Antibacterial degradable packaging film and preparation method thereof

Abstract

The invention discloses an antibacterial degradable packaging film and a preparation method thereof, and relates to the technical field of packaging films, the antibacterial degradable packaging film is prepared from the following components by weight: 10-25 parts of PLA, 40-70 parts of PBAT, 10-20 parts of modified calcium carbonate, 0.4-1 part of a chain extender, 0.4-1.6 parts of a plasticizer, 0.8-1.4 parts of a lubricant, and 0.5-2 parts of an antioxidant; the modified calcium carbonate is obtained by sequentially modifying nano calcium carbonate with poly (3-hydroxybutyric acid) and (3-chloropropyl)-trimethyl ammonium chloride; the antibacterial degradable packaging film integrates excellent mechanical property, safe and long-acting antibacterial property and complete biodegradability, overcomes the defects that an existing biodegradable material is crisp in texture and single in function, and meanwhile solves the potential safety hazard of migration and seepage of a traditional antibacterial agent.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging films, and in particular to an antibacterial and degradable packaging film and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) are the two most widely used and promising fully biodegradable polyester materials in commercial applications. They can eventually be decomposed into carbon dioxide and water by microorganisms under composting conditions and are harmless to the environment.

[0003] However, single biodegradable polyester materials often have inherent performance flaws, making it difficult to meet the application requirements of high-performance packaging films. For example, although polylactic acid (PLA) has high strength and modulus, its texture is hard and brittle, its flexibility is poor, and its elongation at break is low, limiting its direct application in thin films requiring good toughness. In contrast, PBAT is known for its excellent flexibility and high elongation at break, but its strength and rigidity are insufficient, and it is easily deformed by stretching after film formation. Therefore, the existing technology often adopts the method of melt blending PLA and PBAT in order to achieve complementary performance. However, due to the large difference in the solubility parameters of PLA and PBAT, the compatibility between the two is poor, resulting in weak interfacial bonding of the blended material, and the mechanical properties often fail to meet the ideal expectations. At the same time, the use of biodegradable resins alone also faces the problem of high cost.

[0004] At the same time, in the food packaging sector, especially for fresh fruits, vegetables, and meat, simply making the material biodegradable is far from enough. During storage and transportation, microorganisms easily grow on food surfaces, leading to spoilage, causing significant economic losses and harming consumer health. Therefore, imparting excellent antimicrobial properties to packaging films to inhibit microbial growth and reproduction, thereby extending the shelf life of food, is a critical technological need in the packaging materials industry.

[0005] At present, in order to realize the antibacterial function of materials, conventional technical means in this field mainly include adding inorganic antibacterial agents (such as nanosilver, nanozinc oxide, etc.) or organic small molecule antibacterial agents.

[0006] CN115710409A discloses a bio-based antibacterial packaging film and a preparation method thereof. The constituent materials of the bio-based antibacterial packaging film include PLA, PBAT and an antibacterial agent, and the antibacterial agent includes at least one of chitosan, nano-silver and nano-zinc oxide.

[0007] However, the application of these traditional antimicrobial agents has significant defects: on the one hand, the small molecule antimicrobial agents (whether organic or inorganic ions) and the polymer matrix are mostly simple physical blends with poor compatibility, and are easy to migrate and seep from the surface of the material. This migration will not only contaminate the packaged food, posing a potential food safety risk, but will also cause the antimicrobial effect of the packaging film to gradually decay over time, making it impossible to achieve long-term antibacterial effect. On the other hand, the directly added inorganic antimicrobial filler has extremely poor interfacial compatibility with organic polyester matrices such as PLA / PBAT, and is very likely to agglomerate during the melt processing process, which not only greatly weakens the mechanical properties of the material, causing it to become brittle, but also the agglomerated particles reduce its specific surface area, greatly reducing its antibacterial efficiency. Therefore, the development of a functional filler that can not only ensure the mechanical properties of the material, but also provide safe and long-lasting antimicrobial functions and good compatibility with the biodegradable matrix has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0008] In order to address the deficiencies of the prior art, the present invention aims to provide an antibacterial and degradable packaging film and a method for preparing the same. The antibacterial and degradable packaging film of the present invention combines excellent mechanical properties, safe and long-lasting antibacterial properties, and complete biodegradability, overcoming the defects of existing biodegradable materials such as brittleness and single function, while also solving the potential safety hazards of migration and seepage of traditional antibacterial agents.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] An antibacterial and degradable packaging film is prepared from the following components, measured by weight: 10-25 parts of PLA, 40-70 parts of PBAT, 10-20 parts of modified calcium carbonate, 0.4-1 part of a chain extender, 0.4-1.6 parts of a plasticizer, 0.8-1.4 parts of a lubricant, and 0.5-2 parts of an antioxidant.

