband wave-absorbing gradient structure material can be adjusted, the use amounts of the carbon nano tube and the graphene can be adjusted, and the hard polyurethane and the graphene need to be matched with each other in a coordinated manner. The wave absorber of the present invention may be compounded with other carbon-based materials such as fullerene, graphdine, carbon aerogel, and carbon black.
The process according to the invention will be explained and illustrated in detail below by means of several specific examples:
example one
(1) Weighing polyurethane raw materials and a foaming agent (in mass ratio): 100 parts of triethanolamine polyether polyol, 130-150 parts of isocyanate TDI; 30-50 parts of dichloromethane foaming agent, deionized water: 0-2 parts of a solvent; triethylenediamine catalyst: 1-5 parts of silicone oil foam stabilizer: 0.5 to 1.5 parts, 5 parts of the above are weighed, and the parts are numbered (1), (2), (3), (4) and (5);
(2) Weighing a flame retardant: 10-50 parts of aluminum hydroxide, hydrated alumina and melamine, wherein the compounding ratio is 2;
(3) Weighing the carbon nano tube and the graphene wave absorbing agent: respectively weighing 1-2 parts, 2-4 parts, 4-6 parts, 6-8 parts and 8-10 parts, wherein the numbers (1), (2), (3), (4) and (5) are the proportions of the carbon nano tube and the graphene 1:1;
(4) Mixing materials: placing 5 parts of polyol in the step (1) into a container, wherein the polyol is numbered as (1), (2), (3), (4) and (5), and respectively adding a dichloromethane foaming agent, a silicon oil foam stabilizer, a flame retardant, a carbon nano tube, a graphene wave absorbing agent, deionized water and the like, wherein the numbers correspond to each other; in addition, the catalyst and isocyanate were separately mixed, numbered, and used.
(5) Stirring and mixing: respectively stirring the polyol mixed system mixed with the auxiliary agent in the step (4) at a high speed by a dispersing sand mill at the rotating speed of 1000-1500 r/min, or performing ball milling dispersion by a planetary ball milling machine, performing revolution at 100-200 r/min, and stirring for 60-120 min; and (3) adding the isocyanate mixed with the catalyst in the step (4) into a polyol mixing system, stirring and mixing the isocyanate and the polyol mixing system through a dispersing sand mill for 5 to 30 seconds.
(6) Casting and foaming: the systems (1), (2), (3), (4) and (5) stirred and mixed in the step (5) are respectively injected into preheated moulds with corresponding specification and size, the specification of length multiplied by 300mm multiplied by 5mm is taken as an example, and the mould temperature is 60-80 ℃.
(7) Curing and sampling: standing for 10-30 min, and taking out after the polyurethane foaming system is fully reacted and solidified and cooled to room temperature.
(8) Attaching: taking out the boards (1), (2), (3), (4) and (5) and finishing gluing and bonding from top to bottom in sequence.
Finally, the carbon nano composite broadband wave-absorbing gradient structure material is obtained.
Example two
(1) Weighing polyurethane raw materials and a foaming agent (in mass ratio): 100 parts of sucrose polyether polyol, 130-150 parts of MDI isocyanate, 30-50 parts of dichloromethane foaming agent and stannous octoate (T-9) catalyst: 1-5 parts of water-soluble polyether foam stabilizer: 0.5 to 1.5 parts, 5 parts of the above are weighed, and the parts are numbered (1), (2), (3), (4) and (5);
(2) Weighing a flame retardant: 50-60 parts of hydrated alumina, magnesium hydroxide and melamine (mass ratio 2;
(3) Weighing a wave absorbing agent: respectively weighing 1-2 parts, 2-4 parts, 4-6 parts, 6-8 parts and 8-10 parts, numbering (1), (2), (3), (4) and (5), wherein the wave absorber is a carbon nano tube and graphene compound system and is prepared according to the proportion of 2:1;
(4) Mixing materials: placing 5 parts of polyol in the step (1) in a container, wherein the polyol is numbered as (1), (2), (3), (4) and (5), and respectively adding a dichloromethane foaming agent, a water-soluble polyether foam stabilizer, a flame retardant, a carbon nano tube and a graphene compound system wave absorber, wherein the numbers correspond to each other; at the same time, the catalyst and isocyanate were separately mixed, numbered, and used.
