A method for preparing an anti-aging recycled plastic particle

Abstract

The application discloses a preparation method of anti-aging regenerated plastic particles and relates to the technical field of plastics. The anti-aging regenerated plastic particles are prepared by using regenerated plastic as raw material, melting and blending the regenerated plastic with layered composite nanoparticles first, increasing the contact sites, removing free radicals and strengthening the anti-aging performance, then immersing the plastic particles into a polymethyl methacrylate hot coating solution mixed with hydroxylated graphene, and finally forming a layer-by-layer assembly structure after cooling to improve the anti-aging performance. The layered composite nanoparticles are prepared by using cobalt chloride and magnesium sulfate to generate layered hydroxide through coprecipitation and then modified by 3-(benzyldimethylammonium) propane sulfonic acid. The sulfonate is intercalated into the layered hydroxide particles to assist magnesium and cobalt hydroxide, realize the effect of flame retardation and smoke suppression, and improve the dispersibility with better contact with free radicals in the plastic, so that the aging is effectively inhibited.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of plastics, in particular to a preparation method of anti-aging regenerated plastic particles. BACKGROUND

[0002] The regenerated plastic refers to a plastic product obtained through a series of processing treatments such as recycling, classification, cleaning, crushing and melting reconstruction of waste plastics. Compared with the use of original plastics, the regenerated plastic has significant advantages in resource utilization, environmental protection and economic benefits. The recycling methods of waste plastics include sanitary landfill, incineration for heat and resource recycling. Landfill and incineration are easy to cause resource waste and secondary pollution, and the modified regenerated products can reach or exceed the performance of the original resin products, and have high added value, which is the development direction of resource recycling of waste plastics. However, the mechanical properties of the directly regenerated products decrease greatly, and there are problems such as inability to resist aging and easy burning.

[0003] At present, the flame-retardant modification of the regenerated plastic mainly includes two ways of physical blending of flame retardants and coating surface treatment. The physical blending of flame retardants is widely used in the flame-retardant modification of the regenerated plastic due to easy processing and low cost. However, the existing regenerated plastic only pays attention to the flame-retardant performance in the flame-retardant modification process, and ignores the influence of the flame-retardant performance on the modification of the anti-aging performance. Since the aging of the regenerated plastic can cause the main chain of the molecular chain to break, it is more flammable, and the durability of the flame-retardant performance is reduced. Therefore, it is very important to develop a regenerated plastic particle with good anti-aging performance, flame retardation and high strength. SUMMARY

[0004] The application aims to provide a preparation method of anti-aging regenerated plastic particles to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the application provides the following technical scheme: a preparation method of anti-aging regenerated plastic particles, comprising the following preparation steps:

[0006] (1) 10-20 parts of magnesium sulfate heptahydrate, 6-14 parts of cobalt chloride hexahydrate and 60-100 parts of deionized water are uniformly mixed, heated to 50-70 DEG C, and stirred at 120 rpm, and the pH value is adjusted to 9-11 with 2mol / L sodium hydroxide aqueous solution, and reacted for 16-24h, then the solid is filtered, washed with deionized water for 3 times, dried in a 35-45 DEG C oven for 12-24h, and ground into a powder with a particle size of 20-70nm to prepare layered nanoparticles;

[0007] (2) 5-11 parts of layered nanoparticles are dispersed in 30-50 parts of an ethanol-water solution, 8-18 parts of 3-(benzyldimethylammonium) propane sulfonic acid-ethanol solution is added dropwise at a rate of 3 mL / min, ultrasonic stirring is performed at 40 kHz and 100 rpm for 2-6 h, the solid is filtered, washed with deionized water and ethanol alternately for 2 times, and dried in an oven at 30-40℃ for 12-24 h to obtain layered composite nanoparticles;

[0008] (3) 85-95 parts of regenerated plastic with a molecular weight of 70000-100000, 4-8 parts of layered composite nanoparticles, and 1-3 parts of plasticizer are uniformly mixed, extruded by an extruder, and pelletized to obtain regenerated plastic particles.

[0009] (4) The regenerated plastic particles are immersed in a hot coating solution for 2-4 min, taken out, cooled, and dried at 45-55℃ for 24-36 h to obtain anti-aging regenerated plastic particles.

[0010] Further, the volume ratio of ethanol to water in the ethanol-water solution in step (2) is 2:3.

