Highly waterproof composite packaging bag and preparation method thereof

Abstract

The invention discloses a highly waterproof composite packaging bag and a preparation method thereof in the field of packaging materials. The highly waterproof composite packaging bag is prepared from the following raw materials: low-density polyethylene, high-density polyethylene, a perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, a dynamic covalent bond modified polyether-acrylate block polymer, an antioxidant and an ultraviolet absorber. The ternary hybrid is prepared through a reaction of hexafluoropropylene, isophorone diisocyanate and an octa-amino cage-like siloxane derivative, and contains a perfluoroalkyl group and a nanocage hydrophobic skeleton; the dynamic covalent bond modified polymer is synthesized by cross-linking reaction of polyethylene glycol, glycidyl methacrylate and a boric acid modified coupling agent, and contains dynamic and permanent cross-linked structures. According to the packaging bag, through the synergistic effect of the low-surface-energy hydrophobic component and the cross-linked network, the moisture permeability is remarkably reduced, the surface hydrophobicity is high, the water-resistant stability is high, and the packaging bag is suitable for harsh packaging scenes of food, electronic devices and the like.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to a highly waterproof composite packaging bag and its preparation method. Background Technology

[0002] In the field of packaging materials, single-layer packaging bags have long been widely used in the packaging of food, pharmaceuticals, and electronic devices due to their simple manufacturing process and low cost. These bags are typically made of polymers such as polyethylene and polypropylene, with a basic structure consisting of linear or branched polymer chains. However, due to the arrangement characteristics of polymer molecular chains, these materials naturally possess micron- to nanometer-scale pore structures between their molecular chains, and some polymer molecular chains contain polar groups that can interact with water molecules. When the packaging bag is in a high-humidity environment or in direct contact with liquid water, moisture can migrate through the pores via diffusion, penetrate along pore channels through capillary action, or even form hydrogen bonds with the polar groups, thus penetrating the packaging material and entering the interior. This phenomenon directly leads to risks such as moisture absorption, mold growth, and corrosion for the packaged products. Food may breed microorganisms due to moisture intrusion, pharmaceuticals may experience reduced efficacy or spoilage due to moisture absorption, electronic components may experience short circuits or circuit corrosion due to moisture condensation, and precision instruments may have their measurement accuracy or mechanical performance affected by humidity changes. Therefore, improving the moisture barrier properties of single-layer packaging bags has become a key issue in ensuring the quality and functional stability of the products inside the packaging.

[0003] To address the shortcomings of traditional single-layer packaging bags in terms of waterproofing performance, existing technologies primarily focus on two approaches: surface treatment and filler addition. Surface treatment typically involves coating the polymer matrix with a hydrophobic layer. The low surface energy and weak affinity of the coating material for water molecules prevent water droplets from spreading and causing them to roll off, thus reducing water penetration. However, this type of coating relies mainly on physical adhesion to the substrate, making it susceptible to damage from friction, aging, UV radiation, and temperature changes over long-term use. This can lead to localized peeling, cracking, or performance degradation, ultimately compromising the overall waterproofing effect. Furthermore, controlling the uniformity of the coating is challenging; weak areas can allow water to preferentially penetrate, creating a channel effect. Another approach involves adding hydrophobic fillers during polymer processing. The filler's hydrophobic surface properties and steric hindrance effect create a physical barrier layer within the polymer matrix, reducing the path of water penetration. However, this method has limitations. Nanoscale fillers are prone to agglomeration in polymer matrices due to their high surface energy, making uniform dispersion impossible. Agglomerated fillers not only fail to effectively block moisture penetration channels but may also form defective regions in the matrix, becoming entry points for preferential moisture penetration. Furthermore, some fillers may migrate and precipitate, affecting the hygiene, safety, and long-term performance of the packaging material. These issues make traditional improvement methods insufficient for applications with stringent waterproofing requirements, such as food and pharmaceutical manufacturing. Therefore, there is an urgent need to develop a novel single-layer packaging material that can fundamentally improve waterproofing performance at the molecular level.

[0004] To address the aforementioned technical bottlenecks, this invention proposes an innovative solution: by synthesizing two novel modified compounds, a waterproofing mechanism is constructed within a single-layer polyethylene matrix through the synergistic effect of a low-surface-energy hydrophobic structure and a cross-linked network. Specifically, by designing a hybrid containing perfluoroalkyl groups and cage-like polysilsesquioxanes, the low surface energy of the perfluoroalkyl groups reduces the overall hydrophilicity of the material, making it easier for water droplets to roll off the surface. Simultaneously, the nanoscale rigid structure of the cage-like polysilsesquioxanes fills the micropores between polymer molecular chains, reducing the channels for water penetration at the source. Simultaneously, the introduction of modified polymers containing dynamic covalent bonds and permanent cross-links allows energy to be consumed during the breakage and recombination process of dynamic bonds during water penetration, slowing down the rate of water diffusion. Furthermore, the permanent cross-links form a stable three-dimensional network structure, enhancing the overall density of the material and further preventing deep water penetration. These two modified compounds are uniformly dispersed in the polyethylene matrix through a blending process. Without relying on surface coatings or physical fillers, they can simultaneously improve the hydrophobicity and structural stability of the material at the molecular level. This maintains the original flexibility, processing adaptability, and hygiene safety of the polyethylene matrix while significantly enhancing its waterproof performance, providing a more reliable packaging solution for products with extremely high moisture protection requirements, such as food, pharmaceuticals, and electronic devices. Summary of the Invention

[0005] The purpose of this invention is to provide a highly waterproof composite packaging bag and its preparation method, which solves the technical problems of existing packaging bags having poor waterproofness and being susceptible to moisture, and existing improved methods having coatings that are easy to peel off, fillers that are unevenly dispersed, and complex processes.

