Moisture-absorbing and moisture-proof composite film

Abstract

The invention discloses a moisture-absorbing and moisture-proof composite film, and relates to the technical field of film materials, the moisture-absorbing and moisture-proof composite film comprises an inner layer, a middle layer and an outer layer, the inner layer is a moisture-absorbing layer, the middle layer is a moisture-proof layer, and the outer layer is a protective layer; the moisture-absorbing and moisture-proof composite film further comprises the following additives, wherein the additives comprise photocatalytic nanoparticles; a negative ion releasing agent; a high strength bio-based polymer; a self-repairing polymer; and the natural antioxidant is encapsulated by microcapsules. According to the moisture-absorbing and moisture-proof composite film, innovative materials such as the high-strength bio-based polymer, the negative ion releasing agent, the self-repairing polymer and the natural antioxidant microcapsules are adopted, and the comprehensive performance of the film is enhanced. Not only is excellent moisture absorption and moisture prevention functions achieved, but also the air purification and antibacterial performance is improved by adding the negative ion releasing agent; the self-repairing polymer can automatically repair cracks when the surface of the film is damaged, so that the service life is prolonged; the microcapsules of natural antioxidants can effectively resist oxidation and ensure that the membrane material keeps excellent performance for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of membrane materials, in particular to a moisture-absorbing and moisture-proof composite membrane. Background Art

[0002] As people pay more and more attention to environmental protection and sustainable development, composite film materials with good moisture absorption and moisture-proof properties have been widely used in packaging, construction, electronics and other fields. However, existing moisture absorption and moisture-proof film materials usually have some shortcomings, which are mainly reflected in the following aspects: Poor durability: Existing hygroscopic and moisture-proof films mostly use traditional synthetic polymers and simple negative ion releasers. Although they have certain moisture-proof properties, they are prone to degradation of material performance and even aging and embrittlement during long-term use due to external factors such as ultraviolet radiation, temperature and humidity changes.

[0003] Insufficient antioxidant performance: Many traditional membrane materials are prone to discoloration or loss of original physical properties when exposed to oxidation in the air for a long time, resulting in a shortened service life of the membrane.

[0004] Poor environmental friendliness: Most of the existing moisture-absorbing and moisture-proof films use raw materials that mainly rely on petrochemical products. The production process of these materials involves high energy consumption and environmental pollution, and they are difficult to biodegrade, resulting in waste of resources and environmental burden.

[0005] Therefore, there is an urgent need to develop a new type of hygroscopic and moisture-proof composite membrane material that can overcome these deficiencies in the existing technology and improve the comprehensive performance of the membrane, including durability, antioxidant properties and environmental friendliness. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a moisture-absorbing and moisture-proof composite film to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: The embodiment of the present invention provides a moisture-absorbing and moisture-proof composite film, comprising an inner layer, an intermediate layer and an outer layer, wherein the inner layer is a moisture-absorbing layer, the intermediate layer is a moisture-proof layer, and the outer layer is a protective layer; The inner layer comprises polyvinyl alcohol, polyacrylic acid, hygroscopic nanoparticles and water; the inner layer is used for hygroscopicity, quickly absorbing and locking moisture, and provides water absorption and film-forming properties through the combination of polyvinyl alcohol and polyacrylic acid. The hygroscopic nanoparticles improve the overall water absorption efficiency of the film and enhance the uniformity of the film. The intermediate layer comprises polyurethane, fluorinated polymer, graphene and waterproof coating; the intermediate layer is used for moisture-proofing, polyurethane provides strength and elasticity, fluorinated polymer enhances the waterproof performance of the membrane, graphene improves the overall stability and thermal conductivity of the membrane, and the waterproof coating effectively prevents moisture penetration; The outer layer comprises polyester, nanosilver and super-hydrophobic coating, which are used to provide durability and anti-pollution properties. Polyester increases the strength and durability of the membrane, nanosilver has antibacterial effects, and the super-hydrophobic coating makes the membrane surface more waterproof and anti-fouling, reducing the impact of external moisture on the membrane. The moisture-absorbing and moisture-proof composite film also includes the following additives, which include: Photocatalytic nanoparticles; Negative ion releaser; High-strength bio-based polymers; Self-healing polymers; Microencapsulated natural antioxidants.

