阅读说明：本技术 一种具有电磁屏蔽性能的复合板及其制备方法 (Composite board with electromagnetic shielding performance and preparation method thereof ) 是由 徐恩淼 于 2021-05-21 设计创作，主要内容包括：本发明公开了一种具有电磁屏蔽性能的复合板及其制备方法,涉及新材料技术领域。本发明先用吸附铜离子的胺基化氧化石墨烯与聚丙烯混合,经干法纺丝制得改性聚丙烯纤维,然后以苯乙烯、过氧化苯甲酰、羟乙基纤维素、马来酸酐、淀粉、高碘酸钾和丙烯酸为主要原料,通过悬浮聚合制得改性空心微球,最后,将改性聚丙烯纤维与碳纤维、涤纶和改性空心微球混合,经梳理、成网,制得混合纤维毡,将混合纤维毡经针刺加固、热压处理后,制得具有电磁屏蔽性能的复合板。本发明制备的具有电磁屏蔽性能的复合板具备优良的电磁屏蔽性能和降噪性能,且密度低,强度好。(The invention discloses a composite board with electromagnetic shielding performance and a preparation method thereof, and relates to the technical field of new materials. The preparation method comprises the steps of mixing aminated graphene oxide adsorbing copper ions with polypropylene, preparing modified polypropylene fibers through dry spinning, then preparing modified hollow microspheres through suspension polymerization by using styrene, benzoyl peroxide, hydroxyethyl cellulose, maleic anhydride, starch, potassium periodate and acrylic acid as main raw materials, finally mixing the modified polypropylene fibers with carbon fibers, terylene and the modified hollow microspheres, carding and forming a net to prepare a mixed fiber felt, and carrying out needling reinforcement and hot pressing treatment on the mixed fiber felt to prepare the composite board with the electromagnetic shielding performance. The composite board with the electromagnetic shielding performance prepared by the invention has excellent electromagnetic shielding performance and noise reduction performance, and is low in density and good in strength.)

1. The composite board with the electromagnetic shielding performance is characterized by mainly comprising the following raw material components in parts by weight: 40-60 parts of modified polypropylene fibers, 5-10 parts of carbon fibers, 20-40 parts of terylene and 10-20 parts of modified hollow microspheres;

the modified hollow microsphere is prepared from the following raw materials: styrene, benzoyl peroxide, water, hydroxyethyl cellulose, maleic anhydride, starch, potassium periodate, and acrylic acid.

2. The composite board with electromagnetic shielding performance according to claim 1, wherein the modified polypropylene fiber is prepared by mixing polypropylene and modified graphene oxide and dry spinning; the modified graphene oxide is prepared by amination of graphene oxide and adsorption of copper ions.

3. The composite board with electromagnetic shielding performance according to claim 2, wherein the carbon fiber is a carbon fiber with a length of 6 to 10mm and a diameter of 0.2 to 0.5 mm; the terylene has the length of 20-50 mm and the diameter of 0.5-1.0 mm.

4. The composite board with the electromagnetic shielding performance according to claim 3, wherein the composite board with the electromagnetic shielding performance mainly comprises the following raw material components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres.

5. The preparation method of the composite board with the electromagnetic shielding performance is characterized by mainly comprising the following preparation steps of:

(1) mixing an initiator, starch, maleic anhydride and styrene, stirring and prepolymerizing under the inert gas atmosphere to obtain a prepolymerized styrene mixture, mixing the prepolymerized styrene mixture with styrene and the initiator, stirring and mixing to obtain a prepolymerized styrene dispersion, mixing the prepolymerized styrene dispersion with an aqueous solution of a dispersing agent, carrying out suspension polymerization, cooling, carrying out suction filtration, and washing to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at a high temperature to obtain hollow microspheres, mixing the hollow microspheres with water, adding potassium periodate, stirring for reaction, filtering to obtain filter cakes, mixing the filter cakes with a sodium hydroxide solution, adding acrylic acid, stirring for mixing, filtering, and drying to obtain modified hollow microspheres;

(3) mixing the modified graphene oxide with polypropylene, heating and melting to obtain a spinning solution, and spinning the spinning solution by using a dry spinning method to obtain modified polypropylene fibers; weighing the following components in parts by weight: 40-60 parts of modified polypropylene fibers, 5-10 parts of carbon fibers, 20-40 parts of terylene and 10-20 parts of modified hollow microspheres obtained in the step (2); mixing modified polypropylene fibers and carbon fibers, adding polyester and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and carrying out needling reinforcement on the mixed fiber felt to obtain a pretreated mixed fiber felt;

(4) and carrying out hot-pressing treatment on the pretreated mixed fiber felt to obtain the composite board with the electromagnetic shielding performance.