[0006] The present invention achieves the above objectives through the following technical solutions: A highly waterproof composite packaging bag comprises the following raw materials in parts by weight: Low-density polyethylene: 750-900 parts by weight; High-density polyethylene: 50-150 parts by weight; Perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid: 20-60 parts by weight; Dynamically covalently modified polyether-acrylate block polymer: 10-40 parts by weight; Antioxidant: 1-3 parts by weight; Ultraviolet absorber: 0.5-1 parts by weight; The preparation method of the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid includes: A1, mixing hexafluoropropylene and tetrahydrofuran, adding 1,4-bis(trifluoromethyl)phenyllithium under nitrogen protection, and reacting at -78°C to generate a perfluoroalkyl lithium intermediate; then adding isophorone diisocyanate, and heating to 25-30°C to react and form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups; simultaneously reacting octaaminoPOSS with hydroxyethyl acrylate in N,N-dimethylformamide solvent to obtain an amino-terminated POSS-HEA derivative; A2, finally mixing the perfluoroalkyl polyurethane prepolymer, the POSS-HEA derivative, and dibutyltin dilaurate, reacting at 60-80°C, precipitating with acetone, washing, and vacuum drying.

[0007] In this invention, the synthesis of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrids achieves precise molecular-level construction through multi-step chemical reactions. The core lies in the synergistic assembly of perfluoroalkyl segments, polyurethane segments, and polysilsesquioxane (POSS) nanocage structures. First, hexafluoropropylene and tetrahydrofuran are mixed under nitrogen protection, and a strongly basic 1,4-bis(trifluoromethyl)phenyllithium is added as an initiator to initiate the reaction at extremely low temperatures (-78°C). In this step, the double bonds in the hexafluoropropylene molecule undergo deprotonation under the action of a strong base, generating a perfluoroalkyl lithium intermediate. This intermediate is a key active precursor for the subsequent introduction of isocyanate groups. As the reaction system temperature gradually increases, the perfluoroalkyl lithium intermediate undergoes a nucleophilic addition reaction with isophorone diisocyanate. The isocyanate group (a highly active functional group) combines with the lithium ions of the perfluoroalkyl lithium intermediate to form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups. In this process, the isocyanate groups act as "connecting points" for subsequent polymerization reactions, providing active sites for the extension of polyurethane segments. Meanwhile, the perfluoroalkyl segments (derived from hexafluoropropylene) impart excellent hydrophobic properties to the material due to their extremely low surface energy. Simultaneously, another reaction system is carried out in N,N-dimethylformamide solvent: octaaminoPOSS (cage-like siloxane nanoparticles with eight amino functional groups) undergoes a condensation reaction with hydroxyethyl acrylate. Each amino functional group of the octaaminoPOSS forms a stable amide bond with the hydroxyl group of hydroxyethyl acrylate through dehydration condensation, ultimately generating an amino-terminated POSS-HEA derivative. This derivative retains the rigid structure of the POSS nanocage (cubic octahedral cage-like siloxane framework) while introducing amino active sites that can react with the polyurethane segments. When a perfluoroalkyl polyurethane prepolymer, a POSS-HEA derivative, and a catalyst, dibutyltin dilaurate, are mixed and heated to 60-80°C, the isocyanate groups in the prepolymer undergo a secondary nucleophilic addition reaction with the amino groups of the POSS-HEA derivative, forming stable urea bonds. This step achieves covalent bonding between the perfluoroalkyl polyurethane segments and the POSS nanocages. The perfluoroalkyl segments are uniformly dispersed in the material through the polyurethane backbone, while the POSS nanocages act as a rigid framework filling the micropores between the polymer molecular chains. Together, they construct a composite structure of "low surface energy hydrophobic layer + physical barrier." Finally, the reaction product is precipitated with acetone to remove unreacted monomers, washed to remove impurities, and then vacuum dried to obtain a high-purity ternary hybrid. In the molecular structure of this hybrid, the perfluoroalkyl segments provide extremely low surface energy (reducing the affinity for water molecules), the POSS nanocages inhibit water permeation channels, and the polyurethane segments enhance compatibility with the matrix polymer, laying the molecular foundation for subsequent blending with a polyethylene matrix.

[0008] According to a preferred embodiment of the present invention, the low-density polyethylene was purchased from China Petroleum & Chemical Corporation (model: LDPE 2426H).

[0009] According to a preferred embodiment of the present invention, the high-density polyethylene was purchased from China National Petroleum Corporation (model: HDPE 5000S).

[0010] According to a preferred embodiment of the present invention, the hexafluoropropylene was purchased from Sinochem Lantian Group Co., Ltd. (purity ≥ 99.5%).

[0011] According to a preferred embodiment of the present invention, the tetrahydrofuran was purchased from Sinopharm Chemical Reagent Co., Ltd. (analytical grade, specification: ≥99.9%).

[0012] According to a preferred embodiment of the present invention, the nitrogen gas is purchased from Air Liquide (China) Investment Co., Ltd. (purity ≥99.999%).

[0013] According to a preferred embodiment of the present invention, the 1,4-bis(trifluoromethyl)phenyllithium was purchased from Aladdin Reagent (Shanghai) Co., Ltd. (purity ≥95%).

[0014] According to a preferred embodiment of the present invention, the isophorone diisocyanate was purchased from Wanhua Chemical Group Co., Ltd. (model: IPDI, purity ≥99%).

[0015] According to a preferred embodiment of the present invention, the octaaminoPOSS was purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd. (model: OCTA-POSS-NH2).

[0016] According to a preferred embodiment of the present invention, the hydroxyethyl acrylate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (purity ≥ 99%).

[0017] According to a preferred embodiment of the present invention, the N,N-dimethylformamide was purchased from Tianjin Kemei Chemical Reagent Co., Ltd. (analytical grade, specification: ≥99.5%).

[0018] According to a preferred embodiment of the present invention, the dibutyltin dilaurate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. (purity ≥ 95%).

[0019] According to a preferred embodiment of the present invention, the acetone was purchased from Sinopharm Chemical Reagent Co., Ltd. (analytical grade, specification: ≥99.5%).

[0020] According to a preferred embodiment of the present invention, the antioxidant was purchased from BASF (China) Co., Ltd. (model: antioxidant 1010).

[0021] According to a preferred embodiment of the present invention, the ultraviolet absorber is purchased from Ciba Specialty Chemicals (China) Co., Ltd. (model: UV-531).

[0022] According to a preferred embodiment of the present invention, in step A1, the volume ratio of hexafluoropropylene to tetrahydrofuran is 1:2; the reaction time is 3-5 h at -78°C; the reaction time is 2-4 h at 25-30°C; the molar ratio of octaaminoPOSS to hydroxyethyl acrylate is 1:2; and the reaction time is 1-2 h in N,N-dimethylformamide solvent.

