Preparation method of bacteriostatic high-strength high-barrier break-resistant food packaging film

Abstract

The application relates to a preparation method of a bacteriostatic high-strength high-barrier break-resistant food packaging film, and relates to the technical field of food packaging film preparation.The bacteriostatic high-strength high-barrier break-resistant food packaging film comprises a polyethylene surface layer, a first maleic anhydride high-strength adhesive layer, a high-barrier first polyamide layer, an ethylene-vinyl alcohol copolymer layer, a high-barrier second polyamide layer, a second maleic anhydride high-strength adhesive layer and a polyethylene antibacterial inner layer, and the preparation method is specifically completed through the following steps: one, preparing a composite antibacterial agent; two, uniformly mixing polyethylene and the composite antibacterial agent according to a weight ratio of (90-95):(5-8) to obtain a polyethylene antibacterial inner layer master batch; three, co-extruding, downward blowing and film pouring to obtain the bacteriostatic high-strength high-barrier break-resistant food packaging film with a seven-layer composite structure.The bacteriostatic high-strength high-barrier break-resistant food packaging film prepared by the application has spectral antibacterial performance, is harmless to human bodies and can prolong the shelf life of food.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food packaging film preparation, in particular to a preparation method of a bacteriostatic high-strength high-barrier break-resistant food packaging film. BACKGROUND

[0002] With the rapid development of the plastic packaging industry, people's requirements for express logistics, food packaging, public facility health and epidemic prevention, antibacterial and sterilization are also increasing. Food packaging film is a common form of food packaging. Food packaging film is usually a kind of high polymer film material wrapped on the surface of food, which can prevent the contact of bacteria and other microorganisms in the outside world and external pollutants with the surface of food, so as to avoid the deterioration of food in the environment of transportation, storage and other environments, maintain the appearance, and prolong the shelf life of food.

[0003] At present, the most commonly used is polyolefin products. As one of the three major plastics, polyethylene is widely used in food packaging bags, garbage bags, preservative films, cold chain transportation and other fields.

[0004] However, polyethylene and its products do not have antibacterial properties. There are two common antibacterial solutions at present, one is to add antibacterial materials to the film products, and the other is to make antibacterial film layer and composite antibacterial film products.

[0005] However, the existing antibacterial materials have the problems of poor antibacterial effect and long-term antibacterial effect, and the composite antibacterial film has the problems of poor strength, poor barrier property and poor break resistance. SUMMARY

[0006] In order to solve the above problems, the present application provides a preparation method of a bacteriostatic high-strength high-barrier break-resistant food packaging film.

[0007] A bacteriostatic high-strength high-barrier break-resistant food packaging film includes a polyethylene surface layer 1, a first maleic anhydride high-strength adhesive layer 2, a high-barrier first polyamide layer 3, an ethylene-vinyl alcohol copolymer layer 4, a high-barrier second polyamide layer 5, a second maleic anhydride high-strength adhesive layer 6, and a polyethylene antibacterial inner layer 7. The preparation method is specifically completed by the following steps:

[0008] I. Preparation of composite antibacterial agent:

[0009] ①, disperse prussian blue into anhydrous ethanol to obtain a prussian blue dispersion liquid; add silver nitrate solution to the prussian blue dispersion liquid, stir at room temperature for a period of time, then centrifuge, collect the precipitate, wash and dry to obtain a silver / prussian blue composite;

[0010] ②, the silver / prussian blue complex is mixed with an aqueous solution of Zn(NO3)2.6(H2O) uniformly, then a dimethyl imidazole methanol solution is added, stirring for a period of time, then centrifuging, collecting the precipitate, washing, drying, to obtain silver / prussian blue loaded metal organic framework;

[0011] ③, Nd(NO3)3·6H2O is added to the tannic acid aqueous solution, stirring, centrifuging, collecting the precipitate,

[0012] washing, drying, to obtain Nd 3+ loaded tannic acid;

[0013] ④, chitosan is dispersed in an acetic acid solution with a mass fraction of 1-3%, then glutaraldehyde is added, heating and stirring at 40-60 DEG C for a period of time, then Nd 3+ loaded tannic acid is added, heating and stirring for a period of time, finally drying, to obtain chitosan-tannic acid composite material;