[0011] Preferably, the modified calcium carbonate is prepared by the following method steps:

[0012] (1) Calcium chloride and sodium carbonate are respectively prepared into solutions with deionized water, and the sodium carbonate solution is dropped into the heated calcium chloride solution under vigorous stirring. After the dropwise addition is completed, the mixture is stirred and aged, and the product is filtered, washed, and dried to obtain nano calcium carbonate;

[0013] Formation of nano calcium carbonate: Calcium chloride and sodium carbonate dissociate into calcium ions (Ca2 +) and carbonate ions (CO32-). When the two solutions are mixed, the two ions rapidly combine to form calcium carbonate (CaCO3), which has extremely low solubility in water and precipitates as a solid. By controlling conditions such as temperature, addition rate, and aging time, the nucleation and growth of calcium carbonate crystals can be effectively controlled, resulting in nanometer-scale particle sizes.

[0014] Preferably, in step (1), the usage ratio of calcium chloride and sodium carbonate is 11.1 g:10.6-11.7 g; the concentrations of the calcium chloride solution and the sodium carbonate solution are 0.1-1 mmol / L; the calcium chloride solution is heated to 30-60° C. and stirred and aged at the same temperature for 1-4 hours.

[0015] (2) dispersing nano-calcium carbonate in chloroform, ultrasonically treating, adding poly (3-hydroxybutyric acid) to the calcium carbonate suspension, sealing the reaction, centrifuging, washing, and drying the product to obtain an intermediate calcium carbonate;

[0016] Preferably, in step (2), the usage ratio of nano-calcium carbonate, chloroform and poly (3-hydroxybutyric acid) is 10 g: 100-150 mL: 0.5-3.5 g.

[0017] Preferably, in step (2), the ultrasonic treatment time is 10 to 30 minutes, and the reaction conditions are stirring at 30 to 60° C. for 12 to 24 hours.

[0018] Anchoring of poly (3-hydroxybutyric acid): One end of the poly (3-hydroxybutyric acid) (PHB) molecular chain contains an acidic carboxyl group (-COOH). As an alkaline salt, nano calcium carbonate has a rich surface area of ​​calcium ions (Ca2 + ) site. When the two are mixed and reacted in chloroform, the carboxyl group of PHB reacts with the surface of calcium carbonate to form a structure similar to calcium carboxylate, and the PHB molecular chain is "anchored" on the surface of calcium carbonate through ionic bonds.

[0019] (3) The intermediate calcium carbonate is dispersed in DMF, and then (3-chloropropyl)-trimethylammonium chloride and triethylamine are added, and the reaction is stirred under a nitrogen atmosphere. The product is cooled, centrifuged, washed, and dried to obtain modified calcium carbonate.

[0020] Introduction of quaternary ammonium salt groups: The PHB molecular chain bonded to the surface of calcium carbonate has an alcoholic hydroxyl group (-OH) at its other end. Under the action of triethylamine, an organic base, the hydroxyl group loses its proton and transforms into an alcohol anion with stronger nucleophilicity. This attacks the carbon atom connected to the chlorine in the (3-chloropropyl)-trimethylammonium chloride molecule and replaces the chloride ion, thus forming a stable ether bond and successfully grafting the positively charged quaternary ammonium salt group to the end of the PHB chain.

