Electromagnetic shielding polyester molding compound and method for producing the same

Abstract

This invention provides an electromagnetic shielding polyester molding compound and its preparation method. The preparation method of the electromagnetic shielding polyester molding compound includes the following steps: mixing and dispersing unsaturated polyester resin and low-shrinkage additives to obtain a mixture; adding porous aluminum foam filaments, three-dimensional titanium dioxide nanowire particles, and calcium stearate powder, and dispersing them evenly to obtain a dispersion; adding tert-butyl peroxide to the dispersion and mixing to obtain a resin paste; and curing the resin paste to obtain the electromagnetic shielding polyester molding compound. This invention, by adding porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles to unsaturated polyester resin, allows the porous aluminum foam filaments to form a large-frame conductive network within the polyester film, while the micro-three-dimensional structure of the three-dimensional titanium dioxide nanowire particles forms a micro-conductive network, thus improving the large-frame conductive network. The combination of these two elements forms a complete conductive network, achieving excellent electromagnetic shielding performance.

Description

Technical Field

[0001] This invention relates to the technical field of plastic materials, specifically to an electromagnetic shielding polyester molding compound and its preparation method. Background Technology

[0002] With the rapid development of science and technology, more and more electronic devices and products are entering people's work and lives. Electronic technology has permeated all walks of life, leading to a dramatic increase in the density of electronic devices, their transmission power, and the energy density of interference signals. This results in a decline in the performance of equipment, transmission channels, or systems. Electronic and communication equipment is not only highly sensitive to surrounding electromagnetic interference during use, but it also generates electromagnetic interference in the surrounding environment, affecting other equipment and even the growth and health of plants and animals. Therefore, electromagnetic radiation has become another major public hazard after solid waste pollution, air pollution, water pollution, and noise pollution. Currently, the main way to eliminate the hazards of electromagnetic radiation is to use electromagnetic shielding materials for shielding.

[0003] Electromagnetic shielding utilizes shielding materials to block external electromagnetic energy from reaching the shielded area or to attenuate the propagation of electromagnetic energy between the shielded area and the outside world. To address the impact of electromagnetic interference on equipment, most electronic devices currently use metals such as aluminum, steel, and iron for their components to achieve electromagnetic interference resistance; however, these materials are relatively expensive. CN104853577A discloses an ultrathin electromagnetic shielding film and its preparation method, which involves setting an adhesive layer into a mesh structure and filling the mesh pores of the adhesive layer with conductive metal to form a mesh-like electromagnetic shielding layer, thus achieving electromagnetic shielding. However, the edges and corners of the mesh cannot fully contact the metal, leading to an increase in the conductivity of the electromagnetic shielding film and negatively impacting its electromagnetic shielding performance. CN107083221A discloses an aluminum-based composite adhesive for electromagnetic shielding, composed of the following components by weight percentage: 35-45% epoxy resin, 1-3% amine curing agent, 35-50% aluminum powder, 5-15% ferrite powder, and 1-3% dioctyl phthalate. By adding a certain amount of aluminum powder and ferrite powder to the adhesive components, it is used to connect aluminum foam materials, ensuring structural integrity and sealing while providing a certain degree of electromagnetic shielding. However, its application range as an adhesive is limited, and the large proportion of filler is detrimental to maintaining mechanical properties.

[0004] Molding compounds are a type of plastic. Compared to common thermoplastics, molding compounds have higher dimensional stability, better resistance to extreme high-temperature and high-humidity environments, resistance to chemical corrosion, and high mechanical strength. To reduce costs and weight, SMC (sheet molding compound) can be used to replace metal materials. However, the SMC must be resistant to electromagnetic interference to meet the requirements of GB / T 17626.3-2006 "Electromagnetic Compatibility Testing and Measurement Techniques - Radio Frequency Electromagnetic Field Radiation Immunity Test," while ensuring that the molded appearance and mechanical strength of the SMC material are not significantly affected. Therefore, it is necessary to develop an electromagnetically shielded molding compound to replace metal materials, possessing electromagnetic shielding effects and resistance to electromagnetic interference to meet the requirements of GB / T 17626.3-2006 "Electromagnetic Compatibility Testing and Measurement Techniques - Radio Frequency Electromagnetic Field Radiation Immunity Test," while ensuring that the molded appearance and mechanical strength of the material are not significantly affected. Summary of the Invention