(5) Stirring and mixing: respectively stirring the polyol mixed system mixed with the auxiliary agent in the step (4) at a high speed of 500-1200 r/min by a dispersing sand mill, or performing ball milling dispersion by a planetary ball mill, revolving at 150-250 r/min, and stirring for 30-60 min; and (3) adding the isocyanate mixed with the catalyst in the step (4) into a polyol mixing system, stirring and mixing the isocyanate and the polyol mixing system through a dispersing sand mill for 10 to 20 seconds.
(6) Casting and foaming: the systems (1), (2), (3), (4) and (5) stirred and mixed in the step (5) are respectively injected into preheated moulds with corresponding specification sizes, the specification of length multiplied by 300mm multiplied by 5mm is taken as an example, and the mould temperature is 60-70 ℃.
(7) Curing and sampling: standing for 60-120 min, and taking out after the polyurethane foaming system is fully reacted, cured and cooled to room temperature.
(8) Attaching: taking out the boards (1), (2), (3), (4) and (5) and finishing gluing and bonding from top to bottom in sequence.
Finally, the carbon nano composite broadband wave-absorbing gradient structure material is obtained.
EXAMPLE III
(1) Weighing polyurethane raw materials and a foaming agent (in mass ratio): 100 parts of sucrose polyether polyol, 130-150 parts of MDI isocyanate, 30-40 parts of dichloromethane foaming agent and stannous octoate (T-9) catalyst: 1-5 parts of water-soluble polyether foam stabilizer: 0.5 to 1.5 parts, 5 parts of the above are weighed, and the parts are numbered (1), (2), (3), (4) and (5);
(2) Weighing a flame retardant: 50-60 parts of hydrated alumina, magnesium hydroxide and melamine (mass ratio 2;
(3) Weighing a wave absorbing agent: respectively weighing 1-1.5 parts, 2-2.5 parts, 4-4.5 parts, 6-6.5 parts and 9-10 parts, wherein the wave absorbing agent is a carbon nano tube and graphene compound system and is prepared according to the proportion of 1:2;
(4) Mixing materials: placing 5 parts of polyol in the step (1) into a container, wherein the polyol is numbered as (1), (2), (3), (4) and (5), and respectively adding a dichloromethane foaming agent, a water-soluble polyether foam stabilizer, a flame retardant, a carbon nano tube and a graphene compound system wave absorber, wherein the numbers correspond to each other; at the same time, the catalyst and isocyanate were separately mixed, numbered, and used.
(5) Stirring and mixing: respectively stirring the polyol mixed system mixed with the auxiliary agent in the step (4) at a high speed by a dispersing sand mill at the rotating speed of 800-1000 r/min, or performing ball milling dispersion by a planetary ball mill, revolving at 150-250 r/min, and stirring for 30-60 min; and (3) adding the isocyanate mixed with the catalyst in the step (4) into a polyol mixing system, stirring and mixing the isocyanate and the polyol mixing system through a dispersing sand mill for 10 to 20 seconds.
(6) Casting and foaming: the systems (1), (2), (3), (4) and (5) stirred and mixed in the step (5) are respectively injected into preheated moulds with corresponding specification and size, the specification of length multiplied by 300mm multiplied by 5mm is taken as an example, and the mould temperature is 60-70 ℃.
(7) Curing and sampling: standing for 60-120 min, and taking out after the polyurethane foaming system is fully reacted and solidified and cooled to room temperature.
(8) Attaching: taking out the boards (1), (2), (3), (4) and (5) and finishing gluing and bonding from top to bottom in sequence.
Finally, the carbon nano composite broadband wave-absorbing gradient structure material is obtained.
