Process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic

Abstract

The application discloses a process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic, and relates to the technical field of high polymer materials. In the preparation of the flame-retardant polyethylene plastic, waste polyethylene is extruded and granulated to obtain polyethylene masterbatch; the polyethylene masterbatch is catalytically pyrolyzed, and then is reacted with potassium permanganate to obtain hydroxylated carbon nanotubes; the hydroxylated carbon nanotubes are reacted with 1-(chloro-methyl phosphonyl) ethylene, and then are reacted with (mercapto methyl) triethoxysilane to obtain modified carbon nanotubes; the polyethylene masterbatch is irradiation-grafted with 2-hydroxy-4-propenyl benzophenone and N,N-diethyl allylamine, and then is reacted with chloromethyl triethoxysilane to obtain modified polyethylene; the modified carbon nanotubes and the modified polyethylene are melt-extruded, and then are injection-molded to obtain flame-retardant polyethylene plastic after water treatment. The flame-retardant polyethylene plastic prepared by the application has good flame-retardant performance, antibacterial performance, tensile strength and anti-aging performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic. BACKGROUND

[0002] Polyethylene plastic is the most widely used plastic in terms of production and application. It is widely used in industry, agriculture, medicine, daily necessities and other fields due to its low price, easy processing and light weight. However, with the rapid development of polyethylene plastic, a large amount of waste polyethylene has also been produced. Waste polyethylene is difficult to degrade in nature and has an impact on the environment. In addition, the raw material for synthesizing polyethylene mainly comes from non-renewable petroleum, so it is necessary to recycle and regenerate waste polyethylene.

[0003] Since polyethylene only contains carbon and hydrogen, it has high flammability. At the same time, the tensile strength, anti-aging performance and antibacterial performance of waste polyethylene have decreased, so it is necessary to modify waste polyethylene to have good flame retardant performance, tensile strength, anti-aging performance and antibacterial performance. SUMMARY

[0004] The present application relates to the technical field of high polymer materials, in particular to a process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic.

[0005] To solve the above technical problems, the present application provides the following technical scheme:

[0006] A process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic, the process comprising the following steps: preparing modified carbon nanotubes by sequentially reacting hydroxylated carbon nanotubes with 1-(chloro-methyl phosphonyl) ethylene and (mercapto methyl) triethoxysilane; preparing pre-modified polyethylene by irradiation grafting of polyethylene masterbatch, 2-hydroxy-4-acrylate benzophenone and N,N-diethyl allylamine; preparing modified polyethylene by quaternary ammonium reaction of pre-modified polyethylene and chloromethyl triethoxysilane; and preparing flame-retardant polyethylene plastic by melt extrusion of modified polyethylene and modified carbon nanotubes, injection molding and water treatment.

[0007] As an optimization, the hydroxylated carbon nanotubes are prepared by catalytic cracking of polyethylene masterbatch to obtain carbon nanotubes, and then reacting with potassium permanganate aqueous solution.

[0008] As an optimization, the polyethylene masterbatch is prepared by washing, drying and melt extrusion granulation of waste polyethylene plastic.

[0009] As an optimization, the 2-hydroxy-4-acrylate benzophenone is prepared by reacting 2,4-dihydroxybenzophenone with acryloyl chloride.

[0010] The application discloses a process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic.

[0011] (1) washing the waste polyethylene plastic with deionized water for 2-4 times, drying at 80-90 DEG C for 30 min, adding into a double-screw extruder for melt extrusion and granulation to prepare polyethylene masterbatch;

[0012] (2) uniformly mixing hydroxylated carbon nanotube, 1-(chloro-methyl phosphor) ethylene, triethylamine and tetrahydrofuran according to a mass ratio of 1:(3-4):(1-2):(40-50), stirring at 60-70 DEG C and 200-300 r / min for 10-12 h, filtering, washing with deionized water for 2-4 times, vacuum drying at 55-65 DEG C for 24 h, uniformly mixing the pre-modified carbon nanotube, (mercapto methyl) triethoxysilane, azobis isobutyronitrile and N,N-dimethyl formamide according to a mass ratio of 1:(2-3):(0.02-0.03):(40-50) under nitrogen protection, stirring at 55-65 DEG C and 200-300 r / min for 20-24 h, filtering, washing with anhydrous ethanol for 2-4 times, vacuum drying at 45-55 DEG C for 10-12 h to prepare modified carbon nanotube;

[0013] (3) uniformly mixing pre-irradiation polyethylene, 2-hydroxy-4-acrylate benzophenone, N,N-diethyl allylamine and acetone according to a mass ratio of 1:(0.04-0.06):(0.02-0.04):(30-50), stirring at 60-70 DEG C and 200-300 r / min for 1.5-2.5 h, cooling to room temperature, filtering, washing with acetone for 2-4 times, drying at 50-60 DEG C for 10-12 h to prepare pre-modified polyethylene; uniformly mixing the pre-modified polyethylene, chloromethyl triethoxysilane and N,N-dimethyl formamide according to a mass ratio of 1:(0.5-0.6):(30-50), stirring at 50-60 DEG C and 200-300 r / min for 6-8 h, vacuum drying at 40-50 DEG C for 10-12 h to prepare modified polyethylene;

[0014] (4) uniformly mixing the modified carbon nanotube, the modified polyethylene and dibutyl tin dilaurate according to a mass ratio of 1:(25-35):(0.02-0.04), adding into a double-screw extruder for melt extrusion, injection molding, naturally cooling to room temperature, demolding and taking out, adding deionized water according to a solid-liquid ratio of 1g:(40-50)ml, standing at 80-90 DEG C for 10-12 h, taking out, keeping warm at 60-70 DEG C for 3-4 h, vacuum drying at 50-60 DEG C for 6-8 h to prepare flame-retardant polyethylene plastic.

