Polypropylene compounded plasticizing antibacterial starch composite material as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene compounded and plasticized antibacterial starch composite material as well as a preparation method and application thereof, belongs to the technical field of food preservation, and provides the polypropylene compounded and plasticized antibacterial starch composite material. Comprising the following raw materials: 70 to 200 parts of polypropylene, 20 to 60 parts of maleic anhydride grafted polyolefin elastomer, 6.633 to 19.71 parts of starch, 2.673 to 8.91 parts of glycerin, 0.02 to 3 parts of a bacteriostatic agent and 1 part of an antioxidant. The plasticized antibacterial starch and the maleic anhydride grafted polyolefin elastomer are compounded with the polypropylene, so that the mechanical property of the polypropylene material is improved, the broad-spectrum antibacterial property of the polypropylene material is realized, and the polypropylene compounded plasticized antibacterial starch composite material effectively reduces the food transportation loss and the quality safety problem; the problem of excess production value of common polypropylene is solved, and a new choice is provided for toughening modification and antibacterial functionalization of polypropylene.

Description

Technical Field

[0001] The present invention belongs to the technical field of food preservation, and particularly relates to a polypropylene compound plasticized antibacterial starch composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rise of new consumption patterns such as supermarket takeout and instant delivery, the performance requirements of meal boxes in the market have changed from single sealing performance to multi-functionalization. In the early days, traditional polypropylene injection molding technology was the mainstream for meal boxes. Although it had the advantages of large-scale production and low cost, the defects of high brittleness and insufficient impact resistance of the material led to frequent transportation breakages. At the same time, the polypropylene matrix lacked an active antibacterial function, and microorganisms were likely to grow in the sealed environment of food, forcing merchants to rely on low-temperature cold chain systems to delay spoilage. This not only increased operating costs but also restricted the promotion of prefabricated dishes in normal temperature circulation scenarios.

[0003] To extend the shelf life of food, early improvement schemes tried methods such as physical blending or surface coating. For example, adding inorganic antibacterial agents such as silver ions and zinc oxide to the polypropylene matrix could achieve long-term preservation through contact sterilization or ion release. However, the risk of their biological toxicity restricted their application in scenarios of direct contact with food, and the uneven dispersion of rigid particles led to further deterioration of the material toughness. The second technical route used organic synthetic preservatives (such as benzoates, sorbates, and dehydroacetic acid and its sodium salts), and improved the food preservation duration through blending modification. However, the thermal sensitivity of their molecular structure caused partial decomposition and failure during the high-temperature processing of polypropylene, not only reducing the antibacterial efficiency but also releasing harmful gases to pollute the production environment. To maintain the food preservation efficiency, it was often necessary to add excessive amounts of preservatives, which undoubtedly increased costs and significantly decreased the material toughness. The third technical route used natural antibacterial components represented by chitosan and plant polyphenols. Although they had the advantage of biocompatibility, their defects of poor thermal stability and low processing tolerance were particularly prominent. The common defect of the above technical routes was that the introduction of antibacterial agents not only had a significant negative impact on the mechanical properties of the material but also had biological toxicity, and simple processing methods might inhibit the antibacterial activity, ultimately resulting in waste of resources and cost increase.

[0004] In view of the above problems, the synergistic modification technology of polypropylene matrix shows unique advantages. Through the design of the dispersed phase structure and the innovation of the processing technology, the double enhancement of the mechanical properties and antibacterial function of the material can be achieved. In terms of mechanical properties, polyolefin elastomers or rubbers are usually used to melt-blend with polypropylene. Although the toughening method is simple and efficient, these elastomers are all derived from petroleum-based products, and the problems of cost and environmental pollution cannot be ignored. In addition, the increase in petroleum resource consumption is also one of the problems. In terms of antibacterial functionalization, starch is modified with antibacterial agents to make it antibacterial. However, its poor mechanical properties and serious hydrophilic properties limit its wide application. Therefore, the development of a composite material with good mechanical properties and antibacterial function as a food packaging box still needs to be solved. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a polypropylene compound plasticized antibacterial starch composite material, its preparation method and application. By compounding plasticized antibacterial starch and maleic anhydride grafted polyolefin elastomer (POE-MA) with polypropylene, and using bio-based elastomers to replace part of the traditional elastomers, it can not only improve the mechanical properties of polypropylene materials, but also achieve the broad-spectrum antibacterial property of polypropylene materials. The polypropylene compound plasticized antibacterial starch composite material effectively reduces food transportation losses and quality safety problems, and improves the problem of overproduction of ordinary polypropylene output value, providing a new choice for the toughening modification and antibacterial functionalization of polypropylene.