[0008] To further optimize the technical solution, the mass fractions of the components in the inner layer, the middle layer and the outer layer are as follows: Polyvinyl alcohol is 25-30 parts; Polyacrylic acid is 5-10 parts; 10-15 parts of hygroscopic nanoparticles; Water is 30-35 parts; Polyurethane is 25-30 parts; 5-10 parts of fluorinated polymer; Graphene is 3-5 parts; Waterproof coating is 2-4 parts; Polyester is 40-45 parts; Nano silver is 0.5-1 part; Super hydrophobic coating is 2-4 parts.

[0009] To further optimize the technical solution, the mass fractions of the additives are as follows: Photocatalytic nanoparticles are 0.5-1 part; The negative ion release agent is 0.5-1.5 parts; High-strength bio-based polymer is 1-2 parts; 1.5-2.5 parts of self-healing polymer; The natural antioxidants encapsulated in microcapsules are 0.5-1.5 parts; The high-strength bio-based polymer is added in the inner layer; the photocatalytic nanoparticles and self-repairing polymer are added in the middle layer; and the negative ion releaser and microcapsulated natural antioxidants are added in the outer layer.

[0010] To further optimize the technical solution, the photocatalytic nanoparticles are titanium dioxide. Under ultraviolet irradiation, titanium dioxide decomposes organic pollutants in the air; the photolysis reaction formula is as follows: ; In the formula, the organic pollutant benzyl methane is decomposed into carbon dioxide and water under the catalytic action of titanium dioxide, purifying the air; ultraviolet light UV is the driving factor in the reaction and is used to enhance the efficiency of photocatalysis.

[0011] To further optimize the technical solution, the self-repairing polymer contains microcapsules, and the microcapsules contain a repair agent of a carboxyl monomer; when the composite film is damaged, the repair agent is released from the microcapsules and undergoes a polymerization reaction to repair the cracks; the repair reaction formula is as follows: ; In the formula, the carboxyl monomer reacts with water to polymerize into longer chain molecules, thereby filling and repairing the cracks in the membrane. The reaction occurs automatically when the membrane is damaged, and is used to improve the self-healing ability of the composite membrane.

[0012] To further optimize the technical solution, the negative ion releaser includes titanium alloy, zinc oxide and iron oxide; the high-strength bio-based polymer includes polylactic acid and polyhydroxyalkanoate; in the natural antioxidants encapsulated in the microcapsules, the carriers of the microcapsules are chitosan and polylactic acid, and the natural antioxidants are green tea and rosemary extracts.

[0013] Further optimizing the technical solution, the method for preparing the moisture-absorbing and moisture-proof composite film comprises the following specific steps: S1, pre-processing raw materials; S2, preparing a negative ion release agent mixture to provide materials for the preparation of the middle layer and the outer layer; S3, preparing self-healing polymers and microcapsules; S4, preparing natural antioxidant microcapsules; S5, preliminary forming of the polymer base film, and preliminary formation of the base film layer; S6, stacking and laminating the composite membrane layers to form a composite membrane structure; S7, drying the composite membrane structure; S8, conduct quality inspection and finished product packaging.

[0014] To further optimize the technical solution, in step S1, polylactic acid and polyhydroxyalkanoate are first dried to remove moisture therein to prevent moisture from affecting the subsequent molding process; the negative ion releasers of titanium alloy, zinc oxide, and iron oxide are activated at high temperature to ensure efficient negative ion release in the film layer; the green tea and rosemary extracts in the natural extracts are kept active by low-temperature drying to avoid destruction of their effective ingredients due to high-temperature treatment.

[0015] To further optimize the technical solution, in step S5, the high-strength bio-based polymers are mixed according to mass fractions, and a plasticizer is added to dissolve them to form a uniform polymer solution; the solution is coated by solution dipping or casting to form a base film layer.

[0016] To further optimize the technical solution, in step S6, negative ion releasers, self-healing polymers and natural antioxidants encapsulated in microcapsules are sequentially added to the base film layer; hot pressing or cold pressing technology is used to bond the various layers so that each layer is firmly bonded to form a stable composite film structure.

