Anti-aging modified plastic and preparation method thereof

Abstract

The invention relates to the technical field of plastics, and discloses an anti-aging modified plastic and a preparation method thereof.The preparation method comprises the following steps that low-density polyethylene, maleic anhydride grafted polyethylene, an antioxidant 168, calcium stearate, calcium carbonate, 2-(2 '-hydroxy-3', 4 '-dihydroxyphenyl)-1, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate and a plasticizer are mixed, stirred and stirred, and The preparation method comprises the following steps: uniformly mixing 4, 5 '-di-tert-butylphenyl)-benzotriazole, quaternary phosphonium salt modified chitosan and modified magnolol in a high-speed mixer, carrying out extrusion granulation in a twin-screw extruder at a blending temperature of 190-195 DEG C and an extrusion temperature of 170-180 DEG C, drying, and carrying out injection molding by an injection molding machine to obtain the anti-aging modified plastic. The anti-aging modified plastic disclosed by the invention has relatively good anti-aging, flame-retardant and antibacterial effects.

Description

Technical Field

[0001] The present invention relates to the technical field of plastics, in particular to an anti-aging modified plastic and a preparation method thereof. Background Art

[0002] In recent years, plastic products have been widely used in fields such as construction, automobiles, home appliances, and medical treatments. However, long-term exposure to ultraviolet light, heat, humidity, and oxygen can lead to aging phenomena such as photooxidation and thermo-oxidative degradation. Traditional anti-aging modified plastics rely primarily on single or simply compounded light stabilizers, antioxidants, and UV absorbers, which pose challenges in achieving synergistic effects and separating flame retardant and antimicrobial functions. Therefore, avoiding this issue is crucial. For example, patent CN119039703A discloses an antimicrobial, high-toughness PP plastic and its preparation method. The antimicrobial, high-toughness PP plastic comprises the following components: polypropylene, a styrene-maleic anhydride copolymer, a composite antimicrobial agent, an antioxidant, a light stabilizer, a heat stabilizer, an initiator, and a solvent. This antimicrobial, high-toughness PP plastic exhibits enhanced antimicrobial properties, but its anti-aging and flame retardant properties require improvement. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the deficiencies of the prior art, the present invention provides an anti-aging modified plastic and a preparation method thereof, which has good anti-aging, flame retardant and antibacterial effects.

[0005] (2) Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: an anti-aging modified plastic and a preparation method thereof, comprising the following components by weight: 55-80 parts by weight of low-density polyethylene, 15-25 parts by weight of maleic anhydride grafted polyethylene, 0.2-0.3 parts by weight of antioxidant 168, 0.5-0.6 parts by weight of calcium stearate, 2-5 parts by weight of calcium carbonate, 0.6-1 parts by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 3-6 parts by weight of quaternary phosphonium salt modified chitosan, and 3-4 parts by weight of modified magnolol.

[0007] Furthermore, the preparation method of the quaternary phosphonium salt modified chitosan is as follows: dissolving chitosan in 80-90 mL of 1.6% acetic acid solution, stirring to dissolve, adding 1-hydroxybenzotriazole initiator to the solution and reacting for 20-30 minutes, then adding (3-carboxypropyl)triphenylphosphonium bromide to the solution, passing nitrogen protection, heating to 70-76° C. and reacting for 8-15 hours, and after the reaction is completed, dialyzing and freeze-drying to obtain the quaternary phosphonium salt modified chitosan;

[0008] Furthermore, the mass ratio of the chitosan, 1-hydroxybenzotriazole initiator, and (3-carboxypropyl)triphenylphosphonium bromide is 2.11-2.24 g: 0.02-0.03 g: 4.14-4.35 g.

[0009] Furthermore, the preparation method of the modified magnolol is:

[0010] S1. Under nitrogen gas protection, magnolol and 3-mercaptopropionic acid were added to 10-15 mL of dichloro solvent and stirred evenly. Benzoin dimethyl ether was then added and reacted at 30-35°C for 2-4 hours. The solution was irradiated with ultraviolet light (λ = 352 nm, 40 W). After the reaction was completed, the product was purified by column chromatography to obtain a carboxylated intermediate;

[0011] S2. The carboxylated intermediate and N-methyldiethanolamine were added to N,N-dimethylformamide solvent, stirred and mixed, and p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 75-80 ° C. After completion, the reaction was distilled under reduced pressure, washed and dried to obtain intermediate 2;

[0012] S3. Dissolve intermediate 2 and 1,3-propane sultone in acetone solvent, then dropwise add 3-5 mL of 6% sodium hydroxide solution, heat and react for 6-7 hours. After the reaction, concentrate under reduced pressure to remove the solvent, wash, and dry to obtain modified magnolol.

