Functional packaging film capable of controllably releasing chlorine dioxide antibacterial agent and production process of functional packaging film

Abstract

The invention discloses a functional packaging film capable of controllably releasing a chlorine dioxide antibacterial agent and a production process thereof.The functional packaging film is composed of an inner-layer film, a middle-layer film and an outer-layer film from inside to outside, and the functional packaging film is obtained through multi-layer co-extrusion compounding; the inner-layer film is composed of an inorganic porous filler and polyolefin with water vapor permeability, and accounts for 20-30% of the mass of the functional packaging film; the middle-layer film is composed of chlorite, organic acid and a hydrophilic polymer and accounts for 20-30% of the mass of the functional packaging film; and the outer layer film is made of polyolefin and accounts for 45-60% of the mass of the functional packaging film. The functional packaging film provided by the invention can realize controllable and long-lasting slow release of chlorine dioxide, the slow release period of the film for chlorine dioxide exceeds 40 days, the functional packaging film is used for packaging food, the shelf life of the food can be prolonged, and the functional packaging film is simple in production process and easy to industrialize.

Description

Technical Field

[0001] The invention relates to the technical field of packaging material preparation, and in particular to a functional packaging film capable of controlling the sustained release of a chlorine dioxide antibacterial agent and a production process thereof. Background Art

[0002] With the increasing awareness of environmental protection and the increasing requirements for hygiene and safety, the development of new food preservation technologies has attracted much attention. Antimicrobial packaging can play a protective role in food preservation and ensure food safety by preventing external contact and microorganisms from entering food, and regulating internal and external gases. Chlorine dioxide is a safe, efficient, and powerful broad-spectrum bactericide. It has the advantages of no three-causing (carcinogenic, teratogenic, and mutagenic) substances appearing during use; at the same time, chlorine dioxide has unique advantages in reducing foodborne diseases, reducing microbial corruption, maintaining food freshness, and maintaining food nutritional quality. Chlorine dioxide is recommended by the World Health Organization as an A1-level product among safe disinfectants and has been widely used in the fields of fruit and vegetable preservation. However, chlorine dioxide is very unstable, especially in liquid form, which makes it difficult to store for a long time. Compared with liquid chlorine dioxide, gaseous chlorine dioxide has stronger permeability and better antibacterial properties. When gaseous chlorine dioxide is exposed to light, it is easy to decompose, which limits its application. Therefore, it is necessary to develop a stable chlorine dioxide preparation that slowly releases chlorine dioxide gas over a certain period of time.

[0003] In order to achieve the above goals, many researchers have conducted research and published many research papers. Li et al. (Langmuir. 2009, 25 (23): 13472-13480.) used polyoxyethylene-polyoxypropylene as shell material and prepared a microcapsule coating film with good antibacterial activity by water-in-oil-in-water (W / O / W) double emulsion for encapsulating stable chlorine dioxide solution. Ray (Journal Food Science. 2013, 78 (2): 276-284.) prepared a slow-release film for chlorine dioxide by incorporating sodium chlorite and citric acid powder into a polylactic acid (PLA) shell by solution casting. However, since sodium chlorite (NaClO2) and acid are directly mixed in the film, this leads to premature release and further leads to a short release cycle. Bai et al. (Journal of Agricultural and Food Chemistry. 2016, 64 (45): 8647-8652.) used an acrylic pressure-sensitive adhesive polymer impregnated with sodium chlorite and an acid-containing polyvinyl alcohol compound to prepare a binary composite film that can be activated by moisture to release chlorine dioxide gas, and then established a slow-release mechanism model. The film loads sodium chlorite and acid on different film materials to prepare two layers of film, which may have the problem of uneven release. Jain et al. (ACS Applied Materials & Interfaces. 2017, 9 (19): 16594-16603.) studied the photochemical activation of a film containing solid sodium chlorite by ultraviolet (UV) irradiation, and studied the generation of gaseous chlorine dioxide when exposed to moisture. The film requires the use of external ultraviolet (UV) light and cannot generate chlorine dioxide gas by itself according to the environment. Although researchers have tried many methods, the preservation and slow release of solid chlorine dioxide products are easily affected by temperature and humidity, resulting in low preservation rate and short release cycle. Huang (Journal of Materials Science. 2018, 53: 12704-12717.) used microcapsule technology to prepare an antibacterial polylactic acid (PLA) film that can release chlorine dioxide continuously. That is, a stable chlorine dioxide solution (with sodium chlorite as the main component) is encapsulated to prepare chlorine dioxide microcapsules. Then the microcapsules and tartaric acid are added to the polylactic acid to prepare an antibacterial film that can continuously release chlorine dioxide gas under water activation. From the published research papers, the sustained-release chlorine dioxide has the problems of short release duration, uncontrollability, and the need for light or water to trigger. In addition, the preparation process of the film or capsule of the sustained-release chlorine dioxide is relatively cumbersome and complicated, and it is not easy to realize industrialization.

