Octenyl succinic starch / polyvinyl alcohol-based antibacterial paper film and preparation method

Abstract

This invention discloses an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film and its preparation method, belonging to the technical field of food packaging materials. The preparation method provided by this invention involves preparing a composite substrate solution based on octenyl succinic acid starch and polyvinyl alcohol; preparing a nano-titanium dioxide dispersion based on nano-titanium dioxide and a dispersant solution; mixing the composite substrate solution, nano-titanium dioxide dispersion, and phytic acid according to a preset mass ratio; adding a surfactant and dispersing by stirring to prepare a composite coating solution; finally, coating the composite coating solution onto the surface of the original paper substrate, and drying to obtain the octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film. This invention achieves the preparation of a green and biodegradable antibacterial paper film through the synergistic integration of octenyl succinic acid starch, polyvinyl alcohol, nano-titanium dioxide, and phytic acid, simultaneously meeting the requirements of oil resistance, antibacterial properties, and green biodegradability.

Description

Technical Field

[0001] This invention relates to the field of food packaging materials technology, specifically to an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film and its preparation method. Background Technology

[0002] With the rapid development of the food industry, consumers are increasingly concerned about food safety and environmental protection, prompting food packaging materials to simultaneously meet stringent requirements for functional integration and green biodegradability. Currently, traditional food packaging paper relies mainly on fluorinated oil-repellent agents or plastic coating technology to achieve its oil-repellent function. However, fluorinated oil-repellent agents and plastic coating materials have significant drawbacks. These materials are difficult to biodegrade in the natural environment, and long-term accumulation can place a serious burden on the ecological environment. More importantly, they pose a potential risk of the migration of harmful substances during use, which may seep into food and pose a potential threat to consumers' health.

[0003] Meanwhile, food is highly susceptible to microbial contamination during storage and transportation. The growth of microorganisms accelerates food spoilage, affecting not only its quality and taste but also causing significant economic losses. Therefore, endowing food packaging materials with antibacterial properties to effectively inhibit microbial growth and reproduction is of paramount practical significance for extending food shelf life and ensuring food safety.

[0004] However, existing food packaging material technologies struggle to simultaneously meet the requirements of oil resistance, antibacterial properties, and green biodegradability. How to achieve green biodegradability of packaging materials while ensuring good oil resistance and antibacterial properties has become a technical challenge that urgently needs to be overcome by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film and its preparation method, so as to overcome the problem that existing food packaging material technologies cannot simultaneously meet the requirements of oil resistance, antibacterial properties, and green biodegradability.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film, comprising the following steps: Octenyl succinic acid starch and polyvinyl alcohol were mixed in water to obtain a mixed suspension; the mixed suspension was heated and stirred to obtain a composite substrate solution. Nano-titanium dioxide was added to the dispersant solution and dispersed by stirring to obtain a nano-titanium dioxide dispersion. The composite substrate solution, nano titanium dioxide dispersion and phytic acid are mixed in a preset mass ratio, a surfactant is added, and the mixture is dispersed by a second stirring to prepare a composite coating solution. The composite coating liquid is applied to the surface of the base paper substrate, and after drying, an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film is obtained.

[0007] A further improvement of the present invention is that the degree of substitution of octenyl succinic acid starch is 0.01~0.05; the mass ratio of octenyl succinic acid starch to polyvinyl alcohol is 1:(0.05~0.3); and the mass concentration of the mixed suspension is 5%~12%.

[0008] A further improvement of the present invention is that the heating and stirring temperature is 70~95 ℃, the heating and stirring speed is 300~1500 rpm, and the heating and stirring time is 30~60 minutes.

[0009] A further improvement of this invention is that the dispersant solution is a sodium polyacrylate solution, wherein the molecular weight of the sodium polyacrylate in the sodium polyacrylate solution is 5000~8000 g·mol⁻¹. - ¹, The mass concentration of the sodium polyacrylate solution is 0.5~2%.

[0010] A further improvement of this invention is that the particle size of the nano-titanium dioxide is 10~50 nm.

[0011] A further improvement of the present invention is that the preset mass ratio is 1:(0.05~0.2):(0.005~0.05).