[0013] Furthermore, the molar ratio of magnolol, 3-mercaptopropionic acid, and benzoin dimethyl ether in S1 is 1.23-1.25 mmol: 2.24-2.5 mmol: 0.012-0.014 mmol.

[0014] Furthermore, the usage ratio of N,N-dimethylformamide solvent, carboxylation intermediate, N-methyldiethanolamine, and p-toluenesulfonic acid catalyst in S2 is 30-40 mL: 1.2-1.4 mmol: 1-1.5 mmol: 0.02-0.03 mmol.

[0015] Furthermore, the reaction time in S2 is 6-8 hours.

[0016] Furthermore, the amount of intermediate 2, 1,3-propane sultone, and acetone in S3 is 1 mmol: 1.12-1.15 mmol: 20-30 mL.

[0017] Furthermore, the reaction temperature in S3 is 80-85°C.

[0018] Furthermore, the preparation method of the anti-aging modified plastic is: low-density polyethylene, maleic anhydride grafted polyethylene, antioxidant 168, calcium stearate, calcium carbonate, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, quaternary phosphonium salt modified chitosan, and modified magnolol are placed in a high-speed mixer and mixed evenly, extruded into granules in a twin-screw extruder, the blending temperature is 190-195°C, the extrusion temperature is 170-180°C, dried, and injection molded by an injection molding machine to obtain the anti-aging modified plastic.

[0019] (3) Beneficial technical effects

[0020] The invention prepares an anti-aging modified plastic by placing low-density polyethylene, maleic anhydride grafted polyethylene, antioxidant 168, calcium stearate, calcium carbonate, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, quaternary phosphonium salt modified chitosan and modified magnolol in a high-speed mixer and mixing them uniformly, extruding and granulating them in a twin-screw extruder, extruding, drying and injection molding them by an injection molding machine.

[0021] Quaternary phosphonium salt-modified chitosan (core) encapsulates 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole (shell), forming a light-shielding synergistic layer with excellent UV absorption. The phenolic hydroxyl groups in the modified magnolol also have good UV absorption, and the two together improve the plastic's anti-aging effect. Modified magnolol introduces sulfonic acid groups through a propane sultone ring-opening reaction, giving the material pH responsiveness and releasing active oxygen in a humid environment, inhibiting mold growth. The quaternary ammonium salt groups also have good antibacterial effects. The phosphorus element in the quaternary phosphonium salt-modified chitosan and the sulfur and nitrogen elements in the modified magnolol together form a flame retardant system, which has a good flame retardant effect. During the blending process, low-density polyethylene will entangle with the quaternary phosphonium salt-modified chitosan and modified magnolol, increasing their density and achieving a good stretching effect. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] (1) 2.11 g of chitosan was dissolved in 80 mL of 1.6% acetic acid solution, stirred and dissolved, 0.02 g of 1-hydroxybenzotriazole initiator was added thereto and reacted for 20 min, and then 4.14 g of (3-carboxypropyl)triphenylphosphonium bromide was added thereto, nitrogen was passed through, and the temperature was raised to 70°C for reaction for 8 h. After the reaction was completed, the chitosan was dialyzed and freeze-dried to obtain quaternary phosphonium salt-modified chitosan;

[0025] (2) Under nitrogen protection, 1.23 mmol of magnolol and 2.24 mmol of 3-mercaptopropionic acid were added to 10 mL of dichloro solvent and stirred evenly. Then, 0.012 mmol of benzoin dimethyl ether was added and the mixture was reacted at 30°C for 2 h. The solution was irradiated with ultraviolet light (λ = 352 nm, 40 W). After the reaction was completed, the product was purified by chromatography to obtain a carboxylation intermediate.

[0026] (3) Add 1.2 mmol of the carboxylated intermediate and 1 mmol of N-methyldiethanolamine to 30 mL of N,N-dimethylformamide solvent, stir and mix, then add 0.02 mmol of p-toluenesulfonic acid catalyst, react at 75 °C for 6 h, and then distill under reduced pressure, wash and dry to obtain intermediate 2;

[0027] (4) 1 mmol of intermediate 2 and 1.12 mmol of 1,3-propane sultone were dissolved in 20 mL of acetone solvent, and then 3 mL of 6% sodium hydroxide solution was added dropwise. The temperature was raised to 80 °C and the reaction was carried out for 6-7 h. After the reaction, the solvent was removed by concentration under reduced pressure, washed, and dried to obtain modified magnolol.

