Antibacterial chitosan grafted polypropylene composite film and preparation method thereof

Abstract

The invention relates to the technical field of polypropylene antibiosis, and discloses an antibacterial chitosan grafted polypropylene composite membrane, carboxyl of carboxyl-terminated polypropylene is activated under the action of N-hydroxysuccinimide serving as an activator and dicyclohexylcarbodiimide serving as a condensing agent to perform amidation reaction with amino in guanidine salt oligomer modified chitosan, and the antibacterial chitosan grafted polypropylene composite membrane is obtained. The guanidine salt oligomer modified chitosan-based antibacterial agent is grafted into a polypropylene molecular chain, the chemical grafting effect is beneficial to tight combination of the chitosan-based antibacterial agent and polypropylene, and the problems of poor compatibility and phase separation caused by too large interfacial tension between the chitosan-based antibacterial agent and polypropylene are avoided; meanwhile, active antibacterial components are introduced into a polypropylene molecular chain, so that the polypropylene material is endowed with permanent antibacterial activity, and the polypropylene material has very strong inhibiting and killing effects on bacteria and microorganisms such as escherichia coli and staphylococcus aureus.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene antibacterial, in particular to an antibacterial chitosan grafted polypropylene composite film and a preparation method thereof. Background Art

[0002] Antibacterial materials such as antibacterial plastics, antibacterial fibers, antibacterial fabrics, etc., are usually compounded with antibacterial agents with antibacterial activity to give the materials some antibacterial properties. Traditional antibacterial agents mainly include inorganic antibacterial agents, such as zinc oxide, titanium dioxide, nanosilver, etc.; and organic antibacterial agents, such as bisquaternary compounds, quaternary ammonium compounds, thiazole compounds, etc.; and natural antibacterial agents such as castor oil, chitosan, wasabi, etc., among which chitosan is widely available and has good biocompatibility. It is widely used in medical supplies and bioengineering. Therefore, further improving the antibacterial activity of chitosan has become a research hotspot.

[0003] Polypropylene is non-toxic and odorless, transparent in appearance, light in texture, has good acid, alkali and solvent resistance, and has high strength and good toughness, which makes polypropylene have broad application prospects in clothing, blankets and other fabrics, food packaging, pharmaceutical packaging and medical devices. With the development of industry and technology, traditional polypropylene has no antibacterial properties, which limits its practical application in antibacterial materials and antibacterial fields. Therefore, it is necessary to modify polypropylene to improve its antibacterial properties.

[0004] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides an antibacterial chitosan-grafted polypropylene composite film and a preparation method thereof, which solves the problems of low antibacterial activity of chitosan and poor antibacterial performance of traditional polypropylene materials.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: an antibacterial chitosan grafted polypropylene composite film, the preparation method of the antibacterial chitosan grafted polypropylene composite film is the following steps: (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0006] (2) Add chitosan to an acetic acid solution with a pH of 2-3, stir to dissolve, add sodium periodate to carry out a selective oxidation reaction, then add sodium hydroxide to adjust the pH of the solution to neutral, filter the solvent, wash with distilled water for purification, and obtain aldehyde chitosan.

[0007] (3) Add aldehyde chitosan to distilled water solvent, perform ultrasonic dispersion until uniform dispersion, add guanidine oligomer, perform Schiff base reaction, add distilled water and perform centrifugal washing to obtain guanidine oligomer modified chitosan.

[0008] (4) Place polypropylene in a nitric acid solution with a mass fraction of 60-70%, react at 80-100 °C for 2-6 h, filter the nitric acid solution, and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0009] (5) Add end-carboxyl polypropylene and guanidine oligomer modified chitosan to N,N-dimethylformamide solvent, stir evenly, add activator and condensation agent, carry out amidation reaction, add distilled water and centrifuge to wash until the upper layer is clear, wash the lower layer with distilled water and acetone to purify, and obtain antibacterial chitosan grafted polypropylene.

[0010] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate are placed in a twin-screw extruder for melt blending, and polypropylene masterbatch is extruded. The polypropylene masterbatch is subjected to biaxial stretching to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0011] Preferably, in step (2), the mass ratio of chitosan to sodium periodate is 100:70-120.