[0015] As optimization, the process parameters of the melt extrusion granulation in step (1) are: the temperature of the first zone is 180-185℃, the temperature of the second zone is 185-190℃, the temperature of the third zone is 190-195℃, the temperature of the fourth zone is 195-200℃, the temperature of the fifth zone is 200-205℃, and the screw rotation speed is 180-200 r / min.

[0016] As optimization, the preparation process of the hydroxylated carbon nanotube in step (2) is: mixing the carbon nanotube and 40wt%-50wt% potassium permanganate aqueous solution uniformly, refluxing at 95-105℃ under stirring at 200-300 r / min for 10-12 h, filtering, washing with deionized water for 2-4 times, vacuum drying at 60-70℃ for 10-12 h, grinding, and sieving to obtain the hydroxylated carbon nanotube; the preparation process of the carbon nanotube is: mixing iron nitrate nonahydrate and anhydrous ethanol uniformly according to a mass ratio of 1:(20-30), adding 100-200 times of the mass of the iron nitrate nonahydrate of polyethylene masterbatch, uniformly mixing, standing for 12 h for natural drying, heating to 700-900℃ at a heating rate of 5℃ / min under argon atmosphere, and reacting for 2-3 h to obtain the carbon nanotube; the mesh number of the sieve used for sieving is 200 mesh.

[0017] As optimization, the preparation method of the 2-hydroxy-4-acryloyl benzophenone in step (3) is: mixing acryloyl chloride and tetrahydrofuran uniformly according to a mass ratio of 1:(3-5) to prepare an acryloyl chloride solution; mixing 2,4-dihydroxybenzophenone, triethylamine, and tetrahydrofuran uniformly according to a mass ratio of 1:(0.6-0.8):(4-6), uniformly dropping the acryloyl chloride solution of 2-3 times the mass of the 2,4-dihydroxybenzophenone within 2 h, stirring at 0-4℃ and 200-300 r / min for 4-6 h, filtering, washing with saturated sodium bicarbonate aqueous solution for 2-4 times, and vacuum drying at 50-60℃ for 10-12 h to obtain the 2-hydroxy-4-acryloyl benzophenone.

[0018] As optimization, the preparation method of the pre-irradiated polyethylene in step (3) is: pre-irradiating a polyethylene masterbatch with a 1.5 MeV electron accelerator at 55-65℃ and an absorbed dose of 150-250 kGy for 1-2 h under a nitrogen atmosphere to obtain the pre-irradiated polyethylene.

[0019] As optimization, the process parameters of the melt extrusion and injection molding in step (4) are: the temperature of the first zone is 180-190℃, the temperature of the second zone is 190-200℃, the temperature of the third zone is 200-210℃, the temperature of the fourth zone is 210-220℃, the temperature of the fifth zone is 220-230℃, the screw rotation speed is 180-200 r / min, and the mold temperature is 70-80℃.

[0020] As optimization, the waste polyethylene in step (1) is derived from polyethylene agricultural mulch and polyethylene packaging material.

[0021] As optimization, the reaction equation of the pre-modified carbon nanotube in step (2) is:

[0022]

[0023] As optimization, the reaction equation of the modified carbon nanotube in step (2) is:

[0024]

[0025] As optimization, the reaction equation of the 2-hydroxy-4-acrylate benzophenone in step (3) is:

[0026]

[0027] Compared with the prior art, the present application has the beneficial effects that:

[0028] In the preparation of the flame-retardant polyethylene plastic, the waste polyethylene plastic is cleaned, dried, melt-extruded and granulated to obtain a polyethylene masterbatch; the polyethylene masterbatch is catalytically pyrolyzed to obtain carbon nanotubes, which are then oxidized with a potassium permanganate aqueous solution to obtain hydroxylated carbon nanotubes; the hydroxylated carbon nanotubes are reacted with 1-(chloro-methyl phosphor) ethylene to obtain pre-modified carbon nanotubes; the pre-modified carbon nanotubes are subjected to a thiol-ene click reaction with (thiol methyl) triethoxysilane to obtain modified carbon nanotubes; 2,4-dihydroxybenzophenone is reacted with acryloyl chloride to obtain 2-hydroxy-4-acrylate benzophenone; the polyethylene masterbatch is irradiation-grafted with 2-hydroxy-4-acrylate benzophenone and N,N-diethylallylamine to obtain pre-modified polyethylene; the pre-modified polyethylene is subjected to a quaternization reaction with chloromethyl triethoxysilane to obtain modified polyethylene; the modified polyethylene and the modified carbon nanotubes are melt-extruded, injection-molded, and then treated with water to obtain a flame-retardant polyethylene material.

[0029] Firstly, the waste polyethylene plastic is cleaned, dried, melt-extruded and granulated to obtain polyethylene masterbatch; the polyethylene masterbatch is catalytically pyrolyzed to obtain carbon nanotubes, which can improve the tensile strength, and meanwhile, the cavity structure of the carbon nanotubes can absorb ultraviolet light to improve the anti-aging performance; the carbon nanotubes and potassium permanganate aqueous solution are subjected to oxidation reaction to introduce hydroxyl groups on the carbon nanotubes to obtain hydroxylated carbon nanotubes; the hydroxylated carbon nanotubes and 1-(chloro-methyl phosphor) ethylene are reacted to obtain pre-modified carbon nanotubes, the addition of 1-(chloro-methyl phosphor) ethylene improves the flame retardant performance, and meanwhile, double bonds are introduced on the hydroxylated carbon nanotubes; the pre-modified carbon nanotubes and (mercapto methyl) triethoxysilane are subjected to mercapto-ene click reaction to introduce siloxane on the pre-modified carbon nanotubes, which improves the flame retardant performance, and meanwhile, the modification of the carbon nanotubes improves the compatibility and dispersibility of the carbon nanotubes in the polymer, thereby avoiding agglomeration.