[0006] To achieve the above object, the present invention provides a polypropylene compound plasticized antibacterial starch composite material, which is prepared from the following raw materials in parts by weight:

[0007] 70-200 parts of polypropylene, 20-60 parts of maleic anhydride grafted polyolefin elastomer, 6.633-19.71 parts of starch, 2.673-8.91 parts of glycerol, 0.02-3 parts of antibacterial agent, and 1 part of antioxidant.

[0008] Preferably, the polypropylene is one of PA14D, PPH-T03S and T300; the maleic anhydride grafted polyolefin elastomer is one of DF610, LC170 and POE8999.

[0009] Preferably, the starch is one of tapioca starch, corn starch and pea starch; the antibacterial agent is polyhexamethylene biguanide hydrochloride; the antioxidant is antioxidant 1010.

[0010] The present invention also provides a preparation method of the polypropylene compound plasticized antibacterial starch composite material, which includes the following steps:

[0011] (1) Starch is dried to obtain dried starch;

[0012] (2) The dried starch obtained in step (1) is mixed with glycerol, and then a bacteriostatic agent is added, followed by kneading to obtain plasticized bacteriostatic starch.

[0013] (3) Polypropylene, maleic anhydride-grafted polyolefin elastomer, and an antioxidant are mixed and kneaded to obtain a blend. The blend is mixed with the plasticized bacteriostatic starch obtained in step (2) to obtain a polypropylene composite plasticized bacteriostatic starch composite material.

[0014] Preferably, in step (1), the drying temperature is 70-90 °C, and the drying time is 6-18 h.

[0015] Preferably, in step (1), the mass ratio of the starch to the glycerol in step (2) is 67-73:27-33; the dosage of the bacteriostatic agent in step (2) is 0.2%-1.0% of the total mass of the starch in step (1), the glycerol in step (2), and the bacteriostatic agent in step (2).

[0016] Preferably, in step (2), the kneading temperature is 125-145 °C, the kneading speed is 60-80 rpm, and the kneading time is 3-5 min.

[0017] Preferably, in step (3), the kneading temperature is 180-190 °C, the kneading speed is 60-80 rpm, and the kneading time is 3-5 min; in step (3), the blending temperature is 180-190 °C, the blending speed is 60-80 rpm, and the blending time is 3-5 min.

[0018] The present invention also provides the application of the polypropylene composite plasticized bacteriostatic starch composite material in the preparation of a high impact resistance and bacteriostatic prefabricated food box.

[0019] Preferably, the application includes granulating the polypropylene composite plasticized bacteriostatic starch composite material and injection molding to obtain a high impact resistance and bacteriostatic prefabricated food box.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] 1. In the present invention, maleic anhydride-grafted polyolefin elastomer and plasticized bacteriostatic starch are uniformly dispersed inside the polypropylene matrix. The maleic anhydride groups in the maleic anhydride-grafted polyolefin elastomer react with the hydroxyl groups of the plasticized bacteriostatic starch to form ester bonds, thereby forming a multi-core structure inside the polypropylene matrix, that is, the polyolefin elastomer wraps the starch, effectively improving the compatibility between the plasticized bacteriostatic starch and polypropylene. When the composite material is impacted, a large amount of shear yield and cavitation holes are generated, thereby enhancing the impact resistance, that is, toughness, of the polypropylene composite material.

[0022] 2. In the present invention, the bacteriostatic agent is grafted onto starch, endowing the polypropylene composite material with bacteriostatic properties. Due to the chemical reaction between the plasticized starch and the bacteriostatic agent, the bacteriostatic agent is covalently grafted into the plasticized starch. Therefore, the precipitation rate of the bacteriostatic agent in the composite material is 0, preventing the bacteriostatic agent from diffusing into food and being non-toxic and harmless to the human body. The bacteriostatic agent in this composite material has high activity. One end of the guanidine group in the bacteriostatic agent polyhexamethylene biguanide hydrochloride (PHMG) itself has high activity, making the polymer positively charged and easily adsorbed by bacteria and viruses, thereby inhibiting the division function of bacteria and viruses, and thus achieving the bacteriostatic function.