Example four
(1) Weighing polyurethane raw materials and a foaming agent (in mass ratio): 100 parts of sorbitol polyether polyol and 130-140 parts of isocyanate PAPI; 30-50 parts of dichloromethane foaming agent, deionized water: 0-2 parts of a solvent; dimethyl cyclohexylamine catalyst: 1-5 parts of silicone oil foam stabilizer: 0.5 to 1.5 parts, 5 parts of the above are weighed, and the numbers (1), (2), (3), (4) and (5) are respectively assigned;
(2) Weighing a flame retardant: 10-50 parts of aluminum hydroxide, hydrated alumina and melamine, wherein the compounding ratio of the aluminum hydroxide, the hydrated alumina and the melamine is 2;
(3) Weighing the carbon nano tube and the graphene wave absorbing agent: respectively weighing 1-2 parts, 2-4 parts, 4-6 parts, 6-8 parts and 8-10 parts, wherein the numbers (1), (2), (3), (4) and (5) are the proportions of the carbon nano tube and the graphene 4:1;
(4) Mixing materials: placing 5 parts of polyol in the step (1) into a container, wherein the polyol is numbered as (1), (2), (3), (4) and (5), and respectively adding a dichloromethane foaming agent, a silicon oil foam stabilizer, a flame retardant, a carbon nano tube, a graphene wave absorbing agent, deionized water and the like, wherein the numbers correspond to each other; in addition, the catalyst and isocyanate were separately mixed, numbered, and used.
(5) Stirring and mixing: respectively stirring the polyol mixed system mixed with the auxiliary agent in the step (4) at a high speed of 1000-1500 r/min by a dispersing sand mill, or performing ball milling dispersion by a planetary ball mill, revolving at 100-200 r/min, and stirring for 60-120 min; and (3) adding the isocyanate mixed with the catalyst in the step (4) into a polyol mixing system, stirring and mixing the isocyanate and the polyol mixing system through a dispersing sand mill for 5 to 20 seconds.
(6) Casting and foaming: the systems (1), (2), (3), (4) and (5) stirred and mixed in the step (5) are respectively injected into preheated moulds with corresponding specification and size, the specification of length multiplied by 300mm multiplied by 5mm is taken as an example, and the mould temperature is 60-80 ℃.
(7) Curing and sampling: standing for 10-30 min, and taking out after the polyurethane foaming system is fully reacted and solidified and cooled to room temperature.
(8) Attaching: taking out the boards (1), (2), (3), (4) and (5) and finishing gluing and bonding from top to bottom in sequence.
Finally, the carbon nano composite broadband wave-absorbing gradient structure material is obtained.
Generally speaking, the embodiment of the invention prepares a hard polyurethane-based carbon nano composite broadband wave-absorbing gradient structure material, and the most important characteristic is that a composite wave-absorbing agent of carbon nano tubes and graphene is compounded with polyurethane in situ, so that the interface bonding force is improved, the problem of dispersibility is solved, a composite functional system of the wave-absorbing agent and a fire retardant is introduced into a hard polyurethane foaming system, the composition structure of each layer is adjusted through multilayer superposition and the using amount of the wave-absorbing agent, and finally the gradient composite material is formed through lamination, so that the broadband absorption of electromagnetic waves is realized, the bandwidth of less than-10 dB covers more than 6 GHz-40 GHz, the purpose of good dispersion of the carbon nano composite wave-absorbing agent in a resin matrix is realized, meanwhile, certain compatibility is ensured, the light wave-absorbing electromagnetic material also has the characteristics of light weight, strong mechanical support and strong environmental adaptability in the aspect of use, and the carbon wave-absorbing material support is provided for solving the problem of electromagnetic radiation protection in the field of electronic information equipment systems which is increasing seriously.
A second embodiment of the present invention provides a carbon nano composite broadband wave-absorbing gradient structure material, which is characterized in that the carbon nano composite broadband wave-absorbing gradient structure material is prepared by any one of the methods described in the first embodiment of the present invention.
The relevant content of the embodiments of the present invention can be understood by referring to the first embodiment of the present invention, and will not be discussed in detail herein.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.

