Fresh-keeping cloth based on micro-nano mineral hydroxyl anions and application of fresh-keeping cloth

Abstract

The invention belongs to the technical field of food fresh keeping, and particularly relates to fresh keeping cloth based on micro-nano mineral substance hydroxyl anions and application of the fresh keeping cloth. The fresh keeping cloth comprises a base layer, a functional layer, a slow-release and release-promoting layer and a protective layer which are sequentially arranged from bottom to top; the base layer is cotton and linen blended cloth or bamboo fiber cloth, and the gram weight is 80-120 g / m < 2 >; the functional layer is prepared from the following raw materials in parts by weight: 20 to 40 parts of micro-nano mineral composite powder, 40 to 60 parts of waterborne polyurethane emulsion, 2 to 4 parts of dispersing agent, 3 to 5 parts of toughening agent, 1 to 3 parts of antibacterial additive and 10 to 20 parts of deionized water. By adopting the micro-nano mineral composite powder and the dispersing agent in a specific ratio and combining the composite structure of the functional layer and the slow-release and release-promoting layer, the effect of efficiently and uniformly releasing hydroxyl anions is achieved, and meanwhile, the release period is prolonged by virtue of the loading effect of the slow-release and release-promoting layer; the problem that in the prior art, the negative ion release amount is small, the period is short, and the fresh-keeping effect is not stable due to insufficient local concentration is thoroughly solved.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, specifically to a food preservation cloth based on micro-nano mineral hydroxyl negative ions and its application. Background Technology

[0002] Food preservation is a crucial step in ensuring food quality, extending shelf life, and reducing food waste. It is widely used in various scenarios, including daily household use, the catering industry, fresh food e-commerce, and cold chain logistics. Current mainstream food preservation technologies mainly include physical preservation (such as refrigeration, freezing, and vacuum packaging), chemical preservation (such as adding preservatives and freshness-preserving agents), and natural preservatives.

[0003] While physical preservation methods can delay food spoilage to some extent, they suffer from high energy consumption, strong equipment dependence, and the inability to fundamentally inhibit microbial growth. Furthermore, for fruits and vegetables, refrigeration and freezing can easily damage cell walls and cause moisture loss, affecting taste and nutritional value. Chemical preservation methods achieve preservation by adding synthetic preservatives. Although the preservation effect is significant, some chemical preservatives pose potential food safety risks, and long-term intake may harm human health. Moreover, consumers' acceptance of chemical additives is gradually decreasing. Natural preservatives (such as plant extracts and probiotics) are relatively safe, but they generally suffer from high costs, short preservation periods, and unstable preservation effects, making it difficult to meet the needs of large-scale, long-term preservation.

[0004] Based on the above situation, developing a preservation material that combines high safety, good preservation effect, moderate cost, ease of use, and wide applicability has become a research hotspot in the industry. Hydroxyl anions possess strong oxidizing properties, capable of disrupting the cell membrane structure of microorganisms (bacteria, molds, yeasts, etc.), inhibiting their metabolism and reproduction, and simultaneously adsorbing odor molecules in the air to achieve deodorization. Furthermore, hydroxyl anions can regulate environmental humidity, reducing moisture loss from food, and for fruits and vegetables, they can slow down their respiration, reducing nutrient loss. Micro- and nano-sized mineral materials (such as tourmaline, diatomaceous earth, etc.) have natural hydroxyl anion release properties, are widely available, inexpensive, and highly safe. Applying them to the preparation of preservation materials holds promise for overcoming many shortcomings of existing preservation technologies.

[0005] Despite the significant advantages of hydroxyl anions and micro / nano mineral materials in food preservation, the following core issues still exist in current technologies: 1. Low release efficiency of hydroxyl negative ions: In existing mineral-containing preservation materials, the mineral particles are mostly of conventional particle size with small specific surface area, resulting in low release of hydroxyl negative ions and short release cycle, making it difficult to achieve a long-term stable preservation effect; at the same time, the mineral particles are not evenly dispersed in the material, which can easily lead to insufficient local negative ion concentration, resulting in unstable preservation effect.