[0012] A further improvement of the present invention is that the surfactant is sophorolipid, and the mass of sophorolipid is 0.03~0.05% of the mass of octenyl succinic acid starch.

[0013] A further improvement of the present invention is that the stirring speed of the first stirring and dispersion is 500~1000 rpm and the stirring time of the first stirring and dispersion is 30~60 minutes; the stirring speed of the second stirring and dispersion is 500~1500 rpm and the stirring time of the second stirring and dispersion is 20~40 minutes.

[0014] A further improvement of the present invention is that the coating amount of the composite coating liquid applied to the surface of the base paper substrate is 5~25g / m²; the drying temperature is 50~80℃; and the drying time is 10~30 min.

[0015] The present invention also provides an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film, which is prepared by the above-described method for preparing octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film.

[0016] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The present invention provides a method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film. The method utilizes the hydrophobicity of octenyl succinic acid starch to provide an oil-resistant base, while the film-forming properties and mechanical strength of polyvinyl alcohol enhance structural stability, avoiding the defects of pure starch films. Heating and stirring promote the formation of hydrogen bonds between the two molecules, ensuring solution uniformity and processability. A dispersant prevents nanoparticle aggregation, ensuring uniform distribution of nano-titanium dioxide in subsequent coating processes, maximizing its antibacterial and UV-shielding functions. A composite substrate solution, nano-titanium dioxide dispersion, and phytic acid are mixed in a predetermined mass ratio, and a surfactant is added. The mixture is then stirred and dispersed to form a composite coating solution. The multidentate coordination of phytic acid enhances film density through cross-linking, while the surfactant improves the wettability and dispersibility of the coating solution. The predetermined ratio optimizes the synergistic effect of each component, achieving a balance between oil resistance, antibacterial properties, and biodegradability. Finally, the composite coating solution is coated onto the surface of the original paper substrate, and after drying, an antibacterial paper film is obtained. The coating and drying processes form a functional layer, ensuring that the paper film maintains its green and biodegradable characteristics while possessing oil resistance and antibacterial properties. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a schematic diagram of the preparation method of the octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This is an explanation of the present invention and not a limitation thereof.

[0023] See Figure 1 This invention provides a method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film, comprising the following steps: Octenyl succinic acid starch and polyvinyl alcohol were mixed in water to obtain a mixed suspension; the mixed suspension was heated and stirred to obtain a composite substrate solution. Nano-titanium dioxide was added to the dispersant solution and dispersed by stirring to obtain a nano-titanium dioxide dispersion. The composite substrate solution, nano titanium dioxide dispersion and phytic acid are mixed in a preset mass ratio, a surfactant is added, and the mixture is dispersed by a second stirring to prepare a composite coating solution. The composite coating liquid is applied to the surface of the base paper substrate, and after drying, an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film is obtained.

[0024] Octenyl succinate starch (OSA starch) is a modified starch introduced through esterification, resulting in hydrophobic groups. It possesses an amphiphilic structure and combines film-forming and emulsifying properties, making it a starch derivative suitable for use as an emulsifier in the food industry. Polyvinyl alcohol (PVA), a water-soluble semi-crystalline synthetic polymer, exhibits excellent film-forming properties, oxygen barrier properties, and a certain degree of biodegradability. The numerous hydroxyl groups on its molecular chain can form an intermolecular hydrogen bond network with starch, effectively compensating for the insufficient mechanical properties of pure starch films. Phytic acid (PA, inositol hexaphosphate) is a naturally occurring phosphorus-containing organic acid widely found in plant seeds. Its molecular structure contains six phosphate groups, endowing it with extremely strong metal ion chelating ability and antioxidant activity. Phytic acid can also serve as a green, multifunctional crosslinking agent, enhancing the structural density of polysaccharide-based films through multidentate coordination and hydrogen bonding, and synergistically endowing the material with dual functions of resisting lipid oxidation and inhibiting microbial proliferation. Nano-titanium dioxide (TiO2) generates reactive oxygen species (ROS) under UV-Vis light excitation, achieving highly efficient killing of foodborne pathogens. Simultaneously, nano-TiO2 possesses excellent UV shielding properties and a nano-size effect, making it a functional filler that can further optimize the barrier properties and mechanical strength of composite membranes. Phytic acid (PA), a naturally occurring organic acid widely found in plant seeds, has strong chelating ability and antioxidant activity. It can be used as a green crosslinking agent to enhance membrane structural density and impart antibacterial properties to the material. Nano-titanium dioxide (TiO2) generates reactive oxygen species under UV irradiation, achieving photocatalytic antibacterial effects, while also possessing excellent UV shielding capabilities and nano-filler reinforcement.