[0028] (5) 55 parts by weight of low-density polyethylene, 15 parts by weight of maleic anhydride grafted polyethylene, 0.2 parts by weight of antioxidant 168, 0.5 parts by weight of calcium stearate, 2 parts by weight of calcium carbonate, 0.6 parts by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 3 parts by weight of quaternary phosphonium salt modified chitosan, and 3 parts by weight of modified magnolol were mixed uniformly in a high-speed mixer, extruded into granules in a twin-screw extruder at a blending temperature of 190°C and an extrusion temperature of 170°C, dried, and injection-molded by an injection molding machine to obtain an anti-aging modified plastic.

[0029] Example 2

[0030] (1) 2.24 g of chitosan was dissolved in 90 mL of 1.6% acetic acid solution, stirred and dissolved, 0.03 g of 1-hydroxybenzotriazole initiator was added thereto and reacted for 30 min, and then 4.35 g of (3-carboxypropyl)triphenylphosphonium bromide was added thereto, nitrogen was passed through, and the temperature was raised to 76 ° C for 15 h. After the reaction was completed, the chitosan was dialyzed and freeze-dried to obtain quaternary phosphonium salt modified chitosan;

[0031] (2) Under nitrogen protection, 1.25 mmol of magnolol and 2.5 mmol of 3-mercaptopropionic acid were added to 15 mL of dichloro solvent, stirred evenly, and then 0.014 mmol of benzoin dimethyl ether was added. The mixture was reacted at 35°C for 4 h. The solution was irradiated with ultraviolet light (λ = 352 nm, 40 W). After the reaction was completed, the product was purified by chromatography to obtain a carboxylation intermediate.

[0032] (3) 1.4 mmol of the carboxylated intermediate and 1.5 mmol of N-methyldiethanolamine were added to 40 mL of N,N-dimethylformamide solvent, stirred and mixed, and 0.03 mmol of p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 80°C for 8 h. After the reaction, the mixture was distilled under reduced pressure, washed, and dried to obtain intermediate 2;

[0033] (4) 1 mmol of intermediate 2 and 1.15 mmol of 1,3-propane sultone were dissolved in 30 mL of acetone solvent, and then 5 mL of 6% sodium hydroxide solution was added dropwise. The temperature was raised to 85 °C and the reaction was carried out for 7 h. After the reaction, the solvent was removed by concentration under reduced pressure, washed, and dried to obtain modified magnolol.

[0034] (5) 80 parts by weight of low-density polyethylene, 25 parts by weight of maleic anhydride grafted polyethylene, 0.3 parts by weight of antioxidant 168, 0.6 parts by weight of calcium stearate, 5 parts by weight of calcium carbonate, 1 part by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 6 parts by weight of quaternary phosphonium salt modified chitosan, and 4 parts by weight of modified magnolol were mixed uniformly in a high-speed mixer, extruded into granules in a twin-screw extruder at a blending temperature of 195°C and an extrusion temperature of 180°C, dried, and injection-molded by an injection molding machine to obtain an anti-aging modified plastic.

[0035] Example 3

[0036] (1) 2.18 g of chitosan was dissolved in 85 mL of 1.6% acetic acid solution, stirred and dissolved, 0.02 g of 1-hydroxybenzotriazole initiator was added thereto and reacted for 25 min, and then 4.25 g of (3-carboxypropyl)triphenylphosphonium bromide was added thereto, nitrogen was passed through, and the temperature was raised to 73 ° C for 12 h. After the reaction was completed, the chitosan was dialyzed and freeze-dried to obtain quaternary phosphonium salt modified chitosan;

[0037] (2) Under nitrogen protection, 1.24 mmol of magnolol and 2.36 mmol of 3-mercaptopropionic acid were added to 12 mL of dichloro solvent and stirred evenly. Then, 0.013 mmol of benzoin dimethyl ether was added and the mixture was reacted at 33°C for 3 h. The solution was irradiated with ultraviolet light (λ = 352 nm, 40 W). After the reaction was completed, the product was purified by chromatography to obtain a carboxylation intermediate.

