Radiation refrigeration antibacterial composite film and preparation method thereof

Abstract

The invention discloses a radiation refrigeration antibacterial composite film and a preparation method thereof, and the preparation method comprises the following steps: mixing deionized water and acetone to obtain a mixed solvent; uniformly stirring cellulose acetate, ethylene glycol, polyhexamethylene guanidine hydrochloride and the mixed solvent to obtain a mixed solution; and drying the mixed solution to obtain the radiation refrigeration antibacterial composite film. The composite film prepared by the invention not only has excellent radiation refrigeration performance and mechanical properties, but also has long-acting antibacterial ability and antioxidant ability, the radiation refrigeration effect of the composite film does not depend on additionally doped nanoparticles, the environmental pressure is small, and the composite film has wide popularization value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of temperature-controlled packaging, in particular to a radiation refrigeration antibacterial composite film and a preparation method thereof. BACKGROUND

[0002] Grains are prone to spoilage under solar radiation and high temperature conditions during production, transportation and storage, resulting in loss or waste of grains, especially perishable foods such as fruits, vegetables, aquatic products and meat. Although cold chain transportation can effectively extend the shelf life of food, traditional refrigeration methods have high energy consumption, heavy environmental pollution and high requirements for facilities. Therefore, it is particularly important to develop more green and low-energy food packaging technologies.

[0003] Among many advanced strategies, passive radiation refrigeration has attracted much attention due to its ability to cool without external energy. Related materials can reduce heat absorption by efficiently reflecting solar radiation (0.3-2.5 μm) and radiate internal heat to the outside through the atmospheric window (8-13 μm). Currently, passive radiation refrigeration materials mainly include biomimetic structures, phase change materials and engineered structural materials. Many radiation refrigeration materials rely on nanoparticles, for example, patent CN119081174A uses cellulose acetate (BSCA) as a substrate to prepare a radiation refrigeration film, and barium sulfate is doped therein to improve the radiation refrigeration effect. However, nanoparticles are not easily degradable, and the use of such composite films in large quantities will obviously burden the environment.

[0004] At the same time, in each link of the supply chain, microorganisms can accelerate food spoilage, damage sensory quality and increase the risk of foodborne diseases. In addition, ultraviolet barrier and antioxidant properties are also crucial for extending the shelf life of food. Therefore, it is necessary to design a sustainable packaging material that has both radiation refrigeration effect and antibacterial and antioxidant capacity. SUMMARY

[0005] One object of the present application is to provide a preparation method of a radiation refrigeration antibacterial composite film, which is simple in process, conducive to industrialized scale production, and the radiation refrigeration effect of the radiation refrigeration antibacterial composite film prepared thereby does not depend on additional doped nanoparticles, is conducive to degradation and reduces environmental pressure, and the composite film can release polyhexamethylene guanidine hydrochloride, realize long-acting antibacterial and antioxidant, and has wide popularization value.

[0006] The present application is realized by the following technical solutions:

[0007] A preparation method of a radiation refrigeration antibacterial composite film, comprising the following steps:

[0008] Mixing deionized water and acetone to obtain a mixed solvent;

[0009] The cellulose acetate, ethylene glycol, polyhexamethylene guanidine hydrochloride and the mixed solvent are stirred uniformly to obtain a mixed solution;

[0010] The mixed solution is dried to obtain the radiation refrigeration antibacterial composite film.

[0011] In the technical solution, the mixed solvent is composed of deionized water and acetone. In the subsequent drying process, the acetone and deionized water in the mixed solvent have different volatilization speeds, so that the composite film has a uniform porous structure.

[0012] Next, the prepared mixed solvent is mixed with cellulose acetate, ethylene glycol and polyhexamethylene guanidine hydrochloride, and stirred uniformly to obtain a mixed solution. The mixed solvent is dried to obtain a radiation refrigeration antibacterial composite film based on cellulose acetate, ethylene glycol and polyhexamethylene guanidine hydrochloride.