[0017] Compared with the prior art, the present invention provides a moisture-absorbing and moisture-proof composite film, which has the following beneficial effects: The moisture-absorbing and moisture-proof composite membrane overcomes the problems of poor durability and insufficient antioxidant properties in the existing technology through a reasonable hierarchical structure design and a combination of multiple innovative materials. The composite membrane uses innovative materials such as high-strength bio-based polymers, negative ion releasers, self-healing polymers, and natural antioxidant microcapsules to enhance the comprehensive performance of the membrane. Not only does it have excellent moisture-absorbing and moisture-proof functions, but it also improves air purification and antibacterial properties through the addition of negative ion releasers; the self-healing polymer can automatically repair cracks when the membrane surface is damaged, extending the service life; the natural antioxidant microcapsules can effectively resist oxidation, ensuring that the membrane material maintains excellent performance for a long time. In addition, the raw materials of the membrane mainly come from renewable bio-based polymers, which have good environmental friendliness and degradability, and meet current environmental protection requirements. Therefore, while improving performance, the composite membrane has a high market application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of the components of a moisture-absorbing and moisture-proof composite film proposed by the present invention; Figure 2 This is a schematic diagram of an additive for a moisture-absorbing and moisture-proof composite film proposed by the present invention. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0023] Embodiment 1: Reference Figure 1-2 , which is the first embodiment of the present invention, provides a hygroscopic and moisture-proof composite film, including an inner layer, a middle layer and an outer layer, wherein the inner layer is a hygroscopic layer, the middle layer is a moisture-proof layer, and the outer layer is a protective layer.

[0024] The components of the inner layer include polyvinyl alcohol, polyacrylic acid, hygroscopic nanoparticles and water; the inner layer is used for hygroscopicity, quickly absorbing and locking moisture, providing water absorption and film-forming properties through the combination of polyvinyl alcohol and polyacrylic acid, and the hygroscopic nanoparticles improve the overall water absorption efficiency of the film and enhance the uniformity of the film.

[0025] Polyvinyl alcohol (PVA) is a polymer material with good hygroscopic properties and biodegradability, and is commonly used in water-soluble films. In the inner layer of this composite film, PVA is combined with polyacrylic acid (PAA) to form a composite material with higher hygroscopic capacity. PAA has strong hydrophilicity and hydrogel properties, which can effectively enhance hygroscopic properties. The combination of the two not only improves the hygroscopicity of the film, but also maintains the stability of the film's morphology during the hygroscopic process, preventing excessive diffusion of water.

[0026] This combination has a more prominent advantage in hygroscopicity than traditional single polymer materials, and can absorb moisture more quickly and efficiently while maintaining the structural strength of the membrane. In addition, the combination of PVA and PAA improves the operability and environmental friendliness of the membrane, because both materials are biodegradable and meet the requirements of sustainable development.

[0027] Hygroscopic nanoparticles refer to materials with significant water absorption capacity at the nanoscale, such as porous silicon, nano-alumina, etc. These nanoparticles significantly enhance the hygroscopic properties of the inner layer through surface effects and are able to capture and lock more water in a smaller space.

[0028] The addition of nanoparticles increases the moisture absorption rate and capacity of the membrane, making the composite membrane more stable in a humid environment. Compared with the hygroscopic materials commonly used in the prior art, nanoparticles can improve the uniformity and strength of the membrane, while effectively avoiding the problem of excessive moisture loss and extending the service life of the membrane.

[0029] The components of the middle layer include polyurethane, fluorinated polymer, graphene and waterproof coating; for moisture-proofing, polyurethane provides strength and elasticity, fluorinated polymer enhances the waterproof performance of the membrane, graphene improves the overall stability and thermal conductivity of the membrane, and the waterproof coating effectively prevents moisture penetration.

[0030] Polyurethane has good elasticity and durability, while fluorinated polymers (such as polytetrafluoroethylene) are outstanding in waterproofing and antifouling. By combining these two materials, the flexibility of polyurethane and the waterproof properties of fluorinated polymers can be fully utilized to form a composite membrane with both elasticity and waterproof functions.

[0031] This combination is relatively rare in the prior art because it can significantly improve the moisture resistance of the membrane while ensuring the flexibility of the membrane. This allows the composite membrane to effectively prevent moisture penetration in a humid environment and is not prone to losing elasticity due to moisture, thus extending the service life of the membrane.

[0032] Graphene is a two-dimensional carbon material with excellent thermal conductivity, electrical conductivity and mechanical properties. In this composite membrane, the addition of graphene not only enhances the strength of the membrane, but also improves the thermal conductivity of the membrane to a certain extent, preventing the deformation of the membrane caused by temperature difference.