[0014] ⑤, the silver / prussian blue loaded metal organic framework and the chitosan-tannic acid composite material are dispersed in anhydrous ethanol, stirring, finally freeze-drying, to obtain a composite antibacterial agent;

[0015] II, polyethylene and the composite antibacterial agent are mixed uniformly according to a weight ratio of (90-95):(5-8), to obtain a polyethylene antibacterial inner layer masterbatch;

[0016] III, polyethylene, maleic anhydride grafted modified polyethylene, polyamide, ethylene-vinyl alcohol copolymer, polyamide, maleic anhydride grafted modified polyethylene, and the polyethylene antibacterial inner layer masterbatch are placed in the 1#, 2#, 3#, 4#, 5#, 6#, and 7# hopper of a seven-layer co-extrusion molding machine, the 1#, 2#, 3#, 4#, 5#, 6#, and 7# extruders are started synchronously, co-extrusion, downward blowing, and film casting are carried out, to obtain, in sequence, a polyethylene surface layer 1, a first maleic anhydride high-strength adhesive layer 2, a high-barrier first polyamide layer 3, an ethylene-vinyl alcohol copolymer layer 4, a high-barrier second polyamide layer 5, a second maleic anhydride high-strength adhesive layer 6, and a polyethylene antibacterial inner layer 7, i.e., a seven-layer composite structure of a bacteriostatic high-strength high-barrier food packaging film.

[0017] Principles and advantages of the present application:

[0018] I, the first maleic anhydride high-strength adhesive layer 2 and the second maleic anhydride high-strength adhesive layer 6 are maleic anhydride grafted modified polyethylene; the first maleic anhydride high-strength adhesive layer 2 can bond the polyethylene surface layer 1 and the high-barrier first polyamide layer 3 together;

[0019] The second maleic anhydride high-strength adhesive layer 6 can bond the high-barrier second polyamide layer 5 and the polyethylene antibacterial inner layer 7 together;

[0020] II. The high-barrier first polyamide (PA) layer 3 and the high-barrier second polyamide (PA) layer 5 have strong barrier properties and puncture resistance.

[0021] 3. The ethylene-vinyl alcohol copolymer (EVOH) layer 4 is a high barrier layer, especially with high oxygen barrier properties, with an oxygen barrier value of 1.0-1.5 ml / m.24h.23ac.53%RH;

[0022] IV. The high-barrier first polyamide (PA) layer 3 and the high-barrier second polyamide (PA) layer 5 work together to improve barrier performance and puncture resistance, while improving the smoothness of the co-extruded film and reducing curling.

[0023] V. The antibacterial inner layer of polyethylene (7) is made of metallocene polyethylene with added composite antibacterial agent, which has a better low temperature heat sealing effect and softness and toughness, realizes the low temperature and high strength heat sealing effect in the co-extruded film bag making process, improves the overall strength of the co-extruded film, and has antibacterial and mildew-proof properties with good hygiene performance.

[0024] VI. This invention utilizes tannic acid to support Nd 3+ Nd 3+ It has a strong antibacterial effect against Escherichia coli, and the phenolic hydroxyl groups of tannic acid can be used to load more Nd. 3+ Then, chitosan and supported Nd 3+ Using tannic acid as a monomer and glutaraldehyde as a crosslinking agent, a chitosan-tannic acid composite material was obtained, which increased the antibacterial properties and long-lasting antibacterial effect of the chitosan-tannic acid composite material.

[0025] VII. This invention effectively combines the silver / Prussian blue complex with the metal-organic framework, promoting the release of antibacterial particles within the metal-organic framework and inhibiting the growth and reproduction of bacteria.

[0026] 8. This invention combines a silver / Prussian blue-loaded metal-organic framework with a chitosan-tannic acid composite material, which enhances the antibacterial effect and effectively avoids the problem of the antibacterial agent concentration decreasing and the antibacterial effect not lasting due to long-term storage. The antibacterial, high-strength, high-barrier, and puncture-resistant food packaging film prepared by this invention has spectral antibacterial properties, is harmless to the human body, and can extend the shelf life of food.

