Polyethylene composite packaging material containing modified graphene and preparation method thereof

Abstract

This invention relates to a polyethylene composite packaging material containing modified graphene and its preparation method, belonging to the field of polymer materials technology. The invention involves reacting hydroxyl polyethylene with acyl chloride-modified graphene to obtain polyethylene-grafted graphene, followed by quaternization of the tertiary amine groups to obtain graphene modified with both polyethylene and quaternary ammonium salt groups. Furthermore, it utilizes maleic anhydride-grafted polyethylene and epoxy-modified hollow glass microspheres to obtain polyethylene-grafted hollow glass microspheres, followed by reaction of the hydroxyl groups with quaternary phosphonium chloride to obtain hollow glass microspheres modified with both polyethylene and quaternary phosphonium salt groups. The polyethylene segments can improve the affinity between solid particles and the polyethylene substrate, while the quaternary ammonium salt groups and quaternary phosphonium salt groups can further enhance the surface activity of the solid particles, synergistically enhancing the antistatic and antibacterial properties of graphene.

Description

Technical Field

[0001] This invention relates to a polyethylene composite packaging material containing modified graphene and its preparation method, belonging to the field of polymer materials technology. Background Technology

[0002] Polyethylene is a thermoplastic resin produced by the polymerization of ethylene monomers. Polyethylene is a white powder or granules with good flowability, a wide adjustable processing temperature range, and is non-toxic and odorless. It has excellent low-temperature resistance (minimum service temperature can reach -100~-70°C) and good chemical stability; because the polymer molecules are linked by carbon-carbon single bonds, it can resist the erosion of most acids and alkalis. Therefore, polyethylene is a good choice of packaging raw material.

[0003] However, polyethylene has poor electrical conductivity, making it difficult to neutralize static electricity acquired through friction. Furthermore, polyethylene is flammable. Therefore, it is necessary to improve the antistatic and flame-retardant properties of polyethylene.

[0004] Graphene is a planar carbon nanomaterial composed of a single layer of carbon atoms. It is the thinnest known two-dimensional material, with a thickness of only 0.335 nm. The carbon atoms in graphene are connected by σ bonds, giving graphene extremely excellent mechanical properties and structural rigidity. Furthermore, each carbon atom in graphene has one unbonded p electron, which can move freely within the crystal at speeds up to 1 / 300th the speed of light, contributing to graphene's good electrical conductivity. Optically, graphene is almost completely transparent, absorbing only 2.3% of light. In addition, graphene also possesses certain antibacterial properties. Therefore, using graphene to modify polyethylene can improve the polyethylene's heat resistance, flame retardancy, antistatic properties, and antibacterial properties. However, graphene is an inorganic material, and its surface properties differ significantly from those of polyethylene, making it difficult to disperse evenly in polyethylene. Although graphene can be modified with small molecule additives such as silane coupling agents to improve its compatibility and bonding with polyethylene, there is still a certain gap in compatibility between the small molecule coupling agents and polyethylene, resulting in limited improvement in the overall performance of the material. Summary of the Invention

[0005] The purpose of this invention is to provide a polyethylene composite packaging material containing modified graphene and its preparation method, so as to solve the problems of poor heat resistance, flame retardancy, antistatic properties and antibacterial properties in current graphene-modified polyethylene materials.

[0006] This invention provides a method for preparing a polyethylene composite packaging material containing modified graphene, comprising the following steps:

[0007] (1) Graphene oxide nanosheets, chloroacetic acid and sodium hydroxide are mixed and reacted in water to obtain carboxyl-modified graphene; the mass ratio of graphene oxide nanosheets, chloroacetic acid and sodium hydroxide is 0.2:1~1.5:1.2~1.5;

[0008] (2) The carboxyl-modified graphene and thionyl chloride were mixed and reacted to obtain acyl chloride-modified graphene;

[0009] (3) Chlorinated polyethylene, N-phenyldiethanolamine and boron trifluoride are mixed and reacted in a solvent at 60~70℃ for 8~12h to obtain hydroxyl-modified polyethylene; the mass ratio of chlorinated polyethylene and N-phenyldiethanolamine is 5:10;

[0010] (4) Hydroxyl-modified polyethylene and acyl chloride-modified graphene are mixed and reacted to obtain polyethylene-grafted graphene; the mass ratio of hydroxyl-modified polyethylene to acyl chloride-modified graphene is 2~3:1.

[0011] (5) Polyethylene-grafted graphene, chlorinated hydrocarbon compounds and catalyst hexadecyltrimethylammonium bromide are mixed and reacted in a solvent at 80-85°C for 32-40 h to obtain functionalized modified graphene; the chlorinated hydrocarbon compounds are 1-chlorododecane, 1-chlorooctane and 1-chlorodecane;

[0012] (6) After the hollow glass microspheres, acetic acid and solvent are mixed evenly, they are mixed and reacted with γ-(2,3-epoxypropoxy)propyltrimethoxysilane to obtain epoxy-modified hollow glass microspheres; the mass ratio of hollow glass microspheres, acetic acid and γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 10:3~5:5~8.