[0004] Patent document CN104097849A discloses a fresh-keeping packaging material for slow-release chlorine dioxide disinfectant and its preparation method. The fresh-keeping packaging material described in the patent is a composite film prepared by dry compounding of a highly breathable cast polyethylene outer film and an EVA-modified highly breathable cast polyethylene inner film with an adhesive containing chlorine dioxide releaser powder. Patent document CN106476380A discloses a preparation process for a slow-release chlorine dioxide antibacterial film. It uses polyvinyl alcohol and polylactic acid as the main substrates, and uses wet compounding to compound A film and B film together to prepare a reactive chlorine dioxide antibacterial film; A film uses polyvinyl alcohol as the film-forming substrate, and uses a stable chlorine dioxide aqueous solution to prepare a polyvinyl alcohol gel aqueous solution, and then uses a casting process to dry the film, and adds glycerol and carboxymethyl cellulose to increase the hygroscopicity of the film to promote the release of chlorine dioxide; B film uses polylactic acid as the film-forming substrate, dissolves polylactic acid with dichloromethane, and adds one of the activators citric acid or tartaric acid. After adding plasticizer and antioxidant, the film is cast. The preparation of slow-release chlorine dioxide film disclosed in the above patent technology mainly has the problem of complex preparation process.

[0005] Therefore, it is particularly desirable to propose the present invention. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a functional packaging film with controllable sustained release of chlorine dioxide antibacterial agent and its production process. The obtained functional packaging film can achieve controlled and long-lasting sustained release of chlorine dioxide, has a simple production process, and is easy to industrialize.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a functional packaging film capable of controlled sustained release of chlorine dioxide antibacterial agent, wherein the functional packaging film is composed of an inner layer film, an intermediate layer film and an outer layer film from inside to outside, and the functional packaging film is obtained by multi-layer co-extrusion compounding;

[0009] The inner film is composed of an inorganic porous filler and a polyolefin having water vapor permeability, accounting for 20 to 30% of the mass of the functional packaging film;

[0010] The intermediate film is composed of chlorite, organic acid and hydrophilic polymer, accounting for 20-30% of the weight of the functional packaging film;

[0011] The outer film is composed of polyolefin, accounting for 45-60% of the weight of the functional packaging film.

[0012] The above technical scheme is an innovation of the applicant to improve the structure and process of preparing the slow-release chlorine dioxide film based on the work of predecessors, which realizes the controllable release of chlorine dioxide and the duration can reach more than 40 days. The present invention innovatively applies the multi-layer co-extrusion process to the production of such functional packaging film, and the process is simple and easy. The slow-release chlorine dioxide film prepared by the present invention can be applied to the packaging of fruits and vegetables and other foods to achieve its sterilization and preservation effects, thereby ensuring the quality of food and extending the shelf life of food.