[0013] In the ternary system of the radiation refrigeration antibacterial composite film, cellulose acetate is abundant, easy to process and degradable. Its fast solubility and easy film-forming property can form a composite film with excellent performance. Based on the mixed solvent, a porous structure is formed, the pore size of which is comparable to the wavelength of sunlight, so that strong Mie scattering can be generated, realizing efficient sunlight backscattering and excellent optical performance. Polyhexamethylene guanidine hydrochloride (PHMG) is a bactericide widely used for food equipment disinfection, fruit and vegetable cleaning and skin disinfection. It has the characteristics of high bactericidal efficiency, no irritation and environmental friendliness. In the composite film system, polyhexamethylene guanidine hydrochloride can endow the composite film with excellent antibacterial performance and antioxidant capacity without changing the porous structure of the composite film.

[0014] In the technical solution, ethylene glycol plays a role in linking each component and improving the performance of the composite film. Specifically, the hydrogen bond interaction between ethylene glycol and cellulose acetate can effectively improve the toughness and mechanical properties of the composite film. At the same time, the dispersion and occupation of ethylene glycol, as well as its interaction with deionized water can effectively increase the size of the pore size, increase the thickness of the composite film, and make the porous structure more uniform, effectively improving the radiation refrigeration performance and ultraviolet blocking ability of the composite film. Moreover, the hydroxyl group in ethylene glycol can form a hydrogen bond with the amino group in polyhexamethylene guanidine hydrochloride. The interaction between hydrogen bonds can effectively slow down the release of polyhexamethylene guanidine hydrochloride, thereby enhancing the long-acting antibacterial property of the composite film and eliminating the toxicity caused by the burst release of polyhexamethylene guanidine hydrochloride.

[0015] As a preferred embodiment of the present application, the preparation method comprises the following steps:

[0016] The deionized water and acetone are mixed to obtain a mixed solvent;

[0017] dissolving cellulose acetate into the mixed solvent to obtain a first mixture;

[0018] adding ethylene glycol into the first solvent to obtain a second mixture;

[0019] adding polyhexamethylene guanidine hydrochloride into the second mixture to obtain a third mixture;

[0020] drying the third mixture to obtain the radiation refrigeration antibacterial composite film.

[0021] In the technical solution, deionized water and acetone are mixed to obtain a mixed solvent, and cellulose acetate is dissolved into the mixed solvent to obtain a first mixture. Ethylene glycol is then added into the first mixture, and the second mixture is obtained after sufficient stirring. Polyhexamethylene guanidine hydrochloride is then added into the second mixture to obtain a third mixture. Finally, the third mixture is dried and solidified at a specific temperature to obtain the radiation refrigeration antibacterial composite film.

[0022] In some preferred embodiments, the drying temperature of the third mixture is 35-55 °C. The drying temperature affects the evaporation speed of acetone and deionized water. Drying the mixed solvent at a specific temperature is conducive to forming a porous structure with a desired size and distribution. Further preferably, the drying temperature is 35-45 °C.

[0023] In some preferred embodiments, when the third mixture is dried, the liquid level of the third mixture is 1-2 mm. It is found through experiments that if the liquid level of the third mixture before film formation is too low, the composite film formed is more prone to defects, but if the liquid level is too high, it is not easy to obtain a porous structure with uniform pore size and distribution. Therefore, in the final drying process, the height of the third mixed liquid is preferably set to 1-2 mm.

[0024] In the technical solution, the performance of the composite film is further improved by optimizing the ratio of each component in the composite film.

[0025] Specifically, in some preferred embodiments, the mass ratio of cellulose acetate to ethylene glycol is 1:1-3:1.

[0026] The cellulose acetate as a film-forming matrix, if its content is too low, it will lead to difficulty in film formation, even if the film is formed, the mechanical properties are poor, but if the content of cellulose acetate is too high, it is not easy to dissolve, which is not conducive to the formation of a porous structure. After adding ethylene glycol, the interaction between ethylene glycol and cellulose acetate can effectively improve the toughness of the composite film, which is conducive to its use as a packaging material. Through experiments, it is found that when the mass ratio of cellulose acetate to ethylene glycol is 3:1, the morphology, tensile strength and toughness of the composite film are the most ideal, further increasing the amount of cellulose acetate and reducing the amount of ethylene glycol may lead to poor toughness, causing the composite film to be easily broken; and reducing the amount of cellulose acetate and increasing the amount of ethylene glycol will cause some uneven defects on the surface of the composite film. Therefore, in the technical solution, the mass ratio of cellulose acetate to ethylene glycol is set to 1:1~3:1, and more preferably, the mass ratio of cellulose acetate to ethylene glycol is 2:1~3:1.

