Antibacterial modified plastic and preparation method thereof

Abstract

The invention relates to the technical field of high polymer material modification, and discloses an antibacterial modified plastic and a preparation method thereof.The preparation method comprises the following steps that polypropylene, phosphorus-modified imidazoline, modified boric acid ester, an antioxidant 1010, plasticizer polyethylene glycol and talcum powder are placed in a high-speed mixer to be evenly mixed, extrusion granulation is conducted in a double-screw extruder, and the antibacterial modified plastic is obtained. The blending temperature is 180-190 DEG C, and the extrusion temperature is 170-180 DEG C, drying, and carrying out injection molding by an injection molding machine to obtain the antibacterial modified plastic. The antibacterial modified plastic disclosed by the invention has relatively good antibacterial, flame-retardant and tensile effects.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material modification, in particular to an antibacterial modified plastic and a preparation method thereof. Background Art

[0002] Plastics are one of the greatest material innovations of the 20th century. However, due to performance limitations and environmental concerns, plastic modification has become a core area of ​​materials science. Antimicrobial plastics are modified materials that inhibit or kill microorganisms (such as bacteria, fungi, and viruses) by adding antimicrobial agents or employing specialized surface treatment techniques. Their core goal is to reduce microbial growth on plastic surfaces, prevent cross-contamination, and extend the lifespan of products. This is particularly important in high-hygiene applications such as healthcare, food, and home appliances. As people's demands for hygiene and safety increase, traditional plastics lack antimicrobial properties, making preventing this phenomenon a key challenge. For example, patent CN102617912A discloses a shielding flame-retardant plastic comprising the following components, by weight: 100 parts plastic base material, 5-25 parts doped polyaniline, 0.5-3 parts curing agent, 10-30 parts polyphosphatidic acid, 0.5-3.5 parts cross-linking agent, 1-6 parts lubricant, 5-15 parts flame retardant, 0.5-1.5 parts antioxidant, 0.1-1 part stabilizer, and 0.2-1 part metal deactivator. This shielding flame-retardant plastic has low manufacturing costs, high shielding properties, and good safety, but its antibacterial properties need to be improved. Summary of the Invention

[0003] (1) Technical problems solved

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

[0005] (2) Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: an antibacterial modified plastic comprising the following components by weight: 60-75 parts by weight of polypropylene, 2-4 parts by weight of phosphorus-modified imidazoline, 3-5 parts by weight of modified borate, 0.2-0.3 parts by weight of antioxidant 1010, 0.1-0.3 parts by weight of plasticizer polyethylene glycol, and 1-2 parts by weight of talc.

[0007] Furthermore, the preparation method of the phosphorus-modified imidazoline is:

[0008] S1. Add oleic acid and diethylenetriamine to a xylene solvent, stir evenly at room temperature, maintain at 150-160 ° C for 2-2.5 hours, and then carry out a cyclization reaction at 200-220 ° C for 1.5-2 hours. After the reaction is completed, cool and dry to obtain intermediate 1;

[0009] S2. Add 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 4-bromomethylbenzyl alcohol, and triethylamine to an acetonitrile solvent, react at 10-15°C for 30-60 minutes, then at 65-75°C for 4-6 hours. After the reaction, concentrate, wash, and dry to obtain intermediate 2;

[0010] S3. Add intermediate 1 and intermediate 2 to N,N-dimethylformamide solvent, stir and mix, continue to add triethylamine catalyst, react at 60-80°C, and after the reaction is completed, distill under reduced pressure and purify to obtain phosphorus-modified imidazoline.

[0011] In the above reaction process, oleic acid and diethylenetriamine are subjected to a cyclization reaction to introduce a tertiary amine and an amino group, thereby obtaining intermediate 1; the chlorine in 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide reacts with the hydroxyl group in 4-bromomethylbenzyl alcohol to introduce a bromine group, thereby obtaining intermediate 2; the tertiary amine in intermediate 1 and the bromine in intermediate 2 are subjected to a quaternization reaction to obtain a phosphorus-modified imidazoline.

