Preparation method of wave-absorbing and flame-retardant bimetallic heterojunction nano composite material

Abstract

The invention discloses a preparation method of a wave-absorbing and flame-retardant bimetallic heterojunction nano composite material, which comprises the following steps: grinding and mixing two kinds of metal powder and metal sulfide, then transferring into a quartz tube for vacuum sealing, calcining to obtain a bimetallic heterostructure material, and carrying out microwave heating on the bimetallic heterostructure material in an inert gas atmosphere to obtain the wave-absorbing and flame-retardant bimetallic heterojunction nano composite material. The preparation method comprises the following steps: carrying out ball milling on a bimetal heterojunction nano composite material and a two-dimensional conductive material to obtain a bimetal heterojunction nano composite material, banburying the bimetal heterojunction nano composite material and resin, and carrying out hot press molding to obtain the wave-absorbing and flame-retardant bimetal heterojunction nano composite material. The microwave absorbing agent with bimetallic sulfide heterojunction such as Fe-Ni, Fe-Mn, Co-Ni and the like as a core and black phosphorus-graphite as a synergistic shell layer, and the composite material with broadband wave absorbing and intrinsic flame-retardant characteristics are obtained by melting and blending the microwave absorbing agent with resin such as TPU, PLA and EVA.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanofunctional materials and polymer composites, in particular to a nanocomposite with Fe-Ni, Fe-Mn, Co-Ni, etc. double-metal sulfide heterojunction as the core and black phosphorus-graphite as the synergistic shell, which is melt blended with TPU, PLA and EVA resins to obtain a composite material with wideband wave absorption and intrinsic flame retardant properties. BACKGROUND

[0002] With the explosive growth of 5th generation (5G) / 6th generation (6G) wireless communication, millimeter wave radar, Internet of Vehicles and Internet of Things devices, the working frequency band has been fully covered from 0.1-110 GHz. Highly integrated, high frequency and high speed electronic systems not only transmit massive data, but also cause serious electromagnetic pollution and thermal runaway risks: on the one hand, the leaked microwave energy not only interferes with adjacent precision equipment, but also may endanger human health; on the other hand, high power density makes polymer housings, radomes, connecting cables, etc. extremely easy to ignite due to local overheating. Traditional solutions usually handle “wave absorption” and “flame retardation” separately: the wave absorption layer mostly uses ferrite, single magnetic metal or carbon-based filler, which has high areal density, narrow effective bandwidth, and easily sacrifices the insulation of the matrix due to the over-dense conductive network; the flame retardant layer relies on halogen-containing, phosphorus-containing or intumescent additives, which often leads to molten droplets, smoke toxicity and mechanical property degradation.

[0003] Therefore, it is urgent to develop an integrated microwave absorber that can simultaneously achieve “wideband strong absorption, low reflection” and “intrinsic flame retardation, low smoke and non-toxicity” and is easy to melt process with thermoplastic resins (TPU, PLA, PBAT and EVA, etc.), which has become a bottleneck to be broken through in the fields of material science and microwave engineering.

[0004] In recent years, double-metal sulfide heterojunction (M 1x M 2ySn / Sb / S) has been proved to produce multiple relaxation behaviors in the frequency range of 2-18 GHz due to the Schottky barrier and space charge polarization of the metal-semiconductor interface, thus significantly enhancing the dielectric loss. Meanwhile, the lattice distortion and defects at the heterojunction interface can act as magnetic domain pinning centers, inducing natural resonance and eddy current loss, and achieving dielectric-magnetic synergistic attenuation. However, single heterojunction still has problems such as impedance mismatch, low thermal conductivity, and easy oxidation and agglomeration, which is difficult to be directly used in polymer matrix. Black phosphorus (BP) has a layered wrinkled structure and a tunable band gap (0.3-2.0 eV), which can occur polarization relaxation under microwave field and release PO· / P· free radicals to capture ·H / ·OH, and has excellent gas phase flame retardant performance; graphite (Gr) provides a high conductive-thermal network to promote rapid heat dissipation and avoid local hot spots. The BP-Gr is cooperatively coated on the surface of the double-metal sulfide heterojunction, which not only can build a three-dimensional conductive-dielectric-magnetic multiple loss network, but also can form a covalent / van der Waals double interface with TPU, PLA and EVA, etc. polar segment through interface coupling agent, significantly improving the dispersion and mechanical compatibility of the filler.

