Barrier-antibacterial double-effect synergistic biodegradable fresh-keeping master batch as well as preparation method and application of barrier-antibacterial double-effect synergistic biodegradable fresh-keeping master batch

Abstract

The invention belongs to the technical field of biodegradable high polymer materials, and discloses a barrier-antibacterial double-effect synergistic biodegradable fresh-keeping master batch and a preparation method and application thereof.The barrier-antibacterial double-effect synergistic biodegradable fresh-keeping master batch is prepared from, by weight, 40-60 parts of biodegradable polymer matrix and 20-30 parts of plasticized plant polysaccharide, 15-30 parts of a multifunctional nano-composite blocking agent and 5-10 parts of a compatilizer; wherein lamellar nano clay and hydrophobic nano SiOO loaded with plant essential oil are compounded to form a multifunctional nano composite blocking agent, fine dispersion and interfacial compatibilization of nano filler are realized in a PLA / PBAT matrix through a synergistic effect of a reactive compatilizer and plasticized plant polysaccharide, and through an innovative nano composite material formula and structural design, the nano composite material has excellent mechanical properties and mechanical properties. The barrier property and long-acting antibacterial property on water vapor and oxygen are synchronously realized, and the processability is good.

Description

Technical Field

[0001] This invention relates to the field of biodegradable polymer materials technology, specifically to the field of manufacturing technology for high-end food preservation packaging films and bags, and more specifically to a biodegradable preservation masterbatch with synergistic barrier and antibacterial effects, its preparation method, and its application. Background Technology

[0002] With the deepening of global plastic bans and the awakening of consumers' environmental awareness, fully biodegradable materials, represented by polylactic acid (PLA), polybutylene adipate / terephthalate (PBAT), and their blends, are rapidly becoming ideal alternatives to traditional petroleum-based plastics in the packaging field, especially in food packaging. However, in the process of industrial upgrading from "substitution" to "surpassing," two inherent technical bottlenecks exposed by existing fully biodegradable materials severely restrict their application in high-end food preservation packaging. The main reasons are as follows: (1) The inherent barrier properties of the materials are insufficient. PLA and PBAT generally have poor barrier properties against gases such as water vapor and oxygen. For example, although PLA has better oxygen barrier properties than PBAT, it is still far lower than high-barrier materials such as polyvinylidene chloride (PVDC) or ethylene-vinyl alcohol copolymer (EVOH), and it is also more brittle; while PBAT has good toughness, its barrier properties are even lower than those of polyethylene (PE). This makes food packaged with ordinary biodegradable materials, especially high-value-added foods that are sensitive to oxygen and water (such as nuts, baked goods, frozen ingredients, and fresh fruits and vegetables), prone to oxidation, moisture absorption and clumping, or dehydration during storage and logistics, resulting in a sharp deterioration in quality, a significantly shortened shelf life, and huge economic losses and resource waste. Currently, the industry usually uses blending modification or surface coating technology to improve barrier properties. For example, adding nano-clays (such as montmorillonite) is a common method, but its interfacial compatibility with biodegradable matrices is poor, and it is prone to aggregation, forming stress defects. This not only limits the improvement of barrier efficiency but also often leads to a significant decrease in material toughness, resulting in an awkward situation of "one increase and one decrease." Surface coating with silica films, on the other hand, faces problems such as complex processes, high costs, weak adhesion between the coating and the substrate, easy cracking, and impact on the overall biodegradability of the material.

[0003] (2) Materials generally lack active antibacterial function. Another major cause of food spoilage is the reproduction of microorganisms. Existing biodegradable materials themselves do not have the ability to inhibit the growth of microorganisms. In fact, some hydrophilic bio-based materials (such as starch) may become a breeding ground for microorganisms in a humid environment. In order to endow materials with antibacterial properties, it is common practice to directly add inorganic antibacterial agents (such as nano silver, nano zinc oxide) or organic synthetic antibacterial agents. However, inorganic nanoparticles also have controversies regarding dispersibility and biocompatibility, and are also expensive; while some organic synthetic antibacterial agents may have biotoxicity, which runs counter to the original intention of "environmentally friendly". Plant essential oils have received widespread attention due to their natural, safe and broad-spectrum antibacterial properties, but their high volatility, heat intolerance and strong odor make them difficult to withstand the high-temperature environment of plastic processing (such as melt extrusion and blown film), resulting in a large amount of volatilization and failure during processing, and the residual odor may affect the flavor of food. Although some studies have attempted to encapsulate essential oils using microencapsulation technology, the process is complex and costly, and the capsule wall material may affect the material's processing and degradation properties.