[0012] Furthermore, the usage ratio of xylene, oleic acid and diethylenetriamine in S1 is 20-40 mL: 4-4.2 g: 2.1-2.3 g.

[0013] Furthermore, the stirring time in S1 is 20-30 min.

[0014] Furthermore, the usage ratio of acetonitrile, 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 4-bromomethylbenzyl alcohol, and triethylamine in S2 is 20-35 mL: 2-2.2 g: 3.1-3.4 g: 0.02-0.03 g.

[0015] Furthermore, the usage ratio of N,N-dimethylformamide solvent, intermediate 1, intermediate 2, and triethylamine in S3 is 25-40 mL: 3.6-3.8 g: 1.5-1.8 g: 0.01-0.02 g.

[0016] Furthermore, the reaction time in S3 is 6-8 hours.

[0017] Furthermore, the method for modifying the borate ester is as follows: dissolving 2,6-dihydroxy-3,7-dibromonaphthalene and diboronic acid pinacol ester in a 1,4-dioxane solvent, adding [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride catalyst and sodium carbonate thereto, heating to the reaction temperature under a nitrogen atmosphere and reacting for 1.5-2.5 hours. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the modified borate ester.

[0018] Furthermore, the usage ratio of the 2,6-dihydroxy-3,7-dibromonaphthalene, pinacol diboronate, 1,4-dioxane, [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride, and sodium carbonate is 3.5-3.9 g: 2.8-3.2 g: 80-90 mL: 0.3-0.4 g: 4.4.2 g.

[0019] Furthermore, the preparation method of the antibacterial modified plastic is characterized in that the preparation method of the antibacterial modified plastic is: polypropylene, phosphorus-modified imidazoline, modified borate, antioxidant 1010, plasticizer polyethylene glycol, and talc are placed in a high-speed mixer and mixed evenly, extruded into granules in a twin-screw extruder, the blending temperature is 180-190°C, the extrusion temperature is 170-180°C, dried, and injection molded by an injection molding machine to obtain the antibacterial modified plastic.

[0020] (3) Beneficial technical effects

[0021] The invention obtains the antibacterial modified plastic by placing polypropylene, phosphorus-modified imidazoline, modified borate, antioxidant 1010, plasticizer polyethylene glycol and talcum powder in a high-speed mixer and mixing them uniformly, extruding and granulating them in a twin-screw extruder, drying them, and injection molding them by an injection molding machine.

[0022] During the co-extrusion process, the chains of the phosphorus-modified imidazoline and modified borate ester become entangled with polypropylene, creating a tighter connection and forming a cross-linked network, which enhances its tensile properties. The imidazole and quaternary ammonium salt groups in the phosphorus-modified imidazoline exhibit excellent antimicrobial properties. The phosphorus and nitrogen in the phosphorus-modified imidazoline and the boron in the modified borate ester together form a flame-retardant system, resulting in a strong flame-retardant effect. Furthermore, the reaction of intermediate 2 with intermediate 1 increases the degree of substitution of the imidazoline, further enhancing its antimicrobial efficacy. DETAILED DESCRIPTION

[0023] 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.

[0024] In order to better understand the above technical solution, the above technical solution will be described in detail with reference to specific embodiments below.

[0025] Example 1

[0026] (1) Add 4 g of oleic acid and 2.1 g of diethylenetriamine to 20 mL of xylene solvent, stir at room temperature for 20 min, maintain at 150°C for 2 h, and then carry out cyclization reaction at 200°C for 1.5 h. After the reaction is completed, cool and dry to obtain intermediate 1;

[0027] (2) Add 2 g of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 3.1 g of 4-bromomethylbenzyl alcohol, and 0.02 g of triethylamine to 20 mL of acetonitrile solvent, react at 10 ° C for 30 min, then at 65 ° C for 4 h. After the reaction is completed, concentrate, wash and dry to obtain intermediate 2;

[0028] (3) To 25 mL of N,N-dimethylformamide solvent, 3.6-3.8 g of intermediate 1 and 1.5 g of intermediate 2 were added and stirred. 0.01 g of triethylamine catalyst was added and reacted at 60 °C for 6 h. After the reaction was completed, the mixture was distilled under reduced pressure and purified to obtain phosphorus-modified imidazoline.