6. The method for preparing a composite board with electromagnetic shielding property according to claim 5, wherein the method for preparing the composite board with electromagnetic shielding property mainly comprises the following steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to a mass ratio of 1: 20-2: 20, adding starch with the mass of 0.125-0.200 times of that of the styrene and maleic anhydride with the mass of 0.0125-0.0200 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at a rate of 20-40 mL/min, removing air, heating the material in the three-neck flask to 120 ℃, stirring for prepolymerization for 1-2 h to obtain a prepolymerization styrene mixture, mixing the prepolymerization styrene mixture and the styrene according to a mass ratio of 1: 2-1: 2.6, adding benzoyl peroxide with the mass of 0.01-0.04 times of that of the prepolymerization styrene mixture, stirring and mixing for 20-50 min at a temperature of 60-70 ℃ and a rotating speed of 300-400 r/min to obtain a prepolymerization styrene dispersion, mixing the prepolymerization styrene dispersion with a hydroxyethyl cellulose solution with the mass fraction of 0.8-1.2% in a volume ratio of 1:5 in a beaker, after suspension polymerization, cooling the materials in the beaker to 40 ℃, performing suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 3-6 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at the temperature of 150-170 ℃ for 20-40 min to obtain hollow microspheres, and mixing the hollow microspheres with water according to a mass ratio of 1: 10-1: 15, adding potassium periodate with the mass of 0.1-0.2 times that of the hollow microspheres into the flask, stirring and reacting for 1-3 hours at the temperature of 70-90 ℃ and the rotation speed of 300-600 r/min, filtering to obtain a filter cake, mixing the filter cake and a sodium hydroxide solution with the mass fraction of 1-2% according to the mass ratio of 1: 10-1: 20, adding acrylic acid with the mass of 3-5 times that of the filter cake into the mixture of the filter cake and the sodium hydroxide solution, stirring and mixing for 1-4 hours at the temperature of 30-60 ℃ and the rotation speed of 300-600 r/min, filtering to obtain filter residues, drying the filter residues for 1-2 hours at the temperature of 80-90 ℃ to obtain modified hollow microspheres;

(3) mixing the modified graphene oxide and polypropylene according to a mass ratio of 5: 100-15: 100, stirring and mixing at a temperature of 130-180 ℃ to obtain a spinning solution, extruding the spinning solution through a spinneret orifice, and cooling and forming to obtain a modified polypropylene fiber with a diameter of 0.5-1.0 mm and a length of 30-100 mm; weighing the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres; mixing modified polypropylene fibers and carbon fibers, adding polyester fibers and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the modified hollow microspheres with the gram weight of 450-550 g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

7. The method for preparing a composite board with electromagnetic shielding performance as claimed in claim 6, wherein the suspension polymerization in step (1) is performed for 3 hours at 80 ℃, then for 2 hours at 90 ℃, and finally for 1 hour at 120 ℃.

8. The preparation method of the composite plate with the electromagnetic shielding performance according to claim 6, wherein the modified graphene oxide in the step (3) is prepared by mixing graphene oxide and water according to a mass ratio of 1:100, adding ethylenediamine 10-20 times the mass of the graphene oxide, stirring and mixing at 80-120 ℃ for 2-6 hours, ultrasonically dispersing at a frequency of 45-55 kHz for 5-15 minutes, filtering, drying to obtain a modified graphene oxide blank, mixing the modified graphene oxide blank with a 5% copper nitrate solution according to a mass ratio of 1:10, filtering, and drying to obtain the modified graphene oxide.

9. The method for preparing a composite board with electromagnetic shielding performance according to claim 6, wherein the pre-needling reinforcement treatment in the step (3) is performed under the process conditions of 50-100 needling points/cm²(ii) a The process condition of the main needling reinforcement treatment is 200-300 needling points/cm²。

10. The method for preparing a composite board with electromagnetic shielding performance according to claim 6, wherein the hot pressing process in step (4) comprises: increasing the pressure of a hot press to 1-2 MPa at room temperature, introducing air into the hot press to increase the air pressure in the hot press to 1MPa, continuously increasing the temperature constant pressure in the hot press to 220 ℃ after 30-40 s, performing irradiation treatment on the pretreated mixed fiber felt by using an electronic accelerator, wherein the irradiation dosage is 8-30 kGy, simultaneously decompressing the air in the hot press, increasing the pressure of the hot press to 4-5 MPa, and pressing for 60-90 s at the temperature of 220 ℃ and the pressure of 4-5 MPa.

Technical Field

The invention relates to the technical field of new materials, in particular to a composite board with electromagnetic shielding performance and a preparation method thereof.

Background

With the development of society, more and more electronic products and electric appliances are widely applied, but electromagnetic radiation generated by the products is also induced into a circuit to cause interference to the circuit. Meanwhile, the human body is also affected. Therefore, the method for cutting off the propagation path of the electromagnetic wave by using the material with the electromagnetic shielding function is a basic and effective interference elimination method.