[0033] The addition of graphene enhances the structural stability of the membrane, especially in high humidity environments, and can effectively reduce the physical deformation or aging of the membrane. It also has a certain anti-ultraviolet ability, further improving the durability of the membrane.

[0034] The components of the outer layer include polyester, nanosilver and superhydrophobic coating, which are used to provide durability and anti-pollution properties. Polyester increases the strength and durability of the membrane, nanosilver has antibacterial effects, and the superhydrophobic coating makes the membrane surface more waterproof and anti-pollution, reducing the impact of external moisture on the membrane.

[0035] Polyester material itself has good mechanical strength and wear resistance, which can provide external protection for the membrane. Nanosilver is known for its significant antibacterial properties and anti-pollution ability. Adding nanosilver to the outer layer not only improves the antibacterial ability of the membrane, prevents the growth of bacteria and microorganisms, but also effectively inhibits the accumulation of stains on the membrane surface. It improves the antibacterial and self-cleaning ability of the composite membrane, avoids the problem of easy accumulation of dirt and microorganisms in traditional membrane materials, ensures the long-term stability and hygiene of the membrane, and is especially suitable for environments that require high hygiene standards.

[0036] Super hydrophobic coating can give the membrane surface extremely strong water-repellent properties, making it effectively waterproof in humid environments and preventing water droplets from adhering to the surface to form watermarks or stains. This coating uses nanotechnology to form a micron-scale structure on the membrane surface, reducing the water contact area and improving the membrane's water repellency and anti-pollution properties.

[0037] The addition of super-hydrophobic coating greatly improves the waterproofness and anti-fouling properties of the membrane. Compared with traditional waterproof membranes, this coating can significantly reduce the residence time of water droplets on the surface, keeping the membrane clean and dry. In addition, the long-term and stability of this coating enhances the adaptability and durability of the membrane in harsh environments.

[0038] The mass fractions of the components in the inner layer, the middle layer and the outer layer are as follows: Polyvinyl alcohol is 30 parts; Polyacrylic acid is 10 parts; 15 parts of hygroscopic nanoparticles; Water is 35 parts; Polyurethane is 30 parts; 10 parts of fluorinated polymer; Graphene is 5 parts; The waterproof coating is 4 parts; Polyester is 45 parts; Nanosilver is 1 part; Super hydrophobic coating is 4 parts.

[0039] The moisture-absorbing and moisture-proof composite film also includes the following additives, which include: Photocatalytic nanoparticles; Negative ion releaser; High-strength bio-based polymers; Self-healing polymers; Microencapsulated natural antioxidants; Furthermore, the mass fractions of the additives are as follows: Photocatalytic nanoparticles are 1 part; The negative ion release agent is 1.5 parts; 2 parts of high-strength bio-based polymer; 2.5 parts of self-healing polymer; 1.5 parts of natural antioxidants encapsulated in microcapsules; The high-strength bio-based polymer is added in the inner layer; the photocatalytic nanoparticles and self-repairing polymer are added in the middle layer; and the negative ion releaser and microcapsulated natural antioxidants are added in the outer layer.

[0040] In this embodiment, the photocatalytic nanoparticles are titanium dioxide. Under ultraviolet irradiation, titanium dioxide decomposes organic pollutants in the air; the photolysis reaction formula is as follows: ; In the formula, the organic pollutant benzyl methane is decomposed into carbon dioxide and water under the catalytic action of titanium dioxide, purifying the air; ultraviolet light UV is the driving factor in the reaction and is used to enhance the efficiency of photocatalysis.

[0041] Titanium dioxide can decompose harmful substances or dirt in the air under ultraviolet light. These particles act as an active ingredient in the membrane and can use the energy of ultraviolet light to spontaneously clean the membrane surface and reduce the accumulation of harmful substances.

[0042] Most membrane materials currently cannot clean themselves, but photocatalytic nanoparticles make the membrane surface self-cleaning. Especially for applications that need to remain clean for a long time (such as medical and health or food packaging), this function greatly improves the service life and efficiency of the membrane.