[0023] 3. In the present invention, starch is introduced into the interior of the polypropylene matrix, replacing part of the polyolefin elastomer, that is, using a bio-based elastomer to replace part of the petroleum-based elastomer, which can achieve a synergistic toughening effect. The composite material prepared by this method can reduce the cost by about 10%-20% compared with the composite material filled with pure petroleum-based elastomer, which is very important for reducing costs and protecting the environment. Moreover, its processability is safe and the cost is low, enabling wide-range application.

[0024] 4. The present invention has a dual-functional design of impact resistance and bacteriostasis, which not only maintains the inherent processing advantages of polypropylene but also endows the composite material with good mechanical properties and bacteriostatic functionality. That is, it effectively reduces food transportation losses and food quality problems, eliminates the risk of bacteriostatic agent migration, expands the application in food packaging boxes, and provides a new path for the development of high-strength, tough, and long-lasting bacteriostatic prefabricated food meal box packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is the micrograph of the polypropylene compounded plasticized bacteriostatic starch composite material prepared in Example 3, and the scale bar is 1 μm;

[0027] Figure 2 It is the bacteriostatic test chart of the polypropylene compounded plasticized bacteriostatic starch composite materials prepared in Examples 1-3 against Staphylococcus aureus. Among them, A is the polypropylene compounded plasticized bacteriostatic starch composite material prepared in Example 1, B is the polypropylene compounded plasticized bacteriostatic starch composite material prepared in Example 2, and C is the polypropylene compounded plasticized bacteriostatic starch composite material prepared in Example 3;

[0028] Figure 3A high impact resistance and antibacterial prefabricated food container made of a polypropylene compounded plasticized antibacterial starch composite material for Example 3. Detailed implementation manners

[0029] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation manners of the present invention.

[0030] It should be understood that the terms used in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0032] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0033] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0034] The "parts" mentioned in the present invention are all in parts by mass unless otherwise specified.

[0035] Sources of materials and equipment used in the present invention: PA14D was purchased from China National Petroleum Corporation, PPHT03S was purchased from China National Petroleum and Chemical Corporation, T300 was purchased from China National Petroleum and Chemical Corporation, DF610 was purchased from Mitsui Chemicals, LC170 was purchased from Mitsui Chemicals, POE8999 was purchased from Borui New Materials Co., Ltd., tapioca starch was purchased from Shanghai Yuanye Bio-Technology Co., Ltd., corn starch was purchased from Shanghai Macklin Biochemical Co., Ltd., pea starch was purchased from Shanghai Yuanye Bio-Technology Co., Ltd., glycerol was purchased from Shanghai Macklin Biochemical Co., Ltd., polyhexamethylene biguanide hydrochloride (PHMG) was purchased from Shanghai Merck Chemical Technology Co., Ltd., antioxidant 1010 was purchased from Shanghai Kayin Chemical Industry, the oven model was DZC-6020MBE, purchased from the medical equipment factory of Shanghai Boxun Industry Co., Ltd., the internal mixer Hakke Poly Lab QC was purchased from Thermo Fisher Scientific, and the injection molding machine model was BP-8180-A, purchased from Baopin Precision Instruments Co., Ltd.

[0036] Example 1

[0037] 140 parts of PA14D, 40 parts of LC170, 13.972 parts of tapioca starch, 5.988 parts of glycerol, 0.04 part of polyhexamethylene biguanide hydrochloride, and 1 part of antioxidant 1010.

[0038] (1) Put tapioca starch into an oven and dry it at 80 °C for 12 h to obtain the dried starch.

[0039] (2) Mix the dried starch with glycerol (the starch is plasticized with glycerol), then add polyhexamethylene biguanide hydrochloride, and place it in an internal mixer at 145 °C and 80 rpm for 4 min to obtain the plasticized antibacterial starch.

