Antistatic EVA foam composite material and preparation method thereof

Abstract

The invention belongs to the technical field of polymer foam composite materials, and particularly relates to an antistatic EVA foam composite material and a preparation method thereof. The antistatic EVA foam composite material comprises the following raw materials: an ethylene-vinyl acetate copolymer, low-density polyethylene, a conductive filler, a foaming agent, a foaming aid and a cross-linking agent, wherein the conductive filler is modified graphene oxide. Modified graphene oxide is prepared through ring-opening reaction, esterification reaction and silanization reaction of an epoxy compound in sequence, and siloxane, phosphate and a benzene ring are introduced to the surface of graphene oxide. By adjusting the ratio and controlling the process conditions, the prepared EVA foam composite material not only has proper density and rebound resilience, but also has excellent antistatic property, mechanical property and flame retardant property.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer foam composite materials, and particularly relates to an antistatic EVA foam composite material and a preparation method thereof. Background Art

[0002] Ethylene-vinyl acetate copolymer (EVA) is a type of random copolymer formed by the copolymerization of polar vinyl acetate monomer and non-polar ethylene monomer. Because of the polar and non-polar groups on its main chain, it has good mechanical and processing properties, while not lacking in flexibility and elasticity. Therefore, EVA is often used to prepare foam materials and is widely used in packaging, building materials, sports equipment, footwear and other fields. As a new type of functional material, the conductive composite material prepared by compounding conductive fillers and polymer materials has the advantages of excellent conductive properties, low cost and easy processing. It is widely used in products such as sensors and current protection devices. In the study, it was found that the conductive composite material showed pressure dependence under pressure and exhibited piezoresistive behavior. The conductive foam material is a type of material that has good conductivity and the cushioning, energy absorption, shockproof and other properties of foam materials. It also has good compressibility and a certain degree of resilience, which has become a hot topic for scientists to study.

[0003] Patent application number CN200810023439.0 provides an ethylene-vinyl acetate copolymer open-cell foamed profile and a method for manufacturing the same, comprising the following main raw materials: a mixture of ethylene-vinyl acetate copolymer and low-density polyethylene, a filler, a foaming agent, a cross-linking agent, a foaming aid, a flame retardant, and white oil. The ethylene-vinyl acetate copolymer open-cell foamed profile is prepared through mixing, refining, open refining, preforming, primary foaming, secondary foaming and other process steps. The foaming ratio of the ethylene-vinyl acetate copolymer is 15-30, but the limiting oxygen index of the ethylene-vinyl acetate copolymer can only reach about 18%, and the material is extremely flammable, which greatly limits its application range; Patent application number CN200810155834.4 provides a conductive ethylene-vinyl acetate copolymer foamed profile and a method for manufacturing the same , including the following main raw materials: a mixture of ethylene-vinyl acetate copolymer and low-density polyethylene, a filler, a foaming agent, a foaming aid, a cross-linking agent, a lubricant, and conductive carbon black. Through the process steps of mixing, preforming, compression molding, shaping, cooling, etc., the ethylene-vinyl acetate copolymer foamed profile prepared is light in weight, good in cushioning performance, and low in volume resistivity. It can be reprocessed by slotting, stamping, bonding, etc. to adapt to various uses. Conductive carbon black, as an inorganic filler, plays an important role in organic polymer systems. In the fields of batteries, electronics, etc., it can give products conductive or antistatic effects. However, due to the poor compatibility of conductive carbon black with organic polymer materials, it is difficult to disperse evenly in the matrix. Direct filling can easily lead to disadvantages such as decreased mechanical properties and embrittlement of the material. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide an antistatic EVA foam composite material and a preparation method thereof. The EVA foam composite material provided by the present invention not only has suitable density and resilience, but also has excellent antistatic properties, mechanical properties and flame retardant properties.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: An antistatic EVA foam composite material comprises the following raw materials in parts by weight: 80-100 parts of ethylene-vinyl acetate copolymer, 40-60 parts of low-density polyethylene, 2-4 parts of conductive filler, 2-5 parts of foaming agent, 1-2 parts of foaming aid, and 1-3 parts of crosslinking agent, wherein the conductive filler is modified graphene oxide; The preparation method of the modified graphene oxide is: S1. Add 3-aminopropyltriethoxysilane, epoxyphenylpropane, N,N-dimethylcyclohexylamine and 2-methyltetrahydrofuran to the reactor under stirring, increase the temperature to 65-75° C., react for 6-8 hours, cool to room temperature, filter, distill under reduced pressure and dry to obtain product 1; S2, adding the product 1 obtained in step S1, phosphoric acid and 2-methyltetrahydrofuran to the reactor under stirring conditions, raising the temperature to 70-80° C., reacting for 4-7 hours, cooling to room temperature, filtering, distilling under reduced pressure and drying to obtain product 2; S3, ultrasonically dispersing the graphene oxide powder in N,N-dimethylformamide, adding the product 2 obtained in step S2, continuing the ultrasonic treatment for 80-100 min, then reflux reacting at 65-75° C. for 20-30 h, cooling to room temperature, filtering, washing, drying and grinding to obtain modified graphene oxide; Wherein, the synthetic route of product 2 is as follows: ; .