[0043] In this embodiment, the self-healing polymer contains microcapsules, and the microcapsules contain a repair agent of a carboxyl monomer; when the composite film is damaged, the repair agent is released from the microcapsules and undergoes a polymerization reaction to repair the cracks; the repair reaction formula is as follows: ; In the formula, the carboxyl monomer reacts with water to polymerize into longer chain molecules, thereby filling and repairing the cracks in the membrane. The reaction occurs automatically when the membrane is damaged, and is used to improve the self-healing ability of the composite membrane.

[0044] Self-healing polymers can automatically repair the membrane when tiny cracks or damage occur. These polymers contain repair materials that can be activated when damaged, which can effectively restore the integrity of the membrane and reduce the damage and maintenance frequency of the membrane. Traditional membranes are prone to loss of function after damage and need to be replaced or repaired. Self-healing polymers can effectively extend the service life of the membrane and reduce maintenance costs. They have obvious advantages in environments where long-term use is required (such as building exterior walls, car sunshade films, etc.).

[0045] In this embodiment, the negative ion releaser includes titanium alloy, zinc oxide and iron oxide; the high-strength bio-based polymer includes polylactic acid and polyhydroxyalkanoate; in the natural antioxidants encapsulated in the microcapsules, the carriers of the microcapsules are chitosan and polylactic acid, and the natural antioxidants are green tea and rosemary extracts.

[0046] Furthermore, the negative ion releaser provides a continuous air purification function in the outer layer of the membrane, which is particularly suitable for environments with poor air quality. Compared with the single moisture-proof or waterproof function in the prior art, the additional health and air purification effects provided by the negative ion releaser enhance the comprehensive function of the membrane. Titanium alloy has high strength, corrosion resistance and good electronic conductivity, and is suitable for negative ion release. The titanium surface can generate negative ions under the action of air humidity and ultraviolet rays, and release them into the air through a certain carrier structure. Zinc oxide is a common semiconductor material that can generate electron-hole pairs under ultraviolet light, thereby releasing negative ions. It is widely used in air purification and antibacterial materials. Iron oxide can be used as a catalyst for the release of negative ions, and its surface can adsorb and release negative ions to improve air quality.

[0047] The application of high-strength bio-based polymers (such as biodegradable polylactic acid, polyhydroxyalkanoates, etc.) in the inner layer can enhance the hygroscopicity and structural strength of the membrane. Its bio-based source makes the membrane material degradable, reducing the risk of environmental pollution. Traditional hygroscopic layer materials are mostly petroleum-based materials, which are not degradable and may burden the environment. The use of high-strength bio-based polymers can not only improve the performance of the membrane, but also have environmental advantages, which meets the current requirements of sustainable development. Polylactic acid is a polymer material produced from renewable resources (such as corn starch or sugarcane) with good mechanical strength and biodegradability. PLA is commonly used in packaging, textiles and membrane materials, and has good hygroscopicity and environmental protection characteristics. Polyhydroxyalkanoates are a type of bio-based polymer synthesized by microorganisms, with good biodegradability and relatively high mechanical strength, and are commonly used in plastics and membrane materials. Its heat resistance and moisture resistance enable it to maintain excellent mechanical properties in humid environments.

[0048] Natural antioxidants encapsulated in microcapsules (such as vitamin E, green tea extract, etc.) can provide antioxidant protection in the outer layer to prevent the membrane material from aging or degradation due to long-term exposure to oxygen and ultraviolet rays. Microcapsules can effectively control the release rate of antioxidants to ensure long-term stability. Traditional membrane materials are usually easily degraded by ultraviolet rays or oxygen in the air, especially in the outer layer. Natural antioxidants encapsulated in microcapsules can achieve timed release, maintain the anti-aging properties of the outer layer, delay the degradation process of the membrane, and extend its service life. Green tea and rosemary extracts are rich in natural antioxidants (such as polyphenols, flavonoids, etc.), have excellent antioxidant and anti-aging effects, and can effectively prevent the membrane material from oxidative aging due to long-term exposure to oxygen. Chitosan is a natural polysaccharide that is often used to prepare microcapsules. It has good biocompatibility and degradability, can effectively protect the internal antioxidants from the influence of the external environment, and can gradually release antioxidants when the membrane is damaged. Polylactic acid is another common microcapsule material. Its biodegradability and environmental friendliness make it an ideal choice for encapsulating natural antioxidants. Polylactic acid can provide a long-term controlled release effect in the film.