[0011] Further, the content of 3-(benzyldimethylammonium) propane sulfonic acid in the 3-(benzyldimethylammonium) propane sulfonic acid-ethanol solution in step (2) is 15 wt%.

[0012] Further, the regenerated plastic in step (3) is polyethylene terephthalate.

[0013] Further, the plasticizer in step (3) is any one or a mixture of multiple of dioctyl phthalate, sodium sulfonate, n-butyl alkyl benzoate, and epoxy soybean oil.

[0014] Further, the parameters of the extruder in step (3) are a die head temperature of 250-270℃, a screw rotation speed of 190-210 r / min, an extrusion pressure of 6-18 MPa, and a shear rate of 200-300 s -1 .

[0015] Further, the preparation step of the hot coating solution in step (4) is as follows: 10-20 parts of polymethyl methacrylate, 0.5-1.5 parts of hydroxylated graphene, and 50-120 parts of toluene are mixed at 60-80℃ under ultrasonic stirring at 40 kHz and 150 rpm for 2-6 h to obtain a hot coating solution.

[0016] Further, the molecular weight of the polymethyl methacrylate is 60000-90000.

[0017] Further, the preparation step of the hydroxylated graphene is: uniformly dispersing 0.1-0.3 parts of graphene in 80-120 parts of water, adjusting the pH to 3 with hydrochloric acid, adding 0.96 parts of ferrous chloride tetrahydrate, adding 20vol% hydrogen peroxide solution at a rate of 50mL / min, adding for 8-30min, stirring at 80rpm for 1-3h, filtering, washing 3 times with deionized water, and drying in an oven at 40-50℃ for 12-18h to obtain the hydroxylated graphene.

[0018] Further, the cooling condition of step (4) is: cooling air temperature 20-30℃, air speed 0.9-1.3m / s, air pressure 500-650Pa, and cooling time 5-15min.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The present application uses recycled plastic as raw material, first melt-blends with layered composite nanoparticles, and during heat treatment, the polymer chain continuously moves, intercalates and exfoliates the layered composite nanoparticles, so that the particle size and thickness are reduced, a large number of defects are generated, the contact sites are increased, the free radicals are removed, and the anti-aging performance is strengthened. At the same time, due to the conversion and dissipation of heat energy, the aging process of the polymer itself is inhibited, the increase of carbonyl value is slowed down, and the anti-aging effect is further enhanced. Then the plastic particles are immersed in the polymethyl methacrylate hot coating solution mixed with hydroxylated graphene, the molecular chain segments of the plastic particles move more intensively in the hot solution, the intermolecular gap increases, which is beneficial to the diffusion and combination of the hot coating solution, improves the compatibility between the coating and the recycled plastic, and modifies the surface defects of the plastic particles, improves the overall mechanical strength. Finally, cooling forms a double-layer structure, increases the reflection and absorption times of ultraviolet rays, and gradually weakens the ultraviolet rays in the process of layer-by-layer blocking and absorption, thereby indirectly improving the anti-aging performance.

[0021] Secondly, the layered composite nanoparticles are generated by co-precipitation of cobalt chloride and magnesium sulfate to form layered hydroxide, and then modified by 3-(benzyl dimethyl ammonium) propane sulfonic acid. The 3-(benzyl dimethyl ammonium) propane sulfonic acid is intercalated into the layered hydroxide particles by sulfonate. The presence of sulfonate can decompose into sulfonate and sulfonate ester salt and other non-combustible products when heated, achieving the effect of flame retardation. Auxiliary magnesium and cobalt hydroxide have a low decomposition temperature. When combustion occurs, a large amount of heat is absorbed, producing water and carbon dioxide gas, which plays a role in inhibiting the diffusion of smoke and blocking oxygen, thereby achieving the effect of flame retardation and smoke suppression. On this basis, as the intercalation reaction proceeds, the interlayer spacing is expanded, the dispersibility is improved, and the contact with the free radicals in the plastic is better, which generates macromolecular free radicals to reduce the attack of free radicals on the plastic particles, effectively inhibiting the occurrence of aging. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only 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 of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] In order to more clearly illustrate the method provided by the present application, the following embodiments are described in detail. In the following embodiments, the test methods of various indexes of the anti-aging recycled plastic particles are as follows:

[0024] Tensile strength: the same mass of plastic particles in the examples and the comparative examples was taken to make a 0.3 mm film, and the film was tested according to GB / T13022.