[0006] Graphene oxide is obtained by oxidation and exfoliation of natural graphite by strong oxidants. The hybridization type of carbon atoms in the original graphite structure is sp 2The two-dimensional sheet material of carbon structure has the characteristics of high mechanical strength, large specific surface area, good barrier property and excellent antistatic performance. However, due to the van der Waals force and π-π effect between graphene sheets, graphene oxide is very easy to agglomerate in organic systems, and the dispersion of graphene oxide in organic systems is severely limited. How to improve the dispersion uniformity of graphene oxide in organic systems has become a hot topic for scientists to study nowadays. The present invention first uses 3-aminopropyltriethoxysilane and epoxyphenylpropane as raw materials, and an epoxy ring-opening reaction occurs under the catalysis of N,N-dimethylcyclohexylamine to obtain product 1; then, product 1 and phosphoric acid are used as raw materials to undergo an esterification reaction to obtain product 2; finally, product 2 is used as a modifier, and an organic molecular chain is grafted on the surface of graphene oxide by silanization reaction to obtain modified graphene oxide. The grafting of organic molecular chains improves the interface dispersibility and compatibility of graphene oxide in organic systems, and improves the antistatic and mechanical properties of the material.

[0007] In order to obtain modified graphene oxide and improve its compatibility with organic systems and its dispersibility in organic systems, the molar ratio of 3-aminopropyltriethoxysilane, epoxyphenylpropane, and N,N-dimethylcyclohexylamine in step S1 is 0.9-1.1:1:0.03-0.06; the mass volume ratio of 3-aminopropyltriethoxysilane to 2-methyltetrahydrofuran is 0.22-0.34 g / mL; the molar ratio of product 1 to phosphoric acid in step S2 is 1:1 .1-1.3; the mass volume ratio of the product 1 to 2-methyltetrahydrofuran is 0.2-0.3g / mL; the mass ratio of the graphene oxide powder and the product 2 in step S3 is 1:3-5, the amount of graphene oxide powder added to N,N-dimethylformamide is 0.005-0.015g / mL, the ultrasonic power is 400-600W, and the ultrasonic time for ultrasonically dispersing the graphene oxide powder in N,N-dimethylformamide is 20-40min.

[0008] Furthermore, the foaming agent is azodicarbonamide; the foaming aid is prepared by mixing equal masses of zinc stearate and zinc oxide; the crosslinking agent is prepared by mixing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate, and the mass ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate is 6:1-3.

[0009] The present invention also provides a method for preparing an antistatic EVA foam composite material, comprising the following steps: firstly adding ethylene-vinyl acetate copolymer, low-density polyethylene and conductive filler into an internal mixer, and internally mixing at a temperature of 90-110°C for 10-20min, then adding a foaming agent, a foaming aid and a cross-linking agent, and internally mixing at a temperature of 150-180°C for 5-15min to obtain a mixture, and finally placing the mixture on a flat vulcanizer for hot pressing into a sheet, namely the antistatic EVA foam composite material; wherein the internal mixer has a rotation speed of 30-50r / min, and the specific operation of hot pressing into a sheet is: mold foaming at a pressure of 10MPa and a temperature of 170-180°C for 5-15min.