[0049] In this embodiment, the mass fraction of the negative ion releasing agent is distributed as follows: Titanium alloy: 25-30 parts; Zinc oxide: 30-35 parts; Iron oxide: 35-40 parts.

[0050] The mass fraction of high-strength bio-based polymer is distributed as follows: Polylactic acid (PLA): 45-50 parts; Polyhydroxyalkanoate (PHA): 45-50 parts; The mass fraction of natural antioxidants encapsulated in microcapsules is distributed as follows: Green tea extract (natural antioxidant): 35-40 parts; Rosemary extract (natural antioxidant): 35-40 parts; Chitosan: 15-20 parts; Polylactic acid (PLA): 10-15 parts.

[0051] In summary, these additives are located at different layers of the composite membrane (inner layer, middle layer, outer layer), each playing a unique role to improve the overall performance of the membrane: Inner layer (hygroscopic layer): The use of high-strength bio-based polymers enhances the membrane’s hygroscopicity while remaining environmentally friendly.

[0052] Middle layer (moisture-proof layer): Photocatalytic nanoparticles and self-healing polymers enable the membrane to have self-cleaning and self-repairing capabilities, improving the durability and intelligence of the membrane.

[0053] Outer layer (protective layer): Negative ion releasers and natural antioxidants encapsulated in microcapsules give the membrane air purification and antioxidant protection functions, enhancing the membrane's adaptability in harsh environments.

[0054] Embodiment 2: The second embodiment of the present invention provides a method for preparing the moisture-absorbing and moisture-proof composite film, comprising the following specific steps: S1. Pre-treat raw materials.

[0055] First of all, all the main raw materials, such as polylactic acid, polyhydroxyalkanoate, titanium alloy, zinc oxide, iron oxide, green tea extract, rosemary extract, chitosan, etc., need to be pretreated. Polylactic acid and polyhydroxyalkanoate need to be dried first to remove the moisture in them to avoid moisture affecting the subsequent molding process. Anion releasers such as titanium alloy, zinc oxide, and iron oxide need to be activated at high temperature to ensure their efficient anion release in the film layer. Natural extracts (such as green tea and rosemary extracts) should be kept active by low-temperature drying to avoid the destruction of their active ingredients due to high-temperature treatment.

[0056] S2. Prepare a negative ion release agent mixture to provide materials for the preparation of the middle layer and the outer layer.

[0057] Mix titanium alloy, zinc oxide and iron oxide according to their mass fractions, add an appropriate amount of organic solvent (such as isopropyl alcohol) to disperse and form a uniform slurry. This mixture will play a negative ion release function in the outer and middle layers of the membrane, purify the air and enhance the antibacterial ability of the membrane. In particular, zinc oxide can decompose harmful substances in the air under ultraviolet light, while titanium alloy and iron oxide continuously release negative ions, effectively improving the quality of ambient air. This step fully prepares for the subsequent lamination process and ensures that the materials are evenly distributed.

[0058] S3. Prepare self-healing polymers and microcapsules.

[0059] In this process, microcapsules are first filled with a polymer solution, which contains a repair agent that can be automatically activated when the membrane is damaged. The repair agent is usually a monomer containing a carboxyl group, which reacts with water and air when the membrane is damaged to form a long chain structure to fill the cracks. The combination of polyurethane and polyvinyl alcohol provides high mechanical strength, allowing the membrane to restore its performance through self-healing function when it is damaged from the outside.

[0060] S4. Prepare natural antioxidant microcapsules.

[0061] Microcapsules are prepared by copolymerization of chitosan and polylactic acid using natural antioxidant substances such as green tea extract and rosemary extract. These microcapsules can effectively protect the antioxidant components inside and prevent them from being released prematurely during the production process. The outer layer of polylactic acid in the microcapsules is biodegradable, ensuring that it gradually releases antioxidants during the use of the membrane and slows down the aging of the membrane material. Through this step, the membrane surface can maintain its antioxidant properties for a long time, enhancing the durability and service life of the membrane.

[0062] S5. Preliminary shaping of the polymer base film to preliminarily form a base film layer.

[0063] After mixing high-strength bio-based polymers by mass, add plasticizer to dissolve them to form a uniform polymer solution. The solution is coated on the substrate by solution dipping or casting to form a base film layer. This layer mainly provides structural support for the film and has good hygroscopicity and moisture resistance. By controlling the solution concentration and coating speed, the thickness and uniformity of the film can be adjusted to ensure good adhesion of subsequent layers.