[0030] Secondly, 2-hydroxy-4-acryl benzophenone is prepared by reacting 2,4-dihydroxybenzophenone and acryloyl chloride, 2,4-dihydroxybenzophenone is an ultraviolet light absorber, which can improve the anti-aging performance, and after the reaction with acryloyl chloride, double bonds are introduced on the 2,4-dihydroxybenzophenone; the polyethylene masterbatch is subjected to pre-irradiation treatment to introduce free radicals on the polyethylene masterbatch, and then is grafted with 2-hydroxy-4-acryl benzophenone and N,N-diethylallylamine to obtain pre-modified polyethylene, and the ultraviolet light absorber and tertiary amine structure are introduced on the polyethylene masterbatch; the pre-modified polyethylene and chloromethyl triethoxysilane are subjected to quaternization reaction to obtain modified polyethylene, the generated quaternary ammonium salt improves the antibacterial performance of the polyethylene, and meanwhile, the siloxane structure is introduced to improve the flame retardant performance of the polyethylene.

[0031] Finally, the modified polyethylene and the modified carbon nanotubes are subjected to water treatment to obtain flame-retardant polyethylene plastic, and the modified polyethylene and the modified carbon nanotubes both contain siloxane structures, which are hydrolyzed into silanol under the action of water, and then dehydrated and condensed to form a crosslinked structure, thereby improving the tensile strength of the polyethylene plastic, and meanwhile, the silicon element in the siloxane and the phosphorus element in the modified carbon nanotubes synergistically retard flame, thereby improving the flame retardant performance of the polyethylene plastic. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0033] Example 1:

[0034] The application discloses a process for preparing flame-retardant polyethylene plastic from waste polyethylene plastic.

[0035] (1) washing the waste polyethylene plastic with deionized water for 2 times, drying at 80 DEG C for 30 min, adding into a double-screw extruder for melting, the temperature of the first zone is 180 DEG C, the temperature of the second zone is 185 DEG C, the temperature of the third zone is 190 DEG C, the temperature of the fourth zone is 195 DEG C, the temperature of the fifth zone is 200 DEG C, the screw rotation speed is 180 r / min, and the polyethylene master batch is prepared by extruding and granulating;

[0036] (2) mixing the iron nitrate nonahydrate and the absolute ethyl alcohol according to the mass ratio of 1:20, adding the polyethylene master batch with the mass of 100 times of the iron nitrate nonahydrate, uniformly mixing, naturally drying for 12 h, heating to 700 DEG C at the heating rate of 5 DEG C / min under the argon atmosphere, and reacting for 2 h to prepare carbon nanotubes; mixing the carbon nanotubes and the 40wt% potassium permanganate aqueous solution uniformly, stirring and refluxing at 95 DEG C and 200 r / min for 10 h, filtering, washing with deionized water for 2 times, drying at 60 DEG C under vacuum for 10 h, grinding, and passing through a 200-mesh screen to prepare hydroxylated carbon nanotubes; mixing the hydroxylated carbon nanotubes, 1-(chloro-methyl phosphor) ethylene, triethylamine and tetrahydrofuran according to the mass ratio of 1:3:1:40, stirring and reacting at 60 DEG C and 200 r / min for 10 h, filtering, washing with deionized water for 2 times, drying at 55 DEG C under vacuum for 24 h to prepare pre-modified carbon nanotubes; mixing the pre-modified carbon nanotubes, (mercapto methyl) triethoxysilane, azobis isobutyronitrile and N,N-dimethylformamide according to the mass ratio of 1:2:0.02:40 under the protection of nitrogen, stirring and reacting at 55 DEG C and 200 r / min for 20 h, filtering, washing with absolute ethyl alcohol for 2 times, and drying at 45 DEG C under vacuum for 10 h to prepare modified carbon nanotubes;

[0037] (3) mixing acryloyl chloride and tetrahydrofuran uniformly in a mass ratio of 1:3 to prepare an acryloyl chloride solution; mixing 2,4-dihydroxybenzophenone, triethylamine and tetrahydrofuran uniformly in a mass ratio of 1:0.6:4, dropping the acryloyl chloride solution with a mass of 2 times that of 2,4-dihydroxybenzophenone at a constant speed within 2 h, stirring and reacting at 0℃ and 200 r / min for 4 h, filtering and washing twice with saturated sodium bicarbonate aqueous solution, and drying at 50℃ under vacuum for 10 h to prepare 2-hydroxy-4-acryloyl benzophenone; pre-irradiating polyethylene masterbatch with a 1.5 MeV electron accelerator at 55℃ and an absorbed dose of 150 kGy for 1 h to prepare pre-irradiated polyethylene in a nitrogen atmosphere; mixing the pre-irradiated polyethylene, 2-hydroxy-4-acryloyl benzophenone, N,N-diethylallylamine and acetone uniformly in a mass ratio of 1:0.04:0.02:30, stirring and reacting at 60℃ and 200 r / min for 1.5 h, cooling to room temperature, filtering and washing twice with acetone, and drying at 50℃ for 10 h to prepare pre-modified polyethylene; mixing the pre-modified polyethylene, chloromethyltriethoxysilane and N,N-dimethylformamide uniformly in a mass ratio of 1:0.5:30, stirring and reacting at 50℃ and 200 r / min for 6 h, and drying at 40℃ under vacuum for 10 h to prepare modified polyethylene;

[0038] (4) mixing the modified carbon nanotube, the modified polyethylene and dibutyltin dilaurate uniformly in a mass ratio of 1:25:0.02, melting and extruding in a twin-screw extruder, injection molding, setting the temperature of the first zone of the twin-screw extruder to 180℃, the temperature of the second zone to 190℃, the temperature of the third zone to 200℃, the temperature of the fourth zone to 210℃, the temperature of the fifth zone to 220℃, the screw rotation speed to 180 r / min, the mold temperature to 70℃, naturally cooling to room temperature, demolding and taking out, adding deionized water in a solid-liquid ratio of 1 g:40 ml, standing at 80℃ for 10 h, taking out, keeping warm at 60℃ for 3 h, and drying at 50℃ under vacuum for 6 h to prepare the flame-retardant polyethylene plastic.