[0027] 9. This invention can meet the high barrier requirements for liquids such as drinking water, family-packaged fruit juice, alcoholic beverages, and pharmaceuticals, as well as the requirements for aseptic preservation, thereby improving the shelf life of packaged liquids.

[0028] This invention provides a high-strength, high-barrier, and tear-resistant food packaging film with antibacterial properties. Attached Figure Description

[0029] Figure 1A schematic diagram of the structure of the bacteriostatic high-strength high-barrier puncture-resistant food packaging film according to the embodiment 1, wherein 1 is a polyethylene surface layer, 2 is a first maleic anhydride high-strength adhesive layer, 3 is a high-barrier first polyamide layer, 4 is an ethylene-vinyl alcohol copolymer layer, 5 is a high-barrier second polyamide layer, 6 is a second maleic anhydride high-strength adhesive layer, and 7 is a polyethylene antibacterial inner layer. DETAILED DESCRIPTION

[0030] Specific embodiment one: the preparation method of the bacteriostatic high-strength high-barrier puncture-resistant food packaging film according to the embodiment, characterized in that the bacteriostatic high-strength high-barrier puncture-resistant food packaging film comprises a polyethylene surface layer 1, a first maleic anhydride high-strength adhesive layer 2, a high-barrier first polyamide layer 3, an ethylene-vinyl alcohol copolymer layer 4, a high-barrier second polyamide layer 5, a second maleic anhydride high-strength adhesive layer 6, and a polyethylene antibacterial inner layer 7. The preparation method is specifically completed according to the following steps:

[0031] I. Preparation of composite antibacterial agent:

[0032] ①, disperse Prussian blue into anhydrous ethanol to obtain a Prussian blue dispersion liquid; add a silver nitrate solution to the Prussian blue dispersion liquid, stir at room temperature for a period of time, then centrifuge, collect the precipitate, wash and dry to obtain a silver / Prussian blue composite;

[0033] ②, mix the silver / Prussian blue composite with an aqueous solution of Zn(NO3)2.6(H2O) uniformly, then add a dimethylimidazole methanol solution, stir for a period of time, then centrifuge, collect the precipitate, wash and dry to obtain a silver / Prussian blue metal-organic framework;

[0034] ③, add Nd(NO3)3·6H2O to a tannic acid aqueous solution, stir and react, centrifuge, collect the precipitate,

[0035] wash and dry to obtain a Nd 3+ -loaded tannic acid;

[0036] ④, disperse chitosan into an acetic acid solution with a mass fraction of 1% to 3%, then add glutaraldehyde, heat and stir at 40°C to 60°C for a period of time, then add the Nd 3+ -loaded tannic acid, heat and stir for a period of time, and finally dry to obtain a chitosan-tannic acid composite material;

[0037] ⑤, disperse the silver / Prussian blue metal-organic framework and the chitosan-tannic acid composite material into anhydrous ethanol, stir and react, and finally freeze-dry to obtain a composite antibacterial agent;

[0038] II. Mix polyethylene and the composite antibacterial agent uniformly according to a weight ratio of (90-95):(5-8) to obtain a polyethylene antibacterial inner layer masterbatch;

[0039] III. Put the polyethylene, maleic anhydride grafted modified polyethylene, polyamide, ethylene-vinyl alcohol copolymer, polyamide, maleic anhydride grafted modified polyethylene, polyethylene antibacterial inner layer masterbatch into the hopper of the 1#, 2#, 3#, 4#, 5#, 6#, 7# extruder of the seven-layer co-extrusion molding machine group, start 1#, 2#, 3#, 4#, 5#, 6#, 7# extruders synchronously, co-extrude, blow down, and film cast to obtain polyethylene surface layer 1, first maleic anhydride high-strength adhesive layer 2, high-barrier first polyamide layer 3, ethylene-vinyl alcohol copolymer layer 4, high-barrier second polyamide layer 5, second maleic anhydride high-strength adhesive layer 6, and polyethylene antibacterial inner layer 7 in sequence, that is, a seven-layer composite structure of bacteriostatic high-strength high-barrier food packaging film.