[0027] Further, the mass ratio of polyhexamethylene guanidine hydrochloride to ethylene glycol is 1:100~1:400.

[0028] The polyhexamethylene guanidine hydrochloride can endow the composite film with antibacterial properties and antioxidant capacity without significantly affecting the mechanical properties and radiation cooling capacity of the composite film. However, if too much polyhexamethylene guanidine hydrochloride is added in the system, there may be food safety problems, and if too little polyhexamethylene guanidine hydrochloride is added, the antibacterial and antioxidant capacity of the composite film will be limited. At the same time, the amount of ethylene glycol can effectively determine the release speed of polyhexamethylene guanidine hydrochloride. In some preferred embodiments, the mass ratio of polyhexamethylene guanidine hydrochloride to ethylene glycol is 1:100~1:400. In more preferred embodiments, the mass ratio of polyhexamethylene guanidine hydrochloride to ethylene glycol is 1:100~1:200.

[0029] Further, the mass ratio of ethylene glycol to deionized water is 1:5~1:10. The interaction between ethylene glycol and deionized water can effectively increase the size of the pore size, thereby increasing the thickness of the composite film. At the same time, ethylene glycol also makes the porous structure more uniform, thereby effectively improving the radiation cooling performance and ultraviolet blocking capacity of the composite film. Therefore, in the technical solution, the mass ratio of ethylene glycol to deionized water is set to 1:5~1:10. Further preferably, the mass ratio of ethylene glycol to deionized water is set to 1:7.5~1:10.

[0030] Further, the volume ratio of the deionized water and the acetone is 1:5-1:15. The mixed solvent forms a porous structure by using the different volatilization speeds of the acetone and the deionized water. When the content of the deionized water is low, it is not easy to form a porous structure, and it is easy to form a dense composite film. When the content of the deionized water is too high, the composite film formed has uneven pore size and uneven pore size distribution. Through experiments, it is found that when the volume ratio of the deionized water and the acetone is 1:5-1:15, the composite film can obtain a more ideal porous structure, thereby effectively improving the radiation cooling performance.

[0031] Another object of the present application is to provide a radiation cooling antibacterial composite film prepared by using any one of the above-mentioned preparation methods of the radiation cooling antibacterial composite film.

[0032] Further, the thickness of the radiation cooling antibacterial composite film is greater than 50 microns.

[0033] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0034] 1. The composite film prepared by the present application not only has excellent radiation cooling performance and mechanical properties, but also has long-term antibacterial ability and antioxidant ability, and the radiation cooling effect is independent of additional doped nanoparticles, the environmental pressure is small, and it has wide popularization value.

[0035] 2. The cellulose acetate, ethylene glycol and polyhexamethylene guanidine hydrochloride composite film system constructed by the present application can effectively improve the toughness and mechanical properties of the composite film through the hydrogen bond interaction between ethylene glycol and cellulose acetate. At the same time, the interaction between ethylene glycol and deionized water can effectively improve the size of the pore diameter, increase the thickness of the composite film, and make the porous structure more uniform, effectively improving the radiation cooling performance and ultraviolet blocking ability of the composite film. Furthermore, the hydrogen bond formed by ethylene glycol and polyhexamethylene guanidine hydrochloride can effectively slow down the release of polyhexamethylene guanidine hydrochloride, thereby enhancing the long-term antibacterial property of the composite film and eliminating the toxicity caused by the burst release of polyhexamethylene guanidine hydrochloride.

[0036] 3. The present application further improves the performance of the composite film by optimizing the ratio of ethylene glycol and each component.

[0037] 4. The preparation process of the present application has mild process conditions, short process steps and low production cost, which is beneficial to industrial scale production. BRIEF DESCRIPTION OF DRAWINGS

[0038] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0039] Figure 1A flow chart of the preparation method in the embodiment of the present application is shown.

[0040] Figure 2 A topography of the composite film in the embodiment of the present application is shown.

[0041] Figure 3 A 3000 times scanning electron microscope image of the cross section of the composite film in the embodiment of the present application is shown.

[0042] Figure 4 A 6000 times scanning electron microscope image of the cross section of the composite film M4 in the embodiment of the present application is shown.

[0043] Figure 5 A radiation cooling diagram of the composite films M1-M4 in the embodiment of the present application is shown.