[0004] (3) The improvement of barrier properties and antibacterial properties are often mutually restrictive. Simply physically blending antibacterial agents may destroy the constructed barrier network; while high content of sheet-like barrier fillers may completely encapsulate the antibacterial agent, hindering its migration and release to the surface, resulting in the "failure" of antibacterial function.

[0005] Therefore, developing a comprehensive solution that can cleverly synergize the dual functions of "barrier" and "highly effective antibacterial", while simultaneously satisfying the requirements of being processing-friendly, cost-controllable, and fully biodegradable, has become an urgent technical challenge in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a biodegradable preservation masterbatch with synergistic barrier-antibacterial effect, its preparation method and application. The biodegradable preservation masterbatch with synergistic barrier-antibacterial effect of this invention is a multifunctional integrated masterbatch. Through innovative nanocomposite material formulation and structural design, it simultaneously achieves barrier properties against water vapor and oxygen and long-lasting antibacterial properties, and has good processing performance.

[0007] To achieve the objectives of this invention, the present invention provides a biodegradable preservation masterbatch with synergistic barrier-antibacterial effects, comprising, by weight, 40-60 parts of a biodegradable polymer matrix, 20-30 parts of plasticized plant polysaccharides, 15-30 parts of a multifunctional nanocomposite barrier agent, and 5-10 parts of a compatibilizer; wherein the multifunctional nanocomposite barrier agent is a composite of layered nanoclay and hydrophobic nano-SiO2 loaded with plant essential oils.

[0008] Furthermore, in some embodiments of the present invention, the mass ratio of layered nanoclay to hydrophobic nano-SiO2 loaded with plant essential oil in the multifunctional nanocomposite barrier is 1-2:1.

[0009] Furthermore, in some embodiments of the present invention, the mass ratio of hydrophobic nano-SiO2 to plant essential oil in the hydrophobic nano-SiO2 loaded with plant essential oil is 1:2-4.

[0010] Furthermore, in some embodiments of the present invention, the layered nanoclay is montmorillonite.

[0011] Furthermore, in some embodiments of the present invention, the plant essential oil is at least one of cinnamon essential oil, thyme essential oil, and peppermint essential oil.

[0012] Furthermore, in some embodiments of the present invention, the biodegradable polymer matrix is ​​polylactic acid (PLA), polybutylene adipate / terephthalate (PBAT), or a mixture of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT).

[0013] Preferably, the biodegradable polymer matrix is ​​a mixture of polylactic acid (PLA) and poly(butylene adipate / terephthalate) (PBAT) in a mass ratio of 5-7:3-5.

[0014] Furthermore, in some embodiments of the present invention, the plasticized plant polysaccharide is one or more of glycerol plasticized starch, sodium carboxymethyl cellulose (CMC), and chitosan powder.

[0015] Furthermore, in some embodiments of the present invention, the plasticized plant polysaccharide is a mixture of glycerol plasticized starch and chitosan powder; preferably, the mass ratio of the glycerol plasticized starch to the chitosan powder is 0.9-1.1:0.9-1.1.

[0016] Furthermore, in some embodiments of the present invention, the compatibilizer is a reactive epoxy functional group compatibilizer; preferably, the reactive epoxy functional group compatibilizer is at least one of glycidyl methacrylate (GMA) and ethylene-acrylate-GMA terpolymer.

[0017] On the other hand, the present invention also provides a method for preparing the aforementioned barrier-antibacterial dual-effect synergistic biodegradable preservation masterbatch, the preparation method comprising the following steps: a. Pretreatment of composite antibacterial agent: Hydrophobic nano-SiO2 is mixed with plant essential oil, so that the essential oil is fully adsorbed to obtain powdered essential oil-loaded nano-SiO2; b. Premixing: The biodegradable polymer matrix, plasticized plant polysaccharides, layered nanoclay, essential oil-loaded nano-SiO2 obtained in step a, and compatibilizer are mixed to obtain a premix. c. Melt extrusion granulation: The premixed material is fed into a twin-screw extruder, and after melt mixing, extrusion, cooling, and pelletizing, the biodegradable masterbatch is obtained. In this process, the montmorillonite sheets are peeled off and oriented, synergistically with the uniformly dispersed "oil-loaded nano-SiO2" to construct a "labyrinthine" barrier network in the matrix; at the same time, the compatibilizer ensures that the interfaces of each component are firmly bonded.