[0010] The present invention has the following beneficial effects: The invention prepares modified graphene oxide through epoxy compound ring-opening reaction, esterification reaction and silylation reaction in sequence, and introduces siloxane, phosphate and benzene ring on the surface of graphene oxide. The introduction of phosphate esters makes the phosphate molecules excited and decompose when the material is exposed to a combustion source, producing phosphate acetal and gaseous phosphate free radicals. The acetal produced by the decomposition of phosphate acetal can react with hydrogen on the surface of the material to prevent the material from further decomposing. The phosphate free radicals react with oxygen in the air to form phosphate oxides, which in turn form a protective layer on the surface of the material to inhibit combustion. The introduction of benzene rings can improve the aggregation and agglomeration of graphene oxide powder in organic systems and improve the dispersion uniformity of the powder. The introduction of siloxanes can increase the interfacial adhesion between graphene oxide and raw materials such as ethylene-vinyl acetate copolymer and polyethylene. The introduction of a variety of organic functional groups on the surface of graphene oxide can not only increase its compatibility with organic systems, but also affect the dispersibility and reactivity of the material by increasing the steric hindrance between particles, so that the modified graphene oxide can be evenly distributed in the organic system and fully exert its function, thereby significantly improving the antistatic and mechanical properties of the foam composite material.

[0011] The present invention compounds ethylene-vinyl acetate copolymer, low-density polyethylene, modified graphene oxide, a crosslinking agent, a foaming agent and a foaming aid, and the components interact with each other, thereby reducing the amount of inorganic filler used, and significantly improving the antistatic property, mechanical property and flame retardant property of the composite material while ensuring the density and resilience of the EVA foam composite material. DETAILED DESCRIPTION

[0012] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0013] Graphene oxide powder, brand GFA1, diameter 0.5-3 μm, thickness 0.55-1.2 nm, oxygen content of oxygen-containing groups 30-40%, purchased from Beijing Dekedaojin Technology Co., Ltd.; ethylene-vinyl acetate copolymer (EVA), brand Japan Mitsui Chemicals, model 45LX, VA content 19%; low-density polyethylene, brand VL8005, density 0.9 g / cm 3 , purchased from Dongguan Hongkuo Plastic Co., Ltd. The raw materials used in the following examples are all common commercially available products.

[0014] Example 1 A method for preparing modified graphene oxide comprises the following steps: S1. Add 3-aminopropyltriethoxysilane, epoxyphenylpropane, N,N-dimethylcyclohexylamine and 2-methyltetrahydrofuran to the reactor under stirring at 180 rpm, raise the temperature to 70°C, react for 7 hours, cool naturally to room temperature, filter, take the filtrate, remove 2-methyltetrahydrofuran by reduced pressure distillation, and dry in a vacuum drying oven at 55°C for 6 hours to obtain product 1; wherein the molar ratio of 3-aminopropyltriethoxysilane, epoxyphenylpropane and N,N-dimethylcyclohexylamine is 1:1:0.04, and the mass volume ratio of 3-aminopropyltriethoxysilane to 2-methyltetrahydrofuran is 0.27 g / mL; S2, adding the product 1 obtained in step S1, phosphoric acid, and 2-methyltetrahydrofuran to the reactor under stirring at 180 rpm, raising the temperature to 75°C, reacting for 6 hours, naturally cooling to room temperature, filtering, taking the filtrate, removing 2-methyltetrahydrofuran by reduced pressure distillation, and drying in a vacuum drying oven at 55°C for 12 hours to obtain product 2; wherein the molar ratio of product 1 to phosphoric acid is 1:1.2, and the mass volume ratio of product 1 to 2-methyltetrahydrofuran is 0.25 g / mL; The NMR results of product 2 are: 1 H NMR (300MHz, DMSO-d6) δ 7.19-7.23 (m, 5H), 4.20 (s, 2H), 3.90-3.94 (m, 1H), 3.80-3.83 (m, 6H), 3.70 (s, 1H), 2.98- 3.02 (m, 2H), 2.73-2.79 (m, 2H), 2.53 (t, 2H), 1.35-1.39 (m, 2H), 1.21 (t, 9H), 0.56 (t, 2H); S3, ultrasonically disperse the graphene oxide powder in N, N-dimethylformamide, the ultrasonic power is 500 W, the ultrasonic time is 30 min, then add the product 2 obtained in step S2, continue ultrasonic treatment for 90 min, the ultrasonic power is 500 W, then reflux reaction at 70 ° C for 24 h under stirring at 200 rpm, naturally cool to room temperature, filter, take the filter residue, repeatedly wash with N, N-dimethylformamide and distilled water until neutral, dry in a vacuum drying oven at 80 ° C for 24 h, grind and sieve to obtain modified graphene oxide with a diameter of 1-3 μm; wherein, the mass ratio of graphene oxide powder to product 2 is 1:4, and the amount of graphene oxide powder added to N, N-dimethylformamide is 0.01 g / mL.