[0040] Specific embodiment two: the difference between this embodiment and specific embodiment one is that the concentration of the Prussian blue dispersion solution in step one ① is 3g / L-8g / L; the concentration of the silver nitrate solution in step one ① is 0.1mol / L-0.2mol / L; the volume ratio of the silver nitrate solution to the Prussian blue dispersion solution in step one ① is (0.2-0.5):(15-20); the stirring time at room temperature in step one ① is 1h-2h; the washing is sequentially using deionized water and anhydrous ethanol for 3-5 times respectively; the drying temperature is 50℃-70℃, and the drying time is 5h-7h. The other steps are the same as specific embodiment one.

[0041] Specific embodiment three: the difference between this embodiment and one of specific embodiment one or two is that the concentration of the Zn(NO3)2.6(H2O) aqueous solution in step one ② is 0.8mol / L-1mol / L; the concentration of the dimethyl imidazole methanol solution in step one ② is 0.05mol / L-0.1mol / L; the volume ratio of the silver / Prussian blue composite to the Zn(NO3) · 6(H2O) aqueous solution in step one ② is 1g:(20mL-40mL); the volume ratio of the Zn(NO3) · 6(H2O) aqueous solution to the dimethyl imidazole methanol solution in step one ② is (20mL-40mL):(40mL-80mL); the stirring reaction time in step one ② is 2h-3h; the washing in step one ② is sequentially using deionized water and anhydrous ethanol for 3-5 times respectively; the drying temperature is 50℃-70℃, and the drying time is 5h-7h. The other steps are the same as specific embodiment one or two.

[0042] Specific embodiment four: the difference between this embodiment and one of the specific embodiments one to three is that the molar ratio of Nd(NO3)3.6H2O to tannic acid in the aqueous solution of tannic acid in step 1③ is 1:1; the mass of tannic acid to the volume of water in the aqueous solution of tannic acid in step 1③ is (2g-5g):10mL; the stirring reaction time in step 1③ is 3h-5h; the washing is sequentially using deionized water and anhydrous ethanol for 3-5 times respectively; the drying temperature is 50℃-70℃, and the drying time is 5h-7h. The other steps are the same as specific embodiments one to three.

[0043] Specific embodiment five: the difference between this embodiment and one of the specific embodiments one to four is that the mass of chitosan to the volume of 1%-3% acetic acid solution in step 1④ is 1g:(20mL-40mL); the mass of chitosan to the volume of glutaraldehyde in step 1④ is 1g:(0.8mL-1.2mL); the mass ratio of chitosan to tannic acid loaded with Nd 3+ in step 1④ is 1:(0.6-0.8); the heating and stirring time in step 1④ is 2h-3h; the tannic acid loaded with Nd 3+ is added in step 1④, and the heating and stirring time is 2h-3h; the drying temperature is 50℃-70℃, and the drying time is 5h-7h. The other steps are the same as specific embodiments one to four.

[0044] Specific embodiment six: the difference between this embodiment and one of the specific embodiments one to five is that the mass ratio of silver / prussian blue loaded metal-organic framework to chitosan-tannic acid composite material in step 1⑤ is (0.05-0.1):1; the mass of chitosan-tannic acid composite material to the volume of anhydrous ethanol in step 1⑤ is (2g-5g):50mL; the stirring reaction time in step 1⑤ is 20min-40min. The other steps are the same as specific embodiments one to five.

[0045] Specific embodiment seven: the difference between this embodiment and one of the specific embodiments one to six is that the thickness of the polyethylene surface layer 1 is 50μm-100μm; the thickness of the first maleic anhydride high-strength adhesive layer 2 is 10μm-20μm. The other steps are the same as specific embodiments one to six.

[0046] Specific embodiment eight: the difference between this embodiment and one of the specific embodiments one to seven is that the thickness of the high-barrier first polyamide layer 3 is 15μm-20μm; the thickness of the ethylene-vinyl alcohol copolymer layer 4 is 15μm-20μm. The other steps are the same as specific embodiments one to seven.

[0047] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that the thickness of the high barrier second polyamide layer 5 is 15 μm-20 μm; the thickness of the second maleic anhydride high-strength adhesive layer 6 is 10 μm-20 μm. The other steps are the same as specific embodiments one to eight.