[0018] Furthermore, in some embodiments of the present invention, the temperature of the first zone of the twin-screw extruder in step c is controlled at 110-130°C, and the temperature of the subsequent zones and the die head is controlled at 140-170°C.

[0019] In another aspect, the present invention also provides a film prepared from the aforementioned biodegradable preservation masterbatch with synergistic barrier-antibacterial dual effects.

[0020] Furthermore, in some embodiments of the present invention, the oxygen permeability of the film is less than 65 cm³ / m²·day·atm, the antibacterial rate against Escherichia coli and Staphylococcus aureus is greater than 99.5%, and a clearly visible inhibition zone is produced during inhibition zone testing.

[0021] On another aspect, the present invention also provides an application of the aforementioned barrier-antibacterial dual-effect synergistic biodegradable preservation masterbatch or the film prepared therefrom in the preparation of food preservation packaging materials, especially in the fields of fresh fruits and vegetables, high-end cold chain and military food packaging.

[0022] Compared with the prior art, the advantages of the present invention are as follows: (1) Synergistic barrier: The layered nano-clay (montmorillonite) forms a "maze" effect in the matrix, which greatly prolongs the permeation path of gases such as water vapor and oxygen; while nano-SiO2 itself can also fill the free volume, further enhancing the barrier properties. The combination of the two produces a synergistic barrier effect of "1+1>2".

[0023] (2) Long-lasting antibacterial and preservation: The "essential oil-carrying nano-SiO2" not only provides antibacterial function, but its carrier nano-SiO2 itself is also a physical barrier filler. More importantly, the layered structure of montmorillonite can play a certain "shielding" and "slow-release" role for essential oil molecules, and together with nano-SiO2, it regulates the release rate of essential oil, achieves long-lasting antibacterial effect, and effectively removes the ripening gas ethylene.

[0024] (3) Interface optimization and performance balance: Through the combined action of reactive compatibilizer and plasticized plant polysaccharide, the compatibility problem between various polar and non-polar materials (montmorillonite, SiO2, starch, PLA / PBAT) is solved, ensuring the fine dispersion and interface strength of nanofillers, so that the masterbatch can obtain barrier and high antibacterial properties while maintaining good mechanical properties and processability.

[0025] (4) Functional Integration and Industrialization: This invention integrates three major functions—barrier, antibacterial, and degradation—through a one-step melt extrusion process. The process is simple and highly suitable for industrial production. The resulting masterbatch can be directly used for blown film, casting, and other processes to prepare high-end preservation packaging materials, precisely meeting the strategic needs of food logistics for quality preservation and loss reduction. Attached Figure Description

[0026] Figure 1 This is a morphological image of the film prepared from the masterbatch obtained in Example 1 of the present invention after preserving lychees (stored at 4°C for 12 days); Figure 2 This is a morphology image of the film prepared from the masterbatch obtained in Example 2 of the present invention after preserving lychees (stored at 4°C for 12 days); Figure 3 This is a morphology image of the film prepared from the masterbatch obtained in Example 3 of the present invention after preserving lychees (stored at 4°C for 12 days); Figure 4 This is a morphology image of the film prepared from the masterbatch obtained in Example 4 of the present invention after preserving lychees (stored at 4°C for 12 days); Figure 5 The image shows the appearance of lychees after being preserved with commercially available PE plastic wrap (stored at 4°C for 12 days). In the preservation test, the lychees used in each test were fresh lychees randomly selected from the same batch. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and not intended to limit the invention.

[0028] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0029] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0030] The singular form includes the plural objects of discussion unless the context clearly indicates otherwise. "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event occurs and the possibility that the event does not occur.

[0031] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0032] Furthermore, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., described below refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Moreover, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0033] The preparation method of the biodegradable preservation masterbatch with synergistic barrier-antibacterial effect described in this embodiment of the invention includes the following steps: (1) Antibacterial functionalization: Hydrophobic nano-SiO2 and plant essential oil (such as cinnamon essential oil) are mixed at high speed at room temperature to obtain powdered "essential oil-loaded nano-SiO2".