[0025] The preparation method provided by this invention, by synergistically integrating octenyl succinic starch, polyvinyl alcohol, nano titanium dioxide and phytic acid, provides a green and biodegradable antibacterial paper film solution, which can effectively solve the shortcomings of traditional materials in terms of oil resistance, antibacterial properties and biodegradability. Specifically, octenyl succinic acid starch and polyvinyl alcohol are mixed in water to obtain a mixed suspension. The hydrophobicity of octenyl succinic acid starch provides an oil-resistant base, while the film-forming properties and mechanical strength of polyvinyl alcohol enhance structural stability and avoid the defects of pure starch films. Next, the mixed suspension is heated and stirred to obtain a composite substrate solution. Heating and stirring promote the formation of hydrogen bonds between the two molecules, ensuring the uniformity and processability of the solution. Nano-titanium dioxide is added to a dispersant solution and dispersed by a first stirring to obtain a nano-titanium dioxide dispersion. The dispersant prevents the agglomeration of nanoparticles, ensuring that the nano-titanium dioxide is evenly distributed in subsequent coatings and exerts its antibacterial and ultraviolet shielding functions. The composite substrate solution, nano-titanium dioxide dispersion, and phytic acid are mixed in a preset mass ratio, and a surfactant is added. After a second stirring and dispersion, a composite coating solution is prepared. The multidentate coordination of phytic acid enhances the cross-linking and density of the film, while the surfactant improves the wettability and dispersibility of the coating solution. The preset ratio optimizes the synergistic effect of each component, achieving a balance between oil resistance, antibacterial properties, and biodegradability. Finally, the composite coating liquid is applied to the surface of the original paper substrate, and after drying, an antibacterial paper film is obtained. The coating and drying process forms a functional layer, ensuring that the paper film maintains green and biodegradable characteristics while possessing oil-proof and antibacterial properties.

[0026] Preferably, the degree of substitution of octenyl succinic acid starch is 0.01~0.05; the mass ratio of octenyl succinic acid starch to polyvinyl alcohol is 1:(0.05~0.3); and the mass concentration of the mixed suspension is 5%~12%.

[0027] By specifically defining the degree of substitution of octenyl succinic acid starch, its mass ratio to polyvinyl alcohol, and the mass concentration of the mixed suspension, the preparation process of the composite substrate was optimized, thereby solving the problems of film-forming performance and functionality. Specifically, the degree of substitution of octenyl succinic acid starch is in the range of 0.01 to 0.05, ensuring that the starch molecules have appropriate hydrophobic groups, which is conducive to the formation of a stable emulsion structure and oil-repellent properties, while maintaining biodegradability, avoiding insufficient hydrophobicity due to excessively low substitution or environmentally unfriendly effects due to excessively high substitution; the mass ratio of octenyl succinic acid starch to polyvinyl alcohol is 1:0.05 to 1:0.3, balancing the film-forming properties of starch and the mechanical reinforcing effect of polyvinyl alcohol. The hydroxyl groups of polyvinyl alcohol form a hydrogen bond network with starch, improving the film strength and oxygen barrier properties, avoiding insufficient film strength or reduced processability due to an imbalance in the ratio; the mass concentration of the mixed suspension is 5% to 12%, ensuring that the suspension is easy to stir and coat, forming a uniform and dense film layer after drying, avoiding uneven coating and reduced drying efficiency due to excessively low concentration or excessively high concentration.

[0028] Preferably, the heating and stirring temperature is 70~95 ℃, the stirring speed is 300~1500 rpm, and the heating and stirring time is 30~60 minutes.