[0048] Specific embodiment ten: the difference between this embodiment and one of the specific embodiments one to nine is that the thickness of the polyethylene antibacterial inner layer 7 is 80 μm-120 μm. The other steps are the same as specific embodiments one to nine.

[0049] The beneficial effects of the present application are verified by the following examples:

[0050] Example 1: a bacteriostatic high-strength high-barrier food packaging film includes a polyethylene surface layer 1, a first maleic anhydride high-strength adhesive layer 2, a high-barrier first polyamide layer 3, an ethylene-vinyl alcohol copolymer layer 4, a high-barrier second polyamide layer 5, a second maleic anhydride high-strength adhesive layer 6, and a polyethylene antibacterial inner layer 7. The preparation method is specifically completed by the following steps:

[0051] I. Preparation of composite antibacterial agent:

[0052] ①, Prussian blue is dispersed in anhydrous ethanol to obtain a Prussian blue dispersion liquid; silver nitrate solution is added to the Prussian blue dispersion liquid, stirred at room temperature for 2 h, then centrifuged, the precipitate is collected, then deionized water and anhydrous ethanol are used to clean 3 times respectively, and finally dried at 60°C for 5h to obtain a silver / Prussian blue composite;

[0053] The concentration of the Prussian blue dispersion liquid in step one ① is 5g / L;

[0054] The concentration of the silver nitrate solution in step one ① is 0.1mol / L;

[0055] The volume ratio of the silver nitrate solution to the Prussian blue dispersion liquid in step one ① is 0.2:20;

[0056] ②, the silver / Prussian blue composite is mixed with an aqueous solution of Zn(NO3)2.6(H2O) uniformly, then dimethyl imidazole methanol solution is added, stirred for 2h, then centrifuged, the precipitate is collected, then deionized water and anhydrous ethanol are used to clean 3 times respectively, and finally dried at 60°C for 5h to obtain a silver / Prussian blue metal organic framework;

[0057] The concentration of the aqueous solution of Zn(NO3)2.6(H2O) in step one ② is 0.8mol / L;

[0058] The concentration of the dimethyl imidazole methanol solution in step one ② is 0.08mol / L;

[0059] The volume ratio of the aqueous solution of Zn(NO3) · 6(H2O) to the methanol solution of dimethylimidazole is 20 mL:40 mL;

[0060] The volume ratio of the aqueous solution of Zn(NO3) · 6(H2O) to the methanol solution of dimethylimidazole is 20 mL:40 mL;

[0061] ③, Nd(NO3)3·6H2O was added to the aqueous solution of tannic acid, stirred for 3 h, centrifuged, and the precipitate was collected and washed with deionized water and anhydrous ethanol for 3 times respectively, and dried at 60℃ for 5 h to obtain the tannic acid loaded with Nd 3+ ;

[0062] The molar ratio of Nd(NO3)3·6H2O to tannic acid in the aqueous solution of tannic acid in step 1③ is 1:1; the mass of tannic acid in the aqueous solution of tannic acid in step 1

[0063] ③ is 3g:10mL;

[0064] ④, chitosan was dispersed in an acetic acid solution with a mass fraction of 3%, then glutaraldehyde was added, heated and stirred at 40℃-60℃ for 2 h, then the tannic acid loaded with Nd 3+ was added, heated and stirred for 2 h, and finally dried at 60℃ for 5 h to obtain a chitosan-tannic acid composite material;

[0065] The volume ratio of chitosan to the acetic acid solution with a mass fraction of 3% in step 1④ is 1g:40mL;

[0066] The volume ratio of chitosan to glutaraldehyde in step 1④ is 1g:1mL;

[0067] The mass ratio of chitosan to the tannic acid loaded with Nd 3+ in step 1④ is 1:0.7;

[0068] ⑤, the silver / prussian blue loaded metal organic framework and the chitosan-tannic acid composite material were dispersed in anhydrous ethanol, stirred for 30 min, and finally freeze-dried to obtain a composite antibacterial agent;

[0069] The mass ratio of the silver / prussian blue loaded metal organic framework to the chitosan-tannic acid composite material in step 1⑤ is 0.08:1;