[0013] (7) Maleic anhydride-grafted polyethylene and epoxy-modified hollow glass microspheres were reacted in a solvent under the action of aniline to obtain hydroxyl polyethylene-grafted hollow glass microspheres; the mass ratio of maleic anhydride-grafted polyethylene and epoxy-modified hollow glass microspheres was 10:6~8.

[0014] (8) Mix 3-carboxypropyltriphenylphosphine bromide and thionyl chloride and react to obtain acyl chloride quaternary phosphonium salt;

[0015] (9) Hydroxyethylene-grafted hollow glass microspheres and acyl chloride quaternary phosphonium salt are mixed and reacted to obtain functionally modified hollow glass microspheres; the mass ratio of hydroxyethylene-grafted hollow glass microspheres to acyl chloride quaternary phosphonium salt is 1:6~8;

[0016] (10) Polyethylene resin, functionalized modified graphene and functionalized modified hollow glass microspheres are melt-extruded to obtain a polyethylene composite packaging material containing modified graphene; the mass ratio of polyethylene resin, functionalized modified graphene and functionalized modified hollow glass microspheres is 100:5~7:3~5.

[0017] Preferably, the mixing reaction time in step (1) is 24~30h; the mixing reaction time in step (9) is 8~10h.

[0018] Preferably, in step (2), the mass ratio of carboxyl-modified graphene to thionyl chloride is 10:80~100, the mixing reaction is carried out under reflux conditions, and the mixing reaction time is 30~36h.

[0019] Preferably, the solvent in step (3) is cyclohexane, the chlorine content of the chlorinated polyethylene is 6%, the molecular weight is 70,000 to 80,000, and the mass ratio of chlorinated polyethylene to boron trifluoride is 5:1.2 to 1.5.

[0020] Preferably, the mixing reaction time in step (4) is 8 to 12 hours.

[0021] Preferably, in step (5), the mass ratio of polyethylene-grafted graphene to chlorinated hydrocarbon compound is 1:1.5~2, and the mass of the catalyst hexadecyltrimethylammonium bromide is 1~2% of the sum of the masses of polyethylene-grafted graphene and chlorinated hydrocarbon compound.

[0022] Preferably, the average particle size of the hollow glass microspheres in step (6) is 10~20μm, the mixing reaction temperature is 45~55℃, and the time is 6~8h.

[0023] Preferably, the temperature of the mixing reaction in step (7) is 100~105℃ and the time is 9~12h.

[0024] Preferably, in step (8), the mass ratio of 3-carboxypropyltriphenylphosphine bromide to thionyl chloride is 10:60~80, the mixing reaction temperature is 60~70℃, and the time is 6~8h.

[0025] This invention provides a polyethylene composite packaging material containing modified graphene, which is prepared by the method described above for preparing polyethylene composite packaging materials containing modified graphene.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) This invention obtains polyethylene-grafted graphene by reacting hydroxyl polyethylene with acyl chloride-modified graphene, and then quaternizing the tertiary amino groups therein to obtain graphene modified with both polyethylene and quaternary ammonium salt groups; and obtains polyethylene-grafted hollow glass microspheres by reacting maleic anhydride-grafted polyethylene with epoxy-modified hollow glass microspheres, and then reacting the hydroxyl groups therein with acyl chloride quaternary phosphonium salts to obtain hollow glass microspheres modified with both polyethylene and quaternary phosphonium salt groups. Finally, the two modified fillers and polyethylene are melt-extruded to obtain polyethylene composite packaging material. The polyethylene segments bonded to the surfaces of modified graphene and modified hollow glass microspheres can improve the affinity between the graphene and the polyethylene substrate. The entanglement of the segments enhances the bonding force with polyethylene. Quaternary ammonium salt groups and quaternary phosphonium salt groups can further improve the surface activity of the solid particles, thereby improving their dispersion in polyethylene. This enhances the antistatic, antibacterial, and flame-retardant properties of the composite material. Furthermore, the graphene can synergistically enhance the antistatic and antibacterial properties of the composite material, further improving its antistatic and antibacterial properties.

[0028] (2) In this invention, the modified glass microspheres with lower density and the modified graphene with higher density can better promote the movement of solid particles in the polyethylene melt through density difference, improve the dispersibility of solid particles, and the sheet-like modified graphene and the spherical modified glass microspheres can be better distributed in the polyethylene matrix in an interlaced and dense manner, thereby improving the antistatic, antibacterial and flame retardant properties of the material.