[0021] Preferably, in step (3), the usage ratio of the intermediate calcium carbonate, DMF, (3-chloropropyl)-trimethylammonium chloride, and triethylamine is 10 g: 100-150 mL: 0.5-2 g: 0.06-0.12 g.

[0022] Preferably, in step (3), the stirring reaction conditions are stirring and reflux reaction at 60-90° C. for 12-24 hours.

[0023] Preferably, the chain extender is chain extender KL-E; the plasticizer is tributyl citrate; the lubricant is one or more of stearic acid, paraffin, and polyethylene wax; and the antioxidant is antioxidant 1010 and / or antioxidant 168.

[0024] The present invention also claims protection for a method for preparing the antibacterial and degradable packaging film, comprising the following steps: drying the components and fully mixing them, plasticizing and melt-casting them, and cooling and shaping them to obtain the antibacterial and degradable packaging film.

[0025] Preferably, the drying temperature is 40-50° C., the melt extrusion process temperature is 170-190° C., the shaping roller temperature during cooling and shaping is 25-35° C., and the rubber roller pressure is 5-10 MPa.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The antibacterial and degradable packaging film prepared by the present invention is a composite of two biodegradable polyester materials, polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT), which ensures the environmentally friendly and degradable properties of the final product. PBAT, as the main material, provides the film with excellent flexibility and elongation at break, making up for the brittle defect of pure PLA; and the addition of PLA improves the overall rigidity and biodegradation rate of the film. Modified calcium carbonate, as the core functional filler, not only reduces costs, but more importantly, gives the packaging film long-lasting and efficient antibacterial ability and excellent mechanical properties. In addition, the chain extender can effectively improve the melt strength of the blending system and the mechanical properties of the final product; the plasticizer and lubricant significantly improve the processing fluidity of the material; and the antioxidant protects the polymer matrix from oxidative degradation during processing and use, ensuring the performance stability and service life of the packaging film.

[0028] 2. The present invention provides a method for preparing modified calcium carbonate. The first step is to chemically bond the carboxyl group at the end of the poly (3-hydroxybutyric acid) (PHB) chain to the calcium ion on the surface of nano-calcium carbonate, so that a flexible molecular chain is grafted onto the inorganic filler as the center. The PHB chain not only acts as an interfacial compatibilizer, greatly improving the compatibility of the inorganic filler with the organic polyester matrix (PLA / PBAT), but also its own steric hindrance effect is conducive to preventing the agglomeration of nano-calcium carbonate particles, so that it can be more evenly dispersed in the matrix. Furthermore, these evenly dispersed modified particles constitute a molecular chain network with calcium carbonate as the chemical cross-linking core in the matrix. This network structure can effectively disperse and transfer external stress, thereby significantly enhancing the toughness and tear resistance of the packaging film and avoiding stress cracking in actual use. In the second step, a positively charged quaternary ammonium salt functional group was introduced at the end of the PHB chain. As the core of broad-spectrum antibacterial properties, it gives the material a strong contact bactericidal ability by physically destroying the bacterial cell wall. Moreover, since it is permanently fixed by covalent bonds, it has excellent safety and long-term effectiveness. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0030] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0031] Poly (3-hydroxybutyric acid) was purchased from BASF with the brand name 1001MD;

[0032] PBAT was purchased from BASF, brand F Blend C1200;

[0033] PLA was purchased from Nature Works.