[0015] The grafting rate of the modified graphene oxide prepared in this example was measured. The mass of the empty crucible was first weighed, and the modified graphene oxide dried to a constant weight was added. The crucible with the modified graphene oxide added was weighed again, and the data was recorded. The muffle furnace was set to 800°C, and the modified graphene oxide was weighed again after high-temperature calcination for 6 hours. The grafting rate of the modified graphene oxide was calculated. The calculation formula is: Grafting rate (%) = (M 前 -M 后 ) / M 前 ×100%, where M 前 is the mass of modified graphene oxide before calcination, M 后 is the mass of modified graphene oxide after calcination, and the grafting rate of modified graphene oxide is measured to be 4.8%.

[0016] An antistatic EVA foam composite material comprises the following raw materials in parts by weight: 90 parts of ethylene-vinyl acetate copolymer, 50 parts of low-density polyethylene, 3 parts of conductive filler, 4 parts of foaming agent, 1.5 parts of foaming aid, and 2 parts of cross-linking agent; the conductive filler is modified graphene oxide, the foaming agent is azodicarbonamide, the foaming aid is prepared by mixing zinc stearate and zinc oxide of equal mass, the cross-linking agent is prepared by mixing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate, and the mass ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane to triallyl isocyanurate is 6:1.

[0017] A preparation method of an antistatic EVA foam composite material comprises the following steps: firstly, adding ethylene-vinyl acetate copolymer, low-density polyethylene and conductive filler into an internal mixer, and internally mixing them at a temperature of 100 DEG C for 15 minutes; then, adding a foaming agent, a foaming aid and a crosslinking agent, and internally mixing them at a temperature of 170 DEG C for 10 minutes to obtain a mixture; and finally, placing the mixture on a flat vulcanizer and hot-pressing it into a sheet with a thickness of 3 mm, namely, the antistatic EVA foam composite material; wherein the internal mixer has a rotating speed of 40 r / min, and the specific operation of hot-pressing the sheet is: molding and foaming for 10 minutes at a pressure of 10 MPa and a temperature of 180 DEG C.

[0018] Example 2 A method for preparing modified graphene oxide is prepared according to the method described in Example 1, except that: in step S3, the mass ratio of graphene oxide powder to product 2 is 1:5, and the reaction is refluxed at 65° C. for 30 hours. The grafting rate of the prepared modified graphene oxide is 5.2%.

[0019] An antistatic EVA foam composite material comprises the following raw materials in parts by weight: 100 parts of ethylene-vinyl acetate copolymer, 40 parts of low-density polyethylene, 2 parts of conductive filler, 2 parts of foaming agent, 2 parts of foaming aid, and 3 parts of crosslinking agent; the conductive filler is modified graphene oxide, the foaming agent is azodicarbonamide, the foaming aid is prepared by mixing zinc stearate and zinc oxide of equal mass, the crosslinking agent is prepared by mixing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate, and the mass ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane to triallyl isocyanurate is 6:2.

[0020] A preparation method of an antistatic EVA foam composite material comprises the following steps: firstly, adding ethylene-vinyl acetate copolymer, low-density polyethylene and conductive filler into an internal mixer, and internally mixing at a temperature of 110 DEG C for 10 minutes; then, adding a foaming agent, a foaming aid and a crosslinking agent, and internally mixing at a temperature of 180 DEG C for 5 minutes to obtain a mixture; and finally, placing the mixture on a flat vulcanizer and hot-pressing it into a sheet with a thickness of 3.2 mm, namely, the antistatic EVA foam composite material; wherein, the internal mixer has a rotating speed of 30 r / min, and the specific operation of hot-pressing the sheet is: molding and foaming at a pressure of 10 MPa and a temperature of 180 DEG C for 10 minutes.

[0021] Example 3 A method for preparing modified graphene oxide is prepared according to the method described in Example 1, except that: in step S3, the mass ratio of graphene oxide powder to product 2 is 1:3, and the reaction is refluxed at 75° C. for 20 hours. The grafting rate of the prepared modified graphene oxide is 4.3%.

[0022] An antistatic EVA foam composite material comprises the following raw materials in parts by weight: 80 parts of ethylene-vinyl acetate copolymer, 60 parts of low-density polyethylene, 4 parts of conductive filler, 5 parts of foaming agent, 1 part of foaming aid and 1 part of cross-linking agent; the conductive filler is modified graphene oxide, the foaming agent is azodicarbonamide, the foaming aid is prepared by mixing zinc stearate and zinc oxide of equal mass, the cross-linking agent is prepared by mixing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate, and the mass ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane to triallyl isocyanurate is 6:3.