[0006] 2. It is difficult to balance the mechanical properties and preservation performance of food preservation cloth: If the amount of micro-nano mineral particles added is simply increased to improve the release of hydroxyl negative ions, the flexibility of the food preservation cloth will decrease, making it easy to break and shortening its service life, thus failing to meet the needs of repeated use; if the amount added is reduced, the preservation effect will be greatly reduced.

[0007] 3. Limited functionality: Most existing mineral preservation materials only have antibacterial and preservation functions, and cannot simultaneously achieve multiple functions such as moisturizing, deodorizing, and slowing down the respiration of fruits and vegetables, making it difficult to meet the diverse preservation needs of different types of food (such as fresh meat, fruits and vegetables, cooked food, etc.).

[0008] 4. Limited application scenarios: Most existing food preservation materials are disposable films or sheets, which easily generate waste after use and are not environmentally friendly; in addition, their fixed shape makes it difficult to adapt to food of different shapes and sizes, resulting in poor ease of use, and they are especially unsuitable for flexible use in daily household and catering industries. Summary of the Invention

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A food preservation cloth based on micro-nano mineral hydroxyl negative ions includes, from bottom to top, a base layer, a functional layer, a slow-release and fast-release layer, and a protective layer; The base layer is a cotton-linen blend or bamboo fiber fabric with a basis weight of 80-120 g / m². 2 ; The raw materials of the functional layer include, by weight: 20-40 parts of micro-nano mineral composite powder, 40-60 parts of water-based polyurethane emulsion, 2-4 parts of dispersant, 3-5 parts of toughening agent, 1-3 parts of antibacterial agent, and 10-20 parts of deionized water. The raw materials of the sustained-release and accelerated-release layer include, by weight: 5-10 parts of chitosan / montmorillonite composite sustained-release agent, 20-30 parts of water-based acrylic emulsion, and 10-15 parts of deionized water. The protective layer is a breathable and waterproof membrane with a breathability of 500-800 g / m³. 2 ·24h.

[0010] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, wherein the weight ratio of cotton fiber to linen fiber in the cotton-linen blended fabric of the base layer is 7:3.

[0011] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, the micro-nano mineral composite powder is obtained by mixing tourmaline powder, tourmaline powder and diatomaceous earth powder in a weight ratio of 3:2:1 and then pulverizing them with airflow to a particle size of 50-200nm.

[0012] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, the dispersant is sodium polyacrylate or polyethylene glycol.

[0013] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, the toughening agent is epoxidized soybean oil or dibutyl phthalate.

[0014] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, the antibacterial additive is nano silver powder or zinc oxide powder with a particle size of 20-50nm.

[0015] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, the chitosan / montmorillonite composite slow-release agent is obtained by mixing chitosan and montmorillonite in a weight ratio of 2:1, followed by ultrasonic dispersion, stirring reaction, drying and grinding to a particle size of 100-200nm.

[0016] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl negative ions described in this invention, the breathable and waterproof membrane is a polytetrafluoroethylene breathable membrane or a polyurethane breathable membrane.