[0040] (3) Mix PA14D, LC170 and antioxidant 1010, place it in an internal mixer at 180 °C and 80 rpm for 5 min to obtain a blend, mix the blend with the plasticized antibacterial starch, and place it in an internal mixer at 180 °C and 80 rpm for 5 min to obtain a polypropylene compounded plasticized antibacterial starch composite material.

[0041] (4) Granulate the polypropylene compounded plasticized antibacterial starch composite material into 5 mm square particles, and injection mold it at 190 °C for 0.2 h in an injection molding machine to obtain a high impact resistance antibacterial prefabricated food box.

[0042] Example 2

[0043] 140 parts of PA14D, 40 parts of LC170, 13.93 parts of tapioca starch, 5.97 parts of glycerol, 0.1 part of polyhexamethylene biguanide hydrochloride, and 1 part of antioxidant 1010.

[0044] (1) Cassava starch was placed in an oven and dried at 80 °C for 12 h to obtain the dried starch.

[0045] (2) The dried starch was mixed with glycerol, and then polyhexamethylene biguanide hydrochloride was added. The mixture was placed in a mixer at 145 °C and kneaded at 80 rpm for 4 min to obtain the plasticized antibacterial starch.

[0046] (3) PA14D, LC170 and antioxidant 1010 were mixed and placed in a mixer at 180 °C and kneaded at 80 rpm for 5 min to obtain a blend. The blend was mixed with the plasticized antibacterial starch and placed in a mixer at 180 °C and kneaded at 80 rpm for 5 min to obtain a polypropylene compounded plasticized antibacterial starch composite material.

[0047] (4) The polypropylene compounded plasticized antibacterial starch composite material was granulated into 5 mm square particles and injection molded at 190 °C in an injection molding machine for 0.2 h to obtain a high impact resistance antibacterial prefabricated food meal box.

[0048] Example 3

[0049] 140 parts of PA14D, 40 parts of LC170, 13.86 parts of cassava starch, 5.94 parts of glycerol, 0.2 part of polyhexamethylene biguanide hydrochloride, 1 part of antioxidant 1010.

[0050] (1) Cassava starch was placed in an oven and dried at 80 °C for 12 h to obtain the dried starch.

[0051] (2) The dried starch was mixed with glycerol, and then polyhexamethylene biguanide hydrochloride was added. The mixture was placed in a mixer at 145 °C and kneaded at 80 rpm for 4 min to obtain the plasticized antibacterial starch.

[0052] (3) PA14D, LC170 and antioxidant 1010 were mixed and placed in a mixer at 180 °C and kneaded at 80 rpm for 5 min to obtain a blend. The blend was mixed with the plasticized antibacterial starch and placed in a mixer at 180 °C and kneaded at 80 rpm for 5 min to obtain a polypropylene compounded plasticized antibacterial starch composite material.

[0053] (4) The polypropylene compounded plasticized antibacterial starch composite material was granulated into 5 mm square particles and injection molded at 190 °C in an injection molding machine for 0.2 h to obtain a high impact resistance antibacterial prefabricated food meal box.

[0054] Example 4

[0055] 140 parts of PPH-T03S, 40 parts of DF610, 13.93 parts of corn starch, 5.97 parts of glycerol, 0.1 part of polyhexamethylene biguanide hydrochloride, 1 part of antioxidant 1010.

[0056] (1) Corn starch was placed in an oven and dried at 80 °C for 12 h to obtain the dried starch.

[0057] (2) The dried starch is mixed with glycerol, and then polyhexamethylene biguanide hydrochloride is added. It is placed in a mixer at 125 °C and kneaded at 70 rpm for 5 min to obtain plasticized antibacterial starch.

[0058] (3) PPH-T03S, DF610 and antioxidant 1010 are mixed and placed in a mixer at 185 °C and kneaded at 75 rpm for 3 min to obtain a blend. The blend is mixed with the plasticized antibacterial starch and placed in a mixer at 190 °C and kneaded at 80 rpm for 3 min to obtain a polypropylene compounded plasticized antibacterial starch composite material.

[0059] (4) The polypropylene compounded plasticized antibacterial starch composite material is granulated into 5 mm square particles and injection molded at 185 °C in an injection molding machine for 0.2 h to obtain a high impact resistance antibacterial prefabricated vegetable lunch box.