[0025] Tensile strength after aging: the same mass of plastic particles in the examples and the comparative examples was taken to make a 0.3 mm film, the film was irradiated by a 6 kW xenon lamp and sprayed with water at a pressure of 0.12-0.15 MPa, and the periodical ultraviolet irradiation was performed for 120 minutes as one cycle, in which 18 minutes were for simultaneous spraying and light irradiation, and 120 minutes were for light irradiation alone, and the total exposure time was 2000 hours. Then, the sample was placed in a room temperature environment for 20 hours, and the film was tested according to GB / T13022.

[0026] Oxygen index and flame retardant grade: the same mass of plastic particles in the examples and the comparative examples was taken to make a 0.3 mm film, and the film was tested according to ANSI / UL-94-1985.

[0027] Example 1: (1) 10 parts of magnesium sulfate heptahydrate, 6 parts of cobalt chloride hexahydrate and 60 parts of deionized water were uniformly mixed, heated to 50°C, and stirred at 120 rpm. The pH value was adjusted to 9 with a 2 mol / L sodium hydroxide aqueous solution, and the reaction was performed for 16 h. The solid was filtered, washed with deionized water for 3 times, and dried in a 35°C oven for 12 h. The powder with a particle size of 20 nm was ground to obtain layered nanoparticles;

[0028] (2) 5 parts of the layered nanoparticles were dispersed in 30 parts of a mixture of ethanol and water with a volume ratio of 2:3. 8 parts of 3-(benzyldimethylammonium) propane sulfonic acid-ethanol solution with a content of 15 wt% of 3-(benzyldimethylammonium) propane sulfonic acid was added dropwise at a rate of 3 mL / min, and ultrasonic stirring was performed at 40 kHz and 100 rpm for 2 h. The solid was filtered, washed with deionized water and ethanol alternately for 2 times, and dried in a 30°C oven for 12 h to obtain layered composite nanoparticles.

[0029] (3) 85 parts of polyethylene terephthalate with a molecular weight of 70000, 4 parts of layered composite nanoparticles, and 1 part of dioctyl phthalate are uniformly mixed, and then extruded and cut into particles by an extruder, with a material head temperature of 250°C, a screw rotation speed of 190 r / min, an extrusion pressure of 6 MPa, and a shear rate of 200 s -1 , to obtain regenerated plastic particles;

[0030] (4) 0.1 parts of graphene are uniformly dispersed in 80 parts of water, and then 0.96 parts of ferrous chloride tetrahydrate is added after the pH value is adjusted to 3 by hydrochloric acid. A 20 vol% hydrogen peroxide solution is added at a rate of 50 mL / min for 8 min, and then stirred at 80 rpm for 1 h. After filtration, the product is washed with deionized water for 3 times and dried in an oven at 40°C for 12 h to obtain hydroxylated graphene;

[0031] (5) 10 parts of polymethyl methacrylate with a molecular weight of 60000, 0.5 parts of hydroxylated graphene, and 50 parts of toluene are mixed under ultrasonic stirring at 60°C, 40 kHz, and 150 rpm for 2 h to obtain a hot coating solution;

[0032] (6) The regenerated plastic particles are immersed in the hot coating solution for 2 min, taken out, cooled for 5 min under a cooling wind temperature of 20°C, a wind speed of 0.9 m / s, and a wind pressure of 500 Pa, and then dried at 45°C for 24 h to obtain anti-aging regenerated plastic particles.

[0033] Example 2: (1) 15 parts of magnesium sulfate heptahydrate, 10 parts of cobalt chloride hexahydrate, and 80 parts of deionized water are uniformly mixed, heated to 60°C, and then the pH value is adjusted to 10 by a 2 mol / L sodium hydroxide aqueous solution under stirring at 120 rpm for 20 h. The solid is filtered, washed with deionized water for 3 times, dried in an oven at 40°C for 18 h, ground into a powder with a particle size of 45 nm, and then layered nanoparticles are obtained;

[0034] (2) 8 parts of layered nanoparticles are dispersed in a mixture of 40 parts of ethanol and water with a volume ratio of 2:3. A 3-(benzyldimethylammonium) propane sulfonic acid-ethanol solution with a content of 15 wt% of 3-(benzyldimethylammonium) propane sulfonic acid is added at a rate of 3 mL / min, and then ultrasonic stirring is performed at 40 kHz and 100 rpm for 4 h. The solid is filtered, washed with deionized water and ethanol alternately for 2 times, and then dried in an oven at 35°C for 18 h to obtain layered composite nanoparticles;