[0017] As a preferred embodiment of the food preservation cloth based on micro-nano mineral hydroxyl anions described in this invention, it further includes a preparation method, the specific steps of which are as follows: S1, Preparation of micro-nano mineral composite powder: Tourmaline powder, tourmaline powder and diatomaceous earth powder are mixed in proportion, put into an air jet mill, and pulverized under a pressure of 0.6-0.8MPa to obtain micro-nano mineral composite powder with a particle size of 50-200nm. S2, Preparation of functional slurry: Add dispersant to deionized water, stir evenly, then add micro-nano mineral composite powder, and disperse at high speed for 30-60 min at a speed of 2000-3000 r / min to obtain mineral dispersion; then add waterborne polyurethane emulsion, toughening agent and antibacterial agent to mineral dispersion, and continue stirring for 60-90 min to obtain functional slurry; S3, Composite Molding: The functional slurry is evenly coated onto one side of the substrate surface, with a coating amount of 20-30 g / m². 2Dry at 80-100℃ for 15-20 minutes to obtain the base layer of the composite functional layer; S4, Preparation and Coating of Sustained-Release and Promoting-Release Slurry: Add chitosan / montmorillonite composite sustained-release agent to deionized water, stir and disperse at 1500-2000 r / min for 20-30 min, then add aqueous acrylic emulsion and continue stirring for 30-40 min to obtain the sustained-release and promoting-release slurry; uniformly coat it onto the surface of the functional layer, with a coating amount of 10-15 g / m². 2 Dry at 70-80℃ for 15-20 minutes to form a slow-release and accelerated-release layer; S5, Final Composite: The protective layer is laminated onto the surface of the slow-release and activating layer, and then hot-pressed to obtain the finished food preservation cloth. The hot-pressing temperature is 130-140℃, the pressure is 0.3-0.5MPa, and the time is 3-5min.

[0018] An application of a food preservation cloth based on micro-nano mineral hydroxyl negative ions includes the above-mentioned food preservation cloth based on micro-nano mineral hydroxyl negative ions. The food preservation cloth is used for the preservation of fruits and vegetables, fresh meat, cooked food or seafood, and the application methods include directly wrapping food, cutting it into a specific shape to cover the surface of food, or making it into a food preservation bag or food preservation box liner.

[0019] Compared with existing technologies: 1. By using a specific ratio of micro-nano mineral composite powder and dispersant, combined with the composite structure of functional layer and slow-release and accelerator layer, it can achieve the effect of efficient and uniform release of hydroxyl negative ions. At the same time, the release cycle is extended by the loading effect of slow-release and accelerator layer, which completely solves the problem of unstable preservation effect caused by low negative ion release, short cycle and insufficient local concentration in the existing technology. 2. By using water-based polyurethane emulsion as a binder and adding an appropriate amount of toughening agent, the mechanical properties and preservation performance of the food preservation cloth can be balanced while ensuring the amount of effective ingredients added to the functional layer. This avoids the problem of decreased flexibility and easy breakage caused by increasing mineral content, extends the product's service life, and meets the needs of repeated use. 3. Through the synergistic effect of the hydroxyl negative ions released by the micro-nano mineral composite powder, the water absorption and moisturizing properties of diatomaceous earth, and the additional antibacterial agents, it can achieve the integrated effect of multiple functions such as antibacterial, preservation, moisturizing and deodorization, breaking through the limitation of the single function of existing materials and adapting to the diverse preservation needs of different types of food. 4. By using a flexible cotton-linen blend or bamboo fiber base layer and a breathable and waterproof protective layer, it is designed into a cuttable fabric structure, which can be reused and adapted to various food shapes, reducing the generation of disposable waste, improving ease of use, and getting rid of the problems of fixed material shape and limited application scenarios of existing materials. Attached Figure Description

[0020] Figure 1 This is a front view schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram showing the structure of the present invention separated; Figure 3 This is a frontal sectional view of the structure of the present invention.

[0021] In the diagram: Protective layer 10, slow-release and accelerated-release layer 20, functional layer 30, base layer 40. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] Example 1: This invention provides a food preservation cloth based on micro / nano mineral hydroxyl anions. Please refer to [link / reference]. Figures 1-3 It includes, from bottom to top, a base layer 40, a functional layer 30, a slow-release and accelerated-release layer 20, and a protective layer 10; The base layer 40 is a cotton-linen blend or bamboo fiber fabric with a basis weight of 80g / m². 2 In cotton-linen blended fabrics, the weight ratio of cotton fiber to linen fiber is 7:3.