[0029] (3) In this invention, quaternary ammonium salt modified graphene prepared from 1-chlorododecane, 1-chlorooctane and 1-chlorodecane can improve the surface activity of graphene, while using long-chain alkyl groups to increase the affinity between graphene and polyethylene, reduce the repulsion between polar quaternary ammonium salt and polyethylene, facilitate the dispersion of modified graphene in polyethylene, and thus improve the antistatic, antibacterial and flame retardant properties of the composite material. Detailed Implementation

[0030] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0031] Specific embodiments of the modified graphene-containing polyethylene composite packaging material and its preparation method of the present invention are as follows:

[0032] Example 1

[0033] The preparation method of the polyethylene composite packaging material containing modified graphene in this embodiment includes the following steps:

[0034] (1) Graphene oxide nanosheets were dispersed in water to obtain a graphene oxide nanosheet dispersion with a mass fraction of 2%. Chloroacetic acid and sodium hydroxide were added to the graphene oxide nanosheet dispersion, and the dispersion was ultrasonically dispersed for 1 h. The mixture was then stirred and reacted for 24 h. After filtration, washing, and drying, carboxyl-modified graphene was obtained. The mass ratio of graphene oxide nanosheets, chloroacetic acid, and sodium hydroxide was 0.2:1:1.2.

[0035] (2) Carboxyl-modified graphene and thionyl chloride in a mass ratio of 10:80 were added to the reactor, stirred and heated under reflux for 30 h, filtered, and washed with anhydrous dichloromethane to obtain acyl chloride-modified graphene.

[0036] (3) Add 5g of chlorinated polyethylene (chlorine content 6%, molecular weight 70,000~80,000) and 25g of cyclohexane to a stirred tank. Heat to 55℃ and stir until the chlorinated polyethylene is fully dissolved. Then add 10g of N-phenyldiethanolamine to the stirred tank and stir evenly. Add 1.2g of boron trifluoride catalyst and heat the material in the reactor to 60℃. Stir and react for 8h. After cooling to room temperature, add 200g of ethanol and 2.5g of hydrochloric acid to the reactor and stir evenly. Let stand, filter, wash the filter cake with dilute hydrochloric acid, wash with alkaline solution, and finally wash with water. After drying, hydroxyl-modified polyethylene is obtained. The structure of N-phenyldiethanolamine is as follows: .

[0037] (4) Hydroxy-modified polyethylene and anhydrous tetrahydrofuran were added to a stirred tank, heated to 50°C, and stirred until the hydroxy-modified polyethylene was fully dissolved. Then anhydrous tetrahydrofuran was added for dilution. After cooling to room temperature, a 5% hydroxy-modified polyethylene solution was obtained. Acyl chloride-modified graphene was dispersed in anhydrous dichloromethane to obtain a 10% dispersion. The hydroxy-modified polyethylene solution was slowly added to the dispersion, and then triethylamine was added. The mixture was stirred for 8 hours, filtered, washed with tetrahydrofuran, washed with water, and finally washed with ethanol. After drying, polyethylene-grafted graphene was obtained. The mass ratio of hydroxy-modified polyethylene to acyl chloride-modified graphene was 2:1, and the mass of triethylamine was 10% of the mass of acyl chloride-modified graphene.

[0038] (5) Polyethylene-grafted graphene, chlorinated hydrocarbon compound, catalyst hexadecyltrimethylammonium bromide and acetone were added to a reaction vessel, heated to 80°C, stirred for 32 h, cooled to room temperature, filtered, washed with acetone, washed with ethanol, and dried to obtain functionalized modified graphene; wherein, the chlorinated hydrocarbon compound was 1-chlorododecane, the mass ratio of polyethylene-grafted graphene to chlorinated hydrocarbon compound was 1:1.5, the mass of catalyst hexadecyltrimethylammonium bromide was 1% of the sum of the masses of polyethylene-grafted graphene and chlorinated hydrocarbon compound, and the mass of acetone was 80% of the sum of the masses of polyethylene-grafted graphene and chlorinated hydrocarbon compound.

[0039] (6) Add 10g of hollow glass microspheres (average particle size of 10μm) and 60mL of acetone to the reaction vessel, stir evenly, then add 3g of acetic acid, and then add 5g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, heat to 45℃, stir for 6h, filter, wash with ethanol, and dry to obtain epoxy modified hollow glass microspheres.

[0040] (7) Add 10g of maleic anhydride-grafted polyethylene (molecular weight of 10,000~200,000, grafting rate of 2~6%) and 120g of butyl acetate to a stirred tank, heat to 40°C, and stir until the maleic anhydride-grafted polyethylene is completely dissolved to obtain a maleic anhydride-grafted polyethylene solution. Then add 6g of epoxy-modified hollow glass microspheres and 0.2g of aniline to a reaction vessel, heat to 100°C, stir and react for 9h, cool to room temperature, filter, wash the filter cake with butyl acetate first, then wash with ethanol, and dry to obtain hydroxyl polyethylene-grafted hollow glass microspheres.

[0041] (8) Add 3-carboxypropyltriphenylphosphine bromide and thionyl chloride in a mass ratio of 10:60 to the reaction vessel, stir and heat to 60°C, reflux for 6 hours, remove excess thionyl chloride by vacuum distillation, and obtain acyl chloride quaternary phosphonium salt.