[0012] Preferably, the temperature of the selective oxidation reaction in step (2) is 5-15°C, and the reaction time is 4-12 h.

[0013] Preferably, in step (3), the mass ratio of aldehyde chitosan to guanidine oligomer is 100:5-30.

[0014] Preferably, the temperature of the Schiff base reaction in step (3) is 25-50°C, and the reaction time is 12-24 h.

[0015] Preferably, in step (5), the activator is N-hydroxysuccinimide and the condensing agent is dicyclohexylcarbodiimide.

[0016] Preferably, in step (5), the mass ratio of terminal carboxyl polypropylene, guanidine oligomer modified chitosan, N-hydroxysuccinimide and dicyclohexylcarbodiimide is 100:0.5-4:0.8-6:1.5-12.

[0017] Preferably, the temperature of the amidation reaction in step (5) is 40-80°C, and the reaction time is 24-48 h.

[0018] Preferably, in step (6), the mass ratio of the antibacterial chitosan grafted polypropylene, the antioxidant 1010 and the lubricant butyl stearate is 100:0.5-3:1-5.

[0019] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial technical effects: The antibacterial chitosan grafted polypropylene composite film can perform ring-opening oxidation on part of the pyranose rings of chitosan by regulating the ratio of chitosan and oxidant sodium periodate, and controlling the oxidation temperature and time, so as to obtain aldehyde chitosan with low oxidation degree, thereby preventing chitosan from being oxidized to a large extent and destroying the molecular chain structure, and controlling the oxidation degree to adjust the content of aldehyde groups, so as to better react with guanidine oligomers to produce aldehyde-amine Schiff base to obtain guanidine oligomer-modified chitosan, and introduce guanidine functional groups with strong antibacterial properties into the chitosan matrix to obtain a chitosan-based antibacterial agent with high antibacterial activity.

[0020] The invention discloses an antibacterial chitosan grafted polypropylene composite film. The molecular chain of polypropylene is oxidized by nitric acid to obtain carboxyl-terminated polypropylene. Under the action of activator N-hydroxysuccinimide and condensing agent dicyclohexylcarbodiimide, the carboxyl group is activated to undergo amidation reaction with the amino group in chitosan modified by guanidine oligomer, so that the chitosan-based antibacterial agent modified by guanidine oligomer is grafted into the molecular chain of polypropylene. The chemical grafting effect is not only conducive to the close combination of the chitosan-based antibacterial agent and polypropylene, but also avoids the problems of poor compatibility and phase separation caused by excessive interfacial tension between the two, and at the same time, the active antibacterial component is introduced into the molecular chain of polypropylene, so that the polypropylene material is endowed with permanent antibacterial activity, and has a strong inhibitory and killing effect on bacteria and microorganisms such as Escherichia coli and Staphylococcus aureus. DETAILED DESCRIPTION

[0021] To achieve the above object, the present invention provides the following specific implementation methods and examples: An antibacterial chitosan grafted polypropylene composite film, the preparation method of which is the following steps: (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0022] (2) Add chitosan to an acetic acid solution with a pH of 2-3, stir to dissolve, then add sodium periodate in a mass ratio of 70-120:100 to chitosan, carry out selective oxidation reaction at 5-15 °C for 4-12 h, then add sodium hydroxide to adjust the pH of the solution to neutral, filter the solvent, wash with distilled water for purification, and obtain aldehyde chitosan.

[0023] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer in a mass ratio of aldehyde chitosan to guanidine oligomer of 5-30:100, carry out Schiff base reaction at 25-50 °C for 12-24 h, add distilled water for centrifugation and washing, and obtain guanidine oligomer modified chitosan.

[0024] (4) Place polypropylene in a nitric acid solution with a mass fraction of 60-70%, react at 80-100 °C for 2-6 h, filter the nitric acid solution, and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0025] (5) Add carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide in a mass ratio of 100:0.5-4:0.8-6:1.5-12 to N,N-dimethylformamide solvent, carry out amidation reaction at 40-80 °C for 24-48 h, add distilled water and centrifuge to wash until the upper layer is clear, and wash the lower layer with distilled water and acetone to obtain antibacterial chitosan grafted polypropylene.