[0024] The raw materials of the functional layer 30, by weight, include: 20 parts of micro-nano mineral composite powder, 40 parts of water-based polyurethane emulsion, 2 parts of dispersant, 3 parts of toughening agent, 1 part of antibacterial agent, and 10 parts of deionized water; the micro-nano mineral composite powder is obtained by mixing tourmaline powder, tourmaline powder, and diatomaceous earth powder in a weight ratio of 3:2:1 and then pulverizing them with airflow to a particle size of 50nm; the dispersant is sodium polyacrylate or polyethylene glycol; the toughening agent is epoxidized soybean oil or dibutyl phthalate; the antibacterial agent is nano silver powder or zinc oxide powder with a particle size of 20nm.

[0025] The raw materials of the sustained-release and catalytic-release layer 20 include, by weight: 5 parts of chitosan / montmorillonite composite sustained-release agent, 20 parts of aqueous acrylic emulsion, and 10 parts of deionized water; the chitosan / montmorillonite composite sustained-release agent is obtained by mixing chitosan and montmorillonite in a weight ratio of 2:1, followed by ultrasonic dispersion, stirring reaction, drying and grinding to a particle size of 100nm.

[0026] The protective layer 10 is a breathable and waterproof membrane with a breathability of 500g / m³. 2 • 24h; the breathable and waterproof membrane is a polytetrafluoroethylene breathable membrane or a polyurethane breathable membrane.

[0027] It also includes a preparation method, the specific steps of which are as follows: S1, Preparation of micro-nano mineral composite powder: Tourmaline powder, tourmaline powder and diatomaceous earth powder are mixed in proportion, put into an air jet mill, and pulverized under a pressure of 0.6 MPa to obtain micro-nano mineral composite powder with a particle size of 50 nm. S2, Preparation of functional slurry: Add dispersant to deionized water, stir evenly, then add micro-nano mineral composite powder, and disperse at high speed for 30 min at a speed of 2000 r / min to obtain mineral dispersion; then add waterborne polyurethane emulsion, toughening agent and antibacterial agent to mineral dispersion, and continue stirring for 60 min to obtain functional slurry; S3, Composite Molding: The functional slurry is uniformly coated onto one side surface of the base layer 40, with a coating amount of 20g / m². 2 Dry at 80℃ for 15 minutes to obtain the base layer 40 of composite functional layer 30; S4, Preparation and Coating of Sustained-Release and Promoting-Release Slurry: Add chitosan / montmorillonite composite sustained-release agent to deionized water, stir and disperse at 1500 r / min for 20 min, then add aqueous acrylic emulsion and continue stirring for 30 min to obtain sustained-release and promoting-release slurry; uniformly coat it onto the surface of functional layer 30, with a coating amount of 10 g / m². 2 Dry at 70℃ for 15 minutes to form a slow-release and accelerated-release layer 20; S5, Final Composite: The protective layer 10 is composited onto the surface of the slow-release and accelerator layer 20, and then hot-pressed to obtain the finished food preservation cloth. The hot-pressing temperature is 130℃, the pressure is 0.3MPa, and the time is 3min.

[0028] An application of a food preservation cloth based on micro-nano mineral hydroxyl negative ions includes the above-mentioned food preservation cloth based on micro-nano mineral hydroxyl negative ions. The food preservation cloth is used for the preservation of fruits and vegetables, fresh meat, cooked food or seafood, and the application methods include directly wrapping food, cutting it into a specific shape to cover the surface of food, or making it into a food preservation bag or food preservation box liner.

[0029] Example 2: This invention provides a food preservation cloth based on micro / nano mineral hydroxyl anions. Please refer to [link / reference]. Figures 1-3 It includes, from bottom to top, a base layer 40, a functional layer 30, a slow-release and accelerated-release layer 20, and a protective layer 10; The base layer 40 is a cotton-linen blend or bamboo fiber fabric with a basis weight of 100g / m². 2 In cotton-linen blended fabrics, the weight ratio of cotton fiber to linen fiber is 7:3.