[0023] A preparation method of an antistatic EVA foam composite material comprises the following steps: firstly, adding ethylene-vinyl acetate copolymer, low-density polyethylene and conductive filler into an internal mixer, and internal mixing at 90 DEG C for 20 minutes; then, adding a foaming agent, a foaming aid and a crosslinking agent, and internal mixing at 160 DEG C for 15 minutes to obtain a mixture; and finally, placing the mixture on a flat vulcanizer and hot-pressing it into a sheet with a thickness of 2.9 mm, namely, the antistatic EVA foam composite material; wherein, the internal mixer has a rotating speed of 50 r / min, and the specific operation of hot-pressing the sheet is: molding and foaming for 15 minutes at a pressure of 10 MPa and a temperature of 170 DEG C.

[0024] Comparative Example 1 A method for preparing modified graphene oxide is prepared according to the method described in Example 1, except that in step S3, the mass ratio of graphene oxide powder to product 2 is 1:1, and the reaction is refluxed at 80° C. for 24 hours.

[0025] An antistatic EVA foam composite material and a preparation method thereof are prepared according to the method described in Example 1.

[0026] Comparative Example 2 A method for preparing modified graphene oxide comprises the following steps: The graphene oxide powder was ultrasonically dispersed in N, N-dimethylformamide with an ultrasonic power of 500 W and an ultrasonic time of 30 min. 3-aminopropyltriethoxysilane was then added and ultrasonic treatment was continued for 90 min with an ultrasonic power of 500 W. The mixture was then refluxed at 70° C. for 24 h under stirring at 200 rpm, naturally cooled to room temperature, filtered, and the residue was taken. The residue was repeatedly washed with N, N-dimethylformamide and distilled water until neutral, dried in a vacuum drying oven at 80° C. for 24 h, ground and sieved to obtain modified graphene oxide with a diameter of 1-3 μm. The mass ratio of graphene oxide powder to 3-aminopropyltriethoxysilane was 1:3.5, and the amount of graphene oxide powder added to N, N-dimethylformamide was 0.01 g / mL.

[0027] An antistatic EVA foam composite material and a preparation method thereof are prepared according to the method described in Example 1.

[0028] Comparative Example 3 An antistatic EVA foam composite material comprises the following raw materials in parts by weight: 100 parts of ethylene-vinyl acetate copolymer, 20 parts of low-density polyethylene, 1.5 parts of conductive filler, 3 parts of foaming agent, 1 part of foaming aid, and 2 parts of cross-linking agent; the conductive filler is the modified graphene oxide prepared in Example 1, the foaming agent is azodicarbonamide, the foaming aid is prepared by mixing equal masses of zinc stearate and zinc oxide, the cross-linking agent is prepared by mixing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate, and the mass ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane to triallyl isocyanurate is 6:2.

[0029] A method for preparing an antistatic EVA foam composite material is prepared according to the method described in Example 1.

[0030] Relevant performance tests were performed on the antistatic EVA foam composite materials prepared in Examples 1-3 and Comparative Examples 1-3. The volume resistivity test was carried out in accordance with GB / T1410-2006 "Test method for volume resistivity and surface resistivity of solid insulating materials", and the volume resistivity of the sample was tested using a 4339A / B high insulation resistance meter; the tensile strength test and elongation at break test were carried out in accordance with GB / T1040-1992 "Test method for tensile properties of plastics", and the sample was cut into a dumbbell shape with a size of 4mm×75mm×2mm, and the test was carried out using a microcomputer-controlled universal testing machine with a tensile speed of 50mm / min; the density test was carried out in accordance with GB / T533-2008 "Determination of density of vulcanized rubber or thermoplastic rubber"; the rebound resilience test was carried out in accordance with GB / T10652-2001 "Determination of elasticity of porous polymer elastic materials"; the limiting oxygen index test was carried out in accordance with GB / T2406.2-2009 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test"; the above tests were repeated three times and the average value was taken. The test results are shown in Table 1. As can be seen from Table 1, the volume resistivity, tensile strength, elongation at break, and limiting oxygen index of the EVA foam composite materials prepared in Examples 1-3 are significantly better than those in Comparative Examples 1-3, and the density and resilience do not change significantly; the volume resistivity of the EVA foam composite materials prepared in Examples 1-3 is 10 7 -10 8 Ω·cm, reaching the antistatic standard (10 6 -10 9Ω·cm), among which the EVA foam composite material prepared in Example 1 has the best antistatic performance. The limiting oxygen index is an important index to measure the combustion performance of materials. It indicates the minimum oxygen concentration required for the material to maintain combustion in a mixed gas of oxygen and nitrogen. The level of this index directly reflects the combustion difficulty of the material. Generally speaking, the higher the limiting oxygen index, the better the flame retardant performance of the material. Compared with comparative examples 1-3, the EVA foam composite materials prepared in Examples 1-3 show excellent flame retardant performance.