[0039] Example 2

[0040] A process for preparing a flame-retardant polyethylene plastic from waste polyethylene plastic, comprising the following preparation steps:

[0041] (1) washing the waste polyethylene plastic with deionized water for 3 times, drying at 85℃ for 30 min, melting in a twin-screw extruder, setting the temperature of the first zone to 183℃, the temperature of the second zone to 188℃, the temperature of the third zone to 193℃, the temperature of the fourth zone to 198℃, the temperature of the fifth zone to 203℃, and the screw rotation speed to 190 r / min, and extruding and granulating to prepare polyethylene masterbatch;

[0042] (2) mixing the ferric nitrate nonahydrate and the absolute ethanol uniformly according to the mass ratio of 1:25, adding the polyethylene master batch in an amount of 150 times the mass of the ferric nitrate nonahydrate, mixing uniformly, standing for 12 h for natural drying, heating to 800℃ at a heating rate of 5℃ / min under an argon atmosphere, and reacting for 2.5 h to obtain carbon nanotubes; mixing the carbon nanotubes and a 45wt% potassium permanganate aqueous solution uniformly, stirring at 100℃ and 250 r / min for 11 h under reflux, filtering, washing with deionized water for 3 times, drying at 65℃ under vacuum for 11 h, grinding, and passing through a 200-mesh screen to obtain hydroxylated carbon nanotubes; mixing the hydroxylated carbon nanotubes, 1-(chloro-methyl phosphoryl) ethylene, triethylamine, and tetrahydrofuran uniformly according to the mass ratio of 1:3.5:1.5:45, stirring at 65℃ and 250 r / min for 11 h, filtering, washing with deionized water for 3 times, drying at 60℃ under vacuum for 24 h, and obtaining pre-modified carbon nanotubes; mixing the pre-modified carbon nanotubes, (mercapto methyl) triethoxysilane, azobisisobutyronitrile, and N,N-dimethylformamide uniformly according to the mass ratio of 1:2.5:0.025:45, stirring at 60℃ and 250 r / min for 22 h under nitrogen protection, filtering, washing with absolute ethanol for 3 times, and drying at 50℃ under vacuum for 11 h to obtain modified carbon nanotubes;

[0043] (3) mixing the acryloyl chloride and the tetrahydrofuran uniformly according to the mass ratio of 1:4 to prepare an acryloyl chloride solution; mixing the 2,4-dihydroxybenzophenone, triethylamine, and tetrahydrofuran uniformly according to the mass ratio of 1:0.7:5, dropping the acryloyl chloride solution in an amount of 2.5 times the mass of the 2,4-dihydroxybenzophenone at a uniform speed within 2 h, stirring at 2℃ and 250 r / min for 5 h, filtering, washing with a saturated sodium bicarbonate aqueous solution for 3 times, and drying at 55℃ under vacuum for 11 h to obtain 2-hydroxy-4-acryloyl benzophenone; pre-irradiating the polyethylene master batch with a 1.5 MeV electron accelerator at 60℃ and an absorbed dose of 200 kGy for 1.5 h to obtain pre-irradiated polyethylene under a nitrogen atmosphere; mixing the pre-irradiated polyethylene, the 2-hydroxy-4-acryloyl benzophenone, N,N-diethylallylamine, and acetone uniformly according to the mass ratio of 1:0.05:0.03:40, stirring at 65℃ and 250 r / min for 2 h, cooling to room temperature, filtering, washing with acetone for 3 times, and drying at 55℃ for 11 h to obtain pre-modified polyethylene; mixing the pre-modified polyethylene, chloromethyl triethoxysilane, and N,N-dimethylformamide uniformly according to the mass ratio of 1:0.55:40, stirring at 55℃ and 250 r / min for 7 h, drying at 45℃ under vacuum for 11 h, and obtaining modified polyethylene;

[0044] (4) mixing the modified carbon nanotube, the modified polyethylene, and dibutyltin dilaurate in a mass ratio of 1:30:0.03, adding them into a twin-screw extruder for melt extrusion, injection molding, setting the temperature of the first zone of the twin-screw extruder to 185°C, the temperature of the second zone to 195°C, the temperature of the third zone to 205°C, the temperature of the fourth zone to 215°C, the temperature of the fifth zone to 225°C, the screw rotation speed to 190 r / min, the mold temperature to 75°C, naturally cooling to room temperature, demolding and taking out, adding deionized water in a solid-liquid ratio of 1 g:45 ml, standing at 85°C for 11 h, taking out, keeping at 65°C for 3.5 h, and vacuum drying at 55°C for 7 h to obtain the flame-retardant polyethylene plastic.

[0045] Example 3:

[0046] A process for preparing a flame-retardant polyethylene plastic from waste polyethylene plastic, comprising the following preparation steps:

[0047] (1) washing the waste polyethylene plastic with deionized water for 4 times, drying at 90°C for 30 min, adding into a twin-screw extruder for melting, setting the temperature of the first zone to 185°C, the temperature of the second zone to 190°C, the temperature of the third zone to 195°C, the temperature of the fourth zone to 200°C, the temperature of the fifth zone to 205°C, and the screw rotation speed to 200 r / min, extruding and granulating to obtain a polyethylene masterbatch;