[0005] Technical problem to be solved: To address the above-mentioned technical problems, the purpose of this invention is to provide an electromagnetic shielding polyester molding compound and its preparation method. By adding porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles to unsaturated polyester resin, the porous aluminum foam filaments can form a large-frame conductive network in the polyester film, while the micro-three-dimensional structure of the three-dimensional titanium dioxide nanowire particles can form a micro-conductive network, thereby improving the large-frame conductive network. The combination of the two forms a complete conductive network, achieving excellent electromagnetic shielding effect.

[0006] Technical solution: An electromagnetic shielding polyester molding compound, wherein the polyester film is filled with porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles, and the porous aluminum foam filaments are doped with graphene nanorolls.

[0007] Preferably, the porous aluminum foam filaments have a diameter of 0.5-1 μm and a length of 10-20 μm.

[0008] Preferably, the particle size of the three-dimensional titanium dioxide nanowire particles is 0.01-0.5 μm.

[0009] Preferably, the porous aluminum foam filament is prepared as follows:

[0010] (1) Add graphene nanorolls to the molten aluminum in 3-5 portions and disperse them evenly;

[0011] (2) Nitrogen gas was blown into the bottom of the aluminum melt by direct blowing foaming method. After forming a large number of pores in the molten metal, it was cooled and solidified to obtain porous aluminum foam doped with graphene nanorolls.

[0012] (3) Precision cutting into long filaments, i.e., porous aluminum foam filaments.

[0013] Preferably, the mass ratio of the molten aluminum to the graphene nanorolls is 100:(8-13).

[0014] Preferably, the direct blowing foaming method is performed under the following conditions: foaming temperature of 680-700℃ and gas flow rate of 0.05-0.1 L / min. Preferably, the preparation method of the three-dimensional titanium dioxide nanowire particles is as follows:

[0015] (1) Titanium dioxide nanowires were mixed with polyvinylpyrrolidone aqueous solution and subjected to ultrasonic treatment with an ultrasonic power of 300W to obtain a uniform titanium dioxide nanowire suspension.

[0016] (2) The titanium dioxide nanowire suspension was poured into a vacuum filter bottle for vacuum filtration to obtain a titanium dioxide nanowire network preform with a volume fraction of 20%.

[0017] (3) Place it in a furnace and react at 1100℃ for 2-3 hours;

[0018] (4) After cooling, remove the particles and break them into particles to obtain three-dimensional titanium dioxide nanowire particles.

[0019] Preferably, the mass ratio of the titanium dioxide nanowires to polyvinylpyrrolidone is 6:1.

[0020] The preparation method of the above-mentioned electromagnetic shielding polyester molding compound includes the following steps:

[0021] Step 1: Mix and disperse 50-60 parts of unsaturated polyester resin and 40-50 parts of low-shrinkage additive to obtain a mixture;

[0022] Step 2: Add 8-12 parts of porous aluminum foam filaments, 3-7 parts of three-dimensional titanium dioxide nanowire particles and 4-5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0023] Step 3: Add 1.0-1.5 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0024] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0025] Preferably, the unsaturated polyester resin is any one or more of phthalic unsaturated polyester resin, isophthalic unsaturated polyester resin, and terephthalic unsaturated polyester resin; the low-shrinkage additive is a mixture obtained by dissolving polystyrene and styrene monomer solution, wherein the content of polystyrene in the low-shrinkage additive is 45-55 wt%, and the content of styrene monomer solution is 45-55 wt%.