[0034] (2) Premixing: The biodegradable polymer matrix, plasticized plant polysaccharide, montmorillonite, the "oil-loaded nano-SiO2" prepared in step 1), and the compatibilizer are put into a high-speed mixer and mixed thoroughly to obtain a premix.

[0035] (3) Melt extrusion and structure building: The premixed material is fed into a twin-screw extruder and melt-blended under specific temperature fields (Zone 1: 110-130℃, Zone 2 and beyond: 140-170℃) and screw shear force. During this process, montmorillonite sheets are peeled off and oriented, working synergistically with uniformly dispersed "oil-loaded nano-SiO2" to build a "labyrinthine" barrier network in the matrix; at the same time, compatibilizers ensure that the interfaces of each component are firmly bonded.

[0036] (4) Granulation: The final masterbatch is obtained by extrusion, cooling and pelleting. Example 1

[0037] 50 parts PLA / PBAT (60 / 40), 25 parts glycerol-plasticized starch, 10 parts montmorillonite, 10 parts hydrophobic nano-SiO2 loaded with cinnamon essential oil (loading ratio 1:3), and 5 parts reactive epoxy compatibilizer ethylene-acrylate-GMA terpolymer. Premixed and melt-extruded granulated according to the method described in this invention (extrusion temperature range: 115-165℃) to obtain bifunctional masterbatch C1. This is a preferred formulation based on this invention, with balanced proportions of each component, aiming to achieve the best balance between barrier and antibacterial properties, suitable for general-purpose high-value-added food packaging. Example 2

[0038] The masterbatch C2 was prepared using the following methods: 55 parts PLA, 20 parts sodium carboxymethyl cellulose (CMC), 15 parts montmorillonite, 8 parts hydrophobic nano-SiO2 loaded with thyme essential oil (loading ratio 1:2), and 7 parts glycidyl methacrylate (GMA), a reactive epoxy compatibilizer. The PLA content and montmorillonite ratio were increased, and CMC was selected to construct a denser "maze" barrier network. This sacrifices some flexibility to achieve optimal oxygen barrier performance, making it suitable for high-end foods sensitive to oxidation (such as nuts and freeze-dried foods). Example 3

[0039] 45 parts PBAT, 30 parts glycerol-plasticized starch / chitosan powder mixture (1:1), 8 parts montmorillonite, 12 parts hydrophobic nano-SiO2 loaded with peppermint essential oil (loading ratio 1:4), and 5 parts reactive epoxy compatibilizer glycidyl methacrylate (GMA). Masterbatch C3 was prepared using the same method as in Example 1. This method increases the ratio of low-cost plant polysaccharides and antibacterial agents, utilizing the flexibility of PBAT and the natural antibacterial properties of chitosan synergistically. The aim is to significantly improve antibacterial strength and reduce costs while maintaining basic barrier properties, making it suitable for packaging perishable foods such as fresh fruits and vegetables and livestock products. Example 4

[0040] 48 parts PLA / PBAT (50 / 50), 22 parts glycerol-plasticized starch, 12 parts montmorillonite, 13 parts hydrophobic nano-SiO2 loaded with composite essential oils (cinnamon: thyme = 1:1) (total loading ratio 1:3), and 5 parts reactive epoxy compatibilizer ethylene-acrylate-GMA terpolymer. Masterbatch C4 was prepared using the same method as in Example 1. Composite essential oils were used to broaden the antibacterial spectrum, and the polymer and filler ratios were finely adjusted to find the optimal balance between processability, mechanical properties, barrier properties, and antibacterial properties, meeting the highest comprehensive requirements for application scenarios (such as military supplies and maritime food packaging). Comparative Example 1

[0041] Ordinary degradation masterbatch: without adding any montmorillonite or SiO2 loaded with essential oil, the rest is the same as in Example 1, only containing PLA / PBAT, plasticized starch and compatibilizer, to obtain masterbatch D1. Comparative Example 2

[0042] Barrier-only masterbatch: Only 10 parts of montmorillonite were added, without adding SiO2 loaded with essential oil, and the rest was the same as in Example 1, to obtain masterbatch D2. Comparative Example 3

[0043] Antibacterial masterbatch only: only 10 parts of essential oil-loaded nano-SiO2 were added, without adding montmorillonite, and the rest was the same as in Example 1, to obtain masterbatch D3. Comparative Example 4

[0044] The hydrophobic nano-SiO2 loaded with cinnamon essential oil in Example 1 was replaced with hydrophobic nano-SiO2 without cinnamon essential oil to obtain masterbatch D4. Comparative Example 5

[0045] In Example 1, the hydrophobic nano-SiO2 loaded with cinnamon essential oil was replaced with cinnamon essential oil to prepare masterbatch D5.