[0023] According to a preferred embodiment of the present invention, in step A2, the reaction time is 6-10 h at 60-80°C.

[0024] According to a preferred embodiment of the present invention, the preparation method of the dynamically covalently modified polyether-acrylate block polymer includes: B1, adding polyethylene glycol and glycidyl methacrylate to toluene solvent, adding p-toluenesulfonic acid under nitrogen protection, and heating to 110-130°C to react and generate epoxy-terminated polyether-acrylate prepolymer; simultaneously reacting boric acid and 3-aminopropyltriethoxysilane in ethanol solvent to obtain boric acid-modified silane coupling agent; B2, subsequently mixing the epoxy-terminated polyether-acrylate prepolymer, the boric acid-modified silane coupling agent and a photoinitiator, reacting at 50-70°C, and distilling under reduced pressure.

[0025] In this invention, the synthesis of dynamically covalently modified polyether-acrylate block polymers constructs a dual-functional system of "epoxy-terminated prepolymer and dynamic crosslinking agent" through a stepwise reaction. The core of this system lies in utilizing the synergistic effect of dynamic covalent bonds (such as borate ester bonds) and permanent crosslinking bonds (such as epoxy groups) to form a dense network structure. In the first step, polyethylene glycol and glycidyl methacrylate are added to toluene solvent in a molar ratio of 1:1, and p-toluenesulfonic acid (an acidic catalyst) is added under nitrogen protection. The reaction system is heated to 110-130°C, where the hydroxyl groups of polyethylene glycol and the epoxy groups of glycidyl methacrylate undergo a ring-opening reaction: the epoxy ring opens under acidic conditions, and the oxygen atom combines with the hydrogen atom in the hydroxyl group to generate water molecules. Simultaneously, the carbon atom of the epoxy ring forms a new ether bond with the carbon atom of the hydroxyl group, ultimately generating an epoxy-terminated polyether-acrylate prepolymer. This prepolymer retains the flexibility of the polyethylene glycol segments (providing material toughness) and the epoxy groups derived from glycidyl methacrylate (serving as active sites for subsequent crosslinking). In another reaction system, boric acid and 3-aminopropyltriethoxysilane undergo a condensation reaction in ethanol solvent. The three hydroxyl groups of boric acid and the amino groups at the end of the silane coupling agent undergo dehydration condensation to form a boric acid-modified silane coupling agent. This coupling agent contains both boric acid groups (which can form dynamic borate ester bonds) and silane groups (enhancing the binding force with the polymer matrix). When the epoxy-terminated polyether-acrylate prepolymer, the boric acid-modified silane coupling agent, and the photoinitiator are mixed and heated to 50-70°C, multiple reactions occur within the system: on the one hand, the epoxy groups can form a permanent crosslinked network (three-dimensional structure) with the hydroxyl groups of the prepolymer itself or other active sites through ring-opening reactions; on the other hand, the boric acid groups in the boric acid-modified silane coupling agent react with the hydroxyl groups on the prepolymer segments to generate dynamic borate ester bonds. Dynamic borate ester bonds exhibit reversible properties; under the influence of water penetration or external forces, these bonds can break and reform, slowing down the rate of water penetration through this dynamic energy dissipation mechanism. Meanwhile, permanent crosslinking bonds form a stable three-dimensional network structure, filling microscopic defects in the polymer matrix and further enhancing overall barrier performance. Finally, solvent removal via vacuum distillation yields a modified polymer containing both dynamic and permanent crosslinking structures. This polymer exhibits both reversible dynamic crosslinking (consuming penetration energy) and permanent chemical crosslinking (maintaining structural stability) between its molecular chains, providing the packaging bag with dual protection capabilities of "self-healing" and "long-term barrier."

[0026] According to a preferred embodiment of the present invention, the polyethylene glycol was purchased from Haian Petrochemical Plant in Jiangsu Province (model: PEG-1000).

[0027] According to a preferred embodiment of the present invention, the glycidyl methacrylate was purchased from Shanghai Huayi Acrylic Acid Co., Ltd. (model: GMA, purity ≥98%).

[0028] According to a preferred embodiment of the present invention, the toluene was purchased from Sinopharm Chemical Reagent Co., Ltd. (analytical grade, specification: ≥99.5%).

[0029] According to a preferred embodiment of the present invention, the p-toluenesulfonic acid was purchased from Tianjin Kemei Chemical Reagent Co., Ltd. (analytical grade, specification: ≥99%).

[0030] According to a preferred embodiment of the present invention, the boric acid was purchased from Xilong Scientific Co., Ltd. (analytical grade, specification: ≥99.5%).

[0031] According to a preferred embodiment of the present invention, the 3-aminopropyltriethoxysilane was purchased from Nanjing Daoning Chemical Co., Ltd. (model: KH550, purity ≥98%).

[0032] According to a preferred embodiment of the present invention, the ethanol was purchased from Sinopharm Chemical Reagent Co., Ltd. (analytical grade, specification: ≥99.7%).

[0033] According to a preferred embodiment of the present invention, the photoinitiator was purchased from Tianjin Jiuri New Material Co., Ltd. (model: 1173, purity ≥99%).

[0034] According to a preferred embodiment of the present invention, the high-speed mixer was purchased from Zhangjiagang Tonghui Chemical Machinery Co., Ltd. (model: SHR-50A).

[0035] According to a preferred embodiment of the present invention, the single-screw extruder was purchased from Nanjing Keya Chemical Complete Equipment Co., Ltd. (model: TE-65).

[0036] According to a preferred embodiment of the present invention, the ultraviolet curing machine was purchased from Shenzhen Sankun Technology Co., Ltd. (model: SK-UV365).

[0037] According to a preferred embodiment of the present invention, in step B1, the molar ratio of polyethylene glycol to glycidyl methacrylate is 1:1; the reaction time is 4-6 h at 110-130 °C; the molar ratio of boric acid to 3-aminopropyltriethoxysilane is 1:2, and the reaction time is 2-3 h in ethanol solvent.

[0038] According to a preferred embodiment of the present invention, in step B2, the reaction time is 3-5 hours at 50-70°C.