[0030] The raw materials of the functional layer 30, by weight, include: 30 parts of micro-nano mineral composite powder, 50 parts of water-based polyurethane emulsion, 3 parts of dispersant, 4 parts of toughening agent, 2 parts of antibacterial agent, and 15 parts of deionized water; the micro-nano mineral composite powder is obtained by mixing tourmaline powder, tourmaline powder, and diatomaceous earth powder in a weight ratio of 3:2:1, and then pulverizing the mixture with airflow to a particle size of 125nm; the dispersant is sodium polyacrylate or polyethylene glycol; the toughening agent is epoxidized soybean oil or dibutyl phthalate; the antibacterial agent is nano silver powder or zinc oxide powder with a particle size of 35nm.

[0031] The raw materials of the sustained-release and catalytic-release layer 20 include, by weight: 7.5 parts of chitosan / montmorillonite composite sustained-release agent, 25 parts of aqueous acrylic emulsion, and 12.5 parts of deionized water; the chitosan / montmorillonite composite sustained-release agent is obtained by mixing chitosan and montmorillonite in a weight ratio of 2:1, followed by ultrasonic dispersion, stirring reaction, drying and grinding to a particle size of 150nm.

[0032] The protective layer 10 is a breathable and waterproof membrane with a breathability of 650g / m³. 2 • 24h; the breathable and waterproof membrane is a polytetrafluoroethylene breathable membrane or a polyurethane breathable membrane.

[0033] It also includes a preparation method, the specific steps of which are as follows: S1, Preparation of micro-nano mineral composite powder: Tourmaline powder, tourmaline powder and diatomaceous earth powder are mixed in proportion, put into an air jet mill, and pulverized under a pressure of 0.7 MPa to obtain micro-nano mineral composite powder with a particle size of 125 nm. S2, Preparation of functional slurry: Add dispersant to deionized water, stir evenly, then add micro-nano mineral composite powder, and disperse at high speed for 45 min at a speed of 2500 r / min to obtain mineral dispersion; then add waterborne polyurethane emulsion, toughening agent and antibacterial agent to mineral dispersion, and continue stirring for 75 min to obtain functional slurry; S3, Composite Molding: The functional slurry is uniformly coated onto one side surface of the base layer 40, with a coating amount of 25g / m². 2 The substrate 40 of the composite functional layer 30 is obtained by drying at 90℃ for 17.5 min. S4, Preparation and Coating of Sustained-Release and Promoting-Release Slurry: Chitosan / montmorillonite composite sustained-release agent was added to deionized water and stirred and dispersed at 1750 r / min for 25 min. Then, aqueous acrylic emulsion was added and stirring continued for 35 min to obtain the sustained-release and promoting-release slurry. This slurry was then uniformly coated onto the surface of functional layer 30 at a coating weight of 12.5 g / m². 2 Dry at 75℃ for 17.5 min to form a slow-release and accelerated-release layer 20; S5, Final Composite: The protective layer 10 is laminated onto the surface of the slow-release and accelerator layer 20, and then hot-pressed to obtain the finished food preservation cloth. The hot-pressing temperature is 135℃, the pressure is 0.4MPa, and the time is 4min.

[0034] An application of a food preservation cloth based on micro-nano mineral hydroxyl negative ions includes the above-mentioned food preservation cloth based on micro-nano mineral hydroxyl negative ions. The food preservation cloth is used for the preservation of fruits and vegetables, fresh meat, cooked food or seafood, and the application methods include directly wrapping food, cutting it into a specific shape to cover the surface of food, or making it into a food preservation bag or food preservation box liner.

[0035] Example 3: This invention provides a food preservation cloth based on micro / nano mineral hydroxyl anions. Please refer to [link / reference]. Figures 1-3 It includes, from bottom to top, a base layer 40, a functional layer 30, a slow-release and accelerated-release layer 20, and a protective layer 10; The base layer 40 is a cotton-linen blend or bamboo fiber fabric with a basis weight of 120g / m². 2 In cotton-linen blended fabrics, the weight ratio of cotton fiber to linen fiber is 7:3.