[0026] Beneficial effects:

[0027] 1. This invention adds porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles to unsaturated polyester resin. The porous aluminum foam filaments can form a large-frame conductive network in the polyester film, while the micro-three-dimensional structure of the three-dimensional titanium dioxide nanowire particles can form a micro-conductive network, thereby improving the large-frame conductive network. The combination of the two forms a complete conductive network, achieving excellent electromagnetic shielding effect.

[0028] 2. The porous aluminum foam filaments in this invention have numerous closed pores, enabling multiple reflections and attenuation of electromagnetic waves. The doping with graphene nanorolls is beneficial because ordinary graphene particles have numerous polar groups on their surface, and due to their small particle size, large surface area, and high surface energy, they are prone to aggregation and difficult to disperse. Graphene nanorolls, however, are easily dispersed due to their unique structure and possess excellent conductivity, further improving the overall electromagnetic shielding performance of the material. Simultaneously, the graphene nanorolls increase the viscosity of the molten aluminum during foaming and form a surfactant layer at the gas-aluminum interface, ensuring that the gas remains stably in the molten aluminum, preventing foam collapse during solidification and stabilizing the pore structure of the aluminum foam.

[0029] 3. Another purpose of doping the porous aluminum foam filaments with graphene nanorolls in this invention is that graphene nanorolls can also toughen the aluminum foam, reduce the processing difficulty of the porous aluminum foam filaments, and at the same time improve the mechanical properties of the polyester material.

[0030] 4. The three-dimensional titanium dioxide nanowire particles in this invention have a miniature three-dimensional conductive network. Compared with directly adding titanium dioxide nanowires, this invention solves the technical problem that titanium dioxide nanowires are prone to agglomeration and have a two-dimensional structure, making it impossible to form a better conductive network structure.

[0031] 5. The porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles in this invention can also enhance the mechanical properties of polyester molding compound. The impact strength and flexural strength of the preferred embodiment 12 can reach 91.8 kJ / m. 2 And 132.1 MPa. Detailed Implementation

[0032] This invention proposes an electromagnetic shielding polyester molding compound and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following will provide a more detailed description of the invention with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0033] Example 1

[0034] Step (1) uses different mass ratios of molten aluminum and graphene nanorolls, as follows:

[0035] The preparation method of porous aluminum foam filaments is as follows:

[0036] (1) Graphene nanorolls were added to the molten aluminum in four batches, with the mass ratio of molten aluminum to graphene nanorolls being 100:8, 100:10, and 100:13, and then evenly dispersed.

[0037] (2) Nitrogen gas was blown into the bottom of the aluminum melt using the direct blowing foaming method. After forming a large number of pores in the molten metal, the melt was cooled and solidified to obtain porous aluminum foam doped with graphene nanorolls. The conditions for the direct blowing foaming method were: foaming temperature of 690℃ and gas flow rate of 0.08L / min.

[0038] (3) Precision cutting into long filaments, i.e., porous aluminum foam filaments.

[0039] Porous aluminum foam filaments No. 1, No. 2 and No. 3 were obtained, with diameters of 0.5-1μm and lengths of 10-20μm.

[0040] Example 2

[0041] Step (2) uses different gas flow rates, as follows:

[0042] The preparation method of porous aluminum foam filaments is as follows:

[0043] (1) Graphene nanorolls were added to the molten aluminum in four batches, with a mass ratio of 100:10 between the molten aluminum and the graphene nanorolls, and the nanorolls were evenly dispersed.

[0044] (2) Nitrogen gas is blown into the bottom of the aluminum melt using the direct blowing foaming method. After forming a large number of pores in the molten metal, it is cooled and solidified to obtain porous aluminum foam doped with graphene nanorolls. The conditions for the direct blowing foaming method are: foaming temperature of 690℃ and gas flow rate of 0.05L / min and 0.1L / min.

