阅读说明：本技术 一种具有多层泡孔结构的聚合物电磁屏蔽复合材料及其制备方法 (Polymer electromagnetic shielding composite material with multilayer cellular structure and preparation method thereof ) 是由 廖霞 杨建明 周荣涛 王圭 唐婉玉 李光宪 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种具有多层泡孔结构的聚合物电磁屏蔽复合材料及其制备方法；制备时先在纤维的表面负载导电金属,制得高导电纤维；然后将高导电纤维与聚合物混合得到高导电复合材料层,分别将不同含量的碳系填料与聚合物混合得到碳系填料填充的复合材料层；最后将两种复合材料层结合并对其进行发泡处理得到具有多层泡孔结构电磁屏蔽复合材料。采用本发明中的方法可有效提高电磁屏蔽复合泡沫的电磁屏蔽效能,增强复合泡沫吸收电磁波的性能,所制备的多孔材料兼具优异的电磁屏蔽效能与吸收电磁波性能,有效解决了电磁屏蔽复合材料屏蔽效能低、二次电磁波污染严重的问题。(The invention discloses a polymer electromagnetic shielding composite material with a multilayer cellular structure and a preparation method thereof; when in preparation, conductive metal is loaded on the surface of the fiber to prepare the high-conductivity fiber; then mixing the high-conductivity fibers with the polymer to obtain a high-conductivity composite material layer, and respectively mixing the carbon fillers with different contents with the polymer to obtain a composite material layer filled with the carbon fillers; and finally combining the two composite material layers and carrying out foaming treatment on the two composite material layers to obtain the electromagnetic shielding composite material with the multilayer cellular structure. The method can effectively improve the electromagnetic shielding effectiveness of the electromagnetic shielding composite foam, enhance the electromagnetic wave absorption performance of the composite foam, and effectively solve the problems of low shielding effectiveness and serious secondary electromagnetic wave pollution of the electromagnetic shielding composite material.)

1. A method for preparing a polymeric electromagnetic shielding composite having a multi-layer cellular structure, comprising the steps of:

s1: loading conductive metal on the surface of the fiber to obtain conductive fiber;

s2: preparing a conductive fiber-polymer composite;

s3: preparing different types of carbon-based filler-polymer composite materials, wherein the carbon-based filler content in each carbon-based filler-polymer composite material is different;

s4: superposing the multiple carbon-based filler-polymer composite materials obtained in the step S3 on the conductive fiber-polymer composite material obtained in the step S2 layer by layer to obtain a multilayer composite material;

s5: and (3) placing the multilayer composite material obtained in the step (S4) in a reaction device, introducing foaming gas, saturating for 5 min-24 h at the temperature of 0-300 ℃ and under the pressure of 0.2-50 MPa, then relieving pressure to normal pressure at the speed of 0.1-30 MPa/S, and cooling to room temperature to obtain the porous electromagnetic shielding composite material.

2. The method for preparing the polymer electromagnetic shielding composite material with the multilayer cellular structure according to claim 1, wherein the conductive metal loaded on the surface of the conductive fiber is silver, copper, nickel, aluminum, iron or tungsten, and the method is prepared by the following steps:

SS 1: coarsening and sensitizing the fiber in sequence;

SS 2: and adding the sensitized fiber into a chemical plating solution containing silver, copper, nickel, aluminum, iron or tungsten according to a material-to-liquid ratio of 1g: 10-80 mL, then adding a reducing agent solution, stirring and reacting for 10 min-5 h, washing and drying to obtain the conductive fiber.

3. The method for preparing a polymeric electromagnetic shielding composite material with a multi-layered cell structure according to claim 1 or 2, wherein: the fiber is glass fiber, quartz glass fiber, ceramic fiber, carbon fiber, asbestos fiber or basalt fiber.

4. The method for preparing a polymer electromagnetic shielding composite material with a multi-layer cellular structure according to claim 1, wherein the conductive fiber-polymer composite material is prepared by the following steps: dissolving a polymer in a solvent to prepare a polymer solution, adding conductive fibers into the polymer solution, and ultrasonically stirring for 5 min-1 h to obtain a conductive fiber-polymer composite material; the mass ratio of the polymer to the conductive fibers is 1: 1-10: 1.

5. The method for preparing a polymer electromagnetic shielding composite material with a multi-layer cellular structure according to claim 1, wherein the carbon-based filler-polymer composite material is prepared by the following steps: dissolving a polymer in a solvent to prepare a polymer solution, adding a carbon-based filler into the polymer solution, and ultrasonically stirring for 5 min-1 h to obtain a carbon-based filler-polymer composite material; the mass ratio of the polymer to the carbon-based filler is 9.7:0.3 to 9.9: 0.1.

6. The method for preparing a polymeric electromagnetic shielding composite material with a multi-layer cellular structure according to claim 1, wherein: the carbon-based filler is carbon fiber, carbon nano tube, graphene, carbon nano fiber, nano graphite sheet, graphite, carbon black or fullerene.