[0036] The raw materials of the functional layer 30, by weight, include: 40 parts of micro-nano mineral composite powder, 60 parts of water-based polyurethane emulsion, 4 parts of dispersant, 5 parts of toughening agent, 3 parts of antibacterial agent, and 20 parts of deionized water; the micro-nano mineral composite powder is obtained by mixing tourmaline powder, tourmaline powder, and diatomaceous earth powder in a weight ratio of 3:2:1, and then pulverizing them with airflow to a particle size of 200nm; the dispersant is sodium polyacrylate or polyethylene glycol; the toughening agent is epoxidized soybean oil or dibutyl phthalate; the antibacterial agent is nano silver powder or zinc oxide powder with a particle size of 50nm.

[0037] The raw materials of the sustained-release and catalytic-release layer 20 include, by weight: 10 parts of chitosan / montmorillonite composite sustained-release agent, 30 parts of aqueous acrylic emulsion, and 15 parts of deionized water; the chitosan / montmorillonite composite sustained-release agent is obtained by mixing chitosan and montmorillonite in a weight ratio of 2:1, followed by ultrasonic dispersion, stirring reaction, drying and grinding to a particle size of 200nm.

[0038] The protective layer 10 is a breathable and waterproof membrane with a breathability of 800g / m³. 2 • 24h; the breathable and waterproof membrane is a polytetrafluoroethylene breathable membrane or a polyurethane breathable membrane.

[0039] It also includes a preparation method, the specific steps of which are as follows: S1, Preparation of micro-nano mineral composite powder: Tourmaline powder, tourmaline powder and diatomaceous earth powder are mixed in proportion, put into an air jet mill, and pulverized under a pressure of 0.8 MPa to obtain micro-nano mineral composite powder with a particle size of 200 nm. S2, Preparation of functional slurry: Add dispersant to deionized water, stir evenly, then add micro-nano mineral composite powder, and disperse at high speed for 60 min at a speed of 3000 r / min to obtain mineral dispersion; then add waterborne polyurethane emulsion, toughening agent and antibacterial agent to mineral dispersion, and continue stirring for 90 min to obtain functional slurry; S3, Composite Molding: The functional slurry is uniformly coated onto one side surface of the base layer 40, with a coating amount of 30g / m². 2 Drying at 100℃ for 20 minutes yields the base layer 40 of composite functional layer 30. S4, Preparation and Coating of Sustained-Release and Promoting-Release Slurry: Add chitosan / montmorillonite composite sustained-release agent to deionized water, stir and disperse at 2000 r / min for 30 min, then add aqueous acrylic emulsion and continue stirring for 40 min to obtain sustained-release and promoting-release slurry; uniformly coat it onto the surface of functional layer 30, with a coating amount of 15 g / m². 2 Dry at 80℃ for 20 minutes to form a slow-release and accelerated-release layer 20; S5, Final Composite: The protective layer 10 is composited onto the surface of the slow-release and accelerator layer 20, and then hot-pressed to obtain the finished food preservation cloth. The hot-pressing temperature is 140℃, the pressure is 0.5MPa, and the time is 5min.

[0040] An application of a food preservation cloth based on micro-nano mineral hydroxyl negative ions includes the above-mentioned food preservation cloth based on micro-nano mineral hydroxyl negative ions. The food preservation cloth is used for the preservation of fruits and vegetables, fresh meat, cooked food or seafood, and the application methods include directly wrapping food, cutting it into a specific shape to cover the surface of food, or making it into a food preservation bag or food preservation box liner.

[0041] The following data were obtained by comparing the food preservation cloths prepared in Examples 1-3 above:

[0042] As shown in the table above, the food preservation cloths prepared in Examples 1-3 all have good performance in terms of hydroxyl anion release, tensile strength, and elongation at break. After use, Example 2 has the best effect.