[0046] Table 1. Mechanical and barrier properties of films prepared from the masterbatches obtained in each embodiment and comparative example.

[0047] All examples (C1-C4) exhibited an excellent balance of mechanical properties. Example 2 (C2), due to its high content and high rigidity montmorillonite lamellae orientation, showed the highest tensile strength, but with a decrease in elongation at break. Example 3 (C3), benefiting from the flexibility and plasticizing effect of PBAT, exhibited the best toughness. In terms of barrier properties, Examples 1-4 were significantly superior to Comparative Examples D1 and D3, demonstrating that the montmorillonite-dominated "maze" effect is key to improving barrier properties. Example 2 (C2) showed the best barrier data.

[0048] Table 2. Antibacterial properties of the film (inhibition zone test)

[0049] The inhibition zone test directly demonstrated that the film prepared by the masterbatch of this invention possesses the ability to actively release antibacterial components. All examples (C1-C4) produced clearly visible inhibition zones against *Escherichia coli* and *Staphylococcus aureus*, while comparative examples D1 and D2 did not exhibit this effect. Example 3 (C3), containing the highest proportion of essential oil-loaded nano-SiO2, had the largest inhibition zone diameter and the strongest antibacterial ability. Example 4 (C4), using a compound essential oil, also showed broad-spectrum and highly efficient antibacterial activity. It is noteworthy that the inhibition zones of the examples were all larger than those of comparative example D3, indicating that the montmorillonite sheet structure may, through adsorption and sustained release, synergistically with nano-SiO2 to prolong and enhance the antibacterial efficacy of the essential oil, rather than simply providing physical blockage. Examples 1-4 all exhibited nearly 100% strong antibacterial activity, while comparative examples D1 and D2 lacked this function, proving the effectiveness of the "essential oil-loaded nano-SiO2".

[0050] Table 3. Evaluation experiment on the preservation effect of litchi (stored at 4°C for 12 days)

[0051] The calculation method for the mold index is explained below: Surface mold conditions are classified into the following 5 levels: Grade 0: The peel is intact, with no visible mold spots.

[0052] Grade 1: Scattered mold spots appear on the surface of the fruit peel, and the moldy area accounts for less than 10% of the total surface area.

[0053] Level 2: Mold spots are clearly visible, with slight contiguous patches, and the moldy area accounts for 10% to 25% of the total surface area.

[0054] Level 3: Obvious mold spots, moderate rot, moldy area accounts for 26% to 50% of the total surface area.

[0055] Level 4: Severe mold spots, large areas of continuous mildew, severe soft rot or oozing, moldy area accounts for more than 50% of the total surface area.

[0056] After the specified storage period ended (e.g., day 12 in this experiment), all test lychees (30 per group) in each experimental group were observed, and the mold level of each lychee was recorded according to the above standards.

[0057] The mold index is calculated using the following formula: Mold index = [Σ(Mold level number × Number of fruits at that level) / (Highest mold level × Total number of fruits)] × 100 Based on the results in Table 3 and the accompanying figures, the litchi packaged in all embodiments of this invention exhibited significantly better fruit yield, appearance, color, and sensory quality than the comparative examples and commercially available products. This fully demonstrates the decisive role of the synergistic effect of "barrier" and "strong antibacterial" dual functions in extending the shelf life of fruits and vegetables. Comparative Example D1 showed extensive mold growth, severe browning, juice leakage, and a wine-like odor. Comparative Example D2 (barrier only) effectively reduced moisture loss (low weight loss rate) and delayed browning (higher a* value), but due to the lack of antibacterial properties, it could not effectively inhibit mold, thus limiting the fruit yield. Comparative Example D3 (antibacterial only) effectively controlled mold growth, but due to poor barrier properties, the litchi suffered severe water loss (high weight loss rate), similarly affecting the fruit yield and marketability. Comparative Examples D4 and D5 showed significant mold growth, severe browning, juice leakage, and a wine-like odor. The embodiments of the present invention, especially C3 and C4, achieve comprehensive inhibition of lychee spoilage and deterioration through the integrated regulation of moisture, oxygen, microorganisms and ethylene (the effect of essential oils), with significant preservation effect and huge market application potential.