7. The method for preparing a polymeric electromagnetic shielding composite material with a multi-layered cell structure according to claim 4 or 5, wherein: the polymer is polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyamide, vinyl acetate copolymer, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyurethane, polylactic acid, polyglycolic acid, polycaprolactone, polyvinyl alcohol, epoxy resin, urea resin, furan resin, melamine formaldehyde resin, silicone resin, polyarylate, acrylate, phenol resin, polyether ether ketone, polysulfone, polyphenylene sulfide, polyimide, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, fluorine rubber, silicone rubber, thermoplastic polystyrene elastomer, thermoplastic polyolefin elastomer, thermoplastic copolyester elastomer, thermoplastic polyamide elastomer, or thermoplastic polyurethane elastomer.

8. The method for preparing a polymeric electromagnetic shielding composite material with a multi-layered cell structure according to claim 4 or 5, wherein: the solvent is ethanol, methanol, isopropanol, ethylene glycol, diethyl ether, acetone, hexane, cyclohexane, pentane, heptane, octane, aniline, butanone, chloroform, dimethylamine, carbon tetrachloride, N-heptanol, tetrahydrofuran, benzene, toluene, xylene, ethylbenzene, butyl acetate, trichloromethane, formic acid, dimethyl sulfoxide, chlorobenzene, dichlorobenzene, dichloromethane, trichloroethylene or N-methylpyrrolidone.

9. The method for preparing a polymeric electromagnetic shielding composite material with a multi-layer cellular structure according to claim 1, wherein: the foaming gas is air, nitrogen, carbon dioxide, helium, argon, petroleum ether, methane, ethane, propane, butane, pentane, hexane, heptane, n-pentane, n-hexane, n-heptane, dichloromethane or trichlorofluoromethane.

10. The polymer electromagnetic shielding composite material with the multilayer cellular structure prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the field of electromagnetic shielding composite materials, and particularly relates to a polymer electromagnetic shielding composite material with a multilayer cellular structure and a preparation method thereof.

Background

With the rapid development of electronic information technology, various electronic components and communication equipment have been greatly popularized and applied. The wide use of these electronic devices brings great convenience to people and also produces a great deal of electromagnetic wave pollution, which not only seriously interferes with the normal operation of mobile phones, computers, hospital instruments and the like, but also threatens the health of human bodies. For this reason, various electromagnetic shielding composite materials have been developed, but these electromagnetic shielding composite materials generally have disadvantages of low shielding effectiveness and high proportion of reflected electromagnetic waves. Meanwhile, the emerging fields of the 5G communication industry, high-power electronic equipment, aerospace and the like have high requirements on the anti-interference capability of signals, and a lighter electromagnetic shielding composite material is needed to save energy consumption in the use process, so that a great deal of light electromagnetic shielding materials with high shielding efficiency and high absorption capability are needed in the future.

For conventional electromagnetic shielding composites, the shielding effectiveness is determined by the conductivity of the material and the perfection of the conductive network, both of which are determined by the conductive properties and the amount of filler added. In order to obtain good conductivity, more conductive fillers (such as metal fibers, carbon nanotubes, graphene, carbon black, and the like) need to be added. However, the addition of these fillers in large amounts in the polymer matrix can cause a large impedance mismatch between the composite and air, resulting in a large amount of electromagnetic wave reflection, causing severe secondary electromagnetic wave contamination. The electromagnetic shielding composite material with light weight and a multilayer cellular structure is prepared by utilizing a multilayer structure design and combining a high-pressure gas foaming technology, and is a new method for solving the problem of high electromagnetic wave reflection ratio at present.

In addition, the conductive fiber with excellent conductivity can be prepared by loading the conductive metal particles on the surface of the fiber by adopting a chemical plating method, which is beneficial to enhancing the lapping efficiency of the metal particles in the polymer matrix and improving the electromagnetic shielding efficiency of the polymer composite material. At present, the technology of combining high-pressure gas foaming and multilayer compounding is not utilized to prepare the electromagnetic shielding composite material with a multilayer cellular structure.

Disclosure of Invention

In view of the above prior art, the present invention provides a polymer electromagnetic shielding composite material with a multi-layer cellular structure and a preparation method thereof, and the porous composite material has good electromagnetic shielding performance and electromagnetic wave absorption performance.

In order to achieve the purpose, the invention adopts the technical scheme that: there is provided a method for preparing a polymeric electromagnetic shielding composite having a multi-layer cellular structure, comprising the steps of:

s1: loading conductive metal on the surface of the fiber to obtain conductive fiber;

s2: preparing a conductive fiber-polymer composite;

s3: preparing different types of carbon-based filler-polymer composite materials, wherein the carbon-based filler content in each carbon-based filler-polymer composite material is different;

s4: superposing the multiple carbon-based filler-polymer composite materials obtained in the step S3 on the conductive fiber-polymer composite material obtained in the step S2 layer by layer to obtain a multilayer composite material;

s5: and (3) placing the multilayer composite material obtained in the step (S4) in a reaction device, introducing foaming gas, saturating for 5 min-24 h at the temperature of 0-300 ℃ and under the pressure of 0.2-50 MPa, then relieving pressure to normal pressure at the speed of 0.1-30 MPa/S, and cooling to room temperature to obtain the porous electromagnetic shielding composite material.