[0039] The present invention also provides a method for preparing the aforementioned highly waterproof composite packaging bag, comprising the following steps: S1. Add low-density polyethylene, high-density polyethylene, perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, dynamically covalently modified polyether-acrylate block polymer, antioxidant and ultraviolet absorber to a high-speed mixer and stir at 50-60℃ until uniformly dispersed. S2. The mixture is then added to a single screw extruder, melted and plasticized, and extruded into a film through a T-die. After being shaped by cooling rollers, traction, corona treatment, and then wound up. S3. Finally, place the rolled-up film in an ultraviolet curing machine for irradiation.

[0040] In this invention, the final waterproof performance of the high-waterproof composite packaging bag is achieved through the synergistic effect of the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid and the dynamically covalently modified polyether-acrylate block polymer in the polyethylene matrix. Essentially, it is a multi-layered protection mechanism of "low surface energy hydrophobic layer + physical barrier + dynamic / permanent cross-linked network". In the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, the perfluoroalkyl segments (extremely low surface energy) are uniformly dispersed between the polyethylene molecular chains, significantly reducing the affinity of water molecules on the material surface, causing water droplets to tend to form spheres and roll off upon contact. The rigid cage structure of the POSS nanocage fills the micropores originally present between the polyethylene molecular chains, physically blocking the diffusion channels of water and reducing the penetration path. Dynamically covalently modified polyether-acrylate block polymers enhance the internal density of the material through the synergistic effect of dynamic borate bonds and permanent epoxy groups. The dynamic borate bonds undergo a reversible breakage-reorganization reaction during water penetration, slowing down the rate of water diffusion. The permanent epoxy groups form a stable three-dimensional network structure, filling microscopic defects in the polymer matrix and further improving overall barrier properties. During preparation, the three components achieve functional integration through blending and UV curing: low-density polyethylene provides flexibility, high-density polyethylene enhances structural strength, and the ternary hybrid and modified polymer are uniformly dispersed in the matrix. A single-screw extruder melts and plasticizes the mixture and extrudes it into a film. After cooling and roller shaping, corona treatment enhances surface activity. Finally, a UV curing machine causes photopolymerization of the acrylate groups in the modified polymer, further strengthening the cross-linked network. This synergistic effect significantly reduces the water vapor permeability of the packaging bag and maintains stable waterproof performance under long-term high humidity, high temperature, or water immersion environments. Its synergistic reaction mechanism breaks through the limitations of traditional single-layer packaging materials that rely on a single coating or filler. Through molecular-level modification, it achieves an essential improvement in waterproof performance, providing a reliable technical solution for the packaging of products with high moisture resistance requirements.

[0041] According to a preferred embodiment of the present invention, in step S1, the stirring time at 50-60°C is 10-15 min.

[0042] According to a preferred embodiment of the present invention, in step S2, the barrel temperature of the single-screw extruder is 180-210°C and the screw speed is 80-100 rpm.

[0043] According to a preferred embodiment of the present invention, in step S3, the ultraviolet light wavelength of the ultraviolet curing machine is 365 nm, the intensity is 150-200 mW / cm², and the irradiation time is 8-12 min.

[0044] The beneficial effects of this invention are as follows: This invention's highly waterproof composite packaging bag, through unique material design and manufacturing process, significantly improves the waterproof performance of traditional single-layer packaging materials, solving the long-standing industry problem of water penetration. Its core advantage lies in the synergistic effect of two novel modified compounds, constructing a multi-layered waterproof barrier within the polymer matrix. The perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid utilizes the extremely low surface energy of the perfluoroalkyl segments to create a hydrophobic environment on the material surface, significantly reducing the affinity between water molecules and the packaging bag surface. Water droplets are more likely to form spheres and roll off upon contact, reducing adhesion. Simultaneously, the cage-like nanostructure of polysilsesquioxane is uniformly dispersed within the polymer matrix, filling the micropores originally present between molecular chains and physically blocking the channels for water diffusion. The dynamically covalently modified polyether-acrylate block polymer forms a stable three-dimensional network structure within the material through the dual action of dynamic covalent bonds and permanent crosslinking bonds. When moisture attempts to penetrate, dynamic bonds consume energy through a break-recombination process, slowing down the penetration rate; permanent cross-linking bonds enhance the overall density of the matrix, further preventing moisture from penetrating deeper. Through the synergistic effect of these two compounds, the packaging bag not only achieves extremely low initial moisture permeability but also maintains stable waterproof performance over long-term use, effectively protecting food, pharmaceuticals, electronic devices, and other products inside the packaging from damage caused by humid environments.

[0045] From the perspective of long-term stability and weather resistance, the composite packaging bag of this invention breaks through the performance limitations of traditional waterproof materials. Traditional surface coating technology relies on the physical adhesion between the coating and the substrate. After long-term use, the coating is prone to peeling off due to friction, aging, or environmental stress, causing the waterproof performance to rapidly decline. On the other hand, filler addition methods are difficult to form a uniform barrier layer due to filler agglomeration problems, and some fillers may migrate and precipitate, affecting the safety of the material. This invention directly integrates hydrophobic functional groups and cross-linked structures into the polyethylene matrix through chemical modification, avoiding the risks of coating peeling or filler agglomeration. The polysilsesquioxane nanocages in the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid form a stable bond with the polymer chain, preventing the migration and precipitation of perfluoroalkyl segments and ensuring the durability of the surface hydrophobic effect. The cross-linked network in the dynamically covalently modified polyether-acrylate block polymer is anchored in the matrix by chemical bonds, and can still maintain structural integrity after high temperature, high humidity, or long-term water immersion.