[0043] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A food preservation cloth based on micro / nano mineral hydroxyl anions, characterized in that, It includes a base layer (40), a functional layer (30), a sustained-release and accelerated-release layer (20), and a protective layer (10) arranged from bottom to top. The base layer (40) is a cotton-linen blend or bamboo fiber fabric with a basis weight of 80-120 g / m². 2 ; The raw materials of the functional layer (30) include, by weight: 20-40 parts of micro-nano mineral composite powder, 40-60 parts of water-based polyurethane emulsion, 2-4 parts of dispersant, 3-5 parts of toughening agent, 1-3 parts of antibacterial agent, and 10-20 parts of deionized water. The raw materials of the sustained-release and accelerated-release layer (20) include, by weight: 5-10 parts of chitosan / montmorillonite composite sustained-release agent, 20-30 parts of water-based acrylic emulsion, and 10-15 parts of deionized water. The protective layer (10) is a breathable and waterproof membrane with a breathability of 500-800 g / m³. 2 ·24h.

2. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, In the cotton-linen blended fabric of the base layer (40), the weight ratio of cotton fiber to linen fiber is 7:

3.

3. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, The micro-nano mineral composite powder is obtained by mixing tourmaline powder, tourmaline powder and diatomaceous earth powder in a weight ratio of 3:2:1 and then pulverizing them with airflow to a particle size of 50-200nm.

4. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, The dispersant is sodium polyacrylate or polyethylene glycol.

5. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, The toughening agent is epoxidized soybean oil or dibutyl phthalate.

6. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, The antibacterial adjuvant is nano silver powder or zinc oxide powder with a particle size of 20-50 nm.

7. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, The chitosan / montmorillonite composite sustained-release agent is obtained by mixing chitosan and montmorillonite in a weight ratio of 2:1, followed by ultrasonic dispersion, stirring reaction, drying and grinding to a particle size of 100-200 nm.

8. The food preservation cloth based on micro / nano mineral hydroxyl anions according to claim 1, characterized in that, The breathable and waterproof membrane is a polytetrafluoroethylene breathable membrane or a polyurethane breathable membrane.

9. A food preservation cloth based on micro / nano mineral hydroxyl anions and its application as described in claim 3, characterized in that, It also includes a preparation method, the specific steps of which are as follows: S1, Preparation of micro-nano mineral composite powder: Tourmaline powder, tourmaline powder and diatomaceous earth powder are mixed in proportion, put into an air jet mill, and pulverized under a pressure of 0.6-0.8MPa to obtain micro-nano mineral composite powder with a particle size of 50-200nm. S2, Preparation of functional slurry: Add dispersant to deionized water, stir evenly, then add micro-nano mineral composite powder, and disperse at high speed for 30-60 min at a speed of 2000-3000 r / min to obtain mineral dispersion; then add waterborne polyurethane emulsion, toughening agent and antibacterial agent to mineral dispersion, and continue stirring for 60-90 min to obtain functional slurry; S3, Composite Molding: The functional slurry is uniformly coated on one side surface of the base layer (40), with a coating amount of 20-30 g / m. 2 Dry at 80-100℃ for 15-20 min to obtain the base layer (40) of the composite functional layer (30). S4, Prepare and coat the sustained-release and accelerated-release slurry: Add chitosan / montmorillonite composite sustained-release agent to deionized water, stir and disperse at 1500-2000 r / min for 20-30 min, then add water-based acrylic emulsion and continue stirring for 30-40 min to obtain the sustained-release and accelerated-release slurry; coat it evenly on the surface of the functional layer (30), with a coating amount of 10-15 g / m 2 Dry at 70-80℃ for 15-20 minutes to form a slow-release and accelerated-release layer (20). S5, final composite: The protective layer (10) is composited onto the surface of the slow-release and accelerator layer (20), and then hot-pressed to obtain the finished food preservation cloth. The hot-pressing temperature is 130-140℃, the pressure is 0.3-0.5MPa, and the time is 3-5min.

10. An application of a food preservation cloth based on micro / nano mineral hydroxyl anions, characterized in that, The invention includes the food preservation cloth based on micro-nano mineral hydroxyl negative ions as described in claims 1-9. The food preservation cloth is used for the preservation of fruits and vegetables, fresh meat, cooked food or seafood, and the application methods include directly wrapping food, cutting it into a specific shape to cover the surface of food, or making it into a food preservation bag or food preservation box liner.

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