The composite artificial board with the electromagnetic shielding function is an important electromagnetic shielding material; however, the conventional composite plate with the electromagnetic shielding function often contains a large amount of metal, so that the plate is too heavy, and the application range of the plate is affected. The composite board with light weight and electromagnetic shielding performance is prepared, so that the composite board can be better applied to moving facilities such as automobiles.

Disclosure of Invention

The invention aims to provide a composite plate with electromagnetic shielding performance and a preparation method thereof, and aims to solve the problems in the prior art.

The composite board with the electromagnetic shielding performance is characterized by mainly comprising the following raw material components in parts by weight: 40-60 parts of modified polypropylene fibers, 5-10 parts of carbon fibers, 20-40 parts of terylene and 10-20 parts of modified hollow microspheres;

the modified hollow microsphere is prepared from the following raw materials: styrene, benzoyl peroxide, water, hydroxyethyl cellulose, maleic anhydride, starch, potassium periodate, and acrylic acid.

As optimization, the modified polypropylene fiber is prepared by mixing polypropylene and modified graphene oxide and performing melt spinning; the modified graphene oxide is prepared by amination of graphene oxide and adsorption of copper ions.

Optimally, the carbon fiber is 6-10 mm long and 0.2-0.5 mm in diameter; the terylene has the length of 20-50 mm and the diameter of 0.5-1.0 mm.

As optimization, the composite board with the electromagnetic shielding performance mainly comprises the following raw material components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres.

As optimization, the preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing an initiator, starch, maleic anhydride and styrene, stirring and prepolymerizing under the inert gas atmosphere to obtain a prepolymerized styrene mixture, mixing the prepolymerized styrene mixture with styrene and the initiator, stirring and mixing to obtain a prepolymerized styrene dispersion, mixing the prepolymerized styrene dispersion with a mixed aqueous solution, carrying out suspension polymerization, cooling, carrying out suction filtration, and washing to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at a high temperature to obtain hollow microspheres, mixing the hollow microspheres with water, adding potassium periodate, stirring for reaction, filtering to obtain filter cakes, mixing the filter cakes with a sodium hydroxide solution, adding acrylic acid, stirring for mixing, filtering, and drying to obtain modified hollow microspheres;

(3) mixing the modified graphene oxide with polypropylene, heating and melting to obtain a spinning solution, and spinning the spinning solution by using a dry spinning method to obtain modified polypropylene fibers; weighing the following components in parts by weight: 40-60 parts of modified polypropylene fibers, 5-10 parts of carbon fibers, 20-40 parts of terylene and 10-20 parts of modified hollow microspheres obtained in the step (2); mixing modified polypropylene fibers and carbon fibers, adding the modified hollow microspheres obtained from the terylene and the Nameo (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and carrying out needling reinforcement on the mixed fiber felt to obtain a pretreated mixed fiber felt;

(4) and carrying out hot-pressing treatment on the pretreated mixed fiber felt to obtain the composite board with the electromagnetic shielding performance.

As optimization, the preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to a mass ratio of 1: 20-2: 20, adding starch with the mass of 0.125-0.200 times of that of the styrene and maleic anhydride with the mass of 0.0125-0.0200 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at a rate of 20-40 mL/min, removing air, heating the material in the three-neck flask to 120 ℃, stirring for prepolymerization for 1-2 h to obtain a prepolymerization styrene mixture, mixing the prepolymerization styrene mixture and the styrene according to a mass ratio of 1: 2-1: 2.6, adding benzoyl peroxide with the mass of 0.01-0.04 times of that of the prepolymerization styrene mixture, stirring and mixing for 20-50 min at a temperature of 60-70 ℃ and a rotating speed of 300-400 r/min to obtain a prepolymerization styrene dispersion, mixing the prepolymerization styrene dispersion with a hydroxyethyl cellulose solution with the mass fraction of 0.8-1.2% in a volume ratio of 1:5 in a beaker, after suspension polymerization, cooling the materials in the beaker to 40 ℃, performing suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 3-6 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at the temperature of 150-170 ℃ for 20-40 min to obtain hollow microspheres, and mixing the hollow microspheres with water according to a mass ratio of 1: 10-1: 15, adding potassium periodate with the mass of 0.1-0.2 times that of the hollow microspheres into the flask, stirring and reacting for 1-3 hours at the temperature of 70-90 ℃ and the rotation speed of 300-600 r/min, filtering to obtain a filter cake, mixing the filter cake and a sodium hydroxide solution with the mass fraction of 1-2% according to the mass ratio of 1: 10-1: 20, adding acrylic acid with the mass of 3-5 times that of the filter cake into the mixture of the filter cake and the sodium hydroxide solution, stirring and mixing for 1-4 hours at the temperature of 30-60 ℃ and the rotation speed of 300-600 r/min, filtering to obtain filter residues, drying the filter residues for 1-2 hours at the temperature of 80-90 ℃ to obtain modified hollow microspheres;

(3) mixing the modified graphene oxide and polypropylene according to a mass ratio of 5: 100-15: 100, stirring and mixing at a temperature of 130-180 ℃ to obtain a spinning solution, extruding the spinning solution through a spinneret orifice, and coolingAfter cooling and forming, obtaining modified polypropylene fibers with the diameter of 0.5-1.0 mm and the length of 30-100 mm; weighing the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres; mixing modified polypropylene fibers and carbon fibers, adding polyester fibers and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the modified hollow microspheres with the gram weight of 450-550 g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

As an optimization, the suspension polymerization in the step (1) is carried out for 3 hours under the condition of firstly reacting at 80 ℃, then for 2 hours under the condition of 90 ℃, and finally for 1 hour under the condition of 120 ℃.