[0048] (2) mixing ferric nitrate nonahydrate and anhydrous ethanol in a mass ratio of 1:30, adding the ferric nitrate nonahydrate into the polyethylene masterbatch in an amount of 200 times the mass of the ferric nitrate nonahydrate, standing for 12 h for natural drying, heating to 900°C at a heating rate of 5°C / min under an argon atmosphere, and reacting for 3 h to obtain carbon nanotubes; mixing the carbon nanotubes and a 50wt% potassium permanganate aqueous solution uniformly, stirring and refluxing at 105°C at 300 r / min for 12 h, filtering and washing with deionized water for 4 times, vacuum drying at 70°C for 12 h, grinding, and passing through a 200-mesh screen to obtain hydroxylated carbon nanotubes; mixing the hydroxylated carbon nanotubes, 1-(chloro-methyl phosphor) ethylene, triethylamine, and tetrahydrofuran in a mass ratio of 1:4:2:50 uniformly, stirring and reacting at 70°C at 300 r / min for 12 h, filtering, washing with deionized water for 4 times, and vacuum drying at 65°C for 24 h to obtain pre-modified carbon nanotubes; mixing the pre-modified carbon nanotubes, (mercapto methyl) triethoxysilane, azobis isobutyronitrile, and N,N-dimethylformamide in a mass ratio of 1:3:0.03:50 uniformly under nitrogen protection, stirring and reacting at 65°C at 300 r / min for 24 h, filtering and washing with anhydrous ethanol for 4 times, and vacuum drying at 55°C for 12 h to obtain modified carbon nanotubes;

[0049] (3) mixing acryloyl chloride and tetrahydrofuran uniformly at a mass ratio of 1:5 to prepare an acryloyl chloride solution; mixing 2,4-dihydroxybenzophenone, triethylamine and tetrahydrofuran uniformly at a mass ratio of 1:0.8:6, adding the acryloyl chloride solution with a mass of 3 times that of 2,4-dihydroxybenzophenone at a uniform speed within 2 h, stirring at 4°C and 300 r / min for 6 h, filtering and washing 4 times with saturated sodium bicarbonate aqueous solution, and drying at 60°C under vacuum for 12 h to prepare 2-hydroxy-4-acryloyl benzophenone; pre-irradiating polyethylene masterbatch with a 1.5 MeV electron accelerator at 65°C and an absorbed dose of 250 kGy for 2 h to prepare pre-irradiated polyethylene; mixing the pre-irradiated polyethylene, 2-hydroxy-4-acryloyl benzophenone, N,N-diethylallylamine and acetone uniformly at a mass ratio of 1:0.06:0.04:50, stirring at 70°C and 300 r / min for 2.5 h, cooling to room temperature, filtering and washing 4 times with acetone, and drying at 60°C for 12 h to prepare pre-modified polyethylene; mixing the pre-modified polyethylene, chloromethyltriethoxysilane and N,N-dimethylformamide uniformly at a mass ratio of 1:0.6:50, stirring at 60°C and 300 r / min for 8 h, and drying at 50°C under vacuum for 12 h to prepare modified polyethylene;

[0050] (4) mixing the modified carbon nanotube, the modified polyethylene and dibutyltin dilaurate uniformly at a mass ratio of 1:35:0.04, melting and extruding in a twin-screw extruder, injection molding, setting the temperature of the first zone of the twin-screw extruder to 190°C, the temperature of the second zone to 200°C, the temperature of the third zone to 210°C, the temperature of the fourth zone to 220°C, the temperature of the fifth zone to 230°C, the screw rotation speed to 200 r / min, and the mold temperature to 80°C, naturally cooling to room temperature, demolding and taking out, adding deionized water at a solid-liquid ratio of 1 g:50 ml, standing at 90°C for 12 h, taking out, standing at 70°C for 4 h, and drying at 60°C under vacuum for 8 h to prepare the flame-retardant polyethylene plastic.

[0051] Comparative Example 1

[0052] The process for preparing the flame-retardant polyethylene plastic from the waste polyethylene plastic of Comparative Example 1 is different from that of Example 2 in step (2). Step (2) is modified as follows: the ferric nitrate nonahydrate and anhydrous ethanol are mixed uniformly at a mass ratio of 1:25, the polyethylene masterbatch is added in an amount of 150 times the mass of the ferric nitrate nonahydrate, and the mixture is mixed uniformly, left to stand for 12 h for natural drying, heated to 800°C at a heating rate of 5°C / min under an argon atmosphere, and reacted for 2.5 h to prepare carbon nanotubes; the carbon nanotubes and 45 wt% potassium permanganate aqueous solution are mixed uniformly, stirred at 100°C and 250 r / min for 11 h under reflux, filtered, washed with deionized water for 3 times, dried at 65°C under vacuum for 11 h, ground, and passed through a 200-mesh sieve to prepare hydroxylated carbon nanotubes; the hydroxylated carbon nanotubes, 1-(chloro-methyl phosphor) ethylene, triethylamine, and tetrahydrofuran are mixed uniformly at a mass ratio of 1:3.5:1.5:45, stirred at 65°C and 250 r / min for 11 h, filtered, washed with deionized water for 3 times, dried at 60°C under vacuum for 24 h, and modified carbon nanotubes are prepared. The remaining steps are the same as those of Example 2.

[0053] Comparative Example 2

[0054] The process for preparing the flame-retardant polyethylene plastic from the waste polyethylene plastic of Comparative Example 2 is different from that of Example 2 in steps (2) and (4). Step (2) is modified as follows: the ferric nitrate nonahydrate and anhydrous ethanol are mixed uniformly at a mass ratio of 1:25, the polyethylene masterbatch is added in an amount of 150 times the mass of the ferric nitrate nonahydrate, and the mixture is mixed uniformly, left to stand for 12 h for natural drying, heated to 800°C at a heating rate of 5°C / min under an argon atmosphere, and reacted for 2.5 h to prepare carbon nanotubes. Step (4) is modified as follows: the carbon nanotubes, modified polyethylene, and dibutyltin dilaurate are mixed uniformly at a mass ratio of 1:30:0.03, injected into a twin-screw extruder for injection molding, the temperature of the first zone of the twin-screw extruder is set to 185°C, the temperature of the second zone is set to 195°C, the temperature of the third zone is set to 205°C, the temperature of the fourth zone is set to 215°C, the temperature of the fifth zone is set to 225°C, the screw rotation speed is set to 190 r / min, the mold temperature is set to 75°C, the product is naturally cooled to room temperature, demolded, and taken out, deionized water is added at a solid-liquid ratio of 1 g:45 ml, left to stand at 85°C for 11 h, taken out, kept warm at 65°C for 3.5 h, and dried under vacuum at 55°C for 7 h to prepare the flame-retardant polyethylene plastic. The remaining steps are the same as those of Example 2.