[0029] By limiting the specific parameters of heating and stirring, the problems of insufficient dissolution and low efficiency are effectively solved, ensuring the uniformity and stability of the composite substrate solution. Specifically, the heating and stirring temperature is set within the range of 70~95℃ to ensure that octenyl succinic acid starch and polyvinyl alcohol can be fully dissolved in water, while avoiding thermal degradation caused by high temperature or insufficient dissolution caused by low temperature; the stirring speed is controlled at 300~1500 rpm to provide sufficient shear force to uniformly disperse the components, prevent agglomeration or precipitation, and improve the overall homogeneity of the solution; the time is limited to 30~60 minutes to ensure that the reaction proceeds completely, avoiding both insufficient dissolution due to too short a time and unnecessary energy consumption due to too long a time, thereby optimizing the efficiency and quality of the entire preparation process.

[0030] Preferably, the dispersant solution is a sodium polyacrylate solution, wherein the molecular weight of the sodium polyacrylate in the sodium polyacrylate solution is 5000~8000 g·mol⁻¹. - ¹, The mass concentration of the sodium polyacrylate solution is 0.5~2%.

[0031] By limiting the specific type and parameter range of the dispersant solution, the problem of uneven dispersion of nano-titanium dioxide was solved. Specifically, sodium polyacrylate solution was chosen as the dispersant because its molecular structure can effectively adsorb onto the surface of nano-titanium dioxide, forming a stable dispersion system and preventing particle agglomeration; the molecular weight was controlled within the range of 5000~8000 g·mol⁻¹. - Within the specified range, the chain length and adsorption capacity of the dispersant were optimized. Too low a molecular weight might result in insufficient dispersion and inadequate particle coating, while too high a molecular weight could increase solution viscosity and affect subsequent mixing. The mass concentration was set at 0.5–2% to ensure sufficient dispersant molecules cover the nanoparticle surface to maintain dispersion stability, while avoiding excessive concentration that could waste resources or interfere with the compatibility of other components. These characteristics work synergistically to ensure the uniformity and stability of the nano-titanium dioxide dispersion, thereby improving the overall performance of the antibacterial paper film.

[0032] Preferably, the particle size of nano-titanium dioxide is 10~50 nm.

[0033] By limiting the particle size range of nano-titanium dioxide, the potential problems of uneven dispersion and performance defects in the preparation of composite coating solutions are solved. Specifically, the particle size of nano-titanium dioxide is controlled between 10 and 50 nm to ensure that the nanoparticles have appropriate specific surface area and size effect during dispersion, avoiding reduced antibacterial activity due to excessively large particle size or aggregation caused by excessively small particle size. This helps the nano-titanium dioxide to be uniformly distributed in the composite coating solution, effectively exerting its photocatalytic antibacterial effect, while also serving as a functional filler to optimize the ultraviolet shielding ability and mechanical strength of the composite film.

[0034] Preferably, the preset mass ratio is 1:(0.05~0.2):(0.005~0.05).

[0035] By setting preset mass ratios and optimizing the mixing proportions of the composite substrate solution, nano-titanium dioxide dispersion, and phytic acid, the synergistic integration of each component can be promoted, improving the overall uniformity and functionality of the composite coating solution. Specifically, the composite substrate solution is set to a baseline amount of 1 to ensure the dominant role of the film-forming substrate; the relative amount of the nano-titanium dioxide dispersion is controlled between 0.05 and 0.2 to provide an appropriate amount of antibacterial agent for uniform dispersion and to exert a photocatalytic antibacterial effect, avoiding excessive amounts that could lead to agglomeration or a decrease in membrane mechanical properties; the relative amount of phytic acid is controlled between 0.005 and 0.05 to achieve effective cross-linking, enhancing the membrane structure density and antibacterial synergy, while preventing excessive amounts from affecting the stability or biodegradability of the coating solution.

[0036] Preferably, the surfactant is sophorolipid, and the mass of sophorolipid is 0.03~0.05% of the mass of octenyl succinic acid starch.

[0037] By limiting the specific type and proportion of surfactants, the environmental and performance issues that may arise from inappropriate surfactant selection are resolved. Specifically, sophorolipids, a natural and biodegradable substance, replace traditional synthetic surfactants, avoiding the risk of harmful substance migration and enhancing the dispersion uniformity of the composite coating solution. The mass of sophorolipids is controlled within the range of 0.03~0.05% of the mass of octenyl succinic acid starch. This optimized proportion effectively reduces surface tension, promotes the uniform mixing of nano-titanium dioxide and phytic acid, without affecting the film-forming properties and antibacterial activity of the composite coating solution, thus ensuring the overall green biodegradability and functional stability of the paper film.