Optimally, the preparation method of the modified graphene oxide in the step (3) comprises the steps of mixing graphene oxide and water according to the mass ratio of 1:100, adding ethylenediamine with the mass of 10-20 times that of the graphene oxide, stirring and mixing for 2-6 hours at the temperature of 80-120 ℃, then carrying out ultrasonic dispersion for 5-15 minutes at the frequency of 45-55 kHz, filtering, drying to obtain a modified graphene oxide blank, mixing the modified graphene oxide blank and a copper nitrate solution with the mass fraction of 5% according to the mass ratio of 1:10, filtering, and drying to obtain the modified graphene oxide.

As optimization, the pre-needling reinforcement treatment in the step (3) has the process condition of 50-100 needling points/cm²(ii) a The process condition of the main needling reinforcement treatment is 200-300 needling points/cm²。

As an optimization, the hot pressing treatment method in the step (4) comprises the following steps: increasing the pressure of a hot press to 1-2 MPa at room temperature, introducing air into the hot press to increase the air pressure in the hot press to 1MPa, continuously increasing the temperature constant pressure in the hot press to 220 ℃ after 30-40 s, performing irradiation treatment on the pretreated mixed fiber felt by using an electronic accelerator, wherein the irradiation dosage is 8-30 kGy, simultaneously decompressing the air in the hot press, increasing the pressure of the hot press to 4-5 MPa, and pressing for 60-90 s at the temperature of 220 ℃ and the pressure of 4-5 MPa.

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

the invention uses modified polypropylene fiber and modified hollow microsphere when preparing the composite board with electromagnetic shielding performance, and adopts a special hot pressing method for the pre-treated mixed fiber felt after needling.

Firstly, after the mixed fiber felt is subjected to needling treatment, modified polypropylene fibers, terylene and carbon fibers in the mixed fiber felt can be needled into the modified hollow microspheres, so that the bonding force among the fibers after hot pressing can be improved, and the bending strength of a product is further improved; the modified hollow microspheres added in the invention can be used as weight-reducing materials, and the density of the product can be effectively reduced after the modified hollow microspheres are added into the product, so that the weight of the product is reduced, and the practicability of the product is improved;

finally, the method adopts a special hot pressing method for the pre-treated mixed fiber felt after needling, the temperature is not increased at the initial stage of hot pressing, only the pre-treated mixed fiber felt is properly extruded to a certain extent, and the atmospheric pressure around the product is increased in the pressurizing process, so that gas can enter the modified hollow microspheres at the initial stage of hot pressing; then, the temperature in the hot press is raised, and the temperature raising process is carried out in a constant pressure environment, so that the molten modified polypropylene fibers can keep a certain balance inside and outside the hollow microspheres, and the modified polypropylene fibers in the modified hollow microspheres can not be too much or too little; when the temperature reaches 220 ℃, pressurizing and irradiating, and decompressing the air in the hot press; because the acrylic acid is adsorbed on the inner wall of the modified hollow microsphere under the action of the covalent bond, under the irradiation condition, the fused acrylic acid and the acrylic acid on the inner wall of the modified hollow microsphere can form a cross-linked network, so that the strength of the modified hollow microsphere is improved, further the strength of a product is improved, and simultaneously, under the action of the pressure increase of a hot press, the air pressure in the modified hollow microsphere cannot be released, so that the fused modified polypropylene fiber can be attached to the inner wall of the modified hollow microsphere, further, the modified graphene oxide is embedded in the cross-linked network formed by the polypropylene and the acrylic acid and uniformly paved in the modified hollow microsphere, and the product is endowed with better sound insulation and radiation protection performance while the weight of the product is reduced on the premise of keeping the hollow of the modified hollow microsphere.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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 of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe the method in detail, and the method for testing each index of the composite board with electromagnetic shielding performance manufactured in the following examples is as follows:

bending strength: the composite board with electromagnetic shielding performance obtained in each example and the comparative product are tested for the bending strength of each sample according to GB/T1449.

Electromagnetic shielding performance: the composite boards with electromagnetic shielding performance obtained in each example and the comparative example products were measured for their electromagnetic shielding performance at electromagnetic wave frequencies of 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, and 9.5 GHz.