[0042] (9) Hydroxyethylene-grafted hollow glass microspheres and chloroform were added to a stirred tank and stirred until homogeneous to obtain a dispersion with a mass fraction of 6%. Under stirring conditions, a dichloromethane solution of acyl chloride quaternary phosphonium salt (mass fraction of 20%) was added dropwise to the dispersion. After the addition was completed, triethylamine was added to the stirred tank and the reaction was stirred for 8 hours. After the reaction was completed, the mixture was filtered, washed with dichloromethane, and dried to obtain functionally modified hollow glass microspheres. The mass ratio of hydroxyethylene-grafted hollow glass microspheres to acyl chloride quaternary phosphonium salt was 1:6, and the mass of triethylamine was 1% of the mass of acyl chloride quaternary phosphonium salt.

[0043] (10) Mix 100g of polyethylene resin granules, 5g of functionalized modified graphene and 3g of functionalized modified hollow glass microspheres evenly and add them to a twin-screw extruder. Melt extrusion granulation is carried out at 175°C to obtain polyethylene packaging material. In order to obtain film material, the granular polyethylene packaging material can be blown into film at 180°C using a blown film machine to obtain polyethylene packaging film material.

[0044] Example 2

[0045] The preparation method of the polyethylene composite packaging material containing modified graphene in this embodiment includes the following steps:

[0046] (1) Graphene oxide nanosheets were dispersed in water to obtain a graphene oxide nanosheet dispersion with a mass fraction of 2.5%. Chloroacetic acid and sodium hydroxide were added to the graphene oxide nanosheet dispersion, and the dispersion was ultrasonically dispersed for 1 h. The mixture was then stirred and reacted for 28 h. After filtration, washing, and drying, carboxyl-modified graphene was obtained. The mass ratio of graphene oxide nanosheets, chloroacetic acid, and sodium hydroxide was 0.2:1.2:1.4.

[0047] (2) Carboxyl-modified graphene and thionyl chloride in a mass ratio of 10:90 were added to the reactor, stirred and heated under reflux for 34 h, filtered, and washed with anhydrous dichloromethane to obtain acyl chloride-modified graphene.

[0048] (3) Add 5g of chlorinated polyethylene (chlorine content 6%, molecular weight 70,000~80,000) and 30g of cyclohexane to a stirred tank. Heat to 60℃ and stir until the chlorinated polyethylene is fully dissolved. Then add 10g of N-phenyldiethanolamine to the stirred tank and stir evenly. Add 1.4g of boron trifluoride catalyst and heat the material in the reactor to 65℃. Stir and react for 10h. After cooling to room temperature, add 200g of ethanol and 2.5g of hydrochloric acid to the reactor and stir evenly. Let stand, filter, wash the filter cake with dilute hydrochloric acid, wash with alkaline solution, and finally wash with water. After drying, hydroxyl-modified polyethylene is obtained. The structure of N-phenyldiethanolamine is as follows: .

[0049] (4) Hydroxy-modified polyethylene and anhydrous tetrahydrofuran were added to a stirred tank, heated to 50°C, and stirred until the hydroxy-modified polyethylene was fully dissolved. Then anhydrous tetrahydrofuran was added for dilution. After cooling to room temperature, a 6% hydroxy-modified polyethylene solution was obtained. Acyl chloride-modified graphene was dispersed in anhydrous dichloromethane to obtain a 13% dispersion. The hydroxy-modified polyethylene solution was slowly added to the dispersion, and then triethylamine was added. The mixture was stirred for 10 hours, filtered, washed with tetrahydrofuran, washed with water, and finally washed with ethanol. After drying, polyethylene-grafted graphene was obtained. The mass ratio of hydroxy-modified polyethylene to acyl chloride-modified graphene was 2.5:1, and the mass of triethylamine was 13% of the mass of acyl chloride-modified graphene.

[0050] (5) Polyethylene-grafted graphene, chlorinated hydrocarbon compound, catalyst hexadecyltrimethylammonium bromide and acetone were added to a reaction vessel, heated to 83°C, stirred for 36 h, cooled to room temperature, filtered, washed with acetone, washed with ethanol, and dried to obtain functionalized modified graphene; wherein, the chlorinated hydrocarbon compound was 1-chlorododecane, the mass ratio of polyethylene-grafted graphene to chlorinated hydrocarbon compound was 1:1.8, the mass of catalyst hexadecyltrimethylammonium bromide was 1.5% of the sum of the masses of polyethylene-grafted graphene and chlorinated hydrocarbon compound, and the mass of acetone was 90% of the sum of the masses of polyethylene-grafted graphene and chlorinated hydrocarbon compound.

[0051] (6) Add 10g of hollow glass microspheres (average particle size of 15μm) and 70mL of acetone to the reaction vessel, stir evenly, then add 4g of acetic acid, and then add 7g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, heat to 50℃, stir for 7h, filter, wash with ethanol, and dry to obtain epoxy modified hollow glass microspheres.

[0052] (7) Add 10g of maleic anhydride-grafted polyethylene (molecular weight of 10,000~200,000, grafting rate of 2~6%) and 140g of butyl acetate to a stirred tank, heat to 45°C, and stir until the maleic anhydride-grafted polyethylene is completely dissolved to obtain a maleic anhydride-grafted polyethylene solution. Then add 7g of epoxy-modified hollow glass microspheres and 0.3g of aniline to a reaction vessel, heat to 102°C, stir and react for 11h, cool to room temperature, filter, wash the filter cake with butyl acetate first, then wash with ethanol, and dry to obtain hydroxyl polyethylene-grafted hollow glass microspheres.