[0060] Example 5

[0061] 140 parts of T300, 40 parts of POE8999, 13.86 parts of pea starch, 5.94 parts of glycerol, 0.2 part of polyhexamethylene biguanide hydrochloride, 1 part of antioxidant 1010.

[0062] (1) Pea starch is placed in an oven and dried at 80 °C for 12 h to obtain dried starch.

[0063] (2) The dried starch is mixed with glycerol, and then polyhexamethylene biguanide hydrochloride is added. It is placed in a mixer at 130 °C and kneaded at 80 rpm for 3 min to obtain plasticized antibacterial starch.

[0064] (3) T300, POE8999 and antioxidant 1010 are mixed and placed in a mixer at 190 °C and kneaded at 60 rpm for 4 min to obtain a blend. The blend is mixed with the plasticized antibacterial starch and placed in a mixer at 185 °C and kneaded at 60 rpm for 4 min to obtain a polypropylene compounded plasticized antibacterial starch composite material.

[0065] (4) The polypropylene compounded plasticized antibacterial starch composite material is granulated into 5 mm square particles and injection molded at 195 °C in an injection molding machine for 0.2 h to obtain a high impact resistance antibacterial prefabricated vegetable lunch box.

[0066] Comparative Example 1

[0067] It is commercially available pure commercial PP.

[0068] Comparative Example 2

[0069] 140 parts of PA14D, 60 parts of LC17, 1 part of antioxidant 1010.

[0070] (1) PA14D, LC170 and antioxidant 1010 are mixed and placed in a Banbury mixer at 180 °C and kneaded at 80 rpm for 5 min to obtain a blend, and a composite material is obtained.

[0071] (2) The composite material is granulated into 5 mm square particles and injection molded at 190 °C in an injection molding machine for 0.2 h to obtain a prefabricated vegetable lunch box.

[0072] Comparative Example 3

[0073] 140 parts of PA14D, 40 parts of LC170, 14 parts of tapioca starch, 6 parts of glycerol, 1 part of antioxidant 1010.

[0074] (1) Tapioca starch is placed in an oven and dried at 80 °C for 12 h to obtain dried starch.

[0075] (2) The dried starch is mixed with glycerol and placed in a Banbury mixer at 145 °C and kneaded at 80 rpm for 4 min to obtain plasticized starch.

[0076] (3) PA14D, LC170 and antioxidant 1010 are mixed and placed in a Banbury mixer at 180 °C and kneaded at 80 rpm for 5 min to obtain a blend. The blend is mixed with the plasticized starch and placed in a Banbury mixer at 180 °C and blended at 80 rpm for 5 min to obtain a polypropylene compounded plasticized starch composite material.

[0077] (4) The polypropylene compounded plasticized starch composite material is granulated into 5 mm square particles and injection molded at 190 °C in an injection molding machine for 0.2 h to obtain a prefabricated vegetable lunch box.

[0078] Experimental Example 1

[0079] Measure the impact properties and antibacterial rates of the composite materials prepared in Examples 1 to 3 and Comparative Examples 2 to 3 and the commercial PP of Comparative Example 1.

[0080] Table 1 Performance measurement data of the composite materials prepared in Examples 1 to 3 and Comparative Examples 2 to 3 and the commercial PP of Comparative Example 1

[0081]

[0082] As can be seen from Table 1 above, when the addition content of the plasticized starch used in Comparative Example 3 is 20 parts, the impact strength is better than that of the commercial PP in Comparative Example 1 and also better than that of the composite material without plasticized starch in Comparative Example 2 at four temperatures. Considering comprehensively, compared with the pure polyolefin elastomer compounded polypropylene composite material, partially replacing the polyolefin elastomer with plasticized starch can better improve the impact resistance (toughness), which is very important for reducing costs and protecting the environment. By comparing the impact strength between the examples and the comparative examples, when the addition content of the plasticized antibacterial starch described in Examples 1 to 3 is 20 parts, and the mass of the antibacterial agent accounts for 0.2% (Example 1), 0.5% (Example 2), and 1.0% (Example 3) of the total mass of starch, glycerol, and antibacterial agent respectively, the impact strength at 25 °C is comparable to that of the composite material without plasticized starch described in Comparative Example 2 and is better than that of the commercial PP in Comparative Example 1, with 40 - 60 kJ / m 2 The impact strength can be considered as an indication that the material has a certain toughness.