[0064] S6. Superimposing and laminating the composite membrane layers to form a composite membrane structure.

[0065] Use hot or cold pressing technology to bond each layer together so that each layer is firmly bonded to form a stable composite membrane structure. In particular, in the preparation process of the self-healing layer, the temperature and pressure are adjusted to ensure that the microcapsules are evenly distributed in the membrane and that the membrane can be quickly repaired when it is slightly damaged. The lamination process of the composite membrane needs to be controlled within the appropriate pressure and temperature range to ensure the strength and functionality of the membrane.

[0066] S7. Drying the composite membrane structure.

[0067] The composite film is dried by hot air drying or infrared curing. The purpose of this step is to remove excess solvent and moisture in the film so that the film material reaches the best curing state. For the layer containing microcapsules and natural antioxidants, the drying temperature should be controlled at a lower range to avoid affecting the stability of the microcapsules and the effectiveness of the antioxidant components. During the drying process, the film will gradually form a final product with high strength and high stability. This step ensures the stability of the film's various layers and enhances its mechanical properties.

[0068] S8, conduct quality inspection and finished product packaging.

[0069] After production, the composite membrane needs to undergo a series of quality tests, including hygroscopicity, antioxidant properties, negative ion release performance, self-healing effect, etc. For the physical properties of the membrane, tensile and durability tests are carried out to ensure that the membrane meets the predetermined standards. After passing the quality inspection, the membrane is cut into the required specifications and packaged. When packaging, the surface of the membrane should be avoided from contact with external pollution sources to ensure that the function of the membrane remains in the best condition. The final product is sent to customers or markets for use in various application fields.

[0070] In this embodiment, the tensile test and durability test include: Tensile test: Purpose: To test the maximum tensile strength, elongation at break, elastic modulus and other indicators of the composite film and evaluate the tensile strength and ductility of the film.

[0071] Test method: Use a tensile testing machine to perform uniaxial stretching on the film sample under specified test conditions, record the relationship between stress and strain, and calculate the tensile strength and elongation at break.

[0072] Test standard: According to ASTM D882 or GB / T 1040.

[0073] Durability test: Purpose: To test the stability of composite films in long-term use, including their ability to resist aging, UV rays, and climate change.

[0074] Test method: Use an aging box to perform ultraviolet accelerated aging test on the composite film (such as UVB-313 lamp to accelerate ultraviolet irradiation), or use a temperature and humidity cycle tester to perform climate resistance cycle test.

[0075] Test standard: According to ASTM G154 or ISO 4892.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A moisture-absorbing and moisture-proof composite film, characterized in that: It comprises an inner layer, a middle layer and an outer layer, wherein the inner layer is a moisture-absorbing layer, the middle layer is a moisture-proof layer, and the outer layer is a protective layer; The inner layer comprises polyvinyl alcohol, polyacrylic acid, hygroscopic nanoparticles and water; the inner layer is used for hygroscopicity, quickly absorbing and locking moisture, and provides water absorption and film-forming properties through the combination of polyvinyl alcohol and polyacrylic acid. The hygroscopic nanoparticles improve the overall water absorption efficiency of the film and enhance the uniformity of the film. The intermediate layer comprises polyurethane, fluorinated polymer, graphene and waterproof coating; the intermediate layer is used for moisture-proofing, polyurethane provides strength and elasticity, fluorinated polymer enhances the waterproof performance of the membrane, graphene improves the overall stability and thermal conductivity of the membrane, and the waterproof coating effectively prevents moisture penetration; The outer layer comprises polyester, nanosilver and super-hydrophobic coating, which are used to provide durability and anti-pollution properties. Polyester increases the strength and durability of the membrane, nanosilver has antibacterial effects, and the super-hydrophobic coating makes the membrane surface more waterproof and anti-fouling, reducing the impact of external moisture on the membrane. The moisture-absorbing and moisture-proof composite film also includes the following additives, which include: Photocatalytic nanoparticles; Negative ion releaser; High-strength bio-based polymers; Self-healing polymers; Microencapsulated natural antioxidants.