Claims (8)

1. A preparation method of a carbon nano composite broadband wave-absorbing gradient structure material is characterized by comprising the following steps:
respectively stirring and mixing polyurethane, a foaming agent, a wave absorbing agent and a flame retardant according to a plurality of different preset mass proportions, casting and foaming to correspondingly obtain a plurality of bonding layers, wherein the wave absorbing agent is a carbon nano tube and graphene, and the mass fractions of the carbon nano tube in the different preset mass proportions are increased progressively according to a preset gradient;
bonding the plurality of bonding layers according to the increasing sequence of the mass fraction of the carbon nano tubes to obtain the carbon nano composite broadband wave-absorbing gradient structure material, and taking the bonding layer with the minimum mass fraction of the carbon nano tubes as an incident light receiving surface of the carbon nano composite broadband wave-absorbing gradient structure material;
the sticking layer is 5 layers;
the polyurethane, the foaming agent, the wave absorbing agent and the flame retardant are respectively stirred and mixed according to a plurality of different preset mass proportions, and are cast and foamed to correspondingly obtain a plurality of sticking layers, and the method comprises the following steps:
firstly, stirring and mixing polyurethane, a foaming agent, a wave absorbing agent and a flame retardant in a first preset mass ratio, casting and foaming to obtain a first adhesive layer, wherein the wave absorbing agent is a carbon nano tube and graphene;
step two, preparing a second sticking layer, a third sticking layer, a fourth sticking layer and a fifth sticking layer according to a second preset mass proportion, a third preset mass proportion, a fourth preset mass proportion and a fifth preset mass proportion respectively according to the mode of the step one; wherein the mass ratios of the carbon nanotubes in the first preset mass ratio, the second preset mass ratio, the third preset mass ratio, the fourth preset mass ratio and the fifth preset mass ratio are gradually increased according to a preset gradient, wherein the mass ratios of the carbon nanotubes in the first preset mass ratio, the second preset mass ratio, the third preset mass ratio, the fourth preset mass ratio and the fifth preset mass ratio are respectively: 1-2 parts, 2-4 parts, 4-6 parts, 6-8 parts and 8-10 parts;
bonding the plurality of bonding layers according to the increasing sequence of the mass fraction of the carbon nano tube to obtain the carbon nano composite broadband wave-absorbing gradient structure material, which comprises the following steps:
and the first pasting layer, the second pasting layer, the third pasting layer, the fourth pasting layer and the fifth pasting layer are sequentially pasted to obtain the carbon nano composite broadband wave-absorbing gradient structure material, and one side of the first pasting layer of the carbon nano composite broadband wave-absorbing gradient structure material is used as an incident light receiving surface.
2. The method of claim 1,
the polyurethane further comprises: polyol and isocyanate, wherein the mass ratio of the polyol to the isocyanate is 100:130 to 150.
3. The method of claim 2,
the polyol is polyether polyol with the molecular weight of 300-1000 and the functionality of 3-8.
4. The method according to any one of claims 1 to 3, wherein the casting foaming, in particular comprising:
the casting foaming is carried out in a preset mould, and the temperature of the preset mould is 50-80 ℃.
5. The method according to any one of claims 1 to 3,
the polyurethane, the foaming agent, the wave absorbing agent and the flame retardant are in the following mass ratio: 100:30 to 50: 1-2, 2-4, 4-6, 6-8 and 8-10: 10 to 100.
6. The method according to any one of claims 1 to 3,
the stirring and mixing are performed by adopting a dispersing sand mill to stir at the rotating speed of 1000-1500 r/min, or ball milling and dispersing are performed by a planetary ball mill, the revolution is 100-200 r/min, and the stirring time is 60-120 min.
7. The method according to any one of claims 1 to 3,
the mass ratio of the wave absorbing agent to the carbon nano tube is 1:1.
8. A carbon nano composite broadband wave-absorbing gradient structure material, which is characterized in that the carbon nano composite broadband wave-absorbing gradient structure material is prepared by the method of any one of claims 1 to 7.
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