Density: the weight per unit area of the composite sheet having electromagnetic shielding properties obtained in each example and the comparative example was measured.

Noise reduction performance: the acoustic transmission loss of the composite board with electromagnetic shielding performance obtained in each example and the comparative product under the condition that the acoustic frequency is 1, 2, 3, 4 and 5kHz is measured according to GB/T18696.

Example 1

A composite board with electromagnetic shielding performance mainly comprises the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres.

The preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to the mass ratio of 1:20, adding starch with the mass of 0.125 times of that of the styrene and maleic anhydride with the mass of 0.0125 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at the speed of 30mL/min, removing air, heating the materials in the three-neck flask to 120 ℃, stirring and pre-polymerizing for 1.5h to obtain a pre-polymerized styrene mixture, mixing the pre-polymerized styrene mixture and the styrene according to the mass ratio of 1:2.5, adding benzoyl peroxide with the mass of 0.02 times of that of the pre-polymerized styrene mixture, stirring and mixing for 40min under the conditions of the temperature of 65 ℃ and the rotating speed of 350r/min to obtain a pre-polymerized styrene dispersion, mixing the pre-polymerized styrene dispersion and a hydroxyethyl cellulose solution with the mass fraction of 1% in a volume ratio of 1:5 into the flask, carrying out suspension polymerization, cooling the materials in the beaker to 40 ℃, carrying out suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 4 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at 160 ℃ for 40min to obtain hollow microspheres, mixing the hollow microspheres and water in a mass ratio of 1:12 in a flask, adding potassium periodate which is 0.1 time of the mass of hollow microsphere blanks into the flask, stirring and reacting for 2h at the temperature of 80 ℃ and the rotating speed of 500r/min, filtering to obtain filter cakes, mixing the filter cakes and a sodium hydroxide solution with the mass fraction of 2% in a mass ratio of 1:15, adding acrylic acid which is 4 times of the mass of the filter cakes into the mixture of the filter cakes and the sodium hydroxide solution, stirring and mixing for 3h at the temperature of 50 ℃ and the rotating speed of 400r/min, filtering to obtain filter residues, and drying the filter residues for 2h at the temperature of 85 ℃ to obtain modified hollow microspheres;

(3) mixing the modified graphene oxide and polypropylene according to a mass ratio of 7:100, stirring and mixing at the temperature of 170 ℃ to obtain a spinning solution, extruding the spinning solution through a spinneret orifice, and cooling and forming to obtain a modified polypropylene fiber with the diameter of 0.8mm and the length of 80 mm; weighing the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber and 30 parts ofTerylene and 15 parts of modified hollow microspheres; mixing modified polypropylene fibers and carbon fibers, adding terylene and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the modified hollow microspheres with the gram weight of 550g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

As an optimization, the suspension polymerization in the step (1) is carried out for 3 hours under the condition of firstly reacting at 80 ℃, then for 2 hours under the condition of 90 ℃, and finally for 1 hour under the condition of 120 ℃.

As an optimization, the preparation method of the modified graphene oxide in the step (3) comprises the steps of mixing graphene oxide and water according to a mass ratio of 1:100, adding ethylenediamine which is 15 times of the mass of the graphene oxide, stirring and mixing for 5 hours at the temperature of 80 ℃, then carrying out ultrasonic dispersion for 10 minutes at the frequency of 50kHz, filtering and drying to obtain a modified graphene oxide blank, mixing the modified graphene oxide blank and a copper nitrate solution with a mass fraction of 5% according to a mass ratio of 1:10, filtering and drying to obtain the modified graphene oxide.

As optimization, the process condition of the pre-needling reinforcement treatment in the step (3) is 75 pricking points/cm²(ii) a The technological condition of the main needling reinforcement treatment is 250 needling points/cm²。

As an optimization, the hot pressing treatment method in the step (4) comprises the following steps: increasing the pressure of a hot press to 1.5MPa at room temperature, introducing air into the hot press to increase the air pressure in the hot press to 1MPa, continuously increasing the temperature constant pressure in the hot press to 220 ℃ after 30s, performing irradiation treatment on the pretreated mixed fiber felt by using an electron accelerator, wherein the irradiation measurement is 20kGy, simultaneously releasing the pressure of the air in the hot press, increasing the pressure of the hot press to 5MPa, and pressing for 80s at the temperature of 220 ℃ and the pressure of 5 MPa.

Example 2

A composite board with electromagnetic shielding performance mainly comprises the following components in parts by weight: 45 parts of polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres.

The preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to the mass ratio of 1:20, adding starch with the mass of 0.125 times of that of the styrene and maleic anhydride with the mass of 0.0125 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at the speed of 30mL/min, removing air, heating the materials in the three-neck flask to 120 ℃, stirring and pre-polymerizing for 1.5h to obtain a pre-polymerized styrene mixture, mixing the pre-polymerized styrene mixture and the styrene according to the mass ratio of 1:2.5, adding benzoyl peroxide with the mass of 0.02 times of that of the pre-polymerized styrene mixture, stirring and mixing for 40min under the conditions of the temperature of 65 ℃ and the rotating speed of 350r/min to obtain a pre-polymerized styrene dispersion, mixing the pre-polymerized styrene dispersion and a hydroxyethyl cellulose solution with the mass fraction of 1% in a volume ratio of 1:5 into the flask, carrying out suspension polymerization, cooling the materials in the beaker to 40 ℃, carrying out suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 4 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at 160 ℃ for 40min to obtain hollow microspheres, mixing the hollow microspheres and water in a mass ratio of 1:12 in a flask, adding potassium periodate which is 0.1 time of the mass of the hollow microspheres into the flask, stirring and reacting for 2h at 80 ℃ and 500r/min, filtering to obtain a filter cake, mixing the filter cake and a sodium hydroxide solution with the mass fraction of 2% in a mass ratio of 1:15, adding acrylic acid which is 4 times of the mass of the filter cake into the mixture of the filter cake and the sodium hydroxide solution, stirring and mixing for 3h at 50 ℃ and 400r/min, filtering to obtain filter residues, and drying the filter residues for 2h at 85 ℃ to obtain the hollow microspheres;

(3) mixing polypropylene at 170 deg.C under stirring to obtain spinning solution, and spraying the spinning solutionExtruding the filaments through the filament holes, and cooling and forming to obtain polypropylene fibers with the diameter of 0.8mm and the length of 80 mm; weighing the following components in parts by weight: 45 parts of polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres; mixing polypropylene fibers and carbon fibers, adding terylene and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the product with the gram weight of 550g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

As an optimization, the suspension polymerization in the step (1) is carried out for 3 hours under the condition of firstly reacting at 80 ℃, then for 2 hours under the condition of 90 ℃, and finally for 1 hour under the condition of 120 ℃.

As optimization, the process condition of the pre-needling reinforcement treatment in the step (3) is 75 pricking points/cm²(ii) a The technological condition of the main needling reinforcement treatment is 250 needling points/cm²。

As an optimization, the hot pressing treatment method in the step (4) comprises the following steps: increasing the pressure of a hot press to 1.5MPa at room temperature, introducing air into the hot press to increase the air pressure in the hot press to 1MPa, continuously increasing the temperature constant pressure in the hot press to 220 ℃ after 30s, performing irradiation treatment on the pretreated mixed fiber felt by using an electron accelerator, wherein the irradiation measurement is 20kGy, simultaneously releasing the pressure of the air in the hot press, increasing the pressure of the hot press to 5MPa, and pressing for 80s at the temperature of 220 ℃ and the pressure of 5 MPa.

Example 3

A composite board with electromagnetic shielding performance mainly comprises the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of hollow microspheres.

The preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to the mass ratio of 1:20, adding starch with the mass of 0.125 times of that of the styrene and maleic anhydride with the mass of 0.0125 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at the speed of 30mL/min, removing air, heating the materials in the three-neck flask to 120 ℃, stirring and pre-polymerizing for 1.5h to obtain a pre-polymerized styrene mixture, mixing the pre-polymerized styrene mixture and the styrene according to the mass ratio of 1:2.5, adding benzoyl peroxide with the mass of 0.02 times of that of the pre-polymerized styrene mixture, stirring and mixing for 40min under the conditions of the temperature of 65 ℃ and the rotating speed of 350r/min to obtain a pre-polymerized styrene dispersion, mixing the pre-polymerized styrene dispersion and a hydroxyethyl cellulose solution with the mass fraction of 1% in a volume ratio of 1:5 into the flask, carrying out suspension polymerization, cooling the materials in the beaker to 40 ℃, carrying out suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 4 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at 160 ℃ for 40min to obtain hollow microspheres;

(3) mixing the modified graphene oxide and polypropylene according to a mass ratio of 7:100, stirring and mixing at the temperature of 170 ℃ to obtain a spinning solution, extruding the spinning solution through a spinneret orifice, and cooling and forming to obtain a modified polypropylene fiber with the diameter of 0.8mm and the length of 80 mm; weighing the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres; mixing modified polypropylene fibers and carbon fibers, adding terylene and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the modified hollow microspheres with the gram weight of 550g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

As an optimization, the suspension polymerization in the step (1) is carried out for 3 hours under the condition of firstly reacting at 80 ℃, then for 2 hours under the condition of 90 ℃, and finally for 1 hour under the condition of 120 ℃.

As an optimization, the preparation method of the modified graphene oxide in the step (3) comprises the steps of mixing graphene oxide and water according to a mass ratio of 1:100, adding ethylenediamine which is 15 times of the mass of the graphene oxide, stirring and mixing for 5 hours at the temperature of 80 ℃, then carrying out ultrasonic dispersion for 10 minutes at the frequency of 50kHz, filtering and drying to obtain a modified graphene oxide blank, mixing the modified graphene oxide blank and a copper nitrate solution with a mass fraction of 5% according to a mass ratio of 1:10, filtering and drying to obtain the modified graphene oxide.