[0038] (3) 1.3 mmol of the carboxylated intermediate and 1.2 mmol of N-methyldiethanolamine were added to 35 mL of N,N-dimethylformamide solvent, stirred and mixed, and 0.02 mmol of p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 78°C for 7 h. After the reaction, the mixture was distilled under reduced pressure, washed, and dried to obtain intermediate 2;

[0039] (4) 1 mmol of intermediate 2 and 1.13 mmol of 1,3-propane sultone were dissolved in 25 mL of acetone solvent, and then 4 mL of 6% sodium hydroxide solution was added dropwise. The temperature was raised to 82 °C and the reaction was carried out for 6 h. After the reaction, the solvent was removed by concentration under reduced pressure, washed, and dried to obtain modified magnolol.

[0040] (5) 65 parts by weight of low-density polyethylene, 20 parts by weight of maleic anhydride grafted polyethylene, 0.2 parts by weight of antioxidant 168, 0.5 parts by weight of calcium stearate, 3 parts by weight of calcium carbonate, 0.8 parts by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 4 parts by weight of quaternary phosphonium salt modified chitosan, and 3 parts by weight of modified magnolol were mixed uniformly in a high-speed mixer, extruded into granules in a twin-screw extruder at a blending temperature of 192°C and an extrusion temperature of 175°C, dried, and injection-molded by an injection molding machine to obtain an anti-aging modified plastic.

[0041] Example 4

[0042] (1) 2.15 g of chitosan was dissolved in 80 mL of 1.6% acetic acid solution, stirred and dissolved, 0.03 g of 1-hydroxybenzotriazole initiator was added thereto and reacted for 25 min, and then 4.2 g of (3-carboxypropyl)triphenylphosphonium bromide was added thereto, nitrogen was passed through, and the temperature was raised to 70° C. for reaction for 10 h. After the reaction was completed, the chitosan was dialyzed and freeze-dried to obtain quaternary phosphonium salt-modified chitosan;

[0043] (2) Under nitrogen protection, 1.23 mmol of magnolol and 2.3 mmol of 3-mercaptopropionic acid were added to 10 mL of dichloro solvent and stirred evenly. Then, 0.012 mmol of benzoin dimethyl ether was added and the mixture was reacted at 30°C for 3 h. The solution was irradiated with ultraviolet light (λ = 352 nm, 40 W). After the reaction was completed, the product was purified by chromatography to obtain a carboxylation intermediate.

[0044] (3) 1.2 mmol of the carboxylated intermediate and 1.3 mmol of N-methyldiethanolamine were added to 35 mL of N,N-dimethylformamide solvent, stirred and mixed, and 0.02 mmol of p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 75°C for 7 h. After the reaction, the mixture was distilled under reduced pressure, washed, and dried to obtain intermediate 2;

[0045] (4) 1 mmol of intermediate 2 and 1.12 mmol of 1,3-propane sultone were dissolved in 25 mL of acetone solvent, and then 3 mL of 6% sodium hydroxide solution was added dropwise. The temperature was raised to 80 °C and the reaction was carried out for 6 h. After the reaction, the solvent was removed by concentration under reduced pressure, washed, and dried to obtain modified magnolol.

[0046] (5) 60 parts by weight of low-density polyethylene, 18 parts by weight of maleic anhydride grafted polyethylene, 0.2 parts by weight of antioxidant 168, 0.5 parts by weight of calcium stearate, 3 parts by weight of calcium carbonate, 0.6 parts by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 4 parts by weight of quaternary phosphonium salt modified chitosan, and 3 parts by weight of modified magnolol were mixed uniformly in a high-speed mixer, extruded into granules in a twin-screw extruder at a blending temperature of 190° C. and an extrusion temperature of 175° C., dried, and injection-molded by an injection molding machine to obtain an anti-aging modified plastic.

[0047] Example 5

[0048] (1) 2.2 g of chitosan was dissolved in 90 mL of 1.6% acetic acid solution, stirred and dissolved, 0.03 g of 1-hydroxybenzotriazole initiator was added thereto and reacted for 30 min, and then 4.3 g of (3-carboxypropyl)triphenylphosphonium bromide was added thereto, nitrogen was passed through, and the temperature was raised to 75° C. and reacted for 15 h. After the reaction was completed, the chitosan was dialyzed and freeze-dried to obtain quaternary phosphonium salt-modified chitosan;

[0049] (2) Under nitrogen protection, 1.25 mmol of magnolol and 2.28 mmol of 3-mercaptopropionic acid were added to 15 mL of dichloro solvent and stirred evenly. Then, 0.014 mmol of benzoin dimethyl ether was added and the mixture was reacted at 35°C for 4 h. The solution was irradiated with ultraviolet light (λ = 352 nm, 40 W). After the reaction was completed, the product was purified by chromatography to obtain a carboxylation intermediate.