[0038] Preferably, the stirring speed of the first stirring and dispersion is 500~1000 rpm, and the stirring time of the first stirring and dispersion is 30~60 minutes; the stirring speed of the second stirring and dispersion is 500~1500 rpm, and the stirring time of the second stirring and dispersion is 20~40 minutes.

[0039] By limiting the specific speed and time range of stirring and dispersion, it is possible to ensure that nano-titanium dioxide and composite components are uniformly distributed throughout the preparation process, thereby improving the performance of the antibacterial paper film. Specifically, the stirring speed is set to provide appropriate shear force, which can effectively disperse nanoparticles to prevent agglomeration, while avoiding excessive speed that could damage the material structure; the stirring time is set to ensure sufficient time for the components to mix thoroughly and disperse stably, avoiding localized unevenness caused by insufficient time.

[0040] Preferably, the coating amount of the composite coating liquid applied to the surface of the base paper substrate is 5~25 g / m²; the drying temperature is 50~80 ℃, and the drying time is 10~30 min.

[0041] By limiting the specific range of coating amount and drying parameters, the uniformity and structural integrity of the antibacterial paper film can be ensured. Specifically, the coating amount of the composite coating liquid applied to the surface of the base paper substrate is 5~25 g / m². By controlling this coating amount range, the coating thickness is ensured to be moderate, providing sufficient coverage to enhance antibacterial and oil-resistant functions while avoiding material waste or insufficient protection due to an excessively thin film. The drying temperature is 50~80 ℃. Setting this temperature range ensures a gentle and efficient drying process, effectively evaporating moisture without damaging the active ingredients of octenyl succinic acid starch, polyvinyl alcohol, and nano-titanium dioxide, thereby maintaining the antibacterial properties and mechanical strength of the film. The drying time is 10~30 min. Limiting this time range ensures that the coating liquid is fully dried and cured to form a dense film structure, preventing residual moisture from affecting the stability and biodegradability of the paper film, while also optimizing the production process.

[0042] Based on the same inventive concept, the present invention also provides an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film, which is prepared by the above-described method for preparing octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film.

[0043] The composition and process control in the preparation method provided by this invention directly determine the structure and function of the membrane. The paper membrane prepared using this method effectively integrates oil-repellent, antibacterial, and biodegradable properties. Specifically, the preparation method enables the paper membrane to form a stable composite structure based on a mixture of octenyl succinic acid starch and polyvinyl alcohol, combined with additives such as nano-titanium dioxide and phytic acid. This helps to establish a uniformly dispersed hydrophobic network and antibacterial active sites in the membrane, thereby synergistically improving oil-repellent and antibacterial effects. At the same time, the biodegradable properties of polyvinyl alcohol ensure that the material as a whole meets green and environmentally friendly requirements. This not only solves the problem of difficulty in achieving multiple functions in the prior art, but also avoids product performance fluctuations caused by arbitrary preparation processes.

[0044] In a specific embodiment of the present invention, a method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film specifically includes the following steps: Step 1: Preparation of OSA starch / PVA composite substrate solution: Octenyl succinic acid starch (OSA starch) and polyvinyl alcohol (PVA) are mixed at a mass ratio of 1:(0.05~0.3), and water is added to prepare a mixed suspension with a mass concentration of 5~12%. The suspension is heated and stirred at 70~95℃ for 30-60 minutes to fully gelatinize the OSA starch and completely dissolve the PVA, resulting in a homogeneous composite substrate solution.

[0045] Step 2, Preparation of TiO2 Dispersion: Add nano-titanium dioxide to PAAS (molecular weight 5000~8000 g·mol⁻¹) at a mass concentration of 0.5%~2%. - ¹) In an aqueous solution, the TiO2 is dispersed under stirring at 500-1000 r / min for 30-60 min to obtain a highly stable TiO2 dispersion with a solid content of 30%-50% and a viscosity of less than 50 mPa·s. The particle size of the nano-titanium dioxide is 10-50 nm.