[0044] Figure 6 A breaking elongation of the composite films M1-M4 in the embodiment of the present application is shown.

[0045] Figure 7 A breaking strength of the composite films M4, M7 and M8 in the embodiment of the present application is shown.

[0046] Figure 8 A UV blocking ability diagram of the composite films M1-M4 in the embodiment of the present application is shown.

[0047] Figure 9 An antibacterial ability of the composite films M1-M4 in the embodiment of the present application is shown.

[0048] Figure 10 An antibacterial ability of the composite films M3, M4, M9 and M10 in the embodiment of the present application is shown.

[0049] Figure 11 A bacterial growth diagram of chicken wrapped with the composite film M4 and the commercially available preservative film D1 respectively for 7 days in the embodiment of the present application is shown.

[0050] Figure 12 An antioxidant performance diagram of the composite films M1-M4 in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical scheme and advantages of the present application clearer, further detailed description will be given below in combination with embodiments and drawings, and the schematic embodiments and their descriptions are only used to explain the present application, and do not limit the present application.

[0052] The sources of all raw materials of the present application are not particularly limited, and they can be purchased on the market or prepared according to conventional methods well known to those skilled in the art. The purity of all raw materials of the present application is not particularly limited, and the present application preferably uses analytical purity or the purity requirements conventional in the packaging field. The trade name and abbreviation of all raw materials of the present application belong to the conventional trade name and abbreviation in the art, and each trade name and abbreviation is clear and explicit in the field of its relevant use. Those skilled in the art can purchase or prepare them by conventional methods according to the trade name, abbreviation and corresponding use.

[0053] The expression of the substituent groups of the present application is not particularly limited, and the expression well known to those skilled in the art is used. Those skilled in the art can correctly understand the meaning thereof according to the expression based on common sense.

[0054] The "first", "second" and the like (for example, first mixture, second mixture and the like) used herein are only for distinguishing the corresponding components for the sake of clarity, and are not intended to limit any order or emphasize importance.

[0055] I. Preparation of the radiation refrigeration antibacterial composite film

[0056] Example 1

[0057] 300 mg of cellulose acetate was added to 10 mL of acetone, stirred at room temperature for 30 minutes to obtain a first mixture, 2.4 mL of the first mixture was taken into a glass culture dish, and dried in an oven at 40 °C to obtain a composite film M1.

[0058] Example 2

[0059] 0.75 mL of deionized water and 9.25 mL of acetone were mixed to obtain a mixed solvent, 300 mg of cellulose acetate was added to the mixed solvent for dissolution, stirred at room temperature for 30 minutes to obtain a first mixture, 2.4 mL of the first mixture was taken into a glass culture dish, and dried in an oven at 40 °C to obtain a composite film M2.

[0060] Example 3

[0061] 0.75 mL of deionized water and 9.25 mL of acetone were mixed to obtain a mixed solvent, 300 mg of cellulose acetate was added to the mixed solvent for dissolution, stirred at room temperature for 20 minutes to obtain a first mixture, then 100 mg of ethylene glycol was added and stirred for 10 minutes to obtain a second mixture, 2.4 mL of the second mixture was taken into a glass culture dish, and dried in an oven at 40 °C to obtain a composite film M3.

[0062] Example 4

[0063] Mix 0.75 mL of deionized water and 9.25 mL of acetone to obtain a mixed solvent, add 300 mg of cellulose acetate to the mixed solvent for dissolution, stir at room temperature for 10 minutes to obtain a first mixture, then add 100 mg of ethylene glycol and continue to stir for 10 minutes to obtain a second mixture, then add 0.5 mg of polyhexamethylene guanidine hydrochloride and stir for 10 minutes to obtain a third mixture, take 2.4 mL of the third mixture into a glass culture dish, and place it in an oven at 40 °C to dry to obtain a composite film M4.

[0064] Example 5

[0065] The preparation method of this example is the same as that of Example 4, except that the amount of ethylene glycol used in this example is 50 mg, i.e. the mass ratio of cellulose acetate to ethylene glycol is 6:1, and the third mixture is dried to obtain a composite film M5.

[0066] Example 6

[0067] The preparation method of this example is the same as that of Example 4, except that the amount of ethylene glycol used in this example is 200 mg, i.e. the mass ratio of cellulose acetate to ethylene glycol is 1.5:1, and the third mixture is dried to obtain a composite film M6.