As optimization, the process condition of the pre-needling reinforcement treatment in the step (3) is 75 pricking points/cm²(ii) a The technological condition of the main needling reinforcement treatment is 250 needling points/cm²。

As an optimization, the hot pressing treatment method in the step (4) comprises the following steps: increasing the pressure of a hot press to 1.5MPa at room temperature, introducing air into the hot press to increase the air pressure in the hot press to 1MPa, continuously increasing the temperature constant pressure in the hot press to 220 ℃ after 30s, performing irradiation treatment on the pretreated mixed fiber felt by using an electron accelerator, wherein the irradiation measurement is 20kGy, simultaneously releasing the pressure of the air in the hot press, increasing the pressure of the hot press to 5MPa, and pressing for 80s at the temperature of 220 ℃ and the pressure of 5 MPa.

Example 4

A composite board with electromagnetic shielding performance mainly comprises the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres.

The preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to the mass ratio of 1:20, adding starch with the mass of 0.125 times of that of the styrene and maleic anhydride with the mass of 0.0125 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at the speed of 30mL/min, removing air, heating the materials in the three-neck flask to 120 ℃, stirring and pre-polymerizing for 1.5h to obtain a pre-polymerized styrene mixture, mixing the pre-polymerized styrene mixture and the styrene according to the mass ratio of 1:2.5, adding benzoyl peroxide with the mass of 0.02 times of that of the pre-polymerized styrene mixture, stirring and mixing for 40min under the conditions of the temperature of 65 ℃ and the rotating speed of 350r/min to obtain a pre-polymerized styrene dispersion, mixing the pre-polymerized styrene dispersion and a hydroxyethyl cellulose solution with the mass fraction of 1% in a volume ratio of 1:5 into the flask, carrying out suspension polymerization, cooling the materials in the beaker to 40 ℃, carrying out suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 4 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at 160 ℃ for 40min to obtain hollow microspheres, mixing the hollow microspheres and water in a mass ratio of 1:12 in a flask, adding potassium periodate which is 0.1 time of the mass of hollow microsphere blanks into the flask, stirring and reacting for 2h at the temperature of 80 ℃ and the rotating speed of 500r/min, filtering to obtain filter cakes, mixing the filter cakes and a sodium hydroxide solution with the mass fraction of 2% in a mass ratio of 1:15, adding acrylic acid which is 4 times of the mass of the filter cakes into the mixture of the filter cakes and the sodium hydroxide solution, stirring and mixing for 3h at the temperature of 50 ℃ and the rotating speed of 400r/min, filtering to obtain filter residues, and drying the filter residues for 2h at the temperature of 85 ℃ to obtain modified hollow microspheres;

(3) mixing the modified graphene oxide and polypropylene according to a mass ratio of 7:100, stirring and mixing at the temperature of 170 ℃ to obtain a spinning solution, extruding the spinning solution through a spinneret orifice, and cooling and forming to obtain a modified polypropylene fiber with the diameter of 0.8mm and the length of 80 mm; weighing the following components in parts by weight: 45 parts of modified polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres; mixing modified polypropylene fibers and carbon fibers, adding terylene and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the modified hollow microspheres with the gram weight of 550g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

As an optimization, the suspension polymerization in the step (1) is carried out for 3 hours under the condition of firstly reacting at 80 ℃, then for 2 hours under the condition of 90 ℃, and finally for 1 hour under the condition of 120 ℃.

As an optimization, the preparation method of the modified graphene oxide in the step (3) comprises the steps of mixing graphene oxide and water according to a mass ratio of 1:100, adding ethylenediamine which is 15 times of the mass of the graphene oxide, stirring and mixing for 5 hours at the temperature of 80 ℃, then carrying out ultrasonic dispersion for 10 minutes at the frequency of 50kHz, filtering and drying to obtain a modified graphene oxide blank, mixing the modified graphene oxide blank and a copper nitrate solution with a mass fraction of 5% according to a mass ratio of 1:10, filtering and drying to obtain the modified graphene oxide.

As optimization, the process condition of the pre-needling reinforcement treatment in the step (3) is 75 pricking points/cm²(ii) a The technological condition of the main needling reinforcement treatment is 250 needling points/cm²。

As an optimization, the hot pressing treatment method in the step (4) comprises the following steps: hot pressing for 90s under the conditions that the temperature is 220 ℃, the pressure is 5MPa and the irradiation dose is 20 kGy.

Comparative example

A composite board with electromagnetic shielding performance mainly comprises the following components in parts by weight: 45 parts of polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of hollow microspheres.