[0045] (3) Precision cutting into long filaments, i.e., porous aluminum foam filaments.

[0046] Porous aluminum foam filaments No. 4 and No. 5 were obtained, with diameters of 0.5-1μm and lengths of 10-20μm.

[0047] Example 3

[0048] Step (1) uses different foaming temperatures, as follows:

[0049] The preparation method of porous aluminum foam filaments is as follows:

[0050] (1) Graphene nanorolls were added to the molten aluminum in four batches, with a mass ratio of 100:10 between the molten aluminum and the graphene nanorolls, and the nanorolls were evenly dispersed.

[0051] (2) Nitrogen gas is blown into the bottom of the aluminum melt using the direct blowing foaming method. After forming a large number of pores in the molten metal, it is cooled and solidified to obtain porous aluminum foam doped with graphene nanorolls. The conditions for the direct blowing foaming method are: foaming temperature of 680℃ and 700℃, and gas flow rate of 0.08L / min.

[0052] (3) Precision cutting into long filaments, i.e., porous aluminum foam filaments.

[0053] Porous aluminum foam filaments No. 6 and No. 7 were obtained, with diameters of 0.5-1μm and lengths of 10-20μm.

[0054] The pore size and porosity of the prepared porous aluminum foam filaments were measured, and the results are shown in the table below:

[0055]

[0056] After testing and comparison, porous aluminum foam filament No. 6 showed the best electromagnetic shielding effect. Therefore, porous aluminum foam filament No. 6 was selected for subsequent tests.

[0057] Example 4

[0058] The preparation method of three-dimensional titanium dioxide nanowire particles is as follows:

[0059] (1) Titanium dioxide nanowires were mixed with polyvinylpyrrolidone aqueous solution at a mass ratio of 6:1 and subjected to ultrasonic treatment at a power of 300W to obtain a uniform titanium dioxide nanowire suspension.

[0060] (2) The titanium dioxide nanowire suspension was poured into a vacuum filter bottle for vacuum filtration to obtain a titanium dioxide nanowire network preform with a volume fraction of 20%.

[0061] (3) Place it in a furnace and react at 1100℃ for 2.5h;

[0062] (4) After cooling, remove the particles and break them into particles to obtain three-dimensional titanium dioxide nanowire particles.

[0063] Example 5

[0064] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0065] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0066] Step 2: Add 8 parts of porous aluminum foam filament No. 6, 3 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0067] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0068] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0069] Example 6

[0070] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0071] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0072] Step 2: Add 8 parts of porous aluminum foam filament No. 6, 5 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0073] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0074] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0075] Example 7

[0076] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0077] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0078] Step 2: Add 8 parts of porous aluminum foam filament No. 6, 7 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0079] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0080] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0081] Example 8

[0082] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0083] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0084] Step 2: Add 10 parts of porous aluminum foam filament No. 6, 3 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0085] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0086] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0087] Example 9

[0088] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0089] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0090] Step 2: Add 10 parts of porous aluminum foam filament No. 6, 5 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0091] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0092] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0093] Example 10

[0094] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0095] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0096] Step 2: Add 10 parts of porous aluminum foam filament No. 6, 7 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0097] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0098] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0099] Example 11

[0100] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0101] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0102] Step 2: Add 12 parts of porous aluminum foam filament No. 6, 3 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0103] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0104] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0105] Example 12

[0106] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0107] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0108] Step 2: Add 12 parts of porous aluminum foam filament No. 6, 5 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0109] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0110] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0111] Example 13

[0112] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0113] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0114] Step 2: Add 12 parts of porous aluminum foam filament No. 6, 7 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0115] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0116] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0117] Example 14

[0118] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0119] Step 1: Mix and disperse 50 parts of isophthalic unsaturated polyester resin and 40 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 45 wt%, and the content of monomeric styrene solution is 55 wt%.