[0050] (3) 1.3 mmol of the carboxylated intermediate and 1.5 mmol of N-methyldiethanolamine were added to 40 mL of N,N-dimethylformamide solvent, stirred and mixed, and 0.03 mmol of p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 78°C for 8 h. After the reaction, the mixture was distilled under reduced pressure, washed, and dried to obtain intermediate 2;

[0051] (4) 1 mmol of intermediate 2 and 1.15 mmol of 1,3-propane sultone were dissolved in 30 mL of acetone solvent, and then 4 mL of 6% sodium hydroxide solution was added dropwise. The temperature was raised to 85 °C and the reaction was carried out for 7 h. After the reaction, the solvent was removed by concentration under reduced pressure, washed, and dried to obtain modified magnolol.

[0052] (5) 70 parts by weight of low-density polyethylene, 25 parts by weight of maleic anhydride grafted polyethylene, 0.2 parts by weight of antioxidant 168, 0.5 parts by weight of calcium stearate, 4 parts by weight of calcium carbonate, 1 part by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 5 parts by weight of quaternary phosphonium salt modified chitosan, and 4 parts by weight of modified magnolol were mixed uniformly in a high-speed mixer, extruded into granules in a twin-screw extruder at a blending temperature of 195°C and an extrusion temperature of 180°C, dried, and injection-molded by an injection molding machine to obtain an anti-aging modified plastic.

[0053] Comparative Example 1

[0054] Compared with Example 5, this comparative example is different in that a carboxylated intermediate is used instead of modified magnolol.

[0055] Comparative Example 2

[0056] Compared with Example 5, this comparative example is different in that intermediate 2 is used instead of modified magnolol.

[0057] Comparative Example 3

[0058] Compared with Example 5, this comparative example differs in that chitosan is used instead of quaternary phosphonium salt-modified chitosan.

[0059] Performance testing:

[0060] The performance of the anti-aging modified plastics prepared in Examples 1-5 and Comparative Examples 1-3 was tested.

[0061] (1) Antibacterial performance testing was performed according to GB / T 31402-2015, "Test Method for Antibacterial Performance of Plastic Surfaces," using Escherichia coli AS1.90 and Staphylococcus aureus ACTT6538P. The test results are shown in Table 1.

[0062] Table 1: Antibacterial performance test

[0063]

[0064]

[0065] As can be seen from Table 1, the antibacterial rates of the anti-aging modified plastics prepared in Examples 1-5 against Escherichia coli and Staphylococcus aureus are greater than 99%, and they have better antibacterial effects than those in Comparative Examples 1-3.

[0066] (2) Flame retardancy test methods are as follows: oxygen index of the material is tested using an oxygen index meter, and the combustion grade of the material is tested using a horizontal and vertical combustion tester. The test results are shown in Table 2.

[0067] Table 2: Flame retardant performance test

[0068] Group Oxygen index (%) UL-94 Example 1 37.2 V-0 Example 2 38.8 V-0 Example 3 38.1 V-0 Example 4 37.6 V-0 Example 5 37.8 V-0 Comparative Example 1 21.5 V-1 Comparative Example 2 22.3 V-1 Comparative Example 3 21.7 V-1

[0069] It can be seen from Table 2 that the anti-aging modified plastics prepared in Examples 1-5 have better flame retardant effects than those in Comparative Examples 1-3.

[0070] (3) Aging resistance test: Referring to the standard GB / T3512-2001 for accelerated aging and heat resistance test of rubber in hot air, the test samples were cut into dumbbell-shaped specimens. After the aging box was adjusted to 120°C, the test specimens were placed in the aging box for testing. After 72 hours, the specimens were removed and the aged specimens were placed in the air for environmental conditioning for 48 hours. The tensile strength of the plastic before and after aging was tested using an electronic universal testing machine (Zwick, Germany). The test results are shown in Table 3.

[0071] Table 3: Aging resistance and tensile properties test

[0072]

[0073] As can be seen from Table 3, Examples 1-5 of the present invention have better tensile resistance and aging resistance than Comparative Examples 1-3.