[0029] (4) 3.5 g of 2,6-dihydroxy-3,7-dibromonaphthalene and 2.8 g of pinacol diboron were dissolved in 80 mL of 1,4-dioxane solvent, 0.3 g of [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride catalyst and 4 g of sodium carbonate were added thereto, and the temperature was raised to the reaction temperature under a nitrogen atmosphere and the reaction was carried out for 1.5 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a modified borate ester.

[0030] (5) 60 parts by weight of polypropylene, 2 parts by weight of phosphorus-modified imidazoline, 3 parts by weight of modified borate, 0.2 parts by weight of antioxidant 1010, 0.1 parts by weight of plasticizer polyethylene glycol, and 1 part by weight of talc are placed in a high-speed mixer and mixed evenly, and then extruded into granules in a twin-screw extruder at a blending temperature of 180°C and an extrusion temperature of 170°C. The mixture is dried and injection-molded by an injection molding machine to obtain an antibacterial modified plastic.

[0031] Example 2

[0032] (1) Add 4.2 g of oleic acid and 2.3 g of diethylenetriamine to 40 mL of xylene solvent, stir at room temperature for 30 min, maintain at 160°C for 2.5 h, and then carry out cyclization reaction at 220°C for 2 h. After the reaction is completed, cool and dry to obtain intermediate 1;

[0033] (2) Add 2.2 g of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 3.4 g of 4-bromomethylbenzyl alcohol, and 0.03 g of triethylamine to 35 mL of acetonitrile solvent, react at 15 ° C for 60 min, then at 75 ° C for 6 h. After the reaction is completed, concentrate, wash and dry to obtain intermediate 2;

[0034] (3) Add 3.8 g of intermediate 1 and 1.8 g of intermediate 2 to 40 mL of N,N-dimethylformamide solvent, stir and mix, continue to add 0.02 g of triethylamine catalyst, react at 80 ° C for 8 h, and after the reaction is completed, distill under reduced pressure and purify to obtain phosphorus-modified imidazoline.

[0035] (4) 3.9 g of 2,6-dihydroxy-3,7-dibromonaphthalene and 3.2 g of pinacol diboron were dissolved in 90 mL of 1,4-dioxane solvent, 0.4 g of [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride catalyst and 4.2 g of sodium carbonate were added thereto, and the temperature was raised to the reaction temperature under a nitrogen atmosphere and the reaction was carried out for 2.5 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a modified borate ester.

[0036] (5) 75 parts by weight of polypropylene, 4 parts by weight of phosphorus-modified imidazoline, 5 parts by weight of modified borate, 0.3 parts by weight of antioxidant 1010, 0.3 parts by weight of plasticizer polyethylene glycol, and 2 parts by weight of talc are placed in a high-speed mixer and mixed evenly, extruded into granules in a twin-screw extruder at a blending temperature of 190°C and an extrusion temperature of 180°C, dried, and injection-molded by an injection molding machine to obtain an antibacterial modified plastic.

[0037] Example 3

[0038] (1) Add 4.1 g of oleic acid and 2.2 g of diethylenetriamine to 30 mL of xylene solvent, stir at room temperature for 25 min, maintain at 155°C for 2.2 h, and then carry out cyclization reaction at 210°C for 1.5 h. After the reaction is completed, cool and dry to obtain intermediate 1;

[0039] (2) To 30 mL of acetonitrile solvent, 2.1 g of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 3.3 g of 4-bromomethylbenzyl alcohol, and 0.02 g of triethylamine were added, and the mixture was reacted at 12 °C for 45 min and then at 70 °C for 5 h. After the reaction, the mixture was concentrated, washed, and dried to obtain intermediate 2;

[0040] (3) To 35 mL of N,N-dimethylformamide solvent, 3.7 g of intermediate 1 and 1.6 g of intermediate 2 were added and stirred. 0.02 g of triethylamine catalyst was added and the mixture was reacted at 70 °C for 7 h. After the reaction was completed, the mixture was distilled under reduced pressure and purified to obtain phosphorus-modified imidazoline.

