▎ 摘　　要

NOVELTY - A foam electromagnetic shielding material with bulletproof function is prepared by dissolving the matrix resin into the dispersion solution, mechanically stirring at 200-300 rpm for 10-30 minutes to obtain mixed solution (A), adding azodiisobutyronitrile and modified wave absorbent into the mixed solution (A), stirring to obtain wave-absorbing resin dispersion liquid (C), introducing high-purity carbon dioxide, adding 4,4-diaminodiphenylmethane, melamine and nano conductive graphite powder into the liquid (C), stirring to obtain electromagnetic shielding mixed liquid, coating modified ethylene-vinyl alcohol resin (EOVH) in one upward surface of each cloth block, superposing the coated aramid fiber laid fabric blocks to obtain bulletproof aramid fiber chips to obtain foam electromagnetic shielding material precursor (D) with bulletproof function, and heating. USE - Foam electromagnetic shielding material with bulletproof function used in stealth airplanes, stealth naval vessels, satellites, communication base stations and electrical equipment. ADVANTAGE - The method solve the problems of large investment of instruments and equipment, high production cost, complex preparation process, uneven foaming and no protective performance in the current preparation process of the electromagnetic shielding material. The method does not need complex production instruments and equipment, has low production cost and simple operation process, and ensures that the density of holes is more uniform. The foaming is more sufficient and the wave absorbent is more uniformly dispersed by the method combining physical foaming and chemical foaming. The wave absorbent is modified, so that the interface performance between the wave absorbent and the resin matrix is excellent. The foam electromagnetic shielding material has improved stability. The composite material prepared by the gradient structure design from outside to inside have electromagnetic shielding performance and bulletproof performance. DETAILED DESCRIPTION - A foam electromagnetic shielding material with bulletproof function is prepared by using matrix resin, azodiisobutyronitrile, wave absorbent powder, 4,4-diaminodiphenylmethane, melamine and nano conductive graphite powder in a mass ratio of 60:2-5:7-10:2-3:1-2, measuring dispersion solution in the mass volume ratio of matrix resin to dispersion solution of 1 g:50-70 ml, dissolving the matrix resin into the dispersion solution, mechanically stirring at 200-300 rpm for 10-30 minutes to obtain mixed solution (A), transferring the mixed solution (A) to environment with temperature of 5-15℃, adding azodiisobutyronitrile and modified wave absorbent into the mixed solution (A), mechanically stirring at 300-500 rpm, ultrasonically dispersing at 500 W and frequency of 50 kHz for 30-50 minutes to obtain wave-absorbing resin dispersion liquid (C), maintaining the temperature environment, introducing high-purity carbon dioxide having purity of 99.99% or more into the liquid (C) with gas flow rate of 30-50 ml/minute, adding 4,4-diaminodiphenylmethane, melamine and nano conductive graphite powder into the liquid (C), mechanically stirring at 500-800 rpm for 90-120 minutes to obtain electromagnetic shielding mixed liquid, cutting aramid fiber laid fabric into cloth blocks with specification of 48 mm x 98 mm, coating modified ethylene-vinyl alcohol resin (EOVH) in one upward surface of each cloth block, superposing the coated aramid fiber laid fabric blocks by 10-20 layers upwards according to the coating surface to obtain bulletproof aramid fiber chips, placing the chips in hot-pressing mold with specification of 50 mm x 100 mm x 30 mm, pouring the electromagnetic shielding mixed liquid into die for containing the bulletproof aramid fiber chips, placing the mold in hot press at 70-90℃ for hot press molding at pressure value of 6-8 MPa for 5-8 hours to obtain foam electromagnetic shielding material precursor (D) with bulletproof function, placing the precursor (D) in a tubular furnace at 300-400℃ for heating for 50-90 minutes. In step (S1), the nano conductive graphite powder has average particle size distribution of 30-70 nm.