[0005] At present, there is still a lack of a simple process, scalable and environmentally friendly "one-step solid-phase sulfuration-co-ball-milling-coating-melt compounding" overall technical route to realize the synergistic improvement of double-metal sulfide heterojunction / BP-Gr nano composite microwave absorber in wave absorption, flame retardation and mechanics. SUMMARY

[0006] In view of the above problems, the present application provides a preparation method of a double-metal heterojunction nano composite material, which obtains a wave-absorbing and flame-retardant double-metal heterojunction nano composite material.

[0007] The technical scheme of the present application is as follows: A preparation method of a wave-absorbing and flame-retardant double-metal heterojunction nano composite material, the specific steps are as follows: (1) The two kinds of metal powders and metal sulfides are mixed and ground, then moved into a quartz tube for vacuum sealing, and placed in a muffle furnace for calcination to obtain a double-metal heterostructure material; (2) The double-metal heterostructure material is loaded into a ball mill tank in a glove box under an inert gas atmosphere, and ball milled with a two-dimensional conductive material to obtain a double-metal heterojunction nano composite material; (3) The double-metal heterojunction nano composite material is melt compounded with resin in a mixer, and then hot pressed to obtain a double-metal heterojunction nano composite material.

[0008] The metal powder in step (1) is iron, cobalt, nickel, manganese powder, etc.

[0009] The metal sulfide in step (1) is one of tin sulfide, antimony sulfide, tin disulfide, nickel sulfide, and bismuth sulfide.

[0010] The molar ratio of the two metal powders and the metal sulfide in step (1) is 1:1:1-10:10:3.

[0011] The calcination temperature in the muffle furnace in step (1) is 600-800 DEG C, the calcination time is 3-10 h, and the entire calcination process is kept in a vacuum state.

[0012] The two-dimensional conductive material in step (2) is a mixture of black phosphorus and graphite, wherein the mass of black phosphorus and graphite accounts for 15-50% of the mass of the double-metal heterostructure material.

[0013] The ball milling time in step (2) is 4-20 h, and the ball milling rotation speed is 400-800 rpm.

[0014] The resin in step (3) is one of TPU, PLA, PBAT and EVA or a blend thereof.

[0015] The mass of the double-metal heterojunction nanocomposite in step (3) accounts for 5%-20% of the mass of the resin.

[0016] The banburying temperature in step (3) is 160-200 DEG C, the banburying machine rotation speed is 50-80 rpm, and the banburying melt blending time is 10-30 min.

[0017] The application realizes the triple synergy of "microwave strong absorption + intrinsic flame retardation + mechanical retention" in a single filler system through the interface polarization, defect polarization and magnetic-dielectric synergistic loss of the multi-metal sulfide heterostructure, the gas phase flame retardation of black phosphorus and the heat-conducting-conducting network of graphite. The process flow is short, solvent-free, suitable for roll-to-roll extrusion or injection molding, and provides an integrated solution for 5G / 6G base stations, automobile radar covers, wearable electromagnetic shielding, etc. DETAILED DESCRIPTION

[0018] The application will be further described in detail below in combination with specific embodiments.