[0035] (3) 90 parts of polyethylene terephthalate with a molecular weight of 85000, 6 parts of layered composite nanoparticles, and 2 parts of sodium sulfonate are uniformly mixed, and then extruded and cut into particles by an extruder, with a material head temperature of 260°C, a screw rotation speed of 200 r / min, an extrusion pressure of 12 MPa, and a shear rate of 250 s -1 , to obtain regenerated plastic particles;

[0036] (4) 0.2 parts of graphene was uniformly dispersed in 100 parts of water, and then 0.96 parts of ferrous chloride tetrahydrate was added after the pH value was adjusted to 3 with hydrochloric acid. A 20 vol% hydrogen peroxide solution was added at a rate of 50 mL / min for 19 min, and stirring was performed at 80 rpm for 2 h. Filtration was performed, and the product was washed with deionized water three times and dried in an oven at 45°C for 15 h to obtain hydroxylated graphene;

[0037] (5) 15 parts of polymethyl methacrylate with a molecular weight of 75,000, 1.0 parts of hydroxylated graphene, and 85 parts of toluene were mixed under ultrasonic stirring at 70°C, 40 kHz, and 150 rpm for 4 h to obtain a hot coating solution;

[0038] (6) The regenerated plastic particles were immersed in the hot coating solution for 3 min, taken out, cooled for 10 min under a cooling wind temperature of 25°C, a wind speed of 1.1 m / s, and a wind pressure of 575 Pa, and dried at 50°C for 30 h to obtain the anti-aging regenerated plastic particles.

[0039] Example 3: (1) 20 parts of magnesium sulfate heptahydrate, 14 parts of cobalt chloride hexahydrate, and 100 parts of deionized water were uniformly mixed, heated to 70°C, and then the pH value was adjusted to 11 with a 2 mol / L sodium hydroxide aqueous solution under stirring at 120 rpm. The reaction was performed for 24 h, the solid was filtered, washed with deionized water three times, dried in an oven at 45°C for 24 h, and ground into a powder with a particle size of 70 nm to obtain layered nanoparticles;

[0040] (2) 11 parts of the layered nanoparticles were dispersed in 50 parts of a mixture of ethanol and water in a volume ratio of 2:3, and 18 parts of 3-(benzyldimethylammonium) propane sulfonic acid with a content of 15 wt% was added dropwise at a rate of 3 mL / min. Ultrasonic stirring was performed at 40 kHz and 100 rpm for 6 h, the solid was filtered, washed with deionized water and ethanol alternately for two times, and dried in an oven at 40°C for 24 h to obtain layered composite nanoparticles;

[0041] (3) 95 parts of polyethylene terephthalate with a molecular weight of 100,000, 8 parts of the layered composite nanoparticles, and 3 parts of n-butyl alkylbenzoate were uniformly mixed, and then extruded and cut into particles by an extruder. The die head temperature was 270°C, the screw rotation speed was 210 r / min, the extrusion pressure was 18 MPa, and the shear rate was 300 s -1 , to obtain regenerated plastic particles;

[0042] (4) 0.3 parts of graphene was uniformly dispersed in 120 parts of water, and then 0.96 parts of ferrous chloride tetrahydrate was added after adjusting the pH to 3 with hydrochloric acid. A 20 vol% hydrogen peroxide solution was added at a rate of 50 mL / min for 30 min, and stirring was performed at 80 rpm for 3 h. Filtration was performed, and the product was washed with deionized water three times and dried in an oven at 50°C for 18 h to obtain hydroxylated graphene;

[0043] (5) 20 parts of polymethyl methacrylate with a molecular weight of 90000, 1.5 parts of hydroxylated graphene, and 120 parts of toluene were mixed at 80°C, 40 kHz, and 150 rpm for 6 h to obtain a hot coating solution;

[0044] (6) The recycled plastic particles were immersed in the hot coating solution for 4 min, taken out, cooled at a cooling wind temperature of 30°C, a wind speed of 1.3 m / s, and a wind pressure of 650 Pa for 15 min, and dried at 55°C for 36 h to obtain the anti-aging recycled plastic particles.