[0068] Example 7

[0069] The preparation method of this example is the same as that of Example 4, except that 100 mg of glycerol is used to replace 100 mg of ethylene glycol, and finally a composite film M7 is prepared.

[0070] Example 8

[0071] The preparation method of this example is the same as that of Example 4, except that 100 mg of polyethylene glycol is used to replace 100 mg of ethylene glycol, and finally a composite film M8 is prepared.

[0072] Example 9

[0073] The preparation method of this example is the same as that of Example 4, except that the amount of polyhexamethylene guanidine hydrochloride used in this example is 0.25 mg, i.e. the mass ratio of ethylene glycol to polyhexamethylene guanidine hydrochloride is 400:1, and a composite film M9 is prepared.

[0074] Example 10

[0075] The preparation method of this example is the same as that of Example 4, except that the amount of polyhexamethylene guanidine hydrochloride used in this example is 1.0 mg, i.e. the mass ratio of ethylene glycol to polyhexamethylene guanidine hydrochloride is 100:1, and a composite film M10 is prepared.

[0076] Example 11

[0077] The preparation method of this example is the same as that of Example 4, except that the amount of ethylene glycol used in this example is 150 mg, i.e., the mass ratio of cellulose acetate to ethylene glycol is 2:1. After drying the third mixture, a composite film M11 is obtained.

[0078] Example 12

[0079] The preparation method of this example is the same as that of Example 4, except that a mixed solvent composed of 1 mL of deionized water and 15 mL of acetone is used in this example to prepare a composite film M12.

[0080] Example 13

[0081] The preparation method of this example is the same as that of Example 4, except that a mixed solvent composed of 1 mL of deionized water and 10 mL of acetone is used in this example to prepare a composite film M13.

[0082] II. Performance test of the radiation refrigeration antibacterial composite film

[0083] Example 14

[0084] In this example, the surface topography of multiple composite films is collected.

[0085] As shown in Figure 2 , the composite film M1 with only cellulose acetate is transparent. The composite film M4 composed of ethylene glycol, cellulose acetate, and polyhexamethylene guanidine hydrochloride is white, and the surface of M4 is flat.

[0086] After adjusting the ratio of cellulose acetate and ethylene glycol in the ternary system, as shown in the figure, when the amount of cellulose acetate is too large, the composite film M5 has a white surface and no defects, but the toughness is poor and it is easy to break. After reducing the amount of cellulose acetate and increasing the proportion of ethylene glycol, the composite film M6 also has good toughness, but the surface has uneven defects.

[0087] After adjusting the components in the ternary system, as shown in the figure, the composite film M7 using glycerol instead of ethylene glycol has a transparent area on the surface. The surface of the composite film M8 using polyethylene glycol instead of ethylene glycol also presents uneven defects with obvious cracks.

[0088] It can be seen that the system composed of cellulose acetate, ethylene glycol, and polyhexamethylene guanidine hydrochloride can obtain better topography. At the same time, the ratio of cellulose acetate and ethylene glycol determines the hydrogen bond interaction between them, which further affects the toughness and mechanical properties of the composite film.

[0089] Example 15

[0090] In this embodiment, the cross-section of the composite films M1-M4 was photographed by scanning electron microscopy.

[0091] As shown in Figure 3 and Figure 4 , the composite film M1 using only acetone as the solvent has a very dense structure, not a porous structure, which is obviously not conducive to radiation cooling. After using a mixture of water and acetone as the solvent, the composite film M2 can obtain a porous structure by taking advantage of the difference in evaporation speed of water and acetone during drying, and the pore size is 50.48±0.88 μm.

[0092] Further, after adding ethylene glycol to the system, the interaction between ethylene glycol and deionized water can effectively increase the pore size and thus increase the thickness of the composite film. In the composite film M3, the pore size reaches 77.46±1.36 μm, and ethylene glycol also makes the porous structure more uniform, thereby effectively improving the radiation cooling performance and ultraviolet blocking ability of the composite film.

[0093] Still further, in the composite film M4, a certain amount of polyhexamethylene guanidine hydrochloride is also added. As shown in Figure 3 and Figure 4 , the addition of polyhexamethylene guanidine hydrochloride does not affect the porous structure of the composite film, and the pore size of the composite film M4 is 72.58±1.30 μm. In other words, the porous structure of the composite film is not determined by polyhexamethylene guanidine hydrochloride, and after adding polyhexamethylene guanidine hydrochloride, the composite film has excellent antibacterial performance and antioxidant ability.