[0019] Example 1 The raw materials were Fe powder 0.458 g, Ni powder 0.802 g and SnS powder 1 g (molar ratio Fe:Ni:SnS=3:5:2), which were mixed by grinding in a mortar and then moved to a quartz tube for vacuum sealing. The quartz tube was then placed in a muffle furnace and calcined at 600 DEG C for 10 h, obtaining a double-metal FeSn-Ni3Sn2 / FeS-Ni3S2 heterostructure material. The entire calcination process was in a vacuum sealed state. 2g of the bimetallic FeSn-Ni3Sn2 / FeS-Ni3S2 heterostructure material was placed in a ball mill tank, 0.3g of black phosphorus and 0.3g of graphite were added, and ball milling was carried out under an argon atmosphere for 20h at a ball milling speed of 400rpm to obtain the FeSn-Ni3Sn2 / FeS-Ni3S2@BP-Gr bimetallic heterojunction nanocomposite material; 2g of the bimetallic heterojunction nanocomposite material was melt mixed with 20g of TPU (melt mixing temperature of the internal mixer was 185℃, rotation speed was 60rpm, and melt mixing was carried out for 15min), and hot pressing was carried out after melt mixing, the hot press pressure was 10MPa, the hot press temperature was 160℃, and the tablet thickness was 2.0mm to obtain the wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite material.

[0020] The electromagnetic parameters of the sample of the present embodiment were measured using the coaxial method and an Agilent E5071C vector network analyzer, and it was found that at 11.8GHz, RL min =–51.3dB, and the effective bandwidth was 4.03GHz; the limiting oxygen index of the sample was measured by a limiting oxygen index tester to be LOI 33%, and the UL-94 rating was measured by vertical burning to be UL-94 V-0.

[0021] Example 2 Fe powder 0.657g, Mn powder 0.485g, and Sb2S3 powder 2g (molar ratio Fe:Mn:Sb2S3=4:3:2) were placed in a mortar and ground to mix, and then transferred to a quartz tube for vacuum sealing. The quartz tube was then placed in a muffle furnace and calcined at a temperature of 800℃ for 3h to obtain the bimetallic FeSb2-MnSb / FeS-MnS heterostructure material, and the entire calcination process was carried out in a vacuum sealed state; 2g of the bimetallic FeSb2-MnSb / FeS-MnS heterostructure material was placed in a ball mill tank, 0.5g of black phosphorus and 0.5g of graphite were added, and ball milling was carried out under an argon atmosphere for 4h at a ball milling speed of 800rpm to obtain the FeSb2-MnSb / FeS-MnS@BP-Gr bimetallic heterojunction nanocomposite material; 1g of the bimetallic heterojunction nanocomposite material was melt mixed with 20g of TPU (melt mixing temperature of the internal mixer was 185℃, rotation speed was 60rpm, and melt mixing was carried out for 20min), and hot pressing was carried out after melt mixing, the hot press pressure was 10MPa, the hot press temperature was 160℃, and the tablet thickness was 2.0mm to obtain the wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite material.

[0022] The electromagnetic parameters of the sample of the present embodiment were measured using the coaxial method and an Agilent E5071C vector network analyzer, and it was found that at 9.4GHz RL min= -48.7 dB, effective bandwidth 3.8 GHz; the limiting oxygen index of the sample is LOI 34% measured by a limiting oxygen index tester.

[0023] Example 3 The raw materials were Co powder 0.806 g, Ni powder 0.802 g, and SnS2 powder 1 g (molar ratio Co:Ni:SnS2 = 5:5:2). After grinding and mixing the three raw materials in a mortar, they were moved to a quartz tube for vacuum sealing. Then the quartz tube was placed in a muffle furnace to calcine at 700°C for 6 h. A bimetallic CoSn-Ni3Sn2 / Ni3S2-Co9S8 heterostructure material was obtained. The entire calcination process was in a vacuum sealed state. 2 g of the bimetallic CoSn-Ni3Sn2 / Ni3S2-Co9S8 heterostructure material was placed in a ball mill jar, 1 g of black phosphorus and 1 g of graphite were added, and ball milling was carried out under argon atmosphere for 10 h at a rotation speed of 600 rpm. A CoSn-Ni3Sn2 / Ni3S2-Co9S8@BP-Gr bimetallic heterojunction nanocomposite material was obtained. 4 g of the bimetallic heterojunction nanocomposite material was mixed with 20 g of PBS in a mixer (mixing temperature of the mixer was 200°C, rotation speed was 50 rpm, and melt blending was carried out for 30 min). After mixing, hot pressing was carried out at a pressure of 10 MPa and a temperature of 165°C, and a tablet with a thickness of 2.0 mm was obtained. A wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite material was obtained.