[0034] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0035] (1) 11.1 g of calcium chloride and 10.6-11.7 g of sodium carbonate were prepared into 0.1-1 mmol / L solutions respectively with deionized water. The sodium carbonate solution was dropped into a calcium chloride solution heated to 30-60° C. under vigorous stirring. After the dropwise addition was completed, the mixture was stirred and aged at the same temperature for 1-4 hours. The product was filtered, washed, and dried to obtain nano calcium carbonate;

[0036] (2) dispersing 10 g of nano-calcium carbonate into 100-150 mL of chloroform, ultrasonically treating for 10-30 min, adding 0.5-3.5 g of poly(3-hydroxybutyric acid) to the calcium carbonate suspension, sealing and stirring at 30-60° C. for 12-24 h, centrifuging, washing, and drying the product to obtain an intermediate calcium carbonate;

[0037] (3) Dispersing 10 g of the intermediate calcium carbonate into 100-150 mL of DMF, then adding 0.5-2 g of (3-chloropropyl)-trimethylammonium chloride and 0.06-0.12 g of triethylamine, stirring and reflux reaction at 60-90° C. under nitrogen atmosphere for 12-24 h, cooling, centrifuging, washing, and drying the product to obtain modified calcium carbonate;

[0038] (4) 10-25 parts of PLA, 40-70 parts of PBAT, 10-20 parts of modified calcium carbonate, 0.4-1 part of chain extender KL-E, 0.4-1.6 parts of plasticizer tributyl citrate, 0.8-1.4 parts of lubricant (one or more of stearic acid, paraffin wax, polyethylene wax), and 0.5-2 parts of antioxidant (antioxidant 1010 and / or antioxidant 168) are dried at 40-50°C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 170-190°C, cooled and shaped, with a shaping roller temperature of 25-35°C and a rubber roller pressure of 5-10 MPa to obtain the antibacterial and degradable packaging film.

[0039] The present invention will be further described below with reference to specific examples.

[0040] Example 1

[0041] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0042] (1) 11.1 g of calcium chloride and 11.7 g of sodium carbonate were prepared into 0.5 mmol / L solutions with deionized water, and the sodium carbonate solution was added dropwise to a calcium chloride solution heated to 60° C. under vigorous stirring. After the addition was complete, the mixture was stirred and aged at the same temperature for 1 h. The product was filtered, washed, and dried to obtain nano calcium carbonate;

[0043] (2) 10 g of nano-calcium carbonate was dispersed in 130 mL of chloroform and ultrasonicated for 20 min. 3.5 g of poly(3-hydroxybutyric acid) was added to the calcium carbonate suspension, and the mixture was sealed and stirred at 60° C. for 12 h. The product was centrifuged, washed, and dried to obtain the intermediate calcium carbonate.

[0044] (3) 10 g of the intermediate calcium carbonate was dispersed in 130 mL of DMF, and then 2 g of (3-chloropropyl)-trimethylammonium chloride and 0.12 g of triethylamine were added. The mixture was stirred and refluxed at 90° C. under a nitrogen atmosphere for 12 h. The product was cooled, centrifuged, washed, and dried to obtain modified calcium carbonate.

[0045] (4) PLA 2500 g, PBAT 7000 g, modified calcium carbonate 2000 g, chain extender KL-E 100 g, plasticizer tributyl citrate 160 g, lubricant stearic acid 140 g, and antioxidant 1010 200 g were dried at 45 ° C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 180 ° C. The mixture was cooled and shaped at a shaping roller temperature of 30 ° C and a rubber roller pressure of 8 MPa to obtain the antibacterial and degradable packaging film.

[0046] Example 2

[0047] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0048] (1) 11.1 g of calcium chloride and 11.4 g of sodium carbonate were prepared into 0.5 mmol / L solutions with deionized water, and the sodium carbonate solution was added dropwise to a calcium chloride solution heated to 50° C. under vigorous stirring. After the addition was complete, the mixture was stirred and aged at the same temperature for 2 h. The product was filtered, washed, and dried to obtain nano-calcium carbonate;

[0049] (2) 10 g of nano-calcium carbonate was dispersed in 130 mL of chloroform and ultrasonicated for 20 min. 2.5 g of poly(3-hydroxybutyric acid) was added to the calcium carbonate suspension, and the mixture was sealed and stirred at 50° C. for 16 h. The product was centrifuged, washed, and dried to obtain the intermediate calcium carbonate.