[0120] Step 2: Add 12 parts of porous aluminum foam filament No. 6, 5 parts of three-dimensional titanium dioxide nanowire particles and 4 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0121] Step 3: Add 1.0 part of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0122] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0123] Example 15

[0124] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0125] Step 1: Mix and disperse 60 parts of terephthalic unsaturated polyester resin and 50 parts of low-shrinkage additive to obtain a mixture. The low-shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low-shrinkage additive is 55 wt%, and the content of monomeric styrene solution is 45 wt%.

[0126] Step 2: Add 12 parts of porous aluminum foam filament No. 6, 5 parts of three-dimensional titanium dioxide nanowire particles and 5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0127] Step 3: Add 1.5 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0128] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0129] Comparative Example 1

[0130] The difference between this embodiment and Embodiment 12 is that it does not contain porous aluminum foam filament No. 6, but instead uses three-dimensional titanium dioxide nanowire particles, specifically:

[0131] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0132] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0133] Step 2: Add 17 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion; Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0134] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0135] Comparative Example 2

[0136] The difference between this embodiment and Embodiment 12 is that it does not contain three-dimensional titanium dioxide nanowire particles, but instead uses porous aluminum foam filament No. 6, specifically:

[0137] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0138] Step 1: Mix and disperse 55 parts of phthalic unsaturated polyester resin and 45 parts of low shrinkage additive to obtain a mixture. The low shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low shrinkage additive is 50 wt%, and the content of monomeric styrene solution is 50 wt%.

[0139] Step 2: Add 17 parts of porous aluminum foam filament No. 6 and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0140] Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0141] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0142] Comparative Example 3

[0143] The difference between this embodiment and Embodiment 12 is that the porous aluminum foam filaments used are not doped with graphene nanofibers, specifically:

[0144] A method for preparing electromagnetic shielding polyester molding compound includes the following steps:

[0145] Step 1: Mix and disperse 60 parts of terephthalic unsaturated polyester resin and 50 parts of low-shrinkage additive to obtain a mixture. The low-shrinkage additive is a mixture obtained by dissolving polystyrene and monomeric styrene solution. The content of polystyrene in the low-shrinkage additive is 55 wt%, and the content of monomeric styrene solution is 45 wt%.

[0146] Step 2: Add 12 parts of porous aluminum foam filaments, 5 parts of three-dimensional titanium dioxide nanowire particles and 5 parts of calcium stearate powder, disperse evenly to obtain a dispersion;

[0147] Step 3: Add 1.5 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste;

[0148] Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

[0149] The preparation method of porous aluminum foam filaments is as follows:

[0150] (1) Nitrogen gas is blown into the bottom of the aluminum melt using the direct blowing foaming method. After forming a large number of pores in the molten metal, it is cooled and solidified to obtain porous aluminum foam. The conditions for the direct blowing foaming method are: foaming temperature is 680℃ and gas flow rate is 0.08L / min; (3) It is precisely cut into long filaments to obtain porous aluminum foam filaments.

[0151] The obtained porous aluminum foam filaments have a diameter of 0.5-1 μm and a length of 10-20 μm.

[0152] The electromagnetic shielding performance of the polyester molding compounds in each embodiment and comparative example was tested in accordance with the test requirements of Chapter 8 of GB / T 17626.3-2006 "Electromagnetic Compatibility Testing and Measurement Techniques - Radio Frequency Electromagnetic Field Radiation Immunity Test".

[0153] The impact resistance strength was tested according to GB / T 1043.1-2008 "Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact test".

[0154] The tensile strength was tested according to the GB / T 9341-2008 standard "Determination of Flexural Properties of Plastics".