[0041] (4) 3.7 g of 2,6-dihydroxy-3,7-dibromonaphthalene and 3 g of pinacol diboron were dissolved in 85 mL of 1,4-dioxane solvent, 0.3 g of [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride catalyst and 4.1 g of sodium carbonate were added thereto, and the temperature was raised to the reaction temperature under a nitrogen atmosphere for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a modified borate ester.

[0042] (5) 65 parts by weight of polypropylene, 3 parts by weight of phosphorus-modified imidazoline, 4 parts by weight of modified borate, 0.2 parts by weight of antioxidant 1010, 0.2 parts by weight of plasticizer polyethylene glycol, and 1 part by weight of talc are placed in a high-speed mixer and mixed evenly, and then extruded into granules in a twin-screw extruder at a blending temperature of 185°C and an extrusion temperature of 175°C. The mixture is dried and injection-molded by an injection molding machine to obtain an antibacterial modified plastic.

[0043] Example 4

[0044] (1) Add 4 g of oleic acid and 2.1 g of diethylenetriamine to 28 mL of xylene solvent, stir at room temperature for 25 min, maintain at 155°C for 2 h, and then carry out cyclization reaction at 200°C for 1.5 h. After the reaction is completed, cool and dry to obtain intermediate 1;

[0045] (2) Add 2 g of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 3.2 g of 4-bromomethylbenzyl alcohol, and 0.02 g of triethylamine to 25 mL of acetonitrile solvent, react at 10 ° C for 40 min, then at 65 ° C for 5 h. After the reaction is completed, concentrate, wash and dry to obtain intermediate 2;

[0046] (3) Add 3.6 g of intermediate 1 and 1.6 g of intermediate 2 to 30 mL of N,N-dimethylformamide solvent, stir and mix, continue to add 0.01 g of triethylamine catalyst, react at 70 ° C for 6 h, and after the reaction is completed, distill under reduced pressure and purify to obtain phosphorus-modified imidazoline.

[0047] (4) 3.6 g of 2,6-dihydroxy-3,7-dibromonaphthalene and 3 g of pinacol diboron were dissolved in 80 mL of 1,4-dioxane solvent, 0.3 g of [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride catalyst and 4 g of sodium carbonate were added thereto, and the temperature was raised to the reaction temperature under a nitrogen atmosphere for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a modified borate ester.

[0048] (5) 65 parts by weight of polypropylene, 2 parts by weight of phosphorus-modified imidazoline, 4 parts by weight of modified borate, 0.2 parts by weight of antioxidant 1010, 0.2 parts by weight of plasticizer polyethylene glycol, and 1 part by weight of talc are placed in a high-speed mixer and mixed evenly, and then extruded into granules in a twin-screw extruder at a blending temperature of 180°C and an extrusion temperature of 175°C. The mixture is dried and injection-molded by an injection molding machine to obtain an antibacterial modified plastic.

[0049] Example 5

[0050] (1) Add 4.2 g of oleic acid and 2.2 g of diethylenetriamine to 40 mL of xylene solvent, stir at room temperature for 30 min, maintain at 155°C for 2.5 h, and then carry out cyclization reaction at 220°C for 2 h. After the reaction is completed, cool and dry to obtain intermediate 1;

[0051] (2) To 35 mL of acetonitrile solvent, 2.1 g of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 3.3 g of 4-bromomethylbenzyl alcohol, and 0.03 g of triethylamine were added, and the mixture was reacted at 15 °C for 50 min and then at 75 °C for 6 h. After the reaction, the mixture was concentrated, washed, and dried to obtain intermediate 2;

[0052] (3) Add 3.8 g of intermediate 1 and 1.8 g of intermediate 2 to 35 mL of N,N-dimethylformamide solvent, stir and mix, continue to add 0.02 g of triethylamine catalyst, react at 80 ° C for 7 h, and after the reaction is completed, distill under reduced pressure and purify to obtain phosphorus-modified imidazoline.