[0050] (3) 10 g of the intermediate calcium carbonate was dispersed in 130 mL of DMF, and then 1.5 g of (3-chloropropyl)-trimethylammonium chloride and 0.1 g of triethylamine were added. The mixture was stirred and refluxed at 80° C. under a nitrogen atmosphere for 16 h. The product was cooled, centrifuged, washed, and dried to obtain modified calcium carbonate.

[0051] (4) PLA 2000 g, PBAT 6000 g, modified calcium carbonate 1800 g, chain extender KL-E 80 g, plasticizer tributyl citrate 120 g, lubricant stearic acid 120 g, and antioxidant 1010 150 g were dried at 45 ° C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 180 ° C. The mixture was cooled and shaped at a shaping roller temperature of 30 ° C and a rubber roller pressure of 8 MPa to obtain the antibacterial and degradable packaging film.

[0052] Example 3

[0053] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0054] (1) 11.1 g of calcium chloride and 11 g of sodium carbonate were prepared into 0.5 mmol / L solutions with deionized water, and the sodium carbonate solution was added dropwise to a calcium chloride solution heated to 40° C. under vigorous stirring. After the addition was complete, the mixture was stirred and aged at the same temperature for 3 h. The product was filtered, washed, and dried to obtain nano-calcium carbonate;

[0055] (2) 10 g of nano-calcium carbonate was dispersed in 130 mL of chloroform and ultrasonicated for 20 min. 1.5 g of poly(3-hydroxybutyric acid) was added to the calcium carbonate suspension, and the mixture was sealed and stirred at 40° C. for 20 h. The product was centrifuged, washed, and dried to obtain the intermediate calcium carbonate.

[0056] (3) 10 g of the intermediate calcium carbonate was dispersed in 130 mL of DMF, and then 1 g of (3-chloropropyl)-trimethylammonium chloride and 0.08 g of triethylamine were added. The mixture was stirred and refluxed at 70°C under a nitrogen atmosphere for 20 h. The product was cooled, centrifuged, washed, and dried to obtain modified calcium carbonate.

[0057] (4) PLA 1500 g, PBAT 5000 g, modified calcium carbonate 1400 g, chain extender KL-E 60 g, plasticizer tributyl citrate 80 g, lubricant stearic acid 100 g, and antioxidant 1010 100 g were dried at 45 ° C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 180 ° C. The mixture was cooled and shaped at a shaping roller temperature of 30 ° C and a rubber roller pressure of 8 MPa to obtain the antibacterial and degradable packaging film.

[0058] Example 4

[0059] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0060] (1) 11.1 g of calcium chloride and 10.6 g of sodium carbonate were prepared into 0.5 mmol / L solutions with deionized water, and the sodium carbonate solution was added dropwise to a calcium chloride solution heated to 30° C. under vigorous stirring. After the addition was complete, the mixture was stirred and aged at the same temperature for 4 h. The product was filtered, washed, and dried to obtain nano-calcium carbonate;

[0061] (2) 10 g of nano-calcium carbonate was dispersed in 130 mL of chloroform and ultrasonicated for 20 min. 0.5 g of poly(3-hydroxybutyric acid) was added to the calcium carbonate suspension, and the mixture was sealed and stirred at 30° C. for 24 h. The product was centrifuged, washed, and dried to obtain the intermediate calcium carbonate.

[0062] (3) 10 g of the intermediate calcium carbonate was dispersed in 130 mL of DMF, and then 0.5 g of (3-chloropropyl)-trimethylammonium chloride and 0.06 g of triethylamine were added. The mixture was stirred and refluxed at 60° C. under a nitrogen atmosphere for 24 h. The product was cooled, centrifuged, washed, and dried to obtain modified calcium carbonate.