On the basis of the technical scheme, the preparation method can be further improved as follows.

Further, the conductive metal loaded on the surface of the conductive fiber is silver, copper, nickel, aluminum, iron or tungsten, and the conductive fiber is prepared by the following steps:

SS 1: coarsening and sensitizing the fiber in sequence;

SS 2: and adding the sensitized fiber into a chemical plating solution containing silver, copper, nickel, aluminum, iron or tungsten according to a material-to-liquid ratio of 1g: 10-80 mL, then adding a reducing agent solution, stirring and reacting for 10 min-5 h, washing and drying to obtain the conductive fiber.

Further, the coarsening method of the conductive fiber comprises the following steps: adding the fibers into dilute sulfuric acid according to the feed-liquid ratio of 1g: 10-100 mL, stirring for reaction for 10 min-5 h, and then washing and filtering to finish coarsening.

Further, the fiber is glass fiber, quartz glass fiber, ceramic fiber, carbon fiber, asbestos fiber or basalt fiber.

Further, the conductive fiber-polymer composite material is prepared by the following steps: dissolving a polymer in a solvent to prepare a polymer solution, adding conductive fibers into the polymer solution, and ultrasonically stirring for 5 min-1 h to obtain a conductive fiber-polymer composite material; the mass ratio of the polymer to the conductive fibers is 1: 1-10: 1.

Further, the carbon-based filler-polymer composite material is prepared by the following steps: dissolving a polymer in a solvent to prepare a polymer solution, adding a carbon-based filler into the polymer solution, and ultrasonically stirring for 5 min-1 h to obtain a carbon-based filler-polymer composite material; the mass ratio of the polymer to the carbon-based filler is 9.7:0.3 to 9.9: 0.1.

Further, the carbon-based filler is carbon fiber, carbon nanotube, graphene, carbon nanofiber, graphite nanoplatelet, graphite, carbon black, or fullerene.

Further, the polymer is polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyamide, vinyl acetate copolymer, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyurethane, polylactic acid, polyglycolic acid, polycaprolactone, polyvinyl alcohol, epoxy resin, urea resin, furan resin, melamine formaldehyde resin, silicone resin, polyarylate, acrylate, phenol resin, polyether ether ketone, polysulfone, polyphenylene sulfide, polyimide, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, fluorine rubber, silicone rubber, thermoplastic polystyrene elastomer, thermoplastic polyolefin elastomer, thermoplastic copolyester elastomer, thermoplastic polyamide elastomer, or thermoplastic polyurethane elastomer.

Further, the solvent is ethanol, methanol, isopropanol, ethylene glycol, diethyl ether, acetone, hexane, cyclohexane, pentane, heptane, octane, aniline, butanone, chloroform, dimethylamine, carbon tetrachloride, N-heptanol, tetrahydrofuran, benzene, toluene, xylene, ethylbenzene, butyl acetate, chloroform, formic acid, dimethyl sulfoxide, chlorobenzene, dichlorobenzene, dichloromethane, trichloroethylene, or N-methylpyrrolidone.

Further, the foaming gas is air, nitrogen, carbon dioxide, helium, argon, petroleum ether, methane, ethane, propane, butane, pentane, hexane, heptane, n-pentane, n-hexane, n-heptane, dichloromethane, or trichlorofluoromethane.

The invention utilizes the method of combining multilayer compounding and high-pressure gas foaming to prepare the polymer electromagnetic shielding composite material with the multilayer cellular structure, the method effectively increases the electromagnetic shielding effectiveness of the composite material, improves the absorption efficiency of the material on electromagnetic waves, and the prepared composite material has excellent electromagnetic shielding effectiveness and electromagnetic wave absorption performance, the proportion of the electromagnetic waves absorbed can reach 66 percent, the electromagnetic shielding effectiveness can reach 76dB, and the requirements of the electromagnetic shielding material for commercial application are far exceeded.

The invention has the beneficial effects that:

1. the invention obtains the high-conductivity metal-plated fiber by a chemical plating method, effectively strengthens the conductive path of the metal particles after the conductive fiber and the polymer are compounded, and improves the conductivity of the composite material.

2. The polymer electromagnetic shielding composite material with the multilayer cellular structure has excellent electromagnetic shielding efficiency and electromagnetic wave absorption coefficient, and simultaneously, the density of the material can be further reduced by introducing the cells, so that the application field of the electromagnetic shielding composite material is improved.

3. The high-pressure gas foaming method used by the invention has the advantages of simple operation and low cost.

Drawings

FIG. 1 is a scanning electron microscope image of a metallic silver-loaded glass fiber prepared in example 2;

FIG. 2 is a scanning electron microscope image of a cross section of the polymer electromagnetic shielding composite having a multi-layered cell structure prepared in example 2;

fig. 3 is a graph showing electromagnetic shielding effectiveness and electromagnetic wave absorption coefficient of the polymer electromagnetic shielding composite having a multi-layered cell structure prepared in example 4.

Detailed Description

The following examples are provided to illustrate specific embodiments of the present invention.