[0070] The volume ratio of the chitosan-tannic acid composite material to anhydrous ethanol in step 1⑤ is 5g:50mL;

[0071] II. The high-density polyethylene and the composite antibacterial agent are mixed uniformly according to a weight ratio of 95:5 to obtain a high-density polyethylene antibacterial inner layer masterbatch;

[0072] III. The high-density polyethylene, maleic anhydride grafted modified polyethylene, PA6, ethylene-vinyl alcohol copolymer, PA6, maleic anhydride grafted modified polyethylene, high-density polyethylene antibacterial inner layer masterbatch are placed in the hoppers of the 1st, 2nd, 3rd, 4th, 5th, 6th and 7th extruders of a seven-layer co-extrusion molding machine, and the 1st, 2nd, 3rd, 4th, 5th, 6th and 7th extruders are started synchronously to perform co-extrusion, downward blowing and film casting to obtain, in sequence, a polyethylene surface layer 1, a first maleic anhydride high-strength adhesive layer 2, a high-barrier first polyamide layer 3, an ethylene-vinyl alcohol copolymer layer 4, a high-barrier second polyamide layer 5, a second maleic anhydride high-strength adhesive layer 6 and a polyethylene antibacterial inner layer 7, i.e. a seven-layer composite structure of a bacteriostatic high-strength high-barrier food packaging film;

[0073] In step III, the temperature of the 1st extruder barrel is controlled at 220-260℃; the temperature of the 2nd extruder barrel is controlled at 210-230℃; the temperature of the 3rd extruder barrel is controlled at 230-280℃; the temperature of the 4th extruder barrel is controlled at 200-240℃; the temperature of the 5th extruder barrel is controlled at 230-280℃; the temperature of the 6th extruder barrel is controlled at 210-230℃; and the temperature of the 7th extruder barrel is controlled at 220-260℃.

[0074] In step III, the thickness of the polyethylene surface layer 1 is 80μm.

[0075] In step III, the thickness of the first maleic anhydride high-strength adhesive layer 2 is 13μm.

[0076] In step III, the thickness of the high-barrier first polyamide layer 3 is 15μm.

[0077] In step III, the thickness of the ethylene-vinyl alcohol copolymer layer 4 is 16μm.

[0078] In step III, the thickness of the high-barrier second polyamide layer 5 is 15μm.

[0079] In step III, the thickness of the second maleic anhydride high-strength adhesive layer 6 is 13μm.

[0080] In step III, the thickness of the polyethylene antibacterial inner layer 7 is 120μm.

[0081] Comparative Example 1: The difference between this example and Example 1 is that no chitosan-tannin composite material is prepared in Comparative Example 1, i.e. the composite antibacterial agent in step I is silver / prussian blue supported metal-organic framework. The other steps and parameters are the same as those in Example 1.

[0082] The difference between this example and example 1 is that the silver / prussian blue loaded metal organic framework is not prepared in comparative example 1, that is, the composite antibacterial agent in step one is chitosan-tannin composite. The other steps and parameters are the same as those in example 1.

[0083] The tensile yield stress and tensile fracture nominal strain of the seven-layer composite structure antibacterial high-strength high-barrier puncture-resistant food packaging film prepared in example 1 were tested according to the method of national standard GB / T1040.2-2006. The results show that the tensile yield stress of the seven-layer composite structure antibacterial high-strength high-barrier puncture-resistant food packaging film prepared in example 1 is 15.2 MPa, and the tensile fracture nominal strain is 620%.

[0084] The inhibitory activity of polyethylene antibacterial inner layer 7 in the seven-layer composite structure antibacterial high-strength high-barrier puncture-resistant food packaging film prepared in example 1 on escherichia coli and staphylococcus aureus was tested according to the film pasting method in national standard GB / T21510-2008, and the inhibitory activity after soaking in water for one month was also tested.

[0085] The inhibitory activity of polyethylene antibacterial inner layer 7 in the seven-layer composite structure antibacterial high-strength high-barrier puncture-resistant food packaging film prepared in comparative example 1 on escherichia coli and staphylococcus aureus was tested according to the film pasting method in national standard GB / T21510-2008, and the inhibitory activity after soaking in water for one month was also tested.