[0024] The electromagnetic parameters of the sample of the present embodiment were measured using a coaxial method and an Agilent E5071C vector network analyzer. The results are as follows: at 12.1 GHz RL min = -46.5 dB, effective bandwidth 3.4 GHz; the limiting oxygen index of the sample is LOI 32% measured by a limiting oxygen index tester.

[0025] Example 4 The raw materials were Fe powder 0.66 g, Ni powder 0.35 g, and Sb2S3 powder 2 g (molar ratio Fe:Ni:Sb2S3 = 2:1:1). After grinding and mixing the three raw materials in a mortar, they were moved to a quartz tube for vacuum sealing. Then the quartz tube was placed in a muffle furnace to calcine at 600°C for 6 h. A bimetallic FeSb2S4-NiSb / FeS-Ni3S2 heterostructure material was obtained. The entire calcination process was in a vacuum sealed state. 2 g of the bimetallic FeSb2S4-NiSb / FeS-Ni3S2 heterostructure material was placed in a ball mill jar, 0.5 g of black phosphorus and 0.5 g of graphite were added, and ball milling was carried out under argon atmosphere for 8 h at a rotation speed of 700 rpm. A FeSb2S4-NiSb / FeS-Ni3S2@BP-Gr bimetallic heterojunction nanocomposite material was obtained. Take 2 g of bimetallic heterojunction nanocomposite and 20 g of TPU to mix (the mixing temperature of the mixer is 185℃, the rotation speed is 60 rpm, and the mixing melt blending time is 15 min), and then hot press after mixing. The hot press machine pressure is 10 MPa, the hot press temperature is 160℃, and the tablet thickness is 2.0 mm. The wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite is obtained.

[0026] The electromagnetic parameters of the sample in this embodiment are measured by using the coaxial method and Agilent E5071C vector network analyzer. It is obtained that at 8.6 GHz RL min =–51.7dB, the effective bandwidth is 4.03GHz; the limiting oxygen index of the sample is LOI 31% measured by the limiting oxygen index tester.

[0027] Example 5 The raw materials are Fe powder 0.822g, Ni powder 0.518g, and Sb2S3 powder 2g (molar ratio Fe:Ni:Sb2S3=5:3:2). After grinding and mixing the three raw materials in a mortar, they are moved to a quartz tube for vacuum sealing. Then the quartz tube is placed in a muffle furnace to calcine at 700℃ for 8h. The bimetallic FeSb2-NiSb / FeS-Ni3S2 heterostructure material is obtained. The whole calcination process is in a vacuum sealed state. Put 2g of bimetallic FeSb2-NiSb / FeS-Ni3S2 heterostructure material into a ball mill jar, add 0.5g of black phosphorus and 0.5g of graphite, and ball mill under argon atmosphere for 12h at a rotation speed of 600rpm. The FeSb2-NiSb / FeS-Ni3S2@BP-Gr bimetallic heterojunction nanocomposite is obtained. Take 3g of bimetallic heterojunction nanocomposite and 20g of TPU to mix (the mixing temperature of the mixer is 185℃, the rotation speed is 60 rpm, and the mixing melt blending time is 25 min), and then hot press after mixing. The hot press machine pressure is 10 MPa, the hot press temperature is 165℃, and the tablet thickness is 2.0 mm. The wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite is obtained.

[0028] The electromagnetic parameters of the sample in this embodiment are measured by using the coaxial method and Agilent E5071C vector network analyzer. It is obtained that at 11.2 GHz RL min =–48.3dB, the effective bandwidth is 3.73GHz; the limiting oxygen index of the sample is LOI 33% measured by the limiting oxygen index tester.