[0026] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:0.5-3:1-5 are placed in a twin-screw extruder for melt blending, and polypropylene masterbatch is extruded. The polypropylene masterbatch is subjected to biaxial stretching to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0027] Example 1

[0028] (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0029] (2) Chitosan was added to an acetic acid solution with a pH of 2. After stirring to dissolve, sodium periodate was added in a mass ratio of 70:100 to chitosan. The solution was selectively oxidized at 5 °C for 4 h. Then, sodium hydroxide was added to adjust the pH of the solution to neutral. The solvent was filtered and the solution was washed and purified with distilled water to obtain aldehyde chitosan.

[0030] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer at a mass ratio of aldehyde chitosan to guanidine oligomer of 5:100, carry out Schiff base reaction at 25 °C for 12 h, add distilled water for centrifugal washing, and obtain guanidine oligomer modified chitosan.

[0031] (4) Place polypropylene in a 60% by mass nitric acid solution and react at 80 °C for 2 h. Filter the nitric acid solution and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0032] (5) To N,N-dimethylformamide solvent, carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide were added in a mass ratio of 100:0.5:0.8:1.5, and the amidation reaction was carried out at 40°C for 24 h. Distilled water was added and centrifuged until the upper layer was clear. The lower layer was washed and purified with distilled water and acetone to obtain antibacterial chitosan-grafted polypropylene.

[0033] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:0.5:1 were placed in a twin-screw extruder for melt blending, and polypropylene masterbatch was extruded. The polypropylene masterbatch was biaxially stretched to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0034] Example 2

[0035] (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0036] (2) Chitosan was added to an acetic acid solution with a pH of 3. After stirring to dissolve, sodium periodate was added in a mass ratio of 85:100 to chitosan. The solution was selectively oxidized at 15 °C for 6 h. Then, sodium hydroxide was added to adjust the pH of the solution to neutral. The solvent was filtered and the solution was washed and purified with distilled water to obtain aldehyde chitosan.

[0037] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer at a mass ratio of aldehyde chitosan to guanidine oligomer of 12:100, carry out Schiff base reaction at 30 °C for 18 h, add distilled water for centrifugation and washing, and obtain guanidine oligomer modified chitosan.

[0038] (4) Place polypropylene in a 70% by mass nitric acid solution and react at 90 °C for 4 h. Filter the nitric acid solution and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0039] (5) To N,N-dimethylformamide solvent, carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide were added in a mass ratio of 100:1.5:2.5:5, and the amidation reaction was carried out at 50°C for 36 h. Distilled water was added and centrifuged until the upper layer was clear. The lower layer was washed and purified with distilled water and acetone to obtain antibacterial chitosan-grafted polypropylene.

[0040] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:1.2:2 were placed in a twin-screw extruder for melt blending, and polypropylene masterbatch was extruded. The polypropylene masterbatch was subjected to biaxial stretching to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0041] Example 3

[0042] (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0043] (2) Chitosan was added to an acetic acid solution with a pH of 2.5, and after stirring to dissolve, sodium periodate was added in a mass ratio of 105:100 to chitosan. The selective oxidation reaction was carried out at 10 °C for 8 h, and then sodium hydroxide was added to adjust the pH of the solution to neutral. The solvent was filtered, and the solution was washed and purified with distilled water to obtain aldehyde chitosan.

[0044] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer at a mass ratio of aldehyde chitosan to guanidine oligomer of 22:100, carry out Schiff base reaction at 40 °C for 18 h, add distilled water for centrifugal washing, and obtain guanidine oligomer modified chitosan.

[0045] (4) Place polypropylene in a 65% by mass nitric acid solution and react at 90 °C for 6 h. Filter the nitric acid solution and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0046] (5) To N,N-dimethylformamide solvent, carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide were added in a mass ratio of 100:3:4:8.5, and the amidation reaction was carried out at 60 °C for 36 h. Distilled water was added and centrifuged until the upper layer was clear. The lower layer was washed and purified with distilled water and acetone to obtain antibacterial chitosan-grafted polypropylene.