[0046] Step 3: Preparation of composite coating solution: Mix the composite substrate solution from Step 1, the TiO2 dispersion from Step 2, and phytic acid at a mass ratio of 1:(0.05~0.2):(0.005~0.05), then add the surfactant sophorolipid at a dosage of 0.03%~0.05% (for OSA starch), and stir at 500~1500 r / min for 20~40 min to ensure that all components are fully and uniformly dispersed, thus obtaining the composite coating solution; Step 4, Coating and Film Formation: Coat the composite coating solution from Step 3 onto the surface of the base paper substrate with a coating amount of 5-25 g / m², and dry at 50-80℃ for 10-30 min to obtain an octenyl succinic acid starch / polyvinyl alcohol antibacterial paper film.

[0047] The preparation method provided by this invention combines octenyl succinic acid starch (OSA starch), polyvinyl alcohol (PVA), phytic acid (PA), and nano-titanium dioxide (TiO2). Through interface engineering strategies, a four-fold synergistic structure is constructed, consisting of a hydrophobic OSA starch layer, a PVA-reinforced framework, a phytic acid crosslinking network, and a TiO2 nanofiller. This overturns the traditional understanding of the single function of each component, achieving four uses for TiO2 (Pickering emulsion stabilizer, photocatalytic antibacterial agent, nanofiller, and UV shielding agent) and four uses for phytic acid (TiO2 dispersant, green crosslinking agent, chelating antibacterial agent, and antioxidant). This is achieved through phytic acid-phosphoric acid synthesis. The ligand exchange between the group and the hydroxyl group on the TiO2 surface forms a stable inner complex, solving the industry problem of easy aggregation of nano-TiO2. At the same time, the uncoordinated phosphate group forms a hydrogen bond cross-linking network with OSA starch and PVA. On this basis, the photocatalytic antibacterial effect of TiO2 and the chelate antibacterial effect of phytic acid form a dual synergistic mechanism. The octenyl hydrophobic chain of OSA starch and the nano-filling effect of TiO2 form a multi-barrier network. Finally, a comprehensive performance breakthrough is achieved with an oil resistance level of 11-12, an antibacterial rate of 99%, a tensile strength of 73MPa, and a UV blocking rate of over 98%, providing a green solution integrating structure and function for the food packaging paper film industry.

[0048] The octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film prepared by the above method can be applied to antibacterial properties, oil-repellent properties, hydrophobic properties, air permeability and antioxidant properties. It can be used in high-oil food packaging (fried food, baked food, Chinese pastries, etc.), fresh food preservation packaging (berries, fresh-cut fruits and vegetables, ready-to-eat food, etc.), dry food packaging (nuts and roasted seeds, condiments, candy and chocolate, etc.), smart responsive packaging, active food packaging, multifunctional composite packaging and other emerging packaging fields.

[0049] Example 1 A method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film includes the following steps: Step 1: Preparation of OSA starch / PVA composite substrate solution: Octenyl succinic acid starch (OSA starch) and polyvinyl alcohol (PVA) are mixed at a mass ratio of 1:0.05, and water is added to prepare a mixed suspension with a mass concentration of 5%. The suspension is heated and stirred at 70°C for 30 minutes to fully gelatinize the OSA starch and completely dissolve the PVA, resulting in a uniform composite substrate solution.

[0050] Step 2, Preparation of TiO2 Dispersion: Nano-titanium dioxide was added to 0.5% PAAS (molecular weight 5000 g·mol⁻¹). -¹) In an aqueous solution, the nano-titanium dioxide is dispersed under stirring at 500 r / min for 60 min to obtain a highly stable TiO2 dispersion with a solid content of up to 30% and a viscosity of less than 50 mPa·s. The particle size of the nano-titanium dioxide is 10-50 nm.

[0051] Step 3: Preparation of composite coating solution: Mix the composite substrate solution from Step 1, the TiO2 dispersion from Step 2, and phytic acid at a mass ratio of 1:0.05:0.005, then add the surfactant sophorolipid at a dosage of 0.03% (for OSA starch); stir at 500 r / min for 40 min to ensure that all components are fully and uniformly dispersed, thus obtaining the composite coating solution. Step 4, Coating and Film Formation: Coat the composite coating solution from Step 3 onto the surface of the base paper substrate with a coating amount of 5 g / m², and dry at 50°C for 30 min to obtain an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial food paper film.