[0053] (8) Add 3-carboxypropyltriphenylphosphine bromide and thionyl chloride in a mass ratio of 10:70 to the reaction vessel, stir and heat to 65°C, reflux for 7 h, remove excess thionyl chloride by vacuum distillation to obtain acyl chloride quaternary phosphonium salt.

[0054] (9) Hydroxyethylene-grafted hollow glass microspheres and chloroform were added to a stirred tank and stirred until homogeneous to obtain a dispersion with a mass fraction of 7%. Under stirring conditions, a dichloromethane solution of acyl chloride quaternary phosphonium salt (mass fraction of 22%) was added dropwise to the dispersion. After the addition was completed, triethylamine was added to the stirred tank and the reaction was stirred for 9 hours. After the reaction was completed, the mixture was filtered, washed with dichloromethane, and dried to obtain functionally modified hollow glass microspheres. The mass ratio of hydroxyethylene-grafted hollow glass microspheres to acyl chloride quaternary phosphonium salt was 1:7, and the mass of triethylamine was 1.2% of the mass of acyl chloride quaternary phosphonium salt.

[0055] (10) Mix 100g of polyethylene resin granules, 6g of functionalized modified graphene and 4g of functionalized modified hollow glass microspheres evenly and add them to a twin-screw extruder. Melt extrusion granulation is carried out at 178°C to obtain polyethylene packaging material. In order to obtain film material, the granular polyethylene packaging material can be blown into film at 182°C using a blown film machine to obtain polyethylene packaging film material.

[0056] Example 3

[0057] The preparation method of the polyethylene composite packaging material containing modified graphene in this embodiment includes the following steps:

[0058] (1) Graphene oxide nanosheets were dispersed in water to obtain a graphene oxide nanosheet dispersion with a mass fraction of 3%. Chloroacetic acid and sodium hydroxide were added to the graphene oxide nanosheet dispersion, and the dispersion was ultrasonically dispersed for 1 h. The mixture was then stirred and reacted for 30 h. After filtration, washing, and drying, carboxyl-modified graphene was obtained. The mass ratio of graphene oxide nanosheets, chloroacetic acid, and sodium hydroxide was 0.2:1.5:1.5.

[0059] (2) Carboxyl-modified graphene and thionyl chloride in a mass ratio of 10:100 were added to the reactor, stirred and heated under reflux for 36 h, filtered, and washed with anhydrous dichloromethane to obtain acyl chloride-modified graphene.

[0060] (3) Add 5g of chlorinated polyethylene (chlorine content 6%, molecular weight 70,000~80,000) and 35g of cyclohexane to a stirred tank. Heat to 65℃ and stir until the chlorinated polyethylene is fully dissolved. Then add 10g of N-phenyldiethanolamine to the stirred tank and stir evenly. Add 1.5g of boron trifluoride catalyst and heat the material in the reactor to 70℃. Stir and react for 12h. After cooling to room temperature, add 200g of ethanol and 2.5g of hydrochloric acid to the reactor and stir evenly. Let stand, filter, wash the filter cake with dilute hydrochloric acid, wash with alkaline solution, and finally wash with water. After drying, hydroxyl-modified polyethylene is obtained. The structure of N-phenyldiethanolamine is as follows: .

[0061] (4) Hydroxy-modified polyethylene and anhydrous tetrahydrofuran were added to a stirred tank, heated to 50°C, and stirred until the hydroxy-modified polyethylene was fully dissolved. Then anhydrous tetrahydrofuran was added for dilution. After cooling to room temperature, a hydroxy-modified polyethylene solution with a mass fraction of 8% was obtained. Acyl chloride-modified graphene was dispersed in anhydrous dichloromethane to obtain a dispersion with a mass fraction of 15%. The hydroxy-modified polyethylene solution was slowly added to the dispersion, and then triethylamine was added. The mixture was stirred for 12 hours, filtered, washed with tetrahydrofuran, washed with water, and finally washed with ethanol. After drying, polyethylene-grafted graphene was obtained. The mass ratio of hydroxy-modified polyethylene to acyl chloride-modified graphene was 3:1, and the mass of triethylamine was 15% of the mass of acyl chloride-modified graphene.

[0062] (5) Polyethylene-grafted graphene, chlorinated hydrocarbon compound, catalyst hexadecyltrimethylammonium bromide and acetone were added to a reaction vessel, heated to 85°C, stirred for 40 h, cooled to room temperature, filtered, washed with acetone, washed with ethanol, and dried to obtain functionalized modified graphene; wherein, the chlorinated hydrocarbon compound was 1-chlorododecane, the mass ratio of polyethylene-grafted graphene to chlorinated hydrocarbon compound was 1:2, the mass of catalyst hexadecyltrimethylammonium bromide was 2% of the sum of the mass of polyethylene-grafted graphene and chlorinated hydrocarbon compound, and the mass of acetone was 100% of the sum of the mass of polyethylene-grafted graphene and chlorinated hydrocarbon compound.