[0086] The inhibitory activity of polyethylene antibacterial inner layer 7 in the seven-layer composite structure antibacterial high-strength high-barrier puncture-resistant food packaging film prepared in comparative example 2 on escherichia coli and staphylococcus aureus was tested according to the film pasting method in national standard GB / T21510-2008, and the inhibitory activity after soaking in water for one month was also tested.

[0087] The above experimental data are shown in table 1.

[0088] Table 1

[0089]

[0090] From table 1, it can be seen that the silver / prussian blue loaded metal organic framework is compounded with chitosan-tannin composite in the present application, which achieves antibacterial effect, and can effectively avoid the problem of antibacterial agent concentration decrease and antibacterial effect durability caused by long-term storage of antibacterial agent. The antibacterial high-strength high-barrier puncture-resistant food packaging film prepared in the present application has spectral antibacterial performance, is harmless to human body, and can prolong the shelf life of food.

Claims

1. A process for the preparation of a bacteriostatic, high-strength, high-barrier, puncture-resistant food packaging film, characterized by The bacteriostatic high-strength high-barrier puncture-resistant food packaging film comprises a polyethylene surface layer (1), a first maleic anhydride high-strength adhesive layer (2), a high-barrier first polyamide layer (3), an ethylene-vinyl alcohol copolymer layer (4), a high-barrier second polyamide layer (5), a second maleic anhydride high-strength adhesive layer (6), and a polyethylene antibacterial inner layer (7), and the preparation method is specifically completed according to the following steps: I. Preparation of composite antibacterial agent: ①, disperse Prussian blue in anhydrous ethanol to obtain a Prussian blue dispersion liquid; add silver nitrate solution to the Prussian blue dispersion liquid, stir at room temperature for a period of time, then centrifuge, collect the precipitate, wash and dry to obtain a silver / Prussian blue composite; ②, uniformly mix the silver / Prussian blue composite with an aqueous solution of Zn(NO3)2·6H2O, then add a dimethyl imidazole methanol solution, stir for a period of time, then centrifuge, collect the precipitate, wash and dry to obtain a silver / Prussian blue loaded metal organic framework; iii. Nd(NO3)3.6H2O was added to the aqueous solution of tannic acid, the reaction was stirred, centrifuged, the precipitate was collected, washed, and dried to obtain Nd-loaded tannic acid; 3+ iii. Nd(NO3)3.6H2O was added to the aqueous solution of tannic acid, the reaction was stirred, centrifuged, the precipitate was collected, washed, and dried to obtain Nd-loaded tannic acid; IV. The chitosan is dispersed into acetic acid solution with mass fraction of 1%~3%, then glutaraldehyde is added, heated and stirred for a period of time at 40℃~60℃, then Nd 3+ tannic acid is added, heated and stirred for a period of time, and finally dried to obtain chitosan-tannic acid composite material; ⑤, disperse the silver / Prussian blue loaded metal organic framework and chitosan-tannic acid composite material in anhydrous ethanol, stir and react, and finally freeze-dry to obtain a composite antibacterial agent; The mass ratio of the silver / Prussian blue loaded metal organic framework to the chitosan-tannic acid composite material in step I ⑤ is (0.05-0.1):1; II. Mix polyethylene and the composite antibacterial agent according to a weight ratio of (90-95):(5-8) to obtain a polyethylene antibacterial inner layer masterbatch; III. Put polyethylene, maleic anhydride grafted modified polyethylene, polyamide, ethylene-vinyl alcohol copolymer, polyamide, maleic anhydride grafted modified polyethylene, and the polyethylene antibacterial inner layer masterbatch into the 1#, 2#, 3#, 4#, 5#, 6# and 7# hopper of a seven-layer co-extrusion molding machine, simultaneously start the 1#, 2#, 3#, 4#, 5#, 6# and 7# extruders, co-extrude, blow down and film to obtain, in sequence, the polyethylene surface layer (1), the first maleic anhydride high-strength adhesive layer (2), the high-barrier first polyamide layer (3), the ethylene-vinyl alcohol copolymer layer (4), the high-barrier second polyamide layer (5), the second maleic anhydride high-strength adhesive layer (6), and the polyethylene antibacterial inner layer (7), which is a seven-layer composite structure bacteriostatic high-strength high-barrier puncture-resistant food packaging film; The thickness of the polyethylene surface layer (1) in step III is 50-100 μm; the thickness of the first maleic anhydride high-strength adhesive layer (2) is 10-20 μm; the thickness of the high-barrier first polyamide layer (3) is 15-20 μm; the thickness of the ethylene-vinyl alcohol copolymer layer (4) is 15-20 μm; the thickness of the high-barrier second polyamide layer (5) is 15-20 μm; the thickness of the second maleic anhydride high-strength adhesive layer (6) is 10-20 μm; and the thickness of the polyethylene antibacterial inner layer (7) is 80-120 μm.