The preparation method of the composite board with the electromagnetic shielding performance mainly comprises the following preparation steps:

(1) mixing benzoyl peroxide and styrene in a three-neck flask according to the mass ratio of 1:20, adding starch with the mass of 0.125 times of that of the styrene and maleic anhydride with the mass of 0.0125 times of that of the styrene into the three-neck flask, introducing nitrogen into the three-neck flask at the speed of 30mL/min, removing air, heating the materials in the three-neck flask to 120 ℃, stirring and pre-polymerizing for 1.5h to obtain a pre-polymerized styrene mixture, mixing the pre-polymerized styrene mixture and the styrene according to the mass ratio of 1:2.5, adding benzoyl peroxide with the mass of 0.02 times of that of the pre-polymerized styrene mixture, stirring and mixing for 40min under the conditions of the temperature of 65 ℃ and the rotating speed of 350r/min to obtain a pre-polymerized styrene dispersion, mixing the pre-polymerized styrene dispersion and a hydroxyethyl cellulose solution with the mass fraction of 1% in a volume ratio of 1:5 into the flask, carrying out suspension polymerization, cooling the materials in the beaker to 40 ℃, carrying out suction filtration to obtain a pretreated hollow microsphere blank, and washing the pretreated hollow microsphere blank with water for 4 times to obtain pretreated hollow microspheres;

(2) foaming the pretreated hollow microspheres obtained in the step (1) at 160 ℃ for 40min to obtain hollow microspheres;

(3) stirring and mixing polypropylene at the temperature of 170 ℃ to obtain spinning solution, extruding the spinning solution through a spinneret orifice, and cooling and forming to obtain polypropylene fibers with the diameter of 0.8mm and the length of 80 mm; weighing the following components in parts by weight: 45 parts of polypropylene fiber, 10 parts of carbon fiber, 30 parts of terylene and 15 parts of modified hollow microspheres; mixing polypropylene fibers and carbon fibers, adding terylene and the modified hollow microspheres obtained in the step (2), stirring and mixing to obtain a mixture, carding and forming a net to obtain a mixed fiber felt, and sequentially carrying out pre-needling reinforcement treatment and main needling reinforcement treatment on the mixed fiber felt to obtain the product with the gram weight of 550g/m²The pre-treated mixed fiber mat of (1);

(4) and (3) carrying out hot pressing treatment on the pretreated mixed fiber felt in a hot press to obtain the composite board with the electromagnetic shielding performance.

As an optimization, the suspension polymerization in the step (1) is carried out for 3 hours under the condition of firstly reacting at 80 ℃, then for 2 hours under the condition of 90 ℃, and finally for 1 hour under the condition of 120 ℃.

As optimization, the process condition of the pre-needling reinforcement treatment in the step (3) is 75 pricking points/cm²(ii) a The technological condition of the main needling reinforcement treatment is 250 needling points/cm²。

As an optimization, the hot pressing treatment method in the step (4) comprises the following steps: hot pressing for 90s under the conditions that the temperature is 220 ℃, the pressure is 5MPa and the irradiation dose is 20 kGy.

Effect example 1

Table 1 below shows the results of the flexural strength and density analysis of the composite sheet having electromagnetic shielding properties using examples 1 to 4 of the present invention and comparative example.

TABLE 1

Effect example 2

Table 2 below shows the results of the electromagnetic shielding performance analysis of the composite sheets having electromagnetic shielding performance using examples 1 to 4 of the present invention and comparative example.

TABLE 2

Effect example 3

Table 3 below shows the noise reduction performance analysis results of the composite sheets having electromagnetic shielding performance using examples 1 to 4 of the present invention and a comparative example.

TABLE 3

From the comparison of the experimental data of the example 1 and the comparative example in tables 1, 2 and 3, it can be found that the product has good electromagnetic shielding performance and noise reduction performance, and simultaneously has excellent mechanical properties and lower density by adding the modified polypropylene fiber and the modified hollow microsphere when preparing the composite board with electromagnetic shielding performance and using a special hot-pressing process during hot pressing; as can be seen from the comparison of the experimental data obtained in table 1, table 2 and table 3, in example 1 and example 2, when the modified polypropylene fiber is not used in the preparation of the composite board with electromagnetic shielding performance, the fiber does not contain the modified graphene, and therefore, the electromagnetic shielding performance and the strength of the product are reduced; as can be seen from the comparison of the experimental data of example 1 and example 3 in tables 1, 2 and 3, when the composite board with the electromagnetic shielding performance is prepared, the hollow microspheres are not modified, so that gaps of the hollow microspheres are blocked in the preparation process of the product, and the modified graphene cannot be uniformly dispersed, so that the electromagnetic shielding performance and the noise reduction performance of the product are remarkably reduced; from the comparison of the experimental data of example 1 and example 4 in tables 1, 2 and 3, it can be seen that, when a specific hot pressing process is not used in preparing the product, the voids in the modified hollow microspheres in the product disappear, and the modified graphene is unevenly distributed, thereby greatly improving the performance of the product.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.