[0052] The static water contact angle of the coating was measured to be 93°±3°, and the resistance level to vegetable oil (olive oil) reached level 11 (TAPPI T559 standard); the antibacterial rate of Escherichia coli and Staphylococcus aureus was greater than 99.3%, the tensile strength was 73MPa, and the UV blocking was 98%.

[0053] Example 2 A method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film includes the following steps: Step 1: Preparation of OSA starch / PVA composite substrate solution: Octenyl succinic acid starch (OSA starch) and polyvinyl alcohol (PVA) are mixed at a mass ratio of 1:0.3, and water is added to prepare a mixed suspension with a mass concentration of 12%. The suspension is heated and stirred at 95°C for 30 minutes to fully gelatinize the OSA starch and completely dissolve the PVA, resulting in a uniform composite substrate solution.

[0054] Step 2, Preparation of TiO2 Dispersion: Add nano-titanium dioxide to 2% PAAS (molecular weight 8000 g·mol⁻¹). - ¹) In an aqueous solution, the nano-titanium dioxide is dispersed under stirring at 1000 r / min for 30 min to obtain a highly stable TiO2 dispersion with a solid content of up to 50% and a viscosity of less than 50 mPa·s. The particle size of the nano-titanium dioxide is 10-50 nm.

[0055] Step 3: Preparation of composite coating solution: Mix the composite substrate solution from Step 1, the TiO2 dispersion from Step 2, and phytic acid at a mass ratio of 1:0.2:0.05, then add the surfactant sophorolipid at a dosage of 0.05% (for OSA starch); stir at 1500 r / min for 20 min to ensure that all components are fully and uniformly dispersed, thus obtaining the composite coating solution; Step 4, Coating and Film Formation: Coat the composite coating solution from Step 3 onto the surface of the base paper substrate with a coating amount of 25 g / m², and dry at 80°C for 10 min to obtain an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial food paper film.

[0056] The static water contact angle of the paper film was measured to be 94°±3°, and its resistance to vegetable oil (olive oil) reached level 11 (TAPPI T559 standard); the antibacterial rate of Escherichia coli and Staphylococcus aureus was greater than 99.5%, the tensile strength was 75MPa, and the UV blocking was 98%.

[0057] Example 3 A method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film includes the following steps: Step 1: Preparation of OSA starch / PVA composite substrate solution: Octenyl succinic acid starch (OSA starch) and polyvinyl alcohol (PVA) are mixed at a mass ratio of 1:0.15. Water is added to prepare a mixed suspension with a mass concentration of 8%. The suspension is heated and stirred at 80°C for 45 minutes to fully gelatinize the OSA starch and completely dissolve the PVA, resulting in a uniform composite substrate solution.

[0058] Step 2, Preparation of TiO2 Dispersion: Add nano-titanium dioxide to PAAS (molecular weight 6500 g·mol⁻¹) at a mass concentration of 0.5%~2%. - ¹) In an aqueous solution, the nano-titanium dioxide is dispersed under stirring at 800 r / min for 40 min to obtain a highly stable TiO2 dispersion with a solid content of up to 40% and a viscosity of less than 50 mPa·s. The particle size of the nano-titanium dioxide is 10-50 nm.

[0059] Step 3: Preparation of composite coating solution: Mix the composite substrate solution from Step 1, the TiO2 dispersion from Step 2, and phytic acid at a mass ratio of 1:0.1:0.02, then add the surfactant sophorolipid at a dosage of 0.04% (for OSA starch); stir at 700 r / min for 30 min to ensure that all components are fully and uniformly dispersed, thus obtaining the composite coating solution. Step 4, Coating and Film Formation: The composite coating solution from Step 3 is coated onto the surface of the original paper substrate at a coating amount of 15 g / m², and dried at 60°C for 20 min to obtain an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial food paper film.