[0053] (4) 3.7 g of 2,6-dihydroxy-3,7-dibromonaphthalene and 3.2 g of biboronic acid pinacol ester were dissolved in 90 mL of 1,4-dioxane solvent, 0.4 g of [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride catalyst and 4.2 g of sodium carbonate were added thereto, and the temperature was raised to the reaction temperature under a nitrogen atmosphere and the reaction was carried out for 2.5 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a modified borate ester.

[0054] (5) 75 parts by weight of polypropylene, 3 parts by weight of phosphorus-modified imidazoline, 5 parts by weight of modified borate, 0.3 parts by weight of antioxidant 1010, 0.2 parts by weight of plasticizer polyethylene glycol, and 2 parts by weight of talc are placed in a high-speed mixer and mixed evenly, and then extruded into granules in a twin-screw extruder at a blending temperature of 190°C and an extrusion temperature of 175°C. The mixture is dried and injection-molded by an injection molding machine to obtain an antibacterial modified plastic.

[0055] Comparative Example 1

[0056] This comparative example is different from Example 5 in that intermediate 1 is used instead of phosphorus-modified imidazoline.

[0057] Comparative Example 2

[0058] This comparative example is different from Example 5 in that intermediate 2 is used instead of phosphorus-modified imidazoline.

[0059] Comparative Example 3

[0060] This comparative example is different from Example 5 in that no modified borate is added.

[0061] Performance testing:

[0062] The antibacterial modified plastics prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to performance tests.

[0063] (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.

[0064] Table 1: Antibacterial performance test

[0065] Group Escherichia coli (%) Staphylococcus aureus (%) Example 1 99.2 99.3 Example 2 99.7 99.8 Example 3 99.5 99.4 Example 4 99.3 99.3 Example 5 99.5 99.6 Comparative Example 1 92.3 91.5 Comparative Example 2 95.1 94.6 Comparative Example 3 99.4 99.3

[0066] As can be seen from Table 1, the antibacterial modified plastics prepared in Examples 1-5 have an antibacterial rate of greater than 99% against Escherichia coli and Staphylococcus aureus, and have better antibacterial effects than Comparative Examples 1-2.

[0067] (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.

[0068] Table 2: Flame retardant performance test

[0069] Group Oxygen index (%) UL-94 Example 1 36.8 V-0 Example 2 38.2 V-0 Example 3 37.4 V-0 Example 4 37.1 V-0 Example 5 37.8 V-0 Comparative Example 1 20.6 V-1 Comparative Example 2 21.2 V-1 Comparative Example 3 22.9 V-1

[0070] It can be seen from Table 2 that the antibacterial modified plastics prepared in Examples 1-5 have better flame retardant effects than those in Comparative Examples 1-2.

[0071] (3) Mechanical properties were tested according to GB / T 1040-2006 at a tensile rate of 5 mm / min. The test results are shown in Table 3.

[0072] Table 3: Mechanical properties test

[0073] Group Tensile strength (MPa) Example 1 41.5 Example 2 43.2 Example 3 42.1 Example 4 41.6 Example 5 42.7 Comparative Example 1 34.5 Comparative Example 2 33.2 Comparative Example 3 35.9

[0074] It can be seen from Table 3 that the antibacterial modified plastics prepared in Examples 1-5 have better mechanical properties than those in Comparative Examples 1-2.

[0075] 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.

[0076] The above embodiments are intended only to illustrate the technical solutions of the present invention, and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some of the technical features thereof may be replaced with equivalents. Such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Those skilled in the art should understand that the above descriptions are merely some specific embodiments of the present invention, and are not intended to be exhaustive.