[0063] (4) PLA 1000 g, PBAT 4000 g, modified calcium carbonate 1000 g, chain extender KL-E 40 g, plasticizer tributyl citrate 40 g, lubricant stearic acid 80 g, and antioxidant 101050 g were dried at 45 ° C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 180 ° C. The mixture was cooled and shaped at a shaping roller temperature of 30 ° C and a rubber roller pressure of 8 MPa to obtain the antibacterial and degradable packaging film.

[0064] Comparative Example 1

[0065] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0066] (1) 11.1 g of calcium chloride and 11.7 g of sodium carbonate were prepared into 0.5 mmol / L solutions with deionized water, and the sodium carbonate solution was added dropwise to a calcium chloride solution heated to 60° C. under vigorous stirring. After the addition was complete, the mixture was stirred and aged at the same temperature for 1 h. The product was filtered, washed, and dried to obtain nano calcium carbonate;

[0067] (2) 10 g of nano-calcium carbonate was dispersed in 130 mL of chloroform and ultrasonicated for 20 min. 3.5 g of poly(3-hydroxybutyric acid) was added to the calcium carbonate suspension, and the mixture was sealed and stirred at 60° C. for 12 h. The product was centrifuged, washed, and dried to obtain the intermediate calcium carbonate.

[0068] (3) PLA 2500 g, PBAT 7000 g, intermediate calcium carbonate 1666 g, (3-chloropropyl)-trimethylammonium chloride 334 g, chain extender KL-E 100 g, plasticizer tributyl citrate 160 g, lubricant stearic acid 140 g, antioxidant 1010 200 g were dried at 45 ° C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 180 ° C. The mixture was cooled and shaped, the shaping roller temperature was 30 ° C, and the rubber roller pressure was 8 MPa to obtain the antibacterial and degradable packaging film.

[0069] Comparative Example 2

[0070] A method for preparing an antibacterial and degradable packaging film comprises the following steps:

[0071] (1) 11.1 g of calcium chloride and 11.7 g of sodium carbonate were prepared into 0.5 mmol / L solutions with deionized water, and the sodium carbonate solution was added dropwise to a calcium chloride solution heated to 60° C. under vigorous stirring. After the addition was complete, the mixture was stirred and aged at the same temperature for 1 h. The product was filtered, washed, and dried to obtain nano calcium carbonate;

[0072] (2) PLA 2500 g, PBAT 7000 g, nano-calcium carbonate 1481 g, poly (3-hydroxybutyric acid) 519 g, chain extender KL-E 100 g, plasticizer tributyl citrate 160 g, lubricant stearic acid 140 g, and antioxidant 1010 200 g were dried at 45 ° C and fully mixed, and then plasticized and melt-cast extruded at a melt extrusion process temperature of 180 ° C. The film was cooled and shaped, the shaping roller temperature was 30 ° C, and the rubber roller pressure was 8 MPa to obtain the antibacterial and degradable packaging film.

[0073] The packaging films prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to performance tests. The thickness of the packaging film was tested with reference to GB / T 6672-2001 “Plastic film and sheeting - Mechanical measurement of thickness”; the tensile strength and elongation at break were tested with reference to GB / T 1040.3-2006 “Plastics - Determination of tensile properties - Part 3: Test conditions for film and sheeting”; the oxygen permeability was tested with reference to GB / T 1038.1-2022 “Plastic products - Film and sheeting - Test method for gas permeability - Part 1: Differential pressure method”; and the degradation performance was tested with reference to GB / T 20197-2006 “Definition, classification, marking and degradation performance requirements of degradable plastics”.

[0074] The membrane was cut into circular specimens with a diameter of 10 mm, washed and dried, and allowed to stand at room temperature for 15 days before being placed at the bottom of a 24-well plate. Subsequently, 100 μL of diluted E. coli suspension (approximately 10 5 CFU / mL) and evenly dispersed on the surface of the membrane. The 24-well plate was then placed in a bacterial incubator and cultured at 37°C for 6 hours. Each sample was then taken out and immersed in a test tube containing 10 mL of PBS solution, and all test tubes were subsequently placed in a water bath constant temperature oscillator (150 rpm) and shaken for 10 minutes. Subsequently, 60 μL of the diluted bacterial suspension was spread on a nutrient agar plate, cultured at 37°C for 24 hours, and the number of viable colonies was counted. The experiment was repeated three times, and the average value was taken to test the antibacterial rate of the membrane.