[0013] In the above technical scheme, the functional packaging film adopts a multi-layer co-extrusion blow molding or cast film process, and is composed of three layers of film: an outer layer, an intermediate layer, and an inner layer. The outer layer is composed of polyolefin, which can provide good protection and mechanical properties for the film, and can be printed by corona treatment; the intermediate layer is composed of chlorite, organic acid, and hydrophilic polymer that produce chlorine dioxide. When the intermediate layer absorbs water, the chlorite reacts chemically with the organic acid to generate chlorine dioxide. The chemical reaction formula is: 2NaClO2+C6H8O7→2ClO2↑+NaCl+3CO2↑+4H2O; the inner layer is composed of porous inorganic fillers and polyolefin with good water vapor permeability. On the one hand, the inner layer can ensure compatibility and safety with the packaging contents, and on the other hand, the inner layer can make water vapor and chlorine dioxide gas easily permeable, which is one of the key factors for the controllable slow release of chlorine dioxide in the functional packaging film of the present invention.

[0014] In the above technical solution, the outer layer of the functional packaging film is composed of at least one polyolefin selected from linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA) and polypropylene (PP). The outer film provides the mechanical strength of the packaging film and the barrier property to chlorine dioxide gas, and is printable. The polyolefin used for the outer film can be selected according to the specific requirements of the functional packaging film for the outer film. Generally speaking, the packaging film should have good puncture resistance. LLDPE has good puncture resistance and processing performance, and LDPE has good comprehensive performance. The outer polyolefin is preferably a blend of LLDPE and LDPE. As a preferred embodiment of the technical solution of the present invention, the percentage of LLDPE in the total mass of the outer film is 70-90%, and the percentage of LDPE in the total mass of the outer film is 10-30%. Since LLDPE and LDPE are both non-polar polymer materials, in order to make the printed ink not easy to fall off the film, the outer film can be corona treated online to increase the polarity of the polyolefin, thereby increasing the adhesion of the ink on the outer film.

[0015] In the above technical solution, the middle layer of the functional packaging film is composed of chlorite, organic acid and hydrophilic polymer. The percentage of chlorite in the total mass of the middle layer is 1.5-6%, the percentage of organic acid in the total mass of the middle layer is 3-10%, and the percentage of polymer in the total mass of the middle layer is 80-95%. The middle layer slowly releases chlorine dioxide gas, which is produced by the reaction of chlorite and organic acid. Chlorite includes sodium chlorite, calcium chlorite and barium chlorite, preferably sodium chlorite. Organic acid includes any one of citric acid, tartaric acid, sorbic acid and malic acid. Among these four organic acids, citric acid has the strongest acidity, preferably citric acid. The hydrophilic polymer selects one or two of EVA and PVA. The content of VA in EVA will affect its hydrophilicity. The higher the VA content, the better the hydrophilicity. The molecular weight and alcoholysis degree of PVA will affect its hydrophilicity. Low molecular weight and high alcoholysis degree have better hydrophilicity. In order to make PVA more hydrophilic, PVA does not melt when EVA melts, but is in a solid powder state. Before preparing functional packaging film, chlorite, organic acid and hydrophilic polymer should be fully dried to prevent chlorite and organic acid from reacting prematurely under the induction of water.

[0016] Furthermore, the inner layer of the functional packaging film is composed of a porous inorganic filler and a polyolefin with good water permeability. Chlorite has strong oxidizing properties. If it comes into direct contact with packaged food, on the one hand, chlorite will cause the food to oxidize and deteriorate; on the other hand, the water vapor generated by the respiration of the packaged food and the residual water that may be attached to the food will induce the reaction of chlorite with organic acid, which will cause the reaction to be fast at first and then slow, which is not conducive to the controlled slow release of chlorine dioxide. Since the inner film is composed of a porous inorganic filler and a polyolefin with good water vapor permeability, the water generated by the packaging can pass through the inner film and enter the middle film, but since the pore size of the inner film is small, the speed at which water passes through the inner film is controlled, and there will be no problem of the reaction speed being fast at first and then slow, or slow at first and then fast. The porous filler includes one or two of zeolite, diatomaceous earth, expanded perlite and porous ceramics, preferably zeolite. The mass of the porous filler accounts for 5 to 15% of the total mass of the inner film. The water-permeable polymer of the inner layer includes one or two of LDPE, LLDPE, EVA and PP, and the mass of these polymers accounts for 85-95% of the total mass of the inner layer film.