[0031]

[0032] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An antistatic EVA foam composite material, characterized in that: The invention comprises the following raw materials in parts by weight: 80-100 parts of ethylene-vinyl acetate copolymer, 40-60 parts of low-density polyethylene, 2-4 parts of conductive filler, 2-5 parts of foaming agent, 1-2 parts of foaming aid, and 1-3 parts of cross-linking agent, wherein the conductive filler is modified graphene oxide; The preparation method of the modified graphene oxide is: S1. Add 3-aminopropyltriethoxysilane, epoxyphenylpropane, N,N-dimethylcyclohexylamine and 2-methyltetrahydrofuran to the reactor under stirring, increase the temperature to 65-75° C., react for 6-8 hours, cool to room temperature, filter, distill under reduced pressure and dry to obtain product 1; S2, adding the product 1 obtained in step S1, phosphoric acid and 2-methyltetrahydrofuran to the reactor under stirring conditions, raising the temperature to 70-80° C., reacting for 4-7 hours, cooling to room temperature, filtering, distilling under reduced pressure and drying to obtain product 2; S3, ultrasonically dispersing the graphene oxide powder in N,N-dimethylformamide, adding the product 2 obtained in step S2, continuing the ultrasonic treatment for 80-100 min, then reflux reacting at 65-75° C. for 20-30 h, cooling to room temperature, filtering, washing, drying and grinding to obtain modified graphene oxide.

2. The antistatic EVA foam composite material according to claim 1, characterized in that: The molar ratio of 3-aminopropyltriethoxysilane, epoxyphenylpropane and N,N-dimethylcyclohexylamine in step S1 is 0.9-1.1:1:0.03-0.06; the mass volume ratio of 3-aminopropyltriethoxysilane to 2-methyltetrahydrofuran is 0.22-0.34 g / mL.

3. The antistatic EVA foam composite material according to claim 1, characterized in that: The molar ratio of the product 1 to phosphoric acid in step S2 is 1:1.1-1.3; the mass volume ratio of the product 1 to 2-methyltetrahydrofuran is 0.2-0.3 g / mL.

4. The antistatic EVA foam composite material according to claim 1, characterized in that: The mass ratio of the graphene oxide powder and the product 2 in step S3 is 1:3-5, and the amount of the graphene oxide powder added to N,N-dimethylformamide is 0.005-0.015 g / mL.

5. The antistatic EVA foam composite material according to claim 1, characterized in that: The ultrasonic power in step S3 is 400-600 W, and the ultrasonic time for ultrasonically dispersing the graphene oxide powder in N,N-dimethylformamide is 20-40 min.

6. The antistatic EVA foam composite material according to claim 1, characterized in that: The foaming agent is azodicarbonamide.

7. The antistatic EVA foam composite material according to claim 1, characterized in that: The foaming auxiliary agent is prepared by mixing zinc stearate and zinc oxide of equal mass.

8. The antistatic EVA foam composite material according to claim 1, characterized in that: The crosslinking agent is prepared by mixing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and triallyl isocyanurate, and the mass ratio of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane to triallyl isocyanurate is 6:1-3.

9. The method for preparing the antistatic EVA foam composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: First, add ethylene-vinyl acetate copolymer, low-density polyethylene and conductive filler into an internal mixer, and mix them at 90-110°C for 10-20 minutes. Then add foaming agent, foaming aid and cross-linking agent, and mix them at 150-180°C for 5-15 minutes to obtain a mixture. Finally, place the mixture on a flat vulcanizer and hot-press it into a sheet to obtain an antistatic EVA foam composite material.

10. The method for preparing the antistatic EVA foam composite material according to claim 9, characterized in that: The rotating speed of the internal mixer is 30-50 r / min, and the specific operation of hot pressing into sheets is: mold foaming at a pressure of 10 MPa and a temperature of 170-180° C. for 5-15 minutes.

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