[0063] (6) Add 10g of hollow glass microspheres (average particle size of 20μm) and 80mL of acetone to the reaction vessel, stir evenly, then add 5g of acetic acid, and then add 8g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, heat to 55℃, stir for 8h, filter, wash with ethanol, and dry to obtain epoxy modified hollow glass microspheres.

[0064] (7) Add 10g of maleic anhydride-grafted polyethylene (molecular weight 10,000~200,000, grafting rate 2~6%) and 150g of butyl acetate to a stirred tank, heat to 50°C, and stir until the maleic anhydride-grafted polyethylene is completely dissolved to obtain a maleic anhydride-grafted polyethylene solution. Then add 8g of epoxy-modified hollow glass microspheres and 0.4g of aniline to a reaction vessel, heat to 105°C, stir and react for 12h, cool to room temperature, filter, wash the filter cake with butyl acetate first, then wash with ethanol, and dry to obtain hydroxyl polyethylene-grafted hollow glass microspheres.

[0065] (8) Add 3-carboxypropyltriphenylphosphine bromide and thionyl chloride in a mass ratio of 10:80 to the reaction vessel, stir and heat to 70°C, reflux for 8 hours, remove excess thionyl chloride by vacuum distillation, and obtain acyl chloride quaternary phosphonium salt.

[0066] (9) Hydroxyethylene-grafted hollow glass microspheres and chloroform were added to a stirred tank and stirred until homogeneous to obtain a dispersion with a mass fraction of 9%. Under stirring conditions, a dichloromethane solution of acyl chloride quaternary phosphonium salt (mass fraction of 25%) was added dropwise to the dispersion. After the addition was completed, triethylamine was added to the stirred tank and the reaction was stirred for 10 hours. After the reaction was completed, the mixture was filtered, washed with dichloromethane, and dried to obtain functionally modified hollow glass microspheres. The mass ratio of hydroxyethylene-grafted hollow glass microspheres to acyl chloride quaternary phosphonium salt was 1:8, and the mass of triethylamine was 1.5% of the mass of acyl chloride quaternary phosphonium salt.

[0067] (10) Mix 100g of polyethylene resin granules, 7g of functionalized modified graphene and 5g of functionalized modified hollow glass microspheres evenly and add them to a twin-screw extruder. Melt extrusion granulation is performed at 180°C to obtain polyethylene packaging material. In order to obtain film material, the granular polyethylene packaging material can be blown into a film at 185°C using a blown film machine to obtain polyethylene packaging film material.

[0068] Example 4

[0069] The preparation method of the polyethylene composite packaging material containing modified graphene in this embodiment includes the following steps:

[0070] (1) This step is the same as step (1) in Example 1.

[0071] (2) This step is the same as step (2) in Example 1.

[0072] (3) Add 5g of chlorinated polyethylene (chlorine content of 6%, molecular weight of 70,000~80,000) and 25g of cyclohexane to a stirred tank, heat to 55°C, and stir until the chlorinated polyethylene is fully dissolved. Then add 10g of 1-phenyl-1,3-propanediol to the stirred tank, stir evenly, add 1.2g of boron trifluoride catalyst, heat the material in the reactor to 60°C, stir and react for 8h, cool to room temperature, add 200g of ethanol and 2.5g of hydrochloric acid to the reactor, stir evenly, let stand, filter, wash the filter cake with dilute hydrochloric acid, wash with alkaline solution, wash with water, and dry to obtain hydroxyl-modified polyethylene.

[0073] (4) Hydroxy-modified polyethylene and anhydrous tetrahydrofuran were added to a stirred tank, heated to 50°C, and stirred until the hydroxy-modified polyethylene was fully dissolved. Then anhydrous tetrahydrofuran was added for dilution. After cooling to room temperature, a 5% hydroxy-modified polyethylene solution was obtained. Acyl chloride-modified graphene was dispersed in anhydrous dichloromethane to obtain a 10% dispersion. The hydroxy-modified polyethylene solution was slowly added to the dispersion, and then triethylamine was added. The mixture was stirred for 8 hours, filtered, washed with tetrahydrofuran, washed with water, and finally washed with ethanol. After drying, functionalized modified graphene was obtained. The mass ratio of hydroxy-modified polyethylene to acyl chloride-modified graphene was 2:1, and the mass of triethylamine was 10% of the mass of acyl chloride-modified graphene.

[0074] (5) This step is the same as step (6) in Example 1.

[0075] (6) Add 10g of maleic anhydride-grafted polyethylene (molecular weight 10,000~200,000, grafting rate 2~6%) and 120g of butyl acetate to a stirred tank, heat to 40°C, and stir until the maleic anhydride-grafted polyethylene is completely dissolved to obtain a maleic anhydride-grafted polyethylene solution. Then add 6g of epoxy-modified hollow glass microspheres and 0.2g of aniline to a reaction vessel, heat to 100°C, stir and react for 9h, cool to room temperature, filter, wash the filter cake with butyl acetate first, then wash with ethanol, and dry to obtain functional modified hollow glass microspheres.