[0058] Those skilled in the art will readily understand that the above description is only a part of the embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biodegradable preservative masterbatch with synergistic barrier and antibacterial effects, characterized in that, The biodegradable preservation masterbatch with synergistic barrier-antibacterial effect comprises, by weight, 40-60 parts of biodegradable polymer matrix, 20-30 parts of plasticized plant polysaccharide, 15-30 parts of multifunctional nanocomposite barrier agent, and 5-10 parts of compatibilizer; wherein the multifunctional nanocomposite barrier agent is a compound of layered nanoclay and hydrophobic nano-SiO2 loaded with plant essential oil.

2. The biodegradable preservative masterbatch with synergistic barrier-antibacterial effect according to claim 1, characterized in that, The mass ratio of layered nanoclay to hydrophobic nano-SiO2 loaded with plant essential oil in the multifunctional nanocomposite barrier agent is 1-2:1; preferably, the mass ratio of hydrophobic nano-SiO2 to plant essential oil in the hydrophobic nano-SiO2 loaded with plant essential oil is 1:2-4.

3. The biodegradable preservative masterbatch with synergistic barrier-antibacterial effect according to claim 1, characterized in that, The biodegradable polymer matrix is ​​polylactic acid (PLA), polybutylene adipate / terephthalate (PBAT), or a mixture of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT); preferably, the biodegradable polymer matrix is ​​a mixture of polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) in a mass ratio of 5-7:3-5.

4. The biodegradable preservation masterbatch with synergistic barrier-antibacterial effect according to claim 1, characterized in that, The layered nanoclay is montmorillonite.

5. The biodegradable preservative masterbatch with synergistic barrier-antibacterial effect according to claim 1, characterized in that, The plant essential oil is at least one of cinnamon essential oil, thyme essential oil, and peppermint essential oil.

6. The biodegradable preservative masterbatch with synergistic barrier-antibacterial effect according to claim 1, characterized in that, The plasticized plant polysaccharide is one or more of glycerol plasticized starch, sodium carboxymethyl cellulose (CMC), and chitosan powder; preferably, the plasticized plant polysaccharide is a mixture of glycerol plasticized starch and chitosan powder; preferably, the mass ratio of glycerol plasticized starch to chitosan powder is 0.9-1.1:0.9-1.

1.

7. The biodegradable preservative masterbatch with synergistic barrier-antibacterial effect according to claim 1, characterized in that, The compatibilizer is a reactive epoxy functional group compatibilizer; preferably, the reactive epoxy functional group compatibilizer is at least one of glycidyl methacrylate (GMA) and ethylene-acrylate-GMA terpolymer.

8. The method for preparing the biodegradable preservative masterbatch with synergistic barrier-antibacterial effect according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: a. Pretreatment of composite antibacterial agent: Hydrophobic nano-SiO2 is mixed with plant essential oil, so that the essential oil is fully adsorbed to obtain powdered essential oil-loaded nano-SiO2; b. Premixing: The biodegradable polymer matrix, plasticized plant polysaccharides, layered nanoclay, essential oil-loaded nano-SiO2 obtained in step a, and compatibilizer are mixed to obtain a premix. c. Melt extrusion granulation: The premixed material is fed into a twin-screw extruder, and after melt mixing, extrusion, cooling, and pelletizing, the biodegradable masterbatch is obtained; Preferably, in step c, the temperature of the first zone of the twin-screw extruder is controlled at 110-130℃, and the temperature of the subsequent zones and the die head is controlled at 140-170℃.

9. A film prepared from the biodegradable preservative masterbatch with synergistic barrier-antibacterial effect as described in any one of claims 1-7.

10. The application of the biodegradable preservative masterbatch with barrier-antibacterial dual-effect synergy as described in claims 1-7 or the film as described in claim 9 in the fields of fresh fruits and vegetables, high-end cold chain, and military food supplies, characterized in that, The application is to prepare the masterbatch or film into food preservation packaging materials.

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