[0047] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:2.2:3.5 were placed in a twin-screw extruder for melt blending, and polypropylene masterbatch was extruded. The polypropylene masterbatch was biaxially stretched to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0048] Example 4

[0049] (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0050] (2) Chitosan was added to an acetic acid solution with a pH of 3. After stirring to dissolve, sodium periodate was added in a mass ratio of 120:100 to chitosan. The solution was selectively oxidized at 15 °C for 12 h. Then, sodium hydroxide was added to adjust the pH of the solution to neutral. The solvent was filtered and the solution was washed and purified with distilled water to obtain aldehyde chitosan.

[0051] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer at a mass ratio of aldehyde chitosan to guanidine oligomer of 30:100, carry out Schiff base reaction at 50 °C for 24 h, add distilled water for washing by centrifugation, and obtain guanidine oligomer modified chitosan.

[0052] (4) Place polypropylene in a 70% by mass nitric acid solution and react at 100 °C for 6 h. Filter the nitric acid solution and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0053] (5) To N,N-dimethylformamide solvent, carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide were added in a mass ratio of 100:4:6:12, and the amidation reaction was carried out at 80 °C for 48 h. Distilled water was added and centrifuged until the upper layer was clear. The lower layer was washed and purified with distilled water and acetone to obtain antibacterial chitosan-grafted polypropylene.

[0054] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:3:5 were placed in a twin-screw extruder for melt blending, and polypropylene masterbatch was extruded. The polypropylene masterbatch was subjected to biaxial stretching to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0055] Comparative Example 1 (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0056] (2) Chitosan was added to an acetic acid solution with a pH of 3. After stirring to dissolve, sodium periodate was added in a mass ratio of 55:100 to chitosan. The solution was selectively oxidized at 15 °C for 8 h. Then, sodium hydroxide was added to adjust the pH of the solution to neutral. The solvent was filtered and the solution was washed and purified with distilled water to obtain aldehyde chitosan.

[0057] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer at a mass ratio of aldehyde chitosan to guanidine oligomer of 2:100, carry out Schiff base reaction at 50 °C for 24 h, add distilled water for centrifugal washing, and obtain guanidine oligomer modified chitosan.

[0058] (4) Place polypropylene in a 70% by mass nitric acid solution and react at 90 °C for 4 h. Filter the nitric acid solution and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0059] (5) To N,N-dimethylformamide solvent, carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide were added in a mass ratio of 100:0.2:0.3:0.8, and the amidation reaction was carried out at 80°C for 48 h. Distilled water was added and centrifuged until the upper layer was clear. The lower layer was washed and purified with distilled water and acetone to obtain antibacterial chitosan-grafted polypropylene.

[0060] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:0.2:0.5 were placed in a twin-screw extruder for melt blending, and polypropylene masterbatch was extruded. The polypropylene masterbatch was biaxially stretched to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0061] Comparative Example 2 (1) Ethylene diamine and guanidine hydrochloride are subjected to melt polycondensation to obtain an amino-terminated guanidine salt oligomer.

[0062] (2) Chitosan was added to an acetic acid solution with a pH of 3, and after stirring to dissolve, sodium periodate was added in a mass ratio of 140:100 to chitosan. The solution was selectively oxidized at 15 °C for 4 h, and then sodium hydroxide was added to adjust the pH of the solution to neutral. The solvent was filtered, and the solution was washed and purified with distilled water to obtain aldehyde chitosan.

[0063] (3) Add aldehyde chitosan to distilled water solvent by ultrasonication until it is uniformly dispersed, add guanidine oligomer at a mass ratio of aldehyde chitosan to guanidine oligomer of 40:100, carry out Schiff base reaction at 40 °C for 24 h, add distilled water for washing by centrifugation, and obtain guanidine oligomer modified chitosan.

[0064] (4) Place polypropylene in a 65% by mass nitric acid solution and react at 90 °C for 6 h. Filter the nitric acid solution and wash the product with distilled water to obtain end-carboxyl polypropylene.

[0065] (5) To N,N-dimethylformamide solvent, carboxyl-terminated polypropylene, guanidine oligomer-modified chitosan, activator N-hydroxysuccinimide and condensation agent dicyclohexylcarbodiimide were added in a mass ratio of 100:5.5:8:16, and the amidation reaction was carried out at 60 °C for 48 h. Distilled water was added and centrifuged until the upper layer was clear. The lower layer was washed and purified with distilled water and acetone to obtain antibacterial chitosan-grafted polypropylene.