[0076] (7) This step is the same as step (10) in Example 1.

[0077] Example 5

[0078] The difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this embodiment and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 4 is that the 1-phenyl-1,3-propanediol in step (3) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this embodiment is replaced with 1-phenyl-1,4-butanediol.

[0079] Example 6

[0080] The difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this embodiment and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 1 is that the chlorinated hydrocarbon compound in step (5) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this embodiment is 1-chlorooctane.

[0081] Example 7

[0082] The difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this embodiment and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 1 is that the chlorinated hydrocarbon compound in step (5) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this embodiment is 1-chlorodecane.

[0083] Comparative Example 1

[0084] The difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 4 is that 1-phenyl-1,3-propanediol in step (3) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example is replaced with 3-phenyl-1-propanol.

[0085] Comparative Example 2

[0086] The difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 1 is that the mass of the functionalized modified graphene in step (10) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example is 8g, and the mass of the functionalized modified hollow glass microspheres is 0g.

[0087] Comparative Example 3

[0088] The difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 1 is that the mass of the functionalized modified graphene in step (10) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example is 0g, and the mass of the functionalized modified hollow glass microspheres is 8g.

[0089] Comparative Example 4

[0090] The only difference between the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example and the preparation method of the modified graphene-containing polyethylene composite packaging material in Example 1 is that the chlorinated hydrocarbon compound in step (5) of the preparation method of the modified graphene-containing polyethylene composite packaging material in this comparative example is chloropropane.

[0091] Example of effect

[0092] To examine the performance and specific application prospects of the polyethylene packaging materials prepared in each embodiment and comparative example, antistatic, antibacterial, flame retardant, and mechanical property tests were conducted on the polyethylene packaging materials of each embodiment and comparative example. Antistatic performance was evaluated using the surface resistivity of the polyethylene packaging material. Surface resistivity was tested at 12 hours after preparation and at 6 months of storage, according to the method specified in standard GB / T 1410-2016. The surface resistivity at 12 hours and 6 months of storage were represented as B1 and B2, respectively. Antibacterial performance was evaluated using the antibacterial rate, which was tested according to the method specified in standard QB / T2591-2003, using Staphylococcus aureus and Escherichia coli as the experimental bacteria. Flame retardant performance was tested according to the method specified in standard GB / T2406-93, and the test results were expressed as the oxygen index. Tensile strength was tested according to the method specified in standard GB / T1040-92. The antistatic, antibacterial, flame-retardant, and mechanical properties of the polyethylene packaging materials prepared in each embodiment and comparative example are shown in Table 1.

[0093] Table 1. Polyethylene packaging prepared in each embodiment and comparative example.

[0094] Material antistatic properties, antibacterial properties, flame retardant properties and mechanical properties

[0095]

[0096] According to Table 1, as shown in Examples 1 and 4, when only polyethylene-grafted graphene and polyethylene-grafted hollow glass microspheres are used, the prepared composite material has certain antistatic and antibacterial properties. However, in Example 1, the modified graphene is not only connected to polyethylene but also to quaternary ammonium salt groups, and the modified hollow glass microspheres are not only connected to polyethylene but also to quaternary phosphonium salt groups. The polyethylene segments bonded to the surfaces of these two solid particles can improve the affinity between them and the polyethylene host material. The entanglement of the segments improves the bonding force with polyethylene. The quaternary ammonium salt groups and quaternary phosphonium salt groups can further improve the surface activity of the solid particles, thereby improving their dispersion in polyethylene, improving the antistatic, antibacterial, and flame-retardant properties of the composite material, and can synergistically enhance the antistatic and antibacterial properties of graphene, further improving the antistatic and antibacterial properties of the composite material. As shown in Examples 4, 5, and Comparative Example 1, the composite material prepared using monofunctional hydroxyl-modified polyethylene exhibits poor antistatic, antibacterial, and flame-retardant properties. This is because during the reaction of monofunctional hydroxyl-modified polyethylene and acyl chloride-modified graphene, the hydroxyl density on the hydroxyl-modified polyethylene is low, resulting in fewer bonding sites. Consequently, the bonding strength, adhesion, and distribution uniformity of polyethylene on graphene are low, leading to slightly poorer affinity between graphene and the polyethylene matrix, thus affecting the antistatic, antibacterial, and flame-retardant properties of the composite material. As shown in Examples 1 and Comparative Examples 2-3, the overall performance of the composite material prepared using only modified graphene or modified glass microspheres decreases. This may be because the lower density of glass microspheres and the higher density of graphene can better promote the movement of solid particles in the polyethylene melt through density differences, improving the dispersion of solid particles. Furthermore, the sheet-like modified graphene and the spherical modified glass microspheres can be better interwoven and densely distributed in the polyethylene matrix, thereby improving the antistatic, antibacterial, and flame-retardant properties of the material. As can be seen from Example 1 and Comparative Example 4, graphene modified with dodecyl quaternary ammonium salt can improve the antistatic, antibacterial and flame retardant properties of the composite material more than graphene modified with propane quaternary ammonium salt. This is because the carbon chain of propane quaternary ammonium salt is shorter and less nonpolar, and its affinity with polyethylene is smaller than that of dodecyl quaternary ammonium salt. This results in a greater repulsive force between the polar quaternary ammonium salt and polyethylene, which is not conducive to the dispersion of modified graphene in polyethylene, and causes a decrease in the antistatic, antibacterial and flame retardant properties of the composite material.