[0094]

Example 16

[0095] In this embodiment, the passive cooling ability of the composite films M1-M4 for radiation cooling was tested.

[0096] Specifically, the composite films M1-M4 were cut into circular pieces of the same size, placed in a foam box wrapped in tin foil paper, and then irradiated under sunlight for 5 minutes. Pictures were taken by a near-infrared imager and the temperature of the composite film was recorded.

[0097] The test results are shown in Figure 5 . Due to the lack of a porous structure, the temperature of the composite film M1 is significantly higher. After having a uniform porous structure, the temperature of the composite film M2 is greatly reduced, and after adding ethylene glycol, the radiation cooling ability of the composite film is further improved. In addition, as shown in the figure, after adding polyhexamethylene guanidine hydrochloride, the radiation cooling effect of the composite film M4 is not affected.

[0098]

Example 17

[0099] In this embodiment, the mechanical properties of the composite films were tested.

[0100] Specifically, each composite membrane was cut into dumbbell shape and then stretched using a texture analyzer at a speed of 10 mm / min to obtain the elongation at break of each composite membrane.

[0101] The test results are as follows Figure 6 As shown, after using a mixed solvent, the elongation at break of the composite membrane with a porous structure increased significantly. The composite membrane M4, which has a ternary system composed of ethylene glycol, cellulose acetate, and polyhexamethylene guanidine hydrochloride, had the highest elongation at break, indicating that the composite membrane M4 had the highest toughness.

[0102] Furthermore, after replacing ethylene glycol with glycerin or polyethylene glycol, such as Figure 7 As shown, the tensile strength of composite membranes M7 and M8 is significantly lower than that of composite membrane M4, indicating that the hydrogen bonding interaction between ethylene glycol and cellulose acetate can effectively improve the toughness and mechanical properties of the composite membrane.

[0103]

Example 18

[0104] In this embodiment, the ultraviolet blocking capabilities of composite films M1 to M4 were tested.

[0105] The testing method is as follows: First, each composite film is cut into a circle with a diameter of 10 mm, placed on a UV color-changing plate, and then irradiated under UV light at a wavelength of 365 nm for one minute. After that, the composite film is removed, and the difference in color change between the area covered by the composite film and the surrounding area is observed and photographed.

[0106] The test results are as follows Figure 8 As shown, after ultraviolet irradiation, composite membrane M1 turns a deep purple. The purple color of the area covered by composite membrane M2, which has a porous structure, becomes very light. After adding ethylene glycol, the purple color of M3 and M4 becomes even lighter, indicating that the addition of ethylene glycol results in a composite membrane M4 with a larger pore size, more uniform porous structure, and greater thickness, exhibiting superior UV blocking ability.

[0107]

Example 19

[0108] In this embodiment, the antibacterial properties of composite membranes M1 to M4 against Escherichia coli were tested.

[0109] Specifically, the original E. coli bacterial culture was added to a centrifuge tube containing 30 mL of broth medium and incubated for 24 hours in a shaker at 37 °C and 100 rpm. After assay with a microplate reader, the bacterial culture was diluted to 10⁻⁶. 6 CFU / mL. Then, take 100 μL of culture medium onto an agar plate, attach a circular composite film to the surface, and observe the size of the inhibition zone after 24 hours of incubation.

[0110] The test results are as follows Figure 9As shown, although M2 and M3 achieve good radiation cooling effect by using porous structure, both of them do not have antibacterial ability. After introducing polyhexamethylene guanidine hydrochloride, the composite film M4 produces very obvious bacterial inhibition zone, indicating that the composite film M4 can play an effective sterilization effect when used as packaging.

[0111] Further, the composite films M9 and M10 adjust the amount of polyhexamethylene guanidine hydrochloride on the basis of the composite film M4, wherein the amount of polyhexamethylene guanidine hydrochloride of M9 is halved, and the amount of polyhexamethylene guanidine hydrochloride of M10 is doubled. The test results are as follows Figure 10 As shown, the composite film M9 also has antibacterial property, but does not form a complete bacterial inhibition zone, and the antibacterial ability is weaker than that of the composite films M4 and M10. The bacterial inhibition zones of the composite films M4 and M10 are very complete, indicating that both of them have excellent antibacterial ability. In order to reduce the biological safety problem caused by high concentration, in the most preferred embodiment, the amount of polyhexamethylene guanidine hydrochloride in the composite film M4 is used.