2. The preparation method of the bacteriostatic high-strength high-barrier puncture-resistant food packaging film according to claim 1, characterized in that The concentration of the Prussian blue dispersion liquid in step 1-1 is 3 g / L-8 g / L; the concentration of the silver nitrate solution in step 1-1 is 0.1 mol / L-0.2 mol / L; the volume ratio of the silver nitrate solution to the Prussian blue dispersion liquid in step 1-1 is (0.2-0.5):(15-20); the stirring time at room temperature in step 1-1 is 1 h-2 h; the washing is sequentially using deionized water and anhydrous ethanol for 3-5 times; and the drying temperature is 50°C-70°C, and the drying time is 5 h-7 h.

3. The preparation method of the bacteriostatic high-strength high-barrier break-resistant food packaging film according to claim 1, characterized in that The concentration of the Zn(NO3)2·6H2O aqueous solution in step 1-2 is 0.8 mol / L-1 mol / L; the concentration of the dimethyl imidazole methanol solution in step 1-2 is 0.05 mol / L-0.1 mol / L; the mass of the silver / Prussian blue composite to the volume of the Zn(NO3)2·6H2O aqueous solution in step 1-2 is 1 g:(20 mL-40 mL); the volume ratio of the Zn(NO3)2·6H2O aqueous solution to the dimethyl imidazole methanol solution in step 1-2 is (20 mL-40 mL):(40 mL-80 mL); the stirring reaction time in step 1-2 is 2 h-3 h; the washing in step 1-2 is sequentially using deionized water and anhydrous ethanol for 3-5 times; and the drying temperature is 50°C-70°C, and the drying time is 5 h-7 h.

4. The preparation method of the bacteriostatic high-strength high-barrier puncture-resistant food packaging film according to claim 1, characterized in that The molar ratio of Nd(NO3)3·6H2O to tannic acid in the tannic acid aqueous solution in step 1-3 is 1:1; the volume ratio of the mass of tannic acid to water in the tannic acid aqueous solution in step 1-3 is (2 g-5 g):10 mL; the stirring reaction time in step 1-3 is 3 h-5 h; the washing is sequentially using deionized water and anhydrous ethanol for 3-5 times; and the drying temperature is 50°C-70°C, and the drying time is 5 h-7 h.

5. The preparation method of the bacteriostatic high-strength high-barrier puncture-resistant food packaging film according to claim 1, characterized in that The volume ratio of the mass of chitosan to the volume of 1%~3% acetic acid solution in step one ④ is 1g:(20mL~40mL); the volume ratio of the mass of chitosan to the volume of glutaraldehyde in step one ④ is 1g:(0.8mL~1.2mL); the mass ratio of chitosan to tannic acid loaded with Nd 3+ in step one ④ is 1:(0.6~0.8); the heating and stirring time in step one ④ is 2h~3h; the tannic acid loaded with Nd 3+ in step one ④ is added, and the heating and stirring time is 2h~3h; the drying temperature is 50℃~70℃, and the drying time is 5h~7h.

6. The preparation method of the bacteriostatic high-strength high-barrier puncture-resistant food packaging film according to claim 1, characterized in that The volume ratio of the mass of the chitosan-tannic acid composite material to anhydrous ethanol in step 1-5 is (2 g-5 g):50 mL; and the stirring reaction time in step 1-5 is 20 min-40 min.

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