[0046] The preparation process of this invention also considers both production efficiency and material compatibility, providing a feasible solution for large-scale application. Traditional waterproof modification technologies often require multi-step coating or complex surface treatments, which not only increases production costs but may also lead to unstable product quality due to the difficulty of process control. Filler addition methods require precise control of the dispersion process; otherwise, material performance fluctuations are likely to occur. This invention directly adds two modified compounds to the polyethylene matrix through a blending process, eliminating the need for additional coating steps and simplifying the production process. The melt plasticizing and molding process of the single-screw extruder is compatible with existing packaging material production lines, requiring no significant equipment modifications and reducing equipment investment costs for enterprises. Simultaneously, the combination of low-density polyethylene and high-density polyethylene retains the original flexibility and heat-sealing properties of the polyethylene matrix, ensuring that the packaging bags are easy to process and meet sealing requirements. The addition of antioxidants and UV absorbers further enhances the material's aging resistance and extends its service life. This technical solution achieves superior waterproofing while maintaining good processing adaptability, mechanical properties, and hygiene safety, making it widely applicable in fields with extremely high requirements for moisture-proof packaging, such as food, pharmaceuticals, and precision electronic devices, and possessing significant market promotion value and application prospects. Detailed Implementation

[0047] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0048] Example 1 Preparation of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrids: 20g of hexafluoropropylene and 40g of tetrahydrofuran were added to a reaction vessel. Nitrogen gas was introduced at a flow rate of 50ml / min for 30 minutes under a nitrogen atmosphere to purge oxygen. Then, 0.1g of 1,4-bis(trifluoromethyl)phenyllithium was added, and the reaction was carried out with magnetic stirring at -78℃ (temperature controlled by a liquid nitrogen-ethanol bath) for 3 hours to generate a perfluoroalkyl lithium intermediate. Subsequently, 12g of isophorone diisocyanate was added at a rate of 2g / min, and the temperature was increased to 25℃ at a rate of 3℃ / min for 2 hours to form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups. Simultaneously, octaaminoPOSS... 5g of hydroxyethyl acrylate and 10g of hydroxyethyl acrylate were added to N,N-dimethylformamide solvent (volume 20ml), and the mixture was stirred at 40 rpm for 1 hour under nitrogen protection to obtain an amino-terminated POSS-HEA derivative. Finally, the perfluoroalkyl polyurethane prepolymer, the POSS-HEA derivative and 0.03g of dibutyltin dilaurate were mixed and stirred at 50 rpm for 6 hours at 60℃ (temperature controlled by a water bath). After precipitation with acetone (acetone volume 3 times the reaction liquid volume), washing with deionized water (washing 3 times, each time with water volume 5 times the precipitate volume), and vacuum drying (vacuum degree -0.09MPa, temperature 60℃, time 12 hours), a perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid was obtained. Preparation of dynamically covalently modified polyether-acrylate block polymer: 10g of polyethylene glycol and 10g of glycidyl methacrylate were added to toluene solvent (volume 30ml). Under nitrogen protection, the mixture was stirred at a rate of 30 rpm, and 0.01g of p-toluenesulfonic acid was added. The temperature was increased to 110℃ at a rate of 5℃ per minute, and the reaction was carried out for 4 hours to generate epoxy-terminated polyether-acrylate prepolymer. Simultaneously, 1g of boric acid and 2g of 3-aminopropyltriethoxysilane were added to ethanol solvent (volume 10ml). In 15 ml of nitrogen, the mixture was stirred at 40 rpm for 2 hours to obtain a boric acid-modified silane coupling agent. Subsequently, the epoxy-terminated polyether-acrylate prepolymer, the boric acid-modified silane coupling agent, and 0.01 g of photoinitiator were mixed and reacted at 50 °C (temperature controlled by oil bath) at 40 rpm for 3 hours. The mixture was then distilled under reduced pressure (vacuum degree -0.095 MPa, temperature 65 °C) to obtain a dynamically covalently modified polyether-acrylate block polymer.Preparation of high-waterproof composite packaging bags: 750g of low-density polyethylene, 50g of high-density polyethylene, 20g of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, 10g of dynamically covalently modified polyether-acrylate block polymer, 1g of antioxidant, and 0.5g of UV absorber are added to a high-speed mixer (5L capacity). The mixture is stirred at 50℃ (temperature controlled by jacketed circulating water) at a rate of 80 rpm for 10 minutes until uniformly dispersed. The mixture is then added to a single-screw extruder (screw diameter 30mm), with the barrel temperature adjusted from... The temperature range from the feeding section to the die head is set sequentially as follows: 180℃ (feeding section), 190℃ (compression section), 200℃ (metering section), and 210℃ (die head). The screw speed is 80 rpm. After melting and plasticizing, the film is extruded through a T-die (die lip gap is 1 mm) to form a film. After being shaped by a cooling roller (temperature is 25℃), traction (traction speed is 5 m / min), corona treatment (power is 5 kW), and then wound up. Finally, the wound film is placed in an ultraviolet curing machine with an ultraviolet wavelength of 365 nm and an intensity of 150 mW / cm² for 8 minutes.

[0049] Example 2 The specific implementation method is the same as in Example 1, except that the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is prepared as follows: 30g of hexafluoropropylene and 60g of tetrahydrofuran are mixed, and 0.15g of 1,4-bis(trifluoromethyl)phenyllithium is added under nitrogen protection. The mixture is reacted at -78°C for 4 hours to generate a perfluoroalkyl lithium intermediate. Subsequently, 18g of isophorone diisocyanate is added, and the mixture is heated to 28°C and reacted for 3 hours to form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups. At the same time, 7g of octaamino POSS and 14g of hydroxyethyl acrylate are reacted in N,N-dimethylformamide solvent for 1.5 hours to obtain an amino-terminated POSS-HEA derivative. Finally, the perfluoroalkyl polyurethane prepolymer, the POSS-HEA derivative, and 0.05g of dibutyltin dilaurate are mixed and reacted at 70°C for 8 hours. After precipitation with acetone, washing, and vacuum drying, the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is obtained. Preparation of dynamically covalently modified polyether-acrylate block polymer: 15g of polyethylene glycol and 15g of glycidyl methacrylate were added to toluene solvent, and 0.02g of p-toluenesulfonic acid was added under nitrogen protection. The mixture was heated to 120℃ and reacted for 5 hours to generate epoxy-terminated polyether-acrylate prepolymer. Simultaneously, 1.5g of boric acid and 3g of 3-aminopropyltriethoxysilane were reacted in ethanol solvent for 2.5 hours to obtain boric acid-modified silane coupling agent. Subsequently, the epoxy-terminated polyether-acrylate prepolymer, boric acid-modified silane coupling agent and 0.02g of photoinitiator were mixed and reacted at 60℃ for 4 hours. The mixture was then distilled under reduced pressure to obtain the dynamically covalently modified polyether-acrylate block polymer. Preparation of high waterproof composite packaging bags: Take 800g of low-density polyethylene, 100g of high-density polyethylene, 40g of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, 20g of dynamically covalently modified polyether-acrylate block polymer, 2g of antioxidant, and 0.7g of ultraviolet absorber and add them to a high-speed mixer. Stir at 55℃ for 12 minutes until uniformly dispersed. Then add the mixture to a single-screw extruder with a barrel temperature of 195℃ and a screw speed of 90rpm. After melting and plasticizing, extrude it into a film through a T-die. After being shaped by cooling rollers, traction, and corona treatment, the film is wound up. Finally, place the wound film in an ultraviolet curing machine with an ultraviolet wavelength of 365nm and an intensity of 175mW / cm² and irradiate for 10 minutes.