2. A moisture-absorbing and moisture-proof composite film according to claim 1, characterized in that: The mass fractions of the components in the inner layer, the middle layer and the outer layer are as follows: Polyvinyl alcohol is 25-30 parts; Polyacrylic acid is 5-10 parts; 10-15 parts of hygroscopic nanoparticles; Water is 30-35 parts; Polyurethane is 25-30 parts; 5-10 parts of fluorinated polymer; Graphene is 3-5 parts; Waterproof coating is 2-4 parts; Polyester is 40-45 parts; Nano silver is 0.5-1 part; Super hydrophobic coating is 2-4 parts.

3. A moisture-absorbing and moisture-proof composite film according to claim 1, characterized in that: The mass fractions of the additives are as follows: Photocatalytic nanoparticles are 0.5-1 part; The negative ion release agent is 0.5-1.5 parts; High-strength bio-based polymer is 1-2 parts; 1.5-2.5 parts of self-healing polymer; The natural antioxidants encapsulated in microcapsules are 0.5-1.5 parts; The high-strength bio-based polymer is added in the inner layer; the photocatalytic nanoparticles and self-repairing polymer are added in the middle layer; and the negative ion releaser and microcapsulated natural antioxidants are added in the outer layer.

4. A moisture-absorbing and moisture-proof composite film according to claim 3, characterized in that: The photocatalytic nanoparticles are titanium dioxide. Under ultraviolet irradiation, titanium dioxide decomposes organic pollutants in the air; the photolysis reaction formula is as follows: ； In the formula, the organic pollutant benzyl methane is decomposed into carbon dioxide and water under the catalytic action of titanium dioxide, purifying the air; ultraviolet light UV is the driving factor in the reaction and is used to enhance the efficiency of photocatalysis.

5. The moisture-absorbing and moisture-proof composite film according to claim 1, characterized in that: The self-healing polymer contains microcapsules, and the microcapsules contain a repair agent of a carboxyl monomer; when the composite film is damaged, the repair agent is released from the microcapsules and undergoes a polymerization reaction to repair the cracks; the repair reaction formula is as follows: ； In the formula, the carboxyl monomer reacts with water to polymerize into longer chain molecules, thereby filling and repairing the cracks in the membrane. The reaction occurs automatically when the membrane is damaged, and is used to improve the self-healing ability of the composite membrane.

6. A moisture-absorbing and moisture-proof composite film according to claim 1, characterized in that: The negative ion releaser includes titanium alloy, zinc oxide and iron oxide; the high-strength bio-based polymer includes polylactic acid and polyhydroxyalkanoate; in the natural antioxidant encapsulated in the microcapsule, the carrier of the microcapsule is chitosan and polylactic acid, and the natural antioxidant is green tea and rosemary extract.

7. The moisture-absorbing and moisture-proof composite film according to claim 1, characterized in that: The preparation method of the moisture-absorbing and moisture-proof composite film comprises the following specific steps: S1, pre-processing raw materials; S2, preparing a negative ion release agent mixture to provide materials for the preparation of the middle layer and the outer layer; S3, preparing self-healing polymers and microcapsules; S4, preparing natural antioxidant microcapsules; S5, preliminary forming of the polymer base film, and preliminary formation of the base film layer; S6, stacking and laminating the composite membrane layers to form a composite membrane structure; S7, drying the composite membrane structure; S8, conduct quality inspection and finished product packaging.

8. A moisture-absorbing and moisture-proof composite film according to claim 7, characterized in that: In the step S1, polylactic acid and polyhydroxyalkanoate are first dried to remove moisture therein to prevent moisture from affecting the subsequent molding process; the negative ion releasers of titanium alloy, zinc oxide and iron oxide are activated at high temperature to ensure efficient negative ion release in the film layer; the green tea and rosemary extracts in the natural extracts are kept active by low-temperature drying to avoid the destruction of their effective ingredients due to high-temperature treatment.

9. The moisture-absorbing and moisture-proof composite film according to claim 7, characterized in that: In the step S5, high-strength bio-based polymers are mixed according to mass fractions, and a plasticizer is added to dissolve them to form a uniform polymer solution; the solution is coated by solution dipping or casting to form a base film layer.

10. The moisture-absorbing and moisture-proof composite film according to claim 7, characterized in that: In step S6, negative ion releasers, self-healing polymers and natural antioxidants encapsulated in microcapsules are sequentially added to the base film layer; each layer is bonded using hot pressing or cold pressing technology so that each layer is firmly bonded to form a stable composite film structure.

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