[0055] Comparative Example 3

[0056] The process for preparing the flame-retardant polyethylene plastic from the waste polyethylene plastic of Comparative Example 3 is different from that of Example 2 in that step (2) is not performed, and step (4) is modified as follows: the modified polyethylene, dibutyltin dilaurate are uniformly mixed at a mass ratio of 1:0.001, and are injected into a twin-screw extruder for injection molding, the temperature of zone one of the twin-screw extruder is set to 185°C, the temperature of zone two is set to 195°C, the temperature of zone three is set to 205°C, the temperature of zone four is set to 215°C, the temperature of zone five is set to 225°C, the screw rotation speed is 190 r / min, the mold temperature is 75°C, and natural cooling to room temperature is performed, and then the product is removed from the mold, deionized water is added at a solid-liquid ratio of 1 g:45 ml, and then the mixture is placed at 85°C for 11 h, and then the product is removed, and then the product is placed at 65°C for 3.5 h, and then the product is vacuum dried at 55°C for 7 h, to obtain the flame-retardant polyethylene plastic. The remaining steps are the same as in Example 2.

[0057] Comparative Example 4:

[0058] The process for preparing the flame-retardant polyethylene plastic from the waste polyethylene plastic of Comparative Example 4 is different from that of Example 2 in that step (3) is different, and step (3) is modified as follows: acryloyl chloride and tetrahydrofuran are uniformly mixed at a mass ratio of 1:4 to prepare an acryloyl chloride solution; 2,4-dihydroxybenzophenone, triethylamine, and tetrahydrofuran are uniformly mixed at a mass ratio of 1:0.7:5, and the 2.5-fold mass of the acryloyl chloride solution of 2,4-dihydroxybenzophenone is added at a constant speed within 2 h, and then the mixture is stirred at 2°C and 250 r / min for 5 h, and then the product is filtered and washed with saturated sodium bicarbonate aqueous solution for 3 times, and then the product is vacuum dried at 55°C for 11 h, to obtain 2-hydroxy-4-acryloyl benzophenone; under a nitrogen atmosphere, the polyethylene masterbatch is pre-irradiated for 1.5 h at 60°C using a 1.5 MeV electron accelerator at an absorbed dose of 200 kGy, to obtain pre-irradiated polyethylene; the pre-irradiated polyethylene, 2-hydroxy-4-acryloyl benzophenone, N,N-diethylallylamine, and acetone are uniformly mixed at a mass ratio of 1:0.05:0.03:40, and then the mixture is stirred at 65°C and 250 r / min for 2 h, and then the mixture is cooled to room temperature, and then the product is filtered and washed with acetone for 3 times, and then the product is dried at 55°C for 11 h, to obtain the modified polyethylene. The remaining steps are the same as in Example 2.

[0059] Comparative Example 5:

[0060] The process for preparing the flame-retardant polyethylene plastic from the waste polyethylene plastic of Comparative Example 5 is different from that of Example 2 in step (3). Step (3) is modified as follows: acryloyl chloride and tetrahydrofuran are uniformly mixed at a mass ratio of 1:4 to prepare an acryloyl chloride solution; 2,4-dihydroxybenzophenone, triethylamine and tetrahydrofuran are uniformly mixed at a mass ratio of 1:0.7:5, and the 2.5-fold mass of the acryloyl chloride solution of 2,4-dihydroxybenzophenone is added dropwise at a uniform speed within 2 h, and the reaction is stirred at 2°C and 250 r / min for 5 h, then filtered and washed with saturated sodium bicarbonate aqueous solution for 3 times, and dried at 55°C under vacuum for 11 h to prepare 2-hydroxy-4-acryloyl benzophenone; the polyethylene masterbatch, 2-hydroxy-4-acryloyl benzophenone, N,N-diethylallylamine and acetone are uniformly mixed at a mass ratio of 1:0.05:0.03:40, and the reaction is stirred at 65°C and 250 r / min for 2 h, then cooled to room temperature, filtered and washed with acetone for 3 times, and dried at 55°C for 11 h to prepare the pre-modified polyethylene; the pre-modified polyethylene, chloromethyl triethoxysilane and N,N-dimethylformamide are uniformly mixed at a mass ratio of 1:0.55:40, and the reaction is stirred at 55°C and 250 r / min for 7 h, and dried at 45°C under vacuum for 11 h to prepare the modified polyethylene. The remaining steps are the same as those of Example 2.

[0061] Comparative Example 6:

[0062] The process for preparing the flame-retardant polyethylene plastic from the waste polyethylene plastic of Comparative Example 6 is different from that of Example 2 in step (4). Step (4) is modified as follows: the modified carbon nanotube, the modified polyethylene and dibutyltin dilaurate are uniformly mixed at a mass ratio of 1:30:0.03, and then injected into a twin-screw extruder for injection molding, and the temperature of the first zone of the twin-screw extruder is set to 185°C, the temperature of the second zone is set to 195°C, the temperature of the third zone is set to 205°C, the temperature of the fourth zone is set to 215°C, the temperature of the fifth zone is set to 225°C, the screw rotation speed is set to 190 r / min, and the mold temperature is set to 75°C, and then naturally cooled to room temperature, demolded and taken out to prepare the flame-retardant polyethylene plastic.

[0063] Test Example 1:

[0064] Flame-retardant property test: The specific test method is as follows:

[0065] The flame-retardant polyethylene plastics obtained in each example and comparative example are tested for the limiting oxygen index according to GB / T 2406-2015.

[0066] The results are shown in Table 1.