Claims

1. A method for preparing a polyethylene composite packaging material containing modified graphene, characterized in that, Includes the following steps: (1) Graphene oxide nanosheets, chloroacetic acid and sodium hydroxide are mixed and reacted in water to obtain carboxyl-modified graphene; the mass ratio of graphene oxide nanosheets, chloroacetic acid and sodium hydroxide is 0.2:1~1.5:1.2~1.5; (2) The carboxyl-modified graphene and thionyl chloride were mixed and reacted to obtain acyl chloride-modified graphene; (3) Chlorinated polyethylene, N-phenyldiethanolamine and boron trifluoride are mixed and reacted in a solvent at 60~70℃ for 8~12h to obtain hydroxyl-modified polyethylene; the mass ratio of chlorinated polyethylene and N-phenyldiethanolamine is 5:10; (4) Hydroxyl-modified polyethylene and acyl chloride-modified graphene are mixed and reacted to obtain polyethylene-grafted graphene; the mass ratio of hydroxyl-modified polyethylene to acyl chloride-modified graphene is 2~3:

1. (5) Polyethylene-grafted graphene, chlorinated hydrocarbon compound and catalyst hexadecyltrimethylammonium bromide are mixed and reacted in a solvent at 80~85℃ for 32~40h to obtain functionalized modified graphene. The chlorinated hydrocarbon compounds are 1-chlorododecane, 1-chlorooctane, and 1-chlorodecane; (6) After the hollow glass microspheres, acetic acid and solvent are mixed evenly, they are mixed and reacted with γ-(2,3-epoxypropoxy)propyltrimethoxysilane to obtain epoxy-modified hollow glass microspheres; the mass ratio of hollow glass microspheres, acetic acid and γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 10:3~5:5~8. (7) Maleic anhydride-grafted polyethylene and epoxy-modified hollow glass microspheres were reacted in a solvent under the action of aniline to obtain hydroxyl polyethylene-grafted hollow glass microspheres; the mass ratio of maleic anhydride-grafted polyethylene and epoxy-modified hollow glass microspheres was 10:6~8. (8) Mix 3-carboxypropyltriphenylphosphine bromide and thionyl chloride and react to obtain acyl chloride quaternary phosphonium salt; (9) Hydroxyethylene-grafted hollow glass microspheres and acyl chloride quaternary phosphonium salt are mixed and reacted to obtain functionally modified hollow glass microspheres; the mass ratio of hydroxyethylene-grafted hollow glass microspheres to acyl chloride quaternary phosphonium salt is 1:6~8; (10) Polyethylene resin, functionalized modified graphene and functionalized modified hollow glass microspheres are melt-extruded to obtain a polyethylene composite packaging material containing modified graphene; the mass ratio of polyethylene resin, functionalized modified graphene and functionalized modified hollow glass microspheres is 100:5~7:3~5.

2. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, The mixing reaction time in step (1) is 24~30h; the mixing reaction time in step (9) is 8~10h.

3. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, In step (2), the mass ratio of carboxyl-modified graphene to thionyl chloride is 10:80~100. The mixing reaction is carried out under reflux conditions for 30~36 hours.

4. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, The solvent in step (3) is cyclohexane, the chlorine content of chlorinated polyethylene is 6%, the molecular weight is 70,000~80,000, and the mass ratio of chlorinated polyethylene to boron trifluoride is 5:1.2~1.

5.

5. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, The mixing reaction in step (4) takes 8 to 12 hours.

6. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, In step (5), the mass ratio of polyethylene-grafted graphene to chlorinated hydrocarbon compound is 1:1.5~2, and the mass of the catalyst hexadecyltrimethylammonium bromide is 1~2% of the sum of the masses of polyethylene-grafted graphene and chlorinated hydrocarbon compound.

7. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, The hollow glass microspheres in step (6) have an average particle size of 10~20μm, the mixing reaction temperature is 45~55℃, and the time is 6~8h.

8. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, The temperature of the mixing reaction in step (7) is 100~105℃ and the time is 9~12h.

9. The method for preparing the polyethylene composite packaging material containing modified graphene as described in claim 1, characterized in that, In step (8), the mass ratio of 3-carboxypropyltriphenylphosphine bromide to thionyl chloride is 10:60~80, the temperature of the mixed reaction is 60~70℃, and the time is 6~8h.

10. A polyethylene composite packaging material containing modified graphene prepared by a method for preparing a polyethylene composite packaging material containing modified graphene as described in any one of claims 1-9.

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