[0017] Furthermore, the inner layer of the functional packaging film of the present invention has a porous structure, which can absorb part of the ethylene gas released by the packaged food, and chlorine dioxide can oxidize the ethylene gas, so the functional packaging film of the present invention has the effect of preventing the packaged fruits and vegetables from ripening prematurely.

[0018] As a preferred embodiment of the technical solution of the present invention, the organic acid is selected from at least one of citric acid, tartaric acid, sorbic acid and malic acid.

[0019] As a preferred embodiment of the technical solution of the present invention, the hydrophilic polymer is selected from at least one of polyvinyl alcohol and ethylene-vinyl acetate copolymer; wherein the molecular weight of polyvinyl alcohol is 2.5×10 4 ~6.5×10 4 , the alcoholysis degree is less than 85%.

[0020] As a preferred embodiment of the technical solution of the present invention, the polyolefin in the inner film is selected from at least one of low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and polypropylene; wherein the water vapor permeability of low-density polyethylene is 10 to 30 mL / m 2 ·day·atm, the water vapor permeability of linear low-density polyethylene is 5~20mL / m 2 ·day·atm, the water vapor permeability of ethylene-vinyl acetate copolymer is 10~30mL / m 2 ·day·atm, the water vapor permeability of polypropylene is 5~20mL / m 2 ·day·atm.

[0021] As a preferred embodiment of the technical solution of the present invention, the thickness of the functional packaging film is 25 to 35 μm.

[0022] As a preferred embodiment of the technical solution of the present invention, when the concentration of chlorine dioxide is between 2.0 and 5.0 ppm, chlorine dioxide has a good sterilization effect. The functional packaging film of the present invention can slowly release chlorine dioxide at a concentration between 5.0 and 25.0 ppm, and the release period exceeds 40 days.

[0023] In a second aspect, the present invention further provides a method for preparing the functional packaging film, comprising the following steps:

[0024] First, the raw materials of the inner film, the middle film and the outer film are accurately weighed and mixed evenly to obtain respective mixed materials;

[0025] Next, the obtained mixed materials are respectively put into a multi-layer co-extrusion device, and the functional packaging film is obtained by multi-layer co-extrusion blow molding or cast molding. If the requirement for uniformity of film thickness is not very high, the multi-layer co-extrusion blow molding method is preferred.

[0026] As a preferred embodiment of the technical solution of the present invention, the processing temperature of the outer layer is 170-200° C., the processing temperature of the middle layer is 125-145° C., and the processing temperature of the inner layer is 170-200° C. In the middle layer, the decomposition temperature of sodium chlorite is the lowest, which is 175.0° C., and the decomposition of chlorite should be prevented during processing.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The functional packaging film provided by the present invention has good antibacterial properties, can effectively inhibit the growth of microorganisms such as bacteria and molds, and prolong the shelf life of fruits and vegetables in the package. The design of the functional packaging film adopts controlled slow-release technology, so that the chlorine dioxide antibacterial agent can be slowly released, thereby increasing the duration of the antibacterial effect (up to more than 40 days).

[0029] At the same time, the key innovation of the present invention is to use a multi-layer co-extrusion blow molding or cast film process to produce a functional packaging film, which is simple, continuous, and efficient, with tight bonding between the layers, stable performance, and effectively avoiding the problem of interlayer separation. It is easy to achieve industrialization and large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the main structure of functional packaging film.

[0031] Figure 2 Schematic diagram of the working principle of fresh-keeping bags made of functional packaging film. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are described in detail below. It should be emphasized that all the embodiments are intended to explain the present invention and should not be construed as limiting the present invention.