[0067] Table 1

[0068]

[0069]

[0070] From the experimental data comparison of examples 1-3 and comparative examples 1-6 in table 1, it can be found that the flame-retardant polyethylene plastic prepared by the present application has good flame-retardant performance.

[0071] By comparison, the limiting oxygen index of examples 1-3 is greater than that of comparative examples 2-3, which shows that after the carbon nanotubes are modified by potassium permanganate and reacted with 1-(chloro-methyl phosphor) ethylene and (mercapto methyl) triethoxysilane to introduce phosphorus and silicon elements on the carbon nanotubes to prepare modified carbon nanotubes, and then reacted with modified polyethylene, the synergistic flame-retardant effect of phosphorus and silicon elements improves the flame-retardant performance of the flame-retardant polyethylene plastic.

[0072] By comparison, the limiting oxygen index of examples 1-3 is greater than that of comparative examples 1, 4-5, which shows that the silicon element in (mercapto methyl) triethoxysilane and chloromethyl triethoxysilane improves the flame-retardant performance of the flame-retardant polyethylene plastic.

[0073] Test example 2:

[0074] Tensile strength and anti-aging performance test:

[0075] The specific test method is as follows:

[0076] Tensile strength test method: the flame-retardant polyethylene plastic obtained in each example and the comparative examples are respectively made into 10cm×10mm×1mm test samples, and tested according to GB / T 1040-2006, the tensile speed is 10mm / min, and the tensile strength M is tested.

[0077] Anti-aging performance test method: the flame-retardant polyethylene plastic obtained in each example and the comparative examples are respectively made into 10cm×10mm×1mm test samples, and placed in an ultraviolet aging test box, the aging time is 360h, the experimental conditions are air atmosphere, the temperature is 65℃, the distance between the light source and the sample is 20cm, and the radiation intensity is 500W / m 2 The tensile strength N is tested again, and the performance decline rate is calculated as 1-N / M×100%.

[0078] The results are shown in table 2.

[0079] Table 2

[0080]

[0081]

[0082] From the experimental data comparison of examples 1-3 and comparative examples 1-6 in table 2, it can be found that the flame-retardant polyethylene plastic prepared by the present application has good tensile strength and anti-aging performance.

[0083] By comparison, the tensile strength of examples 1-3 is greater than that of comparative examples 1-3, which shows that after the carbon nanotubes are modified by potassium permanganate, a large number of hydroxyl groups are introduced on the carbon nanotubes, which react with 1-(chloro-methyl phosphor) ethylene and (mercapto methyl) triethoxysilane in turn to introduce siloxane structure on the carbon nanotubes, and after water treatment, the siloxane on the modified polyethylene forms a cross-linked structure, which improves the tensile strength of the flame-retardant polyethylene plastic; at the same time, due to the unique nano structure and interatomic bond of carbon nanotubes, the carbon nanotubes themselves have good mechanical properties, and when dispersed in the flame-retardant polyethylene plastic, the tensile strength of the flame-retardant polyethylene plastic is improved.

[0084] By comparison, the tensile strength of examples 1-3 is greater than that of comparative examples 4-5, which shows that the polyethylene masterbatch is pre-irradiated to introduce free radicals on the polyethylene masterbatch, so that grafting modification can be carried out, the pre-irradiated polyethylene is grafted with 2-hydroxy-4-acrylate benzophenone and N,N-diethyl allylamine, and then reacts with chloromethyl triethoxysilane to produce modified polyethylene with siloxane structure, and after water treatment, the siloxane in the modified polyethylene forms a cross-linked structure with the siloxane on the modified carbon nanotubes, which improves the tensile strength of the flame-retardant polyethylene plastic.

[0085] By comparison, the tensile strength of examples 1-3 is greater than that of comparative examples 6, which shows that the siloxane in the modified polyethylene and the modified carbon nanotubes needs to be hydrolyzed to form silanol under the action of water, and then dehydrated and condensed to form a cross-linked structure, which improves the tensile strength of the flame-retardant polyethylene plastic.

[0086] By comparison, the performance degradation rate of examples 1-3 is less than that of comparative example 3, which shows that the carbon nanotubes are made of waste polyethylene catalytic cracking, and the cavity structure of the carbon nanotubes can absorb ultraviolet light, which improves the anti-aging performance of the flame-retardant polyethylene plastic.

[0087] By comparison, the performance degradation rate of examples 1-3 is less than that of comparative example 5, which shows that 2,4-dihydroxybenzophenone as an ultraviolet light absorber is grafted onto the pre-irradiated polyethylene by reacting with acryloyl chloride to produce 2-hydroxy-4-acrylate benzophenone with double bonds, which improves the anti-aging performance of the flame-retardant polyethylene plastic.

[0088] Test example 3:

[0089] Antibacterial test: the specific test method is as follows:

[0090] According to GB / T31402-2015 "Plastic Plastic Surface Antimicrobial Performance Test Method", the antibacterial rate of escherichia coli and staphylococcus aureus is tested.

[0091] The results are shown in Table 3.

[0092] Table 3

[0093] Escherichia coli antibacterial rate Staphylococcus aureus antibacterial rate Example 1 99.73％ 99.79％ Example 2 99.86％ 99.88％ Example 3 99.78％ 99.82％ Comparative Example 1 99.65％ 99.70％ Comparative Example 2 99.52％ 99.71％ Comparative Example 3 99.74％ 99.67％ Comparative Example 4 63.22％ 64.81％ Comparative Example 5 62.59％ 62.77％ Comparative Example 6 99.69％ 99.72％

[0094] From the experimental data of examples 1-3 and comparative examples 1-6 in table 3, it can be found that the flame-retardant polyethylene plastic prepared by the present application has good antibacterial performance.

[0095] By comparison, the antibacterial performance of examples 1-3 is greater than that of comparative examples 4-5, which indicates that the quaternary ammonium salt generated by the quaternization reaction of N,N-diethylallylamine and chloromethyl triethoxysilane has good antibacterial performance, thereby improving the antibacterial performance of the flame-retardant polyethylene plastic.