[0083] As Figure 1 shown, by observing the microstructure of the polypropylene compounded plasticized antibacterial starch composite material prepared in Example 3, the white part is the starch phase and the black part is the rubber phase. The rubber encapsulates the starch to form a multi-core structure in the polypropylene matrix. This structure is confirmed by the microstructure, and this structure makes a special contribution to the improvement of the toughness of the polypropylene composite material.

[0084] As Figure 2 shown, by observing the antibacterial zones shown as A in Figure 2 , B in Figure 2 , and C in Figure 2 , it can be seen that the polypropylene compounded plasticized antibacterial starch composite materials prepared in Examples 1 to 3 all have a certain antibacterial ability when the addition amount of the antibacterial agent accounts for 0.2%, 0.5%, and 1.0% of the total mass of starch, glycerol, and antibacterial agent.

[0085] As Figure 3 shown, it is a high impact resistance and antibacterial type prefabricated vegetable meal box prepared in Example 3.

[0086] In summary, compared with the pure polyolefin elastomer compounded polypropylene composite material, partially replacing the polyolefin elastomer with plasticized antibacterial starch can better maintain the room temperature impact resistance (toughness) and has a certain antibacterial ability. It can be prepared into a prefabricated vegetable meal box with a fresh-keeping function and high impact resistance, which can not only ensure the food safety quality but also avoid the problem of food leakage caused by impact during transportation. This has guiding significance for the development of functional polypropylene composite materials with impact resistance.

[0087] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A polypropylene compounded plasticized antibacterial starch composite material, characterized in that: The method is prepared by comprising the following raw materials in parts by weight: 70-200 parts of polypropylene, 20-60 parts of maleic anhydride grafted polyolefin elastomer, 6.633-19.71 parts of starch, 2.673-8.91 parts of glycerol, 0.02-3 parts of antibacterial agent and 1 part of antioxidant.

2. The polypropylene compounded plasticized antibacterial starch composite material according to claim 1, characterized in that: The polypropylene is one of PA14D, PPH-T03S and T300; the maleic anhydride grafted polyolefin elastomer is one of DF610, LC170 and POE8999.

3. The polypropylene-compounded plasticized antibacterial starch composite material according to claim 1, characterized in that: The starch is one of cassava starch, corn starch and pea starch; the antibacterial agent is polyhexamethylene biguanide hydrochloride; and the antioxidant is antioxidant 1010.

4. The method for preparing the polypropylene-plasticized antibacterial starch composite material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Starch, drying to obtain dried starch; (2) mixing the dried starch obtained in step (1) with glycerol, then adding an antibacterial agent, and kneading to obtain plasticized antibacterial starch; (3) polypropylene, maleic anhydride grafted polyolefin elastomer and antioxidant are mixed and kneaded to obtain a blend, and the blend is mixed with the plasticized antibacterial starch obtained in step (2) to obtain a polypropylene-plasticized antibacterial starch composite material.

5. The preparation method according to claim 4, characterized in that: The drying temperature in step (1) is 70 to 90° C., and the drying time is 6 to 18 hours.

6. The preparation method according to claim 4, characterized in that: The mass ratio of the starch in step (1) to the glycerol in step (2) is 67-73:27-33; the amount of the antibacterial agent in step (2) is 0.2%-1.0% of the total mass of the starch in step (1), the glycerol in step (2) and the antibacterial agent in step (2).

7. The preparation method according to claim 4, characterized in that: The mixing temperature in step (2) is 125-145° C., the mixing speed is 60-80 rpm, and the mixing time is 3-5 min.

8. The preparation method according to claim 4, characterized in that: The mixing temperature in step (3) is 180-190° C., the mixing speed is 60-80 rpm, and the mixing time is 3-5 min. The blending temperature in step (3) is 180-190° C., the blending speed is 60-80 rpm, and the blending time is 3-5 min.

9. Use of the polypropylene-plasticized antibacterial starch composite material as claimed in any one of claims 1 to 3 in the preparation of high-impact antibacterial pre-prepared meal boxes.

10. The use according to claim 9, characterized in that: The application comprises compounding the polypropylene with a plasticized antibacterial starch composite material, granulating, and injection molding to obtain a high-impact antibacterial prefabricated meal box.

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