[0155] Table 1 Mechanical properties and electromagnetic shielding effect of electromagnetic shielding polyester molding compound

[0156]

[0157] As shown in Table 1, the electromagnetic shielding effect of the electromagnetic shielding polyester molding compound of the present invention is good. The electromagnetic shielding effect increases with the increase of the content of porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles. In terms of mechanical properties, the impact strength increases with the increase of porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles. However, with the further increase of porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles, i.e., after obtaining the content in Example 13, the impact strength begins to decrease. On the other hand, the increase of porous aluminum foam filaments is beneficial to the increase of bending strength, but the increase of three-dimensional titanium dioxide nanowire particles will decrease the bending performance. Therefore, considering all factors, Example 12 is considered to be the best embodiment.

Claims

1. An electromagnetic shielding polyester molding compound, characterized by, The polyester mold is filled with porous aluminum foam filaments and three-dimensional titanium dioxide nanowire particles, and the porous aluminum foam filaments are doped with graphene nanorolls. The method for preparing the porous aluminum foam filament is as follows: (1) Add graphene nanorolls to the molten aluminum in 3-5 portions and disperse them evenly; (2) Nitrogen gas was blown into the bottom of the aluminum melt by direct blowing foaming method. After forming a large number of pores in the molten metal, it was cooled and solidified to obtain porous aluminum foam doped with graphene nanorolls. (3) Precision cutting into long filaments, i.e., porous aluminum foam filaments; The preparation method of the three-dimensional titanium dioxide nanowire particles is as follows: (1) Titanium dioxide nanowires were mixed with polyvinylpyrrolidone aqueous solution and subjected to ultrasonic treatment with an ultrasonic power of 300W to obtain a uniform titanium dioxide nanowire suspension. (2) The titanium dioxide nanowire suspension was poured into a vacuum filter bottle for vacuum filtration to obtain a titanium dioxide nanowire network preform with a volume fraction of 20%. (3) Place it in a furnace and react at 1100℃ for 2-3 hours; (4) After cooling, remove the particles and break them into granules to obtain three-dimensional titanium dioxide nanowire particles. The preparation method, by weight, includes the following steps: Step 1: Mix and disperse 55 parts of unsaturated polyester resin and 45 parts of low-shrinkage additive to obtain a mixture; Step 2: Add 12 parts of porous aluminum foam filaments, 5 parts of three-dimensional titanium dioxide nanowire particles and 4.5 parts of calcium stearate powder, disperse evenly to obtain a dispersion; Step 3: Add 1.3 parts of tert-butyl peroxide to the dispersion and mix to obtain a resin paste; Step 4: After the resin paste is cured, electromagnetic shielding polyester molding compound is obtained.

2. The electromagnetic shielding polyester molding compound as claimed in claim 1, wherein, The porous aluminum foam filaments have a diameter of 0.5-1 μm and a length of 10-20 μm.

3. The electromagnetic shielding polyester molding compound according to claim 1, characterized in that, The particle size of the three-dimensional titanium dioxide nanowire particles is 0.01-0.5 μm.

4. The electromagnetic shielding polyester molding compound as claimed in claim 1, wherein, The mass ratio of the molten aluminum to the graphene nanorolls is 100:(8-13).

5. The electromagnetic shielding polyester molding compound as claimed in claim 1, wherein, The conditions for the direct blowing foaming method are: foaming temperature of 680-700℃ and gas flow rate of 0.05-0.1 L / min.

6. The electromagnetic shielding polyester molding compound as claimed in claim 1, wherein, The mass ratio of the titanium dioxide nanowires to polyvinylpyrrolidone is 6:

1.

7. The electromagnetic shielding polyester molding compound as claimed in claim 1, wherein, The unsaturated polyester resin is any one or more of orthophthalic unsaturated polyester resin, isophthalic unsaturated polyester resin, and terephthalic unsaturated polyester resin; the low-shrinkage additive is a mixture obtained by dissolving polystyrene and styrene monomer solution, wherein the content of polystyrene in the low-shrinkage additive is 45-55 wt%, and the content of styrene monomer solution is 45-55 wt%.

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