[0096] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic, characterized in that, The preparation steps include the following: (1) Wash the waste polyethylene plastic with deionized water 2 to 4 times, dry it at 80 to 90°C for 30 minutes, add it to a twin-screw extruder for melt extrusion granulation, and obtain polyethylene masterbatch; (2) Hydroxylated carbon nanotubes, 1-(chloro-methylphosphoryl)ethylene, triethylamine, and tetrahydrofuran were mixed evenly at a mass ratio of 1:(3~4):(1~2):(40~50), and stirred at 60~70℃ and 200~300r / min for 10~12h. The mixture was filtered, washed 2~4 times with deionized water, and dried under vacuum at 55~65℃ for 24h to obtain pre-modified carbon nanotubes. Under nitrogen protection, the pre-modified carbon nanotubes were... Modified carbon nanotubes, (mercaptomethyl)triethoxysilane, azobisisobutyronitrile, and N,N-dimethylformamide were mixed evenly in a mass ratio of 1:(2~3):(0.02~0.03):(40~50), and stirred at 55~65℃ and 200~300r / min for 20~24h. The mixture was filtered and washed 2~4 times with anhydrous ethanol, and then vacuum dried at 45~55℃ for 10~12h to obtain modified carbon nanotubes. (3) Pre-irradiated polyethylene, 2-hydroxy-4-propenyl benzophenone, N,N-diethylallylamine, and acetone are mixed evenly in a mass ratio of 1:(0.04~0.06):(0.02~0.04):(30~50), stirred at 60~70℃ and 200~300r / min for 1.5~2.5h, cooled to room temperature, filtered, washed with acetone 2~4 times, and dried at 50~60℃ for 10~12h to obtain pre-modified polyethylene; pre-modified polyethylene, chloromethyltriethoxysilane, and N,N-dimethylformamide are mixed evenly in a mass ratio of 1:(0.5~0.6):(30~50), stirred at 50~60℃ and 200~300r / min for 6~8h, and dried under vacuum at 40~50℃ for 10~12h to obtain modified polyethylene; (4) Mix modified carbon nanotubes, modified polyethylene, and dibutyltin dilaurate at a mass ratio of 1:(25~35):(0.02~0.04), add them to a twin-screw extruder for melt extrusion, injection molding, and allow to cool naturally to room temperature. Remove from the mold, add deionized water at a solid-liquid ratio of 1g:(40~50)ml, let stand at 80~90℃ for 10~12h, remove, keep warm at 60~70℃ for 3~4h, and vacuum dry at 50~60℃ for 6~8h to obtain flame-retardant polyethylene plastic.

2. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 1, characterized in that, The process parameters for melt extrusion granulation in step (1) are: zone 1 temperature 180~185℃, zone 2 temperature 185~190℃, zone 3 temperature 190~195℃, zone 4 temperature 195~200℃, zone 5 temperature 200~205℃, and screw speed 180~200r / min.

3. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 1, characterized in that, The preparation process of the hydroxylated carbon nanotubes in step (2) is as follows: carbon nanotubes and 40wt%~50wt% potassium permanganate aqueous solution are mixed evenly, stirred and refluxed at 95~105℃ and 200~300r / min for 10~12h, filtered and washed with deionized water 2~4 times, vacuum dried at 60~70℃ for 10~12h, ground and sieved to obtain hydroxylated carbon nanotubes.

4. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 1, characterized in that, The preparation method of 2-hydroxy-4-propenyl benzophenone in step (3) is as follows: Acryloyl chloride and tetrahydrofuran are mixed evenly at a mass ratio of 1:(3~5) to prepare an acryloyl chloride solution; 2,4-dihydroxybenzophenone, triethylamine and tetrahydrofuran are mixed evenly at a mass ratio of 1:(0.6~0.8):(4~6), and 2~3 times the mass of acryloyl chloride solution of 2,4-dihydroxybenzophenone is added dropwise at a uniform rate within 2 hours. The mixture is stirred at 0~4℃ and 200~300r / min for 4~6 hours, filtered and washed 2~4 times with saturated sodium bicarbonate aqueous solution, and dried under vacuum at 50~60℃ for 10~12 hours to obtain 2-hydroxy-4-propenyl benzophenone.

5. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 1, characterized in that, The method for preparing pre-irradiated polyethylene in step (3) is as follows: under a nitrogen atmosphere, polyethylene masterbatch is pre-irradiated for 1-2 hours at 55-65°C with an absorbed dose of 150-250 kGy using a 1.5MeV electron accelerator to obtain pre-irradiated polyethylene.

6. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 1, characterized in that, The process parameters for melt extrusion and injection molding in step (4) are as follows: zone 1 temperature is 180~190℃, zone 2 temperature is 190~200℃, zone 3 temperature is 200~210℃, zone 4 temperature is 210~220℃, zone 5 temperature is 220~230℃, screw speed is 180~200r / min, and mold temperature is 70~80℃.

7. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 1, characterized in that, The waste polyethylene mentioned in step (1) comes from polyethylene agricultural film or polyethylene packaging materials.

8. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 3, characterized in that, The preparation method of the carbon nanotubes is as follows: ferric nitrate nonahydrate and anhydrous ethanol are mixed evenly at a mass ratio of 1:(20~30), polyethylene masterbatch of ferric nitrate nonahydrate at a mass ratio of 100~200 times is added and mixed evenly, and allowed to stand for 12 hours to dry naturally. Under an argon atmosphere, the temperature is raised to 700~900℃ at a heating rate of 5℃ / min and reacted for 2~3 hours to obtain carbon nanotubes.

9. The process for recycling and regenerating waste polyethylene plastic to prepare flame-retardant polyethylene plastic according to claim 3, characterized in that, The sieve used for sieving has a mesh size of 200.

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