[0029] Example 6 The raw materials are Fe powder 0.493 g, Co powder 0.520 g, and Sb2S3 powder 2 g (molar ratio Fe:Co:Sb2S3=3:3:2), the three raw materials are put into a mortar and ground and mixed, then moved to a quartz tube for vacuum sealing, and then the quartz tube is placed in a muffle furnace to keep the temperature at 600 ℃ for calcination for 10 h, to obtain a bimetallic Sb-CoSb / FeS-Co4S3 heterostructure material, and the whole calcination process is in a vacuum sealed state; 2 g of the bimetallic Sb-CoSb / FeS-Co4S3 heterostructure material is put into a ball mill tank, 0.5 g of black phosphorus and 0.5 g of graphite are added, and ball milling is carried out under an argon atmosphere for 10 h at a ball milling speed of 500 rpm, to obtain a Sb-CoSb / FeS-Co4S3@BP-Gr bimetallic heterojunction nanocomposite material; 2 g of the bimetallic heterojunction nanocomposite material is mixed with 20 g of PBAT by internal mixing (the internal mixing temperature of the internal mixer is 160 ℃, the rotating speed is 80 rpm, and the internal mixing melt blending is carried out for 10 min), and then hot pressing is carried out, the hot press pressure is 10 MPa, the hot press temperature is 155 ℃, and the tablet thickness is 2.0 mm, to obtain a wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite material.

[0030] The electromagnetic parameters of the sample of the embodiment are measured by using a coaxial method and an Agilent E5071C vector network analyzer, and the results are as follows: at 13.5 GHz RL min =–44.6 dB, and the effective bandwidth is 4.7 GHz; the limiting oxygen index of the sample is measured by a limiting oxygen index tester to be LOI 30%.

[0031] Example 7 The raw materials are Ni powder 0.779 g, Mn powder 0.543 g, and SnS powder 1 g (molar ratio Ni:Mn:SnS=4:3:2), the three raw materials are put into a mortar and ground and mixed, then moved to a quartz tube for vacuum sealing, and then the quartz tube is placed in a muffle furnace to keep the temperature at 600 ℃ for calcination for 8 h, to obtain a bimetallic Ni3Sn2-MnSn2 / Ni3S2-MnS heterostructure material, and the whole calcination process is in a vacuum sealed state; 2 g of the bimetallic Ni3Sn2-MnSn2 / Ni3S2-MnS heterostructure material is put into a ball mill tank, 0.6 g of black phosphorus and 0.6 g of graphite are added, and ball milling is carried out under an argon atmosphere for 10 h at a ball milling speed of 600 rpm, to obtain a Ni3Sn2-MnSn2 / Ni3S2-MnS@BP-Gr bimetallic heterojunction nanocomposite material; Take 2g bimetallic heterojunction nanocomposite and 20g TPU mixing (the mixing temperature of the mixer is 185℃, the rotating speed is 60rpm, and the mixing melt blending is 15min), after mixing, hot pressing is carried out, the hot press pressure is 10MPa, the hot press temperature is 165℃, and the tablet thickness is 2.0mm, and the wave absorbing and flame-retardant bimetallic heterojunction nanocomposite is obtained.

[0032] The electromagnetic parameters of the sample of the embodiment are measured by using the coaxial method and Agilent E5071C vector network analyzer, and it is obtained that at 11.5GHz RL min =–50.8dB, and the effective bandwidth is 4.25GHz; the limiting oxygen index of the sample is LOI 33% measured by the limiting oxygen index tester.