[0033] The test method adopted for the performance of the present invention is as follows:

[0034] Chlorine dioxide concentration (ppm): Detected with a chlorine dioxide detector.

[0035] Example 1

[0036] 85.0 parts of LLDPE (China Petrochemical Corporation Guangzhou Branch, brand DFDA-7042, density 0.918 g / cm 3 , melt index is 2.0g / 10min) and 15.0 parts of LDPE (PetroChina Daqing Petrochemical Company, grade 18D, density is 0.917-0.923g / cm 3 , melt index is 0.2-0.4g / 10min) after mixing evenly, put into the hopper of the multilayer co-extrusion extruder, the temperature of the extruder barrel and the head is 170℃ (zone 1), 175℃ (zone 2), 180℃ (zone 3), 180℃ (zone 4), 185℃ (zone 5) and 200℃ (head); 2.0 parts of sodium chlorite (Yunnan Jinchu Chemical Co., Ltd., solid powder, decomposition temperature 175.0℃), 4.0 parts of citric acid (Jiangsu Raymond Chemical Technology Co., Ltd., solid powder), 80.0 parts of EVA (Formosa Plastics Group, brand 7350M, VA content 18.0%, density 0.929g / cm 3, melt index 2.5g / 10min) and 20.0 parts PVA (Shanxi Sanwei Group Co., Ltd., brand PVA 088-2017-88, density 1.27g / cm 3 ) are mixed evenly, and then put into the hopper of a multi-layer co-extruded extruder, and the temperatures of the extruder barrel and die head are 125°C (zone 1), 130°C (zone 2), 135°C (zone 3), 135°C (zone 4), 135°C (zone 5) and 140°C (die head); 5.0 parts by weight of zeolite (Wuhan Jiyesheng Chemical Co., Ltd., 4A, 200 mesh), 5.0 parts by weight of diatomaceous earth (Lingshou County Yuanda Mica Factory, 300 mesh), 60.0 parts by weight of LDPE and 40 parts by weight of EVA are mixed evenly, and then put into the hopper of a multi-layer co-extruded extruder, and the temperatures of the extruder barrel and die head are 160°C (zone 1), 170°C (zone 2), 175°C (zone 3), 175°C (zone 4), 175°C (zone 5) and 180°C (die head). The functional packaging film is prepared by multi-layer co-extrusion blow molding, and the blow-up ratio is 2.5-3.5. The film produced by co-extrusion can be directly added into packaging bags, such as Figure 1 and Figure 2 The raw material composition of Example 1 is shown in Table 1.

[0037] The film prepared in Example 1 was processed into packaging bags with a size of 100.0 mm × 100.0 mm, and there were 10 bags in a group. Cherries were used as test samples of packaged food, and 100.0 g of cherries were respectively put into 10 packaging bags, which were sealed by heat sealing. Then, the change of chlorine dioxide concentration in the packaging bags over time was detected, as shown in Table 2.

[0038] Example 2

[0039] The composition of Example 2 is shown in Table 1. The preparation steps, process and chlorine dioxide concentration detection of Example 2 are the same as those of Example 1. The prepared film and packaging bag are as follows Figure 1 and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0040] Example 3

[0041] The composition of Example 3 is shown in Table 1. The preparation steps, process and chlorine dioxide concentration detection of Example 3 are the same as those of Example 1. The prepared film and packaging bag are as follows Figure 1 and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0042] Example 4

[0043] The composition of Example 4 is shown in Table 1. The preparation steps, process and chlorine dioxide concentration detection of Example 4 are the same as those of Example 1. The prepared film and packaging bag are as follows Figure 1and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0044] Example 5

[0045] The composition of Example 5 is shown in Table 1. The preparation steps, process and chlorine dioxide concentration detection of Example 5 are the same as those of Example 1. The prepared film and packaging bag are as follows Figure 1 and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0046] Example 6

[0047] The composition of Example 6 is shown in Table 1. The preparation steps, process and chlorine dioxide concentration detection of Example 6 are the same as those of Example 1. The prepared film and packaging bag are as follows Figure 1 and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0048] From Examples 1 to 6, it can be found (as shown in Table 2) that the concentration of chlorine dioxide gradually increases with time, first increasing rapidly and then slowing down. This shows that in addition to a portion of chlorine dioxide consumed for sterilization, the chlorine dioxide generated in the middle layer is continuous, and the amount generated is greater than the amount consumed.