[0045] Comparative Example 1: Comparative Example 1 differs from Example 2 in that steps (3) and (5) are different. In step (3), 90 parts of polyethylene terephthalate with a molecular weight of 85000, 6 parts of layered composite nanoparticles, 2 parts of sodium sulfonate, and 1 part of hydroxylated graphene were uniformly mixed, and the mixture was extruded and cut into particles by an extruder at a die head temperature of 260°C, a screw rotation speed of 200 r / min, an extrusion pressure of 12 MPa, and a shear rate of 250 s-1 to obtain recycled plastic particles. In step (5), 15 parts of polymethyl methacrylate with a molecular weight of 75000 and 85 parts of toluene were mixed at 70°C, 40 kHz, and 150 rpm for 4 h to obtain a hot coating solution. The remaining steps are the same as those of Example 2.

[0046] Comparative Example 2: Comparative Example 2 differs from Example 2 in that step (5) is different. In step (5), 15 parts of polymethyl methacrylate with a molecular weight of 75000 and 85 parts of toluene were mixed at 70°C, 40 kHz, and 150 rpm for 4 h to obtain a hot coating solution. The remaining steps are the same as those of Example 2.

[0047] Comparative Example 3: Comparative Example 3 differs from Example 2 in that steps (1) and (2) are not performed, and step (3) is changed to: 90 parts of polyethylene terephthalate with a molecular weight of 85000, 6 parts of 3-(benzyldimethylammonium) propane sulfonic acid, and 2 parts of sodium sulfonate were uniformly mixed, and the mixture was extruded and cut into particles by an extruder at a die head temperature of 260°C, a screw rotation speed of 200 r / min, an extrusion pressure of 12 MPa, and a shear rate of 250 s-1 to obtain recycled plastic particles. The remaining steps are the same as those of Example 2.

[0048] Comparative Example 4: Comparative Example 4 differs from Example 2 in that step (2) is omitted, and step (3) is changed to: 90 parts of polyethylene terephthalate with a molecular weight of 85000, 6 parts of layered nanoparticles, and 2 parts of sodium sulfonate are mixed uniformly, and then extruded by an extruder to obtain recycled plastic particles, with a material head temperature of 260°C, a screw rotation speed of 200 r / min, an extrusion pressure of 12 MPa, and a shear rate of 250 s-1. The remaining steps are the same as those of Example 2.

[0049] Comparative Example 5: Comparative Example 5 differs from Example 2 in that steps (4), (5), and (6) are omitted. The remaining steps are the same as those of Example 2.

[0050] The performance analysis results of the anti-aging recycled plastic particles obtained by using Examples 1 to 3 and Comparative Examples 1 to 5 of the present application are shown in Table 1 below.

[0051] Table 1

[0052]

[0053] From the experimental data comparison of examples 1, 2, 3 and comparative examples 1, 2, 5, it can be found that during the melt blending process of the layered composite nanoparticles and the regenerated plastic, the polymer chains continuously move, intercalate and exfoliate the layered composite nanoparticles, so that the particle size and thickness are reduced, a large number of defects are generated, the contact sites are increased, the free radicals are removed, the anti-aging performance is enhanced, and due to the conversion and dissipation of heat energy, the aging process of the polymer itself is inhibited, the increase of the carbonyl value is slowed down, and the anti-aging effect is further enhanced. At the same time, through the movement of the molecular chain segments of the plastic particles in the hot solution, the intermolecular gap is increased, which is beneficial to the diffusion and combination of the hot coating solution, improves the compatibility between the coating and the regenerated plastic, modifies the internal defects of the plastic particles, improves the overall mechanical strength, and cooperates with the layer-by-layer assembled structure formed after the coating is cooled, increases the reflection and absorption times of ultraviolet rays, and makes the ultraviolet rays gradually weaken in the process of layer-by-layer blocking and absorption, thereby improving the anti-aging performance. From the experimental data comparison of examples 1, 2, 3 and comparative examples 3, 4, it can be found that the layered hydroxide is generated by coprecipitation of cobalt chloride and magnesium sulfate, and is modified by 3-(benzyldimethylammonium) propane sulfonic acid. The sulfonic acid group of 3-(benzyldimethylammonium) propane sulfonic acid is intercalated into the layered hydroxide particles. The presence of sulfonic acid group can generate combustion-inhibited products such as sulfonate and sulfonic acid ester salt when heated, which can assist magnesium and cobalt hydroxide to have a low decomposition temperature. When combustion occurs, a large amount of heat is absorbed, water and carbon dioxide gas are generated, which can inhibit the diffusion of smoke and block oxygen, thereby achieving the effect of improving the limiting oxygen index. At the same time, with the intercalation reaction, the interlayer spacing of the layered hydroxide continues to expand, which improves the dispersibility and helps to better contact with the free radicals in the plastic, generates macromolecular free radicals through the quenching effect with the free radicals in the plastic, reduces the attack of free radicals on the plastic particles, and effectively inhibits the occurrence of aging.