[0075] See Table 1 for specific data.

[0076] Table 1 Packaging film performance test results

[0077]

[0078] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An antibacterial and degradable packaging film, characterized in that: The invention is prepared from the following components in parts by weight: 10-25 parts of PLA, 40-70 parts of PBAT, 10-20 parts of modified calcium carbonate, 0.4-1 parts of chain extender, 0.4-1.6 parts of plasticizer, 0.8-1.4 parts of lubricant, and 0.5-2 parts of antioxidant.

2. The antibacterial and degradable packaging film according to claim 1, characterized in that: The modified calcium carbonate is prepared by the following steps: (1) Calcium chloride and sodium carbonate are prepared into solutions with deionized water respectively, and the sodium carbonate solution is dropped into the heated calcium chloride solution under vigorous stirring. After the dropwise addition is completed, the mixture is stirred and aged, and the product is filtered, washed, and dried to obtain nano calcium carbonate; (2) dispersing nano-calcium carbonate in chloroform, ultrasonically treating, adding poly (3-hydroxybutyric acid) to the calcium carbonate suspension, sealing the reaction, centrifuging, washing, and drying the product to obtain the intermediate calcium carbonate; (3) The intermediate calcium carbonate is dispersed in DMF, and then (3-chloropropyl)-trimethylammonium chloride and triethylamine are added. The reaction is stirred under a nitrogen atmosphere. The product is cooled, centrifuged, washed, and dried to obtain modified calcium carbonate.

3. The antibacterial and degradable packaging film according to claim 2, characterized in that: In step (1), the usage ratio of calcium chloride and sodium carbonate is 11.1 g:10.6-11.7 g; the concentrations of calcium chloride solution and sodium carbonate solution are 0.1-1 mmol / L; the calcium chloride solution is heated to 30-60°C and stirred and aged at the same temperature for 1-4 hours.

4. The antibacterial and degradable packaging film according to claim 2, characterized in that: In step (2), the usage ratio of nano-calcium carbonate, chloroform, and poly (3-hydroxybutyric acid) is 10 g: 100-150 mL: 0.5-3.5 g.

5. The antibacterial and degradable packaging film according to claim 2, characterized in that: In step (2), the ultrasonic treatment time is 10-30 min, and the reaction conditions are stirring at 30-60° C. for 12-24 h.

6. The antibacterial and degradable packaging film according to claim 2, characterized in that: In step (3), the usage ratio of the intermediate calcium carbonate, DMF, (3-chloropropyl)-trimethylammonium chloride, and triethylamine is 10 g: 100-150 mL: 0.5-2 g: 0.06-0.12 g.

7. The antibacterial and degradable packaging film according to claim 2, characterized in that: In step (3), the stirring reaction conditions are stirring and reflux reaction at 60-90°C for 12-24 hours.

8. The antibacterial and degradable packaging film according to claim 1, characterized in that: The chain extender is chain extender KL-E; the plasticizer is tributyl citrate; the lubricant is one or more of stearic acid, paraffin, and polyethylene wax; and the antioxidant is antioxidant 1010 and / or antioxidant 168.

9. A method for preparing the antibacterial and degradable packaging film according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: drying the components and fully mixing them, plasticizing, melting, casting and extruding the components, and cooling and shaping the components to obtain the antibacterial and degradable packaging film.

10. The preparation method according to claim 9, characterized in that The drying temperature is 40~50℃, the melt extrusion process temperature is 170~190℃, the temperature of the shaping roller during cooling and shaping is 25~35℃, and the rubber roller pressure is 5~10MPa.

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