[0049] Specifically, the difference between Example 2 and Example 1 is the amount of sodium chlorite and citric acid in the middle layer composition (as shown in Table 1), and the mass of sodium chlorite and citric acid in Example 2 is twice that of Example 1. As time goes on, Example 2 releases chlorine dioxide faster than Example 1, and thus the concentration is higher, especially in the first 14 days (as shown in Table 2). The difference between Example 3 and Example 1 is the amount of EVA and PVA in the inner layer composition (as shown in Table 1), and the content of PVA in Example 3 is higher. PVA is more hydrophilic than EVA, and the water vapor generated by the respiration of cherries in the packaging bag is more likely to penetrate into the middle layer. The middle layer with a high PVA content will produce chlorine dioxide faster, but as time goes on, the speed at which the middle layer with a high PVA content produces chlorine dioxide slows down (as shown in Table 2). The difference between Example 4 and Example 1 is the amount of EVA and PVA and the amount of sodium chlorite and citric acid in the inner and middle layer compositions (as shown in Table 1), and the content of PVA, sodium chlorite and citric acid in Example 4 is higher. The middle layer with high PVA content will produce chlorine dioxide faster, and high content of sodium chlorite and citric acid will produce more chlorine dioxide (as shown in Table 2). The difference between Example 5 and Example 1 is the content of porous filler in the inner layer composition (as shown in Table 1). The content of porous filler in Example 5 is twice that of Example 1. Since porous filler plays an important role in the penetration of water vapor generated by the respiration of packaged cherries into the middle layer, Example 5 with high porous filler content produces chlorine dioxide faster and at a higher concentration (as shown in Table 2). The difference between Example 6 and Example 1 is the content of PVA and porous filler in the middle layer and inner layer composition (as shown in Table 1). In Example 6, the content of PVA and porous filler is higher, and the water vapor generated by the respiration of packaged cherries is more likely to penetrate into the middle layer, so the speed of chlorine dioxide production is faster and the concentration is higher (as shown in Table 2).

[0050] Comparative Example 1

[0051] The difference between Comparative Example 1 and Example 1 is that the composition of the film middle layer does not contain PVA. The preparation steps, process and chlorine dioxide concentration detection of Comparative Example 1 and Example 1 are the same as those of Example 1. The prepared film and the prepared packaging bag are as follows Figure 1 and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0052] Comparative Example 2

[0053] The difference between Comparative Example 2 and Example 1 is that there is no porous inorganic filler in the composition of the inner layer of the film in Comparative Example 2. The preparation steps, process and chlorine dioxide concentration detection of Comparative Example 2 and Example 1 are the same as those of Example 1. The prepared film and the prepared packaging bag are as follows: Figure 1 and Figure 2 The change of chlorine dioxide concentration over time is shown in Table 2.

[0054] The difference between Comparative Example 1 and Example 1 is that there is no PVA in the middle layer composition (as shown in Table 1). PVA, as a hydrophilic polymer, has a certain speed-increasing effect on the water vapor generated by the respiration of cherries in the package to penetrate into the middle layer. Since there is no PVA in the middle layer of Comparative Example 1, compared with the middle layer of Example 1 with PVA, the speed of chlorine dioxide generated in Comparative Example 1 is slow and the concentration is low, as shown in Table 2. The difference between Comparative Example 2 and Example 1 is that there is no porous filler in the inner layer composition (as shown in Table 1). The porous filler makes it easy for the water vapor generated by the respiration of cherries in the package to penetrate into the middle layer. Since there is no porous filler in the inner layer composition of Comparative Example 2, when the time is not long, the speed of chlorine dioxide generated in Comparative Example 2 is extremely slow and the concentration is very low. However, as time goes on, water vapor may penetrate into the middle layer through the inner layer LDPE / EVA, and the concentration of chlorine dioxide increases. As shown in Table 2.