[0050] Example 3 The specific implementation method is the same as in Example 1, except that the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is prepared as follows: 40g of hexafluoropropylene and 80g of tetrahydrofuran are mixed, and 0.2g of 1,4-bis(trifluoromethyl)phenyllithium is added under nitrogen protection. The mixture is reacted at -78°C for 5 hours to generate a perfluoroalkyl lithium intermediate. Subsequently, 24g of isophorone diisocyanate is added, and the mixture is heated to 30°C and reacted for 4 hours to form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups. At the same time, 10g of octaamino POSS and 20g of hydroxyethyl acrylate are reacted in N,N-dimethylformamide solvent for 2 hours to obtain an amino-terminated POSS-HEA derivative. Finally, the perfluoroalkyl polyurethane prepolymer, the POSS-HEA derivative, and 0.07g of dibutyltin dilaurate are mixed and reacted at 80°C for 10 hours. After precipitation with acetone, washing, and vacuum drying, the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is obtained. Preparation of dynamically covalently modified polyether-acrylate block polymer: 20g of polyethylene glycol and 20g of glycidyl methacrylate were added to toluene solvent, and 0.03g of p-toluenesulfonic acid was added under nitrogen protection. The mixture was heated to 130℃ and reacted for 6 hours to generate an epoxy-terminated polyether-acrylate prepolymer. Simultaneously, 2g of boric acid and 4g of 3-aminopropyltriethoxysilane were reacted in ethanol solvent for 3 hours to obtain a boric acid-modified silane coupling agent. Subsequently, the epoxy-terminated polyether-acrylate prepolymer, the boric acid-modified silane coupling agent, and 0.03g of photoinitiator were mixed and reacted at 70℃ for 5 hours. The mixture was then distilled under reduced pressure to obtain the dynamically covalently modified polyether-acrylate block polymer. Preparation of high waterproof composite packaging bags: Take 900g of low-density polyethylene, 150g of high-density polyethylene, 60g of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, 40g of dynamically covalently modified polyether-acrylate block polymer, 3g of antioxidant, and 1g of ultraviolet absorber and add them to a high-speed mixer. Stir at 60℃ for 15 minutes until uniformly dispersed. Then add the mixture to a single-screw extruder with a barrel temperature of 210℃ and a screw speed of 100rpm. After melting and plasticizing, extrude it into a film through a T-die. After being shaped by cooling rollers, traction, and corona treatment, the film is wound up. Finally, place the wound film in an ultraviolet curing machine with an ultraviolet wavelength of 365nm and an intensity of 200mW / cm² for 12 minutes.

[0051] Comparative Example 1 The specific implementation method is the same as in Example 1, except that the high waterproof composite packaging bag is prepared as follows: 750g of low-density polyethylene, 50g of high-density polyethylene, 1g of antioxidant, and 0.5g of ultraviolet absorber are added to a high-speed mixer and stirred at 50°C for 10 minutes until uniformly dispersed; then the mixture is added to a single-screw extruder with a barrel temperature of 180°C and a screw speed of 80 rpm. After melting and plasticizing, it is extruded into a film through a T-die, shaped by a cooling roller, traction, corona treatment, and then wound up; finally, the wound film is placed in an ultraviolet curing machine with an ultraviolet wavelength of 365nm and an intensity of 150mW / cm² for 8 minutes.

[0052] Comparative Example 2 The specific implementation method is the same as in Example 1, except that the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is prepared as follows: 20g of hexafluoropropylene and 40g of tetrahydrofuran are mixed, and 0.1g of 1,4-bis(trifluoromethyl)phenyllithium is added under nitrogen protection. The mixture is reacted at -78°C for 3 hours to generate a perfluoroalkyl lithium intermediate. Subsequently, 12g of isophorone diisocyanate is added, and the mixture is heated to 25°C and reacted for 2 hours to form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups. At the same time, 5g of octaamino POSS and 10g of hydroxyethyl acrylate are reacted in N,N-dimethylformamide solvent for 1 hour to obtain an amino-terminated POSS-HEA derivative. Finally, the perfluoroalkyl polyurethane prepolymer, the POSS-HEA derivative, and 0.03g of dibutyltin dilaurate are mixed and reacted at 60°C for 6 hours. After precipitation with acetone, washing, and vacuum drying, the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is obtained. Preparation of high waterproof composite packaging bags: Take 750g of low-density polyethylene, 50g of high-density polyethylene, 20g of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, 1g of antioxidant, and 0.5g of ultraviolet absorber and add them to a high-speed mixer. Stir at 50℃ for 10 minutes until uniformly dispersed. Then add the mixture to a single-screw extruder with a barrel temperature of 180℃ and a screw speed of 80rpm. After melting and plasticizing, extrude it into a film through a T-die. After being shaped by cooling rollers, traction, and corona treatment, the film is wound up. Finally, place the wound film in an ultraviolet curing machine with an ultraviolet wavelength of 365nm and an intensity of 150mW / cm² for 8 minutes.