[0060] The static water contact angle of the paper film was measured to be 96°±2°, and its resistance to vegetable oil (olive oil) reached level 11 (TAPPI T559 standard); the antibacterial rate of Escherichia coli and Staphylococcus aureus was greater than 99.9%, the tensile strength was 79MPa, and the UV blocking was 98%.

[0061] The only difference between Examples 4 and 5 and Example 2 is the mass ratio of OSA / PVA, PA, and TiO2. Therefore, they will not be described in detail. Please refer to Table 1 for a summary of the parameters and results of each example.

[0062] Table 1 Summary of parameters and results for each embodiment

[0063] In summary, the method of this invention has a high degree of process integration and is environmentally friendly, realizing the direct conversion from low-cost raw materials to high-performance products. The resulting octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film has excellent hydrophobic, oil-resistant and antibacterial properties.

[0064] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of this invention. Their purpose is to clearly illustrate the concept, principle, and application of this invention through specific examples, and is by no means intended to limit the scope of protection of this invention to these specific embodiments. In fact, the true value of this invention lies in its proposed technical ideas and innovations, rather than its manifestations or implementation methods.

[0065] For those skilled in the art, after thoroughly reading and understanding the technical solution of this invention, they are fully capable of making various changes, modifications, or equivalent substitutions to the specific implementation of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the range of technical parameters, optimizing the algorithm flow to improve efficiency, and replacing some technical components to achieve better compatibility or reduce costs. As long as these modified technical solutions substantially retain the technical features claimed by the original invention, that is, they can still achieve the core functions and effects of this invention, then these changes should be considered to fall within the scope of protection of the pending claims of this invention.

[0066] Furthermore, with the continuous progress and development of technology, new technical means and methods are constantly emerging, which provides ample space for further improvement and perfection of this invention. Therefore, the scope of protection of this invention should also include reasonable and foresightful improvements and extensions based on existing technology. As long as these improvements and extensions do not depart from the basic principles and core concepts of this invention, they should be considered equivalents of this invention and are equally protected by patent rights.

Claims

1. A method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film, characterized in that, Includes the following steps: Octenyl succinic acid starch and polyvinyl alcohol were mixed in water to obtain a mixed suspension; The mixed suspension is heated and stirred to obtain a composite substrate solution; Nano-titanium dioxide was added to the dispersant solution and dispersed by stirring to obtain a nano-titanium dioxide dispersion. The composite substrate solution, nano titanium dioxide dispersion and phytic acid are mixed in a preset mass ratio, a surfactant is added, and the mixture is dispersed by a second stirring to prepare a composite coating solution. The composite coating liquid is applied to the surface of the base paper substrate, and after drying, an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film is obtained.

2. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The degree of substitution of octenyl succinic acid starch is 0.01~0.05; the mass ratio of octenyl succinic acid starch to polyvinyl alcohol is 1:(0.05~0.3); and the mass concentration of the mixed suspension is 5%~12%.

3. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The heating and stirring temperature is 70~95 ℃, the stirring speed is 300~1500 rpm, and the heating and stirring time is 30~60 minutes.

4. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The dispersant solution is a sodium polyacrylate solution, and the molecular weight of the sodium polyacrylate in the sodium polyacrylate solution is 5000~8000 g·mol⁻¹. - ¹, The mass concentration of the sodium polyacrylate solution is 0.5~2%.

5. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The particle size of nano-titanium dioxide is 10~50 nm.

6. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The preset mass ratio is 1:(0.05~0.2):(0.005~0.05).

7. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The surfactant is sophorolipid, and the mass of sophorolipid is 0.03~0.05% of the mass of octenyl succinic acid starch.

8. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The stirring speed for the first dispersion is 500~1000 rpm, and the stirring time for the first dispersion is 30~60 minutes; the stirring speed for the second dispersion is 500~1500 rpm, and the stirring time for the second dispersion is 20~40 minutes.

9. The method for preparing an octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film according to claim 1, characterized in that, The coating amount of the composite coating liquid applied to the surface of the base paper substrate is 5~25 g / m²; the drying temperature is 50~80 ℃, and the drying time is 10~30 min.

10. An octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film, characterized in that, It was prepared using the method described in any one of claims 1 to 9 for preparing octenyl succinic acid starch / polyvinyl alcohol-based antibacterial paper film.

Images