[0055] Table 1 Examples and Comparative Examples Raw Materials Composition

[0056]

[0057] Table 2 Chlorine dioxide concentration variation results of examples and comparative examples

[0058]

[0059]

[0060] The results of the examples and comparative examples show that the reasonable design of the raw material composition for preparing the functional packaging film can control the rate of slow release of chlorine dioxide, thereby controlling its concentration. Although the present invention uses cherries to verify the application of the slow-release chlorine dioxide functional packaging film, based on the same principle, the functional packaging film of the present invention is also suitable for the preservation of other fruit and vegetable foods.

[0061] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent, characterized in that: The functional packaging film is composed of an inner film, an intermediate film and an outer film from inside to outside, and the functional packaging film is obtained by multi-layer co-extrusion compounding; The inner film is composed of an inorganic porous filler and a polyolefin having water vapor permeability, accounting for 20 to 30% of the mass of the functional packaging film; The intermediate film is composed of chlorite, organic acid and hydrophilic polymer, accounting for 20-30% of the weight of the functional packaging film; The outer film is composed of polyolefin, accounting for 45-60% of the weight of the functional packaging film.

2. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 1, characterized in that: In the inner film, the inorganic filler and the water vapor permeable polyolefin account for 5-15% and 85-95% by mass, respectively; In the middle layer film, the mass proportions of chlorite, organic acid and hydrophilic polymer are 1.5-6%, 3-10% and 80-95% respectively.

3. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 1, characterized in that: The polyolefin in the outer film is selected from at least one of low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and polypropylene.

4. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 1, characterized in that: The organic acid is selected from at least one of citric acid, tartaric acid, sorbic acid and malic acid; the chlorite is selected from at least one of sodium chlorite, calcium chlorite and barium chlorite.

5. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 1, characterized in that: The hydrophilic polymer is selected from at least one of polyvinyl alcohol and ethylene-vinyl acetate copolymer; wherein the molecular weight of the polyvinyl alcohol is 2.5×10 4 ~6.5×10 4 , the alcoholysis degree is less than 85%.

6. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 1, characterized in that: The polyolefin in the inner film is selected from at least one of low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and polypropylene; wherein the water vapor permeability of low-density polyethylene is 10 to 30 mL / m 2 ·day·atm, the water vapor permeability of linear low-density polyethylene is 5~20mL / m 2 ·day·atm, the water vapor permeability of ethylene-vinyl acetate copolymer is 10~30mL / m 2 ·day·atm, the water vapor permeability of polypropylene is 5~20mL / m 2 ·day·atm.

7. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 1, characterized in that: The inorganic porous filler is selected from at least one of zeolite, diatomaceous earth, expanded perlite and porous ceramics.

8. The functional packaging film for controlled sustained release of chlorine dioxide antibacterial agent according to claim 7, characterized in that: The thickness of the functional packaging film is 25-35 μm.

9. A method for preparing the functional packaging film according to any one of claims 1 to 8, characterized in that: The steps include: First, the raw materials of the inner film, the middle film and the outer film are accurately weighed and mixed evenly to obtain respective mixed materials; Next, the obtained mixed materials are respectively put into a multi-layer co-extrusion device, and the multi-layer co-extrusion blow molding or cast molding is adopted to obtain the functional packaging film.

10. The preparation method according to claim 9, characterized in that: The processing temperature of the outer layer is 170-200°C, the processing temperature of the middle layer is 125-145°C, and the processing temperature of the inner layer is 170-200°C.

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