[0066] (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate in a mass ratio of 100:4:5.5 were placed in a twin-screw extruder for melt blending, and polypropylene masterbatch was extruded. The polypropylene masterbatch was subjected to biaxial stretching to obtain a composite film of the antibacterial chitosan grafted polypropylene.

[0067] Agar culture medium and Staphylococcus aureus suspension were placed in culture dishes, and after oscillation, the antibacterial chitosan grafted polypropylene composite films of Examples 1-4 were added respectively as experimental groups 1-4, and the composite films of Comparative Examples 1-2 were added respectively as control groups 1-2, and the group without composite film was the blank group. The culture dishes of each group were placed in an incubator and cultured at a constant temperature and humidity of 37°C for 12 h, the number of colonies was observed, and the antibacterial performance of each group of composite films on Staphylococcus aureus was calculated.

[0068]

[0069] Agar culture medium and Escherichia coli suspension were placed in culture dishes, and after oscillation, the antibacterial chitosan grafted polypropylene composite films of Examples 1-4 were added respectively as experimental groups 1-4, and the composite films of Comparative Examples 1-2 were added respectively as control groups 1-2, and the group without composite film was the blank group. The culture dishes of each group were placed in an incubator and cultured at a constant temperature and humidity of 37°C for 12 h, the number of colonies was observed and the antibacterial performance of each group of composite films against Escherichia coli was calculated.

[0070]

Claims

1. An antibacterial chitosan-grafted polypropylene composite film, characterized in that: The preparation method of the antibacterial chitosan grafted polypropylene composite film comprises the following steps: (1) melt polycondensing ethylenediamine and guanidine hydrochloride to obtain an amino-terminated guanidine salt oligomer; (2) adding chitosan to an acetic acid solution with a pH of 2-3, stirring and dissolving, and then adding sodium periodate to carry out a selective oxidation reaction to obtain aldehyde chitosan; (3) adding aldehyde chitosan to a distilled water solvent, ultrasonically dispersing it until it is uniformly dispersed, adding guanidine oligomer, and performing Schiff base reaction to obtain guanidine oligomer-modified chitosan; (4) placing polypropylene in a nitric acid solution with a mass fraction of 60-70%, reacting at 80-100 °C for 2-6 h to obtain terminal carboxyl polypropylene; (5) adding carboxyl-terminated polypropylene and guanidine oligomer-modified chitosan to N,N-dimethylformamide solvent, stirring evenly, adding an activator and a condensation agent, and performing an amidation reaction to obtain antibacterial chitosan-grafted polypropylene; (6) The antibacterial chitosan grafted polypropylene, antioxidant 1010 and lubricant butyl stearate are placed in a twin-screw extruder for melt blending, and polypropylene masterbatch is extruded. The polypropylene masterbatch is subjected to biaxial stretching to obtain a composite film of the antibacterial chitosan grafted polypropylene.

2. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: In the step (2), the mass ratio of chitosan to sodium periodate is 100:70-120.

3. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: The temperature of the selective oxidation reaction in step (2) is 5-15°C, and the reaction time is 4-12 h.

4. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: In the step (3), the mass ratio of aldehyde chitosan to guanidine oligomer is 100:5-30.

5. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: The temperature of the Schiff base reaction in step (3) is 25-50°C, and the reaction time is 12-24 h.

6. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: In the step (5), the activating agent is N-hydroxysuccinimide and the condensing agent is dicyclohexylcarbodiimide.

7. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: In the step (5), the mass ratio of the terminal carboxyl-modified polypropylene, the guanidine oligomer-modified chitosan, N-hydroxysuccinimide and dicyclohexylcarbodiimide is 100:0.5-4:0.8-6:1.5-12.

8. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: The temperature of the amidation reaction in step (5) is 40-80°C, and the reaction time is 24-48 h.

9. The antibacterial chitosan-grafted polypropylene composite film according to claim 1, characterized in that: In the step (6), the mass ratio of the antibacterial chitosan grafted polypropylene, the antioxidant 1010 and the lubricant butyl stearate is 100:0.5-3:1-5.

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