[0053] Comparative Example 3 The specific implementation method is the same as in Example 1, except that the dynamically covalently modified polyether-acrylate block polymer is prepared as follows: 10g of polyethylene glycol and 10g of glycidyl methacrylate are added to toluene solvent, and 0.01g of p-toluenesulfonic acid is added under nitrogen protection. The mixture is heated to 110°C and reacted for 4 hours to generate an epoxy-terminated polyether-acrylate prepolymer. At the same time, 1g of boric acid and 2g of 3-aminopropyltriethoxysilane are reacted in ethanol solvent for 2 hours to obtain a boric acid-modified silane coupling agent. Subsequently, the epoxy-terminated polyether-acrylate prepolymer, the boric acid-modified silane coupling agent, and 0.01g of photoinitiator are mixed and reacted at 50°C for 3 hours. The mixture is then distilled under reduced pressure to obtain the dynamically covalently modified polyether-acrylate block polymer. Preparation of high waterproof composite packaging bags: Take 750g of low-density polyethylene, 50g of high-density polyethylene, 10g of dynamically covalently modified polyether-acrylate block polymer, 1g of antioxidant, and 0.5g of ultraviolet absorber and add them to a high-speed mixer. Stir at 50℃ for 10 minutes until uniformly dispersed. Then add the mixture to a single-screw extruder with a barrel temperature of 180℃ and a screw speed of 80rpm. After melting and plasticizing, extrude it into a film through a T-die. After being shaped by cooling rollers, traction, and corona treatment, the film is wound up. Finally, place the wound film in an ultraviolet curing machine with an ultraviolet wavelength of 365nm and an intensity of 150mW / cm² for 8 minutes.

[0054] Performance testing The polymer composite anti-aging bird umbrella covers prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following methods: Water vapor transmission rate test: The test was conducted according to GB / T 1037-1988 "Test Method for Water Vapor Permeability of Plastic Films and Sheets - Cup Method". The highly waterproof composite packaging bags prepared in the examples and comparative examples were cut into circular samples with a diameter of 90 mm. These samples were equilibrated in a constant temperature and humidity chamber at 38℃ and 90% relative humidity for 24 hours. Then, the samples were sealed in a permeation cup containing 50 ml of distilled water and placed in the constant temperature and humidity chamber. The mass change of the permeation cup was measured every 24 hours for 3 consecutive days. The average value was used to calculate the water vapor transmission rate. The calculation formula is P = Δm / A·t·Δp, where P is the water vapor transmission rate (g / (m²)). 2 ·24h), Δm is the increase in mass of the permeation cup (g), and A is the effective area of ​​the sample (m²). 2), t is the test time (h), and Δp is the water vapor pressure difference across the sample (Pa). Contact angle test: The static contact angle test method was used with a contact angle measuring instrument. The high waterproof composite packaging bags prepared in the examples and comparative examples were cut into 10mm×10mm square samples, placed flat on the sample stage of the contact angle measuring instrument, and 5μl of deionized water was dropped onto the sample surface using a micro-syringe. The contact angle between the water droplet and the sample surface was measured using an image analysis system. Five different positions were measured for each sample, and the average value was taken. Tensile strength and elongation at break test: The test was conducted according to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets". The highly waterproof composite packaging bags prepared in the examples and comparative examples were cut into strips with a width of 15 mm and a length of 150 mm. These strips were conditioned for 24 hours at a temperature of 23°C and a relative humidity of 50%. Then, they were tested using a universal testing machine at a tensile rate of 50 mm / min. The maximum load and elongation at break were recorded, and the tensile strength and elongation at break were calculated. The formula for tensile strength is σ = F / b·d, where σ is the tensile strength (MPa), F is the maximum load at break (N), b is the sample width (mm), and d is the sample thickness (mm). The formula for elongation at break is ε = L−L0 / L×100%, where ε is the elongation at break (%), L is the sample length at break (mm), and L0 is the initial sample length (mm). Heat seal strength test: The test was conducted according to QB / T2358-1998 "Test Method for Heat Seal Strength of Plastic Film Packaging Bags". The highly waterproof composite packaging bags prepared in the examples and comparative examples were cut into sample strips with a width of 15 mm. They were heat-sealed for 3 seconds at a temperature of 180°C and a pressure of 0.2 MPa to form a heat-sealed edge. Then, the heat-sealed edge was stretched using a universal testing machine at a tensile rate of 300 mm / min until the heat-sealed edge broke. The maximum load at the time of breakage was recorded, and the heat-sealing strength was calculated using the formula T = F / b, where T is the heat-sealing strength (N / 15 mm), F is the maximum load at the time of breakage (N), and b is the sample width (15 mm). Water resistance test: The highly waterproof composite packaging bags prepared in the examples and comparative examples were cut into samples with a size of 100mm×100mm, and immersed in boiling water for 168 hours. After being taken out, the surface moisture was absorbed with filter paper, and the surface of the sample was observed for phenomena such as bubbles, delamination, and damage. The tensile strength and elongation at break of the sample before and after immersion were tested, and the performance retention rate was calculated. The performance retention rate was calculated by the formula R=P1 / P0×100%, where R is the performance retention rate (%), P1 is the performance value of the sample after immersion (tensile strength or elongation at break), and P0 is the performance value of the sample before immersion (tensile strength or elongation at break).