Claims

1. An antibacterial modified plastic, characterized in that: The invention comprises the following components by weight: 60-75 parts by weight of polypropylene, 2-4 parts by weight of phosphorus-modified imidazoline, 3-5 parts by weight of modified borate, 0.2-0.3 parts by weight of antioxidant 1010, 0.1-0.3 parts by weight of plasticizer polyethylene glycol, and 1-2 parts by weight of talc.

2. The antibacterial modified plastic according to claim 1, characterized in that: The preparation method of the phosphorus-modified imidazoline is: S1. Add oleic acid and diethylenetriamine to a xylene solvent, stir evenly at room temperature, maintain at 150-160 ° C for 2-2.5 hours, and then carry out a cyclization reaction at 200-220 ° C for 1.5-2 hours. After the reaction is completed, cool and dry to obtain intermediate 1; S2. Add 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 4-bromomethylbenzyl alcohol, and triethylamine to an acetonitrile solvent, react at 10-15°C for 30-60 minutes, then at 65-75°C for 4-6 hours. After the reaction, concentrate, wash, and dry to obtain intermediate 2; S3. Add intermediate 1 and intermediate 2 to N,N-dimethylformamide solvent, stir and mix, continue to add triethylamine catalyst, react at 60-80°C, and after the reaction is completed, distill under reduced pressure and purify to obtain phosphorus-modified imidazoline.

3. The antibacterial modified plastic according to claim 2, characterized in that: The usage ratio of xylene, oleic acid and diethylenetriamine in S1 is 20-40 mL: 4-4.2 g: 2.1-2.3 g.

4. The antibacterial modified plastic according to claim 2, characterized in that: The stirring time in S1 is 20-30 min.

5. The antibacterial modified plastic according to claim 2, characterized in that: The usage ratio of acetonitrile, 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 4-bromomethylbenzyl alcohol and triethylamine in S2 is 20-35 mL: 2-2.2 g: 3.1-3.4 g: 0.02-0.03 g.

6. The antibacterial modified plastic according to claim 2, characterized in that: The usage ratio of N,N-dimethylformamide solvent, intermediate 1, intermediate 2, and triethylamine in S3 is 25-40 mL: 3.6-3.8 g: 1.5-1.8 g: 0.01-0.02 g.

7. The antibacterial modified plastic according to claim 2, characterized in that: The reaction time in S3 is 6-8h.

8. The antibacterial modified plastic according to claim 1, characterized in that: The method for modifying the borate ester comprises: dissolving 2,6-dihydroxy-3,7-dibromonaphthalene and pinacol diboron in a 1,4-dioxane solvent, adding a [1,1-bis(diphenylphosphino)ferrocene]palladium dichloride catalyst and sodium carbonate thereto, heating the mixture to a reaction temperature under a nitrogen atmosphere, and reacting for 1.5-2.5 hours. After the reaction is completed, the solvent is removed by rotary evaporation to obtain the modified borate ester.

9. The antibacterial modified plastic according to claim 8, characterized in that: The usage ratio of the 2,6-dihydroxy-3,7-dibromonaphthalene, pinacol diboronate, 1,4-dioxane, [1,1-bis(diphenylphosphino)ferrocene] palladium dichloride, and sodium carbonate is 3.5-3.9 g: 2.8-3.2 g: 80-90 mL: 0.3-0.4 g: 4.4.2 g.

10. A method for preparing the antibacterial modified plastic according to any one of claims 1 to 8, characterized in that: The preparation method of the antibacterial modified plastic comprises the following steps: placing polypropylene, phosphorus-modified imidazoline, modified borate, antioxidant 1010, plasticizer polyethylene glycol, and talcum powder in a high-speed mixer and mixing them uniformly; extruding and granulating the mixture in a twin-screw extruder at a blending temperature of 180-190° C. and an extrusion temperature of 170-180° C.; drying the mixture; and injection molding the mixture using an injection molding machine to obtain the antibacterial modified plastic.