[0054] It is apparent for those skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the claims. Any mark in the claims should not be considered as limiting the involved claims.

Claims

1. A method for preparing aging-resistant recycled plastic granules, characterized in that, The preparation steps include the following: (1) Mix 10-20 parts magnesium sulfate heptahydrate, 6-14 parts cobalt chloride hexahydrate, and 60-100 parts deionized water evenly, heat to 50-70℃, and adjust the pH value to 9-11 with 2mol / L sodium hydroxide aqueous solution while stirring at 120rpm. React for 16-24h, filter to obtain solid, wash with deionized water 3 times, dry in an oven at 35-45℃ for 12-24h, and grind into powder with a particle size of 20-70nm to obtain layered nanoparticles; (2) Disperse 5-11 parts of layered nanoparticles in 30-50 parts of ethanol-water solution, add 8-18 parts of 3-(benzyldimethylammonium)propanesulfonic acid-ethanol solution at a rate of 3 mL / min, and sonicate at 40 kHz and 100 rpm for 2-6 h. Filter to obtain solid, wash twice with deionized water and ethanol alternately, and dry in an oven at 30-40 ℃ for 12-24 h to obtain layered composite nanoparticles. (3) Mix 85-95 parts of recycled plastic with a molecular weight of 70,000-100,000, 4-8 parts of layered composite nanoparticles, and 1-3 parts of plasticizer evenly, and then extrude and granulate the mixture to obtain recycled plastic granules; the recycled plastic is polyethylene terephthalate. (4) Immerse the recycled plastic particles in the hot coating solution for 2-4 minutes, take them out, cool them, and dry them at 45-55℃ for 24-36 hours to obtain aging-resistant recycled plastic particles; the preparation steps of the hot coating solution are as follows: mix 10-20 parts of polymethyl methacrylate, 0.5-1.5 parts of hydroxylated graphene, and 50-120 parts of toluene under ultrasonic stirring at 60-80℃, 40kHz, and 150rpm for 2-6 hours to obtain the hot coating solution.

2. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, In step (2), the volume ratio of ethanol to water in the ethanol-water solution is 2:

3.

3. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, The content of 3-(benzyldimethylammonium)propanesulfonic acid in the 3-propanesulfonic acid-ethanol solution in step (2) is 15 wt%.

4. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, The plasticizer mentioned in step (3) is any one or a mixture of dioctyl phthalate, sodium sulfonate, n-butyl alkyl benzoate, and epoxidized soybean oil.

5. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, The parameters of the extruder in step (3) are: head temperature 250-270℃, screw speed 190-210 r / min, extrusion pressure 6-18 MPa, and shear rate 200-300 s. -1 .

6. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, The molecular weight of the polymethyl methacrylate in step (4) is 60,000 to 90,000.

7. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, The preparation steps of the hydroxylated graphene in step (4) are as follows: 0.1 to 0.3 parts of graphene are uniformly dispersed in 80 to 120 parts of water, the pH is adjusted to 3 with hydrochloric acid, 0.96 parts of ferrous chloride tetrahydrate are added, and 20 vol% hydrogen peroxide solution is added dropwise at a rate of 50 mL / min for 8 to 30 min. The mixture is stirred at 80 rpm for 1 to 3 h, filtered, washed 3 times with deionized water, and dried in an oven at 40 to 50 ℃ for 12 to 18 h to obtain hydroxylated graphene.

8. The method for preparing aging-resistant recycled plastic granules according to claim 1, characterized in that, The cooling conditions described in step (4) are: cooling air temperature 20-30℃, air speed 0.9-1.3m / s, air pressure 500-650Pa, and cooling time 5-15min.

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