[0112] Figure 11 The figure shows the bacterial growth of chicken wrapped with the composite film M4 and the commercially available preservative film D1 for fresh food for 7 days. As shown, the preservative film D1 has no inhibitory effect on bacteria, and the number of bacteria on the wrapped chicken is large. While the number of bacteria on the chicken wrapped with the composite film M4 is very small, indicating that the composite film M4 can significantly inhibit the growth of bacteria. By calculating the number of surface bacteria, it can be concluded that the bacterial inhibition rate of the composite film M4 on the surface of the chicken can reach almost 100%, and the inhibitory effect is very excellent.

[0113] It is worth noting that the hydroxyl group in ethylene glycol can form hydrogen bonds with the amino group of polyhexamethylene guanidine hydrochloride, and ethylene glycol can also form hydrogen bonds with water molecules in the film. The interaction between hydrogen bonds can effectively slow down the release of polyhexamethylene guanidine hydrochloride, not only can avoid the toxicity caused by burst release of polyhexamethylene guanidine hydrochloride, but also Figure 11 As shown, during the 7-day wrapping process, the composite film M4 achieves long-acting antibacterial ability, which can be better applied to long-distance transportation, long-time storage and other scenarios, and has wide application value.

[0114]

Example 20

[0115] In this embodiment, the free radical scavenging ability of the composite films M1-M4 is tested.

[0116] Specifically, the radical scavenging capacity of the composite film was determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical color solution. DPPH is purple in the original state, and the color changes after reaction. The lighter the purple color, the more DPPH is removed, indicating that the radical scavenging capacity is stronger. The concentration of DPPH solution is 0.1 mM, and the film is 1 wt%. Then the composite film solution is uniformly mixed with DPPH solution with a volume ratio of 2:1, and reacted in the dark for 1 hour.

[0117] The test results are shown in Table 1. Figure 12 As shown in Table 1, the solution color of the composite film M4 is the lightest, indicating that polyhexamethylene guanidine hydrochloride not only provides excellent antibacterial capacity for the composite film, but also removes free radicals to achieve excellent antioxidant capacity.

[0118] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a radiation-cooled antibacterial composite membrane, characterized in that, Includes the following steps: Mix deionized water and acetone to obtain a mixed solvent; A mixture is obtained by stirring cellulose acetate, ethylene glycol, polyhexamethylene guanidine hydrochloride, and the mixed solvent until homogeneous. The mixture is dried to obtain a radiation-cooled antibacterial composite membrane.

2. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 1, characterized in that, Includes the following steps: Mix deionized water and acetone to obtain a mixed solvent; Cellulose acetate is dissolved in the mixed solvent to obtain a first mixture; Ethylene glycol is added to the first solvent to obtain a second mixture; Polyhexamethylene guanidine hydrochloride was added to the second mixture to obtain a third mixture; The third mixture is dried to obtain the radiation-cooled antibacterial composite membrane.

3. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 2, characterized in that, The mass ratio of cellulose acetate to ethylene glycol is 1:1 to 3:

1.

4. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 2, characterized in that, The mass ratio of polyhexamethylene guanidine hydrochloride to ethylene glycol is 1:100 to 1:

400.

5. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 2, characterized in that, The mass ratio of ethylene glycol to deionized water is 1:5 to 1:

10.

6. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 2, characterized in that, The volume ratio of deionized water to acetone is 1:5 to 1:

15.

7. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 2, characterized in that, The liquid level of the third mixture is 1-2 mm.

8. The method for preparing a radiation-cooled antibacterial composite membrane according to claim 2, characterized in that, The drying temperature of the third mixture is 35~55 °C.

9. A radiation-cooled antibacterial composite membrane, characterized in that, The antibacterial composite membrane with radiation cooling is prepared by any one of claims 1 to 8.

10. The radiation-cooled antibacterial composite membrane according to claim 9, characterized in that, The thickness of the radiation-cooled antibacterial composite membrane is greater than 50 micrometers.

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