▎ 摘　　要

NOVELTY - Halogen-free flame-retardant high-temperature-resistant heat-conducting polyolefin composite material, comprises 100 pts. wt. polyolefin resin, 80-120 pts. wt. flame retardant, 0.5-50 pts. wt. thermal conductive filler, 0.2-5 pts. wt. antioxidant, 0.2-5 pts. wt. processing aid and 0.2-2 pts. wt. cross-linking agent; where the flame retardant includes inorganic flame retardant and flame retardant synergist with the mass ratio of 1:0.01-0.1; the inorganic flame retardant includes magnesium hydroxide, aluminum hydroxide and/or zinc borate, and the flame retardant synergist includes polysilane, polysiloxane and/or silicone resin; and the thermal conductive filler includes graphene flakes and boron nitride with the mass ratio of 1:0.1-50. USE - The halogen-free flame-retardant high-temperature-resistant heat-conducting polyolefin composite material is useful in manufacturing automotive wires, locomotive cables, power cables, and communication cables (claimed). ADVANTAGE - The material: solves the problem that the existing polyolefin composite material cannot meet the requirements of halogen-free flame retardancy and heat conduction at the same time, which restricts its application. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing halogen-free flame-retardant high-temperature-resistant heat-conducting polyolefin composite material, comprising (1a) mixing 30% aqueous hydrogen peroxide solution and urea to obtain solution A, adding boron nitride into the solution A, and treating under ultrasonic with the power of 200-500 W for 0.5-2 hours, then transferring to reactor, carrying out hydrothermal reaction at 100-130 ℃ for 0.5-5 hours, cooling the reactor to room temperature, filtering the solution, washing the filter cake with deionized water for 3-5 times, and drying in oven at 80-120 ℃ for 2-8 hours to obtain hydroxylated boron nitride, where the mass ratio between hydrogen peroxide and urea is 1:0.2-2, and the mass ratio between boron nitride and hydrogen peroxide is 1:1-10, (1b) mixing absolute ethanol and deionized water with the volume ratio of 1:0.5-5 to obtain solution B, adding the hydroxylated boron nitride into the solution B, and mixing under magnetic stirring for 10-30 minutes, dropwise adding vinyl silane coupling agent with the rate of 1-5 drops/minute under stirring, and maintaining the temperature to 60-80 ℃ for 1-5 hours to obtain vinylsilane-modified boron nitride, where the mass ratio between hydroxylated boron nitride and vinyl silane coupling agent is 1:0.01-0.5, and the mass ratio between hydroxylated boron nitride and solution B is 1:10-200, and (1c) using a high-speed mixer to mix vinylsilane-modified boron nitride and cross-linking agent at 500-1500 revolutions per minute to obtain a mixed filler, using a torque rheometer to blend the mixed filler with polyolefin resin at 120-160 ℃ to obtain resin mixed filler, and treating with an electron beam having radiation energy of 1.5-3.5 MeV and radiation beam current of 5-50 mA to obtain polyolefin grafted boron nitride thermally conductive filler after the radiation absorbed dose per unit mass of sheet reaches 2-6 Mrad, where the mass ratio between vinylsilane-modified boron nitride and the cross-linking agent is 1:0.005-0.05, and the mass ratio between vinylsilane-modified boron nitride and polyolefin resin is 1:0.1-0.4, (2a) mixing graphene flakes and deionized water with the mass ratio of 1:10-100, then adding vinyl silane coupling agent according to the mass ratio between inorganic flame retardant and vinyl silane of 1:0.002-0.05, and ultrasonically treating at 200-500 W for 0.5-2 hours to obtain graphene dispersion, (2b) mixing inorganic flame retardant and deionized water with the mass ratio of 1:1-50 to obtain flame retardant slurry, placing the flame retardant slurry in sand mill, grinding at room temperature for 10-30 minutes with the rotational speed of 500-2000 revolutions per minute, then adding the graphene dispersion to obtain mixed solution, grinding the mixed solution at 500-2000 revolutions per minute for 0.5-5 hours, filtering the solution, and washing the filter cake for 3-5 times with deionized water, and drying in oven at 80-120 ℃ for 2-8 hours to obtain vinylsilane-modified graphene-loaded inorganic flame-retardant heat-conductive filler, and (2c) mixing vinylsilane-modified graphene-loaded inorganic flame-retardant heat-conductive filler, flame-retardant synergist and cross-linking agent with the mass ratio of 1:0.01-0.1:0.001-0.01 at 500-1500 revolutions per minute to obtain mixed filler, then using torque rheometer at 120-160 ℃ according to the mass ratio of vinylsilane-modified graphene-loaded inorganic flame-retardant heat-conductive filler and polyolefin resin of 1:0.1-0.4, and melt mixing the mixed filler and polyolefin resin to obtain resin mixed filler, and treating with electron beam having radiation energy of 1.5-3.5 MeV and radiation beam current of 5-50 mA to obtain polyolefin grafted inorganic flame-retardant heat-conducting filler after the radiation absorption dose per unit mass of the sheet reaches 2-6 Mrad, and (3) using high mixer to mix polyolefin resin, polyolefin grafted boron nitride thermally conductive filler, polyolefin grafted inorganic flame-retardant heat-conducting filler, antioxidant, processing aid and cross-linking agent at 500-1500 revolutions per minute to obtain mixed materials, and melting and blending at 120-180 ℃ by using torque rheometer to obtain composite material, and treating with electron beam having radiation energy of 2.5-5 MeV and radiation beam current of 5-50 mA to obtain final product after the radiation absorption dose per unit mass of the sheet reaches 8-15 Mrad.