[0074] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0076] Those skilled in the art should understand that the above descriptions are only some specific embodiments of the present invention, rather than all embodiments.

Claims

1. An anti-aging modified plastic, characterized in that: The invention comprises the following components by weight: 55-80 parts by weight of low-density polyethylene, 15-25 parts by weight of maleic anhydride grafted polyethylene, 0.2-0.3 parts by weight of antioxidant 168, 0.5-0.6 parts by weight of calcium stearate, 2-5 parts by weight of calcium carbonate, 0.6-1 parts by weight of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, 3-6 parts by weight of quaternary phosphonium salt modified chitosan, and 3-4 parts by weight of modified magnolol.

2. The anti-aging modified plastic according to claim 1, characterized in that: The preparation method of the quaternary phosphonium salt modified chitosan comprises: dissolving chitosan in 80-90 mL of 1.6% acetic acid solution, stirring to dissolve, adding 1-hydroxybenzotriazole initiator to the solution and reacting for 20-30 minutes, then adding (3-carboxypropyl)triphenylphosphonium bromide to the solution, passing nitrogen protection, heating to 70-76° C. and reacting for 8-15 hours, dialyzing and freeze-drying after completion of the reaction to obtain the quaternary phosphonium salt modified chitosan.

3. The anti-aging modified plastic according to claim 2, characterized in that: The mass ratio of the chitosan, 1-hydroxybenzotriazole initiator and (3-carboxypropyl)triphenylphosphonium bromide is 2.11-2.24 g: 0.02-0.03 g: 4.14-4.35 g.

4. The anti-aging modified plastic according to claim 1, characterized in that: The preparation method of the modified magnolol is: S1. Under nitrogen, add magnolol and 3-mercaptopropionic acid to 10-15 mL of dichloromethane. Stir thoroughly, then add benzoin dimethyl ether. Incubate at 30-35°C for 2-4 hours. Irradiate the solution with ultraviolet light (λ = 352 nm, 40 W). After the reaction is complete, purify the product by column chromatography to obtain a carboxylation intermediate. S2. The carboxylated intermediate and N-methyldiethanolamine were added to N,N-dimethylformamide solvent, stirred and mixed, and p-toluenesulfonic acid catalyst was added thereto. The reaction was carried out at 75-80 ° C. After completion, the reaction was distilled under reduced pressure, washed and dried to obtain intermediate 2; S3. Dissolve intermediate 2 and 1,3-propane sultone in acetone solvent, then add 3-5 mL of 6% sodium hydroxide solution dropwise, heat and react for 6-7 hours, concentrate under reduced pressure to remove the solvent, wash, and dry to obtain modified magnolol.

5. The anti-aging modified plastic according to claim 4, characterized in that: The molar ratio of magnolol, 3-mercaptopropionic acid, and benzoin dimethyl ether in S1 is 1.23-1.25 mmol: 2.24-2.5 mmol: 0.012-0.014 mmol.

6. The anti-aging modified plastic according to claim 4, characterized in that: The usage ratio of N,N-dimethylformamide solvent, carboxylation intermediate, N-methyldiethanolamine and p-toluenesulfonic acid catalyst in S2 is 30-40 mL: 1.2-1.4 mmol: 1-1.5 mmol: 0.02-0.03 mmol.

7. The anti-aging modified plastic according to claim 4, characterized in that: The reaction time in S2 is 6-8h.

8. The anti-aging modified plastic according to claim 4, characterized in that: The amounts of intermediate 2, 1,3-propane sultone, and acetone used in S3 are 1 mmol: 1.12-1.15 mmol: 20-30 mL.

9. The anti-aging modified plastic according to claim 4, characterized in that: The reaction temperature in S3 is 80-85°C.

10. A method for preparing the anti-aging modified plastic according to any one of claims 1 to 9, characterized in that: The preparation method of the anti-aging modified plastic comprises the following steps: placing low-density polyethylene, maleic anhydride grafted polyethylene, antioxidant 168, calcium stearate, calcium carbonate, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-benzotriazole, quaternary phosphonium salt modified chitosan, and modified magnolol in a high-speed mixer and mixing them uniformly; extruding and granulating the mixture in a twin-screw extruder at a blending temperature of 190-195° C. and an extrusion temperature of 170-180° C.; drying; and injection molding the mixture using an injection molding machine to obtain the anti-aging modified plastic.

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