[0055] Performance test results: Table 1: Performance test results of each embodiment and comparative example As shown in Table 1, the highly waterproof composite packaging bags prepared in Examples 1-3 are significantly superior to those in Comparative Examples 1-3 in all aspects, effectively solving the technical problems of poor waterproofing, susceptibility to moisture, easy coating peeling, uneven filler dispersion, and complex processes in existing improved methods. Comparative Example 1, without the addition of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid and dynamically covalently modified polyether-acrylate block polymer, achieved a water vapor transmission rate as high as 12.5 g / (m²). 2The contact angle was only 95° (24h), indicating that the waterproof performance of the packaging bag was extremely poor, water molecules could easily penetrate it, and the surface hydrophobicity was insufficient. The tensile strength was 35MPa, the elongation at break was 420%, and the heat seal strength was 42 N / 15mm. Although the overall mechanical properties and heat seal performance could meet the basic requirements, they were prone to moisture absorption and performance degradation in high humidity environments. In the water resistance test, the retention rates of tensile strength and elongation at break were 85% and 83%, respectively, indicating that the material performance deteriorated significantly after long-term contact with water. Comparative Example 2 only added a perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid. Although the water vapor transmission rate was reduced to 8.9 g / (m²·24h) and the contact angle was increased to 110°, the waterproof performance was improved. However, due to the lack of synergistic effect of the dynamically covalently modified polyether-acrylate block polymer, its water vapor barrier effect was still not ideal. The retention rates of tensile strength and elongation at break were 90% and 88%, respectively, and the improvement in water resistance was limited. Moreover, if the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid is added in the form of a traditional coating, it is prone to peeling. Uneven dispersion of fillers will also affect the overall performance. Comparative Example 3 only added dynamically covalently modified polyether-acrylate block polymer. The water vapor transmission rate was 7.2 g / (m²·24h) and the contact angle was 105°, which improved the waterproof performance to a certain extent. However, the lack of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid resulted in insufficient surface hydrophobicity. The retention rates of tensile strength and elongation at break were 92% and 90%, respectively, and the improvement in water resistance was not significant. Furthermore, if the dynamically covalently modified polyether-acrylate block polymer is not dispersed uniformly or has poor compatibility with other components, it will affect the overall performance of the material. At the same time, the traditional filler dispersion process is complex and it is difficult to ensure uniformity. Examples 1-3, through the synergistic effect of perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrids and dynamically covalently modified polyether-acrylate block polymers, significantly improved the waterproof performance of the packaging bags. Example 1 had a water vapor transmission rate of 4.2 g / (m²·24h) and a contact angle of 128°; Example 2 had a water vapor transmission rate of 3.8 g / (m²·24h) and a contact angle of 132°; and Example 3 had a water vapor transmission rate of 3.5 g / (m²·24h). The g / (m²·24h) and contact angle of 135° indicate that the material surface has excellent hydrophobicity and can effectively prevent moisture penetration. The tensile strengths are 38MPa, 40MPa, and 42MPa, the elongation at break is 450%, 480%, and 500%, and the heat seal strengths are 45N / 15mm, 48N / 15mm, and 50N / 15mm, respectively, indicating good mechanical and heat seal performance. In the water resistance test, the retention rates of tensile strength and elongation at break both exceed 95%, indicating that the material has stable performance under long-term high humidity environment and is not easily affected by moisture aging.Furthermore, the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid and the dynamically covalently modified polyether-acrylate block polymer are uniformly dispersed in the polyethylene matrix through a blending process, avoiding the problems of easy coating peeling and uneven filler dispersion. Moreover, the preparation process is compatible with the conventional polyethylene packaging bag production process, without the need for complex additional processing steps. This solves the technical problem of complex processes in existing improved methods and achieves a balance between high waterproof performance and good processability.

[0056] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A highly waterproof composite packaging bag, characterized in that, Including the following parts by weight of raw materials: Low-density polyethylene: 750-900 parts by weight; High-density polyethylene: 50-150 parts by weight; Perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid: 20-60 parts by weight; Dynamically covalently modified polyether-acrylate block polymer: 10-40 parts by weight; Antioxidant: 1-3 parts by weight; Ultraviolet absorber: 0.5-1 parts by weight; The preparation method of the perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid includes: A1, mixing hexafluoropropylene with tetrahydrofuran, adding 1,4-bis(trifluoromethyl)phenyllithium under nitrogen protection, and reacting at -78°C to generate a perfluoroalkyl lithium intermediate; subsequently adding isophorone diisocyanate, and reacting at 25-30°C to form a perfluoroalkyl polyurethane prepolymer containing isocyanate groups; simultaneously reacting octaaminoPOSS with hydroxyethyl acrylate in N,N-dimethylformamide solvent to obtain an amino-terminated POSS-HEA derivative; A2, finally mixing the perfluoroalkyl polyurethane prepolymer, the POSS-HEA derivative, and dibutyltin dilaurate, reacting at 60-80°C, precipitating with acetone, washing, and vacuum drying.

2. The highly waterproof composite packaging bag according to claim 1, characterized in that, In step A1, the volume ratio of hexafluoropropylene to tetrahydrofuran is 1:2; the reaction time is 3-5 h at -78℃; the reaction time is 2-4 h at 25-30℃; the molar ratio of octaaminoPOSS to hydroxyethyl acrylate is 1:2, and the reaction time is 1-2 h in N,N-dimethylformamide solvent.

3. The highly waterproof composite packaging bag according to claim 1, characterized in that, In step A2, the reaction time is 6-10 hours at 60-80℃.

4. The highly waterproof composite packaging bag according to claim 1, characterized in that, The preparation method of the dynamically covalently modified polyether-acrylate block polymer includes: B1, adding polyethylene glycol and glycidyl methacrylate to toluene solvent, adding p-toluenesulfonic acid under nitrogen protection, and heating to 110-130℃ to react and generate epoxy-terminated polyether-acrylate prepolymer; simultaneously reacting boric acid and 3-aminopropyltriethoxysilane in ethanol solvent to obtain boric acid-modified silane coupling agent; B2, subsequently mixing the epoxy-terminated polyether-acrylate prepolymer, boric acid-modified silane coupling agent and photoinitiator, reacting at 50-70℃, and distilling under reduced pressure.

5. The highly waterproof composite packaging bag according to claim 4, characterized in that, In step B1, the molar ratio of polyethylene glycol to glycidyl methacrylate is 1:1; the reaction time is 4-6 hours at 110-130℃; the molar ratio of boric acid to 3-aminopropyltriethoxysilane is 1:2, and the reaction time is 2-3 hours in ethanol solvent.

6. The highly waterproof composite packaging bag according to claim 4, characterized in that, In step B2, the reaction time is 3-5 hours at 50-70℃.

7. A method for preparing a highly waterproof composite packaging bag according to any one of claims 1-6, characterized in that, step include: S1. Add low-density polyethylene, high-density polyethylene, perfluoroalkyl-polyurethane-polysilsesquioxane ternary hybrid, dynamically covalently modified polyether-acrylate block polymer, antioxidant and ultraviolet absorber to a high-speed mixer and stir at 50-60℃ until uniformly dispersed. S2. The mixture is then added to a single screw extruder, melted and plasticized, and extruded into a film through a T-die. After being shaped by cooling rollers, traction, corona treatment, and then wound up. S3. Finally, place the rolled-up film in an ultraviolet curing machine for irradiation.

8. The preparation method according to claim 7, characterized in that, In step S1, the stirring time is 10-15 minutes at 50-60℃.

9. The preparation method according to claim 7, characterized in that, In step S2, the barrel temperature of the single-screw extruder is 180-210℃, and the screw speed is 80-100rpm.

10. The preparation method according to claim 7, characterized in that, In step S3, the ultraviolet light wavelength of the UV curing machine is 365 nm, the intensity is 150-200 mW / cm², and the irradiation time is 8-12 min.

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