[0033] Example 8 The raw materials are Co powder 0.782g, Mn powder 0.543g, and SnS powder 1g (molar ratio Co:Mn:SnS=4:3:2), the three raw materials are ground and mixed in a mortar, then moved to a quartz tube for vacuum sealing, and then the quartz tube is placed in a muffle furnace to keep the temperature at 600℃ for calcination for 10h, and the bimetallic CoSn-MnSn2 / Co9S8-MnS heterostructure material is obtained, and the whole calcination process is in a vacuum sealed state; 2g bimetallic CoSn-MnSn2 / Co9S8-MnS heterostructure material is placed in a ball mill tank, 0.8g black phosphorus and 0.8g graphite are added, and ball milling is carried out under argon atmosphere for 8h, and the ball milling rotating speed is 600rpm, and the CoSn-MnSn2 / Co9S8-MnS@BP-Gr bimetallic heterojunction nanocomposite is obtained; Take 2g bimetallic heterojunction nanocomposite and 20g TPU mixing (the mixing temperature of the mixer is 185℃, the rotating speed is 60rpm, and the mixing melt blending is 20min), after mixing, hot pressing is carried out, the hot press pressure is 10MPa, the hot press temperature is 165℃, and the tablet thickness is 2.0mm, and the wave absorbing and flame-retardant bimetallic heterojunction nanocomposite is obtained.

[0034] The electromagnetic parameters of the sample of the embodiment are measured by using the coaxial method and Agilent E5071C vector network analyzer, and it is obtained that at 10.3GHz RL min =–43.5dB, and the effective bandwidth is 3.87GHz; the limiting oxygen index of the sample is LOI 31% measured by the limiting oxygen index tester.

[0035] The electromagnetic parameters of the sample of the embodiment are measured by using the coaxial method and Agilent E5071C vector network analyzer, and it is obtained that at 11.5GHz RL RL minThe values are all less than -10 dB, indicating that the material has excellent attenuation ability to electromagnetic waves in the corresponding frequency band, has good wave absorption performance, and meets the stringent requirements of modern stealth technology, electromagnetic compatibility and information security and other fields for high-efficiency microwave absorbing materials; at the same time, the limiting oxygen index (LOI) of each embodiment is greater than 30%, meaning that the material is difficult to sustain combustion in air and can meet the strict specifications for flame-retardant safety in aerospace, rail transportation, electronic devices and high-end equipment, indicating that the sample has wave absorption and flame-retardant performance.

[0036] The specific embodiments of the application are described in detail above in combination with specific embodiments, but the application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application.

Claims

1. A method for preparing a wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite, characterized in that, The steps are as follows: (1) two kinds of metal powder and metal sulfide are mixed and ground, then moved into a quartz tube for vacuum sealing, and a bimetallic heterostructure material is obtained after calcination; (2) the bimetallic heterostructure material is ball milled with two-dimensional conductive material in an inert gas atmosphere to obtain a bimetallic heterojunction nanocomposite; (3) the bimetallic heterojunction nanocomposite is mixed with resin and then hot pressed to obtain a wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite.

2. The method for preparing the wave-absorbing and flame-retardant bimetallic heterojunction nanocomposite according to claim 1, characterized in that, The metal powder is iron, cobalt, nickel or manganese powder.

3. The preparation method of the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The metal sulfide in step (1) is one of tin sulfide, antimony sulfide, tin disulfide, nickel sulfide and bismuth sulfide.

4. The preparation method of the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The molar ratio of the two kinds of metal powder and metal sulfide in step (1) is 1:1:1-10:10:

3.

5. The method for preparing the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The calcination temperature in step (1) is 600-800℃, and the calcination time is 3-10h.

6. The method for preparing the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The two-dimensional conductive material in step (2) is a mixture of black phosphorus and graphite; the mass fraction of black phosphorus and graphite in the bimetallic heterostructure material is 15-50%.

7. The method for preparing the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The ball milling time in step (2) is 4-20h, and the ball milling speed is 400-800rpm.

8. The method for preparing the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The resin in step (3) is one of TPU, PLA, PBAT and EVA or a blend thereof.

9. The method for preparing the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The mass fraction of the bimetallic heterojunction nanocomposite in the resin in step (3) is 5%-20%.

10. The method for preparing the microwave-absorbing and flame-retardant bimetallic heterostructure nanocomposite material according to claim 1, characterized in that, The mixing temperature in step (3) is 160-200℃, the rotating speed is 50-80rpm, and the mixing time is 10-30min.